scholarly journals Splenic contraction is enhanced by exercise at simulated high altitude

2021 ◽  
Author(s):  
Angelica Lodin-Sundström ◽  
Pontus Holmström ◽  
Marcus Ekstam ◽  
Daniel Söderberg ◽  
Erika Schagatay
Keyword(s):  
High Altitude ◽  
Spleen Volume ◽  
Short Term ◽  
Graded Response ◽  
Simulated High Altitude ◽  
Oxygen Carrying Capacity ◽  
Partial Contraction ◽  
Hypoxic Exercise ◽  
Term Field

Abstract Purpose Splenic contraction increases circulating hemoglobin (Hb) with advantages during hypoxia. As both hypoxia and exercise have been shown to be important separate triggers of splenic contraction we aimed to investigate if the spleen response to simulated high altitude (HA) is enhanced by superimposing exercise. Method Fourteen healthy volunteers (seven females) performed the following protocol in a normobaric environment sitting on an ergometer cycle: 20 min rest in normoxia; 20 min rest while breathing hypoxic gas simulating an altitude of 3500 m; 10 min exercise at an individually set intensity while breathing the hypoxic gas; 20 min rest in hypoxia; and finally 20 min rest in normoxia. Spleen measurements were collected by ultrasonic imaging and venous Hb measured at the end of each intervention. Result Mean ± SD baseline spleen volume during normoxic rest was 280 ± 107 mL, the volume was reduced by 22% during rest in hypoxia to 217 ± 92 mL (p < 0.001) and by 33% during exercise in hypoxia (189 mL; p < 0.001). Hb was 140.7 ± 7.0 g/L during normoxic rest and 141.3 ± 7.4 g/L during hypoxic rest (NS), but increased by 5.3% during hypoxic exercise (148.6 ± 6.3 g/L; p < 0.001). Spleen volume and Hb were stepwise changed back to baseline at cessation of exercise and return to normoxia. Conclusion Splenic contraction is induced by hypoxia and further enhanced by superimposing exercise, and reduced when exercise ceases, in a step-wise manner, showing that the tonic but partial contraction observed in long-term field expeditions to HA may occur also in the short term. This “graded response” may be beneficial during acclimatization to HA, to cope with moderate chronic hypoxia during rest while allowing additional enhancement of oxygen carrying capacity to overcome short bouts of extreme hypoxia caused by exercise.

scholarly journals BrO/SO<sub>2</sub> molar ratios from scanning DOAS measurements in the NOVAC network

2013 ◽  
Vol 5 (2) ◽  
pp. 1845-1870 ◽  
Author(s):  
P. Lübcke ◽  
N. Bobrowski ◽  
S. Arellano ◽  
B. Galle ◽  
G. Garzón ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Optical Absorption Spectroscopy ◽  
Short Term ◽  
Dynamic Changes ◽  
Volcanic System ◽  
Molar Ratios ◽  
Remote Sensing Technique ◽  
Field Campaigns ◽  
Term Field

Abstract. The molar ratio of BrO to SO2 is, like other halogen/sulphur ratios, a~possible precursor for dynamic changes in the shallow part of a volcanic system. While the predictive significance of the BrO/SO2 ratio has not been well constrained yet, it has the major advantage that this ratio can be readily measured using the remote-sensing technique Differential Optical Absorption Spectroscopy (DOAS) in the UV. While BrO/SO2 ratios have been measured during several short-term field campaigns this article presents an algorithm that can be used to obtain long-term time series of BrO/SO2 ratios from the scanning DOAS instruments of the Network for Observation of Volcanic and Atmospheric Change (NOVAC) or comparable networks. Parameters of the DOAS retrieval of both trace gases are given and the influence of co-adding spectra on the retrieval error will be investigated. Difficulties in the evaluation of spectroscopic data from monitoring instruments in volcanic environments and possible solutions are discussed. The new algorithm is demonstrated by evaluating data from the NOVAC scanning DOAS systems at Nevado del Ruiz, Colombia encompassing almost four years of measurements between November 2009 and end of June 2013. This dataset shows variations of the BrO/SO2 ratio several weeks prior to the eruption on 30 June 2012.

