Segregation and linkage analysis of DNA markers in microspore derived and F2 populations of oilseed rape (Brassica napus L.)

Summary The segregation of RFLP and RAPD markers was compared in two oilseed rape (Brassica napus L.) breeding populations from the cross Topas x R4, the latter being a low linolenic mutation line. A total progeny of 68 F₂ and 40 microspore derived plants were studied with 25 markers. The results indicated a significant excess of Topas alleles at five RAPD loci in the microspore derived population. This suggests that genomic regions which probably affect microspore culture ability do not have identical distribution in the two population types.     

Elderly migration and development in small communities

"This paper develops a conceptual model of the process of community change [in the United States] in response to elderly inmigration. Analysis of intra-regional variation in elderly migration patterns in Appalachia, and synthesis of an emergent literature on the benefits and costs of attracting elderly migrants, serve as a backdrop for case studies, based on field observations and interviews, of three contrasting Appalachian communities at different stages of development as retirement destinations."     

Dietary lysine concentrations from deficient to excessive and the effects on broiler chicks

1. An experiment was designed to test the response of broiler chicks (0–21 d) to dietary lysine concentration. Concentrations ranged from 9.9 to 14.4 g of lysine per kg diet when energy was 13.4 MJ ME/kg.

2. Estimates of the concentration of lysine needed for maximum body weights gain, food consumption and gain:food ratio were calculated using two statistical methods. An average of these estimates was 12.0 g lysine/kg diet to 21 d of age.

3. Chicks given 13.9 or 14.4 g lysine/kg diet were negatively affected by these concentrations. The decreases in average weight gain, food consumption and food efficiency were caused mainly by several chicks that developed severe leg problems and were much smaller than their pen mates. Chicks with no leg problems gained weight as rapidly as chicks receiving optimal amounts of lysine.