Mechanistic understanding of heat stress in cattle reproduction toward pharmacological strategies.

Small ruminant farming plays a pivotal role in agriculture, especially in developing countries due to sheep's diverse functions and capacity to acclimate to varying temperatures. This review comprehensively explored the impact of rising temperatures on reproductive processes, reproductive function encoding gene expression, and sheep's ability to adapt to heat stress. Several mechanisms contribute to sheep's resilience to heat stress, encompassing morphological, behavioral, physiological, and genetic adaptations. It has been shown that heat stress compromises fertility by affecting follicular development, ovulation rate, estrous behavior, rates of conception, embryonic survival, and fetal development, while also disrupting sperm production and motility, and increasing the incidence of structurally abnormal sperm in males. Estimates suggested that heat stress may reduce conception rates from 20% to 27%. Essential genes encoding the Gonadotrophin-releasing hormone, Follicle-stimulating hormone receptor, Luteinizing hormone receptor, Estradiol receptor, progesterone receptor, and Inhibin play a critical role in elucidating how heat stress impacts the reproductive performance of sheep. Furthermore, the resilience of sheep in facing heat stress adversities is associated with a specific heat shock factor. When an animal is under heat stress, Heat shock factors get activated and stimulate the production of Heat Shock Proteins (HSPs). Emphasis should be given to identifying specific genes and candidate genes that confer protection against heat stress and conducting comprehensive research to unravel how sheep adapt to demanding local climatic conditions to enhance production and profitability, improve animal welfare, and for genetic conservation and breeding programs.

BackgroundWater spinach (Ipomoea aquatica) is an important heat-resistant leafy vegetable that can survive under long-time heat stress condition. However, the physiological characteristics and molecular changes in its response to heat stress are poorly understood.ResultsIn this study the selected water spinach cultivars with different thermo resistance and their physiological response to heat stress were examined. Under prolonged heat stress, plant growth was inhibited in all tested cultivars. This inhibition was accompanied by the reduction of photosynthetic performance. The reactive oxygen species system in terms of superoxide and hydrogen peroxide contents, as well as antioxidant polyphenols, were evaluated. The results showed that prolonged heat stress caused reduced antioxidant capacity, but the role of antioxidant capacity in a prolonged thermotolerance was not predominant. Transcriptomic analysis of the water spinach subjected to heat stress revealed that 4145 transcripts were specifically expressed with 2420 up-regulated and 1725 down-regulated in heat-sensitive and heat-tolerant cultivars treated with 42 °C for 15 days. Enrichment analysis of these differentially expressed genes showed that the main metabolic differences between heat-sensitive and heat-tolerant cultivars were the carbohydrate metabolism and phenylpropanoid biosynthesis. The results of carbohydrate profiles and RT-qPCR also suggested that heat stress altered carbohydrate metabolism and associated changes in transcriptional level of genes involved in sugar transport and metabolic transition.ConclusionsThe prolonged heat stress resulted in a reduced antioxidant capacity while the role of antioxidant capacity in a prolonged thermotolerance of water spinach was not predominant. Transcriptome analysis and the measurement of carbohydrates as well as the gene expression evaluation indicated that the response of the metabolic pathway such as carbohydrate and phenylpropanoid biosynthesis to heat stress may be a key player in thermo resistance.

Summer decline is typically characterized by heat and drought stress and is a major concern for fine fescue species (Festuca). The objectives of this study were to examine whether heat or drought stress is more detrimental, and to determine the genotypic variations in heat and drought tolerance for fine fescues. A total of 26 cultivars, including seven hard fescues (Festuca trachyphylla), eight chewings fescues (Festuca rubra ssp. commutate), seven strong creeping red fescues (Festuca rubra ssp. rubra), two sheep fescues (Festuca ovina ssp. hirtula), and two slender creeping red fescues (Festuca rubra ssp. littoralis) were subjected to prolonged heat or drought stress in growth chambers. Several physiological parameters, including turf quality (TQ), electrolyte leakage (EL), photochemical efficiency (Fv/Fm) chlorophyll content (Chl), and relative water content (RWC) were measured in plants exposed to heat or drought stress. The results indicated that heat stress was more detrimental than drought stress for fine fescue species. Based on TQ and major physiological parameters (EL and Fv/Fm) under heat stress, several cultivars with good heat tolerance were selected, including ‘Blue Ray’, ‘Spartan II’, ‘MN-HD1’, ‘Shoreline’, ‘Navigator II’, ‘Azure’, ‘Beacon’, ‘Aurora Gold’, ‘Reliant IV’, ‘Marco Polo’, ‘Garnet’, ‘Wendy Jean’, ‘Razor’, and ‘Cindy Lou’. Based on TQ and major physiological parameters (EL, RWC, and Fv/Fm) under drought stress, several cultivars with good drought tolerance were selected, including ‘Spartan II’, ‘MN-HD1’, ‘Reliant IV’, ‘Garnet’, ‘Azure’, and ‘Aurora Gold’. These cultivars could be used in hot, dry, or both environments and as breeding germplasm for developing heat tolerance, drought tolerance, or both.

Heat shock protein 90 and prolyl hydroxylase 2 co-regulate hypoxia-inducible factor-1α expression in porcine small intestinal epithelial cells under heat stress

Heat stress caused rapid and severe inhibition of photosynthesis and nitrate reduction in nitrate-supplemented cultures of the cyanobacterium Anabaena sp. strain L-31, compared to nitrogen-fixing cultures. Anabaena strains harbour two hsp60 family genes, groEL and cpn60, respectively encoding the 59 kDa GroEL and 61 kDa Cpn60 chaperonin proteins. Of these two Hsp60 chaperonins, GroEL was strongly induced during heat stress, irrespective of the nitrogen status of the cultures, but Cpn60 was rapidly repressed and degraded in heat-stressed nitrate or ammonium-supplemented cultures. The recovery of photosynthesis, nitrate assimilation and growth in heat-stressed, nitrate-supplemented cultures were preceded by resynthesis and restoration of cellular Cpn60 levels. Glutamine synthetase activity, although adversely affected by prolonged heat stress, was not dependent on either the nitrogen status or Cpn60 levels during heat stress. Overexpression of the Cpn60 protein in the closely related Anabaena sp. strain PCC7120 conferred significant protection from heat stress to growth, photosynthesis and nitrate reduction in the recombinant strain. The data favour a role for Cpn60 in carbon and nitrogen assimilation in Anabaena.

Effects of short-term in vitro heat stress on bovine preantral follicles

The objective of the present study was to characterize cattle husbandry practices, production and reproductive performance of cattle in the urban and peri-urban areas of Gambella city. Sample of respondents from each selected kebele were selected randomly using simple random sampling technique. A total of 133 household (70 from urban and 63 from peri-urban) were selected for questionnaire interview. Data was analyzed using SPPS version 23 software. The overall mean of the respondents revealed that, the management system practiced was semi-intensive (87.2%), extensive system (12.8%) and there was no intensive management system practiced. the overall mean daily milk yield was 1.58± 0.017 Littre/cow/day. The overall mean daily milk yield analysis of variance was significantly (P<0.05) difference among urban and peri-urban areas. The current result also indicated that, the overall average lactation length was and 10.59± 0.15 months, and was not significantly (P>0.05) affected by the study areas. The overall average age at first services, age at first calving and calving interval was 46.31±0.33, 51.51±0.54, and 19.01±0.11 months respectively. In Addition, disease prevalence, poor animal health service delivery, grazing land and feed shortage were among the major constraints affecting production and productivity in the study areas. In conclusion, Age at first services, age at first calving and calving interval of indigenous cow was low compared to some of the indigenous breed in other regions, animal health and health services delivery are the problems affecting cattle productivity. Hence, all concerned stakeholders need to take urgent interventions in order to improve production and productivity of cattle.

Kulon Progo is an area that has mountainous areas and plays a role in achieving the target of meat self-sufficiency in the Special Region of Yogyakarta Province (DIY). This research aims to determine the influence of cattle breeds on the reproductive performance of beef cattle as an indicator for improving genetic quality and livestock productivity in achieving these targets. The choice of cattle breeds as research subjects is because cattle breeds are one of the factors that influence the efficiency of cattle reproductive performance. This research used a sample of 47 heads to look at Days Open, Estrus Post Partum, and Calving Interval, and 65 heads aimed to look at CR and Service/Conception of beef cattle in the mountainous area of Kulon Progo, DIY. The research used a survey method by collecting primary data obtained from interviews guided by questionnaires and through anamnesis. The results of this study showed that the average DO was 142.27 days and 152.14 days respectively and the average CI for PO and SimPO cattle was 503.18 and 498.21 days respectively, for the CR rate in PO cattle was 34.09% and SimPO cattle 23.80% and the S/C value for PO cattle was 2.16 times and SimPO 2.43 times. Based on the data, it can be concluded that the reproductive performance of cattle seen from beef cattle breeds in mountainous areas does not show a significant influence.

Providing balanced nutrients is critical for maintaining cow fertility. Adequate trace mineral intake and absorption is required for proper functioning of many metabolic processes associated with reproduction. Reproductive performance of cattle may be compromised if zinc, copper, or manganese status is in the marginal-to-deficient range. Common copper deficiency symptoms in cattle include delayed or suppressed estrus, decreased conception, infertility and embryo death. Inadequate zinc levels have been associated with decreased fertility, abnormal estrus, abortion and altered myometrial contractibility with prolonged labor. Manganese deficiency in cows results in suppression of conception rates, delayed estrus in both post-partum females and young prepuberal heifers, infertility, abortion, immature ovaries and dystocia. This study evaluated the effect on reproduction from feeding complex trace to beef cattle.

Abstract. Anthropogenic climate change, combined with specific modifications of the urban climate, is expected to lead to an increase in the intensity, duration, and frequency of heat waves in urban areas. Prolonged heat stress - as expected due to these changes - has serious health consequences for vulnerable urban population groups. This study examines the effects of heat stress on the accessibility of essential services in Heidelberg, Germany. The concept of isochrones was extended to include heat stress factors and applied to the study area, the city of Heidelberg in Germany. The analysis was based on a heat-sensitive routing approach that uses OpenStreetMap data together with a digital surface model that was used to model solar exposure. Results showed that under moderate heat stress conditions, accessibility to essential services (transportation, healthcare, retail and social services) was largely maintained, while under high heat stress conditions, a significant portion of the population was excluded from these services. Differences in the affected population can be identified according to both administrative territorial units and building structures. The results provide relevant information for urban planning as they indicate where city inhabitants will face problems to access essential services under heat spells.

High environmental temperatures during the hot months of the year reduce reproductive performance in cattle. Summer heat stress depression in fertility is a multifactorial problem; however, there is evidence that the bovine germinal vesicle and maturing oocyte, as well as the early embryo, are major targets of the deleterious effects of heat stress. Such adverse effects are less pronounced in heat-tolerant breeds (Bos indicus) than heat-sensitive breeds (Bos taurus). This genetic variation results from the greater thermoregulatory ability and cellular thermoresistance of heat-tolerant breeds. Heat-induced oocyte cellular damage occurs in both cytoplasmic and nuclear compartments. Heat shock has been shown to reduce oocyte nuclear maturation, induce apoptosis, compromise oocyte cytoskeleton, and impair oocyte mitochondrial function and developmental competence. However, the oocyte cytoplasm is more susceptible to heat shock than the nucleus. This effect is greater for Bos taurus than Bos indicus oocytes. The detrimental effects of heat shock are also critical during the first cleavage divisions when most of the embryonic genome is inactive; however, the bovine embryo becomes more resistant to increased temperature as it proceeds through development. Several studies demonstrated that Bos indicus embryos are more thermotolerant than Bos taurus embryos. Adaptive changes involved in acquisition of thermotolerance are likely derived from changes in gene expression and (or) activity of biochemical molecules that control cellular functions against stress. Recently, molecules such as IGF-I and caspase inhibitor z-DEVD-fmk have been shown to exert a thermoprotective role, rescuing heat-induced oocyte and embryo cellular damage and developmental competence. Therefore, cattle genotype and thermoprotective molecules can be considered as an alternative to modulate the effects of increased temperature in reproductive function.

