Showing papers in "Cytologia in 1988"
TL;DR: Further cytological study of Colocasia taro in the Pacific utilizing karyotypic data has produced a hypothesis for two separate lineages of the plant within contemporary populations, providing support for domestication in the western Pacific independent of diffusion of Asian cultigen forms.
Abstract: Further cytological study of Colocasia taro in the Pacific utilizing karyotypic data has produced a hypothesis for two separate lineages of the plant within contemporary populations. This provides support for domestication in the western Pacific independent of diffusion of Asian cultigen forms, but it is indicated that confirmation awaits more comprehensive karyotyping of Indian and Southeast Asian material.
80 citations
75 citations
TL;DR: It was found that not only the frequency of cytomixis but the amount of chromatin transferred reduced with the advancement of meiosis, which seems to have contributed towards the pollen sterility.
Abstract: Cytomixis was recorded during microsporogenesis in Papaver dubium L, a member of the family Papaveraceae The phenomenon was observed in all the stages of meiosis Further, it was found that not only the frequency of cytomixis but the amount of chromatin transferred reduced with the advancement of meiosis The pollen fertility was found to be affected by this phenomenon and it seems that some other factors like precocious separation and irregular distribution of chromosomes might have also contributed towards the pollen sterility A few large sized cells containing double or more than double chromatin and cells with increased or decreased chromosome number were observed The possible role of cytomixis in the production of aneuploids as well as polyploids is suggested
49 citations
TL;DR: The present author observed various types of intraspecific structural and numerical chromosomal changes of the karyotype involving some mutant chromosomes such as M', T', m and a (Kurita 1987a, 1987b, 1987c, 1988c).
Abstract: As to the trend of karyotype evolution in Lycoris, Inariyama (1951a, 1951b) proposed a fusion hypothesis. He considered that the various karyotypes of fertile diploid species of this genus must have had their origin in the karyotype of L. sanguinea composed of twenty-two I-shaped (acrocentric sensu lato) chromosomes alone, and the most advanced karyotype of L. aurea composed of ten V-shaped (meta or submetacentric) chromosomes and two I-shaped chromosomes were derived from the former by successive fusions of any two I-shaped chromo somes. While he considered that the karyotypes of sterile species such as L. albiflora, L. squamigera and L. radiata were produced by hybridization and/or polyploidization. Nmaely, in his opinion, the basic chromosome number of Lycoris is not x=6, the lowest haploid num ber in the genus, but x=11. Recently, Jones (1978) and Nishikawa et al. (1979) supported Inariyama's hypothesis. On the other hand, however, Darlington (1963) and Flory (1977) considered that I-shaped chromosomes must have been originated from the fission through the centromeric region of V-shaped chromosomes in this genus. Instead of I-shaped and V-shaped chromosomes, the present author recognized three major types of chromosome, M, T and A (1986). Moreover he observed various types of intraspecific structural and numerical chromosomal changes of the karyotype involving some mutant chromosomes such as M', T', m and a (Kurita 1987a, 1987b, 1987c, 1988c). In this
25 citations
24 citations
TL;DR: The chromosome pairing in some species hybrids showed that species genomes in the genus Leucaena were very similar cytologically and polyploidy has played a very important role in the evolution of the genus.
Abstract: In twelve Leucaena taxa examined, the chromosome numbers were found to be n=26, 28 and 52. Six species and one subspecies have n=26, two species n=28 and three species n=52. Chromosome numbers in L. collinsii Britton and Rose (n=26), L. diversifolia (Schlecht.) Benth. ssp. diversifolia Pan et Brewbaker (n=52), L. pallida Britton and Rose (n=52) and L. retusa Benth. (n=28) were reported for the first time. The meiosis was regular in all the diploids and in most tetraploids. Multivalents were found in some tetraploids. The chromosome pairing in some species hybrids showed that species genomes in the genus Leucaena were very similar cytologically. Besides geographical and ecological isolation, polyploidy has played a very important role in the evolution of the genus.
22 citations
TL;DR: Cytogenetical studies in Vigna glaberscens TTK1 revealed twenty two and fourty four as haploid and diploid chromosome numbers respectively.
Abstract: Cytogenetical studies in Vigna glaberscens TTK1 revealed twenty two and fourty four as haploid and diploid chromosome numbers respectively. Spontaneous occurrence of cytomixis is due to the transfer of chromatin material from one pollen mother cell to other through connecting channel has been noted. Pollen mother cells with reduced chromosome number (n=6, n=7) higher than the modal number (n=22) have also been recorded. Grouping of bivalents and late separating chromosomes were some of the noted abnormalities.
22 citations
TL;DR: The genotoxic effects of three organophosphorus pesticides employing in vivo chromosomal aberration bioassay in root meristems of Allium and Hordeum have been investigated and the order of radiomimetic potential was found to be phorate>fenitrothion>ekatin.
Abstract: The genotoxic effects of three organophosphorus pesticides viz. ekatin, fenitrothion, phorate and MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) employing in vivo chromosomal aberration bioassay in root meristems of Allium and Hordeum have been investigated. Both physiological type aberrations like C-mitosis, despiralization, lagging chromosomes, multipolar cells as well as clastogenic effects like chromosome breaks, ring chromosome, chromatin bridges and micronuclei were induced by these pesticides. The order of radiomimetic potential was found to be phorate>fenitrothion>ekatin. The root meristem of Allium cepa was found to be more sensitive.
21 citations
TL;DR: Dithane was more effective in inhibting mitosis, whereas denmart produced higher amount of chromosomal abnormalities than dithane, and the significance of the cytogenetic effects of both fungicides is discussed.
Abstract: The effect of 4 concentrations containing 4, 20, 100 and 500 ppm a.i. of the two fungicides dithane and denmart applied for 4 and 24 h. on mitotic activity and chromosomes in root meristems of Allium cepa has been investigated. Both compounds inhibited mitosis and resulted in the accumulation of metaphase configurations. High concentrations of dithane gave rise to lower prophase frequency, whereas those of denmart reduced the frequency of both anaphase and telophase. Both compounds exerted a weak C-mitotic activity, but induced chromosomal stickiness, breaks and bridges in a considerable proportion of dividing cells. Denmart also induced chromosome lagging, binucleated and multinucleated cells and micronuclei. In general dithane was more effective in inhibting mitosis, whereas denmart produced higher amount of chromosomal abnormalities than dithane. The significance of the cytogenetic effects of both fungicides is discussed.
21 citations
TL;DR: Though the frequency is low, various intraspecific and intercellular chromosome rearrangements were observed in the diploid.
Abstract: Intraspecific variation of the karyotype of L. sanguinea var. kiushiana and L. sanguinea var. koreana was studied. Almost all plants of both taxa examined were diploid having 2n=22, but three triploid bulbs (2n=33) and one tetraploid bulb (2n=44) were found in L. s. var. kiushiana from the Taradake population. The absolute arm length, relative length, and r value of each chromosome of the representative karyotype of these taxa have been summarized in Tables. The standard karyotype of diploid plants consists of twenty-two A type chromosomes of which two are satellite chromosomes.Though the frequency is low, various intraspecific and intercellular chromosome rearrangements were observed in the diploid. They are as follows: 1. Some subtelocentric chromosomes and T' type chromosomes were observed. They must have originated from the standard A type chromsomes by means of deficiency or pericentric inversion. 2. The m type chromosome was found in some cells of L. s. var. koreana. It must have originated from the A by means of a break at the proximal region of the long arm. 3. A few instances of heterozygous combination of satellite chromosomes were observed.
20 citations
TL;DR: Cytomixis has been observed in the pollen mother cells of Leucas aspera, two species of Mentha and two populations of Leonurus sibiricus, and the probable correlation between the aneuploid gamete production, pollen sterility and the cytomictic connections in all the investigated taxa has been indicated.
Abstract: Cytomixis has been observed in the pollen mother cells of Leucas aspera, two species of Mentha and two populations of Leonurus sibiricus. In Mentha piperita L. (2n=120), it has been noted to be of common occurrence as it occurs in almost all the stages of meiotic division. The probable correlation between the aneuploid gamete production, pollen sterility and the cytomictic connections in all the investigated taxa has been indicated.
TL;DR: The karyotype formulae, as brought out in the present study differ quite distinctly amongst the species in-vestigated, principally involve the nucleolar chromosomes of both long and short types.
