Habitat use, diet and body size of Heard Island weevils

Habitat use, diet and body-size variation are examined in weevils from Heard Island. with specific attention being given to the Ectemnorhinus viridis species complex. E. viridis shows marked altitudinal variation in body size and vestiture, but there are no consistent associations between body size and diet. nor are there consistent among-individual differences in conventional taxonomic characters. Thus, the status of E. viridis as a single, variable species is maintained. This species occurs from sea level to 600 rn and it feeds on vascular plants and bryophytes. Canonopsis sericeus also feeds on bryophytes and vascular plants and occurs over a narrower altitudinal range. Palirhoeus eatoni is restricted to the surpralittoral zone where it feeds on marine algae and lichens. Bothrometopus brei,is and B. gracilipes both feed on cryptogams, with the former species occurring from sea level to 450 m. and the latter from 50 to 550 m above sea level. In all species, males are smaller than females and there is a size cline such that populations from higher elevations are smaller than those at lower altitudes. This cline is the reverse of that found on the Prince Edward Islands which, unlike Heard Island, lie to the north of the Antarctic Polar Frontal Zone. This difference in body-size clines between weevils on the two island groups is ascribed to the shorter growing season on the colder Heard Island. The information presented here supports previous ideas regarding the evolution of the Ectemnorhinus-group of weevils on the South Indian Ocean Province Islands, although it suggests that subsequent tests of these hypotheses would profit from the inclusion of molecular systematic work.

Gulliver, a long terminal repeat retrotransposon from the genome of the oriental blood fluke Schistosoma japonicum

We characterized the consensus sequence and structure of a long terminal repeat (LTR) retrotransposon from the genome of the human blood fluke, Schistosoma japonicum, and have earned this element, Gulliver. The full length, consensus Gulliver LTR retrotransposon was 4788 bp, and it was flanked at its 5'- and 3'-ends by LTRs of 259 bp. Each LTR included RNA polymerase II promoter sequences, a CAAT signal and a TATA box, Gulliver exhibited features characteristic of a functional LTR retrotransposon including two read through (termination) ORFs encoding retroviral gag and pol proteins of 312 and 1071 amino acid residues, respectively. The gag ORF encoded motifs conserved in nucleic acid binding proteins, while the pol ORF encoded conserved domains of aspartic protease, reverse transcriptase (RT), RNaseH and integrase, in that order, a pol pattern conserved in the gypsy lineage of LTR retrotransposons. Whereas the sequence and structure of Gulliver was similar to that of gypsy, phylogenetic analysis revealed that Gulliver did not group particularly closely with the gypsy family. Rather, its closest relatives were a LTR retrotransposon from Caenorhabditis elegans, mag from Bombyx mori and, to a lesser extent, easel from the salmon Oncorhynchus keta. Dot blot hybridizations indicated that Gulliver was present at between 100 and several thousand copies in the S. japonicum genome, and Southern hybridization analysis suggested its probable presence in the genome of Schistosoma mansoni. Transcripts encoding the RT domain of Gulliver were detected by RT-PCR in larval and adult stages of S. japonicum, indicating that (at least) the RT domain of Gulliver is transcribed. This is the first report of the sequence and structure of an LTR retrotransposon from any schistosome or indeed from any species belonging to the phylum Platyhelminthes. (C) 2001 Elsevier Science B.V. All rights reserved.

Estrogen receptors in human preadipocytes

Estrogen influences regional adipose tissue distribution and the accompanying cardiovascular disease risk. To elucidate the mechanisms of this link further, we assessed whether human preadipocytes (PAs) expressed estrogen receptors (ERs) and whether there were any regional or gender differences in ER complement. Human PAs expressed the ER alpha gene but not ERP by reverse transcriptase-polymerase chain reaction, possessed ER alpha protein on Western blotting, and displayed specific 17 beta -estradiol (E-2) binding with calculated dissociation constants of 0.78 nM, 0.96 nM, and 1.19 nM and maximal binding capacities of 9.3 fmol/mg, 14.6 fmol/ mg, and 18.2 fmol/mg from three whole cell binding assays. There were no regional differences in ER alpha complement for males or females. There were no gender differences in ER alpha complement for subcutaneous or visceral samples. We conclude that ER alpha but not ERP is present in human PAs. This suggests that the effect of estrogen on adipose tissue deposition has a contribution from the direct effect of estrogen on human PAs via ER alpha.

Chronic hypoxia induced down-regulation of angiotensinogen expression in rat epididymis

The presence of an intrinsic renin-angiotensin system (RAS) in the rat epididymis has been previously established by showing the expression of several key RAS components, and in particular angiotensinogen, the indispensable element for the intracellular generation of angiotensin II. In this study, the possible involvement of this local epididymal RAS in the testicular effects of chronic hypoxia was investigated. Semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR), Western blotting and by in situ hybridization histochemistry of the rat epididymis were used to show changes in localization and expression of angiotensinogen. Results from RT-PCR analysis demonstrated that chronic hypoxia caused a marked decrease (60%) in the expression of angiotensinogen mRNA, when compared with that in the normoxic epididymis. Western blot analysis demonstrated a less decrease (35%) in the expression of angiotensinogen protein. In situ hybridization histochemistry showed that the reduced angiotensinogen mRNA in chronic hypoxia was specifically localized to the epididymal epithelium from the cauda, corpus and caput regions of the epididymis; a distribution similar to that of normoxic rats. It was concluded that chronic hypoxia decreases the transcriptional and translational expression of angiotensinogen, and thus local formation of angiotensin II, in the rat epididymis. (C) 2001 Elsevier Science B.V. All rights reserved.

Amino acid residues in conodont elements

Thermally unaltered conodont elements, brachiopods. and vertebrates were analyzed with reverse phase high profile liquid chromatography to locate and quantify amino acid remnants of the original organic matrix in the fossils. No consistent similarities in amino acid content were found in conodont taxa. and criteria based on organic residues appear to have no taxonomic significance in the fossils tested from these localities. However, hydroxyproline. an amino acid that is found in the collagen molecules of animals. as well as in the glycoproteins in the cell walls and reproductive tissues of certain plants, is represented in most taxa. The organic matter retained in the impermeable crowns of conodont elements might have been derived originally from a form of collagen. Biochemical analyses. correlated with histochemical tests, demonstrate that organic matter is an integral part of the hyaline tissue of the element crown and not the result of surface contamination. Tests of a range of vertebrate and invertebrate fossil hard tissues produced similar results. The analyses indicate that hyaline tissue in the conodont element crown is not a form of vertebrate enamel. which contains no collagen. Albid tissue. with little or no organic content. is not a form of vertebrate bone or dentine, both based on collagen and low in mineral. Although these results do not help to determine the phylogenetic affinities of conodont animals, they indicate teat conodont elements do not contain hard tissues characteristic of vertebrate animals.

Mutations in exon 3 of the beta-catenin gene are rare in melanoma cell lines

Mutations in exon 3 of the CTNNB1 gene encoding beta-catenin have been reported in colorectal cancer cell lines and tumours. Although one study reported mutations or deletions affecting beta-catenin in 20% of melanoma cell lines, subsequent reports detected a much lower frequency of aberrations in uncultured melanomas. To determine whether this difference in mutation frequency reflected an in vitro culturing artefact, exon 3 of CTNNB1 was screened in a panel of 62 melanoma cell lines. In addition, reverse transcription-polymerase chain reaction (RT-PCR) was performed to detect intragenic deletions affecting exon 3. One out of 62 (1.6%) cell lines was found to carry a mutation, indicating that aberration of the Wnt-l/wingless pathway through activation of beta-catenin is a rare event, even in melanoma cell lines. (C) 2002 Lippincott Williams Wilkins.

Economic and environmental impacts of pollution control in a system of environment and economic interdependence

The importance of the rate of change of the pollution stock in determining the damage to the environment has been an issue of increasing concern in the literature. This paper uses a three-sector (economy, population and environment), non-linear, discrete time, calibrated model to examine pollution control. The model explicitly links economic growth to the health of the environment. The stock of natural resources is affected by the rate of pollution flows, through their impact on the regenerative capacity of the natural resource stock. This can shed useful insights into pollution control strategies, particularly in developing countries where environmental resources are crucial for production in many sectors of the economy. Simulation exercises suggested that, under plausible assumptions, it is possible to reverse undesirable transient dynamics through pollution control expenditure, but this is dependent upon the strategies used for control. The best strategy is to spend money fostering the development of production technologies that reduce pollution rather than spending money dealing with the effects of the pollution flow into the environment. (C) 2001 Elsevier Science Ltd. All rights reserved.

