1,864 research outputs found

    Genotypic Diversity In Populations Of A Fungal Endophyte From Douglas-Fir

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    Rhabdocline parkeri, an endophyte of Douglas fir, forms symptomless infections within single epidermal cells of healthy needles. Rhabdocline parkeri strains were isolated from trees growing in various habitats ranging from virgin old growth forests to a single young tree growing isolated in a meadow. Different genotypes of R. parkeri were distinguished by using the Random Amplified Polymorphic DNA (RAPD) technique. A significantly lower number of R. parkeri genotypes per unit foliage were isolated from trees within a 20-year-old managed stand and from an isolated tree than from old growth trees. Foliage from young trees (20 years old) in a stand directly adjacent to the sampled old growth trees showed levels of genotypic endophyte diversity comparable to that in the old growth trees. Genotypic diversity is estimated to be at least three orders of magnitude greater in foliage of the old growth trees and adjacent young trees than in foliage from the managed stand and from an isolated tree. This difference is ascribed to differences in tree age and access to inoculum

    Metabolically exaggerated cardiac reactions to acute psychological stress: The effects of resting blood pressure status and possible underlying mechanisms

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    The study aimed to: confirm that acute stress elicits metabolically exaggerated increases in cardiac activity; test whether individuals with elevated resting blood pressure show more exaggerated cardiac reactions to stress than those who are clearly normotensive; and explore the underlying mechanisms. Cardiovascular activity and oxygen consumption were measured pre-, during, and post- mental stress, and during graded submaximal cycling exercise in 11 young men with moderately elevated resting blood pressure and 11 normotensives. Stress provoked increases in cardiac output that were much greater than would be expected from contemporary levels of oxygen consumption. Exaggerated cardiac reactions were larger in the relatively elevated blood pressure group. They also had greater reductions in total peripheral resistance, but not heart rate variability, implying that their more exaggerated cardiac reactions reflected greater ÎČ-adrenergic activation

    Observations on the Ice-Breaking and Ice Navigation Behavior of Migrating Bowhead Whales (Balaena Mysticetus) near Point Barrow, Alaska, Spring 1985

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    During a four-day period from 28 April to 1 May 1985, we observed bowhead whales breaking up through sea ice in order to breathe. Our observations were made from grounded sea ice approximately 10 km northeast of Point Barrow, Alaska, during the spring bowhead migration (14 April to 10 June). From acoustic and visual data, it was estimated that 665 whales passed the observation perches during this four-day period. However, only 117(17%) whales were seen. The remaining whales either passed underneath the ice or were beyond the range of the visual observers. Whales used their heads, in the area of the blowholes, to push up against the ice (18 cm maximum thickness) and fracture it, creating a hummock of ice in which they were able to respire. Often during such breathing episodes, even at distances of only several hundred meters, the animal was not seen but its blows were clearly audible to the visual observers. Acoustic tracking of whales showed they avoided a large multi-year ice floe seaward of the observation perch. We hypothesize that bowheads use their calls to assess the thickness of ice in their migratory path. In assessing their calls, we suggest the whales can avoid areas where the ice is too thick to break through (to breath) and/or too thick to provide clearance for them to swim beneath.Key words: Balaena mysticetus, Point Barrow, bowhead whale, ice breaking, behavior, sea ice, singer, acoustic, anatomy, censusMots clés: Balaena mysticetus, Point Barrow, baleine franche, casser la glace, comportement, glace de mer, chanteuse, acoustique, anatomie, dénombremen

    Bowhead Whale (Balaena mysticetus) Feeding near Point Barrow, Alaska, During the 1985 Spring Migration

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    Examination of stomach contents and behavioral observations showed conclusively that bowhead whales were feeding in the Point Barrow area during the spring of 1985. All three bowheads harvested near the village of Barrow had over five litres of pelagic zooplankton (calanoid copepods and euphausiids) in their stomachs. Over 60 whales were observed during the period 26 May through 6 June diving repeatedly under the landfast ice and feeding in an area 11.2 km southwest of Point Barrow. Observers recorded times for dive, surfacing and respiration intervals for these whales. The recorded times were significantly different from those of bowhead whales migrating past Point Barrow in the spring and from bowheads, whose major activity was feeding, recorded in the Canadian Beaufort Sea during the summer and fall.Key words: Balaena mysticetus, Point Barrow, feeding, bowhead whale, behavior, copepod,  euphausiid, respiration, springUn examen du contenu stomacal de baleines franches et des observations de leur comportement ont montré sans aucun doute qu’elles se nourrissaient dans la zone de Point Barrow pendant le printemps de1985. Les trois baleines franches pêchées près du village de Barrow avaient toutes dans l’estomac plus de cinq litres de zooplancton pélagique (copépodes calanoïdes et euphausiacés). Pendant la période allant du 26 mai au 6 juin, on a observé plus de 60 baleines qui plongeaient de façon répétée sous la banquise côtière pour se nourrir dans une zone située à 11,2 km au sud-ouest de Point Barrow. Les observateurs ont noté le moment de la plongée et celui du retour à la surface, et l’intervalle entre les souffles des baleines. Les durées enregistrées étaient nettement différentes de celles mesurées pour des baleines franches qui passaient à Point Barrow pendant leur migration au printemps, et de celles enregistrées dans la mer de Beaufort canadienne en été et en automne pour des baleines franches dont l’activité principale était de se nourrir.Mots clés: Balaena mysticetus, Point Barrow, se nourrir, baleine franche, comportement, copépode, euphausiacé, respiration, printemp

    Distribution and Movements of the Teshekpuk Caribou Herd 1990–2005: Prior to Oil and Gas Development

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    Four caribou (Rangifer tarandus grantii) herds calve on the North Slope of Alaska, three of which have been exposed to little or no resource development. We present 15 years of baseline data on the distribution and movements of 72 satellite-collared and 10 GPS-collared caribou from the Teshekpuk caribou herd (TCH) that have had little to no exposure to oil and gas activities. Fixed-kernel home range analyses of collared caribou revealed that calving grounds were concentrated (i.e., 50% kernel utilization distribution) along the northeastern, eastern, and southeastern shores of Teshekpuk Lake. During the postcalving period, 51% and 35% of caribou moved through two constricted zones to the east and west of Teshekpuk Lake, respectively, and accessed insect-relief habitat along the Beaufort Sea coast. During late summer and early fall, TCH caribou were concentrated to the southeast and southwest of Teshekpuk Lake. Although 65% of the Teshekpuk caribou wintered in two areas on the central coastal plain around the village of Atqasuk and south of Teshekpuk Lake, other TCH animals wintered in a great variety of places, including the Seward Peninsula, the eastern and southern Brooks Range, and the Arctic National Wildlife Refuge. We detected an apparent emigration rate of 6.9%. One male and five female TCH caribou joined the breeding populations of the Western Arctic and Central Arctic herds. TCH caribou traveled an average distance of 2348 ± 190 km annually. Movement rates were at a maximum in midsummer, lowest in winter, and intermediate during spring and fall migrations. Restrictions on oil and gas leasing and surface occupancy have been in place to protect calving, migratory corridors, and insect-relief habitat for the TCH, but these protections are likely to be removed. These data will provide a good baseline that can be used to compare predevelopment distribution and movement patterns of TCH caribou to distribution and movement patterns during and after petroleum development.Quatre hardes de caribous (Rangifer tarandus grantii) vĂȘlent sur la cĂŽte nord de l’Alaska, dont trois de ces hardes ont Ă©tĂ© exposĂ©es Ă  peu ou pas d’amĂ©nagement des ressources. Nous prĂ©sentons des donnĂ©es de base Ă©chelonnĂ©es sur 15 ans relativement Ă  la rĂ©partition et aux dĂ©placements de 72 caribous dotĂ©s d’un collier Ă©metteur par satellite et de 10 caribous munis d’un collier Ă©metteur GPS de la harde de caribous de Teshekpuk (HCT), caribous qui ont Ă©tĂ© peu ou pas du tout frottĂ©s aux activitĂ©s pĂ©troliĂšres et gaziĂšres. L’analyse du noyau fixe des domaines vitaux des caribous Ă  collier a rĂ©vĂ©lĂ© que les lieux de vĂȘlage Ă©taient concentrĂ©s (c’est-Ă -dire 50 % de la rĂ©partition de l’utilisation du noyau) le long des cĂŽtes nord-est, est et sud-est du lac Teshekpuk. AprĂšs la pĂ©riode de vĂȘlage, 51 pour cent et 35 pour cent des caribous se dĂ©plaçaient au sein de deux zones de constriction Ă  l’est et Ă  l’ouest du lac Teshekpuk, respectivement, et accĂ©daient un habitat oĂč se trouvait moins d’insectes sur la cĂŽte de la mer de Beaufort. Vers la fin de l’étĂ© et le dĂ©but de l’automne, les caribous de la HCT Ă©taient concentrĂ©s au sud-est et au sud-ouest du lac Teshekpuk. Bien que 65 pour cent des caribous de Teshekpuk passaient l’hiver dans deux rĂ©gions de la plaine cĂŽtiĂšre centrale autour du village d’Atqasuk et au sud du lac Teshekpuk, les autres bĂȘtes de la HCT passaient l’hiver dans divers endroits, dont la pĂ©ninsule de Seward, les versants est et sud des montagnes de Brooks et la RĂ©serve faunique nationale de l’Arctique. Nous avons dĂ©tectĂ© un taux d’émigration apparent de 6,9 pour cent. Un caribou mĂąle et cinq caribous femelles de la HCT ont rejoint les populations de reproduction des hardes de l’ouest et du centre de l’Arctique. En moyenne, le caribou de la HCT parcourait une distance de 2348 ± 190 km annuellement. Les taux de dĂ©placement Ă©taient Ă  leur point le plus Ă©levĂ© au milieu de l’étĂ©, tandis qu’ils Ă©taient Ă  leur niveau le plus bas l’hiver et Ă  un niveau intermĂ©diaire pendant les migrations du printemps et de l’automne. Il existe des restrictions en matiĂšre de location et d’occupation en surface pour le pĂ©trole et le gaz afin de protĂ©ger le vĂȘlage, les corridors de migration et les habitats Ă  faible taux d’insectes pour la HCT, mais il est vraisemblable que ces restrictions soient Ă©liminĂ©es. Ces donnĂ©es fourniront une bonne base pour comparer la rĂ©partition et les dĂ©placements du caribou de la HCT avant la mise en valeur des ressources Ă  la rĂ©partition et aux dĂ©placements du caribou de la HCT pendant et aprĂšs la mise en valeur pĂ©troliĂšre

    Use of satellite telemetry data, GIS, and HTML to create an interactive display of caribou movements

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    The use of animation clearly reveals the large annual variation in wintering areas and large differences in daily movement rates for this herd. This interactive display can be adapted for school groups, subsistence hunters, the general public, or scientists

    Use of satellite telemetry to evaluate movements of caribou within subsistence hunting areas in northern Alaska

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    Caribou from the Teshekpuk Herd (TH) are an important subsistence resource for residents of Inupiaq villages in northern Alaska. In recent years the use of satellite telemetry has increased the understanding of the herd's annual movements and interactions with other herds. Most caribou of the TH are within the National Petroleum Reserve—Alaska (NPRA) throughout the year. The northeastern portion of NPRA has undergone two lease sales for oil and gas exploration, and lease sales are tentatively scheduled for the central/northwest portion of the NPRA in 2004. During 1990—1999, the movements of 27 caribou from the TH were tracked using satellite collars. We evaluated the proportion of time caribou were available to Inupiaq hunters by incorporating maps depicting subsistence-use areas for each of seven Inupiaq villages, and then examining seasonal and annual movements of caribou relative to those areas. By combining caribou locations with subsistence hunting areas, we were able to explore spatial and temporal patterns in caribou availability to subsistence hunters. This information is useful for managers to set appropriate hunting regulations and for devising sensible alternatives and mitigation of likely petroleum development in NPRA

    Investigation of Heavy Metals in a Large Mortality Event in Caribou of Northern Alaska

