Effect of irradiation on adult nuclei in plants
01 Dec 1957-Genetica (Martinus Nijhoff, The Hague/Kluwer Academic Publishers)-Vol. 28, Iss: 1, pp 143-164
TL;DR: It is worthy of note that as far as differentiated cells in plants are concerned, data on this aspect is significantly lacking, and it has been emphasized recently that the non-meristematic differentiated nuclei undergo endomitosis and thus lie in a highly polyploid state.
Abstract: Within the last few years considerable data has been accumulated on irradiation effects on chromosomes. Though the chromosomes are affected in all the divisional and intermitotic states, the manifestation of the effects become different depending on the stage irradiated (MULLER, 1954). This is specially because in some, restitution of ends are favoured due to certain factors, whereas in o~hers there are a number of factors which stand against such restitution and, therefore, considerable structural rearrangements result. But all these researches have mainly been centered round on normal undifferentiated cells. I t is worthy of note that as far as differentiated cells in plants are concerned, data on this aspect is significantly lacking. It has been emphasized recently, specially by one school of thought (HusKINS, 1947) that the non-meristematic differentiated nuclei undergo endomitosis and thus lie in a highly polyploid state. Experimental attempts to prove the validity of the concept have also been met with success (HuSKINS and STEINITZ, 1948b; D'AMATO, 1950 ; SHaRMA and
Citations
More filters
TL;DR: The results provided the genetic evidence to establish the diploidy of plants with 2n = 40 chromosomes and to support the hypothesis that plants are diploids, triploids and tetraploid, respectively, and that the basic chromosome number of D. alata is x-= 20.
Abstract: Dioscorea alata is a polyploid species with several ploidy levels and its basic chromosome number has been considered by most authors to be x = 10. Standard chromosome counting and flow cytometry analysis were used to determine the chromosome number of 110 D. alata accessions of the CIRAD germplasm collection. The results revealed that 76% of accessions have 2n = 40 chromosomes, 7% have 2n = 60 chromosomes and 17% have 2n = 80 chromosomes. Progenies were produced from 2n = 40 types of D. alata and the segregation patterns of six microsatellite markers in four different progenies were analysed. The Bayesian method was used to test for diploid versus tetraploid (allo- and autotetraploid) modes of inheritance. The results provided the genetic evidence to establish the diploidy of plants with 2n = 40 chromosomes and to support the hypothesis that plants with 2n = 40, 60 and 80 chromosomes are diploids, triploids and tetraploids, respectively, and that the basic chromosome number of D. alata is x = 20. The findings obtained in the present study are significant for effective breeding programs, genetic diversity analysis and elucidation of the phylogeny and the species origin of D. alata.
73 citations
01 Jan 1965
TL;DR: Enough information has accumulated to warrant an examination of the subject and even to outline the broad areas in which the subject may expect to make progress in the immediate future, and physiological and biochemical information is brought together.
Abstract: The organization and development of roots have been well described in morphological and anatomical terms by many authors (v. Guttenberg 1940, 1941, Esau 1943b, 1953a, 1960, Foster 1949) and recent concepts and terminologies with respect to root development have been reviewed and consolidated by Esau (1953 b, 1954) and in vol. III of this encyclopedia1. It is not the purpose of the present chapter to repeat such information. Rather, its purpose is to bring together physiological and biochemical information which bears upon the broad subject of root development and to analyze root organization and development in terms of the physiological and biochemical processes upon which they depend. Our present state of knowledge of the intimate machinery of the cell which, through its intricate and complex workings, controls and directs the course of cellular development, is entirely inadequate to give any clear or definitive picture of the physiological basis of cell organization, let alone the further complexities of such an organized tissue system as the elongating root. However, at our present stage, sufficient information has accumulated to warrant an examination of the subject and even to outline the broad areas in which we may expect to make progress in the immediate future.
43 citations
TL;DR: This document summarizes the main findings of a two-year investigation into the determinants of earthquake-triggered landsliding in Northern Ireland in the period of May 21-23, 1991.
Abstract: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 361 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . 363 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . 380 Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 455 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 487
35 citations
TL;DR: Thirty-three cultivars of yams (Dioscorea sp.) from Nigeria distributed over five edible species were found to display a considerable genetic stability while the cultivated species showed a high degree of polyploidy.
Abstract: Thirty-three cultivars of yams (Dioscorea sp.) from Nigeria distributed over five edible species D . alata (11), D. rotundata (11), D. cayenensis (5), D. dumetorum (4), D. esculenta (2) and twenty-six plants belonging to four different indigenous species D. bulbifera (5), D. preussii (10), 13. hirtiflora (8) and D. schimperana (3) were cytologically investigated for the first time. Chromosome number, size, polyploidy and their role in speciation of the genus are discussed. The wild species were found to display a considerable genetic stability while the cultivated species showed a high degree of polyploidy. Chromosome counts of 2n = 80, for the species D. schimperana and D. cayenensis, and 2n = 60, for 1). rotundata, are new records.
25 citations
01 Jan 1969
15 citations
References
More filters
TL;DR: Limitations also exist in the amount of information which can be obtained from studying histologic sections because of their static nature, and it now appears that progress may be made from the develop men t of radiochemistry of organic substances or the use of radioactive tracer technics including autoradiography.
Abstract: It is obviously true that a better knowledge and understanding of the laws of growth of all types of cells will be necessary before many of the fundamental biologic problems in the fields of cancer research in general and radiation therapy in particular can be solved. The Committee on Growth of the K ational Research Council seeks to obtain information on these and related subjects. At one time, study of tissue cultures seemed to offer distinct possibilities along these lines, but the difficulty of growing cultures of epithelial and lymphatic neoplasms or cellular tissues with scanty stroma presents definite limitations. Limitations also exist in the amount of information which can be obtained from studying histologic sections because of their static nature, and it now appears that progress may be made from the develop men t of radiochemistry of organic substances or the use of radioactive tracer technics including autoradiography. Some of the early observations on the action of radiation on cells were ma...
132 citations
103 citations
58 citations
TL;DR: La distribuzione generale della poliploidia nei diversi strati radicali delle 4 specie e fondamentalmente identica, le cellule pericicicle e procambiali essendo le uniche a mantenersi diploidi in tutti i casi.
Abstract: RIASSUNTOL'A. ha studiato la costituzione cariologica dei tessuti differenziati della radice di 6 specie di Monocotiledoni (Allium sativum, Bellevalia romana, Muscari comosum, Hyacinthus amethystinus, Crinum Makoyanum e C. longifolium), ottenendo stimolazione sperimentale alla mitosi per mezzo di soluzioni diluite di 2,4-diclorofenossiacetato di sodio.Nelle due specie di Crinum i tessuti differenziati radicali sono tutti diploidi, mentre nelle rimanenti 4 specie studiate la differenziazione istologica si realizza per endopoliploidia, il grado piu frequente di poliploidia essendo il 4n. La distribuzione generale della poliploidia nei diversi strati radicali delle 4 specie e fondamentalmente identica, le cellule pericicicle e procambiali essendo le uniche a mantenersi diploidi in tutti i casi.In Allium sativum le mitosi tetraploidi decorrono secondo il tipico schema della mitosi a diplocromosomi, scoperto dal LEVAN (1939) in Allium Cepa, e presentano talora aberrazioni cromosomiche spontanee [scoperte da D'...
38 citations