摘要:

Chromosome numbers of 2n= 13, XO and 2n= 17, XO are reported for 2 genera of the Alydidae. Meiotic behaviour is comparable to that of species in 6 genera of the Coreidae which also have an XO sex determination mechanism in males, and chromosome numbers of 2n= 15, 19 and 21. A further 3 coreid genera in which 2n= 18, 20, 22 and 26 are found have an XnX2O mechanism, the meiotic behaviour of which differs in some respects from published reports of other Heteropterans with multiple X chromosomes. The large m-chromosomes present in several species have permitted their morphology to be determined. The significance of achiasmate pairing of m-chromosomes and monhomologous X chromosomes in achieving regular segregation is noted, and the role of chromosome number changes in the evolution of the Coreidae is discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796934

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

Hyphae and haustoria of the pycnio-aecial stage ofCronartium flacciduminPinus pineaandP. pinasterwere observed with a TEM. This characteristically systemic and long-lasting monokaryotic mycelium was examined in primary needles of young seedlings with the first symptoms of infection, in the stem of the same seedlings just invaded by the rust and in cortical tissues of infected internodes of older plants. The described ultrastructural features, generally referable to all examined materials, regarded: the wall, capsular sheath and contents of the intercellular hyphae; the haustorial mother cell and the penetration peg; the general morphology, wall, extrahaustorial matrix, collar and encasement of the haustorium; the close proximity to the extrahaustorial membrane of the host cell endoplasmic reticulum and Golgi apparatus. Some aspects ofC. flaccidummonokaryotic haustorium and related structures are discussed and compared to those reported for monokaryotic and dikaryotic haustoria of other rusts.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796935

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

Counting spermatocyte bivalents, we have determined the haploid numbern= 16 forAplysia depilansandA. punctata, andn= 17 forA. limacina.We have confirmedn= 17 forBursatella leachii.Male diakinetic bivalents are probably chiasmatic in all the species examined. The orders Nudibranchia and Notaspidea, possessing haploid values of 13 and 12 chromosomes respectively, seem to be more evolved than the other orders of the sub-class Opisthobranchia.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796936

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

An analysis of the comparative size of chromosomes has been correlated with the chromosome number of Malaysian representatives of 2 genera of the Alydidae and 9 genera of the Coreidae. The results, although restricted in their significance by sample size, nevertheless illustrate the possible causes of karyological changes which have occurred repeatedly in the evolution of the two families.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796937

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796938

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor