Analysis of sub-populations of rapid-cycling Brassica rapa following recurrent bi-directional selection for cotyledon size

Recurrent selection programmes use one or just a few selection criteria, however other indirect traits may be unpredictably changed in a population. This study was conducted to determine the indirect effects of 10 cycles of bi‐directional recurrent selection for cotyledon size in the model system of rapid‐cycling Brassica rapa. Eight sub‐populations (four large‐ and four small‐cotyledon sizes) were phenotypically and cytologically evaluated. Each sub‐population was measured by five phenotypic traits. Ploidy and pollen viability were studied and compared with the initial population. Total weight was significantly different in broad and bottleneck‐1 sub‐populations. Total cell number exhibited statistically significant differences in broad and bottleneck‐1 sub‐populations, while cell number per unit area exhibited statistically significant differences in broad, bottleneck‐2 and bottleneck‐3 sub‐populations. Decreases in pollen viability in comparison with the base population were observed in three sub‐populations. Among the eight sub‐populations studied, the most significant phenotypic differences were observed within broad sub‐populations. Based on the above, it is possible that bi‐directional recurrent selection for cotyledon size may have been a result of indirect selection for two processes, endoreduplication and cell division.     

Needle catheter duodenostomy: a technique for duodenal alimentation of birds

A technique for duodenal alimentation (needle catheter duodenostomy) of birds was developed, using the domestic pigeon (Columba livia) as the experimental model. A needle catheter was inserted into the descending duodenum of 5 pigeons and was secured to the body wall and dorsum of each bird. A liquid diet was administered daily (in equal amounts of 0, 4, 8, 12, and 16 hours) for 14 days without adverse effects. On day 15, the catheters were removed, and the birds immediately resumed normal consumption of a pigeon ration and water diet. Although 4 of the 5 birds had minor weight loss, dietary alterations probably could be used on an individual basis to alleviate this problem. After oral alimentation was resumed, the 5 birds exceeded their initial body weight within 7 days. Four weeks after catheter removal, positive-contrast radiographic evaluations indicated that the duodenum of each pigeon appeared normal. Needle catheter duodenostomy was a viable method of alimentation in the domestic pigeon. This technique should be applicable for other avian species requiring bypass of the upper gastrointestinal tract proximal to the region of catheter insertion in the duodenum.     

Mammary tumors in a colony of beagle dogs

In a lifetime study, female beagle dogs in a closed colony were administered 226radium and 90strontium. An unirradiated control group was included in the study. A total of 223 of 356 dogs at risk developed 1,112 mammary proliferative growths (hyperplastic nodules and neoplasms). There was no correlation between occurrence and types of lesions in radiation and control groups. The age range for first occurrence of lesions was 10.4 to 13.9 years; hyperplastic nodule and benign mixed tumor occurred 1 to 2 years earlier than other lesions. A multiplicity of growths of similar or different morphological type were common throughout the lifetime of the dog. The female beagles, collectively, developed 244 hyperplastic nodules, 78 adenomas, 694 benign mixed tumors, 78 carcinomas, 14 malignant mixed tumors, and four myoepitheliomas. Proliferations occurred with increasing frequency from the cranial to caudal mammary glands. Metastasis was found in 77% of the dogs with carcinoma. The median time from diagnosis to metastasis was 10 months, but was shorter in dogs with infiltrative carcinoma.     

Anthelmintic resistance in Australian sheep nematode populations

SUMMARY The resistance status of gastro–intestinal nematodes to anthelmintics was evaluated on 881 sheep farms throughout Australia during 1991–92. Resistance was shown to be widespread. Overall, 85% of farms had sheep infected with nematodes resistant to benzimidazole, 65% to levamisole and 34% to combination (benzimidazole + levamisole) products. Resistance to ivermectin was not detcted. On only 9% of farms did all anthelmintic groups reduce egg counts by greater than or equal to 95%. The culture of faeces from untreated sheep showed Telodorsagia circumcincta, Trichostrongylus spp, Chabertia ovina and Haemonchus contortus to be the principal species. The nature and prevalence of resistance was not significantly correlated with stocking rate. However, resistance to combination products was almost twice as prevalent on farms in areas with an average annual rainfall of greater than 500 mm.     

Serological response in field cattle immunised againstBabesia berbera

Summary Serological tests were performed on 184 calves before and after immunisation with liveBabesia berbera parasites. Ninety per cent of the animals were negative at time of immunisation. Titres of 1∶64 and 1∶256 appeared 14 days after immunisation. From day 34 till 615 after immunisation all animals tested were positive. Three out of 24 calves challenged with live parasites after immunisation reacted with fever or parasites in spite of circulating antibody titres of 1∶256 or higher.

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Sumario Pruebas serologicas fueron llevadas a cabo en 184 terneros antes y despues de la immunización con parásitos vivos deBabesia berbera. Noventa y cuatro por ciento de los animals fueron negativos al momento de la immunizacion. Titulos de 1∶64 y 1∶256 aparecieron alrededor de 14 dias despues de la immunización. Desde los 34 hasta los 615 dias despues de la immunización todos los animales muestreados fueron positivos. Tres de 24 terneros desafiados con parasitos vivos despues de la immunización reaccionaron con fiebre ó parásitos a pesar de tener títulos de anticuerpos circulantes de 1∶256 o mas.

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Résumé Des épreuves sérologiques ont été effectuées sur cent quqtre vingt quatre veaux avant et après immunisation avec desBabesia berbera vivantes. Quatre vingt dix pour cent des animaux ont réagi négativement au moment de l'immunisation. Des taux d'anticorps de 1∶64 et 1∶256 sont apparus quatorze jours après l'immunisation. Du 34e au 615e jour après l'immunisation, tous les animaux testés ont réagi positivement. Trois veaux sur vingt quatre soumis à l'épreuve avec des parasites vivants après l'immunisation ont réagi par de la fièvre ou l'apparition de parasites, malgré des taux d'anticorps circulant de 1∶256 ou plus.

     

Immunization of cattle against Theileria annulata using killed schizont vaccine

Cultured bovine lymphoid cells infected with Theileria annulata schizonts were disrupted by freeze drying and sonication. Calves were inoculated with fractions of the disrupted cells with and without Freund's adjuvant, and their degree of immunity was ascertained by challenge with infected blood and with infected ticks. Serum antibody levels were determined by immunofluorescence tests. The highest degree of protection against blood challenge was found in calves receiving vaccine plus adjuvant, the particulate portion of the disrupted parasites being more effective than the soluble. High antibody titers developed in all animals receiving vaccine with adjuvant, but no relationship was observed between antibody titer and protection against challenge. Calves that were immune to blood challenge as a result of receiving killed schizonts remained completely susceptible to infective Theileria particles from ticks.