Towards an integrated system for bio-energy: hydrogen production by <Emphasis Type="Italic">Escherichia coli</Emphasis> and use of palladium-coated waste cells for electricity generation in a fuel cell

Escherichia coli strains MC4100 (parent) and a mutant strain derived from this (IC007) were evaluated for their ability to produce H₂ and organic acids (OAs) via fermentation. Following growth, each strain was coated with Pd(0) via bioreduction of Pd(II). Dried, sintered Pd-biomaterials (‘Bio-Pd’) were tested as anodes in a proton exchange membrane (PEM) fuel cell for their ability to generate electricity from H₂. Both strains produced hydrogen and OAs but ‘palladised’ cells of strain IC007 (Bio-Pd_IC007) produced ~threefold more power as compared to Bio-Pd_MC4100 (56 and 18 mW respectively). The power output used, for comparison, commercial Pd(0) powder and Bio-Pd made from Desulfovibrio desulfuricans, was ~100 mW. The implications of these findings for an integrated energy generating process are discussed.     

A genetic and spatial Bayesian analysis of mastitis resistance

A nationwide health card recording system for dairy cattle was introduced in Norway in 1975 (the Norwegian Cattle Health Services). The data base holds information on mastitis occurrences on an individual cow basis. A reduction in mastitis frequency across the population is desired, and for this purpose risk factors are investigated. In this paper a Bayesian proportional hazards model is used for modelling the time to first veterinary treatment of clinical mastitis, including both genetic and environmental covariates. Sire effects were modelled as shared random components, and veterinary district was included as an environmental effect with prior spatial smoothing. A non-informative smoothing prior was assumed for the baseline hazard, and Markov chain Monte Carlo methods (MCMC) were used for inference. We propose a new measure of quality for sires, in terms of their posterior probability of being among the, say 10% best sires. The probability is an easily interpretable measure that can be directly used to rank sires. Estimating these complex probabilities is straightforward in an MCMC setting. The results indicate considerable differences between sires with regards to their daughters disease resistance. A regional effect was also discovered with the lowest risk of disease in the south-eastern parts of Norway.     

Electron cytochemical study of the muscle cell surface

Summary The lectins wheat germ agglutinin and limulus polyphemus were used as cytochemical probes to study the ultrastructural localization of sialic acid at the cell surface of rat muscle fibers. In addition cytochemical studies employing strontium as an electron-dense marker were also carried out to investigate cation binding sites at the muscle cell surface. The results showed binding of the lectins to the glycocalyx, caveolae and the basal lamina of the muscle fibers. These binding sites matched the ones observed in the cytochemical studies using strontium as a marker. Based on these observations we suggest that the glycocalyx, caveolae and the basal lamina of the muscle fiber may be involved in the binding of Ca⁺⁺ and that significant amounts of Ca⁺⁺ may be normally present at the muscle cell surface.Supported by a grant from the Muscular Dystrophy Association and by Center Grant NS-1176 from the National Institute of Neurological and Communicative Disorders and Stroke     

Gas exchange and water balance of a mistletoe species and its mangrove hosts

Summary The gas exchange and water relations of the hemiparasite Pthirusa maritima and two its mangrove host species, Conocarpus erectus and Coccoloba uvifera, were studied in an intertidal zone of the Venezuelan coast. Carbon uptake and transpiration, leaf osmotic and total water potential, as well as nutrient content in the xylem sap and leaves of mistletoes and hosts were followed through the dry and wet season. In addition, carbon isotope ratios of leaf tissue were measured to further evaluate water use efficiency. Under similar light and humidity conditions, mistletoes had higher transpiration rates, lower leaf water potentials, and lower water use efficiencies than their hosts. Potassium content was much higher in mistletoes than in host leaves, but mineral nutrient content in the xylem sap of mistletoes was relatively low. The resistance of the liquid pathway from the soil to the leaf surface of mistletoes was larger than the total liquid flow resistance of host plants. Differences in the daily cycles of osmotic potential of the xylem sap also indicate the existence of a high resistance pathway along the vascular connection between the parasite pathway along the vascular connection between the parasite and its host. P. maritima mistletoes adjust to the different physiological characteristics of the host species which it parasitizes, thus ensuring an adequate water and carbon balance.     

Duchenne muscular dystrophy: deficiency of dystrophin at the muscle cell surface

Dystrophin is the altered gene product in Duchenne muscular dystrophy (DMD). We used polyclonal antibodies against dystrophin to immunohistochemically localize the protein in human muscle. In normal individuals and in patients with myopathies other than DMD, dystrophin was localized to the sarcolemma of the fibers. The protein was absent or markedly deficient in DMD. The sarcolemmal localization of dystrophin is consistent with other evidence that there are structural and functional abnormalities of muscle surface membranes in DMD.     

Cloning and expression of human nebulin cDNAs and assignment of the gene to chromosome 2q31-q32

We have isolated two nonoverlapping cDNAs encoding human nebulin, a muscle-specific protein. Northern hybridization analysis shows that nebulin is encoded by a huge message at least 25 kb in length. By hybridizing two nonoverlapping cDNAs to DNA isolated from rodent X human cell hybrids, we assign this presumably single-copy gene to human chromosome 2; sublocalization studies indicate that the nebulin gene is on the long arm of the chromosome, in the region 2q31-q32.     

Platelet-activating factor induces the expression of early pregnancy factor activity in female mice

When synthetic platelet-activating factor (PAF, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) was injected into mature female mice during dioestrus, pro-oestrus or oestrus, it induced the expression of early pregnancy factor (EPF) activity in the sera of these animals within 1 h of injection. The sera of similarly injected males, metoestrous or immature females did not display any EPF activity. The results suggest that embryo-derived PAF may be the ovum factor responsible for triggering the generation of serum EPF activity during the preimplantation stages of pregnancy.     

Essentiality of Boron for Dinitrogen Fixation in Anabaena sp. PCC 7119

The relationship between the requirement for boron and the form of N supplied in nutrient media to cyanobacterium Anabaena sp. PCC 7119 was investigated. When cells were grown in a medium which contained nitrate or ammonium-N, boron deficiency in the nutrient media did not inhibit growth or change cell composition. However, when cells were dependent on N₂ fixation, the lack of boron inhibited growth (i.e. growth ceased after 96 hours under these conditions). Additionally, boron-deficient cells showed a significant decrease in their content of phycobiliproteins and chlorophyll and accumulated carbohydrates within 24 hours of removing boron from the nutrient media. Inhibition of photosynthetic O₂ evolution accompanied the decrease in photosynthetic pigments. Boron deficiency symptoms were relieved when either boron or combined N was added to boron-deficient cultures. The degree of recovery depended upon the age of the cultures. Assays of nitrogenase activity showed that, after 2 hours of growth, nitrogenase activity of boron-deficient cells was inhibited by 40%. After 24 hours a total inactivation of nitrogenase activity was observed in boron-deficient cells. These results strongly suggest an involvement of boron in N₂ fixation in cyanobacteria.     

METHOD FOR COMBINED ULTRASTRUCTURAL AND BIOCHEMICAL ANALYSIS OF NEURAL TISSUE

No significant change was found in the electrolytes and lipids of the brain analyzed after glutaraldehyde fixation by perfusion of laboratory animals; such fixation also satisfactorily preserves neural tissues for electron microscopy. The brains of normal and tumor-bearing C3H mice, Wistar rats, and New Zealand rabbits were studied. Little difference was found in the dry weight and the content of sodium, potassium, total lipid and lipid fractions, and in the sulfate space (S³⁵O₄) between specimens from unperfused and perfused animals, whether normal or tumor-bearing. The results suggest the possibility of using selected regions of the nervous system, dissected after fixation, for chemical study and at the same time characterizing similar regions morphologically with the electron microscope.