Carboxylate polyanions accelerate inhibition of thrombin by heparin cofactor II

The heparin cofactor II (HCII)/thrombin inhibition reaction is enhanced by various carboxylate polyanions. In the presence of polyaspartic acid, the HCII/thrombin reaction is accelerated more than 1000-fold with the second-order rate constant increasing from 3.2 x 10(4) M-1 min-1 (in the absence of polyAsp) to 3.6 x 10(7) M-1 min-1 as the polyAsp concentration is increased from 1 to 250 micrograms/ml. This accelerating effect was observed for HCII/thrombin, though to varying degrees, with other carboxylate polyanions. In contrast to HCII, the rate of antithrombin III inhibition of thrombin was decreased in the presence of polyAsp. The HCII/thrombin complex is rapidly formed in the presence of 10 micrograms/ml polyAsp when 125I-labeled-thrombin is incubated with plasma. It is possible that at physiological sites rich in carboxylate polyanions, thrombin may be preferentially inhibited by HCII.     

Evaluating morphometric and metabolic markers of body condition in a small cetacean,the harbor porpoise (Phocoena phocoena)

Mammalian body condition is an important individual fitness metric as it affects both survival and reproductive success. The ability to accurately measure condition has key implications for predicting individual and population health, and therefore monitoring the population‐level effects of changing environments. No consensus currently exists on the best measure to quantitatively estimate body condition in many species, including cetaceans. Here, two measures of body condition were investigated in the harbor porpoise (Phocoena phocoena). First, the most informative morphometric body condition index was identified. The mass/length² ratio was the most appropriate morphometric index of 10 indices tested, explaining 50% of the variation in condition in stranded, male porpoises with different causes of death and across age classes (n = 291). Mass/length² was then used to evaluate a second measure, blubber cortisol concentration, as a metabolic condition marker. Cortisol is the main glucocorticoid hormone involved in the regulation of lipolysis and overall energy balance in mammals, and concentrations could provide information on physiological state. Blubber cortisol concentrations did not significantly vary around the girth (n = 20), but there was significant vertical stratification through the blubber depth with highest concentrations in the innermost layer. Concentrations in the dorsal, outermost layer were representative of concentrations through the full blubber depth, showed variation by sex and age class, and were negatively correlated with mass/length². Using this species as a model for live cetaceans from which standard morphometric measurements cannot be taken, but from which blubber biopsy samples are routinely collected, cortisol concentrations in the dorsal, outermost blubber layer could potentially be used as a biomarker of condition in free‐ranging animals.     

Sequence analysis of recent H7 avian influenza viruses associated with three different outbreaks in commercial poultry in the United States

The hemagglutinin (HA) and neuraminidase (NA) genes of H7 avian influenza virus (AIV) isolated between 1994 and 2002 from live-bird markets (LBMs) in the northeastern United States and from three outbreaks in commercial poultry have been characterized. Phylogenetic analysis of the HA and NA genes demonstrates that the isolates from commercial poultry were closely related to the viruses circulating in the LBMs. Also, since 1994, two distinguishing genetic features have appeared in this AIV lineage: a deletion of 17 amino acids in the NA protein stalk region and a deletion of 8 amino acids in the HA1 protein which is putatively in part of the receptor binding site. Furthermore, analysis of the HA cleavage site amino acid sequence, a marker for pathogenicity in chickens and turkeys, shows a progression toward a cleavage site sequence that fulfills the molecular criteria for highly pathogenic AIV.     

Novel P1 chain-extended HIV protease inhibitors possessing potent anti-HIV activity and remarkable inverse antiviral resistance profiles

A novel series of tyrosine-derived HIV protease inhibitors was synthesized and evaluated for in vitro antiviral activity against wild-type virus and two protease inhibitor-resistant viruses. All of the compounds had wild-type antiviral activities that were similar to or greater than several currently marketed HIV protease inhibitors. In addition, a number of compounds in this series were more potent against the drug-resistant mutant viruses than they were against wild-type virus.     

Zea ribosomal repeat evolution and substitution patterns

Zea and Tripsacum nuclear ribosomal internal transcribed spacer (ITS) sequences were used to evaluate patterns of concerted evolution, rates of substitutions, patterns of methylation-induced deamination, and structural constraints of the ITS. ITS pseudogenes were identified by their phylogenetic position, differences in nucleotide composition, extensive deamination at ancestral methylation sites, and substitutions resulting in low-stability secondary RNA structures. Selection was important in shaping the kinds of polymorphisms and substitutions observed in the ITS. ITS substitution rates were significantly different among the Zea taxa. Deamination of cytosines at methylation sites was a potent mutation source, but selection appeared to maintain high methylation site density throughout the ribosomal repeat except for the gene promoter. Nucleotide divergence statistics identified selectively constrained regions at the 5' ends of the ITS1 and ITS2.      

Loss of phylogenetic information in chorion gene families of Bombyx mori gene conversion

The silkmoth chorion has provided a stimulating model for the study of evolution and developmental regulation of gene families. Previous attempts at inferring relationships among chorion sequences have been based on pairwise comparisons of overall similarity, a potentially problematic approach. To remedy this, we identified the alignable regions of low sequence variability and then analyzed this restricted database by parsimony and neighbor-joining methods. At the deepest level, the chorion sequence tree is split into two branches, called "alpha" and "beta." Within each branch, early- and late-expressing genes each constitute monophyletic groups, while the situation with middle-expressing genes remains uncertain. The HcB gene family appears to be the most basal beta-branch group, but this conclusion is qualified because the effect of gene conversion on branching order is unknown. Previous studies by Eickbush and colleagues have strongly suggested that ErA, HcA, and HcB families undergo gene conversion within a gene family, whereas the ErB family does not. The occurrence of conversion correlates with a particular tree structure; namely, branch lengths are much greater at the base of the family than at higher internodes and terminal branches. These observations raise the possibility that chorion gene families are defined by gene conversion events (reticulate evolution) rather than by descent with modification (synapomorphy).      

High-level expression of the 32.5-kilodalton calelectrin in ductal epithelia as revealed by immunocytochemistry

Calelectrins are a family of antigenically related Ca2+-binding proteins that have only recently been described. They have the important property of binding to membranes only in the presence of Ca2+. We systematically studied the tissue localization of one calelectrin, the 32.5-kilodalton species, in rats using immunocytochemistry. We found that high levels were exclusively present in the epithelial cells of bile and pancreatic ducts, renal collecting ducts, bronchial epithelia, and brain ependyma. In all of these organs, the other cells were not immunoreactive. In addition, strong immunoreactivity was found in the intercalated disks of myocardial cells, and mild immunoreactivity was observed in several endocrine tissues. In contrast, the cellular distribution of the 67-kilodalton calelectrin was more diffuse, involving most parenchymal cells in addition to the already-mentioned cells. Due to the presence of high levels of 32.5-kilodalton calelectrin in some cell types, this protein may be used as a histochemical marker for differentiated ductal epithelial cells, some specialized epithelia, myocardial cells, and Paneth cells.