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SMlTHSONlAN SCI NCE INFORMATION           U.S. DEPARTMENT OF       PROJECT NUMBER                   <

PROJECT NUMBER  Do NOT use this space   HEALTH EDUCATION AND WELFARE
            P~BLl~D~~~~T~FSERVICE
                INTRAMRAL RES;ARCH PROJECT    ZOl HI, 00011-02 LBG

PER IO0 COVERED

July 1, 1975 through June 30, 1976.
TITLE OF PROJECT (80 characters or less)

The Development of Chick Embryo Retina

FIAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AN0 TITLES OF PRINCIPAL INVESTIGATORS AN0 ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT

PI:  F. G. DeMello     Visiting Associate             LBG NHLI
  Marshall Mirenberg Chief, LBG                   LBG NHLI

COOPERATING UNITS (if any)

None

I

LAB/BRANCH
Laboratory of Biochemical Genetics
SECTION
Section on Molecular Biology
INSTITUTE AN0 LOCATION
NHLI, NIH, Bethesda, Maryland 20014
TOTAL MANYEARS:         PROFESS I ONAL:
    1.2              1.2

I OTHER:

                         I                        I
SUMMARY OF WORK (200 words or less - underline keywords)

  Some biochemical aspects of chick embryo retina differentiation were
studied:  1) An alternate route for'GABA synthesis. was characterized in the
retina; which depends  upon the conversion of               2) Glutamic
acid decarboxylase specific activity in the retina, increased during the course

of embrtonic development, either when measured'in ovo or in'gggregate cultures.
                                                     -w
3) The presence of GABA in the culture medium prevented the development of
glutamic acid decarboxylase activity in aggregate cultures.  4) The proposed
course of this project is to attempt to correlate the biochemical changes
observed, with.synaptogenesis in the retina.

PHS-6040
(12-75)


201 HL 0001142 LBG

Project Description:

Objectives:  The objective of the project is to study the biochemical
step required for synaptogenesis in chick embryo retina.

Major Findings: Two.pathways for y-aminobutyric acid synthesis were found
in chick embryo retina.  The first pathway depends upon the conversion of
putrescine to ornithine decarboxylase and the subsequent conversion of
ornithing to y-aminobutyric acid.  The second route of synthesis is dependent
upon the conversion of glutamic acid to y-aminobutyric acid, catalyzed by
glutamic acid decarboxylase.  Elevation of CAMP levels in neuroblastoma cells
was shown to induce ornithioe decarboxplase activity.  Thus, in the develop-
ing :.embryo, neurotransmitters which affect CAMP levels may regulate ornithine
decarboxylase activity and thereby control the rate of GABA synthesis from
ornithine.

Proposed Course:  To determine the effect of retina neurotransmitters
and other compounds on retina synaptogenesis.

Publications:

1.  DeMello, F. G., Bachrach, U. and Nirenberg, M.: Ornithine and glutamic
acid decarboxylase activities in the developing retina.  J. Neurochem. In
Press.