The possibly role of GnIH in stress and gut dysfunction in chicken.

Stress is known to disrupt the intestinal barrier and induce intestinal dysfunction. A critical role for gonadotropin inhibitory hormone (GnIH) in stress has emerged. However, whether GnIH mediates stress-induced intestinal dysfunction remains unknown. The present study explored this question through in vivo and in vitro experiments in hens. Our in vivo experiments showed that continuous intraperitoneal injection of GnIH not only significantly increased the concentration of stress hormones in serum, but also significantly elevated the mRNA expression of glucocorticoid receptor (GR) in the duodenum and jejunum. Moreover, morphological and molecular analyses revealed that GnIH disrupted the physical and chemical barriers of the intestine and dramatically increased inflammatory factor levels in the intestine and serum of hens. Interestingly, the microbiomics results showed that GnIH altered the structure and composition of the gut flora in the cecum, revealing an increased abundance of harmful intestinal bacteria such as Desulfovibrionaceae. Similar results were found in in vitro studies in which the GnIH-induced intestinal mucosal barrier was disrupted, and inflammation increased in jejunal explants, although no significant difference was found in the expression of GR between the control and GnIH groups. Our results demonstrated that GnIH not only directly damaged intestinal barriers and elevated intestinal inflammation but also mediated stress and microflora imbalance-induced intestinal function disorder, suggesting that GnIH is a potential therapeutic target for gut dysfunction, stress-induced intestinal function disorder, and inflammatory bowel disease in animals and humans.

Peripheral 5-HT Mediates Gonadotropin-Inhibitory Hormone-Induced Feeding Behavior and Energy Metabolism Disorder in Chickens via the 5-HT2C Receptor.

INTRODUCTION: Since the discovery of gonadotropin-inhibitory hormone (GnIH), it has been found to play a critical role in reproduction in vertebrates. Recently, a regulatory role of GnIH in appetite and energy metabolism has emerged, although its precise physiological mechanisms remain unknown. METHODS: Thus, the present study evaluated the effects of a single or long-term intraperitoneal GnIH treatment on the food intake, weight, and glucolipid metabolism of chickens, as well as investigating the possible neuroendocrinology factors and mechanisms involved in GnIH-induced obesity and glucolipid metabolism disorder. RESULTS: Our results show that the intraperitoneal administration of GnIH to chickens resulted in a marked body mass increase, hyperlipidemia, hyperglycemia, and glucose intolerance. Subsequently, the results of metabolomics studies and the pharmacological inhibition of the 5-HT2C receptor revealed that blocking the 5-HT2C receptor reinforced the effects of GnIH on food intake, body weight, and blood glucose and lipid levels, resulting in even worse cases of GnIH-induced hyperglycemia, hyperlipidemia, and hepatic lipid deposition. This suggests that, via the 5-HT2C receptor, peripheral 5-HT may act as a negative feedback regulator to interplay with GnIH and jointly control energy balance homeostasis in chickens. DISCUSSION: Our present study provides evidence of cross-talk between GnIH and 5-HT in food intake and energy metabolism at the in vivo pharmacological level, and it proposes a molecular basis for these interactions, suggesting that functional interactions between GnIH and 5-HT may open new avenues for understanding the mechanism of the neuroendocrine network involved in appetite and energy metabolism, as well as providing a new therapeutic strategy to prevent obesity, diabetes, and metabolic disorders.

The moderating role of estradiol in the relationship between parenting styles and preschool children s behavioral problems / 中国学校卫生

Objective@#To explore the moderating role of estradiol in the relationship between parenting styles and preschool children's behavioral problems, so as to provide a theoretical basis for improving the development of human s emotional health development in early life stage.@*Methods@#During September to November in 2022, 354 children aged 3-6 years and their parents from two kindergartens in Bengbu City were chosen by using stratified cluster sampling method for the questionnaire survey. The Parenting Style Scale and the Child Behavior Checklist (CBCL) were used to collect information on parenting style and child behavioral problems. Salivary estradiol of children was collected and tested. Independent samples t test was applied to compare the scores of the scale for parental up bringing and children s behavioral problems, and Pearson correlation analysis was conducted to explore the relationship among parental upbringing, estradiol and children s behavioral problems.@*Results@#Parents doting, laissez faire, autocratic, and inconsistent parenting styles were positive associated with child behavior problems( r =0.14-0.70); fathers democratic parenting style was negatively associated with child behavior problems( r =-0.14，-0.22，-0.21，-0.17，-0.27，-0.20); mothers democratic parenting styles was negatively correlated with scores on all five dimensions of child behavior problems except the withdrawal dimension ( r =-0.14，-0.12，-0.13，-0.21，-0.12)( P <0.05). Estradiol levels had significant moderating effects on maternal doting parenting style and children s withdrawal ( β =0.68) as well as social problems ( β =-1.00), also moderating laissez faire parenting styles and children s withdrawal problems ( β =0.75)( P <0.05). For children with low levels of estradiol, withdrawal problem scores were negatively associated with mother s doting parenting style and positively associated with laissez faire parenting style, and socialization problem scores were associated with mother s doting parenting style; for children with high levels of estradiol, withdrawal problem scores were positively associated with mother s doting parenting style, and socialization problem scores were associated with mother s doting parenting style ( t=2.84, 6.24, 3.16 , 2.37, 4.49, P <0.05).@*Conclusions@#Parenting styles are strongly associated with child behavioral problems; estradiol levels play a moderating role in mothers doting, laissez faire parenting styles and children s withdrawal problems and social problems.Parents should adopt more positive parenting styles and focus on the role of estradiol levels in maternal education to reduce the occurrence of behavioral problems in children.

The associations between 2D:4D ratio and behavior problems among Chinese preschool children: A cross-sectional study.

BACKGROUND: Digit ratio (2D:4D) is considered a biomarker of prenatal androgen activity, the prenatal hormone exposure may affect children's psychology and behavior. OBJECTIVE: The aim of this study was to analyze the associations between 2D:4D ratio and behavior problems in Chinese preschool children, and to provide ideas for early intervention of children's behavior problems. METHODS: A total of 548 Chinese preschool children aged 3-6 years were recruited using a stratified cluster sampling method. The Child Behavior Checklist (CBCL) was used to assess the children's behavior. Basic information of the children and their parents was also collected, finger length was directly measured by electronic vernier caliper. RESULTS: We found that sex and age of the child, mother's educational level, and whether the child was an only child were the influencing factors of behavior problems (P < 0.05). Right-handed 2D:4D was negatively correlated with parent-reported anxiety/depression (P < 0.05), father-reported aggression (P < 0.05) and attention problems (P < 0.01), that is, high levels of testosterone may increase the risk of anxiety and depression, our results were in contrast to previous studies. CONCLUSION: The 2D:4D ratio may be related to behavior problems among Chinese preschool children, and prenatal testosterone exposure may be an important factor affecting behavior problems.

Peripheral Gonadotropin-Inhibitory Hormone (GnIH) Acting as a Novel Modulator Involved in Hyperphagia-Induced Obesity and Associated Disorders of Metabolism in an In Vivo Female Piglet Model.

Apart from the well-established role of the gonadotropin-inhibitory hormone (GnIH) in the regulation of the reproductive functions, much less is known about the peripheral role of the GnIH and its receptor in the metabolic processes. On account of pig being an excellent model for studies of food intake and obesity in humans, we investigated the peripheral effects of the GnIH on food intake and energy homeostasis and revealed the underlying mechanism(s) in female piglets in vivo. Compared to the vehicle-treated group, intraperitoneally injected GnIH significantly increased the food intake and altered the meal microstructure both in the fasting and ad libitum female piglet. GnIH-triggered hyperphagia induced female piglet obesity and altered islet hormone secretion in the pancreas, accompanied with dyslipidemia and hyperglycemia. Interestingly, GnIH decreased the glucose transport capacity and glycogen synthesis, whereas it increased the gluconeogenesis in the liver, while it also induced an insulin resistance in white adipose tissue (WAT) via inhibiting the activity of AKT-GSK3-ß signaling. In terms of the lipid metabolism, GnIH reduced the oxidation of fatty acids, whereas the elevated fat synthesis ability in the liver and WAT was developed though the inhibited AMPK phosphorylation. Our findings demonstrate that peripheral GnIH could trigger hyperphagia-induced obesity and an associated glycolipid metabolism disorder in female piglets, suggesting that GnIH may act as a potential therapeutic agent for metabolic syndrome, obesity and diabetes.

Possible Role of GnIH as a Novel Link between Hyperphagia-Induced Obesity-Related Metabolic Derangements and Hypogonadism in Male Mice.

Gonadotropin-inhibitory hormone (GnIH) is a reproductive inhibitor and an endogenous orexigenic neuropeptide that may be involved in energy homeostasis and reproduction. However, whether GnIH is a molecular signal link of metabolism and the reproductive system, and thus, regulates reproductive activity as a function of the energy state, is still unknown. In the present study, we investigated the involvement of GnIH in glycolipid metabolism and reproduction in vivo, and in the coupling between these two processes in the testis level. Our results showed that chronic intraperitoneal injection of GnIH into male mice not only increased food intake and altered meal microstructure but also significantly elevated body mass due to the increased mass of liver and epididymal white adipose tissue (eWAT), despite the loss of testicular weight. Furthermore, chronic intraperitoneal administration of GnIH to male mice resulted in obesity-related glycolipid metabolic derangements, showing hyperlipidemia, hyperglycemia, glucose intolerance, and insulin resistance through changes in the expression of glucose and lipid metabolism-related genes in the pancreas and eWAT, respectively. Interestingly, the expression of GnIH and GPR147 was markedly increased in the testis of mice under conditions of energy imbalance, such as fasting, acute hypoglycemia, and hyperglycemia. In addition, chronic GnIH injection markedly inhibited glucose and lipid metabolism of mice testis while significantly decreasing testosterone synthesis and sperm quality, inducing hypogonadism. These observations indicated that orexigenic GnIH triggers hyperphagia-induced obesity-related metabolic derangements and hypogonadism in male mice, suggesting that GnIH is an emerging candidate for coupling metabolism and fertility by involvement in obesity and metabolic disorder-induced reproductive dysfunction of the testes.

Effect of RFRP-3, the mammalian ortholog of GnIH, on apoptosis and autophagy in porcine ovarian granulosa cells via the p38MAPK pathway.

RFamide-related peptide-3 (RFRP-3) has been proposed as a key inhibitory regulator of mammalian reproduction. Our previous studies demonstrated that RFRP-3 mediated apoptosis and autophagy of the epididymis in rats and inhibited porcine granulosa cell (GC) proliferation. However, the molecular mechanisms of the RFRP-3 effect on porcine GC apoptosis and autophagy have not been studied before. Herein, we first investigated the role of RFRP-3 in apoptosis and autophagy in cultured porcine GCs in vitro. Our results showed that different doses of RFRP-3 dose-dependently elevated the expression of autophagy markers at both the mRNA and protein levels, whereas the expression of apoptosis markers exhibited a bidirectional, dose-dependent effect. Because the p38MAPK signaling pathway plays essential roles in apoptosis and autophagy, we subsequently evaluated the effect of RFRP-3 on p38MAPK activation. The results showed that 10-6 M RFRP-3 treatment not only significantly decreased p38MAPK phosphorylation but also inhibited the p38MAPK activator U-46619 to promote p38MAPK activation in porcine GCs. Finally, we applied U-46619 to investigate the role of the p38MAPK signaling pathway in apoptosis and autophagy in RFRP-3-treated porcine GCs. The results showed that all doses of RFRP-3 significantly inhibited the U-46619-induced increase in apoptosis in a dose-dependent manner. However, except for the U-46619-induced Beclin-1 expression increase, which was significantly suppressed in high-dose RFRP-3-treated porcine GCs, other doses of RFRP-3 treatment strengthened the U-46619-induced increase in other autophagy markers. In summary, our data demonstrate a critical role for the p38MAPK signaling pathway in the porcine GC cellular response to RFRP-3 by controlling the balance between apoptosis and autophagy.

Extensive antimicrobial resistance and plasmid-carrying resistance genes in mcr-1-positive E. coli sampled in swine, in Guangxi, South China.

BACKGROUND: The discovery of the superbug mcr-1-positive Escherichia coli (MCRPEC) has drew greet attention. Swine-origin multi-drug resistant MCRPEC has been a potential threat to public health and safety. However, there were few detailed studies have been reported on swine MCRPEC in Guangxi, South China. RESULTS: In this study, thirty-three MCRPEC strains were detected from 142 E. coli strains from 116 samples in Guangxi in 2018. Which could be classified into eight unique STs and a total of six incompatibility plasmid groups (IncFI, IncHI1, IncY, IncN, IncI1 and IncX1). After that, the susceptibility of MCRPEC isolates to 27 antimicrobial agents belonging to 17 antimicrobial categories was tested. There were nineteen E. coli resistant to 3rd and 4th generation cephalosporins and twelve E. coli resistant to carbapenem resistan. Importantly, the MCRPEC showed high resistance highly resistance for imipenem and meropenem, which were forbidden to use in livestock production. Three MCRPEC strains were further proved to be extensively drug-resistant (XDR), and the other isolates were multi-drug-resistant (MDR). Furthermore, we found that the plasmid-carrying resistance genes coexisted with the mcr-1 gene of the MCRPEC isolates. Which were listed as follows: ß-lactamase antimicrobial resistance genes e.g. ESBL genes (blaCTX-M14, blaCTX-M24, blaCTX-M123, blaOXA-1), plasmid-mediated AmpC (pAmpC) gene (blaCMY-2), the carbapenem resistance gene (blaNDM-5), and non-ß-lactamase antimicrobial resistance genes (qnrA, qnrB, qnrS, aac (6')-Ib-cr, tetA, tetB, sul1, sul2, floR, aadA). CONCLUSION: Thirty-three mcr-1-positive E. coli isolates in Guangxi displayed a wide profile of antimicrobial resistance. Plasmid-carrying resistance genes might be the main cause of MCRPEC multidrug resistance. This study highlighted the necessity for long-term surveillance of mcr-1-positive E. coli in pigs.

RFRP-3, the Mammalian Ortholog of GnIH, Is a Novel Modulator Involved in Food Intake and Glucose Homeostasis.

RF amide-related peptide 3 (RFRP-3) is a reproductive inhibitor and an endogenous orexigenic neuropeptide that may be involved in energy homeostasis. In this study, we evaluated the effect of acute or chronic RFRP-3 treatment (administered via intraperitoneal injection) on the food intake, meal microstructure and weight of rats, as well as the mechanism through which RFRP-3 is involved in glucose metabolism in the pancreas and glucose disposal tissues of rat in vivo. Our results showed that the intraperitoneal administration of RFRP-3 to rats resulted in marked body mass increased, hyperphagia, hyperlipidemia, hyperglycemia, glucose intolerance, hypoinsulinism, hyperglucagon, and insulin resistance, as well as significant increases in the size of pancreatic islets and the inflammatory reaction. Thus, we strongly assert that RFRP-3 as a novel neuroendocrine regulator involved in blood glucose homeostasis.

Association between Serum Copper and Serum Lipids in Adults.

BACKGROUND: As an essential trace element, copper has been considered to play an important role in lipid metabolism. However, the associations of serum copper with lipid concentration and dyslipidemia are still controversial. METHODS: We used the 2011-2014 National Health and Nutrition Examination Survey to examine the relationship between serum copper and lipid concentration among participants aged 20 years and older. Multivariate linear regression was conducted to estimate the differences in the level of total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol. Logistic regression was conducted to examine the association between serum copper and the risk of dyslipidemia. RESULTS: A total of 2,678 subjects were eligible for our analyses. The multivariable adjusted average differences (95% CIs) comparing the highest to the lowest copper tertile were 8.42 (1.45-15.38) mg/dL for TC, and 2.96 (0.02-5.90) mg/dL for HDL cholesterol. Compared with the lowest tertile of serum copper, participants had significantly higher risks of High-TC dyslipidemia (OR 1.46; 95% CI 1.02-2.08) in tertile 3 and High-LDL cholesterol dyslipidemia (OR 1.48; 95% CI 1.03-2.14) in tertile 2 after adjusting for covariates. In the stratified analyses, we found that the copper-dyslipidemia association was statistically significant in women and subjects younger than 45 years of age. CONCLUSION: High serum copper was associated with elevated serum concentrations of TC and HDL cholesterol, and was associated with increased risks of High-TC and High-LDL cholesterol dyslipidemia. However, the real association between serum copper and serum lipids should be verified in larger prospective cohort studies in -future.

Exploration of the association between dietary fiber intake and depressive symptoms in adults.

OBJECTIVE: Current evidence on the association between dietary fiber intake and the risk of depressive symptoms is inconsistent. Thus, the purpose of the present study was to explore their association. METHODS: Data from the National Health and Nutrition Examination Survey 2007 to 2014 were used in this cross-sectional study. Dietary data were obtained through two 24-h dietary recall interviews. Depressive symptoms were assessed using Patient Health Questionnaire. Logistic regression models and restricted cubic spline models were applied to evaluate the associations among dietary intakes of total, cereal, vegetable, and fruit fiber and depressive symptoms. RESULTS: A total of 16 807 adults ages 20 y or older were included in this study. Dietary intakes of total, cereal, vegetable, and fruit fiber were inversely associated with depressive symptoms in unadjusted model and multivariate-adjusted model 1. In multivariate-adjusted model 2, the odds ratios (95% confidence intervals) of depressive symptoms were 0.59 (0.44-0.79), 0.90 (0.69-1.19), 0.58 (0.45-0.76), and 0.64 (0.45-0.92) for the highest versus lowest quartile of total, cereal, vegetable, and fruit fiber intakes, respectively. Dose-response analyses found that the risk of depressive symptoms was associated with total fiber intake in a nonlinear manner, whereas the relationships were linear with cereal, vegetable, and fruit fiber intakes. CONCLUSIONS: Our study suggested that intakes of total fiber, vegetable fiber, and fruit fiber were inversely associated with depressive symptoms. Further larger prospective studies are needed to confirm our findings.

Association of total zinc, iron, copper and selenium intakes with depression in the US adults.

BACKGROUND: The aim of present study was to examine the associations of total zinc, iron, copper and selenium intakes from diet and supplements with depression. METHODS: Cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 2009-2014 in the present study. Logistic regression models and restricted cubic spline models were applied to examine the associations of total zinc, iron, copper and selenium intakes with depression. RESULTS: A total of 14834 adults aged 18 years or older (7399 men and 7435 women) were included in the present study. Total zinc, iron, copper and selenium intakes were inversely associated with depression in unadjusted model and age- and gender-adjusted model. The multivariate adjusted odds ratios (ORs) with 95% confidence intervals (CIs) of depression were 0.68 (0.49-0.94) and 0.46 (0.32-0.67) for the highest versus lowest quartile of copper and selenium intakes, respectively. The inverse associations of depression were statistically significant for the quartile 3 versus lowest quartile of total zinc (OR: 0.70; 95% CI: 0.49-0.99) and iron intake (OR: 0.66 95% CI: 0.50-0.87). Compared to those below the RDA (Recommended Dietary Allowance), participants who met the RDA for zinc (OR: 0.74; 95% CI: 0.56-0.99), copper (OR: 0.68; 95% CI: 0.56-0.82) and selenium (OR: 0.52; 95% CI: 0.39, 0.71) had significantly lower odds of depression. LIMITATIONS: This was a cross-sectional study, limiting causal inferences. Assessment of depression was based on a self- report scale. CONCLUSION: Total zinc, iron, copper and selenium intakes may be inversely associated with depression.

Novel carbon quantum dots from egg yolk oil and their haemostatic effects.

In this study, the properties of egg yolk oil (EYO) were investigated. Water extraction, dialysis, and ultrafiltration were used to extract and purify EYO, and microscopy, spectrophotometry, and chromatography were used to identify carbon dots (CDs) present in EYO (EYO CDs). Morphology analyses demonstrated that CDs were almost spherical, with an average size of <10 nm, a lattice spacing of 0.267 nm, and a composition of mainly C, O, and Fe. The solution showed bright blue fluorescence at 365 nm. Tail haemorrhaging and liver haemorrhaging experiments showed that CD-treated mice had significantly shorter bleeding times than did control mice. Coagulation assays suggested that EYO CDs stimulate the intrinsic blood coagulation system and activate the fibrinogen system. Thus, EYO CDs possess the ability to activate haemostasis, which may lead to further investigations of this ingredient of traditional Chinese medicine.

Calcium Intake and the Risk of Ovarian Cancer: A Meta-Analysis.

Several epidemiological studies have evaluated the association between calcium intake and the risk of ovarian cancer. However, the results of these studies remain controversial. Thus, we performed a meta-analysis to explore the association between calcium intake and the risk of ovarian cancer. Pubmed, Embase and Web of Science were searched for eligible publications up to April 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model. Small-study effect was estimated using Egger's test and the funnel plot. Among 15 epidemiological studies involving 493,415 participants and 7453 cases eligible for this meta-analysis, 13 studies were about dietary calcium intake, 4 studies about dairy calcium intake and 7 studies about dietary plus supplemental calcium intake. When comparing the highest with the lowest intake, the pooled RRs of ovarian cancer were 0.80 (95% CI 0.72-0.89) for dietary calcium, 0.80 (95% CI 0.66-0.98) for dairy calcium and 0.90 (95% CI 0.65-1.24) for dietary plus supplemental calcium, respectively. Dietary calcium was significantly associated with a reduced risk of ovarian cancer among cohort studies (RR = 0.86, 95% CI 0.74-0.99) and among case-control studies (RR = 0.75, 95% CI 0.64-0.89). In subgroup analysis by ovarian cancer subtypes, we found a statistically significant association between the dietary calcium (RR = 0.78, 95% CI 0.69-0.88) and the risk of epithelial ovarian cancer (EOC). This meta-analysis indicated that increased calcium intake might be inversely associated with the risk of ovarian cancer; this still needs to be confirmed by larger prospective cohort studies.

High serum copper level is associated with an increased risk of preeclampsia in Asians: A meta-analysis.

Epidemiological studies evaluating the associations between serum copper and ratios of Cu/Zn and the preeclampsia (PE) risk in Asian population have produced inconsistent results. Therefore, we conducted a meta-analysis to summarize the relationships. We hypothesize that higher serum copper and ratios of Cu/Zn may increase the PE risk. A systematic literature search was performed in PubMed, Web of Science, Embase, Chinese National Knowledge Infrastructure (CNKI), VIP (Database of Chinese Scientific and Technical Periodicals) and Wangfang databases for relevant studies up to November 2016. Pooled standardized mean difference (SMD) was calculated with random effects model. The results showed that PE patients had a higher serum copper level [SMD (95% CI): 1.05 (0.34, 1.77), Z=2.88, P for Z=0.004; I2=96.9%, P for I2<0.0001] compared with healthy pregnancy controls. In subgroup analyses, a higher serum copper level in PE patients was observed in case-control studies [SMD (95% CI): 1.39 (0.44, 2.34)]. No significant difference was found between PE patients and healthy pregnancy controls for ratios of Cu/Zn [(SMD (95% CI): 0.26 (-0.77, 1.29), Z=0.49, P for Z=0.625; I2=95.8%, P for I2<0.0001)]. In conclusion, our meta-analysis indicates that a higher serum copper level is associated with an increased risk of PE. Further studies are needed to confirm these results in future research.

Dietary zinc and iron intake and risk of depression: A meta-analysis.

The associations between dietary zinc and iron intake and risk of depression remain controversial. Thus, we carried out a meta-analysis to evaluate these associations. A systematic search was performed in PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases for relevant studies up to January 2017. Pooled relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random effects model. A total of 9 studies for dietary zinc intake and 3 studies for dietary iron intake were finally included in present meta-analysis. The pooled RRs with 95% CIs of depression for the highest versus lowest dietary zinc and iron intake were 0.67 (95% CI: 0.58-0.76) and 0.57 (95% CI: 0.34-0.95), respectively. In subgroup analysis by study design, the inverse association between dietary zinc intake and risk of depression remained significant in the cohort studies and cross-sectional studies. The pooled RRs (95% CIs) for depression did not substantially change in the influence analysis and subgroup analysis by adjustment for body mass index (BMI). The present meta-analysis indicates inverse associations between dietary zinc and iron intake and risk of depression.

Trehalose-6-phosphate and SNF1-related protein kinase 1 are involved in the first-fruit inhibition of cucumber.

In cucumber (Cucumis sativus L.), the preexisting fruits inhibit the growth of subsequent fruits. To study the mechanism underlying this phenomenon, we examined the sink activity, the level of free sugars, and the activity of SNF1-related protein kinase 1 (SnRK1) in the peduncles of two types of fruits. In the two-fruit cucumber plants, the growth rate and sink activity [evaluated by alkaline alpha-galactosidase (CsAGA) activity in the peduncle] of the first fruit were greater than those of the second fruit. The (14)C-labeling experiment revealed that assimilates produced by the leaves closer to the second fruit tended to move to the first fruit. Sucrose and trehalose-6-phosphate (T6P) levels in the peduncle of the first fruit were higher than those in the peduncle of the second fruit. The SnRK1 activity was lower in the peduncle of the first fruit than in that of the second fruit at 0-8 days after anthesis. The growth rate and sink activity of the second fruit were enhanced after the removal of the first fruit or after treatment with 6-benzyl aminopurine, as determined by comparison with an increase in the sucrose and T6P levels and a decrease in the SnRK1 activity in its peduncle. The SnRK1 activity was inhibited by T6P in an in vitro kinase assay, and the mRNA level of CsAGA1 in cucumber calli was up-regulated by exogenous trehalose treatment, confirming that the SnRK1 activity and CsAGA1 expression can be regulated by T6P levels. Our results suggest that the T6P- and SnRK1-mediated signaling functions are involved in the regulation of first-fruit inhibition in cucumber plants.

Effect of butterfly-shaped sulfur-bridged ligand and counter anions on the catalytic activity and diastereoselectivity of organobismuth complexes.

In the direct Mannich reaction and synthesis of α,ß-unsaturated ketones, the use of organobismuth complexes as catalysts leads to high diastereoselectivity and products of single trans conformation. In this paper, we illustrate the relationship between structure and catalytic activity as well as diastereoselectivity of organobismuth complexes having a 5,6,7,12-tetrahydrodibenz [c,f][1,5]thiobismocine framework as well as bearing a butterfly-shaped sulfur-bridged ligand and tunable anions. With the exposed bismuth center acting as a Lewis acid site and the uncoordinated lone pair electrons of sulfur as a Lewis base site, the cationic organobismuth complexes work as bifunctional Lewis acid/base catalysts. Due to the steric influence of the butterfly-shaped structure and synergistic effect of Lewis acid and Lewis base centers, the complexes can direct substrate attack in organic synthesis. By adjusting the electron-withdrawing ability of the counter anions, the S-Bi bond strength can be regulated, leading to a significant change in Lewis acidity and Lewis basicity as well as catalytic activity. Through synergistic modulation of the above effects, one can control the diastereoselectivity of the organobismuth complexes for the generation of a single diastereoisomer.