Schistosoma mansoni: influence of the female parasite on glutathione biosynthesis in the male

The glutathione (GSH) content of male Schistosoma mansoni increases in the absence of the female. This phenomenon, originally observed in vitro, also occurs within the host. At the time of recovery from mice, the GSH content of males from single-sex infections was 1.7-fold higher than that of paired males from mixed sex infections (P less than 0.01). The effect of mating status on male GSH biosynthetic and turnover rates was examined to determine the basis for increased GSH content in unpaired males. GSH turnover rates, measured when GSH biosynthesis was inhibited by greater than 95% with 5.0 mM DL-buthionine-SR-sulfoximine, were indistinguishable between unpaired and paired males with a first-order rate constant of 0.018 hr-1. In contrast, incorporation of L-[35S]cysteine into GSH revealed that GSH biosynthesis was 5-fold higher in unpaired than in paired males. Transport of L-cystine into male schistosomes, the presumed rate-limiting step in GSH biosynthesis, was unaffected by mating status. The GSH content increased when males were incubated in medium that had previously contained females or when separated from females by a microporous membrane. Males paired to 50% ethanol-fixed females had unchanged GSH content in vitro. It appears that male GSH biosynthesis may be regulated by a response stimulated by the female's physical presence in the gynechophoral canal and not by a soluble factor released from the female.     

Prevalence of dyslipidemia and mean blood lipid values in Taiwan: results from the Nutrition and Health Survey in Taiwan (NAHSIT, 1993-1996)

This paper reports the blood lipid status of people aged 4 years and older in Taiwan. The data is based on the Nutrition and Health Survey in Taiwan (NAHSIT: 1993-1996), which adopted a multi-stage, stratified clustering sampling scheme. Altogether, 5097 subjects (2451 males and 2646 females) had data on triglyceride and 5643 subjects (2736 males and 2907 females) had data on cholesterol. We found that (a) cholesterol levels of males were lower than females in mid-to old age group (> or = 45 years old); (b) triglyceride values of females were lower than males in young adulthood (19-44 years), but higher than males after the age of 45 years, and (c) adult females had higher HDL-C value and lower ratio of total cholesterol to HDL-C than males. The prevalence of hypercholesterolemia was 10.2% in adult males and 12.6% in mid-to-old aged men, and that in females was 11.2% and 24.4%, respectively. The prevalence of hypertriglyceridemia was 13.4% and 6.1% in adult males and females (> or = 19 years as a whole), respectively. It was 12.3% in mid-to-old aged men (> or = 45 years), and 11.9% in women. The mean cholesterol values were similar to values of several previous surveys in different areas of Taiwan. But it was higher than those in some areas of Mainland China, and lower than those of western countries. People in metropolitan cities had a higher level of blood cholesterol than other areas. The average triglyceride values of males and females were higher than those of previous studies in Taiwan and of people in Mainland China. Mountainous stratum with predominantly aboriginal residents had higher level of triglycerides and body mass index (BMI) than other strata. The associations between dietary intakes of men and women and blood lipids were examined controlling for age and BMI. Result showed that Keys score, which was derived from saturated fat, polyunsaturated fat and dietary cholesterol of a 24-hour recall, was positively related to blood cholesterol and LDL-C in men, but not in women. Average alcohol intakes per day were related to HDL-C positively, but LDL-C negatively in men and women. The regional differences in blood lipid profiles in Taiwan are consistent with the dietary and life-style variations island-wide.     

Sex, but not maternal protein or folic acid intake, determines the fatty acid composition of hepatic phospholipids, but not of triacylglycerol, in adult rats

The aim of the study was to investigate whether the protein and folic acid content of the maternal diet and the sex of the offspring alter the polyunsaturated fatty acid content of hepatic phospholipids and triacylglycerol (TAG). Pregnant rats were fed diets containing 18% or 9% protein with either 1 or 5mg/kg folic acid. Maternal diet did not alter hepatic lipid composition in the adult offspring. Data from each maternal dietary group were combined and reanalysed. The proportion of 18:0, 20:4n-6 and 22:6n-3 in liver phospholipids was higher in females than in males, while hepatic TAG composition did not differ between sexes. Delta5 Desaturase expression was higher in females than in males. Neither Delta5 nor Delta6 desaturase expression was related to polyunsaturated fatty acid concentrations. These results suggest that sex differences in liver phospholipid fatty acid composition may reflect primary differences in the specificity of phospholipid biosynthesis.     

Differences in metabolite profiles between blood matrices,ages, and sexes among Caucasian individuals and their inter-individual variations

Endobiotic metabolites are associated with biological processes in the body and therefore may serve as biomarkers for disease states or therapeutic efficacy and toxicity. However, information is limited regarding how differences between blood matrices, patient backgrounds, and sample handling affect human metabolite profiles. Our objective was to obtain metabolite profiles from Caucasian individuals, based on different matrices (plasma and serum), subject backgrounds (male/female and young/old), and storage conditions (2 or 10 freeze–thaw cycles). In total, 297 metabolites were detected by LC/MS and GC/MS, and more than 75 % of them were highly represented in all sample groups. The multivariate discriminant analysis (OPLS-DA as a model) singled out the matrix type as the most important variable influencing global metabolic profiles; that is, more than 100 metabolites were significantly different based on the matrix type. The influence of subject backgrounds on global metabolic profiles was consistent between plasma and serum. Age-associated differences were more predominant in females than males, whereas gender-associated differences were more prevalent in young subjects than old individuals were. The relative standard deviation of metabolite levels in subjects with the same background ranked from 0.1 to 1.5. Moreover, the changes of metabolite levels caused by freeze–thaw cycles were limited, and the effect was more prominent in plasma than serum. These data demonstrate the impact of matrix, age, gender, and freeze–thaw cycles on the metabolite profiles and reveal metabolites affected by these factors. Thus, our results provide would useful fundamental information for exploring and qualifying biomarkers for clinical applications.     

Noradrenergic content and turnover rate in kidney and heart shows gender and strain differences.

The objective of this study was to compare strain and gender differences in kidney and heart norepinephrine (NE) content and turnover rate in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR, SHR/a, and SHR/y). Our laboratory has shown that the Y chromosome has a significant effect on blood pressure in the SHR model of hypertension through the use of two new rat stains, SHR/a and SHR/y, to study the Y chromosome. SHR/a have a SHR autosomal genetic background with a WKY Y chromosome, whereas the SHR/y rats have a WKY autosomal genetic background with a SHR Y chromosome. Tissues were homogenized after alpha-methyl-DL-p-tyrosine injection and analyzed for NE. The male kidney NE content was significantly lower in the WKY compared with the SHR, SHR/y, and SHR/a. Kidney and heart NE content was significantly higher in females compared with males in all strains except the SHR/y. The WKY and SHR/y females had significantly lower kidney NE turnover rates, and the SHR and SHR/a females had significantly higher kidney NE turnover rates than strain-matched males. This study suggests both a strain and gender difference in sympathetic nervous system activity through noradrenergic neurotransmission.     

Sex differences in energy metabolism and performance of teleost cardiac tissue

This study examined the effects of different oxygenation levels and substrate availability on cardiac performance, metabolism, and biochemistry in sexually immature male and female rainbow trout (Oncorhynchus mykiss). Ventricle strips were electrically paced (0.5 Hz, 14 degrees C) in hyperoxic or hypoxic Ringer solution. Our results demonstrate that 1) males sustain isometric force production (F) longer than females under hyperoxia (P O2 = 640 mmHg) with exogenous glucose present; 2) contractility is not maintained under moderate (P O2 = 130 mmHg) or severe hypoxia (P O2 = 10-20 mmHg) with glucose in either sex; however, following reoxygenation, F is higher in females compared with males; and 3) female tissue has higher lactate levels, net lactate efflux, and lactate dehydrogenase activity than males, whereas males have higher glycogen, citrate synthase, and beta-hydroxy acyl-CoA dehydrogenase activities, and greater inotropic responses to exogenous glucose and octanoate. No sex differences were detected in responsiveness to epinephrine and inhibitors of glucose transport or activities of hexokinase and pyruvate kinase. We conclude that sex differences exist in rainbow trout cardiac tissue: females appear to prefer glycolysis for ATP production, whereas males have a higher capacity for aerobic and lipid metabolism.     

