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1.
M. T. Dumas 《Forest Pathology》1992,22(1):11-18
Pseudomonas fluorescens, Pseudomonas spp., Bacillus spp., Enterobacter spp., Serratia spp. and Agrobacterium radiobacter were isolated from root-free soils of the Boreal Mixedwood Forest of Ontario a, nd found to be capable of inhibiting the linear growth of Armillaria ostoyae in vitro. Isolates of P. fluorescens, Bacillus spp. and A. radiobacter were the most effective inhibitors of mycelial growth. To test the ability of the bacteria to suppress rhizomorph formation, A. gallica, which produces rhizomorphs in culture more consistently than does A. ostoyae, was used; only a small fraction of P. fluorescens and Bacillus spp. isolates were capable of preventing in vitro rhizomorph formation by A. gallica. 相似文献
2.
From the heartwood-free stemwood of Pinus densiflora, 7 compounds inhibitory to the linear growth of Fomes annosus were isolated. These were identified as pinosylvin, pinosylvin monomethyl ether, (3-sitosterol, a cembrol-like diterpene alcohol, and three isomeric diterpene acids belonging to the abietane group, one of which is probably palustric acid. Other antifungal fractions contained complex mixtures and were not characterized. 相似文献
3.
Mathematical models in fish nutrition have proven indispensable in estimating growth and feed requirements. Nowadays, reducing the environmental footprint and improving product quality of fish culture operations are of increasing interest. This review starts by examining simple models applied to describe/predict fish growth profiles and progresses towards more comprehensive concepts based on bioenergetics and nutrient metabolism. Simple growth models often lack biological interpretation and overlook fundamental properties of fish (e.g. ectothermy, indeterminate growth). In addition, these models disregard possible variations in growth trajectory across life stages. Bioenergetic models have served to predict not only fish growth but also feed requirements and waste outputs from fish culture operations. However, bioenergetics is a concept based on energy-yielding equivalence of chemicals and has significant limitations. Nutrient-based models have been introduced into the fish nutrition literature over the last two decades and stand as a more biologically sound alternative to bioenergetic models. More mechanistic models are required to expand current understanding about growth targets and nutrient utilization for biomass gain. Finally, existing models need to be adapted further to address effectively concerns regarding sustainability, product quality and body traits. 相似文献
4.
J. Bordes G. Charmet R. Dumas de Vaulx A. Lapierre M. Pollacsek M. Beckert A. Gallais 《Euphytica》2007,154(1-2):41-51
Progress made in the in situ gynogenesis technique since 1990 now allows production of a high number of maize (Zea mays L.) doubled-haploid (DH) lines. The aim of the study was to compare DH lines versus selfing lines for testcross performance.
DH and single-seed descent (SSD) lines were produced from random S1 progenies of a broad-base population. For grain yield, kernel moisture, plant height, ear height and leaf length, the three
population means were similar. Except for kernel moisture, the genetic variance of DH lines was nearly twice as high as the
genetic variance of S1 families, as expected. On the other hand, genetic variance among SSD lines was only 1.5 times higher than the genetic variance
of S1 families. This lower variance could be due to a selection bias in the method of production of SSD lines. However, for all
traits, heritability of SSD or DH lines was higher than heritability of S1 families. Epistasis effects in DH progenies were not significant. The consequence was a high correlation between S1 testcross progenies and DH or SSD testcross progenies, meaning that the S1 testcross value can be used to select the best families from which DH lines will be extracted. As a whole, the observed variation
in DH lines appeared to be more in accordance with the observed variation among S1 families than with the observed variation among SSD lines. 相似文献
5.
