<PAGE>

                                                                    Exhibit 10.8

                               BIO NEBRASKA, INC.

                          REGISTRATION RIGHTS AGREEMENT

         THIS REGISTRATION RIGHTS AGREEMENT, dated as of July 13, 1989, is made
by and among Bio Nebraska, Inc., a Nebraska corporation with its principal place
of business at 1695 Brower Road, Lincoln, Nebraska 68502 (the "Company"); John
N. Irwin III, an individual with an address at 405 Park Avenue, New York, New
York 10022 (the "Purchaser"); Fred Wagner, an individual with an address at c/o
Bio Nebraska, Inc., 1695 Brower Road, Lincoln, Nebraska 68502 ("Wagner");
Sheldon Schuster, an individual with an address at c/o Bio Nebraska, Inc., 1695
Brower Road, Lincoln, Nebraska 68502 ("Schuster"); Dwane Wylie, an individual
with an address at c/o Bio Nebraska, Inc., 1695 Brower Road, Lincoln, Nebraska
68502 ("Wylie"); Thomas R. Coolidge, an individual with an address at c/o Bio
Nebraska, Inc., 1695 Brower Road, Lincoln, Nebraska 68502 ("Coolidge"; Wagner,
Schuster, Wylie and Coolidge are sometimes referred to herein collectively as
the "Managers"); and Cultor, Ltd., a Finnish corporation with a principal place
of business in Finland ("Cultor"; the Purchaser, Cultor and the Managers are
sometimes referred to herein collectively as "Holders").

                                    RECITALS:

         A. The Company is issuing 110 shares of its Common Stock (the "Initial
Purchaser Shares") to the Purchaser pursuant to a Common Stock Purchase
Agreement of even date herewith (the "Purchase Agreement") and is granting the
Purchaser an option to purchase an additional 55 shares of Common Stock (the
"Purchaser Option Shares") pursuant to an Option Agreement of even date herewith
(the "Option Agreement"). (The Initial Purchaser Shares and the Purchaser Option
Shares are sometimes collectively referred to herein as the "Purchaser Shares.")

         B. Each of Wagner, Schuster and Wylie is the holder of 67 shares of the
Company's Common Stock and it is contemplated by that certain Bio Nebraska, Inc.
Shareholder Agreement, dated as of January 1, 1989, that each of them will be
issued an additional 66 of such shares on December 31, 1989 (all of the
foregoing shares, whether previously or to be hereafter issued, are sometimes
referred to herein as the "Founder Shares").

         C. Coolidge will be the holder of 100 shares of the Company's common
stock (such shares, together with the Founder Shares, are sometimes referred to
herein collectively as the "Manager Shares").

         D. Cultor will be the holder of 501 shares of the Company's Common
Stock (the "Cultor Shares"; the Purchaser Shares, the Manager Shares and the
Cultor Shares, together with any and all other shares of the Company's Common
Stock acquired by the Holders prior to the

<PAGE>

first underwritten public offering of the Company's Common Stock, are sometimes
referred to herein collectively as the "Registrable Securities").

         E. The Holders desire to set forth the registration rights to be
granted to the Holders in connection with the securities of the Company held by
them.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants, and conditions set forth in this
Agreement and in the agreements pursuant to which the Holders acquired or will
acquire their securities in the Company, the parties mutually agree as follows:

         1. REQUESTED REGISTRATION. (a) In case the Company shall receive from
the Purchaser, from Cultor or from the Managers a written request, signed by the
Purchaser, Cultor or all of the Managers, as the case may be, that the Company
effect a registration under the Securities Act of 1933, as amended (the
"Securities Act") with respect to the Registrable Securities of any such Holder,
the Company will as soon as practicable, use its best efforts to effect such
registration (including, without limitation, the execution of an undertaking to
file post-effective amendments, appropriate qualification under applicable blue
sky or other state securities laws (provided that the Company shall not be
required in connection therewith to qualify to do business or to file a general
consent to service of process in any such state or jurisdiction) and appropriate
compliance with applicable regulations issued under the Securities Act) as may
be so requested and as would permit or facilitate the sale and distribution of
all or such portion of such Registrable Securities as are specified in such
request; provided that the Company shall not be obligated to take any action to
effect any such registration, qualification or compliance pursuant to this
Section 1:

         (i) Within 6 years of the date of this Agreement;

         (ii) Within the one hundred eighty (180) day period immediately
following the effective date of the registration statement pertaining to the
first underwritten public offering of securities of the Company for its own
account;

         (iii) In the case of a request by either the Managers or Cultor, after
the Company has effected two (2) registrations pursuant to this Section 1 on
behalf of the Managers as a group or on behalf of Cultor, as the case may be,
and such registration have been declared or ordered effective or, in the case of
a request by the Purchaser, after the Company has effected one (1) such
registration on behalf of the Purchaser and such registration has been declared
or ordered effective;

         (iv) If within thirty (30) days of such request the Company gives
notice that it is engaged or has fixed plans to engage in an initial firmly
underwritten registered public offering


                                       2
<PAGE>

pursuant to a registration statement to be filed with the Securities and
Exchange Commission (the "Commission") within thirty (30) days;

         (v) If at the time of the request, the Holder or Holders making the
request could sell all of the Registrable Securities requested to be registered
under Rule 144 promulgated under the Securities Act ("Rule 144") during the
three-month period following such request;

         (vi) If at the time of the request the Holder or Holders making the
request own, in the aggregate, less than five percent (5%) of the Company's then
outstanding shares of Common Stock (without giving effect to shares issuable
upon exercise or conversion of outstanding securities); or

         (vii) If the aggregate offering to the public of the Registrable
Securities requested to be registered would not be at least $2,500,000.

         Subject to the foregoing clauses (i) through (vii) and to Section (c),
the Company shall file a registration statement covering the Registrable
Securities so requested to be registered as soon as practicable after receipt of
the request of the Purchaser, Cultor or the Managers.

         (b) UNDERWRITING. If the Holders intend to distribute the Registrable
Securities covered by their request by means of an underwriting, they shall so
advise the Company as a part of their request. If the underwriter has not
limited the number of Registrable Securities to be underwritten, the Company may
include securities for its own account or the account of others in such
registration if the underwriter so agrees and if the number of Registrable
Securities which would otherwise have been included in such registration and
underwriting will not thereby be limited.

         (c) DELAY OF REGISTRATION. If the Company shall furnish to the Holders
making the request a certificate signed by the President or the Chairman of the
Board of the Company stating that, in the good faith judgment of the Board of
Directors of the Company, it would be seriously detrimental to the Company and
its shareholders to proceed with such registration statement at that time, then
the Company may direct that such request for registration be delayed for a
period not in excess of one hundred twenty (120) days, such right to delay a
request to be exercised by the Company not more than twice in any one-year
period.

         2. COMPANY REGISTRATION.

         (a) If at any time or from time to time the Company shall determine to
register any of its Common Stock, for its own account or for the account of
others, other than (I) a registration relating solely to employee benefit plans,
(II) a registration relating solely to a Commission Rules 145 transaction, (III)
a registration relating to the first underwritten public offering of securities
of the Company or (IV) a registration on any registration form which does not
include


                                       3
<PAGE>

substantially the same information as would be required to be included in a
registration statement covering the sale of the Registrable Securities, the
Company will:

         (i) promptly give to each Holder written notice thereof (which shall
include a list of the jurisdictions in which the Company intends to attempt to
qualify such securities under the applicable blue sky or other state securities
laws); and

         (ii) include in such registration (and any related qualification under
blue sky laws or other compliance), and in any underwriting involved therein,
all the Registrable Securities specified in a written request or requests, made
within twenty (20) days after receipt of such written notice from the Company,
by any Holder or Holders, PROVIDED, HOWEVER, that the Company shall not be
required to effect any such registration if at the time of the request such
Holder or Holders could legally sell all of the Registrable Securities requested
to be registered under Rule 144 during the 12-month period following such
request.

