Phylogenetics and biogeography of the broad-nosed bats, genus Platyrrhinus (Chiroptera: Phyllostomidae)

The Neotropical broad-nosed bats, genus Platyrrhinus, represent a well-defined monophyletic group of 14 recognized species. A recent study of morphological characters confirmed Platyrrhinus monophyly and species diagnosis, but offered little support to their intra-specific relationships. We conducted phylogenetic analyses of the genus, using dense taxonomic sampling in combination with four gene sequences representing both mitochondrial and nuclear DNA transmission systems. Our aim was to elucidate the phylogenetic structure among species, using the resulting 3341 bp of DNA. Maximum parsimony, maximum likelihood, and Bayesian inference analyses produced similar topologies that confirm the monophyly of the genus Platyrrhinus and strongly support many previously unrecognized groups. Paraphyly of Platyrrhinus helleri and the unclear position of P. brachycephalus in the clades were also apparent in the data. Our biogeographical analysis suggests a Brazilian Shield origin for Platyrrhinus, followed by subsequent radiations of lineages in the Amazon Basin and Andes. Secondary dispersal from Amazonian and Andean centers is responsible for the Platyrrhinus inhabiting the Guianan Shield and the Pacific lowlands and Central America, respectively.     

Effect of ante- and postmortem hide clipping on the microbiological quality and safety and ultimate pH value of beef carcasses in an EC-approved abattoir

Aims:  Effect of ante- and postmortem hide clipping on the microbiological quality of beef carcasses. Methods and Results:  Bovine carcasses (362) were tested for indicator micro-organisms and the presence of pathogens. Prior to slaughter, hide cleanliness of each animal was categorized on a scale of 1–5 (clean to dirty). Lowest mean aerobic colony counts (ACC) (log₁₀ 3·0 CFU cm⁻²) came from carcasses where clipping had been performed in lairage, antemortem. ACC from animals clipped online (log₁₀ 3·2 CFU cm⁻²) were significantly higher (P < 0·05) than those clipped in lairage, but comparable to those carcasses from Category 1 and 2 animals. There were no significant differences in the detection of pathogens from any of the carcass groups. Ultimate pH values for carcasses from Category 3 and 4 animals showed clipping animals in lairage, as opposed to online, resulted in a small, but significant increase (P < 0·05) in pH value (mean pH 5·66 and 5·59, respectively). Conclusions:  Hide clipping does not adversely affect microbiological quality of carcasses, although higher ultimate pH values indicate increases in antemortem stress. Significance and Impact of the Study:  Hide clipping carcasses both ante- and postmortem appears to be an effective intervention to minimize transfer of hide microflora to carcasses during slaughtering operations. Online clipping offers advantages for animal welfare and improves safety for operatives.     

NHERF2 Protein Mobility Rate Is Determined by a Unique C-terminal Domain That Is Also Necessary for Its Regulation of NHE3 Protein in OK Cells

Na⁺/H⁺ exchanger regulatory factor (NHERF) proteins are a family of PSD-95/Discs-large/ZO-1 (PDZ)-scaffolding proteins, three of which (NHERFs 1-3) are localized to the brush border in kidney and intestinal epithelial cells. All NHERF proteins are involved in anchoring membrane proteins that contain PDZ recognition motifs to form multiprotein signaling complexes. In contrast to their predicted immobility, NHERF1, NHERF2, and NHERF3 were all shown by fluorescence recovery after photobleaching/confocal microscopy to be surprisingly mobile in the microvilli of the renal proximal tubule OK cell line. Their diffusion coefficients, although different among the three, were all of the same magnitude as that of the transmembrane proteins, suggesting they are all anchored in the microvilli but to different extents. NHERF3 moves faster than NHERF1, and NHERF2 moves the slowest. Several chimeras and mutants of NHERF1 and NHERF2 were made to determine which part of NHERF2 confers the slower mobility rate. Surprisingly, the slower mobility rate of NHERF2 was determined by a unique C-terminal domain, which includes a nonconserved region along with the ezrin, radixin, moesin (ERM) binding domain. Also, this C-terminal domain of NHERF2 determined its greater detergent insolubility and was necessary for the formation of larger multiprotein NHERF2 complexes. In addition, this NHERF2 domain was functionally significant in NHE3 regulation, being necessary for stimulation by lysophosphatidic acid of activity and increased mobility of NHE3, as well as necessary for inhibition of NHE3 activity by calcium ionophore 4-Br-{"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187. Thus, multiple functions of NHERF2 require involvement of an additional domain in this protein.     

Drosophila purine auxotrophy: New alleles ofadenosine2 exhibiting a complex visible phenotype

New mutant alleles of theadenosine2 locus (ade2; 2–17.7) have been isolated using the eye-color phenotype exhibited by the prototype auxotrophic alleleade2 ¹ as the screening criterion. The new mutants form a single complementation group, suggesting that they all exhibit purine auxotrophy and defective formylglycineamide ribotide amidotransferase enzyme, likeade2 ¹. Tests carried out on particular new alleles confirm these suggestions. The new mutants all exhibit more extreme physical defects than the prototype. They have wing abnormalities like mutants defective in pyrimidine biosynthesis and reduced bristles like those defective in protein synthesis; thus they exhibit the combined visible phenotype ofrudimentary wings,rosy eyes, andbobbed bristles. Cytogenetic analysis places the locus in the interband proximal to26B1-2.This work was supported by NSERC Operating Grant A3269 to D.N., an Alberta Heritage Foundation for Medical Research Postdoctoral Fellowship to S.Y.K.T., and National Institute on Aging Grant AG00029 to D.P.     

