Age- and sex-related differences in baboon (Papio anubis) gray matter covariation.

Age-related changes in cognition, brain morphology, and behavior are exhibited in several primate species. Baboons, like humans, naturally develop Alzheimer's disease-like pathology and cognitive declines with age and are an underutilized model for studies of aging. To determine age-related differences in gray matter covariation of 89 olive baboons (Papio anubis), we used source-based morphometry (SBM) to analyze data from magnetic resonance images. We hypothesized that we would find significant age effects in one or more SBM components, particularly those which include regions influenced by age in humans and other nonhuman primates (NHPs). A multivariate analysis of variance revealed that individual weighted gray matter covariation scores differed across the age classes. Elderly baboons contributed significantly less to gray matter covariation components including the brainstem, superior parietal cortex, thalamus, and pallidum compared to juveniles, and middle and superior frontal cortex compared to juveniles and young adults (p < 0.05). Future studies should examine the relationship between the changes in gray matter covariation reported here and age-related cognitive decline.

Phenotypic and genetic associations between gray matter covariation and tool use skill in chimpanzees (Pan troglodytes): Repeatability in two genetically isolated populations.

Humans and chimpanzees both exhibit a diverse set of tool use skills which suggests selection for tool manufacture and use occurred in the common ancestors of the two species. Our group has previously reported phenotypic and genetic associations between tool use skill and gray matter covariation, as quantified by source-based morphometry (SBM), in chimpanzees. As a follow up study, here we evaluated repeatability in heritability in SBM components and their phenotypic association with tool use skill in two genetically independent chimpanzee cohorts. Within the two independent cohorts of chimpanzees, we identified 8 and 16 SBM components, respectively. Significant heritability was evident for multiple SBM components within both cohorts. Further, phenotypic associations between tool use performance and the SBM components were largely consistent between the two cohorts; the most consistent finding being an association between tool use performance and an SBM component including the posterior superior temporal sulcus (STS) and superior temporal gyrus (STG), and the interior and superior parietal regions (p < 0.05). These findings indicate that the STS, STG, and parietal cortices are phenotypically and genetically implicated in chimpanzee tool use abilities.

Selenium assimilation and volatilization from dimethylselenoniopropionate by Indian mustard.

Earlier work from our laboratory on Indian mustard (Brassica juncea L.) identified the following rate-limiting steps for the assimilation and volatilization of selenate to dimethyl selenide (DMSe): (a) uptake of selenate, (b) activation of selenate by ATP sulfurylase, and (b) conversion of selenomethionine (SeMet) to DMSe. The present study showed that shoots of selenate-treated plants accumulated very low concentrations of dimethylselenoniopropionate (DMSeP). Selenonium compounds such as DMSeP are the most likely precursors of DMSe. DMSeP-supplied plants volatilized Se at a rate 113 times higher than that measured from plants supplied with selenate, 38 times higher than from selenite, and six times higher than from SeMet. The conversion of SeMet to selenonium compounds such as DMSeP is likely to be rate-limiting for DMSe production, but not the formation of DMSe from DMSeP because DMSeP was the rate of Se volatilization from faster than from SeMet and SeMet (but no DMSeP) accumulated in selenite- or SeMet-supplied wild-type plants and in selenate-supplied ATP-sulfurylase transgenic plants. DMSeP-supplied plants absorbed the most Se from the external medium compared with plants supplied with SeMet, selenate, or selenite; they also accumulated more Se in shoots than in roots as an unknown organic compound resembling a mixture of DMSeP and selenocysteine.

Inhibition of gastric and pancreatic secretion in dogs by CGRP: role of somatostatin.

The coexistence of calcitonin gene-related peptide (CGRP) and somatostatin (SS) within the stomach and pancreas and the potent inhibitory effects of both peptides on exocrine secretions from these organs suggest that they are functionally related. To assess the potential role of SS in the mediation of CGRP action, the effects of intravenous human CGRP (64, 132, and 264 pmol.kg-1.h-1) and somatostatin-14 (SS-14; 100, 400, and 800 pmol.kg-1.h-1) on plasma levels of SS immunoreactivity (SS-IR) and on pentagastrin-stimulated gastric and pancreatic secretion were compared in conscious dogs. CGRP caused significant inhibition of gastric acid (85-102%), pancreatic protein (63-86%), and pancreatic bicarbonate (74-89%) outputs and a simultaneous dose-related rise (40-102 fmol/ml) in plasma SS-IR. Cessation of CGRP infusion resulted in prompt return of plasma SS-IR to basal levels and an increase in gastric and pancreatic secretion. Although CGRP is a potent releasor of SS into the circulation, its inhibitory action on gastric acid secretion cannot be explained solely by a rise in plasma SS-IR. In the pancreas, in contrast to the stomach, inhibition appears to be more closely related to a rise in circulating level of SS-IR.