bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bone‐eating Osedax females and their ‘harems’ of dwarf males are recruited from a common larval pool
Authors: VRIJENHOEK R. C. , JOHNSON S. B. , ROUSE G. W. 
Published: October 2008

AbstractExtreme male dwarfism occurs in Osedax (Annelida: Siboglinidae), marine worms with sessile females that bore into submerged bones. Osedax are hypothesized to use environmental sex determination, in which undifferentiated larvae that settle on bones develop as females, and subsequent larvae that settle on females transform into dwarf males. This study addresses several hypotheses regarding possible recruitment sources for the males: (i) common larval pool— males and females are sampled from a common pool of larvae; (ii) neighbourhood— males are supplied by a limited number of neighbouring females; and (iii) arrhenotoky— males are primarily the sons of host females. Osedax rubiplumus were sampled from submerged whalebones located at 1820‐m and 2893‐m depths in Monterey Bay, California. Immature females typically did not host males, but mature females maintained male ‘harems’ that grew exponentially in the number of males as female size increased. Allozyme analysis of the females revealed binomial proportions of nuclear genotypes, an indication of random sexual mating. Analysis of mitochondrial DNA sequences from the male harems and their host females allowed us to reject the arrhenotoky and neighbourhood hypotheses for male recruitment. No significant partitioning of mitochondrial diversity existed between the male and female sexes, or between subsamples of worms collected at different depths or during different years (2002–2007). Mitochondrial sequence diversity was very high in these worms, suggesting that as many as 106 females contributed to a common larval pool from which the two sexes were randomly drawn.
Between a whale bone and the deep blue sea: the provenance of dwarf males in whale bone‐eating tubeworms
Authors: WHITEMAN NOAH K. 
Published: October 2008

AbstractWhen researchers first caught a glimpse of the lush carpet of pink tubeworms covering the scattered bones of a dead grey whale 2900 m below the surface of Monterey Bay, the excitement onboard the Western Flyer (the mother ship of the remotely operated vehicle the Tiburon) must have been electrifying. The discovery of a new genus and several species of whale bone‐eating Osedax tubeworms (Annelida, Siboglinidae) a mere 6 years ago from the deep sea was itself noteworthy. But what the researchers peering into the video monitors aboard the Western Flyer could not have known at that moment was that in the gelatinous tubes of those worms clung even more peculiar forms: harems of tiny, paedomorphic males of Osedax, numbering in the hundreds at times. Whereas female tubeworms bore into the marrow of whale bones (possibly via enzymes from their endosymbiotic bacteria), the dwarf males secondarily colonize the tubes of the resident females. The number of males in a female's tube increases over time in a curvilinear fashion. Dwarf males are known from all Osedax species examined to date, yet the origin of the males was an open question. In this issue, Vrijenhoek et al. provide compelling evidence that dwarf males found in the tubes of female Osedax worms are derived from a common larval pool and are unlikely to be the sons of host females or the progeny of females in the local genetic neighbourhood. This study provides an important foundation for future work on the ecology and evolution of extreme male dwarfism in Osedax and sexual size dimorphism more generally.
Phylogeography of post‐Pleistocene population expansion in a fungus‐gardening ant and its microbial mutualists
Authors: Mikheyev Alexander S. , Vo Tanya , Mueller Ulrich G. 
Published: October 2008

AbstractAlthough historical biogeographical forces, such as climate‐driven range shifts, greatly influence the present‐day population genetic structure of animals and plants, the extent to which they affect microbial communities remains largely unknown. We examined the effect of postglacial expansion on the population structure of the northern fungus‐gardening antTrachymyrmex septentrionalisand compared it with that of its two microbial mutualists: a community of lepiotaceous fungal cultivars and associated antibiotic‐producingPseudonocardiabacteria. The ant population genetic structure showed signs of population expansion and subdivision into eastern and western phylogroups that likely originated in the Pleistocene — a pattern shared by many other North American taxa found in the same region. Although dispersal limitation was present in all three symbionts, as suggested by genetic isolation increasing with distance, the host's east–west subdivision of population genetic structure was absent from the microbial mutualist populations. While neither the cultivar nor thePseudonocardiagenetic structure was correlated with that of the ants, they were significantly correlated with each other. These results show that biogeographical forces may act differently on macro‐ and microscopic organisms, even in the extreme case where microbial mutualists are vertically transmitted from generation to generation and share the same joint ecological niche. It may be that historical climate change played a larger role in determining the population structure of the ant hosts, whereas present‐day environmental forces, such as pathogen pressure, determine the structure of associated microbial populations.
Contrasting patterns of natural variation in global Drosophila melanogaster populations
Authors: NUNES MARIA D. S. , NEUMEIER HANNAH , SCHLÖTTERER CHRISTIAN 
Published: October 2008

AbstractDespite the popularity of Drosophila melanogaster in functional and evolutionary genetics, the global pattern of natural variation has not yet been comprehensively described in this species. For the first time, we report a combined survey using neutral microsatellites and mitochondrial sequence variation jointly. Thirty‐five populations originating from five continents were compared. In agreement with previous microsatellite studies, sub‐Saharan African populations were the most variable ones. Consistent with previous reports of a single ‘out of Africa’ habitat expansion, we found that non‐African populations contained a subset of the African alleles. The pattern of variation detected for the mitochondrial sequences differed substantially. The most divergent haplotypes were detected in the Mediterranean region while Africa harboured most haplotypes, which were all closely related. In the light of the well‐established African origin of D. melanogaster, our results cast severe doubts about the suitability of mtDNA for biogeographic inference in this model organism.
QTL for the thermotolerance effect of heat hardening, knockdown resistance to heat and chill‐coma recovery in an intercontinental set of recombinant inbred lines of Drosophila melanogaster
Authors: NORRY FABIAN M. , SCANNAPIECO ALEJANDRA C. , SAMBUCETTI PABLO , BERTOLI CARLOS I. , LOESCHCKE VOLKER 
Published: October 2008

AbstractThe thermotolerance effect of heat hardening (also called short‐term acclimation), knockdown resistance to high temperature (KRHT) with and without heat hardening and chill‐coma recovery (CCR) are important phenotypes of thermal adaptation in insects and other organisms. Drosophila melanogaster from Denmark and Australia were previously selected for low and high KRHT, respectively. These flies were crossed to construct recombinant inbred lines (RIL). KRHT was higher in heat‐hardened than in nonhardened RIL. We quantify the heat‐hardening effect (HHE) as the ratio in KRHT between heat‐hardened and nonhardened RIL. Composite interval mapping revealed a more complex genetic architecture for KRHT without heat‐hardening than for KRHT in heat‐hardened insects. Five quantitative trait loci (QTL) were found for KRHT, but only two of them were significant after heat hardening. KRHT and CCR showed trade‐off associations for QTL both in the middle of chromosome 2 and the right arm of chromosome 3, which should be the result of either pleiotropy or linkage. The major QTL on chromosome 2 explained 18% and 27–33% of the phenotypic variance in CCR and KRHT in nonhardened flies, respectively, but its KRHT effects decreased by heat hardening. We discuss candidate loci for each QTL. One HHE‐QTL was found in the region of small heat‐shock protein genes. However, HHE‐QTL explained only a small fraction of the phenotypic variance. Most heat‐resistance QTL did not colocalize with CCR‐QTL. Large‐effect QTL for CCR and KRHT without hardening (basal thermotolerance) were consistent across continents, with apparent transgressive segregation for CCR. HHE (inducible thermotolerance) was not regulated by large‐effect QTL.
A polymorphic drug pump in the malaria parasite
Authors: Saliba Kevin J. , Lehane Adele M. , Kirk Kiaran 
Published: October 2008

SummaryThe human malaria parasite, Plasmodium falciparum, has long been known to have a homologue of the human ‘multidrug resistance’ P‐glycoprotein. P‐glycoprotein is an ABC transporter that pumps drugs from multidrug‐resistant cancer cells. The malaria parasite's P‐glycoprotein homologue, Pgh1, is known to influence the sensitivity of malaria parasites to a diverse range of antimalarial drugs, but the mechanism by which it does so has remained obscure. In a new paper, Sanchez et al. report the successful functional expression of Pgh1 in Xenopus laevis oocytes and provide the first direct demonstration of the ability of Pgh1 to transport drugs. The work provides important new insights into the mechanism by which Pgh1 influences malaria parasite drug sensitivity.
Capacitive effect of cavitation in xylem conduits: results from a dynamic model
Authors: HÖLTTÄ TEEMU , COCHARD HERVE , NIKINMAA EERO , MENCUCCINI MAURIZIO 
Published: October 2008

