EXHIBIT 10.10


                               SECURITY AGREEMENT

     THIS SECURITY  AGREEMENT (this  "AGREEMENT") is made as of May 6, 1999 by
and between  INFORMAX,  INC., a Delaware  corporation (the  "GRANTOR"),  with an
address  at 6110  Executive  Boulevard,  N.  Bethesda,  MD 20852,  and PNC BANK,
NATIONAL  ASSOCIATION  (the  "Bank").  All terms  capitalized  but not otherwise
defined  herein shall have the meanings  ascribed to them in the Loan  Agreement
(as defined below).

     Under the terms hereof,  the Bank desires to obtain and the Grantor desires
to grant the Bank security for all of the Obligations (as hereinafter defined).

     NOW,  THEREFORE,  the Grantor and the Bank,  intending to be legally bound,
hereby agree as follows:

     1. DEFINITIONS.

     (a) "COLLATERAL" shall include all personal property of the Grantor (except
for certain  office  equipment  and  related  items  located in home  offices of
employees with a book value less than Thirty Thousand  Dollars  ($30,000) in the
aggregate), including without limitation the following, all whether now owned or
hereafter  acquired or arising:  (i)  accounts,  accounts  receivable,  contract
rights (except with respect to those  contracts which require consent of a third
party to assignment by the Grantor of its rights  thereunder,  and for which the
Grantor is unable to obtain such  consent  after the  exercise  of  commercially
reasonable efforts; provided,  however, that the foregoing exception shall in no
event apply to the Grantor's right to receive payment under any contract,  which
right to payment shall be specifically included in the Collateral without regard
to any  restrictions on the assignment of any other rights under such contract),
chattel paper, notes receivable,  instruments and documents (including warehouse
receipts),  and Grantor's  accounts  with the Bank;  (ii) goods of every nature,
including without limitation, inventory,  stock-in-trade, raw materials, work in
process,  items held for sale or lease or  furnished  or to be  furnished  under
contracts of sale or lease,  goods that are returned,  reclaimed or repossessed,
together  with  materials  used or consumed  in the  Grantor's  business;  (iii)
equipment,  including,  without limitation,  machinery,  vehicles, furniture and
fixtures;  (iv) general intangibles,  of every kind and description,  including,
but not limited to, all existing and future  customer  lists,  choses in action,
claims (including  without  limitation claims for  indemnification  or breach of
warranty),   books,  records,   patents  and  patent  applications,   trademarks
(including,  without  limitation,  the  Trademarks  as  defined  in the Rider to
Security Agreement - Trademarks between Grantor and Bank of even date herewith),
tradestyles, trademark applications, goodwill, blueprints, drawings, designs and
plans, trade secrets, contracts, licenses, license agreements, formulae, tax and
any other types of refunds, returned and unearned insurance premiums, rights and
claims under insurance  policies,  and computer  information,  software,  source
codes,  object codes,  records and data;  (v) all property of the Grantor now or
hereafter in the Bank's  possession or in transit to or from,  under the custody
or control of or on deposit with, the Bank or any


<PAGE>


affiliate thereof,  including deposit and other accounts; (vi) all cash and cash
equivalents;  and  (vii)  all  cash and  non-cash  proceeds  (including  without
limitation,  insurance proceeds) of all of the foregoing property,  all products
thereof and all additions and  accessions  thereto,  substitutions  therefor and
replacements thereof.

     (b) "LOAN  AGREEMENT"  means the Loan Agreement  dated as of May 6, 1999 by
and among the Grantor and the Bank.

     (c) "LOAN DOCUMENTS" means this Agreement,  the Loan Agreement, any and all
notes  evidencing the  Obligations  and all related  documents,  instruments and
agreements.

     (d) "OBLIGATIONS" shall include,  without limitation,  all loans, advances,
debts, liabilities, obligations, covenants and duties owing to the Bank from the
Grantor under the Loan  Documents and any  amendments,  extensions,  renewals or
increases  and all  reasonable  and  necessary  costs and  expenses  of the Bank
incurred  in  the   documentation,   negotiation,   modification,   enforcement,
collection or otherwise in connection  with any of the foregoing,  including but
not limited to reasonable attorneys' fees and expenses.

     2. GRANT OF SECURITY INTEREST.  To secure the Obligations,  the Grantor, as
debtor,  hereby  assigns and grants to the Bank, as secured  party, a continuing
lien on and security interest in the Collateral.

     3.  CHANGE IN NAME OR  LOCATIONS.  The  Grantor  hereby  agrees that if the
location of any material Collateral changes from the locations listed on Exhibit
A hereto and made part  hereof,  or if the  Grantor  changes its name or form of
organization, or establishes a name in which it plans to do business that is not
listed as a  tradename  on Exhibit A hereto,  the  Grantor  will as  promptly as
practicable  notify the Bank in writing of the  additions or changes.  As of the
date hereof,  the Grantor's  chief  executive  office is also shown on Exhibit A
hereto.

