摘要:

SUMMARYUltrastructural examination of the unicellular red algaPorphyridium purpureumhas revealed cytoplasmic and nuclear inclusions termed concentrosomes. These bodies are morphologically distinct from the irregular membranous inclusions previously reported by others as concentric bodies. In thin section, the morphology of concentrosomes varies from a simple set of 3 or 4 (or rarely 5) concentrically arranged, electron‐opaque, circular profiles to elongate, sinuous forms and particulate aggregations, the majority clearly within the nucleus but separated front the nucleoplasm by what appears to be the nuclear envelope. Although simple concentrosomes may be observed in either the cytoplasm or the nuclei, the more elaborate forms occur only in nuclei. In addition to the concentrosomes, subspherical to polygonal virus‐like particles of approximately 40 nm diameter have been observed inP. purpureum.These particles are characterized by an electron‐opaque perimeter that, in approximately equal numbers, surrounds an “empty” or an opaque core. Dense arrays of the virus‐like particles appear in the cytoplasm but not in the nuclei. Similarities between certain forms of the concentrosomes and the virus‐like particles are suggestive of an ontogenetic relationship. The infrequency with which either the concentrosomes or the virus‐like particles are observed has hampered attempts to verify a developmental sequence or to establish unequivocally the infectious nature of the virus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04066.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYAcid spring effluents are often covered with mats of the eucaryotic phycocyanin‐containing alga.Cyanidium caldarium.The primary bacterial component of such mats is an acidophilic strain ofBacillus coagulans, and the primary fungal component isDactylaria gallopava.Because of the limited species diversity,C. caldariummats appeared to be an excellent system for studying algal excretion and various microbial interactions in nature. From 2 to 6% of the NaH14CO3taken up by natural or laboratory populations of the alga was excreted as14C‐labeled materials. The maximum excretion occurred at temperature, light, and pH values optimum for NaH14CO3uptake. However, when excretion was expressed as a percentage of NaH14CO3uptake, a higher percentage of the radioactivity was excreted at nonoptimal conditions for NaH14CO3uptake. Fungal biomass was directly proportional to algal density, but bacterial numbers varied widely and did not correlate with algal numbers. The bacterial and fungal components could be grown in mixed culture with either growingC. caldariumcultures or in an extract prepared, by healing algal ce

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04067.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe results of previous research and a present survey of some of the cytological characteristics of 18 additional genera and 34 additional species are presented and discussed from the viewpoint of phylogenetic and taxonomic significance. A preliminary attempt is made to place these, algae, in 4 orders on the basis of comparative cytology, and in particular on the basis of variation in mitosis and cytokinesis and the distribution of plasmodesmata. Consideration is given to the evolution of the phragmoplast and to the hypothesis that the Chaetophorales are related to the ancestry of land plants.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04068.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe first evidence of conceptacle formation in male and female plantsof Bossiella californicassp.Schmittiiis the secretion of a cap below the epithallium. Subsequent development involves the disintegration of the upper enucleate parts of cortical cells below the center of the cap concomitant with the growth of tissue surrounding these cells. Protoplasts in the lower parts of these cortical cells recover and become initials of reproductive cells. Differentiation of each initial in female plants results in a supporting cells bearing 1 or 2, 2‐celled carpogonial filaments, and in male plants results in a basal cell bearing 2 or 3 spermatangial mother cells which bud off spermatangia. Following fertilization, supporting cells fuse and form a broad, thin fusion cell from the upper surface of which gonimoblast (carposporangial) filaments aris

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04069.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe uptake of amino acids byNitella flexilishas been investigated. Influx of glycine, alanine, and valine appears to be a diffusive process. Influx ranged from 0.14 to 0.06 and 0.04 pmoles/(cm)(sec), respectively. Aspartic acid uptake is an active transport mechanism. TheVmaxis 2.8 pmoles/(cm)(sec); the transport constant (Michaelis constant)Km, 7.8 × 10−3M. The uptake of arginine is apparently due to 2 transport systems, one with aVmaxandKmof 3.1 pmoles/(cm)(sec) and 3.2 × 10−3M, respectively. The second system has aVmaxof 1.4 pmoles/(cm)(sec) and aKmof 2.1 × 10−4M. The possibility that the second system is diffusive has been co

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04070.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA previously undescribed species ofEuglena, E. myxocylindracea, sp. nov., is described from soil in a garden and in a while pine woods in Pike County, Pa. In addition to the, type, an organism (No. 457) in the Culture Collection of Algae. Indiana University, hitherto designatedE. viridisvar.terricola.is transferred toE. myxocylindraceaas var.terricola.Differences such as the usual absence of an emergent flagellum, or the presence of an extremely short one (ca. 3.5–4 μ), and the dominance of a palmelloid state in a variety of liquid and solid culture media in which the cells secrete dichotomously branching slimy cylinders distinguish the new species fromE. virid

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04071.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYUnialgal, nonaxenic cultures ofVacuolaria virestcensCienkowsky were grown in soil‐water medium, in simple salt solutions with added peat and soil extract, and in synthetic medium. Doubling times in different media were determined: maximum growth rate (doubling time = 46.0 hr) was obtained in continuous light (210 ft‐c) at 24 ± IC. Gonyostomum semen(Ehrenberg) Diesing was isolated from a natural population and grown in soil‐water medium and a synthetic medium. Other techniques that have been used for culturing chloromonadophycean algae are re

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04072.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYMeiospores ofLaminaria saccharinalabeled with a fluorescent stain were put into the sea and recovered at frequent intervals. They developed into gametophytes which produced gametes throughout the year. Antheridia were produced earlier than oogonia. Gametogenesis was slowest during the late autumn and early winter. On the basis of nutritional studies and the seasonal distribution of nutrients, it was concluded that the rate of gametogenesis was not due to nutrient deficiency but most likely to light.Production of macroscopic sporophytes appeared to be limited by survival of microscopic sporophytes rather than gametogenesis. Macroscopic sporophytes became evident during the late winter and autumn. The greater light and perhaps higher temperatures of summer were suggested as agents limiting macroscopic sporophyte production during this period.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04073.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe diatom speciesGomphonema parvulumKütz. was isolated, grown in culture, and the details of the internal organization studied by light and electron microscopy. The organism is usually identified from its frustular morphology, but members of the genusGomphonemacan be separated from other naviculoid forms by the H‐shaped chromatophore, whose lobes are connected on 3 sides across the center of the cell, and also from the position of the pyrenoid. This is situated, on the inner side of the chromatophore and is not embedded in the center of the chromatophore. New observations of this pennate diatom include details of the periplastidial network, of the Golgi vesicular activity, and of the storage produc

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04074.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY

摘要:

SUMMARYSkeletonema costatumwas grown in silicate‐limited continuous culture, Culture conditions resulted in synchronization of sexual reproduction. A detailed description of the life cycle is presented. During the life cycle growth rules varied from 0 to 0.12 hr−1. Sexual reproduction in diatoms has often been observed in batch cultures and some stages have been reported in nature. However, this is apparently the first report of its occurrence in continuous culture. Other experiments that demonstrate the importance of sexual reproduction in continuous culture work tare discus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1973.tb04075.x

出版商:Blackwell Science Inc    

年代:1973

数据来源: WILEY