Effects of the levels of fatty acids and carbohydrates in a diet on the biosynthesis of fatty acids in larvae of the silkworm, Bombyx mori

The effects of varying levels of fatty acids and carbohydrates in the diet on fatty acid synthesis from glucose in the larvae of the silkworm, Bombyx mori, were investigated. Elevation of the level of dietary fatty acids resulted in the decrease of the rate of fatty acid synthesis in the larvae. The addition of palmitate, stearate, or oleate to a diet had an inhibitory effect on fatty acid synthesis. The prolonged feeding of larvae on a diet containing a high level of fatty acid intensified the depression of the synthesis. The inhibitory effect of dietary fatty acid was found in the presence of both high and low levels of dietary carbohydrates. On the other hand, the rate of fatty acid synthesis was greatly accelerated by increasing the level of sucrose in a diet but not by the addition of starch. Furthermore, the fatty acid composition of the larval tissue shows a marked difference between the two groups of larvae fed on a diet containing sucrose and on a diet containing potato starch. Palmitic and oleic acid contents of larval tissue were increased significantly on the sucrose diet.     

Properties of the promoter region of theT18 d (T13 c )Tla gene

The T18^d (formerlyT13 ^c) gene of BALB/c mice belongs to the category ofTla genes which is expressed by both thymocytes and TL⁺ T-cell leukemias. To elucidate the regulation of T18^d, different restriction fragments of the 5' flanking region between -457 and⁺ 146 were linked to the chloramphenicol acetyltransferase (CAT) gene and transfected into TL⁺ and TL- cells. By comparison of transiently expresssedCAT activity among cells transfected with differentCAT constructs, the results suggest that determination of TL⁺ vs TL phenotypes is located within the region -105 to - 33, and that an element essential to T18 d expression resides within the region - 33 to + 54. Putative DNA-binding factors characterizing particular cell types and displaying selective affinity for particular TI 8^d restriction fragments were identified by electrophoretic mobility shift assays with nuclear extracts (NEs). Two factors (or complexes) which bound specifically to the T18^d fragment-105 to - 33 were expressed preferentially in TL⁺ cells and thus may be involved in determining the tissue-selective expression of TI8^d. The close proximity of negative and positive cis-acting elements within the promoter region is consistent with regulation of T18^d gene expression by a variety of trans-acting factors whose production is attuned to development and differentiation. The data provided may serve as a guide to study the regulation of other categories of Tla genes that are normally silent in thymocytes but may become expressed by leukemia cells.     

Kinetic behaviour of succinate dehydrogenase of three fibre types in skeletal muscle. I. Effects of temperature and a competitive inhibitor

Summary The kinetic behaviour of succinate dehydrogenase [EC 1.3.99.1] in three fibre types of rat gastrocnemius was examined by a quantitative histochemical method without disruption of the cellular structure. 2-(2-Benzothiazolyl)-3-(4-phthalhydrazidyl)-5-styryl-tetrazolium chloride (BPST) and phenazine methosulphate were used as electron acceptors. On measurement of the absorbance value at 530 nm of BPST formazan, produced by the succinate dehydrogenase reaction in sections, it was found that the staining intensity of succinate dehydrogenase was linearly proportional to both the incubation time and the thickness of the slice therefore, the initial velocity of the staining could be calculated. By Michaelis-Menten (1913) treatment of the dependence of the initial velocity on the substrate concentration in the absence and the presence of a competitive inhibitor, malonate, the Km andVmax values for succinate and the Ki value for malonate were obtained. The Km and Ki values of the three fibre types were similar. The ratio of theVmax values of type A, B and C fibres was 1.02.03.3. The temperature dependence of the kinetic parameters was very similar in the three fibre types. These findings confirm that the differences in the staining intensity of the three fibre types reflect differences in the amounts, but not the properties, of succinate dehydrogenase.     

Regeneration of NAD(H) covalently bound to formate dehydrogenase with several second enzymes

Summary N ⁶-[N-(6-Aminohexyl)carbamoylmethyl]-NAD was covalently bound to formate dehydrogenase. The formate dehydrogenase-NAD complex, which contained 0.2 mol of reactive NAD moiety per subunit, functioned as an NAD(H)-regeneration system for a second coupled reaction involving one of the following enzymes; lactate, malate, alanine and leucine dehydrogenases, whose reductive reactions proceeded stoichiometrically in the absence of exogenous NAD.     

