Systematics within Gyps vultures: a clade at risk

Background  

Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis.     

Patterns of divergence during evolution of alpha 1-proteinase inhibitors in mammals

alpha 1-Proteinase inhibitor (alpha 1-PI), a member of the serine proteinase inhibitor superfamily, has a primary role in controlling neutrophil elastase activity within the mammalian circulation. Several studies have indicated that the reactive center region of alpha 1-PI, the amino acid sequence of which is critical to recognition of and binding to target proteinases, is highly divergent within and among species. This appears to be a consequence of accelerated rates of evolution that may have been driven by positive Darwinian selection. In order to examine this and other features of alpha 1-PI evolution in more detail, we have isolated and sequenced cDNAs representing alpha 1- PI mRNAs of the mouse species Mus saxicola and Mus minutoides and have compared these with a number of other mammalian alpha 1-PI mRNAs. Relative to other mammalian mRNAs, the extent of nonsynonymous substitution is generally high throughout the alpha 1-PI mRNA molecule, indicating greater overall rates of amino acid substitution. Within and among mouse species, the 5'-half of the mRNA, but not the 3'-half, has been homogenized by concerted evolution. Finally, the reactive center is under diversifying or positive Darwinian selection in murid rodents (rats, mice) and guinea pigs yet is under purifying selection in primates and artiodactyls. The significance of these findings to alpha 1-PI function and the possible selective forces driving evolution of serpins in general are discussed.      

Mitochondrial DNA polymorphisms in subterranean mole-rats of the Spalax ehrenbergi superspecies in Israel, and its peripheral isolates

Patterns of mitochondrial DNA (mtDNA) variation were examined in 133 mole-rats constituting all four chromosomal species (2n = 52, 2n = 54, 2n = 58, and 2n = 60) of the Spalax ehrenbergi superspecies in Israel, as well as the peripheral isolates of 2n = 60. In the main range of the complex, a total of 28 mtDNA haplotypes were found in 64 mole-rats, with most haplotypes being unique to either a single chromosomal species or population. mtDNA divergence increased from low to high diploid number in a north-to-south direction in Israel. Overall levels of mtDNA diversity were unexpectedly the highest in the 2n = 60, the youngest species of the complex. The mtDNA haplotypes can be separated into two major groups, 2n = 52-54 and 2n = 58-60, and a phylogenetic analysis for each group revealed evidence of a few haplotypes not sorted by diploid number. The overall patterns of mtDNA divergence seen within and among the four chromosomal species are consistent with the parapatric mode of speciation as suggested from previous studies of allozyme and DNA hybridization. In a separate data set the patterns of mtDNA variation were examined across the main geographic range and across peripheral semi-isolates and isolates of the 2n = 60 chromosomal species. Fifteen haplotypes were found in 69 mole-rats. High levels of mtDNA diversity characterized the main range, semi-isolated, and even some desert isolated populations. The peripheral isolates contain much mtDNA diversity, including novel haplotypes.      

Protease priming of neutrophil superoxide production. Effects on membrane lipid order and lateral mobility.

Phagocyte superoxide (O2-) response is primed by a variety of physiologic compounds including the neutrophil secretory proteases cathepsin G and elastase. To study whether protease priming of neutrophil O2- response is related to changes in membrane physical state, we examined enzyme effects on the order and lateral mobility of lipid probes in intact neutrophil membranes. Exposure to cathepsin G (5 micrograms/ml) or elastase (10 micrograms/ml) caused a significant decrease in fluorescence anisotropy of the probe trimethylammonium diphenylhexatriene in neutrophil plasma membranes (0.279 to 0.256 for cathepsin G, 0.274 to 0.256 for elastase, p less than 0.02 for both), indicating a decrease in phospholipid chain order in the surface membrane bilayer. Cathepsin G and elastase also caused significant increases in membrane lipid lateral mobility as measured by excimer formation of the fluorescent probe 1-pyrenedecanoic acid (for cathepsin G, a 107% increase, and for elastase, a 44% increase in excimer/monomer fluorescence ratio, p less than 0.001). Enzyme effects on membrane structure were dependent on intact proteolytic activity, and were cell specific; the proteases had no effect on lipid order or lateral mobility in liposomes. In corollary studies, the possible association between the physical state of the polymorphonuclear leukocyte membrane and O2- generation was analyzed with the membrane modifying compounds, linoleic acid, ethanol, and cholesterol. Cell exposure to linoleic acid (1 microM) caused a significant decrease in lipid order and an increase in lipid lateral mobility along with increased O2- production to N-formyl-Met-Leu-Phe (fMLP) (191%) and phorbol myristate acetate (PMA) (39%), p less than 0.02 for each. 3 mM ethanol also augmented O2- response to fMLP (31%) and PMA (48%) and caused a significant decrease in lipid order, but did not affect lipid lateral mobility. Treatment with cholesteryl hemisuccinate (100 micrograms/ml) resulted in increased lipid order and decreased lipid lateral mobility, as well as decreased neutrophil superoxide response to fMLP (-61%, p less than 0.001) and PMA (-50%, p less than 0.02). We then examined whether modulation of membrane physical state may explain the mechanism of action of a known priming agent by studying the effects of low concentrations of a diacylglycerol. Cells treated with 10 microM 1-oleoyl-2-acetyl-sn-glycerol had a greater than 8-fold increase in superoxide response to fMLP (p less than 0.001) while demonstrating a significant decrease in lipid order (0.289 to 0.281, p less than 0.01) and a 50% increase in lipid lateral mobility (p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)     

Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae

Arginine decarboxylase (ADC) is an important enzyme in the production of putrescine and polyamines in plants. It is encoded by a single or low-copy nuclear gene that lacks introns in sequences studied to date. The rate of Adc amino acid sequence evolution is similar to that of ndhF for the angiosperm family studied. Highly conserved regions provide several target sites for PCR priming and sequencing and aid in nucleotide and amino acid sequence alignment across a range of taxonomic levels, while a variable region provides an increased number of potentially informative characters relative to ndhF for the taxa surveyed. The utility of the Adc gene in plant molecular systematic studies is demonstrated by analysis of its partial nucleotide sequences obtained from 13 representatives of Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order Capparales) and 1 from the related order Malvales. Two copies of the Adc gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied to data except the basal genus Aethionema. The resulting Adc gene tree provides robust phylogenetic data regarding relationships within the complex mustard family, as well as independent support for proposed tribal realignments based on other molecular data sets such as those from chloroplast DNA.      

HP1-β is required for development of the cerebral neocortex and neuromuscular junctions

HP1 proteins are thought to be modulators of chromatin organization in all mammals, yet their exact physiological function remains unknown. In a first attempt to elucidate the function of these proteins in vivo, we disrupted the murine Cbx1 gene, which encodes the HP1-β isotype, and show that the Cbx1^−/−-null mutation leads to perinatal lethality. The newborn mice succumbed to acute respiratory failure, whose likely cause is the defective development of neuromuscular junctions within the endplate of the diaphragm. We also observe aberrant cerebral cortex development in Cbx1^−/− mutant brains, which have reduced proliferation of neuronal precursors, widespread cell death, and edema. In vitro cultures of neurospheres from Cbx1^−/− mutant brains reveal a dramatic genomic instability. Our results demonstrate that HP1 proteins are not functionally redundant and that they are likely to regulate lineage-specific changes in heterochromatin organization.     

Weight Change in Adult Life and Health Outcomes

Objective: To investigate the relationship between weight change in adult life and subsequent mortality and cancer incidence in women. Research Methods and Procedures: In 1994 to 1995, all women (age range, 42 to 81) still under general practitioner observation in the United Kingdom's Royal College of General Practitioners Oral Contraception Study (n = 12 303) were sent a health survey asking about health and lifestyle issues, including current weight and weight at age 30. The main outcome measures were 6‐year all‐cause mortality and cancer incidence among different weight change deciles. Cox regression was used to calculate hazard ratios that were adjusted for: social class at recruitment, BMI at age 30, and age group, parity, smoking status, and hormone replacement therapy status in 1995. Results: Women who had been obese at age 30 were more likely to die and significantly more likely to develop cancer in the 6 years after the health survey than non‐obese respondents. Women reporting weight gains between age 30 and 1995 were significantly less likely to die during the 6 years after the health survey than those with a stable weight, whereas those with weight loss did not fare any better than those in the stable‐weight group. Discussion: Although obesity at young age was associated with subsequent mortality and cancer incidence, weight gain over a time period of 12 to 51 years appeared to be beneficial when compared with women with stable weight over the same time period. Further research is needed to confirm or refute our findings and to allow detailed examination of potential explanations for them.