Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “winter”

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 307 records · Page 17Linked to original sources
PubMed2000

Iron-superoxide dismutase expression in transgenic alfalfa increases winter survival without a detectable increase in photosynthetic oxidative stress tolerance.

To determine whether overexpression of Fe-superoxide (SOD) dismutase would increase superoxide-scavenging capacity and thereby improve the winter survival of transgenic alfalfa (Medicago sativa L.) plants, two genotypes were transformed with the vector pEXSOD10, which contains a cDNA for Arabidopsis Fe-SOD with a chloroplast transit peptide and cauliflower mosaic virus 35S promoter. A novel Fe-SOD was detected by native PAGE in both greenhouse- and field-grown transgenic plants, but activity varied among independent transgenic plants. The increased Fe-SOD activity was associated with increased winter survival over 2 years in field trials, but not with oxidative stress tolerance as measured by resistance of leaves to methyl viologen, a superoxide generator. Total shoot dry matter production over 2 harvest years was not associated with Fe-SOD activity. There was no detectable difference in the pattern of primary freezing injury, as shown by vital staining, nor was there additional accumulation of carbohydrates in field-acclimated roots of the transgenic alfalfa plants. We did not detect any difference in growth of one transgenic plant with high Fe-SOD activity compared with a non-transgenic control. Therefore, the improvement in winter survival did not appear to be a consequence of improved oxidative stress tolerance associated with photosynthesis, nor was it a consequence of a change in primary freezing injury. We suggest that Fe-SOD overexpression reduced secondary injury symptoms and thereby enhanced recovery from stresses experienced during winter.

Adaptation, Physiological↗
PubMed1979

Germination-induced Changes in Chromosomal Proteins of Spring and Winter Wheat Embryos.

The template activity of chromatin from winter wheat embryos gradually increased during germination and was regulated with some nonhistone proteins different from the two major ones, molecular weight 39k and 59k polypeptides, previously reported.To clarify chromosomal proteins which are involved in regulation of template activity of chromatin, we studied the quantitative and qualitative changes in chromosomal proteins. Differences in acid-soluble and acid-insoluble proteins between chromatins from wheat germ and embryos germinated for various times were visualized by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis.Nonhistone proteins of 39k, 41k, and 50k molecular weights were specifically present in wheat germ and in 24- or 48-hour germinated wheat embryos, thereafter greatly reduced or finally disappeared. In contrast, nonhistone protein of 37k was absent in germ and in embryos germinated for 24 hours and appeared after 48 hours of germination. Thereafter it was present in abundant amounts in 96-hour germinated winter wheat embryos and in 72-hour germinated spring embryos, corresponding to 7 and 10% of total nonhistone proteins, respectively. Histone H1, especially H1d, was slightly reduced after 48-hour germination, as much as basic nonhistone proteins having electrophoretic mobilities between H1d and H2B. Further-more, similarity and diversity of chromosomal proteins between spring and winter wheat embryos are shown in this study. A subspecies of histone H1c of spring wheat had faster electrophoretic mobility than that of winter wheat.

Journal Article↗
PubMed1991

Carbohydrate Metabolism in Taproots of Medicago sativa L. during Winter Adaptation and Spring Regrowth.

Our objective was to identify amylases that may participate in starch degradation in alfalfa (Medicago sativa L.) taproots during winter hardening and subsequent spring regrowth. Taproots from field-grown plants were sampled at intervals throughout fall, winter, and early spring. In experiment 1, taproots were separated into bark and wood tissues. Concentrations of soluble sugars, starch, and buffer-soluble proteins and activities of endo- and exoamylase were determined. Starch concentrations declined in late fall, whereas concentrations of sucrose increased. Total amylolytic activity (primarily exoamylase) was not consistently associated with starch degradation but followed trends in soluble protein concentration of taproots. This was especially evident in spring when both declined as starch degradation increased and shoot growth resumed. Activity of endoamylase increased during periods of starch degradation, especially in bark tissues. In experiment 2, a low starch line had higher specific activity of taproot amylases. This line depleted its taproot starch by late winter, after which taproot sugar concentrations declined. As in experiment 1, total amylolytic activity declined in spring in both lines, whereas that of endoamylase increased in both lines even though little starch remained in taproots of the low starch line. Several isoforms of both amylases were distinguished using native polyacrylamide electrophoresis, with isoforms being similar in bark and wood tissues. The slowest migrating isoform of endoamylase was most prominent at each sampling. Activity of all endoamylase isoforms increased during winter adaptation and in spring when shoot growth resumed. Endoamylase activity consistently increased at times of starch utilization in alfalfa taproots (hardening, spring regrowth, after defoliation), indicating that it may serve an important role in starch degradation.

Journal Article↗
PubMed1992

A cold environment is a prerequisite for formation of "plastid initials" in winter buds of poplar.

The "plastid initial," the presumed precursor of eoplasts and proplastids, is present in the cells of the apical meristem of winter buds of poplar (Populus euramericana). The formation of the plastid initial in the cells of winter buds is initiated soon after the breaking of the innate or resting stage of dormancy, even in winter under nongrowing conditions in mid-January or early February. From this stage to March, the conglomeration of the plastid initial and the formation of prolamellar bodies is evident. In contrast to the poplar samples kept outdoors, the cells of the apical meristem of the indoor winter buds did not show any indication of the formation of the plastid initial and the buds of the latter sample did not flush even at the end of May. These results suggest that the sequence of reactions involved in the onset of regrowth may be closely related to the formation of the plastid initial.

Journal Article↗
PubMed2006

JrSUT1, a putative xylem sucrose transporter, could mediate sucrose influx into xylem parenchyma cells and be up-regulated by freeze-thaw cycles over the autumn-winter period in walnut tree (Juglans regia L.).

Sucrose has been reported to play multiple roles in the winter biology of temperate woody species. However, no report on the molecular basis of sucrose transport in xylem tissue has yet been made. In the walnut tree, it is demonstrated that during the autumn-winter period, active absorption of sucrose from xylem vessels to parenchyma cells (sucrose influx) is much higher when samplings were taken shortly after a period of freezing temperatures. Here, the question of whether this increased sucrose influx mirrors a regulation of sucrose transporters in xylem tissue was tested. A putative sucrose transporter cDNA (JrSUT1: Juglans regia sucrose transporter 1) was isolated. Over the autumn-winter period, JrSUT1 transcripts and respective proteins were present in xylem parenchyma cells and highly detected when samplings were performed shortly after a freeze-thaw cycle. This up-regulation of JrSUT1 level was confirmed in controlled conditions and was not obtained in bark. Immunolocalization studies showed that JrSUT1 and plasma membrane H+ -ATPase (JrAHA) were colocalized to vessel-associated cells (VACs), which control solute exchanges between parenchyma cells and xylem vessels. We propose that JrSUT1 could be involved in the retrieval of sucrose from xylem vessel. All these data are discussed with respect to the winter biology of the walnut tree.

Biological Transport, Active↗
PubMed2006

Winter acclimation of PsbS and related proteins in the evergreen Arctostaphylos uva-ursi as influenced by altitude and light environment.

The evergreen groundcover bearberry (Arctostaphylos uva-ursi [L.] Sprengel) was characterized over two successive years (2002-2004) from both sun-exposed and shaded sites at a montane ponderosa pine and subalpine forest community of 1900- and 2800-m-high altitudes, respectively. During summer, photosynthetic capacities and pre-dawn photosystem II (PSII) efficiency were similarly high in all four populations, and in winter, only the sun-exposed and shaded populations at 2800 m exhibited complete down-regulation of photosynthetic oxygen evolution capacity and consistent sustained down-regulation of PSII efficiency. This photosynthetic down-regulation at high altitude involved a substantial decrease in PSII components [pheophytin, D1 protein, oxygen evolving complex ([OEC)], a strong up-regulation of several anti-early-light-inducible protein (Elip)- and anti-high-light-inducible protein (Hlip)-reactive bands and a warm-sustained retention of zeaxanthin and antheraxanthin (Z + A). PsbS, the protein modulating the rapid engagement and disengagement of Z +A in energy dissipation, exhibited its most pronounced winter increases in the shade at 1900 m, and thus apparently assumes a greater role in providing rapidly reversible zeaxanthin-dependent photoprotection during winter when light becomes excessive in the shaded population, which remains photosynthetically active. It is attractive to hypothesize that PsbS relatives (Elips/Hlips) may be involved in sustained zeaxanthin-dependent photoprotection under the more extreme winter conditions at 2800 m.

