New records for prehistoric introduction of Neotropical mammals to the West Indies: evidence from Carriacou,Lesser Antilles

Aim This paper investigates the prehistoric introduction of five mammalian taxa to Carriacou (Lesser Antilles) and refines the known anthropogenic ranges for these fauna in the pre‐Columbian West Indies. The importance of such records for understanding the region’s historical biogeography and ecology is considered. Location Carriacou Island, Grenada (12°28′ N, 61°26′ W). Methods Zooarchaeological assemblages from Carriacou’s earliest documented prehistoric sites, Grand Bay and Sabazan, were analysed, and exotic taxa were identified and quantified. The timing of introductions was established based on multiple radiocarbon assays, including three new accelerator mass spectrometry (AMS) direct dates obtained on the bone of exotic taxa. Source species and location(s) are considered and compared with known prehistoric records for the Caribbean to synthesize anthropogenic distributions for the pre‐Columbian period. The contexts of the zooarchaeological remains are evaluated to better understand the nature and purpose of introductions. Results Zooarchaeological investigation on Carriacou reveals the occurrence of multiple mammal introductions from South American between c. ad 700 and ad 1400. This paper presents the first records for guinea pig (Cavia sp.), armadillo (Dasypus sp.), peccary (Tayassu/Pecari sp.), opossum (Didelphis sp.) and agouti (Dasyprocta sp.) from the island. Human‐mediated transport of these taxa is indicated by their absence from the record prior to human settlement of Carriacou. Several translocated species are either rare or entirely unknown for the region, and overall West Indian distributions are temporally and spatially discontinuous. Archaeological contexts indicate that mammalian introductions arose from human subsistence needs, but other social factors may have shaped the dispersal of these fauna. Main conclusions The taxonomic combination and richness of Carriacou’s introduced fauna are unusual within the region. Importantly, the new records significantly improve the known pre‐Columbian geographic range for peccary, guinea pig and armadillo. Integrated with regional records, these data augment our understanding of the Caribbean’s historical biogeography, and have the potential to improve our understanding of human mobility and anthropogenic environmental impacts in the West Indies prior to the arrival of Europeans.     

Variation in breeding parameters of Eleonora’s falcon (Falco eleonorae) and factors affecting its reproductive performance

We gathered data for a four-year period (2004?C2007) on the nesting ecology and reproductive performance of Eleonora??s falcon in the Aegean Sea. We investigated in an indirect way the relation between clutch size and pre-laying food availability, the significance of site and pair quality on productivity, and the effects of habitat and intraspecific competition on breeding success. Overall, the species selected nest sites sheltered from sun exposure but not from the prevailing wind. Hatching, fledging, and breeding success rates were estimated at 64, 72%, and 60%, respectively. Fledglings per breeding pair ranged from 1.19 to 1.75, and fledglings per successful pair from 1.84 to 2.0, between the years. Productivity depended on parental care rather than nest-site quality. Breeding parameters varied significantly between the years, exhibiting a strong spatial yet local effect. Low success rates were recorded in specific colonies, which were attributed to adverse weather conditions and habitat degradation. Insect food availability prior to egg-laying, estimated via plant biomass, was positively correlated to clutch size. Meanwhile, low wind strengths in August, large distances from the mainland, and population size in the vicinity of the colonies had negative effects on breeding success. Considering data at the Mediterranean scale, a longitudinal trend is observed across the breeding range of this species, with breeding parameters slightly decreasing from west to east.     

Different contributions of HtrA protease and chaperone activities to Campylobacter jejuni stress tolerance and physiology

The microaerophilic bacterium Campylobacter jejuni is the most common cause of bacterial food-borne infections in the developed world. Tolerance to environmental stress relies on proteases and chaperones in the cell envelope, such as HtrA and SurA. HtrA displays both chaperone and protease activities, but little is known about how each of these activities contributes to stress tolerance in bacteria. In vitro experiments showed temperature-dependent protease and chaperone activities of C. jejuni HtrA. A C. jejuni mutant lacking only the protease activity of HtrA was used to show that the HtrA chaperone activity is sufficient for growth at high temperature or under oxidative stress, whereas the HtrA protease activity is essential only under conditions close to the growth limit for C. jejuni. However, the protease activity was required to prevent induction of the cytoplasmic heat shock response even under optimal growth conditions. Interestingly, the requirement of HtrA at high temperatures was found to depend on the oxygen level, and our data suggest that HtrA may protect oxidatively damaged proteins. Finally, protease activity stimulates HtrA production and oligomer formation, suggesting that a regulatory role depends on the protease activity of HtrA. Studying a microaerophilic organism encoding only two known periplasmic chaperones (HtrA and SurA) revealed an efficient HtrA chaperone activity and proposed multiple roles of the protease activity, increasing our understanding of HtrA in bacterial physiology.     

The 1.6 ? Crystal Structure of Pyranose Dehydrogenase from Agaricus meleagris Rationalizes Substrate Specificity and Reveals a Flavin Intermediate

Pyranose dehydrogenases (PDHs) are extracellular flavin-dependent oxidoreductases secreted by litter-decomposing fungi with a role in natural recycling of plant matter. All major monosaccharides in lignocellulose are oxidized by PDH at comparable yields and efficiencies. Oxidation takes place as single-oxidation or sequential double-oxidation reactions of the carbohydrates, resulting in sugar derivatives oxidized primarily at C2, C3 or C2/3 with the concomitant reduction of the flavin. A suitable electron acceptor then reoxidizes the reduced flavin. Whereas oxygen is a poor electron acceptor for PDH, several alternative acceptors, e.g., quinone compounds, naturally present during lignocellulose degradation, can be used. We have determined the 1.6-Å crystal structure of PDH from Agaricus meleagris. Interestingly, the flavin ring in PDH is modified by a covalent mono- or di-atomic species at the C(4a) position. Under normal conditions, PDH is not oxidized by oxygen; however, the related enzyme pyranose 2-oxidase (P2O) activates oxygen by a mechanism that proceeds via a covalent flavin C(4a)-hydroperoxide intermediate. Although the flavin C(4a) adduct is common in monooxygenases, it is unusual for flavoprotein oxidases, and it has been proposed that formation of the intermediate would be unfavorable in these oxidases. Thus, the flavin adduct in PDH not only shows that the adduct can be favorably accommodated in the active site, but also provides important details regarding the structural, spatial and physicochemical requirements for formation of this flavin intermediate in related oxidases. Extensive in silico modeling of carbohydrates in the PDH active site allowed us to rationalize the previously reported patterns of substrate specificity and regioselectivity. To evaluate the regioselectivity of D-glucose oxidation, reduction experiments were performed using fluorinated glucose. PDH was rapidly reduced by 3-fluorinated glucose, which has the C2 position accessible for oxidation, whereas 2-fluorinated glucose performed poorly (C3 accessible), indicating that the glucose C2 position is the primary site of attack.     

The Erwin equation of biodiversity: From little steps to quantum leaps in the discovery of tropical insect diversity

Almost 40 years ago, Terry L. Erwin published a seemingly audacious proposition: There may be as many as 30 million species of insects in the world. Here, we translate Erwin's verbal argument into a diversity-ratio model—the Erwin Equation of Biodiversity—and discuss how it has inspired other biodiversity estimates. We categorize, describe the assumptions for, and summarize the most commonly used methods for calculating estimates of global biodiversity. Subsequent diversity-ratio extrapolations have incorporated parameters representing empirical insect specialization ratios, and how insect specialization changes at different spatial scales. Other approaches include macroecological diversity models and diversity curves. For many insect groups with poorly known taxonomies, diversity estimates are based on the opinions of taxonomic experts. We illustrate our current understanding of insect diversity by focusing on the six most speciose insect orders worldwide. For each order, we compiled estimates of the (a) maximum estimated number of species, (b) minimum estimated number of species, and (c) number of currently described species. By integrating these approaches and considering new information, we believe an estimate of 5.5 million species of insects in the world is much too low. New molecular methodologies (e.g., metabarcoding and NGS studies) are revealing daunting numbers of cryptic and previously undescribed species, at the same time increasing our precision but also uncertainty about present estimates. Not until technologies advance and sampling become more comprehensive, especially of tropical biotas, will we be able to make robust estimates of the total number of insect species on Earth.     

Interlinking interleukin-7

The signaling processes that maintain the homeostatic proliferation of peripheral T-cells and result in their self-renewal largely remain to be elucidated. Much focus has been placed on the anti-apoptotic function of the cytokine, interleukin-7 (IL-7), during T-cell development. But a more critical role has been ascribed to IL-7 as a mediator of peripheral T-cell maintenance. The biological effects responsive to IL-7 signaling are transduced through only a few well-known pathways. In this review we will focus on the signals transduced by IL-7 and similar cytokines, examining how proliferative signals originate from cytokine receptors, are amplified and eventually alter gene expression. In this regard we will highlight the crosstalk between pathways that promote survival, drive cell cycle progression and most importantly provide the needed energy to sustain these critical cellular activities. Though this review showcases much of what has been learned about IL-7 proliferative signaling, it also reveals the significant gaps in our knowledge about cytokine signaling in the very relevant context of peripheral T-cell homeostasis.     

Primer protein of bacteriophage M2 exposes the RGD receptor site upon linking the first deoxynucleotide

Summary Using electroporation with the phage PRD1 genome, we set up a high-frequency DNA transfer system for a linear dsDNA molecule with 5-covalently linked terminal proteins. The transfer was saturated when more than 100 ng of PRD1 genome was used. Electroporation efficiency was about four orders of magnitude higher than that obtained with transfection. Removal of the terminal protein abolished plaque formation, which could not be rescued by supplying the terminal protein or phage DNA polymerase or both in trans.