bluuebunny/crossref_metadata_2025_split huggingface dataset:
SPERMATOGENESIS INCOLEOCHAETE PULVINATA(CHAROPHYCEAE): SPERM MATURATION1
Authors: Graham Linda E. , Wedemayer Gary J. 
Published: November 2004

ABSTRACTUltrastructural study showed that the sequence of developmental events occurring during spermatozoid maturation inColeochaete pulvinataBraun was similar in a number of respects to sperm development in the Charales and lower land plants. Elaboration of cytoskeletal components and associated flagellar basal bodies occurs early, and is followed by an extensive decrease in cytoplasmic volume and increases in densities of cytoplasm and nucleoplasm. Volume decrease and density increases appear to result from exocytosis involving dictyosome vesicles and perhaps endoplasmic reticulum. Elongation of flagella is accompanied by deposition of flagellar and body scales as in the Charales. During final stages of sperm maturation, the MLS undergoes changes in organization of the lamellar strip, which may also occur in archegoniates. In mature sperm ofC. pulvinatathe MLS and basal bodies are so occluded by dense material that determination of absolute orientation (configuration) is difficult. Thus, absolute orientation of the flagellar apparatus was determined by study of mid‐stage spermatids, and found to be the same as previously described by Sluiman for zoospores ofC. pulvinata.Finally, it is proposed that the large complex, striated fiber which connects basal bodies inC. pulvinatahas been evolutionarily reduced in the Charales andPhaeocerossp., ultimately disappearing from most embryophytic lines of descent.
VALVE MORPHOGENESIS IN THE PENNATE DIATOM ACHNANTHES COARCTATA
Authors: Boyle Judith A. , Pickett‐Heaps Jeremy D. , Czarnecki David B. 
Published: November 2004

ABSTRACTMitosis and valve morphogenesis in the pennate diatom Achnanthes coarctata (Bréb. in W. Sm.) Grun. are described. After cytokinesis, both daughter nuclei and their microtubule centers (MCs) are found near one side of the cell. Each new tubular silica deposition vesicle (SDV) arises centrally, forming a single rib running the length of the cell. Each MC then migrates around its nucleus and positions itself directly adjacent to the new SDV. The enlarging silicalemmas with their associated MCs, nuclei, microtubules (MTs) and microfilaments (MFs) appear in mirror image in the daughter cells. Both SDVs soon generate a second longitudinal rib alongside the first; the gap between the ribs ultimately becomes the future raphe fissure. The MC, MTs and nucleus are associated with each fissure. However, the subsequent behavior of the valve secreting machinery now becomes quite different in the daughter cells. In the cell that will form a raphid valve, the silicalemma, flanked by MFs, expands laterally in both directions over the cleavage furrow. Within the expanding SDV, silica secretion continues, eventually generating the structure of the mature valve, and during this phase the raphe fissure becomes delineated as in other raphid diatoms. In the other daughter cell, however, the MC and its MTs withdraw from the silicalemma, and the SDV moves laterally across the cleavage furrow until the double rib is at the corner of the cell. As silica is secreted into this expanding SDV, the raphe fissure completely fills in. This valve, therefore, lacks a raphe when mature and has a symmetry quite different from that of the valve formed in the other daughter cell. These events are compared with the course of morphogenesis described for other raphid diatoms.
DEMONSTRATION OF NET INFLUX OF FREE AMINO ACIDS IN PHAEODACTYLUM TRICORNUTUM USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY1
Authors: Lu Ming , Stephens Grover C. 
Published: November 2004

ABSTRACTInflux of glycine from dilute solution in the medium into Phaeodactylum tricornutum (Bohlin) was studied using radiochemical techniques. Comparison of these data with simultaneous measurements of the disappearance of primary amines from the medium by fluorometry indicates that influx of 14C‐labeled glycine accurately reflects net entry of substrate. High performance liquid chromatography (HPLC) was employed to demonstrate net removal of fourteen different amino acids from dilute solution by P. tricornutum. HPLC was also used to demonstrate net removal of free amino acids naturally present in sea water.
Impact of water quality on macroinvertebrate assemblages along a tropical stream in Kenya
Authors: Ndaruga Ayub M. , Ndiritu George G. , Gichuki Nathan N. , Wamicha W. N. 
Published: November 2004

AbstractPrudent management of lotic systems requires information on their ecological status that can be estimated by monitoring water quality and biodiversity attributes. To understand environmental conditions in Gatharaini drainage basin in Central Kenya, a study was carried out to establish the relationship between water quality and macroinvertebrate assemblages between the months of March and September 1996. Six sampling sites, each 25 m long were selected along a 24‐km stretch of the stream, which drained land under agricultural, residential and industrial use. Water physico‐chemical data was explored using multivariate analysis of Principal Component Analysis to detect environmental trends downstream. Both macroinvertebrates and water physico‐chemical data of suggested trends were analysed for variations and correlations. Temperatures and invertebrate densities changed significantly between the dry and wet season (P < 0.01) but the fluctuations were not evident downstream. Water physico‐chemical characteristics (total dissolved solids (TDS), pH, turbidity, dissolved oxygen) and biodiversity indices (species richness, diversity, dominance, evenness) changed markedly downstream (P < 0.01). Biodiversity indices correlated inversely with TDS, pH and turbidity but positively with dissolved O2. It was evident macroinvertebrate assemblages changed significantly downstream as opposed to functional feeding groups. Diptera was important in most sites whilst Oligochaeta dominance increased downstream corresponding to the deterioration in water quality. Collectors/browsers were the dominant functional feeding groups at most sites. This study showed that significant changes in aquatic macroinvertebrate assemblages were primarily due to water quality rather than prevailing climatic conditions.
Lack of a strong association between HLA class II, tumour necrosis factor and transporter associated with antigen processing gene polymorphisms and virological response to α‐interferon treatment in patients with chronic hepatitis C
Authors: Airoldi A. , Zavaglia C. , Silini E. , Tinelli C. , Martinetti M. , Asti M. , Rossini A. , Vangeli M. , Salvaneschi L. , Pinzello G. 
Published: November 2004

SummaryThe aim of the study was to investigate whether polymorphisms of the HLA class II, tumour necrosis factor (TNF) and transporter associated with antigen processing (TAP) genes influence the response to α‐interferon in patients with chronic hepatitis C. Twenty‐seven sustained responders and 55 non‐responders to α‐interferon monotherapy were investigated. HLA‐DRB1, DQA1, DQB1, TNFA, TNFB, TAP1 and TAP2 alleles were determined by PCR‐based molecular techniques. Sustained virological response was defined as undetectable serum hepatitis C virus (HCV) RNA for at least 3 years after the end of treatment. Probability (P) values were corrected for the number of alleles tested (Pc). Viral genotype 1b was more frequent in responders than in non‐responders (56% vs. 26%, P = 0.009). HLA‐DQB1*02 occurred less frequently in responders than in non‐responders (14.8% vs. 29%, Pc not significant). HLA‐DRB1*11 and DQB1*0602 were found in 22.2% and 9.3% of responders and in 10.9% and 1.8% of non‐responders, respectively (Pc not significant). There was no difference in the distribution of TNF alleles in the two groups. Twenty‐four (88.8%) responder patients as compared with 34 (61.8%) non‐responders were TAP1*0101 homozygous (Pc not significant). Thus, in European Caucasoids with chronic hepatitis C, we could not demonstrate a strong association between HLA class II, TNF, and TAP gene polymorphisms and response to interferon treatment.
Decomposition of soil and plant carbon from pasture systems after 9 years of exposure to elevated CO2: impact on C cycling and modeling
Authors: De Graaff Marie‐Anne , Six Johan , Harris David , Blum Herbert , Van Kessel Chris 
Published: November 2004

