Mutational Analysis of Substrate Inhibition in Tyrosine Hydroxylase

Abstract: Substrate inhibition in tyrosine hydroxylase (TH) was analyzed by deletion mutagenesis. The deletion mutant TH 156/456 was the smallest section of TH to retain substrate inhibition. The TH 156/456 was monomeric, and so multimer formation does not play a role in substrate inhibition in TH. Further deletion at the N terminus to residue 169 produced a TH molecule with no substrate inhibition but high activity. A mutagenic scan of this region showed that mutations at Trp¹⁶⁶ were responsible for this phenotype. A screen of a library of TH molecules containing random mutations identified three other mutants that had lost substrate inhibition but retained high activity. The results in this report are consistent with a model in which substrate inhibition acts through an allosteric mechanism.     

Experimental evolution of infectious behaviour in a facultative ectoparasite

Parasitic lifestyles have evolved many times in animals, but how such life‐history strategies evolved from free‐living ancestors remains a great puzzle. Transitional symbiotic strategies, such as facultative parasitism, are hypothesized evolutionary stepping stones towards obligate parasitism. However, to consider this hypothesis, heritable genetic variation in infectious behaviour of transitional symbiotic strategies must exist. In this study, we experimentally evolved infectivity and estimated the additive genetic variation in a facultative parasite. We performed artificial selection experiments in which we selected for either increased or decreased propensity to infect in a facultatively parasitic mite (Macrocheles muscaedomesticae). Here, infectiousness was expressed in terms of mite attachment to a host (Drosophila hydei) and modelled as a threshold trait. Mites responded positively to selection for increased infectivity; realized heritability of infectious behaviour was significantly different from zero and estimated to be 16.6% (±4.4% SE). Further, infection prevalence was monitored for 20 generations post‐selection. Selected lines continued to display relatively high levels of infection, demonstrating a degree of genetic stability in infectiousness. Our study is the first to provide an estimate of heritability and additive genetic variation for infectious behaviour in a facultative parasite, which suggests natural selection can act upon facultative strategies with important implications for the evolution of parasitism.     

Competition matters: Determining the drivers of land snail community assembly among limestone karst areas in northern Vietnam

The insular limestone karsts of northern Vietnam harbor a very rich biodiversity. Many taxa are strongly associated with these environments, and individual species communities can differ considerably among karst areas. The exact processes that have shaped the biotic composition of these habitats, however, remain largely unknown. In this study, the role of two major processes for the assembly of snail communities on limestone karsts was investigated, interspecific competition and filtering of taxa due to geographical factors. Communities of operculate land snails of the genus Cyclophorus were studied using the dry and fluid‐preserved specimen collections of the Natural History Museum, London. Phylogenetic distances (based on a Bayesian analysis using DNA sequence data) and shell characters (based on 200 semilandmarks) were used as proxies for ecological similarity and were analyzed to reveal patterns of overdispersion (indicating competition) or clustering (indicating filtering) in observed communities compared to random communities. Among the seven studied karst areas, a total of 15 Cyclophorus lineages were found. Unique communities were present in each area. The analyses revealed phylogenetic overdispersion in six and morphological overdispersion in four of seven karst areas. The pattern of frequent phylogenetic overdispersion indicated that competition among lineages is the major process shaping the Cyclophorus communities studied. The Coastal Area, which was phylogenetically overdispersed, showed a clear morphological clustering, which could have been caused by similar ecological adaptations among taxa in this environment. Only the community in the Cuc Phuong Area showed a pattern of phylogenetic clustering, which was partly caused by an absence of a certain, phylogenetically very distinct group in this region. Filtering due to geographical factors could have been involved here. This study shows how museum collections can be used to examine community assembly and contributes to the understanding of the processes that have shaped karst communities in Vietnam.     

Pathogenesis of biliary fibrosis

Chronic cholestatic liver diseases such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are associated with active hepatic fibrogenesis, and, ultimately, to the development of cirrhosis. However, the precise relationship between cholestasis, in its broad meaning, and liver tissue fibrosis is still poorly defined. Fibrogenesis is currently viewed as a dynamic process that appears strictly related to the extent and duration of parenchymal injury. This relationship is clearly evident in the presence of reiterative hepatocellular necrosis due to viral infection or alcohol abuse. It appears that “pure” intralobular intrahepatic cholestasis secondary to biliary secretory failure of the hepatocyte, in absence of hepatocellular damage, lobular inflammation and bile duct damage and/or proliferation, is not associated with marked and/or progressive liver tissue fibrosis. In contrast, marked and progressive liver tissue fibrosis always follows liver diseases characterized by chronic inflammatory bile duct damage as seen in PBC and PSC or chronic mechanical obstruction of the biliary tree. Overall, the fibrogenic process in these clinical conditions appears to be related to a more complex interaction between immune/inflammatory mechanisms, cytokine networks and the derangement of the homeostasis between epithelial and mesenchymal cells. The elucidation of these mechanisms is indeed crucial for the identification of potential diagnostic and therapeutic targets.     

The role of photosynthesis and respiration in the light-induced recovery of "giant" cells of the Emerson strain of Chlorella

The light-induced recovery of cell division and chloroplastdevelopment in "giant", "bleached" cells of the Emerson strainof Chlorella is unaffected by treatments (atrazine. CMU, incubationin a CO₂-free atmosphere) which interfere with photosynthesis.Anaerobic conditions or the presence of respiratory inhibitors(DNP, KCN, NaN₃) markedly suppress recovery. Recovery is accompaniedby a mobilization of the reserve starch which follows a linearcourse over the first 9 hr. Chloramphenicol (50 µg/ml),which inhibits chlorophyll synthesis and the development ofa photosynthetic capacity, is without effect on the early rateof starch mobilization. Evidence is presented that the contributionof photosynthesis towards recovery is only significant whenthe reserve starch has been depleted. Recovery does not requirecontinuous light; the critical light-stimulated processes apparentlytaking place during the first 9 hr. The possible nature of thelight stimulation of recovery is discussed. (Received June 18, 1973; )     

Protein tyrosine phosphatase 1B inhibitors isolated from Morus bombycis

Bioassay-guided fractionation of the chloroform-soluble fraction of Morus bombycis, using an in vitro PTP1B inhibitory assay led to the identification of three 2-arylbenzofurans, albafuran A (1), mulberrofuran W (2) and mulberrofuran D (6), along with three chalcone-derived Diels–Alder products, kuwanon J (3), kuwanon R (4), and kuwanon V (5). Compounds 1–6 showed remarkable inhibitory activity against PTP1B with IC₅₀ values ranging from 2.7 to 13.8 μM. Inhibition kinetics were analyzed by Lineweaver–Burk plots, which suggested that compounds 1–6 inhibited PTP1B in a mixed-type manner. The present results indicate that the respective lipophilic and hydroxyl groups of 2-arylbenzofurans and chalcone-derived Diels–Alder products play an important role in inhibition of PTP1B.     

Complete genome sequence of Pirellula staleyi type strain (ATCC 27377)

Pirellula staleyi Schlesner and Hirsch 1987 is the type species of the genus Pirellula of the family Planctomycetaceae. Members of this pear- or teardrop-shaped bacterium show a clearly visible pointed attachment pole and can be distinguished from other Planctomycetes by a lack of true stalks. Strains closely related to the species have been isolated from fresh and brackish water, as well as from hypersaline lakes. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is the first completed genome sequence of the order Planctomyces and only the second sequence from the phylum Planctobacteria/Planctomycetes. The 6,196,199 bp long genome with its 4773 protein-coding and 49 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

2009 Society for Medical Anthropology Conference: Training,Communication, and Competence: The Making of Health Care Professionals

