1,2-Dimethylhydrazine-induced alterations in colonic plasma membrane fluidity: restriction to the luminal region

Recently, work in this laboratory has shown that changes in the 'dynamic' component of fluidity, lipid composition and phospholipid methylation activity of distal colonic brush-border membranes could be detected after administration of 1,2-dimethylhydrazine to rats of the Sherman strain for 5-15 weeks, i.e., before the development of colon cancer. The present experiments were therefore conducted to: determine whether similar 'premalignant' biochemical changes could be detected in basolateral membranes of Sherman rats treated with this agent; and clarify the relationship of these membrane changes to the malignant transformation process by examining the effect of 1,2-dimethylhydrazine on these biochemical parameters in colonic antipodal plasma membranes of rats of the Lobund-Wistar strain. This particular strain of rats has previously been shown to be total resistant to the induction of tumors by 1,2-dimethylhydrazine. The results of the present experiments demonstrate that similar biochemical alterations could not be detected in the colonic plasma membranes prepared from either strain of rat treated with 1,2-dimethylhydrazine. These data support the contention that the prior biochemical membrane alterations noted in brush-border membranes of 1,2-dimethylhydrazine-treated animals are, in fact, related to the malignant transformation process and, furthermore, are confined to the luminal surface of distal colonic epithelial cells.     

Dexamethasone influences the lipid fluidity, lipid composition and glycosphingolipid glycosyltransferase activities of rat proximal-small-intestinal Golgi membranes.

Experiments were performed to examine the effects of subcutaneous administration of the synthetic glucocorticoid dexamethasone (100 micrograms/day per 100 g body wt.) on the lipid fluidity, lipid composition and glycosphingolipid glycosyltransferase activities of rat proximal-small-intestinal Golgi membranes. After 4 days of treatment, Golgi membranes and liposomes prepared from treated rats were found to possess a greater fluidity than their control (diluent or 0.9% NaCl) counterpart, as assessed by steady-state fluorescence-polarization techniques using three different fluorophores. Moreover, analysis of the effects of temperature on the anisotropy values of 1,6-diphenylhexa-1,3,5-triene, using Arrhenius plots, demonstrated that the mean break-point temperatures of treated preparations were 4-5 degrees C lower than those of control preparations. Changes in the fatty acyl saturation index and double-bond index of treated membranes, secondary to alterations in stearic acid, linoleic acid and arachidonic acid, at least in part, appeared to be responsible for the differences in fluidity noted between treated and control Golgi membranes. Concomitant with these fluidity and lipid-compositional alterations, treated membranes possessed higher specific activities of UDP-galactosyl-lactosylceramide galactosyltransferase and CMP-N-acetylneuraminic acid:lactosylceramide sialyltransferase than their control counterparts. Experiments utilizing benzyl alcohol, a known fluidizer, furthermore suggested that the fluidity alteration induced by dexamethasone may be responsible for the increased activity of the former, but not the latter, glycosphingolipid glycosyltransferase.     

Effects of selection criteria on yield stability in chickpea (Cicer arietinum L.)

Summary Selection in the F₃ generation for seed yield, fruiting branches/plant, effective pods/plant, and seed index (100-seed weight) was carried out in two chickpea crosses. Sixty F₅ lines (15 lines/selection criterion) along with check variety were evaluated for seed yield in three distinct environments. The effects of selection criteria on yield stability was examined using linear regression approach and genotype-grouping technique. There were no differences between selection criteria for linear yield responses of F₅ lines to different environments. Within all four selection criteria the lines showed similar linear responses. The non-linear component was relatively higher for lines selected for effective pods and seed index than lines selected for yield and fruiting branches. On the basis of mean yield and coefficient of variation across environments, the seed index was the least effective selection criterion for developing high yielding and stable lines. When the results of stability parameters and genotype-grouping technique were considered together, selection for yield and fruiting branches was highly effective for isolating stable and high yielding lines.     

Novel method for screening pigeonpea varieties for globulin content by radioimmunoassay

Summary A rapid and sensitive radioimmunoassay (RIA) is described for screening a large number of pigeonpea varieties for quantitation of globulin content. This method employs precipitation of iodine-labelled pigeonpea globulin by polyethylene glycol and measuring the labelled antigen-antibody complex. Among the 56 varieties screened, Gwalior-3 was found to contain the highest globulin content. RIA when used to quantitate the pigeonpea globulin levels during post anthesis revealed that maximum globulin is present between 24 to 28 days after flowering.NCL Communication No. 3819.     

Metastasis-associated alterations in phospholipids and fatty acids of human prostatic adenocarcinoma cell lines.

Metastatic variants of human prostatic adenocarcinoma cell lines (DU-145, LNCaP, and ND-1) were studied by using soft agar colony forming efficiency, nude mice tumorigenicity, in vitro invasion assay, and type IV collagenase assay. The DU-145 and ND-1 cell line showed higher metastatic potential than LNCaP. Lipids from DU-145, ND-1, and LNCaP cells were extracted and analyzed by thin-layer chromatography and gas-liquid chromatography. The major lipids were phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, fatty acids, and cholesterol. The sphingomyelin level was significantly higher in highly metastatic cells (DU-145 and ND-1) compared with the lower metastatic variant (LNCaP). The increase in the synthetic pathway and decrease in degradation pathway of sphingomyelin in microsomal fractions was sufficient to account for the measured increase in sphingomyelin in DU-145 cells compared with LNCaP cells. The major fatty acids of these lipids were palmitic (16:0), stearic (18:0), oelic (18:1), and arachidonic acid (20:4). The arachidonic acid level was significantly decreased in DU-145 and ND-1 compared with LNCaP cells. Electron microscopic studies showed no significant changes in the morphology of DU-145, ND-1, and LNCaP cells. The results of these investigations demonstrate for the first time that sphingomyelin and arachidonic acid contents are different in high and low metastatic variants of human prostatic adenocarcinoma cell lines.     

Estrogen-induced alterations of the acidic and neutral glycosphingolipids of rat kidney

In order to determine whether female sex hormones could influence the glycosphingolipid composition of the rat kidney, male albino rats of the Sherman strain were subcutaneously administered the synthetic estrogen, ethinylestradiol (5 mg/kg body wt. per day) or vehicle for 5 days, and the ganglioside, ceramide and neutral glycosphingolipid compositions of the kidneys of these animals were analyzed and compared. The results of these experiments demonstrate that estrogen treatment: (1) increased the ceramide, acidic and neutral glycosphingolipid contents of this tissue; (2) decreased the relative percentages of glucosyl- and globotetraosylceramide and hematoside (GM3), but increased the relative percentage of globotriaosylceramide and 'other' gangliosides; (3) increased the relative percentage of N-acetyl- to N-glycolylneuraminic acid in GM3; and (4) altered the long-chain bases of GM3, glucosyl- and globotetraosylceramide in this organ. These data, therefore, demonstrate that estrogen administration induces quantitative and qualitative alterations in the gangliosides, neutral glycosphingolipids and ceramide of the rat kidney. This data as well as a discussion of the possible physiological consequences of these estrogen-induced alterations in kidney glycosphingolipids serve as the basis for this report.     

Comparison of single seed descent,selective intermating and mass selection for seed size in greengram (Vigna radiata (L.) Wilczek)

Summary Three selection methods (single seed descent (SSD), mass selection and selective intermating) were applied simultaneously to a highly heterogeneous and broadly based population of greengram. Progeny developing after two cycles of selection were evaluated for yield and seven other economic characters. The relative efficacy of each selection method was judged on the basis of the number of high yielding progeny, mean yield of top 10% progeny, and mean of the highest yielding progeny. Selection after two cycles of selective intermating was found to be the best method for generating productive progeny although mass selection favouring smaller seeds was an equally efficient method. Both of these were found superior to SSD selection.     

Aortal collagen polymorphism in monkey and man

Aortal collagen typing in monkey and man showed the presence of types I, HI and V in human aorta and types I and III in monkey aorta. Type III collagen was found to be a predominate type in both species. The molecular weight of type III collagen was similar in these species while type I collagen was different. Both monkey and human collagen types I and III were found to be immunogenic. Type I collagen was significantly increased while type III was decreased in human atherosclerotic plaque. Collagen typing in fatty streak remained unaltered.     

Opioid Peptides: An Overview of Functional Significance

International Journal of Peptide Research and Therapeutics - Bioactive peptides have been reported to exhibit opioid-like activity and are termed as opioid peptides. Either these are produced...