         (b) UNDERWRITING. If the registration of which the Company gives notice
is for a registered public offering involving an underwriting, the Company shall
so advise the Holders as part of the written notice given pursuant to Section
2(a)(i). In such event the right of any Holder to registration pursuant to this
Section 2 shall be conditioned upon such Holder's participation in such
underwriting and the inclusion of such Holder's Registrable Securities in the
underwriting to the extent provided herein. All Holders proposing to distribute
their securities through such underwriting shall (together with the Company and
the other holders distributing their securities through such underwriting) enter
into an underwriting agreement in customary form with the underwriter or
underwriters selected for such underwriting by the Company. Notwithstanding any
other provision of this Section 2, if the underwriter determines that marketing
factors require a limitation of the number of shares to be underwritten, the
underwriter may exclude some or all of such Holders' Registrable Securities from
such registration and underwriting. The Company shall so advise all Holders
(except those Holders who have indicated to the Company their decision not to
distribute any of their Registrable Securities through such underwriting), and
the number of shares of Registrable Securities that may be included in the
registration and underwriting shall be allocated among such Holders in
proportion, as nearly as practicable, to the respective amounts of the aggregate
number of shares of Common Stock and Registrable Securities owned by such
Holders and such other shareholders at the time of filing the registration
statement. No Registrable Securities excluded from the underwriting by reason of
the underwriter's marketing limitation shall be included in such registration.
If any Holder disapproves of the terms of any such underwriting, such Holder may
elect to withdraw therefrom by written notice to the Company and the
underwriter. The Registrable Securities and/or other securities so withdrawn
from such underwriting shall also be withdrawn from such registration; provided,
however, that, if by the withdrawal of such Registrable Securities a greater
number of Registrable Securities held by other Holders may be included in such
registration (up to the maximum of any limitation imposed by the underwriter),
then the Company shall offer to all Holders who have included Registrable
Securities in the registration the right to include


                                       4
<PAGE>

additional Registrable Securities in the same proportion used above in
determining the underwriter limitation.

         3. EXPENSES OF REGISTRATION. Unless and to the extent otherwise
required, in the judgment of counsel to the Company, in order to comply with
applicable state blue sky or securities laws and regulations, all expenses
incurred by the Company in complying with Sections 1 and 2 hereof, including,
without limitation, all registration and filing fees, printing expenses, fees
and disbursements of counsel for the Company, blue sky fees and expenses, and
the expense of any special audits incident to or required by any such
registration (but excluding the compensation of regular employees of the Company
which shall be paid in any event by the Company) shall be borne by the Company;
PROVIDED, HOWEVER, that all underwriting discounts, selling commissions and
registration or filing fees applicable to the sale of Registrable Securities and
fees and disbursements of counsel to participating Holders shall be borne by the
Holders of the securities so registered pro-rata on the basis of the number of
shares so registered. The Company shall not, however, be required to pay for
expenses of any registration proceeding begun pursuant to Section 1, the request
of which has been subsequently withdrawn by the Holder making the request
(unless the withdrawal is based upon material adverse information concerning the
Company of which the Holder was not aware at the time of such request or the
Company's failure to provide the legal opinion or accountants' letter described
in paragraph 4(g)), in which case such expenses shall be borne by the Holder.

         4. REGISTRATION PROCEDURES. In the case of each registration,
qualification or compliance effected by the Company pursuant to Sections 1 or 2,
the Company will keep each Holder advised in writing as to the initiation of
each registration, qualification and compliance and as to the completion
thereof. At the Company's expense (unless and to the extent otherwise required,
in the judgment of counsel to the Company, in order to comply with applicable
state blue sky or securities laws and regulations), the Company will:

         (a) Use its best efforts to keep such registration, qualification or
compliance effective for a period of ninety (90) days or until the Holder or
Holders have completed the distribution described in the registration statement
relating thereto, whichever first occurs.

