Patterns of Biofilm Succession on a Sheltered Rocky Shore in Hong Kong

Successional patterns are dependent on the nature of the substratum, water flow, concentrations of organics as well as the availability of bacteria, algal spores and invertebrate larvae in the coastal environment. Bacteria play an especially important role in biofilm formation as they are generally the earliest colonizers. In the present study, both winter and summer biofilm succession patterns were examined on glass coverslips inverted on experimental racks attached at two tidal levels on a sheltered shore in Hong Kong. In the succession, bacteria were followed by diatoms and cyanobacteria. Encrusting algae appeared in the late stages of the experiment (day 80 in summer and day 60 in winter). Colonization by bacteria was much slower in summer and their density remained low throughout the experimental period. The first appearance of diatoms and cyanobacteria, however, was more rapid in the summer. Bacteria and diatoms on the low-shore surfaces also had a faster succession rate than on the high-shore surfaces, suggesting that desiccation/aerial temperature are the causal factors for such differences.     

Antagonist-mediated down-regulation of toll-like receptors increases the prevalence of human papillomavirus infection in systemic lupus erythematosus

IntroductionPrevalence of an abnormal Papanicolaou smear was significantly increased in lupus patients in cross-sectional studies, associated with a higher prevalence of high-risk human papillomavirus (HPV) infection. The nucleic acid-specific Toll-like receptors (TLRs) locate at the endolysosomal compartments and trigger the induction of cytokines for the innate immune response. This study evaluated whether abnormal host innate immune response in lupus patients may enhance HPV persistence.MethodsProtein levels of TLRs 3, 7, 8 and 9 in cervical epithelial cells of lupus patients and controls with or without HPV infection were assessed using flow cytometry. Characteristics associated with the differential expression of TLRs in systemic lupus erythematosus (SLE) were elucidated. The effect and interferon-stimulated genes (ISGs) (ISG15 and Mx-1) gene expressions were then measured in oncogenic HeLa (HPV18), CaSki (HPV) and C33A (HPV negative) cell lines using flow cytometry and quantitative real-time PCR. Ex vivo productions of cytokines and interferon-gamma (IFN-γ) upon TLR ligands stimulations were subsequently measured using cytometric bead array and ELISA.ResultsFor subjects with HPV infection, levels of TLR3 and TLR7 were significantly lower in lupus patients compared with controls. Significantly decreased TLRs 7, 8 and 9 levels were observed in HPV-negative SLE compared to healthy controls. For SLE with and without HPV infection, TLR7 and 9 levels were significantly lower in infected SLE than those in HPV-negative patients. Independent explanatory variables associated with down-regulation of TLR7 level included HPV infection and a higher cumulative dose of prednisolone; while a higher cumulative dose of hydroxychloroquine and HPV infection were associated with down-regulation of TLR9 level. In cervical cell lines, TLRs 3, 7, 8, 9 protein levels and antiviral ISG15 and Mx-1 gene expressions were inhibited in two oncogenic HPV types. Functional data showed that the induction of pro-inflammatory cytokines by TLR ligands (R837, ssRNA and ODN2395) was greatly impaired in CaSki and HeLa than C33A cells.ConclusionsIn conclusion, prednisolone and TLR antagonist (hydroxychloroquine) may down-regulate protein levels of TLR7 and TLR9 in lupus patients, thereby decreasing the innate immune response against HPV infection. Upon infection, HPV further down-regulate TLR7 and 9 levels for viral persistence. Furthermore, reduction of nucleic acid-sensing TLRs 7, 8 and 9 in carcinogenic HPVs ensures that the expression of inducible pro-inflammatory cytokines is minimized to prevent the expression of antiviral ISGs (ISG15 and Mx-1) on a biologically relevant antiviral response.     

Computational prediction of essential genes in an unculturable endosymbiotic bacterium, Wolbachia of Brugia malayi

Background  

Wolbachia (wBm) is an obligate endosymbiotic bacterium of Brugia malayi, a parasitic filarial nematode of humans and one of the causative agents of lymphatic filariasis. There is a pressing need for new drugs against filarial parasites, such as B. malayi. As wBm is required for B. malayi development and fertility, targeting wBm is a promising approach. However, the lifecycle of neither B. malayi nor wBm can be maintained in vitro. To facilitate selection of potential drug targets we computationally ranked the wBm genome based on confidence that a particular gene is essential for the survival of the bacterium.     

Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa

The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galalpha1-->4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group Pkactive Galalpha1-->4Gal, was the best. It was 7.4-fold less active than melibiose (Galalpha1-->6Glc). PA-IL has a preference for the alpha-anomer in decreasing order as follows: Galalpha1-->6 >Galalpha1-->4 >Galalpha1-->3. Of the monosaccharides studied, the phenylbeta derivatives of Gal were much better inhibitors than the methylbeta derivative, while only an insignificant difference was found between the Galalpha anomer of methyl- and p -NO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the alpha-anomer of Gal at nonreducing end and most complementary to Galalpha1-->6Glc. As for the combining site of PA-IL toward the beta-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.      

Genetic consequences of anthropogenic disturbances and population fragmentation in <Emphasis Type="Italic">Acacia senegal</Emphasis>

Acacia senegal is endemic to dry forest and woodland ecosystems of Sub-Saharan Africa and provides both ecological and socio-economic benefits. However, these ecosystems are threatened by escalating human disturbances and fragmentation. To investigate the human impacts on genetic diversity and structure of A. senegal, we studied genetic variability and differentiation of 330 individual trees from 11 natural A. senegal populations, grouped into lightly and heavily disturbed, using 12 polymorphic nuclear microsatellite markers. Gene diversity (H _E ) ranged from H _E = 0.570 to H _E = 0.632. Significant differences (P < 0.05) between the levels of disturbances are reported for mean gene diversity, number of alleles and allelic richness with lightly disturbed populations showing higher values. Overall, the indirect estimates of average outcrossing rates ranged from 0.794 (Kiserian) to 0.999 (Kampi ya Moto) with a mean of 0.997 suggesting a predominantly outcrossing species. There was no significant relationship (P > 0.05) detected between genetic and geographic distances, showing lack of isolation by distance. Analysis of population structure using unweighted pair group method with arithmetic mean and Bayesian model suggests presence of three gene pools as most probable, although most individuals showed mixed ancestry. The diversity and genetic structure reported in this study revealed negative impacts of human disturbance on A. senegal within this ecosystem. We recommend in-situ conservation strategies to safeguard the woodland ecosystem from further deforestation.     

Different mutation patterns of mitochondrial DNA displacement-loop in hepatocellular carcinomas induced by N-nitrosodiethylamine and a choline-deficient l-amino acid-defined diet in rats

Mutations of the mitochondria DNA (mtDNA) displacement loop (D-loop) were investigated to clarify different changes of exogenous and endogenous liver carcinogenesis in rats. We induced hepatocellular carcinomas (HCCs) in rats with N-nitrosodiethylamine (DEN) and a choline-deficient l-amino acid-defined (CDAA) diet. DNAs were extracted from 10 HCCs induced by DEN and 10 HCCs induced by the CDAA diet. To identify mutations in mtDNA D-loop, polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis, followed by nucleotide sequencing, was performed. Mutations were detected in 5 out of 10 HCCs (50%) induced by DEN. Four out of 5 mutations were G/C to A/T transitions at positions 15707, 15717, 15930, and 16087, and one T/A to C/G transition at position 15559. By contrast, no mutations were found in 10 HCCs induced by the CDAA diet. These results demonstrated that mutations in mtDNA D-loop occur in rat HCCs induced by DEN but not by the CDAA diet, suggesting that mtDNA D-loop is a target of exogenous liver carcinogenesis in rats.     

