Isolation, characterization and lipid-binding properties of the recalcitrant FtsA division protein from Escherichia coli

We have obtained milligram amounts of highly pure Escherichia coli division protein FtsA from inclusion bodies with an optimized purification method that, by overcoming the reluctance of FtsA to be purified, surmounts a bottleneck for the analysis of the molecular basis of FtsA function. Purified FtsA is folded, mostly monomeric and interacts with lipids. The apparent affinity of FtsA binding to the inner membrane is ten-fold higher than to phospholipids, suggesting that inner membrane proteins could modulate FtsA-membrane interactions. Binding of FtsA to lipids and membranes is insensitive to ionic strength, indicating that a net contribution of hydrophobic interactions is involved in the association of FtsA to lipid/membrane structures.     

Modulation of the IgM gene expression and IgM immunoreactive cell distribution by the nutritional background in gilthead sea bream (Sparus aurata) challenged with Enteromyxum leei (Myxozoa)

The aim of the present work was to determine if a plant protein-based diet containing vegetable oils (VO) as the major lipid source could alter the distribution of IgM immunoreactive cells (IRCs) and the IgM expression pattern in the intestine and haematopoietic tissues of gilthead sea bream (GSB) (Sparus aurata) challenged with the myxosporean Enteromyxum leei. In a first trial (T1), GSB fed for 9 months either a fish oil (FO) diet or a blend of VO at 66% of replacement (66VO diet) was challenged by exposure to parasite-contaminated water effluent. All fish were periodically and non-lethally sampled to know their infection status. After 102 days of exposure, samples of intestine and head kidney were obtained for IgM expression and immunohistochemical detection (IHC). Additional samples of spleen were taken for IHC. Fish were categorized as control (C, not exposed), and early (E), or late (L) infected. The 66VO diet had no effect on the number of IgM-IRCs in any of the tissues or on IgM expression in C fish, whereas the infection with E.?leei had a strong effect on the intestine. A combined time-diet effect was also observed, since the highest expression and IRCs values were registered in the posterior intestine (Pi) of E-66VO fish. A positive correlation was found between IgM expression and the presence of IgM-IRCs in the Pi. The effect of the time of infection was studied more in detail in a second trial (T2) in which samples of Pi were taken at 0, 24, 51, 91 and 133 days after exposure to the parasite. A significant increase of the IgM expression was detected only in parasitized fish, and very late after exposure. These results show that the duration of the exposure to the parasite is the most determinant factor for the observed intestinal IgM increased phenotype which gets magnified by the feeding of a high VO-based diet.     

Sprouty2-mediated inhibition of fibroblast growth factor signaling is modulated by the protein kinase DYRK1A

Raf-MEK-extracellular signal-regulated kinase (Erk) signaling initiated by growth factor-engaged receptor tyrosine kinases (RTKs) is modulated by an intricate network of positive and negative feedback loops which determine the specificity and spatiotemporal characteristics of the intracellular signal. Well-known antagonists of RTK signaling are the Sprouty proteins. The activity of Sprouty proteins is modulated by phosphorylation. However, little is known about the kinases responsible for these posttranslational modifications. We identify DYRK1A as one of the protein kinases of Sprouty2. We show that DYRK1A interacts with and regulates the phosphorylation status of Sprouty2. Moreover, we identify Thr75 on Sprouty2 as a DYRK1A phosphorylation site in vitro and in vivo. This site is functional, since its mutation enhanced the repressive function of Sprouty2 on fibroblast growth factor (FGF)-induced Erk signaling. Further supporting the idea of a functional interaction, DYRK1A and Sprouty2 are present in protein complexes in mouse brain, where their expression overlaps in several structures. Moreover, both proteins copurify with the synaptic plasma membrane fraction of a crude synaptosomal preparation and colocalize in growth cones, pointing to a role in nerve terminals. Our results suggest, therefore, that DYRK1A positively regulates FGF-mitogen-activated protein kinase signaling by phosphorylation-dependent impairment of the inhibitory activity of Sprouty2.     

