The polarity protein Inturned links NPHP4 to Daam1 to control the subapical actin network in multiciliated cells

Motile cilia polarization requires intracellular anchorage to the cytoskeleton; however, the molecular machinery that supports this process remains elusive. We report that Inturned plays a central role in coordinating the interaction between cilia-associated proteins and actin-nucleation factors. We observed that knockdown of nphp4 in multiciliated cells of the Xenopus laevis epidermis compromised ciliogenesis and directional fluid flow. Depletion of nphp4 disrupted the subapical actin layer. Comparison to the structural defects caused by inturned depletion revealed striking similarities. Furthermore, coimmunoprecipitation assays demonstrated that the two proteins interact with each other and that Inturned mediates the formation of ternary protein complexes between NPHP4 and DAAM1. Knockdown of daam1, but not formin-2, resulted in similar disruption of the subapical actin web, whereas nphp4 depletion prevented the association of Inturned with the basal bodies. Thus, Inturned appears to function as an adaptor protein that couples cilia-associated molecules to actin-modifying proteins to rearrange the local actin cytoskeleton.     

Vibrio coralliilyticus Strain OCN008 Is an Etiological Agent of Acute Montipora White Syndrome

Identification of a pathogen is a critical first step in the epidemiology and subsequent management of a disease. A limited number of pathogens have been identified for diseases contributing to the global decline of coral populations. Here we describe Vibrio coralliilyticus strain OCN008, which induces acute Montipora white syndrome (aMWS), a tissue loss disease responsible for substantial mortality of the coral Montipora capitata in Kāne‘ohe Bay, Hawai‘i. OCN008 was grown in pure culture, recreated signs of disease in experimentally infected corals, and could be recovered after infection. In addition, strains similar to OCN008 were isolated from diseased coral from the field but not from healthy M. capitata. OCN008 repeatedly induced the loss of healthy M. capitata tissue from fragments under laboratory conditions with a minimum infectious dose of between 10⁷ and 10⁸ CFU/ml of water. In contrast, Porites compressa was not infected by OCN008, indicating the host specificity of the pathogen. A decrease in water temperature from 27 to 23°C affected the time to disease onset, but the risk of infection was not significantly reduced. Temperature-dependent bleaching, which has been observed with the V. coralliilyticus type strain BAA-450, was not observed during infection with OCN008. A comparison of the OCN008 genome to the genomes of pathogenic V. coralliilyticus strains BAA-450 and P1 revealed similar virulence-associated genes and quorum-sensing systems. Despite this genetic similarity, infections of M. capitata by OCN008 do not follow the paradigm for V. coralliilyticus infections established by the type strain.     

Müller Glia as an Active Compartment Modulating Nervous Activity in the Vertebrate Retina: Neurotransmitters and Trophic Factors

Müller cells represent the main type of glia present in the retina interacting with most, if not all neurons in this tissue. Müller cells have been claimed to function as optic fibers in the retina delivering light to photoreceptors with minimal distortion and low loss [Franze et al (2007) Proc Natl Acad Sci 104:8287–8292]. Most of the mediators found in the brain are also detected in the retinal tissue, and glia cells are active players in the synthesis, release, signaling and uptake of major mediators of synaptic function. Müller glia trophic factors may regulate many different aspects of neuronal circuitry during synaptogenesis, differentiation, neuroprotection and survival of photoreceptors, Retinal Ganglion Cells (RGCs) and other targets in the retina. Here we review the role of several transmitters and trophic factors that participate in the neuron-glia loop in the retina. Special issue article in honor of Dr. Ricardo Tapia.     

Impact of Plant Functional Group, Plant Species, and Sampling Time on the Composition of nirK-Type Denitrifier Communities in Soil

We studied the influence of eight nonleguminous grassland plant species belonging to two functional groups (grasses and forbs) on the composition of soil denitrifier communities in experimental microcosms over two consecutive years. Denitrifier community composition was analyzed by terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified nirK gene fragments coding for the copper-containing nitrite reductase. The impact of experimental factors (plant functional group, plant species, sampling time, and interactions between them) on the structure of soil denitrifier communities (i.e., T-RFLP patterns) was analyzed by canonical correspondence analysis. While the functional group of a plant did not affect nirK-type denitrifier communities, plant species identity did influence their composition. This effect changed with sampling time, indicating community changes due to seasonal conditions and a development of the plants in the microcosms. Differences in total soil nitrogen and carbon, soil pH, and root biomass were observed at the end of the experiment. However, statistical analysis revealed that the plants affected the nirK-type denitrifier community composition directly, e.g., through root exudates. Assignment of abundant T-RFs to cloned nirK sequences from the soil and subsequent phylogenetic analysis indicated a dominance of yet-unknown nirK genotypes and of genes related to nirK from denitrifiers of the order Rhizobiales. In conclusion, individual species of nonleguminous plants directly influenced the composition of denitrifier communities in soil, but environmental conditions had additional significant effects.     

Tuberculosis Treatment in HIV Infected Ugandans with CD4 Counts >350 Cells/mm3 Reduces Immune Activation with No Effect on HIV Load or CD4 Count

Background

Both HIV and TB cause a state of heightened immune activation. Immune activation in HIV is associated with progression to AIDS. Prior studies, focusing on persons with advanced HIV, have shown no decline in markers of cellular activation in response to TB therapy alone.

Methodology

This prospective cohort study, composed of participants within a larger phase 3 open-label randomized controlled clinical trial, measured the impact of TB treatment on immune activation in persons with non-advanced HIV infection (CD4>350 cells/mm³) and pulmonary TB. HIV load, CD4 count, and markers of immune activation (CD38 and HLA-DR on CD4 and CD8 T cells) were measured prior to starting, during, and for 6 months after completion of standard 6 month anti-tuberculosis (TB) therapy in 38 HIV infected Ugandans with smear and culture confirmed pulmonary TB.

Results

Expression of CD38, and co-expression of CD38 and HLA-DR, on CD8 cells declined significantly within 3 months of starting standard TB therapy in the absence of anti-retroviral therapy, and remained suppressed for 6 months after completion of therapy. In contrast, HIV load and CD4 count remained unchanged throughout the study period.

Conclusion

TB therapy leads to measurable decreases in immune activation in persons with HIV/TB co-infection and CD4 counts >350 cells/mm³.     

Proteome analysis of rat liver mitochondria reveals a possible compensatory response to endotoxic shock

Organ failure induced by endotoxic shock has recently been associated with affected mitochondrial function. In this study, effects of in vivo lipopolysaccharide-challenge on protein patterns of rat liver mitochondria in treated animals versus controls were studied by two-dimensional electrophoresis (differential image gel electrophoresis). Significant upregulation was found for ATP-synthase alpha chain and superoxide dismutase [Mn]. Our data suggest that endotoxic shock mediated changes in the mitochondrial proteome contribute to a compensatory reaction (adaptation to endotoxic shock) rather than to a mechanism of cell damage.