Distribution,biology and hybridization of Scaphirhynchus albus and S. platorynchus in the Missouri and Mississippi rivers

Synopsis Scaphirhynchus albus and S. platorynchus were studied in Missouri during 1978–1979 to assess their distribution and abundance, to obtain information on their life histories, and to identify existing or potential threats to their survival. S. platorynchus was collected in substantial numbers (4355 specimens) at all 12 sampling stations in the Missouri and Mississippi rivers, while only 11 S. albus were captured from 6 stations. Twelve specimens identified in the field as hybrids between the two species were captured from 4 stations. Morphometric and meristic comparisons of presumed hybrids with the parent species, using cluster and principal components analyses, demonstrated intermediacy of most specimens identified in the field as hybrids. Aquatic insects comprised most of the diet of S. platorynchus and S. albus, but S. albus and the hybrids had consumed considerable quantities of fish. S. albus grew more rapidly than S. platorynchus, while the growth of hybrids was intermediate. Hybridization appears to be a recent phenomenon, resulting from man-caused changes in the big-river environment. Hybridization may be a threat to survival of S. albus in the study streams.     

Dissection of DNA Damage Responses Using Multiconditional Genetic Interaction Maps

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Highlights? A resource of genetic modules and networks induced by distinct types of DNA damage ? Networks distinguish DNA damage response pathways with high statistical power ? Rtt109, a histone acetyltransferase, affects the mutagenic bypass of DNA lesions ? The neddylation machinery and Irc21 affect cell-cycle control and genome stability     

The relative effects of local management and landscape context on weed seed predation and carabid functional groups

Farmland biodiversity and its associated ecosystem services are affected by agricultural activities at multiple spatial scales. Among these services, the regulation of weeds by invertebrate seed predators has received much attention recently but little is known about the relative effect of local management and landscape context of fields on this process. We monitored seed predation on four common weed species and carabid communities in 28 winter-cereals fields during five consecutive weeks in spring 2010. These fields were situated in contrasted landscape contexts and varied in terms of intensity of pesticide treatments and soil tillage regimes. Weed seed predation was strongly and positively related to the Shannon diversity of (strictly) granivorous carabids and to the activity–density of omnivorous carabids but negatively to the richness of omnivorous carabids. Weed seed predation and granivore diversity were positively related to landscape diversity and the proportion cover of temporary grassland within a 1000 m radius around focal fields and were negatively affected by the intensity of local pesticide treatments. No-till systems sheltered higher diversity of granivorous carabids but did not show higher seed predation rates. We showed that landscape composition factors had a higher relative influence than local practices factors on weed seed predation service. Consequently, weed management strategies should not only consider the management of single fields but also the surrounding landscape to preserve carabid biodiversity and enhance weed seed predation service.     

Biotic and Abiotic Soil Properties Influence Survival of Listeria monocytogenes in Soil

Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monitoring Network. This soil collection is meant to be representative of the pedology and land use of the whole French territory. The population of L. monocytogenes in inoculated microcosms was enumerated by plate count after 7, 14 and 84 days of incubation. Analysis of survival profiles showed that L. monocytogenes was able to survive up to 84 days in 71% of the soils tested, in the other soils (29%) only a short-term survival (up to 7 to 14 days) was observed. Using variance partitioning techniques, we showed that about 65% of the short-term survival ratio of L. monocytogenes in soils was explained by the soil chemical properties, amongst which the basic cation saturation ratio seems to be the main driver. On the other hand, while explaining a lower amount of survival ratio variance (11%), soil texture and especially clay content was the main driver of long-term survival of L. monocytogenes in soils. In order to assess the effect of the endogenous soils microbiota on L. monocytogenes survival, sterilized versus non-sterilized soils microcosms were compared in a subset of 9 soils. We found that the endogenous soil microbiota could limit L. monocytogenes survival especially when soil pH was greater than 7, whereas in acidic soils, survival ratios in sterilized and unsterilized microcosms were not statistically different. These results point out the critical role played by both the endogenous microbiota and the soil physic-chemical properties in determining the survival of L. monocytogenes in soils.     

Chemical preservation of tail feathers from Anchiornis huxleyi,a theropod dinosaur from the Tiaojishan Formation (Upper Jurassic,China)

A panel of geochemical techniques is used here to investigate the taphonomy of fossil feathers preserved in association with the skeleton of the Jurassic theropod Anchiornis huxleyi. Extant feathers were analysed in parallel to test whether the soft tissues morphologically preserved in the fossil also exhibit a high degree of chemical preservation. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicate that clays and iron oxide pseudomorphs occur in the surrounding sediment and also reveal the preservation of melanosome-like microbodies in the fossil. Carbon gradient along a depth profile and co-occurrence of carbon and sulphur are shown in the fossil by elastic backscattering (EBS) and particle-induced x-ray emission (PIXE), which are promising techniques for the elemental analysis of fossil soft tissues. The molecular composition of modern and fossil soft tissues was assessed from micro-attenuated total reflectance fourier transform infrared spectroscopy (micro-ATR FTIR), solid-state ¹³C nuclear magnetic resonance (CP-MAS ¹³C NMR) and pyrolysis gas chromatography mass spectrometry in the presence of TMAH (TMAH-Py-GC-MS). Results indicate that the proteinaceous material that comprises the modern feathers is not present in the fossil feathers. The fossil feathers and the embedding sediment exhibit a highly aliphatic character. However, substantial differences exist between these samples, revealing that the organic matter of the fossil feathers is, at least partially, derived from original constituents of the feathers. Our results suggest that, despite the morphological preservation of Anchiornis feathers, original proteins, that is keratin, were probably not preserved in the 160-myr-old feathers.     

Heating and microwave assisted SPPS of C-terminal acid peptides on trityl resin: the truth behind the yield

Despite correct purity of crude peptides prepared on trityl resin by Fmoc/tBu microwave assisted solid phase peptide synthesis, surprisingly, lower yields than those expected were obtained while preparing C-terminal acid peptides. This could be explained by cyclization/cleavage through diketopiperazine formation during the second amino acid deprotection and third amino acid coupling. However, we provide here evidence that this is not the case and that this yield loss was due to high temperature promoted hydrolysis of the 2-chlorotrityl ester, yielding premature cleavage of the C-terminal acid peptides.     

Haemosporidian Parasites of Antelopes and Other Vertebrates from Gabon,Central Africa

Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i.e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes.