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211.
212.
A. Thaler‐Neto R. Fries G. Thaller 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2000,117(3):153-167
The risk ratio (λR) is defined as ‘the recurrence risk for a relative of an affected individual divided by the prevalence in the general population’ and is considered as the most important parameter when designing mapping experiments for diseases in humans. In this paper, the risk ratio was introduced as a parameter to genetically characterize complex binary traits such as mastitis in cattle. Simulations were applied to evaluate the properties of λR under different genetic models (monogenic, digenic, polygenic and mixed models) and in dependency of their parameters for a design consisting of unbalanced halfsib families typically found in dairy cattle. Population prevalences of the simulated data ranged from 5 to 40% and λR was estimated on a phenotypic level. In the discrete loci models complexity of the traits was introduced through different levels of penetrance and the proportions of phenocopies within each genetic background. The risk ratio and the power to reject the null hypothesis of independent halfsibs (λR=1) were influenced by the prevalence in all genetic models chosen. Absolute values for λR were higher for lower prevalences, for example, λR=2.77 and 1.62 for a pure monogenic recessive model with 5 and 20% prevalence, respectively, whereas the power decreases in the case of lower prevalences. For all the prevalences investigated, higher risk ratios were found for discrete loci models compared with the polygenic models, with higher values for the monogenic relative to the digenic models in general. For the mixed models, λR was intermediate between the polygenic and discrete loci models. Genes with dominant relative to recessive inheritance for susceptibility caused higher risk ratios in monogenic and mixed models, for example, λR=5.16 and 2.77 for a pure monogenic model with 5% prevalence. In the discrete loci models, λR decreased with lower penetrance and a higher proportion of phenocopies. Risk ratios increased with the heritability in the polygenic and in addition with the effect of the major gene in mixed models. Consistent patterns of risk ratios were observed under the analysed genetic models and parameters, which indicate that the risk ratio is a parameter well suited to genetically characterize binary traits in unbalanced halfsib families. 相似文献
213.
Resistance to the southern root-knot nematode Meloidogyne incognita Chitwood would be an important attribute of lettuce Lactuca sativa L. cultivars adapted to both protected and field cultivation in tropical regions. `Grand Rapids' and a few other cultivars
are reported to be resistant to this nematode. In this paper, we studied the inheritance of the resistant reaction of `Grand
Rapids' (P2) in a cross with a standard nematode-susceptible cultivar Regma-71 (P1). F1(Regina-71 × Grand Rapids) and F2 seed were obtained, and inoculated along with the parental cultivars with different races of M. incognita to evaluate nematode resistance. Broad sense heritability estimates for the number of galls and of egg masses per root system,
gall size and gall index were generally in the order of 0.5 or higher. Class distributions of these variables over generations
P1, P2, F1 and F2 were in agreement with simulated theoretical distributions based on monogenic inheritance models. F3 families were obtained from randomly sampled F2 plants and tested for reaction to the nematode. The frequency ratio of homozygous resistant, segregating and homozygous susceptible
F3 families did not differ from the 1:2:1 ratio expected from monogenic inheritance. M. incognita resistance appears to be under control of a single gene locus. The Grand Rapids allele (for which the symbol Me is proposed) is responsible for the resistant reaction, and shows high (though incomplete) penetrance, variable expressivity
and predominantly additive gene action.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
214.
Matthieu Lebastard Stephanie BeurletLafarge Eymeric Gomes Kevin Le Boedec 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2022,36(4):1444
BackgroundHistorically, positive bacterial cultures from the lower respiratory tract (LRT) have been considered clinically relevant when quantitative bacterial cultures of bronchoalveolar lavage fluid (BALF) were >1700 colony forming units (cfu)/mL. However, this threshold might not accurately predict a requirement for antibiotics.ObjectivesTo study whether quantitative BALF bacterial culture results were predictive of antibiotic requirement in dogs with LRT signs.AnimalsThirty‐three client‐owned dogs.MethodsCross‐sectional study. Dogs with positive quantitative bacterial culture of BALF were included. Dogs were divided into 2 groups, depending on whether they had a LRT infection requiring antibiotics (LRTI‐RA) or LRT disease not requiring antibiotics (LRTD‐NRA), based on thoracic imaging features, presence of intracellular bacteria on BALF cytology, and response to treatment. Predictive effect of cfu/mL and BALF total nucleated cell count (TNCC) on antibiotic requirement, adjusting for ongoing or prior antibiotic therapy and age, were studied using logistic regression.ResultsTwenty‐two and 11 dogs were included in the LRTI‐RA and LRTD‐NRA groups, respectively. The cfu/mL was not significantly predictive of antibiotic requirement, independent of ongoing or prior antibiotic treatment and age (LRTI‐RA: median, 10 000 cfu/mL; range, 10‐3 × 108; LRTD‐NRA: median, 10 000 cfu/mL; range, 250‐1.3 × 109; P = .27). The TNCC was not significantly predictive of antibiotic requirement when only dogs with bronchial disease were considered (LRTI‐RA: median, 470 cells/μL; range, 240‐2260; LRTD‐NRA: median, 455 cells/μL; range, 80‐4990; P = .57).Conclusion and Clinical ImportanceThe cfu/mL is an inappropriate measure for determining whether antibiotics are of benefit in dogs with LRT signs. 相似文献
215.
Isabela Ramsdorf Gomes Patinni Cristiane Alves de Andrade Cid Naudi Silva Campos Larissa Pereira Ribeiro Teodoro Sinomar Moreira Andrade Cassiano Garcia Roque Carlos Antônio da Silva Junior Paulo Eduardo Teodoro 《Journal of Agronomy and Crop Science》2020,206(6):806-814
Most of the Brazilian soils, especially in Cerrado biome, have high acidity and toxic aluminium, making the application of limestone an indispensable technique to obtain high yield in soybean crop. The hypothesis of this study was that contrasting base saturation provides changes in water-use efficiency (WUE) and agronomic traits of soybean populations. Thus, we evaluated the WUE and agronomic performance of F3 soybean populations under different base saturation levels. Each experiment was conducted in a randomized complete blocks design with three replicates and 10 F3 populations (P1, P2, P3, P4, P5, P6, P7, P8, P9 and P10) for two crop seasons. Segregating populations were obtained by bulk method. In the first experiment, F3 populations were evaluated without correction of base saturation (V = 30%), while in the second experiment, limestone was applied three months before sowing to increase base saturation to 60%. The traits evaluated were as follows: calcium, magnesium and potassium contents, water-use efficiency (WUE), plant height, first pod height, main stem diameter and grain yield. Our findings indicate that WUE and agronomic performance of F3 soybean populations depends on the saturation condition. We identified the P4 and P9 populations as the most promising for use in breeding programmes aiming at higher tolerance to abiotic stress caused by low base saturation in soil. 相似文献
216.
SUMMARY The clinical, pathological and biochemical manifestations of maple syrup urine disease (MSUD) are similar in Poll Hereford and Poll Shorthorn X Poll Hereford calves. No significant differences were observed in branched-chain amino acid concentrations in plasma, or of branched-chain keto acid dehydrogenase activity in fibroblasts, between Poll Herefords homozygous normal and heterozygous for the mutation responsible for MSUD. Haemopoietic chimerism resulted in incorrect diagnosis of the MSUD genotype in 30% of non-identical twins when blood DNA was analysed using allele-specific amplification. Hair roots are shown to be a suitable source of target DNA for genotyping Poll Hereford cattle for the MSUD mutation. Twelve of 203 (5.8%) aged Poll Hereford bulls, sampled at saleyards during the last 4 months of 1993, were found to be heterozygous for the mutation. In contrast, the mutant sequence was detected in only 1 of 150 (0.7%) 2- and 3-year-old Poll Hereford bulls offered for sale at 2 stud sales held during 1993, suggesting that the prevalence of the disease may decline over the next few years. 相似文献
217.
218.
Progressive ethmoidal haematoma was diagnosed in 12 Thoroughbreds, 1 part- Arab and 1 stock horse. Ages ranged from 3 to 18 years and both males and females were affected. Diagnosis was based on history, clinical signs, endoscopic and radiographic findings, and was confirmed histologically in 10 cases. Eleven (78%) of the lesions were unilateral and 3 (22%) were bilateral. Two horses were euthanased on diagnosis, 4 were treated conservatively. Of the latter, 3 were euthanased 6 to 24 months after diagnosis, due to progression of the lesions, while 1 case resolved completely within 13 months. Eight horses were treated by surgical excision of the lesion. Three died in the post-operative period, 3 were euthanased within 48 months after recurrence of the condition, and 2 had no recurrence within 60 and 72 months, respectively. 相似文献
219.
A. Gomes M. R. Honer M. A. M. Schenk J. B. E. Curvo 《Tropical animal health and production》1989,21(1):20-24
Studies on purebred Nellore cattle and their crosses with Fleckvieh, Chianina, Charolais and the Ibagé breed (5/8 Aberdeen Angus, 3/8 Nellore) during 39 months in the field gave mean daily counts for engorging female ticks of 3.3, 25.2, 22.2, 21.0 and 59.7 per animal respectively. Annual fluctuations were similar in all groups; with the exception of the purebred Nellore mean counts are at levels considered dangerous for the stability of enzootic tick fever. 相似文献
220.