摘要:

SUMMARYThe process of chloroplast division during mitosis inChlamydomonas reinhardiis followed with the electron microscope. The pyrenoid and the chloroplast reproduce by fission. The dividing chloroplast contains regions of dense material that superficially resemble pyrenoids, but it is concluded that the formation of the dense material is not related to pyrenoid formation inC. reinhardi.The dense material appears to be localized over regions of chloroplast DNA.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02348.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1970.00003.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe amounts of extracellular dissolved organic phosphorus (DOP) produced by 8 species of marine planktonic algae under various conditions of light, salinity, and nutrition were compared. Large amounts, more than 20% of the total P in the system, were excreted byCyclotella cryptica, Thalassiosira fluviatilis, Dunaliella tertiolecta, andSynechococcusunder 1 or more of the experimental conditions. Excretion of DOP was proportional to light intensity inDunaliella, Rhodomonas, Chlorellasp., andCoccolithus huxleyi.Phosphorus limitation reduced DOP production byCyclotellaandThalassiosira, nitrogen limitation reduced DOP production byPhaeodactylum, Dunaliella, andRhodomonas, and lack of iron reduced DOP levels inCyclotellacultures. Salinity affected growth, but no clear relationship to DOP excretion was evident. The DOP eliminated during growth was reassimilated by the species that produced it and by other species, but lack of alkaline phosphatase reduced the amount of DOP that was available to certain algae.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02349.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe fine structure of the pyrenoid in the mature vegetative cell ofTetracystis excentricaBrown and Bold is described. During zoosporogenesis, the pyrenoid undergoes regression, and the ultrastructure of this process is described in detail. The ground substance undergoes dissolution, and reticulate fibrillar structures appear as well as intruding chloroplast thylakoids. Pyrenoid‐associated starch plates diminish, and quantities of starch not associated with the pyrenoid are produced. New pyrenoids appear late in the division cycle after all other major organelles associated with the motile cell have been formed. Zoospore pyrenoids develop in thylakoid‐free spaces of the chloroplast which are similar to the DNA‐containing regions. The new pyrenoid ground substance, which is loosely fibrillar, arises in close proximity to starch grains which may be formed in the stroma. Then the zoospore pyrenoid produces 2 hemispherical starch plates identical to those in the mature vegetative cell. Zoospore pyrenoids lack the 2 convoluted thylakoids between the starch plates and the ground substance characteristic of those in the mature vegetative cell. Instead, the thylakoids are identical to those of the chloroplast at first, and then develop into a convoluted state in the vegetative cell. Cytochemical tests for DNA, RNA, and protein were made for the cytoplasm, nucleus, nucleolus, and pyrenoid. Conclusive evidence is presented for the presence of RNA in the cytoplasm and nucleolus, DNA in the nucleus, and protein in the pyrenoid. The tests did not conclusively demonstrate the presence or absence of DNA and RNA in the pyrenoid; however, they suggested that small amounts of both DNA and RNA may be pr

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02350.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe ultrastructure of theConchocelisor filamentous stage ofPorphyra leucostictawas investigated. Each cell contains 1 or 2 parietal, stellate chloroplasts with a single pyrenoid in each chloroplast. The centrally located nucleus is irregularly shaped and contains 1–2 nucleoli. The cytoplasm has typical floridean starch grains and nonmernbrane‐bound lipid bodies. The cell wall is divided into an outer and an inner wall. Many lomasomes are associated with the cell membrane. Pit connections are found between cells, and their taxonomic significance is discus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02351.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYMinimum phosphorus requirements of 2 marine diatoms,Cylindrotheca (Nitzschia) closteriumandCyclotella nana, were measured in axenic steady state chemostat culture.C. closteriumandC. nanarequired 1.055 and 1.045 × 10−15g‐at P cell−1generation−1, respectively, with an average cell doubling time of 0.20 divisions/day. The algae were cultured at 15.5 C and exposed to 5380 lux on a light‐dark cycle of 19 hr‐5 hr. The phosphorus requirement per unit of cell volume was 0.0135 and 0.0129 × 10−15g‐at P/μ3of cell volume forC. closteriumandC.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02352.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe fine structure of 3 members of the genusCryptomonas, C. rostrella, C. reticulata, andC. calceiformis, has been examined. These species exhibit the features typical of the class Cryptophyceae. The presence of subpellicular trichocysts causes a regular folding of the periplast, and larger trichocysts are present within the gullet. The plastid contains thylacoids arranged in pairs and a prominent pyrenoid; both structures are enclosed in 4 membranes, the outermost of which is a rough endoplasmic reticulum. The nucleus, Golgi apparatus and the Corps de Maupas occupy characteristic positions within the cell, and are the most characteristic features. All these structures indicate that this algal class occupies a unique phylogenetic position.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02353.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYA new species of red algae,Boldia angustatasp. nov., was discovered near Tuscaloosa, Alabama, during the spring of 1968. It differs significantly from the only previously described species,Boldia erythrosiphonHerndon, in length and width of young and mature thalli, cell size, shape of nuclei in first‐order cells, shape of intercalary filaments, morphology of filaments derived from monospores, ontogenetic development of erect plants, morphology of the basal system, and regularity of first‐order ce

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02354.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYSpirogyraandClosteriumexhibit active motility. This motility is associated with the secretion of pectic mucilage from the cells. The gliding of these cells is not directed toward light but photosynthesis is the energy source for it. The secretion of mucilage causes olderClosteriumcultures to become thick gelatinous clusters.Spirogyrafilaments when undisturbed grow to form thick multistranded rings. This growth pattern might result from the tendency of the filaments to rotate on their long axis.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02355.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY

摘要:

SUMMARYDictyocha fibulawas cultured in an enriched seawater medium from collections taken at Edmonds, Washington. The optimum temperature for growth is 10 C at salinity 24% and 160 ft‐c illumination in Provasoli enriched seawater at the concentration of 7.5 ml/liter seawater. Average generation time is 49 hr. In addition to swimming cells with skeletons, swimming cells without skeletons and nonswimming coenocytes were observed in clonal cultures at 15

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1970.tb02356.x

出版商:Blackwell Science Inc    

年代:1970

数据来源: WILEY