Difference between male and female rats in vasopressor response to arginine vasopressin

A study was carried out how the sexual difference influences the increase in blood pressure (BP) induced by arginine vasopressin (AVP), and how the binding characteristics of 3H-labelled AVP on membranes prepared from the vascular bed were affected. After the administration of various doses of AVP, a significantly higher BP increase was observed in male rats than in females. The vasopressor effect of AVP was reduced in males following orchidectomy or administration of the antiandrogen cyproterone acetate. The vasopressin (VP) antagonist d(CH2)5Tyr(Me)AVP diminished the BP response to AVP in both sexes. The plasma AVP level was found to be much higher in males than in females, but it was decreased to the level of females after orchidectomy. The density of AVP-binding sites in the aorta membrane preparation was smaller in females, and in orchidectomized or cyproterone acetate-treated male rats than in the control males. The results demonstrate that testosterone upregulates the number of AVP-binding sites, leading to an increase in the pressor response to AVP in the rat vascular bed

Sensory cutaneous papillae in the sea lamprey (Petromyzonmarinus L.) : I. Neuroanatomy and physiology

Molecules present in an animal's environment can indicate the presence of predators,food, or sexual partners and consequently, induce migratory, reproductive, foraging,or escape behaviors. Three sensory systems, the olfactory, gustatory, and solitarychemosensory cell (SCC) systems detect chemical stimuli in vertebrates. While agreat deal of research has focused on the olfactory and gustatory system over theyears, it is only recently that significant attention has been devoted to the SCC sys-tem. The SCCs are microvillous cells that were first discovered on the skin of fish,and later in amphibians, reptiles, and mammals. Lampreys also possess SCCs that areparticularly numerous on cutaneous papillae. However, little is known regarding theirprecise distribution, innervation, and function. Here, we show that sea lampreys(Petromyzon marinus L.) have cutaneous papillae located around the oral disk, nostril,gill pores, and on the dorsal fins and that SCCs are particularly numerous on thesepapillae. Tract-tracing experiments demonstrated that the oral and nasal papillae areinnervated by the trigeminal nerve, the gill pore papillae are innervated by branchialnerves, and the dorsal fin papillae are innervated by spinal nerves. We also character-ized the response profile of gill pore papillae to some chemicals and showed thattrout-derived chemicals, amino acids, and a bile acid produced potent responses.Together with a companion study (Suntres et al., Journal of Comparative Neurology,this issue), our results provide new insights on the function and evolution of the SCCsystem in vertebrates

Codivergence of Mycoviruses with Their Hosts

BACKGROUND: The associations between pathogens and their hosts are complex and can result from any combination of evolutionary events such as codivergence, switching, and duplication of the pathogen. Mycoviruses are RNA viruses which infect fungi and for which natural vectors are so far unknown. Thus, lateral transfer might be improbable and codivergence their dominant mode of evolution. Accordingly, mycoviruses are a suitable target for statistical tests of virus-host codivergence, but inference of mycovirus phylogenies might be difficult because of low sequence similarity even within families. METHODOLOGY: We analyzed here the evolutionary dynamics of all mycovirus families by comparing virus and host phylogenies. Additionally, we assessed the sensitivity of the co-phylogenetic tests to the settings for inferring virus trees from their genome sequences and approximate, taxonomy-based host trees. CONCLUSIONS: While sequence alignment filtering modes affected branch support, the overall results of the co-phylogenetic tests were significantly influenced only by the number of viruses sampled per family. The trees of the two largest families, Partitiviridae and Totiviridae, were significantly more similar to those of their hosts than expected by chance, and most individual host-virus links had a significant positive impact on the global fit, indicating that codivergence is the dominant mode of virus diversification. However, in this regard mycoviruses did not differ from closely related viruses sampled from non-fungus hosts. The remaining virus families were either dominated by other evolutionary modes or lacked an apparent overall pattern. As this negative result might be caused by insufficient taxon sampling, the most parsimonious hypothesis still is that host-parasite evolution is basically the same in all mycovirus families. This is the first study of mycovirus-host codivergence, and the results shed light not only on how mycovirus biology affects their co-phylogenetic relationships, but also on their presumable host range itself

Autoradiographic localization of V₁ vasopressin binding sites in rat brain and kidney

Monoiodination of the V1 vasopressin antagonist [Mca1,Sar7]AVp did not alter its high-affinity binding to liver plasma membranes. Monoradioiodinated [Mca1,125I-Tyr2,Sar7]AVP was therefore used to label V1-specific binding sites in the rat brain and kidney. The accumbens nucleus, the septal nucleus, the central amygdala, the bed nucleus of the stria terminalis, the stigmoid hypothalamic nucleus and the nucleus of the solitary tract exhibited specific labeling with both the radioiodinated V1 antagonist and tritiated AVP. Of the circumventricular structures only the choroid plexi and the area postrema showed V1-specific binding sites. The subfornical organ and hypothalamic loci of AVP synthesis such as the paraventricular nucleus, the supraoptic nucleus and the suprachiasmatic nucleus were not marked by the V1 antagonist while bearing [3H]AVP binding sites. As demonstrated by HPLC and binding to liver plasma membranes, the radiolabeled antagonist remained intact during tissue incubation. In addition to renal cortical and medullary [3H]AVP binding sites, medullary tubular and vascular structures could be labeled with the V1 antagonist, indicating the presence of both V1 and V2 AVP receptor subtypes in the rat kidney