Modelling zinc changes at the hippocampal mossy fiber synaptic cleft

Zinc, a transition metal existing in very high concentrations in the hippocampal mossy fibers from CA3 area, is assumed to be co-released with glutamate and to have a neuromodulatory role at the corresponding synapses. The synaptic action of zinc is determined both by the spatiotemporal characteristics of the zinc release process and by the kinetics of zinc binding to sites located in the cleft area, as well as by their concentrations. This work addresses total, free and complexed zinc concentration changes, in an individual synaptic cleft, following single, short and long periods of evoked zinc release. The results estimate the magnitude and time course of the concentrations of zinc complexes, assuming that the dynamics of the release processes are similar to those of glutamate. It is also considered that, for the cleft zinc concentrations used in the model (≤ 1 μM), there is no postsynaptic zinc entry. For this reason, all released zinc ends up being reuptaken in a process that is several orders of magnitude slower than that of release and has thus a much smaller amplitude. The time derivative of the total zinc concentration in the cleft is represented by the difference between two alpha functions, corresponding to the released and uptaken components. These include specific parameters that were chosen assuming zinc and glutamate co-release, with similar time courses. The peak amplitudes of free zinc in the cleft were selected based on previously reported experimental cleft zinc concentration changes evoked by single and multiple stimulation protocols. The results suggest that following a low amount of zinc release, similar to that associated with one or a few stimuli, zinc clearance is mainly mediated by zinc binding to the high-affinity sites on the NMDA receptors and to the low-affinity sites on the highly abundant GLAST glutamate transporters. In the case of higher zinc release brought about by a larger group of stimuli, most zinc binding occurs essentially to the GLAST transporters, having the corresponding zinc complex a maximum concentration that is more than one order of magnitude larger than that for the high and low affinity NMDA sites. The other zinc complexes considered in the model, namely those formed with sites on the AMPA receptors, calcium and K_ATP channels and with ATP molecules, have much smaller contributions to the synaptic zinc clearance.     

Physico-chemical approach to adhesion of Alicyclobacillus cells and spores to model solid materials

Extremophiles - Acidothermophilic bacteria of the genus Alicyclobacillus are frequent contaminants of fruit-based products. This study is the first attempt to characterize the physico-chemical...     

New insights in the male anatomy,spermatophore formation,and sperm structure in Atyidae: The red cherry shrimp Neocaridina davidi

This study aims to analyze the functional anatomy of the male reproductive system in Neocaridina davidi, a very popular ornamental species of caridean shrimp. Mature males were cold‐anaesthetized and their reproductive systems were dissected for histological and histochemical analysis, while the spermatozoa and spermatophore wall ultrastructure were analyzed under transmission electron microscopy. The male reproductive system consisted of two coiled testes, which were continuous with the vasa deferentia. Testes were positioned on the dorsal side of the cephalothorax above the hepatopancreas, and comprised seminiferous tubules where spermatogenesis occurred. Each vas deferens (VD) was a long tube dorsolaterally positioned with respect to the hepatopancreas, and increased in diameter at the distal end. Three regions could be recognized in the VD: proximal, middle, and distal. The proximal region had a cylindrical epithelium with secretory cells. The middle region (or typhlosole) had a dorsal fold (or typhlosole) with a thick columnar epithelium and high secretory activity. The spermatophore was a continuous cord with three acellular layers, which were mainly characterized by the presence of neutral glycoconjugates and proteins. The sperm morphology was distinct from the inverted cup‐shaped spermatozoa observed in the majority of caridean shrimps. The spermatozoa in specimens of N. davidi were spherical in shape, with a cross‐striated, single, short spike, and arranged in clusters of three or four sperm cells. The composition of the spermatophore, and the arrangement and form of the spermatozoa, seem to be unique in comparison to other species of Caridea.     

Yellow perch genetic structure and habitat use among connected habitats in eastern Lake Michigan

Maintenance of genetic and phenotypic diversity is widely recognized as an important conservation priority, yet managers often lack basic information about spatial patterns of population structure and its relationship with habitat heterogeneity and species movement within it. To address this knowledge gap, we focused on the economically and ecologically prominent yellow perch (Perca flavescens). In the Lake Michigan basin, yellow perch reside in nearshore Lake Michigan, including drowned river mouths (DRMs)—protected, lake‐like habitats that link tributaries to Lake Michigan. The goal of this study was to examine the extent that population structure is associated with Great Lakes connected habitats (i.e., DRMs) in a mobile fish species using yellow perch as a model. Specifically, we tested whether DRMs and eastern Lake Michigan constitute distinct genetic stocks of yellow perch, and if so, whether those stocks migrate between the two connected habitats throughout the year. To do so, we genotyped yellow perch at 14 microsatellite loci collected from 10 DRMs in both deep and littoral habitats during spring, summer, and autumn and two nearshore sites in Lake Michigan (spring and autumn) during 2015–2016 and supplemented our sampling with fish collected in 2013. We found that yellow perch from littoral‐DRM habitats were genetically distinct from fish captured in nearshore Lake Michigan. Our data also suggested that Lake Michigan yellow perch likely use deep‐DRM habitats during autumn. Further, we found genetic structuring among DRMs. These patterns support hypotheses of fishery managers that yellow perch seasonally migrate to and from Lake Michigan, yet, interestingly, these fish do not appear to interbreed with littoral fish despite occupying the same DRM. We recommend that fisheries managers account for this complex population structure and movement when setting fishing regulations and assessing the effects of harvest in Lake Michigan.     

HDAC inhibition amplifies gap junction communication in neural progenitors: potential for cell-mediated enzyme prodrug therapy

Enzyme prodrug therapy using neural progenitor cells (NPCs) as delivery vehicles has been applied in animal models of gliomas and relies on gap junction communication (GJC) between delivery and target cells. This study investigated the effects of histone deacetylase (HDAC) inhibitors on GJC for the purpose of facilitating transfer of therapeutic molecules from recombinant NPCs. We studied a novel immortalized midbrain cell line, NGC-407 of embryonic human origin having neural precursor characteristics, as a potential delivery vehicle. The expression of gap junction protein connexin 43 (Cx43) was analyzed by western blot and immunocytochemistry. While Cx43 levels were decreased in untreated differentiating NGC-407 cells, the HDAC inhibitor 4-phenylbutyrate (4-PB) increased Cx43 expression along with increased membranous deposition in both proliferating and differentiating cells. Simultaneously, Ser 279/282-phosphorylated form of Cx43 was declined in both culture conditions by 4-PB. The 4-PB effect in NGC-407 cells was verified by using HNSC.100 human neural progenitors and Trichostatin A. Improved functional GJC is of imperative importance for therapeutic strategies involving intercellular transport of low molecular-weight compounds. We show here an enhancement by 4-PB, of the functional GJC among NGC-407 cells, as well as between NGC-407 and human glioma cells, as indicated by increased fluorescent dye transfer.     

Identification and characterization of DUSP27, a novel dual-specific protein phosphatase

A novel human dual-specific protein phosphatase (DSP), designated DUSP27, is here described. The DUSP27 gene contains three exons, rather than the predicted 4-14 exons, and encodes a 220 amino acid protein. DUSP27 is structurally similar to other small DSPs, like VHR and DUSP13. The location of DUSP27 on chromosome 10q22, 50 kb upstream of DUSP13, suggests that these two genes arose by gene duplication. DUSP27 is an active enzyme, and its kinetic parameters and were determined. DUSP27 is a cytosolic enzyme, expressed in skeletal muscle, liver and adipose tissue, suggesting its possible role in energy metabolism.