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At least 1,153 records · Page 64Linked to original sources
PubMed1993

Sequence evolution in and around the mitochondrial control region in birds.

By cloning and sequencing 3.4 kilobases of snow goose mtDNA we found that the ND5 gene is followed by the genes for cytochrome b, tRNA(Thr), tRNA(Pro), ND6, tRNA(Glu), the control region, tRNA(Phe), and srRNA. This order is identical to that of chicken, quail, and duck mtDNA but differs from that of mammals and a frog (Xenopus). The mean extent of difference due to base substitution between goose and chicken is generally closer to the same comparison between rat and mouse but less than that between human and cow. For one of the nine regions compared (tRNA(Glu)), the bird differences appear to be anomalous, possibly implicating altered functional constraints. Within the control region, several short sequences common to mammals are also conserved in the birds. Comparison of the goose control region with that of quail and chicken suggests that a sequence element with similarity to CSB-1 duplicated once prior to the divergence of goose and chicken and again on the lineage leading to chicken. Between goose (or duck) and chicken there are four times more transversions at the third positions of fourfold-degenerate codons in mitochondrial than in nuclear genes.

Amino Acid Sequence↗
PubMed1978

Geroderma osteodysplastica. A report of two affected families.

This paper describes two families in which four boys and two girls were affected with geroderma osteodysplastica. The major features of this syndrome include a droopy, jowly, prematurely aged appearance that has been likened by previous authors to the dwarfs in Walt Disney's 'Snow White.' Also, their skin lacks normal elastic recoil. The bones are osteoporotic and susceptible to fractures, particularly the vertebrae, which show compression with anterior wedging and biconcavity. The findings in the present families are compared with those in the originally reported family. There was a high degree of consanguinity between the parents in both of the present families and the previous hypothesis of X-linked inheritance is questioned.

Bone Diseases, Developmental↗
PubMed1986

Behavioural temperature regulation during a motor-toboggan traverse in Antarctica.

Ten men, members of the International Biomedical Expedition to the Antarctic (IBEA), regularly recorded their thermal comfort, clothing, and activity for 60 days while travelling by motor toboggan and living in tents on the Antarctic plateau. Air temperature averaged -14 degrees C (range +2 degrees to -29 degrees C) and wind speed 11 m s-1 (range 0 to 22 m s-1); on half the days there was wind-blown ("drift") snow. Almost 2,000 sets of observations, evenly distributed throughout the 12 h sampling period 0700 h to 1900 h, were made. Daily (24 h) energy expenditure averaged 14.6 MJ on travelling days, 12.7 MJ on days when men worked in camp, and 13.3 MJ for the whole traverse. Men were outdoors for 7.6 h of the 12 h sampling period on travel days and for 3.6 h on camp days. Bulky down-filled clothing, typical of that used by present-day polar expeditions, adequately protected the trunk from cold at the cost of overheating during exercise. Face, hands, and feet were less well protected, and they experienced cold-induced numbness and pain in 33%, 19%, and 12%, respectively, of the observations made in the coldest weather. Because men could not conveniently reduce clothing insulation to the extent required, sweating and discomfort from warmth increased with energy expenditure and were present in 60% of the observations made during heavy work. The results suggest that there is a need for improvements in clothing design which will permit a more complete adjustment to changes in activity. The residual cold stress might possibly have been enough to induce cold acclimatization, although the accompanying heat stress was probably insufficient to induce acclimatization to heat.

Acclimatization↗
PubMed1987

The cryptoendolithic microbial environment in the Ross Desert of Antarctica: satellite-transmitted continuous nanoclimate data, 1984 to 1986.

