Multifactorial diversity sustains microbial community stability

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty.     

Sulfate reduction and S-oxidation in a moorland pool sediment

In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO₄ ^2– reduction rates in the sediment, (2) depletion of SO₄ ^2– in the overlying water column and (3) release of³⁵S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO₄ ^2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core³⁵SO₄ ^2– injection. Rates of SO₄ ^2– consumption in the overlying water were estimated by changes in SO₄ ^2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m^–2 d^–1. Rates of SO₄ ^2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m^–2 d^–1 (November) to 0.43–1.81 mmol m^–2 d^–1 (July, August and April). Maximum rates of oxidation to SO₄ ^2– in July 1990 estimated by combination of SO₄ ^2– reduction rates and rates of in situ SO₄ ^2– uptake in the enclosed water column were 10.3 and 10.5 mmol m^–2 d^–1 at an organic rich and at a sandy site respectively.Experiments with³⁵S^2– and³⁵SO₄ ^2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO₄ ^2– and (2) the presence of mainly non SO₄ ^2–-S derived from reduced S transported from the sediment into the overlying water. A³⁵S^2– tracer experiment showed that about 7% of³⁵S^2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author     

Influenza H5N1 virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells

Background

Highly pathogenic avian influenza (HPAI) H5N1 virus is entrenched in poultry in Asia and Africa and continues to infect humans zoonotically causing acute respiratory disease syndrome and death. There is evidence that the virus may sometimes spread beyond respiratory tract to cause disseminated infection. The primary target cell for HPAI H5N1 virus in human lung is the alveolar epithelial cell. Alveolar epithelium and its adjacent lung microvascular endothelium form host barriers to the initiation of infection and dissemination of influenza H5N1 infection in humans. These are polarized cells and the polarity of influenza virus entry and egress as well as the secretion of cytokines and chemokines from the virus infected cells are likely to be central to the pathogenesis of human H5N1 disease.

Aim

To study influenza A (H5N1) virus replication and host innate immune responses in polarized primary human alveolar epithelial cells and lung microvascular endothelial cells and its relevance to the pathogenesis of human H5N1 disease.

Methods

We use an in vitro model of polarized primary human alveolar epithelial cells and lung microvascular endothelial cells grown in transwell culture inserts to compare infection with influenza A subtype H1N1 and H5N1 viruses via the apical or basolateral surfaces.

Results

We demonstrate that both influenza H1N1 and H5N1 viruses efficiently infect alveolar epithelial cells from both apical and basolateral surface of the epithelium but release of newly formed virus is mainly from the apical side of the epithelium. In contrast, influenza H5N1 virus, but not H1N1 virus, efficiently infected polarized microvascular endothelial cells from both apical and basolateral aspects. This provides a mechanistic explanation for how H5N1 virus may infect the lung from systemic circulation. Epidemiological evidence has implicated ingestion of virus-contaminated foods as the source of infection in some instances and our data suggests that viremia, secondary to, for example, gastro-intestinal infection, can potentially lead to infection of the lung. HPAI H5N1 virus was a more potent inducer of cytokines (e.g. IP-10, RANTES, IL-6) in comparison to H1N1 virus in alveolar epithelial cells, and these virus-induced chemokines were secreted onto both the apical and basolateral aspects of the polarized alveolar epithelium.

Conclusion

The predilection of viruses for different routes of entry and egress from the infected cell is important in understanding the pathogenesis of influenza H5N1 infection and may help unravel the pathogenesis of human H5N1 disease.     

N-(1,2-diphenylethyl)piperazines: a new class of dual serotonin/noradrenaline reuptake inhibitor

The synthesis and structure-activity relationships of a novel series of piperazine derivatives as dual inhibitors of serotonin and noradrenaline reuptake is described. Two compounds possessed comparable in vitro profiles to the dual reuptake inhibitor duloxetine.     

Identification of an S-locus glycoprotein allele introgressed from B. napus ssp. rapifera to B. napus ssp. oleifera.

We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed.     

Quantification of bacterial internalization by host cells using a beta-lactamase reporter strain: Neisseria gonorrhoeae invasion into cervical epithelial cells requires bacterial viability

Neisseria gonorrhoeae can invade into cervical epithelial cells to overcome this host defense barrier. We developed a beta-lactamase reporter system that allowed us to quantify at the single cell level if a host cell internalized a viable or nonviable microorganism. We autodisplayed beta-lactamase on the surface of FA1090 [FA1090Phi(bla-iga')] and demonstrated by confocal fluorescence microscopy and flow cytometry that FA1090Phi(bla-iga') cleaved the beta-lactamase substrate CCF2-AM loaded into host cells only when gonococci were internalized by these host cells. While FA1090Phi(bla-iga') adhered to almost all ME180 cells, viable N. gonorrhoeae were internalized by only a subset of cells during infection. Nonviable gonococci adhered to, but were not internalized by ME180 cells, and failed to recruit F-actin to sites of adherent bacteria. Overall, we show that epithelial cell invasion is a dynamic process that requires viable N. gonorrhoeae. We demonstrate the advantages of the beta-lactamase reporter system over the gentamicin protection assay in quantifying bacterial invasion. The reporter system that we have developed can be adapted to studying the internalization of any bacterial species into any host cell.     

Influence de l'âge des grand-parents sur l'apparition des mâles chez le Rotifère Notommata copeus Ehr.

When parental females (♀♀P = mothers) of the rotifer Notommata copeus are placed in light conditions inducing the appearance of mictic females in their offspring (F₁), the age of the parents of these parental females significantly affects the ratio of mictic females in the F₁ generation.

The preparental females (♀♀PP = grandmothers), the parental females and the F₁ females are isolated in a medium changed at each generation and, in the second experimental series, changed daily: the preparental age effect implicates the transmission of substances on two generations.

This influence of the preparental age is rhythmic: the ratio of mictic females in F₁ related to this age varies in a sinusoidal manner. This influence is endogenous: it persists, always in a sinusoidal form, when the medium in which each grandmother is placed is changed daily.

Furthermore, the net reproduction ratio, Ro, does not vary significantly with the preparental age during these experiments.     

Diet and Physical Activity Behaviors among Americans Trying to Lose Weight: 2000 Behavioral Risk Factor Surveillance System

Objective: To examine the prevalence and correlates of trying to lose weight among U.S. adults, describe weight loss strategies, and assess attainment of recommendations for weight control (eating fewer calories and physical activity). Research Methods and Procedures: This study used the Behavioral Risk Factor Surveillance System, a state‐based telephone survey of adults ≥18 years of age (N = 184, 450) conducted in the 50 states, the District of Columbia, and Puerto Rico in 2000. Results: The prevalence of trying to lose weight was 46% (women) and 33% (men). Women reported trying to lose weight at a lower BMI than did men; 60% of overweight women were trying to lose weight, but men did not reach this level until they were obese. Adults who had a routine physician checkup in the previous year and reported medical advice to lose weight vs. checkup and no medical advice to lose weight had a higher prevalence of trying to lose weight (81% women and 77% men vs. 41% women and 28% men, respectively). The odds of trying to lose weight increased as years of education increased. Among respondents who were trying to lose weight, ～19% of women and 22% of men reported using fewer calories and ≥150 min/wk leisure‐time physical activity. Discussion: A higher percentage of women than men were trying to lose weight; both sexes used similar weight loss strategies. Education and medical advice to lose weight were strongly associated with trying to lose weight. Most persons trying to lose weight were not using minimum recommended weight loss strategies.