Effect of light and temperature on epicuticular fatty acid and fatty alcohol of tobacco

Genetically uniform burley tobacco (Nicotiana tabacum) was grown under field and various controlled-environment conditions to determine whether environment influenced epicuticular alkane, fatty acid, and fatty-alcohol composition of the leaves. Quantity and quality of alkanes, fatty acids, and fatty alcohols were greatly influenced by environmental conditions. Highest light intensity did not result in the largest total long aliphatic carbon-chain production. Generally, long photoperiod and cool temperature were associated with highest long aliphatic carbon-chain production on a leaf area basis. Quantity of the individual alkane, fatty acid, or fatty alcohol classes present under the different growth conditions varied in relation to the leaf metabolic status and not leaf size.     

Chemically defined serum-free media for the cultivation of primary cells and their susceptibility to viruses

Summary Chemically defined media SFRE-199-1 for the growth and SFRE-199-2 for the maintenance of primary baboon kidney (Bak) cell cultures were formulated by supplementing medium M199 with insulin, sodium pyruvate, zinc sulfate, and increasing arginine-HCl, cysteine, cystine,l-glutamine,l-glutamic acid, glycine, histidine, tyrosine, and glucose to maximally active nontoxic concentrations. For prolonged maintenance of the cells, physiological pH control, and blocking of excessive lactic acid accumulation in the spent medium of the cell cultures, it was necessary to supplement the medium containing Earle's balanced salts withd-(+) galactose. The cells grew and were maintained equally well on glass or polystyrene surfaces. Selenium, when added to growth medium or substituted for insulin and zinc sulfate, did not stimulate cell growth. Electron microscopy showed that numerous dense particles, approximately 250 to 400 ? in diameter, with the appearance of glycogen, were found throughout the cytoplasm in the cells grown in SFRE-199-1 and maintained in SFRE-199-2. Echovirus types 1 to 3, poliovirus types 1 to 3, coxsackievirus types B2, B4, B5,Herpesvirus hominis type 1, simian herpesvirusH. simiae and SA8, and simian adenovirus SV34 when titrated in primary Bak cells and grown and maintained in SFRE-199-1 and 2, respectively, developed titers comparable to those obtained in conventionally grown and maintained cells. This study was supported in part by National Institute of Health Grant RR00361 and World Health Organization Grant V4/181/38. This laboratory serves as the NIH/WHO Collaborating Center for Reference and Research in Simian Viruses.     

Nature of amino acid substitutions in homologous proteins during evolution

Replacement substitutions of mitochondrial cytochrome $\text{c}$ and α- and β-chains of haemoglobin have been studied by considering the structural similarity among amino acid residues at the secondary and tertiary structural levels. Secondary structural similarity explains ～70% while tertiary structural similarity explains ～50% of observed replacements for most of the cases. These structural similarities could not account for all the replacement substitutions. The study was extended to consider the composition of codons, and the chemical nature and polarity of the replacing and replaced residues. These also could not individually account for all the affected replacements. In general, no property of amino acid residues is conserved for substitutions occurring at any single position during evolution of proteins.     

Inhibition of Na+ and K+-stimulated ATPase of rabbit heart sarcolemma after, administration of heparin.

Intravenous heparin administration caused a marked inhibition of Mg⁺⁺-dependent (Na⁺+K⁺)-stimulated ATPase activity of sarcolemmal (SL) membranes prepared from rabbit heart, whereas basal Mg⁺⁺-ATPase was not affected. The inhibition depended on K⁺ concentration and was reversed only in the presence of albumin. Plasma free fatty acid (FFA) concentrations were raised in all animals, after heparin administration. The results obtained support the concept that FFA or other lipids originating in the plasma by the action of lipolytic enzymes released by heparin are involved in the mechanism of inhibition.     

A cutin acid in Pinus sylvestris microspores

Nonacosan-10-ol (0.7%) and the cutin acid, 9,16-dihydroxyhexadecanoic acid (0.3%) are present in Pinus sylvestris microspores. The pollen coat hence has some features in common with leaf cuticles.     

Bile acids,FGF15/19 and liver regeneration: From mechanisms to clinical applications

The liver has an extraordinary regenerative capacity rapidly triggered upon injury or resection. This response is intrinsically adjusted in its initiation and termination, a property termed the “hepatostat”. Several molecules have been involved in liver regeneration, and among them bile acids may play a central role. Intrahepatic levels of bile acids rapidly increase after resection. Through the activation of farnesoid X receptor (FXR), bile acids regulate their hepatic metabolism and also promote hepatocellular proliferation. FXR is also expressed in enterocytes, where bile acids stimulate the expression of fibroblast growth factor 15/19 (FGF15/19), which is released to the portal blood. Through the activation of FGFR4 on hepatocytes FGF15/19 regulates bile acids synthesis and finely tunes liver regeneration as part of the “hepatostat”. Here we review the experimental evidences supporting the relevance of the FXR-FGF15/19-FGFR4 axis in liver regeneration and discuss potential therapeutic applications of FGF15/19 in the prevention of liver failure. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.     

Polysaccharide breakdown by mixed populations of human faecal bacteria

Measurements of polysaccharide-degrading activity in different fractions of human faeces showed that bacterial polysaccharidases and glycosidases were primarily associated with the washed bacterial fractions. Amylase, pectinase and xylanase were the major polysaccharide-hydrolysing enzymes detected, whilst α-L-arabinofuranosidase, β-D-xylosidase, β-D-galactosidase and β-D-glucosidase were the most active glycosidases. Starch and 3 non-starch polysaccharides (NSP; pectin, xylan and arabinogalactan) were fermented by mixed populations of human faecal bacteria in batch culture. Detailed carbohydrate analysis demonstrated that starch and pectin were the most rapidly degraded substrates and that arabinogalactan and the relatively insoluble polysaccharide xylan were broken down more slowly. Free sugars and oligosaccharides did not accumulate in culture media with any polysaccharide tested. Time-course measurements of polysaccharide remaining in the batch culture fermentations showed that the arabinose side chains of pectin, xylan and arabinogalactan were co-utilised with the backbone sugars. In these cultures, polysaccharide-degrading activity was mainly cell-associated, but extracellular polysaccharidase activity increased as the fermentations progressed. Molar ratios of acetate, propionate and butyrate produced in these experiments were dependent upon the polysaccharide substrate tested. Molar ratios of acetate, propionate and butyrate in the starch, arabinogalactan, xylan and pectin fermentations were 50:22:29, 50:42:8, 82:15:3, and 84:14:2, respectively. The presence of starch did not inhibit the breakdown of arabinogalactan, xylan or pectin by faecal bacterial, providing evidence that multicomponent substrate utilisation occurs when complex populations of faecal bacteria are provided with mixed polysaccharide substrates.