SPG20 is mutated in Troyer syndrome,an hereditary spastic paraplegia

Troyer syndrome (TRS) is an autosomal recessive complicated hereditary spastic paraplegia (HSP) that occurs with high frequency in the Old Order Amish. We report mapping of the TRS locus to chromosome 13q12.3 and identify a frameshift mutation in SPG20, encoding spartin. Comparative sequence analysis indicates that spartin shares similarity with molecules involved in endosomal trafficking and with spastin, a molecule implicated in microtubule interaction that is commonly mutated in HSP.     

Structure of the cell-puncturing device of bacteriophage T4

Bacteriophage T4 has a very efficient mechanism for infecting cells. The key component of this process is the baseplate, located at the end of the phage tail, which regulates the interaction of the tail fibres and the DNA ejection machine. A complex of gene product (gp) 5 (63K) and gp27 (44K), the central part of the baseplate, is required to penetrate the outer cell membrane of Escherichia coli and to disrupt the intermembrane peptidoglycan layer, promoting subsequent entry of phage DNA into the host. We present here a crystal structure of the (gp5-gp27)3 321K complex, determined to 2.9 A resolution and fitted into a cryo-electron microscopy map at 17 A resolution of the baseplate-tail tube assembly. The carboxy-terminal domain of gp5 is a triple-stranded beta-helix that forms an equilateral triangular prism, which acts as a membrane-puncturing needle. The middle lysozyme domain of gp5, situated on the periphery of the prism, serves to digest the peptidoglycan layer. The amino-terminal, antiparallel beta-barrel domain of gp5 is inserted into a cylinder formed by three gp27 monomers, which may serve as a channel for DNA ejection.     

The functions of animal microRNAs

MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.     

贝加尔与江苏蝶类区系比较及成因分析

对贝加尔和江苏地区蝶类区系分布做了调查,其中大约有近200份的蝴蝶标本采集于贝加尔地区、有1000多份标本采集于江苏地区．在完成此次调查工作的基础上,结合前人工作总结出了两地区的蝶类名录,江苏地区蝶类共10科105属178种,贝加尔地区蝶类7科39属55种．为此,还比较两地区蝶类区系多样性的相似性和差异性,并分别从气候、寄主植物分布和蝶类起源与演化3个方面分析了造成两地区蝶类分布相似性和差异性的原因．     

Genome-wide association study identifies a susceptibility locus for thyrotoxic periodic paralysis at 17q24.3

Thyrotoxic periodic paralysis (TPP) is a potentially life-threatening complication of thyrotoxicosis. We conducted a genome-wide association study (GWAS) and a replication study with a total of 123 southern Chinese with TPP (cases) and 1,170 healthy controls and identified a susceptibility locus on chromosome 17q24.3 near KCNJ2 (rs312691: odds ratio (OR) = 3.3; P(meta-analysis) = 1.8 × 10(-14)). All subjects with TPP also had Graves' disease, and subsequent TPP versus Graves' disease comparison confirmed that the association at 17q24.3 was specific to TPP. The area under the curve (AUC) of rs312691 genotype for risk prediction of TPP in subjects with Graves' disease was 0.73. Expression quantitative trait locus (eQTL) analysis identified SNPs in the region flanking rs312691 (±10 kb) that could potentially affect KCNJ2 expression (P = 0.0001). Our study has identified a susceptibility locus associated with TPP and provides insight into the causes of TPP.     

Mutations in sodium-borate cotransporter SLC4A11 cause recessive congenital hereditary endothelial dystrophy (CHED2)

Congenital hereditary endothelial dystrophy (CHED) is a heritable, bilateral corneal dystrophy characterized by corneal opacification and nystagmus. We describe seven different mutations in the SLC4A11 gene in ten families with autosomal recessive CHED. Mutations in SLC4A11, which encodes a membrane-bound sodium-borate cotransporter, cause loss of function of the protein either by blocking its membrane targeting or nonsense-mediated decay.     

Membrane-shed vesicles from the parasite <Emphasis Type="Italic">Trichomonas vaginalis</Emphasis>: characterization and their association with cell interaction

Trichomonas vaginalis is a common sexually transmitted parasite that colonizes the human urogenital tract, where it remains extracellular and adheres to epithelial cells. Infections range from asymptomatic to highly inflammatory, depending on the host and the parasite strain. Despite the serious consequences associated with trichomoniasis disease, little is known about parasite or host factors involved in attachment of the parasite-to-host epithelial cells. Here, we report the identification of microvesicle-like structures (MVs) released by T. vaginalis. MVs are considered universal transport vehicles for intercellular communication as they can incorporate peptides, proteins, lipids, miRNA, and mRNA, all of which can be transferred to target cells through receptor–ligand interactions, fusion with the cell membrane, and delivery of a functional cargo to the cytoplasm of the target cell. In the present study, we demonstrated that T. vaginalis release MVs from the plasma and the flagellar membranes of the parasite. We performed proteomic profiling of these structures demonstrating that they possess physical characteristics similar to mammalian extracellular vesicles and might be selectively charged with specific protein content. In addition, we demonstrated that viable T. vaginalis parasites release large vesicles (LVs), membrane structures larger than 1 µm that are able to interact with other parasites and with the host cell. Finally, we show that both populations of vesicles present on the surface of T vaginalis are induced in the presence of host cells, consistent with a role in modulating cell interactions.