C-banding patterns in Japanese grasshoppers belonging to the subfamily Podisminae : Podisma sapporensis Shiraki (2n _??_=23, NF=23), Parapodisma subastris Huang, Parapodisma tenryuensis Kobayashi, Parapodisma yamato Tominaga et Storozhenko, Parapodisma mikado (I. Bolivar), Fruhstorferiola okinawaensis (Shiraki) (2n _??_=21, NF =21), and Sinopodisma punctata Mistshenko (2n _??_ = 21, all chromosomes are two-armed) were studied. Cytogenetic similarities and differences between particular species are discussed using the C-banding method.
Specimens of Edalorhina perezi Jiménez de la Espada from the Brazilian Amazon were studied cytogenetically using Giemsa staining, silver staining and C-banding. The diploid complement of 2n=22 agreed with the chromosome number previously described for Edalorhina sp. Morphologically, the E. perezi karyotype resembled those of Physalaemus and Pleurodema species, but NOR localization and C-banding were unable to detect accurate homologies between E. perezi karyotype and those of the Physalaemus and Pleurodema species studied to date.
More than 300 protein species were identified in the wheat chromosomes by twodimensional gel electrophoresis. Most of the protein species have molecular weight of 12-90 KD, while a few protein species are larger than 100 KD. The chromosome scaffold consists of 70 nonhistone protein species, about 30 species abound in protein content. By comparing the biochemical components of chromosome scaffold and chromosome proteins, we found that most of the protein species in the chromosome scaffold are also existing in the chromosomes, especially 6 protein species that have high molecular weight (about 110 KD, pI was 5.4, 5.6, 5.8, 6.0, 6.3, 6.6, respectively) are very obvious. It was very necessary for further study of the biochemical characteristics and the fundamental roles of these scaffold proteins in the metaphase chromosome structural organization. Our findings demonstrated the existence of nonhistone protein scaffold in metaphase chromosome of wheat, which seems to be similar to the scaffold found in the metaphase chromosomes of humans and animals.
Considering that the production of grains is a characteristic closely related to meiotic behavior, the purpose of the present study was to evaluate some oat cultivars recommended for the southern region of Brazil in order to verify if tose which currently do not display a good performance present meiotic irregularities that might be impairing the production of viable gametes. The most common meiotic abnormalities were those related to the irregular segregation of chromosomes, characterized by the presence of precocious chromosome migration to the poles or laggard chromosomes and of non-oriented bivalents at the equatorial plate. In general, these chromosomes gave rise to micronuclei during telophase that remained until the tetrad stage. Another very common meiotic abnormality in all varieties was the occurrence of multiple bridges in anaphase I and II. Other less common meiotic abnormalities, such as cytomixis, mixoploidy and chromosome stickiness were observed in some varieties. Although meiotic abnormalities can cause pollen sterility, there was no correlation between these abnormalities and sterility. The percentage of sterile pollen grains was much lower than expected. The grains produced by the 12 cultivars ranged from 820 to 2601 kg/ha, showing no correlation with the rate of meiotic abnormalities or pollen fertility. Thus, the results obtained by cytological analysis suggest that the meiotic abnormalities were not the sole factors responsible for the decrease of productivity in the varieties analyzed.
The chromosomes and the karyotype of a female pangolin, Manis crassicaudata collected from Mysore (south Inida) have been described. The karyotype consists of a diploid number of 36 chromosomes. All the autosomes are biarmed except one small and telocentric pair with 7 pairs of large to small metacentric, 6 pairs of submetacentric and 3 pairs of large subtelocentric chromosomes. The X chromosome is a medium sized submetacentric. This study has shown that the pangolins of Varanasi (north India) and Bellary (south India) belong to M. crassicaudata and not M pentadactyla and thus widened the horizon for further karyological studies of pangolins.
The effect of the herbicide 2, 4-D isooctylester 48% (Esteran 48) has been studied on root mitosis of Allium cepa. Root tips of Allium cepa were treated with a series of concentrations, ranging from 50 ppm to 50, 000 ppm for 3, 6, 12, 24 h. Examinations of roots were done in permanent root tip squash preparations stained by the Feulgen technique. Esteran 48 effects the relative duration of each mitotic stage as compared with the control. It also caused reduction in the mitotic index, indicating mitotic inhibition, and increased in the frequency of abnormal mitosis. The type of the abnormalities induced : chromosome stickiness, C-metaphase, tetraploid cells, bridges, laggards, tripolar anaphases-telophases and micronuclei. The effect of Esteran 48 on root mitosis simulates that of colchicine in the type of abnormal metaphase (C-mitosis) and induction of polyploidy cells as well as the accumulation of metaphases
The cell-surface hydrocarbon chains have an important role to characterize cells, however, the information for polyploid cells is little. To assess the expression of sugar chain in cells polyploidized by different mechanisms, the lectin binding was examined. Meth-A cells, a methylcholanthrene-induced mouse abdominal dropsy sarcoma cell line, were polyploidized by demecolcine and K-252a, stained with the FITC labeled lectins, wheat germ agglutinin (WGA), Ricinus cornmunis agglutinin I (RCA120), peanut agglutinin (PNA) and Ulex europeaus agglutinin I (UEA-I), and measured for their fluorescence by flow cytometry. The WGA and UEAI bindings increased proportionally to the area of cell surface, not but to the DNA content. The RCA120 and PNA bindings were significantly larger in K-252a-induced polyploid Meth-A cells than in demecolcine-induced ones. The lectin binding in the diploid cells was almost the same, regardless the presence and the absence of the 2 polyploidizing agents. The lectin binding was roughly proportional to the cell-surface area of polyploidized Meth-A cells and it was affected by the polyploidizing methods.
Cytogenetic studies in 6 species of Apareiodon (Pisces, Parodontidae) from different Brazilian hydrographic basins showed a diploid number equal to 2n=54 chromosomes and the absence of morphologically differentiated sex chromosomes. Although the diploid and the fundamental numbers had been constant, some differences were observed concerning the karyotypic structure of the species. A. ibitiensis, Apareiodon sp. A and Apareiodon sp. B presented 50M/SM+4ST chromosomes, while A. piracicabae, A. vittatus and Apareiodon sp. C presented 52M/SM+2ST ones. Apareiodon piracicabae showed a polymorphism in relation to the number and position of the nucleolar organizer regions (NORs), while A. vittatus showed a variation in the NORs size. The available data indicate that the Parodontidae family have been submitted to a chromosomal diversification during their species differentiation process, despite the maintenance of the same diploid number.
Mitotic segregants for genetic analysis in Aspergillus nidulans depend on the utilization of haploidizing agents such as p-fluorophenylalanine, Benlate and UV UV light is rarely used because of its known mutagenic potential. However, Benlate, a fungicidal drug, has been largely used without evaluation of mutagenicity in eukaryotes. This research shows that Benlate is mutagenic in A. nidulans methG1 strains (biA1 methG1, PAT1). Assays were made by treating quiescent conidia with 0.5 μg/ml Benlate, a commercial product containing 50% Benomyl. Results indicate that Benlate is less safe than 5 s of UV irradiation (26.5 J/m2/s). Consequently the use of this drug for mapping purposes is not recommended.
Analysis of mitotic chromosomes, with special emphasis on the amount and distribution of constitutive heterochromatin, from larval samples of Thai populations of flies in the Bactrocera dorsalis complex has revealed 10 distinctive forms of metaphase karyotypes. This cytological evidence coupled with morphological observations of adults and host relationships with different host plant species have suggested the existence of 10 new cytotaxonomic species provisionally named species Q-Z belonging to the B. dorsalis complex. Metaphase karyotypes of Thai fruit flies were previously classified into 4 groups based on the quantitative differences in pericentric heterochromatin. Metaphase karyotypes of species Q, R, W, X, Y and Z are characterized by the presence of prominent blocks of pericentric heterochromatin in the X chromosomes and autosomes similar to the mitotic patterns found in B. kanchanaburi and B. raiensis. Hence, they are placed in Group 2 of this classification. Species U and V exhibit chromosome X patterns similar to that of B. carambolae and other related species. They are thus assigned to Group 4. In contrast, species S shows a minimum amount of pericentric heterochromatin in all autosomes, although the X chromosome follows the pattern of species Y. Interestingly, species T exhibits a unique pattern of euchromatin and heterochromatin in the X chromosome and conspicuous pericentric heterochromatin in all autosomes. Thus, species S and T are assigned to 2 new categories. Heterochromatin accumulations in the genome, as demonstrated in this study, appear to have played a significant role in chromosomal evolution. The different degree of variation in pericentric heterochromatin in mitotic chromosomes is, therefore, useful for cytotaxonomically distinguishing members of some cryptic species complexes of the dipteran insects.
Polyploidy distribution and variations of karyotypes in Allium grayi Regel were examined in 7 natural populations in Okayama Prefecture, Japan. They showed often tetraploid (2n =32) and pentaploid (2n=40) plants together in the 5 populations and hexaploid (2n=48) plants in the Kasaoka population. The hexaploid plant of the species was found for the first time in western-half part of Japan. Tetraploid plants were solely observed in the Oku population and only pentaploid plants were found in the Kuse population. The analysis revealed the presence of the 2 major different karyotypes : One type consisted of only median- and submedian-centromeric chromosomes and the other type consisted of subterminal-centromeric chromosome (s) in addition to median- and submedian-centromeric chromosomes.
We isolated 2 independent cytokinesis-defective mutants, inc-1 and inc-2, of the unicellular green alga Chlamydomonas reinhardtii through DNA insertional mutagenesis. Characterization of the mutants, using fluorescence microscopy and microfluorometry, revealed that progression of furrowing begins in inc cells after nuclear division. Unlike wild-type cells, however, the cleavage furrow of the dividing cells disappears before cytokinesis. Successive nuclear divisions with incomplete cytokinesis produce multinucleate cells. Additionally, chloroplast autofluorescence revealed that the chloroplast fails to divide throughout the process of cytokinesis in the mutant cells. We also examined the number of chloroplast nucleoids (cp-nucleoids) and chloroplast DNA (cpDNA) content per chloroplast as indicators of cell cycle. We observed cp-nucleoids through DAPI staining and measured the intensity of DAPI fluorescence with a video-intensified microscope photon-counting system (VIMPCS). Both the number of cp-nucleoids and cpDNA content per chloroplast increased under incomplete cytokinesis in inc cells. The inc mutants represent novel cytokinesis-defective mutants of C. reinhardtii.
The transfer of stationary-phase cultured tobacco (Nicotiana tabacum L.) BY-2 cells into auxin-depleted culture medium induces amyloplast formation. To investigate the timing and re-quirement for de novo protein synthesis in organelles during amyloplast development and the enhancement of starch synthesis gene expression, we added chloramphenicol, at various times, to cells grown in amyloplast-inducing medium. Changes in cell growth, starch accumulation, and the mRNA levels of the ADP-glucose pyrophosphorylase small subunit (Agp S) gene were monitored. Chloramphnicol inhibited starch accumulation, but had no significant effect on cell growth, irrespective of the time of addition. RNA gel-blot analyses revealed that chloramphenicol treatment did not reduce the accumulation of mRNA from the AgpS gene, irrespective of addition time. These results suggest that organellar protein synthesis affects starch accumulation independently of starch synthesis gene expression. The necessity of organellar gene expression for starch accumulation is also discussed.
The fluorescent banded somatic karyotypes of Corchorus capsularis, C. olitorius and C. trilocularis showed 14 more or less equal sized metacentric chromosomes each. The orcein stained interphase nuclei revealed the presence of a big nucleolus surrounded by a clear non-staining zone. Moreover, the nucleoli were associated with a pair of prominent dots. All of these characteristics make their interphase nucleus unique. Only 2 CMA-stained satellites were found in the interphase, prophase, prometaphase and metaphase plates of these 3 species. These bands indicate the presence of stable GC-rich sequences at the satellited region of these species. The size of satellites and the length of the satellited chromosomes were found nearly same in these species. Two chromosomes of C. capsularis, however, contained one interstitial CMA-positive band in each. The 2 satellited chromosomes of C. capsularis, C. olitorius and C. trilocularis had 2 DAPI-negative bands at the satellited regions. One interstitial DAPI-positive band was found in C. capsularis. These chromosomes could easily be identified with CMA and DAPI. The base specific banding similarity of their chromosome suggests that their genomes may derive from a common ancestor.