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Selected AbstractsPERSPECTIVE: MATERNAL KIN GROUPS AND THE ORIGINS OF ASYMMETRIC GENETIC SYSTEMS,GENOMIC IMPRINTING, HAPLODIPLOIDY, AND PARTHENOGENESISEVOLUTION, Issue 4 2006Benjamin B. Normark Abstract The genetic systems of animals and plants are typically eumendelian. That is, an equal complement of autosomes is inherited from each of two parents, and at each locus, each parent's allele is equally likely to be expressed and equally likely to be transmitted. Genetic systems that violate any of these eumendelian symmetries are termed asymmetric and include parent-specific gene expression (PSGE), haplodiploidy, thelytoky, and related systems. Asymmetric genetic systems typically arise in lineages with close associations between kin (gregarious siblings, brooding, or viviparity). To date, different explanatory frameworks have been proposed to account for each of the different asymmetric genetic systems. Haig's kinship theory of genomic imprinting argues that PSGE arises when kinship asymmetries between interacting kin create conflicts between maternally and paternally derived alleles. Greater maternal than paternal relatedness within groups selects for more "abstemious" expression of maternally derived alleles and more "greedy" expression of paternally derived alleles. Here, I argue that this process may also underlie origins of haplodiploidy and many origins of thelytoky. The tendency for paternal alleles to be more "greedy" in maternal kin groups means that maternal-paternal conflict is not a zero-sum game: the maternal optimum will more closely correspond to the optimum for family groups and demes and for associated entities such as symbionts. Often in these circumstances, partial or complete suppression of paternal gene expression will evolve (haplodiploidy, thelytoky), or other features of the life cycle will evolve to minimize the conflict (monogamy, inbreeding). Maternally transmitted cytoplasmic elements and maternally imprinted nuclear alleles have a shared interest in minimizing agonistic interactions between female siblings and may cooperate to exclude the paternal genome. Eusociality is the most dramatic expression of the conflict-reducing effects of haplodiploidy, but its original and more widespread function may be suppression of intrafamilial cannibalism. In rare circumstances in which paternal gene products gain access to maternal physiology via a placenta, PSGE with greedy paternal gene expression can persist (e.g., in mammals). [source] Recognition in action: flipping pyrimidine dimersJOURNAL OF MOLECULAR RECOGNITION, Issue 3 2005David S. Goodsell Abstract DNA bases are normally sheltered within a double helix, but enzymes that modify and repair DNA gain access by flipping individual bases out of the double helix. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mimicry in coral reef fishes: ecological and behavioural responses of a mimic to its modelJOURNAL OF ZOOLOGY, Issue 1 2004Janelle V. Eagle Abstract Mimicry is a widely documented phenomenon in coral reef fishes, but the underlying relationships between mimics and models are poorly understood. Juveniles of the surgeonfish Acanthurus pyroferus mimic the coloration of different pygmy angelfish Centropyge spp. at different locations throughout the geographic range of the surgeonfish, while adopting a common species-specific coloration as adults. This study examines the ecological and behavioural relationships between A pyroferus and one of its models, Centropyge vroliki, in Papua New Guinea. Surgeonfish underwent a transition from the juvenile (mimetic) coloration to the adult (non-mimetic) coloration when they reached the maximum size of the angelfish. As typical of mimic,model relationships, mimic surgeonfish were always less abundant than their model. Spatial variation in the abundance of mimics was correlated with models, while the abundance of adults was not. We show that juvenile surgeonfish gain a foraging advantage by mimicking the angelfish. Mimic surgeonfish were always found within 1,2 m of a similar-sized individual of C. vroliki with which they spent c. 10% of their time in close association. When in association with angelfish, juvenile surgeonfish exhibited an increase of c. 10% in the amount of time spent feeding compared to when they were alone. This foraging benefit seems to be explained by reduced aggression by the territorial damselfish Plectroglyphidon lacrymatus, which dominates the reef crest habitat. While