Summary Susceptible Ankole (Sanga:Bos indicus/Bos taurus) and crossbred Ankole x Jersey (B. taurus) and Ankole x Sahiwal (B. indicus) cattle derived from a farm in Rwanda with no recent history of theileriosis, were infected withTheileria parva stocks from Rwanda either by feeding infectedRhipicephalus appendiculatus ticks on the ears, inoculation of tick derived stabilate or natural exposure to tick challenge. The Ankole cattle originated
from local stock born and bred in East Coast fever (ECF) endemic areas of Rwanda. Disease, followed by spontaneous recovery,
was observed in 49 of the 72 Ankole cattle after infection withT. parva (68%); the other 23 animals (32%) died of ECF. In contrast 21 of the 33 infected crossbred cattle (64%) died of ECF. It is
concluded that the partialTheileria tolerance of the Ankole is, to a great extent, genetic. The basis of this partial tolerance seems to be their ability to
limit the explosive multiplication of macroschizonts during the acute phase of the disease.
Resumen Se infectó ganado Ankole susceptible (Sanga:Bos indicus/Bos taurus) y ganado cruzado Ankole x Jersey (Bos taurus) y Ankole x Sahiwal (Bos indicus) proveniente de una finca en Rwanda sin historia reciente de theileriosis, conTheileria parva procedente de Rwanda, mediante la adhesión en la oreja deRhipicephalus appendiculatus infectado, inoculación de estabilados derivados de garrapatas, o exposición natural a la enfermedad a través del vector.
El ganado Ankole era originario de un área endémica de theileriosis en Rwanda. Se observó la enfermedad seguida de recuperación,
en 49 de 72 animales Ankole infectados conT. parva (68%); los otros 23 animales murieron (32%). En contraste, 21 de los 33 animales cruzados infectados (64%), murieron. Se
concluye, que la tolerancia parcial del ganado Ankole es de origen genético. Las bases de ésta tolerancia genética, parece
debida a la habilidad para limitar en cierto modo la multiplicación explosiva de macroesquizontes, durante la fase aguda de
la enfermedad.
Résumé On a infecté du bétail sensible, de race Ankolé (Sanga:Bos indicus/Bos taurus) et des croisés Ankolé x Jersey (B. taurus) et Ankolé x Sahiwal (B. indicus), provenant d'une ferme au Rwanda sans cas récents de theilériose, avec des souches deTheileria parva du Rwanda, par l'application de tiques (Rhipicephalus appendiculatus) infectées sur les oreilles, par inoculation de stabilat de tiques infectées ou par l'exposition à un challenge naturel de
tiques. La souche d'Ankolé était originaire du cheptel local Rwandais, né et élevé dans les régions où la theilériose est
endémique. La maladie suivie par la guérison spontanée fut observée dans 49 des 72 Ankolés (68%), les autres 23 animaux (32%)
ont succombé à la theilériose. Par contre 21 des 33 croisées infectées (64%) ont succombé à la theilériose. Nous concluons
que la tolérance partielle des Ankolés contre la theilériose, est génétique. La base de cette tolérance semble être leur capacité
de limiter la multiplication explosive des macroschizonts pendant la phase aigu de la maladie.
本文利用透射电镜研究了寄生于家鸭小肠上皮细胞的菲莱氏温扬球虫的受精和卵囊壁的形成过程。作者在感染后96 h 的样品中发现一例大、小配子已受精;小配子已进入大配子中,大配子胞质中有一根纵切的鞭毛,小配子的核呈流体状,位于大配子核附近。卵囊壁是由成囊颗粒内含物进入合子表面的膜之间沉积成层而形成。成囊颗粒Ⅰ形成外层卵囊壁,成囊颗粒Ⅱ形成内层卵囊壁。沉积于膜之间的成囊颗粒Ⅰ内含物逐渐浓缩,堆积成颗粒状,使卵囊壁外层外表面形成颗粒状突起。成熟的卵囊壁由三层组成:即薄的外周膜、外层和内层。其内的合子原生质还被两层单位膜包裹。 相似文献
A field experiment was conducted during the winter seasons of 1992–93 and 1993–94 at Anand to study the effect of FYM, nitrogen and source of fertilizer on growth and yield of mustard [ Brassica juncea (L.) Czernj & Cosson]. The results showed significant variation in leaf area index (LAI), crop growth rate (CGR), dry matter production and seed yield. The direct effect of farmyard manure (FYM) was conspicuous in improving the growth of mustard. FYM application at 10 tonnes ha−1 significantly increased the LAI, CGR and dry matter accumulation per plant at almost all the stages during first year study (1992–93) and in pooled analysis. Similarly, nitrogen application registered maximum LAI, CGR at 75 kg level and RGR and NAR at 50 kg level at almost all the during both years. Sulphur carrying source (Ammonium sulphate plus single super phosphate) increased all stages growth characters. Maximum dry matter accumulation per plant and seed yield were recorded with highest levels of FYM (20 tonnes ha−1), N (75 kg ha−1) and source having S. Seed yield was strongly associated with LAI and dry matter accumulation per plant at all the stages. 相似文献
1. Four rearing temperature regimes (15, 20, 25, 30 °C) and three feeding schedules (ad libitum, restricting to the ad libitum intake of the 12th week and feeding 70% of this rate) were carried out with layer replacement pullets to 170 d of age. From this age, during lay, birds were kept at either 21 °C or on a 24‐h cycle of 21 for 18 h and 28 °C for the 6 h before lights out. Both a white and a brown egg‐laying strain were used.
2. Body weight at 169 d of age varied from, on average, 1409 g (15 °C, ad libitum) to 943 g (30 °C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 °C.
3. Rearing at 30 °C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing.
4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21–28 °C cycle, however, appeared small. 相似文献
Summary. Seeds of Polygonum persicaria from several sources, or from plants subjected to in lain treatments, were chilled for varying periods and incubated for a 3-week germination test period. Populations differed widely in seed weight and to some extent in the response to different periods of chilling. No relationship between this response and the climate of the locality of origin could be found. There was much variation in seed weight and germination behaviour between individual plants within populations. A total of four polymorphic seed categories were observed. The proportions of seeds in the two main categories varied widely between and within populations, and were affected by certain environmental factors. These factors also appeared to affect the degree of inter-plant variation in seed shape and germination behaviour. Travaux sur les espàes indésirables du genre Polygonum L. V. Variations dans le poids des semences, leur comportement à la germination et leur polymorphisme chez P. persicaria L. 相似文献