Molecular population genetics of the gene encoding the human fertilization protein zonadhesin reveals rapid adaptive evolution

A hallmark of positive selection (adaptive evolution) in protein-coding regions is a d(N)/d(S) ratio >1, where d(N) is the number of nonsynonymous substitutions/nonsynonymous sites and d(S) is the number of synonymous substitutions/synonymous sites. Zonadhesin is a male reproductive protein localized on the sperm head, comprising many domains known to be involved in cell-cell interaction or cell adhesion. Previous studies have shown that VWD domains (homologous to the D domains of the von Willebrand factor) are involved directly in binding to the female zona pellucida (ZP) in a species-specific manner. In this study, we sequenced 47 coding exons in 12 primate species and, by using maximum-likelihood methods to determine sites under positive selection, we show that VWD2, membrane/A5 antigen mu receptor, and mucin-like domains in zonadhesin are rapidly evolving and, thus, may be involved in binding to the ZP in a species-specific manner in primates. In addition, polymorphism data from 48 human individuals revealed significant polymorphism-to-divergence heterogeneity and a significant departure from equilibrium-neutral expectations in the frequency spectrum, suggesting balancing selection and positive selection occurring in zonadhesin (ZAN) within human populations. Finally, we observe adaptive evolution in haplotypes segregating for a frameshift mutation that was previously thought to indicate that ZAN was a potential pseudogene.     

Comprehensive proteomic analysis of Shigella flexneri 2a membrane proteins

Shigella flexneri is the causative agent of most shigellosis cases in developing countries. We used different proteolytic enzymes to selectively shave the protruding proteins on the surface of purified bacterial membrane sheets or vesicles, and recovered peptides were subsequently identified using 2-D LC-MS/MS. As a result, a total of 666 proteins were unambiguously assigned, including 159 integral membrane proteins, 35 outer membrane proteins and 114 proteins previously annotated as hypothetical. The former had an average grand average hydrophobicity score of 0.362 and were predicted to separate within a pH range of 4.1-10.6 with molecular mass 8-148 kDa, which represents the largest validated set of integral membrane proteins in this organism to date. A functional classification revealed that a large proportion of the identified proteins were involved in cell envelope biogenesis and energy production and conversion. For the first time, this work provides a global view of the S. flexneri 2a membrane subproteome.     

Association of D16S515 microsatellite with specific language impairment on Robinson Crusoe Island, an isolated Chilean population: a possible key to understanding language development

Specific language impairment (SLI) is a developmental language disorder that occurs for no known reason. The disorder affects 2-8% of children. Some scientific evidence suggests that genetic factors are implicated in the etiology of SLI. The disorder is genetically complex. Two novel loci, SLI1 on chromosome 16q24 (MIM 606711) and SLI2 on chromosome 19q13 (MIM 606712), have been found to be highly correlated with SLI. Four genes have been identified as susceptibility genes. SLI occurs at an unusually elevated incidence (35%) among the population of Robinson Crusoe Island (Chile), which also has a high consanguinity rate. This finding supports the influence of genetic mechanisms in the transmission of SLI based on a founder effect. To investigate further the genetic involvement in this population, we collected blood samples from 115 islanders from 13 families with a language-impaired proband and from 18 families with a normal-language proband. The analysis of micro satellite marker D16S515, located in locus SLI1, demonstrated that the 230-bp allele was correlated with SLI and that the 232-bp allele was correlated with normal language development. The domain containing the D16S515 marker, therefore, may play a role in language development.     

Trypanosoma cruzi modulates the expression of Rabs and alters the endocytosis in mouse cardiomyocytes in vitro.

