Effects Of Different Temperatures On Growth, Development, Sexual Maturation And Aging Of The Annual Fish Nothobranchius Guentheri

As a annual killifish, Nothobranchius guentheri (N. guentheri) has a genetic short lifespan which results from the constant monsoon climate in their original habitat. N. guentheri originates from savannah regions in East Africa and has adapted to the seasonal changes between heavy rains and severe draught. They are egg-layers and deposit their eggs in the mud during the dry season, and the eggs will continue to develop and hatch when the rainy season begins. After hatched out, the fish will rapidly grow up, mate and become aging in months. And their living and aging is sensitive to the change of ambient temperature. Therefore, the aim of our research is to study the effects of different temperatures on the growth, development, sexual maturation and aging of N. guentheri.Research methods are stated briefly as follows. An equal number of N.guentheri fry are raised separately under the four temperatures 25℃,27℃,29℃and 31℃dating from their birth. Daily observation and record are taken on their development and survival, and weekly measures are carried on the variation of their body length and egg number. Then summary is done once a month and curves based on the results will be drawn. Moreover, aging research is commenced on the strongest male fish at the age of seven months old in the four temperature groups. And four aging markers are selected and utilized below:SA-β-Gal in the epithelium, lipofuscin in the liver, protein oxidation in the muscle and neurodegeneration in the brain. The amount of the four markers are compared to show the overall aging of organism.The conclusion illustrated that the effects of temperature were prominent on N.guentheri, which showed a better growing and living at lower temperature. Especially, the fish in the 25℃group presented the best situation of growth, development, maturation and surviving among all the four groups. And they were getting aging more slowly.Compared with the 25℃group, higher temperatures bated the growth, and the backbones of the fish developed a unnormal bending in the groups of 29℃and 31℃.Furthermore, it has been found that the female were influenced more obviously than the male by the change of temperature. At lower temperatures, the first spawn appeared over one weeks earlier than that at higher temperatures, while the time had hardly differed when the male of 4 groups turn colorful. Also, low temperature could keep the population of the female steady as well as the male.Besides, quantification of the four aging markers also demonstrateed that at lower temperatures, expression of the 4 aging markers stated above were reduced compared with those at higher temperatures. That means low temperature can slow and defer the process of aging in N.guentheri.In summary, N.guentheri is sensitive to the change of temperature on the aspects of growth, development, sexual maturation, survival and senescence, and low temperature has apositive and distinct effects on their lives.