The metalloprotease SepA governs processing of accumulation‐associated protein and shapes intercellular adhesive surface properties in Staphylococcus epidermidis

The otherwise harmless skin inhabitant Staphylococcus epidermidis is a major cause of healthcare‐associated medical device infections. The species' selective pathogenic potential depends on its production of surface adherent biofilms. The Cell wall‐anchored protein Aap promotes biofilm formation in S. epidermidis, independently from the polysaccharide intercellular adhesin PIA. Aap requires proteolytic cleavage to act as an intercellular adhesin. Whether and which staphylococcal proteases account for Aap processing is yet unknown. Here, evidence is provided that in PIA‐negative S. epidermidis 1457Δica, the metalloprotease SepA is required for Aap‐dependent S. epidermidis biofilm formation in static and dynamic biofilm models. qRT‐PCR and protease activity assays demonstrated that under standard growth conditions, sepA is repressed by the global regulator SarA. Inactivation of sarA increased SepA production, and in turn augmented biofilm formation. Genetic and biochemical analyses demonstrated that SepA‐related induction of biofilm accumulation resulted from enhanced Aap processing. Studies using recombinant proteins demonstrated that SepA is able to cleave the A domain of Aap at residue 335 and between the A and B domains at residue 601. This study identifies the mechanism behind Aap‐mediated biofilm maturation, and also demonstrates a novel role for a secreted staphylococcal protease as a requirement for the development of a biofilm.     

Climatic effects on timing of spring migration and breeding in a long-distance migrant, the pied flycatcher Ficedula hypoleuca

Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient to maintain the synchrony with their main food sources. The timing of arrival in the breeding areas from their African wintering grounds is likely to constrain the advancement of breeding date. We hypothesise that this is because in Africa they cannot predict the advancement of spring in their breeding habitat. However, long-distance migrants may advance their arrival time by migrating faster when circumstances en route are favourable. In this study we show that both arrival and breeding date depend on temperatures at their main North African staging grounds, as well as on temperature at the breeding grounds. Male arrival and average laying date were not correlated, but the positive effect of temperature in North Africa on breeding dates suggests that breeding date is indeed constrained by arrival of females. Long-distance migrants thus are able to adjust arrival and hence breeding by faster spring migration, but the degree of adjustment is probably limited as timing schedules in spring are tight. Furthermore, as climate change is affecting temperatures differently along the migratory flyway and the breeding areas, it is unlikely that arrival dates are advanced at the same rate as the timing of breeding should advance, given the advancement of the underlying levels of the food chain.     

Marriage Timing over the Generations

Strong relationships have been hypothesized between the timing of marriage and the familial environment of the couple. Sociologists have identified various mechanisms via which the age at marriage in the parental generation might be related to the age at marriage of the children. In our paper we study this relationship for historical populations. We use a dataset consisting of several hundreds of thousands of marriages contracted in three of the 11 Dutch provinces between 1812 and 1922. We identified the generational links between the brides, grooms, their parents, and grandparents. We studied (a) whether there is a relationship between ages at marriage of (grandfathers) fathers and sons, and ages at marriage of (grandmothers) mothers and daughters and (b) whether this relationship might be explained by social class. We find evidence for a clear effect of the family on age at marriage and substantial intergenerational transmission. The impact that the family of origin has on age at entry into marriage can partly be attributed to social class. We also observed positive effects of grandparents’ age at marriage on their offspring’s age at marriage.

