Effect of temperature and long-term operation on passively immobilizedZymomonas mobilis for continuous ethanol production

Summary A fibrous support was used forZ. mobilis immobilization. The system showed a broad optimum temperature range (25–35°C) for highest ethanol productivity, ethanol yield and glucose conversion during continuous fermentation of a 100 g/L glucose medium. Ethanol production and glucose conversion kept steady during two months of continuous operation at D=1h^–1.     

Stoichiometric differences in DNA molecules containing the atpA gene suggest mechanisms for the generation of mitochondrial genome diversity in maize

Four genomic arrangements of the maize mitochondrial atpA gene (encoding the α subunit of the F₁ ATPase), have been characterized. Most N (fertile) and S (male-sterile) cytoplasms contain two atpA arrangements of equal abundance. Prolonged exposure of blots of maize mitochondrial DNA probed with atpA-specific sequences show that cytoplasms previously reported to lack one of the atpA arrangements do contain the second arrangement but at low levels. Similarly, restriction fragments containing the atpA gene previously thought unique to male-sterile S and T cytoplasms are present in low abundance in fertile cytoplasms. These observations suggest that fertile and male-sterile cytoplasms of maize may be more closely related than previously thought, and suggest possible mechanisms to explain the observed mitochondrial genome diversity.     

Plant regeneration in vitro of South Pacific taro (Colocasia esculenta var. esculenta cv. Akalomamale,Aracea)

Summary Axillary bud expiants from South Pacific (Solomon Islands) taro, Colocasia esculenta var. esculenta cv. Akalomamale (Araceae) cultured on a modified Murashige-Skoog medium containing 1 mg NAA 1^–1 and TE formed callus and produced multiple plantlets. Explants died if NAA was present at levels lower than 0.1 mg 1^–1. BA was not required and may have been inhibitory. Plantlets developed faster and became larger following transfer to a hormone-free medium two weeks after the start of culture. Fully grown plants were established in a potting mix and are growing well in a greenhouse.Abbreviations BA benzyladenine - BM basal medium - Ca Colocasia esculenta var. antiquorum - Ce Colocasia esculenta var. esculenta - Ck cytokinin(s) - CW coconut water - HSMSM half strength Murashige Skoog macroelements - HSMS half strength Murashige and Skoog medium - IM initial medium(ia) - MS Murashige and Skoog medium - NAA naphthaleneacetic acid - SM second medium - TE taro corm extract - UCI University of California, Irvine     

Expression of c-myc protooncogene in rat lens cells during development,maturation and reversal of galactose cataracts

It is well established that normal patterns of epithelial cell proliferation and metabolism, and of fiber cell differentiation and maturation are essential for the maintenance of transparency in the ocular lens. Several factors, including exposure to high levels of sugars, have been known to result in the compromise of lens transparency. For example, initiation of lens cell damage by galactose induces lens epithelial cells to proliferate. Elevated levels of c-myc mRNA have usually been correlated with rapid cell growth and increased entry of cells into the S phase. Therefore, changes in c-myc mRNA levels may provide an early indication of the stimulation of lens epithelial cells to proliferate and differentiate, which has been postulated to be an early and important event in response to lens cell injury by galactose. By Northern blot hybridization analysis we quantitated c-myc mRNA levels in the lens capsule epithelia of rats (1) exposed to galactose, and (2) undergoing a partial recovery from the galactose-induced cell damage. At the onset of lens cell damage, we find c-myc mRNA to elevate to 6-fold by 24 hr, and by 48 hr decreases to about 3-fold the normal levels. During recovery, c-myc mRNA continues to be expressed at high levels approaching a 10-fold increase by day 12, then decreasing to levels of about 8-fold the control by day 30. The 24 h transitory elevation in c-myc mRNA in lens epithelial cells is in accord with our previous observations on the 24 h increase in MP26, crystallin and aldose reductase mRNAs following a high influx of galactose. Therefore, the elevation in c-myc mRNA as well suggest that galactose appears to cause lens cells to undergo an early transitory period of gene induction following the exposure of lens cells to galactose.     

Comparative studies of selective media for recovery of Staphylococcus aureus from natural waters

Several selective media currently used for the enumeration of Staphylococcus aureus from different sources were evaluated in order to establish their quantitative recovery, specificity and degree of selectivity, using different types of water samples. The highest selectivity and reliability in the enumeration of Staph. aureus from the samples was obtained on Borrego-Florido-Romero-0 (BFR-0) and KRANEP agars. The method that produced the highest recovery of Staph. aureus was BFR-0 agar with membrane filter and incubation at 36 degrees C for 48-72 h.     

Comparative study of different methods for detection and enumeration of Salmonella spp. in natural waters

Seven enrichment media (two proposed by the authors) for detecting salmonellas from polluted freshwater were compared. The Most Probable Number technique for enumeration of salmonellas in water samples was used, directly adding filtered water to buffered peptone water as the pre-enrichment medium. The results indicate that Rappaport-Vassiliadis/43 and Rappaport-Vassiliadis/43 supplemented with 10 micrograms of sodium novobiocin per ml are the best media for the recovery and enumeration of salmonellas from water samples.     

Comparative study of different methods for detection and enumeration of Salmonella spp. in natural waters

Seven enrichment media (two proposed by the authors) for detecting salmonellas from polluted freshwater were compared. The Most Probable Number technique for enumeration of salmonellas in water samples was used, directly adding filtered water to buffered peptone water as the pre-enrichment medium. The results indicate that Rappaport-Vassiliadis/43 and Rappaport-Vassiliadis/43 supplemented with 10 μg of sodium novobiocin per ml are the best media for the recovery and enumeration of salmonellas from water samples.