Adaptations to High-Altitude Hypoxia

2021 ◽  
Author(s):  
Cynthia M. Beall ◽  
Kingman P. Strohl
Keyword(s):  
High Altitude ◽  
Oxygen Delivery ◽  
Hemoglobin Concentration ◽  
Barometric Pressure ◽  
Ambient Air ◽  
Extreme Environment ◽  
Indigenous Populations ◽  
East African ◽  
Short Term

Biological anthropologists aim to explain the hows and whys of human biological variation using the concepts of evolution and adaptation. High-altitude environments provide informative natural laboratories with the unique stress of hypobaric hypoxia, which is less than usual oxygen in the ambient air arising from lower barometric pressure. Indigenous populations have adapted biologically to their extreme environment with acclimatization, developmental adaptation, and genetic adaptation. People have used the East African and Tibetan Plateaus above 3,000 m for at least 30,000 years and the Andean Plateau for at least 12,000 years. Ancient DNA shows evidence that the ancestors of modern highlanders have used all three high-altitude areas for at least 3,000 years. It is necessary to examine the differences in biological processes involved in oxygen exchange, transport, and use among these populations. Such an approach compares oxygen delivery traits reported for East African Amhara, Tibetans, and Andean highlanders with one another and with short-term visitors and long-term upward migrants in the early or later stages of acclimatization to hypoxia. Tibetan and Andean highlanders provide most of the data and differ quantitatively in biological characteristics. The best supported difference is the unelevated hemoglobin concentration of Tibetans and Amhara compared with Andean highlanders as well as short- and long-term upward migrants. Moreover, among Tibetans, several features of oxygen transfer and oxygen delivery resemble those of short-term acclimatization, while several features of Andean highlanders resemble the long-term responses. Genes and molecules of the oxygen homeostasis pathways contribute to some of the differences.

Study on Characteristics of Water Waves in Bohai Sea Using SWAN Model

2014 ◽  
Vol 522-524 ◽  
pp. 983-989
Author(s):  
Dao Sheng Wang ◽  
Xiang Cui Lv ◽  
De Kui Yuan
Keyword(s):  
Wave Height ◽  
Water Waves ◽  
Bohai Sea ◽  
Measured Data ◽  
Wave Direction ◽  
Short Term ◽  
The Bohai Sea ◽  
Good Agreement ◽  
Term Field

The SWAN (Simulating WAves Nearshore) model was applied to study the characteristics of water waves in the Bohai Sea. The model was calibrated against both short-term and long-term field measured data from six different stations in the Bohai Sea and the computational results are in good agreement with the measured data. Then the wave process during 1999 to 2009 in the Bohai Sea was simulated using the calibrated model. The wave characteristics such as significant wave height, average period, dominant wave direction and their seasonal variations were analyzed based on the simulated results. The distributions of wave height and wave period are similar to those of the previous studies, but the wave height is slightly smaller than that given by other researchers.

scholarly journals Long-term field-realistic exposure to a next-generation pesticide, flupyradifurone, impairs honey bee behaviour and survival

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Simone Tosi ◽  
James C. Nieh ◽  
Annely Brandt ◽  
Monica Colli ◽  
Julie Fourrier ◽  
...  
Keyword(s):  
Honey Bees ◽  
Global Scale ◽  
Risk Assessments ◽  
Ring Test ◽  
Emerging Contaminant ◽  
Short Term ◽  
Insect Pollinators ◽  
Impact Of Pesticides ◽  
Term Field

AbstractThe assessment of pesticide risks to insect pollinators have typically focused on short-term, lethal impacts. The environmental ramifications of many of the world’s most commonly employed pesticides, such as those exhibiting systemic properties that can result in long-lasting exposure to insects, may thus be severely underestimated. Here, seven laboratories from Europe and North America performed a standardised experiment (a ring-test) to study the long-term lethal and sublethal impacts of the relatively recently approved ‘bee safe’ butenolide pesticide flupyradifurone (FPF, active ingredient in Sivanto®) on honey bees. The emerging contaminant, FPF, impaired bee survival and behaviour at field-realistic doses (down to 11 ng/bee/day, corresponding to 400 µg/kg) that were up to 101-fold lower than those reported by risk assessments (1110 ng/bee/day), despite an absence of time-reinforced toxicity. Our findings raise concerns about the chronic impact of pesticides on pollinators at a global scale and support a novel methodology for a refined risk assessment.

scholarly journals Long-term field experiment on the impacts of the neonicotinoid dinotefuran and the organophosphate fenitrothion on a honeybee colony

2015 ◽  
Author(s):  
Toshiro Yamada ◽  
Yasuhiro Yamada ◽  
Kazuko Yamada
Keyword(s):  
Field Experiment ◽  
Lethal Dose ◽  
Short Term ◽  
Long Period ◽  
Sugar Syrup ◽  
The World ◽  
Long Term Experiments ◽  
Honeybee Colony ◽  
Term Field

Neonicotinoides are persistent and highly toxic pesticides that have become popular instead of organophosphates, being suspected to be a trigger of massive disappearance of bees that raises concern in the world. The evaluation of the long-term influence for a whole colony in the natural environment is, however, not established yet. In this paper, we conducted a long-term field experiment and found different impacts on honeybee colonies (Apis mellifera) in an apiary between the neonicotinoid dinotefuran and the organophosphate fenitrothion even though whose concentrations in sugar syrup provided for bees were adjusted to have nearly equal short-term effects on a honeybee based on the median lethal dose (LD50) as well as the insecticidal activity to exterminate stinkbugs. The colony with administration of dinotefran (dinotefuran colony) became extinct in 26 days, while the colony with administration of fenitrothion (fenitrothion colony) survived the administration for the same period. Furthermore, the fenitrothion colony succeeded to be alive for more than 293 days after administration, and also succeeded an overwintering, which indicates that colonies exposed to fenitrothion can recover after the exposure. Meanwhile, the dinotefuran colony became extinct even though the intake of dinotefuran was estimated to be comparable with that of fenitrothion in terms of the LD50 of a honeybee. Moreover, the colonies in our previous long-term experiments where dinotefuran with higher concentration were administered only for first few days (Yamada et al., 2012) became extinct in 104 days and 162 days, respectively. From these results, we speculate that colonies exposed to dinotefuran hardly recover from the damage because dinotefuran is much more persistent than fenitrothion and toxic foods stored in cells can affect a colony in a long period.

scholarly journals Genetic variation in phenology and growth among and within Norway spruce populations from two altitudinal transects in Mid-Norway

Silva Fennica ◽  
2019 ◽  
Vol 53 (1) ◽  
Author(s):  
Tore Skrøppa ◽  
Arne Steffenrem
Keyword(s):  
High Altitude ◽  
Norway Spruce ◽  
Genetic Correlations ◽  
Natural Populations ◽  
Height Growth ◽  
Population Variation ◽  
Clinal Variation ◽  
Short Term ◽  
Narrow Sense Heritability

Progenies from open pollinated cones collected in natural populations of Norway spruce ( (L. Karst.)) distributed along two altitudinal transects in Mid-Norway were tested in the nursery, in short term tests and in long-term field trials. The populations showed clinal variation related to the mean annual temperatures of the populations, with the earliest bud flush and cessation of shoot elongation and lowest height at age nine years for the high altitude populations. Within population variation was considerable as the narrow sense heritability for these traits was 0.67, 0.31 and 0.09 in one transect and 0.55, 0.18 and 0.14 in the other transect, respectively. Lammas shoots occurred in the short term trials with large variation in frequency between years. There was significant family variation for this trait, but also interactions between populations and year. The variance within populations was considerably larger in the populations from low altitude compared to the high-altitude populations. Significant genetic correlations between height and phenology traits and damage scores indicate that families flushing early and ceasing growth late were taller. Taller families also had higher frequencies of damages. Selection of the top 20% families for height growth in short term tests at age nine years gave a simulated gain of 11% increased height growth at age 18 years in long term trials at altitudes similar to those of origin of the populations. The gain was negative when high altitude populations were selected based on testing in the lowland.Picea abies

scholarly journals On the importance of time scales when studying adaptive evolution

2018 ◽  
Author(s):  
Charles Perrier ◽  
Anne Charmantier
Keyword(s):  
Time Scales ◽  
Quantitative Traits ◽  
Field Studies ◽  
Data Series ◽  
Wild Populations ◽  
Short Term ◽  
Trait Variation ◽  
Bill Length ◽  
Term Field