ABSTRACTEmbolisms decrease plant hydraulic conductance and therefore reduce the ability of the xylem to transport water to leaves provided that embolized conduits are not refilled. However, as a xylem conduit is filled with gas during cavitation, water is freed to the transpiration stream and this transiently increases xylem water potential. This capacitive effect of embolism formation on plant function has not been explicitly quantified in the past. A dynamic model is presented that models xylem water potential, xylem sap flow and cavitation, taking into account both the decreasing hydraulic conductance and the water release effect of xylem embolism. The significance of the capacitive effect increases in relation to the decreasing hydraulic conductance effect when transpiration rate is low in relation to the total amount of water in xylem conduits. This ratio is typically large in large trees and during drought.
Height‐related growth declines in ponderosa pine are not due to carbon limitation
Authors: SALA ANNA , HOCH GÜNTER 
Published: October 2008

ABSTRACTDecreased gas exchange as trees grow tall has been proposed to explain age‐related growth declines in trees. We examined changes of mobile carbon stores (starch, sugars and lipids) with tree height in ponderosa pine (Pinus ponderosa) at two sites differing in water availability, and tested the following hypotheses: (1) carbon supply does not become increasingly limited as trees grow tall; rather, the concentration of mobile carbon compounds increases with tree height reflecting greater reductions of carbon sink activities relative to carbon assimilation; and (2) increases of stored mobile carbon compounds with tree height are greater in drier sites. Height‐related growth reductions were associated with significant increases of non‐structural carbohydrates (NSC) and lipid concentrations in all tissues in the upper canopy and of NSC in the bole. Lipid concentrations in the bole decreased with tree height, but such decrease is not necessarily inconsistent with non‐limiting carbon supply in tall trees. Furthermore, we found stronger increases of mobile carbon stores with tree height at the dry site relative to the moist site. Our results provide first direct evidence that carbon supply does not limit growth in tall trees and that decreases of water availability might negatively impact growth processes more than net‐photosynthesis.
The Messinian Sicilian stratigraphy revisited: new insights for the Messinian salinity crisis
Authors: Roveri Marco , Lugli Stefano , Manzi Vinicio , Schreiber B. Charlotte 
Published: October 2008

AbstractControversies around the Messinian salinity crisis (MSC) are because of the difficulties in establishing genetic and stratigraphic relationships between its deep and shallow‐water record. Actually, the Sicilian foreland basin shows both shallow and deep‐water Messinian records, thus offering the chance to reconstruct comprehensive MSC scenarios. The Lower Gypsum of Sicily comprises primary and resedimented evaporites separated in space and time by the intra‐Messinian unconformity. A composite unit including halite, resedimented gypsum and Calcare di Base accumulated between 5.6 and 5.55 Ma in the main depocentres; it records the acme of the Messinian Salinity Crisis during a tectonic phase coupled with sea‐level falls at glacials TG14‐TG12. These deposits fully post‐date primary gypsum, which precipitated in shallow‐water wedge‐top and foreland ramp basins between 5.96 and 5.6 Ma. This new stratigraphic framework results in a three‐stage MSC scenario characterized by different primary evaporite associations: selenite in the first and third stages, carbonate, halite and potash salt in the second one associated with hybrid resedimented evaporites.
Regulation of ACS protein stability by cytokinin and brassinosteroid
Authors: Hansen Maureen , Chae Hyun Sook , Kieber Joseph J. 
Published: October 2008

