Mitochondrial DNA restriction map for the Caribbean fruit fly,Anastrepha suspensa,and occurrence of mitochondrial DNA diversity within highly inbred colonies

A restriction map has been constructed for Anastrepha suspensa mitochondrial DNA. One HaeIII site was found to be polymorphic among individuals in highly inbred colonies and a feral population. Based on mapping information, the polymorphic site was determined to be in the ATPase 6 gene. Primers TK-J-3804 and C3-N-5460 amplified this region. The amplicon was cut by HaeIII in flies of one haplotype and not cut in flies of the other haplotype. From 30 to 43% of the individual flies studied had this additional HaeIII site. After cloning of the 5200 bp XbaI fragment, the two mitotypes were identified. A 988 base fragment, coding for the entire tRNA-Lys(AAG), tRNA-Asp(GAC), and ATPase 8genes, and a partial ATPase 6gene was sequenced Four silent mutations, including the one at the informative site were located. The HaeIII polymorphism and other sequence differences may prove useful as a diagnostic for identification of the origin of introduced fruitflies.     

Visual event related potentials. The origin of wave P300. A computer model

This five-layered model consisting of 180 neurons is aimed at simulating some elementary functions of primary visual cortex of mammals in form detection. Its main achievements are: 1. Detection of points, lines, simple geometric figures in the V1. 2. Abstraction of 19 different qualities of geometric figures. 3. Simulation and rational explanation of processing of peripheral stimuli in the V1, explanation of mechanism of origin of visual ERPs, including P300 wave. 4. Simulation and explanation of the nature and build up of the cognitive function within V1 and its possible relation to long-term memory. 5. The model is based partly on Hebb-type synapses, illustrates the role of neuronal assemblies, sheds light on the functional relationship of excitatory and inhibitory neurons, in their conformity with special tasks of different cortical layers.     

Methods to reduce background interferences in electron-capture gas chromatographic analysis of valproic acid and its unsaturated metabolites after derivatization with pentafluorobenzyl bromide

Analysis of the branched, medium-chain fatty acid anticonvulsant, valproic acid, and its unsaturated metabolites by gas chromatography with electron-capture detection suffered from background interference caused by the derivatizing reagent pentafluorobenzyl bromide. Background was reduced by keeping the derivatization anhydrous, using an inert solvent, minimizing the amount of pentafluorobenzyl bromide, using hypernucleophilic bases and displacing the derivatization solvent with isooctane. However, these strategies proved difficult to reproduce. Post-derivatization clean-up with HPLC was much more reliable and provided sufficient sensitivity for the analysis of extracts of plasma and brain homogenate. The assay was validated for plasma and brain samples from humans, rats and mice.     

Large Scale Isolation of Pig Muscle Phosphoglucose Isomerase

large-scale purification procedure for phosphoglucose isomerase from pig skeletal muscle is described. It consists of two fractionations by selective precipitation and two ion exchange chromatography steps yielding an end product of approximately 900 units (micromoles of sub-strate converted to product per rain per mg of protein, at 30°) specific activity. The method separates three isoenzymic forms with an overall recovery of about 30% of the original total enzyme activity in the form of Isoenzyme III, the latter being the predominant enzyme species.     

High Dietary Magnesium Intake Is Associated with Low Insulin Resistance in the Newfoundland Population

Background

Magnesium plays a role in glucose and insulin homeostasis and evidence suggests that magnesium intake is associated with insulin resistance (IR). However, data is inconsistent and most studies have not adequately controlled for critical confounding factors.

Objective

The study investigated the association between magnesium intake and IR in normal-weight (NW), overweight (OW) and obese (OB) along with pre- and post- menopausal women.

Design

A total of 2295 subjects (590 men and 1705 women) were recruited from the CODING study. Dietary magnesium intake was computed from the Willett Food Frequency Questionnaire (FFQ). Adiposity (NW, OW and OB) was classified by body fat percentage (%BF) measured by Dual-energy X-ray absorptiometry according to the Bray criteria. Multiple regression analyses were used to test adiposity-specific associations of dietary magnesium intake on insulin resistance adjusting for caloric intake, physical activity, medication use and menopausal status.

Results

Subjects with the highest intakes of dietary magnesium had the lowest levels of circulating insulin, HOMA-IR, and HOMA-ß and subjects with the lowest intake of dietary magnesium had the highest levels of these measures, suggesting a dose effect. Multiple regression analysis revealed a strong inverse association between dietary magnesium with IR. In addition, adiposity and menopausal status were found to be critical factors revealing that the association between dietary magnesium and IR was stronger in OW and OB along with Pre-menopausal women.

Conclusion

The results of this study indicate that higher dietary magnesium intake is strongly associated with the attenuation of insulin resistance and is more beneficial for overweight and obese individuals in the general population and pre-menopausal women. Moreover, the inverse correlation between insulin resistance and dietary magnesium intake is stronger when adjusting for %BF than BMI.