Integrating expert knowledge and ecological niche models to estimate Mexican primates’ distribution

Ecological niche modeling is used to estimate species distributions based on occurrence records and environmental variables, but it seldom includes explicit biotic or historical factors that are important in determining the distribution of species. Expert knowledge can provide additional valuable information regarding ecological or historical attributes of species, but the influence of integrating this information in the modeling process has been poorly explored. Here, we integrated expert knowledge in different stages of the niche modeling process to improve the representation of the actual geographic distributions of Mexican primates (Ateles geoffroyi, Alouatta pigra, and A. palliata mexicana). We designed an elicitation process to acquire information from experts and such information was integrated by an iterative process that consisted of reviews of input data by experts, production of ecological niche models (ENMs), and evaluation of model outputs to provide feedback. We built ENMs using the maximum entropy algorithm along with a dataset of occurrence records gathered from a public source and records provided by the experts. Models without expert knowledge were also built for comparison, and both models, with and without expert knowledge, were evaluated using four validation metrics that provide a measure of accuracy for presence-absence predictions (specificity, sensitivity, kappa, true skill statistic). Integrating expert knowledge to build ENMs produced better results for potential distributions than models without expert knowledge, but a much greater improvement in the transition from potential to realized geographic distributions by reducing overprediction, resulting in better representations of the actual geographic distributions of species. Furthermore, with the combination of niche models and expert knowledge we were able to identify an area of sympatry between A. palliata mexicana and A. pigra. We argue that the inclusion of expert knowledge at different stages in the construction of niche models in an explicit and systematic fashion is a recommended practice as it produces overall positive results for representing realized species distributions.     

Votive well or refuse tip? Chronicle of an abandonment: taphonomic study of the faunal remains of an iron age well-cistern

Abstract

The well-cistern of the Iberian Fortress of Vilars (Catalonia, Spain) is a monumental feature dating to the late fifth century BCE (Vilars, phases III-IV). Management of water resources is key to interpreting the nature of the fortress, as water was essential not only for human and livestock consumption, but for irrigation, construction, and crafts. Moreover, water was integral to the site in both times of peace and war, as the structures that guaranteed provision and management coincide with facets of military architecture (moat). Yet, why was the well-cistern backfilled with animal remains and other archaeological material only a few years after its construction? To answer this and other questions, this study follows two main lines of research. Firstly, analyses were carried out on the archaeozoological remains collected inside the feature so as to interpret and characterise the nature of the assemblage. Secondly, taphonomic analyses (macro- and microscopic) were undertaken so as to reconstruct the dynamics of accumulation and the premature abandonment of the well-cistern’s primary function: supplying potable water. The results suggest that the abandonment of the well-cistern might be due in part to a drop of the groundwater level during a period of drought.     

Biodiversity hotspots are not congruent with conservation areas in the Gulf of California

As marine systems are threatened by increasing human impacts, mechanisms to maintain biodiversity and ecosystem functions and services are needed. Protecting areas of conservation importance may serve as a proxy for maintaining these functions, while also facilitating efficient use and management of limited resources. Biodiversity hotspots have been used as surrogates for spatial conservation importance; however, as many protected areas have been established opportunistically and under differing criteria, it is unclear how well they actually protect hotspots. We evaluated how well the current protected area network and priority areas selected through previous systematic conservation planning exercises preserve biodiversity hotspots in the Gulf of California, Mexico. We also determined spatial congruence between biodiversity hotspots based on different criteria, which may determine their ability to be used as surrogates for each other. We focus on the Gulf of California because it is a megadiverse system where limited information regarding species diversity and distribution has constrained development of strategies for conservation and management. We developed a species occurrence database and identified biodiversity hotspots using four different criteria: species richness, rarity, endemism, and threatened species. We interpolated species occurrence, while accounting for heterogeneous sampling efforts. We then assessed overlap of hotspots with existing protected areas and priority areas, and between hotspots derived by distinct criteria. We gathered 286,533 occurrence records belonging to 12,105 unique species, including 6388 species identified as rare, 642 as endemic, and 386 as threatened. We found that biodiversity hotspots showed little spatial overlap with areas currently under protection and previously identified priority areas. Our results highlight the importance of distinct spatial areas of biodiversity and suggest that different ecological mechanisms sustain different aspects of diversity and multiple criteria should be used when defining conservation areas.