849 research outputs found
A last glacial ice sheet on the Pacific Russian coast and catastrophic change arising from coupled ice–volcanic interaction
Controversy exists over the extent of glaciation in Eastern Asia at the Last Glacial Maximum:
complete ice sheet cover vs. restricted mountain icefields (an area discrepancy equivalent to
3.7 Greenland Ice Sheets). Current arguments favour the latter. However, significant last
glacial ice-rafted debris (IRD) exists in NW Pacific ocean cores, which must have been
sourced from a major ice sheet somewhere bordering the North Pacific. The origin of this IRD
is addressed through a combination of marine core analysis, iceberg trajectory modelling and
remote sensing of glacial geomorphology. We find compelling evidence for two stages of
glaciation centred on the Kamchatka area of maritime southeast Russia during the last glacial,
with ice extent intermediate in size between previous maximum and minimum
reconstructions. Furthermore, a significant increase in iceberg flux precedes, and
accompanies, a substantial marine core ash deposit at around 40ka BP. We speculate that
rapid decay of the first stage of the ice sheet may have triggered substantial volcanic activity
Adaptation of commercial wheat cultivars to fall-seeding
Non-Peer Reviewe
Molecular genetic variability, within a population of Mycosphaerella graminicola, cause of Septoria tritici leaf blotch of wheat
Non-Peer ReviewedThe pathogen Mycosphaerella graminicola (anamorph Septoria tritici), causes speckled leaf blotch of wheat and has worldwide distribution. Information about genetic variability of the pathogen population is useful for development of disease management strategies. In this study 90 isolates of M. graminicola were collected using a hierarchical sampling procedure from a single wheat field and the genomic DNA of isolates were extracted. RAPD analysis was conducted using 15 random primers, according to standard protocols. Forty molecular phenotypes were detected which phenotype 1 had the highest frequency within the population. The total genotypic diversity was estimated as 0.94.When it was partitioned into within and among location components, 91% of the genetic diversity occurred within locations and only 9% occurred
among locations. Low degree of variability among locations and high degree of variability within locations, points that, most likely the source of primary inoculum was air-borne ascospores, which were dispersed evenly across the field. This finding suggests that, the sexual stage of M. graminicola, occurs in Saskatchewan, although it has not yet been reported from Canada. High degree of genetic variability implies that most likely the pathogen will adapt rapidly to single gene resistance sources, therefore, in breeding for disease resistance, emphasis should be given to non- race specific resistance
Identification of new sources of resistance to tan spot of wheat
Non-Peer ReviewedTan spot, caused by Pyrenophora tritici-repentis, is a major foliar disease of wheat in
western Canada. Isolates of P. tritici-repentis are presently classified into 11 races based
on their virulence on a set of wheat differential cultivars. In western Canada only 5 of
these races have been identified. More than 1000 accessions of wheat including
synthetics and wild relatives were evaluated for resistance against all the virulent races of
P. tritici-repentis that are prevalent in western Canada. Disease screening was done
under controlled environmental conditions at the seedling stage. High level resistance to
P. tritici-repentis was observed in some accessions of Triticum monococum, T. turgidum,
T. dicoccum, T. dicoccoides, T. timopheevii, and T. aestivum including synthetic wheat.
These accessions also showed good resistance to the leaf spot disease stagnospora
nodorum blotch. They will be studied further to determine the genetic basis of resistance
and to transfer their resistance to adapted wheat and durum cultivars
Evaluation of a putatively very high yielding "miracle" spring wheat
Non-Peer ReviewedA supposedly very high yielding branched spike wheat (BSW) was shown to yield as much as 75 % less than standard Canada Western Red Spring (CWRS) cultivars when severely infected with leaf and stem rust. With little or no disease pressure BSW still yielded 25-30% less than semi-dwarf wheat cultivars under both dryland and irrigated conditions. The BSW was very tall and later maturing than HY 320. Kernel and quality characteristics of BSW would appear to limit its market potential regardless of yield
Evaluation of a putatively very high yielding "miracle" spring wheat
Non-Peer ReviewedA supposedly very high yielding branched spike wheat (BSW) was shown to yield as much as 75 % less than standard Canada Western Red Spring (CWRS) cultivars when severely infected with leaf and stem rust. With little or no disease pressure BSW still yielded 25-30% less than semi-dwarf wheat cultivars under both dryland and irrigated conditions. The BSW was very tall and later maturing than HY 320. Kernel and quality characteristics of BSW would appear to limit its market potential regardless of yield
A review of migratory behaviour of sea turtles off southeastern Africa
The survival of sea turtles is threatened by modern fishing methods, exploitation of eggs and habitat destruction. Forming keystone species in the ocean, their extinction would disrupt the marine food chain in ways as yet unknown. The Indian Ocean has many breeding areas for sea turtles, the southernmost ones being on the Maputaland coast of KwaZulu-Natal, where loggerhead and leatherback turtles nest in large numbers thanks to long-lasting protection programmes. For the leatherback this is the only known nesting site in the entire western Indian Ocean. At the end of the reproductive season, both loggerheads and leatherbacks undertake migrations towards disparate feeding areas. To contribute to their conservation, the migratory behaviour of these animals needs to be understood. Here we review 10 years studying this behaviour using transmitters that telemeter data via satellite. It emerges that these species frequent widely dispersed areas ranging from the Atlantic Ocean to the Mozambique Channel. The migratory behaviour of leatherback and loggerhead turtles is, however, very different, probably due to their differing food requirements. While loggerhead postnesting movements have a truly migratory nature, the large-scale wanderings of leatherbacks are better described as prolonged sojourns in extended feeding areas
Trends in sexually transmitted infections in general practice 1990-2000: population based study using data from the UK general practice research database
Objective: To describe the contribution of primary care to the
diagnosis and management of sexually transmitted infections in
the United Kingdom, 1990-2000, in the context of increasing
incidence of infections in genitourinary medicine clinics.
Design: Population based study.
Setting: UK primary care.
Participants: Patients registered in the UK general practice
research database.
Main outcome measures: Incidence of diagnosed sexually
transmitted infections in primary care and estimation of the
proportion of major such infections diagnosed in primary care.
Results: An estimated 23.0% of chlamydia cases in women but
only 5.3% in men were diagnosed and treated in primary care
during 1998-2000, along with 49.2% cases of non-specific
urethritis and urethral discharge in men and 5.7% cases of
gonorrhoea in women and 2.9% in men. Rates of diagnosis in
primary care rose substantially in the late 1990s.
Conclusions: A substantial and increasing number of sexually
transmitted infections are diagnosed and treated in primary
care in the United Kingdom, with sex ratios differing from
those in genitourinary medicine clinics. Large numbers of men
are treated in primary care for presumptive sexually
transmitted infections
The Impact of a 48-Hour Fast on Mitochondrial Biogenesis in Young Healthy Men
Please view abstract in the attached PDF fil
- …