Fecundity and MHC affects ejaculation tactics and paternity bias in sand lizards

We demonstrate that extending copulation enhances probability of paternity in sand lizards and that determinants of copulation duration depend on a males' mating order (first or second). First males, with no information on presence of rivals, extend copulation when mating with a more fecund female. Second males, however, adjust copula duration in relation to a first male's relatedness with his female, which there is reason to believe can be deduced from the MHC-related odor of the copulatory plug. Male-female relatedness negatively influences a male's probability of paternity, and when second males are in a favored role (i.e., the first male is the one more closely related to the female), second males transfer larger ejaculates, resulting in higher probability of paternity. This result corroborates predictions from recent theoretical models on sperm expenditure theory incorporating cryptic female choice and sexual conflict. More specifically, the results conform to a "random roles" model, which depicts males as being favored by some females and disfavored by others, but not to a "constant-type" model, in which a male is either favored or disfavored uniformly by all females in a population.     

Microvillar membrane microdomains exist at physiological temperature. Role of galectin-4 as lipid raft stabilizer revealed by "superrafts"

Lipid rafts (glycosphingolipid/cholesterol-enriched membrane microdomains) have been isolated as low temperature, detergent-resistant membranes from many cell types, but despite their presumed importance as lateral sorting and signaling platforms, fundamental questions persist concerning raft function and even existence in vivo. The nonionic detergent Brij 98 was used to isolate lipid rafts from microvillar membrane vesicles of intestinal brush borders at physiological temperature to compare with rafts, obtained by "conventional" extraction using Triton X-100 at low temperature. Microvillar rafts prepared by the two protocols were morphologically different but had essentially similar profiles of protein- and lipid components, showing that raft microdomains do exist at 37 degrees C and are not "low temperature artifacts." We also employed a novel method of sequential detergent extraction at increasing temperature to define a fraction of highly detergent-resistant "superrafts." These were enriched in galectin-4, a beta-galactoside-recognizing lectin residing on the extracellular side of the membrane. Superrafts also harbored the glycosylphosphatidylinositol-linked alkaline phosphatase and the transmembrane aminopeptidase N, whereas the peripheral lipid raft protein annexin 2 was essentially absent. In conclusion, in the microvillar membrane, galectin-4, functions as a core raft stabilizer/organizer for other, more loosely raft-associated proteins. The superraft analysis might be applicable to other membrane microdomain systems.     

Enzymatic catalysis in microemulsions: enzyme reuse and product recovery

A technique for enzyme reuse and product recovery from enzymatic catalysis in microemulsions is demonstrated. The enzymatic reaction is performed in a homogeneous isotropic microemulsion; AOT (sodium bis-(2-ethyl- hexyl)sulfosuccinate)/isooctane/buffer or C(12)E(5)(penta ethylene glycol dodecyl ether)/heptane/buffer. By small temperature changes the systems are shifted to two phase regions, where an oil-rich phase, containing the product, coexists with a water-rich phase containing surfactant and enzyme. The oil-rich phase may be replaced by an oil solution containing new substrate. Thus, the reaction may be continued and the enzyme reused. This procedure was repeated nine times in the present study. Data on phase behavior in presence and in absence of protein, partitioning of the components and a radioactive-labelled protein between the phases, and the repeated use of horse liver alcohol dehydrogenase (HLADH) in the microemulsions are presented.     

Genetic Barriers to Historical Gene Flow between Cryptic Species of Alpine Bumblebees Revealed by Comparative Population Genomics

Evidence is accumulating that gene flow commonly occurs between recently diverged species, despite the existence of barriers to gene flow in their genomes. However, we still know little about what regions of the genome become barriers to gene flow and how such barriers form. Here, we compare genetic differentiation across the genomes of bumblebee species living in sympatry and allopatry to reveal the potential impact of gene flow during species divergence and uncover genetic barrier loci. We first compared the genomes of the alpine bumblebee Bombus sylvicola and a previously unidentified sister species living in sympatry in the Rocky Mountains, revealing prominent islands of elevated genetic divergence in the genome that colocalize with centromeres and regions of low recombination. This same pattern is observed between the genomes of another pair of closely related species living in allopatry (B. bifarius and B. vancouverensis). Strikingly however, the genomic islands exhibit significantly elevated absolute divergence (d_XY) in the sympatric, but not the allopatric, comparison indicating that they contain loci that have acted as barriers to historical gene flow in sympatry. Our results suggest that intrinsic barriers to gene flow between species may often accumulate in regions of low recombination and near centromeres through processes such as genetic hitchhiking, and that divergence in these regions is accentuated in the presence of gene flow.     