Abstract: Cytological studies have been carried out on five different species of Agave, collected from different parts of India. All of them revealed diploidy having 2n=60 chromosomes. A distinct bimodal karyotype with very long and very short chromosomes in a definite proportion of 5:25 ratio is the most significant characteristic of this genus. However, the karyotype formulae, as brought out in the present study differ quite distinctly amongst the species in-vestigated. Such variations principally involve the nucleolar chromosomes of both long and short types. The total chromosome lengths and volumes also differ at the interspecific level. Structural alterations along with differential degrees of coiling of chromosomes are the suggested factors principally responsible for such variations.
TL;DR: Une etude cytologique d'hybrides issus du croisement de ces cinq varietes, deux a deux, permet de montrer que les paires chromosomiques impliquees dans ces remaniements sont les memes pour l'ensemble des varietations a l'exception de Tonda di Giffoni.
Abstract: Certaines varietes cultivees de noisetier sont caracterisees par une sterilite mâle partielle liee a la presence d'une translocation a l'etat heterozygote (F. de Coutard, Segorbe, Negret, Ronde du Piemont et Tonda di Giffoni).Une etude cytologique d'hybrides issus du croisement de ces cinq varietes, deux a deux, permet de montrer que les paires chromosomiques impliquees dans ces remaniements sont les memes pour l'ensemble des varietes a l'exception de Tonda di Giffoni.
TL;DR: It is evident that lead acetate is a weak mutagen, whereas the use of mercury needs more cautions.
Abstract: The effects of two heavy metal compounds viz., lead acetate and mercuric chloride were studied on the polytene chromosomes in Anopheles stephensi. Various chromotoxic effects such as inversions, translocations, and breaks were observed. In the larvae treated with lead acetate, an increased incidence (as compared to controls) of asynapsis in the X-chromosome was also observed. From the present studies, it is evident that lead acetate is a weak mutagen, whereas the use of mercury needs more cautions.
TL;DR: Among the test pesticides MSMA was observed to be the most effective clastogenic as well as turbagenic agent followed by endosulfan, chlorpyriphos and asulum respectively in that order.
Abstract: Cytological effects of two herbicides viz., asulum and MSMA and two insecticides viz., chlorpyriphos and endosulfan were tested on Allium cepa root meristems. One hour pulse treatments were given with test solutions at different concentrations and allowed to different recovery periods in Hoagland's nutrient solution.Among the test pesticides MSMA was observed to be the most effective clastogenic as well as turbagenic agent followed by endosulfan, chlorpyriphos and asulum respectively in that order.
TL;DR: Observations reveal that the spermatheca, which is in the form of a sac, has single layered epithelium while sperMatheca with apical appendage, or in the forms of sperm storing tubules, has double-layered epithelia.
Abstract: Morphology and histology of spermatheca of seven orthopteran insects is compared. None of the spermathecae are associated with spermathecal accessory gland. Observations reveal that the spermatheca, which is in the form of a sac, has single layered epithelium while spermatheca with apical appendage, or in the form of sperm storing tubules, has double-layered epithelium. The double-layered epithelium is probably more evolved where the outer layer is secretory and the inner is chitogenous in nature.
TL;DR: The present study suggested that sexual polyploidization involving the function of 2n gametes might have played an important role in the origin of naturally occurring intraspecific chromosomal races of C. speciosus.
Abstract: Microsporogenesis in the two diploid clones of C. speciosus was studied in detail. The absence of cytokinesis detected in some of the dyads at the close of the second meiotic division was the mechanism producing 2n pollen in both the diploids. The distinct variation in n and 2n pollen size indicated the possibility of its use as a reliable criterion for estimating the frequency of 2n pollen in large populations. In addition to the normally expected diploids, certain triploid and tetraploid genotypes were identified in the selfed progenies of both the diploids which confirmed the occurrence of functional 2n gametes in their parental diploid clones. The present study suggested that sexual polyploidization involving the function of 2n gametes might have played an important role in the origin of naturally occurring intraspecific chromosomal races of C. speciosus.
TL;DR: Comparision of acute and chronic treatments revealed that the chemical has no cumulative effect, and monocrotophos has been found to be mutagenic in the present test system.
Abstract: In the present study an endeavour has been made to assay the mutagenicity of an organophosphorus pesticide, monocrotophos (Nuvacron) in mouse cytogenetic test system. Cytogenetic assays like somatic chromosome aberration, micronucleus test and sperm shape abnormalities have been done. Different doses (5, 2.5 and 1.25 mg/kg), different exposure times (6, 24, 48 and 120 hours) and different routes (i.p., p.o. and sc) of administration have been employed. The effects are mostly dose, time and route dependent. Comparision of acute and chronic treatments revealed that the chemical has no cumulative effect. Relative sensitivity of cytogenetic assays has been found to be as sperm shape abnormality>chromosome aberration>micronucleus. Monocrotophos has been found to be mutagenic in the present test system.