     4.  REPRESENTATIONS  AND WARRANTIES.  Except as disclosed in or pursuant to
the Loan Agreement,  the Grantor represents,  warrants and covenants to the Bank
that: (a) the Grantor has not made any prior pledge, encumbrance,  assignment or
other  disposition  of any of the  Collateral  and the same  are  free  from all
encumbrances  and rights of setoff of any kind;  (b) the  Grantor  will take all
commercially  reasonable actions to defend the Collateral against all claims and
demands of all persons at any time  claiming the same or any  interest  therein;
(c) each  account and general  intangible,  if  included  in the  definition  of
Collateral,  is genuine and  enforceable  in  accordance  with its terms and the
Grantor will take all commercially reasonable actions to defend the same against
all claims, demands,  setoffs and counterclaims at any time asserted; and (d) at
the time any account or general  intangible  becomes  subject to this Agreement,
such account or general  intangible  will be genuine and enforceable and no such
account or general intangible will be subject to any claim for credit, allowance
or adjustment by any account debtor or any setoff, defense or counterclaim.


                                       2
<PAGE>


     5. GRANTOR'S COVENANTS. The Grantor covenants that it shall:

     (a) from time to time and at all  reasonable  times  allow  the Bank,  with
reasonable prior notice, by or through any of its officers,  agents,  attorneys,
or accountants, to examine or inspect the Collateral,  notify, at any time after
the  occurrence  and  during the  continuance  of an Event of  Default,  account
debtors of the Bank's  security  interest in  accounts  and obtain not more than
once annually  valuations and audits of the Collateral at the Grantor's expense.
The Grantor shall do, obtain,  make, execute and deliver all such additional and
further  acts,  things,  deeds,  assurances  and  instruments  as the  Bank  may
reasonably require to vest in and assure to the Bank its rights hereunder and in
or to the Collateral,  and the proceeds thereof,  including, but not limited to,
waivers  from  landlords,  warehousemen  and  mortgagees  and the  execution  of
appropriate  Riders with respect to patents and  copyrights if the Grantor seeks
to register its rights in any such patents or copyrights  with either the United
States  Patent  and  Trademark  Office  or with the  United  States  Library  of
Congress, as applicable;

     (b) keep the Collateral in good order and repair at all times ordinary wear
and tear and obsolescence excepted;

     (c) only use or permit the  Collateral  to be used in  accordance  with all
applicable federal, state, county and municipal laws and regulations; and

     (d) have and maintain insurance at all times with respect to all Collateral
against risks of fire (including so-called extended coverage),  theft, sprinkler
leakage,  and  other  risks  (including  risk  of  flood  if any  Collateral  is
maintained at a location in a flood hazard zone) as is customary  with companies
in the same or similar  businesses.  The policies of all such casualty insurance
shall contain standard Lender's Loss Payable Clauses issued in favor of the Bank
under  which  all  losses  thereunder  shall be paid to the  Bank as the  Bank's
interest may appear.  Such policies shall  expressly  provide that the requisite
insurance  cannot be altered or canceled without at least thirty (30) days prior
written notice to the Bank and shall insure the Bank  notwithstanding the act or
neglect of the Grantor.  Upon demand of the Bank,  the Grantor shall furnish the
Bank with  duplicate  original  policies of insurance or such other  evidence of
insurance as the Bank may require.  In the event of failure to obtain  insurance
as herein provided,  the Bank may, at its option,  obtain such insurance and the
Grantor  shall  pay to the  Bank,  on  demand,  the cost  thereof.  Proceeds  of
insurance may be applied by the Bank to reduce the  Obligations  or to repair or
replace Collateral, all in the Bank's sole discretion.

     6. NEGATIVE PLEDGE; NO TRANSFER. The Grantor will not sell or offer to sell
or otherwise  transfer or grant or suffer the  imposition  of a lien or security
interest upon the Collateral  (except for sales of inventory and  collections of
accounts in the  Grantor's  ordinary  course of  business  and as  permitted  by
Sections 6.2 and 6.5 of the Loan  Agreement)  or use any portion  thereof in any
manner  inconsistent with this Agreement or with the terms and conditions of any
policy of insurance thereon.


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<PAGE>


     7.  COVENANTS FOR ACCOUNTS.  If accounts are included in the  definition of
Collateral:

     (a) The Grantor will, on reasonable  demand of the Bank,  make notations on
its  books  and  records  showing  the  security  interest  of the Bank and make
available to the Bank shipping and delivery receipts  evidencing the shipment of
the goods that gave rise to an account,  completion  certificates or other proof
of the satisfactory performance of services that gave rise to an account, a copy
of the invoice for each account and copies of any written contract or order from
which an account arose. The Grantor shall promptly notify the Bank if an account
becomes  evidenced or secured by an instrument or chattel paper and upon request
of the Bank,  will promptly  deliver any such instrument or chattel paper to the
Bank,  including  without  limitation,  any  letter of credit  delivered  to the
Grantor to support a shipment of inventory by the Grantor.

     (b) To the extent  inconsistent with any information  provided with respect
to the  Borrowing  Base (as defined in the Loan  Agreement),  the  Grantor  will
within 30 days advise the Bank whenever an account  debtor  refuses to retain or
returns  any goods from the sale of which an account  arose and will comply with
any reasonable  instructions  that the Bank may give regarding the sale or other
disposition of such returns.

     (c) The  Grantor  will notify the Bank on a monthly  basis of any  accounts
which arise out of contracts with the United States or any department, agency or
instrumentality  thereof which have been added to the Borrowing Base (as defined
in the Loan  Agreement),  and will,  upon the  request of the Bank,  execute any
instruments  and  take any  steps  reasonably  required  by the Bank so that all
monies due and to become due under such  contract  shall be assigned to the Bank
and notice  thereof  given to and  acknowledged  by the  appropriate  government
agency or authority under the Federal Assignment of Claims Act.

