Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Snow”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed1998

Changes in pituitary and adrenal sensitivities allow the snow bunting (Plectrophenax nivalis), an Arctic-breeding song bird, to modulate corticosterone release seasonally.

Several free-living avian species have recently been shown to seasonally modulate corticosterone release in response to capture and restraint. We examined possible mechanisms underlying seasonal adrenocortical modulation in snow buntings (Plectrophenax nivalis), a species that breeds and molts (the energetically costly replacement of feathers) in the Alaskan Arctic Snow buntings dramatically reduced baseline and maximal corticosterone titers during molt compared to the breeding season. This effect is not explained by changes in either corticosterone binding protein capacity or the overall condition of the bird (assessed by weight and fat storage). Although the adrenal's capacity to secrete corticosterone is reduced during molt, adrenal insensitivity does not fully explain reduced maximal output since exogenous adrenocorticotropic-hormone enhanced corticosterone release during both seasons. In contrast, no exogenous adrenocorticotropic hormone releasing factor (corticotrophin-releasing factor, arginine vasotocin or mesotocin) enhanced corticosterone secretion during molt. This suggests that the pituitary's endogenous adrenocorticotropic secretion was maximal in response to capture and handling, making the pituitary an important site regulating corticosterone levels. Taken together, these results indicate that seasonal modulation of corticosterone release in this species is controlled at both the adrenal and pituitary glands.

Adrenal Glands↗
PubMed2005

A cold inducible multidomain cystatin from winter wheat inhibits growth of the snow mold fungus, Microdochium nivale.

A novel cold-induced cystatin cDNA clone (TaMDC1) was isolated from cold acclimated winter wheat crown tissue by using a macroarray-based differential screening method. The deduced amino acid sequence consisted of a putative N-terminal secretory signal peptide of 37 amino acids and a mature protein (mTaMDC1) with a molecular mass of 23 kDa. The mTaMDC1 had a highly conserved N-terminal cystatin domain and a long C-terminal extension containing a second region, which exhibited partial similarity to the cystatin domain. The recombinant mTaMDC1 was purified from Escherichia coli and its cysteine proteinase inhibitory activity against papain was analyzed. The calculated Ki value of 5.8 x 10(-7) M is comparable to those reported for other phytocystatins. Northern and western blot analyses showed elevated expression of TaMDC1 mRNA and protein during cold acclimation of wheat. In addition to cold, accumulation of the TaMDC1 message was induced by other abiotic stresses including drought, salt and ABA treatment. Investigation of in vitro antifungal activity of mTaMDC1 showed strong inhibition on the mycelium growth of the snow mold fungus Microdochium nivale. Hyphae growth was totally inhibited in the presence of 50 mug/ml mTaMDC1 and morphological changes such as swelling, fragmentation and sporulation of the fungus were observed. The mechanisms of the in vitro antifungal effects and the possible involvement of TaMDC1 in cold induced snow mold resistance of winter wheat are discussed.

Amino Acid Sequence↗
PubMed2006

Solar furnaces or swamp coolers: costs and benefits of water use by solar-tracking flowers of the alpine snow buttercup, Ranunculus adoneus.

Solar tracking or heliotropism simultaneously raises organ temperature and light interception. For leaves and flowers carbon gain is maximized at the expense of water loss. In this study I explore how costs and benefits associated with water use by solar-tracking flowers of the alpine snow buttercup, Ranunculus adoneus change with ambient temperature. First, I test whether heliotropism increases the water cost of reproduction in the snow buttercup under extant alpine conditions. I then explore whether water use for evaporative cooling in solar-tracking flowers reduces the risk of over-heating as temperatures increase. Solar tracking, by elevating floral temperature and irradiance causes a 29% increase in water uptake by flowers. Gas exchange measurements suggest that the extra water taken up by solar-tracking flowers is released through transpiration. Transpirational cooling in turn allows solar-tracking flowers to gain advantages of enhanced light interception and warmth while reducing the risk of over-heating. Transpiration reduces excess temperature in solar-tracking flowers, but at a water cost. Results show that even in cool alpine habitats, flower heliotropism has water costs to balance its reproductive advantages. Plants with solar-tracking flowers may tolerate hotter conditions if soil moisture is plentiful, but not under drought.

Feedback, Physiological↗
PubMed1984

Tyzzer's disease in snow leopards.

Tyzzer's disease was diagnosed histologically in 2 litters of newborn snow leopard kittens. The gross and histological lesions were similar to those reported in domestic cats and other animals. No signs of illness was noted in either of the snow leopard dams.

Animals↗
PubMed1991

Snow skiing for the physically disabled.

The sport of snow skiing by the physically disabled, which originated in Europe in 1935 and first received attention in the United States in the 1940s, is reviewed in terms of opportunities available, instructions, adaptive equipment necessary, and benefits provided. Persons with a wide variety of disabilities (such as cerebral palsy, multiple sclerosis, spinal cord injury, hemiplegia, amputation, blindness, spina bifida, and muscular dystrophy) can participate. Accordingly, a wide range of adaptive equipment is available--including outrigger skis, flip-skis, canting wedges, ski bras, "toe spreaders," sit-skis, and mono-skis--to allow safe enjoyment of the sport. Programs for instruction of the disabled skier are increasing in number and popularity, and numerous opportunities are available to enter competitive events sponsored by National Handicapped Sports. Both the participants and the instructors relate the numerous physical and psychologic benefits that can be derived from skiing; the sport provides an almost universal enjoyment of the sense of freedom and independence. Snow skiing is an enjoyable, beneficial, outdoor cold-weather activity that the disabled population can safely learn with proper instruction.

Adaptation, Physiological↗
PubMed2001

Observations of scent-marking and discriminating self from others by a domestic dog (Canis familiaris): tales of displaced yellow snow.

Little is known about what stimuli trigger urinating or scent-marking in domestic dogs, Canis familiaris, or their wild relatives. While it is often suggested that the urine of other animals influences urinating and scent-marking patterns in canids, this has not been verified experimentally. To investigate the role of urine in eliciting urinating and marking, in this pilot study I moved urine-saturated snow ('yellow snow') from place-to-place during five winters to compare the responses of an adult male domestic dog, Jethro, to his own and others' urine. Jethro spent less time sniffing his own urine than that of other males or females, and that while his interest in his own urine waned with time it remained relatively constant for other individuals' urine. Jethro infrequently urinated over or sniffed and then immediately urinated over (scent-marked) his own urine. He marked over the urine of other males more frequently than he marked over females' urine. The method used here can be extended to other species for which experimental data are lacking. Though based on one dog, these novel data may further our knowledge of the role of scent-marking in territorial behavior and of sex differences in territory acquisition and maintenance.

Journal Article↗
PubMed2001

Computational cell biologists snowed in at Cranwell.

Cell biology is being inundated by an avalanche of data from the genomics and proteomics enterprises. The complexity and sheer volume of information threaten to overwhelm the ability of traditional cell biologists to grasp its implications and develop experimentally testable hypotheses. For this reason, some have begun to explore computational approaches towards organizing complex data into quantitative models. This requires communication and collaboration between the biological science community and and the physical and mathematical sciences communities. A recent meeting [The First International Symposium on Computational Cell Biology, Cranwell Resort, Lenox, MA, USA; 4-6 March 2001. Organizers: J.H. Carson, A. Cowan, and L.M. Loew (www.nrcam.uchc.edu/conference).] made a first attempt to bring these two communities together. Three feet of new snow fell during the meeting, but the 125 attendees, an unusual mixture of cell biologists, computer scientists, mathematicians, physicists, and engineers, were having too much fun defining the new field of computational cell biology to notice that they were literally snowed in.

Animals↗
PubMed2004

Genetic variability of grey snow mould (Typhula incarnata).

