Soluble End Products Research Articles

Plant Metabolism Of Xenobiotics. Comparison Of The Metabolism Of 3.4-Dichloroaniline In Soybean Excised Leaves And Soybean Cell Suspension Cultures

Excised leaves and cell suspension cultures of soybean (Glycine max L.) were incubated with [UL-14C]-3,4-dichloroaniline. The compound was almost completely metabolized after 48 h in both systems; it was apparent that the major detoxification pathways present in the excised leaves were also present in the cultured cells. Besides considerable amounts of insoluble residues, the N-glucosyl and the N-malonyl conjugates of 3,4-dichloroaniline, and a yet unknown metabolite was formed in the excised leaves; tentatively the latter was identified with the 6′-O-malonylester of N-glucosyl-3,4-dichloroaniline. The cell suspension cultures produced predominantly the N-malonyl conjugate, besides negligible amounts of the N-glucosyl conjugate, and insoluble residues; the majority of the N-malonyl compound was excreted into the medium. It was shown, that the metabolism of 3,4-dichloroaniline in excised leaves and cell suspension cultures of soybean was directed towards different end products: the excised leaves were able to make extensive use of cell wall structures as a deposit for xenobiotic bound residues, resembling plants in this respect; lack of these structures in the cultured soybean cells resulted in a soluble end product, namely the N-malonyl conjugate

Carbon Fluxes in Mature Peach Leaves

The turnover and transport of sugars are described in peach (Prunus persica L. Batsch), a species exporting both sucrose and sorbitol. Apparent export rate was slower in peach leaves than in leaves of herbaceous species. Sorbitol was the major soluble end product of photosynthesis and the major soluble carbohydrate in the leaf (higher than sucrose). Carbon fluxes were described using (14)C labeling, radioactivity loss curves, and compartmental analysis during the second half of the photoperiod when chemical steady state was reached for soluble carbohydrates. The measured specific radioactivity of sucrose was typical of a primary product. The delayed decrease in specific radioactivity of sorbitol indicated that part of it was secondarily synthesized. Sucrose is proposed to be the carbon source for the delayed synthesis of sorbitol in the light. The sorbitol to sucrose ratio was higher in the petiole than in the leaf tissues. In phloem sap, obtained using stylectomy of aphids and collected from the main stem between source leaves and apex, this ratio was lower than in the petiole, suggesting a preferential sorbitol demand by sinks.

Iron Pyrite Oxidation by Thiobacillus Ferrooxidans: Sulfur Intermediates, Soluble End Products, and Changes in Biomass†

Parameters of growth of Thiobacillus fenooxidans were examined with the use of iron pyrite as the substrate. The concentrations of end products deviated from the stoichiometric lFe/2S ratio, reflecting the precipitation of Fe(lII). Minor amounts of trithionate accumulated transiently during growth, tetrathionate was not detected, and thiosulfate was present at trace concentrations. Bacterial growth was monitored by measurement of cell protein; 17-34% of the bacterial cells were associated with the solids. A molar growth yield of 1.92 (g dry weight bacteria per mol FeS2) was determined from batch culture data and growth was estimated to couple with pyrite oxidation at 10-12% efficiency.

In vivo esterification of a synthetic 125I-labeled fatty acid into cardiac glycerolipids.

Recent studies have demonstrated that fatty acids can be successfully utilized as myocardial imaging agents. 125I-paraphenylpentadecanoic acid (IPPA), a synthetic fatty acid, accumulates within the myocardium and can be visualized by conventional gamma scintigraphy. To determine if IPPA was incorporated into cardiac lipids in a pattern similar to palmitate, IPPA was purified by liquid chromatography, bound to fat-free albumin, and administered by intravenous injection to male Sprague-Dawley rats. After 2.5, 5, 10, and 30 min, the hearts were excised and the lipids were extracted in chloroform-methanol. The uptake of IPPA into the myocardium reached a maximal value after 2.5 min, and 95% of the 125I was found in the cardiac lipid fraction after chromatographic separation. Over 65% of the IPPA was found in cardiac triglycerides, whereas approximately 10% was present in membrane phospholipids (predominantly phosphatidylcholine and phosphatidylethanolamine). This pattern of IPPA incorporation is similar to that reported for intravenously administered [3H]palmitate. The rate of turnover of IPPA present in the triglyceride fraction was threefold faster than the rate of the IPPA which was incorporated into membrane lipids. At all time periods examined, the methanol-water soluble end products of IPPA oxidation did not account for more than 5% of the total IPPA present within the myocardium. The present study indicates that IPPA is incorporated primarily into triglycerides and other cardiac lipids in a pattern similar to palmitate.

