Similarity of the oxidation products of L-cystathionine by L-amino acid oxidase to those excreted by cystathioninuric patients

L-Cystathionine is oxidized by snake venom L-amino acid oxidase at a rate about half that with L-leucine at pH 8.5. The appearance of an absorbance at 296 nm and quantitation of the products of oxidation in the presence of catalase indicate formation in the solutions of a seven-membered ketimine ring produced by cyclization of the monoamino monoketo derivative of cystathionine. A limited double deamination has also been observed. In the absence of catalase, S-(carboxymethyl)homocysteine and S-(beta-carboxyethyl)cysteine have been identified together with ninhydrin-unreactive compounds yielding the above mentioned carboxy compounds upon hydrolysis with HCl. Authentic samples of the monoamino monoketo analogs of cystathionine have been prepared and compared with the enzymatic products. Cyclization of the synthetic products into the ketimine ring is pH-dependent as established by UV spectrum and other assays. Compounds derived from either the oxidation or the reduction of the ketimine have been prepared. It was found that many products of enzymatic and chemical changes of cystathionine and its ketimine described in the present paper are identical with those identified in the urine of cystathioninuric patients. This result indicates the occurrence in humans of secondary metabolic routes of cystathionine centered on the production of cystathionine ketimine, in equilibrium with the open form, which in cystathioninurics is revealed by the lack of cystathionase.     

Aerobiological monitoring for fungal spores in a rehabilitation hospital in Northern Italy

In the setting of an aerobiological study of confined environments and environmental prevention of nosocomial infections, aerobiological monitoring of 22 areas in Montescano Medical Rehabilitation Centre (Pavia) was performed in three different months: February, May, and August, 1994. A Lanzoni 3000 spore trap was used for the monitoring. Examination of the results showed that, in the environments monitored, the indoor presence of fungi increased progressively over the three periods considered. The behaviour of individual genera of fungi differed. In the winter periodPenicillium andAspergillus were the most commonly encountered genera.Cladosporium was the dominant genus from the spring to the summer while the yeasts had their maximum counts in the spring morning. The use of air conditioning, combined with the low air exchange between outdoors and indoors in some of the environments certainly played a part in the low concentrations of these latter aerofungi.     

Relationship between Active Oxygen Species,Lipid Peroxidation,Necrosis, and Phytoalexin Production Induced by Elicitins in Nicotiana

Excised leaves of Nicotiana tabacum var Xanthi and Nicotiana rustica were treated with cryptogein and capsicein, basic and acidic elicitins, respectively. Both compounds induced leaf necrosis, the intensity of which depended on concentration and duration of treatment. N. tabacum var Xanthi was the most sensitive species and cryptogein was the most active elicitin. Lipid peroxidation in elicitin-treated Nicotiana leaves was closely correlated with the appearance of necrosis. Elicitin treatments induced a rapid and transient burst of active oxygen species (AOS) in cell cultures of both Nicotiana species, with the production by Xanthi cells being 6-fold greater than that by N. rustica. Similar maximum AOS production levels were observed with both elicitins, but capsicein required 10-fold higher concentrations than those of cryptogein. Phytoalexin production was lower in response to both elicitins in N. tabacum var Xanthi cells than in N. rustica cells, and capsicein was the most efficient elicitor of this response. In cryptogein-treated cell suspensions, phytoalexin synthesis was unaffected by diphenyleneiodonium, which inhibited AOS generation, nor was it affected by tiron or catalase, which suppressed AOS accumulation in the extracellular medium. These results suggest that AOS production, lipid peroxidation, and necrosis are directly related, whereas phytoalexin production depends on neither the presence nor the intensity of these responses.     

Protein Phosphorylation Is Induced in Tobacco Cells by the Elicitor Cryptogein

Changes in plasmalemma ion fluxes were observed when tobacco (Nicotiana tabacum) cells were treated with cryptogein, a proteinaceous elicitor from Phytophthora cryptogea. A strong alkalization of the culture medium, accompanied by a leakage of potassium, was induced within a few minutes of treatment. These effects reached a maximum after 30 to 40 min and lasted for several hours. This treatment also resulted in a rapid, but transient, production of activated oxygen species. All these physiological responses were fully sensitive to staurosporine, a known protein kinase inhibitor. Furthermore, a study of protein phosphorylation showed that cryptogein induced a staurosporine-sensitive phosphorylation of several polypeptides. These data suggest that phosphorylated proteins may be essential for the transduction of elicitor signals.     

Electrotransformation of Streptococcus agalactiae with plasmid DNA

Abstract A protocol for efficient electrotransformation of Streptococcus agalactiae (group B streptococcus) Lancefield's strain O90R (NTCT 9993) (an unencapsulated derivative of type Ia strain O90) was developed. The Escherichia coli - Streptococcus shuttle vector pDP28 (7.8 kb) carrying the ermB gene for resistance to erythromycin was used as donor DNA. Frozen 'electrocompetent' cells were prepared by repeated washes in 10% glycerol. A 50-μl aliquot containing about 5×10⁹ colony forming units of bacteria was subjected to the electric pulse. Optimal conditions for electrotransformation were determined using different media, harvesting cells at different points of the growth curve, and using different field strengths. The dose-response curve for transformation of S. agalactiae with pDP28 showed one-hit kinetics as donor DNA varied between 0.01 and 3 μg. The efficiency of electrotransformation for this range of amounts of donor DNA was 1.2×10⁴ cfu μg⁻¹. The transformation frequencies obtained with this electroporation protocol are high enough to allow both subcloning and shotgun cloning of streptococcal DNA in S. agalactiae .     

Fine-scale mapping of physicochemical and microbial landscapes of the coral skeleton

The coral skeleton harbours a diverse community of bacteria and microeukaryotes exposed to light, O₂ and pH gradients, but how such physicochemical gradients affect the coral skeleton microbiome remains unclear. In this study, we employed chemical imaging of O₂ and pH, hyperspectral reflectance imaging and spatially resolved taxonomic and inferred functional microbiome characterization to explore links between the skeleton microenvironment and microbiome in the reef-building corals Porites lutea and Paragoniastrea benhami. The physicochemical environment was more stable in the deep skeleton, and the diversity and evenness of the bacterial community increased with skeletal depth, suggesting that the microbiome was stratified along the physicochemical gradients. The bulk of the coral skeleton was in a low O₂ habitat, whereas pH varied from pH 6–9 with depth. Physicochemical gradients of O₂ and pH of the coral skeleton explained the β-diversity of the bacterial communities, and skeletal layers that showed O₂ peaks had a higher relative abundance of endolithic algae, reflecting a link between the abiotic environment and the microbiome composition. Our study links the physicochemical, microbial and functional landscapes of the coral skeleton and provides new insights into the involvement of skeletal microbes in the coral holobiont metabolism.