scholarly journals Microscopic sperm head damage and abnormalities as heat stress indicators in Australian Merino rams (Ovis aries) in Northern Patagonia, Argentina

2018 ◽  
Vol 55 (1) ◽  
pp. 1
Author(s):  
María Fernanda López Armengol ◽  
Natalia Rubio ◽  
Guillermo Ariel Sabino ◽  
Nadia Soledad Bérgamo ◽  
Valeria Pelufo
Keyword(s):  
Heat Stress ◽  
Sperm Head ◽  
Ovis Aries ◽  
Stress Indicators ◽  
Northern Patagonia ◽  
Australian Merino

Na Patagônia Norte, os ovinos têm sua estação de acasalamento iniciada em 15 de março, portanto, ficam sujeitos às temperaturas do verão. A exposição de carneiros a estresse térmico aumenta a prevalência de danos microscópicos e anomalias morfológicas nos espermatozoides, que implica uma redução na fertilidade. Este trabalho avaliou a capacidade adaptativa de carneiros Merino Australiano com lã (N = 6) e tosquiados (N = 6): metade ficou ao ar livre e outra metade foi mantida em uma câmara climática por oito horas, durante cinco dias, chegando gradualmente a uma temperatura máxima de 40 °C. Foram analisados danos microscópicos, anormalidades e alterações ultramicroscópicas da membrana plasmática e do acrossoma da cabeça dos espermatozoides. Os resultados microscópicos confirmaram a existência de diferença significativa na porcentagem de espermatozoides sem cauda e com gota citoplasmática proximal, entre os ejaculados pós-tratamento. A temperatura afetou os carneiros tosquiados, principalmente a cabeça de seus espermatozoides, durante a espermatogênese. Alterações submicroscópicas foram observados na membrana plasmática quando ela estava presente no segmento anterior: quando não intacta, ficava ondulada ou dilatada. Quando a membrana plasmática estava ausente, o acrossoma podia se apresentar ondulado ou dilatado. Além disso, sob efeito do calor, a membrana acrossomal externa pode perder completamente seu conteúdo ou apresentar núcleo desnudo. A membrana plasmática assume uma forma ondulada pelo efeito da temperatura no epidídimo. Depois de dez semanas, a cabeça dos espermatozoides recuperou sua forma normal. Como demonstrado neste estudo, a cabeça sem cauda, as gotas citoplasmáticas proximais e as categorias ultramicroscópicas estudadas são indicadores do efeito do estresse térmico no sêmen, e os carneiros com maior cobertura de lã se adaptam melhor ao estresse por calor. Alterações de microscopia e de microscopia eletrônica de transmissão têm se mostrado excelentes indicadores de estresse por calor em carneiros Merino Australiano e podem ser ferramentas úteis para ajudar criadores de ovelhas a escolher quando começar a época de acasalamento, o que irá variar de acordo com as condições ambientais do verão.

Sperm head ellipticity as a heat stress indicator in Australian Merino rams (Ovis aries) in Northern Patagonia, Argentina

2015 ◽  
Vol 83 (4) ◽  
pp. 553-559.e2
Author(s):  
M.F. López Armengol ◽  
G.A. Sabino ◽  
J.C. Forquera ◽  
A. de la Casa ◽  
E.G. Aisen
Keyword(s):  
Heat Stress ◽  
Sperm Head ◽  
Ovis Aries ◽  
Stress Indicator ◽  
Northern Patagonia ◽  
Australian Merino

scholarly journals Effect of extreme severe heat stress on respiratory rate in unshorn and shorn Australian Merino rams from Northern Patagonia

2017 ◽  
Vol 54 (1) ◽  
pp. 36
Author(s):  
María Fernanda López Armengol ◽  
Ronina Paola Freund ◽  
Gustavo Néstor Giménez ◽  
Natalia Rubio
Keyword(s):  
Heat Stress ◽  
Respiratory Rate ◽  
Research Council ◽  
National Research Council ◽  
Northern Patagonia ◽  
Severe Heat Stress ◽  
E 32 ◽  
Australian Merino

O objetivo deste estudo foi determinar o efeito do estresse térmico extremamente severo sobre a frequência respiratória (ofego) em carneiros com lã e tosquiados, em pé ou deitados, e analisar dois índices de temperatura e umidade (ITU). Seis carneiros Merino Australiano da Patagônia Norte, três com lã e três tosquiados, foram expostos durante 40 horas a aumento gradual de temperatura de 25 a 40°C (oito horas durante cinco dias), garantindo quatro horas diárias a 40°C em uma câmara de calor. A frequência respiratória foi registrada continuamente mediante a contagem dos movimentos do flanco. A temperatura e a umidade relativa ambiente foram registradas a cada cinco minutos dentro da câmara. A partir de 1.413 frequências respiratórias registradas, uma análise descritiva foi realizada e um modelo calculado. A variável de resposta do ofego foi dividida em cinco categorias e os efeitos fixos considerados foram: ITU, lã (com lã ou tosquiado) e posição (em pé ou deitado). Não se observaram diferenças significativas nas frequências de ofego nos carneiros com lã (em pé ou deitados) nem entre os carneiros em pé (com lã e tosquiados), mas foram observadas diferenças significativas nos carneiros tosquiados deitados. Essas diferenças podem ser atribuídas à perda de calor com o solo, facilitada nos carneiros com mecha mais curta (pelo menos 1,8 cm), e à baixa produção de calor de atividade de músculo. Nos carneiros lanados, a lã atua como isolante tanto com o ar quanto com o solo. Os carneiros Merino Australianos do Norte da Patagônia foram adaptados a temperaturas ambiente entre 31,5 e 42°C e 32 e 48% de umidade durante 40 horas em cinco dias. Os carneiros permaneceram na primeira fase do ofego e as temperaturas retais diárias, que se registraram ao deixar a câmara de calor, permaneceram dentro da normalidade, o que demonstra que eles puderam regular a temperatura corporal. Além disso, foram analisados comparativamente os ajustes à frequência respiratória dos ITUs: LPHSI e National Research Council.

scholarly journals Performances of Limited Area Models for the WORKLIMATE Heat–Health Warning System to Protect Worker’s Health and Productivity in Italy

2021 ◽  
Vol 18 (18) ◽  
pp. 9940
Author(s):  
Daniele Grifoni ◽  
Alessandro Messeri ◽  
Alfonso Crisci ◽  
Michela Bonafede ◽  
Francesco Pasi ◽  
...  
Keyword(s):  
Heat Stress ◽  
Warning System ◽  
Outdoor Environment ◽  
Limited Area ◽  
Warning Systems ◽  
Stress Indicators ◽  
Climate Conditions ◽  
Health Warning ◽  
Globe Temperature ◽  
Meteorological Models

Outdoor workers are particularly exposed to climate conditions, and in particular, the increase of environmental temperature directly affects their health and productivity. For these reasons, in recent years, heat-health warning systems have been developed for workers generally using heat stress indicators obtained by the combination of meteorological parameters to describe the thermal stress induced by the outdoor environment on the human body. There are several studies on the verification of the parameters predicted by meteorological models, but very few relating to the validation of heat stress indicators. This study aims to verify the performance of two limited area models, with different spatial resolution, potentially applicable in the occupational heat health warning system developed within the WORKLIMATE project for the Italian territory. A comparison between the Wet Bulb Globe Temperature predicted by the models and that obtained by data from 28 weather stations was carried out over about three summer seasons in different daily time slots, using the most common skill of performance. The two meteorological models were overall comparable for much of the Italian explored territory, while major limits have emerged in areas with complex topography. This study demonstrated the applicability of limited area models in occupational heat health warning systems.

