Developing a series of conservative anchor markers and their application to phylogenomics of Laurasiatherian mammals

The availability of numerous universal markers and suitable phylogenetic analysis methods are both very important for phylogenomics inference. Based on PCR amplification, a total of 122 markers, which were amplified in 19 representative species, were developed for Laurasiatherian phylogenomics. Subsequently, we illustrated the utility of these newly developed markers using a subset of eight markers. We showed that both 'supermatrix' and 'supertree' trees generated similar topology, which accorded with the current understanding of the Laurasiatherian phylogeny in most aspects. Thus, markers developed here would be likely to make a contribution to resolving evolutionary relationships and inferring evolutionary histories of the Laurasiatherian mammals in the future.     

Modulation of synaptic plasticity by stress hormone associates with plastic alteration of synaptic NMDA receptor in the adult hippocampus

Stress exerts a profound impact on learning and memory, in part, through the actions of adrenal corticosterone (CORT) on synaptic plasticity, a cellular model of learning and memory. Increasing findings suggest that CORT exerts its impact on synaptic plasticity by altering the functional properties of glutamate receptors, which include changes in the motility and function of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid subtype of glutamate receptor (AMPAR) that are responsible for the expression of synaptic plasticity. Here we provide evidence that CORT could also regulate synaptic plasticity by modulating the function of synaptic N-methyl-D-aspartate receptors (NMDARs), which mediate the induction of synaptic plasticity. We found that stress level CORT applied to adult rat hippocampal slices potentiated evoked NMDAR-mediated synaptic responses within 30 min. Surprisingly, following this fast-onset change, we observed a slow-onset (>1 hour after termination of CORT exposure) increase in synaptic expression of GluN2A-containing NMDARs. To investigate the consequences of the distinct fast- and slow-onset modulation of NMDARs for synaptic plasticity, we examined the formation of long-term potentiation (LTP) and long-term depression (LTD) within relevant time windows. Paralleling the increased NMDAR function, both LTP and LTD were facilitated during CORT treatment. However, 1-2 hours after CORT treatment when synaptic expression of GluN2A-containing NMDARs is increased, bidirectional plasticity was no longer facilitated. Our findings reveal the remarkable plasticity of NMDARs in the adult hippocampus in response to CORT. CORT-mediated slow-onset increase in GluN2A in hippocampal synapses could be a homeostatic mechanism to normalize synaptic plasticity following fast-onset stress-induced facilitation.     

Mite allergen Der-p2 triggers human B lymphocyte activation and Toll-like receptor-4 induction

Background

Allergic disease can be characterized as manifestations of an exaggerated inflammatory response to environmental allergens triggers. Mite allergen Der-p2 is one of the major allergens of the house dust mite, which contributes to TLR4 expression and function in B cells in allergic patients. However, the precise mechanisms of Der-p2 on B cells remain obscure.

Methodology/Principal Findings

We investigated the effects of Der-p2 on proinflammatory cytokines responses and Toll-like receptor-4 (TLR4)-related signaling in human B cells activation. We demonstrated that Der-p2 activates pro-inflammatory cytokines, TLR4 and its co-receptor MD2. ERK inhibitor PD98059 significantly enhanced TLR4/MD2 expression in Der-p2-treated B cells. Der-p2 markedly activated mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) and decreased p38 phosphorylation in B cells. MKP-1-siRNA downregulated TLR4/MD2 expression in Der-p2-treated B cells. In addition, Der-p2 significantly up-regulated expression of co-stimulatory molecules and increased B cell proliferation. Neutralizing Der-p2 antibody could effectively abrogate the Der-p2-induced B cell proliferation. Der-p2 could also markedly induce NF-κB activation in B cells, which could be counteracted by dexamethasone.

Conclusions/Significance

These results strongly suggest that Der-p2 is capable of triggering B cell activation and MKP-1-activated p38/MAPK dephosphorylation-regulated TLR4 induction, which subsequently enhances host immune, defense responses and development of effective allergic disease therapeutics in B cells.     

