Species identification and phylogenetic analysis of genus Nassarius(Nassariidae)based on mitochondrial genes

Genus Nassarius contains many subgenera, such as Zeuxis, Telasco, Niotha, Varicinassa, Plicarcularia, Nassarius s. str. and Reticunassa. On the basis of morphological characteristics of the shell and radula and sequences of mitochondrial cytochrome oxidase subunit I (COI) and 16S rRNA genes, Nassarius specimens collected from the South China Sea were identified and phylogenetically analyzed. Although Nassarius sp. and Nassarius (Varicinassa) variciferus were morphologically different in their shells, few variations were found among their radular teeth and sequences of mtCOI and mt16S RNA genes. Therefore, Nassarius sp. should be classified as N. (Varicinassa) variciferus. Nassarius (Zeuxis) sp. has only a subtle difference from Nassarius (Zeuxis) algidus on the shell, but it shows obvious differences in radular teeth and DNA sequence, indicating that they are two distinct species. Sequence divergence of mtCOI and mt16S RNA genes within Nassarius species was much lower than that between species, suggesting that these two genes are suitable for Nassarius species identification. Phylogenetic analysis (neighbor-joining and maximum parsimony) based on mtCOI and mt16S rRNA genes revealed the presence of two groups in genus Nassarius and a closest relationship between subgenera Zeuxis and Telasco. Species of subgenus Plicarcularia did not form a single clade. The molecular phylogeny was not congruent with the previous morphological phylogeny. The subgeneric divisions of genus Nassarius appear to be uncertain and unreliable.

The Relationships Between Toxicity, Species and Populations in Nassarius Based on Toxin Detection and Multiple Gene Barcoding

Nassarius causes many poisonings in China and other Asian countries.The toxicity of Nassarius is related to species and populations.However,the molecular assignment of different toxic Nassarius samples is still unclear,which deteriorates the poisoning.Our study combined toxicity,toxin detection and multiple genes DNA barcoding to assign the various toxic Nassarius species and populations from China coast.The toxicity test indicated that different Nassarius species and different populations within one Nassarius species had different toxicity.Based on High Performance Liquid Chromatography,the toxin was confirmed to be TTX.The toxin content varied in different samples.The COI,16 S and ITS sequences revealed different toxic Nassarius species as monophyletic clades.All the samples tested have been assigned to species level.However,the different toxic populations within N.succinctus,N.variciferus and N.semiplicata did not form separated clades,and the toxic and nontoxic species did not form two clades separately.Our study constructed the relationship between toxicity and taxonomy assignment of different toxic Nassarius samples based on toxicity detection and multiple gene DNA barcoding,which provides the basis for controlling poisoning and studying the toxin-resistance difference in Mollusca.It is also indicated that the toxicity of Nassarius is really related with species at the genetic level,but not absolutely related with populations.

Two new species of the genus Nassarius(Gastropoda:Nassariidae) from the South China Sea

Two species of Nassarius Duméril, 1805 from the South China Sea are described and illustrated. The specimens are in the Nassariidae collection of the Marine Biological Museum of Chinese Academy of Sciences, Qingdao.Nassarius concavus sp. nov., from the sandy bottom at a depth of 180 m, resembles Nassarius glabrus Zhang and Zhang, 2014 in general shell morphology, but differs from the latter in having a smaller, more slender adult shell without axial ribs on the upper teleoconch whorls. Nassarius nanshaensis sp. nov., from the Nansha Islands at a depth of 56–147 m, is similar to Nassarius maxiutongi Zhang, Zhang and Li, 2019 in the shell sculpture, but differs in having a more slender shell with a higher spire, and fewer cusps on the rachidian tooth(9–11 vs. 13–17).

中国沿海部分地区半褶织纹螺的毒性及毒素组成分析

为确定中国沿海不同地区织纹螺中的毒素成分,本研究在江苏省、浙江省和福建省设立了多个采样点,对采集的半褶织纹螺样品进行了毒性测试和毒素组成分析。研究结果显示,采集的织纹螺样品毒性范围为2—664MU(mouse unit)/g湿重,其中,采自江苏省连云港地区的织纹螺样品毒性远高于其它地区。应用高效液相色谱-质谱联用(high-performance liquid chromatography-mass spectrometry,LC-MS)方法对样品中的毒素成分进行分析,在各地的织纹螺样品中均检测到了河豚毒素(TTX)及trideoxy TTX、4-epi TTX和anhydro TTX等衍生物,但各种毒素成分所占的比例存在差异。自江苏省连云港市和浙江省舟山市采集的织纹螺样品中,Trideoxy TTX是主要的毒素成分,TTX和其它两种毒素成分次之;而自江苏省盐城市、浙江省宁波市及福建省宁德市和莆田市采集的织纹螺样品中,TTX的含量最高。采集自江苏省连云港和浙江省舟山市的大部分织纹螺样品中,肌肉组织的毒素含量最高,其次是消化腺组织,其余组织中的毒素含量最低。高毒性成分TTX的最高值主要出现在肌肉组织或消化腺组织中。从实验结果可以看出,各地的有毒织纹螺中毒素成分基本一致,而各种毒素成分所占的比例有一定的差异,织纹螺的毒性与高毒性成分TTX的含量有关。

河豚毒素生物检测法与荧光光度法的比较研究

为了比较生物检测法和荧光光度法检测河豚毒素(TTX)的性能,使用昆明系小鼠与荧光光度法同时检测10份织纹螺(Nassarius semiplicatus)中河豚毒素的含量。结果表明,荧光光度法与生物检测法之间具有较好的相关性。小鼠死亡时间的倒数与TTX的注射量间的线性方程为y=0.006 97x+0.003 68,r=0.995,精密度为7.4%～10.9%,回收率为90.5%。荧光光度法中TTX的浓度与荧光强度间的线性方程为y=318.09x+8.60,r=0.999,精密度为3.1%～6.6%,回收率为98.7%。荧光光度法测定结果稳定,受外界因素影响小,且速度快,灵敏度高,在河豚毒素的定量检测及预防河豚毒素中毒方面有广泛的应用前景。

三种织纹螺性畸变的发展过程与雄性结构效应

从2000年3月到2002年10月对中国沿海海产腹足类性畸变的大范围调查过程中 ,在广东省汕头港、湛江港和厦门港分别采集到西格织纹螺 (Nassariussiquijorensis)、胆形织纹螺(Nassariusthersites)和节织纹螺 (Nassariushepaticus)等3个种 ,解剖观察发现3种织纹螺的雌性个体都发生了性畸变现象。根据织纹螺性畸变的发展过程 ,对目前的性畸变发展划分体系作了新的修改和补充。通过对比性畸变个体与正常雄性个体的特征 。

纵肋织纹螺人工育苗试验

为探索纵肋织纹螺苗种繁育技术,2016年利用25 kg亲螺进行了纵肋织纹螺人工育苗试验,并对纵肋织纹螺的繁殖习性、生态习性进行了观察。结果显示,纵肋织纹螺为雌雄同体,受精卵产于卵囊内,卵囊黏附于固着物表面。纵肋织纹螺的卵囊呈圆片形状,直径2~4 mm,每个卵囊内有受精卵8~40粒,在水温20~25℃条件下,受精卵约经6~8 d发育成为面盘幼虫。面盘幼虫经18~24 d培育,变态成稚螺。试验共培育出平均壳高4.6 mm的纵肋织纹螺苗种1 060万粒。