Localization of the nerve growth factor receptor on fetal human schwann cells in culture

Previous studies have established that Schwann cells (SC) in culture express an NGF receptor. In this study, cultures of fetal human SC were established from fetal nerves and various light microscopic (LM) and electron microscopic (EM) techniques were used to localize the NGF receptor on the SC. Results indicate that NGF receptor is localized to the plasma membrane of the SC. Quantitative digital analysis determined that the distal portion of the SC process had high concentrations of NGF receptor. The possible functional significance of this latter observation is discussed in terms of SC migration and ensheathment of axons.     

A molecular genetic linkage map of mouse chromosome 18 reveals extensive linkage conservation with human chromosomes 5 and 18

An interspecific backcross between C57BL/6J and Mus spretus was used to generate a molecular genetic linkage map of mouse chromosome 18 that includes 23 molecular markers and spans approximately 86% of the estimated length of the chromosome. The Apc, Camk2a, D18Fcr1, D18Fcr2, D18Leh1, D18Leh2, Dcc, Emb-rs3, Fgfa, Fim-2/Csfmr, Gnal, Grl-1, Grp, Hk-1rs1, Ii, Kns, Lmnb, Mbp, Mcc, Mtv-38, Palb, Pdgfrb, and Tpl-2 genes were mapped relative to each other in one interspecific backcross. A second interspecific backcross and a centromere-specific DNA satellite probe were used to determine the distance of the most proximal chromosome 18 marker to the centromere. The interspecific map extends the known regions of linkage homology between mouse chromosome 18 and human chromosomes 5 and 18 and identifies a new homology segment with human chromosome 10p. It also provides molecular access to many regions of mouse chromosome 18 for the first time.     

Selective incorporation of 5-hydroxytryptophan blocks long range electron transfer in oxalate decarboxylase

Oxalate decarboxylase from Bacillus subtilis is a binuclear Mn-dependent acid stress response enzyme that converts the mono-anion of oxalic acid into formate and carbon dioxide in a redox neutral unimolecular disproportionation reaction. A π-stacked tryptophan dimer, W96 and W274, at the interface between two monomer subunits facilitates long-range electron transfer between the two Mn ions and plays an important role in the catalytic mechanism. Substitution of W96 with the unnatural amino acid 5-hydroxytryptophan leads to a persistent EPR signal which can be traced back to the neutral radical of 5-hydroxytryptophan with its hydroxyl proton removed. 5-Hydroxytryptophan acts as a hole sink preventing the formation of Mn(III) at the N-terminal active site and strongly suppresses enzymatic activity. The lower boundary of the standard reduction potential for the active site Mn(II)/Mn(III) couple can therefore be estimated as 740 mV against the normal hydrogen electrode at pH 4, the pH of maximum catalytic efficiency. Our results support the catalytic importance of long-range electron transfer in oxalate decarboxylase while at the same time highlighting the utility of unnatural amino acid incorporation and specifically the use of 5-hydroxytryptophan as an energetic sink for hole hopping to probe electron transfer in redox proteins.     

A Nitrogen Pressure-Shearing Apparatus for Preparing Distinct Populations of Chromatin Fractions

A method for preparing reproducible chromatin fractions is described. Fragmentation is accomplished by expelling whole chromatin from an enclosed stainless-steel chamber through a restricted orifice utilizing low nitrogen pressure. Sheared chromatin is fractionated into two distinct heavy and light fractions by centrifugation on 5–20% linear sucrose gradient.     

Quinidine: an “Endangered Species” Drug Appropriate for Management of Electrical Storm in Brugada Syndrome

Brugada syndrome is an inherited channelopathy associated with an increased risk of syncope and sudden cardiac death. In rare cases it can be manifested with electrical storm. We report two cases of Brugada syndrome that presented with electrical storm and were treated successfully with oral quinidine, an "endangered species" drug.     

Where Have All the Rodents Gone? The Effects of Attrition in Experimental Research on Cancer and Stroke

Given small sample sizes, loss of animals in preclinical experiments can dramatically alter results. However, effects of attrition on distortion of results are unknown. We used a simulation study to analyze the effects of random and biased attrition. As expected, random loss of samples decreased statistical power, but biased removal, including that of outliers, dramatically increased probability of false positive results. Next, we performed a meta-analysis of animal reporting and attrition in stroke and cancer. Most papers did not adequately report attrition, and extrapolating from the results of the simulation data, we suggest that their effect sizes were likely overestimated.

Where have all the rodents gone?Ooh ooh, ooh ooh, oohTo non-random attrition, every oneWhen will they ever learn?—with apologies to Pete Seeger, 1955

     

Enterobacter sp. AA26 gut symbiont as a protein source for Mediterranean fruit fly mass-rearing and sterile insect technique applications

Background

The interaction between gut bacterial symbionts and Tephritidae became the focus of several studies that showed that bacteria contributed to the nutritional status and the reproductive potential of its fruit fly hosts. Anastrepha fraterculus is an economically important fruit pest in South America. This pest is currently controlled by insecticides, which prompt the development of environmentally friendly methods such as the sterile insect technique (SIT). For SIT to be effective, a deep understanding of the biology and sexual behavior of the target species is needed. Although many studies have contributed in this direction, little is known about the composition and role of A. fraterculus symbiotic bacteria. In this study we tested the hypothesis that gut bacteria contribute to nutritional status and reproductive success of A. fraterculus males.

Results

AB affected the bacterial community of the digestive tract of A. fraterculus, in particular bacteria belonging to the Enterobacteriaceae family, which was the dominant bacterial group in the control flies (i.e., non-treated with AB). AB negatively affected parameters directly related to the mating success of laboratory males and their nutritional status. AB also affected males’ survival under starvation conditions. The effect of AB on the behaviour and nutritional status of the males depended on two additional factors: the origin of the males and the presence of a proteinaceous source in the diet.

Conclusions

Our results suggest that A. fraterculus males gut contain symbiotic organisms that are able to exert a positive contribution on A. fraterculus males’ fitness, although the physiological mechanisms still need further studies.

     

The effects of geographic origin and antibiotic treatment on the gut symbiotic communities of Bactrocera oleae populations

The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is the major insect pest of olive orchards (Olea europaea L.), causing extensive damages on cultivated olive crops worldwide. Due to its economic importance, it has been the target species for a variety of population control approaches including the sterile insect technique (SIT). However, the inefficiency of the current mass‐rearing techniques impedes the successful application of area‐wide integrated pest management programs with an SIT component. It has been shown that insect mass rearing and quality of sterile insects can be improved by the manipulation of the insect gut microbiota and probiotic applications. In order to exploit the gut bacteria, it is important to investigate the structure of the gut microbial community. In the current study, we characterized the gut bacterial profile of two wild olive fruit fly populations introduced in laboratory conditions using next generation sequencing of two regions of the 16S rRNA gene. We compared the microbiota profiles regarding the geographic origin of the samples. Additionally, we investigated potential changes in the gut bacteria community before and after the first exposure of the wild adult flies to artificial adult diet with and without antibiotics. Various genera – such as Erwinia, Providencia, Enterobacter, and Klebsiella – were detected for the first time in B. oleae. The most dominant species was Candidatus Erwinia dacicola Capuzzo et al. and it was not affected by the antibiotics in the artificial adult diet used in the first generation of laboratory rearing. Geographic origin affected the overall structure of the gut community of the olive fruit fly, but antibiotic treatment in the first generation did not significantly alter the gut microbiota community.