Changes in the Levels of Free Amino Acids in Various Regions of Cuscuta during Growth

The angiospermous plant parasite Cuscuta derives reduced carbon and nitrogen compounds primarily from its host. Free amino acids along Cuscuta vines in three zones, viz., 0 to 5 cm, 5 to 15 cm, and 15 to 30 cm, which in a broad sense represent the region of cell division, cell elongation and differentiation and vascular tissue differentiation respectively, were quantitatively estimated. The free amino acid content was the highest in the 0 to 5 cm region and progressively decreased along the posterior regions of the vine. The haustorial region showed the lowest content of free amino acids. In general, the free amino acid content in samples collected at 7 p.m. was found to be higher than that in the samples collected at 7 a.m. Three basic amino acids, histidine, the uncommon amino acid γ-hydroxyarginine, and arginine constituted more than 50% of the total free amino acids in all the zones studied except the haustorial region. Aspartic acid and glutamic acid constituted the major portion in the acidic and neutral fraction of amino acids. Glutamine, asparagine, threonine, and serine were eluted together and occurred in substantial amounts. γ-Hydroxyarginine constituted the largest fraction in the cut end exudate of Cuscuta and presumably appeared to be the major form of transport amino acid. γ-Hydroxyarginine was also a major constituent of the basic amino acids in Cuscuta vines parasitizing host plants from widely separated families, suggesting that this amino acid is a biosynthetic product of the parasite rather than that of the hosts. Also, U-14C arginine was converted to γ-hydroxyarginine by cut Cuscuta vines, suggesting that γ-hydroxyarginine is synthesized de novo from arginine by Cuscuta.

Terminalia paniculata bark extract attenuates non-alcoholic fatty liver via down regulation of fatty acid synthase in high fat diet-fed obese rats

Background: This study was performed to understand the possible therapeutic activity of Terminalia paniculata ethanolic extract (TPEE) on non alcoholic fatty liver in rats fed with high fat diet. Methods: Thirty six SD rats were divided into 6 groups (n = 6): Normal control (NC), high fat diet (HFD), remaining four groups were fed on HFD along with different doses of TPEE (100,150 and 200 mg/kg b.wt) or orlistat, for ten weeks. Liver tissue was homogenized and analyzed for lipid profiles, activities of superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) content. Further, the expression levels of FAS and AMPK-1 alpha were also studied in addition to histopathology examination of liver tissue in all the groups. Results: HFD significantly increased hepatic liver total cholesterol (TC), triglycerides (TG), free fatty acids (FFA) and MDA but decreased the activities of SOD and CAT which were subsequently reversed by supplementation with TPEE in a dose-dependent manner. In addition, TPEE administration significantly down regulated hepatic mRNA expression of FAS but up regulated AMPK-1 alpha compared to HFD alone fed group. Furthermore, western blot analysis of FAS has clearly demonstrated decreased expression of FAS in HFD + TPEE (200 mg/kg b. wt) treated group when compared to HFD group at protein level. Conclusions: Our biochemical studies on hepatic lipid profiles and antioxidant enzyme activities supported by histological and expression studies suggest a potential therapeutic role for TPEE in regulating obesity through FAS.

Lipid composition of the silkworm Bombyx mori L

The constituents of silkworm fat were studied in detail. An unsaturated fat with a high concentration of phospholipid was generally observed. Its iodine value increased during metamorphosis. The free fatty acid concentration likewise increased from the spinning larvae to the moth stage. Analyses of silkworm organs revealed that the fat body had the most fat and the least free fatty acids, whereas haemolymph contained the least fat. Silk glands contained the maximum phospholipid percentage. Stearic acid predominated in those tissues that had a high percentage of phospholipid. Stearic acid was the predominant saturated fatty acid in both the phospholipids and lecithin, and it accounted for 35–50 per cent of the free fatty acids of all the tissues. Q10 was the ubiquinone present; also found were ubichromenol and tocopherol. Results show that silkworm sterol may be cholesterol. Intestines contained the maximum quantities of sterol, ubiquinone, ubichromenol, and tocopherol. The composition of silkworm phospholipids varies considerably from those of other insects, but lecithin is comparable in its composition with lecithins of other animals. The phospholipids had with them a highly complexed protein along with a polysaccharide. In experiments with snake venoms unsaturated fatty acids were found to be predominantly released from silkworm lecithin.

