Molecular Diversity (molecular + diversity)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Side-Chain Retention During Lithiation of 4-Picoline and 3,4-Lutidine: Easy Access to Molecular Diversity in Pyridine Series

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2003
Thomas Kaminski
Abstract The first direct ring-selective lithiation of 4-picoline and 3,4-lutidine has been achieved through the use of BuLi/LiDMAE aggregates to prevent the usual side-chain metallation. Several functionalities have been introduced at the C-2, C-6 and C-5 positions by ring-selective sequential lithiation, opening a simple and fast route to polysubstituted pyridine building blocks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


Molecular Diversity of Vasotocin-Dependent Aquaporins Closely Associated with Water Adaptation Strategy in Anuran Amphibians

JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010
M. Suzuki
Anuran amphibians represent the first vertebrates that adapted to terrestrial environments, and are successfully distributed around the world, even to forests and arid deserts. Many adult anurans have specialised osmoregulatory organs, in addition to the kidney (i.e. the ventral pelvic skin to absorb water from the external environments and a urinary bladder that stores water and reabsorbs it in times of need). Aquaporin (AQP), a water channel protein, plays a fundamental role in these water absorption/reabsorption processes. The anuran AQP family consists of at least AQP0-AQP5, AQP7-AQP10 and two anuran-specific types, designated as AQPa1 and AQPa2. For the three osmoregulatory organs, AQP3 is constitutively located in the basolateral membrane of the tight-junctioned epithelial cells, allowing water transport between the cytoplasm of these cells and the neighbouring tissue fluid at all times. On the other hand, AQPs at the apical side of the tight epithelial cells are different among these organs, and are named kidney-type AQP2, ventral pelvic skin-type AQPa2 and urinary bladder-type AQPa2. All of them show translocation from the cytoplasmic pool to the apical plasma membrane in response to arginine vasotocin, thereby regulating water transport independently in each osmoregulatory organ. It was further revealed that, in terrestrial and arboreal anurans, the bladder-type AQPa2 is expressed in the pelvic skin, together with the pelvic skin-type AQPa2, potentially facilitating water absorption from the pelvic skin. By contrast, Xenopus has lost the ability to efficiently produce pelvic skin-type AQPa2 (AQP-x3) because Cys-273 of AQP-x3 and/or Cys-273-coding region of AQPx3 mRNA attenuate gene expression at a post-transcriptional step, presumably leading to the prevention of excessive water influx in this aquatic species. Collectively, the acquisition of two forms of AQPa2 and the diversified regulation of their gene expression appears to provide the necessary mechanisms for the evolutionary adaptation of anurans to a wide variety of ecological environments. [source]


Molecular Diversity of VEGF-A as a Regulator of Its Biological Activity

MICROCIRCULATION, Issue 7 2009
Jeanette Woolard
ABSTRACT The vascular endothelial growth factor (VEGF) family of proteins regulates blood flow, growth, and function in both normal physiology and disease processes. VEGF-A is alternatively spliced to form multiple isoforms, in two subfamilies, that have specific, novel functions. Alternative splicing of exons 5,7 of the VEGF gene generates forms with differing bioavailability and activities, whereas alternative splice-site selection in exon 8 generates proangiogenic, termed VEGFxxx, or antiangiogenic proteins, termed VEGFxxxb. Despite its name, emerging roles for VEGF isoforms on cell types other than endothelium have now been identified. Although VEGF-A has conventionally been considered to be a family of proangiogenic, propermeability vasodilators, the identification of effects on nonendothelial cells, and the discovery of the antiangiogenic subfamily of splice isoforms, has added further complexity to their regulation of microvascular function. The distally spliced antiangiogenic isoforms are expressed in normal human tissue, but downregulated in angiogenic diseases, such as cancer and proliferative retinopathy, and in developmental pathologies, such as Denys Drash syndrome and preeclampsia. Here, we examine the molecular diversity of VEGF-A as a regulator of its biological activity and compare the role of the pro- and antiangiogenic VEGF-A splice isoforms in both normal and pathophysiological processes. [source]


Molecular Diversity from Tonghaosu Analogues, Selective Reduction of the endo-Cyclic Double Bond of Tonghaosu Analogues and the Synthesis of Cyclopentenone Derivatives.

CHEMINFORM, Issue 23 2003
Biao-Lin Yin
Abstract For Abstract see ChemInform Abstract in Full Text. [source]


Atomic Diversity, Molecular Diversity, and Chemical Diversity: The Concept of Chemodiversity

CHEMISTRY & BIODIVERSITY, Issue 8 2009
Bernard Testa
Abstract This minireview is meant as an introduction to the following paper. To this end, it presents the general background against which the joint paper should be understood. The first objective of the present paper is thus to clarify some concepts and related terminology, drawing a clear distinction between i) atomic diversity (i.e., atomic-property space), ii) molecular or macromolecular diversity (i.e., molecular- or macromolecular-property spaces), and iii) chemical diversity (i.e., chemical-diversity space). The first refers to the various electronic states an atom can occupy. The second encompasses the conformational and property spaces of a given (macro)molecule. The third pertains to the diversity in structure and properties exhibited by a library or a supramolecular assembly of different chemical compounds. The ground is thus laid for the content of the joint paper, which pertains to case ii, to be placed in its broader chemodiversity context. The second objective of this paper is to point to the concepts of chemodiversity and biodiversity as forming a continuum. Chemodiversity is indeed the material substratum of organisms. In other words, chemodiversity is the material condition for life to emerge and exist. Increasing our knowledge of chemodiversity is thus a condition for a better understanding of life as a process. [source]


Molecular Diversity Of Vascular Potassium Channel Isoforms

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2002
Victoria P Korovkina
SUMMARY 1. One essential role for potassium channels in vascular smooth muscle is to buffer cell excitation and counteract vasoconstrictive influences. Several molecular mechanisms regulate potassium channel function. The interaction of these mechanisms may be one method for fine-tuning potassium channel activity in response to various physiological and pathological challenges. 2. The most prevalent K+ channels in vascular smooth muscle are large-conductance calcium- and voltage-sensitive channels (maxi-K channels) and voltage-gated channels (Kv channels). Both channel types are complex molecular structures consisting of a pore-forming , -subunit and an ancillary , -subunit. The maxi-K and Kv channel , -subunits assemble as tetramers and have S4 transmembrane domains that represent the putative voltage sensor. While most vascular smooth muscle cells identified to date contain both maxi-K and Kv channels, the expression of individual , -subunit isoforms and , -subunit association occurs in a tissue-specific manner, thereby providing functional specificity. 3. The maxi-K channel , -subunit derives its molecular diversity by alternative splicing of a single-gene transcript to yield multiple isoforms that differ in their sensitivity to intracellular Ca2+ and voltage, cell surface expression and post- translational modification. The ability of this channel to assemble as a homo- or heterotetramer allows for fine-tuning control to intracellular regulators. Another level of diversity for this channel is in its association with accessory , -subunits. Multiple , -subunits have been identified that can arise either from separate genes or alternative splicing of a , -subunit gene. The maxi-K channel , -subunits modulate the channel's Ca2+ and voltage sensitivity and kinetic and pharmacological properties. 4. The Kv channel , -subunit derives its diverse nature by the expression of several genes. Similar to the maxi-K channel, this channel has been shown to assemble as a homo- and heterotetramer, which can significantly change the Kv current phenotype in a given cell type. Association with a number of the ancillary , -subunits affects Kv channel function in several ways. Beta-subunits can induce inactivating properties and act as chaperones, thereby regulating channel cell-surface expression and current kinetics. [source]


Molecular diversity and characterization of nitrite reductase gene fragments (nirK and nirS) from nitrate- and uranium-contaminated groundwater

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2003
Tingfen Yan
Summary Nitrate-contaminated groundwater samples were analysed for nirK and nirS gene diversity. The samples differed with respect to nitrate, uranium, heavy metals, organic carbon content, pH and dissolved oxygen levels. A total of 958 nirK and 1162 nirS clones were screened by restriction fragment length polymorphism (RFLP) analysis: 48 and 143 distinct nirK and nirS clones, respectively, were obtained. A single dominant nirK restriction pattern was observed for all six samples and was 83% identical to the Hyphomicrobium zavarzinii nirK gene. A dominant nirS pattern was observed for four of the samples, including the background sample, and was 95% identical to the nirS of Alcaligenes faecalis. Diversity indices for nirK and nirS sequences were not related to any single geochemical characteristic, but results suggested that the diversity of nirK genes was inversely proportional to the diversity of nirS. Principal component analysis (PCA) of the sites based on geochemistry grouped the samples by low, moderate and high nitrate but PCA of the unique operational taxonomic units (OTUs) distributions grouped the samples differently. Many of the sequences were not closely related to previously observed genes and some phylogenetically related sequences were obtained from similar samples. The results indicated that the contaminated groundwater contained novel nirK and nirS sequences, functional diversity of both genes changed in relation to the contaminant gradient, but the nirK and nirS functional diversity was affected differently. [source]


Molecular diversity of HLA-A*19 group of alleles in south Indian population

INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 2 2006
V. Vettriselvi
Summary To determine the genetic diversity of the human leucocyte antigen (HLA)-A*19 group of alleles in the south Indian Tamil population, we studied 100 random healthy unrelated individuals. The frequency of HLA-A*19 was 37% with A*33 (45.9%), A*32 (29.7%), A*31 (16.2%), A*30 (5.4%), A*29 (2.7%) and A*74 (0%). The frequency distribution of the HLA-A*19 alleles was distinct and revealed marked similarities and variations with other populations [source]


Characterization of Bacillus subtilis strains in Thua nao, a traditional fermented soybean food in northern Thailand

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2006
Y. Inatsu
Abstract Aims:, To clarify the diversity of Bacillus subtilis strains in Thua nao that produce high concentrations of products useful in food manufacturing and in health-promoting compounds. Method and Results:, Production of amylase, protease, subtilisin NAT (nattokinase), and gamma-polyglutamic acid (PGA) by the Bacillus subtilis strains in Thua nao was measured. Productivity of protease NAT by these strains tended to be higher than by Japanese commercial natto-producing strains. Molecular diversity of isolated strains was analysed via randomly amplified polymorphic DNA-PCR fingerprinting. The strains were divided into 19 types, including a type with the same pattern as a Japanese natto-producing strain. Conclusion:,B. subtilis strains that could be a resource for effective production of protease, amylase, subtilisin NAT, or PGA were evident in Thua nao produced in various regions in northern Thailand. Significance and Impact of the Study:, This study clearly demonstrated the value of Thua nao as a potential resource of food-processing enzymes and health-promoting compounds. [source]


Molecular diversity of arbuscular mycorrhizal fungi and patterns of host association over time and space in a tropical forest

MOLECULAR ECOLOGY, Issue 12 2002
R. Husband
Abstract We have used molecular techniques to investigate the diversity and distribution of the arbuscular mycorrhizal (AM) fungi colonizing tree seedling roots in the tropical forest on Barro Colorado Island (BCI), Republic of Panama. In the first year, we sampled newly emergent seedlings of the understory treelet Faramea occidentalis and the canopy emergent Tetragastris panamensis, from mixed seedling carpets at each of two sites. The following year we sampled surviving seedlings from these cohorts. The roots of 48 plants were analysed using AM fungal-specific primers to amplify and clone partial small subunit (SSU) ribosomal RNA gene sequences. Over 1300 clones were screened for random fragment length polymorphism (RFLP) variation and 7% of these were sequenced. Compared with AM fungal communities sampled from temperate habitats using the same method, the overall diversity was high, with a total of 30 AM fungal types identified. Seventeen of these types have not been recorded previously, with the remainder being similar to types reported from temperate habitats. The tropical mycorrhizal population showed significant spatial heterogeneity and nonrandom associations with the different hosts. Moreover there was a strong shift in the mycorrhizal communities over time. AM fungal types that were dominant in the newly germinated seedlings were almost entirely replaced by previously rare types in the surviving seedlings the following year. The high diversity and huge variation detected across time points, sites and hosts, implies that the AM fungal types are ecologically distinct and thus may have the potential to influence recruitment and host composition in tropical forests. [source]


Molecular diversity of the genetic loci responsible for lipopolysaccharide core oligosaccharide assembly within the genus Salmonella

MOLECULAR MICROBIOLOGY, Issue 5 2002
Natalia A. Kaniuk
Summary The waa locus on the chromosome of Salmonella enterica encodes enzymes involved in the assembly of the core oligosaccharide region of the lipopolysaccharide (LPS) molecule. To date, there are two known core structures in Salmonella, represented by serovars Typhimurium (subspecies I) and Arizonae (subspecies IIIA). The waa locus for serovar Typhimurium has been characterized. Here, the corresponding locus from serovar Arizonae is described, and the molecular basis for the distinctive structures is established. Eleven of the 13 open reading frames (ORFs) are shared by the two loci and encode conserved proteins of known function. Two polymorphic regions distinguish the waa loci. One involves the waaK gene, the product of which adds a terminal ,-1,2-linked N -acetylglucosamine residue that characterizes the serovar Typhimurium core oligosaccharide. There is an extensive internal deletion within waaK of serovar Arizonae. The serovar Arizonae locus contains a novel ORF (waaH) between the waaB and waaP genes. Structural analyses and in vitro glycosyltransferase assays identified WaaH as the UDP-glucose:(glucosyl) LPS ,-1,2-glucosyltransferase responsible for the addition of the characteristic terminal glucose residue found in serovar Arizonae. Isolates comprising the Salmonella Reference Collections, SARC (representing the eight subspecies of S. enterica) and SARB (representing subspecies I), were examined to assess the distribution of the waa locus polymorphic regions in natural populations. These comparative studies identified additional waa locus polymorphisms, shedding light on the genetic basis for diversity in the LPS core oligosaccharides of Salmonella isolates and identifying potential sources of further novel LPS structures. [source]


Molecular diversity and association of SSR markers to rust and late leaf spot resistance in cultivated groundnut (Arachis hypogaea L.)

PLANT BREEDING, Issue 1 2010
S. Mondal
With 1 figure and 2 tables Abstract Molecular diversity and association of simple sequence repeat (SSR) markers with rust and late leaf spot (LLS) resistance were detected in a set of 20 cultivated groundnut genotypes differing in resistance against both diseases. Out of 136 bands amplified from 26 primers, 104 were found polymorphic (76.5%). Cluster analysis (UPGMA) revealed two main clusters separated at 52% Jaccard's similarity coefficient according to disease reaction to rust and LLS. Based on the Kruskal,Wallis one-way anova and simple regression analysis three and four SSR alleles were found associated with rust and LLS resistance, respectively. [source]


Molecular diversity of toxic components from the scorpion Heterometrus petersii venom revealed by proteomic and transcriptome analysis

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2010
Yibao Ma
Abstract Scorpion venoms contain a vast untapped reservoir of natural products, which have the potential for medicinal value in drug discovery. In this study, toxin components from the scorpion Heterometrus petersii venom were evaluated by transcriptome and proteome analysis. Ten known families of venom peptides and proteins were identified, which include: two families of potassium channel toxins, four families of antimicrobial and cytolytic peptides, and one family from each of the calcium channel toxins, La1-like peptides, phospholipase A2, and the serine proteases. In addition, we also identified 12 atypical families, which include the acid phosphatases, diuretic peptides, and ten orphan families. From the data presented here, the extreme diversity and convergence of toxic components in scorpion venom was uncovered. Our work demonstrates the power of combining transcriptomic and proteomic approaches in the study of animal venoms. [source]


Molecular diversity of PBAN family peptides from fire ants,

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2010
Man-Yeon Choi
Abstract The PBAN/Pyrokinin peptide family is a major neuropeptide family characterized with a common FXPRLamide in the C-termini. These peptides are ubiquitously distributed in the Insecta and are involved in many essential endocrinal functions, e.g., pheromone production. Previous work demonstrated the localization of PBAN in the fire ant central nervous system, and identified a new family of PBAN from the red imported fire ant, Solenopsis invicta. In this study, we identified five more PBAN/Pyrokinin genes from S. geminata, S. richteri, S. pergandii, S. carolinensis, and a hybrid of S. invicta and S. richteri. The gene sequences were used to determine the phylogenetic relationships of these species and hybrid, which compared well to the morphologically defined fire ant subgroup complexes. The putative PBAN and other peptides were determined from the amino acid sequences of the PBAN/pyrokinin genes. We summarized all known insect PBAN family neuropeptides, and for the first time constructed a phylogenetic tree based on the full amino acid sequences translated from representative PBAN cDNAs. The PBAN/pyrokinin gene is well conserved in Insecta and probably extends into the Arthropod phylum; however, translated pre-propeptides may vary and functional diversity may be retained, lost, or modified during the evolutionary process. Published 2010 Wiley Periodicals, Inc. [source]


Molecular diversity of Proteus mirabilis isolates producing extended-spectrum ,-lactamases in a French university hospital

CLINICAL MICROBIOLOGY AND INFECTION, Issue 5 2005
M. Biendo
Abstract Between February 1997 and December 2002, 3340 hospitalised patients yielded samples positive for Proteus mirabilis, of whom 45 (1.3%) were colonised/infected by P. mirabilis producing extended-spectrum ,-lactamases (ESBLs). The gross incidence of patients colonised/infected by ESBL-producing P. mirabilis was 1.61/105 days of hospitalisation, with 20% of isolates being collected from patients in urology wards, most frequently (53.3%) from urine samples. Seventeen (37.7%) of the 43 isolates were obtained from samples collected within 48 h of hospitalisation, indicating that they were community-acquired. Isoelectric focusing assays and sequencing identified the TEM-24, TEM-92 and TEM-52 ESBLs. Pulsed-field gel electrophoresis revealed eight pulsotypes (I,VIII), with the two most common pulsotypes, IV and VI, comprising ten (23.3%) and 12 (26.6%) isolates, respectively. These pulsotypes were considered to represent epidemic strains and spread in various wards of the hospital. [source]


Ascomycetes associated with ectomycorrhizas: molecular diversity and ecology with particular reference to the Helotiales

ENVIRONMENTAL MICROBIOLOGY, Issue 12 2009
Leho Tedersoo
Summary Mycorrhizosphere microbes enhance functioning of the plant,soil interface, but little is known of their ecology. This study aims to characterize the ascomycete communities associated with ectomycorrhizas in two Tasmanian wet sclerophyll forests. We hypothesize that both the phyto- and mycobiont, mantle type, soil microbiotope and geographical distance affect the diversity and occurrence of the associated ascomycetes. Using the culture-independent rDNA sequence analysis, we demonstrate a high diversity of these fungi on different hosts and habitats. Plant host has the strongest effect on the occurrence of the dominant species and community composition of ectomycorrhiza-associated fungi. Root endophytes, soil saprobes, myco-, phyto- and entomopathogens contribute to the ectomycorrhiza-associated ascomycete community. Taxonomically these Ascomycota mostly belong to the orders Helotiales, Hypocreales, Chaetothyriales and Sordariales. Members of Helotiales from both Tasmania and the Northern Hemisphere are phylogenetically closely related to root endophytes and ericoid mycorrhizal fungi, suggesting their strong ecological and evolutionary links. Ectomycorrhizal mycobionts from Australia and the Northern Hemisphere are taxonomically unrelated to each other and phylogenetically distant to other helotialean root-associated fungi, indicating independent evolution. The ubiquity and diversity of the secondary root-associated fungi should be considered in studies of mycorrhizal communities to avoid overestimating the richness of true symbionts. [source]


Vertical distribution of picoeukaryotic diversity in the Sargasso Sea

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2007
Fabrice Not
Summary Eukaryotic molecular diversity within the picoplanktonic size-fraction has primarily been studied in marine surface waters. Here, the vertical distribution of picoeukaryotic diversity was investigated in the Sargasso Sea from euphotic to abyssal waters, using size-fractionated samples (< 2 ,m). 18S rRNA gene clone libraries were used to generate sequences from euphotic zone samples (deep chlorophyll maximum to the surface); the permanent thermocline (500 m); and the pelagic deep-sea (3000 m). Euphotic zone and deep-sea data contrasted strongly, the former displaying greater diversity at the first-rank taxon level, based on 232 nearly full-length sequences. Deep-sea sequences belonged almost exclusively to the Alveolata and Radiolaria, while surface samples also contained known and putative photosynthetic groups, such as unique Chlorarachniophyta and Chrysophyceae sequences. Phylogenetic analyses placed most Alveolata and Stramenopile sequences within previously reported ,environmental' clades, i.e. clades within the Novel Alveolate groups I and II (NAI and NAII), or the novel Marine Stramenopiles (MAST). However, some deep-sea NAII formed distinct, bootstrap supported clades. Stramenopiles were recovered from the euphotic zone only, although many MAST are reportedly heterotrophic, making the observed distribution a point for further investigation. An unexpectedly high proportion of radiolarian sequences were recovered. From these, five environmental radiolarian clades, RAD-I to RAD-V, were identified. RAD-IV and RAD-V were composed of Taxopodida-like sequences, with the former solely containing Sargasso Sea sequences, although from all depth zones sampled. Our findings highlight the vast diversity of these protists, most of which remain uncultured and of unknown ecological function. [source]


Secreted factors from ventral telencephalon induce the differentiation of GABAergic neurons in cortical cultures

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006
H.-h. Trinh
Abstract It is widely believed that the pyramidal cells and interneurons of the cerebral cortex are distinct in their origin, lineage and genetic make up. In view of these findings, the current thesis is that the phenotype determination of cortical neurons is primarily directed by genetic mechanisms. Using in vitro assays, the present study demonstrates that secreted factors from ganglionic eminence (GE) of the ventral telencephalon have the potency to induce the differentiation of a subset of cortical neurons towards ,-aminobutyric acid (GABA)ergic lineage. Characterization of cortical cultures that were exposed to medium derived from GE illustrated a significant increase in the number of GABA-, calretinin- and calbindin-positive neurons. Calcium imaging together with pharmacological studies showed that the application of exogenous medium significantly elevated the intracellular calcium transients in cortical neurons through the activation of ionotropic glutamate receptors. The increase in GABA+ neurons appeared to be associated with the elevated calcium activity; treatment with blockers specific for glutamate receptors abolished both the synchronized transients and reduced the differentiation of GABAergic neurons. Such studies demonstrate that although intrinsic mechanisms determine the fate of cortical interneurons, extrinsic factors have the potency to influence their neurochemical differentiation and contribute towards their molecular diversity. [source]


Synthesis of Pyridodiazepinediones by Using the Ugi Multicomponent Reaction

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2010
An M. Van den Bogaert
Abstract Benzodiazepines show a broad spectrum of biological activities. In an ongoing effort to extend molecular diversity in this type of systems, we developed a strategy for synthesizing3,4-dihydro-1H -pyrido[2,3- e][1,4]diazepine-2,5-dione compounds starting from 2-hydroxynicotinic acid and by using an Ugi reaction as a key step in the synthesis. We opted to use 2-isocyanophenyl benzoate instead of Armstrong's convertible isocyanide in this multicomponent reaction. [source]


Spatial characterization of arbuscular mycorrhizal fungal molecular diversity at the submetre scale in a temperate grassland

FEMS MICROBIOLOGY ECOLOGY, Issue 2 2008
Daniel L. Mummey
Abstract Although arbuscular mycorrhizal fungi (AMF) form spatially complex communities in terrestrial ecosystems, the scales at which this diversity manifests itself is poorly understood. This information is critical to the understanding of the role of AMF in plant community composition. We examined small-scale (submetre) variability of AMF community composition (terminal restriction fragment length polymorphism fingerprinting) and abundance (extraradical hyphal lengths) in two 1 m2 plots situated in a native grassland ecosystem of western Montana. Extraradical AMF hyphal lengths varied greatly between samples (14,89 m g soil,1) and exhibited spatial structure at scales <30 cm. The composition of AMF communities was also found to exhibit significant spatial autocorrelation, with correlogram analyses suggesting patchiness at scales <50 cm. Supportive of overall AMF community composition analyses, individual AMF ribotypes corresponding to specific phylogenetic groups exhibited distinct spatial autocorrelation. Our results demonstrate that AMF diversity and abundance can be spatially structured at scales of <1 m. Such small-scale heterogeneity in the soil suggests that establishing seedlings may be exposed to very different, location dependent AMF communities. Our results also have direct implications for representative sampling of AMF communities in the field. [source]


Phylogenetic diversity of T4-like bacteriophages in Lake Baikal, East Siberia

FEMS MICROBIOLOGY LETTERS, Issue 2 2010
Tatyana Vladimirovna Butina
Abstract Among the tailed phages, the myoviruses, those with contractile tails, are widespread and diverse. An important component of the Myoviridae family is the genus ,T4-like viruses'. The present study was aimed at elucidating the molecular diversity of T4-type bacteriophages in Lake Baikal by partial sequencing of g23 genes of T4-type bacteriophages. Our study revealed that the g23 gene sequences investigated were highly diverse and different from those of T4-like bacteriophages and from g23 clones obtained from different environments. Phylogenetic analysis showed that all g23 fragments from Lake Baikal, except for the one sequence, were more closely related to marine T4 cyanophages and to previously described subgroups of uncultured T4 phages from marine and rice field environments. [source]


A Novel Strategy for the Construction of Functionalized 1,5- Benzodiazepines via a Tandem Conjugated Addition/Cyclization Process

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Jian Li
Abstract A novel approach for the synthesis of functionalized 1,5-benzodiazepine is described. The protocol is triggered by a tandem conjugated addition/cyclization process from the readily available starting materials 1,2-phenylenediamine and ethyl propiolate. The products have secondary amino and ester groups, and a ,-enamino ester, which can serve in further functionalizations to produce molecular diversity. [source]


Neither molecular diversity of the envelope, immunosuppression status, nor proviral load causes indeterminate HTLV western blot profiles in samples from human T-cell lymphotropic virus type 2 (HTLV-2)-infected individuals

JOURNAL OF MEDICAL VIROLOGY, Issue 5 2010
Ingrid Olah
Abstract Although human T-cell lymphotropic virus type 2 (HTLV-2) is considered of low pathogenicity, serological diagnosis is important for counseling and monitoring. The confirmatory tests most used are Western blot (WB) and PCR. However, in high-risk populations, about 50% of the indeterminate WB were HTLV-2 positives by PCR. The insensitivity of the WB might be due to the use of recombinant proteins of strains that do not circulate in our country. Another possibility may be a high level of immunosuppression, which could lead to low production of virus, resulting in low stimulation of antibody. We found one mutation, proline to serine in the envelope region in the position 184, presented at least 1/3 of the samples, independent the indeterminate WB profile. In conclusion, we found no correlation of immune state, HTLV-2 proviral load, or env diversity in the K55 region and WB indeterminate results. We believe that the only WB kit available in the market is probably more accurate to detect HTLV-1 antibodies, and some improvement for HTLV-2 detection should be done in the future, especially among high-risk population. J. Med. Virol. 82: 837,842, 2010. © 2010 Wiley-Liss, Inc. [source]


Molecular epidemiology of HIV-1 in Santa Catarina State confirms increases of subtype C in Southern Brazil