         (b) Prepare and file with the SEC such amendments and supplements to
such registration statement and the prospectus used in connection with such
registration statement as may be necessary to comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such
registration statement.

         (c) Furnish to the Holders such numbers of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the
Securities Act, and such other documents as they may reasonably request in order
to facilitate the disposition of Registrable Securities owned by them.


                                       5
<PAGE>

         (d) Use its best efforts to register and qualify the securities covered
by such registration statement under such other securities or Blue Sky laws of
such jurisdictions as shall be reasonably requested by the Holders, provided
that the Company shall not be required in connection therewith to qualify to do
business or to file a general consent to service of process in any such states
or jurisdictions.

         (e) In the event of any underwritten public offering, enter into and
perform its obligations under an underwriting agreement, in usual and customary
form, with the managing underwriter of such offering. Each Holder participating
in such underwriting shall also enter into and perform its obligations under
such an agreement.

         (f) Notify each Holder of Registrable Securities covered by such
registration statement at any time when a prospectus relating thereto is
required to be delivered under the Securities Act of the happening of any event
as a result of which the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing.

         (g) Furnish, at the request of any Holder requesting registration of
Registrable Securities pursuant to Sections 1 or 2, on the date that the
registration statement with respect to such securities becomes effective, (i) an
opinion, dated such date, of the counsel representing the Company for the
purposes of such registration, in form and substance as is customarily given to
underwriters in an underwritten public offering, addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities and
(ii) a letter dated such date, from the independent accountants of the Company,
in form and substance as is customarily given by independent accountants to
underwriters in an underwritten public offering, addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities.

         5. INDEMNIFICATION.

         (a) Except as otherwise provided below, the Company will indemnify each
Holder, each of its officers, directors, partners and legal counsel, and each
person controlling such Holder, participating in any registration, qualification
or compliance effected pursuant to this Agreement with respect to Registrable
Securities held by such Holder, and each underwriter, if any, and each person
who controls any underwriter, against all claims, losses, damages and
liabilities (or actions in respect thereof), including any of the foregoing
incurred in settlement of any litigation, commenced or threatened, to which they
may become subject under the Securities Act, the Securities Exchange Act of
1934, as amended (the "Exchange Act"), or other federal or state law, arising
out of or based on (i) any untrue statement (or alleged untrue statement) of a
material fact contained in any prospectus, offering circular or other similar
document (including any related registration statement, notification or the
like) incident to any such registration, qualification or compliance, or based
on any omission (or alleged omission) to state therein a material fact required
to be stated therein or necessary to make the statements therein not


                                       6
<PAGE>

misleading in the light of the circumstances under which they were made, or
(ii) any violation by the Company of any federal, state or common law rule or
regulation applicable to the Company in connection with any such
registration, qualification or compliance, and will reimburse each such
Holder, each of its officers, directors, partners and legal counsel, and each
person controlling such Holder, each such underwriter and each person who
controls any such underwriter, for any legal and any other expenses
reasonably incurred in connection with investigating or defending any such
claim, loss, damage, liability or action, as incurred, provided that the
Company will not be liable in any such case to the extent that any such
claim, loss, damage, liability or expense arises out of or is based on any
untrue statement or omission, made in reliance on and in conformity with
written information furnished to the Company by an instrument duly executed
by such Holder or underwriter and stated to be specifically for use therein.

         (b) Each Holder will, if Registrable Securities held by such Holder are
included in the securities as to which such registration, qualification or
compliance is being effected, indemnify the Company, each of its directors and
officers, each underwriter, if any, of the Company's securities covered by such
a registration statement, each person who controls the Company or such
underwriter within the meaning of the Securities Act, and each other Holder,
each of its officers, directors, and partners and each person controlling such
Holder, against all claims, losses, damages and liabilities (or actions in
respect thereof) arising out of or based on any untrue statement (or alleged
untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other similar document, 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 in the
light of the circumstances under which they were made, and will reimburse the
Company, such Holders, such directors, officers, persons, underwriters or
control persons for any legal or any other expenses reasonably incurred in
connection with investigating or defending any such claim, loss, damage,
liability or action, as incurred, in each case to the extent, but only to the
extent, that such untrue statement (or alleged untrue statement) or omission (or
alleged omission) is made in such registration statement, prospectus, offering
circular or other document in reliance upon and in conformity with written
information furnished to the Company by an instrument duly executed by such
Holder and stated to be specifically for use therein; provided, however, that
the obligations of such Holders hereunder shall be limited to an amount equal to
the proceeds to each such Holder of Registrable Securities sold as contemplated
herein.