High-performance L-band series and parallel switches using low-cost p-i-n diodes

Low-cost UHF-band p-i-n diodes are used to develop high-performance L-band series and parallel switches. To stop the rectification of large RF, signals, the diodes are biased at a large reverse-bias voltage. Parasitic elements of the diodes are tuned out using LC circuits in biasing circuits without increasing the size of the switches. (C) 2002 John Wiley Sons, Inc.

On the importance function in splitting simulation

The splitting method is a simulation technique for the estimation of very small probabilities. In this technique, the sample paths are split into multiple copies, at various stages in the simulation. Of vital importance to the efficiency of the method is the Importance Function (IF). This function governs the placement of the thresholds or surfaces at which the paths are split. We derive a characterisation of the optimal IF and show that for multi-dimensional models the natural choice for the IF is usually not optimal. We also show how nearly optimal splitting surfaces can be derived or simulated using reverse time analysis. Our numerical experiments illustrate that by using the optimal IF, one can obtain a significant improvement in simulation efficiency.

Cloning of a differentially expressed tropomyosin isoform from cultured rabbit aortic smooth muscle cells

The four known tropomyosin genes have highly conserved DNA and amino acid sequences, and at least 18 isoforms are generated by alternative RNA splicing in muscle and non-muscle cells. No rabbit tropomyosin nucleotide sequences are known, although protein sequences for alpha- and beta-tropomyosin expressed by rabbit skeletal muscle have been described. Subtractive hybridisation was used to select for genes differentially expressed in rabbit aortic smooth muscle cells (SMC), during the change in cell phenotype in primary culture that is characterised by a loss of cytoskeletal filaments and contractile proteins. This led to the cloning of a tropomyosin gene predominantly expressed in rabbit SMC during this change. The full-length cDNA clone, designated rabbit TM-beta, contains an open reading frame of 284 amino acids, 5' untranslated region (UTR) of I 17 base pairs and 3' UTR of 79 base pairs. It is closely related to the beta-gene isoforms in other species, with the highest homology in DNA and protein sequences to the human fibroblast isoform TM-1 (91.7% identity in 1035 bp and 93.3% identity in the entire 284 amino acid sequence of the protein), It differs from rabbit skeletal muscle P-tropomyosin (81.7% homology at the protein level) mainly in two regions at amino acids 189-213 and 258-283 suggesting alternative splicing of exons 6a for 6b and 9d for 9a. Since this TM-P gene was the only gene strongly enough expressed in SMC changing phenotype to be observed by the subtractive hybridisation screen, it likely plays a significant role in this process. (C) 2002 Published by Elsevier Science Ltd.

Genetic differentiation between Australian and North American populations of the monarch butterfly Danaus plexippus (L.) (Lepidoptera : Nymphalidae): an exploration using allozyme electrophoresis

Allozyme analysis was used to address the question of the source of the Australian populations of the monarch butterfly Danaus plexippus (L.). The study had three major aims: (1) To compare the levels of diversity of Australian and Hawaiian populations with potential source populations. (2) To determine whether eastern and western North American populations were sufficiently divergent for the Australian populations to be aligned to a source population. (3) To compare the differentiation among regions in Australia and North America to test the prediction of greater genetic structure in Australia, as a consequence of reduced migratory behaviour. The reverse was found, with F-ST values an order of magnitude lower in Australia than in North America. Predictably, Australian and Hawaiian populations had lower allelic diversity, but unexpected higher heterozygosity values than North American populations. It was not possible to assign the Australian populations to a definitive source, although the high levels of similarity of Australian populations to each other suggest a single colonization event. The possibility that the Australian populations have not been here long enough to reach equilibrium is discussed. (C) 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 437-452.

