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71.
Seasonal Incidence of Bacterial Temperature Types in Louisiana Soil and Water 总被引:6,自引:3,他引:3
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John M. Larkin 《Applied microbiology》1970,20(2):286-288
Psychrophilic bacteria were not detected in soil, mud, and water in the summer. In winter, they were present in water and mud and constituted a significant portion of the bacterial flora in lake water. 相似文献
72.
Comparison of Methods for the Recovery of Virus Inoculated into Ground Beef 总被引:5,自引:5,他引:0
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John T. Tierney Robert Sullivan Edward P. Larkin James T. Peeler 《Applied microbiology》1973,26(4):497-501
Various methods for the recovery of virus inoculated into ground beef were investigated in an attempt to develop a sensitive system that could be used to detect viral contaminants in market foods. A 100-g sample, inoculated with poliovirus 1, was suspended in 150 to 900 ml of Eagle minimum essential medium, pH 8.5, and mixed in either plastic bags or plastic cups on a mechanical shaker. The particulate materials were removed by means of cheese cloth, glass wool, woven fiber glass, or low-speed centrifugation. Large volumes of fluid were concentrated by ultrafiltration. Microbiological contamination was controlled by high antibiotic concentrations or by filtration. Quantitative plaque-forming-unit recovery of the virus was determined by utilizing an agar overlay technique on Vero cell cultures. The data indicated that from 20 to 50% of the seeded virus could be recovered from a 100-g sample of ground beef. The glass wool and woven fiber glass methods were the most effective, with recovery of approximately 50% of the inoculated virus. 相似文献
73.
74.
籼稻和粳稻中蜡质基因座位上微卫星标记的多态性及其与直链淀粉含量的关系 总被引:28,自引:0,他引:28
稻米直链淀粉是在由蜡质基因Wx编码的颗粒结合淀粉合成酶(GBSS)的催化下合成的。最近,在Wx基因的区段内发现了一段多态性微卫星序列(CT)n。对74个非糯籼稻和粳稻材料的(CT)n多态性进行了分析,并探讨了其与直链淀粉含量之间的关系。在74个品种(系)中共发现7种(CT)n片段(Wx等位基因),即(CT)8,(CF)10,(CT)11,(CT)16,(CT)17,(CT)18,(Ch)19。在籼粳亚种间,不同(CT)n的分布存在差异较大:在籼稻中,以(CT)11和(CT)18为主,占92.6%,另有(CT)10和(CT)8各2份,(CT)17型1份;在粳稻中,以(CT)16、(CT)17为主,共占20份材料中的90.0%。在上述74个品种(系)中,以(CT)n表示的Wx基因型对稻米直链淀粉含量的决定系数R2达0.912,也即Wx基因型差异可解释这些材料直链淀粉含量变异的91.2%。还发现6份籼稻材料Wx座位上为杂合的(CT)18/(CT)11,其中2份为推广早籼优质品种浙9248和舟优903,并对其在遗传和育种研究中的意义作了探讨。 相似文献
75.
Halomethane:Bisulfide/Halide Ion Methyltransferase, an Unusual Corrinoid Enzyme of Environmental Significance Isolated from an Aerobic Methylotroph Using Chloromethane as the Sole Carbon Source 总被引:4,自引:4,他引:0
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Catherine Coulter John T. G. Hamilton W. Colin McRoberts Leonid Kulakov Michael J. Larkin David B. Harper 《Applied microbiology》1999,65(10):4301-4312
A novel dehalogenating/transhalogenating enzyme, halomethane:bisulfide/halide ion methyltransferase, has been isolated from the facultatively methylotrophic bacterium strain CC495, which uses chloromethane (CH3Cl) as the sole carbon source. Purification of the enzyme to homogeneity was achieved in high yield by anion-exchange chromatography and gel filtration. The methyltransferase was composed of a 67-kDa protein with a corrinoid-bound cobalt atom. The purified enzyme was inactive but was activated by preincubation with 5 mM dithiothreitol and 0.5 mM CH3Cl; then it catalyzed methyl transfer from CH3Cl, CH3Br, or CH3I to the following acceptor ions (in order of decreasing efficacy): I−, HS−, Cl−, Br−, NO2−, CN−, and SCN−. Spectral analysis indicated that cobalt in the native enzyme existed as cob(II)alamin, which upon activation was reduced to the cob(I)alamin state and then was oxidized to methyl cob(III)alamin. During catalysis, the enzyme shuttles between the methyl cob(III)alamin and cob(I)alamin states, being alternately demethylated by the acceptor ion and remethylated by halomethane. Mechanistically the methyltransferase shows features in common with cobalamin-dependent methionine synthase from Escherichia coli. However, the failure of specific inhibitors of methionine synthase such as propyl iodide, N2O, and Hg2+ to affect the methyltransferase suggests significant differences. During CH3Cl degradation by strain CC495, the physiological acceptor ion for the enzyme is probably HS−, a hypothesis supported by the detection in cell extracts of methanethiol oxidase and formaldehyde dehydrogenase activities which provide a metabolic route to formate. 16S rRNA sequence analysis indicated that strain CC495 clusters with Rhizobium spp. in the alpha subdivision of the Proteobacteria and is closely related to strain IMB-1, a recently isolated CH3Br-degrading bacterium (T. L. Connell Hancock, A. M. Costello, M. E. Lidstrom, and R. S. Oremland, Appl. Environ. Microbiol. 64:2899–2905, 1998). The presence of this methyltransferase in bacterial populations in soil and sediments, if widespread, has important environmental implications. 相似文献
76.
Trophic support functions for fishes are a key goal of salt marsh restoration. Food availability in restored sites may be enhanced by creation of shallow pools, which are important sources of prey items in tidal wetlands. Young restored salt marshes are typically sparsely vegetated and are subject to rapidly changing geomorphology. Scouring and sedimentation create and fill shallow depressions, producing a shifting mosaic of tidal pools. In a large (8-ha) southern California experimental restoration site, we created shallow pools and assessed their development of foods for fishes. Created pools quickly developed abundant invertebrate prey, with densities exceeding those found in older, naturally formed pools (P < 0.0001). Opportunistic mobile and disturbance-associated taxa (calanoid copepods, nematodes, Polydora complex, and Trichocorixa reticulata) accounted for higher invertebrate densities in created pools. We repeated experiments in spring, summer, and fall and found seasonal variability in trophic development. We also applied bottom-up (nitrogen addition) and top-down (fish exclusion) treatments to pools. Some measures of algal biomass were increased by nitrogen fertilization (P = 0.001–0.06), but there were no upward-cascading effects on invertebrate composition or abundance. Fish abundance in the site varied seasonally, but there were no compelling effects of fish exclusion treatments on algal or invertebrate abundance. Incorporating shallow depressions into salt marsh restoration projects is a potential tool to jumpstart fish-support functions. 相似文献
77.
Ocen M. Olanya Andrew B. Plant Robert P. Larkin Charles W. Honeycutt 《Journal of Phytopathology》2009,157(7-8):427-437
Infection of hairy nightshade ( Solanum sarrachoides Sendt.) by Phytophthora infestans has been reported. However, the epidemiological significance of hairy nightshade to potato late blight is not well known. Disease development and infection rates of P. infestans were quantified on hairy nightshade relative to tomato (cv. Brandywine) and potato (cv. Shepody) hosts to evaluate infection potential at 14, 18, 22 and 26°C and 72, 82, 87, and 92% relative humidity (RH). The susceptibility of hairy nightshade to inoculum levels, weed ontogeny, and sporangia production potential were also investigated. Late blight development varied among hairy nightshade, tomato and potato hosts. Pathogen infection rates ranged from 0.0325 to 0.4674 gompits/day (unit for quantifying infection rates), and were significantly (P < 0.05) greater on potato and tomato than on hairy nightshade. Late blight severity was variably affected by RH. Disease levels on hairy nightshade varied with inoculum load; and ranged from 9 to 26% and 26 to 37% at low (5 × 103 ) and high (25 × 103 ) sporangia concentrations, respectively. Late blight was recorded irrespective of hairy nightshade ontogeny, and was significantly greater on 8–10 than 4–6-week-old plants. These results indicate that pathogen, environmental and host factors affect late blight development on hairy nightshade. 相似文献
78.
Michael J. Smietana Fatima N. Syed-Picard Jinjin Ma Tatiana Kostrominova Ellen M. Arruda Lisa M. Larkin 《In vitro cellular & developmental biology. Animal》2009,45(9):512-522
Our laboratory has previously developed scaffoldless engineered bone constructs (EBC). Bone marrow stromal cells (BMSC) were
harvested from rat femur and cultured in medium that induced osteogenic differentiation. After reaching confluence, the monolayer
of cells contracted around two constraint points forming a cylinder. EBCs were placed in small diameter (0.5905 × 0.0625 in.)
or large diameter (0.5905 × 0.125 in.) silicone tubing and implanted intramuscularly in the hind limb of a rat. Bone mineral
content (BMC) of the EBC was analyzed before implantation and at 1 and 2 mo following implantation and compared to that of
native femur bone at different stages of development. Negligible BMC was observed in E-20 femur or EBCs prior to implantation.
One-month implantation in both small and large tubing increased BMC in the EBC. BMC of EBC from large tubing was greater than
in 14 d rat neonatal femurs, but was 2% and 3% of BMC content in adult bone after 1 and 2 mo of implantation, respectively.
Alizarine Red and osteopontin staining of the EBCs before and after implantation confirmed increased bone mineralization in
the implanted EBCs. Implanted EBCs also had extensive vascularization. Our data suggest that BMSC can be successfully used
for the generation of scaffoldless EBC, and this model can be potentially used for the generation of autologous bone transplants
in humans. 相似文献
79.
Genetic enhancement of oil content in potato tuber (Solanum tuberosum L.) through an integrated metabolic engineering strategy
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80.
Edward Bernard Robert P. Larkin Stellos Tavantzis M. Susan Erich Andrei Alyokhin Serena D. Gross 《Plant and Soil》2014,374(1-2):611-627