Ali I. Mohamed

Functional genomic analysis of Arabidopsis thaliana glycoside hydrolase family 1.

In plants, Glycoside Hydrolase (GH) Family 1 β-glycosidases are believed to play important roles in many diverse processes including chemical defense against herbivory, lignification, hydrolysis of cell wall-derived oligosaccharides during germination, and control of active phytohormone levels. Completion of the Arabidopsis thalianagenome sequencing project has enabled us, for the first time, to determine the total number of Family 1 members in a higher plant. Reiterative database searches revealed a multigene family of 48 members that includes eight probable pseudogenes. Manual reannotation and analysis of the entire family were undertaken to rectify existing misannotations and identify phylogenetic relationships among family members. Forty-seven members (designated BGLU1 through BGLU47) share a common evolutionary origin and were subdivided into approximately 10 subfamilies based on phylogenetic analysis and consideration of intron–exon organizations. The forty-eighth member of this family (At3g06510; sfr2) is a β-glucosidase-like gene that belongs to a distinct lineage. Information pertaining to expression patterns and potential functions of Arabidopsis GH Family 1 members is presented. To determine the biological function of all family members, we intend to investigate the substrate specificity of each mature hydrolase after its heterologous expression in the Pichia pastoris expression system. To test the validity of this approach, the BGLU44-encoded hydrolase was expressed in P. pastoris and purified to homogeneity. When tested against a wide range of natural and synthetic substrates, this enzyme showed a preference for β-mannosides including 1,4-β-D-mannooligosaccharides, suggesting that it may be involved in A. thaliana in degradation of mannans, galactomannans, or glucogalactomannans. Supporting this notion, BGLU44 shared high sequence identity and similar gene organization with tomato endosperm β-mannosidase and barley seed β-glucosidase/β-mannosidase BGQ60.

Proinflammatory Cytokines and the Hypermetabolism of Children with Sickle Cell Disease

Sickle cell anemia (HbSS) includes chronic inflammation, but the origin is unclear. We hypothesized that in stable HbSS patients the inflammation was associated with hypermetabolism. We compared selected hypermetabolic and key Immuno-modulator indicators in HbSS versus control children and examined associations between measures of hypermetabolism and inflammation. Twelve fasting asymptomatic HbSS children 6–12 years and 9 controls matched for age, gender and fat mass (FM) were studied. Proportional reticulocyte count (retic%) and resting energy expenditure (REE) represented hypermetabolism, and C-reactive protein (CRP) Indicated Inflammation. Proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), chemokine monocyte chemoattractant proteln-1 (MCP-1), and energy balance cytokine leptin were measured. Methods were indirect calorimetry, enzyme-linked immunosorbent assay, and radioimmunoassay. Statistical analysis included simple correlation and regression analysis. REE (51 ± 6 vs. 43 ± 12 kcal/kg per fat-free mass (FFM), mean ± SD), retic% (12 ± 4 vs. 0.7 ± 0.3%), CRP (5 ± 3 vs. 0.3 ± 0.4 mg/liter), and IL-6 (71 ± 40 vs. 20 ± 7 pg/ml) were significantly higher for HbSS than controls (P < 0.05). Conversely, leptin (0.1 ± 0.1 vs. 2 ± 1 µg/liter per kgFM) and MCP-1 (34 ± 5 vs. 41 ± 4 pg/ml) were significantly lower for the HbSS subjects (P < 0.01). TNF-α was not significantly different. There were no significant associations between REE or retic% and any cytokine measured. However, CRP was significantly associated with REE in HbSS (r = 0.8, P = 0.003) and an important predictor of REE/FFM. We provide new evidence for low circulating levels of inflammatory chemokine MCP-1 in stable HbSS children, confirm mostly low cytokine levels, inflammation, and hypermetabolism and demonstrate association of hypermetabolism with inflammation via CRP but not via cytokines.

