Search Results (38)

Sex determination and gonadal differentiation are essential for vertebrate development and reproduction. Fish, with both genetic and environmental sex-determining mechanisms, serve as ideal models for exploring environmental effects on gonadal development. The hypothalamic–pituitary–gonadal (HPG) axis is involved in sex differentiation, but its role as a key mediator in temperature-dependent sex differentiation remains unclear. Sebastes schlegelii is an economically important marine fish species along the northern coast of China. It exhibits obvious sexual growth dimorphism and typical temperature-dependent sex differentiation, making it an excellent model for investigating the mechanism of sex differentiation. In this study, individuals of S. schlegelii at the sex differentiation stage were treated with a GnRH receptor antagonist and subjected to transcriptome sequencing analysis. The results revealed that GnRH may regulate sex differentiation through steroid biosynthesis, TGF-β and MAPK signaling pathways. We identified several key genes, including srd5, bmp8a, bmp2, fgf23, pdgfra, and egfr, which may affect gonadal differentiation by acting on core sex-determining genes and steroidogenesis. In conclusion, GnRH precisely mediates the process of sex differentiation by modulating the TGF-β signaling pathway, the MAPK signaling pathway, and local gonadal steroidogenic networks. Full article

Contemporary climate change, driven by anthropogenic greenhouse gas (GHG) emissions, has raised global temperatures by over 1 °C above pre-industrial levels, profoundly altering Earth’s energy balance. In marine turtles, which exhibit temperature-dependent sex determination (TSD), embryonic sex ratios are highly sensitive to nest temperature. Most studies predicting the effects of climate change on turtle sex ratios have used air temperature or sea surface temperature (SST) as proxies for nest temperature, despite limited empirical validation of this assumption. I question the validity of this approach by examining the physical mechanisms of heat transfer within beach soils, including conduction, convection, and radiation, and how they are modulated by factors such as soil texture, moisture, and solar radiation. The analysis highlights that while GHGs increase air temperature through the greenhouse effect, they do not directly alter incoming solar radiation, the principal driver of subsurface temperature. Furthermore, increased air temperature enhances evaporation and soil drying, reducing thermal conductivity and potentially lowering heat penetration into nesting depths. Consequently, air or SST proxies can misrepresent the actual thermal environment of marine turtle nests, leading to inaccurate or even reverse projections of sex ratios under climate change. A mechanistic approach integrating soil heat dynamics and solar radiation is therefore essential for realistic assessments of TSD responses and conservation planning in a warming world. Full article

Aquatic ecosystems are increasingly threatened by multiple anthropogenic stressors, notably climate change and pollution by pharmaceuticals. Global warming is predicted to raise water temperatures by 2–5 °C by the end of the century. As ectotherms, fish are particularly vulnerable due to limited thermal tolerance and temperature-dependent physiology. Pharmaceuticals are introduced into aquatic systems at concentrations ranging from ng·L⁻¹ to µg·L⁻¹, including widely prescribed classes such as antibiotics, hormones, analgesics, antifungals, and neuropsychiatric drugs. This narrative review synthesizes experimental evidence on the interactive effects of warming and pharmaceutical exposure in fish. Thirty-nine peer-reviewed studies published since 2005 were analyzed. The findings indicate that higher temperatures often exacerbate pharmaceutical-induced toxicity, altering oxidative stress, metabolism, reproduction, and behavior. Antibiotic-focused studies showed temperature-dependent acceleration of absorption, distribution, metabolism, and excretion, with shorter half-lives and reduced tissue persistence at higher temperatures. Estrogenic hormones and antifungals have been shown to interact with thermal regimes, disrupting reproductive physiology and skewing sex ratios, particularly in species exhibiting temperature-dependent sex determination. Neuropsychiatric drugs exhibited altered uptake and metabolism under warming conditions, resulting in increased brain bioaccumulation and behavioral alterations affecting ecological fitness. Analgesics and anti-inflammatories remain understudied despite their widespread use, with evidence suggesting synergistic effects on oxidative stress at elevated temperatures. Significant research gaps persist regarding chronic exposures, early developmental stages, ecologically relevant temperature scenarios, and underrepresented or absent drug classes, such as hypolipidemic drugs. Ultimately, broader and integrated approaches are needed to better understand and predict the ecological risks of pharmaceutical pollution in a warming world. Full article

