Acrylonitrile (ACN) is an extensively produced industrial chemical used in the synthesis of plastics and fibers. It has been found in car exhaust, cigarette smoke, drinking water and food products. The ability of acrylonitrile to induce sister chromatid exchanges (SCE's) and chromosomal aberrations in male mice was investigated. Three dose levels of acrylonitrile (5, 7.5, 10 mg kg-1b.wt.) were tested (i.p.) for SCE's. The dose 10 mg kg-1b.wt. induced significant increase in the frequency of SCE's 7.2 ±0.2/cell as compared with 4.4±0.26 for control, but the rate of increase was significantly lower than that with mitomycin C 11.9±0.5. Oral treatment with acrylonitrile induced a statistically significant increase in the percentage of chromosomal aberrations in mouse spermatocytes, bone-marrow as well as spleen cells. The aberration frequency increased with the dose and the number of treatments. In all experiments, mitomycin C induced much higher effect. In conclusion acrylonitrile has shown clastogenic potential in the mice examined.
Electrophoretic seed protein profiles, chromosome number and morphological characters of ten species of genus Cassia belonging to two subgenera; Fistula and Senna, are discussed. The phylogenetic relationships between these ten species are also evaluated, based on numerical analysis criterion. According to numerical cluster analysis method the taxa studied are splitting into two groups. Group I (belonging to subgenus Fistula) includes three Cassia spp. (C. fistula, C. javanica and C. nodosa), while C. occidentalis, C. sophera, C. siamea, C. didymobotrya, C. italica, C. senna and C. surattensis are representing group II (belonging to subgenus Senna). The result obtained in this work is reinforced the previous taxonomic treatments of the genus Cassia.
Cytophotometric estimation of 4C DNA content, karyotype analysis and Interphase Nuclear Volume (INV) were carried out in nine species of Ferocactus of the family Cactaceae. Significant interspecific variations in nuclear DNA amount were noted with a constant somatic chromosome number (2n=22). The 4C DNA content varied from 7.66 pg in F. emoryi to 9.74 pg in F. gracilis. The INV varied from 390.36 μm3 in F. pilosus to 564.32 μm3 in F. gracilis. The average chromosome length and volume varied from 2.66 μm in F. emoryi to 2.96 μm in F. gracilis and 1.92 μm3 in F. histrix and 2.77 μm3 in F. gracilis. The mean 4C DNA content showed a significant positive correlation with chromosome length, volume and INV. The structural alterations in the chromosomes as well as loss or addition of highly repetitive sequences in the genome suggest variations in the nuclear DNA at interspecific level during macro-and micro-evolution of the species.
Adult males of Bovicola limbata and B. caprae were cytogenetically analyzed. Both species have n=7, holokinetic chromosomes, and achiasmatic male meiosis. As in other species of Phthiraptera, spermatogenesis follows a particular course with mitotic divisions after meiosis; consequently, cysts of 64 active spermatozoa and 64 non-functional cells (pycnotic nuclei) are encountered. In B. limbata an heteromorphic chromosome pair was observed. The results are compared with previous reports in Phthiraptera. The achiasmatic male meiosis, together with the particular course of spermatogenesis and the low chromosome numbers markedly constrain genetic variability.
Colchitetraploids were synthesized in Cajanus cajan cv. Prabhat and Vigna unguiculata ssp. unguiculata cv. GC 82-7. Tetraploids of C. cajan exhibited reduction in vigour while that of V. unguiculata expressed 'gigantism'. Increase in cell size was observed in both genera. Meiosis was normal in majority of the meiocytes, however, multivalent associations, unequal chromosome distribution, laggards etc. were also observed in some cells. The results suggested involvement of genetic and physiological factors in addition to chromosomal abnormalities for observed high pollen and seed sterility.
The plastid DNA contents of egg, sperm, sporophyte, and gametophyte cells were measured to clarify the relative changes in plastid DNA content during the life cycle of the hornwort Anthoceros punctatus. Samples stained with DAPI were observed using epifluorescence microscopy and CHIAS. The plastid DNA content of unfertilized egg cells did not change before and the fertilization because of preferential digestion of organelle DNA in sperm cells. In the 2n-generation, plastids multiplied by binary fission, with DNA duplication. It is thought that plastid DNA content is halved in spore mother cells, but recovers before, or immediately after, spore germination. In the ngeneration, plastids multiplied by binary fission, with DNA duplication, and the plastid DNA content was maintained at the same level as that of the 2n-generation.
A spontaneous chimeral plant of Rhoeo spathacea is described. A selfed plant GAVA 1.1.19 a sib of desynaptic-SDR, GAVA 1.1 resulted a mixoploid with a diploid chromosome number (2n=12) in root tips. The karyotype is a bimodal one with meta-and submeta-centric chromosomes. Based on chromosome number and meiotic behavior there were identified three types of inflorescences : diploids with PMC's with a ring or a chain of 12 chromosomes at MI, mixoploid flowers presented diploid and tetraploid PMC's in about 4 : 1 ratio, and tetraploid inflorescences with PMC's with as many as 24 univalents at MI. It is proposed a semigamy of a diploid heterokaryon with A and B semigenomes.
The development of sperm formation in the seminal vesicles of Archaeomysis kokuboi Ii (Mysidacea, Gastrosaccinae) is described on the materials collected from the sandy shore at Nesaki-cho Hakodate, Hokkaido from June to November in 1997. The malformed sperms with bifurcate tail were observed liberating from the seminal vesicle of a male obtained in late November. The metaphase nuclei in the seminal vesicles proved to have chromosome number of 2n=40 at mitosis, and n=20 at Meiosis I. Metaphase nuclei at Meiosis I in the seminal vesicles from a male obtained in late November showed usually to have one heterogeneous chromosome which behaves isolately from the others.
We investigated the phenotype of thymic lymphoma induced by fractionated wholebody X-irradiation in DBA1 and NFS mice using mAbs for different cell surface antigens and flow cytometry. The results demonstrated that there was distinct differences in the phenotype of lymphoma between DBA1 and NFS mice, and that the lymphomas developed in NFS mice were more phenotypically mature than those from DBA1 mice.
An extensive NOR variability was described in four Bryconamericus species which are still awaiting more precise taxonomic identification. Nine NOR phenotypes were identified by silver nitrate and mithramycin staining, and cytotaxonomy and phylogenetic relationships were inferred. The wide NOR polymorphism probably related to differences in the number of tandemly repeat ribosomic cistrons and rDNA transcriptional regulation thus far may characterize a particular situation of higher level of NOR phenotype diversification in Bryconamericus than in other neotropical genus fish.
The effect of salinity on the ultrastructure of the chloroplast in the leaf and meristematic cells in the root tips was investigated in three barley genotypes, California Mariout, a salt-tolerant genotype, and two salt-sensitive genotypes, Teo and ICARDA 17. Salinity induced clear changes in the ultrastructure of the chloroplast. The most notable change was disorientated lamellar system with the grana and intergrana lamellae becoming swollen. The chloroplasts of California Mariout were less affected by salinity than those of ICARDA 17. Meristematic cells in the root tips exhibited various degrees of disruption in internal structure : vesiculated plasmalemma, accumulation of lipid droplets, vacuolation of cytoplasm and swelling to a complete damage of mitochondria were observed in the salinity treated plants.
Mitotic chromosome of two cultivars of Colocasia esculenta var. aquatilis and five cultivars of C. esculenta var. esculenta was investigated by the standard aceto-orcein staining method and the fluorescent in situ hybridization with ribosomal DNA probe (rDNA). One cultivar of C. esculenta var. aquatilis and three cultivars of C. esculenta var. esculenta showed the chromosome number of 2n=28, and exhibited an rDNA site on two chromosomes in a mitotic complement. On the other hand, one cultivar of C. esculenta var. aquatilis and two cultivars of C. esculenta var. esculenta showed the chromosome number of 2n=42, and exhibited an rDNA site on three chromosomes in a mitotic complement. These results supported the basic chromosome number of x=14 in C. esculenta.
Chromosomal analysis of an adenocarcinoma of the lung showed three clones. Additionally three cells were also recorded which showed mitotic chromosomal pairing involving varying number of chromosomes. In one of these cells almost the entire genome was involved in mitotic pairing of chromosomes. The importance of somatic pairing of chromosomes in the context of tumor evolution is highlighted.
The chromosomal distribution of constitutive heterochromatin bands (C-bands) investigated in three pomacentrid fishes was highly diversified among the species from simple to complex patterns. Especially, it is remarkable that one species showed various sized C-band blocks appearing not only in centrometric regions but also in interstitial and telomeric regions, as such C-band distribution is unusual in fish. These results reveal that the chromosomes of pomacentrids have evolved by not only structural changes but also quantitative and positional changes of constitutive heterochromatin.
Barley yellow dwarf virus (BYDV) is the most serious viral disease affecting wheat and genes for BYDV resistance have not been found in wheat. BYDV-resistant alien addition and alien substitution lines produced from a wheat × Thinopyrum intermedium (species of Agropyron complex) cross were characterized. Chromosome pairing in the hybrids between two substitution lines showed that they had the same Th. intermedium chromosome. Likewise, two addition lines involved the same alien chromosome. In situ hybridization of chromosomes, confirmed that line P29 is a disomic substitution line. Double monosomic seeds and self-pollinated seeds from monosomic addition plants were irradiated to induce translocations between wheat and Th. intermedium chromosomes. Putative translocations were selected on the basis of BYDV resistance and studied by chromosome analysis, Southern hybridization using Thinopyrum specific probe and RFLP markers. A BYDV-resistant translocation was identified.
The aim of this work was to analyse : a) the phenotypic and cytogenetic differences of Zea mays and Zea perennis hybrids 2n=30 and 40; b) the effect of colchicine on their chromosomes pairing in meiosis. The plant materials used for these studies were Z. mays (Zm20) 2n=20, Z. mays (Zm40) 2n=40 and Z. perennis (Zp) 2n=40 and the hybrids Zm20 ×Zp (MP30) 2n=30 and Zm40 × Zp (MP40) 2n=40. Some characteristics of Z. perennis such as rhizomes, distic ears, perennially and profuse tillering were only observed in MP40 plants. In the other hand, MP30 plants had maize like phenotype; they were annual, with 4 round ears and low tillering. Therefore, phenotypic expression of several traits depends upon the dose of genes from each parent in the hybrid. The genomic formulae proposed for these species and hybrids were Zm20 : AmAm BmBm; Zm40 : AmAmAmAm BmBmBmBm; Zp : ApApApAp Bp1Bp1 Bp2Bp2; MP30 : AmApAp Bp1Bp2 Bm; MP40 : AmAmApAp BmBm Bp1Bp2. Prezigotene colchicine treatment increased the frequency of quadrivalents in Zm20, Zp and Mp40 and trivalents in MP30. These results suggest homoeology between Bm and Bp1Bp2 genomes from maize and Zp, respectively.
Diachasmimorpha longicaudata (Hymenoptera : Braconidae) is a larval endoparasitoid of the fruit fly, Bactrocera correcta (Diptera : Tephritidae) that is important in biological control. We have analysed the metaphase chromosomes of this parasitoid using simple air-drying and squashed air-drying techniques. We examined the karyotypes of reproductive organs of pre-emerged adults and the cerebral ganglia of prepupae. Both show that females are diploid with a chromosome number of (2n) =40, whereas males are haploid with chromosome number of (n) =20. The haploid metaphase karyotype of D. longicaudata comprises 5 metacentric, 13 submetacentric and 2 subtelocentric chromosomes. We could not distinguish the sex chromosomes. These findings are the first record of the metaphase karyotype of this endoparasitoid.