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Harmonics are an integral part of music, speech, and vocalizations of animals. Since the rest of the auditory environment is primarily made up of nonharmonic sounds, the auditory system needs to perceptually separate the above two kinds of sounds. In mice, harmonics, generally with two-tone components (two-tone harmonic complexes, TTHCs), form an important component of vocal communication. Communication by pups during isolation from the mother and by adult males during courtship elicits typical behaviors in female mice—dams and adult courting females, respectively. Our study shows that the processing of TTHC is specialized in mice providing neural basis for perceptual differences between tones and TTHCs and also nonharmonic sounds. Investigation of responses in the primary auditory cortex (Au1) from in vivo extracellular recordings and two-photon Ca2+ imaging of excitatory and inhibitory neurons to TTHCs exhibit enhancement, suppression, or no-effect with respect to tones. Irrespective of neuron type, harmonic enhancement is maximized, and suppression is minimized when the fundamental frequencies (F0 ) match the neuron’s best fundamental frequency (BF0 ). Sex-specific processing of TTHC is evident from differences in the distributions of neurons’ best frequency (BF) and best fundamental frequency (BF0) in single units, differences in harmonic suppressed cases re-BF0, independent of neuron types, and from pairwise noise correlations among excitatory and parvalbumin inhibitory interneurons. Furthermore, TTHCs elicit a higher response compared with two-tone nonharmonics in females, but not in males. Thus, our study shows specialized neural processing of TTHCs over tones and nonharmonics, highlighting local network specialization among different neuronal types. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a common and complex joint disorder that shows higher prevalence and greater disease severity in women. Here, we investigate genome-wide methylation profiles of primary chondrocytes from osteoarthritis patients. We compare genome-wide methylation profiles of macroscopically intact (low-grade) and degraded (high-grade) osteoarthritis cartilage samples matched from osteoarthritis patients undergoing knee replacement surgery. We perform an epigenome-wide association study for cartilage degeneration across 170 patients and separately in 96 women and 74 men. We reveal widespread epigenetic differences with enrichments of nervous system and apoptosis-related processes. We further identify substantial similarities between sexes, but also sex-specific markers and pathways. Together, we provide the largest genome-wide methylation profiles of primary cartilage to date with enhanced and sex-specific insights into epigenetic processes underlying osteoarthritis progression. [ABSTRACT FROM AUTHOR]

Purpose: To identify practice and social contextual factors that associate with physical activity (PA) levels of children during their participation in a youth soccer program. Methods: Twenty-seven youth soccer teams serving children ages 6–11 years participated. Research staff directly observed and recorded PA intensity and practice and social contextual factors using momentary time-sampling procedures. Each team was observed for 1 practice, during which approximately 6 children were each observed for twenty 30-s observation blocks (10-s observation, 20-s recording). In total, children were observed for 3,102 intervals. Multilevel logistic regression analyses were conducted to describe associations between PA intensity and practice and social contexts. Interaction terms were introduced into the models to determine if the associations differed across girls-only, boys-only, and coed teams. Results: A total of 158 children were observed across the 27 teams. Children were more likely to engage in moderate or vigorous PA while performing fitness (Odds Ratio [OR], 9.9, 95% CI = 5.34–18.04), game (OR, 4.0, 95% CI = 2.88–5.66), warm-up (OR, 2.8, 95% CI = 1.85–4.11), and drill (OR, 1.9, 95% CI = 1.41–2.67) activities compared to tactic/instructional activities. The associations between PA intensity levels and practice and social contexts did not differ across girls-only, boys-only, and coed teams. Conclusions: Fitness activities and full-team game play were associated with higher PA intensity levels during children's participation in youth soccer practices. Youth sport practice protocols can be modified to increase children's physical activity. [ABSTRACT FROM AUTHOR]

Today's challenge for precision medicine involves the integration of the impact of molecular clocks on drug pharmacokinetics, toxicity, and efficacy toward personalized chronotherapy. Meaningful improvements of tolerability and/or efficacy of medications through proper administration timing have been confirmed over the past decade for immunotherapy and chemotherapy against cancer, as well as for commonly used pharmacological agents in cardiovascular, metabolic, inflammatory, and neurological conditions. Experimental and human studies have recently revealed sexually dimorphic circadian drug responses. Dedicated randomized clinical trials should now aim to issue personalized circadian timing recommendations for daily medical practice, integrating innovative technologies for remote longitudinal monitoring of circadian metrics, statistical prediction of molecular clock function from single-timepoint biopsies, and multiscale biorhythmic mathematical modelling. Importantly, chronofit patients with a robust circadian function, who would benefit most from personalized chronotherapy, need to be identified. Conversely, nonchronofit patients could benefit from the emerging pharmacological class of chronobiotics targeting the circadian clock. [ABSTRACT FROM AUTHOR]

Background: Yakuts are one of the indigenous populations of the subarctic and arctic territories of Siberia characterized by a continental subarctic climate with severe winters, with the regular January average temperature in the regional capital city of Yakutsk dipping below − 40 °C. The epigenetic mechanisms of adaptation to such ecologies and environments and, in particular, epigenetic age acceleration in the local population have not been studied before. Results: This work reports the first epigenetic study of the Yakutian population using whole-blood DNA methylation data, supplemented with the comparison to the residents of Central Russia. Gene set enrichment analysis revealed, among others, geographic region-specific differentially methylated regions associated with adaptation to climatic conditions (water consumption, digestive system regulation), aging processes (actin filament activity, cell fate), and both of them (channel activity, regulation of steroid and corticosteroid hormone secretion). Further, it is demonstrated that the epigenetic age acceleration of the Yakutian representatives is significantly higher than that of Central Russia counterparts. For both geographic regions, we showed that epigenetically males age faster than females, whereas no significant sex differences were found between the regions. Conclusions: We performed the first study of the epigenetic data of the Yakutia cohort, paying special attention to region-specific features, aging processes, age acceleration, and sex specificity. [ABSTRACT FROM AUTHOR]

Background The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II–mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo. Methods and Results Changes in VEC intracellular calcium ([Ca2+]i) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5–Salsa6f mice or the endothelial uptake of NO‐sensitive dye 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready‐to‐use adeno‐associated virus expressing Mouse Renin 1 gene (Ren1‐AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4‐fold increases in VEC [Ca2+]i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5‐fold increase in 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II–induced VEC [Ca2+]i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation. Conclusions The present study directly visualized angiotensin II–induced increases in VEC [Ca2+]i and NO production that serve to counterbalance agonist‐induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium‐specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.