Randomly amplified polymorphic DNA (RAPD) markers were used to assess the genetic diversity of isolates of grey snow mould ('gray snow mold'), Typhula incarnata, taken from infected turfgrasses from 40 different locations in the northern USA. Data from 115 markers using 37 RAPD primers showed 48 % polymorphism. The distance coefficients between isolates indicate the wide genetic diversity of T. incarnata across the sample area. Dendrograms generated using neighbour-joining (NJ) bootstrap analyses showed three clades and suggest possible recent colonization from common founder groups. Partitioning of the genetic variance using analysis of molecular variance (AMOVA) of four groups based on geographic locations (Michigan, lower and upper peninsula; Minnesota; Wisconsin) showed that genetic variation attributable among groups and within groups was 12.67 and 87.33 %, respectively. No correlation was found between geographic distance and pairwise genetic distance of the groups. High outcrossing and sexual recombination of T. incarnata may well be key factors explaining the genetic variability as shown with the low Fixation index (FST) and high average of genetic diversity per locus within groups.

Basidiomycota↗
PubMed2004

Determination of stable carbon isotopic compositions of low molecular weight dicarboxylic acids and ketocarboxylic acids in atmospheric aerosol and snow samples.

We report a new method developed for the determination of stable carbon isotopic composition of homologous alpha,omega-dicarboxylic acids and phthalic acid isolated from environmental samples such as atmospheric aerosols and snow. Dicarboxylic acids are derivatized with BF3/1-butanol to dibutyl esters, which are analyzed for the stable carbon isotopic composition using a capillary GC interfaced to on-line combustion isotope ratio mass spectrometer. The delta13C values for individual dicarboxylic acid are then calculated from delta13C of 1-butanol and butyl ester derivative using a mass balance equation. The accuracy of the delta13C measurement for C2-C10 diacids is within 0.8 per thousand. We report a few examples of the delta13C ratios of saturated C2-C9 alpha,omega-dicarboxylic acids, unsaturated (maleic, phthalic) diacids, and oxocarboxylic acids in the aerosol and snow samples.

Journal Article↗
PubMed2003

Lytic activity of l-menthol derivatives against the snow blight disease fungus, Micronectriella nivalis.

Lytic activity of l-menthol (1) derivatives [(-)-(1S,3R,4S,6S)-6-hydroxymenthol (2), (-)-(1S,3R,4S)-1-hydroxymenthol (3), and (+)-(1S,3R,4R,6S)-6,8-dihydroxymenthol (4)] against the snow blight disease fungus, Micronectriella nivalis was investigated. Compounds 2, 3, and 4 had 85.0, 63.9, and 81.9% lytic activity, respectively, at a concentration of 0.2 mg/mL. The activity of each of the three compounds increased in a dose-response manner. To study the structure-activity relationship, acetyl esters of 1-4 [(-)-menthyl acetate (1Ac), (-)-6-hydroxymenthyl diacetate (2Ac), (-)-1-hydroxymenthyl 3-monoacetate (3Ac), and (-)-6,8-dihydroxymenthyl 3,6-diacetate (4Ac)] were synthesized with yields of 80.2-99.8% and were also assayed. The acetyl esters of 1Ac, 2Ac, 3Ac, and 4Ac had 51.2, 91.5, 66.0, and 95.2% lytic activity, respectively, at a concentration of 0.2 mg/mL, and these compounds showed further high lytic activity compared with the alcohols of 1-4. These acetyl esters also showed higher lytic activity as their concentration was increased. Of particular interest is the fact that 2Ac and 4Ac both had higher lytic activity at 0.05-0.2 mg/mL compared with copper 8-hydroxyquinolate, a standard chemical widely used to control snow blight. This is the first report on lytic activity of l-menthol derivatives.

Acetylation↗
PubMed2002

Abscisic acid- and cold-induced thaumatin-like protein in winter wheat has an antifungal activity against snow mould, Microdochium nivale.

Cold acclimation of winter wheat (Triticum aestivum L.) seedlings induces accumulation in the apoplast of taTLPs that are similar to thaumatin-like proteins (TLPs), which are pathogenesis-related proteins. We characterized a cDNA of WAS-3a encoding the major isoform of taTLPs from winter wheat cells and showed that WAS-3a transcripts were markedly increased by treatment with ABA and by treatment with elicitors (chitosan, beta-glucan and cell wall fractions of Fusarium oxysporum and Microdochium nivale) in wheat cells. To analyse the function of WAS-3a, a highly efficient expression system using wheat cells was established, and a large amount of recombinant WAS-3a protein (rWAS-3a) was obtained with near homogeneity. Antifungal assays using various fungi grown on agar plates revealed that rWAS-3a inhibits hyphal growth of pink snow mould, Microdochium nivale, at a low temperature. The results suggest that cold-induced taTLPs that accumulate in the apoplast contribute to snow mould resistance of winter wheat.

