摘要:

Karyological investigations of two JapaneseNyctalusspecies were made based on G- and C-banding pattern analysis. The karyotype ofN. furvus(2n= 44, FN = 50) was similar to the standard karyotype ofMyotisspecies. On the other hand, the karyotype ofN. lasiopterus aviator(2n= 42, FN = 50) was characterized by having an additional large metacentric pair. By comparison of the G-banding pattern between the twoNyctalusspecies, it is clear that the metacentric pair ofN. lasiopterus aviatorhas derived from the Robertsonian fusion of the two pairs (nos. 8 and 10) ofN. furvus.There was also a significant difference in amount of constitutive heterochromatin between the twoNyctalusspecies. InN. furvusthe additional heterochromatin was observed on the majority of autosomes, while inN. lasiopterus aviatora small C-band was restricted to the centromeric area of each autosome. Thus, the C-band pattern ofN. lasiopterus aviatorwould be interpreted by assuming the decrease of heterochromatin in the course of its speciation fromN. furvus.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796917

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

By treatingSynechococcus elongatusandNostocsp. with NTG, a large spectrum of morphological and pigment mutants have been obtained. The main mutants are those involving long, nonseptate and branched filaments inSynechococcus, ramification, distortion, enlargement of cells, several terminal heterokysts, yellow mutant and lack of necridium differentiation inNostocas well as anastomosis of terminal or intercalary cells inNostoc.Some evolutionary aspect are also discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796918

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796919

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

The karyotypes ofE. impar, E. albipennisandE. tendenshave been compared. The three species exhibit similar external morphology but differ in the number and the morphology of their polytene chromosomes.E. tendenshas 2n= 6,E. albipennisandE. impar—2n= 8. Standard polytene chromosome maps of the three species are reported for the first time and the map markers necessary for species identification listed. Key tables to the larvae have been prepared on the basis of the cytogenetic data. The independence ofE. albipennisis confirmed. However, because of its morphological and karyological similarity withE. imparit is proposed that the two be combined by transferring.E. albipennisto the dispar group. On the basis of the karyotype analyses two forms of the chromosomes complex ofE. tendenswere defined and a dot-like supernumerary chromosome with a mosaic structure was identified. Three additional cytogenetical characteristics were studied (ectopic pairing, inversion polymorphism and C and Q banding). The highest degree of inversion polymorphism present inE. tendens.Using data on the coincidence of several cytogenetic characteristics in one and the same region, maps of heterochromatin localization in the chromosomes of the species studies have been prepared. The differential distribution of C bands in individuals with homo- and heterozygous inversion are discussed in relation to the position effect phenomenon.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796920

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

摘要:

Eleusineis a small genus currently containing 9 species. From cytological analyses of all nine species it is shown thatEleusinecontains three basic chromosome numbers 8, 9 and 10. Among the five diploid taxa the basic number is 8 inE. multiflora(2n= 2x= 16) and 9 inE. floccifolia, E. tristachya, E. indica(all 2n= 2x= 18) and 10 inE. jaegeri(2n= 2x= 20). The 4 tetraploid specicsE. africana, E. coracana, E. reniformis(all 2n= 4x= 36) show a base number of 9, whileE. compressa(2n= 4x= 40) has a base number of 10. From various lines of evidences it is suggested that 9 is the original base chromosome number in the genus. It appears that aneuploid reduction has played a role in the origin of the number 8 found inE. multiflora, while the two taxaE. jaegeri(2n= 2x= 20) andE. compressa(2n= 4x= 40) with ax= 10 number appears to have originated through gain to the basic set of nine. InEleusinethe chromosomes are all small to medium in size. The presumed primitive species,E. floccifoliais characterised by a symmetrical karyotype, while the morphologically more advanced taxa show varying degrees of asymmetry in their chromosome complements. Meiotic analysis of the tetraploid taxa shows regular bivalent formation inE. africana, E. coracana, E. reniformisandE. compressasuggesting their allotetraploid origin. There are grounds for arguing thatE. coracanaoriginated through selection and further cultivation of a large grain mutant fromE. africana, whileE. reniformisappears to be a simple varietal derivative ofE. coracana.

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796921

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1982.10796922

出版商:Taylor & Francis    

年代:1982

数据来源: Taylor