SummaryA major question in plant biology is how phytohormone pathways interact. Here, we explore the mechanism by which cytokinins and brassinosteroids affect ethylene biosynthesis. Ethylene biosynthesis is regulated in response to a wide variety of endogenous and exogenous signals, including the levels of other phytohormones. Cytokinins act by increasing the stability of a subset of ACC synthases, which catalyze the generally rate‐limiting step in ethylene biosynthesis. The induction of ethylene by cytokinin requires the canonical cytokinin two‐component response pathway, including histidine kinases, histidine phosphotransfer proteins and response regulators. The cytokinin‐induced myc–ACS5 stabilization occurs rapidly (<60 min), consistent with a primary output of this two‐component signaling pathway. We examined the mechanism by which another phytohormone, brassinosteroid, elevates ethylene biosynthesis in etiolated seedlings. Similar to cytokinin, brassinosteroid acts post‐transcriptionally by increasing the stability of ACS5 protein, and its effects on ACS5 were additive with those of cytokinin. These data suggest that ACS is regulated by phytohormones through regulatory inputs that probably act together to continuously adjust ethylene biosynthesis in various tissues and in response to various environmental conditions.
Disruption of a novel gene for a NAC‐domain protein in rice confers resistance to Rice dwarf virus
Authors: Yoshii Motoyasu , Shimizu Takumi , Yamazaki Muneo , Higashi Takahiko , Miyao Akio , Hirochika Hirohiko , Omura Toshihiro 
Published: October 2008

Summary Rice dwarf virus (RDV) is a serious viral pest that is transmitted to rice plants (Oryza sativa L.) by leafhoppers and causes a dwarfism in infected plants. To identify host factors involved in the multiplication of RDV, we screened Tos17 insertion mutant lines of rice for mutants with reduced susceptibility to RDV. One mutant, designated rim1‐1, did not show typical disease symptoms upon infection with RDV. The accumulation of RDV capsid proteins was also drastically reduced in inoculated rim1‐1 mutant plants. Co‐segregation and complementation analyses revealed that the rim1‐1 mutation had been caused by insertion of Tos17 in an intron of a novel NAC gene. The rim1‐1 mutant remained susceptible to the two other viruses tested, one of which is also transmitted by leafhoppers, suggesting that the multiplication rather than transmission of RDV is specifically impaired in this mutant. We propose that RIM1 functions as a host factor that is required for multiplication of RDV in rice.
Integration of comprehensive abortion‐care services in a Maternal and Child Health clinic in Cambodia
Authors: Delvaux Thérèse , Sœur Sophal , Rathavy Tung , Crabbé François , Buvé Anne 
Published: October 2008

SummaryObjectives  To document the pilot experience of provision of safe abortion/post‐abortion services implemented in 2002 at the Mother Child Health clinic in Sihanoukville, Cambodia, and to profile clients and assess their uptake of post‐abortion contraception.Methods  The initial package of safe abortion/post‐abortion clinics (SAPAC) services included counselling on family planning and prevention of sexually transmitted infections, pain management, Manual Vacuum Aspiration procedure and standard universal precautions at an affordable price (US$12.5). SAPAC services became operational in August 2002. The data of medical records from 1 August 2002 to 31 December 2005 (2224 clients) were analysed.Results  The mean number of clients per month attending SAPAC services ranged from 26 in 2002 to 64 in 2005. Fifty‐three per cent were housewives, 24% worked in sales or services, 8% in factories, 11% in bars or karaoke lounges and 3% were brothel‐based sex workers. Ninety‐three per cent of clients came for induced abortion and 7% sought post‐abortion care. Pain management was used in 99% of cases. The overall rate of complications during intervention was 2.1% and dropped from 9.4% in 2002 to 1.3% in 2005. After SAPAC implementation, fewer women in Sihanoukville sought abortion services without any quality control and a safer technique was used. On average, 40% of patients took up contraception after the abortion.Conclusions  Integrating comprehensive abortion‐care services at a peripheral government health facility is feasible. There is a demand for such services provided at an affordable price in Sihanoukville, Cambodia.
Circumcision among adolescent boys in rural northwestern Tanzania
Authors: Weiss Helen A. , Plummer Mary L. , Changalucha John , Mshana Gerry , Shigongo Zachayo S. , Todd Jim , Wight Daniel , Hayes Richard J. , Ross David A. 
Published: October 2008

SummaryObjective  Male circumcision reduces risk of HIV among heterosexual men by about 60%. Modelling the impact of circumcision on HIV transmission, and planning service expansion, relies on self‐reported circumcision status. We investigated the validity of self‐reported status.Methods  Survey and in‐depth interview (IDI) data from adolescents enrolled in a community randomized sexual health intervention trial in rural Mwanza, Tanzania were analysed.Results  The 5354 male school attenders (median age 15.5 years) were recruited in 1998 and followed for 3 years. At baseline, circumcision prevalence was 13.7% by self‐report and 11.8% by clinical examination, rising to 17.3% by clinical examination at final survey. Only 61.5% of Muslim males were circumcised at the final survey. Of 506 participants who reported being circumcised at baseline, only 78.9% reported this at interim. Similarly, only 84.2% of participants clinically assessed as circumcised at baseline were also assessed as circumcised at interim. At both baseline and interim surveys, about 80% of participants who reported being circumcised were also found to be so at clinical examination. There was a high tolerance and respect for circumcision among male IDI respondents, with widespread belief that it was beneficial for penile hygiene and disease prevention. The majority of female IDI respondents said that they did not know what male circumcision was.Discussion  Attitudes to male circumcision were positive in this population despite its low prevalence. There were substantial inconsistencies in both self‐reported and clinically assessed circumcision status. Methods are needed to improve self‐report and training of clinicians in this setting.
Prevalence of epilepsy in Rwanda: a national cross‐sectional survey
Authors: Simms Victoria , Atijosan Oluwarantimi , Kuper Hannah , Nuhu Assuman , Rischewski Dorothea , Lavy Christopher 
Published: October 2008

SummaryObjective  To estimate the prevalence of epilepsy in Rwanda, as part of a survey of musculoskeletal impairment (MSI).Methods  Cross‐sectional nationally representative survey. Clusters of 105 people were selected with probability proportional to size, using the 2002 national census as the sampling frame. Within each cluster, 80 people were selected through compact segment sampling. Physiotherapists examined all participants using a standard questionnaire to assess the presence of seizures through self‐report, as well as aetiology, treatment needs and severity of the seizures. Health‐related quality of life was assessed using the EuroQol generic health index (EQ5D).Results  The response rate was 80.8%, with 6757 individuals screened. The estimated prevalence of epilepsy was 0.7% (95% confidence intervals 0.5–0.9%). A quarter (23%) of cases reported that onset of epilepsy was at birth, for 32% onset was between birth and age 5, 23% between ages 5 and 16, and 21% above the age of 16. In 4.3% of people with epilepsy, an accident during a seizure caused permanent MSI, as identified by a case history and physical examination. The majority of people with epilepsy (59.6%) had never received medical treatment for it. Epilepsy was associated with a significantly reduced quality of life.Conclusions  Epilepsy is a significant and neglected health problem in Rwanda at all ages. Investing in treatment for epilepsy would prevent some disability causing accidents from occurring.
Vector control by insecticide‐treated nets in the fight against visceral leishmaniasis in the Indian subcontinent, what is the evidence?
Authors: Ostyn Bart , Vanlerberghe Veerle , Picado Albert , Dinesh Diwakar Singh , Sundar Shyam , Chappuis François , Rijal Suman , Dujardin Jean‐Claude , Coosemans Marc , Boelaert Marleen , Davies Clive 
Published: October 2008

SummaryVisceral leishmaniasis (VL) is a deadly vector‐borne disease that causes an estimated 500 000 new cases a year. In India, Nepal and Bangladesh, VL is caused by Leishmania donovani, which is transmitted from man to man by the sandfly Phlebotomus argentipes. In 2005, these three countries signed a memorandum of understanding to eliminate VL from the region. Integrated vector management is one of the pillars of this elimination strategy, alongside early case detection and treatment. We reviewed the evidence of effectiveness of different vector control methods, to examine the potential role of insecticide treated bednets (ITNs). Indoor residual spraying has shown poor impact for various reasons and resistance to DDT is emerging in Bihar. Environmental management performed poorly compared to insecticide based methods. ITNs could give individual protection but this still needs to be proven in randomized trials. Given the constraints of indoor residual spraying, it is worthwhile to further explore the use of ITNs, in particular long lasting ITNs, as an additional tool in the VL elimination initiative.