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1.
Shafik HM 《Acta biologica Hungarica》2003,54(1):121-136
The freshwater cyanoprokaryote Cylindrospermopsis raciborskii has become increasingly prevalent in tropical and temperate water bodies worldwide. The morphological characteristics of this species were investigated under different growth rates in continuous cultures (at steady state) and in batch (phosphorus starved) cultures with different mineral nitrogen forms. The species displays an enormous morphological variability under controlled condition. The occurrence of extreme long twisted filaments was found near the maximum growth rate and under high ammonium concentration. Rarely the heterocytes of Cylindrospermopsis raciborskii arise intercalarly between two neighbouring cells(i.e. intercalary heterocytes were found). The morphological features are highly effected by environmental conditions and nutrient availability. Under P-starvation extreme morphology appeared. The specifications of C. africana and C. cuspis overlap with that of C. raciborskii accordingly this is not clear characteristic feature to distinguish species. A pure culture of a pro- or eukaryote alga growing in continuous cultures is a good method for giving a suitable overview on all morphological possibilities of a tested organism. 相似文献
2.
- The exchanges of water between lactating female and young Mus musculus were modelled on the computer.
- The model was used to estimate rates of milk production and water recycling in various litter sizes under various water regimes by following the time course of injected tritiated water.
- The high correlation between estimated rates of milk production and actual growth rates of young was taken to indicate that the method gave if not the actual rates of milk production a very constant proportion of it.
- Approximately 50% of the water secreted in milk is returned to the mother by recycling.