Conserved beta-tubulin binding domain for the microtubule-associated motors underlying sperm motility and fast axonal transport.

An antiserum against tubulin, NS20, has been previously shown to inhibit anterograde and retrograde axonal transport by 50% in vivo and in vitro. We report here that Protein A purified NS20 antibodies also attenuate sperm motility by 50% in demembranated sea urchin sperm. This inhibition is absorbed out by preincubating the NS20 antibodies with a biochemically purified porcine microtubule preparation, with recombinant Trypanosoma beta- (but not alpha-) tubulin and most specifically, with a 37 amino acid (a.a.) synthetic peptide corresponding to a domain near (but not including) the porcine beta-tubulin C terminus. Furthermore, addition of this beta-tubulin peptide alone is sufficient to attenuate motility by 50% in demembranated sperm, indicating that this critical 37a.a. NS20 antigen is a motor binding domain. Together, the results suggest that at least two phenotypically distinct forms of microtubule-based motility, axonal transport and flagellar beating, are homologous at the fundamental level of the microtubule domains (the beta-tubulin peptide and we suggest a distinct but similarly located alpha-tubulin domain) mediating the attachment of tubulin-associated motors.     

Maternal prenatal depressive symptoms predict infant NR3C1 1F and BDNF IV DNA methylation

Prenatal maternal psychological distress increases risk for adverse infant outcomes. However, the biological mechanisms underlying this association remain unclear. Prenatal stress can impact fetal epigenetic regulation that could underlie changes in infant stress responses. It has been suggested that maternal glucocorticoids may mediate this epigenetic effect. We examined this hypothesis by determining the impact of maternal cortisol and depressive symptoms during pregnancy on infant NR3C1 and BDNF DNA methylation. Fifty-seven pregnant women were recruited during the second or third trimester. Participants self-reported depressive symptoms and salivary cortisol samples were collected diurnally and in response to a stressor. Buccal swabs for DNA extraction and DNA methylation analysis were collected from each infant at 2 months of age, and mothers were assessed for postnatal depressive symptoms. Prenatal depressive symptoms significantly predicted increased NR3C1 1F DNA methylation in male infants (β = 2.147, P = 0.044). Prenatal depressive symptoms also significantly predicted decreased BDNF IV DNA methylation in both male and female infants (β = −3.244, P = 0.013). No measure of maternal cortisol during pregnancy predicted infant NR3C1 1F or BDNF promoter IV DNA methylation. Our findings highlight the susceptibility of males to changes in NR3C1 DNA methylation and present novel evidence for altered BDNF IV DNA methylation in response to maternal depression during pregnancy. The lack of association between maternal cortisol and infant DNA methylation suggests that effects of maternal depression may not be mediated directly by glucocorticoids. Future studies should consider other potential mediating mechanisms in the link between maternal mood and infant outcomes.     

A model for the functioning of the striatum

A model is presented for the operation of the striatum. The model posits that the basal ganglia are responsible for driving smooth transitions of state for an organism. We propose that this is accomplished through the computation of a potential function within the striatum on which a gradient descent is performed toward the goal state. The model suggests that various somatotopic regions of the striatum correspond to state spaces, each of which pertains to a different aspect of the organism. This paper discusses this model only in the context of motor control, i.e., egomotion and limb movement. The model appears to account for a variety of experimental results, and for some unusual properties of the striatum.     

Testosterone 5 alpha-reductase activity in neural tissue of fetal rhesus macaques

After development of a 5 alpha-reductase activity (5 alpha-RA) assay based on the capacity of microsomes to convert [3H]testosterone (T) to [3H]dihydrotestosterone (DHT), we analyzed 5 alpha-RA in neural tissues of fetal rhesus macaques at 50, 80 and 150 days of gestation. This method allowed us to collect kinetic data on the properties of the 5 alpha-reductase resident in fetal brain at 150 days of gestation. The Km and Vmax calculated from these data were 4.32 microM and 22.6 nmol.mg protein-1.h-1, respectively. Analyses of 5 alpha-RA in microsomes from the hypothalamic-preoptic area-amygdala (HPA) at dilutions of 1/25 and 1/50 indicated higher enzyme activity with increasing dilution of the microsomes. Measurement of 5 alpha-RA using concentrations of [3H]T which saturated the enzyme in diencephalon (DIEN), brain stem (B.STEM), temporal (TCTX) and frontal cortex (FCTX) of six 50-day old fetuses (3 males and 3 females) revealed no obvious sex differences in 5 alpha-RA, however, a significant difference (P less than 0.05) between tissues was noted. The DIEN and B.STEM contained significantly (P less than 0.05) higher levels 5 alpha-RA than the FCTX while the TCTX contained an intermediate level of activity. Significant increases in 5 alpha-RA were observed in FCTX and TCTX with time of gestation (50, 80 and 150 days). Other tissues, including amygdala, hippocampus, cerebellum, tegmentum and septum also change with fetal age. These data demonstrate the existence of 5 alpha-reductase in the fetal monkey brain. Significant changes in cortical 5 alpha-RA suggest some role for 5 alpha-reductase in development.     

In vivo assessment of tumor-induced nonspecific suppression of contact sensitivity

Summary Normal BALB/c mice were assessed for 2,4-dinitrofluorobenzene (DNFB)-induced contact sensitivity following adoptive transfer of macrophages (Mo). T cells, or their derived products, from normal or tumor-bearing hosts (TBH). Contact sensitivity (CS) was measured by a quantitative radioisotopic ear assay, a total in vivo system based on localization of IP-injected iodinated human serum albumin ([¹²⁵I]HSA) in the DNFB-challenged ear. Adoptive transfer of low or high doses of TBH T cells or their derived supernatants into normal recipients suppresed their responsiveness, while Mo supernatants enhanced it. Moreover, in all cases adoptive transfer of TBH cells or supernatants resulted in a lower CS response than did their normal counterparts. These results further corroborate our previous in vitro data indicating that T cells, or Mo and T cell soluble products, possess immunoregulatory capabilities in vivo.Abbreviations DNFB 2,4-dinitrofluorobenzene - TBH tumor-bearing host - Mo macrophages - ¹²⁵I-HSA iodinated-human serum albumin - CMI cell-mediated immunity - CS contact sensitivity; Ig, immunoglobulin - C complement