Limnonectins: a new class of antimicrobial peptides from the skin secretion of the Fujian large-headed frog (Limnonectes fujianensis)

Amphibian skin secretions are rich sources of biologically-active peptides with antimicrobial peptides predominating in many species. Several studies involving molecular cloning of biosynthetic precursor-encoding cDNAs from skin or skin secretions have revealed that these exhibit highly-conserved domain architectures with an unusually high degree of conserved nucleotide and resultant amino acid sequences within the signal peptides. This high degree of nucleotide sequence conservation has permitted the design of primers complementary to such sites facilitating “shotgun” cloning of skin or skin secretion-derived cDNA libraries from hitherto unstudied species. Here we have used such an approach using a skin secretion-derived cDNA library from an unstudied species of Chinese frog - the Fujian large-headed frog, Limnonectes fujianensis - and have discovered two 16-mer peptides of novel primary structures, named limnonectin-1Fa (SFPFFPPGICKRLKRC) and limnonectin-1Fb (SFHVFPPWMCKSLKKC), that represent the prototypes of a new class of amphibian skin antimicrobial peptide. Unusually these limnonectins display activity only against a Gram-negative bacterium (MICs of 35 and 70 μM) and are devoid of haemolytic activity at concentrations up to 160 μM. Thus the “shotgun” cloning approach described can exploit the unusually high degree of nucleotide conservation in signal peptide-encoding domains of amphibian defensive skin secretion peptide precursor-encoding cDNAs to rapidly expedite the discovery of novel and functional defensive peptides in a manner that circumvents specimen sacrifice without compromising robustness of data.     

Dynamic Host Immune and Transcriptomic Responses to Respiratory Syncytial Virus Infection in a Vaccination-Challenge Mouse Model

Virologica Sinica - Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in children. Inactivated RSV vaccine was developed in the late 1960’s, but the...     

The nuclear localization of SET mediated by impalpha3/impbeta attenuates its cytosolic toxicity in neurons

SET is a multi-functional protein in proliferating cells. Some of the proposed functions of SET suggest an important nuclear role. However, the nuclear import pathway of SET is also unknown and the function of SET in neurons is unclear. Presently, using cortical neurons, we report that the nuclear import of SET is mediated by an impalpha/impbeta-dependent pathway. Nuclear localization signal, (168)KRSSQTQNKASRKR(181), in SET interacts with impalpha3, which recruits impbeta to form a ternary complex, resulting in efficient transportation of SET into nucleus. By in vitro nuclear import assay based on digitonin-permeabilized neurons, we further demonstrated that the nuclear import of SET relies on Ran GTPase. We provide evidence that this nuclear localization of SET is important in neuronal survival. Under basal conditions, SET is predominately nuclear. However, upon death induced by genotoxic stress, endogenous SET decreases in the nucleus and increases in the cytoplasm. Consistent with a toxic role of SET in the cytoplasm, targeted expression of SET to the cytoplasm exacerbates death compared to wild type SET expression which is protective following DNA damage. Taken together, our results indicate that SET is imported into the nucleus through its association with impalpha3/impbeta, and that localization of SET is important in regulation of neuronal death.     

The Contractile Proteins and Calcium Mediated Gelation and Contraction of Pollen Tube Extracts

The crude extracts of pollen tubes, like other nonmuscle ceils, showed gelation at Iow Ga2+ concentrations and ATP-dependent contraction at higher Ga2+ concentrations. The contracted cytoplasmic clots contained a lot of filaments which were mainly composed of actin, myosin, 105 kD, 67 kD, 48 kD, 38 kD, 34 kD and 28 kD proteins. It is likely that Ca2+ are able to mediate tranformation of acfin from a less ordered state to a more oriented filaments, which interact with actin-binding proteins to form the filamentous network, thus to induce the gel formation of cytoplasm, to regulate the interaction of actin and myosin which transform the chemical energy of ATP into mechanical work of contractile movement of cytoplasm.     

Structural determinants of benzodiazepinedione/peptide-based p53-HDM2 inhibitors using 3D-QSAR, docking and molecular dynamics

As a tumor suppressor, p53 protein regulates the cell cycle and is involved in preventing tumorgenesis. The protein level of p53 is under the tight control of its negative regulator human double minute 2 (HDM₂) via ubiquitination. Therefore, the design of inhibitors of HDM₂ has attracted much interest of research on developing novel anticancer drugs. Presently, two classes of molecules, i.e., the 1,4-benzodiazepine-2,5-diones (BDPs) and N-Acylpolyamine (NAPA) derivatives were studied by three-dimensional quantitative structure–activity relationship (3D-QSAR) modeling approaches including the comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) as promising p53-HDM₂ inhibitors. Based on both the ligand-based and receptor-guided (docking) alignments, two optimal 3D-QSAR models were obtained with good predictive power of q ² = 0.41, r ² _pred = 0.60 for BDPs, and q ² = 0.414, r ² _pred = 0.69 for NAPA analogs, respectively. By analysis of the model and its related contour maps, it is revealed that the electrostatic interactions contributed much larger to the compound binding affinity than the steric effects. And the contour maps intuitively suggested where to modify the molecular structures in order to improve the binding affinity. In addition, molecular dynamics simulation (MD) study was also carried out on the dataset with purpose of exploring the detailed binding modes of ligand in the HDM₂ binding pocket. Based on the CoMFA contour maps and MD-based docking analyses, some key structural aspects responsible for inhibitory activity of these two classes of compounds were concluded as follows: For BDPs, the R₁ and R₃ regions should have small electronegativity groups; substituents R₂ and R₄ should be larger, and R₃ substituent mainly involves in H-bonds forming. For NAPA derivatives, bulky and electropositive groups in ring B and ring A, small substituent at region P is favorable for the inhibitory activity. The models and related information, we hope, may provide important insight into the inhibitor-p53-HDM₂ interactions and be helpful for facilitating the design of novel potent inhibitors.     

ETS1 variants confer susceptibility to ankylosing spondylitis in Han Chinese

Introduction

ETS1 is a negative regulator of the Th17 differentiation gene and plays a central role in the pathogenesis of autoimmune diseases. We aimed to investigate whether polymorphisms in ETS1 confer susceptibility to ankylosing spondylitis (AS) in Han Chinese.

Methods

We selected seven single nucleotide polymorphisms (SNPs) within ETS1 based on HapMap data and previous genome-wide association study. Genotyping involved the TaqMan method in 1,015 patients with AS and 1,132 healthy controls from Shandong Province, and 352 AS patients and 400 healthy controls from Ningxia, a northwest region in China. Gene expression was determined by real-time PCR.

Results

The SNP rs1128334 was strongly associated with AS (odds ratio 1.204, 95% confidence interval 1.06-1.37; P = 0.005). This association was confiexrmed in the Ningxia population (P = 0.015). Carriers of the haplotype TAT for rs12574073, rs1128334 and rs4937333 were associated with increased risk of AS and haplotype CGC with reduced risk as compared to controls. In addition, ETS1 expression was lower in AS patients than controls. The risk allele A of rs1128334 and haplotype A-T of rs1128334 and rs4937333 were associated with decreased expression of ETS1.

Conclusions

Common variants in ETS1 may contribute to AS susceptibility in Han Chinese people.     

NdhO,a Subunit of NADPH Dehydrogenase,Destabilizes Medium Size Complex of the Enzyme in Synechocystis sp. Strain PCC 6803

Two mutants that grew faster than the wild-type (WT) strain under high light conditions were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in ssl1690 encoding NdhO. Deletion of ndhO increased the activity of NADPH dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET), while overexpression decreased the activity. Although deletion and overexpression of ndhO did not have significant effects on the amount of other subunits such as NdhH, NdhI, NdhK, and NdhM in the cells, the amount of these subunits in the medium size NDH-1 (NDH-1M) complex was higher in the ndhO-deletion mutant and much lower in the overexpression strain than in the WT. NdhO strongly interacts with NdhI and NdhK but not with other subunits. NdhI interacts with NdhK and the interaction was blocked by NdhO. The blocking may destabilize the NDH-1M complex and repress the NDH-CET activity. When cells were transferred from growth light to high light, the amounts of NdhI and NdhK increased without significant change in the amount of NdhO, thus decreasing the relative amount of NdhO. This might have decreased the blocking, thereby stabilizing the NDH-1M complex and increasing the NDH-CET activity under high light conditions.     

