Professor Dr. J. Ritzema Bos

Ohne Zusammenfassung

---

Professor Dr. J. Ritzema Bos

     

Development of specific PCR primers for identification and detection of <Emphasis Type="Italic">Phytophthora capsici</Emphasis> Leon

A PCR-based method was developed for the identification and detection of Phytophthora capsici in pepper plants. Three PCR primers (CAPFW, CAPRV1 and CAPRV2) specific for P. capsiciwere designed based on the sequence of its internal transcribed spacer regions. CAPFW/CAPRV1 amplify a 452 bp product from P. capsici DNA whereas CAPFW/CAPRV2 a 595 bp fragment; neither set amplifies DNA from pepper or several fungi pathogenic to pepper. In conventional (single-round) PCR, the limit of detection was 5 pg DNA for both primer sets, whereas in nested PCR the detection limit for both was of 0.5 fg. However, when the dilution series of target DNA were spiked with plant DNA, amplification declined two-fold in both conventional and nested PCR. The CAPFW/CAPRV2 set in conventional PCR was used to detect P. capsici DNA in inoculated plants. Detection occurred as soon as 8h post-inoculation in stem samples from infected but still symptomless plants. The method was also tested to detect fungal DNA in infected soils.     

Effect of cutting and vacuum cleaning on the digestibility of oats by horses

Three mature Quarter Horse geldings were used in 2 Latin square experiments to measure the effect of cutting and vacuum cleaning of oats on digestibility. The horses were fed at the maintenance level of digestible energy (DE) as recommended by the NRC.¹²The data were analyzed by Latin square analysis of variance, and Tukey's t test was used to determine any differences between specific means.No significant differences among treatments were observed during either experiment, indicating that the digestibility of nutrients from oats was not affected by cutting and vacuum cleaning. Differences in the digestibility of the ether extract (EE) fraction between periods of experiment 1 were noted.     

Genetic parameters for body weight, reproduction, and parasite resistance traits in the Creole goat

We estimated the genetic parameters for BW, reproduction, and parasite resistance traits to implement a breeding program for the Creole goat. The traits were preweaning BW at 70 d of age (BW70d), BW at 11 mo of age (BW11), fecal egg count at 11 mo of age (FEC11) for all animals, packed cell volumes of lactating does (PCV), and their fertility (FER) and litter size (LS). We analyzed about 30 yr of data, which included 18,450 records on 11,970 animals from the INRA experimental flock in Guadeloupe (French West Indies). Heritability estimates were low for reproduction traits (0.11 ± 0.02 for LS and FER) to moderate for production traits (0.32 ± 0.03 for BW11; 0.20 ± 0.03 and 0.08 ± 0.02 for the direct and maternal heritability estimates of BW70d, respectively). Heritability estimates for gastrointestinal nematode resistance traits were situated in an intermediate range (0.13 ± 0.05 for PCV and 0.18 ± 0.04 for FEC11). Genetic correlations between FER, PCV, BW11, and the maternal effect of BW70d were altogether positive, whereas LS and FEC11 were almost uncorrelated phenotypically and genetically. These correlations are very favorable for setting up a breeding program, making it possible to improve BW, reproduction, and parasite resistance traits simultaneously.     

Computed tomography of testicular torsion in a juvenile dog with unilateral cryptorchidism

A 14-week-old male unilaterally cryptorchid Clumber spaniel was presented for acute lethargy. Physical examination revealed abdominal pain, and a single testis was palpated in the scrotum. Abdominal ultrasound and computed tomography (CT) revealed a poorly vascularized, ovoid structure immediately caudal to the left kidney with scant regional peritoneal effusion. Left intra-abdominal testicular torsion was confirmed at surgery, and routine cryptorchidectomy was performed. The patient recovered uneventfully from anesthesia and surgery.Key clinical message:The most common CT characteristics of testicular torsion were present in this case and correlated well with sonographic findings to allow for rapid, accurate diagnosis and surgical planning of unilateral, non-neoplastic, intra-abdominal cryptorchid testicular torsion in a juvenile dog. Contrast enhanced CT facilitated accurate localization of the undescended testis and evaluation of testicular perfusion and may be a useful alternative to ultrasound for diagnosing testicular torsion, especially in indeterminate cases.     

Tenacity of S. gallinarum in chicken feces]

The survival period of 22 S. gallinarum strains in chicken feces was examined. The suspension of the bacterium was homogenized with a certain feces quantity. The initial ratio was 10(7) to 10(9) colony forming units per gram of feces. The results show that the growth of 5 strains was completely inhibited within 24 hours post homogenization, 7 strains were still positive to S. gallinarum for 24 hours, 5 strains were positive for 48 hours and the last 5 strains were positive for 4 days. Additionally, the effect of tryptose soy (TSB) and Rappaport-Vassiliadis (RV) nutrient broths on the isolation rate of S. gallinarum from feces was examined at 37 degrees C and 43 degrees C. It was shown that the TSB medium was the best at 37 degrees C, in this experiment. The S. gallinarum concentration in RV medium was decreased at 37 degrees C from 9.1 x 10(8) to 1.6 x 10(6) and at 43 degrees C from 9.1 x 10(8) to 4.1 x 10(2).     

Generalized marker regression and interval QTL mapping methods for binary traits in half-sib family designs

A Generalized Marker Regression Mapping (GMR) approach was developed for mapping Quantitative Trait Loci (QTL) affecting binary polygenic traits in a single-family half-sib design. The GMR is based on threshold-liability model theory and regression of offspring phenotype on expected marker genotypes at flanking marker loci. Using simulation, statistical power and bias of QTL mapping for binary traits by GMR was compared with full QTL interval mapping based on a threshold model (GIM) and with a linear marker regression mapping method (LMR). Empirical significance threshold values, power and estimates of QTL location and effect were identical for GIM and GMR when QTL mapping was restricted to within the marker interval. These results show that the theory of the marker regression method for QTL mapping is also applicable to binary traits and possibly for traits with other non-normal distributions. The linear and threshold models based on marker regression (LMR and GMR) also resulted in similar estimates and power for large progeny group sizes, indicating that LMR can be used for binary data for balanced designs with large families, as this method is computationally simpler than GMR. GMR may have a greater potential than LMR for QTL mapping for binary traits in complex situations such as QTL mapping with complex pedigrees, random models and models with interactions.