Chagas disease is an incurable illness caused by the protozoan Trypanosoma cruzi. Cardiomyocytes represent important targets for the parasite infection and alterations in their physiology were reported. Because endocytosis is involved in different cellular events and guanosine triphosphatase (GTPase) Rab proteins play important roles in various aspects of the membrane traffic, our aim was to characterize the expression of Rab proteins in T. cruzi-infected cardiomyocytes, which displayed a downregulation of Rab7 and Rab11, whereas the expression of Rab5a was maintained in the infected cultures even after longer periods of parasite internalization, but early endosome antigen 1 was partially downregulated. The parasite infection also decreased the uptake of fluid phase ligands by the cardiac cultures. The regulation of GTPase proteins and effector molecules can contribute to the altered physiology of the host cells by modifying the normal incoming of nutrients as well as interfering with other important events related to the endocytic pathway.     

Disulfiram irreversibly aggregates betaine aldehyde dehydrogenase--a potential target for antimicrobial agents against Pseudomonas aeruginosa

In the human pathogen Pseudomonas aeruginosa, betaine aldehyde dehydrogenase (PaBADH) may play the dual role of assimilating carbon and nitrogen from choline or choline precursors--abundant at infection sites--and producing glycine betaine, which protects the bacterium against the high-osmolality stress prevalent in the infected tissues. This tetrameric enzyme contains four cysteine residues per subunit and is a potential drug target. In our search for specific inhibitors, we mutated the catalytic Cys286 to alanine and chemically modified the recombinant wild-type and the four Cys-->Ala single mutants with thiol reagents. The small methyl-methanethiosulfonate inactivated the enzymes without affecting their stability while the bulkier dithionitrobenzoic acid (DTNB) and bis[diethylthiocarbamyl] disulfide (disulfiram) induced enzyme dissociation--at 23 degrees C--and irreversible aggregation--at 37 degrees C. Of the four Cys-->Ala mutants only C286A retained its tetrameric structure after DTNB or disulfiram treatments, suggesting that steric constraints arising upon the covalent attachment of a bulky group to C286 resulted in distortion of the backbone configuration in the active site region followed by a severe decrease in enzyme stability. Since neither NAD(P)H nor betaine aldehyde prevented disulfiram-induced PaBADH inactivation or aggregation, and reduced glutathione was unable to restore the activity of the modified enzyme, we propose that disulfiram could be a useful drug to combat infection by P. aeruginosa.     

Identification and molecular characterisation of CmeB, a Campylobacter jejuni multidrug efflux pump

A multidrug efflux pump gene (cmeB) was identified from the published Campylobacter jejuni genome sequence. Secondary structural analysis showed that the gene encoded a protein belonging to the resistance nodulation cell division (RND) family of efflux transporters. The gene was inactivated by insertional mutagenesis. Compared with the wild-type strain (NCTC 11168), the resultant knockout strain (NCTC 11168-cmeB::kan(r)) displayed increased susceptibility to a range of antibiotics including beta-lactams, fluoroquinolones, macrolides, chloramphenicol, tetracycline, ethidium bromide, the dye acridine orange and the detergent sodium dodecyl sulfate. Accumulation of ciprofloxacin was increased in the knockout mutant, but carbonyl cyanide m-chlorophenyl hydrazone, a proton motive force inhibitor, had less effect upon ciprofloxacin accumulation in the knockout mutant compared with NCTC 11168. These data show that the identified gene encodes an RND-type multi-substrate efflux transporter, which contributes to intrinsic resistance to a range of structurally unrelated compounds in C. jejuni. This efflux pump has been named CmeB (for Campylobacter multidrug efflux).     

Evaluation of the efficacy of two mouthrinses formulated for the relief of xerostomia of diverse origin in adult subjects

