Colonial Morphology of Treponemes Observed by Electron Microscopy

The colonial morphology of three strains of cultivable, nonpathogenic treponemes including a human oral treponeme was examined by light and electron microscopy. Treponema phagedenis strains Kazan and Reiter produced large white colonies on the surface of solid media composed of sterility test broth, 0.9 to 3.1% agar, rifampin, and 12.5% rabbit or horse serum. A human oral treponeme, strain G7201, grew as diffused white zones on 0.9 to 3.1% agar plates. Under the cultural conditions employed agar concentrations slightly affected the time of appearance of colonies of the three strains of treponemes. When the colonies of these three strains were viewed by scanning electron microscopy, differences in their colonial morphology were observed. The 11-day-old colonies of human oral strain G7201 were very small, 5 to 15 μm in diameter, and had a slight irregular border. Kazan treponemes developed circular, entire and low convex colonies. Scanning and transmission electron microscopy revealed that the colonies of Reiter treponemes contained spherical forms almost up to 5 μm in diameter, each consisting of an outer membrane and a treponemal main body. They were very similar to the spherical bodies produced by strain G7201 in sucrose-containing broth.     

An Internal View of the Spherical Body of Treponema macrodentium as Revealed by Scanning Electron Microscopy

The osmium-dimethyl sulfoxide-osmium method for clear visualization of intracellular structure was used to observe the detailed inner structure of the spherical bodies produced in vitro by a human oral treponeme. Scanning electron microscopy of the cracked spherical body revealed no morphological differences between the outer and inner surfaces of the spherical body membrane, and that multiple folded or somewhat linear main bodies adhere closely to the inner surface. In addition, axial flagella partially free from the main bodies spread widely within the body to make a network, and a number of blebs ranging from approximately 1 μm to 0.2 μm in diameter were located near the terminal or subterminal areas of the main bodies. The origin of the blebs and the mechanism of spherical body formation are discussed.     

Computational Oral Absorption Simulation for Low‐Solubility Compounds

Bile micelles play an important role in oral absorption of low‐solubility compounds. Bile micelles can affect solubility, dissolution rate, and permeability. For the pH–solubility profile in bile micelles, the Henderson–Hasselbalch equation should be modified to take bile‐micelle partition into account. For the dissolution rate, in the Nernst–Brunner equation, the effective diffusion coefficient in bile‐micelle media should be used instead of the monomer diffusion coefficient. The diffusion coefficient of bile micelles is 8‐ to 18‐fold smaller than that of monomer molecules. For permeability, the effective diffusion coefficient in the unstirred water layer adjacent to the epithelial membrane, and the free fraction at the epithelial membrane surface should be taken into account. The importance of these aspects is demonstrated here using several in vivo and clinical oral‐absorption data of low‐solubility model compounds. Using the theoretical equations, the food effect on oral absorption is further discussed.     

Electron microscope studies on the vegetative cellular life cycle of Chlamydomonas reinhardi Dangeard in synchronous culture I. Some characteristics of changes in subcellular structures during the cell cycle, especially in formation of giant mitochondria

Changes in subcellular structures during the entire vegetativecell cycle of Chlamydomonas reinhardi Dangeard in synchronousculture were followed with an electron microscope. Giant mitochondriaof various shapes were temporarily formed, probably by fusionof smaller mitochondria, in the algal cells at an intermediatestage of the growth phase of the cell cycle. Formation of giantmitochondria was accompanied by a marked decrease in the oxygen-uptakeactivity of cells. Giant mitochondria divided into smaller formsconcurrently with a re-increase in the oxygen-uptake activityof cells. Some characteristics of changes in the structuresof chloroplast, the nucleus, the endoplasmic reticula, flagellaand dictyosomes are described. ¹ This work was reported in part at the 35th Annual Meetingof the Botanical Society of Japan, October 1970. (Received October 13, 1971; )     

Oxidation and esterification of cis- and trans-isomers of octadecenoic and octadecadienoic acids in isolated rat liver

The metabolism of 9-octadecenoic and 9,12-octadecadienoic acids with different geometrical configurations was compared in isolated perfused rat liver. More ketone bodies were produced when the trans-isomers were infused. In contrast, only the cis-isomer augmented the triacylglycerol secretion almost entirely as very-low-density lipoprotein (VLDL). Although these responses were independent of the difference in the degree of unsaturation in both the cis- and trans-isomers, the trans-monoenic acid compared to the trans-dienic acid was incorporated more readily into perfusate and hepatic lipids. Quantitative information was obtained with radioactive tracer experiments. The hepatic uptakes of 9-[10-14C]octadecenoic acids were comparable in the cis- and trans-isomers. The trans-octadecenoic acid compared to the cis counterpart was oxidized more readily and incorporated more into liver phospholipid but less into perfusate and liver triacylglycerol. These reciprocal responses counterbalanced each other. The lower rates of triacylglycerol synthesis and secretion in the liver perfused with the trans-octadecenoic acid was confirmed using [2- 3H]glycerol as a tracer. The marked difference in the channelling of cis- and trans-fatty acids in the pathways of oxidation and esterification seems to modify the VLDL secretion in perfused rat liver. Present observations indicate a considerable difference in the fate of unsaturated fatty acids with different configurations. trans-Fatty acids are expected to be an efficient energy source in animal tissues and may not be hyperlipidemic.     

Aldosterone biosynthesis and cytochrome P-45011 beta: evidence for two different forms of the enzyme in rats

Whereas cytochrome P-45011 beta has been recently shown to catalyze the two-step conversion of corticosterone to aldosterone in the bovine and porcine adrenal cortex, the identity of the enzyme involved in the two final steps of aldosterone biosynthesis in the rat adrenal cortex is as yet unknown. Mitochondria from capsular adrenals of sodium-deficient, potassium-replete rats converted corticosterone to 18-hydroxycorticosterone and aldosterone at markedly higher rates than mitochondria from capsular adrenals of sodium-replete, potassium-deficient rats. However, the same preparations exhibited no difference in the 11 beta-hydroxylase activity, i.e. the conversion of deoxycorticosterone to corticosterone. Only mitochondria of zona glomerulosa from rats with stimulated aldosterone biosynthesis contained a 49K protein which showed a strong cross-reactivity with a monoclonal antibody raised against purified bovine cytochrome P-45011 beta. By contrast, a crossreactive protein with a molecular weight of 51K was found in mitochondria of zona fasciculata and in mitochondria of zona glomerulosa from rats with a suppressed aldosterone biosynthesis. These findings indicate the existence of two different forms of cytochrome P-45011 beta in the rat adrenal cortex, with only one of them, i.e. the 49K form, being capable of catalyzing the two final steps of aldosterone biosynthesis in situ.     

Di(2-ethylhexyl)phthalate enhances hepatic phospholipid synthesis in rats

The effects of di(2-ethylhexyl)phthalate, a typical peroxisomal proliferator, on the activities of key enzymes in the glycerophospholipid synthetic pathway and the incorporation of lipid precursors into liver lipids in vitro were studied periodically in rats. When di(2-ethylhexyl)phthalate was fed at the 1% level to rats, glycerol-3-phosphate acyltransferase activity increased 2-3-fold in liver homogenates and microsomes in 2-4 days. The specific activity of microsomal CTP:phosphocholine cytidylyltransferase increased by 1.5-fold, whereas the cytosolic activity was depressed. The microsomal CDPcholine:diacylglycerol cholinephosphotransferase specific activity decreased, whereas the activity in the homogenates increased, suggesting the proliferation of the hepatic endoplasmic reticulum in di(2-ethylhexyl)phthalate-treated rats. The incorporation of [1(3)-3H]glycerol or [1-14C]acetate into liver phospholipids in vitro increased in 2 days and stayed at a high level up to 12 days. The present study confirmed that di(2-ethylhexyl)phthalate induced an enhancement of phospholipid synthesis in the liver. The increase in hepatic phospholipid synthesis by this drug is presumably linked to the proliferation of peroxisomes and other intracellular membranes.     

