Two members of section Pycreus of Cyperus Linn. show variable chromosome numbers as C. globosus n=36, 40, 42, 44 and C. sanguinolentus n=24. Based on x=8 and 9, the former species shows aneuploid numbers at 8- or 10-ploid level. The later species is a hexaploid. C. globosus shows marked infraspecific phenotypic variations amongst various cytotypes yet infraspecific chromosomal categories do not show any phenotypic specificity. Generic status to Pycreus is not supported by cummulative cytological data for Cyperus.
Recently it has been suggested that there is a relationship between fragile sites (FS) in chromosomes and “sister chromatid intercrossing” (SCI). We have analyzed such relationship in a family study of the expression of FS and SCI using TC 199 medium. In a 43.64% of the cases, the observed SCI were located at the same sites of the expressed FS in our sample. The present study supports the suggestion that there could be a relationship between FS and SCI.
Interspecific hybrids between Coix lacryma-jobi (2n=20 and its colchicine induced autotetraploid 4n=40) and C. gigantea (2n=20) were obtained and inter- and intragenomic chromosome homologies were studied. The diploid hybrid between C. lacryma jobi (2n=20) and C. gigantea displayed PMCs with chromosome numbers, 2n=19 and 20 even within the same anther. At meiosis, frequently 10 bivalents, and occasionally a chain each of 4 and 3 chromosomes and upto 2 univalents per cell were found. Two bridges with fragments were found at anaphase I. In the triploid hybrid between C. lacryma-jobi (4n) and C. gigantea (2n), a stable chromosome number of 3n=30 was found. Chromosomes mostly paired as trivalents. Higher associations of 4 chromosomes (not more than one per cell) were also found. The occurrence of bivalents in diploid hybrids and trivalents in triploid hybrids, despite the fact that the C. lacryma-jobi genome is in the duplicated state in the latter, indicates strong homologies between the genomes of the two species. However, the genomic divergence is reflected in the occurrence of univalents and formation of higher associations at prophase I and bridges and fragments at anaphase I, which indicate that the two genomes are separated at least by 2 translocations and 2 inversions. Judging from the basic number of 5 in the genus, the two species are considered tetraploids and it is believed that they arose from a common stock through polyploidy, differentiated subsequently through chromosomal repatterning. The occurrence of intragenomic bivalents in C. gigantea was deduced from chromosome associations in triploid hybrids. This shows that the haploid complement of 10 chromosomes of gigantea (as also lacryma-jobi) has two genomes, each of 5 chromosomes, which have partial homologies between them.
After the aggregation stage of Dictyostelium discoideum, the cell mass is surrounded with the thin surface sheath. There is a difference in opinion in the work by previous authors. According to Gezelius and Rånby (1957) the whole sorus loses the sheath. Raper and Fennell (1952), and Murata and Ohnishi (1980) indicated that only the papilla, or both the papilla and the lower part of the sorus are enveloped, respectively. On the other hand, Watts and Treffry (1976) claim that the whole fruiting body is enclosed in a sheath. In this study, the surface of the pseudoplasmodium, the culminating cell masses and mature fruiting body was examined by means of both SEM and TEM. It was found that the surface sheath is lost as the sorus is rounding out and spores are maturing. At the end of development the sheath remains only on the papilla and not on the basal end of the mature sorus. The possibility of disappearance of the sheath through digestion and engulfment is discussed.
The diploid chromosome number and karyotypes of fifty-two species in 34 genera belonging to 7 sub-families are reported. All the aphid species are collected from the North-western Himalayan region of India. In this study, chromosome records for 21 species are reported for the first time.
Monolayer embryonic pig kidney cells were fused with a modified method by treating cells with 15% dimethyl sulphoxide (DMSO) in serum before and after polyethylene glycol (PEG) treatment. This method produces higher rate of cell fusion than other methods using only PEG or PEG with DMSO. Polykaryons of embryonic pig kidney cells fused by this method showed early mitotic activity soon after fusion (0.5-4 hr) and late mitotic activity after about one generation period of cell cyle (14-20 hr). The early mitotic activity consisted mainly of asynchronic mitoses including premature chromosome condensation and telophaselike nuclei. The late mitotic activity was mostly synchronous, completed with cytokinesis, but quite frequently producing cells with micronuclei. After the first wave of mitotic activity, sharply increased number of polykaryons with picnotic chromatin and after the second wavepolykaryons with picnotic nuclei. These observations indicate that heterophasic condition of fused cells is the cause of pathological mitosis and senescence of nuclei in polykaryons.
Ditelotetrasomic is a plant with a pair of extra homologous telocentric chromosomes in addition to the normal chromosome complement. Ditelotetrasomic 3S in barley is a plant with 2n=14+2 telocentric chromosome 3S. Comparing with their related telotrisomic 3S (2n=14+1 telo 3S) and disomic sibs (2n=14), ditelotetrasomic 3S did not show much qualitative difference in plant morphology; however, quantitative differences were observed in plant morphology: the ditelotetrasomic 3S plants were weaker, slower growing, with fewer tillers and much shorter. Meiotic chromosome behavior was studied from diakinesis through microspore quartet stage. At diakinesis and metaphase I., chromosome configuration were observed with 6II+1IV, 7II, +1 teloII, 6II+1III+l teloI, and 7II+2 teolI. Most of the sporocytes at anaphase and telophase in the first and second meiotic division showed quite normal chromosome behavior. Microspore quartet stage showed mostly normal with some micronuclei. Certain degrees of instability had been observed in the progenies of ditelotetrasomic 3S. The details were discussed.
The study of mitotic and meiotic chromosomes of Leptorhyncoides plagicephalus is reported. The karyotype (2n=7/8) is composed of 1 pair of metacentric, 1 pair of submetacentric 2 pairs of telocentric and a XO XY sex-determining mechanism.
Karyotypes of seven hemiodid fish species have a similar macrostructure, with 2n=54 and FN=108. The chromosome types range from 24 to 25 M-SM chromosome pairs and from 2 to 3 ST chromosome pairs. The species differ in the karyotypic formulae and the NORs are located on a single pair of ST or SM chromosomes. The results are compared with other characiforms, especially those with a similar karyotypic macrostructures, in order to evaluate the possible derivations of the chromosomal patterns of the group.
The phylogeny of 33 owl species is studied karyologically. Karyotypes of seven owl species new to karyology (Bubo lacteus, Ketupa blakistoni, K. ketupa, Otus scops, Strix hylophila, S. leptogrammica and S. nebulosa) are described. Four other karyotypes (Asio otus, Pulsatrix perspicillata, Speotyto cunicularia, and Tyto alba) are presented to complete previous publications.
Chromosomal location of 5S rRNA genes in Vicia faba and Crepis capillaris was investigated by in situ hybridization using probes amplified by the polymerase chain reaction (PCR) using a set of universal primers of parts of 5S rRNA sequence and labeled with biotin. 5S rRNA genes were located at two sites on the satellite of the large metacentric chromosomes in V. faba and were at the short arm of telocentric chromosomes which was very close to the site of large rRNA genes in C. capillaris.
1) Chromosomal survey of a Mysore population (S.W. India) of a tettigonid, Elimaea securigera revealed two karyotypes-Normal and “Variant” karyotypes. 2) All the individuals have in common a diploid number of 27 chromosomes (26AA+X) including a large acrocentric X chromosome. 3) The normal karyotype seen in 30 males consists of all acrocentric chromosomes. The “Variant” karyotype differs from the normal one in showing structural polymorphism in four pairs of chromosomes; one pair with acro/submeta, two pairs with submeta/submeta, and one pair having subacro/subacrocentric chromosomes. 4) The possible mechanism of the evolution of the “Variant” karyotype is discussed.
The chromosomes and interphase nuclei of Genipa americana L. were analyzed after CMA/DAPI staining. Most of the large chromocentres was CMA+/DAPI+, except that associated with the nucleolus which was CMA + + /DAPI - -, whilst the diffuse euchromatin was CMA-/DAPI+. In addition, some small chromocentres were CMA-/DAPI+. The chromosome bands were CMA + /DAPI + or CMA + +/DAPI- -. Most of the chromosome pairs showed size heteromorphism, mainly in the CMA+/DAPI+ bands. Measurements of the heterochromatin/euchromatin ratio in metaphase chromosomes gave an estimate of about 50%, one of the highest ratio observed in angiosperms. Comparison with some other species with a high heterochromatin amount suggest that heterochromatin accumulation may be an aleatory rather than an adaptive process.
The meiotic behaviour of flower buds of Chlorophytum comosum grown under natural conditions without any treatment was evaluated. Many abnormalities such as univalents, laggards, bridges, micronuclei and chromosome stickiness were observed at high frequency. These abnormalities may have contributed to pollen sterility since seed production was highly affected.
Cytology of 11 taxa in three genera belonging to the subtribe Pogostemoninae in Mentheae from South India is studied. The chromosome numbers observed were Pogostemon auricularius 2n=34, P. benghalense 2n=64, P. gardneri n=16, P. heyneanus 2n=34, P. wightii 2n=32 and 64, Eusteralis stellata var. roxburghiana n=14, E. tomentosa var. gracilis 2n=32, and Colebrookea oppositifolia 2n=32. The basic chromosome numbers suggested are x=16 and 17 in Pogostemon, x=14 and 16 in Eusteralis and x=16 for Colebrookea. On the basis of cytological data it is suggested that the whole of Pogostemoninae be included under the subfamily Lamioideae as done by Wunderlich rather than split it and divide the genera among Lamioideae and Nepetoideae as done by Erdtman.
We have recently demonstrated that fetal bovine serum (FBS), at a high concentration, caused cell death in vitro. Bovine plasma also had such an effect (Kurita and Namiki 1993). In the present study, growth stimulating activity and cytotoxicity of several types of sera were compared using TIG-1, human fetal lung fibroblasts. No big differences were observed in terms of growth stimulating activity among bovine, human, equine and swine sera. In regard to cytotoxicity, bovine sera showed the strongest activity and cell death was observed in all the batches of the sera. Human, equine and swine sera were toxically little weaker, and occasionally did not raise the cell death. On the contrary, both mouse and rat sera exhibited quite low growth activity and high cytotoxicity, being hardly applicable for culture media. Although inactivation of the compliment (incubated at 57°C for 30 min) slightly weakened the cytotoxicity, it never disappeared by any further incubation. The tendency was observed in all the cases of sera examined, suggesting the substance that caused cytotoxicity was not the compliment but some other factor(s) resistant to heat.
Four taxa of Japanese Agrimonia were studied cytologically. Chromosome numbers were: n=14, 2n=28 for A. coreana and A. nipponica; n=28, 2n=56 for A. pilosa var. japonica; and 2n=42 for A.×nippono-pilosa. The karyotypes of the four taxa were gradual and symmetric, and are expressed as follows: A. coreana: 2n=28=12m+4tm+12sm; A. nipponica: 2n=28=16m+2tm+6sm+2tsm+2st;A. pilosa var.japonica: 2n=56=42m+12sm+2tsm;A.×nipponopilosa: 2n=42=29m+1tm+9sm+2tsm+1st. The karyotype formula of A.×nippono-pilosa corresponded with half a set of A. nipponica (8m+1tm+3sm+1tsm+1st) and half of A. pilosa var. japonica (21m+6sm+1tsm). Thus, this plant is thought to be F1 hybrid between A. nipponica and A. pilosa var. japonica. In the PMCs of this proposed hybrid, the most frequent kind of chromosome pairing was 14II+14I, which suggests that A. pilosa var. japonica is an allopolyploid which includes the same genome as that of A. nipponica.
We have isolated two flower-specific cDNA clones: clone 12 and clone 3405. Northern hybridization showed that the expression patterns of these genes differed from each other. The expression of transcripts corresponding to clone 12 peaked in 4-6mm buds and was not detected in the open flower, while the expression of transcripts corresponding to clone 3405 peaked in 8-10mm buds and decreased in the open flower. Analyses of the localization of their expression showed that clone 12 is specific to stamens in 10mm buds, while transcripts corresponding to 3405 are expressed in petals and pistils in 10mm buds only in pistils in the open flower. The expression patterns of these transcripts differed from those of previously reported floral homeotic genes.
The fates of mitochondria and mitochondrial nuclei were followed in the “primitive” unicellular red alga Cyanidioschyzon merolae by microscopy and molecular biological techniques. The young mitochondrion contains one mitochondrial nucleus. The number of DNA molecules doubles during the late G2 phase and then returns to the normal value following division. The physical map of the mitochondrial genome was constructed and the size was determined. The genome was a single circle of about 32 kbp. Therefore, the mitochondrial nucleus contains 35 copies of mitochondrial DNA during interphase, which increases to 70 copies in late G2, and then decreases to 35 copies after mitochondrial division.
The karyotype of the “primitive” unicellular red alga Cyanidioschyzon merolae was determined. This cytogenetic study was limited by the absence of mitotic chromosomes which were visible by light microscopy. Therefore, the electrophoretic karyotype of C. merolae was obtained using a pulsed field gel electrophoresis system which uses contour-clamped homogeneous electric fields. The karyotype of C. merolae consisted of 15 chromosomes which ranged in size from 420 kbp to 2050 kbp. The predicted genome size was 12.2 Mbp. This value is larger than the genome size of C. merolae which was previously estimated using a VIM system.