摘要:

SUMMARYA defined medium was developed for 3 strains of Pandorina morum. The strains tested required no vitamins or other organic compounds. The optimal initial pH was between 7.0 and 8.0. Various carbon sources were tested, and only glycolate and acetate appreciably stimulated growth. Mixotrophic growth in the light was stimulated by glycolate in all 3 strains, and by acetate in strains 880 and N76‐6. Only strain N76‐6 utilized acetate for heterotrophic growth in the dark. Thirty strains ofP. morumof world‐wide distribution were surveyed for mixotrophic and heterotrophic growth with acetate. All were found to fit 1 of 3 classes with respect to acetate metabolism: (1) no effect in light or dark; (2) stimulation of growth in light only; (3) stimulation of growth in light and

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01485.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYThree cultured species ofPyrocystis(Dinoccoccales) reproduced asexually by forming 2 (or 1) aplanospores or zoospores inside the parent cell wall. In all 3 species these small reproductive cells, although they may not resemble the parent cells, swell up rapidly (∼ 10 min) to the approximate size and shape of the parent cell. These swollen cells become new vegetative cells. The above asexual process is the only way by which cells numbers increase in our cultures.Pyrocystis lunulawas propagated at the lunula stage of the life cycle. The nonmotile crescent‐shaped cells produced reproductive cells that wereGymnodinium‐shaped and had, in some cases, a trailing flagellum. WithP. fusiformisandP. noctiluca, the reproductive cells were not flagellated. WithP. fusiformis, these bodies had a pronounced equatorial constriction like a girdle, while inP. noctilucathe “girdle” was an inconspicuous feature if present. WithP. noctilucaandP. fusiformison a 12:12ldcycle, reproductive cells were formed early in the dark period and they swelled up at the beginning of the light period. Reproduction ofP. lunulawas not well phased in our experiments, with reproductive cells developing at the end of the light period and the end of the da

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01486.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYTwo species of blue‐green algaeAnabaena flosaquaeandOscillatoriasp. were shown to assimilate glycolic acid. In the presence of DCMU in light, approximately 50% of it wax oxidized to carbon dioxide; 90% was oxidized in the dark. Glycolate assimilation was increased fivefold by lowering the pH of the medium from 9.0 to 5.0, and the rate of uptake increased with increasing concentration of exogenous glycolate up to a saturation concentration of 12–14 mM. α‐Hydroxysulfonates markedly inhibited glycolate uptake and oxidation but iso‐nicotinyl hydrazide had little effect. These results indicate that glycolate oxidation occursin vivo, but that the glycolate pathway in these algae differs some‐what from that of hig

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01487.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe fine structure of vegetative cells, sporogenesis, and zoospores of the xanthophycean algaPseudo‐bumilleriopsis pyrenoidosais described. Cleavage in sporogenesis closely resembles that of certain aquatic fung

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01488.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe fine structure of the primary nucleus inBryopsis hypnoideswas compared with that of the primary nucleus inAcetabularia calyculusandBatophora oerstedii.InBryopsisthe mature primary nucleus contains a peripheral reticulum composed of 4–6 layers of 200 A diameter fibrils. The nuclear membrane has numerous nuclear pores that are located adjacent to the openings in the layers of the reticulum. Each nuclear pore is constituted of peripheral globular elements and a central granule. Although pores of similar structure are present in the nuclear envelope ofAcetabulariaandBatophora, a fibrillar reticulum is absen

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01489.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYCarbon replicas of the skeletons of a cultured clone ofDictyocha fibulareveal a surface pattern of bands 4–5 nm wide. Reticular ornamentation previously reported for fossil skeletons is not present. Skeleton formation may proceed from an initial series of dichotomous outgrowths of an elongate, formative vacuole; which later fuse at junctures of the basal ring and supporting bars. The presence or absence of an apical ring may be a function of variation in the duration of the synthetic stage of predivision among individuals within the same clon