     (d) Upon the occurrence,  and during the continuance of an Event of Default
for a period of at least sixty (60)  consecutive  days,  the Bank may notify any
persons who are indebted to the Grantor on any Collateral consisting of accounts
or general intangibles of the assignment thereof to the Bank and may direct such
account  debtors to make payment  directly to the Bank of the amounts due.  Upon
the  occurrence,  and  during the  continuance  of an Event of  Default,  at the
request of the Bank, the Grantor will direct any persons who are indebted to the
Grantor on any Collateral  consisting of accounts or general intangibles to make
payment  directly to the Bank.  The Bank is  authorized to give receipts to such
account  debtors for any such payments and the account debtors will be protected
in making such  payments to the Bank.  If an Event of Default has  occurred  and
remains uncured for more than sixty (60) consecutive  days thereafter,  upon the
written  request  of the Bank,  the  Grantor  will  establish  with the Bank and
maintain a lockbox account ("LOCKBOX") with the Bank and a depository account(s)
("CASH  COLLATERAL  ACCOUNT")  with the Bank subject to the  provisions  of this
subparagraph and such other agreements  related thereto as the Bank may require,
whereupon  all  collections  of accounts  shall be paid  directly  from  account
debtors  into the  Lockbox  from which funds  shall be  transferred  to the Cash
Collateral Account, and from which funds shall be applied by the Bank, daily, to
reduce the outstanding Obligations.


                                       4
<PAGE>


     8. FURTHER  ASSURANCES.  At the request of the Bank,  the Grantor will join
with the Bank in  executing  one or more  financing,  continuation  or amendment
statements  pursuant to the Uniform  Commercial Code in form satisfactory to the
Bank and will pay the cost of preparing and filing the same in all jurisdictions
in which  such  filing  is  reasonably  deemed  by the Bank to be  necessary  or
desirable. A carbon,  photographic or other copy of this Agreement or of a UCC-1
financing statement may be filed as and in lieu of a UCC-1 financing statement.

     9. EVENTS OF DEFAULT.  The Grantor shall,  at the option of the Bank, be in
default under this Agreement  upon the happening of any of the following  events
or  conditions  (each,  an "EVENT OF  DEFAULT"):  (a) any Event of  Default  (as
defined in any of the Loan  Documents)  which has not been cured within any time
period  applicable  thereto;  (b)  failure by the  Grantor to perform any of its
obligations  under this  Agreement  which  failure has not been cured within ten
days  after  written  notice to the  Grantor;  (c)  material  falsity,  material
inaccuracy  or  material  breach  by  the  Grantor  of  any  written   warranty,
representation or statement made or furnished to the Bank by or on behalf of the
Grantor; (d) an uninsured material loss, theft, damage, or destruction to any of
the  Collateral,  or the entry of any judgment in excess of $50,000  against the
Grantor or any lien against or the making of any levy,  seizure or attachment of
or on the  Collateral,  other than as permitted  under the Loan  Agreement;  (e)
except as disclosed in the Addendum to or as permitted under the Loan Agreement,
the failure of the Bank to have a perfected first priority  security interest in
the Collateral  (excluding perfection of security interests in vehicles or other
mobile  equipment  covered by a certificate  of title,  the  perfection of which
requires  notation of such security  interest on, or physical  delivery of, such
certificate),  unless such failure  results from the  negligence of the Bank; or
(f) any  indication  or evidence  received by the Bank that the Grantor may have
directly or indirectly been engaged in any type of activity which, in the Bank's
reasonable discretion might result in the forfeiture of any material property of
the Grantor to any governmental entity, federal, state or local.

     10.  REMEDIES.  Upon the occurrence of any such Event of Default and at any
time thereafter, the Bank may declare all Obligations secured hereby immediately
due and payable  upon written  notice to Grantor and shall have,  in addition to
any remedies  provided  herein or by any  applicable  law or in equity,  all the
remedies of a secured party under the Uniform Commercial Code.

     11. POWER OF ATTORNEY.  (a) The Grantor  does hereby make,  constitute  and
appoint  any  officer  or  agent of the Bank as the  Grantor's  true and  lawful
attorney-in-fact,  with power to endorse  the name of the  Grantor or any of the
Grantor's officers or agents upon any notes,  checks,  drafts,  money orders, or
other  instruments of payment or Collateral that may come into the possession of
the Bank in full or part payment of any amounts  owing to the Bank;  granting to
the Grantor's said attorney full power to do any and all things  necessary to be
done in and about the  premises as fully and with the same effect as the Grantor
might or could do, including the right to sign, for the Grantor, UCC-1 financing
statements  and to sue for,  compromise,  settle  and  release  all  claims  and
disputes with respect to, the  Collateral.  The Grantor hereby ratifies all that


                                       5
<PAGE>


said attorney shall lawfully do or cause to be done by virtue hereof. This power
of attorney is coupled with an interest, and is irrevocable for the life of this
Security  Agreement and the Loan  Documents,  and until all the  Obligations are
satisfied in full.

     (b)  Notwithstanding  anything in the Loan  Documents to the contrary,  the
Bank will not exercise any rights under the general  power of attorney  provided
in Section 11(a) unless an Event of Default has occurred and is continuing.

     12. PAYMENT OF EXPENSES.  In the event that the Grantor fails to do so on a
timely basis,  the Bank may, at its option,  discharge  taxes,  liens,  security
interests or such other  encumbrances as may attach to the  Collateral,  may pay
for  required  insurance  on the  Collateral  and may  pay for the  maintenance,
appraisal or reappraisal,  and  preservation  of the  Collateral,  as reasonably
determined by the Bank to be necessary.  The Grantor will  reimburse the Bank on
demand for any payment so made or any expense  incurred by the Bank  pursuant to
the foregoing authorization, and the Collateral also will secure any advances or
payments so made or expenses so incurred by the Bank.

     13. NOTICES. All notices, demands, requests,  consents, approvals and other
communications  required or permitted  hereunder  must be in writing and will be
effective  upon receipt if  delivered  personally  to such party,  or if sent by
facsimile   transmission  with  confirmation  of  delivery,   or  by  nationally
recognized  overnight courier service, to the address set forth above or to such
other address as any party may give to the other in writing for such purpose.

     14. PRESERVATION OF RIGHTS. No delay or omission on the part of the Bank to
exercise  any right or power  arising  hereunder  will  impair any such right or
power or be  considered a waiver of any such right or power or any  acquiescence
therein,  nor will the action or  inaction of the Bank impair any right or power
arising  hereunder.  The Bank's rights and remedies hereunder are cumulative and
not  exclusive  of any other  rights or  remedies  which the Bank may have under
other agreements, at law or in equity.

     15. ILLEGALITY. In case any one or more of the provisions contained in this
Agreement  should be  invalid,  illegal or  unenforceable  in any  respect,  the
validity,  legality and  enforceability  of the remaining  provisions  contained
herein shall not in any way be affected or impaired thereby.

     16.  CHANGES  IN  WRITING.  No  modification,  amendment  or  waiver of any
provision  of  this  Agreement  nor  consent  to any  departure  by the  Grantor
therefrom,  will in any event be  effective  unless the same is in  writing  and
signed by the Bank,  and then such waiver or consent shall be effective  only in
the  specific  instance  and for the  purpose for which  given.  No notice to or
demand on the  Grantor  in any case will  entitle  the  Grantor  to any other or
further notice or demand in the same, similar or other circumstance.


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<PAGE>


     17.  ENTIRE  AGREEMENT.   This  Agreement   (including  the  documents  and
instruments  referred to herein) constitutes the entire agreement and supersedes
all other prior agreements and  understandings,  both written and oral,  between
the parties with respect to the subject matter hereof.

     18. COUNTERPARTS. This Agreement may be signed in any number of counterpart
copies and by the parties hereto on separate  counterparts,  but all such copies
shall constitute one and the same instrument.

     19.  SUCCESSORS AND ASSIGNS.  This Agreement will be binding upon and inure
to the  benefit  of the  Grantor  and  the  Bank  and  their  respective  heirs,
executors,  administrators,  successors and assigns; provided, however, that the
Grantor  may not assign  this  Agreement  in whole or in part  without the prior
written  consent of the Bank and the Bank at any time may assign this  Agreement
in whole or in part upon written notice to Grantor.

     20.  INTERPRETATION.  In this  Agreement,  unless the Bank and the  Grantor
otherwise agree in writing,  the singular includes the plural and the plural the
singular;  words  importing any gender include the other genders;  references to
statutes   are  to  be  construed  as   including   all   statutory   provisions
consolidating,  amending or  replacing  the statute  referred  to; the word "or"
shall be deemed to  include  "and/or",  the words  "including",  "includes"  and
"include"  shall be deemed to be  followed  by the words  "without  limitation";
references to articles,  sections (or  subdivisions of sections) or exhibits are
to those of this Agreement unless otherwise indicated.  Section headings in this
Agreement  are  included  for  convenience  of  reference  only  and  shall  not
constitute a part of this Agreement for any other purpose.  If this Agreement is
executed by more than one Grantor,  the  obligations of such persons or entities
will be joint and several.

     21.  INDEMNITY.  The  Grantor  agrees to  indemnify  each of the Bank,  its
directors,  officers and employees  and each legal entity,  if any, who controls
the Bank (the "INDEMNIFIED PARTIES") and to hold each Indemnified Party harmless
from and against any and all claims, damages,  losses,  liabilities and expenses
(including,  without  limitation,  reasonable  fees of  counsel  with  whom  any
Indemnified  Party  may  consult  and  reasonable   expenses  of  litigation  or
preparation  therefor)  which  any  Indemnified  Party may incur or which may be
asserted  against  any  Indemnified  Party  by  any  third  person,   entity  or
governmental authority as a result of the execution of or performance under this
Agreement;  provided,  however, that the foregoing indemnity agreement shall not
apply to claims, damages,  losses,  liabilities and expenses solely attributable
to an Indemnified Party's gross negligence or willful misconduct.  The indemnity
agreement  contained  in this  Section  shall  survive the  termination  of this
Agreement. The Grantor may participate at its expense in the defense of any such
claim.

     22.  GOVERNING LAW AND  JURISDICTION.  This Agreement has been delivered to
and  accepted by the Bank and will be deemed to be made in the  Commonwealth  of
Pennsylvania.  THIS AGREEMENT WILL BE INTERPRETED AND THE RIGHTS AND LIABILITIES
OF THE PARTIES HERETO DETERMINED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH
OF


                                       7
<PAGE>


PENNSYLVANIA,  EXCEPT THAT THE LAWS OF THE STATE WHERE ANY COLLATERAL IS LOCATED
(IF DIFFERENT FROM THE COMMONWEALTH OF PENNSYLVANIA)  SHALL GOVERN THE CREATION,
PERFECTION AND  FORECLOSURE  OF THE LIENS CREATED  HEREUNDER ON SUCH PROPERTY OR
ANY INTEREST THEREIN.  The Grantor hereby irrevocably  consents to the exclusive
jurisdiction  of any state or federal court for Allegheny  County or the Western
District of  Pennsylvania,  as the case may be, and consents that all service of
process be sent by nationally  recognized  overnight courier service directed to
the Grantor at the  Grantor's  address set forth herein and service so made will
be deemed to be completed on the business day after  deposit with such  courier;
provided  that nothing  contained in this  Agreement  will prevent the Bank from
bringing any action,  enforcing any award or judgment or  exercising  any rights
against the Grantor  individually,  against any security or against any property
of the  Grantor  within any other  county,  state or other  foreign or  domestic
jurisdiction.  The Bank and the Grantor agree that the venue  provided  above is
the most convenient forum for both the Bank and the Grantor.  The Grantor waives
any objection to venue and any objection based on a more convenient forum in any
action instituted under this Agreement.

     23.  WAIVER OF JURY TRIAL.  EACH OF THE  GRANTOR  AND THE BANK  IRREVOCABLY
WAIVES  ANY AND  ALL  RIGHT  IT MAY  HAVE  TO A  TRIAL  BY  JURY IN ANY  ACTION,
PROCEEDING  OR CLAIM OF ANY NATURE  RELATING TO THIS  AGREEMENT,  ANY  DOCUMENTS
EXECUTED IN CONNECTION  WITH THIS AGREEMENT OR ANY  TRANSACTION  CONTEMPLATED IN
ANY OF SUCH DOCUMENTS.  THE GRANTOR AND THE BANK  ACKNOWLEDGE THAT THE FOREGOING
WAIVER IS KNOWING AND VOLUNTARY.


                           [Signature Page to Follow]


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<PAGE>


     WITNESS the due  execution of this Security  Agreement as a document  under
seal, as of the date first written above.


                                 INFORMAX, INC.

                                 By: /s/ Alex Titomirov
                                    ------------------------------------
                                                                  (SEAL)

                                 Print Name: Alex Titomirov
                                            ----------------------------

                                Title:   Chief Executive Officer


                                PNC BANK, NATIONAL ASSOCIATION

                                By: /s/ Katharine Kappler
                                   -------------------------------------
                                                                  (SEAL)

                                Print Name: Katharine Kappler
                                           -----------------------------

                                Title: Vice President
                                      ----------------------------------



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<PAGE>


                                    EXHIBIT A
                              TO SECURITY AGREEMENT


Address of Grantor's chief executive office, including the County:

       6110 Executive Boulevard                Montgomery County, Maryland
       N. Bethesda, MD  20852


Address for books and records, if different:

None

Addresses of other Collateral locations, including Counties and name and address
of landlord or owner if location is not owned by the Grantor:

Name and Address of Landlord:



Other names or tradenames now or formerly used by the Grantor:

<PAGE>


                                                                  EXECUTION COPY

RIDER TO SECURITY AGREEMENT -
TRADEMARKS

         THIS RIDER TO SECURITY AGREEMENT  ("RIDER") is executed of May 6, 1999,
by and between INFORMAX,  INC., a Delaware corporation (the "GRANTOR"),  with an
address  at 6110  Executive  Boulevard,  N.  Bethesda,  MD 20852,  and PNC BANK,
NATIONAL ASSOCIATION (the "BANK"). This Rider is incorporated into and made part
of that certain Security Agreement  ("SECURITY  AGREEMENT")  between the Grantor
and the Bank dated May 6, 1999, and also unto certain other financing  documents
and security  agreements  executed by and between the Grantor and the Bank or by
and between the  Borrower (as defined in the  Security  Agreement)  and the Bank
(all such documents including this Rider being collectively referred to as "LOAN
DOCUMENTS").  All  capitalized  terms not otherwise  defined in this Rider shall
have the same meanings ascribed to such terms in the other Loan Documents.

         Schedule A attached  hereto and made part hereof contains a list of all
trademarks and service marks for which Grantor has obtained a U.S.  registration
or for which an application for such registration is pending (all such marks, in
connection with the relevant goods and/or services, hereinafter referred to as a
the "TRADEMARKS").

         The Banks  desires  to  acquire  a lien and  security  interest  on the
Trademarks and the registration  thereof,  together with all the goodwill of the
Grantor associated therewith and represented thereby, as security for all of the
OBLIGATIONS  (as defined in the Security  Agreement)  to the Bank,  and the Bank
desires to have its security interest in such Trademarks confirmed by a document
identifying  same and in such form that it may be recorded in the United  States
Patent and Trademark Office.

