bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conjugal immunity of Streptomyces strains carrying the integrative element pSAM2 is due to the pif gene (pSAM2 immunity factor)
Authors: Possoz Christophe , Gagnat Josette , Sezonov Guennadi , Guérineau Michel , Pernodet Jean‐luc 
Published: March 2003

SummaryMechanisms of conjugal immunity preventing redundant exchange between two cells harbouring the same conjugative element have been reported in diverse bacteria. Such a system does exist for pSAM2, a conjugative and integrative element of Streptomyces. The apparition of the conjugative free form of pSAM2 in the donor strain during mating can be considered as the initial step of transfer. We analysed the genes involved in transfer inhibition by mating donors harbouring pSAM2 with recipient strains containing different regions of pSAM2. The conjugal immunity was previously thought to be mediated by the transcriptional repressor KorSA. Although the transfer efficiency is reduced by its presence in the recipient, the initiation of the transfer process is not affected. In contrast, the presence in the recipient strain of a single pSAM2 gene, pif (pSAM2 immunity factor), was sufficient to abolish both transfer and initiation of transfer. Thus, the clustered genes korSA and pif act complementarily to maintain pSAM2 in a ‘prophage’ state under non‐conjugal conditions. KorSA is involved in intracellular signalling, whereas Pif participates in intercellular signalling. The Pif nudix motif is essential for its activity. This is the first protein of the nudix family shown to be involved in bacterial conjugation.
Adaptation of the Lyme disease spirochaete to the mammalian host environment results in enhanced glycosaminoglycan and host cell binding
Authors: Parveen Nikhat , Caimano Melissa , Radolf Justin D. , Leong John M. 
Published: March 2003

SummaryThe Lyme disease spirochaete, Borrelia burgdorferi, is transmitted to mammals by Ixodes ticks and can infect multiple tissues. Host cell attachment may be critical for tissue colonization, and B. burgdorferi cultivated in vitro recognizes heparin‐ and dermatan sulphate‐related glycosaminoglycans (GAGs) on the surface of mammalian cells. To determine whether growth of the spirochaete in the mammalian host alters GAG binding, we assessed the cell attachment activities of B. burgdorferi grown in vitro or in dialysis membrane chambers implanted intraperitoneally in rats. Host‐adapted B. burgdorferi exhibited approximately threefold better binding to purified heparin and dermatan sulphate and to GAGs expressed on the surface of cultured endothelial cells. Three B. burgdorferi surface proteins, Bgp, DbpA and DbpB, have been demonstrated previously to bind to GAGs or to GAG‐containing molecules, and we show here that recombinant derivatives of each of these proteins were able to bind to purified heparin and dermatan sulphate. Immunofluorescent staining of in vitro‐cultivated or host‐adapted spirochaetes revealed that DbpA and DbpB were present on the bacterial surface at higher levels after host adaptation. Recombinant Bgp, DbpA and DbpB each partially inhibited attachment of host‐adapted B. burgdorferi to cultured mammalian cells, consistent with the hypothesis that these proteins may promote attachment of B. burgdorferi during growth in the mammalian host. Nevertheless, the partial nature of this inhibition suggests that multiple pathways promote mammalian cell attachment by B. burgdorferi in vivo. Given the observed increase in cell attachment activity upon growth in the mammalian host, analysis of host‐adapted bacteria will facilitate identification of the cell binding pathways used in vivo.
Elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion
Authors: Scheffer R. C. H. , Akkermans L. M. A. , Bais J. E. , Roelofs J. M. M. , Smout A. J. P. M. , Gooszen H. G. 
Published: March 2003

