摘要:

486 species of Pteridophyta were examined under trasmission electron microscope to investigate on the occurrence and morphological features of intranuclear proteinaceous inclusions. 315 species proved to contain nuclear inclusions, i.e. 64.81%. 301 out of the Filicophytina examined have proteinaceous nuclear bodies, giving 69.20%. Families which generally display archaic caracters usually lack nuclear proteinaceous inclusions altogether. Among these are: Huperziaceae, Lycopodiaceae and Isoëtaceae in the Lycophytina; Equisetaceae, in the Sphenophytina; Psilotaceae and Tmesipteridaceae in the Psilophytina; Botrychiaceae, Ophioglossaceae, Angiopteridaceae, Osmundaceae, Hymenophyllaceae, Azollaceae and Salviniaceae in the Filicophytina. The genusSelaginellaseems particularly interesting, both because it is the only Lycophytina with nuclear proteinaceous bodies and because the substructure of the inclusions is fibrillar, which so far has proved to be unique in the Pteridophyta. In the Polypodiaceae the absence of intranuclear paracrystals inPlatyceriumagrees with the thesis of CHING (1940) which places this genus in a distinct family, the Platyceriaceae.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797398

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Summarizing the results of our karyological investigation and the data in literature make it possible to speak about a considerable divergence withinScorzoneraL. s.l. Generic independence ofPodospermumDC. andEpilasia(Bunge) Benth. is confirmed by karyological data. The monotypic genusTakhtajanianthaNazarova is singled out into an independent one and the question of the revision of taxonomic rank of the sectionsPulvinares, Nervosae, VierhapperiaandTuberosaeis raised (by LIPSCHIZ system, 1935, 1939). The scheme of phylogenetic links withinScorzoneras.l. at the basis of primary basic chromosome numbers,x= 6 and 7 and secondary basic chromosome numbers,x= 12, 14 (amphiploid origin) is proposed. The role of structural rearrangements in the evolution of taxa is discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797399

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The karyotypes of two stilt bug speciesMetatropis rufescens(Herrich- Schaeffer) ssp.linneaeWagner andBerytinus minor(Herrich-Schaeffer) (Heteroptera, Berytidae) were reinvestigated by an improved method to analyze chromosomes and their meiotic behaviour. The chromosome formula 2n(♂) = 18 + XY forM. rufescensssp.linneaewas confirmed and a novel chromosome formula forB. minor, 2n(♂) = 42 + X1X2X3Y, was given. This is the first finding of multiple sex chromosome system in this family. Male meiosis is chiasmatic for autosomes. Sex chromosomes undergo post-reductional meiosis. C-banding method revealed heterochromatic bands near one of the telomeres in some but not in all chromosomes inM. rufescensssp.linneae.The present data on chromosomes in the family Berytidae are discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797400

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The karyotype ofRoncus gestroiandRoncus belluatiiis reported.Roncus gestroihas a complement 2n= 43–44, having a chromosome system of sex determination of X0 type, andRoncus belluatiihas a complement 2n= 22. The possible relationships with other species of the same genus are analyzed and discussed together with some hypothesis on the general mechanism involved in the karyotypic evolution of the whole group.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797401

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

C-banding technique was applied in some maize materials with the purpose of verifing cytogenetical association between chromosome 2S knob and the presence and expression oflatent-1supergene and also mitotic chromosome characterization. Materials chosen were IP 48-5-3 Cateto Assis Brasil, its isoline IP 48-5-3-lte-1carringlatent-1factor and Michoacan 21-1-104latent-1donnor. C-band number obtained was 3.26 ± 0.69 for IP 48-5-3 Assis Brasil, 7.86±1.57 for IP-48-5-3-lte-1and 8.43 ±1.12 for Michoacan 21-1-104. The mean of total heterochromatin amount values obtained and expressed as percentage were 4.07±0.46; 9.68±1.59 and 13.99±2.05, respectively, C-band was used because of good correspondence between heterochromatic knobs and positive C-bands. IP 48-5-3lte-1isoline and Michoacan 21 showed positive C-band on short arm of chromosome 2 and IP 48-5-3 Assis Brasil did not show any band in the same chromosome.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797402

