bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic variation across species’ geographical ranges: the central–marginal hypothesis and beyond
Authors: ECKERT C. G. , SAMIS K. E. , LOUGHEED S. C. 
Published: February 2008

AbstractThere is growing interest in quantifying genetic population structure across the geographical ranges of species to understand why species might exhibit stable range limits and to assess the conservation value of peripheral populations. However, many assertions regarding peripheral populations rest on the long‐standing but poorly tested supposition that peripheral populations exhibit low genetic diversity and greater genetic differentiation as a consequence of smaller effective population size and greater geographical isolation relative to geographically central populations. We reviewed 134 studies representing 115 species that tested for declines in within‐population genetic diversity and/or increases in among‐population differentiation towards range margins using nuclear molecular genetic markers. On average, 64.2% of studies detected the expected decline in diversity, 70.2% of those that tested for it showed increased differentiation and there was a positive association between these trends. In most cases, however, the difference in genetic diversity between central and peripheral population was not large. Although these results were consistent across plants and animals, strong taxonomic and biogeographical biases in the available studies call for a cautious generalization of these results. Despite the large number of studies testing these simple predictions, very few attempted to test possible mechanisms causing reduced peripheral diversity or increased differentiation. Almost no study incorporated a phylogeographical framework to evaluate historical influences on contemporary genetic patterns. Finally, there has been little effort to test whether these geographical trends in putatively neutral variation at marker loci are reflected by quantitative genetic trait variation, which is likely to influence the adaptive potential of populations across the geographical range.
Bringing back the fruit into fruit fly–bacteria interactions
Authors: BEHAR A. , JURKEVITCH E. , YUVAL B. 
Published: February 2008

AbstractFemale Mediterranean fruit flies (Ceratitis capitata) oviposit in fruits, within which the larvae develop. This development is associated with rapid deterioration of the fruit, and frequently with invasion by secondary pests. Most research on the associations between medflies and microorganisms has focused on the bacteria inhabiting the digestive system of the adult fly, while the role of the fruit in mediating, amplifying or regulating the fruit fly microflora has been largely neglected. In this study, we examine the hypothesis that the host fruit plays a role in perpetuating the fly‐associated bacterial community. Using direct and cultured‐based approaches, we show that this community is composed in its very large majority of diazotrophic and pectinolytic Enterobacteriaceae. Our data suggest that this fly‐associated enterobacterial community is vertically transmitted from the female parent to its offspring. During oviposition, bacteria are transferred to the fruit, establish and proliferate within it, causing its decay. These results show that the host fruit is indeed a central partner in the fruit fly–bacterial interaction as these transmitted bacteria are amplified by the fruit, and subsequently maintained throughout the fly's life. This enterobacterial community may contribute to the fly's nitrogen and carbon metabolism, affecting its development and ultimately, fitness.
Agricultural management affects evolutionary processes in a migratory songbird
Authors: PERLUT NOAH G. , FREEMAN‐GALLANT COREY R. , STRONG ALLAN M. , DONOVAN THERESE M. , KILPATRICK C. WILLIAM , ZALIK NATHAN J. 
Published: February 2008

AbstractHay harvests have detrimental ecological effects on breeding songbirds, as harvesting results in nest failure. Importantly, whether harvesting also affects evolutionary processes is not known. We explored how hay harvest affected social and genetic mating patterns, and thus, the overall opportunity for sexual selection and evolutionary processes for a ground‐nesting songbird, the Savannah sparrow (Passerculus sandwichensis). On an unharvested field, 55% of females were in polygynous associations, and social polygyny was associated with greater rates of extra‐pair paternity (EPP). In this treatment, synchrony explained variation in EPP rates, as broods by more synchronous females had more EPP than broods by asynchronous females. In contrast, on a harvested field, simultaneous nest failure caused by haying dramatically decreased the overall incidence of EPP by increasing the occurrence of social monogamy and, apparently, the ability of polygynous males to maintain paternity in their own nests. Despite increased social and genetic monogamy, these haying‐mediated changes in mating systems resulted in greater than twofold increase in the opportunity for sexual selection. This effect arose, in part, from a 30% increase in the variance associated with within‐pair fertilization success, relative to the unharvested field. This effect was caused by a notable increase (+110%) in variance associated with the quality of social mates following simultaneous nest failure. Because up to 40% of regional habitat is harvested by early June, these data may demonstrate a strong population‐level effect on mating systems, sexual selection, and consequently, evolutionary processes.
Identification and characterization of small RNAs from the phloem of Brassica napus
Authors: Buhtz Anja , Springer Franziska , Chappell Louise , Baulcombe David C. , Kehr Julia 
Published: February 2008