Abstract The aim of this study was to compare the effect of graded gastric barostat distension and meal‐induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P < 0.01) and the TLOSR rate during inflation and subsequent deflation (r = 0.96; P < 0.01) was found. A similar relationship was found for volume. In addition, after meal ingestion, the TLOSR rate increased significantly from 1.40 ± 3 to 5.4 ± 1.5 h−1 (P < 0.01) and 5.2 ± 1.7 h−1 (P < 0.01), respectively, during the first and second 30‐min postprandially. However, at similar calculated intragastric volumes, barostat distension led to a significantly higher TLOSR rate than the meal. Similarly, distension‐induced increase in gastric wall tension, estimated from the measured bag pressure and volume using Laplace's law, was associated with significantly higher TLOSR rates (P < 0.01). In conclusion, the rate of TLOSRs in healthy volunteers is directly related to the degree of proximal gastric distension and pressure‐controlled barostat distension is a more potent trigger of TLOSRs than a meal. The latter finding suggests that tension receptor activation is an important stimulus for TLOSRs.
Prognostic significance of Ki67, p53 and epidermal growth factor receptor immunostaining in human glioblastomas
Authors: Bouvier‐Labit  , Chinot  , Ochi  , Gambarelli  , Dufour  , Figarella‐Branger  
Published: March 2003

gabctgPrognostic significance of Ki67, p53 and epidermal growth factor receptor immunostaining in human glioblastomasSince glioblastomas in adults are uniformly fatal, evaluation of easily reproducible prognostic criteria which would attempt to define groups of patients is required. However, there is lack of a clear consensus regarding the expression of some markers in the literature. Therefore, an immunohistochemical study was performed to determine the prognostic significance of Ki67, p53, and epidermal growth factor receptor (EGFR) in a retrospective series of 63 glioblastomas. Image analysis was carried out in positive specimens to quantify the immunoprecipitates. p53 and EGFR expression were specifically addressed in the 36 primary glioblastomas reported in this series. In all cases, clinical data (age, Karnofsky performance scale index [KPS] before surgery, extent of surgery) and immunohistochemical features were analysed using univariate and multivariate analysis to ascertain whether any significant correlation exists between [1] EGFR expression [2], p53 accumulation [3], Ki67 labelling index and prognosis (survival time and disease‐free survival time, DFST). The results showed that in this series of glioblastomas, none of these markers had any prognostic value. Among the clinical parameters, a high KPS before surgery was found to be indicative of a shorter DFST and survival time (P<0.05), whereas a younger age at onset and total or subtotal surgical excision were associated with a longer survival (P<0.001 and 0.05, respectively). EGFR protein accumulation was inversely correlated with p53 accumulation (P=0.01). The percentage of the primary glioblastomas expressing EGFR was much lower in our study (33%) than in the literature suggesting that the molecular distinction between primary and secondary glioblastomas is not so clear‐cut.
Muscle pathology in dysferlin deficiency
Authors: Fanin M. , Angelini C. 
Published: March 2003

Dysferlin deficiency is being increasingly recognized in limb‐girdle dystrophy and distal myopathy but its role in the development of muscle pathology is still poorly understood. For this purpose, 26 muscle biopsies from 25 dysferlinopathy patients were analysed by routine histochemistry and by immunohistochemistry with eight different antibodies, and scored for inflammatory response and type of cell infiltrate, fibre degeneration and regeneration, fibre type composition and severity of histopathological changes. In cases with an advanced‐stage dystrophic pattern we observed type 1 fibre predominance exceeding 80%, suggesting a selective loss of type 2 fibres or a conversion process.The extent of muscle fibre regeneration and degeneration in dysferlinopathy was intermediate between sarcoglycanopathy and Duchenne dystrophy or myositis, suggesting a rather aggressive course of the disease. An increased inflammatory response was observed in the majority of our patients (16/26), who also showed an active dystrophic pattern. Type and localization of cellular infiltrates suggest that inflammatory reaction is secondary to necrosis. Major histocompatibility complex (MHC) class I molecules were overexpressed in dysferlinopathy, mainly in association with fibre phagocytosis and regeneration; their occasional expression in non‐necrotic fibres might represent a marker of ongoing necrosis. Muscle inflammation might be triggered by the structurally altered membrane consequent to dysferlin defect.
Congenital arteriovenous fistula of the brain with an atrial septal defect: case report
Authors: Hortobágyi T. , Szüts Á. , Csenki M. , Bódi I. 
Published: March 2003

Introduction:  Aneurysmal malformation of the vein of Galen (AVG) is caused by an arteriovenous fistula (AVF) between the basal arteries and deep venous sinuses of the brain. Congenital forms of AVG are potentially fatal, leading to a left‐to‐right shunt and cardiomegaly, and the death is most commonly as a result of cardiac failure. We present a case with an AVF of brain with an ASD.Material and methods:  A mature male baby born at gestational week 38 was admitted to PICU with tachydyspnoe 4 h after birth. Ultrasound (US) and computed tomography scans of the brain detected a large bilateral AVF with dilated basal arteries and venous sinuses (sinus petrosus, sinus confluens, sinus transvs. and sagittal inferior sinus), hydrocephalus and brain atrophy. Cardiac US showed right ventricular hypertrophy, persistent ductus Botall and ASD. The patient died of cardiac failure 6 days after birth.Results:  Autopsy examination of the brain showed dilatation of the vein of Galen and venous sinuses, a large conglomerate of dilated blood vessels in the midline and left occipital lobe, oedema and hydrocephalus. Examination of the heart confirmed Us findings and showed an ostium secundum ASD. Histologically, the occipital mass revealed features of an AVF, consistent with AVG. Chronic ischaemic lesions with ferruginated neurons were also present.Conclusions:  The presence of chronic hypoxic changes in the brain suggests intrauterine damage as a result of a congenital AVF. The left‐to‐right shunt, in addition to causing cardiomegaly, may also have interfered with the development of the atrial septum, leading to an ostium secundum ASD, aggravating the clinical course.
The population status of chameleons within Ranomafana National Park, Madagascar, and recommendations for future monitoring
Authors: Jenkins Richard K. B. , Brady Lee D. , Huston Kieron , Kauffmann Juliet L. D. , Rabearivony Jeanneney , Raveloson Georges , Rowcliffe J. Marcus 
Published: March 2003

AbstractMalagasy chameleons are threatened by the relentless pace of habitat destruction. Their great popularity amongst herpetoculturalists has also resulted in collection for international animal markets. Most previous fieldwork has focused on the compilation of much needed species inventories, but little attention has been given to estimating chameleon population densities. This lack of information prevents a reliable assessment of the effects ofhabitat loss and direct exploitation on wild populations. A simple and repeatable methodology for the monitoring of chameleon populations is therefore urgently required. The present study developed survey techniques based on distance sampling within an area of relatively undisturbed rain forest at Ranomafana National Park. In total 394 individuals from six species were recorded and population densities (± SE) of 27.2 ± 5.4/ha Brookesia spp. and 21.4±4.0/ha Calumma spp. were estimated using the computer program DISTANCE. The authors propose that monitoring of chameleons in areas subject to different threats should begin immediately using the methods outlined in this paper.
First steps towards the conservation of the microendemic Patagonian frogAtelognathus nitoi
Authors: Úbeda Carmen , Zagarese Horacio , Diaz Mónica , Pedrozo Fernando 
Published: March 2003

AbstractAtelognathus nitoiis a microendemic leptodactylid frog restricted to the area surrounding the pond Laguna Verde in the Nahuel Huapi National Reserve, north-west Patagonia, Argentina. Its habitat is potentially threatened by a number of anthropogenic and natural factors. The aim of this study was to obtain basic knowledge of the biology and habitat of the species, which would be useful for selecting management measures to ensure its conservation. The area was surveyed during all four seasons in 1996 and 1997 and Laguna Verde was sampled intensively in winter and in summer.Atelognathus nitoiis distributed patchily. The preferred microhabitats of adults and juveniles are the most humid areas of the forest. Reproduction and larval development occurs only in lentic environments. Laguna Verde is the only known permanent waterbody suitable for reproduction every year. During rainy years reproduction can also take place in temporary ponds. Action towards the conservation ofA.nitoishould be aimed at preserving both the terrestrial and aquatic habitats. Laguna Verde appears to be a key site for theA. nitoisource population and plays an essential part in the conservation of this species. In terrestrial habitats it is vital to preserve the heterogeneity of the lower strata in the forest. The knowledge gained through this study has allowed the authors to suggest protective measures to mitigate or eliminate the impact of certain stressors on the ecology of the species.
Przewalski's horse—adaptation to semi-wild life in desert conditions
Authors: Pereladova O. B. , Sempéeré A. J. , Soldatova N. V. , Dutov V. U. , Fisenko G. , Flint V. E. 
Published: March 2003

