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Mixed Population (mixed + population)
Selected AbstractsMechanisms of resistance to DDT and pyrethroids in Patagonian populations of Simulium blackfliesMEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2003C. M. Montagna Abstract. Mixed populations of the pest blackflies Simulium bonaerense Coscarón & Wygodzinsky, S. wolffhuegeli (Enderlein) and S. nigristrigatum Wygodzinsky & Coscarón (Diptera: Simuliidae) are highly resistant to DDT and pyrethroids in the Neuquén Valley, a fruit-growing area of northern Patagonia, Argentina. As these insecticides have not been used for blackfly control, resistance is attributed to exposure to agricultural insecticides. Pre-treatment with the synergist piperonyl butoxide (PBO) reduced both DDT and fenvalerate resistance, indicating that resistance was partly due to monooxygenase inhibition. Pre-treatment with the synergist tribufos to inhibit esterases slightly increased fenvalerate toxicity in the resistant population. Even so, biochemical studies indicated almost three-fold higher esterase activity in the resistant population, compared to the susceptible. Starch gel electrophoresis confirmed higher frequency and staining intensity of esterase electromorphs in the resistant population. Incomplete synergism against metabolic resistance indicates additional involvement of a non-metabolic resistance mechanism, such as target site insensitivity, assumed to be kdr -like in this case. Glutathione S-transferase activities were low and inconsistent, indicating no role in Simulium resistance. Knowing these spectra of insecticide activity and resistance mechanisms facilitates the choice of more effective products for Simulium control and permits better coordination with agrochemical operations. [source] Presence of Lythrum salicaria enhances the bodyguard effects of the parasitoid Asecodes mento for Filipendula ulmariaOIKOS, Issue 3 2007Johan A. Stenberg This paper reports significant effects of a co-occurring plant species (Lythrum salicaria, Lythraceae) on the reproductive success of the perennial herb Filipendula ulmaria (Rosaceae). We studied 15 Filipendula populations in the Skeppsvik Archipelago; seven of which were monospecific and eight mixed with Lythrum. All the Filipendula populations studied harbored the chrysomelid beetle Galerucella tenella, and in 2005 seed set was strongly negatively correlated with the percentage leaf area consumed. Moreover, data from 2004 showed that 25,100% of the G. tenella larvae were parasitized by the hymenopteran parasitoid Asecodes mento, and we found a strong cascading top-down effect of parasitism in 2004 on Filipendula seed set in 2005. In 2004, parasitism (at the population level) was negatively correlated with percentage leaf area consumed and positively correlated with seed set in 2005. The parasitoid Asecodes also parasitized G. calmariensis, which is monophagous on Lythrum. Mixed populations of Filipendula and Lythrum supported higher densities of their shared ,bodyguard'Asecodes. Further, Y-tube bioassays showed that floriferous Filipendula attracted more than twice as many gravid Asecodes females as floriferous Lythrum. Taken together, these findings suggest that coexistence of the two plants results in ,associational resistance' for Filipendula and ,associational susceptibility' for Lythrum. This scenario was supported for Filipendula since, for this species, we found lower leaf consumption followed by higher seed production in mixed than in monospecific populations. Considered together, our results show that bodyguards may increase the reproductive fitness of a perennial herb, and that the strength of the cascading ,bodyguard' effect can be strongly influenced by co-occurring plants through ,apparent competition'. This is the first paper to demonstrate that, in the wild, plant species may use odors to compete for ,bodyguards', thereby causing asymmetrical ,apparent competition' between the herbivores involved. Our data emphasize the need to consider community factors in studies of trophic interactions. [source] Spatial repartition and genetic relationship of green and albino individuals in mixed populations of Cephalanthera orchidsPLANT BIOLOGY, Issue 4 2010V. Tranchida-Lombardo Abstract Several green orchids of the Neottieae tribe acquire organic carbon both from their mycorrhizal fungi and from photosynthesis. This strategy may represent an intermediate evolutionary step towards mycoheterotrophy of some non-photosynthetic (albino) orchids. Mixed populations of green and albino individuals possibly represent a transient evolutionary stage offering opportunities to understand the evolution of mycoheterotrophy. In order to understand the emergence of albinos, we investigated patterns of spatial and genetic relationships among green and albino individuals in three mixed populations of Cephalanthera damasonium and one of C. longifolia using spatial repartition and Amplified fragment length polymorphism (AFLP) markers. Two of these populations were monitored over two consecutive flowering seasons. In spatial repartition analyses, albino individuals did not aggregate more than green individuals. Genetic analyses revealed that, in all sampled populations, albino individuals did not represent a unique lineage, and that albinos were often closer related to green individuals than to other albinos from the same population. Genetic and spatial comparison of genets from the 2-year monitoring revealed that: (i) albinos had lower survival than green individuals; (ii) accordingly, albinos detected in the first year did not correspond to the those sampled in the second year; and (iii) with one possible exception, all examined albinos did not belong to any green genet from the same and/or from the previous year, and vice versa. Our results support a scenario of repeated insurgence of the albino phenotypes within the populations, but unsuccessful transition between the two contrasting phenotypes. Future studies should try to unravel the genetic and ecological basis of the two phenotypes. [source] Videoendoscopic evaluation of the upper respiratory tract in 93 sport horses during exercise testing on a high-speed treadmillEQUINE VETERINARY JOURNAL, Issue S36 2006S. H. FRANKLIN Summary Reasons for performing study: Videoendoscopy of the upper respiratory tract (URT) during high-speed treadmill exercise has proved to be invaluable in the assessment of URT dysfunction in racehorses. However, very little information exists regarding dynamic airway collapse in other sport horses used in nonracing equestrian disciplines. Objectives: To evaluate the videoendoscopic findings at rest and during exercise in a mixed population of sport horses referred for investigation of poor athletic performance and/or abnormal respiratory noise. Methods: Videoendoscopy of the upper airway was performed at rest and during high-speed treadmill exercise in 93 horses. Results: Dynamic airway obstructions were diagnosed in 77% of horses and were frequently complex in nature. The most common forms of dynamic collapse included soft palate dysfunction (54%), dynamic laryngeal collapse (38%), axial deviation of the aryepiglottic folds (24%) and pharyngeal wall collapse (18%). In the majority of horses, no obvious abnormalities were identified at rest. Enforced poll flexion was found to be a contributing factor in 24% of cases. Conclusions: Dynamic obstructions of the URT were a common cause of poor performance and/or abnormal respiratory noise in sport horses referred for investigation of performance problems. Potential relevance: This study highlights the importance of videoendoscopic evaluation of the URT during exercise in horses utilised for equestrian sports where exercise during competition is submaximal in nature. [source] Synaptic contacts between an identified type of ON cone bipolar cell and ganglion cells in the mouse retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2005Bin Lin Abstract We surveyed the potential contacts between an identified type of bipolar cell and retinal ganglion cells in the mouse. By crossing two existing mouse strains (line 357 and line GFP-M), we created a double transgenic strain in which GFP is expressed by all members of a single type of ON cone bipolar cell and a sparse, mixed population of retinal ganglion cells. The GFP-expressing bipolar cells appear to be those termed CB4a of Pignatelli & Strettoi [(2004) J. Comp. Neurol., 476, 254,266] and type 7 of Ghosh et al. [(2004) J. Comp. Neurol., 469, 70,82 and J. Comp. Neurol., 476, 202,203]. The labelled ganglion cells include examples of most or all types of ganglion cells present in the mouse. By studying the juxtaposition of their processes in three dimensions, we could learn which ganglion cell types are potential synaptic targets of the line 357 bipolar cell. Of 12 ganglion cell types observed, 10 types could be definitively ruled out as major synaptic targets of the line 357 bipolar cells. One type of monostratified ganglion cell and one bistratified cell tightly cofasciculate with axon terminals of the line 357 bipolar cells. Double labelling for kinesin II demonstrates colocalization of bipolar cell ribbons at the sites of contact between these two types of ganglion cell and the line 357 bipolar cells. [source] Identification and characterization of cytochrome bc1 subcomplexes in mitochondria from yeast with single and double deletions of genes encoding cytochrome bc1 subunitsFEBS JOURNAL, Issue 17 2007Vincenzo Zara We have examined the status of the cytochrome bc1 complex in mitochondrial membranes from yeast mutants in which genes for one or more of the cytochrome bc1 complex subunits were deleted. When membranes from wild-type yeast were resolved by native gel electrophoresis and analyzed by immunodecoration, the cytochrome bc1 complex was detected as a mixed population of enzymes, consisting of cytochrome bc1 dimers, and ternary complexes of cytochrome bc1 dimers associated with one and two copies of the cytochrome c oxidase complex. When membranes from the deletion mutants were resolved and analyzed, the cytochrome bc1 dimer was not associated with the cytochrome c oxidase complex in many of the mutant membranes, and membranes from some of the mutants contained a common set of cytochrome bc1 subcomplexes. When these subcomplexes were fractionated by SDS/PAGE and analyzed with subunit-specific antibodies, it was possible to recognize a subcomplex consisting of cytochrome b, subunit 7 and subunit 8 that is apparently associated with cytochrome c oxidase early in the assembly process, prior to acquisition of the remaining cytochrome bc1 subunits. It was also possible to identify a subcomplex consisting of subunit 9 and the Rieske protein, and two subcomplexes containing cytochrome c1 associated with core protein 1 and core protein 2, respectively. The analysis of all the cytochrome bc1 subcomplexes with monospecific antibodies directed against Bcs1p revealed that this chaperone protein is involved in a late stage of cytochrome bc1 complex assembly. [source] Factors Related to Helicobacter pylori Prevalence in an Adult Population in BrazilHELICOBACTER, Issue 1 2007Schlioma Zaterka Abstract Background:, The prevalence of Helicobacter pylori is higher in developing countries. Sanitary facilities, crowding and ethnic group are some of the factors related to H. pylori infection. The aim of this study was to investigate in blood donors, free of dyspeptic symptoms, the prevalence and factors influencing H. pylori infection. Materials and Methods:, This study was conducted in São Paulo, a city known to have a mixed population coming from all over the country. A total of 1008 blood donors were initially included in the study. After a final revision of all the questionnaires, 993 were included in the final analysis (746 males). H. pylori status was checked by an ELISA test. The following associations to infection were analyzed: sex, age, ethnic group, previous upper gastrointestinal (GI) endoscopy, smoking, alcoholism, drug addiction, type of drinking water, crowding, sanitary facilities, and family income. Results:, Infection was observed in 496 of 746 male (66.5%) and in 156 of 247 female (63.2%) blood donors. Infection prevalence increased according to age group, regardless of sex. Prevalence was lower in White population than in non-White. No relationship was observed between infection and smoking, drug addiction, and alcohol. A positive relation was observed between infection and previous upper GI endoscopy, and type of drinking water, regardless if currently or during childhood. Crowding and lack of toilet in the house during childhood resulted in a higher infection rate. Lower familial income and educational level showed a positive association to infection. Conclusions:, Prevalence of H. pylori is higher in non-White population, independent of gender. A positive association was observed