AbstractElevated atmospheric CO2 may alter decomposition rates through changes in plant material quality and through its impact on soil microbial activity. This study examines whether plant material produced under elevated CO2 decomposes differently from plant material produced under ambient CO2. Moreover, a long‐term experiment offered a unique opportunity to evaluate assumptions about C cycling under elevated CO2 made in coupled climate–soil organic matter (SOM) models. Trifolium repens and Lolium perenne plant materials, produced under elevated (60 Pa) and ambient CO2 at two levels of N fertilizer (140 vs. 560 kg ha−1 yr−1), were incubated in soil for 90 days. Soils and plant materials used for the incubation had been exposed to ambient and elevated CO2 under free air carbon dioxide enrichment conditions and had received the N fertilizer for 9 years. The rate of decomposition of L. perenne and T. repens plant materials was unaffected by elevated atmospheric CO2 and rate of N fertilization. Increases in L. perenne plant material C : N ratio under elevated CO2 did not affect decomposition rates of the plant material. If under prolonged elevated CO2 changes in soil microbial dynamics had occurred, they were not reflected in the rate of decomposition of the plant material. Only soil respiration under L. perenne, with or without incorporation of plant material, from the low‐N fertilization treatment was enhanced after exposure to elevated CO2. This increase in soil respiration was not reflected in an increase in the microbial biomass of the L. perenne soil. The contribution of old and newly sequestered C to soil respiration, as revealed by the 13C‐CO2 signature, reflected the turnover times of SOM–C pools as described by multipool SOM models. The results do not confirm the assumption of a negative feedback induced in the C cycle following an increase in CO2, as used in coupled climate–SOM models. Moreover, this study showed no evidence for a positive feedback in the C cycle following additional N fertilization.
Nitrous oxide and methane fluxes from soils of the Orinoco savanna under different land uses
Authors: Simona Castaldi , Ariangelo De Pascale Raffaele , John Grace , Nina Nikonova , Ruben Montes , José San José 
Published: November 2004

AbstractThe study investigates the effect of land‐use change on nitrous oxide (N2O) and methane (CH4) fluxes from soil, in savanna ecosystems of the Orinoco region (Venezuela). Gas fluxes were measured by closed static chambers, in the wet and dry season, in representative systems of land management of the region: a cultivated pasture, an herbaceous savanna, a tree savanna and a woodland (control site). Higher N2O emissions were observed in the cultivated pasture and in the herbaceous savanna compared with the tree savanna and the woodland, and differences were mainly related to fine soil particle content and soil volumetric water content measured in the studied sites. Overall N2O emissions were quite low in all sites (0–1.58 mg N2O‐N m−2 day−1). The cultivated pasture and the woodland savanna were on average weak CH4 sinks (−0.05±0.07 and −0.08±0.05 mg CH4 m−2 day−1, respectively), whereas the herbaceous savanna and the tree savanna showed net CH4 production (0.23±0.05 and 0.19±0.05 mg CH4 m−2 day−1, respectively). Variations of CH4 fluxes were mainly driven by variation of soil water‐filled pore space (WFPS), and a shift from net CH4 consumption to net CH4 production was observed at around 30% WFPS. Overall, the data suggest that conversion of woodland savanna to managed landscape could alter both CH4 and N2O fluxes; however, the magnitude of such variation depends on the soil characteristics and on the type of land management before conversion.
Nine polymorphic microsatellite loci for the fennel Pondweed Potamogeton pectinatus L.
Authors: NIES GEORG , REUSCH THORSTEN B. H. 
Published: November 2004

AbstractFennel (= Sago) pondweed (Potamogeton pectinatus L.) is a submersed macrophyte of nearly cosmopolitan distribution. The plant is of worldwide ecological importance as structuring component of shallow lakes, and as food for waterfowl. We developed nine polymorphic microsatellite primers for the population genetic analysis of P. pectinatus. The loci were identified using a GA/CT‐enriched genomic library using subtractive hybridization with magnetic particles. All nine loci were highly polymorphic with 6–9 alleles and heterozygosities ranging from 0.23 to 0.80 in a subset of N = 40 genotypes from five locations.
Isolation of 10 polymorphic microsatellite loci from Antirhea borbonica (Rubiaceae)
Authors: LITRICO I. , GILLES J. , SOURROUILLE P. , VIGNES H. 
Published: November 2004

