Screening tests for bacteriuria based on two different principles were evaluated in1582 schoolgirls aged 5-11 years, and in 26 girls aged 3-16 years attending hospitalwith symptomatic urinary tract infection. Tests for hypoglucosuria, performed by a semi-automated fluorometric method and with Uriglox strips on early-morning urine samples voided after overnight fasting, gave unacceptably high false-negative rates (16.7% and 20.8% respectively). Oxoid and Uricult dipslides were immersed in fresh midstreamspecimens of urine obtained at school and read overnight incubation at 37 degrees C.Both gave comparable results, with low false-positive rates and no false-negative responses. The higher cost of screening by dipslides was halved by using the "dipstream" technique, which also gave no false-negative results. Its false-positive rate of 13.5% could be reduced to 1.8% by disregarding colony counts of 10-8 non-faecal organisms and over per litre, which appear unimportant in schoolchildren. Bacteriuria was found in 2.3% of the schoolgirls; 39% of them had symptons, compared with 7.2% of the healthy girls, and 25% showed vesicoureteric reflux, which in 17% was associated with renalscarring. Since the natural history of covert bacteriuria and its relationship withreflux and scarring remain undetermined further research is required. The dipstreamtechnique offers a simple, reliable, and comparatively cheap screening method which could also be applied in general practice. 相似文献
Island populations are often thought to be more susceptible to the loss of genetic diversity as a consequence of limited population
size and genetic drift, greater susceptibility to detrimental stochastic events and low levels of immigration. However the
geographic isolation of islands may create refuges for native crop species whose genetic diversity is threatened from the
genetic erosion occurring in mainland areas as a result of crop-wild gene flow and genetic swamping. Many UK islands remain
uncharacterised in terms of plant genetic diversity. In this study we compared the genetic diversity of mainland populations
and landraces of Trifolium repens with wild populations collected from the islands surrounding the UK, including the island of Hirta in the St Kildan archipelago.
Individuals from St Kilda represent a unique conservation resource, with populations both highly differentiated from UK mainland
populations and genetically distinct from cultivated varieties, whilst able to retain diversity through limited human influence
on the islands. In contrast, there is relative genetic similarity of wild UK populations to cultivated forms highlighted in
mainland populations, but with geographic barriers preventing complete homogenisation of the mainland UK genepool. We underline
the need for conservation priorities to include common species that are threatened by gene flow from cultivation, and draw
attention to the potential of islands to preserve natural levels of genetic diversity. 相似文献
In light of the growing concern over the potentially devastating impacts on biodiversity and food security of climate change
and the massively growing world population, taking action to conserve crop wild relatives (CWR), is no longer an option —
it is a priority. Crop wild relatives are species closely related to crops, including their progenitors, many of which have
the potential to contribute beneficial traits to crops, such as pest or disease resistance, yield improvement or stability.
They are a critical component of plant genetic resources for food and agriculture (PGRFA), have already made major contributions
to crop production and are vital for future food security; their systematic conservation in ways that ensure their continuing
availability for use is therefore imperative. This is a complex, interdisciplinary, global issue that has been addressed by
various national and international initiatives. Drawing on the lessons learnt from these initiatives we can now propose a
global approach to CWR conservation, the key elements of which are: (1) estimating global CWR numbers, (2) assessment of the
global importance of CWR diversity, (3) current conservation status, (4) threats to CWR diversity, (5) systematic approaches
to CWR conservation, (6) CWR informatics, and (7) enhancing the use of CWR diversity. 相似文献
Crop wild relatives are an important socio-economic resource that is currently being eroded or even extinguished through careless
human activities. If the Conference of the Parties (COP) to the CBD 2010 Biodiversity Target of achieving a significant reduction
in the current rate of loss is to be achieved, we must first define what crop wild relatives are and how their conservation
might be prioritised. A definition of a crop wild relative is proposed and illustrated in the light of previous Gene Pool
concept theory. Where crossing and genetic diversity information is unavailable, the Taxon Group concept is introduced to
assist recognition of the degree of crop wild relative relatedness by using the existing taxonomic hierarchy. 相似文献
Conservation programmes are always limited by available resources. Careful planning is therefore required to increase the efficiency of conservation and gap analysis can be used for this purpose. This method was used to assess the representativeness of current ex situ and in situ conservation actions of 234 priority crop wild relatives (CWR) in Indonesia. This analysis also included species distribution modelling, the creation of an ecogeographical land characterization map, and a complementarity analysis to identify priorities area for in situ conservation and for further collecting of ex situ conservation programmes. The results show that both current ex situ and in situ conservation actions are insufficient. Sixty-six percent of priority CWRs have no recorded ex situ collections. Eighty CWRs with ex situ collections are still under-represented in the national genebanks and 65 CWRs have no presence records within the existing protected area network although 60 are predicted to exist in several protected areas according to their potential distribution models. The complementarity analysis shows that a minimum of 61 complementary grid areas (complementary based on grid cells) are required to conserve all priority taxa and 40 complementary protected areas (complementary based on existing protected areas) are required to conserve those with known populations within the existing in situ protected area network. The top ten of complementary protected areas are proposed as the initial areas for the development of CWR genetic reserves network in Indonesia. It is recommended to enhanced coordination between ex situ and in situ conservation stakeholders for sustaining the long term conservation of CWR in Indonesia. Implementation of the research recommendations will provide for the first time an effective conservation planning of Indonesia’s CWR diversity and will significantly enhance the country’s food and nutritional security.
Amplified Fragment Length Polymorphisms (AFLPs) were used to study the taxonomic relationships in Vicia ser. Vicia. 109 accessions representing the taxa and distribution in the series were evaluated using two primer combinations in an attempt
to clarify its taxonomy. The study concludes that four species exist in the series. Viciaincisa should be considered as a separate taxon and does not belong to the Viciasativa aggregate. Within the series Viciapyrenaica appears to be the most closely related to the Viciasativa aggregate. Within the aggregate 6 taxa can be recognised. They are very closely related and for none of the taxa in the aggregate
is there a taxon-specific absence or presence of AFLP bands. We consider these taxa to be subspecies. Several accessions belonging
to the aggregate were found which could not be placed within one of the taxa and are most likely the products of mutations
or hybridisation between taxa.
Received March 12, 2001 Accepted July 12, 2001 相似文献