TL;DR: Comparison of the karyotypes of the donor plant with a regenerated protoclone using the chromosome classification system indicated that translocations and chromosome loss occurred in specific chromosome groups.
Abstract: Somatic chromosome studies using acetocarmine and various banding procedures were initiated on plants of Medicago sativa (2n=4x=32), alfalfa. Banding methodologies were not superior to a conventional acetocarmine staining procedure in specific chromosome identification. A karyotype analysis was conducted on the acetocarmine-stained chromosomes of a plant (RS-K2) selected from the Regen-S cultivar. Chromosomes were divided into eight groups according to the tetraploid nature of M. sativa. Sixteen chromosomes had metacentric centromeres, with the remaining chromosomes appearing more submetacentric. Four SAT-chromosomes were detected, and chromosomes of one group exhibited tertiary constrictions. Certain chromosome groups were indistinguishable because of similar lengths and arm ratios. A generalized chromosome classification system was developed to aid in identification of specific changes in chromosome structure and number. Comparison of the karyotypes of the donor plant with a regenerated protoclone using the chromosome classification system indicated that translocations and chromosome loss occurred in specific chromosome groups.
TL;DR: From these studies it can be confirmed that the low concentrations of the chemicals will only show favourable effects without any meiotic irregularities and the use of these chemicals during flowering stages should be avoided.
Abstract: The effects of two fungicides, Bavistin and Deltan were studied in chilli (Capsicum annuum L. var. x235). Both seed germination and seedling survival were effected with an increase in concentration. The mean chiasma frequency per cell was decreased with the increased concentration of treatments. Critical analysis of PMCs of treated plants revealed chromosomal aberrations including univalents and multivalents, stickiness and non-orientation of chromosomes at metaphase I, whereas chromatin bridges and laggards were observed at anaphase. The cytotoxic/chromotoxic effects have resulted in pollen sterility which ultimately decreased the yield. From these studies it can be confirmed that the low concentrations of the chemicals will only show favourable effects without any meiotic irregularities and the use of these chemicals during flowering stages should be avoided.
TL;DR: Karyotypes in the family show differences in absolute chromosome size indicating changes in nuclear DNA in evolution, and the primary basic number of the family may be n=8 and from this other basic numbers should have originated by means of aneuploidy and euploidsy.
Abstract: The chromosome number of 18 species coming under 6 genera of Cyperaceae from South India has been studied. Chromosome numbers determined in the present study range from 2n=16 to 2n=96.Chromosome numbers determined in the present study and those reported previously in the family reveal the presence of a continuous series of basic numbers between n=8 to n=48. The primary basic number of the family may be n=8 and from this other basic numbers should have originated by means of aneuploidy and euploidy. Along with these karyotype alterations of chromosomes also play important role in evolution.Karyotypes in the family also show differences in absolute chromosome size indicating changes in nuclear DNA in evolution.
TL;DR: 16 taxa coming under 10 families occurring in the Mangroove forests of Tamilnadu, have been studied cytologically, of which first record of chromosome number has been made in lanceolate leaf type.
Abstract: 16 taxa coming under 10 families occurring in the Mangroove forests of Tamilnadu, have been studied cytologically, of which first record of chromosome number has been made in lanceolate leaf type of Sesuvium portulacastrum, Rhizophora candelaria, Ceriops roxburghiana, Bruguiera conjugata, Avicennia marina, Suaeda maritima, S. monoica, Arthrocnemum fruticosum, Aegiceros corniculatus and Ilysanthes tenuifolia.n=18 may be the common primary basic number of the vegetation and from this the basic numbers 8, 9, 11, 12 and 15 should have arisen by decrease of chromosome numbers and the basic numbers n=19, 20, 22 should have originated by increase of chromosome numbers.Smaller size of chromosomes and mostly chromosomes with submedian and subterminal constrictions are the other advanced cytological characters of the mangroove vegetations studied.
TL;DR: The results showed that the two insecticides which are the most effective inducers of SCE are methyl parathion and phoxim.
Abstract: Vicia faba root tips were treated for two hours with several concentrations of the organophosphorus insecticides methyl parathion, dimethoate, oxydemeton methyl, azinphos methyl and phoxim, after one incroporation cycle with 5-bromodeoxyuridine (5-BrdUrd). Afterwards, the roots were exposed to a second replication cycle with 5-BrdUrd. The differential stain technique described by Tempelaar et al. (1982) with some modifications was used. The results showed that the two insecticides which are the most effective inducers of SCE are methyl parathion and phoxim.In no case was a concentration-response relationship observed. The treatments (except with dimethoate 0.5 ppm) produced SCE frequencies which differed significantly from those of the control.
TL;DR: Chromosome stickiness observed in one category was attributed to a recessive gene, the expression of which was influenced by temperature, while variation in chromosome number and multiple meiotic anomalies recorded in the other may be due to spindle abnormalities at premeiotic mitotic cell divisions and at meiosis I.
Abstract: Anomalus meiotic behaviour was recorded in two plants of P. axillaris (Lam.) B.S.P. (2n=14). Meiotic irregularity was associated with diploid chromosome number in one plant, while in the other, chromosome instability and aneuploidy prevailed. Abnormalities such as persistent stickiness of chromosomes from late diplotene stage onwards, diffused arrangement of chromosomes at first metaphase, multipolar spindle abnormality, extreme variability in size of pollen mother cells and pollen grains, and syncyte formation were recorded. Chromosome stickiness observed in one category was attributed to a recessive gene, the expression of which was influenced by temperature, while variation in chromosome number and multiple meiotic anomalies recorded in the other may be due to spindle abnormalities at premeiotic mitotic cell divisions and at meiosis I.
TL;DR: Three species of Astragalus, namely A. grahamianus, A. leucocephalus and A. zanskarensis, collected from two geographically isolated locations each, have been found to exhibit inter-population karyotypic differences.
Abstract: Three species of Astragalus, namely A. grahamianus, A. leucocephalus and A. zanskarensis, collected from two geographically isolated locations each, have been found to exhibit inter-population karyotypic differences. These populations have been found to differ from each other in almost all the karyotypic features like the range of chromosome size, types of chromosomes constituting their karyotypes, total chromatin length, mean chromatin length and the position of marker chromosomes in their idiograms. These interpopulation karyotypic differences and their bearing on the evolution, in these species, have been discussed.
TL;DR: The karyotype of a stingless bee, Melipona favosa, consisted of 6 metacentric, 2 submetacentric and one subtelocentric chromosomes.
Abstract: The karyotype of a stingless bee, Melipona favosa was analysed. The number of chromosomes was n=9, consisted of 6 metacentric, 2 submetacentric and one subtelocentric chromosomes.The basic chromosome number of the genus Melipona seems to be n=9. No chromosome common between the genus Melipona and Apis was morphologically found in the present study.
TL;DR: The haploid number of chromosomes n=12+h and the diploid values 2n =25 in males, and 2n=26 in females, have been determined for three geographically separated populations of Theodoxus meridionalis (Neritidae).
Abstract: The haploid number of chromosomes n=12+h and the diploid values 2n=25 in males, and 2n=26 in females, have been determined for three geographically separated populations of Theodoxus meridionalis (Neritidae). A male XO sex-determining mechanism has been observed for this species.
TL;DR: The results indicate that the damage is not repaired fully either naturally or by the prolonged treatment of vitamin A or vitamin C, thus the vitamins cannot exhibit their antagonistic properties when the damage has already taken place.
Abstract: Effects of vitamin C and vitamin A were reported on the damaged bone marrow chromosomes and sister chromatid exchange studies on mice induced by both metanil yellow and zinc chioride. The results indicate that the damage is not repaired fully either naturally or by the prolonged treatment of vitamin A or vitamin C. Thus the vitamins cannot exhibit their antagonistic properties when the damage has already taken place.
TL;DR: Meiotic observations in this study indicate that the basic chromosome number in Sorghum bicolor is x=5 and that this species is a segmental allotetraploid.
Abstract: Meiotic observations in this study indicate that the basic chromosome number in Sorghum bicolor is x=5 and that this species is a segmental allotetraploid. The wild and cultivated members of this species were crossed, producing at F2, an array of morphological types. One of the intervarietal hybrids showed complex multivalent associations with the attendant reduction in pollen viability indicating interchange heterozygosity. Based on the cytological and hybridization results a probable hybrid origin is proposed for Sorghum bicolor.