Genome‐wide variation within and between wild and domestic yak

The yak is one of the few animals that can thrive in the harsh environment of the Qinghai‐Tibetan Plateau and adjacent Alpine regions. Yak provides essential resources allowing Tibetans to live at high altitudes. However, genetic variation within and between wild and domestic yak remain unknown. Here, we present a genome‐wide study of the genetic variation within and between wild and domestic yak. Using next‐generation sequencing technology, we resequenced three wild and three domestic yak with a mean of fivefold coverage using our published domestic yak genome as a reference. We identified a total of 8.38 million SNPs (7.14 million novel), 383 241 InDels and 126 352 structural variants between the six yak. We observed higher linkage disequilibrium in domestic yak than in wild yak and a modest but distinct genetic divergence between these two groups. We further identified more than a thousand of potential selected regions (PSRs) for the three domestic yak by scanning the whole genome. These genomic resources can be further used to study genetic diversity and select superior breeds of yak and other bovid species.     

Downregulation of both gene expression and activity of Hsp27 improved maturation of mouse oocyte in vitro

Background  

Heat shock protein 27 (Hsp27), a member of the small heat shock protein family, is an apoptosis regulator. Our previous proteomic study showed that Hsp27 mainly expressed in human oocyte, and that Hsp27 expression was downregulated in the ovaries derived from women with the polycystic ovary syndrome (PCOS), a well known endocrinal disorder with abnormal apoptotic activity and folliculogenesis. However, the exact effects of Hsp27 downregulation on oocyte development have not yet been clarified.     

Immune protection induced on day 10 following administration of the 2009 A/H1N1 pandemic influenza vaccine

Background

The 2009 swine-origin influenza virus (S-OIV) H1N1 pandemic has caused more than 18,000 deaths worldwide. Vaccines against the 2009 A/H1N1 influenza virus are useful for preventing infection and controlling the pandemic. The kinetics of the immune response following vaccination with the 2009 A/H1N1 influenza vaccine need further investigation.

Methodology/Principal Findings

58 volunteers were vaccinated with a 2009 A/H1N1 pandemic influenza monovalent split-virus vaccine (15 µg, single-dose). The sera were collected before Day 0 (pre-vaccination) and on Days 3, 5, 10, 14, 21, 30, 45 and 60 post vaccination. Specific antibody responses induced by the vaccination were analyzed using hemagglutination inhibition (HI) assay and enzyme-linked immunosorbent assay (ELISA). After administration of the 2009 A/H1N1 influenza vaccine, specific and protective antibody response with a major subtype of IgG was sufficiently developed as early as Day 10 (seroprotection rate: 93%). This specific antibody response could maintain for at least 60 days without significant reduction. Antibody response induced by the 2009 A/H1N1 influenza vaccine could not render protection against seasonal H1N1 influenza (seroconversion rate: 3% on Day 21). However, volunteers with higher pre-existing seasonal influenza antibody levels (pre-vaccination HI titer ≥1∶40, Group 1) more easily developed a strong antibody protection effect against the 2009 A/H1N1 influenza vaccine as compared with those showing lower pre-existing seasonal influenza antibody levels (pre-vaccination HI titer <1∶40, Group 2). The titer of the specific antibody against the 2009 A/H1N1 influenza was much higher in Group 1 (geometric mean titer: 146 on Day 21) than that in Group 2 (geometric mean titer: 70 on Day 21).

Conclusions/Significance

Recipients could gain sufficient protection as early as 10 days after vaccine administration. The protection could last at least 60 days. Individuals with a stronger pre-existing seasonal influenza antibody response may have a relatively higher potential for developing a stronger humoral immune response after vaccination with the 2009 A/H1N1 pandemic influenza vaccine.