Effect of formation of biofilms and chemical scale on the cathode electrode on the performance of a continuous two-chamber microbial fuel cell

A two-chamber MFC system was operated continuously for more than 500 days to evaluate effects of biofilm and chemical scale formation on the cathode electrode on power generation. A stable power density of 0.57 W/m² was attained after 200 days operation. However, the power density decreased drastically to 0.2 W/m² after the cathodic biofilm and chemical scale were removed. As the cathodic biofilm and chemical scale partially accumulated on the cathode, the power density gradually recovered with time. Microbial community structure of the cathodic biofilm was analyzed based on 16S rRNA clone libraries. The clones closely related to Xanthomonadaceae bacterium and Xanthomonas sp. in the Gammaproteobacteria subdivision were most frequently retrieved from the cathodic biofilm. Results of the SEM-EDX analysis revealed that the cation species (Na⁺ and Ca²⁺) were main constituents of chemical scale, indicating that these cations diffused from the anode chamber through the Nafion membrane. However, an excess accumulation of the biofilm and chemical scale on the cathode exhibited adverse effects on the power generation due to a decrease in the active cathode surface area and an increase in diffusion resistance for oxygen. Thus, it is important to properly control the formation of chemical scale and biofilm on the cathode during long-term operation.     

The polygamous mating system of the sea spider Achelia simplissima

Most species of pycnogonids are sexually dimorphic and all have exclusive male care of the offspring, characteristics that make them essential for studies on sex-roles, sexual selection, and parental investment. However, sea spiders have been understudied because of their small size, cryptic coloration, and often patchy distribution, and little is known about their courtship and mating behaviors. The mating habits of both male and female Achelia simplissima (Hilton 1939) were studied experimentally and observationally. This species mates year-round and females commonly initiate courtship by actively ‘pumping’ their bodies near a male. When both nonparental and parental males were present, females mated significantly more often with males that were not carrying egg masses. Each mating event resulted in a single egg mass. Most often, males placed the first egg mass on their right oviger and then alternated between ovigers with subsequent matings. The newest (least developed) egg mass was always placed at the tip of the oviger. Both males and females routinely mated multiple times and had multiple mates; in the field, males were found carrying up to twelve egg masses simultaneously. This is the first experimental study to describe both the male and female mating system of a pycnogonid, and the first observations of courtship and mating for any species with the ammotheid type of ovigers.     

In vitro induction of cell division in the epidermis of stem segments ofTorenia fournieri Lind.

Cell division in the epidermis of stem segments ofT. fournieri stopped immediately when the epidermis was separated from subjacent tissues after having been in contact with these tissues for some time. Thus, the effects of the inductive signals emanating from these tissues did not persist. However, cell division in isolated epidermis cultured alone could be induced by adding asparagine, alanine or glutamine to the medium. Asparagine, at 5 mM, had the greatest stimulatory effect. Growth substances had a synergistic effect on this induction by amino compounds. However, these cell divisions, unlike those in epidermis cultured together with subepidermal tissues, did not lead to organogenesis. The amino compounds which partially replaced the inductive action of subepidermal layers on the epidermis can be considered as one of the endogenous factors coming from the first-named layers in intact explants.     

Heterogeneous anomalous diffusion of a virus in the cytoplasm of a living cell

The infection pathway of a virus in the cytoplasm of a living cell is studied from the viewpoint of diffusion theory, based on a phenomenon observed by single-molecule imaging. The cytoplasm plays the role of a medium for stochastic motion of a virus contained in an endosome as well as a free virus. It is experimentally known that the exponent of anomalous diffusion fluctuates in localized areas of the cytoplasm. Here, generalizing the fractional kinetic theory, such fluctuations are described in terms of the exponent locally distributed over the cytoplasm and a theoretical proposition is presented for its statistical form. The proposed fluctuations may be examined in an experiment of heterogeneous diffusion in the infection pathway.     

Azospirilli of Uzbekistan Soils and their Influence on Growth and Development of Wheat Plants

Associative nitrogen-fixing bacteria have been isolated, which were related to Azospirillum genus, by their morphological–cultural and physiological–biochemical ability to grow in microaerophilic conditions, as well as by a number of phenotypic traits. They comprised two species, namely, Azospirillum brasilense and Azospirillum lipoferum. Azospirilli strains displayed a varying salt resistance on potato medium containing a range of NaCl concentrations from 100 to 800 mM. The decrease in the nitrogen-fixing activity of azospirilli was detected starting from 200 mM NaCl. The biomass of the inoculated local varieties of wheat, Unumdor Bugdoi and Karlik 85, in microvegetation experiments exceeded the biomass of control plants by 20–50%. During the vegetation, some azospirilli strains formed spontaneous nodules on the wheat roots.     

Salt tolerance improvement in some wheat cultivars after application of in vitro selection pressure

Somatic embryogenesis through callus initiation has been quantified under salt stress conditions for 8 wheat cultivars currently cultivated in Morocco. The cultivars were classed according to the mean number of somatic embryos formed per immature embryo half and regenerated plants per 100 explants under saline conditions. Regenerated plants from control callus (R_0–0) and callus initiated on 10 g l^–1 NaCl (R_0–10) did not show significant differences concerning plant height, spike length and grain number per ear but, the R₀ plants remained less developed than parent plants. When watered with a solution containing more than 20 g l^–1 NaCl, the seeds of cultivar Te derived from R_0–10 regenerated plants exhibited the best elongation of roots and coleoptiles. Furthermore, a chlorophyll fluorescence test showed a clear improvement in salt tolerance of R_0–10 plants at four to five-leaf stage, compared to R_0–0 plants. It is concluded that plant regeneration from callus initiated on high NaCl levels may be a valid method of selection for salt tolerance.     

Mitochondrial KATP channels in hindlimb remote ischemic preconditioning of skeletal muscle against infarction

We previously demonstrated in the pig that instigation of three cycles of 10 min of occlusion and reperfusion in a hindlimb by tourniquet application (approximately 300 mmHg) elicited protection against ischemia-reperfusion injury (infarction) in multiple distant skeletal muscles subsequently subjected to 4 h of ischemia and 48 h of reperfusion, but the mechanism was not studied. The aim of this project was to test our hypothesis that mitochondrial ATP-sensitive potassium (KATP) (mKATP) channels play a central role in the trigger and mediator mechanisms of hindlimb remote ischemic preconditioning (IPC) of skeletal muscle against infarction in the pig. We observed in the pig that hindlimb remote IPC reduced the infarct size of latissimus dorsi (LD) muscle flaps (8 x 13 cm) from 45 +/- 2% to 22 +/- 3% (n = 10; P < 0.05). The nonselective KATP channel inhibitor glibenclamide (0.3 mg/kg) or the selective mKATP channel inhibitor 5-hydroxydecanoate (5-HD, 5 mg/kg), but not the selective sarcolemmal KATP (sKATP) channel inhibitor HMR-1098 (3 mg/kg), abolished the infarct-protective effect of hindlimb remote IPC in LD muscle flaps (n = 10, P < 0.05) when these drugs were injected intravenously at 10 min before remote IPC. In addition, intravenous bolus injection of glibenclamide (1 mg/kg) or 5-HD (10 mg/kg) at the end of hindlimb remote IPC also abolished the infarct protection in LD muscle flaps (n = 10; P < 0.05). Furthermore, intravenous injection of the specific mKATPchannel opener BMS-191095 (2 mg/kg) at 10 min before 4 h of ischemia protected the LD muscle flap against infarction to a similar extent as hindlimb remote IPC, and this infarct-protective effect of BMS-191095 was abolished by intravenous bolus injection of 5-HD (5 mg/kg) at 10 min before or after intravenous injection of BMS-191095 (n = 10; P < 0.05). The infarct protective effect of BMS-191095 was associated with a higher muscle content of ATP at the end of 4 h of ischemia and a decrease in muscle neutrophilic myeloperoxidase activity at the end of 1.5 h of reperfusion compared with the time-matched control (n = 10, P < 0.05). These observations led us to conclude that mKATP channels play a central role in the trigger and mediator mechanisms of hindlimb remote IPC of skeletal muscle against infarction in the pig, and the opening of mKATP channels in ischemic skeletal muscle is associated with an ATP-sparing effect during sustained ischemia and attenuation of neutrophil accumulation during reperfusion.     

Generation of Subcutaneous and Intrahepatic Human Hepatocellular Carcinoma Xenografts in Immunodeficient Mice

In vivo experimental models of hepatocellular carcinoma (HCC) that recapitulate the human disease provide a valuable platform for research into disease pathophysiology and for the preclinical evaluation of novel therapies. We present a variety of methods to generate subcutaneous or orthotopic human HCC xenografts in immunodeficient mice that could be utilized in a variety of research applications. With a focus on the use of primary tumor tissue from patients undergoing surgical resection as a starting point, we describe the preparation of cell suspensions or tumor fragments for xenografting. We describe specific techniques to xenograft these tissues i) subcutaneously; or ii) intrahepatically, either by direct implantation of tumor cells or fragments into the liver, or indirectly by injection of cells into the mouse spleen. We also describe the use of partial resection of the native mouse liver at the time of xenografting as a strategy to induce a state of active liver regeneration in the recipient mouse that may facilitate the intrahepatic engraftment of primary human tumor cells. The expected results of these techniques are illustrated. The protocols described have been validated using primary human HCC samples and xenografts, which typically perform less robustly than the well-established human HCC cell lines that are widely used and frequently cited in the literature. In comparison with cell lines, we discuss factors which may contribute to the relatively low chance of primary HCC engraftment in xenotransplantation models and comment on technical issues that may influence the kinetics of xenograft growth. We also suggest methods that should be applied to ensure that xenografts obtained accurately resemble parent HCC tissues.     

Insulin effects on acetate metabolism

Acetate metabolism was studied in patients with insulin resistance. To evaluate the interaction between glucose and acetate metabolism, we measured acetate and glucose turnover with a hyperinsulinemic euglycemic clamp (hot clamp) in obese and diabetic patients with insulin resistance (n = 8) and in a control group with normal insulin sensitivity (n = 6). At baseline, acetate turnover and plasma concentrations were similar between the two groups (group means: 4.3 +/- 0.4 micromol x kg-1 x min-1 and 128.2 +/- 11.1 micromol/l). Acetate concentrations decreased in both groups with hyperinsulinemia but were significantly lower in the insulin-resistant group (20% vs. 12%, P < 0.05). After the hot clamp treatment, acetate turnover increased for the two groups and was higher in the group with normal insulin sensitivity: 8.1 +/- 0.7 vs. 5.5 +/- 0.5 micromol x kg-1 x min-1 (P < 0.001). No change related to insulin action was observed in either group in the percentage of acetate oxidation. This was approximately 70% of overall utilization at baseline and during the clamp. No correlation between glucose and acetate utilization was observed. Our results support the hypothesis that, like glucose metabolism, acetate metabolism is sensitive to insulin.     

Prader-Willi syndrome: Methylation study or fluorescence in situ hybridization first?

Prader-Willi syndrome (PWS) is neurogenetic disorder involving the imprinting mechanism at 15q11-13 region. We report a 4-year-old girl who was referred to our laboratory to be investigated for clinical obesity, mental deficiency and respiratory problems. The patient was born for non-consanguineous and healthy biological parents. After normal pregnancy, the patient was delivered by cesarean section at full term, with a birth weight of 2500 g, and the height and head circumference were unknown. In neonatal stage, she presented severe hypotonia with feeding problems. Her developmental progress was delayed. She walked and developed speech at the age of 3 years. Since the age of 3 years, she presented severe dental problems. Methylation study had confirmed the diagnosis, and for detecting etiology, fluorescence in situ hybridization using probes for small nuclear ribonucleoprotein polypeptide N (SNRPN), which map inside the chromosomal region 15q11-15q13, was necessary to confirm the 15q11-15q13 deletion of paternal chromosome 15, which is the predominant genetic defect in PWS. In conclusion, we report this case with an objective to reinforce the necessity of analysis of DNA methylation within the 15q11-13 region, which is an important tool for the correct diagnosis among children presenting with neonatal hypotonia, mental deficiency and obesity.