         (c) Each party entitled to indemnification under this Section 5 (the
"Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has received written notice of any claim as to which indemnity may be sought,
and shall permit the Indemnifying Party to assume the defense of any such claim
or any litigation resulting therefrom, provided that counsel for the
Indemnifying Party, who shall conduct the defense of such claim or litigation,
shall be approved by the Indemnified Party (whose approval shall not
unreasonably be withheld). The Indemnified Party may participate in such defense
at such party's expense; provided, however, that the


                                       7
<PAGE>

Indemnifying Party shall bear the expense of such defense of the Indemnified
Party if representation of both parties by the same counsel would be
inappropriate due to actual or potential conflicts of interest. The failure
of any Indemnified Party to give notice as provided herein shall relieve the
Indemnifying Party of its obligations under this Section 5 only to the extent
that such failure to give notice shall materially adversely prejudice the
Indemnifying Party in the defense of any such claim or any such litigation.
No Indemnifying Party, in the defense of any such claim or litigation, shall,
except with the consent of each Indemnified Party, consent to entry of any
judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party of a release from all liability in respect to such claim or
litigation.

         6. INFORMATION BY HOLDER. The Holder or Holders of Registrable
Securities included in any registration shall furnish to the Company such
information regarding such Holder or Holders and the distribution proposed by
such Holder or Holders as the Company may request in writing and as shall be
required in connection with any registration, qualification or compliance
referred to in this Agreement.

         7. RULE 144 REPORTING. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Registrable Securities to the public without registration, after
such time as a public market exists for the Common Stock of the Company, the
Company agrees to:

         (a) Use its best efforts to facilitate the sale of the Registrable
Securities to the public, without registration under the Securities Act,
pursuant to Rule 144 under the Securities Act, provided that this shall not
require the Company to file reports under the Securities Act and the Exchange
Act at any time prior to the Company's being otherwise required to file such
reports;

         (b) Make and keep public information available, as those terms are
understood and defined in Rule 144 under the Securities Act at all times after
ninety (90) days after the effective date of the first registration under the
Securities Act filed by the Company for an offering of its securities to the
general public;

         (c) Use its best efforts to then file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act (at any time after it has become subject to
such reporting requirements);

         (d) So long as the Holders own any Registrable Securities to furnish to
the Holders forthwith upon request a written statement by the Company as to its
compliance with the reporting requirements of said Rule 144 (at any time after
ninety (90) days after the effective date of the first registration statement
filed by the Company for an offering of its securities to the general public),
and of the Securities Act and the Exchange Act (at any time after it has become
subject to such reporting requirements), a copy of the most recent annual or
quarterly report of the Company, and such other reports and documents so filed
by the Company as the Holders may


                                       8
<PAGE>

reasonably request in availing itself of any rule or regulation of the
Commission allowing the Holders to sell any such securities without
registration.

         8. "MARKET STAND-OFF" AGREEMENT. Each Holder agrees that if, at the
time, he or it holds more than 5% of the Company's voting stock (giving effect
to the exercise or conversions of all securities held by such Holder exercisable
for or convertible into voting stock within 180 days), such Holder will not sell
or otherwise transfer or dispose of any Common Stock (or other securities) of
the Company held by him or it during the one hundred eighty (180) day period
following the effective date of a registration statement of the Company filed
under the Securities Act if so requested by the Company and/or underwriter of
Common Stock (or other securities) of the Company, provided that:

         (a) all officers and directors of the Company and all other holders of
at least 5% of the Company's voting securities enter into similar agreements.
The Company may impose stop-transfer instructions with respect to the shares (or
securities) subject to the foregoing restriction until the end of such period;
and

         (b) such time period may be (i) waived or shortened by such
underwriter, or (ii) extended by written agreement among such underwriter and
the holders of a majority in interest of Registrable Securities.

