We performed a karyotype analysis on four species from Phylum Nemertea using regenerating somatic cells.Two palaeonemertean species,Cephalothrix hongkongiensis and Cephalothrix sp.,had the same chromosome number (2n=2...We performed a karyotype analysis on four species from Phylum Nemertea using regenerating somatic cells.Two palaeonemertean species,Cephalothrix hongkongiensis and Cephalothrix sp.,had the same chromosome number (2n=28),but different karyotypes (16 m+10 sm+2 st,NF=54 and 22 m+4 sm+2 st,NF=54,respectively).The karyotypes of the two heteronemerteans,Notospermus geniculatus and Ramphogordius sanguineus were 2n=38,30 m+6 sm+2 sm/st (NF=76/74) and 2n=56,48 m+4 sm+4 sm/st (NF=112/108),respectively.展开更多
The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few sp...The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4℃ and 6℃ showed no growth or gonadal development, and all died within 109 days. At 8℃ and 12℃, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28℃ showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature(16℃), photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis.展开更多
基金Supported by the National Natural Science Foundation of China (No.30270235)
文摘We performed a karyotype analysis on four species from Phylum Nemertea using regenerating somatic cells.Two palaeonemertean species,Cephalothrix hongkongiensis and Cephalothrix sp.,had the same chromosome number (2n=28),but different karyotypes (16 m+10 sm+2 st,NF=54 and 22 m+4 sm+2 st,NF=54,respectively).The karyotypes of the two heteronemerteans,Notospermus geniculatus and Ramphogordius sanguineus were 2n=38,30 m+6 sm+2 sm/st (NF=76/74) and 2n=56,48 m+4 sm+4 sm/st (NF=112/108),respectively.
基金Supported by the National Natural Science Foundation of China(Nos.30970333,31172046)
文摘The limited knowledge about the relationships between environmental factors and the maturation and reproductive seasonality of nemerteans is mostly obtained from field studies, and in many cases is conjectural. Few species have been studied under well-controlled laboratory conditions. In this work, the effects of temperature and photoperiod on gonad development and spawning of Cephalothrix hongkongiensis were observed by rearing worms under different temperatures and photoperiods. Worms reared at 4℃ and 6℃ showed no growth or gonadal development, and all died within 109 days. At 8℃ and 12℃, gonads could be seen from 90 days to the termination of the 360-day experiment, but no spawning was observed. Worms maintained at 16, 24, and 28℃ showed both gonadal development and spawning, and matured faster at higher temperatures. Under a fixed temperature(16℃), photoperiod did not have any significant impact on maturation and spawning. It is likely that temperature plays a major role in regulating the maturation and reproductive cycle of C. hongkongiensis.
