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V. R. Reddi
1971 Volume 36 Issue 3 Pages
377-381
Published: September 25, 1971
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During the study of haploid progenies of a grain
Sorghum variety Tx 403 two aberrant plants with 21 chromosomes were located. In one of the derivatives the extra chromosome formed a chain of five in a proportion of the cell analysed at diakinesis. This evidence suggested that the extra chromosome to be interchanged one, and the plant a tertiary trisomic. The second derivative appeared to be primary trisomic with a translocation involving the nucleolar chromosomes. Cytological evidence confirms the existence of many duplicate segments in the haploid complement of the grain
Sorghum studied, and that some of them at least were located in subterminal or terminal regions of chromosomes.
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K. P. S. Sisodia
1971 Volume 36 Issue 3 Pages
382-391
Published: September 25, 1971
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Detailed microsporogenesis of 4 species of
Urochloa namely
U. pullulans,
U. stolonifera,
U. moschambicensis and
U. setigera is carried out. Critical nature of chromosome pairing is studied and pairing is found regular in allotetraploids. Some multivalent formation is noticed in segmental allotetraploids. Aberrant meiosis in the material is evaluated. The basic chromosome number of the genus and role played by polyploidy, apomixis and hybridization in the evolution of the genus are discussed.
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V. S. Raman, S. R. Sree Rangasamy, G. Manimekalai
1971 Volume 36 Issue 3 Pages
392-399
Published: September 25, 1971
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The cytological behaviour and morphological characteristics of diploid and triploid forms of guava are presented. Meiosis is regular in the diploids with the formation of 11 bivalents. The triploids in general could be distinguished by their greater vigour, large leaves and thicker petals. Meiosis is characterised by a maximum association of chromosomes as 11 trivalents.
The differential development of tissues (ovary wall and placenta) can be attributed to a difference in female sterility. The placenta development is greater in diploids which are fertile or where only partial (genic) female sterility is operative. In case of triploids which are highly seedless, genic sterility is superimposed on chromosomal sterility; the stimulation in placenta development is thereby retarded as fertilisation fails and there appears to result a greaster development of the ovary wall.
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V. S. Raman, G. Manimekalai, S. R. Sreerangaswamy
1971 Volume 36 Issue 3 Pages
400-404
Published: September 25, 1971
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The haploid chromosome number in forty accessions of pomegranate investigated upon was found to be 9. The most frequent chromosome association was 1
IV+7
II. The other associations viz., 2
IV+5
II or 9
II were less frequent. One of the quadrivalents was nucleolar. The quadrivalent always disjoined as 2/2. The horticultural type in which most of the anthers become petaloid has the same chromosome number and behaviour as the other varieties studied. There was no deviation between the somatic and the gametic chromosome numbers. The chromosomal variation in pomegranate has been found to be very little and in improvement hybridisation between varieties would be more profitable than induction of polyploidy or mutations.
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R. B. Singh
1971 Volume 36 Issue 3 Pages
405-410
Published: September 25, 1971
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The basic karyotype of the hexaploid
R. acetocella (2
n=42) were compared with its progenitor diploid
R. angiocarpus (2
n=14). Both the species are dioecious. The sex chromosomes of
R. acetosella were in active evolutionary state and a little differentiation had taken place in the autosomes. On the contrary, the sex chromosomes of
R. angiocarpus have been reported to be stable while the autosomes show considerable repatterning.
The basic karyotype of the two species resembled closely. The corresponding chromosome by chromosome and total chromosome length comparisons of the diploid and the hexaploid species revealed that chromatin loss, decrease of 19.62 precent from the expected, has occured during the evolution of
R. acetosella subsequent to polyploidization. The chromatin loss had caused higher degree of karyotypic asymmetry in the polyploid. The evolutionary significances of the karyotype repatterning in
R. acetocella have been discussed.
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L. Wu, H. W. Li
1971 Volume 36 Issue 3 Pages
411-416
Published: September 25, 1971
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Callus tissues were induced from different somatic organs of
O. sativa variety Taichung No. 65. Specific 2.4-dichlorophenoxy acetic acid (2.4-D) concentration in a medium is necessary for the induction of callus from different organs. The optium 2.4-D concentration for callus induction from different organs are 0.5ppm for roots, 2ppm for scutellum and cotyledonous node, 6ppm for coleoptile and 8ppm for stem nodes and leaf-sheath. All cultures were incubated in darkness at 28°C.
Anatomical studies showed that the initiation of callus tissues from leaf-and coleoptile are initiated from the meristematic cells located very closely by the immature vascular bundles. The initiation of callus in nodes seems to be similar to those of adventitious roots which are initiated near to the differentiating vascular tissue or directly from the procambium.
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Brent L. Davis, Robert J. Baker
1971 Volume 36 Issue 3 Pages
417-420
Published: September 25, 1971
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IV. Cytology of photoperiodic races and cytotypes of Ageratum conyzoides L
M. L. H. Kaul
1971 Volume 36 Issue 3 Pages
421-434
Published: September 25, 1971
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The paper gives an account of the cytological features of two cytotypes (diploid and tetraploid) and of two ecological races
viz., monsoon and winter form, both being tetraploids. The winter form is characterized by a higher number of metacentric chromosomes and higher recombination index; the range of chromosome length being similar in both the forms. Significant reduction in chiasmata from diplotene to diakinesis occurs in both the forms but the chiasma frequency differs significantly between the two forms being higher in winter form. Prefixatives and climatic factors seems to affect the chisama relationships of bivalents significantly. Resemblance in karyotype, morphology and in habitat preference between diploid and winter forms leads one to believe the former to be a putative parent of the latter form. But this needs confirmations.
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G. Harinarayana, B. R. Murky
1971 Volume 36 Issue 3 Pages
435-448
Published: September 25, 1971
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The restriction of recombination through chiasma frequency was investigated in
Pennisetum and
Brassica where outbreeding is controlled by two different genetic mechanisms. Lines with known inbreeding coefficients were utilised for this purpose. Self-compatible and self-incompatible
Brassica material subjected to five generations of disruptive selection for flowering was also included.
A consistent increase was observed in the mean chiasma frequency per cell of
Pennisetum and
Brassica inbreds as compared to the outbred populations. The increase was parallel with the degree of inbreeding in
Pennisetum. Disruptive selection for flowering increased chiasma frequency in Brassica populations with the exception of late self-incompatible group.
The buffering mechanism of chiasma frequency under inbreeding, referred to as cytological homeostasis, was examined from the viewpoint of the genetic diversity of the populations, the past history of selection, the ecological conditions under which the material is grown, the nature of the breeding system and the fitness-flexibility axis. It is concluded that a compromise between fitness and flexibility is arrived essentially by regulation of recombination through cytological homeostasis and the breeding system.
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Richard E. Crang, Ned B. Hein
1971 Volume 36 Issue 3 Pages
449-454
Published: September 25, 1971
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In enzyme treatment studies of
Lychnis alba pollen tubes, cellulase activity degraded 100-200Å fibers associated with wall material and intracytoplasmic fibrillar masses. The wall behind the pollen tube tip is twolayered with the inner layer being composed primarily of an amorphous pectinaceous substance. Terminal wall material was demonstrated to be removed by low pH (5.0-5.5) regardless of the enzyme treatment, indicating a lack of structural polymerization of the wall components. No callose has been demonstrated in the walls of
L. alba pollen tubes.
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Tadashi Hirano
1971 Volume 36 Issue 3 Pages
455-460
Published: September 25, 1971
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The cells of
Saccharomyces cerevisiae labelled with
3H-uridine was studied by electron microscopic autoradiography. The silver deposits are localized over the cytoplasm of the mother cell as well as the daughter cell. It seems reasonable to conclude that the silver deposits are due to
3H-uridine incorporated into ribonucleic acid during growth of the cells. According to this observation, RNA synthesis and storage do not occur within the vacuole in yeast
Saccharomyces.
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P. S. Reddy, R. D'Cruz
1971 Volume 36 Issue 3 Pages
461-468
Published: September 25, 1971
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Seven hybrids were obtained from
D. annulatum (2n=40)×
D. aristatum, (2n=20), out of which four were pentaploids (2n=50), one was tetraploid (2n=40), and two were aneuploids (2n=41 and 42). Out of four hybrids obtained from
D. annulatum (2n=40)×
D. caricosum (2n=20), two were pentaploids, one was a triploid (2n=30), and the other aneuploid (2n=46). These hybrids showed meiotic irregularities like univalents and multivalents at metaphase I, bridges and laggards at anaphase I and II, and micronuclei in the quartets. Abnormal sporads were frequently observed in those hybrids. The aneuploid hybrid with 2n=42 chromosomes of the cross
D. annulatum×
D. aristatum, occasionally formed pentads. One of the two pentaploid hybrids of
D. annulatum×
D. caricosum presented unusually long chromosomes during meiotic division. The hybrids exhibited different degrees of pollen and seed sterility. The factors responsible for such sterility have been discussed.
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I. Cyamopsis psoraloides DC
Amal K. Biswas, N. K. Bhattacharyya
1971 Volume 36 Issue 3 Pages
469-479
Published: September 25, 1971
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Seeds and seedlings of
Cyamopsis psoraloides DC. were treated with different concentrations of colchicine solution for different durations to induce polyploidy. No polyploids could be obtained in seed treatment which can be accounted for the toxic effects of the chemical. Aqueous colchicine solution of two different concentrations viz. 0.25 and 0.5 percent applied on cotton pad around the stem tip at seedling stage responded well. Treatment with 0.25 percent colchicine for 6 hours 2 days treatment gave maximum polyploids.
The induced polyploids were either complete tetraploids, or mixoploids with hypotetraploid chromosome numbers. One plant was hexaploid.
Typical effect of colchicine, like slow growth of plant during early stages of development, thicker, fleshy and deformed leaves, less number and big size of stomata were observed in treated plants in comparison to diploids. Delayed flowering with lesser number of flowers per inflorescence as well as per plant in the tetraploid plants was significant. Pollen size and sterility in the tetraploids increased considerably. Number of fruits and seeds were few in tetraploids in comparison to those in diploids. On the whole C
0 and C
1 plants were less vigorous in growth.
Detailed cytological studies of the diploid plant have been carried out. Irregularities in chromosome association at metaphase I were prominent in the polyploids. The mean frequency of quadrivalents per cell was 0.89. Unequal separation of chromosomes and laggards were present in the meiosis of the polyploids. The present data have been discussed in relation to the previous reports.
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K. Sree Ramulu, S. R. Sree Rangasamy
1971 Volume 36 Issue 3 Pages
480-486
Published: September 25, 1971
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A comparative study on karyology of
Pennisetum typhoides and
P. purpureum and their hybrid and amphiploid revealed considerable differences in the size, shape and position of centromere of the chromosomes of the constituent genomes. The diploid and tetraploid parents exhibited quantitative differences in size in respect of chromosomes of the homologous genomes A and A' and this was evident in the F
1 hybrid. The cultivated species
P. typhoides possessed more of asymmetry in karyotype than the wild species. The chromosomes of ‘B’ genome of
P. purpureum also exhibited asymmetry but less than the ‘A’ genome.
The concommittant morphological specialisation and the asymmetry of karyotype in
P. typhoides (AA') also point out that dominant features of
P. purpureum resident in ‘B’ genome and less specialisation appear to be associated with symmetry of B' genome. The changes in the karyological features in the F
1 and its amphiploid were not as expected to the value of parents. It is concluded that the alteration of the karyotype might be due to hybridity and would suggest alteration of the genetic control in expression of somatic complement.
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A. H. ar-Rushdi
1971 Volume 36 Issue 3 Pages
487-492
Published: September 25, 1971
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I. A comparison of euchromatic and heterochromatic condensation patterns
Rosalyn M. Patterson, Ernest L. Hunt
1971 Volume 36 Issue 3 Pages
493-498
Published: September 25, 1971
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An investigation has been made of the differential reactivity of chromosomes in urodele developmental stages after exposure to colchicine and low temperature. Embryonic stages of
Ambystoma maculatum and
Triturus viridescens, and larvae of
A. maculatum were maintained at low temperature for specific periods of time. Colchicine was added to the experimental stages one to two days prior to fixation. All stages studied demonstrated a differential reactivity or differential staining of the heterochromatin after maintenance at the low temperature. Prolonged treatment of the chromosomes in colchicine at low temperature produced a supercoiling phenomenon which reduced or obscured the heterochromatic areas, but did not completely eliminate the segmentation. These observations are discussed in relationship to asynchronous replication of heterochromatin in mammalian cells.
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J. C. Stockert, O. D. Colman, M. C. Risueño, M. E. Ferná ...
1971 Volume 36 Issue 3 Pages
499-503
Published: September 25, 1971
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Evidence is adduced for the fact that cold, anoxia or treatment with 2-4 dinitrophenol induced nucleolar segregation in root-tips of
Allium cepa. This is the result of redistribution of the argyrophilic and basophilic components of the nucleolus, generally intermingled, into two clearly separate regions. The central region, appearing as highly argyrophilic, corresponds to the “pars fibrosa”, while the peripheral region, which is basophilic in character, consists of the “pars granulosa”. This morphological change in the nucleolus is exactly like the segregation that is induced in root-tip cells through the inhibition of RNA synthesis and the natural segregation observed in the prophase nucleoli of meiocytes from
Allium cepa.
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P. N. Ravindran
1971 Volume 36 Issue 3 Pages
504-508
Published: September 25, 1971
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The cytological effects of commercial folidol have been investigated using
Allium test. It has been found that folidol produces many chromosome abnormalities such as anaphase inhibition, c-mitosis, chromatid and chromosome breakages, abnormal chromosome separation and micronuclei formation.
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G. Madhusudana Rao, M. V. Reddi
1971 Volume 36 Issue 3 Pages
509-514
Published: September 25, 1971
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Chromosomal associations in a triploid indica rice plant (T. 1242) at meiosis were investigated.
Majority of metaphase I cells showed chromosomal association of 10
III+3
II. Precocious disjunction was observed in non-homologous bivalent and moved to opposite poles. The third chromosome of each trivalent separated first and moved irregularly to the poles.
Majority of the anaphase I cells recorded 19/17 disjunction followed by 18/18 and 20/16. Fifty percent of the cells showed 1 to 5 laggards at telophase I.
Triploid plant exhibited high percent of spikelet sterility and pollen abortion. There seems to be a close relationship between the number of microspores with micronuclei and the pollen sterility; more the micronuclei, greater is the pollen sterility.
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G. Sundara Rajulu
1971 Volume 36 Issue 3 Pages
515-521
Published: September 25, 1971
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1. The haemocytes of a centipede
Scolopendra morsitans was studied by means of phase contrast and ordinary microcopy.
2. Six distinct types of haemocytes comparable to the prohaemocytes, plasmatocytes, granular haemocytes, spherule cells, adipohaemocytes and oenocytoids of insects are observed.
3. The possible interrelations between the different types of haemocytes are discussed.
4. The significance of the occurrence of oenocytoids is discussed with reference to the phylogeny of the group.
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R. Sethupathi Ramalingam, S. R. Sree Rangasamy, V. S. Raman
1971 Volume 36 Issue 3 Pages
522-528
Published: September 25, 1971
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The morphological characteristics and cytological behaviour of hybrids between two garden species of
Zinnia viz.,
Z. linearis (2n=22) and
Z. elegans (2n=24) are described. The hybrid (2n=23) resembled the male parent,
Z. elegans in gross morphology but showed intermediate expressions in respect of many metric attributes. The maximum chromosome association was 1
III+5
II+10
I. The most frequent association was represented by 6
II+11
I. indicating the pairing of partially homologous chromosome sets of the parental species. Hybridisation between the basic types (2n=10 and 2n=12) could have been the primary step in the development of
Z. linearis; in the origin of
Z. elegans, two 12-chromosome types were probably involved. The chromosome complements of the two taxa have been analysed and found to possess differences with regard to the number and size of chromosomes, total chromatin and position of constriction. The asymmetry of the karyotype of
Z. linearis was brought out.
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James P. Braselton, C. C. Bowen
1971 Volume 36 Issue 3 Pages
529-533
Published: September 25, 1971
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Nucleolus organizers in meiotic prophase of
Lilium longiflorum microsporocytes were studied with the electron microscope and found to be less electron-dense than the majority of the chromatin and the nucleolus. The structural units of the nucleolus organizers were observed to be loosely arranged fibrils, 75-125 A in diameter. This organization was interpreted as an intermediate stage in chromatin condensation, indicating decreasing synthetic activity, as was suggested by previous workers on mitotic nucleolus organizers.
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K. Yanagisawa, T. Yamada
1971 Volume 36 Issue 3 Pages
534-538
Published: September 25, 1971
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III. Pronase effects on chromosome structure in vitro
Matti S. Al-Aish
1971 Volume 36 Issue 3 Pages
539-542
Published: September 25, 1971
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Short term cultures derived from peripheral blood of a cytogenetically normal man (46, XY) were treated with pronase and incubated for various intervals. The results show that the longer the incubation with pronase is, the more profound the effects on the chromosomes become. A short pronase treatment causes chromosome stickiness followed by the digestion of the longitudinal structure of the chromosomes. Extended reaction results in complete digestion of the chromosomes and drastic reduction in the number of metaphases present in cultures.
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K. Sree Ramului
1971 Volume 36 Issue 3 Pages
543-551
Published: September 25, 1971
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The effect of ionizing radiations (X- and gamma rays) chemical mutagens (EMS, MMS, DES and NEU) and combination treatments on chiasma frequency was studied in the M
1 plants of three varieties (Co 11, Co 12 and Co 18) of
Sorghum (2n=20) raised from the treated seeds. All the treatments caused a decrease in chiasma frequency compared to control. There was a marked reduction in the number of bivalents with three chiasmata, while the number of bivalents with one chiasma increased following mutagen treatments. There were differences in the action of different mutagen agents on one hand and a differential response of the varieties on the other. The treatments with chemical mutagens caused a higher reduction in chiasma frequency than radiation treatments. The combination treatments of gamma rays and DES caused a higher reduction, while X-rays+NEU increased the chiasma frequency compared to the single treatments. The factors namely the terminalisation, structural changes, univalent formation and the process leading to chiasma formation are discussed in the light of the present results.
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Jan Zizka
1971 Volume 36 Issue 3 Pages
552-554
Published: September 25, 1971
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Chromosome studies of 112 patients with Down's syndrome are presented. Two (1.78%) had a sporadic D/G translocation, five (4.46%) had an inherited D/G translocation, one child (0.89%) exhibited a de novo G/G translocation. Two patients (1.78%) had a normal/trisomy G mosaicism, the remaining 102 patients (91.07%) had a regular trisomy 21. Seventy of 112 patients (62.50%) were born to mothers aged 30 years and younger. Other chromosomal aberrations (XYY syndrome, D/D translocation, abnormally long Y chromosome) were found in three families.
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