摘要:

SUMMARYChlorococcum echinozygotumStarr was grown in a modified Bristol's solution, and in the same medium in which strontium had been substituted for calcium. After 3 and 6 weeks growth, cells were transferred to fresh Bristol's solution overnight to initiate motile cell production. Dividing cells were fixed in 2.0% K permanganate, and embedded in Epon. The ultra‐structure of several stages in the life history of the organism is described. Light and electron microscopic observations indicate that progressive cleavage of the protoplast occurs, as well as the previously reported successive bipartitioning. A Sr replacement for Ca in the growth medium apparently has no demonstrable effects on the development of cell organelles inC. echinozygotum.Many investigators have contributed to our understanding of the ultrastructure of the algae(1,4,5,6,7, 8,15,16).Studies of vascular plants(9,19)and algae(11,12,13)indicate that cells and cell organelles do not develop normally when some elements are lacking. This study reports observations on the ultra‐structure of several stages in the life history of the alga,C.hlorococcum echinozygotumStarr, which was grown in a modified Bristol's solution(3)and in the same medium with strontium substituted for calc

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04565.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe effects of non‐ionic, anionic and cationic detergents on 12 species of marine phytoplankton lucre observed. Although individual species varied widely in response, growth inhibition in non‐ionic surfactants became more pronounced as the surface‐active properties of the agents tested increased. The tolerances of species belonging to the same family were generally similar, and each family had a specific inhibition pattern. Anionic detergents inhibited growth in concentration ranges that depended on the species and the surfactant. All species were more sensitive to the cationic agent than to anionic or non‐ionic agents. The significance of these results was di

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04566.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe morphology and ontogeny ofThorea riekeisp. nov. from a spring‐fed stream in Landa Park, New Braunfels, Texas, are described. The organism was isolated into unialgal culture and grown through its complete life history, stages of which are illustrated by photomicrographs. Comparative studies were made of herbarium specimens ofThoreaspecies from several United States herbaria. A review of the taxonomic literature on the genusThorearevealed a considerable number of inaccurate and doubtful determinations of herbarium specimens. A brief study of the ultrastructure ofT. riekeiis include

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04567.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe carotenoids of nine heterokonts grown in axenic culture, Vischeriasp., Heterococcus fuorensis, Bumilliopsis brevis, Ophiocytum majus, Chlorocoster engaginalis, Heterothrix debelis, Tribonema aequale, Chloriclella neglecta,andBotrydiopsis alpina,are qualitatively the same. The pigments have been identified as β‐carotene and three xanthophylls, antheraxanthin, lutein5,6‐epoxide and an unidentified compound which is possibly a hydroxy derivative of lutein, 5,6‐epoxide, trollixanthin. The significance of these observations in relation to algal phylogeny is briefly dis

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04568.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe fine structure of three species ofSpirogyrais presented, utilizing bright field, polarized light, and electron microscopes; x‐ray diffraction; and autoradiographic techniques. The birefringent filament wall consists of an outer amorphous layer covering Cellulose I microfibrils in a multinet growth pattern. Vegetative cytoplasmic fine structure is typical of the Chlorophyta with the exception of karyoids which are described. Autoradiography indicated spots on the conjugating filament walls corresponding to developing conjugation papillae. Conjugation tubes possess a cell wall of microfibrils in a reticulate pattern. During conjugation removal of papillae cross walls was observed. This wall breakdown appears to be controlled by vesicles released from the cytoplas

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04569.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYVarious stages of heterocyst development inAnabaena azollaegrowing withinAzolla filiculoideswere viewed with an electron microscope. Developing heterocysts undergo marked internal and external reorganization which cannot be detected with light microscopy. The proposed sequence of developmental stages includes: (1) formation of a thick, two‐layered envelope; (2) contortion of photosynthetic lamellae; (3) loss of granular inclusions and possible loss of or change in nucleoplasms material; and (4) concentration of photosynthetic lamellae toward the poles. These findings are compared with those reported by Wildon and Mercer in 196

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04570.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe chlorophytan alga, Sirogonium melanosporum,is a member of the Zygnemataceae and superficially resembles certain species ofSpirogyra.Clonal cultures ofS. melanosporumwere isolated from a natural collection obtained near Guaymas, Mexico. In Pringshei?n's soil‐water medium with a light intensity of 3,500 lux at 22 ± 2 C, cultures of the alga produce a netlike growth which results from the genuflexion of filaments and the onset of the sexual process. The clones studied are homothallic with a totally anisogamous mode of reproduction. The major events of the sexual cycle, including gametangial development, gametic formation, syngamy, and the germination of zygospores, were observed forS. melanosporumand compared with an early account of sexual reproduction inS. stictic

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04571.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYNumerous long and delicate appendages, called bristles, have been detected on several species and strains ofScenedesmus.There are frequently over 100 such processes per coenobium. They are more commonly observed on the spine‐bearing species and are found on coenobia resemblingS. quadricaudaboth in nature and in culture. Only a fewS. obliquuscultures have shown these processes. Because they are much more delicate than spines, and because they are removed when coenobia are brought through an alcohol series, the bristles have been observed rarely in the past. A procedure for the detection of the appendages is presente

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1965.tb04572.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY