The aim of the study was to evaluate the sensitivity of two m-PCR methods for the quantitative determination of E. coli O157:H7 in foodstuffs. Genomic serotyping was carried out on bacterial cultures, and the necessary time was optimized to increase the resolution of the method. Subsequently, artificial contamination trials using meat were conducted to assess method accuracy in foodstuffs and pursue the genetic typing of pathogens. Measurement thresholds were shown to range between 105 and 106 CFU/mL, but were reduced by four logarithmic cycles in 80% of samples. Relative to the meat contamination trials, serotypes were identified after 24 hours, corresponding to 10 CFU/mL inoculum, with higher rates seen when m-TSB was used for enrichment. Inoculated samples were found to contain three virulence factors (hlyA, eaeA, and stx1).
In Italy, new agroforestry cultural models could play an important role in the diffusion of plantation forestry timber species. We studied the stem growth rates and leaf water potentials () of common walnut (Juglans regia L.), and gravimetric soil moisture (DW) depletion during the third and fourth growing seasons in an agroforestry trial in central Italy. Since the establishment of experimental plots in 1992, walnut was intercropped with alfalfa (Medicago sativa L.), with or without polyethylene (PE) mulching along tree rows. By the end of the study period, the unmulched-intercropped walnut was almost 68% smaller in stem diameter and height than the sole-unmulched control, demonstrating walnuts sensitivity to alfalfa competition. The competitive effect of alfalfa on walnut stem growth was effectively controlled/reduced by PE mulching. Stem growth rates of mulched-intercropped walnut were always lower than the control, but much higher (ca. 235% in stem diameter and height) than those of unmulched-intercropped walnut. The higher field performance of mulched-intercropped walnut compared to the un- mulched-intercropped treatment was associated with higher soil moisture and predawn and midday values during the summers driest periods. The presence of PE mulching was also associated with lower levels of soil moisture during the early and late growing season, but this did not negatively affect walnut and growth rates. These results suggest that in the climatic conditions of central Italy, competition for soil moisture between young common walnut trees and alfalfa can be substantially lowered, but not completely eliminated, by PE mulching.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
Adaptive and wood quality trait data were collected and analyzed on commercially available Juglans regia and J. regia×J. nigra provenances and progenies planted across Europe in a multi-site network. A total of 19 seed sources, replicated 35 times per site, were planted at 13 sites from 5 European countries, encompassing the potential distribution area of timber production plantation sites. The following traits were evaluated: survival, height, diameter at breast height, stem form, apical dominance, vegetative budbreak, along with biotic and abiotic damage. Mean values were significantly different both among provenances/progenies and sites. Most common damage was late spring and early autumn frost. Bud break ranking was significantly correlated with provenance and progeny origin. Although J. regia is fast growing, southern European early budbreak plant material should not be planted under most middle European conditions where late spring frost can be expected, as it has a significant negative impact on architectural (and thus wood quality) traits. Hybrid J. regia×J. nigra progeny performed better than J. regia provenances/progenies for most traits measured. Differences were significantly in favor of hybrids at sites with medium to low fertility, although some locally selected seed sources tended to perform as well as hybrids on high fertility sites. 相似文献
The effect of GH treatment on hepatic cytochrome P450 content, aryl hydrocarbon hydroxylase (AHH), aminopyrine-N-demethylase (AND), testosterone hydroxylase, testosterone 5- and 5-reductase, UDP-glucuronyl transferase (UDPGT) and glutathione S-transferase (GST) activities in immature rainbow trout were investigated. Hepatic cytochrome P450 content, AHH and GST activities were measured in both GH implanted and GH injected animals whereas other activities were assayed in GH implanted trout only.GH implants significantly decreased cytochrome P450 content at 15 days compared to the control but no significant effect was observed at 15 or 30 d when GH was injected biweekly. In both cases, AHH activity was significantly decreased by GH treatment compared to the control whereas GST remained unchanged. Compared to the control, GH implanted fish exhibited a pronounced inhibition of AND, a decreased 6 and 16-testosterone hydroxylation, an inhibition of UDPGT with testosterone as substrate and an enhanced 17-testosterone oxidation. 相似文献
Transplantation of ovarian tissue has high potential for female gamete conservation. However, optimal timing of oocyte recovery for in vitro maturation and fertilization is still critical. Therefore the aim of the present study was to use high-resolution transcutaneous ultrasonography to monitor follicular development within xenografted ovarian tissue. Ovarian cortex fragments (n=44) from domestic cats were transplanted into athymic nude rats (n=12). Graft development in the animals was assessed weekly by high frequency ultrasound (10-22 MHz) under two different FSH regimes. Blood collection for serum estradiol determination and vaginal smears were performed simultaneously. The xenografts were removed at different time points according to the ultrasound findings. The survival rate of the transplants 4 weeks after surgery was 54.5% and antral follicular growth was observed within 10 grafts from 5 different hosts (8.6 +/- 6.43 follicles per graft). Early follicle antrums could be detected from 0.4 mm onwards. The growth rate of the antral cavity was calculated from weekly measurements (0.56 +/- 0.44 mm per week). Although vaginal cells and estradiol levels followed a cyclic pattern, no correlation was found between follicular diameter, estradiol and keratinized vaginal cells. We recovered 5, 1 and 4 cumulus oocyte complexes from three different individuals during weeks 19, 21, and 23 respectively. Extrusion of a polar body (1 oocyte) and germinal vesicle break down (7 oocytes) indicated progression of maturation after in vitro culture. We conclude that ultrasonography und provided a reliable method to examine xenograft survival and follicular development within the grafts. Furthermore, this technique is suitable for assessment of the efficiency of hormonal treatment and narrowing of the optimal time frame for oocyte retrieval. To our knowledge, this is the first report of the in vivo development of early antral follicles in mammalian species. 相似文献
Summary Powdery mildew development was assessed on squash (Cucurbita pepo) plants of a susceptible cultivar, a resistant accession, their F1, and their F2 in an early summer planting in the field, covered or not covered with a shading net. Three reaction types were observed: susceptible, powdery mildew on stems and on both, the upper and lower leaf surfaces, as in the susceptible parent; resistant, no powdery mildew on leaves or stems, as in the resistant parent; and partially resistant, powdery mildew on upper leaf surfaces only, as in the F1. Disease presence on the stem was associated with susceptibility. Shading hastened the appearance of powdery mildew and increased the severity of infection on partially resistant and susceptible plants, facilitating identification of resistant individuals in the F2 population.Contribution No. 1613-E from the Agricultural Research Organization, Bet Dagan, Israel 相似文献
Longitudinal striping of the fruit exterioris a common trait in Cucurbita pepo(pumpkin, squash, gourd). Striping occursas ten pairs of alternating dark and lightstripes that are regularly situated inaccordance with the ten sub-epidermalcarpellary vein tracts. Usually, the darkstripes occur in the central areas betweenthe vein tracts, with the light stripesoccupying the remainder of the fruitsurface. A new phenotype is described inwhich dark spots or streaks occur in thecentral areas between the vein tracts;these are usually accompanied by darkstreaks or stripes that occur adjacent toand over part or all of the length of someor all of the ten carpellary vein tracts. The inheritance of this irregular stripingpattern was studied by crossing anaccession that bred true for this phenotypewith a near-isogenic line havinglight-colored fruits. The resultsindicated that irregular striping isdominant to light coloration and isconferred by a single gene. Testcrossesfor allelism with regular striping wereprepared by crossing the irregularlystriped accession with near-isogenic lineshaving broad stripes, l-1BSt/l-1BSt, and narrowstripes, l-1St/l-1St. The testcross results revealed thatirregular striping is conferred by anallele at the l-1 locus, designatedl-1iSt. The l-1iStallele is dominant to light-colored (l-1), recessive to dark-colored (L-1), and can be co-dominant or recessiveto broad-striped (l-1BSt) andnarrow-striped (l-1St),depending on whether or not it is fullyexpressed. Dominance relationships at thel-1 locus can, therefore, berepresented as L-1 > (l-1BSt > l-1St) l-1iSt > l-1. 相似文献
About 50% of cancer patients receive radiation therapy. Here we investigated the hypothesis that tumor response to radiation is determined not only by tumor cell phenotype but also by microvascular sensitivity. MCA/129 fibrosarcomas and B16F1 melanomas grown in apoptosis-resistant acid sphingomyelinase (asmase)-deficient or Bax-deficient mice displayed markedly reduced baseline microvascular endothelial apoptosis and grew 200 to 400% faster than tumors on wild-type microvasculature. Thus, endothelial apoptosis is a homeostatic factor regulating angiogenesis-dependent tumor growth. Moreover, these tumors exhibited reduced endothelial apoptosis upon irradiation and, unlike tumors in wild-type mice, they were resistant to single-dose radiation up to 20 grays (Gy). These studies indicate that microvascular damage regulates tumor cell response to radiation at the clinically relevant dose range. 相似文献
Seed samples of 174 accessions of pumpkins, squash, and gourds of Cucurbita pepo were measured for length, width, and thickness. Mean seed length ranged from 8.8 to 23.3 mm, mean seed width from 5.0 to 12.5 mm and mean seed thickness from 1.2 to 3.8 mm. The seeds of the edible-fruited cultivar-groups of C. pepo subsp. pepo (Pumpkin, Vegetable Marrow, Cocozelle, Zucchini) were longer, wider, and thicker than those of their counterparts of C. pepo subsp. texana (Acorn, Crookneck, Scallop, Straightneck). The small-fruited, inedible gourds had the smallest seeds. Of the edible-fruited C. pepo subsp. pepo, the Pumpkin Group (round fruits) possessed the longest and flattest seeds whilst the Zucchini Group (long, uniformly cylindrical fruits) possessed the shortest and thickest seeds. The samples tested also differed greatly in mean values for relative dimensions. Length-to-width ratio ranged from 1.5 to 2.5, length-to-thickness ratio from 3.7 to 8.2, and width-to-thickness ratio from 2.0 to 4.9. The Pumpkin Group, followed by the Cocozelle Group (long, bulbous cylindrical fruits) and the Vegetable Marrow Group (short, tapered cylindrical fruits), had seeds of the highest length-to-width ratio. The seeds of the four edible-fruited groups of C. pepo subsp. pepo differed significantly from one another in their length-to-thickness and width-to-thickness ratios. The seeds of the Pumpkin Group and the wild Mexican gourd (C. pepo subsp. fraterna) differed greatly in their dimensions but were most similar to one another in their relative dimensions. In C. pepo, seed size is positively associated with fruit size and seed shape is inversely associated with fruit shape. 相似文献
Summary Three groups of Boran cattle were maintained under different trypanocidal drug regimes for 29 months in an area of “medium”
tsetse challenge. The development of immunity to trypanosomiasis in the cattle was assessed on the basis of changes in trypanocidal
drug requirement, development of parasitaemia, ability to maintain normal blood values, growth and response to challenge after
the withdrawal of the drugs. Observations were also made on serum antibody content by immunofluorescence and on serum immunoglobulin
levels.
Cattle treated with Berenil on the development of clinical disease developed a partial immunity to trypanosomiasis after two
years. Cattle treated as a group with Berenil on the development of patent parasitaemia in any one animal of the group did
not develop immunity. Cattle treated as a group with Samorin using the same criterion for treatment developed a degree of
immunity to the disease.
It was concluded that group treatment with Samorin was the most suitable of the three regimes examined for the maintenance
of beef cattle in a tsetse infested area.
Resumen Se mantuvieron tres grupos de ganado Boran durante 29 meses bajo differentes regímenes terapéuticos en un área donde la concentración
de moscas tsetse era mediana. Se llevó a cabo la evaluación del desarrollo de la inmunidad contra la tripanosomiasis teniendo
como base los diferentes cambios en el requerimiento de drogas, desarrollo de parasitemia, abilidad para mantener los valores
sanguíneos normales, crecimiento y respuestas a la descarga de parásitos después del retiro de la terápia. Se hicieron también
observaciones del nivel de anticuerpos séricos por inmunofluorescencia y se determinó el nivel de inmunoglobulinas. Los animales
tratados con Berenil cuando mostraban signos clínicos de la enfermedad, desarrollaron una inmunidad parcial a la tripanosomiasis
después de dos a?os. Los animales tratados en grupo con Berenil cuando se detectó parasitemia en cualquier animal del grupo
no desarrollaron inmunidad. El ganado tratado con Samorin en base de grupo siguiendo el mismo criterio para el tratamiento,
desarrolló cierto grado de resistencia a la enfermedad. Se concluye que el tratamiento de grupo utilizando Samorin fue el
mejor de los tres regímenes estudiados para el mantenimiento de ganado de carne en un área infestada de moscas tstse.
Résumé Trois groupes de bovins Boran ont été maintenus vingt neuf mois, sous différents traitements trypanocides, dans une zone “moyennement”
infestée de tsé-tsé. Le développement de l'immunité à la trypanosomiase a été évalué à partir des changements dans les besoins
en trypanocides, du développement de la parasitémie, de l'aptitude à maintenir les valuers normales du sang, de la croissance
et de la réaction à l'infection après la suppression des médicaments. Des observations ont aussi été faites sur la présence
d'anticorps sériques par immunofluorescence et sur les teneurs en immunoglobines sériques.
Le bétail traité au Berenil à l'apparition de signes cliniques a été partiellement immunisé au bout de deux ans. Dans le groupe
du bétail traité au Berenil à l'apparition d'une parasitémie évidente, aucun animal n'a présenté d'immunité. Le groupe de
bovins traité au Samorin, selon les nêmes critères a été bien immunisé.