In silico strategies to couple production of bioethanol with growth in cyanobacteria

Cyanobacteria have been considered as promising candidates for sustainable bioproduction from inexpensive raw materials, as they grow on light, carbon dioxide, and minimal inorganic nutrients. In this study, we present a genome-scale metabolic network model for Synechocystis sp. PCC 6803 and study the optimal design of the strain for ethanol production by using a mixed integer linear problem reformulation of a bilevel programming problem that identifies gene knockouts which lead to coupling between growth and product synthesis. Five mutants were found, where the in silico model predicts coupling between biomass growth and ethanol production in photoautotrophic conditions. The best mutant gives an in silico ethanol production of 1.054 mmol·gDW ⁻¹·h ⁻¹.     

Ultrastructural Study of the Filum Terminate and Caudal Ampulla of the Spinal Cord of Amphioxus (Branchiostoma lanceolatum Pallas)

The filum terminale and caudal ampulla of amphioxus were studied by electron microscopy. The filum terminale consists of ependymal cells whose cilia are directed caudally. Remarkably, nerve fibres course through the filum terminale and caudal ampulla and end on the basal lamina forming neuro-connective structures. Moreover, these nerve boutons are divisible into several classes according to their vesicle content. Boutons containing large dense-cored vesicles are very similar in appearance to the neurosecretory terminals found in the caudal spinal cord of some vertebrates. These observations on nerve fibres suggest that a primitive neurosecretory system similar to the fish urophysis is present in the amphioxus.     

Alternative mRNAs arising from trans-splicing code for mitochondrial and cytosolic variants of Echinococcus granulosus thioredoxin Glutathione reductase

Thioredoxin and glutathione systems are the major thiol-dependent redox systems in animal cells. They transfer via the reversible oxidoreduction of thiols the reducing equivalents of NADPH to numerous substrates and substrate reductases and constitute major defenses against oxidative stress. In this study, we cloned from the helminth parasite Echinococcus granulosus two trans-spliced mRNA variants that encode thioredoxin glutathione reductases (TGR). These variants code for mitochondrial and cytosolic selenocysteine-containing isoforms that possess identical glutaredoxin (Grx) and thioredoxin reductase (TR) domains and differ exclusively in their N termini. Western blot analysis of subcellular fractions with specific anti-TGR antibodies showed that TGR is present in both compartments. The biochemical characterization of the native purified TGR suggests that the Grx and TR domains of the enzyme can function either coupled or independently of each other, because the Grx domain can accept electrons from either TR domains or the glutathione system and the TR domains can transfer electrons to either the fused Grx domain or to E. granulosus thioredoxin.     

Invasive aspergillosis

Invasive aspergillosis is one of the most frequent fungal infections in neutropenic patients, in whom it is associated with a high mortality. Its diagnosis is difficult by the traditionally used laboratory tests. In the last years, an ELISA (Platelia Aspergillus, Bio-Rad, France) to detect galactomannan in neutropenic and cancer patients with high risk of suffering invasive aspergillosis has been developed. The experience accumulated in Spain in the diagnosis of invasive aspergillosis by Platelia Aspergillus is presented in this monograph.     

Screening of substrate analogs as potential enzyme inhibitors for the arginine kinase of Trypanosoma cruzi

Arginine kinase catalyzes the transphosphorylation between phosphoarginine and ADP. Phosphoarginine is involved in temporal ATP buffering and inorganic phosphate regulation. Trypanosoma cruzi arginine kinase phosphorylates only L-arginine (specific activity 398.9 x mUE-min(-1) x mg(-1)), and is inhibited by the arginine analogs, agmatine, canavanine, nitroarginine, and homoarginine. Canavanine and homoarginine also produce a significant inhibition of the epimastigote culture growth (79.7% and 55.8%, respectively). Inhibition constants were calculated for canavanine and homoarginine (7.55 and 6.02 mM, respectively). In addition, two novel guanidino kinase activities were detected in the epimastigote soluble extract. The development of the arginine kinase inhibitors of T. cruzi could be an important feature because the phosphagens biosynthetic pathway in trypanosomatids is different from the one in their mammalian hosts.     

The effect of Cyclosporine A chronic administration on the antioxidant pattern of rat liver mitochondria: structural and functional consequences

Cyclosporine A (CsA) plays a pivotal role in controlling Ca2+ movement in the cell modulating also the mitochondrial permeability transition pore. We investigated if chronic administration of CsA may have some effects on the lipophilic and hydrophilic antioxidant pattern of rat liver mitochondria and on their morphological structure. It seems that CsA administration does not statistically affect the redox status of the antioxidants investigated and their amounts (vitamin E, CoQ9, CoQ10, glutathione, uric acid and ascorbic acid) despite the variety of effects that this treatment produces at physiological and morphological levels. However, some kind of derangement could occur in the liver biochemical machinery since CsA treatment induces a markedly increased variability in antioxidant contents.     

AtBI-1, a plant homologue of Bax inhibitor-1, suppresses Bax-induced cell death in yeast and is rapidly upregulated during wounding and pathogen challenge

Extensive searches have so far failed to identify functional plant homologues of the mammalian apoptotic machinery. Here we report the isolation and characterisation of an Arabidopsis thaliana homologue of human Bax Inhibitor-1, AtBI-1, isolated during a differential screen of plants challenged with the phytopathogen Pseudomonas syringae. AtBI is a member of a small gene family in Arabidopsis, members of which display extensive amino acid identity to human BI-1. AtBI-1 is also functionally similar to BI-1 in its ability to suppress the lethal phenotype in yeast conferred by expression of the mammalian proapoptotic protein, Bax. Expression of AtBI-1 is rapidly upregulated in plants during wounding or pathogen challenge, suggesting a role in responses to biotic and abiotic stress. AtBI-1 upregulation appears R gene independent and is not markedly affected by mutations required for specific classes of R genes. However, the accumulation of AtBI-1 message is significantly reduced in coi1, in which defence responses to insects, pathogens and wounding are compromised.