Adaptation of the melatonin rhythm in human subjects following nightshift work in Antarctica

first_imgDifferent environmental conditions, particularly daylength and intensity of natural light, may influence the ability of shiftworkers to adapt to the abrupt phase-shifts of 24 h time cues imposed by the nature of their work. We have investigated this problem in terms of the circadian rhythm of the pineal hormone melatonin in nightshift workers on the British Antarctic Survey Base at Halley (75° South). Melatonin production was assessed by measurement of its major urinary metabolite 6-sulphatoxymelatonin (aMT6s) by radio-immunoassay in sequential urine samples collected for 48 h at weekly intervals. The acrophase of the melatonin rhythm was significantly delayed from 5.22 h.min to 14.54 h.min (summer) and 8.73 h.min to 13.23 h.min (winter) during a week of night-shift work. Readaptation of the rhythm following night-shift work was markedly slower during the Antarctic winter taking 3 weeks compared to summer where the baseline phase position was re-established after 1 week. Morning and evening treatment (08.00–09.00 h, 16.00–17.00 h) with bright (> 2500 lux) full spectrum white light did not significantly modify this phenomenon in summer, but a trend to faster adaptation with light treatment was seen in winter. These observations are likely to be of importance to shift-workers in temperate zones. Further investigations of phase-shifting techniques, such as appropriately timed bright light and administration of melatonin itself, are indicated, particularly in relation to performance at work.last_img read more

Distribution of pelagic larvae of benthic marine invertebrates in the Bellingshausen Sea

first_imgDuring November and December 1992, plankton samples were collected using a ring net of mesh size 200 μm vertically hauled through a 600 m water column, at five stations along a transect running north from the Allison Peninsula in the Bellingshausen Sea. Three stations were located over the continental shelf; two of these were ice bound, whilst the third was at the ice edge. Two other stations were in deeper, ice-free water. Sixteen different larval and juvenile types were found representing seven phyla: Echinodermata, Nemertea, Coelenterata, Mollusca, Annelida, Arthropoda and Bryozoa, of which the first two were the most abundant. Larval numbers and types decreased with distance offshore and away from permanent sea ice. The presence of many stages of nemertean larval development within a short time scale, in an area where developmental tends to be slow, suggests that reproduction occurs over an extended period and that the larvae have a long planktonic phase. The increased size of later developmental stages of the nemertean larvae indicates they obtain nutrition within the water column during winter, when little particulate food is present.last_img read more

Continental governance and environmental management mechanisms under the Antarctic Treaty System: sufficient for the biodiversity challenges of the this century?

first_imgAntarctic terrestrial biodiversity is challenged by rapid climatic changes and expansion of the human footprint. As well as the potential for environmental damage at the local level, these challenges are likely to act synergistically to increase the risk of introduction and establishment of non-native species and diseases and reduce the resilience of native ecosystems. The Protocol on Environmental Protection to the Antarctic Treaty (‘the Protocol’) entered into force in 1998 and is the main governance mechanism that regulates environmental management in Antarctica. We examine how well the Protocol and associated management tools are currently equipped to protect Antarctic terrestrial biodiversity in a warmer and busier Antarctic, considering likely future challenges, current levels of compliance with the Protocol and implementation of its requirements, and participation in environmental matters by Antarctic Treaty Parties. We argue that a strategic-level response will be needed to boost the ability of the Antarctic Treaty System to deal with the large-scale, pervasive challenges of climate change and increased human activity. A strategic planning approach that can (1) account for trends over long periods, (2) take into consideration cumulative effects, (3) be guided by a set of consciously chosen priorities, and (4) take an integrated approach towards management of human activities and the conservation of the Antarctic environment, will permit the anticipation of upcoming challenges and risks and adoption of proactive and holistic management strategies.last_img read more

The science case for the EISCAT_3D radar

first_imgThe EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere (the ionosphere). The mainland radars were constructed about 30 years ago, based on technological solutions of that time. The science drivers of today, however, require a more flexible instrument, which allows measurements to be made from the troposphere to the topside ionosphere and gives the measured parameters in three dimensions, not just along a single radar beam. The possibility for continuous operation is also an essential feature. To facilitatefuture science work with a world-leading IS radar facility, planning of a new radar system started first with an EU-funded Design Study (2005–2009) and has continued with a follow-up EU FP7 EISCAT_3D Preparatory Phase project (2010–2014). The radar facility will be realised by using phased arrays, and a key aspect is the use of advanced software and data processing techniques. This type of software radar will act as a pathfinder for other facilities worldwide. The new radar facility will enable the EISCAT_3D science community to address new, significant science questions as well as to serve society, which is increasingly dependent on space-based technology and issues related to space weather. The location of the radar within the auroral oval and at the edge of the stratospheric polar vortex is also ideal for studies of the long-term variability in the atmosphere and global change. This paper is a summary of the EISCAT_3D science case, which was prepared as part of the EU-funded Preparatory Phase project for the new facility. Three science working groups, drawn from the EISCAT user community, participated in preparing this document. In addition to these working group members, who are listed as authors, thanks are due to many others in the EISCAT scientific community for useful contributions, discussions, and support.last_img read more

Diapause induces remodelling of the fatty acid composition of membrane and storage lipids in overwintering larvae of Ostrinia nubilalis, Hubn. (Lepidoptera: Crambidae)

first_imgSeasonal changes in the FA composition of triacylglycerols and phospholipids prepared from the whole body of non-diapausing and diapausing fifth instar larvae of Ostrinia nubilalis, Hubn. (Lepidoptera: Crambidae) were determined to evaluate the role of these lipids in diapause. Substantial changes in the FA composition of triacylglycerols and phospholipids were triggered by diapause development. This led to a significant increase in the overall FA unsaturation (UFAs/SFAs ratio), attributable to an increase in the relative proportion of MUFAs and the concomitant decrease in PUFAs and SFAs. In triacylglycerols, the significant changes in FAs composition is the result of an increase in the relative proportions of MUFAs, palmitoleic acid (16:1n-7) and oleic acid (18:1n-9), and a concomitant reduction in composition of SFAs and PUFAs, mainly palmitic acid (16:0) and linoleic acid (18:2n-6), respectively. Changes in the composition of phospholipids were more subtle with FAs contributing to the overall increase of FA unsaturation. Differential scanning calorimetry (DSC) analysis revealed that the melt transition temperatures of total lipids prepared from whole larvae, primarily attributable to the triacylglycerol component, were significantly lower during the time course of diapause compared with non-diapause. These observations were correlated to the FA composition of triacylglycerols, most likely enabling them to remain functional during colder winter conditions. We conclude that O. nubilalis undergoes remodelling of FA profiles of both energy storage triacylglycerols and membrane phospholipids as an element of its overwintering physiology which may improve the ability to cold harden during diapause.last_img read more

A cautionary tale: A study of a methane enhancement over the North Sea

first_imgAirborne measurements of a methane (CH4) plume over the North Sea from August 2013 are analyzed. The plume was only observed downwind of circumnavigated gas fields, and three methods are used to determine its source. First, a mass balance calculation assuming a gas field source gives a CH4 emission rate between 2.5 ± 0.8×104 and 4.6 ± 1.5×104 kg h−1. This would be greater than the industry’s reported 0.5% leak rate if it were emitting for more than half the time. Second, annual average UK CH4 emissions are combined with an atmospheric dispersion model to create pseudo-observations. Clean air from the North Atlantic passed over mainland UK, picking up anthropogenic emissions. To best explain the observed plume using pseudo-observations, an additional North Sea source from the gas rigs area is added. Third, the δ13C-CH4 from the plume is shown to be −53‰, which is lighter than fossil gas but heavier than the UK average emission. We conclude that either an additional small-area mainland source is needed, combined with temporal variability in emission or transport in small-scale meteorological features. Alternatively, a combination of additional sources that are at least 75% from the mainland (−58‰) and up to 25% from the North Sea gas rigs area (−32‰) would explain the measurements. Had the isotopic analysis not been performed, the likely conclusion would have been of a gas field source of CH4. This demonstrates the limitation of analyzing mole fractions alone, as the simplest explanation is rejected based on analysis of isotopic data.last_img read more

Temporal variation in trophic relationships among three congeneric penguin species breeding in sympatry