Riley MB Dumas JA Gbur EE Massey JH Mattice JD Mersie W Mueller TC Potter T Senseman SA Watson E 《Journal of agricultural and food chemistry》2005,53(13):5079-5083
An interlaboratory study was conducted to compare pesticide recovery from Empore C(18) and Speedisks C(18)XF solid phase extraction disks after shipping. Four pesticides were used for the comparison of the two disk extraction materials: atrazine, diazinon, metolachlor, and tebuconazole. These pesticides were chosen to provide a range of physiochemical properties. Water samples were extracted onto the disk types and shipped to a cooperating laboratory for elution and analysis. The mean recoveries from Empore disks were atrazine, 95%; diazinon, 91%; metolachlor, 92%; and tebuconazole, 83%. The recoveries from Speedisks C(18)XF were atrazine, 89%; diazinon, 87%; metolachlor, 86%; and tebuconazole, 79%. Means for each of the pesticides using the different disk types were not statistically different (alpha = 0.05), but results were more variable when using Speedisks C(18)XF as compared to Empore disks. Reasons for the increased variability are discussed, but overall results indicate that Speedisks C(18)XF could be used as an alternative to Empore disks. Speedisks C(18)XF are enclosed in a plastic housing, so they can be used more easily in remote sampling sites without the possibility of glassware breakage, no prefiltration of samples is needed, and there are realignment problems that can be associated with the Empore disks. 相似文献
6.
An in vitro system for adhesion and fusion of maize gametes 总被引:1,自引:0,他引:1
The development of in vitro fertilization systems in flowering plants is important for understanding and controlling the mechanisms of fertilization. Here a method is described in which isolated maize gametes fuse. In a medium containing 5 mM calcium chloride, sperm and egg cells adhere for several minutes and then fuse within 10 seconds. The method is specific to male-female gamete pairs and results in 80 percent fusion, whereas fusions with other combinations of gametic and mesophyllic cells are less frequent. Eggs fertilized in vitro do not fuse with additional male gametes, which suggests that a block to polyspermy exists. 相似文献
7.
Spencer JR Stern SA Cheng AF Weaver HA Reuter DC Retherford K Lunsford A Moore JM Abramov O Lopes RM Perry JE Kamp L Showalter M Jessup KL Marchis F Schenk PM Dumas C 《Science (New York, N.Y.)》2007,318(5848):240-243
Jupiter's moon Io is known to host active volcanoes. In February and March 2007, the New Horizons spacecraft obtained a global snapshot of Io's volcanism. A 350-kilometer-high volcanic plume was seen to emanate from the Tvashtar volcano (62 degrees N, 122 degrees W), and its motion was observed. The plume's morphology and dynamics support nonballistic models of large Io plumes and also suggest that most visible plume particles condensed within the plume rather than being ejected from the source. In images taken in Jupiter eclipse, nonthermal visible-wavelength emission was seen from individual volcanoes near Io's sub-Jupiter and anti-Jupiter points. Near-infrared emission from the brightest volcanoes indicates minimum magma temperatures in the 1150- to 1335-kelvin range, consistent with basaltic composition. 相似文献
8.
Signatures of adaptation to obligate biotrophy in the Hyaloperonospora arabidopsidis genome 总被引:2,自引:0,他引:2
Baxter L Tripathy S Ishaque N Boot N Cabral A Kemen E Thines M Ah-Fong A Anderson R Badejoko W Bittner-Eddy P Boore JL Chibucos MC Coates M Dehal P Delehaunty K Dong S Downton P Dumas B Fabro G Fronick C Fuerstenberg SI Fulton L Gaulin E Govers F Hughes L Humphray S Jiang RH Judelson H Kamoun S Kyung K Meijer H Minx P Morris P Nelson J Phuntumart V Qutob D Rehmany A Rougon-Cardoso A Ryden P Torto-Alalibo T Studholme D Wang Y Win J Wood J Clifton SW Rogers J Van den Ackerveken G Jones JD 《Science (New York, N.Y.)》2010,330(6010):1549-1551
Many oomycete and fungal plant pathogens are obligate biotrophs, which extract nutrients only from living plant tissue and cannot grow apart from their hosts. Although these pathogens cause substantial crop losses, little is known about the molecular basis or evolution of obligate biotrophy. Here, we report the genome sequence of the oomycete Hyaloperonospora arabidopsidis (Hpa), an obligate biotroph and natural pathogen of Arabidopsis thaliana. In comparison with genomes of related, hemibiotrophic Phytophthora species, the Hpa genome exhibits dramatic reductions in genes encoding (i) RXLR effectors and other secreted pathogenicity proteins, (ii) enzymes for assimilation of inorganic nitrogen and sulfur, and (iii) proteins associated with zoospore formation and motility. These attributes comprise a genomic signature of evolution toward obligate biotrophy. 相似文献
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