Showing papers in "Cytologia in 1937"

Studies on the Chromosome Numbers in Higher Plants, with Special Reference to Cytokinesis, I

Abstract: Since I published “Cytological Studies an Tropaeolum majus” in 1925, 1 have been continually engaged in the karyological investigation of more than 260 species, covering 82 families, including both Monocotyledons and Dicotyledons (cf. Table 1 in which 81 families, 250 forms including 233 species are listed).1) Throughout the present study I have used modified Farmer's fixative exclusively for the fixation of materials of both flower buds and root-tips, and have had favourable results.2) I usually found one more or one less chromosome in related plants instead of a polyploidal relation. In some Gases the cause of this seemed to be explained by chromosome fusion during diaphase.3) In the plant groups investigated in the present work polyploidy and aploidy are both found. Discussion an these phenomena among others is left until further study an chromosome numbers in many more plants or plant groups has been made.4) The chromosome sizes during meiotic and somatic nuclear divisions were measured (cf. Table 1).5) True cell plate formation was not observed in the plants used in the present work.6) Considering the works of previous authors together with the present Gase it may be concluded that the f urrowing process during the formation of partition wall of pollen mother cells prevails in the Dicotyledonous plants and is found also in some Monocotyledons.The expense of carrying out the present study was partly defrayed out of a grant from the Educational Department, and from the Foundation for the Promotion of Industrial and Scientific Research of Japan, to the authorities of which the writer wishes to express his best thanks.

Karyotype Alteration and Phylogeny. IV

Abstract: (1) The karyotypes of nineteen genera in the Amaryllidoideae, namely Haerrzanthus (2n=16, 18), Grij inia (2n=77), Clivia (2n=44), Galanthus (2n=24, 25, 28, 48), Leucojum (2n=14, 22), Nerine (2n=22, 33), Amaryllis (2n=22), Zephyranthes (2n=12, 24, 38), Sternbergia (2n=22) Crirzum (2n=22, 33), Cyrtanthus (2n=22) Eucharis (2n=68), Hymenocallis (2n=46, 69), Narcissus (2n=14, 21, 22, 32), Paracratium (2n=44), Sprekelia (2n=ca. 117), Hippeastrum (2n=44), Habranthus (2n=21) and Lycoris (2n=27) have been analyzed from the point of karyotype alteration (cf. Table 1). Many genera such as Grinia, Clivia, Leucojum, Nerine, Amaryllis, Stervbergia, Crinum, Cyrtanthus, Pancratiurn, Hippeastrunz, Habranthus and Lycoris have the 11-series of chromo-somes, in the ether word 11 is their basic number of chromosomes which indicates the intimate relationship existing between these karyotypes. More striking is the fact that various karyotypes be-longing to the same genus, for instance Leucojutm (b=7, 11), have been explicitly explained by the dislocation hypothesis of Navashin (1932). By further reference to this hypothesis it may be possible to suggest the derivaticn of karyotypes in other genera.(2) The karyotypes of Hymenocallis (2n=46, 69) and Eucharis (2n=68) clearly indicate their derivation from the 11-series by the duplication of chromosomes and the secondary balance. The similar secondary polyploid appeared in Zephyranthes (b=6), i.e., Z. candicla (2n=38). All genera except Haernanthus in the Amaryllidoideae may be concluded to have some karyotypical resemblances, when the karyotype alteration such as fusion, fragmentation, duplication, translocation, inversion, elimination and deficiency have been taken into consideration. The karyotypes of Haemanthus resemble those of Scilla in the Liliaceae or Alstroemeria in the Hypoxidoideae.(3) The karyotypes of five genera in the Agavoideae, namely Bravoa, Polianthes, Agave, Fourcroya, and Beschorneria are similar (so-called the Yucca-Agave karyotype) (5 long and 25 short chromo-somes) (cf. Table 2). The karyotype of Dorjanthes (4 long and 44 short chromosomes) is different from the Yucca-Agave type, but some similarities are suggested, although difference in chromosome sizes can clearly be detected. The karyotypes of the Agavoideae are generally speaking different from other ones in the Amaryllidaceae and rather resemble those of Yuccae in the Liliaceae.(4) The karyotypes of Alstroenteria (2n=11) and Bornalia (2n=18) in the Hypoxidoideae are similar to those of Haemanthus (2n=16), especially in respect to the SAT-chromosomes.(5) The hypothesis of the SAT-chromosome has been adopted in the present analysis of karyotypes in the Amaryllidaceae and has brought about successful results. Various hypotheses of karyotype alteration were discussed and such karyotype alterations are con-cluded to be genotypically controlled (cf. Levitskij 1937). The genotypic control of karyotype alteration and the secondary balance seem to play an important role in the process cf evolution.(6) The relation between the nucleoli and the SAT-chromosomes was discussed and the hypothesis of the SAT-chromosome was extended to reconcile it with the conception of the nucleolar chromosome. The presence of the SAT-chromosome was emphasized by the observation of satellites or secondary constrictions in many species which had usually been overlooked cr neglected by previous investigators.The writer wishes to express his thanks to Ass. Prof. Y. Sinoto under whose direction this investigation has been carried out.

Chromosome Studies in Cyperaceae, IV

Abstract: 1). The maturation divisions of Scirpus lacustris L. var. typicus Honda f. pictus Honda (2n=39s+1S) and of S. lacustris L. var. Tabernacmontani Trautv. f. zebrinus Makino (2n=42s) have been described. The first plant pictus having one large compound chromosome in a somatic cell, has shown a sort of heteromorphic pairing in the first meiotic division as expected. The last form zebrinus has shown rather regular meiosis.2). In the 1-metaphase of pictus a number of chromosomal configurations have been observed (cf. tables 1, 2); namely, in the first group (i) the compound chromosome S has conjugated with 3 small chromosomes (3s), giving a formula (1S+3s)+(15+n)II+(6-2n)I where n=0-3; in the second group (ii) S has conjugated with 2 small chromosomes (2s), giving a formula (1S+2s)+(15+n)II+(7-2n)I where n=0-3; (iii) in the third group, S has conjugated with only one Small chromosome (s), (1S+1s)+(14+n)II+(10-2n)I where n=0-4; (iv) in the fourth group, S has failed to conjugate with any small chromosomes, (1S+0)+(17+n)II+(5-2n)I where n=0-2; (v) in the fifth, several abnormal Gases were also observed. In Gase of zebrinus, the first division being rather regular, the chromosome counts in the I-metaphase were made easily; 168 PMC's (84%) out of 200 observed were consisted of 21 bivalents.3). The compound multivalents formed in the first division of pictus have shown various mode of segregation in the I-anaphase. This hetermorphic pairs have segregated equationally as well as reductionally, according to the number of chiasmata between the compound chromosome and the univalents attached to it. Lagging chromosomes were observed now and then. The compound multivalents have always separated slowly. This is probably caused by the chiasma formation.4). Chromosome counts in the II-metaphase were difficult. However, a few of them obtained have given some hints to the behaviour of the univalents and of the heteromorphic pairing. Judging from the tables 3 and 7, the univalents observed in pietus may sometimes divide themselves in the I-metaphase, and sometimes pass to the poles at random as it is in fast.5). In the II-anaphase of pictus, remarkable structural hybridity, i.e. formation of chromatin bridges, occurrence of the lagging or precession chromosomes were observed. Chromatin bridges have been considered to have produced from the results of both crossing-over and unusual crossing-over between the compound chromosome and 1-3 small chromosomes attached to the formen. Generally, chromatin bridges have been formed in the first division and rarely in the second. But in the present Gase, the conditions were entirely reversed, i.e. they were not observed in the first division but only in the second.6). In the II-telophase of pictus, chromatin bridges were persistent. However laggards should have reached to the polen in time to he included, for the percentage of the cells containing laggards had decreased as the stage proceeds.7). As a result of irregularities during the meiosis, there must arise various pollen grains containing variated chromosomal constitutions. Unfortunately, the pollen grain division was observed only in zebrinus, where the chromosome numbers counted have varied 18 to 22.8). Test of goodness of pollen grains of 3 types, i.e. typicus (normal self-colored), pictus (variegated form), and zebrinus (variegated form), has shown 99.81% good for typicus, 0% for pictus, and 37.6% good for zebrinus.9). From the present karyological observations it has been shown that the large chromosome in pictus is equivalent to 3 small chromosomes which were usually non-homologous to each other.

Morphology of the Chromosomes of Drosophila ananassae

Abstract: Drosophila ananassae Doleschall (D. caribbea Sturtevant) is widely distributed in tropical regions of both the Eastern and Western Hemispheres (Kikkawa, 1936). Sturtevant (1921) in his study of the North American Drosophilinae recorded the occurrence of D. caribbea in Brazil, Central America, and the islands of the Caribbean Sea. In the autumn of 1933, and in subsequent years, this species was collected at Tuscaloosa, Alabama, which is considerably north of the southern limit of that area in which freezing temperatures may be expected. The repeated occurrence of the species over the period indicated suggests that it may survive the winter in Alabama, rather than be reintroduced annually. Temporary importation of D. ana nassae from the tropics to a more temperate region has been reported by Moriwaki (1935), who collected the flies in Tokyo in 1931, but was unsuccessful in subsequent attempts. The flies breed well in the laboratory under the same culture con ditions commonly employed for D. melanogaster. Stocks of the Tusca loosa material which have been maintained over the past three years were used predominantly in the present study, another stock, secured from Japan, serving for comparison. The chromosomes of D. caribbea were first studied by Metz (1916) from material collected in Panama and Cuba. He described the female complement (oogonial) as consisting of four pairs of V shaped chromosomes, one of which is shorter than the other three. His figures and diagrams of spermatogonial chromosomes show a V-shaped X and a rod-shaped Y. Kaufmann (1936a, 1936b) reported that ganglion cells of the larvae of both the Alabama and the Japanese stocks possess an unequal-armed, J-shaped Y-chromosome. Kikkawa (1936) likewise found a J-shaped Y in spermatogonial cells of his material. In the present article there will be presented a more detailed account of the chromosomes of the ganglia and the salivary glands.

The Nucleolar Cycle in Some Species of Fritillaria

Abstract: 1. In the meiotic prophase of two species of Fritillaria, “cap nucleoli” are formed which persist to the end of meiosis.2. The mitotic nucleoli of these species are normal. The number and positions of the nucleolar constrictions, are given.3. In twenty-four species the meiotic nucleoli are normal, and one species seems to be intermediate.4. The organization of the nucleoli in the species with abnormal behaviour of the meiotic nucleoli is conformable to the principles elaborated by Heitz (1931).5. In both meiotic telophases of all species studied, small globules appear in early telophase at the distal ends of the chromosomes. They are subsequently dispersed over the whole body of the Gell.6. The results are discussed in connection with McClintock's theory of the metabolism of the chromosomal “matrix”.This study has been carried out at the John Innes Horticultural Institution, London. I wish to acknowledge my gratitute to Sir Daniel Hall, Director of the Institution, for granting me the facilities of the laboratory, and to Dr. C. D. Darlington, an whose suggestion this study was undertaken, for the use of his preparations, and for advice and criticism during the work.

Chromosome Complement of Kinugasa japonica with Special Reference to Its Origin and Behavior

Abstract: 1. From the morphology and behavior of the ehromosomes and from the geographical view point, the gametic complement 4 (A+B+C+D+E)=20 chromosomes of Kinugasa japonica was suggested to be composed of 4 different genoms.2. Meiotic chromosome irregularities, fragmentation-fusion, non-pairing, tertiary splitting and regression of the first division were observed.Particular thanks are due to Professor H. MATSUURA who has kindly taken the photomicrographs, giving very helpful suggestions and criticisms.

Relationship Between Various Chromosomal Changes in Drosophila melanogaster

Abstract: From a total of 61 Jethals affecting known loei of the X-chromosome, and induced by X-ray treatment of 2500 to 3000 r-units, 26 or 42.6 per Cent had ehromosomal aberrations such as inversions and translocations. In 92.3 per cent of cases one breakage point of the chromosomal aberration coincided with the region where the lethal change took place. Of 30 visible mutations induced by a similar treatment only one carried a chromosomal aberration. This, however, did not coincide with the region where visible change took place. Data available an 80 spontaneous Jethals show that none was conneeted with either an inversion or a translocation. Among Jethals induced by X-ray treatment, the frequency of such chromosomal aberrations increases with the increase of dosage.