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Recent Molecular (recent + molecular)
Terms modified by Recent Molecular Selected AbstractsAmyloid precursor protein-mediated free radicals and oxidative damage: Implications for the development and progression of Alzheimer's diseaseJOURNAL OF NEUROCHEMISTRY, Issue 1 2006P. Hemachandra Reddy Abstract Alzheimer's disease (AD) is a late-onset dementia that is characterized by the loss of memory and an impairment of multiple cognitive functions. Advancements in molecular, cellular, and animal model studies have revealed that the formation of amyloid beta (A,) and other derivatives of the amyloid precursor protein (APP) are key factors in cellular changes in the AD brain, including the generation of free radicals, oxidative damage, and inflammation. Recent molecular, cellular, and gene expression studies have revealed that A, enters mitochondria, induces the generation of free radicals, and leads to oxidative damage in post-mortem brain neurons from AD patients and in brain neurons from cell models and transgenic mouse models of AD. In the last three decades, tremendous progress has been made in mitochondrial research and has provided significant findings to link mitochondrial oxidative damage and neurodegenerative diseases such as AD. Researchers in the AD field are beginning to recognize the possible involvement of a mutant APP and its derivatives in causing mitochondrial oxidative damage in AD. This article summarizes the latest research findings on the generation of free radicals in mitochondria and provides a possible model that links A, proteins, the generation of free radicals, and oxidative damage in AD development and progression. [source] Neuroendocrinological and Molecular Aspects of Insect ReproductionJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2004G. Simonet Abstract This review summarizes recent advances and novel concepts in the area of insect reproductive neuroendocrinology. The role of ,classic' hormones, such as ecdysteroids and juvenoids, to control reproduction is well documented in a large variety of insect species. In adult gonads, ecdysteroids appear to induce a cascade of transcription factors, many of which also occur during the larval molting response. Recent molecular and functional data have created opportunities to study an additional level of regulation, that of neuropeptides, growth factors and their respective receptors. As a result, many homologs of factors playing a role in vertebrate reproductive physiology have been discovered in insects. This review highlights several neuropeptides controlling the biosynthesis and release of the ,classic' insect hormones, as well as various peptides and biogenic amines that regulate behavioural aspects of the reproduction process. In addition, hormone metabolizing enzymes and second messenger pathways are discussed with respect to their role in reproductive tissues. Finally, we speculate on future prospects for insect neuroendocrinological research as a consequence of the recent ,Genomics Revolution'. [source] Modelling polar auxin transport in developmental patterningPLANT BIOLOGY, Issue 2010F. Santos Abstract Auxin interacts with its own polar transport to influence cell polarity and tissue patterning. Research over the past decade has started to deliver new insights into the molecular mechanisms that drive and regulate polar auxin transport. The most prominent auxin efflux protein, PIN1, has subsequently become a crucial component of auxin transport models because it is now known to direct auxin flow and maintain local auxin gradients. Recent molecular and genetic experiments have allowed the formulation of conceptual models that are able to interpret the role of (i) auxin, (ii) its transport, and (iii) the dynamics of PIN1 in generating temporal and spatial patterns. Here we review the current mathematical models of patterning in two specific developmental contexts: lateral shoot and vein formation, focusing on how these models can help to untangle the details of auxin transport-mediated patterning. [source] Neuroendocrine mechanism of seasonal reproduction in birds and mammalsANIMAL SCIENCE JOURNAL, Issue 4 2010Takashi YOSHIMURA ABSTRACT In temperate zones, animals use changes in day length as a calendar to time their breeding season. However, the photoreceptive and neuroendocrine mechanisms of seasonal reproduction are considered to differ markedly between birds and mammals. This can be understood from the fact that the eye is the only photoreceptive organ, and melatonin mediates the photoperiodic information in mammals, whereas in birds, photoperiodic information is directly received by the deep brain photoreceptors and melatonin is not involved in seasonal reproduction. Recent molecular and functional genomics analysis uncovered the gene cascade regulating seasonal reproduction in birds and mammals. Long day-induced thyroid stimulating hormone in the pars tuberalis of the pituitary gland regulates thyroid hormone catabolism within the mediobasal hypothalamus. Further, this local thyroid hormone catabolism appears to regulate seasonal gonadotropin-releasing hormone secretion. These findings suggest that although the light input pathway is different between birds and mammals (i.e. light or melatonin), the core mechanisms are conserved in these vertebrates. [source] Patterns of evolutionary transformation in the petrosal bone and some basicranial features in marsupial mammals, with special reference to didelphidsJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2002M. R. SÁNCHEZ-VILLAGRA Twelve petrosal and four nonpetrosal characters were coded for representatives of all 15 extant genera of Didelphidae and for 16 additional genera of marsupials representing all extant orders. Three basal