adult A. pyroferus and all other surgeonfish were aggressively displaced from damselfish territories, mimic surgeonfish and their models were attacked less frequently and were not always displaced. Stomach contents analysis showed that the diet of C. vroliki differed substantially from P. lacrymatus, while that of A. pyroferus was more similar to the damselfish. We hypothesize that mimics deceive damselfish as to their diet in order to gain access to food supplies in defended areas. [source] Voicing differences: Indigenous and urban radio in Argentina, Chile, and NigeriaNEW DIRECTIONS FOR YOUTH DEVELOPMENT, Issue 125 2010Luis E. Cárcamo-Huechante Indigenous cultures throughout the Americas and the rest of the world have to deal with problems of cultural assimilation, migration, and dissemination of their populations. Some of them, in countries such as Argentina, Chile, and Nigeria, have developed radio programming to maintain home languages; gain access to health, education, and employment information; greet friends and relatives; and re-create traditional culture under circumstances of modern pressures but also to open up opportunities. This article explores the capacity and awareness of these contributions in a multicultural world. [source] Hypothetical pathophysiology of acute encephalopathy and encephalitis related to influenza virus infection and hypothermia therapyPEDIATRICS INTERNATIONAL, Issue 2 2000Shumpei Yokota AbstractBackground: To establish a treatment strategy for acute encephalopathy and encephalitis associated with influenza virus infection, the pathophysiology of the disease was investigated through manifestations and laboratory findings of patients. Patients and Methods: A child with central nervous system (CNS) complications during the course of influenza virus infection was analyzed in view of immunologic abnormalities. In addition, four children with acute encephalopathy and encephalitis were enrolled in the hypothermia treatment for the purpose of stabilizing the cytokine storm in the CNS. Results: The CNS symptoms preceded the systemic progression to the failure of multiple organs (MOF) and disseminated intravascular coagulopathy (DIC). The mild hypothermia suppressed the brain edema on computed tomography (CT) scanning and protected the brain from the subsequent irreversible neural cell damage. Conclusion: The replicated viruses at the nasopharyngeal epithelium may disrupt the olfactory mucosa and gain access to the brain via the olfactory nerve system. The direct virus,glial cell interaction or viral stimulation of the glial cells induces the production and accumulation of the pro-inflammatory cytokines, especially tumor necrosis factor (TNF)-,, in the CNS. The cytokine storm results in neural cell damage as well as the apoptosis of astrocytes, due to the TNF-,,induced mitochondrial respiratory failure. The disruption of the blood,brain barrier progresses to the systemic cytokine storm, resulting in DIC and MOF. Mild hypothermia appears promising in stabilizing the immune activation and the brain edema to protect the brain from ongoing functional, apoptotic neural and glial damage and the systemic expansion of the cytokine storm. [source] ORIGINAL ARTICLE: The Combination of the Gastrointestinal Integrin (,4,7) and Selectin Ligand Enhances T-Cell Migration to the Reproductive Tract During Infection with Chlamydia trachomatisAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2009Kathleen A. Kelly Problem,Chlamydia trachomatis causes sexually transmitted infection and reproductive dysfunction worldwide. Identifying a population of endocervical T-cells to target in vaccine development is likely to enhance efficacy of a vaccine and reduce reproductive tract dysfunction. Method of study, Endocervical samples were obtained from young women and flow cytometric analysis was used to identify lymphocytes that appeared in the genital tract in response to sexually transmitted bacterial infections caused by C. trachomatis. Results, Increased numbers of ,4,7+CLA+ memory T-cells, a unique T-cell phenotype, were found in the endocervix of human female subjects infected with C. trachomatis. Conclusion A unique population of memory T lymphocytes expressing both ,4,7 and CLA gain access to reproductive tract tissues during a sexually transmitted infection with C. trachomatis and should be considered in development of vaccines against sexually transmitted infections. [source] Use of Foley's catheter to gain access for retroperitoneoscopyANZ JOURNAL OF SURGERY, Issue 11 2004Amar Shah With the increasing popularity of laparoscopic urologic surgery, many different methods have been used to dissect the extraperitoneal space and gain access to the kidney and ureter. We present our initial experience using a Foley catheter to gain retroperitoneal access. This technique was successfully used in 30 children. We have not encountered any major complications and recommend its use in children. [source] Who is My Partner and How Do We Dance?BRITISH JOURNAL OF MANAGEMENT, Issue 3 2010Patenting Speed in US Biotechnology, Technological Collaboration In settings where patents and intellectual property provide a strong regime of appropriability, the race to be the first firm to patent a product or a process is a central feature of competition. In this context, we hypothesize that cooperative arrangements that only gain access to external knowledge contribute less to heterogeneity between firms and have a much weaker influence on patenting than alliances that transfer highly firm-specific knowledge, residing in individual and social relationships. We also hypothesize that cooperations between private firms and public organizations accelerate the rate of patenting to a higher degree than cooperations among private firms. We develop and test these ideas on the population of 839 US biotechnology firms between 1973 and 2003. We discuss the importance of our findings on the debate about the value of knowledge access versus knowledge transfer in strategic alliances. [source] Neuropathogenesis of Naturally Occurring Encephalitis Caused by Listeria monocytogenes in RuminantsBRAIN PATHOLOGY, Issue 2 2010Anna Oevermann DVM, Dipl. Abstract Listeriosis is a serious food-borne disease with increasing frequency in humans and ruminants. Despite the facts that in both hosts, listeriosis can occur as rhombencephalitis and ruminants are a reservoir of Listeria monocytogenes (LM) strains pathogenic for humans, little work has been done on the pathogenesis in ruminants. This study investigates the neuropathogenesis of listeric encephalitis in over 200 natural cases in cattle, sheep and goats by analyzing anatomical distribution, severity, bacterial load and temporal evolution of the lesions. Our results suggest that LM gains access to the brainstem of all three species via axonal migration not only along the trigeminal nerve, but also along other nerves. The ensuing encephalitis does not remain restricted to the brainstem. Rather, LM spreads further from the brainstem into rostral brain regions likely by intracerebral axonal migration. Significant differences in severity of the lesions and bacterial load were found between cattle and small ruminants, which may be caused by species-specific properties of antibacterial immune responses. As histopathological lesions of human rhombencephalitis caused by LM strongly resemble those of ruminants, the disease likely has a similar pathogenesis in both hosts. [source] Internalization of Bordetella pertussis adenylate cyclase,haemolysin into endocytic vesicles contributes to macrophage cytotoxicityCELLULAR MICROBIOLOGY, Issue 11 2001Nadia Khelef Bordetella pertussis adenylate cyclase,haemolysin is a critical virulence factor in the murine model of intranasal infection, where it is required for several pathological effects, including macrophage apoptosis. Based on biochemical and immunological properties, it was proposed that the toxin was delivered directly to the cytoplasm of eukaryotic cells without trafficking through the endocytic pathway. In the present study, we analysed the cellular distribution of the adenylate cyclase,haemolysin during intoxication of macrophages. We showed that, shortly after its initial binding to the plasma membrane of macrophages, the toxin gains access to intracellular compartments that become progressively positive for the endosomal marker transferrin, but not for the lysosomal membrane protein CD107a/Lamp1. Importantly, the vesicular trafficking of the adenylate cyclase,haemolysin appears to be required for its ability to induce macrophage death. Inhibitors of actin polymerization and of macropinocytosis, as well as depletion of plasma membrane cholesterol and disruption of the Golgi network, reduce the toxin's ability to kill macrophages. Altogether, these results suggest that internalization of the adenylate cyclase,haemolysin into endocytic vesicles, at least partly through macropinocytosis, contributes to cytotoxicity. [source] | |||||||||||||