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.     

Exogenous GnRH overrides the endogenous annual reproductive rhythm in green iguanas, Iguana iguana

Female green iguanas, Iguana iguana, were caught in Belize, Central America (17 degrees N), in December, at the onset of seasonal gonadal activity. The animals were immediately transferred to San Diego (32 degrees N). Ovarian follicular development continued, with peak plasma hormone levels measured in January and February; 200 pg/ml for progesterone (P) and 800 pg/ml for total estrogens (Et = estradiol [E2] + estrone [E1]). E2 was the predominant estrogen throughout the cycle. Follicular atrophy was indicated in April with circulating progesterone and estrogen levels decreasing to baseline (refractory phase) levels (P = 20 pg/ml; Et = 50 pg/ml). Approximately midway through the refractory phase of their annual reproductive cycle (late May), either the D-Arg6 analog of Chicken II or mammalian GnRH was administered via intraperitoneal osmotic pumps for 14 days to nine females. The analog of chicken II induced a fivefold increase in total circulating estrogens within 3-4 days after implantation. Both continuous and pulsatile delivery of the chicken II analog produced a similar pattern of steroidogenic response. A radical sham control animal showed no increase in steroidogenesis. Mammalian GnRH produced a pattern of similar duration, although the magnitude of the steroidogenic response was only half that produced by the chicken II analog. Estrogen titers approached baseline levels in all treatment groups two days after treatment ceased. Progesterone levels increased in all treatment groups during the delivery of exogenous GnRH, although the increases were not consistent. Untreated male cagemates housed with treated females exhibited increased territoriality, courtship behavior, and mating, which began on day 4 or 5 of the treatment period. The control female was not courted by its male cagemate.     

Bifunctional oligonucleotide probes synthesized using a novel CPG support are able to detect single base pair mutations.

A novel multifunctional controlled pore glass, MF-CPG (Fig. 1), has been synthesized and used to incorporate 3' terminal primary aliphatic amines into synthetic oligonucleotides. MF-CPG consists of a unique succinic acid linking arm which possesses both a masked primary amine for label attachment and a dimethoxytrityl protected hydroxyl for nucleotide chain elongation. Using MF-CPG, we have devised a simple and convenient technique to attach non-radioactive labels to the 3' terminus of oligonucleotides. Bifunctional probes can then be constructed by 32P labeling the 5' terminus with T4 kinase and gamma 32P-ATP. Using such bifunctional oligonucleotide probes in conjunction with polymerase chain reaction (PCR) amplification, we were able to detect single base substitutions in a target segment of the human H-ras protooncogene employing either functionality. Our technique thus expands the potential applications for oligonucleotides as hybridization probes.     

Arachidonic Acid Release and Catecholamine Secretion from Digitonin-Treated Chromaffin Cells: Effects of Micromolar Calcium, Phorbol Ester, and Protein Alkylating Agents

The relationship between catecholamine secretion and arachidonic acid release from digitonin-treated chromaffin cells was investigated. Digitonin renders permeable the plasma membranes of bovine adrenal chromaffin cells to Ca2+, ATP, and proteins. Digitonin-treated cells undergo exocytosis of catecholamine in response to micromolar Ca2+ in the medium. The addition of micromolar Ca2+ to digitonin-treated chromaffin cells that had been prelabeled with [3H]arachidonic acid caused a marked increase in the release of [3H]arachidonic acid. The time course of [3H]arachidonic acid release paralleled catecholamine secretion. Although [3H]arachidonic acid release and exocytosis were both activated by free Ca2+ in the micromolar range, the activation of [3H]arachidonic acid release occurred at Ca2+ concentrations slightly lower than those required to activate exocytosis. Pretreatment of the chromaffin cells with N-ethylmaleimide (NEM) or p-bromophenacyl bromide (BPB) resulted in dose-dependent inhibition of 10 microM Ca2+-stimulated [3H]arachidonic acid release and exocytosis. The IC50 of NEM for both [3H]arachidonic acid release and exocytosis was 40 microM. The IC50 of BPB for both events was 25 microM. High concentrations (5-20 mM) of Mg2+ caused inhibition of catecholamine secretion without altering [3H]arachidonic acid release. A phorbol ester that activates protein kinase C, 12-O-tetradecanoylphorbol-13-acetate (TPA), caused enhancement of both [3H]arachidonic acid release and exocytosis. The findings demonstrate that [3H]arachidonic acid release is stimulated during catecholamine secretion from digitonin-treated chromaffin cells and they are consistent with a role for phospholipase A2 in exocytosis from chromaffin cells. Furthermore the data suggest that protein kinase C can modulate both arachidonic acid release and exocytosis.     

Increased Neural Cell Adhesion Molecule in the CSF of Patients with Mood Disorder

Abstract: Neural cell adhesion molecule (N-CAM) is involved in cell-cell interactions during synaptogenesis, morphogenesis, and plasticity of the nervous system. Disturbances in synaptic restructuring and neural plasticity may be related to the pathogenesis of several neuropsychiatric diseases, including mood disorders and schizophrenia. Disturbances in brain cellular function may alter concentrations of N-CAM in the CSF. Soluble human N-CAM proteins are detectable in the CSF but are minor constituents of serum. We have recently found an increase in N-CAM content in the CSF of patients with schizophrenia. Although the pathogenesis of both schizophrenia and mood disorders is unknown, ventriculomegaly, decreased temporal lobe volume, and subcortical structural abnormalities have been reported for both disorders. We have therefore measured N-CAM concentrations in the CSF of patients with mood disorder. There were significant increases in amounts of N-CAM immunoreactive proteins, primarily the 120-kDa band, in the CSF of psychiatric inpatients with bipolar mood disorder type I and recurrent unipolar major depression. There were no differences in bipolar mood disorder type II patients as compared with normals. There were no significant effects of medication treatment on N-CAM concentrations. It is possible that the 120-kDa N-CAM band present in the CSF is derived from CNS cells as a secreted soluble N-CAM isoform. Our results suggest the possibility of latent state-related disturbances in N-CAM cellular function, i.e., residue from a previous episode, or abnormal N-CAM turnover in the CNS of patients with mood disorder.     

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.      

Characterization of groups of the zygomycete genusRhizopus

Rhizopus is a zygomycetous genus. Several species of this taxon may infect humans and lower animals. Seventeen isolates ofRhizopus species in three distinct morphological groups were studied: the stolonifer group (sporangiophores greater than 1 mm in height, sporangial diameters of 100–275 µm, branched rhizoids); the arrhizus group (sporangiophores greater than 1 mm in height, branched rhizoids, sporangial diameters of 100–240 µm); and the microsporus group (sporangiophores less than 0.8 mm in height, sporangial diameters less than 100 µm, simple rhizoids). Maximal growth temperatures were characteristic: the stolonifer group grew at 30°C, the arrhizus group grew at 36°C, and the microsporus group grew at 45°C. The DNA mol% G + C base composition of all isolates ranged from 34.9 to 40.2% Species within the three groups were grouped by DNA differences. The arrhizus group was most distinctive with a value of 34.9–36.3%; the stolonifer and microsporus groups had G + C values of 37.0–39.3% and 37.8–40.2%, respectively. Our research clarifies and defines the G-C values of the three important groups ofRhizopus species.