doi: 10.1111/j.1741‐2358.2012.00626.x Evaluation of the efficacy of two mouthrinses formulated for the relief of xerostomia of diverse origin in adult subjects Objective: To evaluate the efficacy of two new mouthrinses in the reduction of xerostomía‐associated symptomatology. Background: Xerostomia is a common chronic health condition that affects a great number of adults and significantly deteriorates quality of life, such that treatment is necessary. Materials and methods: Sixty‐seven adult subjects of both sexes presenting xerostomia of diverse origin were selected. Mouthrinses were tested using a double‐blind, randomized, cross‐over clinical trial with an intervining wash out period. Results: The 100% of subjects presented sensation of dry mouth, and 86% stated sensation of thick saliva. Burning tongue sensation, need to drink liquids to swallow and the sensation of swallowing difficulty were recorded in more than 50% of the patients. The most frequent pathologies in the sample were depression, arthritis, and arterial hypertension. Results of the clinical tests showed that mouthrinse 1 relieves sensation of dry mouth, need to drink liquids, and swallowing difficulty. In contrast, mouthrinse 2 relieves only latter two symptoms. Both rinses were more effective in relieving xerostomía‐associated symptomatology in patients taking 3 or more medicines simultaneously. Conclusion: Both mouthrinses were effective in relieving various xerostomia symptoms, could be distributed at a low cost, thereby improving the quality of life of population affected.     

Virome analysis for identification of novel Mammalian viruses in bat species from chinese provinces

Bats are natural hosts for a large variety of zoonotic viruses. This study aimed to describe the range of bat viromes, including viruses from mammals, insects, fungi, plants, and phages, in 11 insectivorous bat species (216 bats in total) common in six provinces of China. To analyze viromes, we used sequence-independent PCR amplification and next-generation sequencing technology (Solexa Genome Analyzer II; Illumina). The viromes were identified by sequence similarity comparisons to known viruses. The mammalian viruses included those of the Adenoviridae, Herpesviridae, Papillomaviridae, Retroviridae, Circoviridae, Rhabdoviridae, Astroviridae, Flaviridae, Coronaviridae, Picornaviridae, and Parvovirinae; insect viruses included those of the Baculoviridae, Iflaviridae, Dicistroviridae, Tetraviridae, and Densovirinae; fungal viruses included those of the Chrysoviridae, Hypoviridae, Partitiviridae, and Totiviridae; and phages included those of the Caudovirales, Inoviridae, and Microviridae and unclassified phages. In addition to the viruses and phages associated with the insects, plants, and bacterial flora related to the diet and habitation of bats, we identified the complete or partial genome sequences of 13 novel mammalian viruses. These included herpesviruses, papillomaviruses, a circovirus, a bocavirus, picornaviruses, a pestivirus, and a foamy virus. Pairwise alignments and phylogenetic analyses indicated that these novel viruses showed little genetic similarity with previously reported viruses. This study also revealed a high prevalence and diversity of bat astroviruses and coronaviruses in some provinces. These findings have expanded our understanding of the viromes of bats in China and hinted at the presence of a large variety of unknown mammalian viruses in many common bat species of mainland China.     

One clutch or two clutches? Fitness correlates of coexisting alternative female life-histories in the European earwig

Whether to reproduce once or multiple times (semelparity vs. iteroparity) is a major life-history decision that organisms have to take. Mode of parity is usually considered a species characteristic. However, recent models suggested that population properties or condition-dependent fitness payoffs could help to maintain both life-history tactics within populations. In arthropods, semelparity was also hypothesised to be a critical pre-adaptation for the evolution of maternal care, semelparous females being predicted to provide more care due to the absence of costs on future reproduction. The aim of this study was to characterize potential fitness payoffs and levels of maternal care in semel- and itero-parous females of the European earwig Forficula auricularia. Based on 15 traits measured in 494 females and their nymphs, our results revealed that iteroparous females laid their first clutch earlier, had more eggs in their first clutch, gained more weight during the 2 weeks following hatching of the first clutch, but produced eggs that developed more slowly than semelparous females. Among iteroparous females, the sizes of first and second clutches were significantly and positively correlated, indicating no investment trade-off between reproductive events. Iteroparous females also provided more food than semelparous ones, a result contrasting with predictions that iteroparity is incompatible with the evolution of maternal care. Finally, a controlled breeding experiment reported full mating compatibility among offspring from females of the two modes of parity, confirming that both types of females belong to one single species. Overall, these results indicate that alternative modes of parity represent coexisting life-history tactics that are likely to be condition-dependent and associated with offspring development and specific levels of maternal care in earwigs.