Chemical composition of kenaf (Hibiscus cannabinus L.) seed oil

Abstract Seeds from nine kenaf genotypes (Cubano, Everglades 41, Everglades 71, GR2563, Guatemala 48, Indian, 178-18RS-10, Tainung #1, and Tainung #2) were evaluated for oil, fatty acid, phospholipid, and sterol content. Oil content ranged from 21.4 to 26.4% with a mean of 23.7%. Total phospholipids ranged from 3.9 to 10.3% of the oil, with a mean of 6.0%. Mean sterol percent was 0.9 and ranged from 0.6% of the total oil for 178-18RS-10 accession to 1.2% for Everglades 71. Palmitic (20.1% of the total fatty acids), oleic (29.2%), and linoleic (45.9%) were the major fatty acids, and palmitoleic (1.6%), linolenic (0.7%), and stearic (3.5%) were the minor components. Medium (C 12 C 14 ) and long (C 22 C 24 ) chain fatty acids were less than 1%. Sphingomyelin (4.42% of the total phospholipids), phosphatidyl ethanolamine (12.8%), phosphatidyl choline (21.9%), phosphatidyl serine (2.9%), phosphatidyl inositol (2.7%), lysophosphatidyl choline (5.3%), phosphatidyl glycerol (8.9%), phosphatidic acid (4.9%), and cardiolipin (3.6%) were identified in the nine genotypes. Phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl glycerol were the dominant phospholipids. In addition, eight unidentified phospholipids were also found, β-sitosterol (72.3% of the total sterols), campsterol (9.9%), and stigmasterol (6.07%) were prevalent among kenaf genotypes. Kenafs relatively high oil content and its similarity to cottonseed oil suggest that the seed oil may be used as a source of edible oil. The variation among genotypes indicates potential for genetic improvement in oil yield and quality.

Chemical composition of purslane (Portulaca oleracea)

Purslane (Portulaca oleracea), grown under greenhouse conditions, was harvested at three growth stages and analyzed for total solids, total protein, ash, soluble carbohydrate, and fructose/fructane in whole plants, leaves, stems, and roots. Significant increases were observed in total solids and protein during plant maturation. Leaves had the highest amount of protein in the third growth stage (44.25g/100g dry matter). Roots showed a decline in protein level as the plant aged. Soluble carbohydrate was significantly higher in growth states 1 and 3. Significant variation among growth stages was found with regard to total phosphorous, calcium, potassium, iron, managanese, and copper. Total phosphorus (P) content in leaves was significantly higher than P found in stems and roots. Iron (Fe) content varied significantly among growth stages, and roots and leaves had the highest Fe content (121.47 and 33.21 mg, respectively). Significant accumulation of managanese (Mn) was found in different growth stages. Leaves and roots had significantly higher Mn content than stems.

Dietary Flaxseed Meal is More Protective Than Soy Protein Concentrate Against Hypertriglyceridemia and Steatosis of the Liver in an Animal Model of Obesity

Objective: Soy protein and flaxseed meal have been reported to have beneficial effects on many chronic diseases in humans and animals. The primary objective of the study was to evaluate the beneficial effects of soy protein and flaxseed meal on hypertriglyceridemia and liver steatosis associated with obesity and diabetes. We compared the effects of dietary soy protein and flaxseed meal with that of casein on plasma and liver lipids in a genetic model of obesity, type II diabetes and insulin resistance, namely the SHR/N-cp rat. Methods: Lean and obese phenotypes of SHR/-cp rats were fed AIN 93 diets containing 20% of energy from casein (control), soy protein concentrate or flaxseed meal for six months. Plasma was analyzed for total cholesterol, LDL cholesterol, triglyceride and total protein. Liver was analyzed for steatosis by light microscopy after staining samples with Hematoxylin-Eosin and Oil-Red-O. Results: In lean rats soy protein and flaxseed meal significantly decreased plasma total cholesterol (26.0% and 20.3% respectively) compared to casein. In obese rats flaxseed meal had significant cholesterol lowering effect compared to control rats (41%). Soy protein significantly lowered both plasma LDL-cholesterol and HDL-cholesterol in lean phenotypes while in obese phenotypes flaxseed meal significantly lowered LDL-cholesterol and HDL-cholesterol compared to casein-fed rats. Flaxseed meal also significantly lowered plasma triglyceride in both lean and obese rats compared to casein fed rats (33.7% and 37% respectively). There was significantly greater fat accumulation in livers of obese rats than lean rats (200%) regardless of dietary protein type. Flaxseed meal significantly lowered fat deposition in livers of both lean and obese rats compared to rats fed casein or soy protein. Dietary component(s) present in flaxseed meal or soy protein responsible for hypolipidemic effects is not clear. Conclusions: The marked hypotriglyceridemic and hypocholesterolemic effects of flaxseed meal may have important therapeutic implications in patients with hypertriglyceridemia and hypercholesterolemia and deserve further study in humans with these disorders. Flaxseed meal supplementation may provide a new therapeutic strategy to reduce hypertriglyceridemia and fatty liver.

Differential effects of dietary flaxseed protein and soy protein on plasma triglyceride and uric acid levels in animal models.

The effect of dietary soy protein and flaxseed meal on metabolic parameters was studied in two animal models, F344 rats with normal lipid levels and obese SHR/N-cp rats with elevated levels of cholesterol and triglyceride. The rats were fed AIN 93 diet differing only in the source of protein. The rats were fed either 20% casein, 20% soy protein or 20% flaxseed meal. Plasma was analyzed for cholesterol, triglyceride, uric acid, blood urea nitrogen (BUN), creatinine and total protein. In both strains of rats, flaxseed meal significantly decreased plasma cholesterol and triglyceride concentrations. The effect of soy protein on lipids was not as striking as that of flaxseed meal. Flaxseed meal also lowered uric acid in F344 rats and BUN in SHR/N-cp rats. Since cholesterol, triglyceride and uric acid are independent risk factors for cardiovascular disorders, our data show that both flaxseed meal and soy protein may have beneficial effects. Which chemical constituent(s) of flaxseed meal or soybean is (are) responsible for the beneficial effects need to be identified.

The effect of dietary menhaden, olive, and coconut oil fed with three levels of vitamin E on plasma and liver lipids and plasma fatty acid composition in rats

The effect of dietary fats with varying degrees of unsaturation in the presence of different concentrations of vitamin E on tissue lipid levels was studied in rats. Rats were fed either menhaden oil, olive oil or coconut oil at 15% levels with either 0.1, 0.3 or 0.6 mg/g of vitamin E as alpha-tocopherol for four weeks. Rat serum and liver were analyzed for total cholesterol, HDL-cholesterol, triacylglycerol and phospholipids. In addition, fatty acid composition of serum lipids was also analyzed. Serum total cholesterol and triacylglycerol were significantly lower in rats fed menhaden oil than in those fed olive or coconut oil, while the HDL-cholesterol was significantly higher in serum of rats fed menhaden and olive oil than in those fed coconut oil. Levels of vitamin E in the diet had only a significant effect on serum cholesterol and liver phospholipids. The Pearson correlation coefficient showed a significant positive relationship between serum triacylglycerol and total cholesterol, and a negative correlation between triacylglycerol and HDL-cholesterol, and between total and HDL-cholesterol.In the liver, total cholesterol was significantly higher in rats fed coconut oil than in rats fed menhaden oil. Total liver phospholipids were lower in rats fed either coconut oil or olive oil compared to those fed menhaden oil, especially with higher levels of vitamin E intake. Higher levels of vitamin E in the diet appear to increase triacylglycerol and phospholipids in livers of rats fed menhaden oil. In the liver a significant negative correlation was observed between phospholipids and cholesterol. The type and degree of unsaturation (polyunsaturated fatty acids in menhaden oil, monounsaturated fatty acids in olive oil and saturated fatty acids in coconut oil) significantly affected plasma and tissue lipids.