A group of proteins called heat shock proteins (HSPs) are synthesized during heat stress. They are expressed at high levels when exposed to stress. Polymorphism in HSPs has been reported to be associated with heat tolerance and reproductive performance in cattle. The present study aimed to investigate the polymorphisms in the coding region of the HSPA1A gene in Holstein-Friesian (HF) crossbreds and the Deoni breed of cattle. Genomic DNA was extracted from 94 animal blood samples and was subjected to polymerase chain reaction-single strand conformation polymorphism analysis, which revealed 14 band patterns in Deoni cattle and 8 band patterns in HF crossbreds. Sequence data were analyzed using BioEdit software for detecting single nucleotide polymorphisms. Sequence analysis showed 12 single nucleotide polymorphisms in the coding region of the HSPA1A gene, which included 5 transitions (G456A, A972G, A1098G, C1766T, and G1788A) and 2 transversions (C312G and G2033C) in Deoni cattle and 2 indels (C at positions 574?575 and 624?625), 2 transitions (A480G and A1098G), and 1 transversion (C312G) in HF crossbred cattle. The study indicated a high degree of genetic variability in the HSPA1A gene in the cattle populations under study.

Heat stress seriously threatens the growth of Pleurotus ostreatus. Various studies have been performed to study the resistance of P. ostreatus to heat stress. Here, the metabolome was evaluated to determine the response of P. ostreatus mycelia to heat stress at different times (6, 12, 24, 48 h). More than 70 differential metabolites were detected and enriched in their metabolic pathways. Dynamic metabolites changes in enrichment pathways under heat stress showed that heat stress enhanced the degradation of unsaturated fatty acids and nucleotides, increased the content of amino acids and vitamins, and accelerated glycolysis and the tricarboxylic acid cycle in P. ostreatus. The time course changes of P. ostreatus metabolites under continuous heat stress demonstrated that amino acids continuously changed with heat stress, nucleotides clearly changed with heat stress at 12 and 48 h, and lipids exhibited an increasing trend with prolonged heat stress, while few types saccharides and vitamins changed under heat stress. Additionally, heat-treated P. ostreatus produced salicylic acid and other stress-resistant substances that were reported in plants. This study first reported the metabolites changes in P. ostreatus mycelia during 48 h of heat stress. The metabolic pathways and substances that changed with heat stress in this research will aid future studies on the resistance of P. ostreatus and other edible fungi to heat stress.

Humans are occasionally exposed to extreme environmental heat for a prolonged period of time. Here, we investigated testicular responses to whole-body heat exposure by placing mice in a warm chamber. Among the examined tissues, the testis was found to be most susceptible to heat stress. Heat stress induces direct responses within germ cells, such as eukaryotic initiation factor 2αphosphorylation and stress granule (SG) formation. Prolonged heat stress (42°C for 6 hr) also disturbed tissue organization, such as through blood-testis barrier (BTB) leakage. Germ cell apoptosis was induced by heat stress for 6 hr in a cell type- and developmental stage-specific manner. We previously showed that spermatocytes in the early tubular stages (I-VI) form SGs for protection against heat stress. In the mid-tubular stages (VII-VIII), BTB leakage synergistically enhances the adverse effects of heat stress on pachytene spermatocyte apoptosis. In the late tubular stages (IX-XII), SGs are not formed and severe leakage of the BTB does not occur, resulting in mild apoptosis of late-pachytene spermatocytes near meiosis. Our results revealed that multiple stress responses are involved in germ cell damage resulting from prolonged heat stress (42°C for 6 hr).

Dietary selenium levels modulates antioxidant, cytokine and immune response and selenoproteins mRNA expression in rats under heat stress condition