Lipids of some thermophilic fungi

Total lipid content in the thermophilic fungi—Thermoascus aurantiacus, Humicola lanuginosa, Malbranchea pulchella var.sulfurea, andAbsidia ramosa—varied from 5.3 to 19.1% of mycelial dry weight. The neutral and polar lipid fractions accounted for 56.4 to 80.2% and 19.8 to 43.6%, respectively. All the fungi contained monoglycerides, diglycerides, triglycerides, free fatty acids, and sterols in variable amounts. Sterol ester was detected only inA. ramosa. Phosphatide composition was: phosphatidyl choline (15.9–47%), phosphatidyl ethanolamine (23.4–67%), phosphatidyl serine (9.3–17.6%), and phosphatidyl inositol (1.9–11.9%). Diphosphatidyl glycerol occurred in considerable quantity only inH. lanuginosa andM. pulchella var.sulfurea. Phosphatidic acid, detected as a minor component only inM. pulchella var.sulfurea andA. ramosa, does not appear to be a characteristic phosphatide of thermophilic fungi as suggested earlier. The 16∶0, 16∶1, 18∶0, 18∶1, and 18∶2 acids were the main fatty acid components. In addition,A. ramosa contained 18∶3 acid. Total lipids contained an average of 0.93 double bonds per mole of fatty acids, and neutral lipids tend to be more unsaturated than phospholipids.

Mass Transfer Coefficients in Mixer-Settlers

Mass transfer coefficients have been determined for transfer into a highly viscous phase in a stirred tank involving high Schmidt numbers. The results have been used to compute mass transfer coefficients in the extraction of free fatty acids from oils using alcohol and show good agreement with experimental results

Influence of cerebral ischemia and post-ischemic reperfusion on mitochondrial oxidative phosphorylation

Unilateral ischemia in the right cerebral hemisphere of the rat was induced by ligation of the right common carotid artery coupled with controlled hemorrhage to produce hypotension (25±8 mm/Hg). Where indicated after 30 min of ischemia, the withdrawn blood was reinfused to restore arterial pressure to normal. Mitochondria isolated from the ipsilateral hemisphere after 30 min of ischemia showed significantly lower respiratory rates than the organelles isolated from the contralateral side. Oxidation of NAD+-linked substrates was more sensitive to inhibition in ischemia (30%) than was of ferrocytochromec (12%), succinate oxidation being intermediate. The activities of membrane-bound dehydrogenases (both NADH and succinate-linked) were also significantly lowered. Ischemia did not affect the cytochrome content of mitochondria. Respiratory activity (NAD+-linked) of mitochondria isolated from the ipsilateral hemisphere was twice as sensitive to inhibition by fatty acid as was of preparations from the contralateral side. Mitochondria isolated from cerebral cortex after 90 min of post-ischemic reperfusion showed no significant improvement in the rate of substrate oxidation. Adenine nucleotide translocase activity and energy-dependent Ca2+ uptake, both of which decreased significantly in mitochondria isolated from the ischemic brain, showed little recovery, on reperfusion. These observations suggested the strong possibility that the deleterious effects of ischemia on mitochondrial respiratory function might be mediated by free fatty acids that are known to accumulate in large amounts in ischemic tissues. The pattern of inhibition of ATPase activity was consistent with this view.

