Fructose Diet-Induced Skin Collagen Abnormalities Are Prevented by Lipoic Acid

Nonenzymatic glycation of proteins, leading to chemical modification and cross-linking are of importance in the pathology of diabetic complications.We studied the effect of α-lipoic acid (LA) on the content and characteristics of the protein collagen from skin of high-fructose fed rats. The rats were divided into 4 groups of 6 each. Two groups of rats were fed with a high fructose diet (60 g/100 g diet) and administered either LA (35 mg/kg b.w., i.p) (FRU+LA) or 0.2 ml vehicle (saline) (FRU) for 45 days. The other 2 groups were fed with control diet containing starch (60 g/100 g diet) and administered either saline (CON) or lipoic acid (CON+LA). The rats were maintained for 45 days and then sacrificed. Plasma glucose, insulin, fructosamine, protein glycation, and blood glycated hemoglobin (HbA₁C) were measured. Collagen was isolated from skin and the physicochemical properties of collagen were studied. Fructose administration caused accumulation of collagen in skin. Extensive cross-linking was evidenced by enhanced glycation and AGE-linked fluorescence. Increased peroxidation and changes in physicochemical properties such as shrinkage temperature, aldehyde content, solubililty pattern, susceptibility to denaturing agents were observed in fructose-fed rats. SDS gel pattern of collagen from these rats showed elevated β component of type I collagen. These changes were alleviated by the simultaneous administration of LA. Administration of LA to fructose-fed rats had a positive influence on both quantitative and qualitative properties of collagen. The results suggest a mechanism for the ability of LA to delay diabetic complications.     

Molecular Mapping and Character Tagging in Mustard (Brassica juncea) II. Association of RFLP markers with Seed Coat Colour and Quantitative Traits

In Brassica juncea, segregation of 44 RFLP markers generated by homologous genomic DNA clones as probes was studied in a F₂ population obtained from an intervarietal cross. Linkage relationship among the markers was established using computer package ‘MAPMAKER’. Twenty five of the markers could be arranged in nine linkage groups, covering a total of 243.3 cM. Marker BJG357c showed tight linkage (3.9 cM) with yellow seed coat colour locus (r ₁). Based on single factor analysis of variance,17 significant marker-trait associations could be established in respect of six quantitative traits viz. days to flowering, plant height, number of primary branches, secondary branches per primary branch, siliquea per secondary branch, and seeds per siliqua. The proportion of phenotypic variation explained by individual marker-trait association ranged from 3.0% to 33.2%. The putative gene action at majority of the marked genomic regions was found to be partial dominance to dominance.