AbstractIn 1989 an experiment was started at the Bukhara Breeding Centre, Kyzylkum Desert, Uzbekistan, to discover whether zoo-bred Przewalski's horses Equus przewalskiicould adapt to semi-wild desert conditions. One stallion and four mares of different ages were released into a 5126-ha fenced area and monitored over a period of 17 years. This paper presents the information gained from the studies concerning home ranges, interactions with other ungulate species, adaptation to new food resources and comparative changes in daily activity. The results of breeding and changes in the structure of the group are also presented. The horses appeared to adapt well to the new conditions and there appeared to be no negative effects of interspecific interaction with introduced kulans Equus hemionus kulan in the release area.
Conserving the African wild dog Lycaon pictus. II. Is there a role for reintroduction?
Authors: Woodroffe Rosie , Ginsberg Joshua R. 
Published: March 2003

AbstractAfrican wild dogs Lycaon pictus have been extirpated across most of West and central Africa, and greatly depleted in eastern and southern Africa. Given an urgent need for population recovery, especially in West and central Africa, this paper discusses the possibilities for using reintroduction to re-establish wild dog populations. Reintroduction is probably now technically possible, as long as release groups include wildcaught animals; several past attempts failed because captive-reared animals lacked skills needed to survive in the wild. However, reintroduction has only a limited role to play in wild dog conservation. Ideally, it should involve animals of the appropriate local genotype. Limited genetic data indicate that wild dogs from West and central Africa may be distinct from those in eastern and southern Africa. Because there are no wild dogs with West or central African genotypes in captivity, and no wild populations in the region large enough to be harvested for translocation, future reintroductions might have to use animals with non-native genotypes. In addition, there appear to be no suitable sites for wild dog reintroduction in West or central Africa, and few in eastern and southern Africa. Releases currently planned in the Republic of South Africa will be locally valuable, but will not establish a population likely to remain viable without intensive management in perpetuity. For these reasons, protecting remaining wild dog populations currently represents a better investment than any attempt at reintroduction.
Elephant corridors in India: lessons for other elephant range countries
Authors: Johnsingh A. J. T. , Williams A. Christy 
Published: March 2003

AbstractThe conservation status of five elephant corridors in different regions of India is discussed. Elephants have not used the 13-km-wide corridor between Ariankavu and Thenmalai, in the southern portion of the Western Ghats for several decades because a rail track and road, both of which are bordered by human habitations, cross it. The future of the Chilla–Motichur and Rajaji–Corbett corridors, which hold the Rajaji–Corbett elephant population in north-west India as one entity, is bleak. It is still possible for elephants to use the Kallar–Jaccanari corridor linking the 4000-strong elephant population of northern and southern Nilgiri Biosphere Reserve in southern India. It may be possible to save the Siju–Rewak corridor, which connects the elephant populations on either side of the River Simsang in north-east India. The authors suggest that other Asian countries that have elephant populations and that are capable of establishing large conservation units, should have master plans that should detail possible developmental activities around existing wildlife habitats. Establishing vast protected areas for large mammals, however, would need political will and regular communication among the nations' development planners, wildlife managers and researchers.
Status of wild Bactrian camels and other large ungulates in south-western Mongolia
Authors: Reading Richard P. , Mix Henry , Lhagvasuren Badamjaviin , Blumer Evan S. 
Published: March 2003

