Constitutional delay of growth and puberty in female mice is induced by circadian rhythm disruption in utero.

Constitutional delay of growth and puberty (CDGP) refers to the late onset of puberty. CDGP is associated with poor psychosocial outcomes and elevated risk of cardiovascular and osteoporotic diseases, especially in women. The environmental factors that contribute to CDGP are poorly understood. Here, we investigated the effects of chronic circadian disturbance (CCD) during the fetal stage on the pubertal development of female mice. Compared to non-stressed female (NS-F) mice that were not exposed to CCD in utero, adolescent CCD female (CCD-F) mice exhibited phenotypes that were consistent with CDGP, including lower body weight, reduced levels of circulating gonadal hormones, decreased expression of gonadal hormones and steroid synthesis-related enzymes in the ovary and hypothalamus, irregular estrus cycles, and tardive vaginal introitus initial opening (VO) days (equivalent to the menarche). Phenotypic differences in the above-noted parameters were not observed in CCD-F mice once they had reached adulthood. The expression of genes involved in fatty acid metabolism was perturbed in the ovary and hypothalamus of CCD-F mice. In addition, the ovaries of these animals exhibited altered diurnal expression profiles of circadian clock genes. Together, our findings not only suggest that CCD during fetal development may result in delayed puberty in female mice, they also offer insights on potential mechanisms that underlie CDGP.

Silica Nanoparticles Disturb Ion Channels and Transmembrane Potentials of Cardiomyocytes and Induce Lethal Arrhythmias in Mice.

BACKGROUND: The toxicity of silica nanoparticles (SiNPs) on cardiac electrophysiology has seldom been evaluated. METHODS: Patch-clamp was used to investigate the acute effects of SiNP-100 (100 nm) and SiNP-20 (20 nm) on the transmembrane potentials (TMPs) and ion channels in cultured neonatal mouse ventricular myocytes. Calcium mobilization in vitro, cardiomyocyte ROS generation, and LDH leakage after exposure to SiNPs in vitro and in vivo were measured using a microplate reader. Surface electrocardiograms were recorded in adult mice to evaluate the arrhythmogenic effects of SiNPs in vivo. SiNP endocytosis was observed using transmission electron microscopy. RESULTS: Within 30 min, both SiNPs (10-8-10-6 g/mL) did not affect the resting potential and IK1 channels. SiNP-100 increased the action potential amplitude (APA) and the INa current density, but SiNP-20 decreased APA and INa density. SiNP-100 prolonged the action potential duration (APD) and decreased the Ito current density, while SiNP-20 prolonged or shortened the APD, depending on exposure concentrations and increased Ito density. Both SiNPs (10-6 g/mL) induced calcium mobilization but did not increase ROS and LDH levels and were not endocytosed within 10 min in cardiomyocytes in vitro. In vivo, SiNP-100 (4-10 mg/kg) and SiNP-20 (4-30 mg/kg) did not elevate myocardial ROS but increased LDH levels depending on dose and exposure time. The same higher dose of SiNPs (intravenously injected) induced tachyarrhythmias and lethal bradyarrhythmias within 90 min in adult mice. CONCLUSION: SiNPs (i) exert rapid toxic effects on the TMPs of cardiomyocytes in vitro largely owing to their direct interfering effects on the INa and Ito channels and Ca2+ homeostasis but not IK1 channels and ROS levels, and (ii) induce tachyarrhythmias and lethal bradyarrhythmias in vivo. SiNP-100 is more toxic than SiNP-20 on cardiac electrophysiology, and the toxicity mechanism is likely more complicated in vivo.

Distribution and association study in copy number variation of KCNJ12 gene across four Chinese cattle populations.

Copy number variation is a large genome variation which usually happens in the noncoding-region, and it may occur at the locus associated with the functional gene to further influence the phenotype. Potassium inwardly-rectifying channel, subfamily J 12 (KCNJ12) gene expressed widely in cardiomyocytes and neurons, plays an important role in tumor therapy and muscle movement regulation. In this study, we detected the distribution of CNVs for KCNJ12 gene in 404 individuals belonging to four Chinese cattle breeds (NY, JX, JA and GF). We also investigated the KCNJ12 gene expression in different tissues of JX cattle. Additionally, we examined the association of two CNV regions (CNV1: 1,600 bp, intron 1; CNV2: 4,800 bp, intergenic) with growth traits. The statistical analyses indicated that the CNV1 is associated with the body length, rump length and weight in JX cattle population (P < 0.05); and there has a significant association with the body length, chest circumference, and body weight in GF cattle (P < 0.05).The CNV2 had a significant effect on the body length and body weight in JX cattle (P < 0.05); the body length, chest circumference, rump length and body weight in GF cattle (P < 0.01 or P < 0.05). The copy numbers of KCNJ12 gene presented the negative correlations with the transcript level of gene in skeletal muscles (P < 0.05). Our results provide evidence that CNV1 and CNV 2 in KCNJ12 are associated with growth traits in two cattle populations and may be used as candidates for marker-assisted selection and breeding management in cattle.

[Study on relationship between endogenous androgens and insulin resistance at the different stages of postmenopause].

OBJECTIVE: To investigate the relationship between insulin resistance and endogenous androgens at early and late phase of postmenopause. METHODS: A total of 105 women with early postmenopause ( ≤ 5 years since menopause) and 107 women with late postmenopause ( ≥ 10 years since menopause) were enrolled in this study.In the mean time, those women were classified into normal weight[body mass index (BMI), BMI <24 kg/m(2)] group and overweight (BMI ≥ 24 kg/m(2)) group.Sex hormone-binding globulin (SHBG), testosterone (T) , dehydroepiandrosterone-sulfate (DHEA-S) , fasting blood glucose(FBG), fasting insulin (FINS) levels were measured and then calculated free androgen index (FAI) and homeostatic model assessment of insulin resistance (HOMA-IR) . The relationship between sex hormones and insulin resistance was analyzed by partial correlation and multiple linear regression analyses. RESULTS: Compared to early postmenopausal women, late postmenopausal women had higher FINS [(7.9 ± 6.6) mU/L versus (6.6 ± 4.0) mU/L] and HOMA-IR(2.1 ± 1.9 versus 1.7 ± 1.1), but they had lower DHEA-S[(0.9 ± 0.5) mg/L versus (1.1 ± 0.5) mg/L, all P < 0.05) ]. Both in early postmenopausal and late postmenopausal groups, overweight women had higher HOMA-IR (early group, 2.2 ± 1.0 versus 1.2 ± 0.9;late group, 2.8 ± 2.6 versus 1.6 ± 1.1) and FINS early group[(6.9 ± 2.9) mU/L versus (4.6 ± 2.0) mU/L];late group[(10.2 ± 9.3) mU/L versus (6.4 ± 3.6) mU/L] than those at women with normal weight group (all P < 0.05) .In early postmenopausal group, overweight women had lower SHBG[ (52 ± 37) nmol/L versus (71 ± 37) nmol/L] and higher FAI (2.5 ± 2.1) versus (1.3 ± 1.1) than those at normal weight women group (all P < 0.05) .In late postmenopausal group, overweight women had higher DHEA-S (1.0 ± 0.5) mg/L versus (0.8 ± 0.4) mg/L (P < 0.05) . The analyses suggested that in early postmenopausal group, SHBG was correlated negatively with FINS and HOMA-IR (ß = -0.386, P < 0.05;ß = -0.553, P < 0.05) , DHEA-S was correlated positively with FBG (ß = 0.348, P < 0.05) in early postmenopausal group.FAI was correlated positively with FBG in late postmenopausal group (ß = 0.505, P < 0.05) . CONCLUSIONS: The increased androgenic activities are associated with insulin resistance after of menopause. These correlations are different at different stages of postmenopause, which SHBG levels correlate with high risk of insulin resistance and DHEA-S levels correlates with high blood glucose levels at early postmenopause and FAI correlates with high blood glucose levels at late postmenopause.

Two trypsin isoforms from the intestine of the grass carp (Ctenopharyngodon idellus).

Two trypsin isoforms (GT-A and GT-B) from the grass carp (Ctenopharyngodon idellus) intestine were isolated and purified. SDS-PAGE electrophoresis showed that GT-A and GT-B had relative molecular masses of 30,740 and 26,400, respectively. Enzyme activity was inhibited by three organic trypsin inhibitors but not by EDTA. They had optimal pH of 8.0 and 8.5, and optimal temperatures of 38.5 and 44.0 degrees C, respectively, when hydrolyzing N-benzoyl-L: -arginine ethyl ester.HCl (BAEE). They lost 95.8 and 93.7% of their activities, respectively, after heating for 20 min at 65 degrees C. Their thermal denaturation temperatures, respectively, were 66.3 and 67.3 degrees C. GT-A has a K(m) value of 21.2 microM and a V(max) of 2.0 x 10(3) min(-1), and GT-B has a K(m) value of 31.7 microM and a V(max) of 3.3 x 10(3) min(-1). Their physiological efficiencies were 94.3 and 105.3 microM(-1) min(-1), respectively. The Arrhenius activation energies of GT-A and GT-B were 4.16 and 4.38 kcal/mol, respectively. The activities of GT-A and GT-B were not activated by Ca(2+), but their thermostability was improved in the presence of Ca(2+). Enzyme activity was reduced in presence of Zn(2+), Cu(2+), Hg(2+) and Al(3+). Thermal stabilities of GT-A and GT-B were intermediate between Arctic and tropical fish species, and consistent with the wide range of water temperatures to which grass carp are exposed in most provinces of China.