SummarySystemic signalling is indispensable for the coordination of diverse physiological processes during development, defence and nutrient allocation. Indirect evidence suggests that plant small RNAs (smRNAs) could be involved in long‐distance information transfer via the vasculature of the plant. Analyses of the smRNA complements of vascular exudates from oilseed rape (Brassica napus) showed that xylem sap is devoid of RNA, whereas phloem sap contained a large number of smRNAs. In addition to 32 annotated microRNAs (miRNAs) from 18 different families that could be identified and approved, a set of unknown smRNAs, predominantly of 21 and 24 nucleotides in length, was obtained, and selected candidates were found to be highly abundant in phloem sap. Moreover, we could demonstrate that the levels of three miRNAs known to respond to nutrient deprivation in non‐vascular tissue, miR395 (sulphate), miR398 (copper) and miR399 (phosphate), were increased in phloem sap during the growth of plants under the respective starvation conditions. Interestingly, only mature miRNA molecules were found to be stress responsive, demonstrating that single‐stranded sense miRNAs are most likely to represent the physiologically relevant molecules. The strong responses in the phloem suggest a role of miRNAs in systemic information transfer via this long‐distance transport system.
Degradation of the cyclin‐dependent kinase inhibitor KRP1 is regulated by two different ubiquitin E3 ligases
Authors: Ren Hong , Santner Aaron , Pozo Juan Carlos del , Murray James A. H. , Estelle Mark 
Published: February 2008

SummaryIn animals and fungi, a group of proteins called the cyclin‐dependent kinase inhibitors play a key role in cell cycle regulation. However, comparatively little is known about the role of these proteins in plant cell cycle regulation. To gain insight into the mechanisms by which the plant cell cycle is regulated, we studied the cyclin‐dependent kinase inhibitor KRP1 in Arabidopsis. KRP1 interacts with the CDKA;1/CYCD2;1 complex in planta and functions in the G1–S transition of the cell cycle. Furthermore, we show that KRP1 is a likely target of the ubiquitin/proteasome pathway. Two different ubiquitin protein ligases, SCFSKP2 and the RING protein RKP, contribute to its degradation. These results suggest that SCFSKP2b and RPK play an important role in the cell cycle through regulating KRP1 protein turnover.
Transient transformation and RNA silencing in Zinnia tracheary element differentiating cell cultures
Authors: Endo Satoshi , Pesquet Edouard , Tashiro Gen , Kuriyama Hideo , Goffner Deborah , Fukuda Hiroo , Demura Taku 
Published: February 2008

SummaryThe Zinnia elegans cell culture system is a robust and physiologically relevant in vitro system for the study of xylem formation. Freshly isolated mesophyll cells of Zinnia can be hormonally induced to semisynchronously transdifferentiate into tracheary elements (TEs). Although the system has proven to be valuable, its utility is diminished by the lack of an efficient transformation protocol. We herein present a novel method to introduce DNA/RNA efficiently into Zinnia cells by electroporation‐based transient transformation. Using reporter gene plasmids, we optimized the system for efficiency of transformation and ability for the transformed cells to transdifferentiate into TEs. Optimal conditions included a partial digestion of the cell walls by pectolyase, a low voltage and high capacitance electrical pulse and an optimal medium to maintain cell viability during transformation. Beyond the simple expression of a reporter protein in Zinnia cells, we extended our protocol to subcellular protein targeting, simultaneous co‐expression of several reporter proteins and promoter‐activity monitoring during TE differentiation. Most importantly, we tested the system for double‐stranded RNA (dsRNA)‐induced RNA silencing. By introducing in vitro‐synthesized dsRNAs, we were able to phenocopy the Arabidopsis cellulose synthase (CesA) mutants that had defects in secondary cell‐wall synthesis. Suppressing the expression ofZinnia CesA homologues resulted in an increase of abnormal TEs with aberrant secondary walls. Our electroporation‐based transient transformation protocol provides the suite of tools long required for functional analysis and developmental studies at single cell levels.
Frequent sequence exchanges between homologs of RPP8 in Arabidopsis are not necessarily associated with genomic proximity
Authors: Kuang Hanhui , Caldwell Katherine S. , Meyers Blake C. , Michelmore Richard W. 
Published: February 2008

SummaryDisease resistance (R) genes are often clustered in plant genomes and may exhibit heterogeneous rates of evolution. Some (type I R genes) have evolved rapidly through frequent sequence exchanges, while others (type II R genes) have evolved independently and tend to be conserved in different genotypes or related species. The RPP8 resistance gene in Arabidopsis thaliana is located at a complex locus that also harbors the sequence‐related resistance genes HRT and RCY1 in different ecotypes. We sequenced 98 homologs of RPP8 from A. thaliana, Arabidopsis arenosa and Arabidopsis lyrata. Three lineages of type II and one lineage of type I RPP8 homologs were identified. Two of the three lineages of type II genes are each represented by a single‐copy locus on either chromosomes I or V. Chromosome V contains two small clusters of RPP8 paralogs. One cluster contains both type I and type II genes and the other comprises only type I genes. These multi‐copy loci have expanded and contracted through unequal crossovers, which have generated chimeric genes as well as variations in copy number. Sequence exchanges, most likely gene conversions, were detected between RPP8 homologs that are spatially separated by 2.2 Mb and 12 cM. The sequence exchanges between type I homologs within a locus have been more frequent than sequence exchanges between homologs from two different loci, indicating the influence of chromosomal position on the evolution of these R genes. However, physical distance was not the only factor determining the frequency of sequence exchange, because some closely linked paralogs exhibited little sequence exchange. At least two distinct lineages of type II RPP8 homologs were identified in different species, with obvious allelic/orthologous relationships within each lineage. Therefore, the differentiation of type I and type II RPP8 homologs seems to have occurred before speciation of A. thaliana, A. arenosa and A. lyrata.
Reduced activity of Arabidopsis thaliana HMT2, a methionine biosynthetic enzyme, increases seed methionine content
Authors: Lee Minsang , Huang Tengfang , Toro‐Ramos Tatiana , Fraga Michele , Last Robert L. , Jander Georg 
Published: February 2008

SummaryIn the S‐methylmethionine cycle of plants, homocysteine methyltransferase (HMT) catalyzes the formation of two molecules of methionine from homocysteine and S‐methylmethionine, and methionine methyltransferase (MMT) catalyzes the formation of methionine from S‐methylmethionine using S‐adenosylmethionine as a methyl group donor. Somewhat surprisingly, two independently isolated knockdown mutations of HMT2 (At3g63250), one of three Arabidopsis thaliana genes encoding homocysteine methyltransferase, increased free methionine abundance in seeds. Crosses and flower stalk grafting experiments demonstrate that the maternal genotype at the top of the flower stalk determines the seed S‐methylmethionine and methionine phenotype of hmt2 mutants. Uptake, transport and inter‐conversion of [13C]S‐methylmethionine and [13C]methionine in hmt2, mmt and wild‐type plants show that S‐methylmethionine is a non‐essential intermediate in the movement of methionine from vegetative tissue to the seeds. Together, these results support a model whereby elevated S‐methylmethionine in hmt2 vegetative tissue is transported to seeds and either directly or indirectly results in the biosynthesis of additional methionine. Manipulation of the S‐methylmethionine cycle may provide a new approach for improving the nutritional value of major grain crops such as rice, as methionine is a limiting essential amino acid for mammalian diets.
Characterization of a Phytoplasma Associated with Pear Decline in Iran
Authors: Salehi M. , Izadpanah K. , Taghavi S. M. , Rahimian H. 
Published: February 2008

AbstractSymptoms of pear decline (PD) were observed in several pear growing regions of Iran. Pear trees with typical symptoms of PD from Estahban (Fars Province) were examined for phytoplasma infection using polymerase chain reaction (PCR) assay. Graft inoculation of healthy pear trees with scions from diseased trees resulted in production of PD symptoms and transmission of phytoplasma as verified by PCR. Target DNA was amplified from symptomatic pear trees with fO1/rO1, an apple proliferation (AP) group‐specific primer pair. Physical and putative restriction fragment length polymorphism (RFLP) analyses of fO1/rO1 primed PCR products showed profiles corresponding to AP group, 16SrX‐C subgroup (Candidatus Phytoplasma pyri). Percent similarity values and phylogenetic analysis of fO1/rO1 primed sequences confirmed that, as a member of AP subclade, Estahban PD phytoplasma has a closer relationship to PD and peach yellow leaf roll phytoplasmas than to AP (Ca. Phytoplasma mali) and European stone fruit yellows (Ca. Phytoplasma prunorum) phytoplasmas. This is the first report of PD phytoplasma in the eastern Mediterranean.
Genetic Variation Among and Within Uromyces Species Infecting Legumes
Authors: Emeran A. A. , Román B. , Sillero J. C. , Satovic Z. , Rubiales D. 
Published: February 2008

AbstractGenetic variation of 30 different Uromyces isolates collected on faba bean, lentil, common vetch, pea, chickpea, alfalfa, cowpea and lupin was studied. Random Amplified Polymorphic DNA markers were used showing clear differences among Uromyces species. Uromyces viciae‐fabae isolates clustered according to the host, with a clear cluster including all U. viciae‐fabae ex Vicia faba isolates. The U. viciae‐fabae ex Lens culinaris isolate was the nearest to the cluster of U. viciae faba ex V. faba isolates, followed by U. pisi from Canada and U. viciae‐fabae ex V. sativa. No association was found among molecular diversity and virulence or geographic origin within U. vicia‐fabae ex V. faba isolates. Among the three U. pisi isolates considered, a great variability was observed and no grouping could be established. The most different isolate from the rest of species considered was U. striatus, followed by U. vignae. The two U. ciceris‐arietini isolates clustered together and so did the two U. lupinicolus isolates.
Review of intern preparedness and education experiences in General Medicine
Authors: Gome J. J. , Paltridge D. , Inder W. J. 
Published: February 2008

AbstractBackground:  Few studies assess the transition from medical student to intern and there is limited understanding of what measures are required to assist intern development. The aim of the study was to assess interns’ perception of their preparedness before commencing and on completion of their rotation in General Medicine, and their attitudes towards educational experiences at a tertiary metropolitan teaching hospital.Methods:  Self‐assessed preparedness for the General Medical internship and educational experiences were evaluated using a quantitative 5‐point scale (1 = low score and 5 = high score) and qualitatively through interview, on interns based at St Vincent’s Hospital (Melbourne). Data were collected at the beginning and at the end of each 10‐week rotation (n = 25).Results:  Before commencement of the rotation, the interns identified areas where they felt inadequately prepared, particularly resuscitation skills and medico‐legal aspects. When resurveyed at the completion of their 10‐week rotation, the interns felt they had been better prepared for their role than they initially perceived, both generally and in specific aspects. Nine out of 16 parameters showed a significant increase in preparedness score at week 10 compared to week 1. The educational experiences most valued were peer driven education sessions and informal registrar teaching. Formal consultant teaching and online learning were perceived as being the least useful.Conclusion:  Interns at St Vincent’s Hospital have been adequately prepared for their role in General Medicine, although many realize this only in retrospect. Deficiencies in educational opportunities for interns have been uncovered that emphasize areas of attention for medical educators.
Improving the quality of written prescriptions in a general hospital: the influence of 10 years of serial audits and targeted interventions
Authors: Gommans J. , McIntosh P. , Bee S. , Allan W. 
Published: February 2008

AbstractBackground:  Poor quality prescribing has been identified as one of the leading causes of medication error and adverse drug events. The aim of this study was to improve the quality of written prescriptions in a general hospital by a combination of serial audits and interventions designed to address identified deficiencies.Methods:  Inpatient medication charts were audited annually from 1998 to 2007. Charts were assessed against predetermined standards for good‐quality prescribing.Results:  Initially an unacceptable proportion of medication charts failed to document adequately one or more of the following: prescriber identification (58%), legible prescriptions (14%), route of administration (14%), a dose (11%), date (11%) or adequate patient identification (8%). Only 53% of charts had any information about medication alerts and 15% contained at least one verbal order. Interventions designed to address these deficiencies included educational strategies (e.g. feedback of audit results, education sessions for doctors and nurses on prescribing and medication errors) and changes to systems (e.g. modifications to medication charts, development of hospital wide prescribing standards and an alert notification system). Serial audits showed progressive improvements in all items by 2007 including; legibility (97%), patient identification (100%), documentation of date (98%), drug dose (99%) and route (97%), use of medication alerts (98%) and the prevalence of verbal orders (<1%). Identification of prescribers remained suboptimal (81% in 2006, 53% in 2007).Conclusion:  Serial audits of the quality of prescribing on hospital medication charts can rapidly identify the extent of deficiencies in prescribing practice, facilitate interventions specifically designed to address these and monitor their influence.
Management of MUTYH‐associated neoplasia in Australia
Authors: Worthley D. L. , Suthers G. , Lipton L. 
Published: February 2008

AbstractBackground:  Mutations in the MUTYH gene,which codes for a base excision repair protein, have recently been found to cause an autosomal recessive syndrome characterized by multiple colorectal adenomas and increased risk of colorectal cancer. To identify key areas for clinical research, it is necessary to understand the current management of MUTYH‐associated neoplasia.Methods:  Twelve questionnaires were sent to experts from familial colorectal cancer services throughout Australia, including representatives from all Australian states. The questionnaire was designed to clarify the practical management of MUTYH‐associated neoplasia in the patient and their family.Results:  All 12 questionnaires were returned. For patients with fewer than 100 colorectal adenomas, and no dominant family history of colorectal neoplasia, most respondents carried out MUTYH testing before or concomitantly with APC. Australian laboratories generally carried out an intial directed analysis of the MUTYH gene for the two common mutations Y165C and G382D. For patients with biallelic MUTYH mutations all respondents endorsed regular colonoscopy surveillance with an interval of 1–2 years, whereas the recommended surveillance for monoallelic mutation carriers varied.Conclusion:  This is the first study to document current management practices for MUTYH‐associated neoplasia and forms a basis for the development of evidence‐based recommendations as further research becomes available. Current guidelines for testing and management of MUTYH‐associated neoplasia are discussed.
Management of stages I and II non‐small‐cell lung cancer in a New Zealand study: divergence from international practice and recommendations
Authors: Stevens W. , Stevens G. , Kolbe J. , Cox B. 
Published: February 2008

AbstractBackground:  Lung cancer survival statistics for New Zealand (NZ) are poor relative to Australia, USA, Canada and some European countries for reasons that are unknown. As patients with early‐stage non‐small‐cell lung cancer (NSCLC) have the highest chance of survival, appropriate management disproportionately influences survival rates. The aim of this study was to assess management of stage I/II NSCLC, whether management differed from international practice, and factors influencing curative management.Methods:  Management of patients with stages I and II NSCLC was determined from an audit of secondary care in Auckland and Northland for patients with lung cancer diagnosed in 2004 (565).Results:  Of the 142 cases with stage I or II NSCLC, 79 patients (56%) were treated with curative intent and 61 (44%) were managed palliatively. Of those treated curatively, 69 underwent surgical resection, 9 received definitive radiation therapy and a single patient received concurrent chemo‐irradiation. Of those managed palliatively, 21 received anticancer treatment and 40 received supportive care. Increasing age and comorbidity reduced the chances of receiving curative treatment (P < 0.001, P = 0.004, respectively); however, discussion at a multidisciplinary meeting was associated with increased likelihood of curative management (P < 0.001). Disparity between NZ and overseas practice increased with increasing age and comorbidity. Only half of those managed curatively commenced treatment within internationally recommended time frames.Conclusion:  Relatively fewer patients received potentially curative treatment in this NZ study than in countries with better survival outcomes and many were not managed within recommended time frames. Management differences increased with increasing age and comorbidity, possibly suggesting more nihilistic attitudes in NZ.