Exercise training with ageing protects against ethanol induced myocardial glutathione homeostasis

Glutathione plays a central role in the maintenance of cellular antioxidant defense. The alterations in the glutathione and associated recyclic enzymes caused by both exercise training and ethanol are well documented; however, their interactive effects with age are not well understood. Therefore, the influence of ageing and the interactive effects of exercise training and ethanol on the myocardial glutathione system in 3 months and 18 months old rats were examined. The results showed a significant (p<0.01) reduction in GSH content, Se and non-Se GSH-Px, GR and GST activities in the myocardium of rat with age. A significant increase (p<0.05) in the activities of these enzymes was observed in both age groups of rats in response to exercise training. This exercise-induced elevation of Se and non-Se GSH-Px and GR activities was more pronounced in the 18 months old rats when compared to 3 months old rats. Ethanol consumption significantly (p<0.05) reduced the GSH content, Se and non-Se GSH-Px and GR activities in both age groups of rats. In contrast, ethanol consumption significantly (p<0.05) increased the activity of GST. The combined action of exercise plus ethanol significantly (p<0.05) elevated the GSH content, Se and non-Se GSH-Px, GR and GST activities when compared to the ethanol treated rats in both age groups, indicating the suppression of ethanol-induced oxidative stress by exercise training. In conclusion, there was a compensatory myocardial response lessening ethanol-induced oxidative stress by exercise training, which seemed to result from the higher activity of glutathione recycling and utilizing enzymes, which may be critical for preventing chronic oxidative damage to the myocardium during ageing and even due to ethanol consumption.     

Marine invasive species: validation of citizen science and implications for national monitoring networks

Approximately 1,000 volunteers assessed the presence of invasive (Carcinus maenas and Hemigrapsus sanguineus) and native crabs within the intertidal zone of seven coastal states of the US, from New Jersey to Maine. Identification of crab species and determination of the gender of the observed crabs was documented at all 52 sites across a 725-km coastal transect. Using quantitative measures of accuracy of data collected by citizen scientists, a significant predictor of a volunteer’s ability was determined and eligibility criteria were set. Students in grade three and seven had the ability to differentiate between species of crabs with over 80% and 95% accuracy, respectively. Determination of gender of the crabs was more challenging and accuracy exceeded 80% for seventh grade students, while 95% accuracy was found for students with at least 2 years of university education. We used the data collected by citizen scientists to create a large-scale standardized database of the distribution and abundance of the native and invasive crabs. Hemigrapsus sanguineus dominated the rocky intertidal zone from Sandy Hook, New Jersey to Boston Harbor, Massachusetts while C. maenas dominated the northern extent of the sampled coastline. A citizen scientist of this monitoring network detected a range expansion of H. sanguineus. We identified obstacles to creating a national monitoring network and proposed recommendations that addressed these issues.     

The evolutionary dynamics of the lion Panthera leo revealed by host and viral population genomics

The lion Panthera leo is one of the world's most charismatic carnivores and is one of Africa's key predators. Here, we used a large dataset from 357 lions comprehending 1.13 megabases of sequence data and genotypes from 22 microsatellite loci to characterize its recent evolutionary history. Patterns of molecular genetic variation in multiple maternal (mtDNA), paternal (Y-chromosome), and biparental nuclear (nDNA) genetic markers were compared with patterns of sequence and subtype variation of the lion feline immunodeficiency virus (FIV(Ple)), a lentivirus analogous to human immunodeficiency virus (HIV). In spite of the ability of lions to disperse long distances, patterns of lion genetic diversity suggest substantial population subdivision (mtDNA Phi(ST) = 0.92; nDNA F(ST) = 0.18), and reduced gene flow, which, along with large differences in sero-prevalence of six distinct FIV(Ple) subtypes among lion populations, refute the hypothesis that African lions consist of a single panmictic population. Our results suggest that extant lion populations derive from several Pleistocene refugia in East and Southern Africa ( approximately 324,000-169,000 years ago), which expanded during the Late Pleistocene ( approximately 100,000 years ago) into Central and North Africa and into Asia. During the Pleistocene/Holocene transition ( approximately 14,000-7,000 years), another expansion occurred from southern refugia northwards towards East Africa, causing population interbreeding. In particular, lion and FIV(Ple) variation affirms that the large, well-studied lion population occupying the greater Serengeti Ecosystem is derived from three distinct populations that admixed recently.