bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic review of personality disorder amongst people with intellectual disability with implications for the mental health nurse practitioner
Authors: Pridding Andrew , Procter Nicholas G
Published: July 2008

Aims and objectives.  This paper reviews and summarises the literature on assessment, diagnosis and management of personality disorder in people with intellectual disability. It will proceed to argue the implications of a mental health nurse practitioner in clinical practice.

Background.  Personality disorder is a potentially severe and disabling condition causing significant distress as well as presenting considerable challenges for service providers. Diagnosis in people with intellectual disability is controversial. However, it is considered that this population is at greater risk of these disorders. There is, however, little research on which to base clinical interventions or service planning.

Design.  Systematic review.

Methods.  A literature search of electronic data was undertaken in April 2007 using CINAHL, AMED, Medline, PsycINFO, EMBASE and Cochrane Library. Other sources included Google Scholar, hand searching of reference lists and texts and search of relevant websites.

Results.  The literature on personality disorder in intellectual disability is notable for its paucity. The limited evidence available suggests that this population is at greater risk of personality disorder and that assessment and diagnosis is complex and often overshadowed by the intellectual disability. Few papers address treatment, there are no trial‐based studies and it has not been established whether results can be extrapolated from research in the general population.

Conclusions.  The issue of personality disorder in people with intellectual disability is shrouded in controversy with a dearth of robust evidence to inform assessment or therapeutic care. Personality disorder does, however, provide a basis for decisions on type and intensity of support required for this population who have significant levels of unmet need.

Relevance to clinical practice.  Some people with an intellectual disability and personality disorder can live in the community with specialist support. The mental health nurse practitioner has the potential to provide people with dual diagnostic support needed to enhance the capacity of the service system to meet the needs of this complex and difficult population.
Mental health care: trust and mistrust in different caring contexts
Authors: Piippo Jukka , Aaltonen Jukka
Published: July 2008

Aims and objectives.  To identify the factors that make trust within the context of public mental health possible. We also consider the question of patients’ trust in the whole caring system. The study is based on individual interviews with 22 psychiatric patients, who were also users of social services.

Background.  There are theoretical studies concerning trust between human beings in several disciplines within psychiatry and social services but few studies investigate how trust can be created and what makes it possible. The literature reveals that there is need for research concerning trust in psychiatry. In this study we examined two different caring contexts and investigated what makes trust possible in these contexts. The contexts are termed the Integrated Network and Family Model and the Traditional Model.

Design.  A qualitative method based on the grounded theory approach was used.

Methods.  The main focus in the analysis was on how the patients had experienced the contexts of the caring systems and how trust was created or not within them.

Results.  Three categories creating trust were found in the Integrated Network and Family Model and two in the Traditional context. Acceptance of the patient’s expertise concerning his/her life situation, openness and joint discussions concerning knowledge are important. Trust is closely connected to autonomy and power: patients feel that trust increases as their experience of autonomy increases and in such situations power is not owned by any one person.

Conclusions.  Trust between psychiatric patients and personnel can be created in both the Integrated Network and Family Model and traditional context, but in different ways.

Relevance to clinical practice.  Clinical workers and nursing personnel can use our findings in their practical work with psychiatric patients. Our findings support theoretical considerations concerning trust and can be used as guidelines for nursing personnel in their work.
Nursing practice and oral fluid intake of older people with dementia
Authors: Ullrich Sandra , McCutcheon Helen
Published: July 2008

Aim.  This paper describes the findings of a descriptive study about what nurses do to ensure that older people with dementia have adequate hydration.

Background.  Frail nursing home residents, particularly those who cannot accurately communicate their thirst as a result of Alzheimer’s disease and who depend on nursing staff for their fluid intake, are at risk of dehydration. While the interventions that promote nutrition in older people with dementia are documented, the specific interventions for improving oral hydration in older people with dementia remain poorly studied and understood.

Design.  Observational study.

Methods.  Ten care workers and seven residents were observed for the types of behavioural nursing interventions and assistance provided to residents when promoting oral fluid intake. Observational data were compared with resident‐care plans to determine whether what was carried out by care workers was consistent with what was being documented.

Results.  Care workers provided a wide variety of behavioural interventions to the residents when promoting oral fluid intake. The resident‐care plans did not sufficiently represent the specific interventions implemented by care workers.

Conclusions.  A more rigorous approach is required in defining the specific behavioural interactions practised by care workers, which promote oral fluid intake in older people with dementia. Nurses determined the content of care documented in care plans, yet they were not the predominant implementers of that care. Care plans need to be accurate in terms of the specific nursing actions that respond to the level of assistance required by the resident, both behaviourally and physically.

Relevance to clinical practice.  Sound knowledge and reflective practices should be implemented by care workers of the nursing interventions that promote adequate oral fluid intake. Care plans should serve a dual purpose and facilitate communication between staff members and provide sufficient flexibility to allow for the contribution of novel ways in which to promote oral fluid intake while also being educative.
Evaluating effects of a prenatal breastfeeding education programme on women with caesarean delivery in Taiwan
Authors: Lin Chien‐Hui , Kuo Su‐Chen , Lin Kuan‐Chia , Chang Tse‐Yun
Published: July 2008

Aims.  The aims of this study were: (1) to evaluate the effectiveness of a prenatal breastfeeding education programme for primigravida women who have elected caesarean section as a model of delivery and (2) to evaluate its effectiveness for encouraging a positive attitude to breastfeeding and rooming‐in and to increase exclusive breastfeeding rates within hospital and at one month postpartum.

Background.  Prenatal preparation for pregnant women about breastfeeding enhances their practical knowledge and skills about breastfeeding techniques, which prepares them when encountering possible difficulties.

Design.  A quasi‐experimental design was used.

Methods.  The targeted population was primigravidas at 36–39 weeks and who had chosen to deliver by caesarean section. The study consisted of approximately 100 individuals; the control group consisted of 46 subjects and the following 54 made up the experimental group. The study was conducted at a hospital in Taiwan.

Results.  The results of the study show that the subjects of the experimental group exhibited a more positive breastfeeding attitude (88·9 vs. 79·8, t = 7·40, p < 0·001), a higher 24 hours rooming‐in rate (87% vs. 63%, χ2 = 16·06, p < 0·001) and a higher exclusive breastfeeding rate (79·6% vs. 52·2%, χ2 = 8·38, p = 0·004) during hospital stays and a higher exclusive breastfeeding rate (75·9% vs. 34·7%, χ2 = 16·98, p < 0·001) for the one month postpartum period.

Conclusion.  Results suggest that providing education booklets, videos and telephone interview on breastfeeding prior to a caesarean delivery may contribute to breastfeeding attitude and improved rooming‐in and exclusive breastfeeding rates.

Relevance to clinical practice.  This breastfeeding education programme has proven to be successful in aiding women breastfeeding after a caesarean delivery and provides health care professionals with an evidence‐based intervention.
A systematic review of informal caregivers’ needs in providing home‐based end‐of‐life care to people with cancer
Authors: Bee Penny E , Barnes Pamela , Luker Karen A
Published: July 2008

Aims.  This paper presents the results of a systematic review examining the practical information needs of informal caregivers providing home‐based palliative and end‐of‐life care to people with advanced cancer.

Background.  Modern hospice care has led to increases in home‐based palliative care services, with informal caregivers assuming responsibility for the majority of care. In response, health policy emphasises the provision of palliative care services in which both the patient and carer receive adequate support throughout illness and death. While the emotional needs of carers have been extensively researched, their practical needs with respect to the provision of physical care are yet to receive systematic attention.

Design.  Systematic review.

Methods.  Eligible articles were identified via electronic searches of research and evidence‐based databases, hand‐searching of academic journals and searches of non‐academic grey literature websites. Quality of research was assessed via accepted guidelines for reviewing non‐randomised, observational and qualitative literature. Data were synthesised by comparing and contrasting the findings to identify prominent themes.

Results.  Research consistently highlights this lack of practical support, often related to inadequate information exchange. These deficits typically manifest in relatives adopting a ‘trial and error’ approach to palliative care. Informal carers request a greater quantity of practically‐focussed information, improvements in quality and increased methods of dissemination.

Conclusion.  Synthesis of the literature suggests that home‐based palliative care services have been insufficiently focussed on assisting informal caregivers acquire practical nursing skills.

Relevance to clinical practice.  Enhanced access to professional advice represents a potentially effective method of increasing carers’ confidence in their ability to undertake practical aspects of home‐based care. Evidence suggests that nurses and other health providers may better assist home‐based carers by providing the information and skills‐training necessary to facilitate this. This may necessitate the involvement of carers in the design and testing of new educational interventions.
Evidence for multiple sources of invasion and intraspecific hybridization inBrachypodium sylvaticum(Hudson) Beauv. in North America
Authors: ROSENTHAL DAVID M. , RAMAKRISHNAN ALISA P. , CRUZAN MITCHELL B.
Published: July 2008

We compared the levels and distribution of genetic diversity in Eurasian and North American populations ofBrachypodium sylvaticum(Huds.) Beauv. (false brome), a newly invasive perennial bunchgrass in western North America. Our goals were to identify source regions for invasive populations, determine the number of independent invasion events, and assess the possibility that postinvasion bottlenecks and hybridization have affected patterns of genetic diversity in the invaded range. We tested the hypothesis that this Eurasian grass was accidentally introduced into two areas in Oregon and one site in California by examining nuclear microsatellites and chloroplast haplotype variation in 23 introduced and 25 native populations. In the invaded range, there was significantly lower allelic richness (RS), observed heterozygosity (HO) and within‐population gene diversity (HS), although a formal test failed to detect a significant genetic bottleneck. Most of the genetic variation existed among populations in the native range but within populations in the invaded range. All of the allelic variation in the invaded range could be explained based on alleles found in western European populations. The distribution of identified genetic clusters in the North American populations and the unique alleles associated with them is consistent with two historical introductions in Oregon and a separate introduction to California. Further analyses of population structure indicate that intraspecific hybridization among genotypes from geographically distinct regions of western Europe occurred following colonization in Oregon. The California populations, however, are more likely to be derived from one or perhaps several genetically similar regions in the native range. The emergence and spread of novel recombinant genotypes may be facilitating the rapid spread of this invasive species in Oregon.
Fungal specificity bottlenecks during orchid germination and development
Authors: BIDARTONDO MARTIN I. , READ DAVID J.
Published: July 2008

Fungus‐subsidized growth through the seedling stage is the most critical feature of the life history for the thousands of mycorrhizal plant species that propagate by means of ‘dust seeds.’ We investigated the extent of specificity towards fungi shown by orchids in the genera Cephalanthera and Epipactis at three stages of their life cycle: (i) initiation of germination, (ii) during seedling development, and (iii) in the mature photosynthetic plant. It is known that in the mature phase, plants of these genera can be mycorrhizal with a number of fungi that are simultaneously ectomycorrhizal with the roots of neighbouring forest trees. The extent to which earlier developmental stages use the same or a distinctive suite of fungi was unclear. To address this question, a total of 1500 packets containing orchid seeds were buried for up to 3 years in diverse European forest sites which either supported or lacked populations of helleborine orchids. After harvest, the fungi associated with the three developmental stages, and with tree roots, were identified via cultivation‐independent molecular methods. While our results show that most fungal symbionts are ectomycorrhizal, differences were observed between orchids in the representation of fungi at the three life stages. In Cephalanthera damasonium and C. longifolia, the fungi detected in seedlings were only a subset of the wider range seen in germinating seeds and mature plants. In Epipactis atrorubens, the fungi detected were similar at all three life stages, but different fungal lineages produced a difference in seedling germination performance. Our results demonstrate that there can be a narrow checkpoint for mycorrhizal range during seedling growth relative to the more promiscuous germination and mature stages of these plants’ life cycle.
Mitochondrial DNA‐inferred population structure and demographic history of the mitten crab (Eriocheir sensu stricto) found along the coast of mainland China
Authors: WANG CHENGHUI , LI CHENHONG , LI SIFA
Published: July 2008

The mitten crab, Eriocheir sensu stricto, is economically important in East Asia, although it is an invasive species in Europe and North America. Little is known about its population structure and historical demography in its native range, especially along the Pacific coast of China. We collected mitochondrial cytochrome oxidase subunit II and cytochrome b sequences from 154 individuals distributed in the rivers along the Chinese coast and 15 individuals from Japan. Phylogenetic analysis resulted in three major monophyletic groups: northern China, southern China and Japan. Negligible migration was detected among those groups by coalescent analysis. Hence, we support the recognition of three species: Eriocheir hepuensis in southern China, Eriocheir sinensis in northern China and Eriocheir japonica in Japan. The populations in the middle (the Oujiang and Minjiang Rivers) possess a mixture of haplotypes similar to either the northern or the southern haplotypes. We believe that secondary intergradation as the most likely cause of the clinal variation based on examining the genetic variation in the latitudinal space. The estimated divergence time between E. sinensis and E. hepuensis is 2.24 million years ago (Ma), while the divergence time between E. japonica and E. sinensis is 1.83 Ma. Both are in the late Pliocene, suggesting that land bridges associated with low sea level during that time might have severed as vicariant barriers for speciation. The divergence of the northern population and the ‘northern haplotypes’ in the middle population was estimated at 0.12 Ma, while the time separating the southern population and the ‘southern haplotypes’ in the middle populations was estimated as 0.16 Ma, implicating possible secondary contact in the late Pleistocene.
Differentiating salmon populations at broad and fine geographical scales with microsatellites and single nucleotide polymorphisms
Authors: NARUM S. R. , BANKS M. , BEACHAM T. D. , BELLINGER M. R. , CAMPBELL M. R. , DEKONING J. , ELZ A. , GUTHRIE III C. M. , KOZFKAY C. , MILLER K. M. , MORAN P. , PHILLIPS R. , SEEB L. W. , SMITH C. T. , WARHEIT K. , YOUNG S. F. , GARZA J. C.
Published: July 2008

Single nucleotide polymorphisms (SNPs) are appealing genetic markers due to several beneficial attributes, but uncertainty remains about how many of these bi‐allelic markers are necessary to have sufficient power to differentiate populations, a task now generally accomplished with highly polymorphic microsatellite markers. In this study, we tested the utility of 37 SNPs and 13 microsatellites for differentiating 29 broadly distributed populations of Chinook salmon (n = 2783). Information content of all loci was determined by In and , and the top 12 markers ranked by In were microsatellites, but the 6 highest, and 7 of the top 10 ranked markers, were SNPs. The mean ratio of random SNPs to random microsatellites ranged from 3.9 to 4.1, but this ratio was consistently reduced when only the most informative loci were included. Individual assignment test accuracy was higher for microsatellites (73.1%) than SNPs (66.6%), and pooling all 50 markers provided the highest accuracy (83.2%). When marker types were combined, as few as 15 of the top ranked loci provided higher assignment accuracy than either microsatellites or SNPs alone. Neighbour‐joining dendrograms revealed similar clustering patterns and pairwise tests of population differentiation had nearly identical results with each suite of markers. Statistical tests and simulations indicated that closely related populations were better differentiated by microsatellites than SNPs. Our results indicate that both types of markers are likely to be useful in population genetics studies and that, in some cases, a combination of SNPs and microsatellites may be the most effective suite of loci.
A population genomic approach to map recent positive selection in model species
Authors: PAVLIDIS P. , HUTTER S. , STEPHAN W.
Published: July 2008

Based on nearly complete genome sequences from a variety of organisms data on naturally occurring genetic variation on the scale of hundreds of loci to entire genomes have been collected in recent years. In parallel, new statistical tests have been developed to infer evidence of recent positive selection from these data and to localize the target regions of selection in the genome. These methods have now been successfully applied to Drosophila melanogaster, humans, mice and a few plant species. In genomic regions of normal recombination rates, the targets of positive selection have been mapped down to the level of individual genes.
Landscape genetics, historical isolation and cross‐Andean gene flow in the wax palm,Ceroxylon echinulatum(Arecaceae)
Authors: TRÉNEL PHILIPP , HANSEN MICHAEL M. , NORMAND SIGNE , BORCHSENIUS FINN
Published: July 2008

Knowledge of the role of landscapes in shaping genetic connectivity and divergence is essential for understanding patterns of biogeography and diversity. This is particularly relevant for the Andes region, a major biodiversity hotspot of relatively recent origin. We examined the phylogeography and landscape genetics of the Andean wax palmCeroxylon echinulatum(Arecaceae) that occurs in two narrow bands of montane forests on each side of the Andes in Ecuador and northeastern Peru. First, we tested the hypothesis ofC. echinulatumbeing a geographic cline species crossing the Andes in the Amotape–Huancabamba zone (AHZ) of southern Ecuador/northern Peru, as indicated by observations on fruit morphology. Second, we assessed the timeframe of cross‐Andean divergence, and third, we investigated the impact of contemporary and historical landscape features on observed spatio‐genetic patterns. Individual‐based Bayesian clustering (BC) identified a northeastern, southeastern, southwestern, and northwestern cluster, with areas of genetic discontinuity coinciding with the Andes and the Giron–Paute deflection.F‐statistics derived from BC suggested an east‐to‐west dispersal history. Population‐based analyses revealed strong genetic structuring at both small and large geographic scales. Interpopulation relationships and Mantel tests strongly supported the cline model with cross‐Andean dispersal in the AHZ. Along the cline, gene flow measured asFSTwas mainly limited by distance, with less but significant impact of climatic friction. Coalescent analysis revealed that cross‐Andean divergence took place during the Quaternary. Significant historical isolation (RST > FST) was found in the southwestern population. The current study illustrates a joint effect of founder dynamics, divergence by distance and historical isolation on patterns of Andean diversity and distribution.
In‐stream and overland dispersal across a river network influences gene flow in a freshwater insect, Calopteryx splendens
Authors: CHAPUT‐BARDY A. , LEMAIRE C. , PICARD D. , SECONDI J.
Published: July 2008

Gene flow in riverine species is constrained by the dendritic (branching) structure of the river network. Spatial genetic structure (SGS) of freshwater insects is particularly influenced by catchment characteristics and land use in the surroundings of the river. Gene flow also depends on the life cycle of organisms. Aquatic larvae mainly drift downstream whereas flying adults can disperse actively overland and along watercourses. In‐stream movements can generate isolation by distance (IBD) at a local scale and differentiation between subcatchments. However, these patterns can be disrupted by overland dispersal. We studied SGS across the Loire River in the damselfly Calopteryx splendens which is able to disperse along and between watercourses. Our sampling design allowed us to test for overland dispersal effects on genetic differentiation between watercourses. Amplified fragment length polymorphism markers revealed high genetic differentiation at the catchment scale but the genetic structure did not reflect the geographical structure of sampling sites. We observed IBD patterns when considering the distance following the watercourse but also the Euclidean distance, i.e. the shortest distance, between pairs of sites. Altogether, our results support the hypothesis of overland dispersal between watercourses. From a conservation perspective, attention should be paid to the actual pathways of gene flow across complex landscapes such as river networks.
Twenty years of phylogeography: the state of the field and the challenges for the Southern Hemisphere
Authors: BEHEREGARAY LUCIANO B.
Published: July 2008

Phylogeography is a young, vigorous and integrative field of study that uses genetic data to understand the history of populations. This field has recently expanded into many areas of biology and also into several historical disciplines of Earth sciences. In this review, I present a numerical synthesis of the phylogeography literature based on an examination of over 3000 articles published during the first 20 years of the field (i.e. from 1987 to 2006). Information from several topics needed to evaluate the progress, tendencies and deficiencies of the field is summarized for 10 major groups of organisms and at a global scale. The topics include the geography of phylogeographic surveys, comparative nature of studies, temporal scales and major environments investigated, and genetic markers used. I also identify disparities in research productivity between the developing and the developed world, and propose ways to reduce some of the challenges faced by phylogeographers from less affluent countries. Phylogeography has experienced explosive growth in recent years fuelled by developments in DNA technology, theory and statistical analysis. I argue that the intellectual maturation of the field will eventually depend not only on these recent developments, but also on syntheses of comparative information across different regions of the globe. For this to become a reality, many empirical phylogeographic surveys in regions of the Southern Hemisphere (and in developing countries of the Northern Hemisphere) are needed. I expect the information and views presented here will assist in promoting international collaborative work in phylogeography and in guiding research efforts at both regional and global levels.
A comparison of techniques for assessing dispersal behaviour in gundis: revealing dispersal patterns in the absence of observed dispersal behaviour
Authors: NUTT KAREN J
Published: July 2008

Knowledge of the dispersal status of group members is important to understanding how sociality may have evolved within a species. I assessed the effectiveness of four techniques for elucidating dispersal behaviour in a rock‐dwelling rodent (Ctenodactylus gundi) with small group sizes (2–10 animals): genetic parentage assignment, haplotype data and kinship analyses, assignment testing, andF‐statistics. The first two methods provided the greatest insight into gundi dispersal behaviour. Assignment testing andF‐statistics proved of limited use for elucidating fine‐scale dispersal, but could detect large‐scale patterns despite low sex‐biased dispersal intensity (1.9 : 1) because of moderate genetic differentiation among groups (FST = 0.10). Findings are discussed in light of current dispersal theory. In general, gundi dispersal is plastic, and seems to be dependent on body weight (for males), group composition, and scale of analysis (total dispersal events recorded within the population were almost twice the immigration rate into the population). Most groups were comprised of a single matriline and one immigrant male. Immigrant rather than philopatric males bred with group females. Dispersal among groups was male‐biased, but dispersal or philopatry could occur by either sex. During a drought, both sexes delayed dispersal and cooperative social units formed. Whether such behaviour resulted directly from the drought or not remains unclear, however, since comparative information was not available from nondrought years. Combining fine‐scale analyses with information on large‐scale patterns provided substantial insight into gundi dispersal behaviour despite the limited movement of animals during a drought, and may prove useful for elucidating dispersal behaviour in other social animals.
Male‐biased dispersal in a tropical Australian snake (Stegonotus cucullatus, Colubridae)
Authors: DUBEY S. , BROWN G. P. , MADSEN T. , SHINE R.
Published: July 2008

Sex‐based differences in dispersal distances can affect critical population parameters such as inbreeding rates and the spatial scale of local adaptation. Males tend to disperse further than females in mammals, whereas the reverse is true for birds; too few reptiles have been studied to reveal generalities for that group. Although reptiles are most diverse and abundant in the tropics, few tropical reptiles have been studied in this respect. We combine data from a long‐term (10‐year) mark–recapture study with genetic information (based on nine microsatellite markers) on slatey‐grey snakes (Stegonotus cucullatus, Colubridae) in the Australian wet‐dry tropics. Males attain larger body sizes than females, and both genetic and mark–recapture data show that males also disperse further than females. Recapture records show that hatchling males dispersed away from their release points whereas hatchling females did not, and adult males moved further than adult females. In the genetic analysis, males contributed less to overall FST and relatedness than did females (FSTm = 0.0025, FSTf = 0.0275, P < 0.001; rm = 0.0053; rf = 0.0550; P < 0.001). Spatial autocorrelation analyses within the largest population revealed a similar pattern, with spatial structuring stronger for females than males. Overall, our genetic analyses not only supported the mark–recapture data, but also extended our insights by revealing occasional long‐distance dispersal not detected by the mark–recapture study.
Selection and sticklebacks
Authors: BEAUMONT MARK A.
Published: July 2008

Over the last decade, there has been increasing circumstantial evidence for the action of natural selection in the genome, arising largely from molecular genetic surveys of large numbers of markers. In nonmodel organisms without densely mapped markers, a frequently used method is to identify loci that have unusually high or low levels of genetic differentiation, or low genetic diversity relative to other populations. The paper by Mäkinen et al. (2008a) in this issue of Molecular Ecology reports the results of a survey of microsatellite allele frequencies at more than 100 loci in seven populations of the three‐spined stickleback (Gasterosteus aculeatus). They show that a microsatellite locus and two indel markers located within the intron of the Eda gene, known to control the number of lateral plates in the stickleback (Fig. 1), tend to be much more highly genetically differentiated than other loci, a finding that is consistent with the action of local selection. They identify a further two independent candidates for local selection, and, most intriguingly, they further suggest that up to 15% of their loci may provide evidence of balancing selection.

Three‐spined stickleback (Gasterosteus aculeatus).

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RecA‐mediated SOS induction requires an extended filament conformation but no ATP hydrolysis
Authors: Gruenig Marielle C. , Renzette Nicholas , Long Edward , Chitteni‐Pattu Sindhu , Inman Ross B. , Cox Michael M. , Sandler Steven J.
Published: July 2008

The Escherichia coli SOS response to DNA damage is modulated by the RecA protein, a recombinase that forms an extended filament on single‐stranded DNA and hydrolyzes ATP. The RecA K72R (recA2201) mutation eliminates the ATPase activity of RecA protein. The mutation also limits the capacity of RecA to form long filaments in the presence of ATP. Strains with this mutation do not undergo SOS induction in vivo. We have combined the K72R variant of RecA with another mutation, RecA E38K (recA730). In vitro, the double mutant RecA E38K/K72R (recA730,2201) mimics the K72R mutant protein in that it has no ATPase activity. The double mutant protein will form long extended filaments on ssDNA and facilitate LexA cleavage almost as well as wild‐type, and do so in the presence of ATP. Unlike recA K72R, the recA E38K/K72R double mutant promotes SOS induction in vivo after UV treatment. Thus, SOS induction does not require ATP hydrolysis by the RecA protein, but does require formation of extended RecA filaments. The RecA E38K/K72R protein represents an improved reagent for studies of the function of ATP hydrolysis by RecA in vivo and in vitro.
The headful packaging nuclease of bacteriophage T4
Authors: Alam Tanfis I. , Draper Bonnie , Kondabagil Kiran , Rentas Francisco J. , Ghosh‐Kumar Manjira , Sun Siyang , Rossmann Michael G. , Rao Venigalla B.
Published: July 2008

Most tailed bacteriophages and herpes viruses replicate genome as a concatemer which is cut by a ‘headful’ nuclease upon completion of genome packaging. Here, the catalytic centre of phage T4 headful nuclease, present in the C‐terminal domain of ‘large terminase’ gp17, has been defined by mutational, biochemical and structural analyses. The crystal structure shows that this nuclease has an RNase‐H fold, suggesting that it cuts DNA by a two‐metal ion mechanism. The active centre has a Mg ion co‐ordinated by three acidic residues, D401, E458 and D542. Mutations at any of these residues resulted in loss of nuclease activity, but the mutants can package linear DNA. The gp17's nuclease activity is modulated by the ‘small terminase’, gp16, by the N‐terminal ATPase domain of gp17, and by the assembled packaging motor. These results lead to hypotheses concerning how phage headful nucleases cut the viral genomes before and after, but not during, DNA packaging.
Pheromone‐regulated target genes respond differentially to MAPK phosphorylation of transcription factor Prf1
Authors: Zarnack Kathi , Eichhorn Heiko , Kahmann Regine , Feldbrügge Michael
Published: July 2008

Pheromone signalling during mating is essential for pathogenicity of Ustilago maydis. The activity of the key transcription factor Prf1 is controlled at the transcriptional level and post‐translationally by mitogen‐activated protein kinase (MAPK) and protein kinase A (PKA) phosphorylation. However, the precise contribution of these regulatory mechanisms to the transcriptional output is unknown. Here, we genetically dissected the three levels of Prf1 regulation. We performed transcriptional profiling of respective mutants to identify and classify targets. This approach revealed that transcriptional regulation of prf1 had only minor influence on target gene expression stressing the importance of post‐translational control. PKA regulation of Prf1 was sufficient to control expression of nine pheromone‐responsive genes including the major transcription factor regulating pathogenicity. MAPK regulation was necessary for the pheromone response of a set of 57 genes. In 35 cases, pheromone responsiveness was completely lost, while in the remaining 22 cases regulation was alleviated. This indicated a novel level of complexity in MAPK signalling suggesting that target genes respond differentially to MAPK phosphorylation of the respective transcription factors.
Complement factor H allotype 402H is associated with increased C3b opsonization and phagocytosis of Streptococcus pyogenes
Authors: Haapasalo Karita , Jarva Hanna , Siljander Tuula , Tewodros Wezenet , Vuopio‐Varkila Jaana , Jokiranta T. Sakari
Published: July 2008

The main virulence factor of group A streptococcus (GAS), M protein, binds plasma complement regulators factor H (FH) and FH‐like protein 1 (FHL‐1) leading to decreased opsonization. The M protein binding site on FH is within domain 7 in which also the age‐related macular degeneration (AMD)‐associated polymorphism Y402H is located. We studied if FH allotypes 402H and 402Y have different binding affinities to GAS. Plasma‐derived FH allotype 402H and its recombinant fragment FH5‐7(402H) showed decreased binding to several GAS strains. Growth of GAS in human blood taken from FH(402H) homozygous individuals was decreased when compared with blood taken from FH(402Y) homozygous individuals. The effect of the allotype 402H can be explained by combining the previous M protein mutagenesis data and the recently published crystal structure of FH6‐8. In conclusion the data indicate that the AMD‐associated allotype 402H leads to diminished binding of FH to GAS and increased opsonophagocytosis of the bacteria in blood. These results suggest that the homozygous presence of the allele 402H could be associated with decreased risk for severe GAS infections offering an explanation for the high frequency of the allele despite its association with visual impairment.
Identification and characterization of two trypanosome TFIIS proteins exhibiting particular domain architectures and differential nuclear localizations
Authors: Uzureau Pierrick , Daniels Jan‐Peter , Walgraffe David , Wickstead Bill , Pays Etienne , Gull Keith , Vanhamme Luc
Published: July 2008

Nuclear transcription of Trypanosoma brucei displays unusual features. Most protein‐coding genes are organized in large directional gene clusters, which are transcribed polycistronically by RNA polymerase II (pol II) with subsequent processing to generate mature mRNA. Here, we describe the identification and characterization of two trypanosome homologues of transcription elongation factor TFIIS (TbTFIIS1 and TbTFIIS2‐1). TFIIS has been shown to aid transcription elongation by relieving arrested pol II. Our phylogenetic analysis demonstrated the existence of four independent TFIIS expansions across eukaryotes. While TbTFIIS1 contains only the canonical domains II and III, the N‐terminus of TbTFIIS2‐1 contains a PWWP domain and a domain I. TbTFIIS1 and TbTFIIS2‐1 are expressed in procyclic and bloodstream form cells and localize to the nucleus in similar, but distinct, punctate patterns throughout the cell cycle. Neither TFIIS protein was enriched in the major pol II sites of spliced‐leader RNA transcription. Single RNA interference (RNAi)‐mediated knock‐down and knockout showed that neither protein is essential. Double knock‐down, however, impaired growth. Repetitive failure to generate a double knockout of TbTFIIS1 and TbTFIIS2‐1 strongly suggests synthetical lethality and thus an essential function shared by the two proteins in trypanosome growth.
The ylo‐1 gene encodes an aldehyde dehydrogenase responsible for the last reaction in the Neurospora carotenoid pathway
Authors: Estrada Alejandro F. , Youssar Loubna , Scherzinger Daniel , Al‐Babili Salim , Avalos Javier
Published: July 2008

The accumulation of the apocarotenoid neurosporaxanthin and its carotene precursors explains the orange pigmentation of the Neurospora surface cultures. Neurosporaxanthin biosynthesis requires the activity of the albino gene products (AL‐1, AL‐2 and AL‐3), which yield the precursor torulene. Recently, we identified the carotenoid oxygenase CAO‐2, which cleaves torulene to produce the aldehyde β‐apo‐4′‐carotenal. This revealed a last missing step in Neurospora carotenogenesis, namely the oxidation of the CAO‐2 product to the corresponding acid neurosporaxanthin. The mutant ylo‐1, which exhibits a yellow colour, lacks neurosporaxanthin and accumulates several carotenes, but its biochemical basis is unknown. Based on available genetic data, we identified ylo‐1 in the Neurospora genome, which encodes an enzyme representing a novel subfamily of aldehyde dehydrogenases, and demonstrated that it is responsible for the yellow phenotype, by sequencing and complementation of mutant alleles. In contrast to the precedent structural genes in the carotenoid pathway, light does not induce the synthesis of ylo‐1 mRNA. In vitro incubation of purified YLO‐1 protein with β‐apo‐4′‐carotenal produced neurosporaxanthin through the oxidation of the terminal aldehyde into a carboxyl group. We conclude that YLO‐1 completes the set of enzymes needed for the synthesis of this major Neurospora pigment.
A versatile partner of eukaryotic protein complexes that is involved in multiple biological processes: Kti11/Dph3
Authors: Bär Christian , Zabel René , Liu Shihui , Stark Michael J. R. , Schaffrath Raffael
Published: July 2008

The Kluyveromyces lactis killer toxin zymocin insensitive 11 (KTI11) gene from Saccharomyces cerevisiae is allelic with the diphthamide synthesis 3 (DPH3) locus. Here, we present evidence that the KTI11 gene product is a versatile partner of proteins and operates in multiple biological processes. Notably, Kti11 immune precipitates contain Elp2 and Elp5, two subunits of the Elongator complex which is involved in transcription, tRNA modification and zymocin toxicity. KTI11 deletion phenocopies Elongator‐minus cells and causes antisuppression of nonsense and missense suppressor tRNAs (SUP4, SOE1), zymocin resistance and protection against the tRNase attack of zymocin. In addition and unlike Elongator mutants, kti11 mutants resist diphtheria toxin (DT), protect against ADP‐ribosylation of eukaryotic translation elongation factor 2 (eEF2) by DT and induce resistance against sordarin, an eEF2 poisoning antifungal. The latter phenotype applies to all diphthamide mutants (dph1‐dph5) tested and Kti11/Dph3 physically interacts with diphthamide synthesis factors Dph1 and Dph2, presumably as part of a trimeric complex. Moreover, we present a separation of function mutation in KTI11, kti11‐1, which dissociates zymocin resistance from DT sensitivity. It encodes a C‐terminal Kti11 truncation that almost entirely abolishes Elongator interaction without affecting association with Kti13, another Kti11 partner protein.
Mating type influences chromosome loss and replicative senescence in telomerase‐deficient budding yeast by Dnl4‐dependent telomere fusion
Authors: Meyer Damon H. , Bailis Adam M.
Published: July 2008

Summay

As we age, the majority of our cells gradually lose the capacity to divide because of replicative senescence that results from the inability to replicate the ends of chromosomes. The timing of senescence is dependent on the length of telomeric DNA, which elicits a checkpoint signal when critically short. Critically short telomeres also become vulnerable to deleterious rearrangements, end‐degradation and telomere–telomere fusions. Here we report a novel role of non‐homologous end‐joining (NHEJ), a pathway of double‐strand break repair in influencing both the kinetics of replicative senescence and the rate of chromosome loss in telomerase‐deficient Saccharomyces cerevisiae. In telomerase‐deficient cells, the absence of NHEJ delays replicative senescence, decreases loss of viability during senescence, and suppresses senescence‐associated chromosome loss and telomere–telomere fusion. Differences in mating‐type gene expression in haploid and diploid cells affect NHEJ function, resulting in distinct kinetics of replicative senescence. These results suggest that the differences in the kinetics of replicative senescence in haploid and diploid telomerase‐deficient yeast are determined by changes in NHEJ‐dependent telomere fusion, perhaps through the initiation of the breakage‐fusion‐bridge cycle.
Biosynthesis of mycobacterial arabinogalactan: identification of a novel α(1→3) arabinofuranosyltransferase
Authors: Birch Helen L. , Alderwick Luke J. , Bhatt Apoorva , Rittmann Doris , Krumbach Karin , Singh Albel , Bai Yu , Lowary Todd L. , Eggeling Lothar , Besra Gurdyal S.
Published: July 2008

The cell wall mycolyl‐arabinogalactan–peptidoglycan complex is essential in mycobacterial species, such as Mycobacterium tuberculosis and is the target of several antitubercular drugs. For instance, ethambutol targets arabinogalactan biosynthesis through inhibition of the arabinofuranosyltransferases Mt‐EmbA and Mt‐EmbB. A bioinformatics approach identified putative integral membrane proteins, MSMEG2785 in Mycobacterium smegmatis, Rv2673 in Mycobacterium tuberculosis and NCgl1822 in Corynebacterium glutamicum, with 10 predicted transmembrane domains and a glycosyltransferase motif (DDX), features that are common to the GT‐C superfamily of glycosyltransferases. Deletion of M. smegmatis MSMEG2785 resulted in altered growth and glycosyl linkage analysis revealed the absence of AG α(1→3)‐linked arabinofuranosyl (Araf) residues. Complementation of the M. smegmatis deletion mutant was fully restored to a wild‐type phenotype by MSMEG2785 and Rv2673, and as a result, we have now termed this previously uncharacterized open reading frame, arabinofuranosyltransferase C (aftC). Enzyme assays using the sugar donor β‐d‐arabinofuranosyl‐1‐monophosphoryl‐decaprenol (DPA) and a newly synthesized linear α(1→5)‐linked Ara5 neoglycolipid acceptor together with chemical identification of products formed, clearly identified AftC as a branching α(1→3) arabinofuranosyltransferase. This newly discovered glycosyltransferase sheds further light on the complexities of Mycobacterium cell wall biosynthesis, such as in M. tuberculosis and related species and represents a potential new drug target.
High resolution infrared spectra of NGC 6440 and NGC 6441: two massive bulge globular clusters
Authors: Origlia L. , Valenti E. , Rich R. M.
Published: July 2008

Using the NIRSPEC spectrograph at Keck II, we have obtained infrared echelle spectra covering the 1.5–1.8 μm range for giant stars in the massive bulge globular clusters NGC 6440 and NGC 6441. We report the first high-dispersion abundance for NGC 6440, [Fe/H]=−0.56 ± 0.02 and we find [Fe/H]=−0.50 ± 0.02 for the blue Horizontal Branch cluster NGC 6441. We measure an average α-enhancement of ≈+0.3 dex in both clusters, consistent with previous measurements of other metal rich bulge clusters, and favouring the scenario of a rapid-bulge formation and chemical enrichment. We also measure very low 12C/13C isotopic ratios (≈5 ± 1), suggesting that extra-mixing mechanisms are at work during evolution along the Red Giant Branch also in the high-metallicity regime. We also measure Al abundances, finding average [Al/Fe]= 0.45 ± 0.02 and [Al/Fe]= 0.52 ± 0.02 in NGC 6440 and 6441, respectively, and some Mg–Al anticorrelation in NGC 6441. We also measure radial velocities vr=−76 ± 3 and vr=+14 ± 3 km s−1 and velocity dispersions σ= 9 ± 2 and σ= 10 ± 2 km s−1 in NGC 6440 and 6441, respectively.
The shortest period field contact binary
Authors: Rucinski Slavek M. , Pribulla Theodor
Published: July 2008

Photometric and spectroscopic results for the contact binary GSC 01387–00475 (ASAS 083128+1953.1) are presented. The existence of this binary with the orbital period of P= 0.2178 d strengthens the argument that the cut-off of the period distribution for contact binaries – until now defined by CC Comae – is very sharp. The only case of a still shorter period is known in a globular cluster where more compact contact configurations are in fact expected. While the spectroscopic orbit of GSC 01387–00475 is well defined, the low orbital inclination of the binary and the presence of a spectroscopic companion contributing about 1/3 of the total light conspire to reduce the photometric variability to ≃0.09 mag. The photometric data are currently inadequate to identify the source of the small amplitude (0.02–0.03 mag) intrinsic variability of the system.
Vein patterning screens and the defectively organized tributaries mutants in Arabidopsis thaliana
Authors: Petricka Jalean Joyanne , Clay Nicole Kho , Nelson Timothy Mark
Published: July 2008

Leaf veins form a closed network that transports essential photosynthates, water and signaling molecules to the developing plant. The formation of the patterns of these networks during leaf ontogeny is an active subject of modeling and computer simulation. To investigate the vein patterning process, we performed screens for defects in juvenile leaf vein patterning in Arabidopsis thaliana lines subjected to mutagenesis via diepoxybutane, activation tagging or the Dissociation/Activator transposon. We identified over 40 vein pattern defective lines, providing a phenotypic resource for the testing of vein patterning models. In addition, we report the chromosomal linkage for 13 of these, eight of which were successfully cloned. We further describe the phenotypes of five of these mutants, which we call the defectively organized tributaries (dot) mutants, and their corresponding molecular identities. The diversity of the individual genes affected in this collection of pattern mutants suggests that vein pattern is highly sensitive to perturbations in many cellular processes. Despite this diversity of causes, the resulting pattern defects fall into a limited number of classes, including parallel, spurred, misaligned, open, midvein gap and irregularly spaced. These classes may represent sensitivities to cellular processes associated with the DOT genes. The ontogeny of common defective patterns should be accommodated into any robust model for the ontogeny and evolution of pattern.