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01490.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYDictyocha fibulain exponential phase cultures displays a range of morphological variants of which the “sunburst” is most common. In this form, the perinuclear cytoplasm (perikaryon) contains an average of 72 dictyosomes, assorted vesicles, mitochondria, endoplasmic reticulum, and ribosomes. Cytoplasmic processes, globose to irregular, extend on fine cytoplasmic strands from the perikaryon into an extensive, viscous wall, structureless in electron micrographs except for scattered electron‐opaque leaflets near the perikaryon. Mitochondria with tubular cristae occur within the globose process and occasionally within the connecting strands. Chloroplasts, with 3‐disk lamellar bands and with pyrenoids not crossed by lamellae, are confined to the cytoplasmic processes in the sunburst from. A structure which may be the “flagellum” occasionally occurs attached to the perikaryon. However, no flagellar structures containing microtubules, nor flagellar root structures, have

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01491.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYGliding is an active movement displayed by a microorganism in contact with a solid substrate where there is no evidence of a motility organelle or of a conformational change in the organism. Gliding may be accompanied by rotations, reversals, flectional activity, and mucilage sheath production, as well as linear translation. Previous explanations of the mechanism responsible did not consider all these aspects of behavior.The gliding behavior and ultrastructure of the blue‐green algaOscillatoria princepsVaucher were examined.O. princepshas a maximum observed gliding rate of 11.1 μm/sec. The trichomes can glide in either longitudinal direction following rapid and occasionally frequent reversals. Right‐handed trichome rotation was always observed, which means that any surface point on these trichomes traces a 60‐deg right‐handed helix. A mucilage sheath envelopes the moving trichomes. The rate of gliding was reduced by viscous substrates, extreme pH, lysozyme, DNP, and cyanide, while sustained darkness had no inhibitory effect.Ultrastructurally, the cell wall is composed of an L‐1 layer which is 10 nm thick and often ill‐defined. The L‐2 layer which is outside this is 200 nm thick and participates in septum formation. The L‐3 layer is outside the L‐2 and is continuous over the trichome surface. The L‐4 “membrane” lies outside the L‐3 layer. Grazing surface sections and freeze‐etch replicas show a parallel and tight array of 6–9 nm wide continuous fibrils in the cell wall on the surface of the distinctive L‐2 layer. Isolated wall fragments were tightly coiled inside out with the fibrils on the inside. The angle of orientation for the fibrils was to the right in a helix with a pitch of 60 deg.O. animalis, a blue‐green alga with a movement tracing a left‐handed helix, showed a similar array of fibrils oriented in a left‐handed helix with a pitch of 60 deg.It is proposed that gliding is produced by unidirectional waves of bending in the fibrils which, act against the sheath or su

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01492.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe green algal genusBlidingia(Ulvales), reported for the first time in California only 4 years ago, is now found to be fairly widely distributed there asB. minima(Nägeli ex Kützing) Kylin var.minima. B. minimavar.subsalsa(Kjellman) Seagal is now recorded for California.Ulva vexataSetchell and Gardner[Enteromorpha vexata(Setch.&Gardn.) Doty]is reduced to varietal status asB. minimavar.vexata, and is reported, to be found in 2 ecological forms. Forms with expanded, ulvoid blades are common to exposed localities and is the form described by Setchell&Gardner. Smaller, narrower, enteromorphoid forms are found near river mouths and are the kind referred to by Doty. There are many intermediate forms of this variety.Characters which are used to separateBlidingiafromEnteromorphaare critically evaluate

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01493.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY

摘要:

SUMMARYSkeletonema costatumandCoccolithus huxleyiwere grown in nitrogen‐limited chemostat cultures with illumination provided in light/dark cycles.S. costatumassimilated nitrate and ammonium primarily during the day and less so at night. Conversely, the concentration of nitrate and ammonium in the culture medium varied periodically, increasing at night and decreasing in the light.C. huxleyiassimilated both N sources at a rate sufficient to keep them at very low levels both day and night. However, the activity of N‐assimilating enzymes, measured in cell‐free extracts, were higher in the light than in the dark periods, implying light/dark differences in the capacity to assimilate nitrogen. Such periodicity in the rate of uptake and enzymatic activity appears to complicate the mathematical expression of nutrient‐limited growth of phytoplankton exposed to natural light/dark cycles.Three aspects of dial periodicity in N assimilation have been observed in natural phytoplankton communities in the sea: (1) in assimilation rate, (2) in activity of enzymes of N‐assimilation, and (3) in the ammonium concentration of the seawater. The cultures also showed periodicity in these parameters and appear to be useful model systems

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1971.tb01494.x

出版商:Blackwell Science Inc    

年代:1971

数据来源: WILEY