Repeated trans-watershed hybridization among haplochromine cichlids (Cichlidae) was triggered by Neogene landscape evolution

The megadiverse haplochromine cichlid radiations of the East African lakes, famous examples of explosive speciation and adaptive radiation, are according to recent studies, introgressed by different riverine lineages. This study is based on the first comprehensive mitochondrial and nuclear DNA dataset from extensive sampling of riverine haplochromine cichlids. It includes species from the lower River Congo and Angolan (River Kwanza) drainages. Reconstruction of phylogenetic hypotheses revealed the paradox of clearly discordant phylogenetic signals. Closely related mtDNA haplotypes are distributed thousands of kilometres apart and across major African watersheds, whereas some neighbouring species carry drastically divergent mtDNA haplotypes. At shallow and deep phylogenetic layers, strong signals of hybridization are attributed to the complex Late Miocene/Early Pliocene palaeohistory of African rivers. Hybridization of multiple lineages across changing watersheds shaped each of the major haplochromine radiations in lakes Tanganyika, Victoria, Malawi and the Kalahari Palaeolakes, as well as a miniature species flock in the Congo basin (River Fwa). On the basis of our results, introgression occurred not only on a spatially restricted scale, but massively over almost the whole range of the haplochromine distribution. This provides an alternative view on the origin and exceptional high diversity of this enigmatic vertebrate group.     

Seasonal Fluctuations of Bacterial Community Diversity in Agricultural Soil and Experimental Validation by Laboratory Disturbance Experiments

Natural fluctuations in soil microbial communities are poorly documented because of the inherent difficulty to perform a simultaneous analysis of the relative abundances of multiple populations over a long time period. Yet, it is important to understand the magnitudes of community composition variability as a function of natural influences (e.g., temperature, plant growth, or rainfall) because this forms the reference or baseline against which external disturbances (e.g., anthropogenic emissions) can be judged. Second, definition of baseline fluctuations in complex microbial communities may help to understand at which point the systems become unbalanced and cannot return to their original composition. In this paper, we examined the seasonal fluctuations in the bacterial community of an agricultural soil used for regular plant crop production by using terminal restriction fragment length polymorphism profiling (T-RFLP) of the amplified 16S ribosomal ribonucleic acid (rRNA) gene diversity. Cluster and statistical analysis of T-RFLP data showed that soil bacterial communities fluctuated very little during the seasons (similarity indices between 0.835 and 0.997) with insignificant variations in 16S rRNA gene richness and diversity indices. Despite overall insignificant fluctuations, between 8 and 30% of all terminal restriction fragments changed their relative intensity in a significant manner among consecutive time samples. To determine the magnitude of community variations induced by external factors, soil samples were subjected to either inoculation with a pure bacterial culture, addition of the herbicide mecoprop, or addition of nutrients. All treatments resulted in statistically measurable changes of T-RFLP profiles of the communities. Addition of nutrients or bacteria plus mecoprop resulted in bacteria composition, which did not return to the original profile within 14 days. We propose that at less than 70% similarity in T-RFLP, the bacterial communities risk to drift apart to inherently different states.     

Enhanced biodegradation of hexachlorocyclohexane (HCH) in contaminated soils via inoculation with Sphingobium indicum B90A

Soil pollution with hexachlorocyclohexane (HCH) has caused serious environmental problems. Here we describe the targeted degradation of all HCH isomers by applying the aerobic bacterium Sphingobium indicum B90A. In particular, we examined possibilities for large-scale cultivation of strain B90A, tested immobilization, storage and inoculation procedures, and determined the survival and HCH-degradation activity of inoculated cells in soil. Optimal growth of strain B90A was achieved in glucose-containing mineral medium and up to 65% culturability could be maintained after 60 days storage at 30°C by mixing cells with sterile dry corncob powder. B90A biomass produced in water supplemented with sugarcane molasses and immobilized on corncob powder retained 15–20% culturability after 30 days storage at 30°C, whereas full culturability was maintained when cells were stored frozen at −20°C. On the contrary, cells stored on corncob degraded γ-HCH faster than those that had been stored frozen, with between 15 and 85% of γ-HCH disappearance in microcosms within 20 h at 30°C. Soil microcosm tests at 25°C confirmed complete mineralization of [¹⁴C]-γ-HCH by corncob-immobilized strain B90A. Experiments conducted in small pits and at an HCH-contaminated agricultural site resulted in between 85 and 95% HCH degradation by strain B90A applied via corncob, depending on the type of HCH isomer and even at residual HCH concentrations. Up to 20% of the inoculated B90A cells survived under field conditions after 8 days and could be traced among other soil microorganisms by a combination of natural antibiotic resistance properties, unique pigmentation and PCR amplification of the linA genes. Neither the addition of corncob nor of corncob immobilized B90A did measurably change the microbial community structure as determined by T-RFLP analysis. Overall, these results indicate that on-site aerobic bioremediation of HCH exploiting the biodegradation activity of S. indicum B90A cells stored on corncob powder is a promising technology.     