Regulatory effects of the L-lysine metabolites,L-2-aminoadipic acid and L-pipecolic acid,on protein turnover in C2C12 myotubes

We previously showed that L-lysine (Lys) and a metabolite of Lys, L-saccharopine, suppressed autophagic proteolysis in C2C12 myotubes. However, the effects of other metabolites of Lys on protein turnover were unknown. We here investigated the effect of the Lys metabolites, L-2-aminoadipic acid (2-AA) and L-pipecolic acid (Pip), on protein turnover in C2C12 myotubes. 2-AA suppressed myofibrillar protein degradation evaluated by the 3-methylhistidine and autophagy activity evaluated by light chain 3-II at lower concentration (100 μM) than did Lys. On the other hand, Pip stimulated the mammalian target of rapamycin signaling activity. Additionally, 100 μM Pip significantly increased the rates of protein synthesis whereas 100 μM Lys had no effect. These results indicate that in C2C12 myotubes, 2-AA could suppress autophagy and Pip could stimulate the rates of protein synthesis, and these metabolites may contribute to exert effect of Lys on protein turnover.     

Differential sex mortality in a rural nineteenth-century population: Escazu, Costa Rica.

Cross-cultural studies of sex-specific mortality indicate that, whereas males experience their greatest mortality in industrialized societies, females experience their greatest mortality in populations with low life expectancy. The higher mortality of females in low-life-expectancy communities has been interpreted as a reflection of nutritional and health-care discrimination against females. Cross-cultural demographic studies also indicate that males have a higher frequency of violent and accidental deaths, possibly because of more frequent risky behaviors. This study focuses on Escazu, a rural nineteenth-century population from Costa Rica with low life expectancy. I investigate whether Escazu males had higher violent and accidental deaths and whether females had higher diarrhea-related deaths, an indication of nutritional discrimination. An analysis of mortality by cause of death indicates that males and females did not experience significantly different diarrhea-related death rates, although males did experience greater violent mortality. This study illustrates that more anthropological community-specific studies of mortality are needed to elucidate variation of death rates within large national or international regions.     

The effects of selection for early and late reproduction on metabolite pools in Acanthoscelides obtectus Say

Abstract The present study was aimed at revealing the responses of metabolite pools to selection for alternative reproductive schedules in the seed beetle, Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae). The levels of metabolites (free sugars, glycogen, lipids, soluble and hydrophobic proteins) that were determined in virgin females and males at three ages from adult eclosion onwards were compared among the base population (B) and two derived lines that were selected for either early (Y) or late (O) reproduction. The results showed differences in the accumulation of metabolites during pre‐adult development, as well as in the pattern of their changes during adult ageing. Generally, in comparison to the B population, the short‐lived beetles from the Y line showed increased protein content and reduced carbohydrate and lipid content, whereas the opposite was true for the long‐lived beetles from the O line. Females from the O line exhibited slower utilization of energy reserves and a slower increase in protein contents than females from the Y line. Females contained higher levels of free sugars, glycogen and hydrophobic proteins and lower levels of lipids and soluble proteins than males, although the sexual dimorphism was not evenly expressed among lines. Age‐specific changes in metabolite contents were slower in females than males. Our findings suggest that trade‐offs among capital resources are a physiological basis of early/late fitness trade‐offs and point to a conservation of resources that can be used for somatic maintenance.     

Brood protection at a cost: mouth brooding under hypoxia in an African cichlid

This study quantifies the behavioral response of the widespread mouth brooding African cichlid Pseudocrenilabrus multicolor victoriae to progressive hypoxia. We exposed four gender/stage classes of P. multicolor (males, brooding females, females that had just released young, and non-brooding females) to progressive hypoxia and recorded the percent time spent using aquatic surface respiration (surface skimming, ASR) and gill ventilation rates. This was done for fish collected from three sites in Uganda (lake, swamp, and river) after long-term acclimation to normoxia. There was no effect of site of origin on response to hypoxia, but ASR thresholds did differ between gender/stage classes. The oxygen level (threshold) at which spent 10, 50, and 90% of their time at the surface using ASR was much higher for brooding females than for males, whereas ASR thresholds did not differ between non-brooding females and males. Similarly, the level at which ASR was initiated was much higher in brooding females than males, but did not differ between males and non-brooders, or between males and females than had just released young. The rate of gill ventilation dropped significantly in males and all stages of females after initiation of ASR, suggesting that surface skimming increases efficiency of oxygen acquisition. These results suggest that mouth brooding in female P. multicolor ASR improves oxygen uptake but imposes a cost in terms of time spent at the water surface, and this may affect maternal predation risk in low-oxygen habitats.