Metabolomics provide insights into the endogenous mechanism of strobilation in the scyphozoan jellyfi sh Rhopilema esculentum

Strobilation is a well-organized metamorphosis process in scyphozoan jellyfi sh,through which the benthic polyp develops into the pelagic medusa.So far,knowledge on the molecular mechanisms behind the drastic morphological and physiological changes remains limited.In the present study,the metabolic profi les in polyp and strobila stages of jellyfi sh Rhopilema esculentum were examined using ultra-performance liquid chromatography coupled to a mass spectrometer.A total of 3071 metabolites with putative annotation were detected,of which 167 were identifi ed as diff erential metabolites between the polyp and strobila.Among the metabolites,31 signifi cantly decreased and 136 signifi cantly increased in abundance in the strobila.Thyroxin,one of the previously proposed strobilation inducer of Aurelia,was not detected in this study.The indole-containing compounds are known for triggering strobilation in Discomedusae.Two indole derivatives and an indole-isomer containing metabolite were detected among the most signifi cantly increased metabolites,which may be potential endogenous molecules for strobilation initiation.The membrane-associated phospholipids and the infl ammation and oxidative stress-related eicosanoids were found to have signifi cant changes.Although the functions of these metabolites in strobilation are not yet completely known,they provide some clues to the induction of the process of strobilation and metabolic responses that take place during strobilation.

Using LA-ICP-MS to analysis elemental composition of statoliths of Scyphozoan jellyfish

Scyphozoan jellyfish outbreak events are drawing increasing attentions during the past decade.Elemental compositions of statoliths are helpful to understand jellyfish life history and blooming mechanisms,but very rare endeavor has been focused on the Scyphozoan class.In this work,we explored the feasibility of element analysis of Aurelia aurita(a representative Scyphozoan jellyfish outbreak species in China)which may be used as proxies of environment parameters during jellyfish living and moving.Statolith crystals of Aurelia aurita were found to be a gathering of hexahedron type trigonal needle with size of 10-50μm long,and 5-10μm in diameter.By using laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)downhole profiling method,elements such as Ca,Sr,Mg,Na and P were found to be above the limit of detection and limit of quantification.The epidermis of statocyst could significantly impact the element analyses,so the real statolith element signal section needs to be selected based on elements and Ca profiles together with care.By laser ablated a signal spot repeatedly,the analytical uncertainty was about 3%-4%for Sr/Ca content ratio and Mg/Ca content ratio,but above 10%for other element/Ca content ratios(n=3).Based on the analysis of statolith from temperature-control cultured jellyfish,Sr/Ca content ratios among different statoliths of the same jellyfish were about 6%(n=14),demonstrating biological processes/vital effects causing small variations compared with analytical uncertainties.Therefore,Sr/Ca content ratios may be used as a potential proxy to reveal the living environment variations the Scyphozoan jellyfish has experienced,such as temperature history,which is helpful to understand jellyfish bloom mechanisms.

中国北部海域灾害水母沙蜇(Nemopilema nomurai)及其它钵水母繁殖生物学特征与形态比较

为查清沙蜇大量暴发的原因,采用黄海北部的沙蜇亲体进行自然受精获得了数百万的螅状体,除海月水母和发形霞水母在消化腔和雌体的性腺中完成受精外,上述其余种类均为体外受精,霞水母属的2个种类的浮浪幼虫在形成螅状体前先形成一个具角质的浮浪体囊,沙蜇、海蜇、黄斑海蜇和Stomolophus meleagris螅状体繁殖新螅状体的唯一无性繁殖方式是足囊繁殖,霞水母可通过足囊和由匍匐茎形成囊胞两种方式繁殖新螅状体,海月水母(A.aurita)螅状体繁殖新螅状体的的无性繁殖方式包括足囊繁殖、出芽生殖、匍匐茎生殖、纵向分裂、内繁殖体和外繁殖体生殖,同时有直接发育现象,Rhizostoma pulmo的无性繁殖方式有足囊,出芽生殖,匍匐茎,浮浪体芽。