Identification of early induced genes upon water deficit in potato cell cultures by cDNA-AFLP.

For plant cells in the early phases of water stress exposure, the genes induced under such conditions play a key role in detecting and responding to water deficit. In this study, potato cell suspensions were used as a simplified model system to dissect early molecular changes upon low water potential. In particular, the cDNA-amplified fragment length polymorphism approach was used to capture genes rapidly activated in potato cell cultures in response to water deficit induced by short-term exposure (up to 1 h) to polyethylene glycol. Selective amplifications with 38 primer combinations allowed the visualization of about 167 transcript-derived fragments (TDFs) differentially expressed upon exposure to low water potential. The gene expression pattern of 18 up-regulated genes was further investigated by semi-quantitative reverse transcriptase polymerase chain reaction analysis. Sequencing and similarity analysis revealed that TDFs present homologies chiefly with proteins involved in chaperone activity and protein degradation (hsps, proteinase precursor), in protein synthesis (elongation factor, ribosomal proteins) and in the ROS scavenging pathway (phenylalanine ammonia-lyase, peroxidase). Our findings might contribute to describe the potential role of genes activated in the early phases of plant response to drought.

A stepped approach to vascular access device selection.

Infusion therapy has evolved dramatically over the past few decades. From being used only in emergencies and for critically-ill patients, intravenous (IV) therapy has become a specialized form of treatment used for almost 90% of hospitalized patients (Corrigan, 1995). Infusion therapy is the parenteral administration of fluids, medications, nutritional support, blood products and the transfusion of blood. Fluids are delivered through a vascular access device, which is inserted into a peripheral or central vein (Royal College of Nursing (RCN), 2003). The venous route is the most predictable and reliable way to administer fluids and drugs when oral administration is not longer achievable or appropriate.

Comparison of three peripherally-inserted central catheters: pilot study.

Peripherally-inserted central catheters (PICCS) are non-tunnelled, central catheters inserted through a peripheral vein of the arm. They are 50-60 cm long and are usually made of either silicone or second-third generation polyurethane. PICCs can be used for prolonged, continuous or intermittent infusion therapies (up to 3 months) both in hospitalized patients and in patients treated as outpatients, in a hospice, or at home. When establishing a vascular service it is key to select a PICC that meets the requirements of safety, cost-effectiveness, high resistance (ability to take increasing fluid volumes with high pressure devices) and durability, and low complications rate. The complications and dwell times of three different PICCs were studied: coated polyurethane, valved silicone and power-injectable. The study was conducted at the chemotherapy suite at the author's hospital with the aim of selecting the right PICC based on low incidence of complications, resistance and enhanced dwell time. Results show a low incidence of complications and long dwell time among patients with the power-injectable PICC. Furthermore, this study demonstrated a reduction on the rate of occlusion and rupture with power-injectable PICCs, which makes them safer to use for administration of chemotherapy and other vesicant agents, as well as for the management of patients in critical care.

Nitrite metabolism in Debaryomyces hansenii TOB-Y7, a yeast strain involved in tobacco fermentation.

The Italian cigar manufacturing process includes a fermentation step that leads to accumulation of nitrite and tobacco-specific nitrosamines (TSNA), undesirable by-products due to their negative impact on health. In this study, growth and biochemical properties of Debaryomyces hansenii TOB-Y7, a yeast strain that predominates during the early phase of fermentation, have been investigated. With respect to other D. hansenii collection strains (Y7426, J26, and CBS 1796), TOB-Y7 was characterized by the ability to tolerate very high nitrite levels and to utilize nitrite, but not nitrate, as a sole nitrogen source in a chemically defined medium, a property that was enhanced in microaerophilic environment. The ability to assimilate nitrite was associated to the presence of YNI1, the gene encoding the assimilatory NAD(P)H:nitrite reductase (NiR), absent in Y7426, J26, and CBS 1796 by Southern blot data. YNI1 from TOB-Y7 was entirely sequenced, and its expression was analyzed in different media by Northern blot and reverse transcriptase polymerase chain reaction. The evidence that, in D. hansenii TOB-Y7, YNI1 was transcriptional active also in the presence of high ammonia concentration typical of tobacco fermentation, stimulated the development of an improved process that, on a laboratory scale, was proved to be effective in minimizing nitrite and TSNA accumulation.

Microbial community structure and dynamics of dark fire-cured tobacco fermentation.

The Italian Toscano cigar production includes a fermentation step that starts when dark fire-cured tobacco leaves are moistened and mixed with ca. 20% prefermented tobacco to form a 500-kg bulk. The dynamics of the process, lasting ca. 18 days, has never been investigated in detail, and limited information is available on microbiota involved. Here we show that Toscano fermentation is invariably associated with the following: (i) an increase in temperature, pH, and total microbial population; (ii) a decrease in reducing sugars, citric and malic acids, and nitrate content; and (iii) an increase in oxalic acid, nitrite, and tobacco-specific nitrosamine content. The microbial community structure and dynamics were investigated by culture-based and culture-independent approaches, including denaturing gradient gel electrophoresis and single-strand conformational polymorphism. Results demonstrate that fermentation is assisted by a complex microbial community, changing in structure and composition during the process. During the early phase, the moderately acidic and mesophilic environment supports the rapid growth of a yeast population predominated by Debaryomyces hansenii. At this stage, Staphylococcaceae (Jeotgalicoccus and Staphylococcus) and Lactobacillales (Aerococcus, Lactobacillus, and Weissella) are the most commonly detected bacteria. When temperature and pH increase, endospore-forming low-G+C content gram-positive bacilli (Bacillus spp.) become evident. This leads to a further pH increase and promotes growth of moderately halotolerant and alkaliphilic Actinomycetales (Corynebacterium and Yania) during the late phase. To postulate a functional role for individual microbial species assisting the fermentation process, a preliminary physiological and biochemical characterization of representative isolates was performed.