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Crocuspollen tubes following intra- and interspecific crosses, were removed from the ovary and examined by light and electron microscopy. Compatible pollen tubes (outcross) exhibit the typical organule distribution in the four major regions; in the apical region, globules are joined to plasma membrane and vesicles consisting of an electron translucent core and a homogeneously opaque halo are present. Intra- and interpecific rejections show identical ultrastructural pattern, indicative of a common incompatibility mechanism. The rejection pattern is comparable to that known for species with stylar rejection; some differences concerning wall changes are discussed in therms of a probable relationship between pistil structure and self-incompatibility (SI) mechanisms.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797403

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The karyological analysis of fifty-five voles collected in different localities of Greece showed that they belong to the following cytotypes ofMicrotus (Terricola) thomasi:«thomasi» 2n= 44; FN = 44, «atticus» 2n= 44; FN = 46, «subalpine» 2n= 42; FN = 42 and «Rb-subalpine» 2n= 40; FN = 42. A comparative study of the G-banding patterns among them showed that the first two, differing in a pericentric inversion, both represent the type speciesM. (T.) thomasi.Their distribution is intermingled and extends from central Greece to Peloponissos. The «subalpine» cytotypes distributed in mountainous central Greece, in Mt. South Pindos and in lowland of Ipiros, differ by a Robertsonian centric fusion. They display moreover a tandem fusion, a pericentric inversion and addition of heterochromatin which differentiate them to a greater extend from the type species and may consequently be consider to belong to another taxon of «thomasi» complex. The relatioships among these cytotypes is also descussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797404

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Mitotic chromosome numbers and measurements were determined for fifteen species ofRosa, subgeneraHulthemia, Platyrhodon, Hesperhodos, andRosa(the latter represented by sections Pimpinellifoliae, Carolinae, Cinnamoneae, Synstylae, Banksianae, Chinenses, Caninae, Laevigatae, and Bracteatae). All were 2n= 2x= 14, 2n= 4x= 28, or 2n= 5x= 35, as expected from previously published chromosome counts. Similar chromosomes were matched in pairs by least-squares analysis of chromosome arm lengths. Arm ratio and heterogeneity in chromosome length were used to compare these karyotypes among species, sections, and subgenera. Although the karyotypes were largely symmetric on the basis of both criteria, homogeneity was greater within sections, and a phenogram was obtained on the basis of cluster analysis. The subgeneraHulthemiaandPlatyrhodonrespectively lay near sections Bracteatae and Carolinae in subgenusRosa, but the convergent evolution of these largely symmetric karyotypes has not been critically assessed on the basis of other, especially molecular, characteristics.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797405

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Heterochromatin is known to have contributed greatly in the karyotype variability ofDrosophila kikkawai.Two types of IV chromosome, large acrocentric and medium metacentric, have been encountered in the Indian populations of this species. The frequency of different karyotypes with respect to the IV chromosome was analysed in four Indian populations. The results revealed that there exists a precise genotype-environment interactions.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797406

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Fluorescencein situhybridization (FISH) was used to localize rDNA sites in relation to heterochromatic regions revealed by double chromomycin A3(CMA) and 4′-6-diamidino-2-phenylindole (DAPI) in somatic chromosomes of Meiwa kumquat (Fortunella crassifoliaSwing.). Four sites were observed, all corresponding to CMA positive regions. Two of them were located in the centromeric region of the two chromosomes with three CMA bands (type A chromosome), and the other two, in the long arm's terminal region of the chromosomes with terminal CMA bands on both telomeres (type C). These sites were of different sizes among probable homologous chromosomes, most likely due to a hybrid origin of this accession. The sites located in the type C chromosomes represent a new locus of rRNA genes in these taxa, suggesting that different evolutionary pathways may lead to a similar heterochromatin distribution, and, hence, that chromosomes with the same CMA banding pattern among different species may not always be homoeologous.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797407

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor