Diversity of laccase genes from basidiomycetes in a forest soil     

Patricia Luis  Grit Walther  Francis Martin 《Soil biology & biochemistry》2004,36(7):1025-1036

Fungal oxidative exo-enzymes lacking substrate specificity play a central role in the cycling of soil organic matter. Due to their broad ecological impact and available knowledge of their gene structure, laccases appeared to be appropriate markers to monitor fungi with this kind of oxidative potential in soils. A degenerate PCR-primer pair Cu1F/Cu2R, specific for basidiomycetes, was designed to assess directly the diversity of laccase genes in soils. PCR amplification of mycelial cultures and fruit-bodies of a wide spectrum of basidiomycetes, covering all functional groups (saprophytes, symbionts, and pathogens), produced multiple DNA fragments around 200 bp. A neighbor-joining tree analysis of the PCR-amplified laccase sequences showed a clear species-specificity, but also revealed that most fungal taxa possess several laccase genes showing a large sequence divergence. This sequence diversity precluded the systematic attribution of amplified laccase of unknown origin to specific taxa. Amplification of laccase sequences from DNA, extracted from a brown (moder) forest soil, showed a specific distribution of laccase genes and of the corresponding fungal species in the various soil horizons (O_h, A_h, B_v). The most organic O_h-horizon displayed the highest gene diversity. Saprophytic fungi appeared to be less widespread through the soil horizons and displayed a higher diversity of laccase genes than the mycorrhizal ones.  相似文献   

Microparticle dispensers for the controlled release of insect pheromones     

Stipanovic AJ  Hennessy PJ  Webster FX  Takahashi Y 《Journal of agricultural and food chemistry》2004,52(8):2301-2308

The potential utility of micrometer-sized particles as controlled-release devices for the volatilization of insect pheromones for mating disruption applications is evaluated in this study for two pheromone/model compound systems (codlemone/1-dodecanol and disparlure/1,2-epoxyoctadecane). To expedite the measurement of release rates from these particle devices, two techniques based on thermogravimetric analysis (TGA) have been exploited: isothermal TGA (I-TGA) at elevated temperatures (40-80 degrees C) with N(2) convection and volatilization temperature (VT) by dynamic TGA. A correlation between these two methods has been established. Samples that exhibit a higher VT provide a lower release rate from a particle substrate. Using these techniques, it has been demonstrated that chemical interactions between adsorbed liquids and particle surfaces may play a small role in defining release characteristics under conditions of low surface area, whereas parameters associated with total surface area and micropore structure appear to be much more significant in retarding evaporation for uncoated particles containing an adsorbed liquid. Additional regulation of release rates was achieved by coating the particle systems with water-soluble or water-dispersible polymers. By careful selection of particle porosity and coating composition, it is envisioned that the evaporation rate of pheromones can be tailored to specific insect control applications.  相似文献   

Role of anaerobic bacteria in mastitis     

P G Francis 《The Veterinary record》1991,128(7):166-167

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The recognition and prevalence of Bacteroides nodosus serotype M in Australia and New Zealand     

DH CHETWIN  LC WHITEHEAD  SEJ THORLEY 《Australian veterinary journal》1991,68(4):154-155

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Fimbriae and enterotoxins associated with Escherichia coli serogroups isolated from pigs with colibacillosis   总被引：20，自引：0，他引：20  

R A Wilson  D H Francis 《American journal of veterinary research》1986,47(2):213-217

A comprehensive study of 223 Escherichia coli isolates from pigs with colibacillosis included determination of O serogroups, detection of heat-labile enterotoxin, heat-stable enterotoxin (STa and STb), and identification of K88, K99, 987-P, F-41, and type 1 fimbriae. The incidence of the various E coli types among isolates of pigs of different ages was also determined. Escherichia coli bearing K88 fimbriae accounted for 48% of all isolates studied, were most often of serogroup O157, O149, or O8, and usually produced labile toxin alone or in combination with STa or STb. These E coli were commonly isolated from pigs in each age group studied (0 to 5 days, 6 to 10 days, 11 to 24 days, and greater than 24 days). Escherichia coli bearing 987-P accounted for 30% of the isolates, were most often of serogroup O141 or O20, and usually produced STa. Escherichia coli bearing K99 accounted for 13% of the isolates, usually were of serogroup O101 or O8, and almost always produced STa. Escherichia coli bearing 987-P or K99 were most often isolated from pigs less than 6 days of age. Fimbriae F-41, when identified, were usually on E coli of serotype O101:K99. Although infrequently found, type 1 fimbriae were on E coli of most of the serogroups identified in this study.  相似文献   

Advantages of a new agar medium in the primary isolation of Mycobacterium bovis   总被引：2，自引：0，他引：2  

D V Cousins  B R Francis  B L Gow 《Veterinary microbiology》1989,20(1):89-95

Suspect tuberculous lesions from 116 cattle were examined histologically and cultured for Mycobacterium bovis using 5 different media. The media used were: B83, an agar medium incorporating bovine blood and sodium pyruvate; Middlebrook's agar; 2 variations of Stonebrink's medium; L?wenstein-Jensen medium. The B83 medium and a modification of Stonebrink's medium which had a lowered concentration of malachite green were most successful, detecting 95.2% of tuberculous animals when used together. The B83 medium detected isolates approximately 1 week earlier and had more colonies than the Stonebrink's modification. A combination of 2 slopes of B83 and 2 slopes of modified Stonebrink's medium is recommended for routine culture of samples.  相似文献   

Systemic candidiasis in a Suffolk ram     

TF JUBB  JD BAIRD  DH PERCY 《Australian veterinary journal》1988,65(10):333-335

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Observations on the incidence of clinical bovine mastitis in non-lactating cows in England and Wales   总被引：1，自引：0，他引：1  

P G Francis  J W Wilesmith  C D Wilson 《The Veterinary record》1986,118(20):549-552

Epidemiological features of clinical mastitis in dry cows from a three year prospective study are described. Two hundred and seventy-three herds in England and Wales participated in the first year (1980) and 209 and 159 of them continued in the study in the subsequent two years. Clinical mastitis was recorded in 1.5 per cent of cows during the dry period in each of the three years. These cases represented between 3.6 and 4.2 per cent of samples from all clinical cases examined. The incidence of clinical mastitis in dry cows increased during the winter housing period (October to March), a peak occurring at the end of this period. A secondary peak in incidence was recorded in August. Streptococcus uberis was the predominant pathogen. Variations in the monthly incidences of cases associated with the major mastitis pathogens were observed. A greater proportion of cases which occurred during the dry period exhibited systemic signs than of cases which occurred during lactation, with the exception of cases associated with Escherichia coli. The risk of clinical mastitis was apparently higher during the last 30 days of the dry period than during the earlier stages of the dry period.  相似文献   

ZOONOSES AND PUBLIC HEALTH*     

J. Francis 《Australian veterinary journal》1967,43(8):311-328

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OBSERVATIONS ON BOVINE EPHEMERAL FEVER AND ISOLATION OF VIRUS     

P. B. Spradbrow  B.V.Sc.  Ph.D. J. Francis  D.Sc.  M.Sc.  F.R.C.V.S. 《Australian veterinary journal》1969,45(11):525-527

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