The exposure to sublethally high temperature reduces reproductive performance in diverse organisms. Although this effect has been particularly emphasized for males or male reproductive functioning, it remains largely unknown whether the effect of heat on fertility is sex-specific. Here we examined the impact of sublethally high temperature on male and female functions in a simultaneously hermaphroditic snail species, Lymnaea stagnalis. Examining hermaphrodites is useful to evaluate the sex-specific impacts of heat exposure, since they possess male and female functions within a single individual, sharing genetic and environmental factors. Moreover, previously developed sex allocation theory allows us to compare the differential performance of sex functions. In this study, we exposed snails to 20°C (control), 24°C and 28°C for 14 days and assessed their egg and sperm production, sperm transfer, mating behaviour and growth. Both types of gamete production were significantly reduced by higher temperature, leading to an overall reduction of reproductive investment. By quantifying sex allocation, we furthermore revealed that the heat-stressed snails reduced the relative investment in their male function. This study illustrates that examining simultaneous hermaphrodites can provide significant insights for the impact of heat, and the proximate mechanism, on reproduction in diverse organisms.

Myristoylated alanine-rich C-kinase substrate (MARCKS) is a critical member of a signaling cascade that influences disease-relevant neural functions such as neural growth and plasticity. The effector domain (ED) of MARCKS interacts with the extracellular glycan polysialic acid (PSA) through the cell membrane to stimulate neurite outgrowth in cell culture. We have shown that a synthetic ED peptide improves functional recovery after spinal cord injury in female but not male mice. However, peptides themselves are unstable in therapeutic applications, so we investigated more pharmacologically relevant small organic compounds that mimic the ED peptide to maximize therapeutic potential. Using competition ELISAs, we screened small organic compound libraries to identify molecules that structurally and functionally mimic the ED peptide of MARCKS. Since we had shown sex-specific effects of MARCKS on spinal cord injury recovery, we assayed neuronal viability as well as neurite outgrowth from cultured cerebellar granule cells of female and male mice separately. We found that epigallocatechin, amiodarone, sertraline, tegaserod, and nonyloxytryptamine bind to a monoclonal antibody against the ED peptide, and compounds stimulate neurite outgrowth in cultured cerebellar granule cells of female mice only. Therefore, a search for compounds that act in males appears warranted. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) can affect marine bivalves at various levels of biological organization. Yet, little effort has been devoted to understanding how OA affects the reproductive events of marine bivalves during multiple cycles of maturation. Here, we tested sex-specific reproductive responses of Manila clams (Ruditapes philippinarum) to OA during gonadal rematuration. Under acidified conditions, both male and female clams exhibited delayed gonadal rematuration following spawning and impairments in gonadal tissues, which can be likely ascribed to lowered concentrations of hormones and vitellogenin. The findings indicate that marine bivalves experience significant declines in reproductive capacity as a result of OA during their reproductive cycles, with clear sex-specific differences. Consequently, it is essential to consider sex-specific reproduction responses of marine bivalves to OA when developing conservation strategies and forecasting population sustainability in a rapidly acidifying marine environment. • Impacts of ocean acidification on bivalve gonadal rematuration were examined. • Sex can significantly affect physiological performances under acidified conditions. • Females are more vulnerable to OA than males during gonadal rematuration. [ABSTRACT FROM AUTHOR]

Myristoylated alanine-rich C-kinase substrate (MARCKS) is a critical member of a signaling cascade that influences disease-relevant neural functions such as neural growth and plasticity. The effector domain (ED) of MARCKS interacts with the extracellular glycan polysialic acid (PSA) through the cell membrane to stimulate neurite outgrowth in cell culture. We have shown that a synthetic ED peptide improves functional recovery after spinal cord injury in female but not male mice. However, peptides themselves are unstable in therapeutic applications, so we investigated more pharmacologically relevant small organic compounds that mimic the ED peptide to maximize therapeutic potential. Using competition ELISAs, we screened small organic compound libraries to identify molecules that structurally and functionally mimic the ED peptide of MARCKS. Since we had shown sex-specific effects of MARCKS on spinal cord injury recovery, we assayed neuronal viability as well as neurite outgrowth from cultured cerebellar granule cells of female and male mice separately. We found that epigallocatechin, amiodarone, sertraline, tegaserod, and nonyloxytryptamine bind to a monoclonal antibody against the ED peptide, and compounds stimulate neurite outgrowth in cultured cerebellar granule cells of female mice only. Therefore, a search for compounds that act in males appears warranted.

In the animal kingdom, intraspecific variation occurs, for example, between populations, different life stages, and sexes. For venomous animals, this can involve differences in their venom composition. In cases where venom is utilized in the context of mating, the differences in composition might be driven by sexual selection. In this regard, the genus Euscorpius is a promising group for further research, as some of these scorpions exhibit a distinct sexual dimorphism and are known to perform a sexual sting during mating. However, the venom composition of this genus remains largely unexplored. Here, we demonstrate that Euscorpius italicus exhibits a male-specific venom composition, and we identify a large fraction of the substances involved. The sex specificity of venom peptides was first determined by analyzing the presence/absence patterns of ion signals in MALDI-TOF mass spectra of venom samples from both sexes and juveniles. Subsequently, a proteo-transcriptomic analysis provided sequence information on the relevant venom peptides and their corresponding precursors. As a result, we show that several potential toxin precursors are down-regulated in male venom glands, possibly to reduce toxic effects caused to females during the sexual sting. We have identified the precursor of one of the most prominent male-specific venom peptides, which may be an ideal candidate for activity tests in future studies. In addition to the description of male-specific features in the venom of E. italicus, this study also includes a general survey of venom precursors in this species. [ABSTRACT FROM AUTHOR]

Caffeine exerts a biphasic effect on zebrafish behavior. High doses of caffeine have been associated with increased stress and anxiety, whereas low doses have been found to enhance performance on tasks requiring focus and attention. However, the sex-specific nature of these biphasic effects on behavior and physiology remains unclear. This study assessed the behavioral responses and hormone levels in male and female zebrafish after acute exposure to caffeine ranging from 0.3 to 600 mg/L. The results showed no significant difference in caffeine intake between males and females after acute exposure at each concentration. Caffeine-induced behavioral and physiological responses indicated a threshold dosage existed between 30 and 300 mg/L. Female fish displayed increased anxiety-like behavioral phenotypes, i.e., latency to upper and freezing, whereas males exhibited more erratic movement following acute exposure to a high-dose treatment. In addition, females exhibited a significant increase in whole-body cortisol levels, while males experienced a testosterone elevation at 300 mg/L of caffeine acute exposure. There was a significant decrease in the duration of erratic movements in males treated with the androgen receptor antagonist flutamide compared to the control group. The transcriptome analysis uncovered 511 and 592 up-regulated and 761 and 922 down-regulated differential expression genes in males and females, respectively, compared to the control. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway analysis revealed that caffeine has the potential to impact various pathways in zebrafish, including phototransduction and steroid hormone biosynthesis. Our findings demonstrate that testosterone and cortisol play a combined role in regulating stress responses in both behavior and physiology. Furthermore, our study highlights the significance of encompassing both male and female zebrafish as a model system. • Zebrafish showed sex-specific behavior and physiology in response to caffeine. • Females showed signs of freezing, while males displayed erratic movements. • Cortisol and testosterone levels were higher in females and males, respectively. • Caffeine may affect steroid hormone production. [ABSTRACT FROM AUTHOR]

Nootropics (smart drugs) are used by students to enhance cognitive performance which have been reported times in recent years. However, some of the nootropics are central nervous system stimulants which are very likely to lead to addiction or complications such as vomiting and dizziness. Are there nootropics that can improve learning behavior while having potential positive effect on health? Here, we reported that Atomoxetine (ATX) has sex-specific effect on prolonging the life span of female Drosophila melanogaster. Further study indicated that ATX enhanced female resistance to heat stress and their vertical climbing ability, but it did decrease the number of eggs laid. ATX increased food-intake and sleep time both of females and males, and significantly reduced the 24h spontaneous activity of females and males. Our results present the sex dimorphic effect of ATX on life span regulation in Drosophila, and support further research on the beneficial role of ATX and the mechanisms in other animal models. [ABSTRACT FROM AUTHOR]

Bisphenols, parabens, and triclosan (TCS) are common endocrine disrupters used in various consumer products. These chemicals have been shown to cross the placental barrier and affect intrauterine development of fetuses. In this study, we quantified serum levels of six bisphenols, five parabens, and TCS in 483 pregnant women from southern China. Quantile-based g-computation showed that combined exposure to bisphenols, parabens, and TCS was significantly ( p < 0.05) and negatively associated with birth weight (β = -39.9, 95% CI: -73.8, -6.1), birth length (β = -0.19, 95% CI: -0.34, -0.04), head circumference (β = -0.13, 95% CI: -0.24, -0.02), and thoracic circumference (β = -0.16, 95% CI: -0.29, -0.04). An inverse correlation was also identified between mixture exposure and gestational age (β = -0.12, 95% CI: -0.24, -0.01). Bisphenol A (BPA), bisphenol Z (BPZ), bisphenol AP (BPAP), propylparaben (PrP), and TCS served as the dominant contributors to the overall effect. In subgroup analyses, male newborns were more susceptible to mixture exposure than females, whereas the exposure-outcome link was prominent among pregnant women in the first and second trimesters. More evidence is warranted to elucidate the impacts of exposure to mixtures on birth outcomes, as well as the underlying mechanisms.

In the animal kingdom, intraspecific variation occurs, for example, between populations, different life stages, and sexes. For venomous animals, this can involve differences in their venom composition. In cases where venom is utilized in the context of mating, the differences in composition might be driven by sexual selection. In this regard, the genus Euscorpius is a promising group for further research, as some of these scorpions exhibit a distinct sexual dimorphism and are known to perform a sexual sting during mating. However, the venom composition of this genus remains largely unexplored. Here, we demonstrate that Euscorpius italicus exhibits a male-specific venom composition, and we identify a large fraction of the substances involved. The sex specificity of venom peptides was first determined by analyzing the presence/absence patterns of ion signals in MALDI-TOF mass spectra of venom samples from both sexes and juveniles. Subsequently, a proteo-transcriptomic analysis provided sequence information on the relevant venom peptides and their corresponding precursors. As a result, we show that several potential toxin precursors are down-regulated in male venom glands, possibly to reduce toxic effects caused to females during the sexual sting. We have identified the precursor of one of the most prominent male-specific venom peptides, which may be an ideal candidate for activity tests in future studies. In addition to the description of male-specific features in the venom of E. italicus, this study also includes a general survey of venom precursors in this species.

Although macula densa (MD) cells are chief regulatory cells in the nephron with unique microanatomical features, they have been difficult to study in full detail due to their inaccessibility and limitations in earlier microscopy techniques. The present study used a new mouse model with a comprehensive imaging approach to visualize so far unexplored microanatomical features of MD cells, their regulation, and functional relevance. MD-GFP mice with conditional and partial induction of green fluorescent protein (GFP) expression, which specifically and intensely illuminated only single MD cells, were used with fluorescence microscopy of fixed tissue and live MD cells in vitro and in vivo with complementary electron microscopy of the rat, rabbit, and human kidney. An elaborate network of major and minor cell processes, here named maculapodia, were found at the cell base, projecting toward other MD cells and the glomerular vascular pole. The extent of maculapodia showed upregulation by low dietary salt intake and the female sex. Time-lapse imaging of maculapodia revealed highly dynamic features including rapid outgrowth and an extensive vesicular transport system. Electron microscopy of rat, rabbit, and human kidneys and three-dimensional volume reconstruction in optically cleared whole-mount MD-GFP mouse kidneys further confirmed the presence and projections of maculapodia into the extraglomerular mesangium and afferent and efferent arterioles. The newly identified dynamic and secretory features of MD cells suggest the presence of novel functional and molecular pathways of cell-to-cell communication in the juxtaglomerular apparatus between MD cells and between MD and other target cells. NEW & NOTEWORTHY This study illuminated a physiologically regulated dense network of basal cell major and minor processes (maculapodia) in macula densa (MD) cells. The newly identified dynamic and secretory features of these microanatomical structures suggest the presence of novel functional and molecular pathways of cell-to-cell communication in the juxtaglomerular apparatus between MD and other target cells. Detailed characterization of the function and molecular details of MD cell intercellular communications and their role in physiology and disease warrant further studies. [ABSTRACT FROM AUTHOR]

Background: Previous epidemiological research has linked posttraumatic stress disorder (PTSD) with specific physical health problems, but the comprehensive landscape of medical conditions associated with PTSD remains uncharacterized. Electronic health records provide an opportunity to overcome clinical knowledge gaps and uncover associations with biological relevance that potentially vary by sex., Methods: PTSD was defined among biobank participants ( N  = 145,959) in 3 major healthcare systems using 2 ICD code-based definitions: broad (≥1 PTSD or acute stress codes vs. 0; n cases  = 16,706) and narrow (≥2 PTSD codes vs. 0; n cases  = 3325). Using a phenome-wide association study design, we tested associations between each PTSD definition and all prevalent disease umbrella categories, i.e., phecodes. We also conducted sex-stratified phenome-wide association study analyses including a sex × diagnosis interaction term in each logistic regression., Results: A substantial number of phecodes were significantly associated with PTSD Narrow (61%) and PTSD Broad (83%). While the strongest associations were shared between the 2 definitions, PTSD Broad captured 334 additional phecodes not significantly associated with PTSD Narrow and exhibited a wider range of significantly associated phecodes across various categories, including respiratory, genitourinary, and circulatory conditions. Sex differences were observed in that PTSD Broad was more strongly associated with osteoporosis, respiratory failure, hemorrhage, and pulmonary heart disease among male patients and with urinary tract infection, acute pharyngitis, respiratory infections, and overweight among female patients., Conclusions: This study provides valuable insights into a diverse range of comorbidities associated with PTSD, including both known and novel associations, while highlighting the influence of sex differences and the impact of defining PTSD using electronic health records., (© 2024 The Authors.)

Background: The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II-mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo., Methods and Results: Changes in VEC intracellular calcium ([Ca 2+ ] i ) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5-Salsa6f mice or the endothelial uptake of NO-sensitive dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready-to-use adeno-associated virus expressing Mouse Renin 1 gene (Ren1-AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4-fold increases in VEC [Ca 2+ ] i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5-fold increase in 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II-induced VEC [Ca 2+ ] i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation., Conclusions: The present study directly visualized angiotensin II-induced increases in VEC [Ca 2+ ] i and NO production that serve to counterbalance agonist-induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium-specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.

Abstract Background An increasing number of epidemiological and experimental studies have associated exposure to second-hand smoke (SHS) during pregnancy with adverse outcomes in newborns. As we have previously shown in mice, in utero exposure to SHS at critical stages of fetal development, results in altered lung responses and increased disease susceptibility upon re-exposure to irritants (SHS or ovalbumin) in adulthood. In this study, we asked whether the in utero SHS exposure alone is sufficient to alter lung structure and function in adult mice. Methods Pregnant BALB/c mice were exposed from days 6 to 19 of pregnancy to 10 mg/m3 of SHS or HEPA-filtered air. Male and female offspring (n = 13–15/group) were sacrificed at 15 weeks of age. We measured lung function with non-invasive and invasive methods, performed lung morphometric analysis on trichrome-stained lung tissue samples, and assessed lung gene expression via RNA sequencing and protein assays. Results In utero SHS exposure significantly increased mean linear intercept and decreased the surface area per unit volume of the lungs in both males and females, indicating perturbation in alveolar developmental processes. Tidal volume, minute volume and inspiratory capacity were significantly decreased compared with the controls only in male mice exposed in utero to SHS, suggesting that males are more sensitive than females to an SHS insult during lung development. This also suggests that in our model, lung structure changes may be necessary but are not sufficient to impair lung function. SERPINA1A, the mouse ortholog of human α1-antitrypsin, deficiency of which is a known genetic risk factor for emphysema, was down-regulated at the protein level in the in utero SHS-exposed mice. Additionally, DNMT3A protein expression was dysregulated, indicating that DNA methylation occurred in the lungs. Conclusions Our results indicate that in utero SHS exposure alone alters both lung function and structure well into adulthood (15 weeks) in male mice. Furthermore, lung function alterations in this model are sex-specific, with males being more susceptible to in utero SHS effects. Overall, our data suggest that in utero SHS exposure alone can predispose to adult lung diseases.

The exposure to sublethally high temperature reduces reproductive performance in diverse organisms. Although this effect has been particularly emphasized for males or male reproductive functioning, it remains largely unknown whether the effect of heat on fertility is sex-specific. Here we examined the impact of sublethally high temperature on male and female functions in a simultaneously hermaphroditic snail species, Lymnaea stagnalis . Examining hermaphrodites is useful to evaluate the sex-specific impacts of heat exposure, since they possess male and female functions within a single individual, sharing genetic and environmental factors. Moreover, previously developed sex allocation theory allows us to compare the differential performance of sex functions. In this study, we exposed snails to 20°C (control), 24°C and 28°C for 14 days and assessed their egg and sperm production, sperm transfer, mating behaviour and growth. Both types of gamete production were significantly reduced by higher temperature, leading to an overall reduction of reproductive investment. By quantifying sex allocation, we furthermore revealed that the heat-stressed snails reduced the relative investment in their male function. This study illustrates that examining simultaneous hermaphrodites can provide significant insights for the impact of heat, and the proximate mechanism, on reproduction in diverse organisms., Competing Interests: The authors declare no competing or financial interests., (© 2024 The Authors.)

Abstract Patients presenting with chest pain suggestive of coronary artery disease (CAD) who at coronary arteriography appear to be free of obstructive disease have presented a diagnostic and therapeutic challenge since the 1970's. Studies in female patient populations have suggested that this is predominantly a women's syndrome usually caused by microvascular endothelial dependent and independent dysfunction. A critical review of the literature focusing on studies including both women and men revealed that apart from a higher incidence of this syndrome in women there are no clinical relevant differences between both sexes. In women a lower coronary flow reserve has been reported but this appears to be mainly due to a higher basal flow. Important questions with regard to the clinical implications of microvascular dysfunction have yet to be resolved in studies involving women as well as men in which a distinction is made between patients with normal coronary arteries and those with nonobstructive disease. Highlights • Sex specificity of microvascular angina has not been proven. • Women more often than men have chest pain without coronary obstructions. • Hypertension is a common cause of microvascular disease and in part reversible. • Irrespective of sex normal coronary arteries indicates a favorable prognosis. [ABSTRACT FROM AUTHOR]

The circadian clock is an evolutionarily conserved mechanism that generates the rhythmic expression of downstream genes. The core circadian clock drives the expression of clock-controlled genes, which in turn play critical roles in carrying out many rhythmic physiological processes. Nevertheless, the molecular mechanisms by which clock output genes orchestrate rhythmic signals from the brain to peripheral tissues are largely unknown. Here we explored the role of one rhythmic gene, Achilles, in regulating the rhythmic transcriptome in the fly head. Achilles is a clock-controlled gene in Drosophila that encodes a putative RNA-binding protein. Achilles expression is found in neurons throughout the fly brain using fluorescence in situ hybridization (FISH), and legacy data suggest it is not expressed in core clock neurons. Together, these observations argue against a role for Achilles in regulating the core clock. To assess its impact on circadian mRNA rhythms, we performed RNA sequencing (RNAseq) to compare the rhythmic transcriptomes of control flies and those with diminished Achilles expression in all neurons. Consistent with previous studies, we observe dramatic upregulation of immune response genes upon knock-down of Achilles. Furthermore, many circadian mRNAs lose their rhythmicity in Achilles knock-down flies, suggesting that a subset of the rhythmic transcriptome is regulated either directly or indirectly by Achilles. These Achilles -mediated rhythms are observed in genes involved in immune function and in neuronal signaling, including Prosap, Nemy and Jhl-21. A comparison of RNAseq data from control flies reveals that only 42.7% of clock-controlled genes in the fly brain are rhythmic in both males and females. As mRNA rhythms of core clock genes are largely invariant between the sexes, this observation suggests that sex-specific mechanisms are an important, and heretofore under-appreciated, regulator of the rhythmic transcriptome. [ABSTRACT FROM AUTHOR]

We investigated the toxic effect of visible light on Drosophila life span in both sexes. The toxic effect of ultraviolet light on organisms is well known. However, the effects of illumination with visible light remain unclear. Here, we found that visible light could be toxic to Drosophila survival, depending on the protein content in diet. In addition, further analysis revealed significant interaction between light and sex and showed that strong light shortened life span by causing opposite direction changes in mortality rate parameters in females versus males. Our findings suggest that photoaging may be a general phenomenon and support the theory of sexual antagonistic pleiotropy in aging intervention. The results caution that exposure to visible light could be hazardous to life span and suggest that identification of the underlying mechanism would allow better understanding of aging intervention. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) can seriously affect marine bivalves at different levels of biological organization, generating widespread consequences on progeny recruitment and population maintenance. Yet, few effort has been devoted to elucidating whether female and male bivalves respond differentially to OA in their reproductive seasons. Here, we estimated differences in physiological responses of female and male Manila clams (Ruditapes philippinarum) to OA during gonadal maturation. In comparison to OA-stressed male clams, females significantly depressed activities in enzymes related to energy metabolism (NKA, T-ATP), antioxidant defence (SOD and MDA), and non-specific immune function (ACP), and downregulated expression of AMPK that plays a key role in cellular metabolism, indicating that sex did significantly affect responses of R. philippinarum to OA. Such sex-based differences can be likely couched in energetic terms, given the much more energetically expensive cost of egg production than that of sperms. These results indicate that sex-specific responses to OA during reproductive seasons do exist in marine bivalves, and therefore accounting for such sex specificity is of paramount importance when projecting population sustainability and formulating conservation strategies in an acidifying ocean. • Sex specificity in responses to OA during reproductive seasons were examined. • Sex can significantly affect physiological performances under acidified conditions. • Females are more sensitive to OA than males during gonadal maturation. [ABSTRACT FROM AUTHOR]

Elevated levels of the type III ( III ) isoforms of neuregulin 1 ( NRG1 ) have been observed in the brains of schizophrenia patients that carry NRG1 Hap ICE risk alleles, which is thought to contribute to the aetiology of the disease. We generated transgenic mice with forebrain driven Nrg1 III overexpression ( Nrg1 III tg ) and previously found that male heterozygous Nrg1 type III tg mice exhibit several schizophrenia-relevant behaviours including social and cognitive deficits as well as impaired sensorimotor gating. A number of mouse models for other Nrg1 isoform types exhibit sex-specific phenotypes yet sex-specific effects of Nrg1 III overexpression had not been evaluated. Thus, in this study we tested female Nrg1 III transgenic mice using a comprehensive behavioural phenotyping battery relevant to positive, negative and cognitive symptoms of schizophrenia. Firstly, forebrain Nrg1 III mRNA overexpression was confirmed in female transgenic mice using by qPCR. In the open field test, female Nrg1 III mice exhibited a blunted response to an acute challenge with the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801. Female Nrg1 III tg mice also exhibited moderately impaired short-term memory. Other behavioural domains including sensory abilities, motor functions, baseline locomotion, anxiety, sociability, social recognition memory, fear conditioning and prepulse inhibition were unperturbed in Nrg1 III tg females. Together these results illustrate that overexpressing forebrain Nrg1 III in female mice modifies the locomotive response to NMDA receptor antagonism without causing severe alterations to a number of other schizophrenia-related behavioural domains. The data suggest that behavioural effects of Nrg1 III overexpression may be sex-dependent. [ABSTRACT FROM AUTHOR]

Background: An increasing number of epidemiological and experimental studies have associated exposure to second-hand smoke (SHS) during pregnancy with adverse outcomes in newborns. As we have previously shown in mice, in utero exposure to SHS at critical stages of fetal development, results in altered lung responses and increased disease susceptibility upon re-exposure to irritants (SHS or ovalbumin) in adulthood. In this study, we asked whether the in utero SHS exposure alone is sufficient to alter lung structure and function in adult mice.Methods: Pregnant BALB/c mice were exposed from days 6 to 19 of pregnancy to 10 mg/m3 of SHS or HEPA-filtered air. Male and female offspring (n = 13-15/group) were sacrificed at 15 weeks of age. We measured lung function with non-invasive and invasive methods, performed lung morphometric analysis on trichrome-stained lung tissue samples, and assessed lung gene expression via RNA sequencing and protein assays.Results: In utero SHS exposure significantly increased mean linear intercept and decreased the surface area per unit volume of the lungs in both males and females, indicating perturbation in alveolar developmental processes. Tidal volume, minute volume and inspiratory capacity were significantly decreased compared with the controls only in male mice exposed in utero to SHS, suggesting that males are more sensitive than females to an SHS insult during lung development. This also suggests that in our model, lung structure changes may be necessary but are not sufficient to impair lung function. SERPINA1A, the mouse ortholog of human α1-antitrypsin, deficiency of which is a known genetic risk factor for emphysema, was down-regulated at the protein level in the in utero SHS-exposed mice. Additionally, DNMT3A protein expression was dysregulated, indicating that DNA methylation occurred in the lungs.Conclusions: Our results indicate that in utero SHS exposure alone alters both lung function and structure well into adulthood (15 weeks) in male mice. Furthermore, lung function alterations in this model are sex-specific, with males being more susceptible to in utero SHS effects. Overall, our data suggest that in utero SHS exposure alone can predispose to adult lung diseases. [ABSTRACT FROM AUTHOR]

The information transmitted by acoustic signals has attracted much scientific interest in recent years. However, isolation calls, which are long-distance vocalizations used by lost group members to reunite with their social group, have been surprisingly neglected. These calls assist in maintaining group cohesion and are thus particularly important in species that depend on the group for survival or reproduction such as cooperative breeders. Our study therefore examined the information transmitted by the isolation vocalization in a wild cooperatively breeding carnivore: the dwarf mongoose, Helogale parvula . We ran an acoustic analysis for informative cues within isolation calls, and conducted a series of playback experiments to identify whether mongooses could discriminate between callers based on these cues. The acoustic structure of dwarf mongoose isolation vocalizations contained information concerning the caller's identity, sex and potentially also group membership. Target mongooses discriminated between callers of their own and other groups and biased their response based on the sex of the caller. They responded more quickly and for longer, and approached more closely, for calls of foreign females than calls of female group mates. This is the first time that sex specificity has been demonstrated in the vocalization of an herpestid, and we suggest that dwarf mongooses eavesdrop on the calls of isolated foreigners and may use isolation calls to attract and identify potential mates. [ABSTRACT FROM AUTHOR]

Gap junctions are present in many cell types throughout the animal kingdom and allow fast intercellular electrical and chemical communication between neighboring cells. Connexin-36 (Cx36), the major neuronal gap junction protein, synchronizes cellular activity in the brain, but also in other organs. Here we identify a sex-specific role for Cx36 within the hypothalamic-pituitary-gonadal (HPG) axis at the level of the anterior pituitary gland (AP). We show that Cx36 is expressed in gonadotropes of the AP sustaining their synchronous activity. Cx36 ablation affects the entire downstream HPG axis in females, but not in males. We demonstrate that Cx36-mediated coupling between gonadotropes in the AP supports gonadotropin-releasing hormone-induced secretion of luteinizing hormone. Furthermore, we provide evidence for negative feedback regulation of Cx36 expression in the AP by estradiol. We thus conclude that hormonally-controlled plasticity of gap junction communication at the level of the AP constitutes an additional mechanism affecting female reproduction.

Gap junctions are present in many cell types throughout the animal kingdom and allow fast intercellular electrical and chemical communication between neighboring cells. Connexin-36 (Cx36), the major neuronal gap junction protein, synchronizes cellular activity in the brain, but also in other organs. Here we identify a sex-specific role for Cx36 within the hypothalamic-pituitary-gonadal (HPG) axis at the level of the anterior pituitary gland (AP). We show that Cx36 is expressed in gonadotropes of the AP sustaining their synchronous activity. Cx36 ablation affects the entire downstream HPG axis in females, but not in males. We demonstrate that Cx36-mediated coupling between gonadotropes in the AP supports gonadotropin-releasing hormone-induced secretion of luteinizing hormone. Furthermore, we provide evidence for negative feedback regulation of Cx36 expression in the AP by estradiol. We thus, conclude that hormonally-controlled plasticity of gap junction communication at the level of the AP constitutes an additional mechanism affecting female reproduction. [ABSTRACT FROM AUTHOR]

Background: New therapeutic targets are needed to fight aging-related diseases and increase life span. A new female-specific association with diseases and limited survival past 80 years was recently reported for a copy number variation (CNV) in the CNTNAP4 gene from the neurexin superfamily. Objective: We asked whether there are CNVs that are associated with aging phenotypes within other genes from the neurexin superfamily and whether this association is sex specific. Methods: Select CNV polymorphisms were genotyped with proprietary TaqMan qPCR assays. Results: A case/control study, in which a group of 81- to 90-year-old community-dwelling Caucasians with no chronic diseases (case) was compared to a similar control group of 65- to 75-year-olds, revealed a negative association with healthy aging for the ins allele of common esv11910 CNV in the CNTNAP2 gene (n = 388; OR = 0.29, 95% CI: 0.14-0.59, p = 0.0004 for males, and OR = 0.82, 95% CI: 0.42-1.57, p = 0.625 for females). This male-specific association was validated in a study of an independent group of 76- to 80-year-olds. To look for a corresponding positive association of the allele with aging-related diseases, two case subgroups of 81- to 90-year-olds, one composed of individuals with cognitive impairment and the other with various diseases not directly related to the nervous system, such as cardiovascular diseases, etc., were compared to a healthy control subgroup of the same age. A positive male-specific association was found for both cases (OR = 2.75, p = 0.008 for association with cognitive impairment, and OR = 3.18, p = 0.002 for other diseases combined). Conclusions: A new male-specific association with aging is reported for a CNV in the CNTNAP2 gene. The polymorphism might be useful for diagnosing individual genetic predispositions to healthy aging versus aging complicated by chronic diseases. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The decline of Drosophila climbing behavior is one of the common phenomena of Drosophila aging. The so-called negative geotaxis refers to the natural upward climbing behavior of Drosophila melanogaster after it oscillates to the bottom of the test tube. The strength of climbing ability is regarded as the index of aging change of D. melanogaster. At present, many laboratories use the percentage of 10 fruit flies climbing a specific height in 5 s as a general indicator of the climbing ability of fruit flies. This group research index ignores the climbing performance of a single fruit fly, and the climbing height belongs to the concept of vertical distance in physics, which cannot truly and effectively reflect the concept of curve distance in the actual climbing process of fruit flies. Therefore, based on the image processing algorithm, we added an experimental method to draw the climbing trajectory of a single fruit fly. By comparing the differences in climbing behavior of fruit flies under different sex, group or single, oscillation condition or rotation inversion condition, we can find that the K-Nearest Neighbor target detection algorithm has good applicability in fruit fly climbing experiment, and the climbing ability of fruit flies decreases with age. Under the same experimental conditions, the climbing ability of female fruit flies was greater than that of male fruit flies. The climbing track length of a single fruit fly can better reflect the climbing process of a fruit fly., (© 2022 Wiley Periodicals LLC.)

The hypothalamus contains nuclei and cell populations that are critical in reproduction and that differ significantly between the sexes in structure and function. To examine the molecular and genetic basis for these differences, we quantified gene expression in the hypothalamus of 39 pairs of adult male and female mice belonging to the BXD strains. This experimental design enabled us to define hypothalamic gene coexpression networks and provided robust estimates of absolute expression differences. As expected, sex has the strongest effect on the expression of genes on the X and Y chromosomes (e.g., Uty, Xist, Kdm6a). Transcripts associated with the endocrine system and neuropeptide signaling also differ significantly. Sex-differentiated transcripts often have well delimited expression within specific hypothalamic nuclei that have roles in reproduction. For instance, the estrogen receptor (Esr1) and neurokinin B (Tac2) genes have intense expression in the medial preoptic and arcuate nuclei and comparatively high expression in females. Despite the strong effect of sex on single transcripts, the global pattern of covariance among transcripts is well preserved, and consequently, males and females have well matched coexpression modules. However, there are sex-specific hub genes in functionally equivalent modules. For example, only in males is the Y-linked gene, Uty, a highly connected transcript in a network that regulates chromatin modification and gene transcription. In females, the X chromosome paralog, Kdm6a, takes the place of Uty in the same network. We also find significant effect of sex on genetic regulation and the same network in males and females can be associated with markedly different regulatory loci. With the exception of a few sex-specific modules, our analysis reveals a system in which sets of functionally related transcripts are organized into stable sex-independent networks that are controlled at a higher level by sex-specific modulators.

Abstract: In mammals, low-density lipoprotein receptor-related protein-2 (LRP2) is an endocytic receptor that binds multiple ligands and is essential for a wide range of physiological processes. To gain new insights into the biology of this complex protein, we have initiated the molecular characterization of the LRP2 homolog from an oviparous species, the chicken (Gallus gallus). The galline LRP2 cDNA encodes a membrane protein of 4658 residues. Overall, the galline and human proteins are 73% identical, indicating that the avian gene has been well conserved over 300million years. Unexpectedly, LRP2 transcript and protein levels in the kidney of females and estrogen-treated roosters were significantly higher than those in untreated males. The estrogen-responsiveness of avian LRP2 may be related to the dramatic differences in lipoprotein metabolism between mature roosters and laying hens. Newly identified potential estrogen-responsive elements (ERE) in the human and galline LRP2 gene, and additional Sp1 sites present in the promoter of the chicken gene, are compatible with both direct estrogen induction via the classical ligand-induced ERE pathway and the indirect transcription factor crosstalk pathway engaging the Sp1 sites. In agreement with this assumption, estrogen induction of LRP2 was observed not only in primary cultured chicken kidney cells, but also human kidney cell lines. These findings point to novel regulatory features of the LRP2 gene resulting in sex-specific receptor expression. [Copyright &y& Elsevier]

Species from the Dipteran family Chironomidae are widely used in laboratory and field studies to identify toxicity in freshwater environments. However, toxicity assessments can be influenced by food availability, which can alter endpoints in assays including viability, sex ratios and development time. The aim of this study was to determine if food limitation affected the endpoints used in toxicity tests with the Australian model organism, Chironomus tepperi, including responses in offspring. First instar larvae were subjected to food treatments with larval density controlled and offspring were either raised under the same food conditions as their parents or under standard conditions. In lower food density treatments adults in the F 0 generation experienced delayed emergence and females produced fewer egg masses. F 0 diet affected the performance of F 1 to continued exposure and there was evidence that the quality of the offspring was compromised. Although sex ratios were not skewed, males and females responded differently to food limitation, especially in the F 1 generation where female development was more delayed. These results demonstrate that endpoints used in toxicity evaluation in C. tepperi also respond to food availability, highlighting the need to control for food in both laboratory and field toxicity studies. Multiple generations should ideally be exposed to stressors under laboratory conditions to elucidate likely long term effects in the field. [Copyright &y& Elsevier]

Abstract: Recent functional neuroimaging studies have suggested that specific brain regions might be associated with the formation of anxiety-related personality traits, which are well known to be influenced by gender. Such anxiety-related personality traits are one of the representative predisposing factors for mood and anxiety disorders, whose incidence is also known to be much influenced by gender. However, little is known about the gender differences in brain function related to anxiety-related personality traits. The aim of the present study was to examine gender-related differences in the pattern of the relationships between an anxiety-related personality trait and cerebral brain glucose metabolism. Regional brain glucose metabolism was measured using [18F]fluorodeoxyglucose positron emission tomography in 102 healthy subjects (65 males and 37 females). An anxiety-related trait was assessed using the Temperament and Character Inventory dimension Harm Avoidance (HA). HA was negatively correlated with glucose metabolism in the anterior portion of the ventromedial prefrontal cortex (vmPFC) in females but not in males. The anterior vmPFC may be a possible neural target for the prevention or therapy of emotional disorders, especially in females. [Copyright &y& Elsevier]

This article discusses glucocorticoid receptor (GR) genes that have extreme bone mineral density (BMD). To study the role of the Chinese GR gene on BMD regulation, a sex-specific association study was performed. The results indicated that GR variation contributed to the extreme BMD variation in the Chinese.

The article discusses the results of a study examining the effect of giving isoflavone-rich fermented soy bean extract (FSBE) on the serum cholesterol concentrations of male and intact ovariectomized (OVX) female rats. The FSBE decreased the serum concentrations of the intact female and OVX rats. The FSBE had no effect on the male rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor gene expression of the intact female rats, but did not effect the OVX rats.

A portion of the 5′-flanking region of the female-specific hexamerin gene, Hex-1.2, from the mosquito Ochlerotatus atropalpus was used to drive expression of the luciferase reporter gene in Drosophila melanogaster. The proximal 0.7 kb of 5′-flanking DNA were sufficient to partially repress reporter gene activity in males and to drive tissue- and stage-specific expression comparable with that of the endogenous O. atropalpus Hex-1.2 gene. The Drosophila doublesex transcription factor (DSX), expressed in Escherichia coli, bound putative DSX sites of the Hex-1.2 gene differentially in vitro. Blocking expression of the female isoform of the Doublesex transcription factor in transgenic female flies resulted in reduction of luciferase expression to levels comparable with those in males, suggesting that Doublesex could contribute to regulation of female-specific expression of the O. atropalpus Hex-1.2 gene. [ABSTRACT FROM AUTHOR]

Abstract: 17β-Estradiol (E2) regulates growth-plate chondrocyte differentiation in a gender and cell maturation-dependent manner via classic nuclear receptors ERα and ERβ, and membrane-associated signalling. Here we show that sex-specific effects of E2 involve changes in intracellular calcium concentration (ICCC). Resting-zone chondrocytes (RC) and growth-zone chondrocytes (GC) were isolated from costochondral cartilage of male and female rats. Confluent cultures were treated with 10−8 M E2 or 17α-estradiol in the presence of high and low extracellular Ca2+ concentration. The ICCC was determined using laser scanning confocal microscopy to measure changes in Fluo-4 fluorescence every 5s for a total of 500s. E2 increased ICCC in the cells from female rats but had no effect on ICCC in male cells. The effect was rapid (peak at 140s) and stereospecific. E2 increased ICCC in RC and GC chondrocytes but the effect was greater in RC cells. Low Ca2+ media did not abolish the E2-dependent ICCC elevation, nor did inclusion of verapamil, which inhibits Ca2+ channels on the cell membrane. Thapsigargin reduced the effect of E2 on ICCC, showing that Ca2+ pumps on the endoplasmic reticulum were involved. Pre-treatment of the cells with the ER antagonist ICI 182780 did not alter the stimulatory effect of E2, suggesting that traditional estrogen receptor mechanisms do not play a role. E2 caused rapid production of inositol-1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) but only in female cells, and the effect was greater in RC chondrocytes. These results indicate that E2 regulates ICCC in a sex-specific and cell maturation state-dependent manner. The mechanism is membrane-associated and is mediated by PLC-dependent IP3 production and release of Ca2+ from the endoplasmic reticulum. [Copyright &y& Elsevier]

Acute effects of the endocrine disruptor bis(tri-n-butyltin) oxide (TBTO) on molting-hormone biosynthesis and imaginaldisc development were investigated in larvae of the midge Chironomus riparius (Meigen). Ecdysteroid synthesis was measured by 24-h incubation of molting-hormone-synthesizing tissues (prothoracic glands) in vitro with or without the addition of TBTO. The amount of ecdysteroids produced was analyzed by radioimmunoassay. Developmental effects in vivo were investigated by determining the developmental phase of the genital imaginal discs before and after a 48-h exposure to TBTO in water. Sex-specific effects were found with both endpoints. Ecdysteroid synthesis was significantly reduced (analysis of variance [ANOVA], p ≤ 0.005) in female larvae at all concentrations (TBTO-Sn at 50, 500, and 5,000 ng/L), whereas a significant elevation of the biosynthesis rate occurred in male larvae in the 500-ng/L treatment (ANOVA, p ≤ 0.05). In vivo experiments with development of the genital imaginal disc within a 48-h exposure period revealed a significantly slower development in female larvae and a significantly faster development in male larvae (contingency tables, p ≤ 0.001) at all concentrations tested (TBTO-Sn at 10, 50, 200, and 1,000 ng/ L). These results partly coincided with the in vitro effects on molting-hormone synthesis. The 48-h median lethal concentration (LC50) was 25 μg/L (20-30 μg/L 95% confidence intervals). The combination of in vitro and in vivo methods has proven to be a useful approach for the detection of endocrine effects of TBTO in C. riparius at levels 2,000-fold below the LC50 value. High sensitivity and short test duration suggest that chironomids may have potential as freshwater sentinel organisms for endocrinedisrupting chemicals. [ABSTRACT FROM AUTHOR]