         NOW,  THEREFORE,  with the foregoing  background deemed incorporated by
reference  and made part  hereof,  the parties  hereto,  intending to be legally
bound hereby, covenant and agree as follows:

         1. GRANT OF SECURITY INTEREST.  In consideration of and pursuant to the
terms of the  Loan  Documents,  and for  other  good,  valuable  and  sufficient
consideration,  the receipt of which is hereby  acknowledged,  and to secure the
Obligations,  the Grantor grants a lien and security interest to the Bank in all
its  present and future  right,  title and  interest  in and to the  Trademarks,
together with all the goodwill of the Grantor associated with and represented by
the  Trademarks,  and the  registration  thereof  and  the  right  (but  not the
obligation) to sue for past, present and future infringements,  and the proceeds
thereof,  including,  without  limitation,  license  royalties  and  proceeds of
infringement suits.

         2. REPRESENTATION AND WARRANTIES.  Subject to the disclosures set forth
pursuant to the Loan  Agreement  of even date by and between the Grantor and the
Bank, the Grantor represents,  warrants and covenants that: (a) it has the right
to use the  Trademark;  (b) the Grantor is the sole and  exclusive  owner of the
entire  and  unencumbered  right,  title  and  interest  in and to  each  of the
Trademarks, and each of the Trademarks is free and clear of any client, charges,

<PAGE>

and encumbrances,  including, without limitation, pledges, assignments, licenses
and covenants by the Grantor not to sue third  persons;  (c) the Grantor has the
unqualified  right to enter  into this  Rider and  perform  its  terms:  (d) the
Grantor  has used,  and will  continue  to use for the  duration  of this Rider,
proper notice, as permitted by 15 U.S.C. SS 1051-1127 in connection with its use
of the registered Trademarks; and (e) the Grantor has used, and will continue to
use for the duration of this Rider,  consistent standards of quality in products
leased  or sold  under  the  Trademarks  and  hereby  grants to the Bank and its
employees  and agents the right to visit the  Grantor's  locations  which lease,
sell, or store  products under any of the Trademarks and to inspect the products
and quality control records  relating thereto at reasonable times during regular
business hours to ensure the Grantor's compliance with this paragraph 2(c).

         3. COVENANTS.  The Grantor further covenants that: (a) Until all of the
Obligations  have been  satisfied  in full,  the Grantor will not enter into any
agreement,   including  without  limitation,   license  agreements,   which  are
inconsistent  with the Grantor's  obligations  under this Rider,  and (b) If the
Grantor  acquires  rights to any new  Trademarks,  the  provisions of this Rider
shall  automatically  apply  thereto and the Grantor  shall give the Bank prompt
written notice thereof along with an amended Schedule A; provided, however, that
notwithstanding  anything  to the  contrary  contained  in this  Agreement,  the
Grantor shall have the right to enter into  agreements in the ordinary course of
business with respect to the Trademarks.

         4. EXCLUSIVE USE OF TRADEMARKS.  So long as this Rider is in effect and
so long as the  Grantor has not  received  notice from the Bank that an Event of
Default has occurred  under the Loan Documents and that the Bank has elected to
exercise its rights to assignment  hereunder,  the Grantor shall continue to own
and to have the exclusive right to use the Trademarks and the Bank shall have no
right to use the Trademarks or issue any exclusive or non-exclusive license with
respect thereto, or assign, pledge or otherwise transfer title in the Trademarks
to any one else.

         5. NEGATIVE PLEDGE.  The Grantor agrees not to sell,  assign or further
encumber its rights and interest in the Trademarks,  other than licensing in the
ordinary course of business of products subject to the Trademarks, without prior
written consent of the Bank.

         6. REMEDIES UPON DEFAULT. (a) Anything herein contained to the contrary
notwithstanding,  if and while the Grantor  shall be in default  hereunder or an
Event of Default exists under the Loan Documents,  the Grantor hereby  covenants
and agrees that the Bank, as the holder of a security interest under the Uniform
Commercial  Code, as now or hereafter in effect in  Pennsylvania,  may take such
action permitted  under the Loan Documents or permitted by law, in its exclusive
discretion, to foreclose upon the Trademarks covered hereby.

            (b) For such  purposes,  and in the event of the  Grantor's  default
hereunder or an Event of Default under the Loan Documents and while such default
or Event of Default exists,  the Grantor hereby authorizes and empowers the Bank
to make, constitute and appoint any officer or agent of the Bank as the Bank may
select, in its exclusive discretion, as the Grantor's true and

                                   -2-

<PAGE>

lawful  attorney-in-fact,  with the power to endorse the  Grantor's  name on all
applications,  documents,  papers and instruments  necessary for the Bank to use
the Trademarks or to grant or issue any exclusive or non-exclusive license under
the  Trademarks  to anyone else,  or necessary  for the Bank to assign,  pledge,
convey or otherwise  transfer  title in or dispose of the  Trademarks  to anyone
else.  The Grantor  hereby  ratifies all that such attorney shall lawfully do or
cause to be done by virtue  hereof,  except for the gross  negligence or willful
misconduct of such attorney. This power of attorney shall be irrevocable for the
life of this  Rider and the Loan  Documents,  and until all the  Obligations are
satisfied in full.

            (c) The  Grantor  expressly  acknowledges  that this Rider  shall be
recorded by the Bank with the Patent and Trademark  Office in  Washington,  D.C.
Contemporaneously  herewith,  the Grantor  shall also execute and deliver to the
Bank such documents as the Bank shall reasonably request to conditionally assign
all rights in the Trademarks to the Bank,  which documents shall be held by the
Bank until the  occurrence  of an Event of Default  hereunder  or under the Loan
Documents.  After such occurrence, the Bank may, at its sole option, record such
escrowed documents with the Patent and Trademark Office.