         9. TRANSFER OF REGISTRATION RIGHTS. The registration rights granted
under Section 1 of this Agreement may be assigned or otherwise transferred by
any Holder to a transferee or all of such Holder's Registrable Securities and
the registration rights granted under Section 2 of this Agreement may be
transferred by any Holder to a transferee of all or any part of such Holder's
Registrable Securities; provided, however, that the Company is given (i) written
notice by such transferee at the time of or within a reasonable time after said
transfer, stating the name and address of said transferee and (ii) said
transferee's agreement to be bound by the provisions of this Agreement.

         10. GOVERNING LAW. This Agreement shall be governed by and construed in
accordance with the laws of the State of Nebraska applicable to contracts
between Nebraska residents entered into and to be performed entirely within the
State of Nebraska.

         11. SUCCESSORS AND ASSIGNS. Except as otherwise provided herein, the
provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, heirs, executors and administrators of the parties hereto.

         12. ENTIRE AGREEMENT. This Agreement constitutes the full and entire
understanding and agreement between the parties with regard to the subjects
hereof.

         13. NOTICES, ETC. All notices, requests and other communications to any
party hereunder shall be in writing (including telecopy or similar writing) and
shall be given to such


                                       9
<PAGE>

party at the address or telecopy number indicated for such party below or at
such other address or telecopy number as such party may hereafter specify by
notice to the other parties. Each such notice, request or other communication
shall be effective (i) if given by mail, 72 hours (but 120 hours in the case
of a communication to Cultor) after such communication is deposited in the
mails with first-class postage prepaid, addressed as aforesaid, (ii) if given
by telecopy, when such telecopy is transmitted to the telecopy number
specified in this paragraph and the party to which such telecopy is
transmitted orally confirms receipt, or (iii) if given by any other means,
when delivered at the address specified in this paragraph.

         (a)      If to the Company, to:

                  Bio Nebraska, Inc.
                  1695 Brower Road
                  Lincoln, Nebraska 68502

                  Telecopy number:  not applicable

                  With a copy to:

                  Thomas R. Coolidge, Esq.
                  Beebe Hill Road
                  Falls Village, Connecticut 06031

                  Telecopy number:  (203) 824-5770

         (b)      If to the Purchaser, to:

                  c/o Hillside Capital Incorporated
                  405 Park Avenue
                  New York, New York 10022

                  Telecopy number:  (212) 759-4831

         (c)      If to Wagner, Schuster or Wylie, to:

                  c/o Bio Nebraska, Inc.
                  1695 Brower Road
                  Lincoln, Nebraska 68502

                  Telecopy number:  not applicable


                                       10
<PAGE>

         (d)      If to Coolidge, to:

                  Beebe Hill Road
                  Falls Village, Connecticut 06031

                  Telecopy number:  (203) 824-5770

         (e)      If to Cultor, to:



         14. DELAYS OR OMISSIONS. No delay or omission to exercise any right,
power or remedy accruing upon any breach or default under this agreement, shall
be construed to be a waiver of any such breach or default, or an acquiescence
therein, or of or in any similar breach or default thereunder occurring; nor
shall any waiver of any single breach or default be deemed a waiver of any other
breach or default theretofore or thereafter occurring. Any waiver, permit,
consent or approval of any kind or character of any breach or default under this
agreement, or any waiver of any provisions or conditions of this agreement, must
be in writing and shall be effective only to the extent specifically set forth
in such writing. All remedies, either under this agreement, or by law or
otherwise afforded to any holder, shall be cumulative and not alternative.

