RESUMO
A moderately thermophilic, sulphate-reducing bacterium, designated strain P6-2(T), was isolated from a terrestrial hot spring located at a height of 2,500 m in the Andean region, Colombia (5 degrees 43'69''N, 73 degrees 6'10''W). Cells of strain P6-2(T) were rod-shaped, stained Gram-negative and were motile by means of a single polar flagellum. The strain grew lithotrophically with H(2) as the electron donor and organotrophically on lactate, pyruvate, ethanol, malate, fumarate, n-propanol and succinate in the presence of sulphate as the terminal electron acceptor. Fumarate and pyruvate was fermented. Strain P6-2(T) grew optimally at 55 degrees C (range 37-60 degrees C), pH 6.6 (range 5.8-8.8) in the presence of 0.5% NaCl (range 0-4.5%) with lactate and sulphate and produced acetate, CO(2) and H(2)S as the major end-products. Sulphate, sulphite and thiosulphate could be used as electron acceptors but not elemental sulphur or nitrate. The G + C content of the genomic DNA was 58.7 mol%. The 16S rRNA sequence analysis indicated that strain P6-2(T) was a member of the class Deltaproteobacteria, domain Bacteria with Desulfomicrobium baculatum being the closest relative (similarity value of 94%). Phylogeny of genes encoding alpha- and beta-subunits of the dissimilatory sulphite reductase (dsrAB genes) supported its affiliation to members of the genus Desulfomicrobium. On the basis of this evidence, we propose to assign strain P6-2(T) as new species of the genus Desulfomicrobium, D. thermophilum sp. nov., with strain P6-2(T) as the type strain (= DSM 16697(T) = CCUG 49732(T)).
Assuntos
Bacilos e Cocos Aeróbios Gram-Negativos , Fontes Termais/microbiologia , Filogenia , Microbiologia da Água , 1-Propanol/metabolismo , Ácidos Acíclicos/metabolismo , Composição de Bases/genética , Colômbia , Etanol/metabolismo , Bacilos e Cocos Aeróbios Gram-Negativos/genética , Bacilos e Cocos Aeróbios Gram-Negativos/isolamento & purificação , Bacilos e Cocos Aeróbios Gram-Negativos/metabolismo , Temperatura Alta , Hidrogênio/metabolismo , Oxirredução , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Sulfatos/metabolismoRESUMO
Drosophila mojavensis and Drosophila arizonae are species of cactophilic flies that share a recent duplication of the alcohol dehydrogenase (Adh) locus. One paralog (Adh-2) is expressed in adult tissues and the other (Adh-1) in larvae and ovaries. Enzyme activity measurements of the ADH-2 amino acid polymorphism in D. mojavensis suggest that the Fast allozyme allele has a higher activity on 2-propanol than 1-propanol. The Fast allele was found at highest frequency in populations that utilize hosts with high proportions of 2-propanol, while the Slow allele is most frequent in populations that utilize hosts with high proportions of 1-propanol. This suggests that selection for ADH-2 allozyme alleles with higher activity on the most abundant alcohols is occurring in each D. mojavensis population. In the other paralog, ADH-1, significant differences between D. mojavensis and D. arizonae are associated with a previously shown pattern of adaptive protein evolution in D. mojavensis. Examination of protein sequences showed that a large number of amino acid fixations between the paralogs have occurred in catalytic residues. These changes are potentially responsible for the significant difference in substrate specificity between the paralogs. Both functional and sequence variation within and between paralogs suggests that Adh has played an important role in the adaptation of D. mojavensis and D. arizonae to their cactophilic life.
Assuntos
Adaptação Fisiológica/genética , Álcool Desidrogenase/metabolismo , Cactaceae , Drosophila/genética , Polimorfismo Genético , Seleção Genética , Simbiose , 1-Propanol/metabolismo , 2-Propanol/metabolismo , Álcool Desidrogenase/genética , Animais , Arizona , Drosophila/enzimologia , Feminino , Genótipo , México , Ovário/metabolismo , Conformação Proteica , Especificidade da Espécie , Especificidade por SubstratoRESUMO
The addition of a precursor of the enol form of isobutanal to neutrophils results in formation of triplet acetone, as attested to by emission from appropriate acceptors and cell damage (Nascimento et al., 1986 Biochim. Biophys. Acta 888, 337-342). The present study confirms the formation of triplet acetone by detection of the direct emission (lambda max 430 nm) and differentiates between effects produced by triplet acetone and by the enol substrate itself. Thus, triplet acetone: (1) enhances the release of ribonucleic acid; (2) promotes lipid peroxidation (N3(-)-inhibitable formation of thiobarbituric acid reactive products and concomitant light emission peaking at 480-500 nm); (3) increases myeloperoxidase activity, presumable as a result of damage and consequent increased exposure of the enzyme. On the other hand, the enol greatly enhances the release of protein(s) into the medium. These results confirm the utility of the neutrophil as a model system for the study of chemiexcitation processes induced at the cellular level. They also provide the first demonstration that an excited species formed at the cellular level may induce release of nucleic acids, thus reflecting the occurrence of deleterious processes in situ.