Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olen...Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olenekian,Early Triassic)marine deposits of Jurong,Jiangsu and Chaohu,Anhui,China.This new discovery documents the third and youngest species of Teffichthys,which is slightly younger than the Dienerian(Induan)T.elegans from Guizhou and the early Smithian T.madagascariensis from Madagascar.The new species shows diagnostic features of Teffichthys(presence of a spiracular,38-41 lateral line scales,and no more than three epaxial rays in the caudal fin)but differs from T.madagascariensis and T.elegans in some autapomorphies(e.g.,a horizontal opercle/subopercle contact and smooth scales with a nearly straight posterior margin).The diagnostic features for the genus Teffichthys and the family Perleididae are emended based on detailed comparisons of the new taxon with other perleidids.The phylogenetic relationships of perleidids with other stem neopterygians are discussed using a cladistic approach,and the results provide new insights into the phylogeny and classification of main stem neopterygian clades.展开更多
文摘Perleididae is a group of stem neopterygian fishes known only from the Triassic.Here,we report the discovery of a new perleidid,Teffichthys wui sp.nov.,based on six well-preserved specimens from the late Smithian(Olenekian,Early Triassic)marine deposits of Jurong,Jiangsu and Chaohu,Anhui,China.This new discovery documents the third and youngest species of Teffichthys,which is slightly younger than the Dienerian(Induan)T.elegans from Guizhou and the early Smithian T.madagascariensis from Madagascar.The new species shows diagnostic features of Teffichthys(presence of a spiracular,38-41 lateral line scales,and no more than three epaxial rays in the caudal fin)but differs from T.madagascariensis and T.elegans in some autapomorphies(e.g.,a horizontal opercle/subopercle contact and smooth scales with a nearly straight posterior margin).The diagnostic features for the genus Teffichthys and the family Perleididae are emended based on detailed comparisons of the new taxon with other perleidids.The phylogenetic relationships of perleidids with other stem neopterygians are discussed using a cladistic approach,and the results provide new insights into the phylogeny and classification of main stem neopterygian clades.
文摘目的 研究产气荚膜梭菌(Clostridium perfringens,C.perfringens)芽孢的萌发特性。方法 本研究以C.perfringens芽孢为研究对象,研究L-丙氨酸、L-谷氨酰胺、L-赖氨酸、L-天冬酰胺(L-asparagine)、氯化钾(KCl)、钙离子与2,6-吡啶二羧酸(pyridine-2,6-dicarboxylic acid,DPA)的螯合物(a chelate of Ca^(2+)with DPA,Ca^(2+)-DPA)、十二烷胺、L-asparagine和KCl的混合物(a mixture of L-asparagine and KCl,AK)、L-asparagine、D-葡萄糖、D-果糖和KCl的混合物(a mixture of L-asparagine,D-glucose,D-fructose and KCl,AGFK)、脑心浸液肉汤(brain heart infusion broth,BHI) 10种萌发剂对芽孢萌发的影响,选取处理后芽孢DPA释放量、热抗损失、芽孢溶液吸光度(optical density at 600 nm,OD_(600))及微观图像的变化来表征芽孢萌发,筛选出诱导C.perfringens芽孢萌发效果最好的萌发剂,并对其浓度进一步优化。结果 AK是诱导C.perfringens芽孢萌发效果最好的萌发剂;100 mmol/L AK与C.perfringens芽孢共孵育120 min时,C.perfringens芽孢溶液OD_(600)下降至49.42%,88.56%的DPA从芽孢核内释放,1.76个log芽孢被随后的湿热处理杀灭,在相差显微镜下由“亮相”变成“暗相”状态的芽孢数量最多;比较不同浓度的AK诱导芽孢萌发的效果,发现150 mmol/L AK诱导C.perfringens芽孢萌发的效果最好,其萌发率达63.17%。结论 AK诱导C.perfringens芽孢萌发的效果较好,为揭示C.perfringens芽孢的萌发机制奠定理论基础,同时为更高效、定向地防控肉制品中的C.perfringens提供科学依据。
