Showing papers in "Cytologia in 1959"
TL;DR: The presence of a normal appearing sex bivalent with a ring or chain of four configuration, involving Matthey's “X” chromosome, support the writer's views that the largest metacentric pair is purely autosomal.
Abstract: 1. The normal complement of the Chinese hamster consists of 11 pairs of readily distinguishable chromosome types.2. The sex bivalent of the Chinese hamster is the third largest in the complement. It resembles the J-shaped “isomorphic” Chromosome pair VIII. Earlier selections by Matthey and Pontecorvo, involving heteromorphism and or the largest metacentrics as sex elements, are considered incorrect on the basis of present experimental data.3. Variation in the length of Chromosome I is due to mechanical stretching, leaving the impression of heteromorphism of homologues.4. Reciprocal translocations are readily identified in offspring sired by x-irradiated males. The presence of a normal appearing sex bivalent with a ring or chain of four configuration, involving Matthey's “X” chromosome, support the writer's views that the largest metacentric pair is purely autosomal.5. Experimental proof of the actual sex chromosomes remains to be demonstrated.
28 citations
TL;DR: Initial hybridization between two unidentified species with n=5 each leading to segmental allopolyploidy, and followed by two successive autopolyploidization, have probably resulted in the origin of S. officinarum with 80 chromosomes.
Abstract: The euploid number of Saccharum officinarum L. is 80. By crossing noble cane variety vellai (2n=80) to Sclerostachya fusca A. Camus (2n=30), and by repeated back-crossing to the recurrent male parent, the chromosomes of sugarcane will be halved in each successive back-cross generation. Till finally, in the third back-cross generation only 10 sugarcane chromosomes are left in the hybrid along with 30 Sclerostachya-Narenga chromosomes. The third back-crossing was done in Taiwan. Narenga Porphyrocoma (Hance) Bor (2n=30) was used instead of Sclerostachya.SG310/6 (BC1) was found to have 72 chromosomes, 42 of which belong to sugarcane, the other 30 to Sclerostachya. It was obtained by back-crossing F1 hybrid to Sclerostachya. Of PMC's examined, many had 36 bivalents showing complete autosyndesis. The larger closed-type bivalents of Sclerostachya can be easily distinguished from the smaller open-type ones of sugarcane. One or two tetravalents were formed by the sugarcane chromosomes.In the second back-cross generation, clone SG363/4 was found to have 50 chromosomes. In majority of the cases, 25 bivalents were found. Again it showed complete autosyndesis. One sugarcane tetravalent was found sometimes.In the third back-cross generation, Narenga was used. 14 out of 15 plants were found to have 40 chromosomes. The other had 63. There was almost perfect pairing between the chromosomes of Sclerostachya and Narenga forming 15 closed type bivalents. The 10 sugarcane chromosomes remained either as univalents or as 1-4 open type bivalents. As many as 4 trivalents were found. It showed that 4 sugarcane chromosomes were partially homologous with 4 Sclerostuchya-Narenga chromosomes. Sometimes, two tetravalents were found. There were found to be composed of two sugarcane and two Sclerostachya-Narenga chromosomes.From these, it is conjectured that the 10 sugarcane chromosomes are probably made up of two sets of 5. Four chromosomes of each set are partially homologous to one another. At least 4 chromosomes of one set of 5 of one species are partially homologous to 4 of those from either Sclerostachya or Narenga. Initial hybridization between two unidentified species with n=5 each leading to segmental allopolyploidy, and followed by two successive autopolyploidization, have probably resulted in the origin of S. officinarum with 80 chromosomes.
22 citations
TL;DR: It has been revealed, that in spite of a homogeneity amongst all the strains, each strain is characterised by its own karyotype, which suggests that the structural changes of chromosomes have always been associated with the evolution of different varieties.
Abstract: In order to find out how far karyotypic changes or undetectable gene mutations have been associated with the origin of different varieties of Lathyrus odoratus, which differ in flower colour, leaf nature, tendril character etc., a thorough analysis of the karyotype of different pure varieties of L. odoratus have been carried out in the present investigation. For this purpose a new improved method involving pre-treatment with paradichlorobenzene was employed and the procedure for all the strains had been kept constant.It has been revealed, that in spite of a homogeneity amongst all the strains, each strain is characterised by its own karyotype. They mainly differ with respect to the number and position of constriction regions in chromosomes. All these facts suggest that the structural changes of chromosomes have always been associated with the evolution of different varieties.Regular meiosis noticed in these strains can be explained by assuming that through extensive cultivation and selection all the structural alterations have attained a state of homozygosity.
20 citations
TL;DR: Most of the morphological findings included in the present note, as well as some of the points of view attained, may be summarized in diagram form as shown in Fig. 7.
Abstract: 1. Histological structure of acontium of Diadumene luciae was studied by means of light-microscopical as well as electron-microscopical examinations. Certain indications were obtained that the whole surface of acontium was covered by a thin, continuous, uniformly ciliated sheet of protoplasm, which also separated the distal end of the cnidae from the exterior. It was very probable that the cnidae were situated in vacuole-like cavities among the epithelium, without any cytoplasmic coat such as to be called “cnidoblast”.2. Peculiar refractile bodies of varying forms such as could be assumed as developmental stages of cnida were abundantly found in the acontia, which were in the course of regenerating either themselves or their cnidae. Evidence obtained from their study also pointed to the view that the cnidoblast had already been degenerated in the full-grown cnidae.3. Remarks are given of some further findings as to structural elements of acontia and of cnidae, including the peculiar globular bodies, which were normally found within the acontia and were suggested as possible precursors of cnidae.Most of the morphological findings included in the present note, as well as some of the points of view attained, may be summarized in diagram form as shown in Fig. 7.
19 citations
TL;DR: Early literature as well as the present records show that in species of this genus, a large number of chromosomal biotypes occur, and the importance of analysis of these biotypes from a cyto-ecological standpoint has been emphasized.
Abstract: 1. A cytological investigation of five different species and varieties of the genus Mentha have been carried out. Their chromosome numbers noted here are as follows:i) Mentha viridis Linn. var. I 2n=32ii) Mentha viridis Linn. var. II 2n=48iii) M. piperita Linn. var. I 2n=72iv) M. piperita Linn. var. II n=66v) M. arvensis Linn. 2n=902. Karyotype analysis in detail has been performed in four species and varieties. Meiosis has been worked out in M. viridis var. I and M. piperita var. II.3. It has been shown that each species and variety has got a karyotype, characteristic of its own. This fact indicates that evolution has been associated with a considerable degree of structural changes of chromosomes in them.4. Role of polyploidy in speciation in this genus has been emphasized in view of the present and the previous data available on this aspect in the different species. Six has been considered as the possible basic number of chromosomes, from which all the euploid and aneuploid series have evolved.5. Early literature as well as the present records show that in species of this genus, a large number of chromosomal biotypes occur. The importance of analysis of these biotypes from a cyto-ecological standpoint has been emphasized.6. Variation in chromosome number in the same somatic tissue and the ineffective method of sexual reproduction have been pointed out as responsible for the origin of chromosomal biotypes or individuals with different chromosome numbers. Their role in speciation as an additional means is obvious.In conclusion, the authors wish to express their sincere thanks to Dr. K. P. Biswas, Director in charge, Medicinal Plants Scheme, Government of West Bengal, for giving us all facilities to collect different wild and cultivated species of Mentha at Rongo, Darjeeling.
19 citations
17 citations
TL;DR: The metallophilic cytoplasm could not be verified in rhizoids of the sporeling of a moss, Pogonatum inflexum, in root hairs of the seedling of some Angiosperm, Glycine Max, Raphanus sativus, and Triticum vulgare and it seems that it cannot be attributed to the attraction by the cy toplasm of metallic ions caused by difference in electric charge between the two.
Abstract: 1. When rhizoid is differentiated from the protonema of some ferns, Dryopteris varia, Diplazium japonicum, and Blechnum niponicum a special cytoplasm which has a high affinity for metallic ions, called the “metallophilic cytoplasm”, appears at the presumptive part prior to the actual differentiation as a prepattern to the rhizoid formation.2. In the rhizoid under active elongation, the metallophilic cytoplasm appears in the basal region while in a fullgrown rhizoid it is restricted to the basal end.3. The metallophilic cytoplasm could not be verified in rhizoids of the sporeling of a moss, Pogonatum inflexum, in root hairs of the seedling of some Angiosperm, Glycine Max, Raphanus sativus, and Triticum vulgare. 4. The metallophilic property appears regardless of the acidity level of the cytoplasm whether it is on the lower or on the higher side of its IEP. Therefore, it seems that it cannot be attributed to the attraction by the cytoplasm of metallic ions caused by difference in electric charge between the two.