in aging, previous upper GI endoscopy, crowding, type of drinking water, lack of toilet during childhood, lower family income, and lower educational level. [source] Different Helicobacter pylori Strains Colonize the Antral and Duodenal Mucosa of Duodenal Ulcer PatientsHELICOBACTER, Issue 2 2000Ann-Catrin E. Thoreson Background. We have investigated the possibility that the same patients may be colonized by Helicobacter pylori strains of different genotypes or phenotypes in the antrum as compared to in the duodenum. The strains were typed for DNA fingerprints, different lipopolysaccharides (LPS), and Lewis antigen expression on the O,side chains of LPS. Materials and Methods. Polymerase chain reaction (PCR) amplifications using primer sequences (i.e., the Enterobacterial Repetitive Intergenic Consensus [ERIC]) and randomly amplified polymorphic DNA (RAPD) elements were performed to asses chromosomal DNA diversity between H. pylori strains. The expression of different LPS types and Lewis antigens in the various H. pylori isolates were determined by whole bacterial enzyme-linked immunosorbent assays using monoclonal antibodies. Results. Duodenal ulcer patients had different H. pylori genotypes in the duodenum as compared to in the antrum as shown by ERIC-PCR (44%) and by RAPD-PCR (75%). Different DNA patterns were found among the strains that were isolated from various regions of the duodenum in 4 of 16 patients (25%) as shown by ERIC-PCR and in 8 of 16 patients (50%) as shown by RAPD-PCR. Sixty-three percent of the duodenal ulcer patients had H. pylori strains with a different Lewis antigen phenotype in the duodenum as compared to in the antrum, and 3 of 16 patients (19%) had strains with different Lewis antigens expressed by strains from different duodenal biopsies from the same patient. Conclusion. The results suggest that a mixed population of different H. pylori strains with marked variation, both genotypically and phenotypically, colonize the same patient. [source] Characterization of cells of the B lineage in the human adult greater omentumIMMUNOLOGY, Issue 1 2006Laurent Boursier Summary Peritoneal B cells and their omental precursors play an important role in the immune response of the peritoneal cavity and mucosal surfaces in mice. We have previously shown that peritoneal and mucosal B lineage cells are unlikely to be significantly linked in humans. However, the status of the omentum remains unknown. Here, using immunohistochemistry, we observed that sparse, quiescent B cells and occasional clusters of B cells were present in the omentum and that plasma cells, predominantly with cytoplasmic immunoglobulin G (IgG), were present. We analysed sequences of immunoglobulin genes amplified using reverse transcriptase,polymerase chain reaction (RT-PCR) from the normal human greater omentum, and describe the characteristics of variable region genes used by IgG, IgA and IgM. We focused on the properties of IgVH4 and IgVH5 families to allow comparisons of like with like between different Ig isotypes and cells from different immune compartments. We observed that the IgM genes were derived from a mixed population with mutated and unmutated immunoglobulin sequences. All IgVH4 and IgVH5 genes used by IgA and IgG from omental cells showed evidence of somatic hypermutation but the load of mutations was not significantly different to that seen in either the systemic or the mucosal compartments. The trends observed, including the dominance of IgG plasma cells, the IgA1/IgA2 ratio being biased towards IgA1, JH1 usage, and a moderate level of somatic mutations, link omental B lineage cells with the systemic compartment. These observations reinforce previous studies highlighting the difference between human and murine B-cell compartments and their relationship to the mucosal immune system. [source] Oligonucleotide microarrays for the detection and identification of viable beer spoilage bacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2008D.G. Weber Abstract Aims:, The design and evaluation of an oligonucleotide microarray in order to detect and identify viable bacterial species that play a significant role in beer spoilage. These belong to the species of the genera Lactobacillus, Megasphaera, Pediococcus and Pectinatus. Methods and Results:, Oligonucleotide probes specific to beer spoilage bacteria were designed. In order to detect viable bacteria, the probes were designed to target the intergenic spacer regions (ISR) between 16S and 23S rRNA. Prior to hybridization the ISR were amplified by combining reverse transcriptase and polymerase chain reactions using a designed consenus primer. The developed oligonucleotide microarrays allows the detection of viable beer spoilage bacteria. Conclusions:, This method allows the detection and discrimination of single bacterial species in a sample containing complex microbial community. Furthermore, microarrays using oligonucleotide probes targeting the ISR allow the distinction between viable bacteria with the potential to grow and non growing bacteria. Significance and Impact of the Study:, The results demonstrate the feasibility of oligonucleotide microarrays as a contamination control in food industry for the detection and identification of spoilage micro-organisms within a mixed population. [source] Resident bacteria in a mixed population of rhesus macaque (Macaca mulatta) monkeys: a prevalence studyJOURNAL OF MEDICAL PRIMATOLOGY, Issue 6 2009C.A. Carrier Abstract Background, Microflora populations residing in oropharyngeal and gastrointestinal sites defend against pathogenic bacterial colonization. Perturbations in these microbial communities may allow opportunistic pathogenic bacteria to establish themselves and cause morbidity and mortality from sepsis particularly after stressful experimental procedures. This study determined the prevalent facultative bacteria in a resident population of Macaca mulatta prior to use in experimentally induced immunosuppressive radiation studies. Methods, Standard microbiological methods were used to assess prevalent facultative bacteria in the oropharynx and rectum of 24 male M. mulatta. Results, The majority of the bacteria isolated from the oropharyngeal and rectal sites were gram-positive cocci. Species of Staphylococcus and Streptococcus predominated in all samples. Few gram-negative bacteria were isolated. Conclusions, Bacteriological assessment is recommended to identify predominant bacterial species to be