Postnatal development of amino acid metabolism enzymes in the liver and muscle of 'cafeteria' rats

The effect of feeding a high-energy highly palatable cafeteria diet on the liver and muscle ontogenesis of serine dehydratase, alanine transaminase, glutamine synthetase and adenylate deaminase during postnatal development of the rat has been studied. The results are in agreement with the lower amino acid utilization in cafeteria rats, both adults and during postnatal development. The feeding of excess energy coupled with high-quality protein resulted in changes in the ontogenesis of the studied enzymes that coincide with the development of protein synthesis and overall pup growth even before they had direct access to this rich diet, suggesting that cafeteria feeding already affects the amino acid metabolism of the pup through the dam's milk.     

Analysis of fluorescence transients of DCMU-treated leaves of Triticum species to provide estimates of the densities of photosystem II reaction centres

The fluorescence of the chlorophyll associated with photosystem II was studied in seedling and flag leaves of Triticum species. Seedling leaves of the diploid species T. urartu had higher values of t (the normalised area over the fluorescence induction curve of DCMU treated leaves) than those of the other species studied which included hexaploid T. aestivum. However this difference was not evident when leaves were grown in a low light intensity (40 µmol quanta of photosynthetically active radiation m^–2 s^–1). The smaller total number of chlorophyll molecules per photosystem II reaction centre (chl/RCII) in T. urartu (177) as compared with the other species (mean 234) was deduced from the observed differences in t. As a consequence of its lower chl/RCII, despite slightly lower chlorophyll content (mg m^–2), T. urartu had a greater density of reaction centres than the other species (2880 cf 2230 nmol m^–2 of leaf). Consistent with the lower chl/RCII of T. urartu, it had a higher chlorophyll a/b ratio than the other genotypes. Seedling leaves of T. urartu had higher light saturated rates of photosynthesis than those of the other species, when grown at high light, a difference associated with reaction centre density.In flag leaves, when the complications due to variable development and senescence patterns were eliminated, t of the diploid species including T. urartu was lower than that of T. aestivum. The lower apparent chl/RCII of T. urartu arose partly because the molar extinction coefficient of the chlorophyll in the leaves of T. urartu was greater than in T. aestivum. However, the density of PS II reaction centres was slightly lower for the diploid species studied because their chlorophyll contents were lower than the hexaploids.The validity of the method for estimating chl/RCII from fluorescence transients is discussed. The possibility is considered that the difference in apparent chl/RCII of flag and seedling leaves of R. urartu as compared to the other five genotypes is a consequence of its different adaptive response to the spectral quality of the light.     

Anther and tissue culture-induced grain chalkiness and associated variants in rice

Rice, Oryza sativa, plants regenerated from anther culture with and without in vitro selection pressure were evaluated for chalky seed. Progeny evaluated included 21 spontaneously doubled haploids selfed 4 times, progeny from plants regenerated from S-aminoethylcysteine resistant callus selfed 4 times and backcrosses of both types to the parental type. All lines with in vitro histories had higher seed chalkiness than the controls both in the intensity of chalkiness and in the number of seeds expressing the character. The full range of intensity and amount of chalkiness was expressed in the progeny. The average intensity of anther/tissue culture-derived progeny was 4–5, based on a scale of 1 (translucent) to 10 (fully opaque), and the average amount of chalkiness within plants sampled was 50–75 percent. The chalky characteristic is transmitted from parent to offspring into a range of identifiable F₂ segregants. Disclaimer statement Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the USDA, and does not imply its approval to the exclusion of other products that may also be suitable.     

Mercury-biogeochemical exploration for mineral deposits

Biogeochemical prospecting for mercury deposits and deposits of other minerals by the chemical analysis of mercury in plants or plant tissue that accumulate this element in linear (or near linear) proportion to the concentration in the soil is an effective method of exploration, even where allochthonous material as much as 200 to 2000 m thick covers the deposits. Plant tissues with this tendency to accumulate mercury (designated as non-barrier to mercury) comprise only a small fraction of the total of 255 types of plant tissues that were tested. Ten of these were considered to be quantitatively informative, and their mercury concentrations exceeded background values 300 or more times. The remaining types of plant tissues ranged in prospecting value from semi-quantitatively informative to qualitatively informative to uniformative (mercury values at or below background). The failure of some earlier uses of this prospecting method is attributed to the use of inappropriate plant tissues, to the mercury in the particular substrate studied existing in a form of low mobility and availability to plants, or to both causes.Prospecting by examining mercury concentrations in soils and rocks (lithogeochemical prospecting) is more effective than the biogeochemical approach only in prospecting for cinnabar deposits having no allochthonous cover. Mercury-biogeochemical prospecting is most effective for non-mercury mineral deposits and for oil and gas deposits. The types of plant tissues used in these studies are listed and are classified according to their value in prospecting. A case history is given of the Ozernoe pyrite-polymetallic deposit in Siberia.     

Diazo-reaction positive substance observed in the cortex of Chattonella antiqua

In order to investigate the causative factors responsible for removal of mucous coat from the gill lamellae of young yellowtail, Seriola quinqueradiata by red tide, diazo-reactions were employed for planktons and their media. The concentration of NO2- in the medium containing the raphidophyceae, Chatonella antiqua (ca 2000 cells/ml), was 0.70 +/- 0.05 (mu g/ml +/- SEM). In addition, diazo-reaction positive substances (NOx) which may degenerate the mucous, was highly concentrated in the cortex (perikaryon) of Chattonella antiqua. Morphologically, mucocysts, and chloroplats were likewise present in the cortex. Mucocysts were packed with fine fibrous content. Histochemically, the mucocysts were stained with PAS and had an abundance of nitrogen oxides (NOx). We observed discharge of the fibrous material from the mucocysts. These results suggest that when Chattonella antiqua is passing between the gill lamellae, NOx discharged from the mucocysts may act on the mucous, leading to the degeneration and concomitant removal of the mucous coat from gill lamellae.     

Effect of growth temperature on the morphology and performance ofZymomonas mobilis ATCC 29 191 in batch and continuous culture

Summary Increasing the temperature in chemostat culture ofZymomonas mobilis ATCC 29 191 with low and high glucose concentrations was found to result in a decreasing frequency of septation leading to the formation of long filaments and in increasing outer membrane blebbing. Whether this effect is strain specific or universal inZymomonas is, unknown. Improvements in the fermentation kinetics could be achieved at elevated temperatures, with an optimum at 33°C. Temperatures >30°C induced uncoupled growth in chemostat cultures ofZ. mobilis ATCC 29 191. The results of this study emphasize the importance of temperature regulation in optimizing the performance of continuous fermentations withZymomonas.Nomenclature D Dilution rate, 1/h - _max Maximum specific growth rate, 1/h - S _R Initial substrate concentration, g glucose/1 - S Amount of glucose consumed, g glucose/1 - S ₀ Effluent substrate concentration, g glucose/1 - X Biomass concentration - g cells/1 - [P] Amount of product formed, g ethanol/1 - [P] Product concentrations, g ethanol/l - Y _x/s Growth yield, g cells/g glucose used - Y _p/s Product yield, g ethanol/g glucose used - O _s Specific rate of glucose uptake, g glucose/g cells/h - Q _p Specific rate of ethanol formation, g ethanol/g cells/h - VP Volumetric productivity, g ethanol/1/h - t Fermentation time, h Corresponding author     

Quantitative study of cell interaction with collagen and fibronectin

The interaction of BHK-fibroblasts with collagen or fibronectin-collagen complex was investigated quantitatively. For that purpose an improved method for production of defined cell substrata was developed. The method permitted reproducible coupling of different ligands to glass via an amino or carboxyl group. BHK-cells grown on collagen required a minimum density of 15-20 ng collagen/cm2 for spreading. When grown on fibronectin adsorbed on collagen the cells were found to remove fibronectin from the substratum at a rate of 0.15 pg/(cell X h).     

Effects of chloride replacement and chloride transport blockade on the tonic tension of frog atrial trabeculae

The effects of a chloride-poor medium (methanesulfonate substituted) and a chloride transport inhibitor (SITS) on the outward delayed current and the tonic tension were studied on frog atrial trabeculae under voltage-clamp conditions. The outward delayed current decreased in low-chloride medium (10.5 mmol/l) or in the presence of SITS (2 mmol/l). The tonic tension increased in chloride-poor solution and decreased following SITS. The replacement of chloride by methanesulfonate enhanced the transient increase of tonic tension induced by low external sodium concentration while SITS reduced it. In the same conditions, the effect of the chloride-poor medium was abolished in the presence of SITS. The results showing an increase in Na-Ca exchange in low-chloride medium and a decrease by SITS are discussed assuming that changes in the inner negative charge density influenced the Na-Ca exchange mechanism; the influence of pHi variation are also considered.