Effects Of Temperature On Vitellin Degradation And Three Enzymes In Embryonic Development Of Haemaphysalis Longicornis

Ticks are a type of hematophagous obligate ectoparasites.They have a wide range of hosts and are extremely capable of reproduction.They can transmit a variety of pathogens during blood feeding,which can cause disease.Vitellin(Vn)degradation is an important physiological event during embryonic development.Vn is degraded with the participation of hydrolase to produce amino acids,sugars and lipids,which provide nutrients and energy for embryo development.This process is regulated by hydrolytic enzymes to ensure that embryonic development is completed programmatically.As an important ecological factor,temperature affects the reproduction and development of ticks.There is no research on the response of the Vn degradation and the hydrolases of ticks to temperature.Haemaphysalis longicornis is widely distributed in China and transmit a variety of pathogens,which can pose a great threat to human health and the development of animal husbandry.Therefore,it is of great scientific significance to study the effects of temperature on the degradation of Vn and three enzymes during the development of H.longicornis.1.The response of the hatching index to temperature was studied using statistical methods.The results showed that the incubation period was longer in the low temperatures group(16?: 40 days;20?: 32.5 days)than the control group(26?: 22.5 days),and the high temperatures group(30?: 20 days;35?:19.5 days)is shorter than the control group.The low temperatures group(16?: 21.18 %;20?: 63.26 %)and the high temperatures group(30?: 60.72 %;35? : 60.72 %)had lower hatching rates than the control group(26?: 88.13 %).2.The response of Vn degradation to temperature during embryonic development was analyzed using immunological and statistical methods.The results showed that the Vn content of the low temperatures group and the high temperatures group on the first day was lower than that of the control group.Vn undergone different degrees and incomplete degradation due to different temperatures,and new peptides were continuously generated with the degradation of Vn.Low temperatures delayed the appearance of subunits a,b,c,d and high temperatures made the appearance of all subunits occurs earlier.3.Using real-time PCR technology,the response of three hydrolase expression levels during embryonic development to temperature was analyzed.The results showed that Low temperatures promotes the expression of CB,but inhibits the expression of CD and AP.High temperatures had no obvious effects on the expression of CB and AP,but promoted the expression of CD.The low temperatures delayed the peaks of the expression of the three enzymes.The high temperatures had no obvious regular effects on the peak of CB expression,but made the peaks of CD and AP expression occur earlier.It can be seen that the effects of temperatures on the expression of the three enzymes are different,indicating that these three enzymes had many different functions in the embryonic development stage and all had stage specificity.The occurrence of CD and AP expression peaks was delayed in the lower temperatures group and advance in the higher temperatures group.This phenomenon had a positive correlation with the response of incubation period to temperatures.4.Using substrate specificity,the response of three hydrolase activities to temperature was examined.The results showed that the response of patterns of change to temperature was different.The effects of low temperatures on the peak of CB had no obvious regularity,but high temperatures delayed it.Low temperatures and high temperatures lead to the peak of CD activity.The overall activity of the AP at 16? of the lower temperatures group and at 35? of the higher temperatures group was significantly reduced.The low temperatures caused the AP to show a higher value in advance and the high temperatures also caused the peak time to appear earlier than the control group.