アマノリ属植物の細胞学的研究

鬼頭, 鈞

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アマノリ属植物の細胞学的研究

https://fra.repo.nii.ac.jp/records/2007253

Item type

紀要論文 / Departmental Bulletin Paper(1)

公開日

2024-06-10

タイトル

アマノリ属植物の細胞学的研究

言語

jpn

資源タイプ

資源タイプ識別子

http://purl.org/coar/resource_type/c_6501

資源タイプ

departmental bulletin paper

アクセス権

metadata only access

アクセス権URI

http://purl.org/coar/access_right/c_14cb

著者

鬼頭, 鈞

抄録

内容記述タイプ

Abstract

内容記述

It is well known that Porphyra has a long history as the most important species among the many marine organisms which are treated as mariculture species in Japan. It is the basis of the special industry called Nori culture in Japan, and extensive progress from the standpoint of its yield has been achieved recently as a result of serious effort by scientists and fishermen. The annual yield today has become more than 6 billion sheets of Nori and more is produced than is consumed in Japan. Under such conditions the new emphasis is improvement of the quality of cultivated Nori. To attack this problem, studies on the gentics and breeding of Porphyra are required. The author has continued cytological studies on Porphyra with the purpose of contributing basic information to these areas of research. Since Ishikawa in 1921 reported cytological studies in Porphyra tenera using light microscope, many observations concerning the thallus stage in some species have been described, however few observations on the conchocelis stage have been made. Especially, clear investigations on the presence of reduction division in the life-cycle have been few, and these studies have been completed quite recently (Giraud and Magne 1968, Kito 1974). Electron microscopic observations on Porphyra have been reported by the present author at first on the cell of the thallus stage of Porphyra yezoensis, but studies on the ultrastructure in the life-cycle in detail have remained incomplete. In the present studies, using a light microscope, nuclear division was observed and chromosome numbers determined in the thallus stage of some species. The results of this work demonstrated that the haploid chromosome number is n=3 in Porphyra amplissima, P. dentata, P. kuniedai P. miniata, P. okamurai, P. onoi, P. pseudocrassa, P. suborbiculata, P. tenera, P. yezoensis, P. sp. no. 1 (Japanese name; Ooba-asakusanori) P. sp. no. 2 (Japanese name; Narawa-susabinori), P. sp. no. 3 (Japanese name; Muroneamanori), n=4 in P. irregularis, P. moriensis, P. pseudolinearis, P. umbilicalis, and n=5 in P. katadai, P. purpurea. All of the species which showed n=3 are monoecious except P. sp no. 3 which is exceptionally dioecious. In addition, n=3 chromosome species exhibit contaminate formation of sexual organs such as antheridial and carpogonial cells on the marginal portion of the leafy thalli in a mosaic configuration. Both species which showed n=5 are also monoecious, however their sexual cells are produced in special form on the thalli i.e., their antheridial and carpogonial cells are separately produced on opposite side of the thallus, divided by a central longitudinal limiting line in a direction perpendicular to the thallus length. Three out of four species which showed n=4 were obviously dioecious, although another species, P. moriensis, could not be clearly determined as monoecious or dioecious. Refering to the relations between chromosome number and monospore formation, all of the species which have been described as capable of releasing monospores showed n=3 in chromosome number. For the purpose of understanding the alternations of nuclear phases clearly, three species, P. pseudolinearis, P. tenera and P. yezoensis were observed cytologically throughout their life-cycle, using materials cultured artificially in vitro. It was clearly confirmed that the macroscpic phase (thallus stage) is haploid and the microscopic phase (conchocelis stage) is diploid in chromosome number. Also the critical diplonema and diakinesis stages which appear characteristically only at meiotic division, were observed at the divisions leading to the formation of conchospores in these three species. From these results reliable conclusions concernig the long term uncertainty about the time of onset of meiosis in the lifecycle were clearly confirmed concurring with recent reports. Through observing continuously the developing process of carpospore germlings and conchosporangia, a few characteristic differences among the three species mentioned above were cytologically recognized. In P. pseudolinearis the carpospore-germling makes a primary and thick germtube which develops at first from the original spore then changes its shape to a pear-like formation. Finally, from the top of the primary germtube a secondary thin germtube is developed. In addition to these species characteristics, the first nuclear division at germination in a carpospore can be observed in its primary germtube. On the other hand in P. tenera and P. yezoensis the thin germtubes are developed from the