摘要:

Two species ofCryptocoryne, namelyC. ciliataandC. spiralishave been found to have 2n=22 and 90 chromosomes, respectively. The latter species with the highest number of chromosomes in this genus has possibly been derived through allopolyploidy, as evidenced by characteristic meiotic irregularities.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796771

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Pennisetum pedicellatumTrin. has four wild biotypes. The paper deals with the cytomorphological aspect of four such types. Based on morphological characters they have been designated as Types-A, B, C and D, respectively. These types not only differ from each other in minor morphological details but also in their chromosome number (2n=54, 48, 36 and 54, respectively) and behavior giving rise to different races. The taxonomic significance of these races has been discussed. Since the species is a well established apomict and irregular meiosis is not a barrier to seed formation, it has been inferred that the different races are successfully maintained in a polyploid complex.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796772

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Somatic chromosomes from gill epithelia of six species of marine fishes and germinal chrmosomes from testes of two of them have been studied. The diploid complements of all the six species contain 48 gradually seriated chromosomes and thus no size grouping was possible. The karyotypes ofLiza oligolepis, L. macrolepis, Lutjanus kasmiraandSiganus javuscontained only telocentric chromosomes whilescatophagus argusandThysanophrys indicusinclude one and six pairs of biarmed chromosomes respectively in their complement. Interspecific relationship has been discussed and the role of pericentric inversion and/or centromeric shift has been stressed for the origin of karyotypes ofS. argusandT. indicusfrom ancestral primative karyotype. Indication of the presence of a genetic heterogamety in two species ofLizaunder study has been suspected.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796773

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The paper presents data on the karyology of the speciesGl. glaucus, Gl. gripekoveni, Gl. paripes, Gl. caulicolaandGl. barbipes.Tre diploid number 2n=8 was established. The chromosomes of the first, second and third pairs are metacentric and those of the fourth pair acrocentric. The karyological analysis of the speciesGl. gripekoveniandGl. caulicolaas well as their standard maps are presented for the first time. The karyotype evolution of the species is traced and the chromosome aberrations of importance for the divergence of species are noted. On the basis of the data of the comparative karyological analysis it is supposed thatGl. glaucus, Gl. gripekoveni, Gl. paripesandGl. caulicolahave evolved from ancestor and in one direction whileGl. barbipeshas evolved on another direction.Gl. glaucusis considered to be phylogenetically the most ancient. The karyotype evolution of the investigated species has followed two trends: preservation in the chromosome structure of constant features observed in all species on the one hand, change of chromosome structure during the homozygous inversions and appearance of new band patterns of the chromosomes in different species on the other hand. A heterozygous band, the cytological marker of the Y chromosome, was observed in the second chromosome of all malesGl. caulicola.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796774

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The development of ascocarp and the nuclear behaviour during the development of ascus and ascospores was studied inAchaetomiella megaspora(Sörgel) D. Hawksw. The ascocarp initials arise by the coiling of a hyphal branch, the ascogonial coil. The septate, multinucleate ascogonial coil soon becomes invested, forming a spherical ball of pseudoparenchymatous mass, which later on differentiates into a central sporogenous core and wall layers. The asci were developed from typical croziers, produced by the binucleate ascogenous cells. Young ascus undergoes meiosis forming 2 and 4 nucleate stages, followed by a mitotic division which results into an eight nucleate ascus. Cell wall is laid down around each nucleus to form the young ascospores. The ascospores generally have a single nucleus, but sometimes become binucleate due to mitotic division of their nuclei. The haploid chromosome number for this species is 5(n=5).

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796775

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The karyotype ofZ. nasicumis described. It consists of 2n=20 ♂ (XY)-20 ♀ (XX), with a pair of large metacentric autosomes, a metacentric X and an acrocentric Y, the remaining autosomes being acrocentric. Both the metacentric autosomal pair and the XY♂- XX ♀ sex mechanism are present in all the species cytologically examined ofAleuasandZygoclistronexcept an undescribed species ofAleuaswhere the metacentric autosome dissociated into two acrocentric chromosomes. So, an ancient and common origin for both the fusions involved is suggested.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796776

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The lampbrush phase of 6 F1female hybrids ofTriturus cristatus carnifex♀ ×T. vulgaris meridionalis♂ and 1 female hybrid of the reciprocal cross was analyzed in several growing oocytes. The chromosome constitution of these hybrids was found to be diploid and derived from a regular, although heterospecific amphimixis (2n= n♀ + n♂). All the oocytes contained 24 unpaired lampbrush chromosomes, among which the single univalents of the 2 parental sets were recognized by their cytogenetic markers (loops, spheres, NORs, other objects and lateral projections). Lampbrush univalents can be joined to one another by transitional fusions of spheres and telomeres and, occasionally, by very rare chiasmata which may be defined as anomalous since they form between heterologous chromosomes and probably represent a further impediment to subsequent meiotic stages. Problems concerning chromosomal homologies and cytogenetic aspects of sexuality and sex determination in these species hybrids have been discussed in the light of the present findings.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796777

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Male individuals ofAsellus aquaticuswere injected with BrdU and Hoechst 33258; gonad preparations were set up at various time intervals after treatment. Both substances Acted in the first 4h of treatment, outside of S phase, interfering with the normal mitotic and meiotic process of chromosomal condensation. A very slight banding appeared on the mitotic metaphase chromosomes 48 and 65h after treatment; this being the only effect obtained which is likely due to the action of the two substances during S phase.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796778

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The molecular properties of cell surface glycosaminoglycans are considered as well as their interactions with other ‘surface associated’ macromolecules including collagen, actomyosin and fibronectin.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796779

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796780

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor