A new species of coccinellid feeding on scale insects in West Pakistan

Résumé Les auteurs décriventPseudoscymnus simmondsi, espèce nouvelle deCoccinellidae prédatrice dePinnaspis strachani (Cooley) surFicus palmata au Pakistan occidental. Les autres espèces du genre sont connues seulement de l'Extrême-Orient.

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This research has been financed in part by a grant made by the United States Department of Agriculture, Agricultural Research Service.     

Thermostability of Bacillus cereus penicillinase

Williams, Daniel H., III (Hahnemann Medical College, Philadelphia, Pa.), A. Bondi, A. G. Moat, and F. Ahmad. Thermostability of Bacillus cereus penicillinase. J. Bacteriol. 91:257-261. 1966.-The extracellular penicillinase of Bacillus cereus, strain 13-10, exhibited an unusual thermostability. Whereas it was completely and irreversibly inactivated by heating at 70 C, it retained considerable activity when heated at 100 C for 30 min. The active enzyme remaining was completely stable to further heating at temperatures from 40 to 100 C for as long as 1 hr. Preparations of the enzyme heated to 100 C possessed pH (7.0) and temperature (37 C) optima identical with the unheated enzyme. Furthermore, both enzyme preparations exhibited identical combining capacity for the substrate (penicillin G), suggesting that the two preparations had similar hydrolytic properties. Our findings suggest that heating of penicillinase at 100 C results in the formation of a protein complex which is resistant to further denaturation by heat and other agents. Addition of certain metal ions to the enzyme solution before heat treatment increased the stability to heat at 100 C by virtue of their ability to induce complex formation. Pectin was shown to decrease thermostability, presumably by preventing aggregation of proteins present in the enzyme preparations. The well-known stabilizing effect of gelatin may be attributed to its role in enhancing complex formation.     

Failure of spermatozoa from T/t mice to fertilize in vitro is overcome by zona drilling

Failure of epididymal spermatozoa from T/t mutant mice, but not from t/t individuals, to fertilize oocytes in vitro was partially overcome by opening a small aperture in the zona pellucida with acidified Tyrode's solution to permit direct access of the spermatozoon to the vitellus. This study provides a model system to evaluate requirements for successful zona drilling in the treatment of human infertility and further insights into the effects of the t complex on sperm fertility.     

Effects of Electrical Stimulation on Molecular Forms of Butyrylcholinesterase in Denervated Fast and Slow Latissimus Dorsi Muscles of Newly Hatched Chicken

The effects of denervation and direct electrical stimulation upon the activity and the molecular form distribution of butyrylcholinesterase (BuChE) were studied in fast-twitch posterior latissimus dorsi (PLD) and in slow-tonic anterior latissimus dorsi (ALD) muscles of newly hatched chicken. In PLD muscle, denervation performed at day 2 substantially reduced the rate of rapid decrease of BuChE specific activity which takes place during normal development, whereas in the case of ALD muscle little change was observed. Moreover, the asymmetric forms which were dramatically reduced in denervated PLD muscle were virtually absent in denervated ALD muscle at day 14. Denervated PLD and ALD muscles were stimulated from day 4 to day 14 of age. Two patterns of stimulation were applied, either 5-Hz frequency (slow rhythm) or 40-Hz frequency (fast rhythm). Both patterns of stimulation provided the same number of impulses per day (about 61,000). In PLD muscle, electrical stimulation almost totally prevented the postdenervation loss in asymmetric forms and led to a decrease in BuChE specific activity. In ALD muscle, electrical stimulation partially prevented the asymmetric form loss which occurs after denervation. This study emphasizes the role of evoked muscle activity in the regulation of BuChE asymmetric forms in the fast PLD muscle and the differential response of denervated slow and fast muscles to electrical stimulation.     

Alteration of follicular steroid secretion and thecal morphology after in-vitro exposure of individual pig follicles to follicle regulatory protein

Medium-sized (4-6 mm) pig follicles were incubated for 10 h and then examined via light microscopy. Treatment with pig FSH resulted in significantly increased concentrations of oestradiol, testosterone, androstenedione and progesterone in the medium. Follicle regulatory protein (FRP) alone (1 micrograms/ml) decreased follicular secretion of oestradiol (56%) and progesterone (53%) but stimulated the secretion of testosterone (226%) and androstenedione (139%). In the presence of 1 ng FSH/ml, the inhibitory effect of FRP on oestradiol secretion was enhanced (74%), progesterone values were unaffected and secretion of testosterone and androstenedione were reduced by 66% and 53%, respectively. All effects of FRP were fully overcome by 1 micrograms FSH/ml. The incidence of atresia, as defined by granulosa cell pycnosis, was similar in all treatment groups (1-3 of 10 follicles per group). The remaining follicles had intact granulosa cells. However, follicles treated with FRP (1 micrograms/ml) + FSH (1 ng/ml) had pycnotic nuclei in the theca interna cells, in the presence of an intact stratum granulosum. External exposure of follicles to FRP may not reflect physiological conditions since, in vivo, thecal pycnosis is never observed before granulosa cell pycnosis. However, the present results indicate that FRP is potentially capable of altering both follicular morphology and steroidogenesis. We suggest that FSH and FRP interact to affect follicular development.     

