The Condition Of Diapause And Biochemical Composition Comparition For Diapause Of Mylabris Cichorii Linnaeus Egg

As important Chinese medicine material, Mylabris cichorii has anti-cancer function. Facing the fact of shortened resources of the blister beetles, artificial rearing M. cichorii become one of the effective approaches to obtain large numbers of blister beetles. Under natural conditions, M. cichorii occur one generation every year, and enter diapause as egg. Research of diapause mechanism was foundation of large-scale breeding of M. cichorii. This paper systematically analysed that the condition of diapause, diapause termination and biochemical composition comparition between diapause and non-diapause of M. cichorii egg, which was expected to provide underlying data for large-scale feeding of M. cichorii. The main results as follows:Diapause incidence of offspring in M. cichorii was evaluated by exposing parents generation and offsprings to different photoperiod and temperature, observing condition of diapause and diapause termination. The results showed that photoperiod was the critical environmental factor in induction of diapause of M. cichorii egg. Diapause of M. cichorii egg was induced by Short photoperiod. Long daylengh was benefit to development and restrain diapause. Under constant temperature 28℃, the critical photoperiod for diapause induction of egg was estimated to be between L11: D13 and L10: D14. Diapause egg developed normally until 18 egg age, and stop embryonic development and entered diapause.Temperature was the key factor of M. cichorii egg diapause termination. Diapause of egg was terminated by Low temperature (10℃) with 10 days.This paper determined the contents of trehalose, glycogen, glycerol, DNA, RNA and protein in diapause egg and non-diapause egg under different development stages of M. cichorii. During early period of diapause, the change trends of biochemical indicators contents were similar between diapause and non-diapause egg. But some biochemical indicators had different change trend between diapause egg and non-diapause egg in the later development.Contents of glycogen, trehalose and glycerol were examined respectively by gravimetric method. In pro-diapause period, change trends of glycogen,trehalose and glycerol contents in non-diapause eggs were similar to change trends of diapause egg in various periods. The titers of glycogen in diapause egg showed linear decrease while trehalose and glycerol contents increased during pro-diapause. During diapause developing, the titers of trehalose and glycerol in diapause egg were kept on a higher level, while contents of glycogen were kept on a lower level. The content of trehalose, glycerol and glycogen were 9.47～10.55ug/mg, 30.04～39.48ug/m, 2.77～3.05ug/mg respectively during diapause period. Diapause egg of M. cichorii accumulated trehalose and polyol. No accumulation of glycogen was determined. So M. cichorii belong to trehalose accumulation.Contents of DNA and RNA were directly obtained with Bio-Rad microplate determination. In pro-diapause period, content of DNA was increased with embryonic development in diapause and non-diapause egg. During diapause period, contents of DNA had no significant change. The titers of DNA changed between 0.36～0.68ug/mg in diapause egg and 0.24～0.88ug/mg in non-diapause egg. In pro-diapause period, change trends of RNA contents in non-diapause eggs were similar to change trends of diapause egg. The titer of RNA was increased with embryonic development, and reach to the maximum value, 1.14ug/mg in diapause egg and 0.92ug/mg in non-diapause egg. Contents of RNA showed linear decrease after 20days.Protein contents were examined by Bradford. In pro-diapause period, change trends of protein contents in non-diapause eggs were similar to change trends of diapause egg in various periods, and reach to the maximum value, 41.39ug/mg in diapause egg and 35.87ug/mg in non-diapause egg. Special protein profiles of M. cichorii egg under diapause condition at 18 days were analysised by 12%SDS-PAGE. Protein with molecular weight of 80KD was found in diapause egg. And expressions levels of two proteins (45KD and 23KD) were raised in diapause egg. These proteins may be associated with the diapause of M. cichorii.Photoperiod of parents generation was the critical environmental factors in induction of diapause of M. cichorii offspring. And termination of diapause was controlled by low temperature. Diapause egg growed normally at early stage and entered into diapause at 18 days. Trehalose and glycerol were the major storage of sugar during diapause periods, and content of gene expression was decline during diapause. Three proteins had separated from diapause egg.