<PAGE>
                                                                   Exhibit 10.43
                                                                   -------------

THIS WARRANT AND THE SECURITIES ISSUABLE UPON THE EXERCISE HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
STATE SECURITIES LAWS.  THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED,
HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE ABSENCE OF A REGISTRATION STATEMENT
IN EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN EXEMPTION TO SUCH
ACT.

      Void After July 27, 2009 (the Tenth Anniversary of the Date Hereof)


                                WARRANT FOR THE
                      PURCHASE OF SHARES OF COMMON STOCK

                                      of

                            PARADIGM GENETICS INC.

          INCORPORATED UNDER THE LAWS OF THE STATE OF NORTH CAROLINA
          ----------------------------------------------------------

     THIS CERTIFIES THAT, for value received, ARE-104 Alexander Road, LLC, a
Delaware limited liability company, together with its successors and assigns
(the `Investor"), is initially entitled to purchase up to One Hundred Fifty
Thousand (150,000) duly authorized, validly issued, fully paid and nonassessable
shares of Common Stock (the "Common Stock") of Paradigm Genetics Inc., a North
Carolina corporation (the "Company"), at the per share purchase price described
in Section 1.3 below, subject to the provisions and upon the terms and
conditions hereinafter set forth.

     1.   Exercise of Warrant.  The terms and conditions upon which this Warrant
          -------------------
may be exercised, and the Common Stock covered hereby (the "Warrant Stock") may
be purchased, are as follows:

          1.1 Term. The purchase right represented by this Warrant may be
              ----
exercised in whole or in part at any time and from time to time from and after
the date hereof and on or before the earlier of (i) July 27, 2009 (the tenth
anniversary of the date hereof) or (ii) the fifth anniversary of the date of the
consummation of a bona fide, underwritten initial public offering of Common
Stock, at a public offering price equal to or exceeding $10.00 per share (as
adjusted for any stock dividends, combinations, splits or the like with respect
to such shares) and an aggregate offering price to the public of not less than
$20,000,000; provided that, if the last day on which this Warrant may be
exercised is a Sunday or a legal holiday or a day on which banking institutions
doing business in the State of North Carolina are authorized by law to close,
this Warrant may be exercised prior to 5:00 p.m. local time) on the next
succeeding full business day with the same force and effect as if exercised on
such last day specified herein.
<PAGE>

          1.2  Number of Shares.  This Warrant is initially exercisable for One
               ----------------
Hundred Fifty Thousand (150,000) shares of Common Stock, subject to adjustment
pursuant to Section 2 of this Warrant.

          1.3 Purchase Price. The initial per share purchase price for the
              --------------
shares of Common Stock to be issued upon exercise of this Warrant shall be
$3.00, subject to adjustment as provided herein (the "Warrant Price").

          1.4 Method of Exercise. The exercise of the purchase rights evidenced
              ------------------
by this Warrant shall be effected by (a) the surrender of the Warrant, together
with a duly executed copy of the form of a subscription attached hereto, to the
Company at its principal offices and (b) the delivery of the purchase price (i)
by check or bank draft payable to the Company's order or by wire transfer to the
Company's account for the number of shares for which the purchase rights
hereunder are being exercised or (ii) pursuant to the procedure set forth in
Section 1.5. Any such exercise of this Warrant may be made contingent upon the
closing of a public offering, merger, recapitalization or similar transaction.

          Each exercise of this Warrant shall be deemed to have been effected
immediately prior to the close of business on the day on which this Warrant
shall have been surrendered to the Company as provided herein or at such latter
date as may be specified in the executed form of subscription, and at such time
the person or persons in whose name or names any certificate or certificates for
shares of Common Stock shall be issuable upon such exercise as provided herein
shall be deemed to have become the holder or holders of record thereof.

          1.5  Cashless Exercise.  In addition to and without limiting the
               -----------------
rights of the holder hereof under the terms hereof, at the holder's option this
Warrant may be exercised in whole or in part at any time or from time to time
prior to its expiration for a number of shares of Common Stock having an
aggregate fair market value on the date of such exercise equal to the difference
between (a) the fair market value of the number of shares of Common Stock
subject to this Warrant designated for exercise by the holder hereof on the date
of the exercise and (b) the aggregate Warrant Price for such shares in effect at
such time.

          The "fair market value" of shares of Common Stock shall be calculated
on the basis of (a) if the Common Stock is then traded on a securities exchange
or the Nasdaq National Market, the average of the closing prices of the Common
Stock on such exchange or market over the 20 trading day period ending three (3)
trading days prior to the date of exercise, (b) if the Common Stock is then
regularly traded over-the-counter, the average of the sale prices or secondarily
the closing bid of the Common Stock over the 20 trading day period ending three
(3) trading days prior to the date of exercise, or (c) if there is no active
public market for the Common Stock, the fair market value thereof shall be the
price per share that the Company could obtain from a willing buyer for shares
sold by the Company from authorized but unissued shares, as determined in good
faith by the Company's Board of Directors. If the holder of this Warrant
exercises this Warrant contingent upon the closing of a public offering, the
"fair market value" of a share of Common Stock on the date of exercise shall be
equal to the initial price to the public specified in the final prospectus with
respect to such public offering.

                                       2
<PAGE>

          No payment of any cash or other consideration to the Company shall be
required from the holder of this Warrant in connection with any exercise of this
Warrant pursuant to this Section 1.5.  Such exercise shall be effective upon the
date of receipt by the Company of the original Warrant surrendered for
cancellation and a written request from the holder hereof that the exercise
pursuant to this Section 1.5 be made, or at such later date as may be specified
in such request.

          1.6  Issuance of Shares.  As soon as reasonably practicable after each
               ------------------
exercise of this Warrant, in whole or in part, the Company at its expense
(including the payment by it of any applicable issue taxes) will cause to be
issued in the name of and delivered to the holder hereof or as such holder (upon
payment by such holder of any applicable transfer taxes) may direct, (a) a
certificate or certificates for the number of duly authorized, validly issued,
fully paid and nonassessable shares of Common Stock to which such holder shall
be entitled upon such exercise, and (b) in case such exercise is in part only, a
new Warrant or Warrants of like tenor, calling in the aggregate on the face or
faces thereof for the number of shares of Common Stock equal (without giving
effect to any adjustment thereof) to the number of such shares called for on the
face of this Warrant minus the number of such shares designated by the holder
upon such exercise as provided herein.

     2.  Certain Adjustments.
         -------------------

         2.1 Mergers Consolidations or Sale of Assets. If after the date hereof
             ----------------------------------------
there shall be a capital reorganization (other than a combination or subdivision
of Common Stock otherwise provided for herein), or spin-off, or a merger or
consolidation of the Company with or into another corporation, or the sale of
all or substantially all of the Company's properties and assets to any other
person, then, as a part of such transaction, lawful provision shall be made so
that the Investor shall thereafter be entitled to receive upon exercise of this
Warrant, during the period specified in this Warrant and upon payment of the
purchase price, the number of shares of stock or other securities, cash or
property of the Company or the successor corporation resulting from such
transaction, to which a holder of the Common Stock deliverable upon exercise of
this Warrant would have been entitled under the provisions of the agreement in
such transaction if this Warrant had been exercised immediately before such
transaction. In any such case, appropriate adjustment (as determined reasonably
and in good faith by the Company's Board of Directors) shall be made in the
application of the provisions of this Warrant with respect to the rights and
interests of the Investor after such transaction to the end that the provisions
of this Warrant (including adjustment of the purchase price then in effect and
the number of shares of Common Stock issuable upon exercise hereof) shall
applicable after that event, as near as reasonably may be, in relation to any
shares or other property deliverable after that event upon exercise of this
Warrant.

          2.2 Splits and Subdivisions Dividends. If the Company should effect or
              ---------------------------------
fix a record date for the effectuation of a split or subdivision of the
outstanding shares of Common Stock or the determination of the holders of Common
Stock entitled to receive a dividend or other distribution payable in additional
shares of Common Stock or other securities or warrants, options or other rights
convertible into, or entitling the holder thereof to receive directly or
indirectly, additional shares of Common Stock (hereinafter referred to as
"Common Stock

                                       3
<PAGE>

Equivalents") without payment of any consideration by such holder
for the additional shares of Common Stock or Common Stock Equivalents (including
the additional shares of Common Stock issuable upon conversion or exercise
thereof), then, as of such record date (or the date of such distribution, split
or subdivision if no record date is fixed), the per share purchase price shall
be appropriately decreased and the number of shares of Common Stock issuable
upon exercise hereof shall be appropriately increased in proportion to such
increase of outstanding shares.

          2.3  Combination of Shares.  If the number of shares of Common Stock
               ---------------------
outstanding at any time after the date hereof is decreased by a combination of
the outstanding shares of Common Stock, the per share purchase price shall be
appropriately increased and the number of shares of Common Stock issuable upon
exercise hereof shall be appropriately decreased in proportion to such decrease
in outstanding shares.

          2.4  Adjustments for Other Distributions.  In the event the Company
               -----------------------------------
shall declare a distribution payable in securities of the Company (other than
Common Stock Equivalents) or other persons, evidences of indebtedness issued by
the Company or other persons, assets (including cash dividends) or options or
rights not referred to in Section 2.2, then, in each such case for purposes of
this Section 2.4, upon exercise of this Warrant the holder hereof shall be
entitled to a proportionate share of any such distribution as though such holder
was the holder of the number of shares of Common Stock of the Company into which
this Warrant may be exercised as of the record date fixed for the determination
of the holders of Common Stock of the Company entitled to receive such
distribution.

          2.5  Issuance of Additional Common Stock
               -----------------------------------

               (a) If, after the date hereof, the Company shall issue or sell

                   (ii) Additional Shares (defined below) without consideration
                    or for a consideration per share less than the Warrant
                    Price, or

                   (ii) Common Stock Equivalents exercisable for Additional
                    Shares with a minimum exercise or exchange price less than
                    the Warrant Price, or

then, and in each such case, the Warrant Price shall be reduced, concurrently
with such issue or sale, to a price (calculated to the nearest .001 of a cent)
determined by multiplying such Warrant Price by a fraction:

                   (i) the numerator of which shall be (A) the number of shares
                   of Common Stock outstanding immediately prior to such issue
                   or sale plus (B) the number of shares of Common Stock that
                   the aggregate consideration received by the Company upon such
                   issuance or sale (or, in the case of Common Stock Equivalents
                   exercisable for Additional Shares, receivable by the Company

                                       4
<PAGE>

                   upon exercise or exchange) would purchase at
                   such Warrant Price, and

                   (ii) the denominator of which shall be the number of shares
                   of Common Stock outstanding immediately after such issue or
                   sale (or, in the case of Common Stock Equivalents
                   exercisable for Additional Shares, assuming exercise or
                   exchange thereof).

          (b) For the purposes of this Section 2.5, the consideration for the
issue or sale of Additional Shares shall, irrespective of the accounting
treatment of such consideration, (i) insofar as it consists of cash, be computed
at the net amount of cash received by the Company, and (ii) insofar as it
consists of property (including securities) other than cash, be computed at the
fair value thereof at the time of such issue or sale as determined in good faith
by the Board of Directors.

          (c) Notwithstanding anything contained herein to the contrary, the
consideration for any Common Stock Equivalents shall be the total amount of
consideration received by the Company for the issuance of such Common Stock
Equivalents plus the minimum amount of consideration payable to the Company upon
exercise, conversion or exchange of Common Stock Equivalents (the "Net
Consideration") determined as of the date of issuance of such Common Stock
Equivalents.  Any obligation, agreement or understanding to issue Common Stock
Equivalents at any time in the future shall be deemed to be an issuance at the
time such obligation or agreement is made or arises.  No adjustment of the
Warrant Price shall be made under this Section 2.5 upon the issuance of any
shares of Common Stock which are issued pursuant to the exercise, conversion or
exchange of any Common Stock Equivalents if any adjustment shall previously have
been made upon the issuance of any such Common Stock Equivalents.

          Should the Net Consideration for any such Common Stock Equivalents be
increased or decreased from time to time, then, upon the effectiveness of such
change, the Warrant Price will be that which would have been obtained (i) had
the adjustments made upon the issuance of such Common Stock Equivalents been
made upon the basis of the actual Net Consideration (as so increased or
decreased) of such Common Stock Equivalents, and (ii) had adjustments to such
Warrant Price since the date of issuance of such Common Stock Equivalents been
made to such Warrant Price as adjusted pursuant to (i) above.  Any adjustment of
the Warrant Price with respect to this paragraph which relates to Common Stock
Equivalents shall be disregarded if, as, and when all of such Common Stock
Equivalents expire or are canceled without being exercised, so that the Warrant
Price effective immediately upon cancellation or expiration shall be equal to
the Warrant Price in effect at the time of the issuance of the expired or
canceled Common Stock Equivalents, with such additional adjustments as would
have been made to such Warrant Price had the expired or canceled Common Stock
Equivalents not been issued.

          (d) "Additional Shares" means all shares of Common Stock, whether or
not subsequently reacquired or retired by the Company other than shares of
Common Stock issued or to be issued to directors, officers, employees and
consultants of the Company or any

                                       5
<PAGE>

subsidiary pursuant to any bona fide qualified or non-qualified stock option
plan or agreement, stock purchase plan or agreement, stock restriction
agreement, employee stock ownership plan (ESOP) or other stock incentive plans
or arrangements.

          (e) The number of shares of Common Stock that the holder of this
Warrant shall be entitled to receive upon each exercise hereof after any
adjustment pursuant to this Section 2.5 shall be determined by multiplying (i)
the number of shares of Common Stock that were issuable immediately prior to
such adjustment, by (ii) the fraction of which (A) the numerator is the Warrant
Price immediately prior to such adjustment and (B) the denominator is the
Warrant Price immediately following such adjustment.

          2.6  Certificate as to Adjustments.  In the case of each adjustment or
               -----------------------------
readjustment of the Warrant Price pursuant to this Section 2, the Company at its
expense will promptly compute such adjustment or readjustment in accordance with
the terms hereof and cause a certificate, signed by the Company's Chief
Financial Officer, setting forth such adjustment or readjustment and showing in
detail the facts upon which such adjustment or readjustment is based to be
delivered to the holder of this Warrant.  The Company will furnish or cause to
be furnished to such holder a certificate setting forth (a) such adjustments and
readjustments, (b) the Warrant Price at the time in effect and how it was
calculated and (c) the number of shares of Common Stock issuable upon exercise
hereof and the amount, if any, of other property at the time receivable upon the
exercise of the Warrant.

          2.7  Other Dilutive Events.  If any event shall occur as to which the
               ---------------------
provisions of Section 2 are not strictly applicable but the failure to make any
adjustment would not fairly protect the purchase rights represented by this
Warrant in accordance with the essential intent and principles of such sections,
then, in each such case, the Board of Directors of the Company shall make such
adjustment, if any, on a basis consistent with the essential intent and
principles established in Section 2, necessary to preserve, without dilution,
the purchase rights represented by this Warrant.  The Company will promptly
notify the Investor of any such adjustments and shall make the suggested
adjustments.

          2.8  No Dilution or Impairment.  The Company will not, by amendment of
               -------------------------
its certificate of incorporation or through any consolidation, merger,
reorganization, transfer of assets, dissolution, issue or sale of securities or
any other voluntary action, avoid or seek to avoid the observance or performance
of any of the terms of this Warrant, but will at all times in good faith assist
in the carrying out of all such terms and in the taking of all such action as
may be necessary or appropriate in order to protect the rights of the holder of
this Warrant against dilution or other impairment.

     Without limiting the generality of the foregoing, the Company (a) will not
permit the par value of any shares of stock receivable upon the exercise of this
Warrant to exceed the amount payable therefor upon such exercise, (b) will take
all such action as may be necessary or appropriate in order that the Company may
validly and legally issue fully paid and nonassessable shares of stock on the
exercise of the Warrants from time to time outstanding; and (c) will not take
any action which results in any adjustments of the Warrant Price if the total
number of shares of Common Stock issuable after the action upon the exercise of
all of the Warrants would

                                       6
<PAGE>

exceed the total number of shares of Common Stock then authorized by the
Company's certificate of incorporation and available for the purpose of issue
upon such exercise.

          2.9  Notices of Record Date etc.  In the event of:
               --------------------------

               (a) any taking by the Company of a record of the holders of any
class of securities of the Company for the purpose of determining the holders
thereof who are entitled to receive any dividend (other than a cash dividend
payable out of earned surplus at the same rate as that of the last such cash
dividend theretofore paid) or other distribution, or any right to subscribe for,
purchase or otherwise acquire any shares of stock of any class or any other
securities or property, or to receive any other right;

               (b) any capital reorganization of the Company, any
reclassification or recapitalization of the capital stock of the Company or any
transfer of all or substantially all of the assets of the Company to any other
person or any consolidation or merger involving the Company; or

               (c) any voluntary or involuntary dissolution, liquidation or
winding-up of the Company,

the Company will mail to the holder of this Warrant at least thirty (30) days
prior to the earliest date specified below, a notice specifying: (i) the date on
which any such record is to be taken for the purpose of such dividend,
distribution or right, and the amount and character of such dividend,
distribution or right; and (ii) the date on which any such reorganization,
reclassification, transfer, consolidation, merger, dissolution, liquidation or
winding-up is expected to become effective and the record date for determining
stockholders entitled to vote thereon and the time, if any such time is to be
fixed, as of which the holders of record of Common Stock shall be entitled to
exchange their shares of Common Stock for the securities or other property
deliverable upon such reorganization, reclassification, recapitalization,
consolidation, merger, transfer, dissolution, liquidation or winding-up.

     3.  Fractional Shares.  No fractional shares shall be issued in connection
         -----------------
with any exercise of this Warrant.  In lieu of the issuance of such fractional
share, the Company shall make a cash payment equal to the then fair market value
of such fractional share as determined in accordance with Section 1.5 hereof.

