The dispersal rate of a beetle, Osmoderma eremita, living in tree hollows

The dispersal of an endangered beetle, Osmoderma eremita, that lives in tree hollows, was studied by mark-release-recapture with pitfall traps. As only a small proportion of all dispersals is observed by this method, a simulation model was constructed to estimate the dispersal rate per individual. The model results suggest that 15% of the adults leave the original tree for another hollow tree, and consequently most individuals remain in the same tree throughout their entire life. This suggests that each hollow tree sustains a local population with limited connection with the populations in surrounding trees. It supports the view that O. eremita has a metapopulation structure, with each tree possibly sustaining a local population, and with the population in an assemblage of trees forming a metapopulation. Low dispersal rate and range make the species vulnerable to habitat fragmentation, probably at a scale of only a few hundred meters.     

Membrane Insertion of Marginally Hydrophobic Transmembrane Helices Depends on Sequence Context

In mammalian cells, most integral membrane proteins are initially inserted into the endoplasmic reticulum membrane by the so-called Sec61 translocon. However, recent predictions suggest that many transmembrane helices (TMHs) in multispanning membrane proteins are not sufficiently hydrophobic to be recognized as such by the translocon. In this study, we have screened 16 marginally hydrophobic TMHs from membrane proteins of known three-dimensional structure. Indeed, most of these TMHs do not insert efficiently into the endoplasmic reticulum membrane by themselves. To test if loops or TMHs immediately upstream or downstream of a marginally hydrophobic helix might influence the insertion efficiency, insertion of marginally hydrophobic helices was also studied in the presence of their neighboring loops and helices. The results show that flanking loops and nearest-neighbor TMHs are sufficient to ensure the insertion of many marginally hydrophobic helices. However, for at least two of the marginally hydrophobic helices, the local interactions are not enough, indicating that post-insertional rearrangements are involved in the folding of these proteins.     

Multigenic phylogeographic divergence in the paleoendemic southern Appalachian opilionid Fumontana deprehendor Shear (Opiliones, Laniatores, Triaenonychidae)

The paleoendemic opilionid Fumontana deprehendor is restricted to a small area of mid-elevation forested habitats in the southern Blue Ridge province of the Appalachian Mountains. In a recent study we reported on the discovery of 22 new montane populations of this monotypic genus, specimens from which exhibit remarkably little morphological divergence despite their separation by intervening lowlands and large riverine barriers. Here, we further explore spatial and temporal patterns of divergence in this taxon using DNA sequence data from a portion of the mitochondrial cytochrome c oxidase subunit I gene ( approximately 1000 bp) and full-length sequences of both nuclear ribosomal internal transcribed spacer regions, including the intervening 5.8S rRNA region ( approximately 700 bp total). Bayesian phylogenetic analyses of these independent data sets reveal congruent genealogical patterns, with all data partitioning and combination strategies consistently recovering five allopatric, geographically cohesive genetic clades. These clades show an almost complete lack of internal genetic divergence, with most individuals sharing a clade-specific, regionally widespread haplotype. The geographic distribution of these clades corresponds to patterns seen in other upland taxa of the region, possibly indicating coincident vicariance. Because of a lack of quantifiable morphological divergence and relatively modest levels of genetic divergence, we conservatively refer to the geographically cohesive genetic clades as "phylogeographic units", although these may actually represent cryptic species. Conservation implications and the prospect for future comparative arachnid phylogeography in the southern Appalachians are discussed in light of the results presented here.     

Restricted dispersal in a flying beetle assessed by telemetry

Many insects living in ancient trees are assumed to be threatened as a result of habitat loss and fragmentation. It is generally expected that species in habitats with low temporal variability in carrying capacity have lower degree of dispersal in comparison to those in more ephemeral habitats. As hollow trees are long-lived, species in that habitat are expected to be sensitive to habitat fragmentation, due to a low capacity to establish new populations far from present ones. Using radio telemetry, we studied the dispersal for a beetle, Osmoderma eremita, living in hollow trees. O. eremita exhibited philopatry and only dispersed over short ranges. About 82–88% of the adults remained in the tree where they were caught. All observed dispersal movements ended up in nearby hollow trees and 62% in the neighbouring hollow tree. These results corroborate the suggestion that habitat fragmentation may be detrimental to insects living in temporally stable but spatially variable habitats. In order to preserve such species, we propose that conservation efforts should be focused on maintaining or increasing the number of suitable trees in and near presently occupied stands.     

