Rat Sertoli and spermatogenic cells express a similar gene, and its product is antigenically related to an outer dense fiber-associated protein.

We have previously reported that a heterodimeric protein secreted by rat Sertoli cells is antigenically related to a protein associated with outer dense fibers of the sperm tail. Therefore, we have explored the possibility that Sertoli and spermatogenic cells express a similar gene encoding a homologous protein. A Sertoli cell heterodimeric protein cDNA probe recognizes specific mRNA in pachytene and round spermatids fractionated by centrifugal elutriation; however, this specific mRNA was less prominent than in cultured Sertoli cells. In agreement with these observations, in situ hybridization experiments show that Sertoli cells are predominantly engaged in active heterodimeric protein mRNA synthesis, while meiotic prophase spermatocytes and spermatids also show significant but less abundant specific mRNA. Immunoblotting experiments demonstrate that, while Sertoli cells synthesize a heterodimeric protein consisting of two disulfide-linked components with molecular masses of 45 and 35 kD, both primary spermatocytes and round spermatids synthesize single 30 kD monomers not associated by disulfide linkage but recognized by antisera to Sertoli cell heterodimeric protein. Immunoblotting and immunogold electron microscopic studies show that antisera to Sertoli cell heterodimeric protein recognize a protein associated with outer dense fibers. This immunoreactivity was abolished by a 5-min pronase treatment, without affecting the integrity of outer dense fibers. Results of this study and previous studies demonstrate that both Sertoli and spermatogenic cells express a similar gene and that an antigenically related product encoded by this gene becomes associated with outer dense fibers during their assembly at spermiogenesis.     

Insulin-secreting beta-cells possess specific receptors for interleukin-1 beta

The effect of the cytokine interleukin-1 beta on the insulin secretory responsiveness of single beta-cells (HIT-T15) was investigated. In the short-term, IL-1 beta induced a dosage-dependent stimulation of insulin release. In contrast, in the long-term, IL-1 beta, inhibited both basal and secretagogue-stimulated insulin secretion. We also demonstrate the simultaneous presence of specific high and low affinity binding sites for IL-1 beta on beta-cells. IL-1 beta, which has been implicated in the pathogenesis of insulin-dependent diabetes, may therefore mediate its opposing effects on beta-cells through a specific plasma membrane receptor.     

Glucose tolerance factor: an essential dietary agent

Glucose tolerance factor (GTF), the biologically active form of chromium, is an essential dietary agent that potentiates the action of insulin and thereby functions in regulating carbohydrate metabolism. Dietary trends that show increased consumption of more highly processed foods may be leading to deficiencies of'GTF and chromium in man.     

Aerosols transmit prions to immunocompetent and immunodeficient mice

Prions, the agents causing transmissible spongiform encephalopathies, colonize the brain of hosts after oral, parenteral, intralingual, or even transdermal uptake. However, prions are not generally considered to be airborne. Here we report that inbred and crossbred wild-type mice, as well as tga20 transgenic mice overexpressing PrP(C), efficiently develop scrapie upon exposure to aerosolized prions. NSE-PrP transgenic mice, which express PrP(C) selectively in neurons, were also susceptible to airborne prions. Aerogenic infection occurred also in mice lacking B- and T-lymphocytes, NK-cells, follicular dendritic cells or complement components. Brains of diseased mice contained PrP(Sc) and transmitted scrapie when inoculated into further mice. We conclude that aerogenic exposure to prions is very efficacious and can lead to direct invasion of neural pathways without an obligatory replicative phase in lymphoid organs. This previously unappreciated risk for airborne prion transmission may warrant re-thinking on prion biosafety guidelines in research and diagnostic laboratories.     

The psychoactive substance of cannabis Δ9-tetrahydrocannabinol (THC) negatively regulates CFTR in airway cells

Background

Marijuana consumption is on the rise in the US but the health benefits of cannabis smoking are controversial and the impact of cannabis components on lung homeostasis is not well-understood. Lung function requires a fine regulation of the ion channel CFTR, which is responsible for fluid homeostasis and mucocilliary clearance. The goal of this study was to assess the effect that exposure to Δ9-tetrahydrocannabinol (THC), the psychoactive substance present in marijuana, has on CFTR expression and function.

Detection of asymptomatic herpes simplex virus infections after vaccination.

Twenty-two volunteers seronegative for antibodies to herpes simplex virus (HSV) were enrolled in a trial to determine tolerance and immunogenicity of an HSV-2 glycoprotein subunit vaccine. Vaccine was administered at days 0, 28, and 140, and sera were obtained on days 0, 7, 14, 21, 28, 35, 49, 56, 140, 147, and 365 for determination of HSV neutralizing antibody activity and antibody-dependent cell cytotoxicity (ADCC). Sera were also tested by immunoprecipitation of radiolabeled HSV-2-infected cell proteins and polyacrylamide gel electrophoresis to identify the viral proteins which elicited antibody responses in vaccine recipients. After vaccination two male volunteers presented with atypical first-episode genital herpes: patient 1 with a culture-negative genital lesion at day 53 and patient 3 with urethritis at day 68. Seroconversion to wild-type viral proteins not present in the vaccine was detectable by radioimmunoprecipitation-polyacrylamide gel electrophoresis within 10 days in both patients. Two additional volunteers, one a sex contact of patient 1, seroconverted asymptomatically to nonvaccine proteins during the trial. All four vaccine breakthrough patients were indistinguishable from the other volunteers in the time required to develop neutralizing and ADCC antibodies, in the titer of these antibodies, and the time to seroconversion to gB and gD vaccine proteins. However, only one of the four breakthrough patients had antibodies to g80 (a complex of gC-2 and gE) after vaccination as compared with 15 of the other 18 volunteers (P = 0.05). Neither neutralizing antibody nor ADCC titers consistently identified acquisition of wild-type viral infection; therefore, protein-specific serologies were required to detect wild-type antibodies in these four patients. These data underscore the importance of using serologic assays which will distinguish naturally acquired infection from the immune response to vaccination.     

Anecdotal,Historical and Critical Commentaries on Genetics: Personal Reflections on the Origins and Emergence of Recombinant DNA Technology

The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.THE ever-increasing accessibility of genetic markers is allowing sex-determining regions to be genetically mapped in a growing number of nonmodel organisms. There are several reasons for studying sex determination. In animals, gonadal differences are often accompanied by striking somatic secondary sexual dimorphisms, which are interesting in an evolutionary context (Shine 1989; Badyaev 2002). In plants, females and males often differ in flower morphology and abundance (Dawson and Geber 1998), and, although sex differences are often minor outside the flowers (or inflorescences), they do exist (Dawson and Geber 1998; Eppley and Wenk 2001). The genetic control of these phenotypes is a fundamental biological process, and studying sex determination pathways is important in animal developmental biology (Adams and McLaren 2002; Pinyopich et al. 2003), including genetic pathway evolution (Wilkins 1995; Williams and Carroll 2009).Until recently, sex determination was generally studied by testing for genetic control vs. partial or complete environmental influences. Genetic systems were examined cytologically to determine the level of heteromorphism between the sex chromosomes and to identify whether females or males are heterogametic (see the comprehensive review in Bull 1983). Male heterogametic systems, referred to as XY, were also tested to identify whether the Y chromosome carries a male-determining gene, as in almost all therian mammals and most dioecious plants so far studied, or whether sex is determined through X–autosome balance, as in Drosophila and Caenorhabditis elegans (Haag 2005). For female heterogametic (ZW) species, analogous tests were used to identify how femaleness is determined.Until recently, sex-determining genes and regions could be genetically mapped in only a few model species, but now that molecular genetic markers can be developed in nonmodel species, new information is becoming available about how genetic sex determination (GSD) mechanisms have changed during evolutionary history. It has long been known from genetic mapping in model systems, including mammals, and (more recently) birds, that sex chromosomes often have large nonrecombining regions (Bull 1983; Charlesworth 1991; Charlesworth et al. 2005). However, in other organisms, nonrecombining regions are not always large and may sometimes be absent. The evolution of sexual reproduction and recombination have been the focus of many years of discussion in evolutionary biology (Otto 2009), and studies of sex chromosomes are important for understanding why recombination is often lost, and elucidating the evolutionary consequences of recombination suppression (Charlesworth 1996; Otto and Barton 1997; Barton and Charlesworth 1998). The adaptation of genes on the sex chromosomes is also interesting, because this location affects the outcome of sex-specific selection pressures (Rice 1984; Charlesworth et al. 1987; Vicoso and Charlesworth 2006; Mank 2009a). Finally, the mechanism of sex determination can affect sex ratios (West and Sheldon 2002; Dorken and Pannell 2008; West 2009) and is therefore significant in evolutionary ecology.Sex determination is also relevant in applied biology. In many domesticated animals, one sex may be of greatest economic interest to farmers and breeders. Modern meat production is largely based on males, including industrial production of chicken, cattle, and many fish, whereas females are the sex required for milk (cattle) and egg (chicken) production. Similarly, a few crop plants are dioecious, and, in some of these, the crop is produced by females (e.g., grapes, dates, and papaya), while in other species the sexes differ in characteristics such as fiber or chemical content. Because immature birds, fish, and plants have no obvious phenotypic sex differences, maximizing agricultural returns often requires genetically sexing juveniles. Mapping sex determination is an important first step toward identifying the sex-determining genes or finding other sex-specific markers to develop molecular sexing methods.In this review, we first summarize recent developments in genetic mapping of sex determination, concentrating on nonmodel plants and animals with genetic sex determination. We show how this information can be useful for understanding the evolution of sex determination and sex chromosomes and identify some important unanswered questions.