metatherians were used as outgroup comparison. Histological sections of a subset of the data were examined. An intermediate position of the hiatus Fallopii supports the monophyly of Didelphidae. Several basicranial regions support different clades within the Didelphidae that recent molecular work has identified, including a sister group relationship of Caluromys and Caluromysiops, the monophyly of large opossums, a Lestodelphys-Thylamys clade, and a Lestodelphys-Thylamys-Gracilinanus-Marmosops clade. Glironia lacks petrosal and jaw synapomorphies of Caluromys and Caluromysiops. The transverse canal, a synapomorphy of the crown-group Marsupialia, opens as a single foramen anterior to the carotid foramen in most marsupials or as numerous foramina in the pterygoid fossa in diprotodontians. It is either intramural (most marsupials) or simply endocranial (most diprotodontians excluding koalas and wombats). Loss of a deep sulcus in the anterior pole of the promontorium for the internal carotid artery and a rostral tympanic process of the petrosal also characterize the groundplan of the crown group Marsupialia. Pouch-young wombats show a groove in the anterior pole of the petrosal for the internal carotid artery. The absence of a prootic canal foramen in the tympanic side of the petrosal of adults supports the monophyly of Australidelphia. Some pouch-young marsupials possess a prootic canal that is later lost in ontogeny. A rather flat promontorium and a crest running medio-distally in the middle of the promontorium characterize Macropodidae. Zur Evolution des Petrosum und des Basicranium bei Beuteltiere, unter besonderer Berücksichtigung der Didelphiden Zwolf Merkmale des Petrosum und vier Merkmale des Basicranium wurden bei Vertretern aller Gattungen der Didelphidae sowie bei 16 zusätzlichen Taxa der Marsupialia untersucht. Drei basale Metatheria wurden als Außengruppen verwendet. Histologische Schnittserien von verschiedenen Arten wurden in die Untersuchung einbezogen. Einige monophyletische Gruppen innerhalb der Didelphidae, die durch molekulare Analysen identifiziert wurden, werden durch im Rahmen dieser Arbeit gewonnenen morphologischen Merkmale unterstützt, u. a., das Schwestergruppenverhältnis von Caluromys und Caluromysiops, die Monophylie von großen Opossums, sowie die Monophylie der Taxon-Gruppe Lestodelphys-Thylamys-Gracilinanus-Marmosops sowie der Gruppierung Marmosa-Micoureus-Monodelphis. Glironia fehlt die Synapomorphien von Caluromys und Caluromysiops, die in dieser Arbeit gefunden wurden. Das Fehlen des `deep sulcus' für die Arteria Carotis communis am Vorderende des Petrosum, ein Processus rostralis anterior des Petrosum und der Canalis transvs. werden als Synapomorphie der Kronengruppe Marsupialia gewertet. Das Fehlen des Canalis prooticus bei Cranien von Adultstadien unterstützt das Monophylum Australidelphia. Einige Beuteljunge von Australidelphien besitzen einen Canalis prooticus, der später in der Ontogenese zurückgebildet wird. Die Öffnung des Canalis transvs. liegt bei den meisten Marsupialia rostral zum Foramen caroticum, während bei den Diprotodontia die Öffnung aus verschiedenen Foramina in der Fossa pterygoidea besteht. Der Canalis transvs. ist entweder `intramural' oder einfach endocranial (Diprotodontia, aussschließlich Koalas und Wombats). Beuteljunge Wombat besitzen am Vorderende des Petrosums eine Rinne für die Arteria carotis interna. [source] History and evolution of the arctic flora: in the footsteps of Eric HulténMOLECULAR ECOLOGY, Issue 2 2003Richard J. Abbott Abstract A major contribution to our initial understanding of the origin, history and biogeography of the present-day arctic flora was made by Eric Hultén in his landmark book Outline of the History of Arctic and Boreal Biota during the Quarternary Period, published in 1937. Here we review recent molecular and fossil evidence that has tested some of Hultén's proposals. There is now excellent fossil, molecular and phytogeographical evidence to support Hultén's proposal that Beringia was a major northern refugium for arctic plants throughout the Quaternary. In contrast, most molecular evidence fails to support his proposal that contemporary east and west Atlantic populations of circumarctic and amphi-Atlantic species have been separated throughout the Quaternary. In fact, populations of these species from opposite sides of the Atlantic are normally genetically very similar, thus the North Atlantic does not appear to have been a strong barrier to their dispersal during the Quaternary. Hultén made no detailed proposals on mechanisms of speciation in the Arctic; however, molecular studies have confirmed that many arctic plants are allopolyploid, and some of them most probably originated during the Holocene. Recurrent formation of polyploids from differentiated diploid or more low-ploid populations provides one explanation for the intriguing taxonomic complexity of the arctic flora, also noted by Hultén. In addition, population fragmentation during glacial periods may have lead to the formation of new sibling species at the diploid level. Despite the progress made since Hultén wrote his book, there remain large gaps in our knowledge of the history of the arctic flora, especially about the origins of the founding stocks of this flora which first appeared in the Arctic at the end of the Pliocene (approximately 3 Ma). Comprehensive analyses of the molecular phylogeography of arctic taxa and their relatives together with detailed fossil studies are required to fill these gaps. [source] Phymatotrichum (cotton) root rot caused by Phymatotrichopsis omnivora: retrospects and prospectsMOLECULAR PLANT PATHOLOGY, Issue 3 2010SRINIVASA RAO UPPALAPATI SUMMARY Phymatotrichum (cotton or Texas) root rot is caused by the soil-borne fungus Phymatotrichopsis omnivora (Duggar) Hennebert. The broad host range of the fungus includes numerous crop plants, such as alfalfa and cotton. Together with an overview of existing knowledge, this review is aimed at discussing the recent molecular and genomic approaches that have been undertaken to better understand the disease development at the molecular level with the ultimate goal of developing resistant germplasm. Taxonomy:Phymatotrichopsis omnivora (Duggar) Hennebert [synonym Phymatotrichum omnivorum (Shear) Duggar] is an asexual fungus with no known sexual stage. Mitosporic botryoblastospores occasionally form on epigeous spore mats in nature, but perform no known function and do not contribute to the disease cycle. The fungus has been affiliated erroneously with the polypore basidiomycete Sistotrema brinkmannii (Bres.) J. Erikss. Recent phylogenetic studies have placed this fungus in the ascomycete order Pezizales. Host range and disease symptoms: The fungus infects most dicotyledonous field crops, causing significant losses to cotton, alfalfa, grape, fruit and nut trees and ornamental shrubs in the south-western USA, northern Mexico and possibly parts of central Asia. However, this fungus does not cause disease in monocotyledonous plants. Symptoms include an expanding tissue collapse (rot) of infected taproots. In above-ground tissues, the root rot results in vascular discoloration of the stem and rapid wilting of the leaves without abscission, and eventually the death of the plant. Characteristic mycelial strands of the pathogen are typically present on the root's surface, aiding diagnosis. Pathogenicity: Confocal imaging of P. omnivora interactions with Medicago truncatula roots revealed that infecting hyphae do not form any specialized structures for penetration and mainly colonize cortical cells and eventually form a mycelial mantle covering the root's surfaces. Cell wall-degrading enzymes have been implicated in penetration and symptom development. Global gene expression profiling of infected M. truncatula revealed roles for jasmonic acid, ethylene and the flavonoid pathway during disease development. Phymatotrichopsis omnivora apparently evades induced host defences and may suppress the host's phytochemical defences at later stages of infection to favour pathogenesis. Disease control: No consistently effective control measures are known. The long-lived sclerotia and facultative saprotrophism of P. omnivora make crop rotation ineffective. Chemical fumigation methods are not cost-effective for most crops. Interestingly, no genetic resistance has been reported in any of the susceptible crop species. [source] Transport of di- and tripeptides in teleost fish intestineAQUACULTURE RESEARCH, Issue 5 2010Tiziano Verri Abstract The initial observation of peptide absorption in fish intestine dates back to 1981, when, in rainbow trout (Oncorhynchus mykiss), the rate of intestinal absorption of the dipeptide glycylglycine (Gly-Gly) was compared in vivo with the rate of absorption of its component amino acid glycine (Gly). The description of the identification of the underlying mechanisms that allow di- and tripeptide transport across the plasma membranes in fish was provided in 1991, when the first evidence of peptide transport activity was reported in brush-border membrane vesicles of intestinal epithelial cells of Mozambique tilapia (Oreochromis mossambicus) by monitoring uptake of radiolabelled glycyl- l -phenylalanine (Gly- l -Phe). Since then, the existence of a carrier-mediated, H+ -dependent transport of di- and tripeptides (H+/peptide cotransport) in the brush-border membrane of fish enterocytes has been confirmed in many teleost species by a variety of biochemical approaches, providing basic kinetics and substrate specificities of the transport activity. In 2003, the first peptide transporter from a teleost fish, i.e. the zebrafish (Danio rerio) PEPtide transporter 1 (PEPT1), was cloned and functionally characterized in the Xenopus laevis oocyte expression system as a low-affinity/high-capacity system. PEPT1 is the protein in brush-border membranes responsible for translocation of intact di- and tripeptides released from dietary protein by luminal and membrane-bound proteases and peptidases. The transporter possesses affinities for the peptide substrates in the 0.1,10 mM range, depending on the structure and physicochemical nature of the substrates. After the molecular and functional characterization of the zebrafish transporter, the interest in PEPT1 in teleost fish has increased and approaches for cloning and functional characterization of PEPT1 orthologues from other fish species, some of them of the highest commercial value, are now underway. In this paper, we provide a brief overview of the transport of di- and tripeptides in teleost fish intestine by recalling the bulk of biochemical, biophysical and physiological observations collected in the pre-cloning era and by recapitulating the more recent molecular and functional data. [source] Towards a new classification of ectodermal dysplasiasCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 4 2003J. Lamartine Summary Ectodermal dysplasias (EDs) constitute a large and complex group of diseases characterized by various defects in hair, nails, teeth and sweat glands. Of the 170 EDs described so far, fewer than 30 have been explained at the molecular level with identification of the causative gene. This review proposes a new classification of EDs based on the function of the protein encoded by the mutated gene. The EDs are reviewed in light of the recent molecular and biochemical findings and an attempt is made to classify ED causative genes into four major functional subgroups: cell,cell communication and signalling; adhesion; transcription regulation; and development. [source] | |||||||||||||