Role of pleated septate junctions in the epithelium of miracidia of Schistosoma mansoni during transformation to sporocysts in vitro

The surfaces of miracidia of Schistosoma mansoni were examined ultrastructurally during in vitro transformation to sporocysts. Before transformation, the surface was composed of ciliated epithelial plates (EP) that were set into a reticulum of narrow syncytial ridges (SR). The EP were attached to SR by extensive pleated septate junctions that had 18-24 strands of intramembrane particles (IMP) on the protoplasmic faces and complementary pits on the ectoplasmic faces. These junctions also appeared to separate the EP plasma membrane into apical and basolateral domains with a larger number of IMPs on the latter. Transformation was induced by placing the miracidia in salt containing medium which also halted ciliary beating. In 2-5 hr, the SR expanded until they formed a syncytium covering the parasite surface, while the EP retracted and rounded up. During this time, the EP and SR were held in contact with one another by the septate junctions which became progressively convoluted. Subsequently, the EP detached from the parasite. When transforming miracidia were returned to fresh water, the cilia resumed beating and the EP detached from the parasite surface and exposed the underlying basement membrane. Those EP that remained attached were connected only by septate junctions to the expanded SR. These studies demonstrate that the formation of the syncytium occurs gradually with contact maintained between EP and SR via the septate junctions. Further, the septate junctions are similar to occluding junctions in mammalian epithelia since they segregate the plasma membrane of the EP and they have an adhesive function.     

Adaptive Immunity Alters Distinct Host Feeding Pathways during Nematode Induced Inflammation,a Novel Mechanism in Parasite Expulsion

Gastrointestinal infection is often associated with hypophagia and weight loss; however, the precise mechanisms governing these responses remain poorly defined. Furthermore, the possibility that alterations in feeding during infection may be beneficial to the host requires further study. We used the nematode Trichinella spiralis, which transiently inhabits the small intestine before migrating to skeletal muscle, as a biphasic model of infection to determine the cellular and molecular pathways controlling feeding during enteric and peripheral inflammation. Through the infection of genetically modified mice lacking cholecystokinin, Tumor necrosis factor α receptors and T and B-cells, we observed a biphasic hypophagic response to infection resulting from two separate immune-driven mechanisms. The enteroendocrine I-cell derived hormone cholecystokinin is an essential mediator of initial hypophagia and is induced by CD4+ T-cells during enteritis. In contrast, the second hypophagic response is extra-intestinal and due to the anorectic effects of TNFα during peripheral infection of the muscle. Moreover, via maintaining naive levels of the adipose secreted hormone leptin throughout infection we demonstrate a novel feedback loop in the immunoendocrine axis. Immune driven I-cell hyperplasia and resultant weight loss leads to a reduction in the inflammatory adipokine leptin, which in turn heightens protective immunity during infection. These results characterize specific immune mediated mechanisms which reduce feeding during intestinal or peripheral inflammation. Importantly, the molecular mediators of each phase are entirely separate. The data also introduce the first evidence that I-cell hyperplasia is an adaptively driven immune response that directly impinges on the outcome to infection.     

Immunochemical evidence for the light-regulated modulation of phosphatidylinositol-4,5-bisphosphate in rat photoreceptor cells

Immunocytochemical localization of phosphatidylinositol-4,5-bisphosphate (PIP2) in the rat rod photoreceptor outer segments (OS) was investigated with rabbit antiPIP2 antibodies. The OS of the light-adapted rat eye showed little or no staining, whereas the OS of the dark-adapted eye were intensely stained for PIP2. The immunoreactivity of photoreceptor PIP2 in the eye exposed to a brief flash of light was markedly reduced. However, subsequent dark-adaptation of the flash-bleached eye resulted in a rapid recovery of PIP2 immunoreactivity; dark-adaptation for 5 min was sufficient for recovery to the fully dark-adapted level. In dark-adapted eyes exposed to graded light intensities, the PIP2 immunostaining varied with light levels and was correlated with unbleached rhodopsin concentrations. These results suggest that PIP2 in the rat photoreceptor cells is rapidly hydrolyzed upon light exposure and rapidly synthesized in the dark and that the decrease of PIP2 level is triggered by photic bleaching of rhodopsin.     

Self-assembling diblock copolymers of poly[N-(2-hydroxypropyl)methacrylamide] and a beta-sheet peptide

The self-assembly of hybrid diblock copolymers composed of poly(HPMA) and beta-sheet peptide P11 (CH(3)CO-QQRFQWQFEQQ-NH(2)) blocks was investigated. Copolymers were synthesized via thiol-maleimide coupling reaction, by conjugation of semitelechelic poly(HPMA)-SH with maleimide-modified beta-sheet peptide. As expected, CD and CR binding studies showed that the peptide block imposed its beta-sheet structural arrangement on the structure of diblock copolymers. TEM and AFM proved that peptide and these copolymers had the ability to self-assemble into fibrils.     

Invasion of epithelial cells by <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> is independent of caveolae

Caveolae are 25–100 nm flask-like membrane structures enriched in cholesterol and glycosphingolipids. Researchers have proposed that Campylobacter jejuni require caveolae for cell invasion based on the finding that treatment of cells with the cholesterol-depleting compounds filipin III or methyl-β-cyclodextrin (MβCD) block bacterial internalization in a dose-dependent manner. The purpose of this study was to determine the role of caveolae and caveolin-1, a principal component of caveolae, in C. jejuni internalization. Consistent with previous work, we found that the treatment of HeLa cells with MβCD inhibited C. jejuni internalization. However, we also found that the treatment of HeLa cells with caveolin-1 siRNA, which resulted in greater than a 90% knockdown in caveolin-1 protein levels, had no effect on C. jejuni internalization. Based on this observation we performed a series of experiments that demonstrate that MβCD acts broadly, disrupting host cell lipid rafts and C. jejuni- induced cell signaling. More specifically, we found that MβCD inhibits the cellular events necessary for C. jejuni internalization, including membrane ruffling and Rac1 GTPase activation. We also demonstrate that MβCD disrupted the association of the β₁ integrin and EGF receptor, which are required for the maximal invasion of epithelial cells. In agreement with these findings, C. jejuni were able to invade human Caco-2 cells, which are devoid of caveolae, at a level equal to that of HeLa cells. Taken together, the results of our study demonstrate that C. jejuni internalization occurs in a caveolae-independent manner.     

Genetic variation in C57BL/6 ES cell lines and genetic instability in the Bruce4 C57BL/6 ES cell line

Genetically modified mouse strains derived from embryonic stem (ES) cells are powerful tools for gene function analysis. ES cells from the C57BL/6 mouse strain are not widely used to generate mouse models despite the advantage of a defined genetic background. We assessed genetic variation in six such ES cell lines with 275 SSLP markers. Compared to C57BL/6, Bruce4 differed at 34 SSLP markers and had significant heterozygosity on three chromosomes. BL/6#3 and Dale1 ES cell lines differed at only 3 SSLP makers. The C2 and WB6d ES cell lines differed at 6 SSLP markers. It is important to compare the efficiency of producing mouse models with available C57BL/6 ES cells relative to standard 129 mouse strain ES cells. We assessed genetic stability (the tendency of cells to become aneuploid) in 110 gene-targeted ES cell clones from the most widely used C57BL/6 ES cell line, Bruce4, and 710 targeted 129 ES cell clones. Bruce4 clones were more likely to be aneuploid and unsuitable for ES cell-mouse chimera production. Despite their tendency to aneuploidy and consequent inefficiency, use of Bruce4 ES cells can be valuable for models requiring behavioral studies and other mouse models that benefit from a defined C57BL/6 background. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Relating Ozone Uptake in Forest Trees to Risk Assessment

This paper reviews the importance of ozone uptake through plant stomata in understanding plant response to ozone and discusses challenges in quantifying ozone uptake in forest trees. Uncertainties in spatial and temporal scaling of ozone uptake from the leaf to the landscape level, insufficient monitoring of ozone in forested areas, and tremendous variability in the composition and structure of forest ecosystems of the United States prevent the current use of ozone uptake in large-scale risk assessments and regulatory decisions.     

Adolescent Sexual and Reproductive Health Services and Implications for the Provision of Voluntary Medical Male Circumcision: Results of a Systematic Literature Review

Background

Voluntary medical male circumcision (VMMC) is a critical HIV prevention tool. Since 2007, sub-Saharan African countries with the highest prevalence of HIV have been mobilizing resources to make VMMC available. While implementers initially targeted adult men, demand has been highest for boys under age 18. It is important to understand how male adolescents can best be served by quality VMMC services.

Methods and Findings

A systematic literature review was performed to synthesize the evidence on best practices in adolescent health service delivery specific to males in sub-Saharan Africa. PubMed, Scopus, and JSTOR databases were searched for literature published between January 1990 and March 2014. The review revealed a general absence of health services addressing the specific needs of male adolescents, resulting in knowledge gaps that could diminish the benefits of VMMC programming for this population. Articles focused specifically on VMMC contained little information on the adolescent subgroup. The review revealed barriers to and gaps in sexual and reproductive health and VMMC service provision to adolescents, including structural factors, imposed feelings of shame, endorsement of traditional gender roles, negative interactions with providers, violations of privacy, fear of pain associated with the VMMC procedure, and a desire for elements of traditional non-medical circumcision methods to be integrated into medical procedures. Factors linked to effective adolescent-focused services included the engagement of parents and the community, an adolescent-friendly service environment, and VMMC counseling messages sufficiently understood by young males.

Conclusions

VMMC presents an opportune time for early involvement of male adolescents in HIV prevention and sexual and reproductive health programming. However, more research is needed to determine how to align VMMC services with the unique needs of this population.