Regulation of diacylglycerol kinase in rat brain membranes by docosahexaenoic acid

The effect of docosahexaenoic acid (DHA) on the diacylglycerol kinase (DG kinase) activity in rat brain membranes was investigated. DHA at 500 mu M concentration, stimulated the enzyme activity by about 2 fold. This effect was concentration-and time-dependent and was observed after very short periods of incubation (one min). DHA stimulation of DG kinase was observed only with rat brain membranes, and not with rat brain cytosol or rat liver membranes. Treating the rat brain membranes with phospholipase A(2) which released free fatty acids including DHA, significantly stimulated the DG kinase activity. It is concluded that DHA through its stimulatory effect on DG kinase may regulate the signalling events in growth-related situations in the brain such as synaptogenesis.

The physicochemical characteristics and anaerobic degradability of desiccated coconut industry waste water

Desiccated coconut industries (DCI) create various intermediates from fresh coconut kernel for cosmetic, pharmaceutical and food industries. The mechanized and non-mechanized DCI process between 10,000 and 100,000 nuts/day to discharge 6-150 m(3) of malodorous waste water leading to a discharge of 2646642 kg chemical oxygen demand (COD) daily. In these units, three main types of waste water streams are coconut kernel water, kernel wash water and virgin oil waste water. The effluent streams contain lipids (1-55 g/l), suspended solids (6-80 g/l) and volatile fatty acids (VFA) at concentrations that are inhibitory to anaerobic bacteria. Coconut water contributes to 20-50 % of the total volume and 50-60 % of the total organic loads and causes higher inhibition of anaerobic bacteria with an initial lag phase of 30 days. The lagooning method of treatment widely adopted failed to appreciably treat the waste water and often led to the accumulation of volatile fatty acids (propionic acid) along with long-chain unsaturated free fatty acids. Biogas generation during biological methane potential (BMP) assay required a 15-day adaptation time, and gas production occurred at low concentrations of coconut water while the other two streams did not appear to be inhibitory. The anaerobic bacteria can mineralize coconut lipids at concentrations of 175 mg/l; however; they are severely inhibited at a lipid level of = 350 mg/g bacterial inoculum. The modified Gompertz model showed a good fit with the BMP data with a simple sigmoid pattern. However, it failed to fit experimental BMP data either possessing a longer lag phase and/or diauxic biogas production suggesting inhibition of anaerobic bacteria.

Theoretical calculations of base-base interactions in nucleic acids: I Stacking interactions in free bases

Stacking interactions in free bases were computed on the basis of molecular association. The results of the calculations were compared with the stacking patterns observed in a few single crystals of nucleic acid components as examples. The following are the conclusions: (i) there can be two types of stacking pattern classified as normal and inverted types for any two interacting bases and both can be energetically favourable (ii) in both the types the stacking interaction is a combined effect of the overlap of the interacting bases and relative positions and orientations of the atomic centres of the two bases (iii) crystal symmetry and H-bonding interaction may influence stacking patterns.

Degradation of substituted benzoic acids by a Micrococcus species

Abstract a Micrococcus sp. isolated by isophthalate enrichment, utilized 8 of the 13 substituted benzoic acids tested as the sole source of carbon and energy. The organism degraded benzoic acid and anthranilic acid through the intermediate formation of catechol. While salicylate is metabolized through genetisic acid, p-hydroxybenzoic acid is degraded through protocatechuic acid. The organism grew well on isophthalate but failed to utilize phthalate and terphthalate. Catechol disoxygenase, gentisate dioxygenase and protocatechuate dioxygenase activities were shown in the cell-free extracts. Catechol and protocatechuate are further metabolized through an ortho-cleavage pathway.

