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.     

Diaphragmatic activity is a determinant of postnatal lung growth

To test the hypothesis that activity of respiratory muscles determines regional growth of lung parenchyma, we studied the effects of unilateral diaphragmatic paralysis on contralateral/ipsilateral lung growth in cats and piglets. Five 10- to 12-wk-old cats and five 8-wk-old piglets underwent unilateral diaphragmatic paralysis by thoracic and cervical phrenectomy, respectively. Five to seven weeks after surgery, when the cats were killed for studies of lung growth, gain in body weight was the same as in five sham-operated controls. At this time, mean pleural pressure ipsilateral to the paralyzed hemidiaphragm was the same as contralateral mean pleural pressure during tidal breathing, and values did not differ from controls. However overall functional residual capacity was lower in the phrenectomized cats (35 +/- 4 ml) than in the controls (55 +/- 11 ml, P less than 0.01). Growth of contralateral lungs relative to ipsilateral lungs was greater in the phrenectomized cats than in the controls, as shown by ratios of contralateral/ipsilateral wet lung weight (1.44 vs. 1.34, P less than 0.01), maximum inflation volume (1.53 vs. 1.33, P less than 0.05), and total protein content (1.45 vs. 1.26, P less than 0.05). Ratios of total protein to DNA and RNA to DNA were unchanged. One week after surgery in the piglets, the ratio of contralateral/ipsilateral wet lung weight was increased (1.61 vs. 1.29, P less than 0.01) and total weight of both lungs was reduced. We conclude that regional growth of lung parenchyma by cell proliferation depends in part on regional distribution of respiratory muscle activity.     

Rotavirus RNA replication: VP2, but not VP6, is necessary for viral replicase activity.

Temperature-sensitive mutants of simian rotavirus SA11 were previously developed and organized into 10 of a possible 11 recombination groups on the basis of genome reassortment studies. Two of these mutants, tsF and tsG, map to genes encoding VP2 (segment 2) and VP6 (segment 6), respectively. To gain insight into the role of these proteins in genome replication, MA104 cells were infected with tsF or tsG and then maintained at permissive temperature (31 degrees C) until 9 h postinfection, when some cells were shifted to nonpermissive temperature (39 degrees C). Subviral particles (SVPs) were recovered from the infected cells at 10.5 and 12 h postinfection and assayed for associated replicase activity in a cell-free system shown previously to support rotavirus genome replication in vitro. The results showed that the level of replicase activity associated with tsF SVPs from cells shifted to nonpermissive temperature was ca. 20-fold less than that associated with tsF SVPs from cells maintained at permissive temperature. In contrast, the level of replicase activity associated with tsG SVPs from cells maintained at nonpermissive temperature was only slightly less (twofold or less) than that associated with tsG SVPs from cells maintained at permissive temperature. Analysis of the structure of replicase particles from tsG-infected cells shifted to nonpermissive temperature showed that they were similar in size and density to virion-derived core particles and contained the major core protein VP2 but lacked the major inner shell protein VP6. Taken together, these data indicate that VP2, but not VP6, is an essential component of enzymatically active replicase particles.     

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.      

Influence of broth dilution on the disruption of Escherichia coli

Summary The effect of cell concentration (5 to 150 g/L wet wt after broth dilution) on homogenizer disruption efficiency and homogenate viscosity is reported for E. coli. Broth dilution increases homogenizer efficiency and decreases feed and homogenate viscosity. However, this increase in disruption efficiency is not sufficient to warrant dilution of the broth prior to homogenization. The optimal feed concentration is the maximum possible that does not lead to practical handling difficulties due to high viscosity.     

Radioimmunoassay for the determination of limonin in Citrus

An ¹²⁵I-radioimmunoassay technique has been developed for the triterpenoid bitter principle, limonin. Synthesis of the iodinated tracer and the limonin—bovine serum albumin conjugate are described. The antibody has a high affinity (K_a 1.1 x 10⁹l/mol) and specificity for limonin and the detection limit of the assay is 0.07 ng or 0.7 ppb. Standard curves are linear over a range of 0.5–100 ng limonin, assays can be performed in crude extracts, and several hundred samples can be processed per day. The distribution of limonin in fruits and vegetative parts of Citrus paradisi has been determined, highest values (0.92%) being found in the seeds, lowest (0.0007%) in the juice vesicles of ripe fruits. The potential of this assay method in citrus research is discussed.     

Phylogeny and biogeography of southern African spoon-winged lacewings (Neuroptera: Nemopteridae: Nemopterinae)

Nemopteridae are a charismatic family of lacewings characterised by uniquely extended hind wings. They are an ancient widespread group in the drier regions of the world. The family comprises two subfamilies, Crocinae (thread-wings) and Nemopterinae (spoon- and ribbon-wings). The present distribution of the family has been largely influenced by the vicariant events of plate tectonics, resulting in relict populations in some parts of the world and extensive evolutionary radiations in others, particularly southern Africa where the vast majority of the species are endemic to the Western and Northern Cape Provinces of South Africa. This study aimed to establish the validity of the 11 currently recognised genera and infer their biogeographic history using molecular sequence data from four gene regions. The hypothesis that the Cape nemopterines co-evolved with certain taxa in the Cape Floristic Region was also tested. Phylogenetic analysis supports seven of the 11 currently recognised genera. The crown age of the Nemopterinae is estimated to be at ca. 145.6 Mya, indicating that the group has been present since the late Jurassic. Most of the genera appear to have diversified during the middle Eocene and into the middle Miocene (ca. 44–11 Mya) with recent rapid radiation of several of the genera occurring during the late Miocene (ca. 6–4.5 Mya). While these data support an initial radiation with the Rushioideae (Aizoaceae) it is recommended that further study including observations and gut content be carried out.