Particulate Residue Research Articles

Microbial Control of the Citrus Rust Mite with the Mycoacaricide, Mycar registered

Mycar, a mycoacaricide produced by Abbott Laboratories as a wettable powder or dust was effective in stimulating premature fungal epizootics in citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Family Eriophyididae) populations in `Valencia' orange groves located in central and south Florida in 1979 and 1980. Hirsutella thompsonii (Strain: Fla. CBS 556. 77b), the active ingredient of Mycar was established on treated fruit and foliage via the particulate residue which supplied a substrate for mycelial growth and subsequent conidiogenesis by the fungus. Excellent crop protection was achieved with Mycar and a Mycar-oil combination in field trials. Oil, Dacagin, Nu-Film 17, Plyac and Ortho X-77 at recommended rates had no detrimental effect on the germination of primary conidia of H. thompsonii and Nu-Film 17 was an excellent spreader-sticker for Mycar formulated as a wettable powder.

Gel electrophoretic and density gradient analysis of the (K + + Ca 2+)-ATPase and the (Na + + K +)-ATPase activities of cardiac membrane vesicles

The two major ATPase activities of intact and leaky cardiac membrane vesicles (microsomes) were characterized with respect to ionic activation requirements. The predominant ATPase activity of intact vesicles was (K + + Ca 2+)-ATPase, an enzymic activity localized to sarcoplasmic reticulum, whereas the predominant ATPase activity of leaky, sodium dodecyl sulfate-pretreated vesicles was (Na + + K +)-ATPase, an enzymic activity localized to sarcolemma. The (K + + Ca 2+)-ATPase activity was stimulated 4- to 5-fold by 100 mM K + in the presence of 50 μM Ca 2+. Phosphorylation of the (K + + Ca 2+)-ATPase of intact vesicles with [γ- 32P]ATP was Ca 2+ dependent, and monovalent cations including K + increased the level of [ 32P]phosphoprotein by up to 50% when phosphorylation was measured at 5°C. After the intact vesicles were treated with SDS (0.30 mg/ml), (K + + Ca 2+)-ATPase was inactivated, as was Ca 2+-dependent 32P incorporation. The monovalent cation-stimulated ATPase activity of the particulate residue (SDS-extracted membrane vesicles) displayed the usual characteristics of ouabain-sensitive (Na + + K +)-ATPase and the activity was increased 9- to 14-fold over the small amount of patent (Na + + K +)-ATPase activity of intact membrane vesicles. 32P incorporation by the (Na + + K +)-ATPase of SDS-extracted vesicles was Na + dependent, and Na +-stimulated incorporation was increased 7- to 9-fold over that of intact vesicles. Slab gel polyacrylamide electrophoresis of both intact and SDS-extracted crude vesicle preparations revealed at least 40 distinct Coomassie Blue-positive protein bands and provided evidence for a possible heterogeneous membrane origin of the vesicles. Periodic acid-Schiff staining of the gels revealed at least two major glycoproteins. Simultaneous electrophoresis of the 32P-intermediates of the (K + + Ca 2+)-ATPase and the (Na + + K +)-ATPase in the same gels did not resolve the two enzymes clearly. With sucrose gradient centrifugation of intact membrane vesicles, it was possible to physically resolve the two ATPase activities. Latent (Na + + K +)-ATPase activity (unmasked by exposing the various fractions to SDS) was found in the higher regions of the gradient, whereas (K + + Ca 2+)-ATPase activity was primarily in the denser regions. A reasonable interpretation of the data is that cardiac microsomes consist of membrane vesicles derived both from sarcolemma and sarcoplasmic reticulum. (Na + + K +)-ATPase is localized to intact vesicles of sarcolemma but is mainly latent, whereas (K + + Ca 2+)-ATPase is mostly patent and is localized to vesicles of sarcoplasmic reticulum.

Lysosomal phospholipase a activities of rat ovarian tissue

1. 1. Lysosome-enriched fractions were prepared by differential centrifugation of homogenates of luteinized rat ovaries. Acid phospholipase A activities were characterized with [U- 14C]diacyl- sn-glycero-3-phosphocholine and 1-palmitoyl-2-[9, 10- 3H]- or [1- 14C]oleoyl- sn-glycero-3-phosphocholine as substrates. Acid phospholipase A 1 activity had properties similar to other hydrolases of lysosomal origin; subcellular distribution, latency and acidic pH optimum. Acid phospholipase A 2 activity with similar characteristics was also tentatively identified. We were unable to exclude the possibility that the combined action of phospholipase A 1 and lysophospholipase contributed to the release of acyl moieties from the 2-position of the synthetic substrates. 2. 2. Lysophospholipase activity was present in the lysosome-enriched fractions. This activity had an alkaline pH optimum. 3. 3. Phospholipase a 1 and A 2 activities solubilized from lysosome fractions by freeze-thawing were inhibited by Ca 2+ and slightly activated by EDTA. A Ca 2+-stimulated phospholipase A 2 activity, with an alkaline pH optimum, remained in the particulate residue of freeze-thawed lysosome preparations. This activity is believed to represent mitochondrial contamination. 4. 4. Activities of acid phospholipase A, as well as other acid hydrolases, increased approx. 1.5-fold between 1 and 4 days following induction of luteinization, suggesting a hormonal influence on lysosomal enzyme activities.

High Seas Oil Pollution: Particulate Petroleum Residues in the North Atlantic

The results of a continuing investigation into the occurrence and distribution of particulate petroleum residues on the surface of the North Atlantic are presented. From 1971 to 1974 more than 850 samples were collected from the North Atlantic on transects between the east coast of Canada and South America, the Caribbean, Baffin Bay and surrounding waters, the Labrador Sea, and the Azores. Repeated sampling was carried out in the Gulf of St. Lawrence and the region between Nova Scotia and Bermuda. The results indicate that the waters north of the Gulf Stream–North Atlantic Current system were virtually free from floating petroleum residues, while the waters of the Gulf Stream, Sargasso Sea, and Caribbean Sea were much more heavily polluted. Although concentrations as high as 91.8 mg/m2 were encountered, the general level of pollution was much less with tar contents in southern waters following a lognormal distribution with a geometric mean of 0.16 mg/m2. The geographical distribution of tar is interpreted in terms of inputs from shipping and tanker traffic, and surface circulation patterns.

Effects of temperature on extraction and electrophoretic migration of envelope proteins from Erwinia species

Extraction of the envelope of Erwinia sp. with sodium dodecylsulfate at 37°C results in solubilization of the majority of envelope proteins. Heating of these extracted proteins to 100°C causes a change in electrophoretic migration of some protein components. Extraction at 100 °C of the particulate residue which remains after extraction at 37 °C causes the release of at least two additional proteins which migrate as heavy bands in detergent gel columns.

The disaccharidase activity of a membrane fraction obtained from the rabbit renal cortex.

Abstract An investigation has been made into the disaccharidase activities found in the rabbit renal cortex with particular reference to their selective solubilization by the use of proteolytic enzymes. 1. 1. A membrane fraction which carries high specific activities of the enzymes maltase and trehalase (0.14 and 0.52 μmole substrate hydrolyzed/min per mg protein) has been isolated from the rabbit renal cortex. It appears to represent brush border membrane together with its associated external coat. 2. 2. Brief treatment of this particulate material with papain releases a soluble fraction which is excluded from Sephadex G-100, and which contains 8 % of the total protein and 90 % of the total maltase activity. The specific activity of this soluble enzyme is increased by 10–20 times. Almost all (99 %) of the trehalase activity remains on the membrane. 3. 3. Treatment of the membranes with trypsin also releases a soluble fraction excluded from G-100 but in smaller yield (approx. 3 % of total protein). However, no maltase and only a trace of trehalase activity could be detected in this fraction, almost all the activities being retained in the particulate residue.

A Visual Demonstration of the Beneficial Effects of Sewage Treatment for Phosphate Removal on Particulate Matter Production in Waters of Lakes Erie and Ontario

Filtered samples of raw sewage, biologically treated sewage, and sewage treated chemically for phosphate removal were added to unfiltered waters from lakes Erie and Ontario, and particulate residues (PR) on Millipore filters photographed after incubation in light for 10 and 30 days. PR levels in the sewage-enriched flasks were least in the case of sewage treated for removal of phosphates. Addition of phosphate to the phosphate-depleted effluent increased its PR generating ability to that of raw and biologically treated sewage. The removal of phosphates from sewage wastes thus appears to eliminate their fertilizing effect.

Association of heart hexokinase with subcellular structure

Sucrose extracts of minced pig heart muscle contain only 10–20% of the total tissue hexokinase activity. Treatment of the particulate residue with salts of monovalent cations induces a pH- and ionic strength-dependent solubilization of the enzyme. Evidence has been obtained indicating that this solubilization is reversible and that an equilibrium exists between the soluble and particle-bound forms of the enzyme. Glucose-6-phosphate also induces solubilization of heart hexokinase. This effect appears to be related to the ability of glucose-6-phosphate to combine with the specific regulatory site on the enzyme described by Crane and Sols. An irreversible and pH-independent solubilization of heart hexokinase has also been obtained with divalent cations.

Enhancement of mousevirulence of group A streptococci.

THE virulence of organisms can be enhanced by a variety of substances, mainly of carbohydrate nature (see review by Olitzki1). Current interest centres on mucin, which was found by Smith and his co-workers2–4 to owe its activity to the synergic action of three factors—viscosity, a particulate residue and a heparin. The present communication shows that bacteriological peptone and some of its hydrolysis products also have considerable virulence-enhancing activity.

Identification of a heparin as a main component of the third factor involved in the virulence-enhancing action of hog gastric mucin.

PREVIOUS work1–4 has shown that the virulence-enhancing action of hog gastric mucin is due to a synergic action between two non-specific factors (a viscous medium and particulate residue), and a more specific soluble third factor. Partial purification of the latter3 yielded a heterogeneous product which was predominantly peptide in nature, but which contained 5–10 per cent of carbohydrate residues. Further purification, using a revised assay4 in which the two non-specific factors are maintained constant, has shown that the carbohydrate moiety is responsible for the activity.