Monitoring novel metabolic pathways using metabolomics and machine learning: induction of the phosphoketolase pathway in Aspergillus nidulans cultivations

The physiological phenotype of Aspergillus nidulans was determined under different environmental conditions through the quantification of the intracellular and extracellular metabolite pools and clear evidence of the presence of a novel fungal metabolic pathway, the phosphoketolase pathway, was obtained. Induction of the phosphoketolase pathway resulted after blocking the EMP pathway through the deactivation of glyceraldehyde-3-P dehydrogenase (G3PD). Deactivation of G3PD in cultivations of A. nidulans on glucose and xylose led to a 10-fold decrease in the specific growth rate; however, growth could still be sustained solely through the phosphoketolase pathway. Metabolomics and machine learning tools were successfully used to monitor the alteration caused by the inhibition of G3PD in the metabolism of A. nidulans grown on glucose, xylose, acetate as well as mixtures of glucose or xylose with acetate. This is the first study that demonstrates in vivo that the fungal central carbon metabolism includes an active phosphoketolase pathway.     

Challenges in enzymatic hydrolysis and fermentation of pretreated Arundo donax revealed by a comparison between SHF and SSF

The perennial herbaceous crop Arundo donax is a potential feedstock for second-generation bioethanol production. In the present work, two different process options were investigated for the conversion of two differently steam-pretreated batches of A. donax. The pretreated raw material was converted to ethanol with a xylose-consuming Saccharomyces cerevisiae strain, VTT C-10880, by applying either separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). The highest overall ethanol yield and final ethanol concentration were achieved using SHF (0.27 g g^?1 and 20.6 g L^?1 compared to 0.24 g g^?1 and 19.0 g L^?1 when SSF was used). The performance of both SHF and SSF was improved by complementing the cellulolytic enzymes with hemicellulases. The higher amount of acetic acid in one of the batches was shown to strongly affect xylose consumption in the fermentation. Only half of the xylose was consumed when batch 1 (high acetic acid) was fermented, compared to that 94% of the xylose was consumed in fermentation of batch 2 (lower acetic acid). Furthermore, the high amount of xylooligomers present in the pretreated materials considerably inhibited the enzymatic hydrolysis. Both the formation of xylooligomers and acetic acid thus need to be considered in the pretreatment process in order to achieve efficient conversion of A. donax to ethanol.     

Detection of Helicobacter in the liver of patients with chronic cholestatic liver diseases.

Helicobacter species were identified in human liver tissues by PCR. Biopsies were obtained from patients with primary sclerosing cholangitis, primary biliary cirrhosis and noncholestatic liver cirrhosis. One set of Helicobacter genus-specific primers and two different primer sets for Helicobacter pylori were used in the PCR-assays. Using Helicobacter genus-specific primers 80% (8/10) of patients with primary sclerosing cholangitis and 90% (9/10) of patients with primary biliary cirrhosis were positive. Seven of these 17 samples were positive using two different primers for H. pylori and Southern blot hybridization. Among the non-cholestatic liver cirrhosis controls, only one sample was positive in the Helicobacter genus-specific PCR-assay. Significantly higher values of alkaline phosphatases and prothrombin complex was found for the patients positive for Helicobacter genus. In conclusion, gene sequences of Helicobacter species and H. pylori were detected in human liver tissue using PCR and DNA hybridization in patients with a cholestatic liver disease, but rarely in noncholestatic liver cirrhosis.     

Facultative sex allocation in snow skink lizards (Niveoscincus microlepidotus)

Mathematical models suggest that reproducing females may benefit by facultatively adjusting their relative investment into sons vs. daughters, in response to population‐wide shifts in operational sex ratio (OSR). Our field studies on viviparous alpine skinks (Niveoscincus microlepidotus) document such a case, whereby among‐ and within‐year shifts in OSR were followed by shifts in sex allocation. When adult males were relatively scarce, females produced male‐biased litters and larger sons than daughters. The reverse was true when adult males were relatively more common. That is, females that were courted and mated by few males produced mainly sons (and these were larger than daughters), whereas females that were courted and mated by many males produced mainly daughters (and these were larger than sons). Maternal body size and condition also covaried with sex allocation, and the shifting pattern of sexual size dimorphism at birth may reflect these correlated effects rather than a discrete component of an evolved sex‐allocation strategy.