Karyotype And Nuclear DNA Contents Analyses Of Nemerteans

Only 13 nemertean species have been mentioned for their chromosomes in literatures, but there were no karyotype analyses. The measure technology of DNA content has applied extensively in animal kingdom, but there was only one research concerning the nemertean. The present paper report the karyotype of four nemerteans and nuclear DNA contents of eight nemerteans.1 The karyotype of four nemertean speciesThe present study optimizes the chromosome analysis technique. The karyotype of four nemerteans was studied from the regenerating somatic cells using hot air-dried method. The species conclude Cephalothrix simula (Iwata, 1952), Cephalothrix sp., Ramphogordius sanguineus (Rathke, 1799) and Notospermus geniculatus (Delle Chiaje, 1828). It is obviouse that different nemerteans need different methods.In C. simulus, 80% of the 100 counted spreads have the diploid chromosome number of 2n=28.The karyotype of P. simulus is 2n=28, 16m+10sm+2st, FN=54.In C. sp., 81% of the 100 counted spreads have the diploid chromosome number of 2n=28. The karyotype of it is 2n=28, 22m+4sm+2st, NF=54.In R. sanguineus, 70% of the 100 counted spreads have the diploid chromosome number of 2n=56. The karyotype of it is 2n=56, 48m+4sm+4sm/st, NF=112/108.In N. geniculatus, 62% of the 100 counted spreads have the diploid chromosome number of 2n=38. The karyotype of it is 2n=38, 30m+6sm+2sm/st, NF=76/74.2 Nuclear DNA contents of 8 nemertean speciesThe nuclear DNA contents of eight nemertean species were quantified using flow cytometry with chicken red blood cells as the internal or external reference standards. The mean 2C-values of the species were as follows, respectively: Nipponnemertes punctatula, 1.10±0.004 pg; Quasitetrastemma nigrifrons, 1.38±0.03 pg; Ramphogordius sanguineus, 1.65±0.06 pg; Notospermus geniculatus, 1.74±0.04 pg; Baseodiscus curtus, 2.56±0.10 pg; Lineus alborostratus, 2.67±0.09 pg; Cephalothrix simula, 3.03±0.13 pg; Cephalothrix sp., 3.05±0.12 pg. The interspecies difference was significant (p<0.01). Hoplonemerteans have the least nuclear DNA content, while palaeonemerteans have the most nuclear DNA content. These data show that DNA contents of nemerteans seem have some relationships with the high classification unit.