Canadian Journal of Zoology, Ahead of Print.
To understand the response of freshwater organisms to rising environmental salinity, it is essential to investigate their osmo-ionic regulatory physiology. Our laboratory experiment investigated the transfer of Palaemon argentinus (Nobili, 1901) from 2‰ (control condition) to concentrated salinity (15 and 25‰) for short- (6 h), medium- (48 h), and long-term (>504 h) acclimation periods. We measured relevant parameters in the shrimp’s haemolymph, the time course of the response of branchial V–H+–ATPase (VHA), Na+, K+–ATPase (NKA), carbonic anhydrase (CA) activity, and muscle water content. Upon prolonged acclimation to 15‰ (hyper-regulating condition), shrimp reached a new steady state of haemolymph osmolality by tightly adjusting ion concentrations to levels higher than the external medium. While NKA and CA activities recovered their pre-transfer levels, the downregulation of VHA suggests other functions rather than ion uptake after prolonged acclimation to 15‰. The activity of the three transport-related enzymes remained almost unchanged at the highest salinity (isosmotic condition), leading to increasing osmotic pressure and ion concentration after prolonged acclimation to 25‰. Although the freshwater shrimp studied here retains a certain degree of tolerance to high salinity, a common trait in palaemonid shrimps, our results highlight that 25‰ represents a significant hypertonic challenge for this species.
Assessment of relationships between bullous pemphigoid and neurological diseases: A bidirectional two‐sample Mendelian randomization study
Abstract
Bullous pemphigoid (BP) is the most prevalent autoimmune vesiculobullous skin illness that tends to affect the elderly. Growing evidence has hinted a correlation between BP and neurological diseases. However, existing observational studies contained inconsistent results, and the causality and direction of their relationship remain poorly understood. To assess the causal relationship between BP and neurological disorders, including Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and stroke. A bidirectional two-sample Mendelian randomization (MR) adopted independent top genetic variants as instruments from the largest accessible genome-wide association studies (GWASs), with BP (n = 218 348), PD (n = 482 730), AD (n = 63 926), stroke (n = 446 696), and MS (n = 115 803). Inverse variance weighted (IVW), MR-Egger, weighted mode methods, weighted median, and simple mode were performed to explore the causal association. Multiple sensitivity analyses, MR-Pleiotropy Residual Sum and Outlier (PRESSO) was used to evaluate horizontal pleiotropy and remove outliers. With close-to-zero effect estimates, no causal impact of BP on the risk of the four neurological diseases was discovered. However, we found that MS was positively correlated with higher odds of BP (OR = 1.220, 95% CI: 1.058–1.408, p = 0.006), while no causal associations were observed between PD (OR = 0.821, 95% CI: 0.616–1.093, p = 0.176), AD (OR = 1.066, 95% CI: 0.873–1.358, p = 0.603), stroke (OR = 0.911, 95% CI: 0.485–1.713, p = 0.773) and odds of BP. In summary, no causal impact of BP on the risk of PD, AD, MS and stroke was detected in our MR analysis. However, reverse MR analysis identified that only MS was positively correlated with higher odds of BP, but not PD, AD and stroke.
Differences between thermal preference and thermal performance in a wintry spider Mecicobothrium thorelli: are the spiders under evolutionary pressures on their seasonal activity?
Canadian Journal of Zoology, Ahead of Print.
Thermal preference and thermal performance are used to describe the thermal biology of an ectothermic organism through parameters, i.e., estimating locomotor performance by maximum running speed. In this study, we assessed the thermal preference and locomotor performance of the spider Mecicobothrium thorelli Holmberg, 1882, a wintry mygalomorph spider endemic to the native mountainous grasslands of central Argentina and Uruguay. The preferred temperatures of the 72.4% of the individuals were in the range of 10–20 °C. The highest frequencies of preferred temperatures were 10–15 °C in males and 15–20 °C in females. The sprint speed showed significant differences between all the temperatures evaluated and showed the highest speeds at 25 °C and the lowest at 3 °C. The optimal temperature was 26.09 °C, which was significantly higher than the preferred temperature in both males and females. We concluded that M. thorelli selects a wide range of temperatures and prefers to stay in medium and low temperatures, which are correlated with winter activity in the wild. However, the species showed maximum speed at higher temperatures, which implies that spiders would perform even better in nature and maximize their locomotion by being active during a warmer period.
Thermal preference and thermal performance are used to describe the thermal biology of an ectothermic organism through parameters, i.e., estimating locomotor performance by maximum running speed. In this study, we assessed the thermal preference and locomotor performance of the spider Mecicobothrium thorelli Holmberg, 1882, a wintry mygalomorph spider endemic to the native mountainous grasslands of central Argentina and Uruguay. The preferred temperatures of the 72.4% of the individuals were in the range of 10–20 °C. The highest frequencies of preferred temperatures were 10–15 °C in males and 15–20 °C in females. The sprint speed showed significant differences between all the temperatures evaluated and showed the highest speeds at 25 °C and the lowest at 3 °C. The optimal temperature was 26.09 °C, which was significantly higher than the preferred temperature in both males and females. We concluded that M. thorelli selects a wide range of temperatures and prefers to stay in medium and low temperatures, which are correlated with winter activity in the wild. However, the species showed maximum speed at higher temperatures, which implies that spiders would perform even better in nature and maximize their locomotion by being active during a warmer period.
Ovarian activity, hormone profile, pro‐inflammatory cytokines and reproductive performance of buffalo cows fed diets with different estrogenicity
Abstract
Buffalo cows play a vital role in milk and meat production; however, they are characterised by several reproductive disorders. Feeding diets with high oestrogenic activity may be a disrupting factor. This study aimed to evaluate the effects of feeding roughages with different oestrogenic activity on the reproductive performance of early postpartum buffalo cows. A total of 30 buffalo cows were equally stratified into two experimental groups and fed either Trifolium alexandrinum (Berseem clover, phytoestrogenic roughage) or corn silage (nonoestrogenic roughage) for 90 consecutive days. After 35 days from the beginning of the feeding treatments, buffalo cows in both groups were synchronized for oestrus using a double i.m. injection of 2 mL prostaglandin F2α, 11 days apart, subsequently, overt signs of oestrus were observed and recorded. Moreover, ovarian structures, numbers and sizes of follicles and corpora lutea, were ultrasonography examined at day—12 (represents Day 35 of feeding treatment), Day 0 (day of oestrus) and Day 11 after oestrous synchronization (mid-luteal phase). Pregnancy was diagnosed 35 days postinsemination. Blood serum samples were analysed for progesterone (P4), estradiol (E2), tumor necrosis factor (TNF-α), interlukein-1β (IL-1β) and nitric oxide (NO). The high performance liquid chromatography-analysis of roughages showed the abundance of isoflavones in Berseem clover, with about 58 times higher concentration than that in corn silage group. During the experimental period, the numbers of ovarian follicles of all size categories were higher in the Berseem clover group than that in the corn silage group. No significant difference in the numbers of corpora lutea was observed between both experimental groups, but lower (p < 0.05) diameter of corpus luteum was observed in the Berseem clover group than that in the corn silage group. The Berseem clover group had higher (p < 0.05) overall concentrations of blood serum E2, IL-1β and TNF-α, but lower (p < 0.05) overall concentrations of blood serum P4 than those recorded in the corn silage group. Oestrous rate, onset of oestrus time and oestrous duration were not significantly affected by the treatment. The conception rate was significantly (p < 0.05) reduced in the Berseem clover group compared with that in the corn silage group. In conclusion, feeding roughage with a high oestrogenic activity such as Berseem clover can negatively affect the conception rate of buffalo cows. This reproductive loss seems to be associated with inadequate luteal function and P4 concentration during early pregnancy.
Energetic costs of testosterone in two subsistence populations
Abstract
Objective
Testosterone plays a role in mediating energetic trade-offs between growth, maintenance, and reproduction. Investments in a high testosterone phenotype trade-off against other functions, particularly survival-enhancing immune function and cellular repair; thus only individuals in good condition can maintain both a high testosterone phenotype and somatic maintenance. While these effects are observed in experimental manipulations, they are difficult to demonstrate in free-living animals, particularly in humans. We hypothesize that individuals with higher testosterone will have higher energetic expenditures than those with lower testosterone.
Methods
Total energetic expenditure (TEE) was quantified using doubly labeled water in n = 40 Tsimane forager-horticulturalists (50% male, 18–87 years) and n = 11 Hadza hunter-gatherers (100% male, 18–65 years), two populations living subsistence lifestyles, high levels of physical activity, and high infectious burden. Urinary testosterone, TEE, body composition, and physical activity were measured to assess potential physical and behavioral costs associated with a high testosterone phenotype.
Results
Endogenous male testosterone was significantly associated with energetic expenditure, controlling for fat free mass; a one standard deviation increase in testosterone is associated with the expenditure of an additional 96–240 calories per day.
Discussion
These results suggest that a high testosterone phenotype, while beneficial for male reproduction, is also energetically expensive and likely only possible to maintain in healthy males in robust condition.
Boron foliar supplementation as a strategy to attenuate drought stress in soybean
Extra boron alleviates the effects of drought stress in soybean.
Abstract
Drought is the major abiotic stress that limits growth, development and yield of crops worldwide. In this scenario, mineral nutrients, such as boron (B), have been promising for increasing the tolerance of plants to abiotic stresses because of their physiological roles in plants. We aimed to evaluate the benefits of foliar supplementation of B in either relieving or reducing the physiological damages caused by water stress in soybean (Glycine max L.). A greenhouse trial was carried out in a 2 × 3 factorial scheme, with two water conditions (well-watered and drought stress) and three doses of B (0, 150 and 300 mg B L−1). Foliar application of B was before inducing the water stress, which remained for 20 days during vegetative stage. Plants were evaluated at three moments, according to the water conditions: maximum stress, rehydration and just before harvesting. The levels of hydrogen peroxide and lipid peroxidation increased in soybean leaves and roots under water stress, resulting in impaired plant growth. However, the foliar supplementation with B before the stress increased activities of the antioxidant enzymes and reduced the levels of stress markers. Furthermore, B applied foliar increased the nutrient concentration in the leaves of plants and stimulated root growth, which resulted in higher harvest index related to yield. The foliar application of B has shown as an alternative management to mitigate the damages caused by drought stress in soybean.
Human milk immune factors, maternal nutritional status, and infant sex: The INSPIRE study
Abstract
Objectives
Breastfeeding is an energetically costly and intense form of human parental investment, providing sole-source nutrition in early infancy and bioactive components, including immune factors. Given the energetic cost of lactation, milk factors may be subject to tradeoffs, and variation in concentrations have been explored utilizing the Trivers-Willard hypothesis. As human milk immune factors are critical to developing immune system and protect infants against pathogens, we tested whether concentrations of milk immune factors (IgA, IgM, IgG, EGF, TGFβ2, and IL-10) vary in response to infant sex and maternal condition (proxied by maternal diet diversity [DD] and body mass index [BMI]) as posited in the Trivers-Willard hypothesis and consider the application of the hypothesis to milk composition.
Methods
We analyzed concentrations of immune factors in 358 milk samples collected from women residing in 10 international sites using linear mixed-effects models to test for an interaction between maternal condition, including population as a random effect and infant age and maternal age as fixed effects.
Results
IgG concentrations were significantly lower in milk produced by women consuming diets with low diversity with male infants than those with female infants. No other significant associations were identified.
Conclusions
IgG concentrations were related to infant sex and maternal diet diversity, providing minimal support for the hypothesis. Given the lack of associations across other select immune factors, results suggest that the Trivers-Willard hypothesis may not be broadly applied to human milk immune factors as a measure of maternal investment, which are likely buffered against perturbations in maternal condition.
Assessment of family-derived metabolic traits for the conservation of an ancient fish
Canadian Journal of Zoology, Ahead of Print.
Physiological and behavioral traits of aquatic organisms are often highly dependent on environmental conditions, but genetic (family) effects often contribute to phenotypic variation. In this study, a series of physiological indices were used to assess the variability that exists among progeny of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) produced from eight different families. We designed a controlled experiment aimed to evaluate metabolic performance of age-0 lake sturgeon where growth, energy density, survival, metabolic rate, volitional swimming performance, and critical thermal maxima were quantified for fish reared under the same environmental conditions. We found a strong family effect for most metrics that were quantified and primarily influenced by the female. Furthermore, poor growth and survival within families were strongly correlated to low energy density levels and depressed routine metabolic rates at the yolk sac stage. Lastly, the quantification of energy density at the onset of exogenous feeding appeared to be an excellent predictor of future growth and survival. Our results suggest that the choice of female for production of progeny in conservation hatcheries will have significant impacts on the success of stock enhancement as a conservation strategy for lake sturgeon.
Physiological and behavioral traits of aquatic organisms are often highly dependent on environmental conditions, but genetic (family) effects often contribute to phenotypic variation. In this study, a series of physiological indices were used to assess the variability that exists among progeny of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) produced from eight different families. We designed a controlled experiment aimed to evaluate metabolic performance of age-0 lake sturgeon where growth, energy density, survival, metabolic rate, volitional swimming performance, and critical thermal maxima were quantified for fish reared under the same environmental conditions. We found a strong family effect for most metrics that were quantified and primarily influenced by the female. Furthermore, poor growth and survival within families were strongly correlated to low energy density levels and depressed routine metabolic rates at the yolk sac stage. Lastly, the quantification of energy density at the onset of exogenous feeding appeared to be an excellent predictor of future growth and survival. Our results suggest that the choice of female for production of progeny in conservation hatcheries will have significant impacts on the success of stock enhancement as a conservation strategy for lake sturgeon.
Metabolic and transcriptomic response of two juvenile anadromous brook charr (Salvelinus fontinalis) genetic lines towards a chronic thermal stress
Canadian Journal of Zoology, Ahead of Print.
Many salmonid species are particularly susceptible to chronic and acute temperature changes caused by global warming. We aimed to study the differences in metabolic and transcriptomic responses of a chronic heat stress on a control and selected (absence of early sexual maturation and growth) line of brook charr Salvelinus fontinalis (Mitchill, 1814). We exposed individuals to different temperatures for 35 days (15, 17, and 19 °C). High temperature reduced the growth rate (in length) and the Fulton condition factor. Both maximal metabolic rate and the aerobic scope were higher in fish reared at 17 °C, while they decreased in fish maintained at 19 °C. The relative gene expression of cytochrome c oxidase was lower at 19 °C than at 15 °C. The relative gene expressions of both liver and gill hsp90 was higher at the highest temperature. The standard metabolic rate, while not affected by temperature, was higher for the control line over the selected line. Only in the control line, the relative expression of catalase and of receptor of insulin-like growth factor-1 increased at 19 °C. Our results showed that the selected line was able to cope more effectively with the oxidative stress caused by the rise in temperature.
Many salmonid species are particularly susceptible to chronic and acute temperature changes caused by global warming. We aimed to study the differences in metabolic and transcriptomic responses of a chronic heat stress on a control and selected (absence of early sexual maturation and growth) line of brook charr Salvelinus fontinalis (Mitchill, 1814). We exposed individuals to different temperatures for 35 days (15, 17, and 19 °C). High temperature reduced the growth rate (in length) and the Fulton condition factor. Both maximal metabolic rate and the aerobic scope were higher in fish reared at 17 °C, while they decreased in fish maintained at 19 °C. The relative gene expression of cytochrome c oxidase was lower at 19 °C than at 15 °C. The relative gene expressions of both liver and gill hsp90 was higher at the highest temperature. The standard metabolic rate, while not affected by temperature, was higher for the control line over the selected line. Only in the control line, the relative expression of catalase and of receptor of insulin-like growth factor-1 increased at 19 °C. Our results showed that the selected line was able to cope more effectively with the oxidative stress caused by the rise in temperature.
Comparison of behavioural and transcriptional responses to a heat stressor between freshly collected and an inbred strain of Lymnaea
Canadian Journal of Zoology, Volume 101, Issue 10, Page 904-912, October 2023.
Different populations of organisms occurring across varying thermal regimes show diversity in responses to heat stress. We use a “common garden experimental” approach designed to deal with phenotypic plasticity to study in Lymnaea stagnalis (Linnaeus, 1758) the behavioural and molecular responses to a heat shock in laboratory-inbred snails (W-strain) and freshly collected snails (Stony strain) from ponds. In the W-strain, which has been reared under standardized temperatures for generations, the exposure to 30 °C for 1 h (heat shock, HS) when experienced after a novel “taste” results in a taste-specific aversion known as the “Garcia effect”. This learned avoidance requires the upregulation of heat shock proteins (HSPs). In contrast, freshly collected Stony strain, which experiences temperature fluctuations regularly, does not exhibit a Garcia effect. Here, we found that (1) Stony-strain snails have higher basal mRNA levels of HSPs than W-strain ones; (2) in the W-strain, the training procedure to cause the Garcia effect upregulates the mRNA levels of HSPs and key neuroplasticity-related genes such as CREB1 and GRIN1; (3) in Stony-strain snails, the same training procedure fails to alter the mRNA levels of those targets. These data suggest that Stony-strain snails do not perceive the HS as a stressor because of the higher HSP basal mRNA levels, which may confer a higher thermal tolerance.
Different populations of organisms occurring across varying thermal regimes show diversity in responses to heat stress. We use a “common garden experimental” approach designed to deal with phenotypic plasticity to study in Lymnaea stagnalis (Linnaeus, 1758) the behavioural and molecular responses to a heat shock in laboratory-inbred snails (W-strain) and freshly collected snails (Stony strain) from ponds. In the W-strain, which has been reared under standardized temperatures for generations, the exposure to 30 °C for 1 h (heat shock, HS) when experienced after a novel “taste” results in a taste-specific aversion known as the “Garcia effect”. This learned avoidance requires the upregulation of heat shock proteins (HSPs). In contrast, freshly collected Stony strain, which experiences temperature fluctuations regularly, does not exhibit a Garcia effect. Here, we found that (1) Stony-strain snails have higher basal mRNA levels of HSPs than W-strain ones; (2) in the W-strain, the training procedure to cause the Garcia effect upregulates the mRNA levels of HSPs and key neuroplasticity-related genes such as CREB1 and GRIN1; (3) in Stony-strain snails, the same training procedure fails to alter the mRNA levels of those targets. These data suggest that Stony-strain snails do not perceive the HS as a stressor because of the higher HSP basal mRNA levels, which may confer a higher thermal tolerance.