Dr. Stevens is also Professor at the Salk Institute 
for Biological Studies and Adjunct Professor of 
Pharmacology at the University of California 
School of Medicine, San Diego. 
Books and Chapters of Books 
Jen, J., and Stevens, C.F. 1992. Neuromodulation 
of non-NMDA class glutamate receptor channels 
in hippocampal neurons. In Excitatory Amino 
Acids and Second Messenger Systems (Teich- 
berg, V.I., and Turski, L., Eds.). New York: 
Springer- Verlag, vol 3, pp 153-168. 
Articles 
Bekkers, J.M., and Stevens, C.F. 1991. Excitatory 
and inhibitory autaptic currents in isolated hip- 
pocampal neurons maintained in cell culture. 
Proc Natl Acad Sci USA 88:7834-7838. 
Bettler, B., Egebjerg, J., Sharma, G., Pecht, G., Her- 
mans-Borgmeyer, 1., Moll, C, Stevens, C.F., and 
Heinemann, S. 1992. Cloning of a putative gluta- 
mate receptor: a low affinity kainate-binding sub- 
unit. Neuron 8:257-265. 
Chavez-Noriega, L.E., and Stevens, C.F. 1992. 
Modulation of synaptic efficacy in field CAl of the 
rat hippocampus by forskolin. Brain Res 
574:85-92. 
Greengard, P., Jen, J., Nairn, A.C., and Stevens, C.F. 
1 99 1 . Enhancement of the glutamate response by 
cAMP-dependent protein kinase in hippocampal 
neurons. 5c/e«ce 253:1 135-1 138. 
Ranganathan, R., Harris, G.L., Stevens, C.F., and 
Zuker, C.S. 1 99 1 ■ A Drosophila mutant defective 
in extracellular calcium-dependent photorecep- 
tor deactivation and rapid desensitization. Nature 
354:230-232. 
Silva, A.J., Stevens, C.F., Tonegawa, S., and Wang, 
Y. 1992. Deficient hippocampal long-term po- 
tentiation in a-calcium-calmodulin kinase II mu- 
tant mice. Science 257:201-206. 
Stevens, C.F. 1992. Just say NO. Curr Biol 2:108- 
109. 
CELL AND BODY PATTERNING IN DROSOPHILA 
Gary Struhl, Ph.D., Associate Investigator 
Dr. Struhl's research is focused on the molecular 
nature and mode of action of spatial determinants 
responsible for organizing cell and body patterns in 
Drosophila. The basic body pattern of head, tho- 
racic, and abdominal segments is prefigured at fertil- 
ization by distinct anterior, posterior, and terminal 
determinant systems laid down in the egg during 
oogenesis. All three systems operate in the early, 
syncytial embryo in which signaling molecules can 
diffuse from one region to another through a com- 
mon cytoplasm. Later, spatial signals must be locally 
generated in some cells and passed to others. The 
roles of the three early determinant systems, as well 
as the molecular mechanisms involved in their es- 
tablishment and function, are under investigation. A 
general method has also been developed for analyz- 
ing the roles of putative signaling molecules in 
later, cellular systems. 
Early Determinant Systems 
Prior work by Dr. Christiane Niisslein-Volhard 
and her colleagues has established that two morpho- 
gens, bicoid (bed) and nanos (nos), are responsi- 
ble for specifying most aspects of anteroposterior 
body pattern. Recent studies in Dr. Struhl's labora- 
tory have established that bed and nos act at least in 
part by blocking the accumulation of protein from 
uniformly distributed maternal transcripts of the 
caudal (cad) and hunchback (hb) genes. The in- 
volvement of bed in regulating cad protein expres- 
sion is interesting because bed is a homeodomain 
protein, and previous work in Dr. Struhl's laboratory 
has established 1) that it can directly bind and tran- 
scriptionally activate subordinate regulatory genes 
and 2) that single-amino acid changes in the ho- 
meodomain that alter DNA-binding specificity also 
prevent the regulation of cad protein expression. 
Hence it is possible that bed may bind and transla- 
tionally regulate cad mRNA via the homeodomain. 
For nos, recent experiments of Drs. Struhl, Robin 
Wharton, and Peter Lawrence have established 1) 
that the sole role of nos in generating posterior body 
pattern is its regulation of hb protein expression, 2) 
that this regulation depends critically on small cis- 
acting sequences in the hb transcript, and 3) that 
the resulting gradient of hb protein, a zinc finger 
transcription factor, specifies posterior body pat- 
tern by activating or repressing downstream regula- 
tory genes in a concentration-dependent fashion. 
Thus concentration-dependent binding of hb mRNA 
442 