Effects of chetomin on growth and acidic fermentation products of rumen bacteria.

Chetomin, an antibiotic metabolite of Chaetomium spp., was tested in the form of its tetrathiol derivative for its effects on growth and carbohydrate metabolism by five strains of functionally important rumen bacteria. The compound was bacteriostatic for the strains tested and Gram-positive bacteria were more sensitive to inhibition than Gram-negative bacteria. In an anaerobic broth dilution assay using a medium lacking rumen fluid, the minimum inhibitory concentration (MIC) of chetomin which completely inhibited growth of Butyrivibrio fibrisolvens D1 for 18 h at 39 degrees C was 40 micrograms X mL-1. The MICs determined under the same conditions for Megasphaera elsdenii B159, Selenomonas ruminantium GA192, and Succinivibrio dextrinosolvens 24 were 160, 600, and 60 micrograms X mL-1, respectively. The MIC for cellulose hydrolysis by Ruminococcus albus 7 was 20 micrograms X mL-1. Chetomin at concentrations below the MIC appeared to inhibit the separation and division of cells in cultures of B. fibrisolvens D1. Chetomin consistently stimulated acetate production from glucose by B. fibrisolvens D1, M. elsdenii B159, and S. ruminantium GA192 at the expense of compounds which comprised major soluble end products of fermentation in cultures lacking chetomin.

Biochemistry of insect differentiation: A system for studying the mechanism of chitinase activity in vitro

Results obtained with an in vitro system for the study of chitinase are described. The system involves soluble enzyme protein(s) and an insoluble substrate preparation. With insect molting fluid chitinase, it shows properties that parallel those observed during in vivo breakdown of cuticle during the molt. For example, molting fluid chitinase activity not previously exposed to chitin is stronly and specifically adsorbed to the substrate, in contrast to other enzymatic activities including hexosaminidase (chitobiase) present in molting fluid. This leads to partial purification of molting fluid chitinase activity reflected in increased specific activity of chitinase associated with the insoluble chitin substrate; we have previously reported increase of specific chitinase activity of (deproteinized) cuticle resulting from its incubation with molting fluid ( M. L. Bade and A. Stinson, 1978, Biochem. Biophys. Res. Commun. 84, 381–388). Soluble end product is generated rapidly and linearly with time by the in vitro system; the end product is assumed to be N-acetylglucosamine since the specific radioactivity of this compound is unchanged during the 10 min required for assay. Molting fluid chitinase activity may involve a number of polypeptides ranging in molecular weight from 145,000 to less than 20,000 daltons. The system described gives results consistent with a processive mechanism for molting fluid chitinase, i.e., data are given demonstrating that molting fluid chitinase continues to act on the same chitin particle(s) with which it initially associates rather than diffusing freely from substrate particle to substrate particle, and the product of its action appears to be a monosaccharide rather than a mixture of oligosaccharides. Processive behavior for chitinase would be predicted from the known structure, and the in vivo measured rate of breakdown, of cuticle chitin during the molt; the preliminary nature of this conclusion, based on what is so far known about the structure of the substrate used in the in vitro system, is briefly discussed.

Biochemistry of insect differentiation. Requirements for high in vitro moulting fluid chitinase activity

A method for preparing chitinase substrate is described; the substrate reproducibly gives high chitinase activity under suitable conditions. For moulting fluid chitinase, these are: a chitin concentration of at least 2 mg/ml, pH 6.5, and presence of calcium; addition of an inhibitor for neutral protease is helpful. Activity may be measured in minutes, either colourimetrically or by counting acid-soluble product from in vivo labelled chitin. N- Acetylglucosamine is the chief soluble end product. Moulting fluid chitinase appears to form a complex with chitin and calcium which successfully competes with EGTA for calcium; the dissociation constant is therefore at least as low as 10 −7 M. A transient increase in product release of chitinase accompanies the first interaction of chitin, chitinase and calcium ions.

