GLM versus CCA spatial modeling of plant species distribution

Despite the variety of statistical methods available for static modeling of plant distribution, few studies directly compare methods on a common data set. In this paper, the predictive power of Generalized Linear Models (GLM) versus Canonical Correspondence Analysis (CCA) models of plant distribution in the Spring Mountains of Nevada, USA, are compared. Results show that GLM models give better predictions than CCA models because a species-specific subset of explanatory variables can be selected in GLM, while in CCA, all species are modeled using the same set of composite environmental variables (axes). Although both techniques can be readily ported to a Geographical Information System (GIS), CCA models are more readily implemented for many species at once. Predictions from both techniques rank the species models in the same order of quality; i.e. a species whose distribution is well modeled by GLM is also well modeled by CCA and vice-versa. In both cases, species for which model predictions have the poorest accuracy are either disturbance or fire related, or species for which too few observations were available to calibrate and evaluate the model. Each technique has its advantages and drawbacks. In general GLM will provide better species specific-models, but CCA will provide a broader overview of multiple species, diversity, and plant communities.     

High‐Throughput DNA sequencing of ancient wood

Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high‐throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long‐term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human‐induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro‐evolutionary response of trees to climate change and human forest management.     

Angiogenesis and diabetes: different responses to pro-angiogenic factors in the chorioallantoic membrane assay

Hyperglycemia induces defects in angiogenesis without alteration in the expression of major vascular growth factors in the chicken chorioallantoic membrane (CAM) model. A direct negative effect of hyperglycemia on angiogenesis may participate in failures of "therapeutic angiogenesis" trials. Here, we tested the hypothesis that the response to pro-angiogenic molecules such as angiotensin-converting enzyme (ACE), endothelin-1 (ET-1), and vascular endothelial growth factor-A (VEGF) is altered by hyperglycemia. Transfected (Chinese hamster ovary [CHO] or human embryonic kidney [HEK]) cells overexpressing ACE, ET-1, or VEGF were deposed onto the CAM of hyperglycemic or control embryos. The proangiogenic effect was evaluated 3 d later by angiography and histological analyses. Gene expression in response to these factors was assessed by in situ hybridization. Only VEGF overexpression evoked a proangiogenic response in the CAM from hyperglycemic embryos, upregulating the expression of endogenous VEGF, VEGF-R2, and Tie-2, all of them related to activation of endothelial cells. In conclusion, in a model where hyperglycemia does not alter the major vascular growth factor expression, the negative effect of diabetes on capillary density was overcome only by VEGF overexpression, whereas responses to other vasoactive peptides were practically abolished under hyperglycemic conditions.     

不产桔霉素的红曲霉菌种深层发酵生产莫纳可林K

对三株在YES培养基中不产桔霉素的红曲霉菌种,在摇瓶中研究了它们液体发酵生产莫纳可林K的情况。在大米粉培养基中,红色红曲霉不产莫纳可林K,但是紫色红曲霉和烟灰色红曲霉均能产莫纳可林K,前者产量高于后者。在葡萄糖．甘油培养基中,后两者的产量均很低,但是如果在该培养基中添加酵母膏,紫色红曲霉能产生较为可观的莫纳可林K。在2L的发酵罐中,利用添加了酵母膏的葡萄糖-甘油培养基,紫色红曲霉在第13d的莫纳可林K产量可达104mg/L,培养过程中无桔霉素产生。     

Design and validation of a homogeneous time-resolved fluorescence cell-based assay targeting the ligand-gated ion channel 5-HT3A

Ligand-gated ion channels (LGICs) are considered as attractive protein targets in the search for new therapeutic agents. Nowadays, this strategy involves the capability to screen large chemical libraries. We present a new Tag-lite ligand binding assay targeting LGICs on living cells. This technology combines the use of suicide enzyme tags fused to channels of interest with homogeneous time-resolved fluorescence (HTRF) as the detection readout. Using the 5-HT3 receptor as system model, we showed that the pharmacology of the HALO-5HT3 receptor was identical to that of the native receptor. After validation of the assay by using 5-HT3 agonists and antagonists of reference, a pilot screen enabled us to identify azelastine, a well-known histamine H1 antagonist, as a potent 5-HT3 antagonist. This interesting result was confirmed with electrophysiological experiments. The method described here is easy to implement and could be applicable for other LGICs, opening new ways for the screening of chemical libraries.     

Caspase-1 activation by Salmonella

Salmonella is an interesting example of how the selective pressure of host environments has led to the evolution of sophisticated bacterial virulence mechanisms. This microbe exploits the first-line of defence, the macrophage, as a crucial tool in the initiation of disease. After invasion of intestinal macrophages, a virulence protein secreted by Salmonella specifically induces apoptotic cell death by activating the cysteine protease caspase-1. The pro-apoptotic capability is necessary for successful pathogenesis. The study of mechanisms by which Salmonella induces programmed cell death offers new insights into how pathogens cause disease and into general mechanisms of activation of the innate immune system.     

Systematic review of Atractus schach (Serpentes: Dipsadidae) species complex from the Guiana Shield with description of three new species

The Guiana Shield harbours one of the best preserved and largest extents of tropical forest on Earth and an immense biodiversity. The herpetofauna of this region remains poorly known. The species-rich snake genus Atractus contains ～140 species, many with complicated taxonomic histories, including A. schach. Examination of specimens in museums and newly collected material from French Guiana has allowed the illustration of hemipenial morphology for the first time and an expanded diagnosis. Concatenated molecular phylogenetic (mitochondrial and nuclear genes) and phenotypic (morphometrics, external and hemipenial morphology) analyses confirm non-monophyly of the A. flammigerus group and indicate that A. schach is a species complex with three new species described here. The geographic distribution of A. schach sensu stricto is restricted to Guiana, Surinam, and French Guiana north of Tumucumaque massif. Populations tentatively assigned to A. schach from the east from French Guiana in the Roura lowlands to Almeirim, and from central Amazonia between the Negro and Trombetas rivers in Brazil are also recognized as new species. Our results suggest that populations from south of the Amazon River are not conspecific with those from the Guiana Shield.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:A7AE40BC-4716-4302-B3BE-1F43600B0A72