Telomere dynamics in parasitic great spotted cuckoos and their magpie hosts

Although little is known on the impact of environment on telomere length dynamics, it has been suggested to be affected by stress, lifestyle and/or life‐history strategies of animals. We here compared telomere dynamics in erythrocytes of hatchlings and fledglings of the brood parasite great spotted cuckoos (Clamator glandarius) and of magpies (Pica pica), their main host in Europe. In magpie chicks, telomere length decreased from hatching to fledging, whereas no significant change in telomere length of great spotted cuckoo chicks was found. Moreover, we found interspecific differences in the association between laying date and telomere shortening. Interspecific differences in telomere shortening were interpreted as a consequence of differences in lifestyle and life‐history characteristics of magpies and great spotted cuckoos. In comparison with magpies, cuckoos experience reduced sibling competition and higher access to resources and, consequently, lower stressful environmental conditions during the nestling phase. These characteristics also explain the associations between telomere attrition and environmental conditions (i.e. laying date) for magpies and the absence of association for great spotted cuckoos. These results therefore fit expectations on telomere dynamics derived from interspecific differences in lifestyle and life history of brood parasites and their bird hosts.     

Migratory divides and their consequences for dispersal, population size and parasite-host interactions

Populations of migratory birds differ in their direction of migration with neighbouring populations often migrating in divergent directions separated by migratory divides. A total of 26% of 103 passerine bird species in Europe had migratory divides that were located disproportionately often along a longitudinal gradient in Central Europe, consistent with the assumption of a Quaternary glacial origin of such divides in the Iberian and Balkan peninsulas followed by recolonization. Given that studies have shown significant genetic differentiation and reduced gene flow across migratory divides, we hypothesized that an absence of migratory divides would result in elevated rates of gene flow and hence a reduced level of local adaptation. In a comparative study, species with migratory divides had larger population sizes and population densities and longer dispersal distances than species without migratory divides. Species with migratory divides tended to be habitat generalists. Bird species with migratory divides had higher richness of blood parasites and higher growth rates of Staphylococcus on their eggs during the incubation period. There was weaker cell-mediated immunity in adults and stronger cell lysis in species with migratory divides. These findings may suggest that migratory divides constitute barriers to dispersal with consequences for ecology and evolution of distributions, population sizes, habitats and parasite-host interactions. They also suggest that migratory divides may play a role in local adaptation in host-parasite interactions.     

Effect of the degree of cross-linking on the properties of different CLEAs of penicillin acylase

Cross-linked enzyme aggregates (CLEAs) are novel type biocatalysts well suited to catalyze reactions of organic synthesis. Penicillin acylase is a versatile enzyme that can both hydrolyze and synthesize β-lactam antibiotics. CLEAs and CLEAs covered with polyionic polymers (polyethyleneimine and dextran sulfate at two different enzyme to polymer ratios) were prepared at varying cross-linking agent to enzyme ratio: 0.15 and 0.25. Results are presented on the effect of such variables on immobilization yield, specific activity, stability and performance of penicillin acylase CLEAs in the kinetically controlled synthesis of cephalexin. The cross-linking agent to enzyme ratio had no significant effect on the specific activity of the CLEAs, but affected immobilization yield, stability in ethylene glycol medium and conversion yield and productivity in the synthesis of cephalexin, being always higher at the lower cross-linking agent to enzyme ratio. Best results were obtained with CLEAs at 0.15 glutaraldehyde to enzyme protein ratio: specific activity of hydrolysis and synthesis was 708 and 325 UI/g_CLEA respectively, conversion yield was 87%, specific productivity was 5.4 mmol cephalexin/(g_CLEA·h) and 90% of the enzyme remained active after 170 h at operating conditions.     

Characteristics of Iberian red deer (Cervus elaphus hispanicus) spermatozoa cryopreserved after storage at 5 degrees C in the epididymis for several days

The aim of this study was to assess the influence of prolonged cold storage of Iberian red deer epididymides on post-thaw sperm characteristics. Thirty-seven pairs of testes, with attached epididymides, were collected during November and December. Spermatozoa from one of each of the pairs were immediately recovered, evaluated and frozen (control group). The remaining epididymides were cooled to 5 degrees C and stored for 12, 24, 48, 72 and 96 h (experimental groups), after which spermatozoa were collected and frozen as in the control group. After thawing, sperm motility, membrane and acrosome integrities, mitochondrial function and DNA damage were evaluated. The motility of spermatozoa stored in the epididymis for up to 96 h did not decrease significantly (P>0.05) but, after cryopreservation, a decline in sperm motility was seen in spermatozoa stored for 48 h, or later. A slower decrease in sperm membrane and acrosome integrities after cryopreservation were seen as storage time progressed. Some differences were seen when different methods were used to assess the same sperm parameter although changes followed similar patterns. This was the case for acrosome integrity (phase contrast microscopy versus fluorescent lectin) or membrane integrity (hypo-osmotic swelling test or nigrosin-eosin stain versus propidium iodide). We conclude that frozen-thawed spermatozoa of Iberian red deer recovered from epididymides stored at 5 degrees C have a good sperm quality (including motility) during less than 48 h of storage for most of the sperm parameters assessed.     

Male fertility in natural populations of red deer is determined by sperm velocity and the proportion of normal spermatozoa

Male reproductive success is determined by the ability of males to gain sexual access to females and by their ability to fertilize ova. Among polygynous mammals, males differ markedly in their reproductive success, and a great deal of effort has been made to understand how selective forces have shaped traits that enhance male competitiveness both before and after copulation (i.e., sperm competition). However, the possibility that males also may differ in their fertility has been ignored under the assumption that male infertility is rare in natural populations because selection against it is likely to be strong. In the present study, we examined which semen traits correlate with male fertility in natural populations of Iberian red deer (Cervus elaphus hispanicus). We found no trade-offs between semen traits. Our analyses revealed strong associations between sperm production and sperm swimming velocity, sperm motility and proportion of morphologically normal spermatozoa, and sperm viability and acrosome integrity. These last two variables had the lowest coefficients of variation, suggesting that these traits have stabilized at high values and are unlikely to be related to fitness. In a fertility trial, our results show a large degree of variation in male fertility, and differences in fertility were determined mainly by sperm swimming velocity and by the proportion of morphologically normal sperm. We conclude that male fertility varies substantially in natural populations of Iberian red deer and that, when sperm numbers are equal, it is determined mainly by sperm swimming velocity and sperm morphology.     

IL-10-conditioned dendritic cells, decommissioned for recruitment of adaptive immunity, elicit innate inflammatory gene products in response to danger signals

Dendritic cells (DCs) are the professional APCs of the immune system, enabling T cells to perceive and respond appropriately to potentially dangerous microbes, while also being able to maintain T cell tolerance toward self. In part, such tolerance can be determined by IL-10 released from certain types of regulatory T cells. IL-10 has previously been shown to render DCs unable to activate T cells and it has been assumed that this process represents a general block in maturation. Using serial analysis of gene expression, we show that IL-10 pretreatment of murine bone marrow-derived DCs alone causes significant changes in gene expression. Furthermore, these cells retain the ability to respond to Toll-like receptor agonists, but in a manner skewed toward the selective induction of mediators known to enhance local inflammation and innate immunity, among which we highlight a novel CXCR2 ligand, DC inflammatory protein-1. These data suggest that, while the presence of a protolerogenic and purportedly anti-inflammatory agent such as IL-10 precludes DCs from acquiring their potential as initiators of adaptive immunity, their ability to act as initiators of innate immunity in response to Toll-like receptor signaling is enhanced.