Journal Article↗
PubMed2003

Formation of recent martian gullies through melting of extensive water-rich snow deposits.

The observation of gullies on Mars indicates the presence of liquid water near the surface in recent times, which is difficult to reconcile with the current cold climate. Gullies have been proposed to form through surface runoff from subsurface aquifers or through melting of near-surface ice under warmer conditions. But these gullies are observed to occur preferentially in cold mid-latitudes, where the presence of liquid water is less likely, and on isolated surfaces where groundwater seepage would not be expected, making both potential explanations unsatisfactory. Here I show that gullies can form by the melting of water-rich snow that has been transported from the poles to mid-latitudes during periods of high obliquity within the past 10(5) to 10(6) years (refs 5, 6). Melting within this snow can generate sufficient water to erode gullies in about 5,000 years. My proposed model for gully formation is consistent with the age and location of the gullies, and it explains the occurrence of liquid water in the cold mid-latitudes as well as on isolated surfaces. Remnants of the snowpacks are still present on mid-latitude, pole-facing slopes, and the recent or current occurrence of liquid water within them provides a potential abode for life.

Journal Article↗
PubMed1998

Breeding structure of three snow pool Aedes mosquito species in northern Colorado.

RAPD-PCR polymorphisms were used to examine breeding structure in three species of snow pool Aedes mosquitoes across three river drainages in northern Colorado. Larvae were collected from four snow pools for Aedes cataphylla Dyar, seven pools for A. hexodontus Dyar and six pools for A. pullatus (Coquillet). Polymorphisms were scored at 47-48 RAPD loci in each species. To test for isolation by distance, FST/(1-FST) values between pairs of pools were plotted against geographical distances and subjected to a Mantel test with 1000 random permutations. FST values were independent of geographical distances in A. cataphylla and A. hexodontus but were somewhat correlated in A. pullatus suggesting isolation by distance in this species. A cluster analysis was performed on pair-wise FST values among pools including seven pools that were sampled in both 1994 and 1995. Bootstrap analysis indicated that pools clustered across drainages and generally independently of geographical proximity. However, there was consistent support for clustering of larvae collected from the same pool across years in A. cataphylla and in high altitude collections of A. pullatus. Mountains do not appear to act as major barriers to gene flow in any of these species. Instead, seasonal differences in adult emergence may serve as barriers to migration among A. pullatus and A. cataphylla populations. Larvae of A. hexodontus are distributed continuously in grassy pools along the banks of rivers and genetic drift probably occurs through random larval mortality when these pools are washed out during spring run-off.

Aedes↗
PubMed2002

Multiple ocular colobomas in the snow leopard (Uncia uncia).

Two singleton female snow leopard cubs are reported with bilateral central upper lid colobomas. In addition, one cub had a coloboma of the fundus in one eye extending from the lower optic disc region. Surgical treatment by wedge resection was successful in both cases. Details of ocular colobomas in other snow leopards reported in the literature are described and it is suggested that the exact etiology of the condition in this species may be discovered by further study of similar colobomas in the domestic cat.

Animals↗
PubMed2000

An experience of the Snow-Littler procedure.

This paper reviews the results of the Snow-Littler procedure performed in twelve hands with classical central longitudinal deficiency and in one hand with symbrachydactyly, cleft type. There were no instances of major flap necrosis although two flaps showed tip ischaemia. The width of the first web was, in the main, satisfactory but four webspace revisions were performed. Supplementary skin grafting at the time of surgery was necessary in complete and/or complex thumb index syndactylies and in the patient with symbrachydactyly. In eight cases, a transverse metacarpal ligament was reconstructed. In the five other cases, no clinical instability or radiological divergence of the index and ring fingers occurred, in spite of no transverse metacarpal ligament reconstruction. Three de-rotational osteotomies of transposed index fingers were performed in patients who had a transverse metacarpal ligament reconstruction. These results indicated significantly improved appearance and improved function following the Snow-Littler procedure.

