Fe- and S-Metabolizing Microbial Communities Dominate an AMD-Contaminated River Ecosystem and Play Important Roles in Fe and S Cycling

Indigenous Fe- and S-metabolizing bacteria play important roles both in the formation and the natural attenuation of acid mine drainage (AMD). Due to its low pH and Fe-S-rich waters, a river located in the Dabaoshan Mine area provides an ideal opportunity to study indigenous Fe- and S-metabolizing microbial communities and their roles in biogeochemical Fe and S cycling. In this work, water and sediment samples were collected from the river for physicochemical, mineralogical, and microbiological analyses. Illumina MiSeq sequencing indicated higher species richness in the sediment than in the water. Sequencing also found that Fe- and S-metabolizing bacteria were the dominant microorganisms in the heavily and moderately contaminated areas. Fe- and S-metabolizing bacteria found in the water were aerobes or facultative anaerobes, including Acidithiobacillus, Acidiphilium, Thiomonas, Gallionella, and Leptospirillum. Fe- and S-metabolizing bacteria found in the sediment belong to microaerobes, facultative anaerobes, or obligatory anaerobes, including Acidithiobacillus, Sulfobacillus, Thiomonas, Gallionella, Geobacter, Geothrix, and Clostridium. Among the dominant genera in the sediment, Geobacter and Geothrix were rarely detected in AMD-contaminated natural environments. Canonical correspondence analysis indicated that pH, S, and Fe concentration gradients were the most important factors in structuring the river microbial community. Moreover, a scheme explaining the biogeochemical Fe and S cycling is advanced in light of the Fe and S species distribution and the identified Fe- and S-metabolizing bacteria.     

MicroRNA-30a sensitizes tumor cells to cis-platinum via suppressing beclin 1-mediated autophagy

Autophagy is activated in cancer cells during chemotherapy and often contributes to tumor chemotherapy resistance. In this study, we characterized the role of microRNA-30a (miR-30a) in the coordination of cancer cell apoptosis and autophagy, which determines the sensitivity of cancer cells to chemotherapy. First, the autophagy activity in cancer cells increased after cis-dichloro-diamine platinum (cis-DDP) or Taxol treatment, as indicated by the enhanced expression of beclin 1, a key regulator of autophagy, and increased number of LC3-positive autophagosomes. Second, miRNA screening using a TaqMan probe-based quantitative RT-PCR assay identified that miR-30a, a miRNA that targets beclin 1, was significantly reduced in tumor cells by cis-DDP treatment. Forced expression of miR-30a significantly reduced beclin 1 and the autophagy activity of tumor cells induced by cis-DDP. Third, the blockade of tumor cell autophagy activity by miR-30a expression or 3-methyladenine significantly increased tumor cell apoptosis induced by cis-DDP treatment. Finally, an in vivo tumor implantation mouse model clearly showed that elevation of miR-30a in implanted tumor cells by administration of the recombinant lentivirus expressing miR-30a strongly enhanced cis-DDP-induced apoptosis of tumor cells. In conclusion, our results demonstrate for the first time that miR-30a can sensitize tumor cells to cis-DDP via reducing beclin 1-mediated autophagy and that increasing miR-30a level in tumor cells represents a novel approach to enhance the efficacy of chemotherapy during cancer treatment.     

Testing hypotheses driving genetic structure in the cooperatively breeding Brown‐headed Nuthatch Sitta pusilla

Habitat fragmentation has often been implicated in the decline of many species. For habitat specialists and/or sedentary species, loss of habitat can result in population isolation and lead to negative genetic effects. However, factors other than fragmentation can often be important and also need to be considered when assessing the genetic structure of a species. We genotyped individuals from 13 populations of the cooperatively breeding Brown‐headed Nuthatch Sitta pusilla in Florida to test three alternative hypotheses regarding the effects that habitat fragmentation might have on genetic structure. A map of potential habitat developed from recent satellite imagery suggested that Brown‐headed Nuthatch populations in southern Florida occupied smaller and more isolated habitat patches (i.e. were more fragmented) than populations in northern Florida. We also genotyped individuals from a small, isolated Brown‐headed Nuthatch population on Grand Bahama Island. We found that populations associated with more fragmented habitat in southern Florida had lower allelic richness than populations in northern Florida (P = 0.02), although there were no differences in heterozygosity. Although pairwise estimates of F_ST were low overall, values among southern populations were generally higher than northern populations. Population assignment tests identified K = 3 clusters corresponding to a northern cluster, a southern cluster and a unique population in southeast Florida; using sampling localities as prior information revealed K = 7 clusters, with greater structure only among southern Florida populations. The Bahamas population showed moderate to high differentiation compared with Florida populations. Overall, our results suggest that fragmentation could affect gene flow in Brown‐headed Nuthatch populations and is likely to become more pronounced over time.     

Novel Biomarkers for Non-functioning Invasive Pituitary Adenomas were Identified by Using Analysis of microRNAs Expression Profile

The microRNAs (miRNAs) are involved in multiple pathological processes among various types of tumors. However, the functions of miRNAs in benign brain tumors are largely unexplored. In order to explore the pathogenesis of the invasiveness in non-functional pituitary adenoma (NFPA), the miRNAs expression profile was analyzed between invasive and non-invasive non-functional pituitary adenoma by miRNAs microarray. Six most significant differentially expressed miRNAs were identified including four upregulated miRNAs hsa-miR-181b-5p, hsa-miR-181d, hsa-miR-191-3p, and hsa-miR-598 and two downregulated miRNAs hsa-miR-3676-5p and hsa-miR-383. The functions and corresponding signaling pathways of differentially expressed miRNAs were investigated by bioinformatics techniques, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The result of GO analysis indicates regulation of voltage-gated potassium channel activity, positive regulation of sodium ion transport, positive regulation of GTPase activity, negative regulation of Notch signaling pathway, etc. KEGG pathway reveals a series of biological processes, including prolactin signaling pathway, endocrine and other factor-regulated calcium reabsorption, fatty acid metabolism, neuroactive ligand-receptor interaction, etc. The miRNAs hsa-miR-181a-5p was verified by quantitative real-time PCR, and the expression level was in accordance with the microarray result. Our result can provide the evidence on featured miRNAs which play a prominent role in pituitary adenoma as effective biomarkers and therapeutic targets in the future.     

Removal of selectable marker gene from fibroblast cells in transgenic cloned cattle by transient expression of Cre recombinase and subsequent effects on recloned embryo development

Introduction of selectable marker genes to transgenic animals could create an inconvenience to further research and may exaggerate public concerns regarding biological safety. The objective of the current study was to excise loxP flanked neo^R in transgenic cloned cattle by transient expression of Cre recombinase. Green fluorescent protein gene (GFP) was incorporated to monitor Cre expression; therefore, Cre-expressed cells could be selected indirectly by fluorescence-activated cell sorting (FACS). The neo^R was removed and Cre expressed transiently in GFP-positive colonies; excision of neo^R was confirmed by single-blastocyst PCR in recloned blastocysts, with neo^R-free fibroblast cells as donors. There was no difference (P > 0.05) in rates of cleavage (76.0% vs. 68.8%) or blastocyst formation (56.6% vs. 52.9%) between recloned embryos with neo^R-free or neo^R-included donors. The differential staining of recloned blastocysts were similar (P >0.05) in terms of total cell number (124 vs. 122) and the ratio of ICM (Inner Cell Mass) to the total cell number (38.1% vs. 38.2%). Furthermore, pregnancy and calving rates were not different (P > 0.05) from those of the control. In conclusion, we successfully excised neo^R from transgenic cloned cattle; the manipulation did not affect the developmental competence of recloned preimplantation embryos. This approach should benefit bioreactor and transgenic research in livestock.     

The effect of different platelet-rich plasma concentrations on proliferation and differentiation of human periodontal ligament cells in vitro

OBJECTIVES: The use of platelets and platelet products has become increasingly popular clinically as a means of accelerating endosseous wound healing. It is likely that growth factors released by activated platelets at the site of injury play a role in periodontal regeneration by regulating cellular activity. The purpose of this study was to evaluate the biological effects of platelet-rich plasma (PRP) on human periodontal ligament cells (hPDLCs) in vitro. MATERIALS AND METHODS: Primary cultures of hPDLCs were obtained from healthy premolars. PRP was isolated by two-step centrifugation. Two main growth factors present in the thrombin-activated PRP (platelet-derived growth factor [PDGF-AB] and transforming growth factor-beta1 [TGF-beta1]) were evaluated using ELISA assay. Activated PRP or the combination of recombined human TGF-beta1 (rhTGF-beta1) and PDGF-AB (rhPDGF-AB) were added to hPDLCs in different concentrations to assess cell proliferation and osteogenic differentiation. RESULTS: PRP contained high levels of TGF-beta1 and PDGF-AB. Cell attachment, proliferation and ALP activity were enhanced by addition of PRP or rhTGF-beta1 and rhPDGF-AB combination to the cell cultures, while the stimulatory potency of PRP was much greater than the latter. These stimulatory effects presented in a dose-dependant manner, it seemed that PRP with 50~100 ng/ml TGF-beta1 was an ideal concentration. CONCLUSIONS: PRP can enhance hPDLC adhesion, proliferation and induce the differentiation of hPDLC into mineralized tissue formation cell; thereby contribute to the main processes of periodontal tissue regeneration. For economical and biological reasons, PRP has more clinical beneficial than analogous growth factors.     

Genome Sequence of Hybrid Vibrio cholerae O1 MJ-1236, B-33, and CIRS101 and Comparative Genomics with V. cholerae

The genomes of Vibrio cholerae O1 Matlab variant MJ-1236, Mozambique O1 El Tor variant B33, and altered O1 El Tor CIRS101 were sequenced. All three strains were found to belong to the phylocore group 1 clade of V. cholerae, which includes the 7th-pandemic O1 El Tor and serogroup O139 isolates, despite displaying certain characteristics of the classical biotype. All three strains were found to harbor a hybrid variant of CTXΦ and an integrative conjugative element (ICE), leading to their establishment as successful clinical clones and the displacement of prototypical O1 El Tor. The absence of strain- and group-specific genomic islands, some of which appear to be prophages and phage-like elements, seems to be the most likely factor in the recent establishment of dominance of V. cholerae CIRS101 over the other two hybrid strains.Vibrio cholerae, a bacterium autochthonous to the aquatic environment, is the causative agent of cholera, a life-threatening disease that causes severe, watery diarrhea. Cholera bacteria are serogrouped based on their somatic O antigens, with more than 200 serogroups identified to date (6). Only toxigenic strains of serogroups O1 and O139 have been identified as agents of cholera epidemics and pandemics; serogroups other than O1 and O139 have the potential to cause mild gastroenteritis or, rarely, local outbreaks. Genes coding for cholera toxin (CTX), ctxAB, and other virulence factors have been shown to reside in bacteriophages and various mobile genetic elements. In addition, V. cholerae serogroup O1 is differentiated into two biotypes, classical and El Tor, by a combination of biochemical traits, by sensitivity to biotype-specific bacteriophages, and more recently by nucleotide sequencing of specific genes and by molecular typing (5, 17, 19).There have been seven pandemics of cholera recorded throughout human history. The seventh and current pandemic began in 1961 in the Indonesian island of Sulawesi and subsequently spread to Asia, Africa, and Latin America; the six previous pandemics are believed to have originated in the Indian subcontinent. Isolates of the sixth pandemic were almost exclusively of the O1 classical biotype, whereas the current (seventh) pandemic is dominated by the V. cholerae O1 El Tor biotype as the causative agent, a transition occurring between 1923 and 1961. Today, the disease continues to remain a scourge in developing countries, confounded by the fact that V. cholerae is native to estuaries and river systems throughout the world (8).Over the past 20 years, several new epidemic lineages of V. cholerae O1 El Tor have emerged (or reemerged). For example, in 1992, a new serogroup, namely, O139 of V. cholerae, was identified as the cause of epidemic cholera in India and Bangladesh (25). The initial concern was that a new pandemic was beginning; however, the geographic range of V. cholerae O139 is currently restricted to Asia. Additionally, V. cholerae O1 hybrids and altered El Tor variants have been isolated repeatedly in Bangladesh (Matlab) (23, 24) and Mozambique (1). Altered V. cholerae O1 El Tor isolates produce cholera toxin of the classical biotype but can be biotyped as El Tor by conventional phenotypic assays, whereas V. cholerae O1 hybrid variants cannot be biotyped based on phenotypic tests and can produce cholera toxin of either biotype. These new variants have subsequently replaced the prototype seventh-pandemic V. cholerae O1 El Tor strains in Asia and Africa, with respect to frequency of isolation from clinical cases of cholera (27).Here, we report the genome sequence of three V. cholerae O1 variants, MJ-1236, a Matlab type I hybrid variant from Bangladesh that cannot be biotyped by conventional methods, CIRS101, an altered O1 El Tor isolate from Bangladesh which harbors ctxB of classical origin, and B33, an altered O1 El Tor isolate from Mozambique which harbors classical CTXΦ, and we compare their genomes with prototype El Tor and classical genomes. From an epidemiological viewpoint, among the three variants characterized in this study, V. cholerae CIRS101 is currently the most “successful” in that strains belonging to this type have virtually replaced the prototype El Tor in Asia and many parts of Africa, notably East Africa. This study, therefore, gives us a unique opportunity to understand why V. cholerae CIRS101 is currently the most successful El Tor variant.     

A Passive Anti-icing Strategy Based on a Superhydrophobic Mesh with Extremely Low Ice Adhesion Strength

Although superhydrophobic materials have attracted much research interest in anti-icing,some controversy still exists.In this research,we report a cost-effective method used to verify the contribution of area fraction to ice adhesion strength.We tried to partially-embed siliea nanopnarticles into microscale fabrics of a commercial polyamide mesh.Then,the area fraction could be determined by altering the mesh size.Generally,the ice adhesion strength decreases as the area fraction decreases.An ice adhesion strength of~1.9 kPa and a delayed freezing time of~1048 s can be obtained.We attribute the low ice adhesion strength to the combination of superhydro-phobicity and stress concentration.The superhydrophobicity prohibits the water from penetrating into the voids of the meshes,and the small actual contact area leads to stress concentration which promotes interfacial crack propagation.Moreover,our superhydrophobic mesh simultaneously exhibis a micro-nano hierarchical structure and a partally-cmbedded structure.Therefore,the as-prepared superhydrophobic mesh retained the ieephobicity after 20 icingldeicing cycles,and maintained its superhydrophobicity even afier 60 sandpaper-abrasion cycles and a 220"C thermal treatment.