Mannose-specific interaction of Lactobacillus plantarum with porcine jejunal epithelium

Host-microorganism interactions in the intestinal tract are complex, and little is known about specific nonpathogenic microbial factors triggering host responses in the gut. In this study, mannose-specific interactions of Lactobacillus plantarum 299v with jejunal epithelium were investigated using an in situ pig Small Intestinal Segment Perfusion model. The effects of L. plantarum 299v wild-type strain were compared with those of two corresponding mutant strains either lacking the gene encoding for the mannose-specific adhesin (msa) or sortase (srtA; responsible for anchoring of cell surface proteins like Msa to the cell wall). A slight enrichment of the wild-type strain associated with the intestinal surface could be observed after 8 h of perfusion when a mixture of wild-type and msa-mutant strain had been applied. In contrast to the mutant strains, the L. plantarum wild-type strain tended to induce a decrease in jejunal net fluid absorption compared with control conditions. Furthermore, after 8 h of perfusion expression of the host gene encoding pancreatitis-associated protein, a protein with proposed bactericidal properties, was found to be upregulated by the wild-type strain only. These observations suggest a role of Msa in the induction of host responses in the pig intestine.     

Male reproductive health statement (XIIIth international symposium on Spermatology,may 9th–12th 2018, Stockholm,Sweden

On the occasion of the XIIIth International Symposium on Spermatology held from 9 to 13 May 2018 in Stockholm (Sweden), participants (guest speakers and audience) collectively felt the need to make a public statement on the general issue of male reproductive health. Our intention is to raise awareness of what we believe is a neglected area of research despite alarming situations around the world. The disclosure strategy desired by the co-authors is to bring it to the attention of the greatest number partly by considering co-publication in the various periodicals dealing with Reproductive Biology and Andrology. BaCA’s editorial office accepted this mission and found it natural that our periodical, the official journal of the French Andrology Society (SALF), should carry this message.     

Inhibition of denitrification activity but not of mRNA induction in Paracoccus denitrificans by nitrite at a suboptimal pH

The influence of pH on the denitrification activity of a continuous culture of Paracoccus denitrificans was studied in relation to the presence of nitrite. After a transition from aerobic to anaerobic conditions at the suboptimal pH of 6.8, P. denitrificans was not able to build up a functional denitrification pathway. Nitrite accumulated in the medium as the predominant denitrification product. Although the nitrite reductase gene was induced properly, the enzyme could not be detected at sufficient amounts in the culture. These observations indicate that either translation was somehow inhibited, or once synthesized nitrite reductase was inactivated, possibly by the high concentrations of nitrous acid (HNO₂. Interestingly, when a P. denitrificans culture which was grown to steady-state under anaerobic conditions was then exposed to suboptimal pHs, cells exhibited a reduced overall denitrification activity, but neither nitrite nor any other denitrification intermediate accumulated.     