Accurate scientific information is critical for undertaking appropriate conservation and management practices for imperiled species. One source of concern is that research findings might vary for non-biological reasons, including experimental design and analytical methods. To illustrate, we provide detailed modern analysis of reproductive data for leatherback turtles (Dermochelys coriacea). This species exhibits significant fluctuations in nesting densities across different regions, possibly driven by local rather than global factors. Key factors influencing these changes include hatching success and sex determination, both sensitive to incubation temperatures (e.g., lower temperatures yield more males, higher temperatures yield females). This study updates the understanding of temperature-dependent sex determination (TSD) in this species using Bayesian statistics. Growth rate data from the West Pacific and Northwest Atlantic populations show a similar, monotone increase with temperature, affirming the reliability of the models used. The analysis of TSD patterns indicates that observed differences are more likely due to study methodologies and clutch-specific factors rather than regional differences. These findings challenge previous assumptions, showing that leatherback TSD does not conform to a simple on/off pattern but is influenced by multiple, interacting environmental factors. Population dynamics models must account for these complexities, recognizing that both sex ratios and hatching success are critical to understand the rapid changes observed in some leatherback populations. Full article

The sex of crocodilians is determined by the temperature to which the eggs, and hence the developing embryo are exposed during critical periods of development. Temperature-dependent sex determination is a process that occurs in all crocodilians and numerous other reptile taxa. The study of artificial incubation temperatures in different species of crocodiles and alligators has determined the specific temperature ranges that result in altered sex ratios. It has also revealed the precise temperature thresholds at which an equal number of males and females are generated, as well as the specific developmental period during which the sex of the hatchlings may be shifted. This review will examine the molecular basis of the sex-determination mechanism in crocodilians elucidated during recent decades. It will focus on the many patterns and theories associated with this process. Additionally, we will examine the consequences that arise after hatching due to changes in incubation temperatures, as well as the potential benefits and dangers of a changing climate for crocodilians who display sex determination based on temperature. Full article

The predatory mirids Macrolophus pygmaeus Ramber (Heteroptera: Miridae) and Nesidiocoris tenuis Reuter (Heteroptera: Miridae) are used for the biological control of Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) and other pests in tomato greenhouses. The functional response of 1-day-old (young) and 10-day-old (old) adult females and males of M. pygmaeus and N. tenuis on eggs of T. absoluta was determined on tomato at two temperatures (20 °C and 25 °C) and LD 16:8. Females of M. pygmaeus exhibited higher predation efficiency than males at both tested temperatures. Young M. pygmaeus females had a higher efficiency than old ones, whereas males had a low efficiency irrespective of age. The predation efficiency of N. tenuis was high (but lower than M. pygmaeus) in both young females and males, although old females had a higher efficiency than the respective males. Our results show that the two predatory species have different functional response characteristics to their prey depending mainly on sex and age, which may affect their role as biological control agents. Full article

This study explores the relationship between the light features of the Arctic spring equinox and circadian rhythms, sleep and metabolic health. Residents (N = 62) provided week-long actigraphy measures, including light exposure, which were related to body mass index (BMI), leptin and cortisol. Lower wrist temperature (wT) and higher evening blue light exposure (BLE), expressed as a novel index, the nocturnal excess index (NEIbl), were the most sensitive actigraphy measures associated with BMI. A higher BMI was linked to nocturnal BLE within distinct time windows. These associations were present specifically in carriers of the MTNR1B rs10830963 G-allele. A larger wake-after-sleep onset (WASO), smaller 24 h amplitude and earlier phase of the activity rhythm were associated with higher leptin. Higher cortisol was associated with an earlier M10 onset of BLE and with our other novel index, the Daylight Deficit Index of blue light, DDIbl. We also found sex-, age- and population-dependent differences in the parametric and non-parametric indices of BLE, wT and physical activity, while there were no differences in any sleep characteristics. Overall, this study determined sensitive actigraphy markers of light exposure and wT predictive of metabolic health and showed that these markers are linked to melatonin receptor polymorphism. Full article

The Guatemalan strategy for sea turtle conservation was defined by the National Council of Protected Areas (CONAP) in 1989. Hatcheries lie at the core of this strategy: egg collectors are allowed to deliver 20% of a nest to a hatchery in exchange for selling or eating the remaining eggs. Consequently, nearly 100% of nests are collected, with no nests being left on the beaches. Hatchery design promotes shading using roofs made from vegetation. The logic behind this recommendation is that the natural incubation of eggs is supposedly impossible due to the overly high temperatures on the beach. However, changing the incubation temperature of sea turtle eggs can profoundly alter the sex ratio in sea turtles with temperature-dependent sex determination. It can also modify the physiology or behavior of juvenile turtles. Here, we test whether incubation in natural conditions is possible on Guatemalan beaches, and for the first time, we determine the thermal reaction norm of embryo growth to ensure hatching success in sea turtles. We show that incubation in natural conditions is possible since three out of the four monitored nests produced hatchlings. We urge the Guatemala National Council of Protected Areas to reevaluate its strategy for sea turtle conservation in Guatemala in light of these results. Full article

The application and prognostic nature of systemic inflammatory reaction syndrome (SIRS) is still being researched, as using SIRS parameters to predict patient status is cheap, efficient, fast, and easy. The study aimed to determine SIRS markers and postoperative complications occurrence in patients undergoing kidney tumor surgery, and to verify if SIRS occurrence depends on age, sex, BMI (body mass index), comorbidities, patients’ general condition before the surgery, type of surgery, intraoperative blood loss, or intraoperative ischemia time. Body temperature, heart rate, respiratory rate, and leukocyte count were measured in patients (n = 285) operated on due to a kidney tumor on the first (T0) and third (T3) postoperative day. Univariable and multivariable logistic regression were used to analyze the factors affecting postoperative SIRS and complications occurrence. T0: SIRS developed in patients with higher BMI, >2 ASA points, and more substantial intraoperative blood loss. T3: SIRS developed in obese or overweight patients, with >2 ASA points, significantly higher relative HR change, lower relative body temperature change, respiratory rate, and leukocyte count. BMI values, preoperative general health status, and the amount of intraoperative blood loss in patients undergoing surgery due to a kidney tumor can contribute to SIRS occurrence. Patient’s sex, age, tumor size, type of surgery, operated side, and time of intraoperative ischemia do not affect SIRS occurrence. Full article

The multi-ocellated racerunner, Eremias multiocellata, was considered to have temperature-dependent sex determination (TSD), as its sex ratio can be influenced at different temperatures. However, such an observation contrasts with recent findings that suggest TSD is less common than previously thought. Here, a genotyping-by-sequencing (GBS) approach was employed to identify sex-linked markers in the E. multiocellata, for which the mechanism choice of TSD or GSD is still controversial. We preliminarily identified 119 sex-linked markers based on sex-associated sex-specific sequences, 97% of which indicated female heterogamety. After eliminating the false positives, 38 sex-linked markers were recognized, all of which showed the ZW/ZZ system. Then, eight of the novel markers were verified by PCR amplification from 15 populations of E. multiocellata, which support the GSD in E. multiocellata without geographic variation. To test the conservation of sex chromosome in Eremias, the eight markers were further cross-tested by PCR amplification in 10 individuals of the Mongolian racerunner (Eremias argus), two of which exhibited cross-utility. The novel sex-linked markers could be mapped on the W chromosome of the sand lizard (Lacerta agilis). Our finding that the sex-linked markers are shared in closely related species, along with a conserved synteny of the W chromosome, further supports the homology and conservation of sex chromosomes in the lacertid lizards. Full article

Childhood adversity can induce maladaptive behaviors and increase risk for affective disorders, post-traumatic stress disorder, personality disorders, and vulnerability to stress in adulthood. Deprivation of maternal care interrupts brain development through the disturbance of various neurotransmitters, however, the details remain unclear. The features of the symptoms of disorders are largely determined by early stress protocol, genetic characteristics (line), and the sex of the animals. The purpose of current study was (1) to assess behavioral changes in adult Wistar rats of both sexes after early life stress; (2) to determine the levels of monoamines in brain structures involved in the motor, emotional, and social reactions in rats aged 1 and 2 months; and (3) to determine the level of monoamines after physical or emotional stress in adult rats. The rat pups were separated from their dams and isolated from siblings in tight boxes at a temperature of 22–23 °C for 6 h during postnatal days 2–18. The data were processed predominantly using two-way analysis of variance and the Newman–Keys test as the post hoc analysis. The adult rats demonstrated an increase in motor activity and aggressiveness and a decrease in levels of anxiety and sociability. Behavioral disturbances were accompanied by region-, sex-, and age-dependent changes in the levels of monoamines and their metabolites. The dopaminergic and noradrenergic systems were found to be sensitive to psycho-emotional stress. Full article

Maternal hormones such as estrogens deposited into the yolk of turtle eggs follow circulating levels in adult females, and they may alter the sexual fate of developing embryos in species with temperature-dependent sex determination (TSD). In temperate regions, this deposition occurs during the spring when estrogens increase in adult females as ambient temperatures rise, drop after the first clutch, and peak again (albeit less) in the fall. Global warming alters turtle nesting phenology (inducing earlier nesting), but whether it affects circulating hormones remains unknown, hindering our understanding of all potential challenges posed by climate change and the adaptive potential (or lack thereof) of turtle populations. Here, we addressed this question in painted turtles (Chrysemys picta) by quantifying estradiol, estrone, and testosterone via mass spectrometry in the blood of wild adult females exposed to 26 °C and 21 °C in captivity between mid-August and mid-October (15 females per treatment). Results from ANOVA and pairwise comparisons revealed no differences between treatments in circulating hormones measured at days 0, 2, 7, 14, 28, and 56 of the experiment. Further research is warranted (during the spring, using additional temperatures) before concluding that females are truly buffered against the indirect risk of climate change via maternal hormone allocation. Full article

The anti-Müllerian hormone (Amh) is a protein belonging to the TGF-β superfamily, the function of which has been considered important for male sex differentiation in vertebrates. The Japanese flounder (Paralichthys olivaceus) is a teleost fish that has an XX/XY sex determination system and temperature-dependent sex determination. In this species, amh expression is up-regulated in genetic males and in temperature-induced masculinization during the sex differentiation period. However, to the best of our knowledge, no reports on the Amh receptor (Amhr2) in flounder have been published, and the details of Amh signaling remain unclear. In this study, we produced amhr2-deficient mutants using the CRISPR/Cas9 system and analyzed the gonadal phenotypes and sex-related genes. The results revealed that the gonads of genetically male amhr2 mutants featured typical ovaries, and the sex differentiation-related genes showed a female expression pattern. Thus, the loss of Amhr2 function causes male-to-female sex reversal in Japanese flounder. Moreover, the treatment of genetically male amhr2 mutants with an aromatase inhibitor fadrozole, which inhibits estrogen synthesis, resulted in testicular formation. These results strongly suggest that Amh/Amhr2 signaling causes masculinization by inhibiting estrogen synthesis during gonadal sex differentiation in the flounder. Full article

The aim of the conducted research was to determine the impact of factors such as sex hormone levels, which vary during gilts’ reproductive cycle, on the quality of the obtained meat and slaughter characteristics of the processed gilts. The research material included a population of 60 gilts slaughtered in one of the slaughterhouses located in south-eastern Poland. After the slaughtering operations were completed, the carcasses were weighed at the classification stand. The results of the statistical evaluation of the haematological and biochemical blood parameters of the examined gilts showed that, in the tested blood samples, the concentration of progesterone had a statistically significant impact only on the level of total protein, which was higher in the blood samples of gilts with a low concentration of progesterone. It was found that carcasses of gilts with higher levels of the LH hormone were characterized by a lower meat content index by nearly 3%. It was shown that the concentration of LH affected the post-slaughter temperature of the sirloin and ham muscles. The interpretation of the obtained data was difficult since there seems to be a gap in the literature concerning the dependencies of sex hormone levels in gilts and meat quality. Full article

Background: The gonads of Chrysemys picta, a turtle with temperature-dependent sex determination (TSD), exhibit differential DNA methylation between males and females, but whether the same is true in somatic tissues remains unknown. Such differential DNA methylation in the soma would provide a non-lethal sex diagnostic for TSD turtle hatchings who lack visually detectable sexual dimorphism when young. Methods: Here, we tested multiple approaches to study DNA methylation in tail clips of Chrysemys picta hatchlings, to identify differentially methylated candidate regions/sites that could serve as molecular sex markers To detect global differential methylation in the tails we used methylation-sensitive ELISA, and to test for differential local methylation we developed a novel hybrid method by sequencing immunoprecipitated and bisulfite converted DNA (MeDIP-BS-seq) followed by PCR validation of candidate regions/sites after digestion with a methylation-sensitive restriction enzyme. Results: We detected no global differences in methylation between males and females via ELISA. While we detected inter-individual variation in DNA methylation in the tails, this variation was not sexually dimorphic, in contrast with hatchling gonads. Conclusions: Results highlight that differential DNA methylation is tissue-specific and plays a key role in gonadal formation (primary sexual development) and maintenance post-hatching, but not in the somatic tail tissue. Full article