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At least 883 records · Page 49Linked to original sources
PubMed2006

Evolution of developmental strategies in parasitic hymenoptera.

Parasitoid wasps have evolved a wide spectrum of developmental interactions with hosts. In this review we synthesize and interpret results from the phylogenetic, ecological, physiological, and molecular literature to identify factors that have influenced the evolution of parasitoid developmental strategies. We first discuss the origins and radiation of the parasitoid lifestyle in the Hymenoptera. We then summarize how parasitoid developmental strategies are affected by ecological interactions and assess the inventory of physiological and molecular traits parasitoids use to successfully exploit hosts. Last, we discuss how certain parasitoid virulence genes have evolved and how these changes potentially affect parasitoid-host interactions. The combination of phylogenetic data with comparative and functional genomics offers new avenues for understanding the evolution of biological diversity in this group of insects.

Animals↗
PubMed2005

Exploiting chinks in the plant's armor: evolution and emergence of geminiviruses.

The majority of plant-infecting viruses utilize an RNA genome, suggesting that plants have imposed strict constraints on the evolution of DNA viruses. The geminiviruses represent a family of DNA viruses that has circumvented these impediments to emerge as one of the most successful viral pathogens, causing severe economic losses to agricultural production worldwide. The genetic diversity reflected in present-day geminiviruses provides important insights into the evolution and biology of these pathogens. To maximize replication of their DNA genome, these viruses acquired and evolved mechanisms to manipulate the plant cell cycle machinery for DNA replication, and to optimize the number of cells available for infection. In addition, several strategies for cell-to-cell and long-distance movement of the infectious viral DNA were evolved and refined to be compatible with the constraints imposed by the host endogenous macromolecular trafficking machinery. Mechanisms also evolved to circumvent the host antiviral defense systems. Effectively combatting diseases caused by geminiviruses represents a major challenge and opportunity for biotechnology.

Biological Evolution↗
PubMed1989

Steroid metabolism determines mineralocorticoid specificity in the toad bladder.

Edwards et al. (C. R. W. Edwards, P. M. Stewart, D. Burt, L. Brett, M. A. McIntyre, W. S. Sutanto, E. R. de Kloet, and C. Monder, Lancet 2: 986-989, 1988) proposed that 11 beta-hydroxysteroid-dehydrogenase (11 beta-OHSD) plays a key role in the kidney by converting glucocorticoids (cortisol or corticosterone), which display a high affinity for type 1 mineralocorticoid receptors, into their inactive metabolites (cortisone or 11-dehydroxy-corticosterone), thus preventing their illicit occupation of the receptor in the target cell for aldosterone. We have tested this hypothesis in the urinary bladder of Bufo marinus by measuring the sodium transport responses to aldosterone and corticosterone. Aldosterone (10 nM) on the serosal side elicited a quarter of the maximal increase in sodium transport. At the same concentration, corticosterone (10 nM, serosal side) was ineffective. Adding corticosterone (10 nM) on the mucosal side elicited a response equivalent to that of aldosterone, suggesting that corticosterone was inactivated in the serosal or underlying tissue of the toad bladder. Carbenoxolone (10 microM, serosal side), a potent inhibitor of 11 beta-OHSD, did not modify the base-line sodium transport. However, in the presence of carbenoxolone (10 microM, serosal side, 2 h pretreatment) corticosterone (10 nM, serosal side) became as potent as aldosterone in eliciting the mineralocorticoid response. Our data are consistent with the idea that corticosterone is converted into an inactive metabolite in the mucosal and/or submucosal tissue of the toad bladder. These studies are consistent with our concept that 11 beta-OHSD is crucial in protecting the nonspecific mineralocorticoid receptor from glucocorticoid.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed2006

Sodium/calcium exchanger: influence of metabolic regulation on ion carrier interactions.

The Na(+)/Ca(2+) exchanger's family of membrane transporters is widely distributed in cells and tissues of the animal kingdom and constitutes one of the most important mechanisms for extruding Ca(2+) from the cell. Two basic properties characterize them. 1) Their activity is not predicted by thermodynamic parameters of classical electrogenic countertransporters (dependence on ionic gradients and membrane potential), but is markedly regulated by transported (Na(+) and Ca(2+)) and nontransported ionic species (protons and other monovalent cations). These modulations take place at specific sites in the exchanger protein located at extra-, intra-, and transmembrane protein domains. 2) Exchange activity is also regulated by the metabolic state of the cell. The mammalian and invertebrate preparations share MgATP in that role; the squid has an additional compound, phosphoarginine. This review emphasizes the interrelationships between ionic and metabolic modulations of Na(+)/Ca(2+) exchange, focusing mainly in two preparations where most of the studies have been carried out: the mammalian heart and the squid giant axon. A surprising fact that emerges when comparing the MgATP-related pathways in these two systems is that although they are different (phosphatidylinositol bisphosphate in the cardiac and a soluble cytosolic regulatory protein in the squid), their final target effects are essentially similar: Na(+)-Ca(2+)-H(+) interactions with the exchanger. A model integrating both ionic and metabolic interactions in the regulation of the exchanger is discussed in detail as well as its relevance in cellular Ca(i)(2+) homeostasis.

