Biomedical subjects

R Dahiya

Publications and source records attributed to R Dahiya.

At least 127 records · Page 7Linked to original sources

PubMed1989

ABH blood group antigen expression, synthesis, and degradation in human colonic adenocarcinoma cell lines.

The synthesis of blood group ABH antigens is under genetic control, where the primary gene products are glycosyltransferases. Several studies have demonstrated cancer-associated alterations in ABH antigen expression in human colon cancer tissues. However, the mechanism(s) responsible for these alterations has not been elucidated. Therefore, experiments were conducted using nine established colon cancer cell lines (four type O, three type A, and two type B) to examine ABH antigen expression by immunocytochemistry and correlate this with activities of ABH biosynthetic (glycosyltransferase) and degradative (glycosidase) enzymes. The products of the glycosyltransferase enzymes were characterized by high performance liquid chromatography and paper chromatography, and substrate affinities (apparent Km values) of the cancer cell-derived glycosyltransferases were analyzed. The present data demonstrate: (a) all cell lines except H-498 (blood type A) expressed the appropriate ABH glycosyltransferase as well as all three glycosidases; (b) product characterization and substrate dependence experiments suggested that the cancer cell-derived ABH glycosyltransferase enzymes had properties that were similar to those of the ABH enzymes in human serum; (c) H-498 cells exhibited A antigen deletion with accumulation of H precursor substance, most likely due to insufficient A transferase activity; (d) SW1417 cells (blood type B) demonstrated B antigen deletion without precursor accumulation, despite adequate levels of B transferase and low alpha-galactosidase activity; and (e) weak incompatible A antigen expression occurred in LoVo (type B) and SW1116 (type O) cells, and weak incompatible B antigen expression occurred in H-498 (type A) and SW1116 cells. However, since these cells lacked incompatible A or B transferase activity, these incompatible antigens are probably not the true A or B antigens. Thus, the colon cancer cell lines used in this study exhibit all of the ABH alterations previously described in colon cancer tissues and appear to be useful experimental models for studying the molecular events involved in cancer-associated ABH expression.

ABO Blood-Group System↗

PubMed1989

The glycosphingolipid composition and glycosyltransferase activities of the small intestinal mucosa of testosterone-treated rats.

Prior studies have demonstrated that sex hormones can influence the glycosphingolipid composition of different organs, including small intestine. However, to date, the effects of testosterone on glycosphingolipids of rat small intestinal mucosa have not been examined. Experiments were conducted to examine the effect of subcutaneous administration of synthetic testosterone (500 micrograms/100 g body wt.) on the gangliosides and neutral glycosphingolipids of rat small intestinal mucosa. Their results demonstrated that testosterone administrations: (i) increased the ganglioside content including hematoside (GM3); (ii) increased the total content of neutral glycosphingolipids, which was due to the increases in glucosylceramide and globotriaosylceramide; (iii) increased the activities of cytidine 5'-monophosphate-N-acetylneuraminic acid: lactosylceramide sialyltransferase, and UDPgalactose: lactosylceramide galactosyltransferase; (iv) increased the percentage of the long chain base phytosphingosine in hematoside, glucosyl-, and globotriaosylceramide; and (v) significantly altered the fatty acid composition of each of these glycosphingolipids. These results demonstrate that administration of testosterone induces alterations in glycosphingolipid composition and glycosyltransferases activities in rat small intestinal mucosa.

Animals↗

PubMed1989

Basic fibroblast growth factor does not initiate mitogenic signalling via phosphoinositide hydrolysis in PC12 cells.

Basic fibroblast growth factor (b FGF) was found to be equally potent mitogen as compared to alpha-thrombin to reinitiate DNA synthesis in quiescent PC12 cells. Whereas thrombin was found to be an activator of phospholipase C as judged by a rapid increase in the formation of inositol triphosphate, inositol biphosphate and a massive accumulation of inositol phosphate when 20 mM LiCl was present as an inhibitor of inositol mono phosphatases, basic FGF failed to induce the breakdown of the polyphosphoinositides in quiescent PC12 cells to any appreciable levels, however, a simultaneous increase in the level of diacylglycerol was observed. b FGF also failed to stimulate protein kinase C which is believed to be activated by diacylglycerol. It is therefore concluded that bFGF receptor mediated 'signalling is not via phospholipase C activation and bFGF's early mitogenic responses and DNA synthesis are initiated independent of the inositol lipids and protein kinase C activation. Thus bFGF must have its own unique signal transducing mechanism independent of inositol pathways.

Animals↗

PubMed1988

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.

Animals↗

PubMed1988

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.

Animals↗

PubMed1988

Cholesterol modulates alkaline phosphatase activity of rat intestinal microvillus membranes.

Experiments were conducted, using a nonspecific lipid transfer protein, to vary the cholesterol/phospholipid molar ratio of rat proximal small intestinal microvillus membranes in order to assess the possible role of cholesterol in modulating enzymatic activities of this plasma membrane. Cholesterol/phospholipid molar ratios from 0.71 to 1.30 were produced from a normal value of 1.05 by incubation with the transfer protein and an excess of either phosphatidylcholine or cholesterol/phosphatidylcholine liposomes for 60 min at 37 degrees C. Cholesterol loading or depletion of the membranes was accompanied by a decrease or increase, respectively, in their lipid fluidity, as assessed by steady-state fluorescence polarization techniques using the lipid-soluble fluorophore 1,6-diphenyl-1,3,5-hexatriene. Increasing the cholesterol/phospholipid molar ratio also decreased alkaline phosphatase specific activity by approximately 20-30%, whereas decreasing this ratio increased this enzymatic activity by 20-30%. Sucrase, maltase, and lactase specific activities were not affected in these same preparations. Since the changes in alkaline phosphatase activity could be secondary to alterations in fluidity, cholesterol, or both, additional experiments were performed using benzyl alcohol, a known fluidizer. Benzyl alcohol (25 mM) restored the fluidity of cholesterol-enriched preparations to control levels, did not change the cholesterol/phospholipid molar ratio, and failed to alter alkaline phosphatase activity. These findings, therefore, indicate that alterations in the cholesterol content and cholesterol/phospholipid molar ratio of microvillus membranes can modulate alkaline phosphatase but not sucrase, maltase, or lactase activities. Moreover, membrane fluidity does not appear to be an important physiological regulator of these enzymatic activities.

Alkaline Phosphatase↗

PubMed1988

Rat proximal small intestinal Golgi membranes: lipid composition and fluidity.

The present studies were conducted to examine and characterize the lipid composition and physical state of the membrane lipids of rat proximal small intestinal Golgi membranes. Golgi membranes were purified from isolated enterocytes; lipids were extracted from these membranes and analyzed by thin-layer and gas-liquid chromatography. The 'static' and 'dynamic' components of fluidity of Golgi membranes and their liposomes were assessed by steady-state fluorescence polarization techniques utilizing r infinity and S values of 1,6-diphenyl-1,3,5-hexatriene and r values of DL-2-(9-anthroyl)- and DL-12-(9-anthroyl)stearic acid, respectively. Additional studies were also performed on these membranes, using benzyl and methyl alcohol, to examine the relationship between alterations in lipid fluidity and glycosphingolipid glycosyltransferase activities. The results of these studies demonstrated that: (1) the principal phospholipids and neutral lipids of intestinal Golgi membranes, respectively, were phosphatidylcholine, phosphatidylethanolamine and sphingomyelin, and unesterified cholesterol and fatty acids; (2) the major fatty acids of Golgi membranes were palmitic (16:0), stearic (18:0), linoleic (18:2), arachidonic (20:4) and oleic (18:1) acids; (3) fluorescence polarization studies using diphenylhexatriene detected a thermotropic transition at 24-26 degrees C in Golgi membranes and liposomes prepared from lipid extracts of these membranes; (4) benzyl alcohol (25 and 50 mM) but not methyl alcohol (50 mM) significantly increased the fluidity of these membranes; and (5) at these same concentrations, benzyl alcohol was also found to increase significantly the specific activity of UDP-galactosyllactosylceramide galactosyltransferase but not CMP-acetylneuraminic acid: lactosylceramide sialyltransferase. Methyl alcohol was not found to influence either enzyme's activity in these membranes.

Animals↗

PubMed1988

Premalignant alterations in the glycosphingolipids of small intestinal mucosa of rats treated with 1,2-dimethylhydrazine.

1,2-Dimethylhydrazine is a procarcinogen with selectivity for the colon and proximal small intestine. In weekly subcutaneous (s.c.) doses of 20 mg/kg body weight, this agent produces colonic and proximal small intestinal tumors in a high percentage of rodents with a latency period of approximately six months. To determine whether alterations in the glycosphingolipid content of rat proximal and/or distal small intestinal mucosa existed before the development of dimethylhydrazine-induced cancer, rat were given s.c. injections of this agent (20 mg/kg body weight per wk) or diluent for five wk. Animals were killed at this time, and mucosa was isolated from each small intestinal segment of both groups. Glycosphingolipids then were extracted from these tissues and analyzed by high performance thin layer chromatography and gas liquid chromatography. The results of these studies demonstrated that (1) the content of neutral and acidic glycosphingolipids was significantly decreased (approximately 20%) in the proximal small intestine of treated rats compared with their control counterparts; (2) no significant difference in the glycosphingolipid content was seen, however, in the distal small intestinal mucosa of control and treated rats; and (3) while significant differences were noted in the majority of fatty acids of GM3, glucosyl- and globotriaosylceramide in the proximal small intestine of control and treated animals, differences in the fatty acids of these glycosphingolipids in the distal segment of these groups were confined to stearic (18:0) acid and/or arachidic (20:0) acid.

1,2-Dimethylhydrazine↗

PubMed1988

Dexamethasone-induced alterations in the glycosphingolipids of rat kidney.

To determine whether glucocorticoids would influence the glycosphingolipid composition of the rat kidney, male albino rats of the Sherman strain were subcutaneously administered dexamethasone (100 micrograms/100 g body wt/day) or diluent for four days. The compositions of ceramide and of acidic and neutral glycosphingolipids of the kidneys of these animals were then examined and compared. The results demonstrated that dexamethasone administration: 1) increased the content of ceramide and of acidic and neutral glycosphingolipids in kidney; 2) increased the relative percentage of globotriaosyl- and globotetraosyl-ceramide, but decreased the relative percentages of glucosylceramide; 3) decreased the relative percentages of GM3 and increased other gangliosides; 4) increased the relative percentages of N-glycolylneuraminic acid in GM3; 5) did not appear to influence significantly the long-chain bases of the major glycosphingolipids; and 6) altered the relative percentages and chain length of the hydroxy and nonhydroxy fatty acids of the major acidic and neutral glycosphingolipids in this tissue. The data show that dexamethasone administration induces quantitative and qualitative changes in the glycosphingolipids of the rat kidney.

Animals↗

PubMed1988

The lipid composition of plasma membrane from goat mammary gland.

Experiments were conducted to examine and characterize the lipid composition of the plasma membrane from the lactating goat mammary gland. The plasma membranes were purified by discontinuous sucrose density centrifugation. Lipids were extracted from these membranes and analyzed by thin-layer and gas-liquid chromatography. The results of these studies demonstrate that (i) the principal phospholipids of mammary-gland plasma membranes are phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin; (ii) the principal neutral lipids are triacylglyceride and cholesterol ester; (iii) the major glycolipids are globotetraosylceramide and globotriaosylceramide; and (iv) the major fatty acids are oleic (18:1), palmitic (16:0), stearic (18:0), and myristic (14:0) acids.

Animals↗

PubMed1988

Bovine basic fibroblast growth factor: identification and binding of its receptor on PC12 cells.

Basic fibroblast growth factor (FGF) was purified to homogeneity from bovine pituitary glands on the basis of its ability to stimulate Swiss 3T3 cell proliferation. The binding characteristics of biologically active 125[I]-FGF to PC12 cells have been studied. Binding of 125[I]-FGF was found to be specific, as the bound 125[I]-FGF was displaced by native FGF but not by epidermal growth factor (EGF) or nerve growth factor (NGF). Binding was saturable both as a function of time and of the concentration of 125[I]-FGF. Scatchard analysis of the binding data revealed the presence of 1.05.10(5) binding sites/cell with an apparent KD of 258 pM. When 125[I]-FGF binding was studied in PC12 cell membranes, it was found that the membraneous binding site displayed a lower KD of 28 pM. 125[I]-FGF was covalently cross-linked to its cell surface receptor on intact PC12 cells using the homobifunctional agent disuccinimidyl suberate. The covalently cross-linked 125[I]-FGF identified a single detergent soluble FGF binding site with an apparent molecular weight of 145,000 by SDS-PAGE analysis. Unlabeled FGF was found to compete with 125[I]-FGF for binding to the same receptor site. No labelling was observed in the absence of the cross-linker or when heat inactivated 125[I]-FGF was used. In conclusion, the present studies demonstrate for the first time the presence of FGF receptor on PC12 cells.

Adrenal Gland Neoplasms↗

PubMed1987

Dexamethasone-induced alterations in lipid composition and fluidity of rat proximal-small-intestinal brush-border membranes.

A series of experiments were conducted to examine the possible effects of subcutaneous administration of the synthetic glucocorticoid dexamethasone (100 micrograms/day per 100 g body wt.) on the lipid fluidity and lipid composition of rat proximal-small-intestinal brush-border membranes. After 4 days of treatment, membranes and their liposomes prepared from treated animals possessed a greater fluidity than did their control (diluent, 0.9% NaCl) counterparts, as assessed by steady-state fluorescence-polarization techniques using several different fluorophores. Examination of the effects of temperature on the anisotropy values of 1,6-diphenylhexa-1,3,5-triene, using Arrhenius plots, moreover, revealed that the mean break-point temperatures of the treated preparations were approx. 3-4 degrees C lower than those of their control-preparation counterparts. Changes in the sphingomyelin/phosphatidylcholine (PC) molar ratio as well as in certain of the fatty acids of the PC fraction of treated membranes, secondary to alterations in membrane PC levels and in lysophosphatidylcholine acyltransferase activities respectively, were also noted after dexamethasone administration. These compositional alterations appeared to be responsible, at least in part, for the differences in fluidity noted between treated and control plasma membranes. These results therefore demonstrate that dexamethasone administration can modulate the lipid fluidity and lipid composition of rat proximal-small-intestinal brush-border membranes.

Acyltransferases↗

PubMed1987

Dexamethasone-induced alterations in the glycosphingolipids of rat proximal small-intestinal mucosa.

Prior studies have demonstrated that glucocorticoids can influence the structure and function of several different organs, including the small intestine. However, to date, the effects of glucocorticoids on the glycosphingolipids of the rat small intestinal mucosa have not been examined. In the present experiments, male albino rats of the Sherman strain were subcutaneously administered dexamethasone (100 micrograms/100 g body wt. per day) or diluent for 4 days, and the ceramide, acidic and neutral glycosphingolipid compositions of the proximal small intestine of these animals were examined and compared. The results of these studies demonstrate that dexamethasone administration: (1) increased the content and relative percentage of hematoside (GM3) in this tissue; (2) increased the percentage of N-glycoylneuraminic acid of hematoside; (3) decreased the percentage of the long-chain base phytosphingosine of hematoside, glucosyl- and globotriaosylceramide; and (4) did not appear to influence significantly the concentration of the neutral glycosphingolipids or ceramide in this tissue. These data, therefore, indicate that dexamethasone administration induces alterations in the glycosphingolipids, particularly hematoside, of rat small-intestinal mucosa.

Animals↗

PubMed1987

Modulation of Na+-H+ exchange by ethinyl estradiol in rat colonic brush-border membrane vesicles.

Prior studies by our laboratory have suggested that a relationship may exist between rat colonic brush-border membrane vesicular fluidity and Na+-H+ exchange. To further explore this possible relationship, in the present studies the effects of ethinyl estradiol (17 alpha-ethinyl-1,3,5-estratriene-3,17-beta-diol) administration subcutaneously (5 mg/kg body wt. per day) for 5 days, on rat colonic brush-border membrane fluidity and Na+-H+ exchange were examined. This treatment regimen has previously been shown to decrease the lipid fluidity of rat hepatic and rabbit small intestinal plasma membranes. In agreement with these prior studies, the present results demonstrate that this agent decreases the lipid fluidity of treated-rat colonic brush-border membranes compared to control membranes, as assessed by steady-state fluorescence polarization techniques using three different fluorophores. An increase in the cholesterol content and cholesterol/phospholipid molar ratio of treated-membranes appear to, at least partially, be responsible for the fluidity differences. Furthermore, examination of the kinetic parameters for amiloride-sensitive sodium-stimulated proton efflux in treated and control membrane vesicles, utilizing the pH-sensitive fluorescent dye, Acridine orange, revealed that ethinyl estradiol administration decreased the Vmax for this exchange mechanism, expressed in arbitrary fluorescence units, by approx. 25% but did not influence its Km for sodium. These data, therefore, lend further support to the contention that alterations in fluidity may modulate Na+-H+ exchange in rat colonic brush-border membrane vesicles.

