A Preliminary Study On The Endocrine Control Function Of Oratosquilla Oratoria

Oratosquilla oratoria is one of the important perennial marine economic crustaceans in the coastal regions of China.It Widely distributed in western Pacific,including Russia,Japan,Korea,China,Vietnam,and coastal Australia.Due to its tender and delicious taste and rich nutrition,it is an important fishery resource in many countries and regions.In China,due to factors such as excessive fishing and environmental degradation,the shrimp resources are currently undergoing a severe recession,and the market prices are increasing.Conservation of this species and the development of successful artificial breeding technologies are therefore extremely important.Effective resource management and breeding programs for O.oratoria require detailed knowledge of its reproductive biology.The eyestalk is an important reproductive and endocrine organ of crustaceans.The X-organ-sinus gland complex participates in the secretion of neuropeptides such as gonad-inhibiting hormone(GIH),crustacean hyperglycaemic(CHH),and molt-inhibiting hormone(MIH)involoed in regulting growth development,molting,metabolism and other physiological and biochemical activities.In the present study,we observed the structure of the X-organ-sinus gland complex by conventional histological methods and electron microscopy firstly.And then investigated the effects of unilateral eyestalk ablation on ovary development,nutrition compositions of ovary,hepatopancreas and muscle in female mantis shrimp,and viellogenin(Vtg).Finally,we performed transcriptome sequencing of the testis,ovary,female and male eyestalks and the androgenic gland of mantis shrimp,and compared the expression pattern of transcripts from the female and male eyestalks libraries,to identify genes involved in reproduction,The main findings are as follows:1.The mantis shrimp eyestalk consists of visual cortex,medulla externa(ME),medulla interna(MI),medulla terminalia(MT).The ME occupied the most volume the eyestalk followed by the MT,and the MI is the smallest.The sinus gland is located between the MI and the MT,and close to the MI,which is composed of the wall of the sinus and the central blood chamber.The X organ is located in the ME,MI and MT,and it is composed of discrete neurosecretory cells.We observed the sinus gland ultrastructure of mantis shrim,pand distinguish four kinds of nerve cells according to the size and quantity of neurosecretory cells that secrete endings in the mantis shrimp.2.The GSI was increased in the mantis shrimp in the treatment group,and significant higher than that in the control group on 5,10,and 15 days(P < 0.05).HPI was found to be significantly decreased in both treatment and control groups in the late stage of the whole experiment(P < 0.05).There was higher glycogen level in ovary of the mantis shrimp in the treatment group than in the control group,and had significant difference in 5 days(P < 0.05).The same case was found in glycogen level in hepatopancreas(P < 0.05).But the glycogen level in muscular was decreased in the treatment group in 5 days and earlier than that in the control group.In the ablated eyestalk mantis shrimp,the hepatopancreas protein content was elevated in 10 days and then significantly higher than the mantis shrimp in the control group did(P < 0.05).The protein content in ovary of the treatment group was higher than that of the control group,and had a significant difference in 15 days(P < 0.05).The protein content in ovary in both two groups had the same pattern that elevated firstly and then declined,without significant difference(P > 0.05).The expression of Vtg in the hepatopancreas was elevated in 10 day and it was decreased in 15 days then elevated slowly again.The expression of Vtg in the ovary was increased in the mantis shrimp in the treatment group(P < 0.05)and it was declined in 10 days.The expression of Vtg in the ovary was increased in the mantis shrimp in the control group and had significant difference in 10,15 days(P < 0.05).3.We obtained 51,427,400 clean data,including 26,360,940 clean data in female eyestalk,and 25,066,460 clean data in male eyestalk.After assembly,a total of 25,316 Unigenes were obtained in eyestalk.By comparing the expression level of the female and the male eyestalk,865 genes were considered as DEGs,of which 588 showed higher expressed in the female eyestalk,and 277 showed higher expressed in the male eyestalk.Among these DEGs CHH/MIH/GIH neural hormone family,c-type lectin(C?type lectin,Let)were up regulated in male eyestalk,and heat shock protein(heat shock protein,Hsp),ferritin(ferritin)and cytochrome P450(cytochromeP450)up regulated in female eyestalk.The transcriptomic data obtained in the present study will provide a basis for our future research on the endocrinology and regulatory mechanism of eyestalk in mantis shrimp endocrine.