Fluorouracil and the isolation of mutants lacking uridine phosphorylase in Escherichia coli: location of the gene

Summary A selective technique is described for the isolation of mutants of Escherichia coli lacking uridine phosphorylase and the location of the gene specifying this enzyme on the bacterial chromosome is determined. Using strains with appropriate lesions it is shown that there are three routes via which 5-fluorouracil can be converted to compounds which inhibit cell growth.     

Intra- and extraganglionic peripheral cholinergic neurons in the urogenital organs of the cat

Summary The distribution of cholinergic neurons in the urinary tract and male genital organs of the cat was studied by a histochemical method for acetylcholinesterase. In addition to cell clusters in autonomic ganglia (intraganglionic cells), isolated extraganglionic cholinergic cells were found within the innervated tissues, usually in association with nerve trunks and blood vessels. Smaller neural cells with multiple axonal processes, identical to Cajal's interstitial cells, were found in the meshes of the terminal nerve plexus in smooth muscle, lamina propria and vascular wall.It is concluded that peripheral cholinergic neurons, like their adrenergic analogues, are arranged as a short intraganglionic, a shorter extraganglionic, and a terminal system of neurons.Supported in part by grants 10465 and 11285 from the USPHS and the Henry C. Buswell Urology Research Fund.     

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.     

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.     

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.     

Fungal population in the atmosphere of Ismailia City

Fungal spore populations in the outdoor and indoor atmosphere of Ismailia have been studied during the period from March 1992 to May 1993. A total of 23 350 cfu and 73 species were recorded,Cladosporium cladosporioides, Aureobasidium pullulans andAspergillus flavus were the most abundant. The indoor and outdoor mycoflora showed marked quantitative and qualitative differences. In view of count, recorded species could be categorized into three groups as follows: (a) species showing higher counts in out- than indoor, (b) species showing the opposite trend i.e. lower counts in out-door than indoor, (c) species showing approximately equal counts in out- and indoor. Regarding seasonal periodicity, March and either September or October showed the highest count for both normal fungal flora (NFF) and opportunistic fungal flora (OFF). While January and July showed the lowest count of them both, May but not July was the lowest as for outdoor NFF.     

Oil palm (Elaeis guineensis) protoplasts: isolation, culture and microcallus formation

Procedures are deseribed for the efficient isolation of protoplasts from a variety of oil palm (Elaeis guineensis Jacq.) tissues. Various factors including donor source, composition of enzyme mixture and culture medium affected the yield and viability of the protoplasts Polyembryogenic cultures of oil palm were the most suitable starting material in terms of yield, viability and metabolic competence. Pectolyase Y-23 in association with cellulase and hemicellulase was required for the efficient release of protoplasts from the oil palm tissues. Limited cell division to form microcallus was observed at very low frequency (<0.01%) when glutathione and catalase were incorporated in the culture medium.Abbreviations 2,4-d dichlorophenoxyacetic acid - DTT dithiothreitol - MES 2[N-morpholino] ethanesulphonic acid - NAA 1-naphthalene acetic acid - PVP polyvinylpyrrolidone     

Seasonality and vertical structure of light-attracted insect communities in a dipterocarp forest in Sarawak

Nocturnal flying insects were collected monthly for 13 months using ultra violet light-traps set at various vertical levels in a weakly-seasonal, tropical lowland dipterocarp forest in Sarawak, Malaysia. Abundance, faunal composition, size distribution and guild structure of these samples were analyzed with respect to temperal and vertical distributions. The nocturnal flying insect community in the canopy level was highly dominated by fig wasps (84%) in individual number, and by scarabaeid beetles (28%) in weight. A principal component analysis on monthly catches detected non-random, seasonal trends of insect abundance. The first two principal trends were an alternation of wetter (September to January) and less wet seasons (February to August) and an alternation between the least wet (January to March) and the other seasons. Many insect groups were less abundant in the least wet season than the other seasons, whilst inverse patterns were found in Scarabaeidae and Tenebrionidae. Significantly positive and negative correlations between monthly catch and rainfall were detected only in ovule-feeders and in phloem-feeders, respectively. Delayed, significant negative correlations between monthly catch and 1–3 month preceding rainfall were more frequently detected in phytophages, phloem-feeders, seed-feeders, wood-borers and scavengers. The peak in abundance along vertical levels were found at the canopy level (35 m) for phloem-, ovule-, seed-, root-, fungal-feeders and nectar collectors, at an upper subcanopy level (25 m) for scavengers and aquatic predators, and at a middle subcanopy level (17 m) for ants. Catches at the emergent level (45 m) did not exceed those at the canopy level.