original spore directly, and are the same diameter as that of the conchocelis filament. The first nuclear division is performed in the space of the original spore. In conchospores formation, P. tenera and P. yezoensis produce conchosporangial cells arranged on a duplicate line along the longitudinal axis of a conchosporangium. In P. pseudolinearis however the cells are arranged on only one longitudinal line. Additonal information concernig the morphological differences in the carpogonial cells at fertilization in these three species were also obtained. In P. fenera and P. yezoensis carpogonium produce one protuberate prototrichogyne either from the end of a cell or two from the each end of a cell. In these species, at the time of fertilization the fine canal is developed from the top of the protuberance to the thallus surface, following which the spermatia becomes attached to the top of the fine canal. On the other hand, in P. pseudolinearis the protuberate prototrichogyne is not formed, but only fine canals are developed from the carpogonium directly at the time of fertilization. In the present study ultrastructural differences among cells from different parts of the life-cycle of P. pseduolincaris and P. yezoensis as well as ultrastructural differences among the vegetative cells of four species of Porphyra belonging to three subgenera were examined. First ultrastructural comparisons of the four species belonging to three different subgenera are described. In the two species, P. pseudolinearis and P. yezoensis, of the subgenus Porphyra the chloroplasts, which have one pyrenoid in the center, exist in the center of a cell and occupy almost the total volume of the cell. Thylakoid layers are arranged methodically in the shape of concentric circles. The nucleus, mitochondria and other cell organelles exist in the cytoplasm outside of the chloroplast. In cells of P. pseudocrassa of the subgenus Diplastidia, two chloroplasts are located near each surface in a cell, and each chloroplast has one pyrenoid in the center. Thylakoids of the chloroplast are arranged regularly in a direction perpendicular to the thallus surface. The nucleus is located in the center of the cell, but almost all the cytoplasm is distributed near the chloroplast. In cells of P. amplissima of the subgenus Diploderma, each cell has one chloroplast near the surface, and almost all the cell organelles exist around this chloroplast. About one-thrid to two-thrids of the volume of a cell is occupied by a large vacuole. The chloroplast has one pyrenoid and its thylakoids are arranged regularly in a direction parallel to the thallus surface. The ultrastructural characteristic of different kinds of cells at different stages through the life-cycle is given as under. In the spermatangial cell in the process of spermatia formation, all the cell organelles, except nucleus and mitochondria, began to be simple in shape. The chloroplast especially is composed of only a few thylakoids which become swollen in shape and its has no pyrenoid. Many ribosome-like granules become to be observed stiking on the outside surface of the nuclear membrane. In the spermatangial cells which is just before its releasing from the thallus or in the spermatium, all the cell organelles are broken and in the process of disappearing except only the nucleus, in addition, many small pithy vesicle which seem to appear in the process of vacuole formation are observed. The nucleolus in the nucleus is observed remaining at the same stage of the chromatin stage. In the carposporganial cells which are in the process of carpospore formation, a lot of small pithy fibrous vesicles which seem to have closely related to the endoplasmic reticulum and many large fibrous vacuole-like structures which seem to be orignated in dictyosomes are observed. And, the substance of the small pithy fibrous vesicle is secreted as the components of outerlayer of the cell wall which is considered as the mucilage of the spore, and the substance of the large fibrous vacuole-like structure is secreted as the components of the inner layer of the cell wall. In the filamentous cell of conchocelis stage the nucleus is very irregular in shape, although it is nearly round in the cell of the thallus stage. Also the number of the thylakoids in the chloroplast is very small compared with that of the cells of the thallus. From observations on the conchocelis stage, which are similar to those described by Cole and Conway (1977), peripheral thylakoids and pit-connections were recognized in both P. pseudolinearis and P. yezoensis.

言語

書誌情報

ja : 東北区水産研究所研究報告
en : Bulletin of Tohoku Regional Fisheries Research Laboratory

巻 39, 号 tnf_k_39_29, p. 29-84, ページ数 56, 発行日 1978-03

出版者

東北海区水産研究所

言語

出版者

Tohoku Regional Fisheries Research Laboratory

言語

ISSN

収録物識別子タイプ

PISSN

収録物識別子

0049-402X

書誌レコードID

収録物識別子タイプ

NCID

収録物識別子

AN00167637

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アマノリ属植物の細胞学的研究

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