Supercritical fluid extraction of Vernonia galamensis seeds

Abstract Vernonia galamensis is an excellent source of a seed oil rich in vernolic acid. However, the seeds of this plant exhibit a high lipase activity in the dormant state. The activity of this enzyme is apparent as vernonia oil will undergo lipolysis when the seeds are crushed prior to extraction. In this study, supercritical fluid extraction (SFE) utilizing carbon dioxide has been examined as an alternative solvent, at different pressures, temperatures and cosolvent concentrations. The use of supercritical fluid carbon dioxide (SC-CO2) as the extraction fluid under high temperatures and pressures has the potential to inhibit the lipolysis reaction during the extraction by reducing the activity of the enzyme, and hence the production of undesired fatty acids. Vernonia seeds were ground with dry ice prior to extraction to minimize any nascent lipase activity. Selective SFE was conducted at various pressures, temperatures, modifier concentrations, and total CO2 volume used to determine whether the vernolic acid content of the resultant extract could be enriched. An increase in pressure and temperature significantly increased the amount of extracted oil as well as the vernolic acid content. In addition, a significant reduction in the free fatty acid content of the oil from 69 to 8 mg/g oil was present with increasing extraction pressure. Exhaustive extraction of the oil could be attained via SFE with neat CO2 and with ethanol-modified CO2. However, regrinding the matrix after the initial extraction, followed by re-extraction of the seed matrix was necessary in these cases. The resultant oil and extracted meal were characterized with respect to free fatty acid, phospholipid, and percent protein contents.

Nutrient composition and anti-nutritional factors in selected vegetable soybean (Glycine Max [L.] Merr.)

The genetic variation in the nutrient composition and anti-nutritional factors of 17 vegetable soybean genotypes were determined and a wide variation in protein %, total phosphorus (TPi) and available phosphorus (AP) was found among these genotypes. Variations in Ca, K, Fe, Mn, and Cu were also documented. Variation was also found for trypsin inhibitor (TI) activity and Phytate (PA) content. A highly significant and negative correlation (r=−0.533,P<0.01) was observed between TI and total protein. Strong positive correlation (r=0.90) was also found between TPi and AP. Several genotypes (Sooty, Emperor, Wilson-5, PI 416771, PI 417322) showed good nutritional potential and can be used in the breeding program. High protein %, TPi, and minerals are desirable qualities for vegetable-type soybeans that make it as food with high nutrient density. Studies on the nutritional evaluation of immature vegetable type soybean seeds at different reproductive stages are also underway.

Accumulation of phytate in vegetable-type soybean genotypes harvested at four developmental stages

A total of 17 vegetable-type soybean (Glycine max [L.] Merr) genotypes were planted in four-row plots arranged in a randomized complete block design in 1988 and 1989 at Petersburg, Virginia. Each genotype was harvested at four developmental stages and evaluated for phytate content. Highly significant differences for phytate content were observed among the stages of harvest and genotypes, and there was an interaction between genotype x stage of harvest. The significant differences observed for phytate content among genotypes indicated that genetic variation exists among the tested genotypes for selection and improvement through hybridization. Among the genotypes, ‘Kingston’ and PI 423852 had the highest phytate content in most stages of harvest while PI 416771, ‘Emperor’, and PI 416982 had the lowest phytate values. A heritability estimate of 81 percent was observed for phytate content. This high heritability value indicates that selecting genotypes for lower phytate content would be effective. Significant correlations were observed for phytate content among genotypes harvested at R6, R7, R8, and overall. The magnitude of association of R6 with the overall phytate mean was especially high. These results illustrate that determining the phytate content of genotypes at the R6 growth stage would be a good predictor of the overall genotypic performance.