Partial Purification of Mucor pusillus Intracellular Proteases

The intracellular protease extracted from the freeze-dried mycelia obtained after the growth of Mucor pusillus at 30°C in corn steep liquor medium was chromatographed on DEAE-A50. Some characteristics of the protease fractions obtained after ion-exchange chromatography were determined and compared with those of the extracellular proteases reported previously. The mycelia were found to contain two acid proteases and an alkaline protease. The ratio of milk clotting to protease activity of one acid protease was greater than that of the other. The electrophoretic pattern of the alkaline protease fraction suggested that it was not a single species, but a mixture of proteolytic enzymes.     

Ecosystem state shifts during long‐term development of an Amazonian peatland

The most carbon (C)‐dense ecosystems of Amazonia are areas characterized by the presence of peatlands. However, Amazonian peatland ecosystems are poorly understood and are threatened by human activities. Here, we present an investigation into long‐term ecohydrological controls on C accumulation in an Amazonian peat dome. This site is the oldest peatland yet discovered in Amazonia (peat initiation ca. 8.9 ka BP), and developed in three stages: (i) peat initiated in an abandoned river channel with open water and aquatic plants; (ii) inundated forest swamp; and (iii) raised peat dome (since ca. 3.9 ka BP). Local burning occurred at least three times in the past 4,500 years. Two phases of particularly rapid C accumulation (ca. 6.6–6.1 and ca. 4.9–3.9 ka BP), potentially resulting from increased net primary productivity, were seemingly driven by drier conditions associated with widespread drought events. The association of drought phases with major ecosystem state shifts (open water wetland–forest swamp–peat dome) suggests a potential climatic control on the developmental trajectory of this tropical peatland. A third drought phase centred on ca. 1.8–1.1 ka BP led to markedly reduced C accumulation and potentially a hiatus during the peat dome stage. Our results suggest that future droughts may lead to phases of rapid C accumulation in some inundated tropical peat swamps, although this can lead ultimately to a shift to ombrotrophy and a subsequent return to slower C accumulation. Conversely, in ombrotrophic peat domes, droughts may lead to reduced C accumulation or even net loss of peat. Increased surface wetness at our site in recent decades may reflect a shift towards a wetter climate in western Amazonia. Amazonian peatlands represent important carbon stores and habitats, and are important archives of past climatic and ecological information. They should form key foci for conservation efforts.     

Toxicity and partial structure of a hepatotoxic peptide produced by the cyanobacterium Nodularia spumigena Mertens emend. L575 from New Zealand.

A clonal isolate, termed L575, of the filamentous brackish-water cyanobacterium Nodularia spumigena Mertens emend. was found to produce a potent hepatotoxic peptide (50% lethal intraperitoneal dose for the mouse, 60 micrograms/kg) with chemical and toxicological properties similar to those of the hepatotoxic heptapeptides produced by other freshwater planktonic cyanobacteria. The isolate was made from a water sample collected in Lake Ellesmere, New Zealand, in 1980. The toxin, isolated and purified by high-performance liquid chromatography (HPLC) and analyzed by HPLC amino acid analysis, contained glutamic acid, beta-methyla-spartic acid, and arginine units in equivalent amounts. The fast-atom-bombardment mass spectrum of the toxin indicated the molecular weight to be 824. Batch cultures of strain L575 showed that the toxin content varied between 1.96 and 2.99 mg/g of cells and that a positive correlation between toxin content and chlorophyll a, but not biomass, was present.     

The induction of acetylcholine synthesis in primary cultures of dissociated rat sympathetic neurons : II. Developmental aspects

Dissociated sympathetic neurons from the neonatal rat, grown in cell culture in the virtual absence of other cell types, can develop many of the properties expected of differentiated adrenergic neurons including the ability to synthesize and accumulate catecholamines (CA)². However, in the presence of high concentrations of appropriately conditioned medium (CM), the cultures develop the ability to synthesize and accumulate acetylcholine (ACh); correspondingly, their ability to synthesize CA decreases. In this paper several developmental aspects of the CM effect are described. The time course of development of cultures grown with or without CM was followed using synthesis and accumulation of [³H]CA from [³H]tyrosine and production of [³H]ACh from [³H]choline as assays for adrenergic and cholinergic differentiation. The ability to produce CA or ACh developed along parallel time courses in the two sets of cultures, rising primarily during the second week in vitro and reaching a plateau during the fourth week. When CM was used as a cholinergic developmental signal, the sympathetic neurons showed a decreasing response to addition of CM as they matured adrenergically; addition of CM during the third or fourth 10 days in vitro was not as effective in inducing ACh production as addition during the first or second 10 days. Similarly, removal of CM at various times from cultures previously grown in CM showed that the cholinergic induction caused by CM was not easily reversible in older cultures. Thus, as with the adrenergic decision, the cholinergic decision becomes less reversible as the phenotype becomes fully expressed.