N6-methyladenosine modification modulate in the heat stress of sheep (Ovis aries)

2019 ◽  
Author(s):  
Zengkui Lu ◽  
Huihua Wang ◽  
Youji Ma ◽  
Mingxing Chu ◽  
Kai Quan ◽  
...  
Keyword(s):  
Heat Stress ◽  
Signaling Pathways ◽  
Stress Responses ◽  
Large Scale ◽  
Ovis Aries ◽  
Stop Codons ◽  
Coding Regions ◽  
Mrna Methylation ◽  
Response To Stress ◽  
And Control

Abstract Background: Intensive and large-scale development of the sheep industry and increases in global temperature are increasingly exposing sheep to heat stress. N6-methyladenosine (m6A) mRNA methylation varies in response to stress, and can link external stress with complex transcriptional and post-transcriptional processes. However, no m6A mRNA methylation map has been obtained for sheep, nor is it known what effect this has on regulating heat stress in sheep. Results: A total of 8,306 and 12,958 m6A peaks were detected in heat stress and control groups, respectively, with 2,697 and 5,494 genes associated with each. Peaks were mainly enriched in coding regions and near stop codons with classical RRACH motifs. Methylation levels of heat stress and control sheep were higher near stop codons, although methylation was significantly lower in heat stress sheep. GO revealed that differential m6A-containing genes were mainly enriched in the nucleus and were involved in several stress responses and substance metabolism processes. KEGG pathway analysis found that differential m6A-containing genes were significantly enriched in Rap1, FoxO, MAPK, and other signaling pathways of the stress response, and TGF-beta, AMPK, Wnt, and other signaling pathways involved in fat metabolism. These m6A-modified genes were moderately expressed in both heat stress and control sheep, and the enrichment of m6A modification was significantly negatively correlated with gene expression. Conclusions: Our results showed that m6A mRNA methylation modifications regulate heat stress in sheep, and it also provided a new way for the study of animal response to heat stress.

scholarly journals The role of N6-methyladenosine RNA methylation in the heat stress response of sheep (Ovis aries)

2019 ◽  
Vol 24 (2) ◽  
pp. 333-342 ◽  
Author(s):  
Zengkui Lu ◽  
Youji Ma ◽  
Qing Li ◽  
Enmin Liu ◽  
Meilin Jin ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Response ◽  
Ovis Aries ◽  
Heat Stress Response ◽  
Rna Methylation

scholarly journals Cell Membrane Stability and Relative Cell Injury in Response to Heat Stress during Early and Late Seedling Stages of Diverse Carrot (Daucus carota L.) Germplasm

HortScience ◽  
2020 ◽  
Vol 55 (9) ◽  
pp. 1446-1452 ◽  
Author(s):  
Aneela Nijabat ◽  
Adam Bolton ◽  
Muhammad Mahmood-ur-Rehman ◽  
Adeel Ijaz Shah ◽  
Rameez Hussain ◽  
...  
Keyword(s):  
Heat Stress ◽  
Cell Membrane ◽  
Heat Tolerance ◽  
Daucus Carota ◽  
Cell Injury ◽  
Membrane Stability ◽  
Seedling Stage ◽  
Stress Indicators ◽  
Cell Membrane Stability ◽  
Heat Tolerant