JOURNAL OF MEDICAL VIROLOGY, Issue 10 2007
Dayse Locateli
Abstract Recent studies have demonstrated an increased prevalence of human immunodeficiency virus type 1 (HIV-1) subtype C in southern Brazil. Although Santa Catarina State (SC) is located in this area and presents one of the country's highest incidences of HIV/AIDS, knowledge on the molecular epidemiology of HIV-1 in such State is lacking. The aim of this study was to investigate the HIV-1 molecular diversity and epidemiological profile of HIV-1-infected patients from SC. DNA samples were PCR amplified and HIV-1 subtypes were determined using both env and gag genes by direct sequencing. Phylogenetic analyses revealed that 48% were subtype C and 23% were subtype B. Possible recombinant forms were observed for both B/C (23%) and B/F (6%) subtypes. Our results, for the first time, identifies HIV-1 subtype C as a major clade circulating in SC and contributes to the understanding of HIV epidemics in the country by confirming the epidemic spread of the HIV-1 subtype C in southern Brazil. J. Med. Virol. 79:1455,1463, 2007. © Wiley-Liss, Inc. [source]


Molecular epidemiology of HIV in Ghana: Dominance of CRF02_AG

JOURNAL OF MEDICAL VIROLOGY, Issue 2 2004
Lucia Fischetti
Abstract Recent studies showed the importance of CRF02_AG in West Africa, although the clinical relevance of these recombinant forms of HIV remains unknown. The present study aimed at determining the molecular diversity of HIV in Ghana and investigating the possible epidemiologic advantage of recombinant HIV-1. Plasma samples collected in 1999,2002 from two populations of HIV infected individuals (144 asymptomatic candidate blood donors and 169 AIDS patients) were studied and 249 of them were molecularly characterised in gag, pol, and env regions. Five molecular groups were identified: strains clustering with CRF02_AG in all regions (147/249 or 59%), recombinant strains clustering with CRF02_AG in one or two regions (50/249 or 20%), other subtypes, pure or recombinant, but not involving CRF02_AG (37/249 or 15%), HIV-2 (11/249 or 4.5%), and double infections (4/249 or 1.5%). There was no significant difference in the distribution of HIV-1 recombinant strains according to clinical presentation. No evidence of a significant increase in CRF02_AG prevalence between 1999 and 2002 was found. Irrespective of clinical condition, CRF02_AG is the predominant molecular form of HIV-1 in Kumasi, Ghana. J. Med. Virol. 73:158,166, 2004. © 2004 Wiley-Liss, Inc. [source]


Expression and molecular diversity of Tcf7l2 in the developing murine cerebellum and brain

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 7 2009
Tommy A. Nazwar
Abstract The Wingless family of secreted proteins impinges on multiple aspects of vertebrate nervous system development, from early global patterning and cell fate decision to synaptogenesis. Here, we mapped the developmental expression of the Tcf7l2, which is key to the canonical Wingless signaling cascade, in the developing cerebellum. The exclusive and transient expression of Tcf7l2 in ventricular and Olig2-defined precursor cells within the cerebellar anlage, and its predominant expression in postmitotic neurons in the midbrain/inferior colliculus allowed us to ask whether cell type,specific differences are also reflected in splice isoform variability. We also included in this analysis intestinal epithelia, where Tcf7l2 function has been intensively studied. Our data reveal extensive variability of Tcf7l2 splicing in the central nervous system. Additional variability in brain-expressed Tcf7l2 is generated by a length polymorphism of expressed mRNAs in a stretch of normally nine adenines found at the beginning of exon 18, reminiscent of variability observed at the same site in cancers with microsatellite instability. A consensus emerging from our data is that the expression of isoforms comprising or lacking the C-clamp motif, which has been linked by in vitro studies to the regulation of cell growth, is indeed tightly correlated with the proliferative status in vivo. © 2009 Wiley-Liss, Inc. [source]


Genome-wide expression analysis of intra- and extraarticular connective tissue

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2009
Richard V. Pearse II
Abstract In comparison to extraarticular ligaments and tendons, the intraarticular ligaments such as the anterior and posterior cruciates exhibit different biochemical, biomechanical, and viscoelastic properties and most importantly, differential abilities to heal after surgical repair. Little is known about the underlying basis for these differences, in large measure due to the paucity of molecular markers distinguishing different classes of tendons and ligaments. To date, there has been no systematic analysis of gene expression differences between different types of connective tissues. We used Affymetrix expression arrays to analyze the differences in gene expression levels between the anterior cruciate, posterior cruciate, and medial collateral ligaments, the patellar and Achilles tendons and the synovium. We have identified five clusters of gene cohorts displaying similar expression patterns. These clusters group into three categories including: (1) genes that are strongly expressed in all connective tissues compared to the synovium control tissue; (2) genes that distinguish intraarticular connective tissues from extraarticular connective tissues; and (3) a group of genes expressed in common by the patellar tendon and the synovium. Our analysis identifies a new marker of tendons and ligaments (fibin2), demonstrates molecular diversity between subtypes of tendons and ligaments, and indicates that the primary molecular subdivision among dense regular connective tissues is intra- versus extraarticular rather than ligament versus tendon. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 427,434, 2009 [source]


Molecular Diversity of VEGF-A as a Regulator of Its Biological Activity

MICROCIRCULATION, Issue 7 2009
Jeanette Woolard
ABSTRACT The vascular endothelial growth factor (VEGF) family of proteins regulates blood flow, growth, and function in both normal physiology and disease processes. VEGF-A is alternatively spliced to form multiple isoforms, in two subfamilies, that have specific, novel functions. Alternative splicing of exons 5,7 of the VEGF gene generates forms with differing bioavailability and activities, whereas alternative splice-site selection in exon 8 generates proangiogenic, termed VEGFxxx, or antiangiogenic proteins, termed VEGFxxxb. Despite its name, emerging roles for VEGF isoforms on cell types other than endothelium have now been identified. Although VEGF-A has conventionally been considered to be a family of proangiogenic, propermeability vasodilators, the identification of effects on nonendothelial cells, and the discovery of the antiangiogenic subfamily of splice isoforms, has added further complexity to their regulation of microvascular function. The distally spliced antiangiogenic isoforms are expressed in normal human tissue, but downregulated in angiogenic diseases, such as cancer and proliferative retinopathy, and in developmental pathologies, such as Denys Drash syndrome and preeclampsia. Here, we examine the molecular diversity of VEGF-A as a regulator of its biological activity and compare the role of the pro- and antiangiogenic VEGF-A splice isoforms in both normal and pathophysiological processes. [source]


Functional variation in a disease resistance gene in populations of Arabidopsis thaliana

MOLECULAR ECOLOGY, Issue 22 2008
T. H. JORGENSEN
Abstract Analyses of functional genetic diversity in natural populations may provide important new insights into gene function and are necessary to understand the evolutionary processes maintaining diversity itself. The importance of including diversity within and between local populations in such studies is often ignored although many of the processes affecting genetic diversity act on this scale. Here we examine the molecular diversity in RPW8 (Recognition of Powdery Mildew), a gene conferring broad-spectrum resistance to powdery mildews in Arabidopsis thaliana stock-center accessions. Our eight UK study populations of the weedy A. thaliana were from locations judged to be subject to a minimum of anthropogenic disturbance and potentially long established. The majority of populations comprised considerable variation both in disease phenotype and RPW8 genotype. Although resistant individuals shared a major RPW8 genotype, no single allele was uniquely associated with resistance. It is concluded that RPW8 is an essential component of resistance to powdery mildews in A. thaliana, but not the only genetic factor involved in this process. No signature of selection was detected at RPW8 with a microsatellite multilocus test using an empirical null model. Unlike many previous studies of this model plant species, we found high levels of genetic diversity and relatively low differentiation (FST = 0.31) between populations at 14 microsatellite markers. This is judged to be due to our sampling being aimed at potentially long established populations and highlights the importance of population choice for studies of genetic diversity within this species. [source]


Genetic structure of the widespread and common Mediterranean bryophyte Pleurochaete squarrosa (Brid.) Lindb. (Pottiaceae) , evidence from nuclear and plastidic DNA sequence variation and allozymes

MOLECULAR ECOLOGY, Issue 4 2007
MICHAEL GRUNDMANN
Abstract The Mediterranean Basin as one the world's most biologically diverse regions provides an interesting area for the study of plant evolution and spatial structure in plant populations. The dioecious moss Pleurochaete squarrosa is a widespread and common bryophyte in the Mediterranean Basin. Thirty populations were sampled for a study on molecular diversity and genetic structure, covering most major islands and mainland populations from Europe and Africa. A significant decline in nuclear and chloroplast sequence and allozyme variation within populations from west to east was observed. While DNA sequence data showed patterns of isolation by distance, allozyme markers did not. Instead, their considerable interpopulation genetic differentiation appeared to be unrelated to geographic distance. Similar high values for coefficients of gene diversity (GST) in all data sets provided evidence of geographic isolation and limited gene flow among populations (i) within islands, (ii) within mainland areas, and (iii) between islands and mainland. Notably, populations in continental Spain are strongly genetically isolated from all other investigated areas. Surprisingly, there was no difference in gene diversity and GST between islands and mainland areas. Thus, we conclude that large Mediterranean islands may function as ,mainland' for bryophytes. This hypothesis and its implication for conservation biology of cryptogamic plants warrant further investigation. While sexually reproducing populations were found all over the Mediterranean Basin, high levels of multilocus linkage disequilibrium provide evidence of mainly vegetative propagation even in populations where sexual reproduction was observed. [source]