Adaptation, Physiological↗
PubMed2004

Phylogenetic relationships among genotypes of worldwide collection of spring and winter ryes (Secale cereale L.) determined by RAPD-PCR markers.

Genetic similarities among 20 spring and 22 winter accessions of agronomically different ryes from fourteen countries were estimated by employing random amplified polymorphic DNA (RAPD) techniques. Cluster analysis of genetic distance data showed that 42 genotypes were readily classifiable into two main groups: spring and winter groups. Within the spring group, cultivars fell into a North European and an American-Chinese group. Cultivars of winter rye fell into four groups: Northern European, Russian, American and Chinese lines. A UPGMA-dendrogram based on genetic distances of cultivars of rye within the winter and spring groups showed that the clusters corresponded well to their geographical locations. The results indicated that isolation has played an important role in the evolution of rye, and that temporal isolation has influenced the genetic diversity of rye more than geographical isolation. In this experiment, RAPD proved to be a rapid, reliable and practicable method of revealing polymorphisms in rye populations.

Ecosystem↗
PubMed1979

The Spitzbergen reindeer--a winter-dormant ungulate?

Seasonal changes in serum levels of growth hormone, cortisol and thyroxine in calves and adult Spitzbergen reindeer (Rangifer tarandus platyrynchus) were measured and compared to those previously found in Norwegian reindeer (R.t. tarandus). Cortisol did not differ significantly between summer and winter, or between the subspecies. Growth hormone and thyroxine exhibited highly significant seasonal changes and subspecific differences: winter levels of growth hormone were much higher than summer levels in the Spitzbergen reindeer, while Norwegian reindeer differed very little from season to season. Both Spitzbergen and Norwegian reindeer had markedly reduced thyroxine levels during winter, but the values from the former were much lower than those from the latter. In summer, however, the levels were equal. The high levels of growth hormone and low levels of thyroxine in the Spitzbergen reindeer during winter are indicative of high lipolytic activity and a reduced metabolic rate, respectively.

Animals↗
PubMed2006

Identification and specific detection of a novel pseudomonadaceae cluster associated with soils from winter wheat plots of a long-term agricultural field experiment.

The genus Pseudomonas (sensu stricto) represents a group of microorganisms directly involved in functions conferring plant health. We performed a study in the DOK long-term agricultural field experiment on the basis of previously published Pseudomonas-selective PCR primers in order to investigate the community structure of the microbial groups defined by the target range of these primers. Three different agricultural management systems, i.e., conventional, biodynamic, and bio-organic, along with mineral and unfertilized controls were investigated, with each system planted with either winter wheat or a grass-clover ley. Amplified small-subunit rRNA gene fragments were analyzed using the genetic profiling techniques restriction fragment length polymorphism (RFLP) and denaturing gradient gel electrophoresis (DGGE), revealing distinct differences between soils planted with winter wheat and grass clover but only minor differences between the management systems. Phylogenetic analyses of 59 clone sequences retrieved from bio-organic and unfertilized systems identified sequences related to Pseudomonas fluorescens and a novel cluster termed Cellvibrio-related Pseudomonadaceae (CRP). The CRP clones were exclusively isolated from winter wheat soil samples and were responsible for the crop-specific differences observed in RFLP and DGGE profiles. New primers were designed for the amplification of CRP targets directly from soil DNA, yielding strong signals exclusively for winter wheat soils. We concluded that crop-associated CRP exist in agricultural soils and that genetic profiling followed by specific probe design represents a valuable approach for identification as well as sensitive and rapid monitoring of novel microbial groups in the environment.