     4.  Representations and Warranties of the Company.
         ---------------------------------------------

         4.1  Authorization.  The Company has full power and authority to enter
              -------------
into this Warrant.  This Warrant has been duly authorized, executed and
delivered by the Company and constitutes its valid and legally binding
obligation, enforceable in accordance with its terms.

          4.2  Reservation of Common Stock.  The Company shall at all times
               ---------------------------
reserve and keep available out of its authorized but unissued shares of Common
Stock, solely for the purpose of effecting the exercise of this Warrant, such
number of its shares of Common Stock, free from preemptive rights, as shall from
time to time be sufficient to effect the exercise of this

                                       7
<PAGE>

Warrant, and if at any time the number of authorized but unissued shares of
Common Stock shall not be sufficient to effect the exercise of the entire
Warrant, in addition to such other remedies as shall be available to the holder
of this Warrant, the Company will take such action as may be necessary to
increase its authorized but unissued shares of Common Stock to such number of
shares as shall be sufficient for such purposes. If any shares of its Common
Stock to be reserved for the purpose of issuance upon exercise of the Warrants
require registration with or approval of any governmental authority under any
applicable law (other than registration of the Common Stock under the Act)
before such shares of Common Stock may be validly issued or delivered, then it
shall secure such registration or approval, as the case may be, and maintain
such registration or approval in effect so long as so required.

          4.3  Adjustment in Number of Shares Issuable and Purchase Price.
               ----------------------------------------------------------
There has not been nor will there be any adjustment to the number of shares
issuable or the purchase price payable upon the exercise of any securities of
the Company convertible into or exchangeable for shares of Common Stock
resulting from the issuance or exercise of this Warrant.

          4.4  Valid Issuance.  This Warrant, when issued and delivered in
               --------------
accordance with the terms hereof will be duly authorized and validly issued, and
the Common Stock issuable upon the exercise hereof, when issued pursuant to the
terms hereof and upon payment of the exercise price, shall, upon such issuance,
be duly authorized, validly issued, fully paid and nonassessable.

     5.  Privilege of Stock Ownership.  Prior to the exercise of this Warrant,
         ----------------------------
the Investor shall not be entitled, by virtue of holding this Warrant, to any
rights of a stockholder of the Company, including (without limitation) the right
to vote, receive dividends or other distributions, exercise preemptive rights or
be notified of stockholder meetings, and such holder shall not be entitled to
any notice or other communication concerning the business or affairs of the
Company.  Nothing in this Section 5, however, shall limit the right of the
Investor to be provided the notices described in Section 2 hereof or to
participate in distributions described in Section 2 hereof if the Investor
ultimately exercises this Warrant.

     6.  Limitation of Liability.  Except as otherwise provided herein, in the
         -----------------------
absence of affirmative action by the holder hereof to purchase the Common Stock
in accordance herewith, no mere enumeration herein of the rights or privileges
of the holder hereof shall give rise to an obligation on such holder to purchase
any securities or any liability of such holder for the purchase price or as a
stockholder of the Company, whether such obligation or liability is asserted by
the Company or by creditors of the Company.

     7.  Representations and Warranties of the Investor.  The Investor
         ----------------------------------------------
represents and warrants to the Company as follows:

          7.1  Investment Experience.  The Investor represents that it can bear
               ---------------------
the economic risk of its investment and has such knowledge and experience in
financial or business matters that it is capable of evaluating the merits and
risks of the investment in the Warrant and the Common Stock issuable upon
exercise hereof.  The Investor also represents it has not been

                                       8
<PAGE>

organized solely for the purpose of acquiring the Warrant or the Common Stock
issuable upon exercise hereof.

          7.2  Restricted Securities.  The Investor understands that the Warrant
               ---------------------
being issued hereunder and the Common Stock issuable upon exercise hereof are
characterized as "restricted securities" under the federal securities laws
inasmuch as they are being acquired from the Company in a transaction not
involving a public offering and have not been registered under the Act nor
qualified under applicable state securities laws and that under such laws and
applicable regulations such securities may not be resold without registration
under the Act, except in certain limited circumstances.  In this connection, the
Investor represents that it is familiar with Rule 144 promulgated under the Act
("Rule 144"), as presently in effect, and understands the resale limitations
imposed thereby and by the Act.

          7.3  Accredited Investor.  The Investor is an "accredited investor"
               -------------------
within the meaning of Rule 501 of Regulation D promulgated under the Act.

          7.4  Legends.  It is understood that the certificates evidencing the
               -------
Common Stock issuable upon exercise hereof may bear the following legend:

     "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
     1933, AS AMENDED, OR ANY STATE SECURITIES LAWS.  THEY MAY NOT BE SOLD,
     OFFERED FOR SALE, PLEDGED, HYPOTHECATED OR OTHERWISE TRANSFERRED IN THE
     ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE
     SECURITIES UNDER SUCH ACT OR AN EXEMPTION TO SUCH ACT"

     8.  Transfers and Exchanges.
         -----------------------

          8.1  The Investor agrees not to sell, hypothecate, pledge or otherwise
dispose of any interest in the Warrant or the Common Stock issuable upon
exercise hereof in the United States, its territories, possessions or any area
subject to its jurisdiction, or to any person who is a national thereof or
resident therein (including any estate of such person), or any corporation,
partnership or other entity created or organized therein, other than in
accordance with the Act.  With respect to any offer, sale or other disposition
of this Warrant, or any shares of Common Stock acquired pursuant to the exercise
of this Warrant prior to registration of such shares, the holder hereof and each
subsequent holder of the Warrant agrees to give written notice to the Company
prior thereto, describing briefly the manner thereof, together with a written
opinion of such holder's counsel, if reasonably requested by the Company, to the
effect that such offer, sale or other disposition may be effected without
registration or qualification (under the Act as then in effect or any federal or
state law then in effect) of this Warrant or such shares of Common Stock and
indicating whether or not under the Act certificates for this Warrant or such
shares of Common Stock to be sold or otherwise disposed of require any
restrictive legend as to applicable restrictions on transferability in order to
insure compliance with the Act; provided, however, that the holder may transfer
or assign this Warrant, or any shares of Common Stock acquired pursuant to the
exercise of this Warrant prior to registration of such shares to Alexandria Real
Estate Equities, Inc., a Maryland corporation ("Alexandria") or to another
wholly-owned

                                       9
<PAGE>

subsidiary of Alexandria without written notice to the Company or an opinion of
holder's counsel. Each certificate representing this Warrant or the shares of
Common Stock thus transferred (except a transfer pursuant to Rule 144) shall
bear a legend as to the applicable restrictions on transferability in order to
insure compliance with the Act, unless in the aforesaid opinion of counsel for
the holder, such legend is not required in order to insure compliance with the
Act. The Company may issue stop transfer instructions to its transfer agent in
connection with the foregoing restrictions.

          8.2  Upon presentation to the Company of the form of Assignment
attached hereto, a new Warrant shall be issued to the new holder hereof.  New
Warrants issued in connection with transfers or exchanges shall not require the
signature of the new holder hereof and shall be identical in form and provision
to this Warrant except as to the number of shares.

          8.3  Each certificate evidencing the shares of Common Stock issued
upon exercise of this Warrant, or upon any transfer of such shares (other than a
transfer registered under the Act or any subsequent transfer of shares so
registered) shall, at the option of the Company, contain a legend, in form and
substance reasonably satisfactory to the Company and its counsel, restricting
the transfer of such shares to sales or other dispositions exempt from the
requirements of the Act.

          8.4  Ownership of Warrants.  The Company may treat the person in whose
               ---------------------
name any Warrant is registered on the register kept at the office of the Company
as the owner and holder thereof for all purposes, notwithstanding any notice to
the contrary, except that, if and when any Warrant is properly assigned in
blank, the Company may (but shall not be obligated to) treat the bearer thereof
as the owner of such Warrant for all purposes, notwithstanding any notice to the
contrary.  A Warrant, if properly assigned, may be exercised by a new holder
without a new Warrant first having been issued.

          8.5  Transfer and Exchange of Warrants.  Upon the surrender of any
               ---------------------------------
Warrant, properly endorsed, for registration of transfer or for exchange, the
Company at its expense will execute and deliver to or upon the order of the
holder thereof a new Warrant or Warrants of like tenor, in the name of such
holder or as such holder (upon payment by such holder of any applicable transfer
taxes) may direct, calling in the aggregate on the face or faces thereof for the
number of shares of Common Stock called for on the face or faces of the Warrant
or Warrants so surrendered.

     9.  Successors and Assigns.  The terms and provisions of this Warrant shall
         ----------------------
be binding upon the Company and the Investor and their respective successors and
assigns, subject at all times to the restrictions set forth herein.

     10.  Loss, Theft, Destruction or Mutilation of Warrant.  Upon receipt by
          -------------------------------------------------
the Company of evidence reasonably satisfactory to it of the loss, theft,
destruction or mutilation of this Warrant, and in case of loss, theft or
destruction, of indemnity or security reasonably satisfactory to the Company,
and upon reimbursement to the Company of all reasonable expenses incidental
thereto, and upon surrender and cancellation of this Warrant, if mutilated, the
Company will

                                       10
<PAGE>

make and deliver a new warrant of like tenor and dated as of such cancellation,
in lieu of this Warrant.

     11.  Saturdays, Sundays, Holidays.  etc.  If the last or appointed day for
          ----------------------------------
the taking of any action or the expiration of any right required or granted
herein shall be a Saturday or Sunday or shall be a legal holiday, then such
action may be taken or such right may be exercised on the next succeeding day
not a legal holiday.

     12.  Amendments and Waivers.  Any term of this Warrant may be amended and
          ----------------------
the observance of any term of this Warrant may be waived (either generally or in
a particular instance and either retroactively or prospectively), only with the
written consent of the Company and the Investor.  Any such amendment or waiver
shall be binding on the parties.

     13.  Governing Law.  The terms and conditions of this Warrant shall be
          -------------
governed by and construed in accordance with North Carolina law, without regard
to conflict of law provisions.

     14.  Notices.  Except as otherwise provided in this Warrant, any
          -------
requirement for a notice, demand or request under this Warrant will be satisfied
by a writing (a) hand delivered with receipt; (b) mailed by United States
registered or certified mail or Express Mail, return receipt requested, postage
prepaid; or (c) sent by Federal Express or any other nationally recognized
overnight courier service, and addressed as follows: if to the holder, at its
address as shown on the books of the Company; and if to the Company, at the
address indicated on the signature page of this Warrant, Attn:  Chief Financial
Officer, with a copy to Gerald F. Roach, Esq., Smith, Anderson, Blount, Dorsett,
Mitchell & Jernigan, L.L.P., 2500 First Union Capital Center, Raleigh, North
Carolina 27601.  All notices that are sent in accordance with this Section 14
will be deemed received by the holder or the Company on the earliest of the
following applicable time periods: (i) the date the return receipt is executed;
or (ii) the date delivered as documented by the overnight courier service or the
hand delivery receipt.  Either the holder or the Company may designate a change
of address by written notice to the other party.

     15.  Registration Rights.
          -------------------

          (a) The shares of Common Stock issued or issuable upon the exercise
hereof shall constitute "Registrable Securities" for purposes of this Warrant;
provided, that Registrable Securities shall not include any shares of Common
Stock that have been sold to the public either pursuant to a registration
statement or the exemption from registration under the Securities Act provided
by Rule 144.

          (b) If at any time the Company proposes to file a registration
statement under the Act with respect to an offering of equity securities by the
Company for its own account or for the account of any securityholders of any
class of its equity securities (other than (i) a registration statement on Form
S-4 or S-8 (or any substitute form that may be adopted by the Securities and
Exchange Commission (the "Commission")) or (ii) a registration statement filed
in connection with an exchange offer or offering of securities solely to the
Company's existing securityholders) or a registration on any registration form
that does not permit secondary sales,

                                       11
<PAGE>

then the Company shall give written notice of such proposed filing to the
Investor as soon as practicable (but in no event less than 20 days before the
anticipated filing date), and such notice shall offer such Investor the
opportunity to register such number of shares of Registrable Securities as each
such Investor may request in writing within 15 days after such notice from the
Company (which request shall specify the Registrable Securities intended to be
disposed of and the intended method of distribution thereof) (a "Piggy-Back
Registration").

          The Company shall use its best efforts to cause the managing
Underwriter or Underwriters of a proposed underwritten public offering to permit
the Registrable Securities requested by the Investor thereof to be included in a
Piggy-Back Registration on the same terms and conditions as any similar
securities of the Company or any other securityholder included therein and to
permit the sale or other disposition of such Registrable Securities in
accordance with the intended method of distribution thereof. The Investor shall
have the right to withdraw its request for inclusion of its Registrable
Securities in any registration statement pursuant to this Section 15 by giving
written notice to the Company of its request to withdraw. The Company may
withdraw a Piggy-Back Registration at any time prior to the time it becomes
effective; provided that the Company shall reimburse the Investor for all
reasonable out-of-pocket expenses (including counsel fees and expenses) incurred
prior to such withdrawal. Notwithstanding the foregoing, if the representative
of the underwriters advises the Company in writing that market factors require a
limitation on the number of shares to be underwritten, the representative may
reduce the number of Registrable Securities to be included in the registration
and underwriting (to zero, if necessary) on a pro rata basis (based on number of
shares owned) with all other secondary shares sought to be included therein.

          No failure to effect a registration under Section 15(b) and to
complete the sale of Registrable Securities in connection therewith shall
relieve the Company of any other obligation under this Agreement (-including,
without limitation, the Company's obligations under Sections 15(d) and 15(e)).

              (c) In the case of a Piggy-Back Registration:

                  (1) The Company will, as expeditiously as possible:

                      (A) prepare and file with the Commission such amendments
and post-effective amendments to the applicable registration statement as may be
necessary to keep the registration statement effective for as long as such
registration is required to remain effective pursuant to the terms hereof, cause
the prospectus to be supplemented by any required prospectus supplement, and, as
so supplemented, to be filed pursuant to Rule 424 under the Act;

                      (B) furnish to the Investor at least one signed copy of
the registration statement and any post-effective amendment thereto, as soon as
such documents become available to the Company, and such number of conformed
copies thereof and such number of copies of the prospectus (including each
preliminary prospectus) and any amendments or supplements thereto, and any
documents incorporated by reference therein, as the Investor may reasonably
request as soon as such documents become available to the Company;

                                       12
<PAGE>

                      (C) on or prior to the date on which the registration
statement is declared effective, qualify such Registrable Securities requested
to be included under such other securities or blue sky laws of such
jurisdictions as the Investor reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable the Investor
to consummate the disposition in such jurisdictions of such Registrable
Securities; provided, that the Company will not be required to (i) qualify
generally to do business in any jurisdiction where it would not otherwise be
required to qualify, (ii) subject itself to general taxation in any such
jurisdiction or (iii) consent to general service of process in any such
jurisdiction;

                      (D) notify the Investor at any time when a prospectus
relating to such Registrable Securities is required to be delivered under the
Act of the happening of any event as a result of which the prospectus included
in such registration statement contains an untrue statement of a material fact
or omits to state any material fact required to be stated therein or necessary
to make the statements therein not misleading, and prepare a supplement or
amendment to such prospectus so that, as thereafter delivered to the purchasers
of such Registrable Securities, such prospectus will not contain an untrue
statement of a material fact or omit to state any material fact required to be
stated therein or necessary to make the statements therein not misleading;

                      (E) notify the Investor of any stop order or other
suspension. of effectiveness of the registration statement; and obtain the
withdrawal of any order suspending the effectiveness of the registration
statement at the earliest possible time.

                      (F) enter into such agreements (including an underwriting
agreement in form, scope and substance as is customary in underwritten
offerings) and take all such other actions in connection therewith (including
those requested by the managing underwriters, if any, or the Investor) in order
to expedite or facilitate the disposition of such Registrable Securities and in
such connection, whether or not an underwriting agreement is entered into and
whether or not the registration is an underwritten registration, (i) make such
representations and warranties to the Investor and the underwriters, if any,
with respect to the business of the Company and its subsidiaries, the
registration statement, prospectus and documents incorporated by reference or
deemed incorporated by reference, if any, in each case, in form, substance and
scope as are customarily made by issuers to underwriters in underwritten
offerings and confirm the same if and when requested; (ii) obtain opinions of
counsel to the Company and updates thereof (which counsel and opinions in form,
scope and substance) shall be reasonably satisfactory to the managing
underwriters, if any, and the Investor addressed to the Investor and each of the
underwriters, if any, covering the matters customarily covered in opinions
requested in underwritten offerings and such other matters as may be reasonably
requested by such holders and underwriters, including without limitation the
matters referred to clause (i) above; (iii) obtain "cold comfort" letters and
updates thereof from the independent certified public accountants of the Company
(and, if necessary, any other certified public accountants of any subsidiary of
the Company or of any business acquired by the Company for which financial
statements and financial data is, or is required to be, included in the
registration statement), addressed to the Investor and each of the underwriters,
if any, such letters to be in

                                       13
<PAGE>

customary form and covering matters of the type customarily covered in "cold
comfort" letters in connection with underwritten offerings; and (iv) deliver
such documents and certificates as may be requested by the Investor, its counsel
and the managing underwriters, if any, to evidence the continued validity of the
representations and warranties of the Company and its subsidiaries made pursuant
to clause (i) above and to evidence compliance with any customary conditions
contained in the underwriting agreement or other agreement entered into by the
Company; and notify the Investor promptly of the receipt by the Company of any
notification with respect to the suspension of the qualification of the Warrant
and/or Common Stock for sale in any jurisdiction; and

                      (G) take all other steps reasonably necessary to effect
the registration of the Registrable Securities contemplated hereby.

               (2) The Company will otherwise use its best efforts to comply
with all applicable rules and regulations of the Commission, and make available
to its securityholders, as soon as reasonably practicable, an earnings statement
covering a period of 12 months, beginning within three months after the
effective date of the registration statement, which earnings statement shall
satisfy the provisions of Section 11(a) of the Act.

               (3) The Company will use its best efforts (i) to cause any class
of Registrable Securities to be listed on a national securities exchange (if
such shares are not already so listed) and on each additional national
securities exchange on which similar securities issued by the Company are then
listed (if any), if the listing of such Registrable Securities is then permitted
under the rules of such exchange or (ii) to secure designation of all such
Registrable Securities covered by such registration statement as a NASDAQ
"national market system security" within the meaning of Rule 1lAa2-1 of the
Commission or, failing that, to secure NASDAQ authorization for such Registrable
Securities.

          (d) The Company shall keep effective and maintain any registration,
qualification, approval or listing specified in this Section 15 for a period of
180 days plus the term of any lock-up or until the holders have completed the
distribution described in the registration statement, whichever occurs first,
and from time to time shall amend or supplement the prospectus used in
connection therewith to the extent necessary in order to comply with applicable
law.  All expenses, disbursements and fees in connection with any action to be
taken hereunder (including, without limitation, all registration and filing
fees, fees and expenses of compliance with securities or blue sky laws, printing
expenses and fees and expenses of counsel for the Company and its independent
certified public accountants and all reasonable fees and expenses of the
Investor and one Investor's counsel and appropriate local counsel (all such
expenses being herein called "Registration Expenses") will be borne by the
Company; provided that in no event shall Registration Expenses include any
underwriting discounts, sales commissions or similar fees or transfer taxes
attributable to the sale of Registrable Securities.

          (e) The rights to cause the Company to register securities granted to
a holder under this Section 15 may be transferred or assigned by a holder only
to (i) an affiliate of such holder or (ii) a transferee or assignee of not less
than 20% of such holder's Registrable Securities (as determined on the date of
this Warrant and subject to subsequent adjustments for

                                       14
<PAGE>

stock splits, stock dividends, reverse stock splits, and the like), provided
that, in either case (A) the Company is given written notice at the time of or
within 30 days after transfer or assignment, stating the name and address of the
transferee or assignee and identifying the securities with respect to which such
registration rights are being transferred or assigned, (B) the transferee or
assignee of such rights assumes in writing the obligations of such holder under
this Section 15 and (C) in the reasonable opinion of the Company, the transferee
is neither a competitor to the Company nor a party who is demonstrably hostile
to the Company.

          (f) If requested by the Company and an underwriter of Common Stock (or
other securities) of the Company, an Investor shall not sell or otherwise
transfer or dispose of any Common Stock (or other securities) of the Company
held by such Investor (other than those included in the registration) during a
period not to exceed 180 days following the effective date of a registration
statement of the Company filed under the Securities Act, provided that all
officers and directors of the Company and holders of at least five percent of
the Company's voting securities are bound by and have entered into similar
agreements.  The Company may impose stop-transfer instructions with respect to
the shares of Common Stock (or other securities) subject to the foregoing
restriction until the end of such 180 day period.

          (g) The holders under this Warrant agree that, upon receipt of any
notice from the Company of the existence of any state of facts or the occurrence
of any event (including, without limitation, pending negotiations relating to,
or the consummation of, a transaction or the occurrence of any event which, in
the reasonable opinion of the Company, might require additional disclosure of
material, non-public information by the Company in any registration statement
provided for in this Warrant as to which the Company believes in good faith that
it has a bona fide business purpose for preserving confidentiality or which
renders the Company unable to comply with the published rules and regulations of
the Commission promulgated under the Securities Act or the Exchange Act, as in
effect at any relevant time) which might reasonably result in (A) such
registration statement, any amendment or post-effective amendment thereto, or
any document incorporated therein by reference containing an untrue statement of
a material fact or omitting to state a material fact required to be stated
therein or necessary to make the statements therein not misleading, or (B) the
prospectus issued under such registration statement, any prospectus supplement,
or any document incorporated therein by reference including an untrue statement
of material fact or omitting to sate a material fact necessary in order the make
the statements therein, in light of the circumstances under which they were
made, not misleading, the holders will forthwith discontinue disposition of the
Registrable Securities pursuant to such registration statement for a period
which is the shorter of (i) 30 calendar days from the Company's notice to such
holders or (ii) until the holders receive copies of prospectus supplements or
amendments prepared by or on behalf of the Company.  If so directed by the
Company, the holders will deliver to the Company all copies in their possession
of the prospectus covering such Registrable Securities current at the time of
receipt of such notice.  The Company shall not be permitted to require the
suspension of the disposition of Registrable Securities for a period in excess
of 90 calendar days in any 12 month period.

          (h) The rights to request registration of any Company securities
pursuant to this Section 15 shall terminate as to any holder who holds
Registrable Securities upon the earlier of (i) when a holder holds one percent
or less of the Company's Common Stock

                                       15
<PAGE>

on an as-converted basis; (ii) when all of a holder's Registrable Securities may
be sold during a single three-month period under Rule 144; (iii) when a holder's
Registrable Securities may be transferred under Rule 144(k) unless such holder
later becomes an affiliate of the Company (as defined in Rule 144), in which
case such holder's rights to request registration shall be revived until such
holder's rights otherwise terminate under this subsection (h); and (iv) three
years after the closing of a firm commitment underwritten public offering
pursuant to an effective registration statement under the Securities Act
covering the offer and sale of the Company's Common Stock at a price per share
of not less than $10.00 (as adjusted for stock splits, dividends, combinations
and the like) and an aggregate offering price to the public of not less than
$20,000,000. Such three-year period shall not include any period of time during
which adequate current public information, as defined in Rule 144(c) promulgated
under the Securities Act, is not available with respect to the Company.

