bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic variation in the Desert Springsnail (Tryonia porrecta): implications for reproductive mode and dispersal
Authors: HERSHLER R. , MULVEY M. , LIU H.‐P. 
Published: April 2005

AbstractAllozymes and mitochondrial cytochrome c oxidase subunit I (mtCOI) sequences were analysed to determine whether populations of the western North American gastropod Tryonia porrecta (from California, Nevada, Utah, and northwest Mexico) are strongly differentiated in accordance with traditional interpretation of regional fauna as ancient relicts inhabiting isolated fragments of late Tertiary palaeodrainages. These data were also used to assess whether this species, for which males have not been recorded, is a rare example of a molluscan parthenogen. Both data sets strongly supported monophyly of T. porrecta populations. Five of the nine sampled populations consisted of a single monoallelic allozyme genotype while the others contained two to 10 distinct genotypes. Allozymic data for genetically diverse Utah populations provided evidence of clonal and sexual reproduction. mtCOI haplotypes of T. porrecta formed two subgroups which differed by 1.99–2.60%. The common haplotype was found in seven populations with rare haplotypes observed in single populations. Based on these results and an available mtCOI molecular clock for related hydrobiid snails, T. porrecta is interpreted as a primarily parthenogenetic species that undergoes occasional sexual reproduction and has accumulated substantial diversity following its mid‐Pliocene to mid‐Pleistocene origin. Our results also suggest that the distribution of present‐day populations of these gill‐breathing snails did not result from fragmentation of an ancient, well‐integrated drainage but instead reflects overland colonization of habitats which only recently became available following desiccation of late Quaternary pluvial lakes.
The effects of habitat fragmentation via forestry plantation establishment on spatial genotypic structure in the small marsupial carnivore, Antechinus agilis
Authors: BANKS S. C. , LINDENMAYER D. B. , WARD S. J. , TAYLOR A. C. 
Published: April 2005

AbstractDispersal is an important influence on species’ distributions, patch colonization and population persistence in fragmented habitat. We studied the impacts of habitat fragmentation resulting from establishment of an exotic pine plantation on dispersal of the marsupial carnivore, Antechinus agilis. We applied spatial analyses of individual multilocus microsatellite genotypes and mitochondrial haplotypes to study patterns of gene flow in fragmented habitat and natural habitat ‘control’ areas, and how this is affected by the spatial dispersion of habitat patches, the presence of corridors and a ‘mainland’ source of migrants. Spatial analysis of molecular variance and partial Mantel tests confirmed the absence of cryptic barriers to gene flow in continuous habitat, which if present would confound the comparison of genetic structures in fragmented vs. unfragmented habitats. Spatial genotypic structure suggested that although dispersal was male‐biased in both habitat types, fragmentation restricted dispersal of males more than that of females and the degree of restriction of male dispersal was dependent on the geographical isolation of the patch. The scale of positive genotypic structure in fragmented habitat was restricted to the two closest patches for females and the three closest patches for males. Our results provide evidence for significantly increased gene flow through habitat corridors relative to that across the matrix and for significantly lower gene flow between ‘mainland’ unfragmented habitat and habitat patches relative to that within either habitat type, suggesting a behavioural barrier to crossing habitat interfaces.
Mating patterns, pollen dispersal, and the ecological maternal neighbourhood in a Prunus mahaleb L. population
Authors: GARCÍA C. , ARROY J. M. , GODOY J. A. , JORDANO P. 
Published: April 2005

AbstractGender polymorphism, plant–animal interactions, and environmental heterogeneity are the three important sources of variation in mating system and pollen dispersal patterns. We used progeny arrays and paternity analysis to assess the effects of gender type and density level on variation in mating patterns within a highly isolated population of Prunus mahaleb, a gynodioecious species. All the adult trees in the population were sampled and located. The direct estimate of long‐distance insect‐mediated pollination events was low (< 10%). Gender expression deeply influenced the mating system, decreasing the outcrossing rates (tm) and the pollen pool diversity in hermaphrodite trees. Long intermate distances (> 250 m) were significantly more frequent among female mother trees. Variation in local tree density also affected pollen pool diversity and intermate distance, with a higher effective number of fathers (ke) and longer intermate distances for female trees in low‐density patches. A canonical correlation analysis showed significant correlations between mating variables and the maternal ecological neighbourhood. Only the first canonical variable was significant and explained 78% of variation. Outcrossing rates tended to decrease, and the relatedness among the fathers tended to increase, when mother trees grew in dense patches with high cover of other woody species and taller vegetation away from the pine forest edge. We highlight the relevance of considering maternal ecological neighbourhood effects on mating system and gene flow studies as maternal trees act simultaneously as receptors of pollen and as sources of the seeds to be dispersed.
Comparative analysis of population genetic structure in Athyrium distentifolium (Pteridophyta) using AFLPs and SSRs from anonymous and transcribed gene regions
Authors: WOODHEAD M. , RUSSELL J. , SQUIRRELL J. , HOLLINGSWORTH P. M. , MACKENZIE K. , GIBBY M. , POWELL W. 
Published: April 2005

AbstractTo examine the performance and information content of different marker systems, comparative assessment of population genetic diversity was undertaken in nine populations of Athyrium distentifolium using nine genomic and 10 expressed sequence tag (EST) microsatellite (SSR) loci, and 265 amplified fragment length polymorphism (AFLP) loci from two primer combinations. In range‐wide comparisons (European vs. North American populations), the EST‐SSR loci showed more reliable amplification and produced more easily scorable bands than genomic simple sequence repeats (SSRs). Genomic SSRs showed significantly higher levels of allelic diversity than EST‐SSRs, but there was a significant correlation in the rank order of population diversities revealed by both marker types. When AFLPs, genomic SSRs, and EST‐SSRs are considered, comparisons of different population diversity metrics/markers revealed a mixture of significant and nonsignificant rank–order correlations. However, no hard incongruence was detected (in no pairwise comparison of populations did different marker systems or metrics detect opposingly significant different amounts of variation). Comparable population pairwise estimates of FST were obtained for all marker types, but whilst absolute values for genomic and EST‐SSRs were very similar (FST = 0.355 and 0.342, respectively), differentiation was consistently higher for AFLPs in pairwise and global comparisons (global AFLP FST = 0.496). The two AFLP primer combinations outperformed 18 SSR loci in assignment tests and discriminatory power in phenetic cluster analyses. The results from marker comparisons on A. distentifolium are discussed in the context of the few other studies on natural plant populations comparing microsatellite and AFLP variability.
Metastasizing Seminal Vesicle Adenocarcinoma in a Wistar Rat
Authors: Teredesai A. , Wöhrmann T. 
Published: April 2005

SummaryAn adenocarcinoma in the seminal vesicles of a 15‐month‐old male Wistar rat from a 30‐month inhalation study is described. The rat was killed because of cachexia, apathy and a large palpable mass in the abdominal cavity. Macroscopic examination of the abdominal cavity revealed a 3.8 cm × 3.2 cm yellow‐grey to pink mass, firm to soft in consistency. The cut section revealed cystic spaces. Histologically, the mass consisted of epithelial cells arranged in glandular and solid patterns with abundant amounts of connective tissue. Epithelial tumour cells were round‐to‐cylindrical with round‐to‐oval basophilic nuclei and one or two prominent nucleoli and a distinct eosinophilic cytoplasm. The glandular structure contained clusters of macrophages in their lumen with eosinophilic cytoplasm and indented nuclei. Extensive necrosis and reactive inflammation were present. The histological features of the small nodules in the pancreas and on the surface of the liver, rectum and urinary bladder resembled those of the primary tumour in the seminal vesicles. Based on these criteria, the neoplasm (mass) was diagnosed as an adenocarcinoma of the seminal vesicles. The immunohistological examination confirmed the diagnosis, i.e. immunostaining was positive for cytokeratins (4, 7, 14, 15, 18, and 19), vimentin, PCNA, and ED1.
Systemic AA‐amyloidosis in a European Wild Boar (Sus scrofa) Suffering from Generalized Tuberculosis
Authors: Segalés J. , Vicente J. , Luján L. , Toussaint M. J. M. , Gruys E. , Gortázar C. 
Published: April 2005

SummaryAn adult female wild boar (Sus scrofa) was found moribund in Cabañeros National Park (central Spain). The animal had a markedly emaciated carcass, with body weight of 25.9 kg. At necropsy, most of the parenchymatous organs had widespread variably sized granulomas. Generalized tuberculosis was confirmed by PCR detection of Mycobacterium bovis in the mandibular lymph node. Large amounts of a hyaline, pale eosinophilic material were observed in liver, kidney and intestine. Congo red staining and green birefringence identified amyloid, which was further classified as AA type based on immunohistochemical results. It is speculated that the abundant serum amyloid A derivatives deposited in the tissues as AA‐amyloid may be associated with the generalized tuberculosis. This is the first report of amyloidosis in the European wild boar.
Awareness and use of smoking cessation treatments among diabetic patients
Authors: Gill G. V. , Morgan C. , MacFarlane I. A. 
Published: April 2005

AbstractAims  To investigate awareness of pharmacotherapeutic aids to smoking cessation in diabetic cigarette smokers.Methods  A structured questionnaire‐based interview was held by a research nurse individually with consecutively attending cigarette smokers.Results  Of 597 diabetic patients attending a routine clinic, 100 (17%) were current cigarette smokers. Mean (± sd) age was 58 ± 11 years, 58% were male, and 96% Type 2 diabetic patients. Mean daily cigarette consumption was 16/day, for a mean duration of 35 years. There were 34% who had never heard of nicotine replacement therapy (NRT), and of those who had, only 49% considered it safe with diabetes. Bupropion (Zyban) was unknown to 46%, and of those who knew of it, 39% thought it unsafe in diabetic patients. Only 31% of the group had been previously offered NRT, and 14% bupropion. The NHS Quitline was known of by 84%, but only 8% had used it.Conclusions  Cigarette smokers with diabetes have poor uptake, awareness and knowledge of NRT and bupropion as aids to smoking cessation. They comprise a high‐risk group, for large and small vessel disease, and these findings are therefore of concern. More active education and support for these patients by medical and nursing staff is needed.
Characterization of a Cluster of Three Glycosyltransferase Enzymes Essential for
Moraxella catarrhalis
Lipooligosaccharide Assembly
Authors: Edwards Katie J. , Allen Simon , Gibson Bradford W. , Campagnari Anthony A. 
Published: April 2005

ABSTRACT

Moraxella catarrhalis
isolates express lipooligosaccharide (LOS) molecules on their surface, which share epitopes similar to that of the
Neisseria
and
Haemophilus
species. These common LOS epitopes have been implicated in various steps of pathogenesis for the different organisms. In this study, a cluster of three LOS glycosyltransferase genes (
lgt
) were identified in
M. catarrhalis
7169, a strain that produces a serotype B LOS. Mutants in these glycosyltransferase genes were constructed, and the resulting LOS phenotypes were consistent with varying degrees of truncation compared to wild-type LOS. The LOS structures of each
lgt
mutant were no longer detected by a monoclonal antibody (MAb 4G5) specific to a highly conserved terminal epitope nor by a monoclonal antibody (MAb 3F7) specific to the serotype B LOS side chain. Mass spectrometry of the LOS glycoforms assembled by two of these
lgt
mutants indicated that
lgt1
encodes an α(1-2) glucosyltransferase and the
lgt2
encodes a β(1-4) galactosyltransferase. However, these structural studies could not delineate the function for
lgt3
. Therefore,
M. catarrhalis lgt3
was introduced into a defined β(1-4) glucosyltransferase
Haemophilus ducreyi
35000glu− mutant in
trans
, and monoclonal antibody analysis confirmed that Lgt3 complemented the LOS defect. These data suggest that
lgt3
encodes a glucosyltransferase involved in the addition of a β(1-4)-linked glucose to the inner core. Furthermore, we conclude that this enzymatic step is essential for the assembly of the complete LOS glycoform expressed by
M. catarrhalis
7169.
Characterization of PmfR, the Transcriptional Activator of the pAO1-Borne
purU-mabO-folD
Operon of
Arthrobacter nicotinovorans
Authors: Chiribau Calin B. , Sandu Cristinel , Igloi Gabor L. , Brandsch Roderich 
Published: April 2005

ABSTRACT

Nicotine catabolism by
Arthrobacter nicotinovorans
is linked to the presence of the megaplasmid pAO1. Genes involved in this catabolic pathway are arranged on the plasmid into gene modules according to function. During nicotine degradation γ-
N
-methylaminobutyrate is formed from the pyrrolidine ring of nicotine. Analysis of the pAO1 open reading frames (ORF) resulted in identification of the gene encoding a demethylating γ-
N
-methylaminobutyrate oxidase (
mabO
). This gene was shown to form an operon with
purU-
and
folD
-like genes. Only in bacteria grown in the presence of nicotine could transcripts of the
purU-mabO-folD
operon be detected, demonstrating that this operon constitutes part of the pAO1 nicotine regulon. Its transcriptional start site was determined by primer extension analysis. Transcription of the operon was shown to be controlled by a new transcriptional regulator, PmfR, the product of a gene that is transcribed divergently from the
purU
,
mabO
, and
folD
genes. PmfR was purified, and electromobility shift assays and DNase I-nuclease digestion experiments were used to determine that its DNA binding site is located between −48 and −88 nucleotides upstream of the transcriptional start site of the operon. Disruption of
pmfR
by homologous recombination with a chloramphenicol resistance cassette demonstrated that PmfR acts in vivo as a transcriptional activator. Mutagenesis of the PmfR target DNA suggested that the sequence GTTT-14 bp-AAAC is the core binding site of the regulator upstream of the −35 promoter region of the
purU-mabO-folD
operon.
Phosphorylation-Independent Activity of Atypical Response Regulators ofHelicobacter pylori
Authors: Schär Jennifer , Sickmann Albert , Beier Dagmar 
Published: April 2005

ABSTRACTThe genome of the gastric pathogenHelicobacter pyloriharbors a remarkably low number of regulatory genes, including three and five open reading frames encoding two-component histidine kinases and response regulators, respectively, which are putatively involved in transcriptional regulation. Two of the response regulator genes, hp1043 and hp166, proved to be essential for cell growth, and inactivation of the response regulator gene hp1021 resulted in a severe growth defect, as indicated by a small-colony phenotype. The sequences of the receiver domains of response regulators HP1043 and HP1021 differ from the consensus sequence of the acidic pocket of the receiver domain which is involved in the phosphotransfer reaction from the histidine kinase to the response regulator. Using a genetic complementation system, we demonstrated that the function of response regulator HP166, which is essential for cell growth, can be provided by a mutated derivative carrying a D52N substitution at the site of phosphorylation. We found that the atypical receiver sequences of HP1043 and HP1021 are not crucial for the function of these response regulators. Phosphorylation of the receiver domains of HP1043 and HP1021 is not needed for response regulator function and may not occur at all. Thus, the phosphorylation-independent action of these regulators differs from the well-established two-component paradigm.
Isolation of Lactococcal Prolate Phage-Phage Recombinants by an Enrichment Strategy Reveals Two Novel Host Range Determinants
Authors: Rakonjac Jasna , O'Toole Paul W. , Lubbers Mark 
Published: April 2005

ABSTRACT

Virulent lactococcal prolate (or c2-like) phages are the second most common phage group that causes fermentation failure in the dairy industry. We have mapped two host range determinants in two lactococcal prolate phages, c2 and 923, for the host strains MG1363 and 112. Each phage replicates on only one of the two host strains: c2 on MG1363 and 923 on 112. Phage-phage recombinants that replicated on both strains were isolated by a new method that does not require direct selection but rather employs an enrichment protocol. After initial mixed infection of strain 112, two rotations, the first of which was carried out on strain MG1363 and the second on 112, permitted continuous amplification of double-plating recombinants while rendering one of the parent phages unamplified in each of the two rotations. Mapping of the recombination endpoints showed that the presence of the N-terminal two-thirds of the tail protein L10 of phage c2 and a 1,562-bp
cosR
-terminal fragment of phage 923 genome overcame blocks of infection in strains MG1363 and 112, respectively. Both infection inhibition mechanisms act at the stage of DNA entry; in strain MG1363, the infection block acts early, before phage DNA enters the cytoplasm, and in strain 112, it acts late, after most of the DNA has entered the cell but before it undergoes
cos
-end ligation. These are the first reported host range determinants in bacteriophage of lactic acid bacteria required for overcoming inhibition of infection at the stage of DNA entry and
cos
-end ligation.
Staphylococcus intermedius
Produces a Functional
agr
Autoinducing Peptide Containing a Cyclic Lactone
Authors: Ji Guangyong , Pei Wuhong , Zhang Linsheng , Qiu Rongde , Lin Jianqun , Benito Yvonne , Lina Gerard , Novick Richard P. 
Published: April 2005

ABSTRACT

The
agr
system is a global regulator of accessory functions in staphylococci, including genes encoding exoproteins involved in virulence. The
agr
locus contains a two-component signal transduction module that is activated by an autoinducing peptide (AIP) encoded within the
agr
locus and is conserved throughout the genus. The AIP has an unusual partially cyclic structure that is essential for function and that, in all but one case, involves an internal thiolactone bond between a conserved cysteine and the C-terminal carboxyl group. The exceptional case is a strain of
Staphylococcus intermedius
that has a serine in place of the conserved cysteine. We demonstrate here that the
S. intermedius
AIP is processed by the
S. intermedius
AgrB protein to generate a cyclic lactone, that it is an autoinducer as well as a cross-inhibitor, and that all of five other
S. intermedius
strains examined also produce serine-containing AIPs.
The Active Site of
O-
Acetylserine Sulfhydrylase Is the Anchor Point for Bienzyme Complex Formation with Serine Acetyltransferase
Authors: Huang Bin , Vetting Matthew W. , Roderick Steven L. 
Published: April 2005

ABSTRACT

The biosynthesis of cysteine in bacteria and plants is carried out by a two-step pathway, catalyzed by serine acetyltransferase (SAT) and
O
-acetylserine sulfhydrylase (OASS;
O-
acetylserine [thiol] lyase). The aerobic form of OASS forms a tight bienzyme complex with SAT in vivo, termed cysteine synthase. We have determined the crystal structure of OASS in complex with a C-terminal peptide of SAT required for bienzyme complex formation. The binding site of the peptide is at the active site of OASS, and its C-terminal carboxyl group occupies the same anion binding pocket as the α-carboxylate of the
O
-acetylserine substrate of OASS. These results explain the partial inhibition of OASS by SAT on complex formation as well as the competitive dissociation of the complex by
O
-acetylserine.
Multistress Regulation inEscherichia coli: Expression ofosmBInvolves Two Independent Promoters Responding either to σSor to the RcsCDB His-Asp Phosphorelay
Authors: Boulanger Alice , Francez-Charlot Anne , Conter Annie , Castanié-Cornet Marie-Pierre , Cam Kaymeuang , Gutierrez Claude 
Published: April 2005

ABSTRACTTranscription of theEscherichia coli osmBgene is induced by several stress conditions.osmBis expressed from two promoters,osmBp1andosmBp2. The downstream promoter,osmBp2, is induced after osmotic shock or upon entry into stationary phase in a σS-dependent manner. The upstream promoter,osmBp1, is independent of σSand is activated by RcsB, the response regulator of the His-Asp phosphorelay signal transduction system RcsCDB. RcsB is responsible for the induction ofosmBp1following treatment with chlorpromazine. Activation ofosmBp1by RcsB requires a sequence upstream of its −35 element similar to the RcsB binding site consensus, suggesting a direct regulatory role.osmBappears as another example of a multistress-responsive gene whose transcription involves both a σS-dependent promoter and a second one independent of σSbut controlled by stress-specific transcription factors.
Arc and resistance welding and tumours of the endocrine glands: a Swedish case-control study with focus on extremely low frequency magnetic fields
Authors: Håkansson N , Stenlund C , Gustavsson P , Johansen C , Floderus B 
Published: April 2005

Background:Mechanisms for potential effects of extremely low frequency (ELF) magnetic fields on carcinogenesis have not been identified. A potential pathway could be an interaction with the endocrine system.Aims:To analyse occupational exposure to ELF magnetic fields from welding, and tumours of the endocrine glands.Methods:This case-control study was based on a cohort with an increased prevalence of high exposed individuals. A total of 174 incident cases of tumours of the endocrine glands, 1985–94, were identified and data were obtained from 140 (80%) of these cases; 1692 controls frequency matched on sex and age were selected, and information on 1306 (77%) individuals was obtained. A short questionnaire was sent to a work administrator at the workplaces of the cases and controls. The exposure assessment was based on questions about job tasks, exposure to different types of welding, and exposure to solvents.Results:There was an overall increased risk for all tumours of the endocrine glands for individuals who had been welding sometime during the follow up. The increased risk was attributable to arc welding; for resistance welding there was no clear evidence of an association. We found an increased risk for the adrenal glands in relation to arc welding, and for the parathyroid glands in relation to both arc welding and resistance welding. An imprecise increase in risk was also noted for tumours of the pituitary gland for arc welding. No confounding effect was found for solvent exposure, and there was no sign of biological interaction.Conclusion:The increased risks of endocrine gland tumours related to welding might be explained by exposure to high levels of ELF magnetic fields.