Air sampling of its pheromone to monitor the occurrence of Osmoderma eremita, a threatened beetle inhabiting hollow trees

Osmoderma eremita is a threatened scarab beetle living in the hollows of old deciduous trees and is regarded as an umbrella species of the beetle fauna associated with this habitat. Several methods like pitfall trapping and wood mould sampling have been used to monitor the occurrence of O. eremita, but these methods cannot be applied for trees with certain characteristics. Recently, (R)-(+)--decalactone was identified as a male-produced sex pheromone of the species. Here, we show that -decalactone can be detected in hollow trees by air sampling and that the presence of the compound is strongly correlated with the occurrence of living male beetles in the same trees. Air was sampled from tree cavities and extracts analysed using gas chromatography–and mass spectrometry. There was a 89% match between the detection of -decalactone in extracts and the occurrence of male O. eremita±2 days from the sampling event. In the absence of males, samples never contained -decalactone, and the presence of this compound in a tree cavity appears to be a good predictor of O. eremita occupancy. Air sampling can be a useful complement to other methods when trying to detect as many trees housing this beetle as possible, which is crucial when estimating populations sizes and developing conservation strategies for this species.     

Genealogical exclusivity in geographically proximate populations of Hypochilus thorelli Marx (Araneae,Hypochilidae) on the Cumberland Plateau of North America

The issue of sampling sufficiency is too infrequently explored in phylogeographical analysis, despite both theoretical work and analytical methods that stress the importance of sampling effort. Regarding the evolutionary pattern of reciprocal monophyly, both the probability of recovering this pattern and the possible inferences derived from this pattern, are highly contingent upon the density and geographical scale of sampling. Here, we present an empirical example that relates directly to this issue. We analyse genetic structure in the southern Appalachian spider Hypochilus thorelli, using an average sample of 5 mitochondrial DNA (mtDNA) sequences per location for 19 locations. All sampled sites are reciprocally monophyletic for mtDNA variation, even when separated by geographical distances as small as 5 km. For populations separated by greater geographical distances of 20-50 km, mtDNA sequences are not only exclusive, but are also highly divergent (uncorrected p-distances exceeding 5%). Although these extreme genealogical patterns are most seemingly consistent with a complete isolation model, both a coalescent method and nested cladistic analysis suggest that other restricted, but nonzero, gene flow models may also apply. Hypochilus thorelli appears to have maintained morphological cohesion despite this limited female-based gene flow, suggesting a pattern of stasis similar to that observed at higher taxonomic levels in Hypochilus.     

Control of smooth muscle cell proliferation in vascular disease

PURPOSE OF REVIEW: Smooth muscle cell proliferation has previously been regarded as a central feature in vascular disease. The role of this process has recently been substantially re-evaluated, and we have reconsidered the functional importance of smooth muscle cell proliferation, the origin of proliferating smooth muscle cells in lesions, and the mechanisms whereby smooth muscle cell proliferation is controlled. In this review, we summarize recent progress in the understanding of smooth muscle cell proliferation, with a particular focus on how interactions between the extracellular matrix, smooth muscle cells, and mitogens control critical steps in this process. RECENT FINDINGS: Irrespective of the origin of smooth muscle cells in vascular lesions, fundamental interactions between the extracellular matrix and cell surface integrins are necessary in order to initiate a proliferative response in a quiescent smooth muscle cell, in a similar manner to any non-malignant cell. These interactions trigger intracellular signaling and cell cycle entry, which facilitate cell cycle progression and proliferation by mitogens. In addition, extracellular matrix interactions may also control the availability and activity of growth factors such as heparin-binding mitogens, which can be sequestered by heparan sulfate containing extracellular matrix components and regulate smooth muscle cell proliferation. SUMMARY: New insights into mechanisms whereby the extracellular matrix takes part in the control of smooth muscle cell proliferation suggest a number of putative targets for future therapies that can be applied to increase plaque stability, prevent the clinical consequences of atherosclerosis and improve outcomes after interventional procedures and organ transplantation.     

