Chrysonila sitophila (TFB-27441): A hyperlignolytic strain

Summary C. sitophila strain TFB-27441 showed 2–3 times higher lignolytic activity thanPhanerochaete chrysosporium (BKM-F-1767 strain). Lignin had a marked effect on the ligninase activity indicating that some induction or activation mechanism is involved in lignin degradation byC. sitophila.     

Postnatal maturation in nitric oxide-induced pulmonary artery relaxation involving cyclooxygenase-1 activity

The maturation in the vasodilator response to nitric oxide (NO) in isolated intrapulmonary arteries was analyzed in newborns and 15- to 20-day-old piglets. The vasodilator responses to NO gas but not to the NO donor sodium nitroprusside increased with age. The inhibitory effects of the superoxide dismutase inhibitor diethyldithiocarbamate and xanthine oxidase plus hypoxanthine and the potentiation induced by superoxide dismutase and MnCl(2) of NO-induced vasodilatation were similar in the two age groups. Diphenyleneiodonium (NADPH oxidase inhibitor) potentiated the response to NO, and this effect was more pronounced in the older animals. The nonselective cyclooxygenase inhibitors indomethacin and meclofenamate and the preferential cyclooxygenase-1 inhibitor aspirin augmented NO-induced relaxation specifically in newborns, whereas the selective cycloxygenase-2 inhibitor NS-398 had no effect. The expressions of alpha-actin, cycloxygenase-1, and cycloxygenase-2 proteins were similar, whereas Cu,Zn-superoxide dismutase decreased with age. Therefore, the present data suggest that the maturational increase in the vasodilatation of NO in the pulmonary arteries during the first days of extrauterine life involves a cycloxygenase-dependent inhibition of neonatal NO activity.     

Biotransformations of Bile Acids with Bacteria from Cayambe Slaughterhouse (Ecuador): Synthesis of Bendigoles

The biotransformations of cholic acid ( 1a ), deoxycholic acid ( 1b ), and hyodeoxycholic acid ( 1c ) to bendigoles and other metabolites with bacteria isolated from the rural slaughterhouse of Cayambe (Pichincha Province, Ecuador) were reported. The more active strains were characterized, and belong to the genera Pseudomonas and Rhodococcus. Various biotransformation products were obtained depending on bacteria and substrates. Cholic acid ( 1a ) afforded the 3‐oxo and 3‐oxo‐4‐ene derivatives 2a and 3a (45% and 45%, resp.) with P. mendocina ECS10, 3,12‐dioxo‐4‐ene derivative 4a (60%) with Rh. erythropolis ECS25, and 9,10‐secosteroid 6 (15%) with Rh. erythropolis ECS12. Bendigole F ( 5a ) was obtained in 20% with P. fragi ECS22. Deoxycholic acid ( 1b ) gave 3‐oxo derivative 2b with P. prosekii ECS1 and Rh. erythropolis ECS25 (20% and 61%, resp.), while 3‐oxo‐4‐ene derivative 3b was obtained with P. prosekii ECS1 and P. mendocina ECS10 (22% and 95%, resp.). Moreover, P. fragi ECS9 afforded bendigole A ( 8b ; 80%). Finally, P. mendocina ECS10 biotransformed hyodeoxycholic acid ( 1c ) to 3‐oxo derivative 2c (50%) and Rh. erythropolis ECS12 to 6α‐hydroxy‐3‐oxo‐23,24‐dinor‐5β‐cholan‐22‐oic acid ( 9c , 66%). Bendigole G ( 5c ; 13%) with P. prosekii ECS1 and bendigole H ( 8c ) with P. prosekii ECS1 and Rh. erythropolis ECS12 (20% and 16%, resp.) were obtained.     

Coordination of cell proliferation and anterior-posterior axis establishment in the mouse embryo

During development, the growth of the embryo must be coupled to its patterning to ensure correct and timely morphogenesis. In the mouse embryo, migration of the anterior visceral endoderm (AVE) to the prospective anterior establishes the anterior-posterior (A-P) axis. By analysing the distribution of cells in S phase, M phase and G2 from the time just prior to the migration of the AVE until 18 hours after its movement, we show that there is no evidence for differential proliferation along the A-P axis of the mouse embryo. Rather, we have identified that as AVE movements are being initiated, the epiblast proliferates at a much higher rate than the visceral endoderm. We show that these high levels of proliferation in the epiblast are dependent on Nodal signalling and are required for A-P establishment, as blocking cell division in the epiblast inhibits AVE migration. Interestingly, inhibition of migration by blocking proliferation can be rescued by Dkk1. This suggests that the high levels of epiblast proliferation function to move the prospective AVE away from signals that are inhibitory to its migration. The finding that initiation of AVE movements requires a certain level of proliferation in the epiblast provides a mechanism whereby A-P axis development is coordinated with embryonic growth.     

A developmental switch in sea urchin U1 RNA

The sequence of U1 RNA has been determined in the eggs and embryos of two sea urchins, Lytechinus variegatus and Strongylocentrotus purpuratus. In both species the sequence of the U1 RNA changes as the embryos progress through development. The sequence of the major U1 RNA in the eggs of the two species differs in two nucleotides, while the sequence of the U1 RNA present in the late embryos and somatic tissue is identical in the two species. The U1 RNA in eggs and early embryos is primarily derived from the tandemly repeated gene set, which is not expressed in somatic tissues.     

Genetic dissection of vitamin E biosynthesis in tomato

Vegetables are critical for human health as they are a source of multiple vitamins including vitamin E (VTE). In plants, the synthesis of VTE compounds, tocopherol and tocotrienol, derives from precursors of the shikimate and methylerythritol phosphate pathways. Quantitative trait loci (QTL) for α-tocopherol content in ripe fruit have previously been determined in an Solanum pennellii tomato introgression line population. In this work, variations of tocopherol isoforms (α, β, γ, and δ) in ripe fruits of these lines were studied. In parallel all tomato genes structurally associated with VTE biosynthesis were identified and mapped. Previously identified VTE QTL on chromosomes 6 and 9 were confirmed whilst novel ones were identified on chromosomes 7 and 8. Integrated analysis at the metabolic, genetic and genomic levels allowed us to propose 16 candidate loci putatively affecting tocopherol content in tomato. A comparative analysis revealed polymorphisms at nucleotide and amino acid levels between Solanum lycopersicum and S. pennellii candidate alleles. Moreover, evolutionary analyses showed the presence of codons evolving under both neutral and positive selection, which may explain the phenotypic differences between species. These data represent an important step in understanding the genetic determinants of VTE natural variation in tomato fruit and as such in the ability to improve the content of this important nutriceutical.     

Structural and biochemical characterization of toad liver fatty acid-binding protein

Two paralogous groups of fatty acid-binding proteins (FABPs) have been described in vertebrate liver: liver FABP (L-FABP) type, extensively characterized in mammals, and liver basic FABP (Lb-FABP) found in fish, amphibians, reptiles, and birds. We describe here the toad Lb-FABP complete amino acid sequence, its X-ray structure to 2.5 A resolution, ligand-binding properties, and mechanism of fatty acid transfer to phospholipid membranes. Alignment of the amino acid sequence of toad Lb-FABP with known L-FABPs and Lb-FABPs shows that it is more closely related to the other Lb-FABPs. Toad Lb-FABP conserves the 12 characteristic residues present in all Lb-FABPs and absent in L-FABPs and presents the canonical fold characteristic of all the members of this protein family. Eight out of the 12 conserved residues point to the lipid-binding cavity of the molecule. In contrast, most of the 25 L-FABP conserved residues are in clusters on the surface of the molecule. The helix-turn-helix motif shows both a negative and positive electrostatic potential surface as in rat L-FABP, and in contrast with the other FABP types. The mechanism of anthroyloxy-labeled fatty acids transfer from Lb-FABP to phospholipid membranes occurs by a diffusion-mediated process, as previously shown for L-FABP, but the rate of transfer is 1 order of magnitude faster. Toad Lb-FABP can bind two cis-parinaric acid molecules but only one trans-parinaric acid molecule while L-FABP binds two molecules of both parinaric acid isomers. Although toad Lb-FABP shares with L-FABP a broad ligand-binding specificity, the relative affinity is different.