Strategic Investment in Sperm Removal Behaviour in a Bushcricket

Multiple mating by females is widespread and generates sperm competition among the ejaculates of rival males over fertilization. One way in which males can avoid or reduce sperm competition is by displacing or removing previous males’ sperm from female sperm stores. An apparent example of this occurs in the bushcricket Metaplastes ornatus. Males perform a specialised sperm removal behaviour (SRB), using their highly-derived subgenital plate, with which they remove sperm from the female’s spermatheca during the early phases of mating before transferring a spermatophore of their own. Here we investigated whether males strategically invest in SRB according to the amount of previously stored sperm present in females. Each male was tested twice, once with a female containing sperm (‘filled’ condition) and once with a female from whom most previously deposited sperm had recently been removed by another male (‘emptied’ condition). For comparison, a separate group of males was paired with virgin females. Males did not discriminate between non-virgin females in the ‘emptied’ or ‘filled’ conditions in terms of their investment in SRB, suggesting they may not able to perceive the amount of sperm present in the female’s spermatheca. By contrast, male investment in SRB was significantly reduced in pairings with virgin females, indicating that males are sensitive to some aspect of a female’s mating status. Our results thus suggest that males modulate SRB in response to female-mediated cues, possibly chemical cues left by previous males, which would not be present on virgin but would be on non-virgin females.     

Habitat degradation affects the summer activity of polar bears

Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species’ distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50–75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.     

A distinctive set of genes is upregulated during the inflammation-carcinoma sequence in mouse stomach infected by Helicobacter felis.

Helicobacter pylori infects over half the population worldwide and is a leading cause of chronic gastritis and gastric cancer. However, the mechanism by which this organism induces inflammation and carcinogenesis is not fully understood. In the present study we used insulin-gastrin (INS-GAS) transgenic mice that fully develop gastric adenocarcinoma after infection of H. pylori-related Helicobacter felis. Histological examination revealed that more than half of those mice developed invasive adenocarcinoma after 8 months of infection. These carcinomas were stained by NCC-ST-439 and HECA-452 that recognize 6-sulfated and non-sulfated sialyl Lewis X. Lymphocytic infiltration predominantly to submucosa was observed in most H. felis-infected mice, and this was associated with the formation of peripheral lymph node addressin (PNAd) on high endothelial venule (HEV)-like vessels detected by MECA-79. Time-course analysis of gene expression by using gene microarray revealed upregulation of several inflammation-associated genes including chemokines, adhesion molecules, surfactant protein D (SP-D), and CD74 in the infected stomach. Immunohistochemical analysis demonstrated that SP-D is expressed in hyperplasia and adenocarcinoma whereas CD74 is expressed in adenocarcinoma in situ and invasive carcinoma. These results as a whole indicate that H. felis induces HEV-like vessels and inflammation-associated chemokines and chemokine receptors, followed by adenocarcinoma formation.     

Individual chitin synthase enzymes synthesize microfibrils of differing structure at specific locations in the Candida albicans cell wall

The shape and integrity of fungal cells is dependent on the skeletal polysaccharides in their cell walls of which beta(1,3)-glucan and chitin are of principle importance. The human pathogenic fungus Candida albicans has four genes, CHS1, CHS2, CHS3 and CHS8, which encode chitin synthase isoenzymes with different biochemical properties and physiological functions. Analysis of the morphology of chitin in cell wall ghosts revealed two distinct forms of chitin microfibrils: short microcrystalline rodlets that comprised the bulk of the cell wall; and a network of longer interlaced microfibrils in the bud scars and primary septa. Analysis of chitin ghosts of chs mutant strains by shadow-cast transmission electron microscopy showed that the long-chitin microfibrils were absent in chs8 mutants and the short-chitin rodlets were absent in chs3 mutants. The inferred site of chitin microfibril synthesis of these Chs enzymes was corroborated by their localization determined in Chsp-YFP-expressing strains. These results suggest that Chs8p synthesizes the long-chitin microfibrils, and Chs3p synthesizes the short-chitin rodlets at the same cellular location. Therefore the architecture of the chitin skeleton of C. albicans is shaped by the action of more than one chitin synthase at the site of cell wall synthesis.     

Cross-reactivity of antibodies against T-2 with deepoxide T-2 toxin

Two types of antibodies raised against T-2 toxin, namely anti-T-2-HS-BSA and anti-3 -Ac -NEOS-HS -BSA, showed good cross-reactivity with deepoxy T-2 toxin. Our results indicate that the epoxide is not an important epitope for the production of antibody against T-2 toxin     

The use of microscale processing technologies for quantification of biocatalytic Baeyer-Villiger oxidation kinetics

Microscale processing techniques would be a useful tool for the rapid and efficient collection of biotransformation kinetic data as a basis for bioprocess design. Automated liquid handling systems can reduce labor intensity while the small scale reduces the demand for scarce materials such as substrate, product, and biocatalyst. Here we illustrate this concept by establishing the use of several microwell formats (96-round, 96-deep square and 24-round well microtiter plates) for quantification of the kinetics of the E. coli TOP10 [pQR239] resting cell catalyzed Baeyer-Villiger oxidation of bicyclo[3.2.0]hept-2en-6-one using glycerol as a source of reducing power. By increasing the biocatalyst concentration until the biotransformation rate was oxygen mass-transfer limited we can ensure that kinetic data collected are in the region away from oxygen limitation. Using a 96-round well plate the effect of substrate (bicyclo[3.2.0]hept-2en-6-one) concentration on the volumetric CHMO activity was examined and compared to data collected from 1.5-L stirred-tank experiments. The phenomenon and magnitude of substrate inhibition, observed at the larger scale, was accurately reproduced in the microwell format. We have used this as an illustrative example to demonstrate that under adequately defined conditions, automated microscale processing technologies can be used for the collection of quantitative kinetic data. Additionally, by using the experimentally determined stoichiometry for product formation and glycerol oxidation, we have estimated the maximum oxygen transfer rates as a function of well geometry and agitation rate. Oxygen-transfer rates with an upper limit of between 33 mmol. L(-1). h(-1) (based solely on product formation) and 390 mmol. L(-1). h(-1) (based on product formation and glycerol oxidation) were achieved using a 96-square well format plate shaken at 1300 rpm operated with a static surface area to volume ratio of 320 m(2). m(-3).     

Force-velocity analysis of strength-training techniques and load: implications for training strategy and research

The purpose of this study was to investigate the force-velocity response of the neuromuscular system to a variety of concentric only, stretch-shorten cycle, and ballistic bench press movements. Twenty-seven men of an athletic background (21.9 +/- 3.1 years, 89.0 +/- 12.5 kg, 86.3 +/- 13.6 kg 1 repetition maximum [1RM]) performed 4 types of bench presses, concentric only, concentric throw, rebound, and rebound throw, across loads of 30-80% 1RM. Average force output was unaffected by the technique used across all loads. Greater force output was recorded using higher loading intensities. The use of rebound was found to produce greater average velocities (12.3% higher mean across loads) and peak forces (14.1% higher mean across loads). Throw or ballistic training generated greater velocities across all loads (4.4% higher average velocity and 6.7% higher peak velocity), and acceleration-deceleration profiles provided greater movement pattern specificity. However, the movement velocities (0.69-1.68 m.s(-1)) associated with the loads used in this study did not approach actual movement velocities associated with functional performance. Suggestions were made as to how these findings may be applied to improve strength, power, and functional performance.