Genetic analysis of factors affecting risk to develop excessive ethanol drinking has been extensively studied in humans and animal models for over 20 years. However, little progress has been made in determining molecular mechanisms underlying environmental or non-genetic events contributing to variation in ethanol drinking. Here, we identify persistent and substantial variation in ethanol drinking behavior within an inbred mouse strain and utilize this model to identify gene networks influencing such “non-genetic” variation in ethanol intake. C57BL/6NCrl mice showed persistent inter-individual variation of ethanol intake in a two-bottle choice paradigm over a three-week period, ranging from less than 1 g/kg to over 14 g/kg ethanol in an 18 h interval. Differences in sweet or bitter taste susceptibility or litter effects did not appreciably correlate with ethanol intake variation. Whole genome microarray expression analysis in nucleus accumbens, prefrontal cortex and ventral midbrain region of individual animals identified gene expression patterns correlated with ethanol intake. Results included several gene networks previously implicated in ethanol behaviors, such as glutamate signaling, BDNF and genes involved in synaptic vesicle function. Additionally, genes functioning in epigenetic chromatin or DNA modifications such as acetylation and/or methylation also had expression patterns correlated with ethanol intake. In verification for the significance of the expression findings, we found that a histone deacetylase inhibitor, trichostatin A, caused an increase in 2-bottle ethanol intake. Our results thus implicate specific brain regional gene networks, including chromatin modification factors, as potentially important mechanisms underlying individual variation in ethanol intake.

The mesopelagic shrimp Sergestes similis emits ventrally directed bioluminescence that closely matches the intensity of downward-directed illumination and is able to rapidly modify its light output to match changes in background intensity. Masking experiments show that the photoreceptors involved are the compound eyes or adjacent tissues. Light emission originates from modified portions of the hepatopancreas and is similar to oceanic light in angular distribution and spectral characteristics. Normally oriented animals respond minimally to upward-directed light.

The light generating-systems of Porichthys notatus, the midshipman fish, cross react with those of the ostracocl I 7 argnla ( = Cypridind) hilgendorfii (Cormier et al., 1967), indicating that Porichthys might be able to utilize exogenous luciferin to support luminescence. This remarkable possibility is not wholly unexpected since some fishes in the two genera Apogon and Parapriacanthus are thought to acquire their luciferin from a sympatric ostracod, V. hilgendorfii (Haneda et al., 1966(Haneda et al., , 1969Tsuji et al., 1971). The research reported here reinforces possible dependence of the midshipman on an exogenous luciferin. P. notatus occurs in coastal waters from Baja California to Southeastern Alaskan waters (Wilimovski, 1954), a range encompassing many kinds of luminescent organisms which might furnish luciferin (Tsuji et al., 1971). However, luminescent ostracods, the most likely dietary source of luciferin, were not known to occur within the range of the midshipman until Kornicker and Baker (1977) described Vargula tsitjii (Mycopoda; Cyprindinae). The existence of a luminescent ostracod closely related to V . hilgendorfii but, unlike it, sympatric with the southern

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