High concentration cultivation of Bifidobacterium longum in fermenter with cross-flow filtration

Summary High concentration cultivation of Bifidobacterium longum in a fermenter with cross-flow filtration using a ceramic filter is described. Continuous cross-flow filtration allowed complete recycling of the cells to the fermenter and also continuous separation of inhibitory metabolites. The final cell concentration attained in the cultivation was 54.4 g dry wt./l; this was seven times as high as that without cross-flow filtration. The time course of the cultivation with cross-flow filtration was predicted, based on the assumption that the specific growth rate can be expressed only as a function of concentrations of metabolites (acetate and lactate) in a culture broth.Nomenclature D dilution rate (h^-1) - m maintenance coefficient (h^-1) - OD ₅₇₀ optimal density at 570 nm - P _A acetate concentration (g/l) - P _A0 initial acetate concentration (g/l) - P _L lactate concentration (g/l) - P _L0 initial lactate concentration (g/l) - S lactose (substrate) concentration (g/l) - S ₀ initial lactose (substrate) concentration (g/l) - t cultivation time (h) - Y _x/s growth yield (g/g) - X dry cell concentration (g/l) - X ₀ initial dry cell concentration (g/l) - constant - constant     

Existence of fatty acyl-CoA oxidizing system in (micro)peroxisomes of rabbit aorta

A cyanide-insensitive palmitoyl-CoA oxidizing activity was detected in rabbit aorta. An assay developed for the arterial acyl-CoA oxidizing system was linear with respect to protein content of the homogenate between 12.5 and 100 micrograms and incubation time for at least 15 min. The system was shown to be localized in (micro)peroxisomes by centrifugation in sucrose density gradient. With a diet containing 1% (w/w) cholesterol and 3% (w/w) olive oil for 8 weeks the activity of peroxisomal beta-oxidation increased from 1.38 to 2.54 nmole/min/g aorta. These results show that the aortic catalase-positive particles have a capacity to oxidize fatty acyl-CoA and participate in fatty acid metabolism.     

Sedimentation of phytoplankton populations dominated by Microcystis in a shallow lake

The sedimentary flux of phytoplankton was measured using sedimenttraps in a shallow hypertrophic lake (Lake Kasumigaura), whereMicrocystis bloomed, from June to November 1983 The sedimenttraps were set at 0.5, 1.5 and 3.0 m depth in Takahamairi Bay(3.5 m depth). Microcystis spp. (including M.aerugmosa and M.viridis)in the traps were rare until early August, but increased thereafter.Sinking rates of Microcystis were 0.0045, 0.020 and 0.24 m day^–1in June–August, September and October respectively, whichwere far lower than those of Melosira (0.2–1.7 m day^–1)and Syncdra (0.2–1.0 m day^–1). The total sedimentaryfluxes of POC and that of algal carbon during the study periodwere 283.2 and 96.7 gC m^–2 which were 59.5% and 20.3%of the gross primary production (475.8 gC m^–2) respectively.The sedimentary flux of living algae measured by algal countswas large in June but small in August and September. On theother hand, the flux of detritus obtained by subtracting totalalgal carbon from POC was small in June and July but large inAugust and September. Therefore diatoms, which appeared mostlyin June, tended to sink as live algae, while Microcystis sankas detritus after being decomposed or consumed in the waterIt was concluded from the results of carbon budget calculationsand the respiration rate of the 1- to 20-µm fraction thatthe activity of decomposers or consumers increased greatly inthe short period at the end of the bloom of Microcystis.     

Biological half-time in rats exposed to nickel monosulfide (amorphous) aerosol by inhalation

This study reports the biological half-time of amorphous nickel monosulfide(NiS(A)) aerosol retained in rat lungs. Wistar male rats were exposed to NiS(A) aerosols (mass median aerodynamic diameter: 4.0 μm) for a single 4 h exposure, or for 7 h/d, 5 d/wk for 1 mo. The average exposure concentrations were controlled at 107 mg/m³ for the single exposure and at 8.8 mg/m³ for the repeated exposures by a dust generator consisting of a continuous fluidized bed with an overflow pipe and a screw feeder. After the exposures, the nickel contents in the rat organs, blood, and urine were measured and histopathological examinations were performed. The biological half time of NiS(A) in rat lungs was 20 h, which was extremely shorter than 21 mo of green nickel oxide (NiO(G)). There were no malignant tumors in any of the exposure groups.     

Immunoaffinity purification and characterization of nucleotide pyrophosphatase from human placenta

Nucleotide pyrophosphatase [EC 3.6.1.9] was purified to homogeneity from human placenta using a monoclonal antibody affinity column. By sodium dodecylsulfate--polyacrylamide gel electrophoresis, the purified enzyme showed a major band at a molecular size of 130 K. The enzyme was a glycoprotein with N-linked oligosaccharides consisting of both complex- and oligomannoside-types. Substrate specificity to hydrolyze phosphodiester and phosphosulfate linkages as well as other properties were similar to those of nucleotide pyrophosphatase and phosphodiesterase from other sources.