prepared to provide appropriate antimicrobial therapy in non-human primates that are expected to undergo stressful immunocompromising procedures. [source] Reproducible methodology for the isolation of mesenchymal stem cells from human umbilical cord and its potential for cardiomyocyte generationJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 7 2008Winston Costa Pereira Abstract Mesenchymal stem cells (MSCs) are considered to be a source of stem cells in tissue regeneration and therapeutics, due to their ability to undergo proliferation and differentiation. Complications associated with bone marrow-derived MSCs has prompted researchers to explore alternative sources of MSCs. The human umbilical cord is one such source; it is easily available and its collection is non-invasive. The sources of MSCs are non-controversial and thus they are not subjected to ethical constraints, as in the case of embryonic stem cells. MSCs are multipotent stem cells and has the ability to differentiate into various cell types of the mesodermal lineage. The aim of this study was to establish a reproducible method for the isolation of MSCs from human umbilical cord, as the few methods published till date gave inconsistent results and had a mixed population of contaminating endothelial cells. In our isolation strategy, we isolated a pure population of MSCs from Wharton's jelly of the human umbilical cord, which is very rich in collagen, and we used a high concentration of collagenase enzyme in the isolation of MSCs. Extensive phenotypic characterization analysis of these cells, using flow cytometry and antibody staining methods, have shown that we were able to isolate a pure population of the mesenchymal lineage cells that is devoid of haematopoietic and endothelial cell contaminants. When these MSCs were subjected to cardiomyocyte differentiation, we observed a change in the morphological characteristics, which was accompanied by the formation of myotube structures and spontaneous beating after 21 days. Copyright © 2008 John Wiley & Sons, Ltd. [source] Competition between vectors of Chagas disease, Triatoma infestans and T. sordida: effects on fecundity and mortalityMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2004E. B. Oscherov Abstract., Interspecific competition between two species of triatomine bugs (Hemiptera: Reduviidae), vectors of Chagas disease, was assessed for 16 months through comparative fecundity and mortality of experimental populations in chicken nests, maintained indoors with ambient conditions. Triatoma sordida (Stål), the secondary vector in north-eastern Argentina, was compared with Triatoma infestans (Klug) the more widespread domestic vector in the southern cone of South America. Both species populations originated from females collected in 1995 from the community of Empedrado, Corrientes, Argentina. Three population units were monitored: T. infestans alone, T. sordida alone and both species together in equal proportions. Each population started with six male and six female adults, 116 eggs, and nymphal instars I to V numbering 82, 48, 16, 11 and 19, respectively. Numbers and weight of individual bugs were recorded monthly (August 1995 to December 1996). The pure populations of T. infestans and T. sordida showed temporal changes in abundance, rising in summer and falling in winter, similar to the typical trends under normal field conditions. In the mixed population, however, T. sordida fell to extinction after 6 months, whereas T. infestans reached similar abundance to the pure (control) population. For each nymphal instar of T. sordida, the mean body weight was significantly less and mortality rate was higher in the mixed population compared to the pure population, but there were no significant differences of adult longevity or fecundity between the pure and mixed populations of T. sordida. The apparent competitive displacement of T. sordida by T. infestans was attributed to the latter species having better ability to obtain bloodmeals. This might explain the rarity of mixed populations where these two species occur in sympatry. [source] First determination of the incidence of the unique TOR1A gene mutation, c.907delGAG, in a Mediterranean populationMOVEMENT DISORDERS, Issue 6 2007Mélissa Frédéric MS Abstract The c.907delGAG mutation in the TOR1A gene (also named DYT1) is the most common cause of early-onset primary dystonia. The mutation frequency and prevalence have so far been only estimated from rare clinical epidemiological reports in some populations. The purpose of this study was to investigate the incidence at birth of the c.907delGAG mutation in a French-representative mixed population of newborn from South-Eastern France. We applied an automated high-throughput genotyping method to dried blood spot samples from 12,000 newborns registered in Hérault between 2004 and 2005. Only one allele was found to carry the mutation, which allows to determine its incidence at birth as 1/12,000 per year in this area. © 2007 Movement Disorder Society [source] Widespread hybridization between the Greater Spotted Eagle Aquila clanga and the Lesser Spotted Eagle Aquila pomarina (Aves: Accipitriformes) in EuropeBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010ÜLO VÄLI Hybridization is a significant threat for endangered species and could potentially even lead to their extinction. This concern applies to the globally vulnerable Greater Spotted Eagle Aquila clanga, a species that co-occurs, and potentially interbreeds, with the more common Lesser Spotted Eagle Aquila pomarina in a vast area of Eastern Europe. We applied single nucleotide polymorphism (SNP) and microsatellite markers in order to study hybridization and introgression in 14 European spotted eagle populations. We detected hybridization and/or introgression in all studied sympatric populations. In most regions, hybridization took place prevalently between A. pomarina males and A. clanga females, with introgression to the more common A. pomarina. However, such a pattern was not as obvious in regions where A. clanga is still numerous. In the course of 16 years of genetic monitoring of a mixed population in Estonia, we observed the abandonment of A. clanga breeding territories and the replacement of A. clanga pairs by A. pomarina, whereby on several occasions hybridization was an intermediate step before the disappearance of A. clanga. Although the total number of Estonian A. clanga × A. pomarina pairs was twice as high as that of A. clanga pairs, the number of pairs recorded yearly were approximately equal, which suggests a higher turnover rate in interbreeding pairs. This study shows that interspecific introgressive hybridization occurs rather frequently in a hybrid zone at least 1700-km wide: it poses an additional threat for the vulnerable A. clanga, and may contribute to the extinction of its populations. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 725,736. [source] Syntrophic interactions among anode respiring bacteria (ARB) and Non-ARB in a biofilm anode: electron balancesBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2009Prathap Parameswaran Abstract We demonstrate that the coulombic efficiency (CE) of a microbial electrolytic cell (MEC) fueled with a fermentable substrate, ethanol, depended on the interactions among anode respiring bacteria (ARB) and other groups of micro-organisms, particularly fermenters and methanogens. When we allowed methanogenesis, we obtained a CE of 60%, and 26% of the electrons were lost as methane. The only methanogenic genus detected by quantitative real-time PCR was the hydrogenotrophic genus, Methanobacteriales, which presumably consumed all the hydrogen produced during ethanol fermentation (,30% of total electrons). We did not detect acetoclastic methanogenic genera, indicating that acetate-oxidizing ARB out-competed acetoclastic methanogens. Current production and methane formation increased in parallel, suggesting a syntrophic interaction between methanogens and acetate-consuming ARB. When we inhibited methanogenesis with 50 mM 2-bromoethane sulfonic acid (BES), the CE increased to 84%, and methane was not produced. With no methanogenesis, the electrons from hydrogen were converted to electrical current, either directly by the ARB or channeled to acetate through homo-acetogenesis. This illustrates the key role of competition among the various H2 scavengers and that, when the hydrogen-consuming methanogens were present, they out-competed the other groups. These findings also demonstrate the importance of a three-way syntrophic relationship among fermenters, acetate-consuming ARB, and a H2 consumer during the utilization of a fermentable substrate. To obtain high coulombic efficiencies with fermentable substrates in a mixed population, methanogens must be suppressed to promote new interactions at the anode that ultimately channel the electrons from hydrogen to current. Biotechnol. Bioeng. 2009;103: 513,523. © 2009 Wiley Periodicals, Inc. [source] Determination of community structure through deconvolution of PLFA-FAME signature of mixed populationBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2007Dipesh K. Dey Abstract Phospholipid fatty acids (PLFAs) as biomarkers are well established in the literature. A general method based on least square approximation (LSA) was developed for the estimation of community structure from the PLFA signature of a mixed population where biomarker PLFA signatures of the component species were known. Fatty acid methyl ester (FAME) standards were used as species analogs and mixture of the standards as representative of the mixed population. The PLFA/FAME signatures were analyzed by gas chromatographic separation, followed by detection in flame ionization detector (GC-FID). The PLFAs in the signature were quantified as relative weight percent of the total PLFA. The PLFA signatures were analyzed by the models to predict community structure of the mixture. The LSA model results were compared with the existing "functional group" approach. Both successfully predicted community structure of mixed population containing completely unrelated species with uncommon PLFAs. For slightest intersection in PLFA signatures of component species, the LSA model produced better results. This was mainly due to inability of the "functional group" approach to distinguish the relative amounts of the common PLFA coming from more than one species. The performance of the LSA model was influenced by errors in the chromatographic analyses. Suppression (or enhancement) of a component's PLFA signature in chromatographic analysis of the mixture, led to underestimation (or overestimation) of the component's proportion in the mixture by the model. In mixtures of closely related species with common PLFAs, the errors in the common components were adjusted across the species by the model. Biotechnol. Bioeng. 2007;96: 409,420. © 2006 Wiley Periodicals, Inc. [source] Development and optimization of a process for automated recovery of single cells identified by microengravingBIOTECHNOLOGY PROGRESS, Issue 3 2010Jae Hyeok Choi Abstract Microfabricated devices are useful tools for manipulating and interrogating large numbers of single cells in a rapid and cost-effective manner, but connecting these systems to the existing platforms used in routine high-throughput screening of libraries of cells remains challenging. Methods to sort individual cells of interest from custom microscale devices to standardized culture dishes in an efficient and automated manner without affecting the viability of the cells are critical. Combining a commercially available instrument for colony picking (CellCelector, AVISO GmbH) and a customized software module, we have established an optimized process for the automated retrieval of individual antibody-producing cells, secreting desirable antibodies, from dense arrays of subnanoliter containers. The selection of cells for retrieval is guided by data obtained from a high-throughput, single-cell screening method called microengraving. Using this system, 100 clones from a mixed population of two cell lines secreting different antibodies (12CA5 and HYB099-01) were sorted with 100% accuracy (50 clones of each) in ,2 h, and the cells retained viability. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Re: Outcome of pregnancies in women with pre-existent type 1 or 2 diabetes, in an ethnically mixed populationBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 4 2006Author's Reply No abstract is available for this article. [source] Outcomes of pregnancies in women with pre-existing type 1 or type 2 diabetes, in an ethnically mixed populationBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 11 2005Evelyn C.J. Verheijen Objective To compare the outcomes of pregnancies in women with pre-existing, type 1 and type 2, diabetes and to examine the influence of ethnicity on these outcomes. Design Prospective cohort study. Setting Large district hospital in Yorkshire with an ethnically mixed population. Sample Case series of all 202 pregnancies in women with pre-existing diabetes, ending in miscarriage, termination of pregnancy or delivery between January 1994 and December 2002. Methods Univariate and multivariate logistic regression analysis comparing outcomes in type of diabetes and in ethnic group. Main outcome measures Fetal loss, perinatal and infant mortality and congenital anomaly. Results All 14 stillbirths and infant deaths and 13 of the 15 congenital malformations were to Asian women. Analysis within this ethnic group showed a very high rate of adverse birth outcome for type 1 diabetic women and for type 2 diabetic women on insulin before the pregnancy. Total pregnancy loss among type 1 diabetic women was 156 per 1000 and among type 2 diabetic women on insulin was 167 per 1000. Congenital abnormality rates were 156 per 1000 for type 1 diabetic women and 261 per 1000 for type 2 diabetic women on insulin. Asian type 2 diabetic women not on insulin prior to pregnancy had significantly better outcomes: Total pregnancy loss was 123 per 1000 and congenital abnormality rate was 32 per 1000. After adjustment for confounders, including type of diabetes, Asian women had significantly worse outcomes (combined perinatal loss and malformation) than Caucasian women [odds ratio (OR) 4.96, 95% confidence interval (CI) 1.16,21.1]. Conclusion Ethnicity has a significant impact on the outcome of diabetic pregnancies, with worse outcomes for babies born to Asian mothers compared with Caucasian mothers. The use of insulin pre-pregnancy rather than type of diabetes appears to predict adverse outcome. [source] Risk indicators for hearing loss in infants treated in different Neonatal Intensive Care UnitsACTA PAEDIATRICA, Issue 3 2010P Van Dommelen Abstract Aim:, To assess which infants' characteristics and specialized procedures are risk indicators for unilateral or bilateral hearing loss (HL) and to evaluate whether these risk indicators are associated with variation in prevalence of HL between Neonatal Intensive Care Units (NICUs). Methods:, For 2002,2005, data from the NICU hearing screening database in the Netherlands were matched with the national neonatology database in which all NICU infants with their patient characteristics and specialized procedures are registered. Multivariate logistic regression analyses were performed to assess risk indicators for HL and to explain differences in prevalence rates between NICUs. Results:, A total of 10 830 infants were available for analyses. The prevalence of HL was 1.8% and ranged from 0.7 to 3.7% between NICUs. Infants' characteristics that significantly increased the risk of HL were the presence of craniofacial anomalies, chomosomal/syndromal anomalies, central nervous system conditions, circulatory system conditions and intra-uterine infections. The specialized procedures involving ,12 days of intensive care and high frequency oxygenation ventilation were independent risk indicators for HL. Approximately 20% of the variance can be explained by the studied risk indicators. Differences in prevalence rates between NICUs were slightly reduced after adjustment for these risk indicators. NICUs with the highest prevalence rates of HL were situated in the largest cities in the Netherlands with a mixed population because of immigration. Therefore, ethnicity may be a risk indicator. Conclusions:, Several independent risk indicators for HL were found, but they could not explain all differences in prevalence rates of HL between NICUs. [source] HYPERTENSION, OBESITY AND GNB3 GENE VARIANTSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 3 2006María E Danoviz SUMMARY 1The polymorphism C825T of the gene encoding the G-protein b3-subunit (GNB3) was found to be associated with an increased prevalence of hypertension in a number of studies. The aim of the present study was to investigate the association between this polymorphism and blood pressure phenotypes in an urban, large and ethnically mixed population of Brazil. 2Individuals (n = 1 568) were randomly selected from the general population of the Vitória City metropolitan area. The GNB3 C825T polymorphism was genotyped in each individual. Baseline cardiovascular risk factors were collected for all participants. Cardiovascular risk variables and genotypes were compared using anova and the Chi-squared test for univariate comparisons and logistic regression for multiple comparisons. 3A statistically significant interaction between the 825T allele and obesity was observed for systolic blood pressure (SBP; P = 0.02). In fact, the C825T genotype was predictive of SBP only in individuals with increased body mass index (P = 0.02). In addition, in a multiple logistic regression model conducted in the obese population and adjusted for age, sex, ethnicity, diabetes, triglycerides and total cholesterol, the presence of the T allele was significantly associated with a 1.5-fold (95% confidence interval 1.04,2.26) increased risk of hypertension. Lack of statistical power does not explain the absence of other positive gene,environment interactions. 4The present results suggest that an important gene ¥ environment interaction may take place between bodyweight regulation and the GNB3 gene. This finding provides further evidence for a role of the 825T allele in hypertension susceptibility and may be used for better disease stratification. [source] Cold tolerance in obligate and cyclical parthenogens of the peach-potato aphid, Myzus persicaeECOLOGICAL ENTOMOLOGY, Issue 4 2004Christoph Vorburger Abstract., 1. Many aphids form mixed populations of cyclical and obligate parthenogens. This is puzzling, because all else being equal, obligate parthenogens should outcompete cyclical parthenogens due to the two-fold cost of sex. Yet cyclical parthenogens produce frost-resistant, diapausing eggs in autumn, while obligate parthenogens spend the winter as active stages. Frost resistance thus represents a short-term advantage to sexual reproduction mediated by winter temperatures, which may promote this coexistence. 2. Because obligate parthenogens overwinter as active stages, there may be selection for increased cold tolerance compared to cyclical parthenogens. This has the potential to gradually erode the advantage of sexually producing eggs. 3. Four obligately and four cyclically parthenogenetic lines of Myzus persicae (Sulzer) (Hemiptera: Aphididae) were collected from each of two areas differing in winter severity, and their survival after exposure to a severe experimental frost (14 h at ,9 °C), as well as their reproductive performance at a low (10 °C) and a high (20 °C) temperature were compared. 4. There was significant variation among lines in survival after the experimental frost, but this variation was neither related to their reproductive mode, nor to their area of origin. Similarly, neither reproductive mode nor origin had a significant effect on reproductive performance, independent of temperature. The average slope of the response to variation in temperature was also similar for both reproductive modes, despite the fact that slopes differed significantly among lines. 5. Within the limits of extrapolating from laboratory experiments, it is concluded that in M. persicae, the active stages of obligate parthenogens are not better adapted to cold temperatures than those of cyclical parthenogens. [source] Localization of a putative low-penetrance ependymoma susceptibility locus to 22q11 using a chromosome 22 tiling-path genomic microarrayGENES, CHROMOSOMES AND CANCER, Issue 4 2005Anneke C. J. Ammerlaan Ependymomas frequently display allelic loss of chromosome 22 in the absence of mutations in the known tumor-suppressor genes on chromosome 22, suggesting the role of an alternative predisposing gene or genes from this chromosome. In an effort to localize these genes, 37 ependymomas derived from 33 patients were analyzed for the presence of copy number changes by use of a high-resolution chromosome 22 genomic microarray. Eighteen ependymomas (49%) displayed an array-CGH profile consistent with monosomy of chromosome 22. However, in 10 of these tumors, the fluorescence ratios for 22q clones scored as deleted were different from those at the single gene copy level. This suggests either analysis of mixed populations of tumor and normal stromal cells or analysis of mixed tumor cell populations with different genetic profiles. Four ependymomas derived from two patients showed overlapping interstitial deletions of 2.2 Mb and ,510 kb. Further analyses revealed that these deletions were present in the constitutional DNA of these two patients as well as in some of their unaffected relatives. Detailed microsatellite analysis of these families refined the commonly deleted segment to a region of 320 kb between markers RH13801 and D22S419. Our results provide additional evidence for the involvement of genes on chromosome 22 in the development of ependymoma and suggest the presence of a low-penetrance ependymoma susceptibility locus at 22q11. © 2005 Wiley-Liss, Inc. [source] Validation of the Chinese version of the MacNew Heart Disease Health-related Quality of Life questionnaireJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 2 2008Doris S. F. Yu RN PhD Abstract Rationale, Patient-reported outcomes such as health-related quality of life (HRQL) describe or characterize what patients have experienced as a result of their health care. However, treatment outcome comparisons among different pure or mixed populations of patients with myocardial infarction, angina or heart failure cannot be made using existing coronary heart disease (CHD)-specific HRQL instruments. Aims and objectives, The aim of this study was to evaluate the psychometric properties of the Chinese version of the MacNew in a cohort of Hong Kong patients diagnosed with CHD. Methods, Chinese translations of a CHD-specific HRQL instrument, the MacNew Heart Disease HRQL questionnaire (MacNew), the Short-form 36 Health Survey and the Hospital Anxiety and Depression Scale were administered to 365 Chinese-speaking patients with CHD at baseline and again 3 months later (n = 363). The Medical Outcomes Trust Scientific Advisory Committee criteria were used to examine the psychometric properties of the Chinese MacNew Heart Disease HRQL questionnaire. Results, The results warrant recommending the use of the MacNew as an outcome measure to enhance treatment evaluation in Chinese patients with CHD and a diagnosis of myocardial infarction, angina or heart failure, substantiating previous psychometric data on the MacNew in a number of different studies in patients speaking seven different languages. Conclusion, The MacNew questionnaire may have value as a core CHD questionnaire for treatment outcome comparisons among pure or mixed populations of patients with myocardial infarction, angina or heart failure. [source] Temporal dynamics of genotypic diversity reveal strong clonal selection in the aphid Myzus persicaeJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2006C. VORBURGER Abstract Parthenogenetic organisms often harbour substantial genotypic diversity. This diversity may be the result of recurrent formations of new clones, or it may be maintained by environmental heterogeneity acting on ecological differences among clones. In aphids, both processes may be important because obligate and cyclical parthenogens can form mixed populations. Using microsatellites, I analysed the temporal dynamics of clonal diversity in such a population of the aphid Myzus persicae over a 1-year period. The frequency distribution of clonal genotypes was very skewed, with many rare and few common clones. The relative frequencies of common clones underwent strong and rapid changes indicative of intense clonal selection. Differences in their host associations suggest that these shifts may partly be caused by changes in the abundance of annual host plants. Other selective factors of potential importance are also discussed. New, sexually produced genotypes made a minor contribution to clonal diversity, consistent with the observed heterozygote excess characteristic of predominantly asexual populations in M. persicae. [source] Competition between vectors of Chagas disease, Triatoma infestans and T. sordida: effects on fecundity and mortalityMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2004E. B. Oscherov Abstract., Interspecific competition between two species of triatomine bugs (Hemiptera: Reduviidae), vectors of Chagas disease, was assessed for 16 months through comparative fecundity and mortality of experimental populations in chicken nests, maintained indoors with ambient conditions. Triatoma sordida (Stål), the secondary vector in north-eastern Argentina, was compared with Triatoma infestans (Klug) the more widespread domestic vector in the southern cone of South America. Both species populations originated from females collected in 1995 from the community of Empedrado, Corrientes, Argentina. Three population units were monitored: T. infestans alone, T. sordida alone and both species together in equal proportions. Each population started with six male and six female adults, 116 eggs, and nymphal instars I to V numbering 82, 48, 16, 11 and 19, respectively. Numbers and weight of individual bugs were recorded monthly (August 1995 to December 1996). The pure populations of T. infestans and T. sordida showed temporal changes in abundance, rising in summer and falling in winter, similar to the typical trends under normal field conditions. In the mixed population, however, T. sordida fell to extinction after 6 months, whereas T. infestans reached similar abundance to the pure (control) population. For each nymphal instar of T. sordida, the mean body weight was significantly less and mortality rate was higher in the mixed population compared to the pure population, but there were no significant differences of adult longevity or fecundity between the pure and mixed populations of T. sordida. The apparent competitive displacement of T. sordida by T. infestans was attributed to the latter species having better ability to obtain bloodmeals. This might explain the rarity of mixed populations where these two species occur in sympatry. [source] Recurrent nuclear DNA introgression accompanies chloroplast DNA exchange between two eucalypt speciesMOLECULAR ECOLOGY, Issue 7 2010G. E. MCKINNON Abstract Numerous studies within plant genera have found geographically structured sharing of chloroplast (cp) DNA among sympatric species, consistent with introgressive hybridization. Current research is aimed at understanding the extent, direction and significance of nuclear (nr) DNA exchange that accompanies putative cpDNA exchange. Eucalyptus is a complex tree genus for which cpDNA sharing has been established between multiple species. Prior phylogeographic analysis has indicated cpDNA introgression into the widespread forest species Eucalyptus globulus from its rare congener E. cordata. In this study, we use AFLP markers to characterize corresponding nrDNA introgression, on both a broad and fine spatial scale. Using 388 samples we examine (i) the fine-scale spatial structure of cp and nrDNA introgression from E. cordata into E. globulus at a site in natural forest and (ii) broad-scale patterns of AFLP marker introgression at six additional mixed populations. We show that while E. globulus and E. cordata retain strongly differentiated nuclear gene pools overall, leakage of nrDNA occurs at mixed populations, with some AFLP markers being transferred to E. globulus recurrently at different sites. On the fine scale, different AFLP fragments show varying distances of introgression into E. globulus, while introgression of cpDNA is extensive. The frequency of E. cordata markers in E. globulus is correlated with spatial proximity to E. cordata, but departs from expectations based on AFLP marker frequency in E. cordata, indicating that selection may be governing the persistence of introgressed fragments in E. globulus. [source] Spatial repartition and genetic relationship of green and albino individuals in mixed populations of Cephalanthera orchidsPLANT BIOLOGY, Issue 4 2010V. Tranchida-Lombardo Abstract Several green orchids of the Neottieae tribe acquire organic carbon both from their mycorrhizal fungi and from photosynthesis. This strategy may represent an intermediate evolutionary step towards mycoheterotrophy of some non-photosynthetic (albino) orchids. Mixed populations of green and albino individuals possibly represent a transient evolutionary stage offering opportunities to understand the evolution of mycoheterotrophy. In order to understand the emergence of albinos, we investigated patterns of spatial and genetic relationships among green and albino individuals in three mixed populations of Cephalanthera damasonium and one of C. longifolia using spatial repartition and Amplified fragment length polymorphism (AFLP) markers. Two of these populations were monitored over two consecutive flowering seasons. In spatial repartition analyses, albino individuals did not aggregate more than green individuals. Genetic analyses revealed that, in all sampled populations, albino individuals did not represent a unique lineage, and that albinos were often closer related to green individuals than to other albinos from the same population. Genetic and spatial comparison of genets from the 2-year monitoring revealed that: (i) albinos had lower survival than green individuals; (ii) accordingly, albinos detected in the first year did not correspond to the those sampled in the second year; and (iii) with one possible exception, all examined albinos did not belong to any green genet from the same and/or from the previous year, and vice versa. Our results support a scenario of repeated insurgence of the albino phenotypes within the populations, but unsuccessful transition between the two contrasting phenotypes. Future studies should try to unravel the genetic and ecological basis of the two phenotypes. [source] Pollinators, flowering phenology and floral longevity in two Mediterranean Aristolochia species, with a review of flower visitor records for the genusPLANT BIOLOGY, Issue 1 2009R. Berjano Abstract The pollination of Aristolochia involves the temporary confinement of visitors inside the flower. A literature review has shown that some species are visited by one or a few dipteran families, while others are visited by a wider variety of dipterans, but only some of these are effective pollinators. We observed flowering phenology and temporal patterns of pollinator attendance in diverse populations of Aristolochia baetica and A. paucinervis, two species that grow in SW Spain, frequently in mixed populations. The two species had overlapping floral phenologies, extended flowering periods and long-lived flowers. A. baetica attracted a higher number of visitors than A. paucinervis. Drosophilids and, to a lesser extent, phorids, were the main pollinators of A. baetica, whereas in A. paucinervis, phorids were the only pollinators. Attendance to A. paucinervis flowers by phorids in mixed populations was markedly lower than in pure populations. This effect was more evident in years with lower pollinator density. Our results suggest that A. baetica and A. paucinervis may compete for pollinators in mixed populations. [source] | |||||||||||||||||||||||||||||||