Alternative reproductive tactics in male freshwater fish influence the accuracy of species recognition

Sexual conflict can result in coercive mating. Because males bear low costs of heterospecific mating, coercive males may engage in misdirected mating attempts toward heterospecific females. In contrast, sexual selection through consensual mate choice can cause mate recognition cues among species to diverge, leading to more accurate species recognition. Some species show both coercive mating and mate choice‐associated courtship behaviors as male alternative reproductive tactics. We hypothesized that if the selection pressures on each tactic differ, then the accuracy of species recognition would also change depending on the mating tactic adopted. We tested this hypothesis in the guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis) by a series of choice experiments. Poecilia reticulata and G. affinis males both showed imperfect species recognition and directed all components of mating behavior toward heterospecific females. They tended to direct courtship displays more frequently toward conspecific than heterospecific females. With male P. reticulata, however, accurate species recognition disappeared when they attempted coercive copulation: they directed coercions more frequently toward heterospecific females. We also found that heterospecific sexual interaction had little effect on the fecundity of gravid females, which suggests that prepregnancy interactions likely underpin the exclusion of G. affinis by P. reticulata in our region.     

Increased Oxidative Stress Impairs Adipose Tissue Function in Sphingomyelin Synthase 1 Null Mice

Sphingomyelin synthase 1 (SMS1) catalyzes the conversion of ceramide to sphingomyelin. Here, we found that SMS1 null mice showed lipodystrophic phenotype. Mutant mice showed up-regulation of plasma triglyceride concentrations accompanied by reduction of white adipose tissue (WAT) as they aged. Lipoprotein lipase (LPL) activity was severely reduced in mutant mice. In vivo analysis indicated that fatty acid uptake in WAT but not in liver decreased in SMS1 null compared to wild-type mice. In vitro analysis using cultured cell revealed that SMS1 depletion reduced fatty acid uptake. Proteins extracted from WAT of mutant mice were severely modified by oxidative stress, and up-regulation of mRNAs related to apoptosis, redox adjustment, mitochondrial stress response and mitochondrial biogenesis was observed. ATP content of WAT was reduced in SMS1 null mice. Blue native gel analysis indicated that accumulation of mitochondrial respiratory chain complexes was reduced. These results suggest that WAT of SMS1 null mice is severely damaged by oxidative stress and barely functional. Indeed, mutant mice treated with the anti-oxidant N-acetyl cysteine (NAC) showed partial recovery of lipodystrophic phenotypes together with normalized plasma triglyceride concentrations. Altogether, our data suggest that SMS1 is crucial to control oxidative stress in order to maintain WAT function.     

Determination of Anomeric Configuration of Furanoside Derivatives by Carbon-13 NMR

A 24 kDa protein was isolated from tartary buckwheat seeds by using chromatography of Superdex 75 gel filtration and Resource Q ion-exchange column. SDS-PAGE and Sephacryl S-200 gel filtration were used to provide information about the molecular mass of the protein purified from tartary buckwheat. The protein was composed of 215 amino acid residues and showed strong IgE binding activity in an ELISA test to the sera colleted from two patients allergic to buckwheat. These results suggested that the purified 24 kDa protein from tartary buckwheat seeds was an important functional protein and was relatively specific for buckwheat-allergic patients. It should be a very useful tool in the diagnosis of buckwheat allergy in the future.     

A rapid detection method using flow cytometry to monitor the risk of Legionella in bath water

Legionella species are the causative agents of human legionellosis, and bathing facilities have been identified as the sources of infection in several outbreaks in Japan. Researchers in Japan have recently reported evidence of significant associations between bacterial counts and the occurrence of Legionella in bathing facilities and in a hot tub model. A convenient and quantitative bacterial enumeration method is therefore required as an indicator of Legionella contamination or disinfection to replace existing methods such as time-consuming Legionella culture and expensive Legionella-DNA amplification. In this study, we developed a rapid detection method (RDM) to monitor the risk of Legionella using an automated microbial analyzing device based on flow cytometry techniques to measure the total number of bacteria in water samples within two minutes, by detecting typical patterns of scattered light and fluorescence. We first compared the results of our RDM with plate counting results for five filtered hot spring water samples spiked with three species of bacteria, including Legionella. Inactivation of these samples by chlorine was also assessed by the RDM, a live/dead bacterial fluorescence assay and plate counting. Using the RDM, the lower limit of quantitative bacterial counts in the spiked samples was determined as 3.0 × 10³ (3.48 log) counts mL^− 1. We then used a laboratory model of a hot tub and found that the RDM could monitor the growth curve of naturally occurring heterotrophic bacteria with 1 and 2 days' delayed growth of amoeba and Legionella, respectively, and could also determine the killing curve of these bacteria by chlorination. Finally, samples with ≥ 3.48 or < 3.48 log total bacterial counts mL^− 1 were tested using the RDM from 149 different hot tubs, and were found to be significantly associated with the positive or negative detection of Legionella with 95% sensitivity and 84% specificity. These findings indicated that the RDM can be used for Legionella control at bathing facilities, especially those where the effectiveness of chlorine is reduced by the presence of Fe²⁺, Mn²⁺, NH₄⁺, skin debris, and/or biofilms in the water.     

Loss of a GPI-anchored membrane protein Aah3p causes a defect in vacuolar protein sorting in Schizosaccharomyces pombe

Schizosaccharomyces pombe has four alpha-amylase homologs (Aah1p-Aah4p) with a glycosylphosphatidylinositol (GPI) modification site at the C-terminal end. Disruption mutants of aah genes were tested for mislocalization of vacuolar carboxypeptidase Y (CPY), and aah3Delta was found to secrete CPY. The conversion rate from pro- to mature CPY was greatly impaired in aah3Delta, and fluorescence microscopy inidicated that a sorting receptor for CPY, Vps10p, mislocalized to the vacuolar membrane. These results indicate that aah3Delta had a defect in the retrograde transport of Vps10p, and that Aah3p is the first S. pombe specific protein required for vacuolar protein sorting.     

Shati/Nat8l Overexpression Improves Cognitive Decline by Upregulating Neuronal Trophic Factor in Alzheimer’s Disease Model Mice

Neurochemical Research - Alzheimer’s disease (AD) is a type of dementia characterized by the deposition of amyloid β, a causative protein of AD, in the brain. Shati/Nat8l, identified as...     

Arm-specific telomere dynamics of each individual chromosome in induced pluripotent stem cells revealed by quantitative fluorescence in situ hybridization

We have reported that telomere fluorescence units (TFUs) of established induced pluripotent stem cells (iPSCs) derived from human amnion (hAM933) and fetal lung fibroblasts (MRC-5) were significantly longer than those of the parental cells, and that the telomere extension rates varied quite significantly among clones without chromosomal instability, although the telomeres of other iPSCs derived from MRC-5 became shorter as the number of passages increased along with chromosomal abnormalities from an early stage. In the present study we attempted to clarify telomere dynamics in each individual chromosomal arm of parental cells and their derived clonal human iPSCs at different numbers of passages using quantitative fluorescence in situ hybridization (Q-FISH). Although no speci?c arm of any particular chromosome appeared to be consistently shorter or longer than most of the other chromosomes in any of the cell strains, telomere elongation in each chromosome of an iPSC appeared to be random and stochastic. However, in terms of the whole genome of any specific cell, the telomeres showed overall elongation associated with iPSC generation. We have thus demonstrated the specific telomere dynamics of each individual chromosomal arm in iPSCs derived from parental cells, and in the parental cells themselves, using Q-FISH.