Heat waves occur with more regularity and they adversely affect the yield of cool season crops including carrot (Daucus carota L.). Heat stress influences various biochemical and physiological processes including cell membrane permeability. Ion leakage and increase in cell permeability are indicators of cell membrane stability and have been used to evaluate the stress tolerance response in numerous crops and inform plant breeders for improving heat tolerance. No study has been published about the effects of heat stress on cell membrane stability and relative cell injury of carrot. Therefore, the present study was designed to estimate these stress indicators in response to heat stress at the early and late seedling developmental stages of 215 diverse accessions of wild and cultivated carrot germplasm. The article identifies the relationship between early and late stages of seedling tolerance across carrot genotypes and identifies heat-tolerant genotypes for further genetic analysis. Significant genetic variation among these stress indicators was identified with cell membrane stability and relative cell injury ranging from 6.3% to 97.3% and 2.8% to 76.6% at the early seedling stage, respectively; whereas cell membrane stability and relative cell injury ranged from 2.0% to 94.0% and 2.5% to 78.5%, respectively, at the late seedling stage under heat stress. Broad-sense heritability ranged from 0.64 to 0.91 for traits of interest under study, which indicates a relatively strong contribution of genetic factors in phenotypic variation among accessions. Heat tolerance varied widely among both wild and cultivated accessions, but the incidence of tolerance was higher in cultivated carrots than in wild carrots. The cultivated carrot accessions PI 326009 (Uzbekistan), PI 451754 (Netherlands), L2450 (USA), and PI 502654 (Pakistan) were identified as the most heat-tolerant accessions with highest cell membrane stability. This is the first evaluation of cell membrane stability and relative cell injury in response to heat stress during carrot development.

Heat stress projections for major European cities from high-resolution regional climate model simulations

2021 ◽  
Author(s):  
Clemens Schwingshackl ◽  
Anne Sophie Daloz ◽  
Carley Iles ◽  
Nina Schuhen ◽  
Jana Sillmann
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Northern Europe ◽  
Stress Indicators ◽  
Model Simulations ◽  
European Cities ◽  
Climate Model Simulations

<p>Cities are hotspots of human heat stress due to their large number of inhabitants and the urban heat island effect leading to amplified temperatures. Exposure to heat stress in urban areas is projected to further increase in the future, mainly due to climate change and expected increases in the number of people living in cities. The impacts of climate change in cities have been investigated in numerous studies, but rarely using climate models due to their coarse spatial resolution compared to the typical areal extent of cities. Recent advances in regional climate modelling now give access to an ensemble of high-resolution simulations for Europe, allowing for much more detailed analyses of small-scale features, such as city climate.</p><p>Focusing on Europe, we compare the evolution of several heat stress indicators for 36 major European cities, based on regional climate model simulations from EURO-CORDEX. The applied EURO-CORDEX ensemble (Vautard et al., 2020) has a spatial resolution of 0.11° (~11 km; comparable to the extent of large cities) and contains over 60 ensemble members, allowing thus for robust multi-model analyses of climate change on city levels. We analyze changes in heat stress both relative to the climatological heat stress variability in each city during 1981-2010 using the Heat Wave Magnitude Index daily (HWMId, Russo et al., 2015) and in absolute terms by counting the yearly number of exceedances of impact-relevant thresholds. Relative and absolute heat stress increase throughout Europe but with distinct patterns. Absolute heat stress increases predominantly in Southern Europe, primarily due to the hotter climate in the South. Relative changes are also highest in Southern Europe but exhibit a secondary maximum in Northern Europe, while being lowest in Central Europe. The main reason for this pattern is that day-to-day variability in heat stress indicators during present climate conditions is highest in Central Europe but lower in Southern and Northern Europe. Large Northern European cities, which are all located at the shore, are further influenced by different heat stress evolutions over land and sea surfaces.</p><p>As human vulnerability does not only depend on the absolute heat stress but also on what people are adapted to (i.e., the climatological range), the results of this study highlight that cities in all parts of Europe – including in Northern Europe – must prepare for higher heat stress in the future.</p><p> </p><p>References:</p><p>Russo, S., et al. (2015). Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environmental Research Letters, 10(12). doi:10.1088/1748-9326/10/12/124003</p><p>Vautard, R., et al. (2020). Evaluation of the large EURO‐CORDEX regional climate model ensemble. Journal of Geophysical Research: Atmospheres. doi:10.1029/2019jd032344</p>

Multi-year prediction of drought and heat stress to support decision making in the wheat sector