Transgenic tobacco resistant to a bacterial disease by the detoxification of a pathogenic toxin

Summary Some plant pathogens produce toxins which cause disease in infected plants. One of the pathogenic toxins, tabtoxin, is produced by Pseudomonas syringae pv. tabaci, which causes wildfire of tobacco. A tabtoxin resistance gene (ttr) coding for an acetyltransferase isolated from Pseudomonas syringae pv. tabaci was fused to the 35S promoter of the cauliflower mosaic virus (CaMV) to construct a chimeric gene for introduction into tobacco cells by Agrobacterium-mediated transformation. The transgenic tobacco plants showed high specific-expression of the ttr gene and no chlorotic symptoms caused by tabtoxin treatment or with infection by Pseudomonas syringae pv. tabaci. These results demonstrate a successful approach to obtain disease-resistant plants by detoxification of the pathogenic toxins which play an important role in pathogenesis.     

Picosecond Photochemistry of P700-Enriched and Vitamin K1-Depleted Photosystem I Particles Isolated from Spinach

Picosecond transient absorption changes, with a laser intensityas low as one photon absorbed per single reaction center, weremeasured with vitamin K₁-depleted and P700-enriched particleswhich were obtained by ether treatment of spinach PS-I particles.When P700 was in the oxidized state, a bleaching that correspondedto about one-seventh of the ground state absorption was observedjust after a laser flash (0 picosecond delay). A major partof the bleaching decayed with a lifetime of about 35 picoseconds,which corresponds to the relaxation of the excited antenna chl-ato the ground state. By contrast, when P700 was in the reducedstate, the bleaching observed at a 0 ps delay was broader, especiallyon the longer wavelength side than the ground state absorption,probably because of the generation of the excited state of P700.About one half of the bleaching decayed within 35 ps and theremaining half, which had a broad spectrum and a peak around682 nm, was conserved up to 2 ns. This long-lived bleachingprobes no picosecond decay of the radical pair P700⁺-A₀^–because electrons were not transferred from A₀¹ to A₁ in vitaminK₁-depleted particles. After addition of vitamin K₃, an analogof vitamin K₁, to the reduced particles, the bleaching around685 nm decayed successively with an apparent rate of about 150picosecond, while the bleaching around 700 nm was conservedfor up to 2 nanosecond. Thus, the bleaching remaining at 2 nsresembled the difference spectrum of P700, suggesting a subnanosecondquenching of A₀¹ by the externally added vitamin K₃. These observationssupport a recent proposal that the secondary electron acceptorA₁, in photosystem I, is vitamin K₁. ³Permanent address: Optics Laboratory, Korea Standards ResearchInstitute, Daedok Science Town, Chungnam 300-31, Korea. (Received October 24, 1988; Accepted April 14, 1989)     

Selective growth of a mutant in continuous culture of Bacillus caldolyticus for production of α-amylase

Summary In a continuous culture of Bacillus caldolyticus strain SP, which requires maltose as an inducer for production of -amylase in batch culture, a predominant mutant strain M1 which produced high amounts of -amylase in the absence of maltose in batch culture, developed. The change of cell population from strain SP to strain M1 in maltose-casitone medium was linear with time in the transient state after the change from batch to continuous culture at a dilution rate of 0.17 h^-1, and was completed in about 11 generations of bacterial growth. The dilution rate effect of continuous culture on -amylase activity was almost the same with both strains SP and M1. The maximum -amylase activity of 380 units/ml was observed at an intermediate dilution rate that was 11.5 times higher than -amylase activity at the end of a batch culture using the same medium. It was deduced that the enhancement of -amylase production in continuous culture was attributed partly to the predominant growth of a mutant strain with higher -amylase productivity.