Photosynthesis and yield performance of cassava in seasonally dry and semiarid environments

Two field trials with two groups of cassava (Manihot esculenta Crantz) cultivars were conducted under rainfed conditions in seasonally dry and semiarid environments at the northern coast of Colombia, South America, to evaluate the genetic diversity in photosynthesis and productivity, and to determine their interrelationship. There were significant differences among cultivars in both environments, in average net photosynthetic rates (P _N ) of upper canopy leaves and in final dry root yields. Both P _N and dry root yields were much higher in the seasonally dry environment than in the semiarid one. Highly significant correlation (r ² = 0.90, p < 0.001) between leaf P _N and dry root yield was observed across environments, suggesting that selection in parental plants for high photosynthesis might lead to high yields if combined with other yield determinants, such as leaf area duration, high harvest index and strong root sink. This revised version was published online in August 2006 with corrections to the Cover Date.     

In vivo tissue specific modulation of rat insulin receptor gene expression in an experimental model of mineralocorticoid excess

Insulin receptor (IR) gene expression at the mRNA level was investigated in hindlimb skeletal muscle, epididymal adipose tissue and in the liver of rats exposed to prolonged in vivo administration of deoxycorticosterone acetate (DOCA). Following treatment, plasma insulin levels were reduced while glucose levels increased compared to values in control rats. DOCA-treated animals showed an increase in blood pressure and a reduction in body weight. This treatment also induced hypokalemia and decreased plasma protein levels. Sodium levels were unaffected. Moreover, no differences in DNA and protein content or in the indicator of cell size (protein/DNA) were observed in the skeletal muscle or adipose tissue of animals. In contrast, there was a clear increase in the protein and DNA contents of the liver with no change in the indicator of cell size. Northern blot assays revealed 2 major IR mRNA species of approximately 9.5 and 7.5 Kb in the 3 tissues from control animals. DOCA treatment induced no change in the levels of either RNA species in skeletal muscle. However, a decrease of approximately 22% was detected in the levels of both species in adipose tissue whereas the liver showed an increase of 64%. These results provide the first evidence for an in vivo tissue-specific modulation of IR mRNA levels under experimental conditions of mineralocorticoid excess.     

Menstrual cycle characterization and artificial insemination in the black mangabey (Cercocebus aterrimus)

Concentrations of immunoreactive estrone conjugates, pregnanediol-3-glucuronide, and luteinizing hormone were measured and indexed to creatinine in daily urine samples from three female black mangabeys (Cercocebus aterrimus). Daily observations of menstruation and perineal tumescence were recorded. The mean ± SEM lengths of the menstrual cycle [apparent cycle length of 26.0 ± 0.8 days determined by observation of intermenstrual intervals (n = 26); physiologic cycle length of 31.3 ± 5 days determined by urinary endocrine analysis (n = 4)], follicular phase [16.5 ± 4 days (n = 4)], and luteal phase [14.8 ± 1 day (n = 4)] were determined. The apparent cycle length is probably more accurate. Perineal tumescence began during or shortly after menstruation, increased concomitantly with increasing follicular phase conjugated estrone values, and reached maximal size in the periovulatory period. Ovulation was closely followed by a drop in conjugated estrone levels, an increase in urinary pregnanediol-3-glucuronide, and perineal detumescence. Peak concentrations of conjugated estrone and luteinizing hormone values were coincident. Pregnanediol-3-glucuronide accurately reflected luteal function in the black mangabey. Knowledge of the menstrual cycle parameters and their correlation to perineal tumescence was used to time artificial inseminations. Semen was obtained by rectal electroejaculation. Coagulum and extended semen, or trypsin-digested coagulum, were used for insemination. One insemination of trypsin-digested coagulum at the external os of the cervix resulted in a probable conception, follówed by apparent abortion after 3 weeks.     

The Quantitative Relationship Between “The Metabolic Syndrome” and Abdominal Obesity in Women

Abdominal obesity is closely associated with the presence of metabolic risk factors and elevated blood pressure in selected materials. This has, however, never been analyzed quantitatively in a non-selected cohort. Therefore, in a population-based study of 1462 Swedish women, four selected risk factors for non-insulin dependent diabetes mellitus (NIDDM) and cardiovascular disease (CVD), serum triglycerides, blood glucose and systolic blood pressure and also serum insulin in a subsample, were examined in relation to regional and overall obesity. This was performed by subdividing the age adjusted sample into quintiles of waist to hip circumference ratio (WHR) or body mass index (BMI) as indicators of abdominal distribution of body fat and overall obesity, respectively. The risk factors serum triglycerides, blood glucose, blood pressure and serum insulin were defined as being elevated when the value of the risk factor was higher than the mean plus one or two standard deviations of the total age-adjusted cohort. The percentage of women with elevated risk factors according to this definition was then calculated in each of these quintiles. Having a risk factor which was elevated according to the definition was significantly correlated to WHR and BMI (p<0.0001) independent of age. The presence of one or several of these elevated risk factors was clearly higher than expected in the fifth quintile of WHR, and to a lesser extent in the fifth quintile of BMI while this was not the case in the lower quintiles of WHR and BMI. When studying the combination of the WHR and BMI, the presence of risk factors higher than the mean plus two standard deviations increased gradually with WHR in all five quintiles of BMI. A significant association was observed between WHR and presence of risk factors independent of BMI (p<0.0001) but BMI did not remain significantly correlated to presence of risk factors when controlling for WHR (p=0.09). These results indicate that abdominal distribution of body fat in women independently of general obesity is closely associated with metabolic risk factors including elevated blood pressure, a metabolic syndrome with increased risk for cardiovascular disease and non-insulin dependent diabetes mellitus.     

Dietary Intake in Relation to Restrained Eating,Disinhibition, and Hunger in Obese and Nonobese Swedish Women

The aims of this study were to: describe dietary intakes of obese and nonobese middle-aged women using a validated food frequency questionnaire; to assess dietary restraint, disinhibition, and hunger by the three factor eating questionnaire (TFEQ) in obese and nonobese samples and determine which of the factors are independently associated with obesity; and to examine correlations between selected nutritional variables and the TFEQ factors. Subjects studied included 179 obese Swedish women (BMI>32) and 147 nonobese population-based controls (BMI<28). Age-adjusted mean energy intake was significantly higher in obese women (2730 ± 78 vs. 2025 ± 85 kcal, p<0.0001). In absolute and relative terms, fat intake was higher and alcohol intake was lower in the obese subjects. Disinhibition was the strongest TFEQ factor independently differentiating the obese and nonobese states, i.e., after adjustment for restraint and hunger. Within the obese sample, strong associations were seen between energy intake and disinhibition (p=0.0005) and hunger (p=0.0004). The association between energy intake and restrained eating was negative and weaker (p=0.04). No such associations were seen in nonobese women. Thus, using a dietary instrument that is valid and unbiased with respect to obesity, strong psychological correlates, possibly causal, of variability in energy intake were detected in middle-aged women with obesity. Disinhibition is associated with both obesity and high-energy intakes and is therefore an important factor to consider in the treatment of women with obesity.     

An isocoumarin and other phenolic components of Ononis natrix

From the n-hexane extract of the whole aerial part of flowering Ononis natrix, besides homopterocarpin and some known terpenoids and sterols, three new compounds: 8-hydroxy-6-methoxy-3-undecyl-3,4-dihydroisocoumarin, 5-(2-acetoxytridecyl)-3-methoxyphenol and 5-(2-hydroxytridecyl)-3-methoxyphenol have been isolated.     

Effect of streptozotocin at the insulin pre-receptor, receptor and post-receptor level in adipocytes of rats

The relationship among plasma insulin disappearance, insulin binding to specific receptors in fat cells and antilipolytic insulin activity in streptozotocin-diabetic rats has been studied. Male Wistar rats were injected streptozotocin (65 mg/kg body weight) or saline by cardiac puncture. Decreased insulin levels and increased insulin degradation together with an increase in insulin binding were found in diabetic rats. The increase in insulin binding was related to an increase in the number of insulin receptors rather than to a change in receptor affinity. These findings at the pre-receptor and receptor levels could be correlated with an increase in antilipolytic insulin activity. However our results suggest that the mechanism for insulin action occurred through a potentiation of the norepinephrine lipolytic activity.     

Adrenergic receptors are not mediators in the lipolytic effect of somatostatin in rat adipocytes

Beta-adrenergic receptors have been purported to act as possible mediators in the lipolytic effect of somatostatin in vivo. Investigations with isolated rat adipocytes studying the lipolytic activity of somatostatin (1.7 x 10(-7) M), glucagon (8.1 x 10(-8 M) and norepinephrine (10(-6) M), have shown that the lipolytic effect stimulated by somatostatin is not altered by 10(-5) M propranolol (beta-antagonist); is significantly enhanced by 10(-5) M isoproterenol (beta-agonist) and is not altered by the addition of 10(-6) M phenoxybenzamine (alpha-antagonist) or 10(-6) M phenylephrine (alpha-agonist). Similar results were found when lipolysis was stimulated by glucagon, whereas the lipolytic effect stimulated by norepinephrine was blocked by propranolol. These results indicate that the direct lipolytic effect of somatostatin on isolated rat adipocytes does not seem to be mediated through mechanisms involved with adrenergic receptors.