La peche dans le fleuve Niger

The fish production of the River Niger can best be estimated from a country by country evaluation of the tonnage exported and that consumed locally. All exported and some locally consumed fish are preserved by smoking or sun drying, a process which entails a loss of weight. Coefficients to correct for this of between 2.6 to 4 have been calculated depending on the type of product. A further loss occurs due to handling and to insect attack, which may account for up to 40% of the production. Taking the above factors into account the productions estimated for the various countries of the Niger River basin are as follows: Guinea (3,600 t), Mali (90,000 t), Upper Volta and Ivory Coast (negligible), Niger (5,200 t), Dahomey (1,200 t), Nigeria (25,000 t), Cameroon (3,000 t). A total production of 128,000 t is, therefore, obtained for the basin as a whole, excluding the Kainji Reservoir. At this level of production, there have been no intimations of overfishing from any part of the basin, and there is unanimity that fishing could be intensified. On the basis of the estimates of existing production and local estimates of potential production it is possible that up to 200,000 t of fish could be produced annually from the basin as a whole.

Le斑马鱼nanos1基因在配子发生中的原位杂交研究

利用组织原位杂交技术,以地高辛标记的反义RNA为探针,检测了斑马鱼(Daniorerio)nanos1基因在卵子发生及精子发生中的表达分布特点,初步探讨了该基因在斑马鱼配子发生中可能的功能。结果表明:在斑马鱼卵子发生中,nanos1mRNA均匀分布于卵原细胞和各时期卵母细胞的胞质中;在卵原细胞和Ⅰ、Ⅱ期卵母细胞中,nanos1mRNA的杂交信号十分强烈,而较晚期卵母细胞中信号明显减弱。在斑马鱼精子发生中,nanos1mRNA可在精原细胞和初级精母细胞中检测到。nanos1mRNA的阳性信号在精原细胞中极为

Parametros operacionais da irrigacao por sulcos em contorno em LE argiloso de cerrado.

2001

Strat?gie et id?ologie: le haut commandement fran?ais et la guerre civile espagnole?

Jackson, Peter, 'Strat?gie et id?ologie: le haut commandement fran?ais et la guerre civile espagnole ', Guerres Mondiales et Conflits Contemporains - Revue Trimestrielle d'Histoire (2001) 199 pp.111-133 RAE2008