Spermine modulation of the glutamate(NMDA) receptor is differentially responsive to conantokins in normal and Alzheimer's disease human cerebral cortex

The pharmacology of the N -methyl-d-aspartate (NMDA) receptor site was examined in pathologically affected and relatively spared regions of cerebral cortex tissue obtained at autopsy from Alzheimer's disease cases and matched controls. The affinity and density of the [H-3]MK-801 binding site were delineated along with the enhancement of [H-3]MK-801 binding by glutamate and spermine. Maximal enhancement induced by either ligand was regionally variable; glutamate-mediated maximal enhancement was higher in controls than in Alzheimer's cases in pathologically spared regions, whereas spermine-mediated maximal enhancement was higher in controls in areas susceptible to pathological damage. These and other data suggest that the subunit composition of NMDA receptors may be locally variable. Studies with modified conantokin-G (con-G) peptides showed that Ala(7)-con-G had higher affinity than Lys(7)-con-G, and also defined two distinct binding sites in controls. Nevertheless, the affinity for Lys(7)-con-G was higher overall in Alzheimer's brain than in control brain, whereas the reverse was true for Ala(7)-con-G. Over-excitation mediated by specific NMDA receptors might contribute to localized brain damage in Alzheimer's disease. Modified conantokins are useful for identifying the NMDA receptors involved, and may have potential as protective agents.

Body mass index-related human adipocyte agouti expression is sex-specific but not depot-specific

Objective: To determine if human adipocyte agouti signal protein (ASIP) mRNA expression is associated with obesity and is gender and/or depot specific. Research Methods and Procedures: Subjects included 8 men (64 +/- 3 years) and 14 women (56 +/- 15 years) undergoing elective abdominal surgery. ASIP mRNA levels in isolated omental and subcutaneous abdominal adipocytes were measured by quantitative reverse transcription polymerase chain reaction. Results: No significant depot difference was observed between genders; ASIP mRNA levels of omental and subcutaneous abdominal adipocytes were pooled for this analysis. BMI and ASIP gene expression were negatively correlated in men (p = -0.70; p < 0.05), whereas a positive relationship was observed in women (p = 0.48; p < 0.05). No significant difference was observed in age, body weight, body mass index (BMI), and waist circumference between groups. Hip circumference was significantly higher in women than in men (p < 0.05). Also, no significant difference in ASIP mRNA expression was observed between men and women, regardless of the fat depot. Discussion: These results show that men and women of similar age and BMI present similar ASIP mRNA levels in omental and subcutaneous abdominal adipocytes. However, a sexual dimorphism exists in the relationship between ASIP expression and BMI. If ASIP is involved in appetite regulation or energy homeostasis in humans, this observation may contribute to the recognized differences in these parameters between men and women.

Detection of West Nile virus antigen in mosquitoes and avian tissues by a monoclonal antibody-based capture enzyme immunoassay

An antigen capture immunoassay to detect West Nile (WN) virus antigen in infected mosquitoes and avian tissues has been developed. With this assay purified WN virus was detected at a concentration of 32 pg/0.1 ml, and antigen in infected suckling mouse brain and laboratory-infected mosquito pools could be detected when the WN virus titer was 10(2.1) to 10(3.7) PFU/0.1 ml. In a blindly coded set of field-collected mosquito pools (n = 100), this assay detected WN virus antigen in 12 of 18 (66.7%) TaqMan-positive pools, whereas traditional reverse transcriptase PCR detected 10 of 18 (55.5%) positive pools. A sample set of 73 organ homogenates from naturally infected American crows was also examined by WN virus antigen capture immunoassay and TaqMan for the presence of WN virus. The antigen capture assay detected antigen in 30 of 34 (88.2%) TaqMan-positive tissues. Based upon a TaqMan-generated standard curve of infectious WN virus, the limit of detection in the antigen capture assay for avian tissue homogenates was approximately 10(3) PFU/0.1 ml. The recommended WN virus antigen capture protocol, which includes a capture assay followed by a confirmatory inhibition assay used to retest presumptive positive samples, could distinguish between the closely related WN and St. Louis encephalitis viruses in virus-infected mosquito pools and avian tissues. Therefore, this immunoassay demonstrates adequate sensitivity and specificity for surveillance of WN virus activity in mosquito vectors and avian hosts, and, in addition, it is easy to perform and relatively inexpensive compared with the TaqMan assay.