Animals↗
PubMedDate not supplied

Haplotyping in pedigrees via a genetic algorithm.

Genome-wide screening for localization of disease genes necessitates the efficient reconstruction of haplotypes of members of a pedigree from genotype data at multiple loci. We propose a genetic algorithmic approach to haplotyping and show that it works fast, efficiently and reliably. This algorithm uses certain principles of biological evolution to find optimal solutions to complex problems. The optimality criterion used in the present problem is the minimum number of recombinations over possible haplotype configurations of members of a pedigree. The proposed algorithm is much less demanding in terms of data and assumption requirements compared to the currently used likelihood-based methods of haplotype reconstruction. It also provides multiple optimal haplotype configurations of a pedigree, if such multiple optima exist.

Algorithms↗
PubMed2003

Long-term follow-up of childhood-onset hypopituitarism in patients with the PROP-1 gene mutation.

OBJECTIVE: The PROP-1 gene mutation is a rare disorder leading to combined pituitary hormone deficiencies over time. The aim was to analyze the clinical picture of 40 years of an almost untreated PROP-1 gene mutation. METHODS: We describe the clinical and hormonal data of 2 brothers from childhood to adulthood as well as imaging procedures (MRI of the pituitary gland, bone mineral density by QCT and DPX). The PROP-1 gene mutation (301-302delAG) was confirmed by DNA sequencing. RESULTS: Although long-standing untreated hypopituitarism was present, there was normal physical and professional activity. Bone mineral density was low only in 1 patient. Adrenocortical deficiency occurred late at 45 and 39 years. CONCLUSIONS: The biological evolution of the PROP-1 gene mutation illustrates the importance of continuous care for these patients. Hormonal deficiencies do not necessarily lead to the same phenotype as is obvious in differences of bone age and bone mineral density.

Adolescent↗
PubMed1977

Acute infantile pneumonopathies treated with fosfomycin.

Reference is made to the results obtained in 24 children, from 11 months to 12 years, affected with acute pneumopathies and treated with fosfomycin with a dosage of 200 mg/kg/day. In all cases a clinical, radiological, biological and bacteriological study was carried out. At the same time, levels of fosfomycin in plasma and sputum were checked every 5 days during the course of treatment. In the 4 cases of pleurisy the level of antibiotic in the pleural liquid was also checked. The concentration of fosfomycin in the sputum gives very variable results with average values oscillating between 16.5 and 23.4% of the plasmatic level respectively at the beginning and end of treatment, a cumulative effect of the antibiotic being observed. Concentration in pleural liquid oscillates between 39 and 50%. The clinical, radiological and biological evolution has been favourable iin 21 cases, unfavourable in two cases and in one case treatment had to be suspended because of the apparition of a cutaneous necrosis. Apart from this case no notable toxic effects were observed. Children do not support intramuscular injections very well and intravenous injections often cause phlebitis.

Anti-Bacterial Agents↗
PubMed1993

Clinical manifestations of allergy and their relation to HIV infection.

In this retrospective study 141 HIV positive subjects were included. Allergy was studied by a specific questionnaire and the Phadia Top Test, an in vitro screening test for specific IgE. Both were related to the patients' history, clinical symptoms and the treatment used. Allergy was studied in reference to HIV negative controls and in relation to the clinical and biological subgroups of HIV patients. The statistical analysis (x 2 test) demonstrated a relationship between allergy and HIV infection and the clinical stage of AIDS-IKEL among patients with CD4 > 300 microliters, which may suggest that allergy contributes to the functional deficiency of these cells. We also demonstrated a high frequency of hypersensitivity reactions (75%) in HIV asymptomatic patients with CD4 < 300 microliters, which indicates that allergy could contribute to the early destruction of these cells. The allergic patients declared to be hypersensitive before contamination. Both mechanisms, functional deficiency and destruction of CD4 T-lymphocytes could be the result of the mediators, cytokines and enzymes released from the mast cells during IgE allergic reaction. Thus this study demonstrated that allergy could be a predisposing factor for the contamination and a polyvalent co-factor for the clinical and biologic evolution of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Did Kettlewell commit fraud? Re-examining the evidence.

H.B.D. Kettlewell is famous for several investigations conducted in the early 1950s on the phenomenon of industrial melanism, which are widely regarded as the classic demonstration of natural selection. In a recent (2002) book-length popularization of this episode in the history of the science, science writer Judith Hooper draws attention to what she interprets as discrepancies in the results reported by Kettlewell in his first scientific papers on the subject. On the basis of correspondence among Kettlewell and his associates, a survey of scientific publications that mention outstanding questions surrounding the phenomenon, as well as interviews with his son, surviving colleagues, and scientists who have worked on industrial melanims, Hooper all but explicitly concludes that Kettlewell committed fraud. The following essay critically examines her evidence in support of this allegation, including her discussion of his character, the alleged motives, and whether fraud was even committed. None of Hooper's arguments is found to withstand careful scrutiny. The concluding section draws several conclusions about how history of science should be depicted to the public.

Animals↗