         7. PROSECUTION OF TRADEMARK  APPLICATIONS.  (a) Subject to the terms of
the Security Agreement,  the Grantor shall have the duty to prosecute diligently
any trademark  application with respect to the Trademarks pending as of the date
of this Rider or thereafter,  until the Obligations shall have been satisfied in
full, to preserve and maintain all rights in the Trademarks, and upon reasonable
request of the Bank,  the Grantor shall make federal  application on registrable
but unregistered  material trademarks  belonging to the Grantor.  Any reasonable
expenses  incurred in connection  with such  applications  shall be borne by the
Grantor.  Unless  the  Grantor  discontinues  the sale of the goods  offered  in
connection with a Trademark, the Grantor shall not abandon any Trademark without
the written consent of the Bank.

         (b) The  Grantor  shall have the right to bring suit in its own name to
enforce the  Trademarks,  in which  event the Bank may, if the Grantor  deems it
necessary or after an Event of Default under the Loan Documents,  be joined as a
nominal party to such suit if the Bank shall have been  satisfied that it is not
thereby  incurring any risk of liability  because of such  joinder.  The Grantor
shall promptly,  upon demand,  reimburse and indemnify the Bank for all damages,
reasonable costs and reasonable expenses, including attorneys' fees, incurred by
the Bank in the fulfillment of the provisions of this paragraph.

         8.  SUBJECT TO SECURITY  AGREEMENT.  This Rider shall be subject to the
terms,  provisions,  and conditions set forth in the Security  Agreement and may
not  be  modified  without  the  written  consent  of  the  party  against  whom
enforcement is being sought.

         9.  INCONSISTENT  WITH  SECURITY  AGREEMENT.  All rights and  remedies
herein  granted to the Bank  shall be in  addition  to any  rights and  remedies
granted to the Bank under the Loan Documents.  In the event of an  inconsistency
between this Rider and the Security

                                      -3-
<PAGE>

Agreement,  the language of the Security Agreement shall control.  The terms and
conditions  of  the  Security  Agreement  are  hereby   incorporated  herein  by
reference.

         10.  TERMINATION  OF AGREEMENT.  Upon payment and  performance  of all
Obligations  under the Loan Documents,  the Bank shall  immediately  execute and
deliver to the Grantor all documents, and take any and all actions, necessary to
terminate the Bank's security interest in the Trademarks.

         11. FEES AND EXPENSES. Any and all reasonable fees, costs and expenses,
of whatever kind or nature,  including the reasonable  attorney's fees and legal
expenses  incurred by the Bank in connection  with the preparation of this Rider
and  all  other  documents   relating  hereto  and  the   consummation  of  this
transaction,  then filing or recording of any documents  (including all taxes in
connection  therewith) in public offices, the payment or discharge of any taxes,
reasonable  counsel fees,  maintenance  fees,  encumbrances  or costs  otherwise
incurred in protecting,  maintaining, preserving the Trademarks, or in defending
or  prosecuting  any  actions or  proceedings  arising  out of or related to the
Trademarks,  in each case in accordance  with the terms of this Rider,  shall be
borne and paid by the  Grantor  on demand by the Bank and until so paid shall be
added to the  principal  amount of the  Obligations  to the Bank and shall  bear
interest at the contract rate therefor.

         12.  ADDITIONAL  REMEDIES.  Upon the  occurrence of an Event of Default
under  the Loan  Documents,  the Bank  may,  without  any  obligation  to do so,
complete any  obligation of the Grantor  hereunder,  in the Grantor's name or in
the Bank's name, but at the Grantor's expense,  and the Grantor hereby agrees to
reimburse the Bank in full for all  reasonable  expenses,  including  reasonable
attorney's fees,  incurred by the Bank in protecting,  defending and maintaining
the Trademarks.

         13.  GOVERNING LAW. THIS RIDER WILL BE  INTERPRETED  AND THE RIGHTS AND
LIABILITIES OF THE PARTIES HERETO  DETERMINED IN ACCORDANCE WITH THE LAWS OF THE
COMMONWEALTH OF PENNSYLVANIA,  EXCLUDING ITS CONFLICT OF LAW RULES,  EXCEPT THAT
THE  FEDERAL  LAWS OF THE UNITED  STATES OF AMERICA  SHALL  GOVERN TO THE EXTENT
APPLICABLE.

         14. COUNTERPARTS. This Rider may be signed in any number of counterpart
copies and by the parties hereto on separate  counterparts,  but all such copies
shall constitute one and the same instrument.

                     [This space intentionally left blank]


                                      -4-

<PAGE>

         WITNESS  the due  execution  of this  Rider  to  Security  Agreement  -
Trademarks as a document  under seal, as of the date first written  above,  with
the intent to be legally bound hereby.

ATTEST:                                   INFORMAX, INC.