A combined molecular approach to phylogeny of the jumping spider subfamily dendryphantinae (araneae: salticidae)

Four gene regions were sequenced for 30 species of jumping spiders, most from the subfamily Dendryphantinae, to investigate their molecular phylogeny and evolution. These are three regions from the mitochondria (ca. 560 bp of 16S plus adjacent tRNA, 1047 bp of cytochrome oxidase 1 (CO1), and 414 bp of NADH1 (ND1) and one region from the nuclear genome (ca. 750 bp of 28S). Parsimony and likelihood analyses of these gene regions separately and together support the monophyly of the dendryphantines as delimited previously by morphological characters. A group of elongate-bodied genera are placed as basal among the dendryphantines, and previously proposed relationships of Poultonella, Paraphidippus, and Sassacus vitis are confirmed. Comparison of overall rates of molecular evolution indicates striking differences across the gene regions, with highest divergence in ND1, CO1, 16S, and 28S in decreasing order. All four regions are characterized by both within- and among-site rate variation. Phylogenetic results from CO1 conflict conspicuously with phylogenetic results from the other genes and morphological data. Attempts to account for potential sources of this conflict (e.g., accommodating biased base composition, high homoplasy, within- and among-site rate variation, etc.) are largely unsuccessful.     

Phylogenetic utility and evidence for multiple copies of elongation factor-1alpha in the spider genus Habronattus (Araneae: Salticidae)

In the continuing quest for informative genes for use in molecular systematics, the protein-coding gene Elongation factor-1alpha (EF-1alpha) has rapidly become one of the most prevalent "single-copy" nuclear genes utilized, particularly in arthropods. This paper explores the molecular evolutionary dynamics and phylogenetic utility of EF-1alpha in the salticid spider genus Habronattus. As has been reported for other arthropod lineages, our studies indicate that multiple (two) copies of EF-1alpha exist in Habronattus. These copies differ in intron structure and thus in size, making it possible to easily separate PCR amplification products. We present data for an intronless EF-1alpha copy for three Habronattus species. The presence of nonsense mutations and generally elevated rates of amino acid change suggest that this copy is evolving under relaxed functional constraints in Habronattus. A larger taxon sample (50 species plus outgroups) is presented for an EF-1alpha copy that includes both intron and exon regions. Characteristics of both regions suggest that this is a functional, orthologous copy in the species sampled. Maximum-likelihood relative-rate comparisons show that exon third codon sites are evolving more than 100 times as fast as second codon sites in these sequences and that intron sites are evolving about twice as fast as exon third sites. In combination, the EF-1alpha data provide robust, species-level phylogenetic signal that is largely congruent with morphologically well supported areas of Habronattus phylogeny. The recovery of some novel clades, and the unexpected fragmentation of others, suggests areas requiring further phylogenetic attention.     

Effects of staurosporine,U-73122, wortmannin, 4-hydroxynonenal and sodium azide upon the release of secreted β-amyloid precursor protein from human platelets in response to thrombin stimulation

In the present study, the release of secreted -amyloid precursor protein (APPs) in response to thrombin stimulation in platelets has been investigated. Incubation of platelets with thrombin produced a concentration-dependent release of APPs with a concomitant reduction in the APP remaining in the lysates. The response to thrombin was not affected by pretreatment for 15 min with the phospholipase C inhibitor U-73122, with the protein kinase C inhibitor staurosporine, or with hydrogen peroxide (which at the concentrations used affects the phosphoinositide signalling system in human platelets). In contrast, pretreatment with wortmannin and sodium azide reduced the responses to thrombin. These data would suggest that thrombin may cause the release of APPs from human platelets via an activation of a phospholipase C-independent pathway. Thrombin-stimulated APPs release was also reduced by 4-hydroxynonenal. This finding, if it is a phenomenon also found for CNS cells, could be of relevance to the pathogenesis of Alzheimer's disease, given that an accumulation of 4-hydroxynonenal is found in this disease.