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    We measured element concentrations (As, Cd, Cu, Pb, Zn, Fe) and body condition (gross and histologic endpoints) of animals from a caribou (Rangifer tarandus) mortality event that occurred in Alaska, in the area of Point Hope and Cape Thompson (including the Chariot site), in 1995. These were compared to results from hunter-killed caribou from reference sites (Barrow and Teshekpuk Lake, Alaska) and from the area of a mine (Red Dog Mine) to determine whether heavy metals had played a role in the mortality event or whether any elements were at concentrations of concern for human consumers. Starvation and malnutrition were major factors leading to death or severe weakness, as very little or no fat (very low body condition scores) and serous atrophy of fat (observed as watery contents of the marrow cavity, with no apparent fat, and histologically) were more prevalent in caribou associated with the mortality event than in hunter-killed animals from reference sites. Accumulation of hepatic (liver) hemosiderin in Kupffer cells (macrophages) was noted as an indicator of cachexia. Concentrations of lead in feces and liver, copper in the rumen contents, and arsenic in muscle were higher in caribou harvested near Red Dog Mine, as might be expected in that mineral-rich area, but were not at levels of concern for toxicoses. Kidney concentrations of cadmium, which increased significantly with increasing age, present a potential concern for human consumers, and this is an expected finding. We concluded that caribou had starved and that heavy metals had played no role in the mortality event. Further investigation of regional mineral differences is required to understand the sources and transport mechanisms that explain these findings and to properly address mining activity. Mortality events on the north slope of Alaska are common and likely involve starvation as described here, but in most cases they are not investigated, even though recent industrial activities have heightened concern among some local residents and wildlife managers.On a mesurĂ© la concentration en Ă©lĂ©ments (As, Cd, Cu, Pb, Zn, Fe) et l'Ă©tat corporel (points limites bruts et histologiques) de caribous (Rangifer tarandus) prĂ©levĂ©s lors d'un Ă©pisode de mortalitĂ© qui s'est produit en 1995 en Alaska, dans la rĂ©gion de Point Hope et de Cape Thompson (y compris le site Chariot). On a comparĂ© ces rĂ©sultats Ă  ceux de caribous tuĂ©s par des chasseurs Ă  des emplacements tĂ©moins (Barrow et Teshekpuk Lake, en Alaska) et Ă  proximitĂ© d'une mine (Red Dog Mine) pour trouver si les mĂ©taux lourds avaient jouĂ© un rĂŽle dans l'Ă©pisode de mortalitĂ© ou si la concentration d'un ou plusieurs Ă©lĂ©ments pouvait constituer un risque pour la consommation humaine. La famine et la malnutrition Ă©taient des facteurs majeurs ayant causĂ© la mort ou une extrĂȘme faiblesse, vu que la prĂ©sence minime ou l'absence de graisse (trĂšs basses notes d'Ă©tat corporel) et une atrophie sĂ©reuse de la graisse (observĂ©e sous forme de contenu aqueux de la cavitĂ© mĂ©dullaire, sans graisse visible, et Ă  la suite de l'examen histologique) Ă©taient plus courantes chez le caribou associĂ© Ă  l'Ă©pisode de mortalitĂ© que chez les animaux des emplacements tĂ©moins tuĂ©s par les chasseurs. On a notĂ© dans le foie une accumulation d'hĂ©mosidĂ©rine hĂ©patique des cellules de Kupffer (cellules macrophages) tĂ©moignant d'une cachexie. La concentration de plomb dans les matiĂšres fĂ©cales et le foie, de cuivre dans le rumen et d'arsenic dans le tissu musculaire Ă©tait plus Ă©levĂ©e chez le caribou provenant de Red Dog Mine, comme on pouvait s'y attendre dans cette zone riche en minĂ©raux, mais cette concentration n'atteignait pas un niveau pouvant provoquer des toxicoses. La concentration de cadmium dans le rein, qui augmentait de façon significative avec l'Ăąge, pourrait constituer un risque pour la consommation humaine, ce qui n'est pas surprenant. On a conclu que les caribous Ă©taient morts de faim et que les mĂ©taux lourds n'avaient jouĂ© aucun rĂŽle dans l'Ă©pisode de mortalitĂ©. Il faudrait effectuer des recherches plus poussĂ©es sur les diffĂ©rences rĂ©gionales en minĂ©raux afin de comprendre les mĂ©canismes d'origine et de transport qui expliquent ces rĂ©sultats et d'aborder comme il le faut les activitĂ©s miniĂšres. Les Ă©pisodes de mortalitĂ© sont courants sur le versant Nord de l'Alaska et sont probablement liĂ©s Ă  la famine, comme le dĂ©crit cet article, mais dans la plupart des cas ils ne font pas l'objet d'une enquĂȘte, mĂȘme si l'activitĂ© industrielle rĂ©cente est un sujet qui prĂ©occupe de plus en plus certains rĂ©sidents et gestionnaires locaux de la faune

    Associations of sperm telomere length with semen parameters, clinical outcomes and lifestyle factors in human normozoospermic samples

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    Background Many studies have demonstrated that lifestyle factors can affect sperm quality and fertility. Sperm telomere length (STL) has been reported as potential biomarker or sperm quality. However, no studies have investigated how lifestyle factors can affect STL and associated clinical outcomes. Objectives The purpose of this manuscript is to investigate any association between STL with lifestyle factors, semen parameters and clinical outcomes. Materials and methods Sperm telomere length was measured using real‐time PCR in normozoospermic male partners (n = 66) of couples undergoing ART treatment. Each participant also completed a detailed questionnaire about general lifestyle. Linear regression univariate analysis and ANCOVA were performed to respectively determine correlations between STL and study parameters or identify statistically significant differences in STL while controlling for age, BMI and other factors. Results Using a linear regression model, STL is positively correlated with in vitro fertilization success (n = 65, r = 0.37, P = .004) but not with embryo cleavage rates and post‐implantation clinical outcomes including gestational age‐adjusted birth weight. No associations were observed between STL and sperm count, concentration or progressive motility. We further found that STL did not associate age, BMI, health or lifestyle factors. Discussion In somatic cells, the rate of telomere shortening is influenced by a number of lifestyle factors such as smoking, diet and occupation. However, little is known about how lifestyle factors affect STL and subsequently reproductive outcome. Out data suggest that STL might have an important role mechanistically for fertilization rate regardless of sperm parameters and lifestyle factors. Conclusion The results of this study demonstrate that STL is associated with in vitro fertilization rates, but not with semen parameters nor lifestyle factors. Further investigations are warranted to identify the potential variation of STL overtime to clarify its significance as a potential biomarker in ART
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