AbstractWe report here the characteristics of 10 microsatellite markers isolated from a microsatellite‐enriched DNA library from Antirhea borbonica, Gmel (Rubiaceae). Antirhea borbonica is an endemic tree on the islands of La Réunion and Mauritius (Indian Ocean) where it occurs on young lava flows (fragmented and perturbed habitat) and in old primary forest. Ten polymorphic loci were characterized, with two to 15 alleles per locus, based on samples from six populations. These loci will be useful for analysing population structure in a metapopulation context where populations frequently go extinct.
Microsatellite DNA markers for the Stable Fly, Stomoxys calcitrans (Diptera: Muscidae)
Authors: GILLES J. , LITRICO I. , SOURROUILLE P. , DUVALLET G. 
Published: November 2004

AbstractEight polymorphic microsatellite markers have been isolated from a microsatellite‐enriched DNA library from the Stable Fly, Stomoxys calcitrans. These loci exhibited four to 15 alleles per locus and an expected heterozygosity ranging from 0.19 to 0.84 in the three populations studied from La Réunion island (Indian Ocean). They should therefore be valuable for studying genetic diversity and population structure. Cross‐species amplification of these eight loci in the closely allied species Stomoxys niger niger was successful for four of these loci, one of which was monomorphic and one of which strongly departed from Hardy–Weinberg expectations.
Development and characterization of nine new microsatellite markers in Taraxacum (Asteraceae)
Authors: VAŠUT RADIM J. , VAN DIJK PETER J. , FALQUE MATTHIEU , TRÁVNÍČEK BOHUMIL , DE JONG J. HANS 
Published: November 2004

AbstractThis study aims at developing and characterizing new microsatellite primer pairs in Taraxacum officinale auct. to produce polymorphic markers for genetical and evolutionary studies on apomixis in this sexual‐apomictic complex. A total of 24 diploid plants were tested for allelic polymorphism and heterozygosity. Out of nine loci three deviated significantly from the Hardy–Weinberg equilibrium expectations, probably due to the presence of null‐alleles. Successful cross‐species amplification was obtained for all markers in 29 Taraxacum microspecies from five sections.
Isolation of polymorphic tetranucleotide microsatellite markers for the little greenbul (Andropadus virens)
Authors: BARDELEBEN CAROLYNE 
Published: November 2004

AbstractThirteen polymorphic microsatellite markers have been developed for the little greenbul, Andropadus virens. The number of alleles range from two to 15 per locus with the observed heterozygosity ranging from 0.15 to 0.92. Eight sets of primers also amplify in closely related species, Andropadus laterostris and Andropadus tephrolaemus. These markers will be useful for analysis of questions concerning population genetic structure and models of speciation.
Isolation and characterization of polymorphic microsatellite loci in the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae)
Authors: KIM KYUNG SEOK , SAPPINGTON THOMAS W. 
Published: November 2004

AbstractThe boll weevil (Anthonomus grandis Boheman) is a major insect pest of cotton in North America. Dispersal activity poses a threat to ongoing eradication efforts in the US, but little is known about the frequency of long‐distance migration. Nuclear molecular markers are needed to assess gene flow in relation to geographical distance. A biotin‐enrichment strategy was employed to develop microsatellite markers for the boll weevil. Of 23 loci isolated, 14 were polymorphic with three to 10 alleles per locus. Twelve of the polymorphic loci showed Mendelian inheritance and are likely to be useful in population genetics studies.
genotypeandgenodive: two programs for the analysis of genetic diversity of asexual organisms
Authors: MEIRMANS PATRICK G. , VAN TIENDEREN PETER H. 
Published: November 2004

AbstractInvestigating diversity in asexual organisms using molecular markers involves the assignment of individuals to clonal lineages and the subsequent analysis of clonal diversity. Assignment is possible using a distance matrix in combination with a user‐specified threshold, defined as the maximum distance between two individuals that are considered to belong to the same clonal lineage. Analysis of clonal diversity requires tests for differences in diversity and clonal composition between populations. We developed two programs,genotypeandgenodivefor such analyses of clonal diversity in asexually reproducing organisms. Additionally,genotypecan be used for detecting genotyping errors in studies of sexual organisms.
Microsatellite loci from red sea urchins (Strongylocentrotus franciscanus)
Authors: MILLER K. M. , KAUKINEN K. H. , LABEREE K. , SUPERNAULT K. J. 
Published: November 2004