first_imgPenguins are a monophyletic group in which many species are found breeding sympatrically, raising questions regarding how these species coexist successfully. Here, the isotopic niche of three sympatric pygoscelid penguin species was investigated at Powell Island, South Orkney Islands, during two breeding seasons (austral summers 2013–2014 and 2015–2016). Measurements of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios were obtained from blood (adults) or feather (chicks) samples collected from Adélie Pygoscelis adeliae, chinstrap P. antarctica, and gentoo P. papua penguins. Isotopic niche regions (a proxy for the realized trophic niches) were computed to provide estimates of the trophic niche width of the studied species during the breeding season. The isotopic niche regions of adults of all three species were similar, but gentoo chicks had noticeably wider isotopic niches than the chicks of the other two species. Moderate to strong overlap in isotopic niche among species was found during each breeding season and for both age groups, suggesting that the potential for competition for shared food sources was similar during the two study years, although the actual level of competition could not be determined owing to the lack of data on resource abundance. Clear interannual shifts in isotopic niche were seen in all three species, though of lower amplitude for adult chinstrap penguins. These shifts were due to variation in carbon, but not nitrogen, isotopic ratios, which could indicate either a change in isotopic signature of their prey or a switch to an alternative food web. The main conclusions of this study are that (1) there is a partial overlap in the isotopic niches of these three congeneric species and that (2) they responded similarly to changes that likely occurred at the base of their food chain between the 2 years of the study.last_img read more

Distinct oceanic microbiomes from viruses to protists located near the Antarctic Circumpolar Current

first_imgMicrobes occupy diverse ecological niches and only through recent advances in next generation sequencing technologies have the true microbial diversity been revealed. Furthermore, lack of perceivable marine barriers to genetic dispersal (i.e., mountains or islands) has allowed the speculation that organisms that can be easily transported by currents and therefore proliferate everywhere. That said, ocean currents are now commonly being recognized as barriers for microbial dispersal. Here we analyzed samples collected from a total of six stations, four located in the Indian Ocean, and two in the Southern Ocean. Amplicon sequencing was used to characterize both prokaryotic and eukaryotic plankton communities, while shotgun sequencing was used for the combined environmental DNA (eDNA), microbial eDNA (meDNA), and viral fractions. We found that Cyanobacteria dominated the prokaryotic component in the South-West Indian Ocean, while γ-Proteobacteria dominated the South-East Indian Ocean. A combination of γ- and α-Proteobacteria dominated the Southern Ocean. Alveolates dominated almost exclusively the eukaryotic component, with variation in the ratio of Protoalveolata and Dinoflagellata depending on station. However, an increase in haptophyte relative abundance was observed in the Southern Ocean. Similarly, the viral fraction was dominated by members of the order Caudovirales across all stations; however, a higher presence of nucleocytoplasmic large DNA viruses (mainly chloroviruses and mimiviruses) was observed in the Southern Ocean. To our knowledge, this is the first that a statistical difference in the microbiome (from viruses to protists) between the subtropical Indian and Southern Oceans. We also show that not all phylotypes can be found everywhere, and that meDNA is not a suitable resource for monitoring aquatic microbial diversity.last_img read more

Scoreboard roundup — 5/9/19

first_img FacebookTwitterLinkedInEmailiStock(NEW YORK) — Here are the scores from Thursday’s sports events:MAJOR LEAGUE BASEBALLINTERLEAGUECincinnati 3, Oakland 0AMERICAN LEAGUECleveland 5, Chi White Sox 0, 5 InningsLA Angels 13, Detroit 0NY Yankees 3, Seattle 1Houston 4, Texas 2NATIONAL LEAGUEChi Cubs 4, Miami 1Colorado 12, San Francisco 11St. Louis 17, Pittsburgh 4Arizona 3, Atlanta 2, 10 InningsWashington 6, LA Dodgers 0NATIONAL BASKETBALL ASSOCIATION PLAYOFFSPhiladelphia 112, Toronto 101 (series tied 3-3)Portland 119, Denver 108 (series tied 3-3)NATIONAL HOCKEY LEAGUE PLAYOFFSBoston 5, Carolina 2 (Boston leads series 1-0)WOMEN’S NATIONAL BASKETBALL ASSOCIATION PLAYOFFSNY Liberty 89, China National Team 71Copyright © 2019, ABC Radio. All rights reserved. Written by May 10, 2019 /Sports News – National Scoreboard roundup — 5/9/19center_img Beau Lundlast_img read more

Utah’s Mitchell Vying For Team USA Spot

first_imgJune 11, 2019 /Sports News – Local Utah’s Mitchell Vying For Team USA Spot Written by Tags: Donovan Mitchell/Kyle Kuzma/Team USA Robert Lovell FacebookTwitterLinkedInEmail(Salt Lake City, UT)  —  Jazz guard Donovan Mitchell is one of 20 players vying for a spot on Team USA this summer.Mitchell will train with the team in Las Vegas starting in August.  Team USA will compete in the FIBA World Cup opening on August 31st in China.Only a dozen players will make the team.  Former Utah Ute Kyle Kuzma is also trying out.last_img