         15. COUNTERPARTS. This agreement may be executed in any number of
counterparts, each of which may be executed by less than all of the parties,
each of which shall be enforceable against the parties actually executing such
counterparts, and all of which together shall constitute one instrument.

         16. SEVERABILITY. In the case any provision of this agreement shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

         17. AMENDMENTS. The provisions of this Agreement may be amended at any
time and from time to time, and particular provisions of this Agreement may be
waived, with and only with an agreement or consent in writing signed by the
Company and by the holders of eighty-five percent (85%) of the number of shares
of Registrable Securities outstanding as of the date of such amendment or
waiver. Each Holder acknowledges that by the operation of this Section the
holders of eighty-five percent (85%) of the outstanding Registrable Securities
may have the right and power to diminish or eliminate certain rights of such
Holder under this Agreement.


                                       11
<PAGE>

         The foregoing Registration Rights Agreement is hereby executed as of
the date first above written.

                                   BIO NEBRASKA, INC.


                                   By:/s/ Thomas R. Coolidge
                                      ----------------------------------------
                                       Name:
                                       Title: Chairman of the Board

                                   /s/ John N. Irwin III
                                   -------------------------------------------
                                   John N. Irwin III


                                   CULTOR LTD.


                                   By:/s/ Juha Koivurinta
                                      ----------------------------------------
                                      Name:
                                      Title:

                                   /s/ Fred W. Wagner
                                   -------------------------------------------
                                   Fred Wagner

                                   /s/ Sheldon Schuster
                                   -------------------------------------------
                                   Sheldon Schuster

                                   /s/ Dwane Wylie
                                   -------------------------------------------
                                   Dwane Wylie


                                   /s/ Thomas R. Coolidge
                                   -------------------------------------------
                                   Thomas R. Coolidge


                                       12
<PAGE>

                                    AMENDMENT
                                       TO
                BIO NEBRASKA, INC. REGISTRATION RIGHTS AGREEMENT

         This Amendment, dated as of November 22, 1989, is entered into among
Bio Nebraska, Inc., a Nebraska corporation having its principal place of
business at 1695 Brower Road, Lincoln, Nebraska 68502 (the "Company"); Hillside
Industries Incorporated, a Delaware corporation having its principal place of
business at 405 Park Avenue, New York, New York 10022 ("Hillside"); John N.
Irwin III, an individual with an address at 405 Park Avenue, New York, New York
10022 (the "Irwin"); Fred Wagner, an individual with an address at c/o Bio
Nebraska, Inc., 1695 Brower Road, Lincoln, Nebraska 68502; Sheldon Schuster, an
individual with an address at c/o Bio Nebraska, Inc., 1695 Brower Road, Lincoln,
Nebraska 68502; Thomas R. Coolidge, an individual with an address at c/o Bio
Nebraska, Inc., 1695 Brower Road, Lincoln, Nebraska 68502 ("Coolidge"); Dwane
Wylie, an individual with an address at c/o Bio Nebraska, Inc. 1695 Brower Road,
Lincoln, Nebraska 68502; and Cultor, Ltd., a Finnish corporation having its
principal place of business in Finland ("Cultor").

                                    RECITAL:

         A. The Company is issuing 123 shares of its Common Stock to Hillside
pursuant to a Securities Purchase Agreement, dated the date hereof;

         B. Cultor is selling to Hillside 136 shares of the Company's Common
Stock pursuant to a Common Stock Purchase Agreement, dated the date hereof (the
"Cultor Agreement") (such 136 shares, together with the 123 shares being
acquired by Hillside from the Company and any and all other shares of the
Company's Common Stock acquired by Hillside prior to the first underwritten
public offering of the Company's Common Stock, are referred to herein as the
"Hillside Shares");

         C. Cultor is selling to Coolidge 90 shares of the Company's Common
Stock pursuant to the Cultor Agreement (such 90 shares, together with any and
all other shares of the Company's Common Stock acquired by Coolidge from Cultor
after the date hereof and prior to the first underwritten public offering of the
Company's Common Stock, are referred to herein as the "Coolidge Investment
Shares");

         D. The Holders desire to set forth the registration rights to be
granted to Hillside and Coolidge in connection with the securities of the
Company to be held by Hillside and Coolidge.