2021 ◽  
Author(s):  
Balakrishnan Solaraju-Murali ◽  
Nube Gonzalez-Reviriego ◽  
Louis-Philippe Caron ◽  
Andrej Ceglar ◽  
Andrea Toreti ◽  
...  
Keyword(s):  
Heat Stress ◽  
Potential Evapotranspiration ◽  
Decision Makers ◽  
Stress Indicators ◽  
Potential Applicability ◽  
Community Earth System Model ◽  
Decadal Climate ◽  
Drought And Heat Stress ◽  
Climate Events ◽  
Support Decision Making

<p>Unfavorable and extreme climate events such as drought and heat stress affect wheat production and food security globally. Predicting such climate events in the next decade is of great interest for decision-makers, as this time horizon coincides with the strategic planning of many stakeholders in the wheat sector. To address this, we assess the forecast quality in predicting the evolution of drought and heat stress conditions using two proxy user-oriented drought and heat stress indicators: Standardized Potential Evapotranspiration Index (SPEI6) and Heat Magnitude Day Index (HMDI3) on a multi-annual timescale (forecast years 1 to 5). In particular, we present the probabilistic skill and reliability of decadal forecast to predict these indices for the months preceding wheat harvest on a global spatial scale. We use decadal forecasts from the Community Earth System Model Decadal Prediction Large Ensemble (CESM-DPLE), which contributes to the Decadal Climate Prediction Project (DCPP) of CMIP6. Following this, we demonstrate the potential applicability of these forecasts to enhance the adaptation and mitigation activities in the wheat sector by presenting the forecast of multi-year averaged SPEI6 and HMDI3 based on categorical events for the period 2016-2020 along with the corresponding observational values.</p>

Seasonal variation in sperm freezability associated with changes in testicular germinal epithelium in domestic (Ovis aries) and wild (Ovis musimon) sheep

2019 ◽  
Vol 31 (10) ◽  
pp. 1545 ◽  
Author(s):  
Lucía Martínez-Fresneda ◽  
Emma O'Brien ◽  
Rosario Velázquez ◽  
Adolfo Toledano-Díaz ◽  
Carlos M. Martínez-Cáceres ◽  
...  
Keyword(s):  
Seminiferous Tubule ◽  
Sperm Quality ◽  
Small Ruminants ◽  
Sperm Head ◽  
Ovis Aries ◽  
Germinal Epithelium ◽  
Nuclear Antigen ◽  
Proliferation Markers ◽  
Testosterone Levels ◽  
Head Area

The aim of this study was to examine ovine sperm cryoresistance during the rutting season (RS) and its association with sperm head area and seminiferous epithelium proliferation. Small ruminants show fluctuating testosterone levels throughout the year, which could interfere with spermatogenesis and sperm cryopreservation. Ejaculates, testicular biopsies and blood were collected during the middle and at the end of the RS (Middle-RS vs End-RS) during periods of high and low testosterone levels in Merino and Mouflon rams. Fresh and frozen–thawed sperm quality, sperm morphometry, seminiferous tubule morphometry and testicular proliferation markers (proliferating cell nuclear antigen, proliferation marker protein Ki-67 and transcription factor GATA-4) were evaluated. Post-thaw sperm viability was higher in the End-RS group in both Merino (69.9±8.2 vs 41.6±7.3%; P=0.020) and Mouflon rams (40.9±3.3 vs 24.2±5.0%; P=0.008). Mouflons had larger sperm head area at the End-RS (38.3±0.2 vs 34.3±0.1µm2; P=0.029), whereas there was no difference between Merino groups (35.7±0.5 vs 34.8±1.0µm2). Seminiferous tubule morphometry and proliferation markers showed higher levels of germinal epithelium proliferation in the Middle-RS of both species. In conclusion, sperm freezability is affected during the RS in domestic and wild rams, which could be correlated with changes that occur during spermatogenesis, since there is an effect of season on cell proliferation in the testis.

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