Identification of genes directly involved in shell formation and their functions in pearl oyster, Pinctada fucata

Mollusk shell formation is a fascinating aspect of biomineralization research. Shell matrix proteins play crucial roles in the control of calcium carbonate crystallization during shell formation in the pearl oyster, Pinctada fucata. Characterization of biomineralization-related genes during larval development could enhance our understanding of shell formation. Genes involved in shell biomineralization were isolated by constructing three suppression subtractive hybridization (SSH) libraries that represented genes expressed at key points during larval shell formation. A total of 2,923 ESTs from these libraries were sequenced and gave 990 unigenes. Unigenes coding for secreted proteins and proteins with tandem-arranged repeat units were screened in the three SSH libraries. A set of sequences coding for genes involved in shell formation was obtained. RT-PCR and in situ hybridization assays were carried out on five genes to investigate their spatial expression in several tissues, especially the mantle tissue. They all showed a different expression pattern from known biomineralization-related genes. Inhibition of the five genes by RNA interference resulted in different defects of the nacreous layer, indicating that they all were involved in aragonite crystallization. Intriguingly, one gene (UD_Cluster94.seq.Singlet1) was restricted to the 'aragonitic line'. The current data has yielded for the first time, to our knowledge, a suite of biomineralization-related genes active during the developmental stages of P. fucata, five of which were responsible for nacreous layer formation. This provides a useful starting point for isolating new genes involved in shell formation. The effects of genes on the formation of the 'aragonitic line', and other areas of the nacreous layer, suggests a different control mechanism for aragonite crystallization initiation from that of mature aragonite growth.     

Confirmation and refinement of a genetic locus of congenital motor nystagmus in Xq26.3-q27.1 in a Chinese family

Congenital motor nystagmus (CMN), a subtype of nystagmus, may reduce vision or be associated with other, more serious, conditions that limit vision. The genetic basis for CMN is still unknown. To identify a locus for CMN, genotyping and linkage analysis were performed in 22 individuals from a Chinese family with X-linked CMN using markers from X chromosome. The maximum LOD score obtained for microsatellite maker DXS1192 linked the CMN locus in this family to Xq. By haplotype construction the locus for CMN was finally localized to an approximately 4.4-cM region at chromosome Xq26.3-q27.1. The SLC9A6 and FGF13 genes in this region, were selected and screened for mutation in this family, but no mutation was detected.B. Zhang and K. Xia contribute to this work equally     

Proton pumping inorganic pyrophosphatase of endoplasmic reticulum-enriched vesicles from etiolated mung bean seedlings

Endoplasmic reticulum (ER)-enriched vesicles from etiolated hypocotyls of mung bean seedlings (Vigna radiata) were successfully isolated using Ficoll gradient and two-phase (polyethylene glycol-dextran) partition. The ER-enriched vesicles contained inorganic pyrophosphate (PPi) hydrolysis and its associated proton translocating activities. Antiserum prepared against vacuolar H+-pyrophosphatase (V-PPase, EC 3.6.1.1) did not inhibit this novel pyrophosphatase-dependent proton translocation, excluding the possible contamination of tonoplast vesicles in the ER-enriched membrane preparation. The optimal ratios of Mg2+/PPi (inorganic pyrophosphate) for enzymatic activity and PPi-dependent proton translocation of ER-enriched vesicles were higher than those of vacuolar membranes. The PPi-dependent proton translocation of ER-enriched vesicles absolutely required the presence of monovalent cations with preference for K+, but could be inhibited by a common PPase inhibitor, F-. Furthermore, ER H+-pyrophosphatase exhibited some similarities and differences to vacuolar H+-PPases in cofactor/substrate ratios, pH profile, and concentration dependence of F-, imidodiphosphate (a PPi analogue), and various chemical modifiers. These results suggest that ER-enriched vesicles contain a novel type of proton-translocating PPase distinct from that of tonoplast from higher plants.