                                   AGREEMENT:

         NOW, THEREFORE, the parties (being the holders of at least 85% of the
Registrable Securities of the Company outstanding as of the date of this
Amendment) do, for good and

<PAGE>

valuable consideration, hereby mutually agree to the following amendments to
the Registration Rights Agreement of the Company, dated as of July 13, 1989
(the "Agreement"):

         1.(a) The registration rights granted to the Holders pursuant to
Sections 1 and 2 of the Agreement are extended to Hillside as the holder of the
Hillside Shares, all on the same terms and conditions of the Agreement as are
applicable to the Registrable Securities held by Cultor (such that Hillside is
entitled to two requested registrations pursuant to Section 1 of the Agreement).

         1.(b) The registration rights granted to the Holders pursuant to
Sections 1 and 2 of the Agreement are extended to Coolidge as the holder of the
Coolidge Investment Shares (but to Coolidge only in respect of the Coolidge
Investment Shares and not in respect of share of the Company's Common Stock held
by Coolidge that are included with the term "Manager Shares" as defined in the
Agreement), all on the same terms and conditions of the Agreement as are
applicable to the Registrable Securities held by Irwin (such that Coolidge is
entitled to one requested registration pursuant to Section 1 of the Agreement in
respect of the Coolidge Investment Shares).

         2. Any reference in the Agreement to the term "Registrable Securities"
shall be deemed to include the Hillside Shares and the Coolidge Investment
Shares, provided that, wherever the term "Registrable Securities" is used in the
Agreement with reference to Coolidge as an individual Holder (and not as one of
the Managers), the term "Registrable Securities" shall be deemed to include only
the Coolidge Investment Shares and not those shares of the Company's Common
Stock held by Coolidge that are included within the term "Manager Shares" as
defined in the Agreement.

         3. Any reference in the Agreement to the term "Holders" shall be deemed
to include Hillside as the holder of the Hillside Shares and Coolidge as the
holder of the Coolidge Investment Shares.

         4. All capitalized terms used and not defined herein shall the meanings
ascribed to them in the Agreement.

         5. This Amendment may be executed in counterparts, each of which shall
be an original, but all of which together shall constitute one and the same
agreement.

         6. This Amendment shall be governed by and construed in accordance with
the laws of the State of Nebraska applicable to contracts between Nebraska
residents entered into and to be performed entirely within the State of
Nebraska.

         7. Except as amended hereby, the Agreement shall continue in full force
and effect in accordance with the provisions thereof in effect on the date of
execution and delivery of this Amendment. As used in the Agreement, all
references to the terms "Agreement", "hereof",


                                       2
<PAGE>

"hereby" or the like shall mean the Agreement as amended by this Amendment
unless the context specifically requires otherwise.

         IN WITNESS WHEREOF, this Amendment has been executed by each of the
parties hereto (or their duly authorized officers) all as of the year and day
first above written.


                                   BIO NEBRASKA, INC.


                                   By:/s/ Thomas R. Coolidge
                                      ---------------------------------
                                   Name:
                                   Title: Chairman of the Board

                                   HILLSIDE INDUSTRIES INCORPORATED


                                   By: /s/ John N. Irwin III
                                      ----------------------------------
                                   Name: John N. Irwin III
                                   Title: Managing Director

                                   CULTOR LTD.


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

                                   /s/ John N. Irwin III
                                   ------------------------------------
                                   John N. Irwin III

                                   /s/ Thomas R. Coolidge
                                   ------------------------------------
                                   Thomas R. Coolidge


                                   ------------------------------------
                                   Fred Wagner


                                   ------------------------------------
                                   Sheldon Schuster


                                   ------------------------------------
                                   Dwane Wylie


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