Allostery and conformational free energy changes in human tryptophanyl-tRNA synthetase from essential dynamics and structure networks

The interdependence of the concept of allostery and enzymatic catalysis, and they being guided by conformational mobility is gaining increased prominence. However, to gain a molecular level understanding of llostery and hence of enzymatic catalysis, it is of utter importance that the networks of amino acids participating in allostery be deciphered. Our lab has been exploring the methods of network analysis combined with molecular dynamics simulations to understand allostery at molecular level. Earlier we had outlined methods to obtain communication paths and then to map the rigid/flexible regions of proteins through network parameters like the shortest correlated paths, cliques, and communities. In this article, we advance the methodology to estimate the conformational populations in terms of cliques/communities formed by interactions including the side-chains and then to compute the ligand-induced population shift. Finally, we obtain the free-energy landscape of the protein in equilibrium, characterizing the free-energy minima accessed by the protein complexes. We have chosen human tryptophanyl-tRNA synthetase (hTrpRS), a protein esponsible for charging tryptophan to its cognate tRNA during protein biosynthesis for this investigation. This is a multidomain protein exhibiting excellent allosteric communication. Our approach has provided valuable structural as well as functional insights into the protein. The methodology adopted here is highly generalized to illuminate the linkage between protein structure networks and conformational mobility involved in the allosteric mechanism in any protein with known structure.

Accumulation of glycine in the fat body of the silkworm, bombyx mori L. [31]

INVESTIGATIONS of intestinal transport of amino-acids in the locust1,2 and silkworm3,4 have shown no evidence for active accumulation in a transport from the insect gut of amino-acids. When glycine-2-14C was administered in vivo to fifth instar larvae of the silkworm, 96 per cent of the radioactivity was incorporated into various tissues within 1 h whereas in vitro only 19 per cent of the activity was transported by the mid-gut of silkworm (unpublished work). These results suggested that continued absorption of glycine by the intestine could be aided by a facilitated diffusion mechanism in which amino-acids are rapidly removed from the site of absorption either by accumulation into other tissues or by degradation. Although the insect fat body has been assigned both accumulatory and dissimilatory roles5, the mechanism of accumulation of amino-acids has not been investigated. Our present experiments show that the silkworm fat body possesses an efficient mechanism for accumulating glycine and that both the accumulation and the release of glycine are metabolically controlled.

Effect of phenoxy acids and their derivatives on lipid metabolism in groundnut (Arachis hypogaea) leaves

The effect of four phenoxy compounds [2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid, 4-chlorophenoxyacetic acid 2-(dimethylamino)ethyl ester (centrophenoxine), and 4-chlorophenoxy ethyl 2-(dimethylamino) ethyl ether (neophenoxine)] on lipid metabolism in groundnut (Arachis hypogaea) leaves was investigated under nonphotosynthetic conditions. In experiments with leaf disks, the uptake of [1-14C]acetate, [32P]orthophosphate, [35S]sulfate and [methyl-14C]choline was substantially inhibited by all the phenoxy compounds except neophenoxine. When the incorporation of these precursors into lipids was measured and expressed as percentage of total uptake, there was significant inhibition of incorporation of [1-14C]acetate and [32P]orthophosphate into lipids by all the compounds except neophenoxine. The incorporation of [methyl-14C]choline was unaffected by all except centrophenoxine which showed stastically significant stimulation. [35S]Sulfate incorporation into lipids was markedly inhibited only by centrophenoxine. The fatty acid synthetase of isolated chloroplasts assayed in the absence of light was inhibited 20–50% by the phenoxy compounds at 0.5 mM concentration. This inhibition showed a dependence on time of preincubation with the herbicide suggesting an interaction with the enzyme. It was, however, reversible and excess substrate did not prevent the inhibition, suggesting that the herbicide interaction may not be at the active site. sn-Glycerol-3-phosphate acyltransferase in the chloroplast and microsomal fractions was inhibited by 2,4-D while the phosphatidic acid phosphatase was insensitive to all the phenoxy compounds. It is concluded that phenoxy compounds affect precursor uptake, their incorporation into lipids, and the chloroplast fatty acid synthetase. The free acids were the most potent compounds while the ester (centrophenoxine) was less effective and the ether (neophenoxine) was completely ineffective in their influence on lipid metabolism.