AbstractLong-term field studies coupled with quantitative genomics offer a powerful means to understand the genetic bases underlying quantitative traits and their evolutionary changes. However, analyzing and interpreting the time scales at which adaptive evolution occurs is challenging. First, while evolution is predictable in the short term, with strikingly rapid phenotypic changes in data series, it remains unpredictable in the long term. Second, while the temporal dynamics of some loci with large effect on phenotypic variation and fitness have been characterized, this task can be complicated in cases of highly polygenic trait architecture implicating numerous small effect size loci, or when statistical tests are sensitive to the heterogeneity of some key characteristics of the genome, like recombination rate variations. After introducing these aforementioned challenges, we discuss a recent investigation of the genomic architecture and spatio-temporal variation in great tit bill length, which was related to the recent use of bird feeders. We discuss how this case study illustrates the importance of considering different temporal scales and evolutionary mechanisms both while analyzing trait temporal trends and when searching for and interpreting the signals of putative genomic footprints of selection. More generally this commentary discusses interesting challenges for unraveling the time scale at which adaptive traits evolve and their genomic bases.Impact summaryAn important goal in evolutionary biology is to understand how individual traits evolve, leading to fascinating variations in time and space. Long-term field studies have been crucial in trying to understand the timing, extent, and ecological determinants of such trait variation in wild populations. In this context, recent genomic tools can be used to look for the genetic bases underlying such trait variation and can provide clues on the nature and timing of their evolution. However, the analysis and the interpretation of the time scales at which evolution occurs remain challenging. First, analyzing long-term data series can be tricky; short-term changes are highly predictable whereas long-term evolution is much less predictable. A second difficult task is to study the architecture of complex quantitative traits and to decipher the timing and roles of the several genomic mechanisms involved in their evolution. This commentary introduces these challenges and discusses a recent investigation of the nature and timing of ecological and genomic factors responsible for variation in great tit bill length. Overall, we raise cautionary warnings regarding several conceptual and technical features and limitations when coupling analyses of long-term and genomic data to study trait evolution in wild populations.

Tests for phosphates from Rum Jungle, Northern Territory

1970 ◽  
Vol 10 (46) ◽  
pp. 592 ◽  
Author(s):  
MJ Fisher ◽  
MJT Norman
Keyword(s):  
Rock Phosphate ◽  
Field Experiments ◽  
Northern Territory ◽  
Residual Effects ◽  
Short Term ◽  
Christmas Island ◽  
Second Year ◽  
Term Response ◽  
Term Field

Phosphate-rich rock from Rum Jungle, N.T., was tested as fertilizer against Christmas Island rock phosphate dust (CIRPD) and superphosphate in two pot and three field experiments. The Rum Jungle material had little short-term value as fertilizer, but the long-term residual effects were about 60 per cent of those of CIRPD. Calcining at 450�C gave a marked improvement in short-term response in pots, but had little effect in a long-term field experiment. Pelletting the Rum Jungle material with sulphur and Thiobacillus ('biosuper') increased its effectiveness in the field at the end of the second year to the equivalent of that of superphosphate.

Influence of hematocrit ratio on survival of unacclimatized dogs at simulated high altitude

1963 ◽  
Vol 205 (6) ◽  
pp. 1172-1174 ◽  
Author(s):  
Elvin E. Smith ◽  
Jack W. Crowell
Keyword(s):  
High Altitude ◽  
Carrying Capacity ◽  
Simulated Altitude ◽  
High Altitudes ◽  
Survival Group ◽  
Closed Chamber ◽  
Atmospheric Air ◽  
Simulated High Altitude ◽  
Nitrogen Ratio ◽  
Oxygen Carrying Capacity

Eighty-six dogs were subjected to acutely induced, simulated high altitudes to determine the optimum hematocrit ratio for survival. High altitudes were simulated by diluting atmospheric air with nitrogen. Dogs with various hematocrit ratios were obtained by natural selection, hemorrhage, transfusion, and pretreatment with phenylhydrazine. Fifty-one dogs, in groups of 5–15, were placed in a closed chamber, and a 40,000-ft altitude was simulated by proper adjustment of the oxygen-to-nitrogen ratio. This altitude was maintained for a period of 6 hr. Most dogs with hematocrits less than 24 or greater than 66 died before the simulated altitude of 40,000 ft was attained; those with hematocrits of 24–30 survived from 1/2 to 5 hr. Some dogs with hematocrits of 30–65 survived the entire 7-hr period. However, no dogs with hematocrits from 37 to 54 died. The same procedures were repeated at a simulated altitude of 50,000 ft with a group of 38 dogs. The survival group was composed of dogs with hematocrits of 36–46. Dogs with hematocrits of 40–41 were conscious and active while those with hematocrits on either side of this value were comatose. These data indicate that the optimum hematocrit for survival of the unacclimatized dog at acutely induced high altitude is about 40. Deaths occurring on both sides of the optimum value may be explained by a simultaneous consideration of the curves depicting oxygen-carrying capacity of the blood, and blood viscosity, at all ranges of hematocrit.

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