摘要:

The anther development was examined in someCrocus species, by light and scanning electron microscopy. Epidermal cells develop a longitudinal stomium which is connected to the interlocular septum by cells with wide intercellular spaces.Endothecial cells are mono or bilayered, and they develop annular wall thickenings.Middle layer cells degenerate shortly after the microspore release. Tapetal cells are secretory with orbicules, and they form the tapetal membrane. The stomium disjoins from the interlocular septum after the lysis of the middle lamellae in the abscission region. The stomial cells break long before the flower opening, and inC. boryitheyshow signs of programmed cell death. Following the flower opening, the locular walls shrink tangentially, with flattening of epidermal cells and shortening of endothecial cells, and they bend up to turn inside out, exposing the pollen grains. The results are discussed in relation to the dehiscence mechanism.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589203

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Banded karyotypes of two related subspecies ofPetaurista alborufus castaneusfrom southern China andPetaurista alborufus lenafrom Taiwan are presented and compared. Both subspecies had 2n=38 with a fundamental number of FN=72, and shared the gross chromosomal similarity and G-band homology.However, the size of their X chromosomes, C-band patterns and the number and sites of Ag-NORs revealed gross differences. These cytogenetic information suggest that each subspecies developed independently from the common ancestral form. Robertsonian mechanism was absent for their karyotype evolution. With regard to the number of NORs, the P.alborufus lenakaryotype seemed to be primitive. The present findings suggest that P.alborufus lenacould be categorized as a distinct species.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589204

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Chromosomes of the Japanese weaselMustela itatsiendemic to Japanese main islands except Hokkaido were examined by conventional, G-, and C-stainings,and compared with those of the Siberian weaselM. sibiricawhich is widespread ineastern Asia and Siberia. The two species shared the same diploid chromosome number (2n=38). However, their fundamental numbers and G- and C-banding patterns were largely differentiated from each other. Judging from the karyological features as well as mitochondrial DNA data and morphological characters previously reported,M itatsishould be regarde as an independent species fromM. sibirica, in agreement with the first description

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589205

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

New chromosome numbers of seven peanut species, A.cryptopotamicaKrapov. and W.C. Gregory and A.douradianaKrapov. and W.C. Gregory (Sect.Erectoides), A. subcoriacea Krapov. and W.C. Gregory and A chiquitana Krapov.,W.C. Gregory and C.A. Simpson (Sect. Procumbentes), A.cruzianaKrapov., W.C.Gregory and C.A. Simpson, A.HerzogiiKrapov., W.C. Gregory&C.A. Simpson and A.SimpsoniiKrapov. and W.C. Gregory (Sect. Arachis) have been determined,all of them have 2n=20. SAT chromosomes were analysed for all species and a new type of satellited chromosome was described for the genus, which was named 3B for its close resemblance to the first described 3 type. “A” chromosomes were only found in A.Herzogii, A.Simpsoniiand A.chiquitanafrom all the studied species. The last one belong to the section Procumbentes, however, the type of satellited chromosome and the presence of “A” chromosomes in its karyotype suggest that it should be moved from section Procumbentes. The presence of "A" chromosomes proves that it belongs to the section Arachis.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589206

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Physalaemus biligonigerus, P.fuscomaculatusand P. sp. have2n=2chromosomes, consistent with the number of chromosomal pairs found in the genus.There were no substantial differences in the karyotypes of the three species, except for chromosome 3 which was submetacentric in P. fuscomaculatus and metacentric in P.biligonigerusand P. sp.All chromosomes were characterised by the presence of a C-band in the pericentromeric region. Some interstitial bands were also detected at the same position in all karyotypes, but the band located on the short arm of chromosome 3 was larger in P.biligonigerusandP.sp. than in P.fuscomaculatus.Also, only P. sp. had a large block of pericentromeric heterochro-matin in the short arm of chromosome 9 and another one in the telomeric band on the long arm. The NOR was located on the long arm of chromosome 9 in the three species. These findings confirmed that the three species are indeed closely related cytogenetically.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589207

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor