摘要:

A population ofOphioglossum reticulatumL. growing in an area of c. 1500 sq. metres in Darbhanga (N. Bihar), India exhibited marked morphological differences. Sampling of the morphological variants led to the delimitation of five groups in the population. Of this, three were confined to moist shady place and the other two to open dry condition. Meiotic investigations carried out in these groups revealed differences in chromosome numbers which indicated different ploidy levels. The lowest number of 112–114 bivalents and 8–12 univalents has been encountered in one group and constitutes the first report of a diploid count from this country. Other numbers counted were 194–200 bivalents, 375–380 bivalents and 632–640 bivalents with 6–12 univalents in each. The univalents may represent fragments. Polyploidy has been suggested to be the dominant genetic theme in homosporous pteriodophytes. Storage and release of genetic variability through polyploidy may have provided evolutionary adaptability to this genus, known for its ancient history and high number of chromosomes.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796781

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

In this study, changes in the distribution of polysaccharides and lipids and stainability of ABB and AB during the embryo sac development in the tetraploid and octoploid ofPaspalum longifoliumwere examined in the glutaraldehyde-fixed, Epon-embedded ovary sections. Starch grains and lipid granules accumulate most abundantly in the ovary wall. They also accumulate in a considerable amount in the embryo sac. The stainability of ABB in different tissue cells are parallel to that of AB except that of the nuclear saps in the nuclei of the embryo sac. Deoxyribonucleic acid in the nuclei of the developing and mature embryo sac, except those of mature antipodals, are hardly stainable with AB and Feulgen reagent. Antipodals may be metabolically very active in transporting nutrients into the embryo sac through the intimate connection between these cells and the nucellus and papillae on the inner surface of antipodal wall adjacent to nucellar cells. They also contain a large amount of starch grains and lipids in liquid state. Both the central cell and egg are higly vacuolated and contain a considerable amount of starch grains and lipid droplets. Filiform apparatus of the two synergids develops from the micropylar wall between these two cells as well as from the micropylar wall adjacent to the region believed to be the degenerated megaspore (s) and is composed mainly of polysaccharides. These polysaccharides seem to have been transformed from starch grains stored in the synergids at an early stage. The cytoplasm around each filiform apparatus stains rather intensely with ABB and AB. Many lipid granules are also present around this apparatus. The nucellar cells below the embryo sac, micropylar integumentary cells, cells in the ovule attachment region (OAR), and cells of the cell strand connecting the OAR and ovary base are all much less vacuolated and rich in cytoplasm. They form a connection from the base of the ovary to the micropylar end of the embryo sac, probably for the translocation of nutrients into the embryo sac. No significant difference in the distribution and concentration of polysaccharides and lipids during embryo sac development in the ovaries of the tetraploid and octoploid was observed, except starch grains and lipid granules, both of which are larger and more numerous in the latter than in the former.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796782

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Somatic chromosomes from the kidneys of both sexes ofAplocheilus panchax(Cyprinodontidae), of maleLates calcerifer(Percidae) and germinal chromosomes from the testes ofA. panchaxandGadusia chapra(Clupeidae) are described. In both sexes ofA. panchax, the somatic complements consist of 38 chromosomes, measuring between 2.6 and 1.1 μm in male and 2.7 and 1.1 μm in female. The male karyotype comprises 7 pairs of metacentric, 4 pairs of submetacentric, 2 pairs of subtelocentric and 6 pairs of telocentric chromosomes. The female karyotype differs in having one fairly large submetacentric more and small metacentric less than the male karyotype indicating thereby female heterogamety (ZW) in this species. The spermatocytic metaphase I contained 19 apparently homomorphic bivalents.L. calcerifercontains 2n=48 chromosomes which can be aligned into 24 homomorphic pairs comprising 1 pair of metacentric, 3 pairs of submetacentric, 1 pair of subtelocentric and 19 pairs of telocentric chromosomes. The chromosomes range between 2.4 and 0.9 μm in length.G. chaprahas in its spermatogonial metaphases 2n=46 rods measuring between 2.3 and 1.0 μm. 23 homomorphic bivalents with terminalized chiasmata are found in primary spermatocytic metaphases. Sex elements are not recognizable in males ofL. calceriferandG. chapra.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796783

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The root growth rate of alloplasmic rye (Secale cerealeL. nucleus andTriticum durumDesf. cytoplasm) is approximately 30% lower than that of non-alloplasmic rye. To summarise, we can make the following concluding observations: i) Both normal and alloplasmic rye fit equilibrium kinetics; ii) the mitotic and phase indices are similar in both materials, and are also constant for roots with a length of between 10 to 60 mm.; iii) the cycle duration is sligtly shorter in CAL than in Elbon; iv) the final length of CAL cell is also slightly shorter than the Elbon ones; and v) the number of meristematic cells is notably lower in Cal than in Elbon. This might be the main cause for the lesser growth of alloplasmic plants.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796784

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

A detailed karyological analysis ofA. sapidus(2n=40) andA. terrestris(2n=36) from the Iberian Peninsula is made in this report. Comparative study of the karyotypes of both species is carried out. The differences in chromosome number and chromosome morphology between them are explained in terms of centric fusions. The hypothesis of fusions is confirmed by means of G-banding technique.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796785

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Quinacrine-bright bands of polytene chromosomes have been localized in the members of the virilis group. Four species:Drosophila virilis, D. lummei, D. flavomontanaandD. ovivororumhave Q-bands of varying intensities.D. virilis, the most karyotypically primitive member of the group, has a Q-band doublet in the heterochromatin of chromosome four. This doublet is not found in any of the other members of the group. One species,D. flavomontana, is polymorphic for a Q-band in the Yi-j region of chromosome four. With the exception ofD. ezoana, chromocentric quinacrine-bright granules are a unifying feature of all the members of the virilis group.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796786

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The triploidRhoeo spatacea(X=6) exhibited random distribution of the chromosomes at anaphase I, and the number of chromosomes in the gametes will range from monoploid to diploid, i.e. from 6 to 12. Among 89 pollen mother cells (PMC) without laggards, 4 (4,49%) had 6–12 distribution, 11 (12,36%) had 7–11, 44 (49.44%) ah 8–10 distribution which was most frequently observed, and 30 (33.71%) had 9–9 distribution.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796787

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The idiogram of the domestic horse is established by measuring 20 cells (10 male and 10 female cells) derived from 10 horses. A practical classification of the karyotype according to size and morphology of the chromosomes is proposed.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796788

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

Teliospores ofMelampsora pinitorquaRostr. were collected in the formation, overwintering and germination stages and observed by transmission electron microscope. Some information about their general ultrastructure is given, particularly concerning the cell wall, lipid bodies, mitochondria, ER, cytoplasmic vesicles, vacuoles, unidentified membrane formations, nucleus and germ tube wall. Some organelle changes occurring from the maturation to germination stage were observed.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796789

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor

摘要:

The authors have cultivatedin vitromicrosporangia ofEncephalartos altensteiniiLehm, observing the microgametophytes up to spermatogenesis.

ISSN:0008-7114    

DOI:10.1080/00087114.1979.10796790

出版商:Taylor & Francis    

年代:1979

数据来源: Taylor