CYTOLOGIA
Online ISSN : 1348-7019
Print ISSN : 0011-4545
Volume 60 , Issue 2
Showing 1-14 articles out of 14 articles from the selected issue
  • P. Wittouck, E. Pinna Senn, C. A. Soñez, M. C. Provensal, J. J. ...
    1995 Volume 60 Issue 2 Pages 93-102
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    A cytogenetical study was performed on several populations assigned to Akodon dolores by external morphology. The specimens from Yacanto (type locality of A. dolores) and the near Villa Dolores, however, showed the karyotype of Akodon molinae, presenting the Robertsonian polymorphism of pair 1 described in this species. In the populations with “dolores” karyotype, most specimens were heterozygous for at least one Robertsonian polymorphism in pairs 1 to 5. A discriminant analysis of craniometric values failed to differentiate between groups with “dolores” or “molinae” karyotype. In the F1 and F2 individuals obtained by crossing specimens from Yacanto or V. Dolores with specimens from Chucul (“dolores” karyotype) all the possible chromosomal constitutions in pairs 1 to 5 were seen. These results favor the possibility that A. molinae represents a chromosomal race of A. dolores. In male Robertsonian heterozygotes for one or more pairs, the corresponding number of trivalent complexes was observed in micro-dispersed pachytene meiocytes; these were characterized by the presence of a short perpendicular segment formed by the pairing of the centromeric ends of the subterminal or terminal chromosomes.
    Download PDF (1889K)
  • G. García, E. Scvortzoff, A. Hernández
    1995 Volume 60 Issue 2 Pages 103-110
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Cytogenetic observations in five species of South American killifishes of the genus Cynolebias reveals chromosome variation at the arm level, but not in diploid number. In this instance pericentric inversions seem to predominate in karyotypic reorganization. Heterochromatin changes may also play an important role in the chromosomal evolution of this genus as evidenced by the presence of large heterochromatic blocks in some of these species. The high karyotypic heterogeneity observed at inter and intraspecific level, confirms the great genome instability detected in this genus.
    Download PDF (1967K)
  • G. O. Williams, B. I. Ogunbiyi
    1995 Volume 60 Issue 2 Pages 111-116
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    The morphology of the chromosomes of the grasshopper, Zonocerus variegatus was studied from mitotic metaphase and meiotic stages in squashed preparations of fresh testicular material. The chromosomes (2n_??_=19) were found to be acrocentric as in most of the Pyrgomorphidae and not metacentric as reported in one study. No meiotic aberrations were detected.
    Download PDF (1483K)
  • M. Wagenvoort
    1995 Volume 60 Issue 2 Pages 117-121
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    A diploid (2n=2x=24) interchange heterozygote of Solanum phureja Juz. et Buk. produced first division restitution-equivalent 2n pollen by abnormal meiosis II spindle orientation. A relative map distance of 31.7 centimorgans was estimated by a half-tetrad analysis for the distance between ym (yellow margin) and the centromere. A similar distance was estimated for the non-interchange situation. These results suggest that crossing over in the interchange heterozygote is not influenced by the presence of the interchange.
    Download PDF (788K)
  • Lan Zhuang Chen, Taiji Adachi
    1995 Volume 60 Issue 2 Pages 123-131
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    The ovules 3-30 days after pollination (DAP) in the interspecific backcross, Lycopersicon esculentum×(L. esculentum×L. peruvianum) {E×(E×P)}, were observed to clarify the process of abortion of postfertilization hybrid embryo (APHE) by using nomarski differential interference contrast optics, and to estimate the optimum timing for the embryo rescue. The critical difference between E×E and E×(E×P) was that the hybrid embryo was usually accompanied with incompletely developed suspensor, remain of large polar nucleus or endosperm deterioration when compared with that of E×E at 7 DAP. About 90% of the hybrid embryos observed, however, continued to divide until the proliferated endothelium filled up the embryo sac cavity at 15 DAP (Fig. 4a, A type). On the other hand, the remains (about 10%) of the hybrid embryos developed in various types after 15 DAP. At 20 DAP, globular-stage embryo with incompletely developed suspensor (Fig. 4b, B type), and at 25 DAP, early globular-stage embryo with collapsed suspensor (Fig. 4c, C type) and a shrivelling embryo and suspensor (Fig. 4d, D type) were observed all in empty embryo sac cavity with different ratios, respectively (Table 1). These observations not only clarify the mechanism of APHE but also provide reliable information for efficient embryo rescue in interspecific hybridization in genus of Lycopersicon. Quantitative analysis of ovule growth in both E×E and E×(E×P) was also discussed.