A satellite mediated station for monitoring nanoclimate (climate in the millimeter range) data, suitable for use in polar regions is described. The station, located in the Ross desert of Antarctica, has been in operation for more than 3 years, measuring rock temperatures, air temperature, light, snow, wind, and moisture. The data indicate that biological activity in the cryptoendolithic microbial ecosystem is limited to the period from mid November to mid February. The total number of hours of biological activity, based on assumptions of the minimum light, temperature and moisture requirements of the community, is less than 1000 h/year. The time above 0 degrees C, representing more nearly optimal conditions, is between 50 and 550 h/year, depending on the orientation of the surface.

Antarctic Regions↗
PubMed1979

A gel-sandwich technique for the qualitative and quantitative determination of dehydrogenases in the enzyme histochemistry. I. Development of the new methods on the example of LDH (E.C. 1.1.1.27).

A gel-sandwich technique for the histochemical demonstration of dehydrogenase is introduced with LDH set up as an example. Especially suitable, of the gels examined, for this technique is 1.5% W/V agar-agar low gel strength. In it several reaction ingredients for the histochemical reaction are dissolved. Considering LDH the following gel composition showed good results: 1.5% W/V agar-agar low gel strength, 5 mM TNBT in 150 microliter DMF, 120 mM L-lactate, 3--5 mM NAD+, 10 mM amytal, 22,4--32 X 10(-5) M Meldola Blue, 160 mM soldium phosphate buffer pH 7.6 (total solution of 1 ml). After the solidification of the gel, gel-bars were frozen with CO2-snow. The 40--80 micrometer thick gel slices were gained in the cryostat. Of the three different arrangement possibilities of the gel slices and the tissue-sections a sandwich arrangement (cover-gel slice--tissue section--ground-gel slice) produced the best results. The enzyme reaction is started by thawing of the gel slices (together with the tissue sections) and by putting them between the hotplate and the evaporator-head-piece, especially developed for this technique. The gel slices also remain in combination with the tissue sections after the reaction. The influence of the gel in combination with the electron carrier Meldola Blue on the spontaneous reduction rates of ditetrazolium salts in day light, were examined as well as the diffusion rates of TNBT and NADH out of gel slices and the influence of DMF and DMSO on the LDH activity. This technique prevents both, the loss of enzymes and the loss of reduction equivalents. There are given presuppositions for qualitative and quantitative histochemical investigations as well. The advantages of the new gel technique are discussed.

Adrenal Glands↗
PubMed1995

A year-round study on functional relationships of airborne fungi with meteorological factors.

Air sampling was conducted in Waterloo, Canada throughout 1992. Functional relationships between aeromycota and meteorological factors were analysed. The meteorological factors were, in descending order of importance: mean temperature, minimum temperature, maximum temperature, mean wind speed, relative humidity (RH), rain, maximum wind speed and snow. The most important airborne fungal propagules in descending order were total fungal spores, unidentified Ascomycetes, Cladosporium, Coprinus, unidentified Basidiomycetes, Alternaria and unidentified fungi. Most airborne fungal taxa and highly significant relationship with temperature, but Aspergillus/Penicillium, hyphal fragments were positively associated with wind speed. In comparison with other airborne fungal taxa, Leptosphaeria and unidentified Ascomycetes were more closely correlated with rain and RH during the growing season.

Air Microbiology↗
PubMed1995

Characterization of SRSVs using RT-PCR and a new antigen ELISA.

Stool samples from 451 patients involved in volunteer studies, 26 outbreaks and approximately 175 sporadic cases of acute gastroenteritis from different geographical locations in the world were tested for Norwalk virus (NV) using a newly developed antigen ELISA and RT-PCR. NV was detected in most outbreaks previously characterized as being of NV origin. Overall, a low number of positives for NV was obtained using either RT-PCR with primers that amplified a unique region of the genome, or an ELISA with hyperimmune antisera made to the baculovirus-expressed recombinant NV capsid. However, a significant number of positives was obtained when these samples were tested by RT-PCR using primers that amplified the more highly conserved regions of the genome. Sequence analysis of the amplified viral cDNAs indicated that small round structured viruses (SRSVs) with a wide range of variable genomic sequences (44-87% nucleotide and 31-99% amino acid similarity to the 8Flla NV genome sequence) were responsible for these outbreaks. Several recent outbreaks from the US, Japan and the UK were related to the Snow Mountain Agent (SMA) by sequence analyses. Continued accumulation of sequence information will facilitate the design of new primers for virus detection and increase our understanding of the relationships and epidemiology of these viruses from different sources.