AbstractWild Bactrian camels Camelus bactrianus ferus are endangered. Surveys over the past several decades suggest a marked decline in camel numbers and reproductive success. However, most surveys were made using methods that precluded rigorous population estimation. The need for more accurate surveys resulted in an aerial survey of known and suspected camel habitat in Mongolia during March 1997. We estimated density, group density and population size of large mammals in south-western Mongolia using the interactive computer program DISTANCE. We recorded sufficient data for population modelling of wild Bactrian camels, goitred gazelles Gazella subgutturosa, Asian wild asses Equus hemionus and argali sheep Ovis ammon. We observed 277 camels in 27 groups (mean group size = 10.26 ± 2.38 SE camels/group). Modelling yielded a population estimate of 1985 ± 802 SE camels in the survey area. Population modelling for other ungulates yielded estimates of 6046 ± 1398 SE goitred gazelles, 1674 ± 506 SE Asian wild asses and 909 ± 303 SE argalis. Discrepancies between population estimates of ungulates in our survey and previous surveys are discussed with regard to methods used and robustness of results obtained. We also discuss conservation implications for wild Bactrian camels and other Mongolian ungulates.
Strategic conservation interventions in a region of high biodiversity and high vulnerability: a case study from the Agulhas Plain at the southern tip of Africa
Authors: Heydenrych Barry J. , Cowling Richard M. , Lombard Amanda T. 
Published: March 2003

AbstractIn terms of the persistence of biodiversity, the siting of conservation areas has traditionally beenad hoc.In the Cape Floristic Region, a hot-spot of plant biodiversity and endemism, past conservation interventions have led to the mountains being over-represented in the reserve network, while the lowlands have remained very poorly conserved. Ongoing threats to the lowlands such as the rampant spread of invasive alien plants, and land transformation for agriculture and resort development, continue to undermine biodiversity in these regions. A new conservation intervention, the Agulhas National Park, is in the process of being implemented on the coastal lowlands at Africa's southernmost tip. A flexible, reserve-selection design tool is being used to guide this process. The practical challenges in implementing a new protected area in a fragmented landscape, which has a high biodiversity and vulnerability, are examined. The role of different institutions, in partic-in particular state-private partnerships, and current investigations into conservation agencies' policies, legislation and funding mechanisms are dealt with. It is imperative that future conservation planning considers the threats to biodiversity first and foremost. Institutions such as South African National Parks and the Cape Nature Conservation Board must act strategically to avoid changes in land use that will compromise the biodiversity goals of retention and persistence. Conservation efforts will only succeed if institutional and socio-economic considerations are integrated with conservation plans aimed at ensuring the long-term persistence of biodiversity.
Bearded sakis in south-eastern Amazonia—back from the brink?
Authors: Ferrari Stephen F. , Emidio-Silva Claudio , Lopes M. Aparecida , Bobadilla Urbano L. 
Published: March 2003

AbstractThe endemic bearded sakisChiropotes satanas SatanasandChiropotes satanas utahickiof south-eastern Amazonia are among the most threatened of this region's primates because of a combination of deforestation and hunting, and their apparent intolerance of habitat disturbance. Recent surveys at eight sites confirm that sakis are locally extinct in some areas where intense habitat fragmentation is exacerbated by hunting pressure, but also show that, in the absence of hunting, they can be relatively abundant in isolated forest fragments. Density was unexpectedly low in one protected area, however, which implies that caution is necessary for the planning of long-term conservation strategies. Well-protected forest fragments of reasonable size ( > 5000 ha) appear to have good potential for the protection of bearded saki populations. While many of the region's major landowners may thus make a significant contribution to the management of saki populations, land conflicts are a potentially serious problem for the long-term conservation of not just these primates, but the region's fauna and flora as a whole.
The potential role of safari hunting as a source of revenue for protected areas in the Congo Basin
Authors: Wilkie David S. , Carpenter Julia F. 
Published: March 2003

AbstractIn sub-Saharan Africa conservation of biodiversity is increasingly predicated on finding ways to ensure that the economic value of maintaining a landscape in its ‘natural’ state meets or exceeds the expected returns from converting the area to an alternative land use, such as agriculture. ‘Wildlands’ in Africa must generate, directly or from donor contributions, funds sufficient to cover both the operating costs of conservation, and the opportunity costs of forgoing other forms of resource use. Government and donor investments currently meet less than 30 per cent of the estimated recurring costs required to manage the protected-area network within central African countries effectively, and cover none of the growing opportunity costs incurred to maintain protected areas. Unfortunately, few additional sources of funding are available.