Abstract Strongylocentrotus franciscanus is a keystone marine herbivore in the Pacific North West of North America, that is commercially harvested for its roe in wild fisheries and is under development as an aquaculture species. We report the development of 11 novel, highly polymorphic di‐ and trinucleotide loci for use in population studies of this species. In a survey of over 200 individuals from three coastal sites in British Columbia, observed heterozygosities of the loci ranged from 0.39 to 0.85 and an average of 26 alleles per locus were resolved. Seven of the 11 microsatellite loci were in Hardy–Weinburg equiulibruim (HWE).
The use of imagination in professional education to enable learning about disadvantaged clients
Authors: Hall Valerie , Hart Angie 
Published: November 2004

AbstractProfessional education is delivered equally on campus and in practice placements but until lately, theories of learning and teaching in higher education have focused mainly on processing text‐based forms of knowledge. Even more recently introduced learning methods such as reflection and problem or enquiry based learning do not fully address the complex and often challenging learning needs of student health and social care professionals as they face the reality of everyday professional practice (Hall 2001). Working in a practice placement requires students to be able to make sense of the chaotic events going on around them that frequently evoke emotional responses, and challenge the individual's value and belief systems, which can lead to a changed outlook on life (Howard 2002). This means that the type of learning, which occurs in practice settings, is often implicit in nature and the knowledge gained is likely to be tacit making it difficult to share with others. However, what is learnt implicitly both within the placement and campus will have a significant impact on later practice and therefore we need a mechanism to ‘unlock’ this tacit knowledge.In this paper we propose that creative methods of learning such as developing the use of imagination may have more direct application in bringing into the public domain previous implicit learning experiences. As a means of exploring this issue we present our recent research (Hart et al. 2001), which assessed how qualified and pre qualified midwives are educationally prepared to work with disadvantaged women, an area of crucial importance, and one that is personally and professionally challenging. From the findings of this research we created a learning model which can be used by lecturers or practice educators either in the campus or practice settings. We conclude the paper with a discussion evaluating its fitness for enabling students to learn about disadvantaged clients.
In Vivo Activity of Enzymatic and Regulatory Components of the Phosphoenolpyruvate:Sugar Phosphotransferase System in
Mycoplasma pneumoniae
Authors: Halbedel Sven , Hames Claudine , Stülke Jörg 
Published: November 2004

ABSTRACT

Mycoplasma pneumoniae
is a pathogenic bacterium that is highly adapted to life on mucosal surfaces. This adaptation is reflected by the very compact genome and the small number of regulatory proteins. However,
M. pneumoniae
possesses the HPr kinase/phosphorylase (HPrK/P), the key regulator of carbon metabolism in the
Firmicutes
. In contrast to the enzymes of other bacteria, the HPrK/P of
M. pneumoniae
is already active at very low ATP concentrations, suggesting a different mode of regulation. In this work, we studied the ability of
M. pneumoniae
to utilize different carbohydrates and their effects on the activity of the different phosphotransferase system (PTS) components. Glucose served as the best carbon source, with a generation time of about 30 h. Fructose and glycerol were also used but at lower rates and with lower yields. In contrast,
M. pneumoniae
is unable to use mannitol even though the bacterium is apparently equipped with all the genes required for mannitol catabolism. This observation is probably a reflection of the continuing and ongoing reduction of the
M. pneumoniae
genome. The general enzymatic and regulatory components of the PTS, i.e., enzyme I, HPr, and HPrK/P, were present under all growth conditions tested in this study. However, HPrK/P activity is strongly increased if the medium contains glycerol. Thus, the control of HPrK/P in vivo differs strongly between
M. pneumoniae
and the other
Firmicutes
. This difference may relate to the specific conditions on lipid-rich cell surfaces.