Amino Acid Sequence↗
PubMed2006

Highly conserved D-loop-like nuclear mitochondrial sequences (Numts) in tiger (Panthera tigris).

Using oligonucleotide primers designed to match hypervariable segments I (HVS-1) of Panthera tigris mitochondrial DNA (mtDNA), we amplified two different PCR products (500 bp and 287 bp) in the tiger (Panthera tigris), but got only one PCR product (287 bp) in the leopard (Panthera pardus). Sequence analyses indicated that the sequence of 287 bp was a D-loop-like nuclear mitochondrial sequence (Numts), indicating a nuclear transfer that occurred approximately 4.8-17 million years ago in the tiger and 4.6-16 million years ago in the leopard. Although the mtDNA D-loop sequence has a rapid rate of evolution, the 287-bp Numts are highly conserved; they are nearly identical in tiger subspecies and only 1.742% different between tiger and leopard. Thus, such sequences represent molecular 'fossils' that can shed light on evolution of the mitochondrial genome and may be the most appropriate outgroup for phylogenetic analysis. This is also proved by comparing the phylogenetic trees reconstructed using the D-loop sequence of snow leopard and the 287-bp Numts as outgroup.

Animals↗
PubMed2001

Photodegradation of halobenzenes in water ice.

Results from the photolysis of o, p-dichlorobenzene, bromobenzene, and p-dibromobenzene in water ice are reported. All phototransformations appeared to be based on dehalogenation, coupling, and rearrangement reactions in ice cavities. No photosolvolysis products, i.e. products from intermolecular reactions between organic and water molecules, were found. Many of the products were very toxic substances of a high environmental risk, such as PCBs. The results support our model, in which secondary, very toxic, pollutants can be formed in ice, snow, and atmospheric ice particles from primary pollutants through the action of solar irradiation. The photoproducts may be released to the environment by ice melting and evaporation.

Benzene Derivatives↗
PubMed1994

Embolism detected by transoesophageal echocardiography during hip arthroplasty.

This case report demonstrates embolization of echogenic material detected by transoesophageal echocardiography during a cemented total hip arthroplasty in a 76-yr-old woman without patent foramen ovale. During the placement of the acetabular and femoral components, and during relocation of the hip joint, a "snow flurry" appearing in the right atrium was followed by several highly echogenic and mobile emboli of various sizes, some of them with a vermiform shape 1 to 5 cm long. At skin closure, echogenic material was seen in the right branch of the pulmonary artery adherent to the vascular wall of the bifurcation of the main pulmonary artery. No changes were observed in any haemodynamic variable monitored (heart rate, systemic and right atrial pressures). Also, no desaturation was detected by pulse oximetry and blood gases at the time of embolism and there was no decrease in PETCO2. This case report is in line with other studies which failed to show a haemodynamic impact of TEE detected emboli during THA.

Aged↗
PubMed1998

Molecular adaptations in psychrophilic bacteria: potential for biotechnological applications.