          (i) The Company hereby indemnifies, to the fullest extent permitted by
law, the Investor or each person, if any, who controls Investor within the
meaning of Section 15 of the Act, and the directors, officers, employees, agents
and representatives of each of them, against all losses, claims, damages,
liabilities, costs and expenses (including, without limitation, fees and
expenses of counsel), as incurred, arising out of, relating to, or caused by any
untrue statement or alleged untrue statement of a material fact contained in any
registration statement, prospectus or preliminary prospectus (or any amendment
or supplement thereto) or any omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, except insofar as such losses, claims, damages,
liabilities or expenses are caused by any untrue statement contained in, or
omission from, information furnished in writing to the Company by Investor
expressly for use therein.  In connection with any registration statement in
which Investor is participating, Investor will furnish to the Company in writing
such information as shall reasonably be requested by the Company for use in any
such registration statement or prospectus and will indemnify, to the extent
permitted by law, the Company, its directors and officers and each person, if
any, who controls the Company within the meaning of the Act against any losses,
claims, damages, liabilities and expenses resulting from any untrue statement or
alleged untrue statement of a material fact or any omission or alleged omission
of a material fact required to be stated in the registration statement or
prospectus or necessary to make the statements therein not misleading, but only
to the extent that such untrue statement of a material fact is contained in, or
such material fact is omitted from, information so furnished in writing by such
Investor expressly for use therein.

          (j) For purposes of this Section 15, the Investor shall include any
transferee of the Investor if such transfer is made in accordance herewith.

     16.  Remedies.  The Company acknowledges and agrees that irreparable harm,
          --------
for which there may be no adequate remedy at law and for which the ascertainment
of damages would be difficult, would occur in the event any of the provisions of
this Warrant were not performed in accordance with its specific terms or were
otherwise breached.  The Company accordingly agrees that the holders shall be
entitled to an injunction or injunctions to prevent breaches of the provisions
of this Warrant and to enforce specifically the terms and provisions hereof in
any court of the United States or any state thereof having jurisdiction, in each
instance

                                       16
<PAGE>

without being required to post bond or other security and in addition to, and
without having to prove the inadequacy of other remedies at law.

     17.  Securities Matters
          ------------------

          At such time as the Company becomes subject to the reporting
requirements of the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), and at all times thereafter, the Company agrees to deliver to the
Investor all such reports, information and other documents as it shall be
required to file with the Commission pursuant to Section 13 or 15(d) of the
Exchange Act within 15-days after the date it is required to file such reports
with the Commission.  Prior to such time as the Company becomes subject to the
reporting requirements of the Exchange Act, and in order to make available the
benefits of certain rules and regulations of the Commission which may at any
time permit the sale of the shares of Common Stock issuable upon exercise of the
Warrant to the public without registration; the Company agrees to deliver to the
Investor all such reports, information and other documents as it may be required
to provide to any lender or other creditor.  From and after the time the Company
files a registration statement with die Commission with respect to the Warrants
or the shares of Common Stock issuable thereunder, the Company shall file such
information with the Commission; provided, that the Company shall not be in
default of the provisions of this Section 17 for any failure to file reports
with the Commission solely by refusal by the Commission to accept the same for
filing.

                 [Remainder of page intentionally left blank]

                                       17
<PAGE>

[Warrant for the Purchase of Shares of Common Stock of Paradigm Genetics Inc.]


                                           PARADIGM GENETICS INC.,
                                           a North Carolina corporation


Address:
104 Alexander Drive                        By:     /s/  Ian Howes
Building 2                                    ---------------------------
Research Triangle Park, NC  27709          Name:   Ian Howes
                                           Title:  Vice President
                                           Dated:


ACCEPTED AND AGREED:


ARE-104 ALEXANDER ROAD, LLC,
a Delaware limited liability company

  By:  Alexandria Real Estate Equities, L.P.,
       a Delaware limited partnership,
       Its Managing Member

       By: ARE-QRS Corp., a Maryland corporation,
           Its General Partner

           By:
               ---------------------------
               Name:
               Title:

               Dated:

                                       18
<PAGE>

[Warrant for the Purchase of Shares of Common Stock of Paradigm Genetics Inc.]


                                           PARADIGM GENETICS INC.,
                                           a North Carolina corporation


Address:
104 Alexander Drive                        By:
Building 2                                    --------------------------
Research Triangle Park, NC  27709          Name:
                                           Title:
                                           Dated:


ACCEPTED AND AGREED:


ARE-104 ALEXANDER ROAD, LLC,
a Delaware limited liability company

  By:  Alexandria Real Estate Equities, L.P.,
       a Delaware limited partnership,
       Its Managing Member

       By:   ARE-QRS Corp., a Maryland corporation,
             Its General Partner

             By:     /s/ Joel S. Marcus
                ----------------------------
             Name:   Joel S. Marcus
             Title:  Chief Executive Officer

             Dated:

                                       19
<PAGE>

                                 SUBSCRIPTION
                                 ------------



Paradigm Genetics Inc.
104 Alexander Drive
Building 2
Research Triangle Park, North Carolina  27709

Ladies and Gentlemen:

     The undersigned,             , hereby elects to purchase, pursuant to the
                     -------------
provisions of the Warrant dated        , 1999 held by the undersigned,    shares
                               --------                               ----
of the Common Stock of Paradigm Genetics Inc., a North Carolina corporation, and
tenders herewith payment of the purchase price of such shares in full.

     In exercising its rights to purchase such Common Stock, the undersigned
hereby confirms the investment representations made in Section 7.

Dated:
       ---------------------

                                      --------------------------------------

                                      By

                            Address:
                                      --------------------------------------

                                      --------------------------------------

                                       20
<PAGE>

                             [FORM OF ASSIGNMENT]

The undersigned hereby assigns this Warrant to

----------------------------------------------------------------------------

----------------------------------------------------------------------------

----------------------------------------------------------------------------
            (Print or type name, address and zip code of assignee)

Please insert Social Security or other
  identifying number of assignee


 -------------------------------------

and irrevocably appoints             as agent to transfer this Warrant on the
                        -------------
books of the Company.  The agent may substitute another to act for him or it.


Dated:                    Signed:
      -------------------        --------------------------

-----------------------------------------------------------------------------
          (Sign exactly as name appears on the front of this Warrant)


Dated:                     Signed:
      --------------------        --------------------------
                           Name:
                                  --------------------------
                           Title:
                                  --------------------------


(Sign exactly as name appears on the front of this Warrant)



Dated:              Signed:                 Name:
      --------------       ----------------      ----------------------
                                     Title:
------------------------------------       ----------------------------

                                       21