Gap junction structures: Analysis of the x-ray diffraction data

Models for the spatial distribution of protein, lipid and water in gap junction structures have been constructed from the results of the analysis of X-ray diffraction data described here and the electron microscope and chemical data presented in the preceding paper (Caspar, D. L. D., D. A. Goodenough, L. Makowski, and W.C. Phillips. 1977. 74:605-628). The continuous intensity distribution on the meridian of the X-ray diffraction pattern was measured, and corrected for the effects of the partially ordered stacking and partial orientation of the junctions in the X-ray specimens. The electron density distribution in the direction perpendicular to the plane of the junction was calculated from the meridional intensity data. Determination of the interference function for the stacking of the junctions improved the accuracy of the electron density profile. The pair-correlation function, which provides information about the packing of junctions in the specimen, was calculated from the interference function. The intensities of the hexagonal lattice reflections on the equator of the X-ray pattern were used in coordination with the electron microscope data to calculate to the two-dimensional electron density projection onto the plane of the membrane. Differences in the structure of the connexons as seen in the meridional profile and equatorial projections were shown to be correlated to changes in lattice constant. The parts of the junction structure which are variable have been distinguished from the invariant parts by comparison of the X-ray data from different specimens. The combination of these results with electron microscope and chemical data provides low resolution three- dimensional representations of the structures of gap junctions.     

Rift Valley Fever Risk Map Model and Seroprevalence in Selected Wild Ungulates and Camels from Kenya

Since the first isolation of Rift Valley fever virus (RVFV) in the 1930s, there have been multiple epizootics and epidemics in animals and humans in sub-Saharan Africa. Prospective climate-based models have recently been developed that flag areas at risk of RVFV transmission in endemic regions based on key environmental indicators that precede Rift Valley fever (RVF) epizootics and epidemics. Although the timing and locations of human case data from the 2006–2007 RVF outbreak in Kenya have been compared to risk zones flagged by the model, seroprevalence of RVF antibodies in wildlife has not yet been analyzed in light of temporal and spatial predictions of RVF activity. Primarily wild ungulate serum samples from periods before, during, and after the 2006–2007 RVF epizootic were analyzed for the presence of RVFV IgM and/or IgG antibody. Results show an increase in RVF seropositivity from samples collected in 2007 (31.8%), compared to antibody prevalence observed from 2000–2006 (3.3%). After the epizootic, average RVF seropositivity diminished to 5% in samples collected from 2008–2009. Overlaying maps of modeled RVF risk assessments with sampling locations indicated positive RVF serology in several species of wild ungulate in or near areas flagged as being at risk for RVF. Our results establish the need to continue and expand sero-surveillance of wildlife species Kenya and elsewhere in the Horn of Africa to further calibrate and improve the RVF risk model, and better understand the dynamics of RVFV transmission.     

Heavy Rainfall,Sewer Overflows,and Salmonellosis in Black Skimmers (Rynchops niger)

EcoHealth - Extreme weather events, particularly heavy rainfall, are occurring at greater frequency with climate change. Although adverse human health effects from heavy rainfall are often...     

A sequence-specific protease cleaves a maternal, cortical protein during early embryogenesis in Sciara coprophila (Diptera)

One of the first events of egg activation in Sciara coprophila (Diptera) is the disappearance of an abundant maternal 38-kDa protein (p38) and the simultaneous emergence of an abundant 35-kDa protein (p35). Western blotting experiments using monoclonal antibodies directed against p38 reveal that p38 and p35 are serologically related and indicate that maternal p38 is transformed into p35 during early development. This transition is possibly accompanied by a conformational change in the part of the protein that is common to both protein species. The processing of p38 to p35 can be mimicked by trypsin treatment in vitro, suggesting that a trypsin-like protease is responsible for this conversion in vivo. Immunostaining indicates that the p38 class of antigens is evently distributed in the periplasm of early cleavage embryos. After the arrival of nuclei in the periplasm, the antigens become associated with the infolding cellular membranes. A similar membrane association of actin can be observed with anti-actin antibodies. Nevertheless, p38 and actin are clearly distinct from each other. We presume that p38 is a product of a maternal effect gene necessary for early dipteran development.     

Bioinspirations: cell-inspired small-scale systems for enabling studies in experimental biomechanics

Biomechanical forces govern the behaviors of organisms and their environment and examining these behaviors to understand the underlying phenomena is an important challenge. One experimental approach for probing these interactions between organisms and their biomechanical environment uses biologically-inspired, artificial surrogates that reproduce organic mechanical systems. For the case of complex, multicellular organisms, robot surrogates have been particularly effective, such as in the analysis of the fins of fish and insects' wings. This biologically-inspired approach is also exciting when examining cell-scale responses as multicellular organisms' behavior is directly influenced by the integrated interactions of smaller-scale components (i.e., cells). In this review, we introduce the burgeoning field of engineering of artificial cells, which focuses on developing cell-scale entities replicating cellular behaviors. We describe both a bottom-up approach to constructing artificial cells, using molecular components to directly assemble artificial cells, as well as a top-down approach, in which living cells are encapsulated in a single entity whose behavior is determined by its constituent members. In particular, we discuss the potential role of these artificial cells as implantable controllers, designed to alter the mechanical behavior of a host organism. Eventually, artificial cells designed to function as small-scale controllers may help alter organisms' phenotypes.     

Artificial cells: building bioinspired systems using small-scale biology

Artificial cells have generated much interest since the concept was introduced by Aleksandr Oparin in the 1920s, and they have had an impact on the pharmaceutical and biotechnology industry in various areas, including potential therapeutic applications. Here, we discuss the development of small-scale, bio-inspired artificial cell components that recreate the function of key cellular and physiological systems. We describe artificial cells, selected current applications and how small-scale biology could be used to provide what might be a next-generation approach in this area. We believe that this type of work is in its infancy and that exploiting small-scale biological inspiration in the field of artificial cells has great potential for successes in the future.     

The role of nitric oxide in cancer

Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including va-sodilatation, neurotransmission and macrophage-mediated immunity. The family of nitric oxide synthases (NOS) comprises inducible NOS (iNOS), endothelial NOS (eNOS), and neuronal NOS (nNOS). Interestingly, various studies have shown that all three isoforms can be involved in promoting or inhibiting the etiology of cancer. NOS activity has been detected in tumour cells of various histogenetic origins and has been associated with tumour grade, proliferation rate and expression of important signaling components associated with cancer development such as the oestrogen receptor. It appears that high levels of NOS expression (for example, generated by activated macrophages) may be cytostatic or cytotoxic for tumor cells, whereas low level activity can have the opposite effect and promote tumour growth. Paradoxically therefore, NO (and related reactive nitrogen species) may have both genotoxic and angiogenic pro