Circadian time-place learning in mice depends on Cry genes

Endogenous biological clocks allow organisms to anticipate daily environmental cycles. The ability to achieve time-place associations is key to the survival and reproductive success of animals. The ability to link the location of a stimulus (usually food) with time of day has been coined time-place learning, but its circadian nature was only shown in honeybees and birds. So far, an unambiguous circadian time-place-learning paradigm for mammals is lacking. We studied whether expression of the clock gene Cryptochrome (Cry), crucial for circadian timing, is a prerequisite for time-place learning. Time-place learning in mice was achieved by developing a novel paradigm in which food reward at specific times of day was counterbalanced by the penalty of receiving a mild footshock. Mice lacking the core clock genes Cry1 and Cry2 (Cry double knockout mice; Cry1(-/-)Cry2(-/-)) learned to avoid unpleasant sensory experiences (mild footshock) and could locate a food reward in a spatial learning task (place preference). These mice failed, however, to learn time-place associations. This specific learning and memory deficit shows that a Cry-gene dependent circadian timing system underlies the utilization of time of day information. These results reveal a new functional role of the mammalian circadian timing system.     

Photic sensitivity ranges of hamster pupillary and circadian phase responses do not overlap

Mammalian retinal photoreceptors form an irradiance detection system that drives many nonvisual responses to light such as pupil reflex and resetting of the circadian clock. To understand the role of pupil size in circadian light responses, pupil diameter was pharmacologically manipulated and the effect on behavioral phase shifts at different irradiance levels was studied in the Syrian hamster. Dose-response curves for steady-state pupil size and for behavioral phase shifts were constructed for 3 pupil conditions (dilated, constricted, and control). Retinal irradiance was calculated from corneal irradiance, pupil size, retinal surface area, and absorption of ocular media. The sensitivity of photic responses to retinal irradiance is approximately 1.5 log units higher than to corneal irradiance. When plotted against corneal irradiance, pharmacological pupil constriction reduces the light sensitivity of the circadian system, but pupil dilation has no effect. As expected, when plotted against retinal irradiance all dose-response curves superimposed, confirming that the circadian system responds to photon flux on the retina. Pupil dilation does not increase the circadian response to increasing irradiance, since the response of the circadian system attains saturation at irradiance levels lower than those required to induce pupil constriction. The main finding shows that due to the different response sensitivities, the effect of pupil constriction on the light sensitivity of the circadian system in the hamster under natural conditions is virtually negligible. We further suggest the existence of distinct modulating mechanisms for the differential retinal irradiance sensitivity of the pupil system and the circadian system, which enables the different responses to be tuned to their specific tasks while using similar photoreceptive input.     

Salmonella Induced IL-23 and IL-1β Allow for IL-12 Production by Monocytes and M?1 through Induction of IFN-γ in CD56+ NK/NK-Like T Cells

Background

The type-1 cytokine pathway plays a pivotal role in immunity against intracellular bacterial pathogens such as Salmonellae and Mycobacteria. Bacterial stimulation of pattern recognition receptors on monocytes, macrophages and dendritic cells initiates this pathway, and results in the production of cytokines that activate lymphocytes to produce interferon (IFN)-γ. Interleukin (IL)-12 and IL-23 are thought to be the key cytokines required for initiating a type-1 cytokine immune response to Mycobacteria and Salmonellae. The relative contribution of IL-23 and IL-12 to this process is uncertain.

Methodology/Principal Findings

We show that various TLR agonists induce the production of IL-23 but not IL-12 in freshly isolated human monocytes and cultured human macrophages. In addition, type 1 pro-inflammatory macrophages (Mϕ1) differentiated in the presence of GM-CSF and infected with live Salmonella produce IL-23, IL-1β and IL-18, but not IL-12. Supernatants of Salmonella-infected Mϕ1 contained more IL-18 and IL-1β as compared with supernatants of Mϕ1 stimulated with isolated TLR agonists, and induced IFN-γ production in human CD56⁺ cells in an IL-23 and IL-1β-dependent but IL-12-independent manner. In addition, IL-23 together with IL-18 or IL-1β led to the production of GM-CSF in CD56⁺ cells. Both IFN-γ and GM-CSF enhanced IL-23 production by monocytes in response to TLR agonists, as well as induced IL-12 production.

Conclusions/Significance

The findings implicate a positive feedback loop in which IL-23 can enhance its release via induction of IFN-γ and GM-CSF. The IL-23 induced cytokines allow for the subsequent production of IL-12 and amplify the IFN-γ production in the type-1 cytokine pathway.