Animals↗

PubMed1987

Estrogen-induced alterations of hematoside of rat small intestinal mucosa.

Prior studies have suggested that sex hormones could influence the ganglioside and/or neutral glycosphingolipid composition of various organs. To date, the effects of sex hormones on the glycosphingolipid composition of the rat small intestinal mucosa, however, have not been examined. In the present studies, male albino rats of the Sherman strain were subcutaneously administered the synthetic estrogen, ethinylestradiol (5 mg/kg body wt. per day), or diluent for 5 days, and the ganglioside, neutral glycosphingolipid and ceramide composition of the small intestinal mucosa of these animals were analyzed and compared. The results of these experiments demonstrate that estrogen administration: increased the ganglioside concentration of this tissue, including hematoside (Gm3); increased the percentage of the long-chain base phytosphingosine of hematoside; and did not appear to significantly influence the concentration or composition of the neutral glycosphingolipids or ceramide in this tissue. These data, therefore, indicate that estrogen administration induces quantitative and qualitative alterations in the gangliosides but not in the neutral glycosphingolipids or ceramide of rat small intestinal mucosa.

Animals↗

PubMed1987

Premalignant alterations in the glycosphingolipid composition of colonic epithelial cells of rats treated with 1,2-dimethylhydrazine.

1,2-Dimethylhydrazine is a procarcinogen with selectivity for the colon. In weekly s.c. doses of 20 mg/kg of body weight, this agent produces colonic tumors in virtually 100% of rodents, with a latency period of approximately 6 months. To determine whether alterations in the glycosphingolipid content and composition of rat colonic epithelial cells existed before the development of dimethylhydrazine-induced colon cancer, rats were given s.c. injections of this agent (20 mg/kg body weight per week) or diluent for 5 weeks. Animals were sacrificed at this time period and colonocytes isolated from each group. Glycosphingolipids were then extracted from these cells and analyzed by thin-layer chromatography, high-performance liquid chromatography and gas-liquid chromatography. The results of these studies demonstrate that: (a) the content and relative percentages of globotriaosylceramide is increased, whereas hematoside and globotetraosylceramide are decreased in dimethylhydrazine-treated colonocytes compared to their control counterparts; and (b) differences in the enzymatic activities responsible for the biosynthesis of these glycosphingolipids appear to explain, at least partially, these compositional differences. The present data, therefore, suggest that alterations in certain glycosphingolipids may be an early event in colonic malignant transformation and, furthermore, that these alterations may prove useful in the detection of early colon cancer.

1,2-Dimethylhydrazine↗

PubMed1987

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.

1,2-Dimethylhydrazine↗

PubMed1987

Intraluminal calcium modulates lipid dynamics of rat intestinal brush-border membranes.

The present investigations were performed to evaluate whether calcium modulates the physical state and lipid composition of rat enterocyte plasma membranes in vivo. Ca2+ [CaCl2 (50 mM) in NaCl] or NaCl (vehicle control) was administered to rats by intraluminal (gavage) or intraperitoneal routes. Sixty minutes later, brush-border (BBM) and basolateral membranes (BLM) were prepared from the proximal small intestine. By use of the fluorophores, DL-2-(9-anthroyl)-stearic acid (2-AS), DL-12-(9-anthroyl)-stearic acid (12-AS), and 1,6-diphenyl-1,3,5-hexatriene (DPH), steady-state fluorescence polarization studies demonstrated that intraluminal calcium decreased the fluidity of BBM but not BLM compared with their respective vehicle controls. These alterations in fluidity could, at least in part, be attributed to the concomitant increase in sphingomyelin content and the sphingomyelin/lecithin ratio (mol/mol) observed in the BBM prepared from calcium-gavaged rats. To evaluate the mechanism for these lipid alterations, enzyme activities involved in sphingomyelin synthesis and degradation were measured and revealed an increase in sphingomyelin synthase and a decrease in sphingomyelinase in BBM prepared from calcium-gavaged rats. In contrast, intraperitoneal administration of calcium failed to influence membrane fluidity, lipid composition, or these enzymatic activities in either BBM or BLM.

Animals↗