15 citations
TL;DR: The nuclei in the germ tubes and mycelium of the imperfect fungus Phyllosticta sp.
Abstract: The nuclei in the germ tubes and mycelium of the imperfect fungus Phyllosticta sp. do not divide in a manner directly comparable to ordinary mitosis. A mitotic apparatus such as a spindle or metaphase plate was not observed. At the beginning of division the granular chromatin contracts usually forming a tightly packed complex of filaments. Counts of these filaments could not be made. As division proceeds this complex elongates, constricts at the midregion and at the end of division the extremities pull apart forming the chromatin portions of the sister nuclei. During division the original central body becomes separated from the dividing chromatin and progressively smaller. At the end of division the central body is either a tiny remnant of its former self or has completely disappeared. New central bodies are formed in the maturing sister nuclei.
14 citations
14 citations
Journal Article•
Journal Article•
TL;DR: Variant colonies arising after irradiation, when overlaid with triphenyl tetrazolium chloride agar, can be classified as “whole colony” and “variegated or sectored,” which may explain some cases of “reversion” of respirationdeficient cells to wild type.
Abstract: Ultraviolet radiation induces respiration-deficient variants with high frequency in both haploid and tetraploid yeasts. Variant colonies arising after irradiation, when overlaid with triphenyl tetrazolium chloride agar, can be classified as (1) “whole colony” and (2) “variegated or sectored.” The heterogeneity in respiratory phenotype of the latter type of colonies is not detectable by colony morphology prior to overlaying with tetrazolium agar. The variegated types may explain some cases of “reversion” of respirationdeficient cells to wild type. Whole colony variants can be grouped into two classes (vI and vII). The vI variants are similar to spontaneously occurring variants and fail to revert to wild type, whereas the vII variants generally revert to wild type at a low frequency. The vI type is produced most frequently and presumably results from nongenic radiation damage, while the less frequently occurring vI type results from nuclear damage.
TL;DR: The binucleate cell is capable of subsequent mitosis in Euglena acus and EuglENA spirogyra, the half-nuclei dividing simultaneously, and cell cleavage following this mitosis produces two bin nucleate cells.
Abstract: Amitosis is recorded for Euglena acus, Euglena spirogyra and Euglena viridis, occurring only in biphasic culture. The process is a nuclear fragmentation not connected with reproduction, the product being a binucleate cell.The binucleate cell is capable of subsequent mitosis in Euglena acus and Euglena spirogyra, the half-nuclei dividing simultaneously.Cell cleavage following this mitosis produces two binucleate cells. Rare miscleavage results in cells with one half-nucleus (approximately half the specific chromosome complement) and with three half-nuclei (one-and-a-half times the specific chromosome complement). These types of cells are viable and their progeny retain the cytological characteristics of the species.
TL;DR: The testes of Anopheles stephensi sensu stricto are two pale yellowish, ellipsoidal bodies whose wall consists of an outer, tough, pigmented envelope, and an inner squamous epithelial layer.
Abstract: 1. The testes of Anopheles stephensi sensu stricto are two pale yellowish, ellipsoidal bodies. Their wall consists of an outer, tough, pigmented envelope, and an inner squamous epithelial layer. The nuclei of various types of resting cells within the testes are characterized by a peripheral, basophilic crescent. The anterior part of the testicular cavity is divided into cysts which hold spermatogonia and primary spermatocytes. Germ cells at later stages of differentiation are held free within the posterior part of the testicular cavity.2. The spermatogonial metaphase configuration consists of two pairs of V-shaped autosomes and a pair of unequal, subtelocentric sex chromosomes. The homologous chromosomes exhibit somatic pairing. The centromeres appear as distinct, non-staining gaps. The centromere is slightly off-median in one of the autosomal pairs.3. The nuclei of early primary spermatocytes show long, slender, chromomeric threads and a peripheral basophilic crescent. The latter subsequently resolves into deeply staining thread-like structures representing the heterochromatic regions of the sex chromosomes and a lightly staining nucleolar body. The chromosomal threads undergo a process of uniform condensation to produce thick pachytene bivalents. The nucleolus disappears by diplotene. The sex chromosomes associate together only along short lengths of their long limbs proximal to their centromeres. Terminalization of chiasmata takes place during diakinetic condensation of the chromosomes. The sex bivalent is symmetrical. The metaphase spindle is formed within a welldefined nuclear space surrounded by a thin limiting membrane. Tiny dotlike centrioles are present. At first anaphase the autosomal univalents disjoin normally. The sex chromosomes, on the otherhand, show obligatory postreduction. The sex chromosomes lag during the first anaphase separation. In the dyads the chromatids are widely divergent except near the centromere. The telophase nuclei are oval in shape and show a peripheral concentration of chromatin.4. A short interkinesis stage is present. At the second prophase the dyads appear as typical X or cross-shaped figures. Subsequently they constitute a tangled group at the centre of nucleus representing a prometaphase stage. A second metaphase plate is produced although the stage is of short duration only. The sex chromosomes show precession during the second anaphase. The spermatid nuclei fall into two classes on the basis of the relative dimensions of their heteropycnotic dots.
TL;DR: The megasporocytes of Lilium constitute excellent material for the study of nucleoli since they are quite large, are not so masked by the chromatin at most stages as are the microsporocytic nucleoli, and the stages are lengthened in time making it easier to get a completely graduated series for study.
Abstract: The megasporocytes of Lilium constitute excellent material for the study of nucleoli since they are quite large, are not so masked by the chromatin at most stages as are the microsporocytic nucleoli, and the stages are lengthened in time making it easier to get a completely graduated series for study.Two types of extrusions emerge from the nucleoli. A homogeneous substance is extruded as the megasporocyte begins to elongate and a small globular body is extruded in early prophase I. The latter extrusion occurs concurrently with, or immediately before, a deep invagination is formed in the nucleolus.
TL;DR: Cytology of 4 species of Atrichum Palis has been studied and difference in the sexuality of A. flavisetum and A. subserratum indicate that a monoecious race of the former and a dioeciousRace of the latter may be expected to grow in this area or near it.
Abstract: 1. Cytology of 4 species of Atrichum Palis has been studied. A. flavisetum and A. pallidum (both dioecious) have seven chromosomes each, while A. subserratum and A. obtusulum (which includes A. sub-obtusulum of C. Muller) both monoecious have 14 chromosomes each.2. Difference in the sexuality of A. flavisetum and A. subserratum between what we have noted and Brotherus has recorded, indicate that a monoecious race of the former and a dioecious race of the latter may be expected to grow in this area or near it.3. A. subserratum may have been produced by hybridization between A. flavisetum (recorded) and A. subserratum (diploid expected race) or by auto-polyploidy of the latter.4. A. obtusulum may be the hybrid between a diploid like A. subserratum expected, but differing from it in having “m” chromosome and A. pallidum.5. A search is being made for the expected “races” and species. Further work on the cytology of this group or plexus of species is in hand.Our sincerest thanks are due to Prof. P. N. Mehra for providing facilities, which enabled us to carry on this work, to Shri T. N. Khoshoo for going through the manuscript, Shri R. S. Pathania for the microphotographs and Mr. A. H. Norkett for the determination of the species of Atrichum.
TL;DR: There is evidence that all H-segments from metaphase to late anaphase are capable of such synthesis, and differential reactivity in polyploid cells and plants is identical with that in its diploid counter-part.
Abstract: 1. The degree of differentiation attained after chilling varies from one H-segment to another in Trillium, both between and within the species. These can be grouped into four degrees:1° Slight (e.g. T. stylosum)2° Moderate (e.g. most Trillium segments)3° HIGH (e.g. Paris polyphylla)4° Extreme (e.g. T. undulatum and Japanese species)2. H-segments lose their differential appearance when chilled chromosomes are blocked at metaphase and returned to normal temperatures. This would seem to be due to a synthesis of DNA by H-segments, which are regarded as being retained in an early prophase condition. There is evidence that all H-segments from metaphase to late anaphase are capable of such synthesis.3. Differential reactivity in polyploid cells and plants is identical with that in its diploid counter-part.4. Chemical treatment of Trillium chromosomes has failed to reveal H-segments. This might be due to the chemical treatments being nonspecific for heterochromatin. All the chemical methods suggested in the literature seem to be variable and therefore unreliable in their results.
TL;DR: This paper will be concerned largely with some of the major questions which consideration of these two models inevitably raises and set up a general model which at least has value as a basis for experimentation.
Abstract: By the term \"mitotic cycle\" is meant the series of events which occur from the inception of one mitosis to the inception of the ensuing one. For purposes of discussion, this cycle may be divided into 4 segments; namely, active mitosis, synthetic stage, resting phase , and antephase. The relative durations of these segments is, for the most part, unknown and probably varies depending on a variety of factors such as age, metabolic state of tissue, etc. Furthermore, the transition between stages can scarcely be con sidered as being abrupt. Nonetheless, the segments of the cycle mentioned above must represent somewhat different levels of physiological activity. Despite the lack of detailed information concerning the more important changes which occur during the mitotic cycle, it is still possible to set up a general model which at least has value as a basis for experimentation. The diagrams in figures 1A and 113 represent two such models (1A for the multicellular organism; 1B for the unicellular organism). This paper will be concerned largely with some of the major questions which consideration of these two models inevitably raises. The 4 segments of the mitotic cycle may be defined as follows: 1. Active mitosis. This stage represents that part of the cycle during which active division of the nucleus into two daughter nuclei occurs. 2. Synthetic stage. By this stage is meant that period following active mitosis during which major growth of daughter cells occurs. This stage obviously involves considerable synthetic activity, since the daughter cells must increase by a factor of approximately two in size. 3. Resting phase. This stage is a somewhat hypothetical, but obviously necessary, stage between the end of synthesis and the regaining of high mitotic competence. This is presumably a stage of comparative quiescene and would seem to be the period during which a cell would be most likely to undergo differentiation under appropriate conditions (see figures 1A and 1B.) 4. Antephase. This term has been used by Bullough (1952) and also by Wilson and Hyypio (1954) to designate a stage just prior to the inception of active mitosis. The major morphological criterion for such a stage is a
TL;DR: Findings are taken to indicate that the primary radiation events which result in inactivation or loss of the extrachromosomal genetic determinants of cellular respiration are nuclear in nature.
Abstract: The kinetics of the induction by ultraviolet radiation of extrachromosomally inherited respiratory deficiency in Saccharomyces is determined by the ploidy level of the cells. The fraction of the inducing radiation damage which is photoreactivatable is similarly ploidy dependent. These findings are taken to indicate that the primary radiation events which result in inactivation or loss of the extrachromosomal genetic determinants of cellular respiration are nuclear in nature.
TL;DR: The two cytologically distinct races of M. tuberculatus though not markedly different with respect to size and external morphology do show ecological physiological and biochemical differences and Polyploidy seems to confer hardiness and selective advantage.
Abstract: 1. The chromosomes of six Melaniid snails have been studied. The chromosome numbers of the various forms are as follows.Melania crenulata _??_ 2n=34+X=35Paludomus tanschaurica _??_ 2n=36+XY=38Melanoides tuberculatus (diploid race) _??_ 2n=32Melanoides tuberculatus (polyploid race) _??_ and_??_ 90-94Melanoides lineatus _??_ and _??_ 71-73Melanoides scabra _??_ 76-782. The chromosomes of all the Melaniids studied are metacentric and in this respect their chromosome complements are similar.3. All the Melanoides except the diploid race of M. tuberculatus are high polyploids and these add to the only one instance of polyploidy so far known in Molluscs.4. The co-existence of parthenogenesis and polyploidy may account for the numerous forms of Melanoides, their variability, wide distribution and consequent taxonomic difficulty. In view of the prevailing confusion in identification and nomenclature of the Melaniids in general, a cytotaxonomical approach seems imperative. An indication of this is provided by the two races of M. tuberculatus.5. The two cytologically distinct races of M. tuberculatus though not markedly different with respect to size and external morphology do show ecological physiological and biochemical differences. Polyploidy seems to confer hardiness and selective advantage.