Zur funktion des afterschornsteinschleuderns bei diademseeigeln

In some diadematid sea urchins, the anus opens at the top of the anal cone, i.e., a chimney-like elevation of the periproctal membrane. With this anal cone, Diadema setosum can perform a rotatory movement which often lasts more than 1 h. During rotation, the anal cone inclines towards the rotation axis which yields a device similar in function to a centrifugal pump that can throw water out of the rectum. The calculation of the hydrodynamic mechanism pertinent to the parameters given for D. setosum shows that anal-cone rotation is sufficiently effective to empty the rectum and a great part of the hind gut within a short time. This allows a more rapid water change in the second intestinal circuit, which could provide several advantages: (1) increased rinsing results in better evacuation of soluble metabolic end products which, in turn, promotes their excretion by the hind gut; (2) provision of oxygen-rich water to the intestine improves the oxygen supply to the perivisceral cavity in cases of increased oxygen demand; (3) faecal pellets are expelled into the free water and do not sink to the aboral body surface, where they would be difficult to remove because of the lack of tridentate pedicellaria. The rotating anal cone — in D. setosum encireled by an orange iris-like ring — probably resembles a rolling eye, which may deter predators.

Adaptations of Crustaceans to Land: A Summary and Analysis of New Findings

Crustaceans have adapted to land through various morphological, physiological, biochemical, and behavioral modifications, of which some are shared by all land-dwelling crustaceans and others are unique to animals within a particular habitat. Among the three groups of crustaceans having truly terrestrial members, the amphipods have achieved their success on land primarily by behavioral means, while the isopods and the decapods have developed many morphological, physiological, and biochemical adaptations as well. In all three groups, behavioral modifications ensure that loss of water is minimal, that the animals are exposed to favorable rather than extreme environmental conditions, and that the fine line between evaporative cooling and excessive dehydration is maintained. In most crustaceans the excretion of nitrogenous wastes requires that copious supplies of water be available for washing away the soluble end-products. Yet terrestrial isopods are able to excrete ammonia as a gas, without being subject to toxic side-effects. In decapods, either ammonia or insoluble uric acid may be excreted, with ammonia the more likely product when water is available, uric acid when water is scarce. In adult land crabs water balance is maintained through the concerted action of gills, pericardial sacs, and gut. These organs may take up, store, and redistribute salts and water in response to control exerted by the central nervous system through its secretory products. In larvae of land crabs these organs are not known to function in this way. Rather, the larvae are adapted to cope with osmotic problems of their planktonic existence. Gaseous exchange in adult land crabs is carried on not only by the gills but also by the highly vascularized lining of the branchial chambers, and the hemocyanin ot these crabs is adapted to function in the environment peculiar to each species. Terrestrial crabs seem unable to withstand low temperatures, but their high rate of cytochrome c oxidase activity may help them to survive when temperatures are high. Modifications in behavior must have occurred quite early in the transition of crustaceans from sea to land. Then, as now, appropriate behavioral responses to light, temperatuie, humidity, tidal cycles, and so on. were crucial if a terrestrial animal was to survive. Social interactions, both for courtship and for aggression, required the sending and receiving of appropriate visual and acoustic signals and were promoted by the ritualization of potentially injurious patterns of behavior.

The properties and effects of osmium tetroxide as a tissue fixative with special reference to its use for electron microscopy

Osmium tetroxide has been demonstrated to produce excellent fixation of the cytoplasm of cells, particularly for those to be examined in the electron microscope. The action of osmium tetroxide on various tissue constituents differs in its rate and nature. The reaction with lipids is probably by way of an affinity of osmium tetroxide for double bond configurations, thus forming unstable osmium esters which decompose to deposit osmium oxides or hydroxides at the site of activity. Little is known of the reaction of osmium tetroxide with proteins, but in preliminary studies it has been shown to produce quickly an initial gelation of protein solutions which, in the case of albumin, show no well-defined structure in the electron microscope. Coagulation images are, however, evident after other fixing agents. It is postulated that by virtue of its tetrahedral configuration, OsO 4 may form polymer-like structures with proteins establishing linkages at double bond containing groups. This initial gelation may then be followed by a further oxidation and the production of soluble end products, which after long fixation wash out of the cell.