Predicted class-I aminoacyl tRNA synthetase-like proteins in non-ribosomal peptide synthesis

Background  

Recent studies point to a great diversity of non-ribosomal peptide synthesis systems with major roles in amino acid and co-factor biosynthesis, secondary metabolism, and post-translational modifications of proteins by peptide tags. The least studied of these systems are those utilizing tRNAs or aminoacyl-tRNA synthetases (AAtRS) in non-ribosomal peptide ligation.     

Use of autonomous audio recordings for the rapid inventory of birds in the white‐sand forests of the Peruvian Amazon

White‐sand forests are patchily distributed ecosystems covering just 5% of Amazonia that host many specialist species of birds not found elsewhere, and these forests are threatened due to their small size and human exploitation of sand for construction projects. As a result, many species of birds that are white‐sand specialists are at risk of extinction, and immediate conservation action is paramount for their survival. Our objective was to evaluate current survey methods and determine the relative effect of the size of patches of these forests on the presence or absence of white‐sand specialists. Using point counts and autonomous recorders, we surveyed avian assemblages occupying patches of white‐sand forest in the Peruvian Amazon in April 2018. Overall, we detected 126 species, including 21 white‐sand forest specialists. We detected significantly more species of birds per survey point with autonomous recorders than point counts. We also found a negative relationship between avian species richness and distance from the edge of patches of white‐sand forest, but a significant, positive relationship when only counting white‐sand specialists. Although we detected more species with autonomous recorders, point counts were more effective for detecting canopy‐dwelling passerines. Therefore, we recommend that investigators conducting surveys for rare and patchily distributed species in the tropics use a mixed‐method approach that incorporates both autonomous recorders and visual observation. Finally, our results suggest that conserving large, continuous patches of white‐sand forest may increase the likelihood of survival of species of birds that are white‐sand specialists.     

A process optimization for bio-catalytic production of substituted catechols (3-nitrocatechol and 3-methylcatechol

Background  

Substituted catechols are important precursors for large-scale synthesis of pharmaceuticals and other industrial products. Most of the reported chemical synthesis methods are expensive and insufficient at industrial level. However, biological processes for production of substituted catechols could be highly selective and suitable for industrial purposes.     

Winter food availability limits winter survival of Mongolian gerbils (<Emphasis Type="Italic">Meriones unguiculatus</Emphasis>)

Food availability is important to the dynamics of animal social organizations or populations. However, the role of winter food availability in animal population dynamics is still controversial. We carried out an experimental study to test Lack’s hypothesis that reduced food in winter limits survival and spring numbers of breeding individuals of social groups, using the Mongolian gerbil (Meriones unguiculatus) as model species. We established 24 gerbil social groups in 24, 10 × 10 m, pens in September 2008. We provided wheat seeds as supplemental food in 12 enclosures from September 2008 to March 2009; the other 12 enclosures, not provided with supplemental food, served as controls. We live-trapped gerbils at a 2-week interval from September to April. Supplemental food during winter increased biweekly survival by 10% relative to that in control groups. Only four control social groups survived to the end of our study whereas all 12 food-supplemented social groups survived through our study period. Supplemental food also increased cumulative numbers of recruits and group sizes of gerbils. We conclude that winter food availability limits winter survival and spring social groups or population sizes of Mongolian gerbils.     

Reply to Hussey et al.: The requirement for accurate diet-tissue discrimination factors for interpreting stable isotopes in sharks

Carbon and nitrogen stable isotope analyses have improved our understanding of food webs and movement patterns of aquatic organisms. These techniques have recently been applied to diet studies of elasmobranch fishes, but isotope turnover rates and isotope diet–tissue discrimination are still poorly understood for this group. We performed a diet switch experiment on captive sandbar sharks (Carcharhinus plumbeus) as a model shark species to determine tissue turnover rates for liver, whole blood, and white muscle. In a second experiment, we subjected captive coastal skates (Leucoraja spp.) to serial salinity reductions to measure possible impacts of tissue urea content on nitrogen stable isotope values. We extracted urea from spiny dogfish (Squalus acanthias) white muscle to test for effects on nitrogen stable isotopes. Isotope turnover was slow for shark tissues and similar to previously published estimates for stingrays and teleost fishes with low growth rates. Muscle isotope data would likely fail to capture seasonal migrations or diet switches in sharks, while liver and whole blood would more closely reflect shorter term movement or shifts in diet. Nitrogen stable isotope values of skate blood and skate and dogfish white muscle were not affected by tissue urea content, suggesting that available diet–tissue discrimination estimates for teleost fishes with similar physiologies would provide accurate estimates for elasmobranchs.     

Interferon inhibits DNA Synthesis induced in Mouse Lymphocyte Suspensions by Phytohaemagglutinin or by Allogeneic Cells

IN addition to its well known antiviral activity, interferon has recently been shown to inhibit the multiplication of tumour and mammalian cells in cell culture^1–6. We report here the inhibition by interferon of DNA synthesis induced in mouse spleen lymphocytes by the non-viral stimuli phytohaemagglutinin (PHA) and allogeneic lymphocytes. These findings are in accord with our contention that interferon affects cell function and, furthermore, they suggest that by acting on lymphocytes, interferon plays a role in the immunological response of the host.     

Untangling spider silk evolution with spidroin terminal domains

Background  

Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C)-terminal domains, though they offer limited character data. The few known spidroin amino (N)-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs) from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains.     

Brief Bursts Self-Inhibit and Correlate the Pyramidal Network

Inhibitory pathways are an essential component in the function of the neocortical microcircuitry. Despite the relatively small fraction of inhibitory neurons in the neocortex, these neurons are strongly activated due to their high connectivity rate and the intricate manner in which they interconnect with pyramidal cells (PCs). One prominent pathway is the frequency-dependent disynaptic inhibition (FDDI) formed between layer 5 PCs and mediated by Martinotti cells (MCs). Here, we show that simultaneous short bursts in four PCs are sufficient to exert FDDI in all neighboring PCs within the dimensions of a cortical column. This powerful inhibition is mediated by few interneurons, leading to strongly correlated membrane fluctuations and synchronous spiking between PCs simultaneously receiving FDDI. Somatic integration of such inhibition is independent and electrically isolated from monosynaptic excitation formed between the same PCs. FDDI is strongly shaped by I(h) in PC dendrites, which determines the effective integration time window for inhibitory and excitatory inputs. We propose a key disynaptic mechanism by which brief bursts generated by a few PCs can synchronize the activity in the pyramidal network.