Agriculture↗
PubMedDate not supplied

Risk factors for winter outbreak of acute diarrhoea in France: case-control study.

OBJECTIVES: To assess the potential role of consumption of shellfish (particularly raw oysters) and tap water in the winter epidemic of acute diarrhoea in France. DESIGN: Population based, case-control study during the 1995-6 winter epidemic of acute diarrhoea in France. SETTING: A national network comprising 1% of general practitioners in France. SUBJECTS: 568 pairs of cases and controls consulting in general practice and interviewed by 209 doctors from 26 December 1995 to 31 January 1996. Cases and controls were matched for age, doctor, and time of consultation. MAIN OUTCOME MEASURES: Adjusted relative risk of diarrhoea estimated from conditional logistic regression. RESULTS: The risk of acute diarrhoea was not increased in people who had recently eaten raw oysters (odds ratio 1.1; 95% confidence interval 0.9% to 1.4%) or other shellfish such as clams, cockles, and mussels, or in those people who usually consumed tap water rather than bottled water (0.8; 0.6% to 1.1%). The risk was, however, increased in people who had had recent contact wit ha person with diarrhoea either within the household (adjusted odds ratio 5.0) or in the workplace (3.1), and in people who lived with a child < or = 2 years of age (1.6). Recent treatment with either oral penicillin or cephalosporin was also independently associated with acute diarrhoea in winter. CONCLUSIONS: The winter epidemic of acute diarrhoea in France is probably not caused by consumption of either shellfish or tap water. A viral aetiology, however, is suggested by the speed with which the acute diarrhoea is transmitted.

Acute Disease↗
PubMed1992

Sudden infant death syndrome: does winter affect poor and rich babies equally?

STUDY OBJECTIVE: The aim was to investigate whether the winter increase in risk of sudden infant death was similar across social classes. DESIGN: This was an unmatched case-control study using routine data. SETTING: Cases and controls were selected from files holding routine birth and death certificate data for England and Wales for 1986. SUBJECTS: Cases were deaths in the first year of life occurring in the summer or the winter of 1986 with mention of sudden infant death or SIDS in the death certificate. Controls were a 1% random sample of all children born in the same year. Only children whose parents were married or living together at the time of birth registration were included. MAIN RESULTS: Data on age and season of death for cases, and on date of birth, social class of father, and birth weight were abstracted from the file. Season of birth and birth weight were treated as confounding variables. The increase in risk of SIDS in winter was calculated for each age group and social class. The winter increase in SIDS was more marked among the higher social classes for all ages, but not to a statistically significant degree: the p values for heterogeneity were 0.26 for age 0-3 months, 0.42 for 4-7 months, and 0.41 for 8-12 months. CONCLUSIONS: There is no direct association between seasonal variation in sudden infant death and social class.

Birth Weight↗
PubMed1999

Deprivation and excess winter mortality.

OBJECTIVE: To investigate the effect of material deprivation on the winter rise in mortality and temperature dependent variations in mortality. DESIGN: Ecological comparison of seasonal mortality at electoral ward level. Main outcome measures were ratios of winter to rest of the year mortality rates (seasonality ratios) and monthly deaths as the outcome variable in a model with monthly average temperature and Townsend score as main predictors. SETTING: Croydon, London, United Kingdom. SUBJECTS: All deaths of Croydon residents for the period 1990-1995. MAIN RESULTS: There was a clear relation between overall mortality and deprivation. There was no evidence of a relation between age and sex standardised seasonality ratios and Townsend scores for all deaths (Kendall's tau = -0.066, p = 0.63) or cardiovascular deaths or respiratory deaths. There was no evidence of an interaction between Townsend score and temperature in the model of ward mortality rates (p = 0.73). These findings were not affected by exclusion of deaths of nursing and residential home residents. CONCLUSION: This study provides no evidence of an effect of deprivation on excess winter mortality or temperature dependent variations in mortality. The findings question simple assumptions about the relation between deprivation and excess winter mortality and highlight the need for further study to guide interventions.