TL;DR: The diploid chromosome number in the males of this species is 46 and the fundamental chromosome number is also the same, so possibility of the occurrence of M-A+A type of process is discussed.
Abstract: 1. The diploid chromosome number in the males of this species is 46. The fundamental chromosome number is also the same.2. No metacentrics have been observed in the karyotypes of this species. It is being reported for the first time for ophidian karyotypes.3. Meiosis is normal. First and second metaphases show 23 bivalent and univalent chromosomes, respectively. Males are homogametic.4. Possibility of the occurrence of M-A+A type of process is discussed.
TL;DR: It is proposed that this pentaploid race probably arose as a hybrid between triploid and tetraploid races in which unreduced gametes of former were involved and is proposed to be a segmental-allopentaploid (AA AIAI B).
Abstract: The present population is pentaploid with seven as the basic number. The karyotype shows that all the chromosomes are median or submedian. However, four submedian chromosomes have their smaller arms, rather shorter than the smaller arms of the remaining submedian chromosomes. Two of these have an exaggerated centromere and have a secondary constriction located very near it. The karyotype can be relegated into two sets of 14 chromosomes each, and another set of 7 chromosomes.At meiosis pentavalents to univalents are organized. Higher associations occur in a lower frequency, The maximum number of bivalents is 14, which are accompanied by 7 univalents.At anaphase-I unequal distribution is common. The number at a pole varies from 14 to 21. Lagging and misdividing univalents, telocentrics, bridges with and without fragments are present.On average 29.6 chromosomes pair at metaphase-I, while 5.4 remain as univalents. This point, coupled with the karyotypic evidence, makes it reasonably clear that there are probably two sets of 14 fairly homologous chromosomes plus 7 other chromosomes. In the former two sets, there are small portions that are homologous, which fact accounts for the low multivalent frequency. It appears that this race is a segmental-allopentaploid (AA AIAI B). On the basis of the comparative evidence from the karyotypes, it is proposed that this pentaploid race probably arose as a hybrid between triploid and tetraploid races in which unreduced gametes of former were involved.The seeds appear to be inviable but the race is perpetuated by production of 8-10 bulbs by each individual.
TL;DR: A chromosome survey was made in the following human malignant tumors in vivo; sixteen gastric cancers, five maxillary cancers, four laryngeal cancers, two penis cancers and four reticulosarcomas.
Abstract: A chromosome survey was made in the following human malignant tumors in vivo; sixteen gastric cancers, five maxillary cancers, four laryngeal cancers, two penis cancers and four reticulosarcomas.Evidence was presented that in each tumor stem-cells are present with a characteristic range and mode of chromosome numbers and a particular idiogram by which the tumor is clearly distinguishable from other tumors, as well as from the ordinary tissue. The stemline chromosome numbers show a wide variation ranging from hypodiploid to hypertetraploid.It was shown that most of the chromosomes of neoplastic cells differ in shape and/or size from those of normal cells; it is assumed that in tumor chromosomes considerable structural and mutational changes must have occurred probably correlated with the neoplastic condition.
TL;DR: A number of features of chromosome behaviour in the triploid of Endymion hispanicus (Mill) Chouard is shown to play some part in the sterility of this type of polyploid.
Abstract: 1) The suitability of the chromosomes of the Bluebell, has made it possible to study the composition of the individual chromosome-number classes at pollen-mitosis in the triploid of Endymion hispanicus (Mill) Chouard.2) Present studies show that the Anaphase chromosome classes and the Pollen-grain groups may not be ‘pure’, but may contain all 3 of one chromosome or lack all 3 of a particular chromosome.3) In the triploid Bluebells the Pollen-mitosis showed an apparent increase in groups with more than 1.5n chromosomes, and it has been shown that a number of this is caused by the ‘impure grains’. The presence of these grains is due to delay in disjunction at Anaphase I.4) The individual chromosomes in a triploid occur with different frequencies in the population, the highest being the smallest Chromosome H followed by one of the long but satellitic Chromosome D. The lowest is Chromosome B.5) A number of the above features of chromosome behaviour in the triploid is shown to play some part in the sterility of this type of polyploid.