The Effect Of Light On The Population Growth Of Ciliated Prozoa

The kingdom Ciliophora, is a large and diverse group within Protozoa. Ciliates, eurychoric unicellular eukaryotes, are characterized by:(1) cilia exist at least some time during the whole life cycle; (2) nuclear dimorphism:two types of cell nuclei, i.e. the bigger, non-germline macronucleus and the smaller, germline micronucleus; (3) asexual reproduction is two divisions, while sexual reproduction is zygogamy. And ciliates play an important role in ecosystem and are commonly used in the research fields of cell biology and phyletic evolution.The growth and reproduction of most of organism are affected by light. However, this kind of work has not been reported in cliates yet. So, we use experimental ecological methods to reveal the influence of light on population dynamics of ciliates. Euplotes vannus (marine species) and Paramecium caudatum (fresh water species) are chosen as representive ciliate species. E. vannus and P. caudatum are cultured in beef extract media, bacteria culture media, inactivated bacteria media, Escherichia coli media and inactivated E. coli media at 23℃ under light and dark conditions.The results are as following:(1) in beef extract media the E. vannus’ population growth rate of light (0.278) was lower than that of darkness (0.4271), the population densities in equilibrium phase of light (50 ind/ml) was lower than that of darkness (449 ind/ml); (2) in bacteria media the E. vannus’ population growth rate of light (0.2145) was lower than that of darkness (0.2537), the population densities in equilibrium phase of light (200 ind/ml) was lower than that of darkness (310 ind/ml); (3) in inactivated bacteria media the E. vannus’ population growth rate of light (0.1881) was lower than that of darkness (0.2304), the population densities in equilibrium phase of light (240 ind/ml) was lower than that of darkness (355 ind/ml); (4) in E. coli media the E. vannus’ population growth rate of light (0.3099) was lower than that of darkness (0.4194), the population densities in equilibrium phase of light (210 ind/ml) was lower than that of darkness (340 ind/ml); (5) in inactivated E. coli culture medium the E. vannus’ population growth rate of light (0.1717) was lower than that of darkness (0.2931), the population densities in equilibrium phase of light (285 ind/ml) was lower than that of darkness (380 ind/ml); (6) in beef extract media the P. caudatum’s population growth rate of light (0.5183) was higher than that of darkness (0.4033), the population densities in equilibrium phase of light (110 ind/ml) was higher than that of darkness (47 ind/ml); (7) in bacteria media the P. caudatum’s population growth rate of light (0.3534) was higher than that of darkness (0.2764), the population densities in equilibrium phase of light (140 ind/ml) was higher than that of darkness (65 ind/ml); (8) in inactivated bacteria media the P. caudatum’s population growth rate of light (0.3241) was higher than that of darkness (0.2379), the population densities in equilibrium phase of light (130 ind/ml) was higher than that of darkness (60 ind/ml); (9) in E. coli media the P. caudatum’s population growth rate of light (0.3355) was higher than that of darkness (0.2447), the population densities in equilibrium phase of light (880 ind/ml) was higher than that of darkness (370 ind/ml); (10) in inactivated E. coli media the P. caudatum’s population growth rate of light (0.3319) was higher than that of darkness (0.2905), the population densities in equilibrium phase of light (650 ind/ml) was higher than that of darkness (270 ind/ml).Therefore, light have influence on the reproduction of E. vannus and P. caudatum. Light inhibits the reproduction of E. vannus, while it promotes the reproduction of P. caudatum.