The Fem1c genes: conserved members of the Fem1 gene family in vertebrates.

The fem-1 gene of Caenorhabditis elegans functions in a signaling pathway that controls sex determination. Homologs of fem-1 in mammals have been characterized, consisting of two family members, Fem1a and Fem1b. We report here on Fem1c, a third member of the Fem1 gene family, in three vertebrate species: human, mouse, and zebrafish. The proteins encoded by these Fem1c genes share >99% amino acid identity between human and mouse, 79% amino acid identity between mouse and zebrafish, and end with a C-terminal Arginine residue, which distinguishes them from other FEM-1 proteins reported thus far. The human and mouse Fem1c coding regions show conservation of intron-exon structure and expression pattern in adult tissues. Human FEM1C maps to 5q22, mouse Fem1c maps to chromosome 18, and zebrafish fem1c maps to Linkage Group 8. The Fem1c genes in vertebrates may play a conserved role in the development and/or physiologic function of these organisms.

Age-dependent reductions in the level of glial fibrillary acidic protein in the prefrontal cortex in major depression.

The density of glial cells is reduced in certain layers of the dorsolateral prefrontal cortex in major depressive disorder (MDD). Moreover, there are reductions in the packing density of glial fibrillary acidic protein (GFAP) immunoreactive astrocytes in the same cortical layers in younger subjects with MDD. The objective of the present study was to test if the level of GFAP is preferentially decreased in younger subjects with MDD, and whether GFAP levels are correlated with the age of onset of depression. Post-mortem brain tissue punches from dorsolateral prefrontal cortex were collected from 15 subjects with MDD and 15 age-matched psychiatrically normal control subjects. Western blots were performed on gels containing duplicated samples from both subjects of each matched pair, and on gels containing samples at different ages from either the MDD or the control group. The GFAP level was calculated as the ratio of the optical density of GFAP bands to actin bands in subjects with MDD and nonpsychiatric controls. Levels of GFAP were significantly lower in subjects with MDD as compared to controls and this decrease was most prominent in subjects less than 60 years old at the time of death. In the MDD group, GFAP levels were positively correlated with age at the time of death and show a trend toward correlation with the age of onset of depression. These findings indicate that a decrease in levels of GFAP may contribute to the pathophysiology of MDD, particularly in subjects of relatively young age.

Afferent innervation of the utricular macula in pigeons.

Biotinylated dextran amine (BDA) was used to retrogradely label afferents innervating the utricular macula in adult pigeons. The pigeon utriclar macula consists of a large rectangular-shaped neuroepithelium with a dorsally curved anterior edge and an extended medioposterior tail. The macula could be demarcated into several regions based on cytoarchitectural differences. The striola occupied 30% of the macula and contained a large density of type I hair cells with fewer type II hair cells. Medial and lateral extrastriola zones were located outside the striola and contained only type II hair cells. A six- to eight-cell-wide band of type II hair cells existed near the center of the striola. The reversal line marked by the morphological polarization of hair cells coursed throughout the epithelium, near the peripheral margin, and through the center of the type II band. Calyx afferents innervated type I hair cells with calyceal terminals that contained between 2 and 15 receptor cells. Calyx afferents were located only in the striola region, exclusive of the type II band, had small total fiber innervation areas and low innervation densities. Dimorph afferents innervated both type I and type II hair cells with calyceal and bouton terminals and were primarily located in the striola region. Dimorph afferents had smaller calyceal terminals with few type I hair cells, extended fiber branches with bouton terminals and larger innervation areas. Bouton afferents innervated only type II hair cells in the extrastriola and type II band regions. Bouton afferents innervating the type II band had smaller terminal fields with fewer bouton terminals and smaller innervation areas than fibers located in the extrastriolar zones. Bouton afferents had the most bouton terminals on the longest fibers, the largest innervation areas with the highest innervation densities of all afferents. Among all afferents, smaller terminal innervation fields were observed in the striola and large fields were located in the extrastriola. The cellular organization and innervation patterns of the utricular maculae in birds appear to represent an organ in adaptive evolution, different from that observed for amphibians or mammals.