Child↗
PubMed1997

Seasonal effects on ovarian responsiveness to exogenous gonadotrophins and successful artificial insemination in the snow leopard (Uncia uncia).

Ovaries of the seasonally-breeding snow leopard (Uncia uncia) were examined to determine whether they were responsive to exogenous gonadotrophins throughout the year. The potential of laparoscopic artificial insemination (AI) also was assessed for producing offspring. During the non-breeding, pre-breeding, breeding and post-breeding seasons, females (n = 20) were treated with a standardized, dual-hormone regimen given intramuscularly (600 I.U. of equine chorionic gonadotrophin followed 80-84 h later with 300 I.U. of human chorionic gonadotrophin (hCG)). Laparoscopy was performed 45-50 h after administration of hCG, and all ovarian structures were described. Females with fresh corpora lutea (CL) were inseminated, and anovulatory females were subjected to follicular aspiration to examine oocyte quality. Snow leopards responded to exogenous gonadotrophins throughout the year. Mean number of total ovarian structures (distinct follicles mature in appearance plus CL) did not differ (P > or = 0.05) with season, but the proportion of CL: total ovarian structures was greater (P < 0.01) for the breeding season compared with all other seasons. The proportion of females ovulating was greater (P < 0.05) during the breeding and post-breeding seasons than during the pre-breeding and non-breeding seasons respectively. No Grade-1 quality oocytes were recovered from follicles of anovulatory females. Serum concentrations of oestradiol-17 beta appeared elevated in all females, and neither oestradiol-17 beta concentrations nor progesterone concentrations differed (P > or = 0.05) among seasons. Of 15 females artificially inseminated, the only one that was inseminated in the non-breeding season became pregnant and delivered a single cub. This is the first successful pregnancy resulting from AI in this endangered species.

Animals↗
PubMed2003

Soot climate forcing via snow and ice albedos.

Plausible estimates for the effect of soot on snow and ice albedos (1.5% in the Arctic and 3% in Northern Hemisphere land areas) yield a climate forcing of +0.3 W/m(2) in the Northern Hemisphere. The "efficacy" of this forcing is approximately 2, i.e., for a given forcing it is twice as effective as CO(2) in altering global surface air temperature. This indirect soot forcing may have contributed to global warming of the past century, including the trend toward early springs in the Northern Hemisphere, thinning Arctic sea ice, and melting land ice and permafrost. If, as we suggest, melting ice and sea level rise define the level of dangerous anthropogenic interference with the climate system, then reducing soot emissions, thus restoring snow albedos to pristine high values, would have the double benefit of reducing global warming and raising the global temperature level at which dangerous anthropogenic interference occurs. However, soot contributions to climate change do not alter the conclusion that anthropogenic greenhouse gases have been the main cause of recent global warming and will be the predominant climate forcing in the future.

Journal Article↗
PubMedDate not supplied

Survival strategy of hiba (Thujopsis dolabrata var. hondae) and two broad-leaved trees in northern Japan in response to creep and glide pressures of snow.

We compared the tolerance of hiba (Thujopsis dolabrata var. hondae Makino), beech (Fagus crenata Blume) and oak (Quercus serrata Thunb.) to creep and glide pressures of snow. The top/root (T/R) ratio of hiba trees ranged between 7.1 and 41.4 compared with 3.6-10.9 and 1.0-12.4 for beech and oak, respectively. However, if prostrate stems bearing adventitious roots were included in the root component, the T/R ratio of hiba trees was comparable to the range observed for the co-occurring broad-leaved species (1.2 to 3.9). The adventitious roots originating from the trunks of hiba trees extended horizontally during the early growth stage. However, when stem diameter at ground level reached 6-7 cm, some large-diameter adventitious roots developed vertically to form, so-called, sustentacular roots. Because all of the dead hiba trees that we examined lacked sustentacular roots, we conclude that sustentacular roots are necessary to enable young hiba trees to withstand the pressures of snow movement. All of the large beech trees formed sustentacular roots and no dead beech trees were observed. Not all the oak trees formed sustentacular roots, which may explain why this species was found only on gentle slopes.

Journal Article↗