Effect of copper on cell division, nitrogen metabolism, morphology, and sexual reproduction in the life cycle of Closterium moniliferum (Chlorophyceae)

Abstract

Additions of copper were shown to affect cell morphology, growth rates and nutrient uptake in Closterium moniliferum. These parameters are interrelated in the total life cycle of the organism. It was found that the timing of events in the life cycle, including sexual reproduction, could be changed when copper was added. When increasing concentrations of copper were added to the growth medium, Closterium rnoniliferurn exhibited a stimulatory, inhibitory, or toxic dose-response typical of organisms to trace metals. The stimulatory effect, occurring at pCu* 14.4, was demonstrated by an early increase in cell number, increased nitrate uptake, and early onset of sexual reproduction. The inhibitory effects of greater concentrations of copper (pCu* 12.1) were a longer lag phase, decreased nitrate uptake, and later onset of sexual reproduction. Light micrographs and scanning electron micrographs of normal and aberrant cells demonstrated the effect of copper on morphology. It was demonstrated that the sexual phase in some srains of Closteriurn moniliferurn could be triggered by changes in the amount of nitrogen in the medium. Although it was expected that each cell would have a minimal cell quota (Q nitrogen/cell) before sexual reproduction occurred, work here demonstrated that Q was not the critical factor 2 in the initiation of the process. Sexual reproduction occurred at Q = .05 micromoles nitrogen/cell up to .21 micromoles nitrogen/cell. Neither was cell density in batch pH Measurement • • • 34

The distribution and morphology of Fucus distichus in an estuarine environment and the effect of selected ions on the uptake of inorganic carbon and nitrate

“…An example of a physical effect would be temperature, which slows metabolic reaction rates if too low, and degrades proteins and other organic molecules when too high. Copper is an example of a chemical factor, being nutritionally required in low concentrations and becoming inhibitory at high levels (Christenson, 1983;. In a natural system, complex interactions occur between these factors, and biological influences such as competition and predation further modify the effects.…”