    Download PDF (2914K)
  • Xue Cai, Yunzhou Dong, Sodmergen
    1995 Volume 60 Issue 2 Pages 133-139
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Dynamics of actin organization and distribution during hydration, activation and germination of pollen in Amaryllis vittata Ait. was examined after TRITC-phalloidin staining. Fresh pollen grains and pollen tubes without fixation were treated and observed in a staining buffer contained dimethylsulphoxide (DMSO) as a permeabilising agent. Among the mature pollen grains, two organizational patterns of actin were confirmed in the cytoplasm of the vegetative cell. Those were fusiform bodies or a network constructed by filamentous fibres. Five min after incubation in a germination medium, the hydrated pollen grains appeared in various sizes representing the different degrees of hydration. In the larger-sized pollen grains, actin filaments confined to one end of the germ furrow. While in the smaller-sized pollen grains, actin appeared as needle-like bodies together with filamentous fibres. The results proved that the figuration of actin changed from fusiform bodies to a network of fibres accompanied the progress of hydration. The pollen grains activated 10-20 min after incubation. Actin in the vegetative cells of the activated pollen grains became highly polarized. After 30-40 min of incubation, the pollen grains began to germinate. Actin was observed in the protruding region (s). During pollen tube growing, actin filaments were transfered to the pollen tube and reached the tip. Actin in the ungerminated pollen grains remained in the storage form, which was very similar to that in the mature pollen grains. Cytochalasin D inhibited pollen germination. These results showed that the developmental and physiological states of the pollen cells could be different and be directly reflected by the organization patterns of actin.
    Download PDF (1292K)
  • Katsuhiko Kondo, Goro Kokubugata, Masahiro Hizume, Ryuso Tanaka, Toshi ...
    1995 Volume 60 Issue 2 Pages 141-147
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    The chromosomes of five species and one variety of Cycas studied showed commonly the morphological characteristics of the complex chromocenter type at early interphase and the interstitial type at mitotic prophase. All of the taxa had the common chromosome number of 2n=22 and very similar karyotypes to each other; C. media var. basaltica and C. siamensis showed the chromosome number of 2n=22 for the first time.
    Download PDF (1347K)
  • Makoto Fujie, Haruko Kuroiwa, Shigeyuki Kawano, Tsuneyoshi Kuroiwa
    1995 Volume 60 Issue 2 Pages 149-158
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Changes in cytoplasmic rRNA density during cell differentiation were studied in the root tip of Lactuca sativa L. and Arabidopsis thaliana (L)., especially near the quiescent centre (QC). The density in cytoplasm was investigated semi-quantitatively by a new in situ hybridization method which provides very high resolution to study cell specific gene expression. Samples were embedded in Technovit 7100 resin, cut into thin sections, and hybridized with a digoxigenin-labelled probe. The hybridized probe was detected by indirect immunofluorescence microscopy using anti-digoxigenin antibody. The fluorescence intensity in each cell was measured using microphotometry. The intensity in the QC was less than that in the surrounding meristematic cells. The density of rRNA was relatively higher in the meristematic cells, and declined in the differentiated cells of the elongation zone and root cap as the distance from the QC increased. The density of cytoplasmic rRNA in the elongation zone was five fold lower than that in the active meristem in root of Arabidopsis. This suggests that the density of cytoplasmic rRNA is closely related to mitotic activity. This method also enabled to observe the subcellular localization of rRNA with a light microscope. The rRNA level of organelles was also observed in the root apical meristem. The organelles in the root tip contain large amounts of DNA, but the rRNA level in the organelles was low.
    Download PDF (2044K)
  • M. I. Arrieta, B. Martínez, M. Nuñez, A. Gil, A. Echarri ...
    1995 Volume 60 Issue 2 Pages 159-165
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Cells with an abnormal centromere behaviour called premature centromere division (PCD) were observed in a cytogenetic study on the incidence of fragile sites and other chromosomal anomalies in seven autistic children and in two children from a sample control, all of them from the Basque Country.
    The phenomenon affects all the chromosomes of a cell and folic acid deficiency is the most influential factor.
    Download PDF (1329K)
  • Ashok Kumar Giri, Kaleem Ahmed Khan
    1995 Volume 60 Issue 2 Pages 167-172
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Centchroman (3, 4-trans-2, 2-dimethyl-3-phenyl-4p (β-pyrrolidinoethoxy phenyl)-7-methoxy chroman), a non-steroidal oral contraceptive has been developed by the Central Drug Research Institute, Lucknow India. Sister chromatid exchange (SE) and chromosome aberrations (CA) was carried out after in vivo exposure of centchroman in bone marrow cells of female mice. No significant changes of either SCE or CA were observed when the treated groups were compared with solvent controls. Trend tests for the evidence of dose response effects were also insignificant. This indicate that centchroman was not genotoxic in bone marrow cells of mice.
    Download PDF (752K)
  • Huai-Jun Li, Sodmergen
    1995 Volume 60 Issue 2 Pages 173-181
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Cytoplasmic DNAs of male reproductive cells were examined during the pollen development of Zea mays and Triticale using fluorescence microscopy after staining with DAPI (4', 6-diamidino-2-phenylindole). Nucleolytic activities in mature pollen of Zea mays, Triticale and Triticum aestivum were analysed on SDS-DNA-gels after electrophoresis. Cytoplasmic DNAs were observed in the generative cells both in Z. mays and Triticale. However, a gradual degradation occurred later. In Z. mays, organelle nuclei (nucleoids) were undetectable in young sperm cells. In Triticale, quite a few organelle nuclei remained in the young sperm cells but completely disappeared during the maturation of sperm cells. Nuclease assay showed that two Mg2+-dependent and two Mn2+-dependent nucleases were specifically associated with the pollen protein of Z. mays and, one Mn2+-dependent nuclease was specifically associated with the pollen protein of Triticale. In T, aestivum, where the disappearance of organelle nuclei during maturation of sperm cells had been reported, two Ca2+-dependent nucleases were specifically detected in the pollen protein. These results suggest that a preferential degradation of organelle nuclei would occur in the generative and sperm cells which may result in the absence of cytoplasmic DNAs in the mature sperm cells. This preferential degradation of cytoplasmic DNA may be the root cause of maternal cytoplasmic inheritance and the pollen-specific nucleases could be responsible for the degradation.
    Download PDF (2248K)
  • Kyoko Toda, Hidenori Takahashi, Ryuuichi Itoh, Tsuneyoshi Kuroiwa
    1995 Volume 60 Issue 2 Pages 183-188
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    The DNA contents in the cell nuclei of the Cyanidiophyceae C. merolae and C. caldarium Forma A were estimated using VIMPCS after staining with DAPI, Schiff's reagent or PI. For C. merolae, the obtained data were compared with those of PFGE. The results indicated that the genome sizes of C. merolae and C. caldarium Forma A were approximately 13 Mbp and 35 Mbp, respectively. Since the values obtained by PFGE were very close to those estimated from Feulgen staining, Schiff's reagent, which binds to purine residues and is not affected by GC content, is considered to be the most reliable of these three reagents for estimating DNA contents.
    Download PDF (1190K)
  • K. S. Awasthy, O. P. Chaurasia, S. P. Sinha
    1995 Volume 60 Issue 2 Pages 189-193
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    Oral administration for one week of 0.5, 1.0 or 2.0g/kg body weight/day of crude leaf extract of neem (Azadirachta indica) to laboratory inbred albino Swiss-mice induced both individual and gross types of mitotic chromosome abnormalities in the bone marrow cells. The frequency of total abnormalities was dose-dependent. Gross type abnormalities appeared even at the lowest dose and remained unchanged in their frequency at the higher doses; the individual type abnormalities were induced only at the highest dose.
    Download PDF (871K)
  • M. L. H. Kaul, Jaswinder Kaur
    1995 Volume 60 Issue 2 Pages 195-203
    Published: June 25, 1995
    Released: March 19, 2009
    JOURNAL FREE ACCESS
    In addition to normal bivalency (15%), the PMCs of the four head types (white and yellow radiate and ligulate) of Chrysanthemum coronarium (crown daisy) exhibit bivalent interlocks (55%), translocation rings (15%) and telomere adhesions (9%). But only one of these three anomalies, never all the three, occur in the PMC of each head type. Despite these prophase I anomalies, the subsequent meiosis from metaphase I to its completion is normal in all the four head types; the gametic- and seed-fertility are high (95%). Why do these anomalies occur, why are these retained from generation to generation and how their interference in meiotic course is prevented remain cytogenetic puzzles.
    Download PDF (1586K)
feedback
Top