bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contrasting phylogeography in three endemic Hawaiian limpets (Cellana spp.) with similar life histories
Authors: BIRD CHRISTOPHER E. , HOLLAND BRENDEN S. , BOWEN BRIAN W. , TOONEN ROBERT J. 
Published: July 2007

AbstractThe marine environment offers few obvious barriers to dispersal for broadcast‐spawning species, yet population genetic structure can occur on a scale much smaller than the theoretical limits of larval dispersal. Comparative phylogeographical studies of sympatric sister species can illuminate how differences in life history, behaviour, and habitat affinity influence population partitioning. Here we use a mitochondrial DNA marker (612 bp of cytochrome c oxidase subunit I) to investigate population structure of three endemic Hawaiian broadcast‐spawning limpets (Cellana spp.) with planktonic larvae that are competent to settle within 4 days. All three species exhibit significant population structure and isolation by distance, but the spatial scales of partitioning differ among the species. Cellana talcosa (n = 105) exhibits strong population structure between Kauai and the other main Hawaiian Islands (MHI) where the maximum channel width is 117 km, and no shared haplotypes were observed (ΦCT = 0.30, P < 0.001). In contrast, populations of Cellana exarata (n = 149) and Cellana sandwicensis (n = 109) exhibit weaker population structure within the MHI (ΦST = 0.03–0.04, P < 0.05), and between the MHI and the Northwestern Hawaiian Islands (ΦST = 0.03–0.09, P < 0.01), where the maximum channel width is 260 km. Biogeographical range and microhabitat use were correlated with estimates of dispersal, while phylogenetic affiliation and minimum pelagic larval duration were poor predictors of population partitioning. Despite similar life histories, these closely related limpets have contrasting patterns of population structure, illustrating the danger of relying on model species in management initiatives to predict population structure and dispersal in the context of marine protected area delineation.
Invasion of host cells by malaria parasites: a tale of two protein families
Authors: Iyer Jayasree , Grüner Anne Charlotte , Rénia Laurent , Snounou Georges , Preiser Peter R. 
Published: July 2007

SummaryMalaria parasites are obligate intracellular parasites whose invasive stages select and invade the unique host cell in which they can develop with exquisite specificity and efficacy. Most studies aimed at elucidating the molecules and the mechanisms implicated in the selection and invasion processes have been conducted on the merozoite, the stage that invades erythrocytes to perpetuate the pathological cycles of parasite multiplication in the blood. Bioinformatic analysis has helped identify the members of two parasite protein families, the reticulocyte‐binding protein homologues (RBL) and erythrocyte binding like (EBL), in recently sequenced genomes of different Plasmodium species. In this article we review data from classical studies and gene disruption experiments that are helping to illuminate the role of these proteins in the selection‐invasion processes. The manner in which subsets of proteins from each of the families act in concert suggests a model to explain the ability of the parasites to use alternate pathways of invasion. Future perspectives and implications are discussed.
FourU: a novel type of RNA thermometer in Salmonella
Authors: Waldminghaus Torsten , Heidrich Nadja , Brantl Sabine , Narberhaus Franz 
Published: July 2007

SummaryThe translation of many heat shock and virulence genes is controlled by RNA thermometers. Usually, they are located in the 5′‐untranslated region (5′‐UTR) and block the Shine‐Dalgarno (SD) sequence by base pairing. Destabilization of the structure at elevated temperature permits ribosome binding and translation initiation. We have identified a new type of RNA thermometer in the 5′‐UTR of the Salmonella agsA gene, which codes for a small heat shock protein. Transcription of the agsA gene is controlled by the alternative sigma factor σ32. Additional translational control depends on a stretch of four uridines that pair with the SD sequence. Mutations in this region affect translation in vivo. Structure probing experiments demonstrate a temperature‐controlled opening of the SD region in vitro. Toeprinting (primer extension inhibition) shows that ribosome binding is dependent on high temperatures. Together with a postulated RNA thermometer upstream of the Yersinia pestis virulence gene lcrF (virF), the 5′‐UTR of Salmonella agsA might be the founding member of a new class of RNA thermometers that we propose to name ‘fourU’ thermometers.
The response regulator SsrB activates expression of diverse Salmonella pathogenicity island 2 promoters and counters silencing by the nucleoid‐associated protein H‐NS
Authors: Walthers Don , Carroll Ronan K. , Navarre William Wiley , Libby Stephen J. , Fang Ferric C. , Kenney Linda J. 
Published: July 2007

SummaryThe two‐component system SsrA–SsrB activates expression of a type III secretion system required for replication in macrophages and systemic infection in mice. Here we characterize the SsrB‐dependent regulation of genes within Salmonella pathogenicity island 2 (SPI‐2). Primer extension and DNase I footprinting identified multiple SsrB‐regulated promoters within SPI‐2 located upstream of ssaB, sseA, ssaG and ssaM. We previously demonstrated that ssrA and ssrB transcription is uncoupled. Overexpression of SsrB in the absence of its cognate kinase, SsrA, is sufficient to activate SPI‐2 transcription. Because SsrB requires phosphorylation to relieve inhibitory contacts that occlude its DNA‐binding domain, additional components must phosphorylate SsrB. SPI‐2 promoters examined in single copy were highly SsrB‐dependent, activated during growth in macrophages and induced by acidic pH. The nucleoid structuring protein H‐NS represses horizontally acquired genes; we confirmed that H‐NS is a negative regulator of SPI‐2 gene expression. In the absence of H‐NS, the requirement for SsrB in activating SPI‐2 genes is substantially reduced, suggesting a role for SsrB in countering H‐NS silencing. SsrB activates transcription of multiple operons within SPI‐2 by binding to degenerate DNA targets at diversely organized promoters. SsrB appears to possess dual activities to promote SPI‐2 gene expression: activation of transcription and relief of H‐NS‐mediated repression.
Disruption of iron homeostasis in Saccharomyces cerevisiae by high zinc levels: a genome‐wide study
Authors: Pagani M. Ayelen , Casamayor Antonio , Serrano Raquel , Atrian Sílvia , Ariño Joaquín 
Published: July 2007

SummaryZinc is an essential metal that, when in excess, can be deleterious to the cell. Therefore, homeostatic mechanisms for this cation must be finely tuned. To better understand the response of yeast in front of an excess of zinc, we screened a systematic deletion mutant library for altered growth in the presence of 6 mM zinc. Eighty‐nine mutants exhibited increased zinc sensitivity, including many genes involved in vacuolar assembling and biogenesis. Interestingly, a mutant lacking the Aft1 transcription factor, required for the transcriptional response to iron starvation, was found to be highly sensitive to zinc. Genome‐wide transcriptional profiling revealed that exposure to 5 mM ZnCl2 results in rapid increase in the expression of numerous chaperones required for proper protein folding or targeting to vacuole and mitochondria, as well as genes involved in stress response (mainly oxidative), sulphur metabolism and some components of the iron regulon. The effect of the lack of Aft1 both in the absence and in the presence of zinc overload was also investigated. Exposure to high zinc generated reactive oxygen species and markedly decreased glutathione content. Interestingly, zinc excess results in decreased intracellular iron content and aconitase and cytochrome c activities in stationary‐phase cultures. These findings suggest that high zinc levels may alter the assembly and/or function of iron–sulphur‐containing proteins, as well as the biosynthesis of haem groups, thus establishing a link between zinc, iron and sulphur metabolism.
Polyphosphate kinase is involved in stress‐induced mprAB‐sigE‐rel signalling in mycobacteria
Authors: Sureka Kamakshi , Dey Supratim , Datta Pratik , Singh Anil Kumar , Dasgupta Arunava , Rodrigue Sébastien , Basu Joyoti , Kundu Manikuntala 
Published: July 2007

SummaryPolyphosphate kinase 1 (PPK1) helps bacteria to survive under stress. The ppk1 gene of Mycobacterium tuberculosis was overexpressed in Escherichia coli and characterized. Residues R230 and F176, predicted to be present in the head domain of PPK1, were identified as residues critical for polyphosphate (polyP)‐synthesizing ability and dimerization of PPK1. A ppk1 knockout mutant of Mycobacterium smegmatis was compromised in its ability to survive under long‐term hypoxia. The transcription of the rel gene and the synthesis of the stringent response regulator ppGpp were impaired in the mutant and restored after complementation with ppk1 of M. tuberculosis, providing evidence that PPK1 is required for the stringent response. We present evidence that PPK1 is likely required for mprAB‐sigE‐rel signalling. σE regulates the transcription of rel, and we hypothesize that under conditions of stress polyP acts as a preferred donor for MprB‐mediated phosphorylation of MprA facilitating transcription of the sigE gene thereby leading finally to the enhancement of the transcription of rel in M. smegmatis and M. tuberculosis. Downregulation of ppk1 led to impaired survival of M. tuberculosis in macrophages. PolyP plays a central role in the stress response of mycobacteria.
Chromium nanoparticle exhibits higher absorption efficiency than chromium picolinate and chromium chloride in Caco‐2 cell monolayers
Authors: Zha L.‐Y. , Xu Z.‐R. , Wang M.‐Q. , Gu L.‐Y. 
Published: July 2007

SummaryThis study was conducted to determine whether chromium nanoparticle (CrNano) exhibited higher absorption efficiency and possessed unique absorption mechanism in comparison to chromium picolinate (CrPic) and chromium chloride (CrCl3), as was postulated by previous reports. Twenty‐one‐day‐old Caco‐2 cell monolayers grown on semipermeable membranes in Snapwell tissue culture bichambers were incubated with CrNano, CrPic or CrCl3 to examine their transport and uptake respectively. In the concentration range of 0.2–20 μmol/l, transport of CrNano, CrPic and CrCl3 across Caco‐2 monolayers both in apical‐to‐basolateral and basolateral‐to‐apical direction was concentration‐, and time‐dependent, and temperature independent. The apparent permeability coefficient (Papp) of CrNano was between 5.89 and 7.92 × 10−6 cm/s and that of CrPic and CrCl3 was between 3.52 and 5.31 × 10−6 cm/s and between 0.97 and 1.37 × 10−6 cm/s respectively. Uptake of CrNano, CrPic and CrCl3 by both apical and basolateral membranes was concentration‐ and time‐dependent. Uptake of CrNano by apical membrane was significantly (p < 0.05) decreased when the incubation temperature was reduced from 37 °C to 4 °C. The transport efficiency of CrNano, CrPic and CrCl3 after incubation for 120 min at 37 °C was 15.83% ± 0.76%, 9.08% ± 0.25% and 2.11% ± 0.53% respectively. The uptake efficiency of CrNano, CrPic and CrCl3 was 10.08% ± 0.76%, 4.73% ± 0.60% and 0.88% ± 0.08% respectively. It was concluded that the epithelial transport of CrNano, CrPic and CrCl3 across the Caco‐2 cell monolayers was mainly via passive transport pathways. In addition, CrNano exhibited considerably higher absorption efficiency than both CrPic and CrCl3 in Caco‐2 cell monolayers.
Mineral balance in horses fed two supplemental silicon sources
Authors: O'Connor C. I. , Nielsen B. D. , Woodward A. D. , Spooner H. S. , Ventura B. A. , Turner K. K. 
Published: July 2007

SummaryNumerous studies suggest that silicon (Si) supplementation is beneficial for mineral metabolism and bone health. Mineral balance studies have not been performed in horses to determine how these supplements affect absorption of other minerals. The purpose of these studies was to investigate the effects of two different Si supplements on mineral absorption and retention in horses. Eight geldings were randomly placed in one of two groups: control (CO) or supplemental Si, which was provided by one of two supplements. The first, sodium aluminium silicate (SA), contains a bioavailable form of Si and is high in aluminium (Al). The second supplement contains oligomeric orthosilicic acid (OSA). All horses received textured feed and ad libitum access to hay. Supplemented horses received either 200 g of SA or 28.6 ml of OSA per day. Following a 10‐day adaptation period, the horses underwent a 3‐day total collection. Blood samples were taken on days 0 and 13. The two balance studies were conducted 4 months apart to reduce carryover effects. Intakes of Al and Si were greater with SA supplementation (p < 0.05). Sodium aluminium silicate increased faecal and urinary Si excretion (p < 0.05). Calcium retention and apparent digestion were increased by SA (p < 0.05). It also maintained plasma Si compared with the CO which tended to have a decrease in plasma Si (p = 0.08). Supplemental OSA increased retention of Ca and B (p < 0.05) and apparent digestion of B (p < 0.01). Orthosilicic acid tended to increase Si retention (p = 0.054), apparent digestion (p < 0.065), and also increased plasma Si. Both supplements were able to alter Ca retention and B metabolism, however, only OSA was able to alter Si retention, digestibility and plasma concentration. Orthosilicic acid, an Si supplement without substantial Al, appears to be a viable option for Si supplementation as it increased Si retention and digestibility.
Reversible optic neuropathy due to metronidazole
Authors: McGrath Nicole M , Kent‐Smith Brian , Sharp Dianne M 
Published: July 2007

AbstractMetronidazole is a little known cause of drug‐induced optic neuropathy. We report a patient who developed progressive visual loss after an 8‐month course of Metronidazole. Electrophysiology confirmed a bilateral optic neuropathy. Her vision improved dramatically with cessation of the drug.
Macular hole formation, spontaneous closure, and reopening in severe hypertensive chorioretinopathy
Authors: Park Young‐Hoon , Kim Su Young , Lee Young‐Chun 
Published: July 2007

AbstractMacular hole is rarely reported in severe hypertensive chorioretinopathy, and spontaneous closure of a macular hole is uncommon. We report a case of reopening after spontaneous closure of a full‐thickness macular hole in a patient with severe hypertensive chorioretinopathy.
Altered face scanning and impaired recognition of biological motion in a 15‐month‐old infant with autism
Authors: Klin Ami , Jones Warren 
Published: July 2007

AbstractMounting clinical evidence suggests that abnormalities of social engagement in children with autism are present even during infancy. However, direct experimental documentation of these abnormalities is still limited. In this case report of a 15‐month‐old infant with autism, we measured visual fixation patterns to both naturalistic and ambiguous social stimuli: video scenes of a caregiver and point‐light animations of human action. Results suggested that viewing patterns of the child with autism were driven by the physical contingencies of the stimuli rather than by their social context. If corroborated in larger studies, this observation would advance the hypothesis that mechanisms of social development which rely on preferential engagement with socially contingent conspecifics – and which emerge in the very first weeks of life in typical infants – are developmentally derailed in children with autism.
Insulin resistance: central and peripheral mechanisms. The 2007 Stock Conference Report
Authors: Ye J. , Kraegen T. 
Published: July 2007

SummaryInsulin resistance in peripheral tissues and in the brain are fundamental to the development of obesity and its associated type 2 diabetes. Multiple mechanisms contribute to the development of insulin resistance. The 2007 Stock Conference focused on the role of fatty acids and other lipid signals in initiating insulin resistance and the consequences of central insulin resistance to the regulation of energy balance and peripheral metabolism.
The use of vaginal antimicrobial after large loop excision of transformation zone: a prospective randomised trial
Authors: Chan KKL , Tam KF , Tse KY , Ngan HYS 
Published: July 2007

Objective To investigate whether the use of an antibacterial vaginal pessary containing tetracycline and amphotericin B would reduce complications from large loop excision of the transformation zone (LLETZ). Design Prospective randomised controlled trial. Setting Department of Obstetrics and Gynaecology, University of Hong Kong. Population A total of 321 women who underwent LLETZ. Methods Women were randomised to either receiving an antimicrobial vaginal pessary twice a day for 14 days after LLETZ or no medication. Before LLETZ, endocervical and high vaginal swabs were taken for the detection of Chlamydia and other pathogens. All women were given a diary to record the degree of symptoms, such as vaginal discharge, bleeding and pain for 3 weeks. These were then compared between the two groups. Main outcome measures Bleeding, vaginal discharge and pain after LLETZ. Results There was no significant difference in the total bleeding, vaginal discharge and pain scores between the two groups. However, for women who had positive endocervical or high vaginal swabs, the treatment group had significantly less bleeding in the second week (Z=−2.083, P= 0.037) and less overall vaginal discharge (Z=−2.024, P= 0.043). Conclusions An antimicrobial vaginal pessary containing tetracycline and amphotericin B did not provide any significant benefit after LLETZ, except for a subgroup of women with positive vaginal or endocervical swabs. Given that this group of women cannot be identified before the procedure since swabs are not routinely taken, the use of routine prophylactic topical antibiotics cannot be recommended for the general population.
Development, characterization and transferability of microsatellite markers for the plant genus Phlox (Polemoniaceae)
Authors: FEHLBERG SHANNON D. , FORD KRISTEN A. , UNGERER MARK C. , FERGUSON CAROLYN J. 
Published: July 2007

AbstractIn order to study diversification and microevolution in Phlox, we developed nine polymorphic microsatellite loci. In 20 individuals of Phlox pilosa from a single population, the average number of alleles per locus was 10.0 ± 5.1, and average observed and expected heterozygosities were 0.611 ± 0.234 and 0.769 ± 0.170, respectively. Most of these markers amplified successfully in 11 additional species of Phlox, representing a broad diversity of the genus, and some also amplified in more distantly related members of the Polemoniaceae. These microsatellite markers will be valuable for investigation of evolutionary processes in this important study system.
Antioxidant properties of hesperidin in nicotine‐induced lung toxicity
Authors: Balakrishnan Annida , Menon Venugopal P. 
Published: July 2007

AbstractNicotine, the principal alkaloid in tobacco, is generally considered to be an active pharmacological agent responsible for lung‐related disorders. The actions of nicotine have been extensively investigated in animal and variety of cell systems. Nicotine is known to induce the lipid peroxidation by producing reactive oxygen species and reactive nitrogen species. In the present study, we have investigated the effect of hesperidin on nicotine toxicity. The parameters studied were marker enzymes and antioxidant status in blood, tissues, BAL (bronchoalveolar lavage cells) and BALF (bronchoalveolar lavage fluid). Lung damage was induced by subcutaneous injection of nicotine at a dosage of 2.5 mg/kg body weight for 5 days a week. Hesperidin was administered orally at a dose of 25 mg/kg body weight. The results showed an increase in the level of marker enzymes and decrease in the antioxidant status in nicotine‐treated rats. Hesperidin treatment resulted in a decreased level of all the marker enzymes and the antioxidant status was brought back to near normal. Thus the study shows that hesperidin offers protection against the lung damage caused by nicotine.
Forecasting “friends forever”: A longitudinal investigation of sustained closeness between best friends
Authors: LEDBETTER ANDREW M , GRIFFIN EM , SPARKS GLENN G. 
Published: July 2007

AbstractUsing data collected across 19 years, the chief goal of this study was to discover predictors of continued relational closeness between best friends. Participants were same‐sex and cross‐sex best friend pairs recruited from a small Midwestern college. In 1983, participants completed several tests and activities designed to assess facets of intimacy, with follow‐up studies in 1987 and 2002 measuring relational closeness. Regression analysis indicates that both manifest similarity and months of closeness in 1983 are associated with relational closeness in 2002. These results suggest that the investment of resources in the friendship and similarity between friends facilitate friendship longevity and that Kelley et al.’s (1983) conceptualization of closeness as related to interdependence is empirically robust.
A standardised ultrasonic diagnosis and an accurate prevalence for the retroverted uterus in general gynaecology patients
Authors: HAYLEN Bernard T. , McNALLY Glenn , RAMSAY Philippa , BIRRELL Warwick , LOGAN Vanessa 
Published: July 2007

AbstractTransvaginal ultrasound with an empty bladder is recommended as a standardised ultrasonic technique for the accurate diagnosis of the retroverted uterus. Using this method, the prevalence of the retroverted uterus in 480 general gynaecological patients attending for subspecialist gynaecological ultrasound was 18%. The anteverting effect of the full bladder required for transabdominal ultrasound reduces the prevalence of the retroverted uterus to 13% (P < 0.001).
Avulsion of the pubovisceral muscle associated with large vaginal tear after normal vaginal delivery at term
Authors: DIETZ Hans Peter , GILLESPIE Alec V. L. , PHADKE Pramod 
Published: July 2007

AbstractTrauma to the levator ani muscle commonly occurs during vaginal childbirth and is associated with female pelvic organ prolapse in later life. To date, such trauma was thought to be occult. We present a case of intrapartum diagnosis of levator avulsion in a patient who suffered a large vaginal tear at the time of a normal vaginal delivery at term.