摘要:

Potassium permanganate fixed conidia and hyphae ofNeurospora crassawere studied with the electron microscope. The cell wall comprises an outer friable electrondense portion and an inner electron-light region where the fibers seem to be longitudinally oriented. The endoplasmic reticulum is sparse and discontinuous in the conidium but a well developed lamellar system is present in the mycelium; in some instances the ends of the reticulum enlarge to form vesicles. Rounded nuclei are observed both in the hyphae and the conidia, but in the former elongated nuclei also occur. In one case, migrating elongated nuclei in the hyphae are seen to squeeze through a septal pore. In properly fixed material, nucleoplasm is differentiated to electron-dense and electron-light areas. Well defined nuclear envelopes, nuclear pores and continuities between endoplasmic reticulum and nuclear envelopes also are observed. Mitochondria show variations in form, size and structure. Some of the mitochondria eventually give rise to small vacuoles by the disintegration of cristae. These findings are discussed in the light of related reports in the literature.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796210

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

The present study on the chromosome cytology of two species of Diplopoda which are commonly called pill-millipedes, is a continuation of a similar study for the group (CHOWDAIAH 1965). They present two diploid chromosome numbers of 26 and 30, and the highest chromosome number (2n = 30) is recorded for the group. In the species studied, all the chromosomes are acrocentric. The sex-chromosome mechanism is of the XY type. The sex bivalent (XY) is the largest pair in the complement. An attempt has been made to gain some evidence on the probable numerical relationship of the various Karyotypes and their role in the evolution of the group as a whole.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796211

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

An idea of the distributional pattern of this complex has been obtained by pooling together of the information gathered from floras, herbarium specimens, living plants raised from seed obtained from various sources and analysis of living populations.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796212

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

1.The report on the chromosome number n = 13 and 2n = 26 inGaruga pinnatawas first determined by the author in 1961.2.In the present communication, karyotype analysis of the species has been worked out in detail and probably this is the first exploration of the karyotype of the member in the family Burseraceac.3.Six distinguishable types of chromosomes have been revealed during karyological analysis of the species.4.Of the 13 pairs of chromosomes, 8 pairs are medianly constricted and 5 pairs having subterminal centromeres of which one pair of chromosomes is long and secondarily constricted.5.On the basis of karyotype analysis, an interpretation of the phylogeny of the taxon has been attempted.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796213

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

In apici radicali diArisarum proboscideum(L.) Savi (Araceae), prelevati direttamente da esemplari di una stazione presso Reggello (Valdarno superiore), è stato trovato un numero cromosomico 2n = 28. Tutti i cromosomi sono eterobrachiali, con centromero submediano; una coppia appare satellitata. Questi dati risultano essere i primi Sulla cariologia del genereArisarum.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796214

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

One of the seeds of a variety ofC. arietinumwith green seed coats was observed to have three SAT-chromosomes at meta- and ana- phases. It is shown to be a triploid with 24 chromosomes.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796215

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

1.Karyological investigations of some twenty-four species in theLolium-Festucagroup were made as a preliminary to meiotic studies of selected species and hybrids. Comparative studies were made on relative length and arm ratio of all the chromosomes in the various species. The chromosomes with secondary constrictions were classified into sixteen types and designated as A.B,C,……J.2.In theLoliumspecies, which were all diploid, three inbreeding species,L. temulentum, L. remotum, L. loliaceumand four outbreeding species,L. multiflorum, L. westerwoldicum, L. rigidumandL. perennewere studied.(a)These studies confirmed that the basic karyotype was similar in the two groups and all the species had three pairs of satellited chromosomes. However, the two groups could be differentiated clearly on the basis of a difference in the position of the secondary constriction in chromosome 1.(b)Significant differences in relative chromosome length and arm ratio between corresponding chromosomes of different species were found.(c)There appeared to be more variability among the outbreeding species in respect of the various chromosome characters than in the inbreeding species.(d)It is concluded that many chromosome rearrangements have occurred in the differentiation of the various species but gene mutations must also have been involved.3.InFestucaseventeen species and six populations of tall fescue belonging to the sectionsOvinae, Bovinae, Scariosae, Montanae, Sub-bulbosaeandVariaewere studied.(a)All the diploid species differed in their karyotypes both with respect to relative length and arm ratio and the satellited chromosomes were distinct in the different species.(b)Karyotypes ofF. arundinaceavar.glaucescens(2n = 28) indicated similarities of some of its satellited chromosomes with those ofF. pratensis(2n = 14) andF. Mairei(2n = 28). In addition, similarities were also discerned betweenglaucescensand two other forms ofF. arundinacea(2n = 42,70). This indicated the phylogenetic relationship of these forms.(c)The tetraploid form ofF. spadiceaincluded some of the satellited chromosomes of its diploid form. Similar relationships were found between satellited chromosomes of the hexaploid forms ofF. amplaandF. rubrawith their octoploid forms respectively.4.Special attention was given to the karyotypic analysis of one indigenous and six exotic populations ofF. arundinacea(2n = 42). There was positive evidence of chromosomal differentiation between the populations.(a)The indigenous population had four satellited pairs whereas introduced ones had five to eight pairs. In addition diversity with regard to the size and shape of the satellites of different populations were also found. This variation was also observed with regard to arm ratio and relative length.(b)Chromosomal repatterning as a result of segmental inter-change, inversion and deletion must have played some significant role in the differentiation of tall fescue.5.Such karyotypic variations were also found in other species includingF. Mairei, glaucescens, arundinacea(2n = 70). Apparently chromosomal repatterning is well spread and possibly perpetuated by vegetative reproduction.6.The following general conclusions were also drawn:(a)The separate status accorded to the two generaLolium-Festucais supported.(b)In the evolutionary process there was no change in the basic chromosome number for the species in this group and there was evidence to support the view that the two genera had a common origin. Compared with the diploids the polyploids were of relatively recent origin.(c)From a study of chromosome asymmetry in the different species it was possible to evaluate the evolutionary trends in the genusFestucaand to show the significant part played by polyploidy in speciation.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796216

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

Among the several aspects investigated in the programme of studies on induced mutagenesis inTriticum durum, cytological analysis of mutant progenies has been particularly taken into consideration. Data obtained from microsporogenesis, pollen fertility and seed setting analysis of heterozygotes for reciprocal translocations, allowed a general appraising on the relation of translocation heterozygosis to gametic fertility.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796217

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor

摘要:

The chromosome complements of the somatic cells ofMustela putorius, Mustela nivalisandMeles melesare described.

ISSN:0008-7114    

DOI:10.1080/00087114.1966.10796218

出版商:Taylor & Francis    

年代:1966

数据来源: Taylor