Glutathione S-transferases of human lung: characterization and evaluation of the protective role of the alpha-class isozymes against lipid peroxidation.

Glutathione S-transferase (GST) isozymes of human lung have been purified, characterized, quantitated, and, based on their structural and immunological profiles, identified with their respective classes. The tau-, mu-, and alpha-class GSTs represented 94, 3, and 3% activities of total human lung GSTs toward CDNB, respectively, and 60, 10, and 30% of total GST protein, respectively. Both the mu- and the alpha-class GSTs of human lung exhibited heterogeneity. The two mu-class GSTs of human lung had pI values of 6.5 and 6.25 and were differentially expressed in humans. Significant differences were seen between the kinetic properties of these two isozymes and also between the lung and liver mu-class GSTs. The alpha-class GST isozymes of lung resolved into three peaks during isoelectric focusing corresponding to pI values of 9.2, 8.95, and 8.8. All three alpha-class GSTs isozymes had blocked N-termini and were immunologically similar to human liver alpha-class GSTs. Peptide fingerprints generated by SV-8 protease digestion and CNBr cleavage indicated minor structural differences between the liver and the lung alpha-class GSTs. The three alpha-class GSTs of lung expressed glutathione peroxidase activities toward the hydroperoxides of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol, with Km values in the range of 22 to 87 microM and Vmax values in the range of 67-120 mol/mol/min, indicating the involvement of the alpha-class GSTs in the protection mechanisms against peroxidation. All three classes of lung GSTs expressed activities toward leukotriene A4 methyl ester and epoxy stearic acid but the mu-class GSTs had relatively higher activities toward these substrates.     

Construction of a cDNA for the human c-fes protooncogene protein-tyrosine kinase and its expression in a baculovirus system.

Previous studies have established that the 93-kDa protein-tyrosine kinase (PTK) encoded by the human c-fes protooncogene plays an active role in the induction of terminal myeloid differentiation. However, this enzyme is expressed at very low levels in myeloid cells, making isolation of sufficient quantities for detailed biochemical analysis difficult. To overcome this problem, we used the polymerase chain reaction to construct a full-length c-fes cDNA from overlapping 5' and 3' partial cDNA sequences. The c-fes cDNA was expressed at high levels in a baculovirus system, and the catalytically active recombinant c-fes gene product p93c-fes was partially purified by DEAE-Sepharose and tyrosine-agarose chromatography. Recombinant p93c-fes was indistinguishable from the native protein in terms of its apparent molecular weight following SDS-PAGE, catalytic activity, Km for poly(Glu,Tyr)4:1, antigenicity, and phosphopeptide pattern generated with Staphylococcus aureus protease.     

The effects of soil warming on plant recruitment

We demonstrate, using a simple field experiment, that soil warming is sufficient, independent of other cues, to potentially alter the recruitment of Betula pendula seedlings. This study suggests that changing temperature, and correlated changes in edaphic factors, can alter patterns in plant recruitment via differential effects on seed dormancy. Increased soil temperatures (of less than 5 °C) throughout the year led to a significant increase in the number of birch seedlings that emerged from soil samples collected in the spring. No concomitant changes in the emergence of other species was observed. Such temperature induced changes in seedbank dynamics and their subsequent effects on the competitive interactions within a plant community suggest far reaching ecological consequences of current increases in global temperature.     

Characterization of active recombinant 2,3-dihydro-2,3-dihydroxybiphenyl dehydrogenase from Comamonas testosteroni B-356 and sequence of the encoding gene (bphB).

2,3-Dihydro-2,3-dihydroxybiphenyl-2,3-dehydrogenase (B2,3D) catalyzes the second step in the biphenyl degradation pathway. The nucleotide sequence of Comamonas testosteroni B-356 bphB, which encodes B2,3D, was determined. Structural analysis showed that the dehydrogenases involved in the bacterial degradation of aromatic compounds are related to each other and that their phylogenetic relationships are very similar to the relationships observed for dioxygenases that catalyze the initial reaction in the degradation pathway. The bphB sequence was used to produce recombinant active His-tagged B2,3D, which allowed us to describe for the first time some of the main features of a B2,3D. This enzyme requires NAD+, its optimal pH is 9.5, and its native M(r) was found to be 123,000, which makes it a tetramer. These characteristics are very similar to those reported for the related enzyme cis-toluene dihydrodiol dehydrogenase. The Km value and maximum rate of metabolism for 2,3-dihydro-2,3-dihydroxybiphenyl were 73 +/- 16 microM and 46 +/- 4 nmol min-1 microgram-1, respectively. Compared with the cis-toluene dihydrodiol dehydrogenase, B2,3D appeared to be more substrate specific since it was unable to attack cis-1,2-dihydroxy-cyclohexa-3,5-diene.