Bacteria which live in cold conditions are known as psychrophiles. Since so much of our planet is generally cold, i.e. below 5 degrees C, it is not surprising that they are very common amongst a wide variety of habitats. To enable them to survive and grow in cold environments, psychrophilic bacteria have evolved a complex range of adaptations to all of their cellular components, including their membranes, energy-generating systems, protein synthesis machinery, biodegradative enzymes and the components responsible for nutrient uptake. Whilst such a systems approach to the topic has its advantages, all of the changes can be described in terms of adaptive alterations in the proteins and lipids of the bacterial cell. The present review adopts the latter approach and, following a brief consideration of the definition of psychrophiles and description of their habitats, focuses on those adaptive changes in proteins and lipids, especially those which are either currently being explored for their biotechnological potential or might be so in the future. Such applications for proteins range from the use of cold-active enzymes in the detergent and food industries, in specific biotransformations and environmental bioremediations, to specialised uses in contact lens cleaning fluids and reducing the lactose content of milk; ice-nucleating proteins have potential uses in the manufacture of ice cream or artificial snow; for lipids, the uses include dietary supplements in the form of polyunsaturated fatty acids from some Antarctic marine psychrophiles.

Bacteria↗
PubMed1999

Male-driven evolution among Eoaves? A test of the replicative division hypothesis in a heterogametic female (ZW) system.

Because avian females are heterogametic, the reverse of mammals, avian sex chromosomes undergo significantly different patterns and numbers of DNA replications than do those in mammals. This makes the W (female-specific) and the Z chromosomes an excellent model system for the study of the replicative division hypothesis, which purports that DNA substitution rate is determined by the number of germline replications. The sex-specific chromosome in birds (the W) is predicted to change at the slowest rate of all avian chromosomes because it undergoes the fewest rounds of replication per unit of evolutionary time. Using published data on gametogenesis from a variety of sources, we estimated the ratio of male-to-female germline replications (c) in galliforms and anseriforms to be approximately 4.4. The value of c should predict the value of the ratio of male-to-female mutation rates (alpha(m)) if the replicative division hypothesis is true. Homologous DNA sequences including an intron and parts of two exons of the CHD gene were obtained from the W and the Z chromosomes in ostrich, sage grouse, canvasback duck, tundra swan, and snow goose. The exons show significantly different nucleotide composition from the introns, and the W-linked exons show evidence of relaxed constraint. The Z-linked intron is diverging approximately 3.1 times faster than the W-linked intron. From this, alpha(m) was calculated to be approximately 4.1, with a confidence interval of 3.1 to 5.1. The data support the idea that the number of replicative divisions is a major determinant of substitution rate in the Eoavian genome.

Animals↗
PubMed1996

[Mining in the Harz Mountains in the times thereafter and its effects on the environment].

Not only during the industrial age have mining and metallurgy strongly influenced environmental developments. Since the beginning of mining activities and smelting ores, parts of the processed minerals, especially various heavy metals, have been lost during various technical operations and been distributed by water and wind over large areas. A good example for the Middle Ages and thereafter was the silver, lead, and copper mining district of the Harz Mountains in northeastern Germany. Environmental problems caused by the activity in this mining center have been known since the Renaissance. The rivers transported sand-like lead minerals over long distances, which were distributed over large areas by floods, especially in spring when the snow melted. The lead got into the food of various farm animals and poisoned them, as we know from the complaints of inhabitants of the area to the authorities particularly during the 17th-19th centuries. These environmental problems have been the subject of scientific studies as early as the first half of the 19th century.

Animals↗
PubMed2006

Self-estimation of ability among skiers and snowboarders in alpine skiing resorts.

Skiing ability is thought to be an important risk factor for injuries, but the best method to classify skiing ability is not known. The objective of this study was to validate five different questions designed to self-report skiing ability for ski injury surveillance. To this end 512 alpine skiers, Telemark skiers, snowboarders and skiboarders were asked to selfestimate their skiing ability using five different questions based on skiing skill, piste difficulty, turning technique, skiing experience and falling frequency, each with four categories. The participants then made a test run to test their skiing ability. Observed and self-reported skiing ability were compared using kappa statistics. The correlation between observed and self-reported skiing ability was low to fair, with kappa values of 0.34 for skiing skill), 0.33 for piste difficulty, 0.38 for turning technique, 0.26 for experience and 0.16 for falling frequency. However, the sensitivity and specificity for each of the questionnaires in discriminating between individuals in the poorest skiing ability category on the test and the rest of the group was relatively good (skiing skill: sensitivity 75%, specificity 91%; piste difficulty 68, 96%; turning technique 75, 91%; experience 75, 90%; falling frequency 61, 97%). The results show that the capacity to self-assess skiing ability is limited, but estimation based upon turning technique or skiing skill seem to be best methods for epidemiological studies on injuries in snow sports.

