Gene expression analysis of the ovary of hybrid females of Xenopus laevis and X. muelleri

<p>Abstract</p> <p>Background</p> <p>Interspecific hybrids of frogs of the genus <it>Xenopus </it>result in sterile hybrid males and fertile hybrid females. Previous work has demonstrated a dramatic asymmetrical pattern of misexpression in hybrid males compared to the two parental species with relatively few genes misexpressed in comparisons of hybrids and the maternal species (<it>X. laevis</it>) and dramatically more genes misexpressed in hybrids compared to the paternal species (<it>X. muelleri</it>). In this work, we examine the gene expression pattern in hybrid females of <it>X. laevis </it>× <it>X. muelleri </it>to determine if this asymmetrical pattern of expression also occurs in hybrid females.</p> <p>Results</p> <p>We find a similar pattern of asymmetry in expression compared to males in that there were more genes differentially expressed between hybrids and <it>X. muelleri </it>compared to hybrids and <it>X. laevis</it>. We also found a dramatic increase in the number of misexpressed genes with hybrid females having about 20 times more genes misexpressed in ovaries compared to testes of hybrid males and therefore the match between phenotype and expression pattern is not supported.</p> <p>Conclusion</p> <p>We discuss these intriguing findings in the context of reproductive isolation and suggest that divergence in female expression may be involved in sterility of hybrid males due to the inherent sensitivity of spermatogenesis as defined by the faster male evolution hypothesis for Haldane's rule.</p

NASP aeroservothermoelasticity studies

Some illustrative results obtained from work accomplished under the aerothermoelasticity work breakdown structure (WBS) element of the National Aerospace Plane (NASP) Technology Maturation Program (TMP) are presented and discussed. The objectives of the aerothermoelasticity element were to develop analytical methods applicable to aerospace plane type configurations, to conduct analytical studies to identify potential problems, to evaluate potential solutions to problems, and to provide an experimental data base to verify codes and analytical trends. Work accomplished in the three areas of experimental data base, unsteady aerodynamics, and integrated analysis methodology are described. Some of the specific topics discussed are: (1) transonic wind tunnel aeroelastic model tests of cantilever delta wing models, of an all-moveable delta-wing model, and of aileron buzz models; (2) unsteady aerodynamic theory correlation with experiment and theory improvements; and (3) integrated analysis methodology results for thermal effects on vibration, for thermal effects on flutter, and for improving aeroelastic performance by using active controls

Activation of the Bile Acid Pathway and No Observed Antimicrobial Peptide Sequences in the Skin of a Poison Frog

The skin secretions of many frogs have genetically-encoded, endogenous antimicrobial peptides (AMPs). Other species, especially aposematic poison frogs, secrete exogenously derived alkaloids that serve as potent defense molecules. The origins of these defense systems are not clear, but a novel bileacid derived metabolite, tauromantellic acid, was recently discovered and shown to be endogenous in poison frogs (Mantella, Dendrobates, and Epipedobates). These observations raise questions about the evolutionary history of AMP genetic elements, the mechanism and function of tauromatellic acid production, and links between these systems. To understand the diversity and expression of AMPs among frogs, we assembled skin transcriptomes of 13 species across the anuran phylogeny. Our analyses revealed a diversity of AMPs and AMP expression levels across the phylogenetic history of frogs, but no observations of AMPs in Mantella. We examined genes expressed in the bile-acid metabolic pathway and found that CYP7A1 (Cytochrome P450), BAAT (bile acid-CoA: amino acid N-acyltransferase), and AMACR (alphamethylacyl- CoA racemase) were highly expressed in the skin of M. betsileo and either lowly expressed or absent in other frog species. In particular, CYP7A1 catalyzes the first reaction in the cholesterol catabolic pathway and is the rate-limiting step in regulation of bile acid synthesis, suggesting unique activation of the bile acid pathway in Mantella skin. The activation of the bile acid pathway in the skin of Mantella and the lack of observed AMPs fuel new questions about the evolution of defense compounds and the ectopic expression of the bile-acid pathway

Recombinant vacuolar iron transporter family homologue PfVIT from human malaria-causing Plasmodium falciparum is a Fe2+/H+ exchanger

This work was funded in part by a Royal Society Wolfson Research Merit Award (to J.P.D). It was also supported by the Wellcome Trust (grant number WT079272AIA) which funded the MALDI TOF-TOF analyser at the BSRC Mass Spectrometry and Proteomics Facility, University of St Andrews. P.L was supported by a Northern Ireland Department of Employment and Learning (DEL) postgraduate studentship.Vacuolar iron transporters (VITs) are a poorly understood family of integral membrane proteins that can function in iron homeostasis via sequestration of labile Fe2+ into vacuolar compartments. Here we report on the heterologous overexpression and purification of PfVIT, a vacuolar iron transporter homologue from the human malaria-causing parasite Plasmodium falciparum. Use of synthetic, codon-optimised DNA enabled overexpression of functional PfVIT in the inner membrane of Escherichia coli which, in turn, conferred iron tolerance to the bacterial cells. Cells that expressed PfVIT had decreased levels of total cellular iron compared with cells that did not express the protein. Qualitative transport assays performed on inverted vesicles enriched with PfVIT revealed that the transporter catalysed Fe2+/H+ exchange driven by the proton electrochemical gradient. Furthermore, the PfVIT transport function in this system did not require the presence of any Plasmodium-specific factor such as post-translational phosphorylation. PfVIT purified as a monomer and, as measured by intrinsic protein fluorescence quenching, bound Fe2+ in detergent solution with low micromolar affinity. This study of PfVIT provides material for future detailed biochemical, biophysical and structural studies to advance understanding of the vacuolar iron transporter family of membrane proteins from important human pathogens.Publisher PDFPeer reviewe

