Invertase and phosphatase of yeast in a phosphate-limited continuous culture

Summary Deficiency of inorganic phosphate caused the hyper production of invertase and the derepression of acid phosphatase in a continuous culture ofSaccharomyces carlsbergensis. The specific invertase activity was 40,000 enzyme units per g dry cell weight at a dilution rate lower than 0.05 h^–1 with a synthetic glucose medium of which the molecular ratio of KH₂PO₄ to glucose was less than 0.006. This activity is eight fold higher than in a batch growth and 1.5 fold as much as the highest enzyme activity observed so far in a glucose-limited continuous culture.For the hyper production of invertase, it is necessary to culture the yeast continuously by keeping the Nyholm's conservative inorganic phosphate concentration at less than 0.2 m mole per g dry weight cell. The derepression of acid phosphatase brought about by phosphate deficiency, was similar in both batch and continuous cultures.Nomenclature D dilution rate of continuous culture (h^–1) - E_i invertase concentration in culture (enzyme unit l^–1) - E_p acid phosphatase concentration in culture (enzyme unit l^–1) - P inorganic phosphate concentration in culture (mM) - S glucose concentration in culture (mM) - X cell concentration in culture (g dry weight cell l^–1) Greek Letter specific rate of growth (h^–1) Suffix f feed - 0 initial value     

Effect of short — chain fatty acids on electrical activity of the small intestinal mucosa of rat

Intravenous administration of short-chain fatty acid (SCFA), such as propionate, butyrate, valerate and caproate, caused a transient increase in transmural potential difference (p.d.) across the small intestine of rat $\text{in vivo}$. There was a sigmoid relationship between the change in the p.d. and the logarithm of the dose of SCFA. The median effective dose of propionate, n-butyrate, n-valerate and n-caproate, which was calculated from the each dose-response curve obtained from the terminal ileum, 1.31, 1.43, 0.83 and 0.81 μmole, respectively. Repeated administrations of the same dose of propionate evoked progressively smaller response. The dose-response curve of propionate was shifted to the left by neostigmine and to the right by atropine, suggesting that the action of SCFA may be mediated by acetylcholine, which was released from a nerve ending.     

Catenation and supercoiling in the products of bacteriophage λ integrative recombination in vitro

Catenanes (interlocked circular DNA molecules) are the exclusive products of the bacteriophage λ integrative recombination reaction in vitro when the substrate is a supercoiled DNA molecule containing both the attP and attB sites. It is proposed that the catenation results from the superhelical form of the substrate DNA. We also show that both circular DNA products of a single recombination event can be recovered as superhelical molecules with a superhelical density approximately that of the substrate DNA. The recombination reaction must therefore occur as a coupled process which does not permit free rotation around single-strand breaks at any stage.     

Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach

Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO₂ under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO₂.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO₂ at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO₂-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO₂was due to superoxide radicals (O₂^–). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO₂-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D₂O. These results suggest thatlipid peroxidation in SO₂-fumigated leaves was due to singletoxygen ¹O₂ produced from O_2^–. (Received May 15, 1980; )     

Depolarized light-scattering studies of bilayer structures in phospholipid vesicles

Depolarized light scattering has been used to investigate the hydrocarbon chain packing of phospholipids in vesicles below the phase transition and ordering of their chains above the phase transition. The chain packing and ordering have been demonstrated for vesicles of l-α-dipalmitoylphosphatidylethanolamine and some phosphatidylcholines of different hydrocarbon chain lenghts. Anisotropy ratios for phospholipid vesicles could be determined by measuring depolarization ratios for several vesicle sizes at low concentrations of the lipids. The following results were obtained. Hydrocarbon chains of l-α-dimyristoyl and distearoylphosphatidylcholines below their phase transitions pack at tilting angles in good agreement with X-ray diffraction data. On the other hand, hydrocarbon chains of dipalmitoylphosphatidylethanolamine pack perpendicular to the bilayer surface. Values of the averaged order parameter for dimyristoyl, dipalmitoyl and distearoylphosphatidylcholines at 2.5°C above their phase transition are all the same and the value for dipalmitoylphosphatidylcholine is in agreement with results from ²H-NMR experiments. The value of the order parameter for dipalmitoylphosphatidylethanolamine is slightly larger than that for dipalmitoylphosphatidylcholine.     

Unsaturated diacylglycerol as a possible messenger for the activation of calcium-activated, phospholipid-dependent protein kinase system

A small quantity of unsaturated diacylglycerol (DG) sharply decreased the Ca²⁺ and phospholipid concentrations needed for full activation of a Ca²⁺-activated, phospholipid-dependent multifunctional protein kinase described earlier (Takai, Y., Kishimoto, A., Iwasa, Y., Kawahara, Y., Mori, T. and Nishizuka, Y. (1979)$\text{J.}\text{Biol.}\text{Chem.}\text{254}$. 3692–3695). In the presence of unsaturated DG and micromolar order of Ca²⁺, phosphatidylserine (PS) was most relevant with the capacity to activate the enzyme, whereas phosphatidylethanolamine and phosphatidylinositol (PI) were far less effective. Phosphatidylcholine was practically inactive. It is possible, therefore, that unsaturated DG, which may be derived from PI turnover provoked by various extracellular stimulators, acts as a messenger for activating the enzyme, and that Ca²⁺ and various phospholipids such as PI and PS seem to play a role cooperatively in this unique receptor mechanism.     

Hydrolase production by Aspergillus niger in solid-state cultivation

Summary A production of macerating enzymes which liquefy and hydrolyze the mandarin orange peel was studied in a solid state cultivation of Aspergillus niger on wheat bran substrate. Solid state cultivation in a 2 drum fermenter capable of interchangeable operation under dynamic or static conditions were carried out maintaining the moisture content of the substrate at 32, 39, 46, 56, 67, and 74%. Biomass grown on the solid substrate was estimated on the basis of a constant value of glucosamine content of A. niger, 50 mg glucosamine/g cell. A linear relationship between oxygen uptake rate and growth rate observed in all the experiments gave an oxygen growth yield, Y_X/O, of 28.5 g cell/mol O₂. The rate of macerating enzyme formation was also in proportion to the growth rate irrespective of the difference of the moisture content of the substrate.The enzyme accumulation on the solid substrate, the growth rate and oxygen uptake rate were maximum when the moisture content of the substrate was maintained at ca. 56% ascending from 32 to 56 and descending from 56 to 74.     

Studies of oligosaccharide linkages by simultaneous determination of component aldehydes in dialdehyde fragments as (2,4-dinitrophenyl)hydrazones

The component aldehydes in dialdehyde fragments formed by periodate oxidation of oligosaccharides were converted quantitatively into the corresponding (2,4-dinitrophenyl)hydrazones by the simple procedure of treatment with excess (2,4-dinitrophenyl)hydrazine hydrochloride in 1,2-dimethoxyethane. Then, by chromatographic separation of the hydrazones on a small column of silica gel and subsequent spectrophotometric analysis, it was possible to determine the position of glycosidic substitution in μmolar amounts of various types of glucobioses, oligosaccharides of senega, and some synthetic (1→6)-β-D-gluco-oligosaccharides.     

Possible intrachromosomal duplication in a case of trisomy 9p

Summary A 5-year-old boy with multiple minor anomalies and mental retardation was found to have chromosomal condition of 46,XY,inv dup(9p)(pterp13::p21p24::p13qter). The clinical features of the propositus fit well with those of trisomy 9p which have been established to be a clinical entity.