The role of medical anthropology in tackling the problems and challenges at the intersections of public health, medicine, and technology was addressed during the 2009 Society for Medical Anthropology Conference at Yale University in an interdisciplinary panel session entitled Training, Communication, and Competence: The Making of Health Care Professionals.The discipline of medical anthropology is not very formalized in the health setting. Although medical anthropologists work across a number of health organizations, including schools of public health, at the Centers for Disease Control (CDC), and at non-governmental organizations (NGOs), there is an emerging demand for an influential applied medical anthropology that contributes both pragmatically and theoretically to the health care field.The role of anthropology at the intersections of public health, medicine, and technology was addressed during the 2009 Society for Medical Anthropology Conference at Yale University in September. In a conference session entitled Training, Communication, and Competence: The Making of Health Care Professionals, health professional career issues, including training and education, medical entrepreneurship, and the maintenance of clinical relationships with patients were examined. The presentations encompassed macro approaches to institutional reform in training, education, and health care delivery, as well as micro studies of practitioner-patient interaction. Seemingly disparate methodological, disciplinary, and theoretical orientations were united to assess the increasing relevance of medically oriented anthropology in addressing the challenges of health care delivery, health education, and training.Margaret Bentley, a professor of public health at the University of North Carolina, Chapel Hill, spoke about the increasing “epidemic of global health” in universities, noting a doubling of global health majors within the past three years. Despite this expansion of the field, a common discipline of global health continues to be developed. In September, the Association of Schools of Public Health (ASPH) and the University of Minnesota hosted a Global Health Core Competency Development Consensus Conference with the initiative to explore “workforce needs, practice settings, and to identify core constructs, competency domains, and a preliminary global health competency model”¹. Given the current variability in training, Bentley believes medical anthropology is uniquely suited to inform training in global health because of its offerings in the way of interdisciplinary methods and team-based applied field experience.Anthropologists Carl Kendall of Tulane University and Laetitia Atlani of Université de Paris X Nanterre have seen medical anthropologists examine models of health strictly within a clinical experience. Understanding of the social determinants of epidemiology, methodological issues of population health, and survey research is crucial. However, training individuals through a more formalized program (currently in development in Europe) will allow anthropologists to better understand context, explain complex models, humanize aggregate statistics, and articulate methods of the multidimensional “social field” of health outside of the clinical experience.The social field of health, however, as Robert Like of the University of Medicine and Dentistry of New Jersey explained, shares an uncomfortable interface with clinical medicine. Recent efforts by the New Jersey Board of Examiners to incorporate cultural competency legislation have been robustly criticized. Evaluations of six-hour training sessions on cultural competency training have revealed health professionals’ frustration with the health care system’s inability to deal with “culturally different” individuals. In fact, the majority of health professionals who were required to complete the training believe cultural competency to be an area of study that is a “waste of time.”This opposition to cross-cultural education and the value of “cultural competence” training also has been a topic of great debate among anthropologists and health researchers. Despite the ubiquitous use of the term among research and health professionals, cultural competency is a term that cannot be defined precisely enough to operationalize.In “Anthropology in the Clinic: The Problem of Cultural Competency and How to Fix It,” Arthur Kleinman and Peter Benson asserted that the static notion of culture in the medical field “suggests that a culture can be reduced to a technical skill for which clinicians can be trained to develop expertise” [1]. T.S. Harvey, a linguistic and medical anthropologist at the University of California, Riverside, expounded on Kleinman’s opposition to competence as an acquired “technical skill” [1] and suggested reconceptualizing the approach to competence as communication. Although Kleinman’s explanatory models approach [2] provides a health care professional with what to ask the patient, Harvey pulls from Dell Hymes’ communicative competence [3] to understand how to ask it. Harvey recommended viewing competence as a “sociolinguistic acquisition … like a foreign language” where competencies are rule-governed and communication and speech events are formulaic.Harvey also noted that the “onus of cultural competency” is too often placed on the practitioner. Inevitably, there is an asymmetry in every clinical encounter, whereby the “would-be patient” is perpetually considered the “passive receptor.” Patients also share a stake in their health and, as such, should be taught communicative competence as well.Harvey also noted that the “onus of cultural competency” is too often placed on the practitioner. Inevitably, there is an asymmetry in every clinical encounter, whereby the “would-be patient” is perpetually considered the “passive receptor.” Patients also share a stake in their health and, as such, should be taught communicative competence as well.The role of the patient is made ever more complex by the power relationship that exists in the patient-provider context. Through ethnographic research, Sylvie Fainzang, director of research in the Inserm (Cermes), examines how doctors and patients lie. She argues that lying, in the context of secrecy, is an indication of a power relationship [4]. Fainzaing’s further research on the relationship between doctors and patients has yielded additional information on how patients learn about their diagnoses and how they will react to these diagnoses. Though a clinical encounter between a doctor and patient is expected to be one of informed consent, doctors often judge patients upon their ability to “intellectually understand” [4] and assess who is “psychologically ready” [4] to bear the information. This leads to manipulated, misinformed, and “resigned consent” [4]. This sort of social training of obligation of a subject to medical authority provides the patient with the choice either to conform or overthrow the rules as defined by society.Collectively, this interdisciplinary panel worked to inform the discussion on how medical anthropology can address training, communication, and competence at the intersections of medicine, public health, and education. By reviewing health professionals’ growing interest in public health, training in health education and competence, and the patient-provider relationship, medical anthropology can be seen as both relevant and necessary to addressing the challenges faced by the medical and health community today.     

Molecular systematic study of Cardamine glechomifolia Levl. (Brassicaceae) using internal transcribed spacer sequence of nuclear ribosomal DNA (ITS) and chloroplast trnL and trnL-F sequences

The internal transcribed spacer (ITS) region of nuclear ribosomal DNA, trnL and trnL-F genes of Cardamine glechomifolia Levl. (family Brassicaceae) were sequenced and analyzed with the sequence of related Cardamine species retrieved from NCBI GenBank to detect pattern of evolutionary differentiation. All trees resulting from combined sequence analyses data of ITS, trnL and trnL-F gene resolve that C. glechomifolia – an endemic species to South Korea clade with Cardamine microzyga (100% bootstrap support). The evolutionary history was inferred using the Maximum Parsimony method. The consistency index is (0.588235), the retention index is (0.687500), and the composite index is 0.519622 (0.404412) for all sites and parsimony-informative sites (in parentheses). The result of the analysis using Maximum Parsimony was found congruence with Maximum Likelihood method and in Baseyan analysis.