A simple method for estimating larval supply in reef fishes and a preliminary test of population limitation by larval delivery in the kelp bass \u3cem\u3eParalabrax clathratus\u3c/em\u3e

This paper describes a method for estimating larval supply of a temperate reef fish, the kelp bass Paralabrax clathratus, that is simple, inexpensive, requires relatively low effort, and integrates larval supply over time. Using this method, we sampled larval supply concurrently at 4 sites spread over about 35 km for nearly an entire settlement season. With these data and visual estimates of recruitment (the density of young-of-the-year after the end of the settlement season), we tested the hypothesis that spatial patterns in recruitment were set by larval supply. This hypothesis was rejected: kelp bass recruitment to the 4 sites was not related to patterns of larval supply. Furthermore, in contrast to the findings of an earlier study, recruitment was not related to the density of the macroalga Macrocystis pyrifera. Recruitment was, however, strongly correlated with the density of 1 yr old kelp bass, suggesting that spatial patterns of recruitment were consistent between the 2 cohorts. Recruitment, however, was not correlated with the density of bass 2+ yr old. We also measured larval supply in a second year and found that spatial patterns of supply were strongly correlated between years at a relatively small scale of 10s to 100s m, but not at a larger scale of several km. This finding suggests that some deterministic process (or set of processes) sets spatial patterns of larval supply at small, but not large scales. At large scales, consistent patterns of recruitment between 2 cohorts in the face of variable larval supply suggest that deterministic, postsettlement processes may generate predictable patterns of recruitment even when the supply of larvae is variable. In addition to demonstrating that spatial patterns in the abundance of demersal fish are not always well predicted by larval supply, this study introduces a technique that may facilitate more thorough exploration of the role of larval supply in determining the dynamics of populations of reef fishes

Volcanic Initiation of the Eocene Heart Mountain Slide, Wyoming, USA

The Eocene Heart Mountain slide of northwest Wyoming covers an area of as much as 5000 km2 and includes allochthonous Paleozoic carbonate and Eocene volcanic rocks with a run-out distance of as much as 85 km. Recent geochronologic data indicated that the emplacement of the slide event occurred at ∼48.9 Ma, using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) extracted from U-Pb zircon ages from basal layer and injectite carbonate ultracataclasite (CUC). We now refine that age with U-Pb results from a lamprophyre diatreme that is temporally and spatially related to the CUC injectites. The ages for the lamprophyre zircons are 48.97 ± 0.36 Ma (LA-ICPMS) and 49.19 ±0.02 Ma (chemical abrasion isotope dilution thermal ionization mass spectrometry). Thus, the lamprophyre and CUC zircons are identical in age, and we interpret that the zircons in the CUC were derived from the lamprophyre during slide emplacement. Moreover, the intrusion of the lamprophyre diatreme provided the trigger mechanism for the Heart Mountain slide. Additional structural data are presented for a variety of calcite twinning strains, results from anisotropy of magnetic susceptibility for the lamprophyre and CUC injectites and alternating-field demagnetization on the lamprophyre, to help constrain slide dynamics. These data indicate that White Mountain experienced a rotation about a vertical axis and minimum of 35° of counterclockwise motion during emplacement

Germline-dependent gene expression in distant non-gonadal somatic tissues of Drosophila

<p>Abstract</p> <p>Background</p> <p><it>Drosophila </it>females commit tremendous resources to egg production and males produce some of the longest sperm in the animal kingdom. We know little about the coordinated regulation of gene expression patterns in distant somatic tissues that support the developmental cost of gamete production.</p> <p>Results</p> <p>We determined the non-gonadal gene expression patterns of <it>Drosophila </it>females and males with or without a germline. Our results show that germline-dependent expression in the non-gonadal soma is extensive. Interestingly, gene expression patterns and hormone titers are consistent with a hormone axis between the gonads and non-gonadal soma.</p> <p>Conclusions</p> <p>The germline has a long-range influence on gene expression in the <it>Drosophila </it>sexes. We suggest that this is the result of a germline/soma hormonal axis.</p

Biodiversity, drug discovery, and the future of global health:Introducing the biodiversity to biomedicine consortium, a call to action

First paragraph: Looking to nature for medicine is nothing new – we have been doing it for tens of thousands of years and although modern pharmaceutical science has come a long way from those ancient roots, nature is and will always be an important source of useful compounds and inspiration. Dismissing nature in this regard is a huge mistake as evolution is the greatest problem solver and the myriad compounds produced by the immense variety of species we share the planet with have been honed by three billion years of trial and error. However, with every bit of habitat that disappears under the plough or concrete we impoverish nature and deprive ourselves of potential medicines.Additional co-authors: Uttam Babu Shrestha, Milica Pešić, Alexander Kagansk

Biodiversity, drug discovery, and the future of global health: Introducing the biodiversity to biomedicine consortium, a call to action

Looking to nature for medicine is nothing new – we have been doing it for tens of thousands of years and although modern pharmaceutical science has come a long way from those ancient roots, nature is and will always be an important source of useful compounds and inspiration. Dismissing nature in this regard is a huge mistake as evolution is the greatest problem solver and the myriad compounds produced by the immense variety of species we share the planet with have been honed by three billion years of trial and error. However, with every bit of habitat that disappears under the plough or concrete we impoverish nature and deprive ourselves of potential medicines