Adolescent↗
PubMed1999

Contribution of weather to the seasonality of distal forearm fractures: a population-based study in Rochester, Minnesota.

Distal forearm fractures due to falls were more frequent in the winter (p < 0.0001) among Rochester men and women 35 years of age or older in 1952-89. The winter excess was partially explained by a greater relative risk of distal forearm fractures on days with freezing rain (1.65; 95% CI 1.28-2.13) or snow (1.42; 95% CI 1.17-1.74) among women under 65 years of age and on days with freezing rain (1.63; 95% CI 1.23-2.17) among older women. The greater seasonality of forearm compared with hip fractures is explained by the fact that more of them occur out-of-doors. However, residual effects of season after adjusting for daily weather conditions suggest that other factors may play a role.

Accidental Falls↗
PubMed1999

Microbial metabolism of methanesulfonic acid

Methanesulfonic acid is a very stable strong acid and a key intermediate in the biogeochemical cycling of sulfur. It is formed in megatonne quantities in the atmosphere from the chemical oxidation of atmospheric dimethyl sulfide (most of which is of biogenic origin) and deposited on the Earth in rain and snow, and by dry deposition. Methanesulfonate is used by diverse aerobic bacteria as a source of sulfur for growth, but is not known to be used by anaerobes either as a sulfur source, a fermentation substrate, an electron acceptor, or as a methanogenic substrate. Some specialized methylotrophs (including Methylosulfonomonas, Marinosulfonomonas, and strains of paragraph signHyphomicrobium and Methylobacterium) can use it as a carbon and energy substrate to support growth. Methanesulfonate oxidation is initiated by cleavage catalysed by methanesulfonate monooxygenase, the properties and molecular biology of which are discussed.

Journal Article↗
PubMed2000

Analysis of low molecular weight organic acids in water with capillary zone electrophoresis employing indirect photometric detection.

A capillary zone electrophoretic method for the analysis of low molecular weight carboxylic acids in water was developed. The application uses the chromophore trimellitic acid that allows for indirect photometric detection at 254 nm. Selectivity control by the addition of Ca2+ to the carrier electrolyte made possible a baseline resolved separation of 14 carboxylic acids. Good linearity and repeatability were obtained for both electrokinetic and hydrostatic injection modes. The usefulness of the method is demonstrated by the analysis of a snow sample.

Journal Article↗
PubMed1998

Aerial Transport of Keratinaceous Substrate and Distribution of the Fungus Geomyces pannorum in Antarctic Soils

> Abstract Aerobiological sampling was conducted year-round at three sites on Signy Island, maritime Antarctic, between December 1992 and January 1994, and during the summer at a fourth coastal site. The concentrations of keratinaceous particles were monitored. Feather fragments were the most abundant of all particle types trapped. Seal hairs were also common, particularly on the coast. Numbers of both particle types were most common in the air in summer. The Antarctic soil fungus Geomyces pannorum, which is able to utilize keratin-based substrates, was also present in aerobiological samples on Signy Island. G. pannorum was only found during early winter on the year-round sampling sites. It was more abundant during summer in the air at the coastal site, which was more heavily influenced by seals, birds and humans. Skuas were swabbed when they returned to the island early in summer. G. pannorum was recovered in culture, suggesting that these birds may act as vectors for the transport of microorganisms between Antarctica and more northern landmasses. Organic material deposited on snow was concentrated on the soil at the edge of the ice cap by melt wash, making additional keratin and other organic substrates available to soil microorganisms.

Journal Article↗