Cold Temperature↗
PubMed2006

Maintenance and accumulation of trimethylamine oxide by winter skate (Leucoraja ocellata): reliance on low whole animal losses rather than synthesis.

Trimethylamine oxide (TMAO) is typically accumulated as an organic osmolyte in marine elasmobranchs to levels second only to urea (which can reach >400 mM); however, little is known about the whole animal regulation of TMAO in elasmobranchs. In the present study on the winter skate (Leucoraja ocellata), we determine whether this species can maintain levels of TMAO in the absence of feeding, and if so, is this due to endogenous synthesis or low whole animal losses. Winter skates maintain plasma TMAO levels for up to 45 days without feeding. The liver displays methimazole oxidation, which is consistent with the presence of flavin-containing monooxygenase (E.C. 1.14.13.8) activity, the class of enzymes responsible for the physiological oxygenation of trimethylamine (TMA) to TMAO in mammals. However, no evidence for TMA oxygenation by winter skates was found using in vivo or in vitro techniques, indicating no significant capacity for endogenous TMAO synthesis. Fed skates displayed low, but measurable ( approximately 4-13 micromol.kg(-1).h(-1)), efflux of TMAO (plus TMA), whereas fasted skates did not. Using the loss of injected [14C]TMAO, it was determined that whole animal TMAO losses are likely <1% of whole body TMAO per day. These results demonstrate that winter skates utilize low whole animal TMAO losses, rather than endogenous synthesis, to maintain TMAO levels when not feeding.

Animals↗
PubMed2006

Winter birth in association with a risk of brain tumor among a Finnish patient population.

The aim of this study was to analyze whether winter birth is related to risk of brain tumor in a clinical sample of patients from northern Finland. The study group comprised 101 patients suffering from a primary brain tumor. When comparing births in winter to births in other seasons, a 1.39-fold (95% CI 1.01-1.77) excess of winter births among patients was observed compared to respective births in the general population (p = 0.026). Especially patients with pituitary adenomas exhibited a 2.5-fold (95% CI 1.5-4.4) excess of winter births. The authors conclude that the season-of-birth effect in brain tumor patients should not be neglected when the actual and important tumorigenesis is investigated.

Adult↗
PubMed1998

Greater improvement in summer than with light treatment in winter in patients with seasonal affective disorder.

OBJECTIVE: The authors sought to compare the degree of mood improvement after light treatment with mood improvement in the subsequent summer in patients with seasonal affective disorder. METHOD: By using the Seasonal Affective Disorder Version of the Hamilton Depression Rating Scale, the authors rated 15 patients with seasonal affective disorder on three occasions: during winter when the patients were depressed, during winter following 2 weeks of light therapy, and during the following summer. They compared the three conditions by using Friedman's analysis of variance and the Wilcoxon signed ranks test. RESULTS: The patients' scores on the depression scale were significantly higher after 2 weeks of light therapy in winter than during the following summer. CONCLUSIONS: Light treatment for 2 weeks in winter is only partially effective when compared to summer. Further studies will be necessary to assess if summer's light or other factors are the main contributors to this difference.

Adult↗
PubMed1993

Winter adaptations of male deer mice (Peromyscus maniculatus) and prairie voles (Microtus ochrogaster) that vary in reproductive responsiveness to photoperiod.

Individuals of many nontropical rodent species restrict breeding to the spring and summer. Seasonal reproductive quiescence putatively reflects the energetic incompatibility of breeding and thermoregulatory activities. However, so-called "out-of-season" breeding occurs in virtually all rodent populations examined, suggesting that the incompatibility can be resolved. Both reproductive inhibition and development of energy-saving adaptations are mediated by environmental photoperiod, but some individuals do not inhibit reproduction in short days. In order to assess the costs and benefits of winter breeding, the present study examined the extent to which male prairie voles (Microtus ochrogaster) and deer mice (Peromyscus maniculatus) that maintained summer reproductive function in winter-simulated daylengths also maintained summer thermoregulatory adaptations. Circadian locomotor activity patterns, basal metabolic rate, capacity for nonshivering thermogenesis, nest building, body mass, and daily food consumption were compared among short-day (LD 8:16) regressed males, short-day (LD 8:16) nonregressed males, and long-day (LD 16:8) males. Short-day nonregressed deer mice resembled long-day conspecifics in terms of body mass and nest-building activities; however, the locomotor activity pattern of short-day nonregressed deer mice was similar to that of their short-day regressed conspecifics. Short-day nonregressed prairie voles had body masses similar to those of long-day conspecifics. Regardless of their reproductive response to photoperiod, short-day prairie voles reduced their daily food consumption and wheel-running activity, compared to long-day voles. These results suggest that winter breeding has energetic costs, most likely resulting from maintaining a "summer-like" body mass relative to that of reproductively regressed animals. These costs may be ameliorated to some extent by the reduction in locomotor activity and nest-building behavior emitted by short-day animals, regardless of reproductive response to short days. Thus, the occurrence of winter breeding may be the result of sufficient numbers of reproductively photoperiod-nonresponsive morphs in the population and sufficiently mild ambient conditions to permit survival of these larger animals.

Adaptation, Physiological↗
PubMed2005

FRIGIDA-ESSENTIAL 1 interacts genetically with FRIGIDA and FRIGIDA-LIKE 1 to promote the winter-annual habit of Arabidopsis thaliana.

Studies of natural variation have revealed that the winter-annual habit of many accessions of Arabidopsis is conferred by two genes, FRIGIDA (FRI) and FLOWERING LOCUS C (FLC), whose activities impose a vernalization requirement. To better understand the mechanism underlying the winter-annual habit, a genetic screen was performed to identify mutants that suppress the late-flowering behavior of a non-vernalized winter-annual strain. We have identified a locus, FRIGIDA-ESSENTIAL 1 (FES1), which, like FRI, is specifically required for the upregulation of FLC expression. FES1 is predicted to encode a protein with a CCCH zinc finger, but the predicted sequence does not otherwise share significant similarity with other known proteins. fes1 is a complete suppressor of FRI-mediated delayed flowering, but has little effect on the late-flowering phenotype of autonomous-pathway mutants. Thus, FES1 activity is required for the FRI-mediated winter-annual habit, but not for the similar phenotype resulting from autonomous-pathway mutations. Epistasis analysis between FES1, FRI and another specific suppressor of FRI-containing lines, FRIGIDA-LIKE 1 (FRL1), indicates that these genes do not function in a linear pathway, but instead act cooperatively to promote the expression of FLC.

Amino Acid Sequence↗
PubMed1995

The effect of temperature on spontaneous action potential discharge of the isolated sinus venosus from winter and summer plaice (Pleuronectes platessa)

The spontaneous cardiac pacemaker activity and conformation were recorded in vitro, using intracellular recording methods, from heart tissue of summer- and winter-caught plaice. The effects of changing temperature on the pacemaker rate, duration of action potential and diastolic depolarization were investigated by altering the temperature of the superfusing medium. The resting intrinsic rate of discharge was significantly greater in pacemaker cells from winter plaice (P=0.05), but there was no significant difference between winter and summer fish in the apparent Arrhenius activation energies for this process. However, there was a significant difference in the estimated intercept, indicating a thermal shift in the processes underlying the spontaneous pacemaker rhythm. There was no significant difference in the diastolic depolarization duration recorded from winter and summer fish over the temperature range 4&shy;22 &deg;C. The major effect of previous environmental temperature was on the duration of the action potential (P<0.02), indicating that the observed changes in pacemaker discharge rate were not influenced by the processes that determine the duration of the pacemaker diastolic depolarisation but were modulated by the channel events that give rise to the action potential.

Journal Article↗