 /s/ Joseph E. Lehnen                     By:  /s/ Alex Titomirov
---------------------------------            -----------------------------------
                                                                          (SEAL)
Print Name: Joseph E. Lehnen              Print Name: Alex Titomirov
           ----------------------                    ---------------------------

                                          Title: President / CEO
                                                --------------------------------


                                          PNC BANK, NATIONAL
                                          ASSOCIATION


                                          By: /s/ Katharine Kappler
                                             -----------------------------------

                                          Print Name: Katharine Kappler
                                                     ---------------------------
                                          Title: Vice President
                                                --------------------------------



                                      -5-

<PAGE>

             SCHEDULE A TO RIDER TO SECURITY AGREEMENT - TRADEMARKS

                     APPLICATION OR                              REGISTRATION
TRADEMARK            REGISTRATION NO.          COUNTRY           OR FILING DATE
---------            ----------------          -------           --------------
ALIGNX (Stylized)      75/565,659                 US               08-Oct-1998

BIOPLOT (Stylized)     75/565,658                 US               08-Oct-1998

CONTIGEXPRESS          75/565,657                 US               08-Oct-1998
(Stylized)

INFORMAX (& Design)     2,115,618                 US               25-Nov-1997

SOFTWARE SOLUTION      75/565,656                 US               08-Oct-1998
FOR BIO-MEDICINE
(SSBM) (Stylized)

VECTOR NTI              1,923,416                 US               03-Oct-1995

VECTOR NTI SUITE       75/565,655                 US               08-Oct-1998
(Stylized)

VECTOR PC               1,776,118                 US               08-Jun-1993

<PAGE>

                              TRADEMARK ASSIGNMENT

         WHEREAS,  INFORMAX,  INC.  (the  "GRANTOR")  is the owner of the entire
right,   title  and  interest  in  and  to  the  United  States  trademarks  and
registrations  listed on Schedule A attached hereto and made a part hereof,  the
inventions described therein and all rights associated therewith  (collectively,
the  "TRADEMARKS"),  which  are  registered  in the  United  States  Patent  and
Trademark Office or which are the subject of pending  applications in the United
States Patent and Trademark Office; and

         WHEREAS, PNC BANK, NATIONAL ASSOCIATION,  having a place of business at
USX Tower,  600 Grant Street,  29th Floor,  MS#  P6-PUSX-29-4.  Pittsburgh,  PA.
15219, identified as the "BANK" under that certain Rider to Security Agreement -
Trademarks  (the "RIDER") of even date  herewith (the  "GRANTEE") is desirous of
acquiring said Trademarks; and

         WHEREAS,  the  Grantee  has a security  interest  in the assets of the
Grantor adequate to carry on the business of the Grantor; and

         WHEREAS,   the  Rider  provides  that  this  Assignment  shall  become
effective  upon the  occurrence  of an  "EVENT OF  DEFAULT"  as  defined  in the
Security  Agreement  of even date  herewith by and  between the Grantor and the
Grantee.

         NOW, THEREFORE,  for good and valuable consideration,  receipt of which
is hereby  acknowledged,  and intending to be legally bound hereby, the Grantor,
its  successors  and  assigns,  subject  to  the  limitation  in  the  paragraph
immediately following,  does hereby transfer,  assign and set over unto Grantee,
its successors,  transferees  and assigns,  all of its present and future right,
title and  interest  in and to the  Trademarks,  the  goodwill  of the  business
associated  with such  Trademarks  and all  proceeds  thereof and all rights and
proceeds associated therewith.

         This Trademark  Assignment  shall be effective only upon  certification
below by an officer of the Grantee  that (i) an Event of Default  has  occurred,
and (ii) the Grantee has elected to take possession of the Trademarks.

         IN  WITNESS  WHEREOF,   the  undersigned  has  caused  this  Trademark
Assignment to be executed by its duly  authorized  officer on this 6 day of May,
1999.

ATTEST:                                   INFORMAX, INC.


 /s/ Joseph E. Lehnen                     By:  /s/ Alex Titomirov
---------------------------------            -----------------------------------
                                                                          (SEAL)
Print Name: Joseph E. Lehnen              Print Name: Alex Titomirov
           ----------------------                    ---------------------------

                                          Title: President / CEO
                                                --------------------------------

         I hereby certify on behalf of PNC Bank, National Association,  that (i)
an "Event of Default" as defined in the  aforementioned  Security  Agreement has
occurred as of ______________,  and (ii) the Bank has elected to take possession
of the Trademarks and is recording this Assignment in the United States Patented
Trademark Office.

                                          By:
                                             -----------------------------------

                                          Title:
                                                --------------------------------

<PAGE>


                       SCHEDULE A TO TRADEMARKS ASSIGNMENT

                     APPLICATION OR                              REGISTRATION
TRADEMARK            REGISTRATION NO.          COUNTRY           OR FILING DATE
---------            ----------------          -------           --------------
ALIGNX (Stylized)      75/565,659                 US               08-Oct-1998

BIOPLOT (Stylized)     75/565,658                 US               08-Oct-1998

CONTIGEXPRESS          75/565,657                 US               08-Oct-1998
(Stylized)

INFORMAX (& Design)     2,115,618                 US               25-Nov-1997

SOFTWARE SOLUTION      75/565,656                 US               08-Oct-1998
FOR BIO-MEDICINE
(SSBM) (Stylized)

VECTOR NTI              1,923,416                 US               03-Oct-1995

VECTOR NTI SUITE       75/565,655                 US               08-Oct-1998
(Stylized)

VECTOR PC               1,776,118                 US               08-Jun-1993