Effect of self-association on the structural organization of partially folded proteins: inactivated actin

The propensity to associate or aggregate is one of the characteristic properties of many nonnative proteins. The aggregation of proteins is responsible for a number of human diseases and is a significant problem in biotechnology. Despite this, little is currently known about the effect of self-association on the structural properties and conformational stability of partially folded protein molecules. G-actin is shown to form equilibrium unfolding intermediate in the vicinity of 1.5 M guanidinium chloride (GdmCl). Refolding from the GdmCl unfolded state is terminated at the stage of formation of the same intermediate state. An analogous form, known as inactivated actin, can be obtained by heat treatment, or at moderate urea concentration, or by the release of Ca(2+). In all cases actin forms specific associates comprising partially folded protein molecules. The structural properties and conformational stability of inactivated actin were studied over a wide range of protein concentrations, and it was established that the process of self-association is rather specific. We have also shown that inactivated actin, being denatured, is characterized by a relatively rigid microenvironment of aromatic residues and exhibits a considerable limitation in the internal mobility of tryptophans. This means that specific self-association can play an important structure-forming role for the partially folded protein molecules.     

Ultrasound to Decontaminate Organics in Dredged Sediments

Sediments contaminated with organics compounds due to past disposal practices threaten the environment and require remediation. This study was an attempt to develop a technology to decontaminate organics in dredged sediments using ultrasound coupled with vacuum pressure. A set of laboratory scale experiments were carried out using simulated dredged sediments from New York/New Jersey harbor, category III sediments that failed to meet USEPA requirements for toxicity or bioaccumulation, and required secure disposal. Acoustic cavitation due to ultrasound energy coupled with vacuum pressure was used to facilitate the removal of p-terphenyl (the selected organic contaminant) from the sediments. Two coupled processes were used to separate and to treat both coarse (Process 1) and fine (Process 2) fractions of sediments. Selected variables for evaluation of Process 1 were ultrasound power, solvent to sediment ratio, vacuum pressure, and sonication time. Process 2 was evaluated without and with surfactants. Process 2 without surfactant had three variables: power, solvent to sediment ratio, and sonication time, while Process 2 with surfactant had four variable contributing to its performance: power, solvent to sediment ratio, surfactant concentration, and sonication time. Laboratory-scale experiments were carried out with various combinations of these parameters according to the factorial design. Experimental test results showed that Process 1 had 99% contaminant removal efficiency at 60% power (900 Watts), 15:1 solvent to sediment ratio, 15?psi vacuum pressure, and 9?min of sonication time. Similarly, Process 2 without the surfactant had 55% contaminant removal efficiency at 80% power (1200 Watts), 50:1 solvent to sediment ratio, and 90?min of sonication time. Modification of Process 2 with the addition of a surfactant produced 89% contaminant removal efficiency at 80% power (1200 Watts), 50:1 solvent to sediment ratio, 0.1% surfactant concentration, and 60?min of sonication time. The study showed that the proposed treatment technique is effective for treating dredged sediments.     

Can Reproductive Health Voucher Programs Improve Quality of Postnatal Care? A Quasi-Experimental Evaluation of Kenya’s Safe Motherhood Voucher Scheme

This study tests the group-level causal relationship between the expansion of Kenya’s Safe Motherhood voucher program and changes in quality of postnatal care (PNC) provided at voucher-contracted facilities. We compare facilities accredited since program inception in 2006 (phase I) and facilities accredited since 2010-2011 (phase II) relative to comparable non-voucher facilities. PNC quality is assessed using observed clinical content processes, as well as client-reported outcome measures. Two-tailed unpaired t-tests are used to identify differences in mean process quality scores and client-reported outcome measures, comparing changes between intervention and comparison groups at the 2010 and 2012 data collection periods. Difference-in-differences analysis is used to estimate the reproductive health (RH) voucher program’s causal effect on quality of care by exploiting group-level differences between voucher-accredited and non-accredited facilities in 2010 and 2012. Participation in the voucher scheme since 2006 significantly improves overall quality of postnatal care by 39% (p=0.02), where quality is defined as the observable processes or components of service provision that occur during a PNC consultation. Program participation since phase I is estimated to improve the quality of observed maternal postnatal care by 86% (p=0.02), with the largest quality improvements in counseling on family planning methods (IRR 5.0; p=0.01) and return to fertility (IRR 2.6; p=0.01). Despite improvements in maternal aspects of PNC, we find a high proportion of mothers who seek PNC are not being checked by any provider after delivery. Additional strategies will be necessary to standardize provision of packaged postnatal interventions to both mother and newborn. This study addresses an important gap in the existing RH literature by using a strong evaluation design to assess RH voucher program effectiveness on quality improvement.