摘要:

ABSTRACTIn the North Atlantic over a wide geographic region that includes various oceanic regimes and a temperature range from 10 to 22° C, an increase in the number of nondividingSynechococcuscells (X) was generally accompanied by a greater‐than‐proportional increase in the number of dividing cells (Y). As a result, the fraction of dividing cells (FDC = Y · (Y + X)−1) was positively related to population size (Y + X). Recognizing that FDC is generally greater in a rapidly growing population than in a slowly growing one, our empirical finding implies a positive correlation between specific growth rate and standing stock forSynechococcus.One notable exception occurred during winter (T<5°C) in a eutrophic coastal embayment when a decrease in cell abundance was not matched by a decreas

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00559.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTCulture strains ofEmiliania huxleyi(Lohmann 1902) Hay et al. 1967 were placed into two groups designatedE. huxleyitype A and type B on the basis of coccolith morphology and immunological properties of the coccolith polysaccharide. We studied the distribution of these types in the North Atlantic region using an indirect immunofluorescence assay with antisera directed against the coccolith polysaccharide ofE. huxleyitype A and type B and epifluorescence microscopy. In field samples taken in the Northeast Atlantic Ocean,E. huxleyitype A was found exclusively. In contrast, type B was dominant in the North Sea. Scanning electron microscopy of the samples revealed the same unequal distribution of the two types as found with the immunofluorescent‐labelling assa

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00566.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTEach of four clones from theSynura peterseniicomplex was grown at different pHs (5.5, 6.5, 7.5, 8.5) in batch culture experiments. Growth response curves and exponential growth rates were compared among clones and pH treatments in order to examine growth trend variation among the clonal groups. The clones were isolated from geographically distant North American localities. The clonal groups represented distinct mating types, an isolate and its subisolate, andS. petersenii‐andS. glabra‐like scale morphologies. No consistent relationship existed between growth response curve, and culture medium pH. Additionally, the trends across time differed according to clone and pH combination. Pairwise comparisons of linear trends from transformed growth response curves indicated two distinct clonal associations. Although the clonal associations corresponded with the final cell density of the cultures, growth response curves did not correspond with mating type, the parent‐isolate and subisolate, or scale morphology. Clones withglabra‐like scales had greater growth rates than the clone withpetersenii‐like scales. The conflicting results generated from growth response curve and growth rate analyses support the concept thatS. peterseniiandS. glabraform a highly variable, homogeneous

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00570.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTIn N‐limited continuous chemostat cultures of the green algaHaematococcus lacustris(Gir.) Rostaf. (UTEX 16), the steady‐state astaxanthin content of the cells was determined by the specific growth rate of the cultures. The highest, pigment content was obtained at the lowest dilution rate. The specific rate of astaxanthin accumulation was, however, a function of the photon flux density measured at the illuminated culture surface. In nongrowingHaematococcuscultures, the specific rate of astaxanthin accumulation was determined by the growth rate of the culture during growth phase. The highest possible cellular astaxanthin content of all cultures was comparable and independent of the culture paramet

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00575.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe marine cryptophytePyrenomonas salinaSantore is capable of autotrophic and heterotrophic nutrition. We studied the physiological and ultrastructural changes that accompany the shift between these nutritional modes. The addition of glycerol to batch cultures ofP. salina,grown at an irradiance limiting for photoautotrophic growth, increased its growth rate and induced specific biochemical and structural changes in its photosynthetic system. Results from extracted pigment analyses, thin‐section electron microscopy, and freeze‐fracture electron microscopy indicated that glycerol addition reduced the cell phycoerythrin content, phycoerythrin to chlorophyll a ratio, degree of thylakoid packing, number of thylakoids · cell−1, and PSII particle size. These properties were reduced to a similar extent in cells grown photoautotrophically under an irradiance saturating for growth. These results are consistent with the hypothesis that enhancement of heterotrophic potential occurs at the expense of light‐harvesting ability in glycerol‐grow

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00578.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTSynchronously dividing cells ofChlamydomonas reinhardtiiDang. (Chlorophyta) produce a single peak of cyclic adenosine monophosphate (cAMP), about sevenfold above the basal level, at the time of onset of the flagellar shortening that precedes mitosis. Cultures of a spontaneous palmelloid variant (which forms flagella‐less cell clusters) ofC. reinhardtiiproduce up to 15 times more cAMP per gram fresh weight of cells than do cultures of normalC. reinhardtii.Revertants from the palmelloid phenotype to the normal phenotype exhibit the low levels of cAMP characteristic of normalC. reinhardtii.Thus, elevation of cAMP level and decreased ability to form or maintain flagella are closely related phenomena. We propose that flagellar assembly/disassembly is regulated by endogenous cAMP inC. reinhardti

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00587.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTCultures and field samples of the toxic dinoflagellateGymnodinium catenatumGraham from Tasmania, Australia, were analyzed for pigment, fatty acid, and sterol composition.Gymnodinium catenatumcontained the characteristic pigments of photosynthetic dinoflagellates, including chlorophylla,chlorophyllc2,and the carotenoids peridinin, dinoxanthin, diadinoxanthin, diatoxanthin, and β,β‐carotene. In midlogarithmic and early stationary phase cultures, the chlorophyllacontent ranged 50–72 pg · cell−1, total lipids 956–2084 pg · cell−1, total fatty acids 426–804 pg · cell−1, and total sterols 8–20 pg · cell−1. The major fatty acids (in order of decreasing abundance) were 16:0, 22:6(n‐3), and 20:5(n‐3) (collectively 65–70% of the total fatty acids), followed by 16:1(n‐7), 18:2(n‐6), and 14:0. This distribution is characteristic of most dinoflagellates, except for the low abundance (<3%) of the fatty acid 18:5(n‐3), considered by some authors to be a marker for dinoflagellates. The three major sterols were 4α‐methyl‐5α‐cholest‐7‐en‐3β‐ol, 4α,23,24‐trimethyl‐5α‐cholest‐22E‐en‐3β‐ol (the dinoflagellate sterol, dinosterol), and 4α,23,24‐trimethyl‐5α‐cholest‐7‐en‐3β‐ol. These three sterols comprised about 75% of the total sterols in both logarithmic and early stationary phase cultures, and they were also found in high proportions (22–25%) in natural dinoflagellate bloom samples. 4‐Desmethyl sterols, which are common in most microalgae, were only present in trace amounts inG. catenatum.The chemotaxonomic affinities ofG. catenatumand the potential fo

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00591.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe cold‐water, photosynthetic dinoflagellateAmphidinium cryophilumWedemayer, Wilcox&Graham feeds phagotrophically on other dinoflagellate species. Food is ingested through a feeding tube, termed here the “phagopod,” which extends from the antapex. The peduncle of this organism plays no observable role in the feeding process. The phagopod is essentially a hollow cylinder composed electron‐opaque material that is possibly deposited on a membrane. NoAmphidiniumcytoplasmic components, including microtubules or other cytoskeletal elements, were observed in the phagopod. Prefeeding cells aggregate, in small clumps near prey organisms with their phagopods extended. Eventually some cells commence feeding, first inserting the phagopod through the prey cell‐covering and then slowly, over a period of 10 min or more, drawing cytoplasm through the phagopod and into a nascent food vacuole. Both light and electron microscopy suggest that one or more prey cell amphiesmal membranes remain intact during the feeding process. Upon completion of feeding, theAmphidinium cellswims off with a prominent food vacuole in the hypocone, leaving at least part of the phagopod attached to the prey cell. Phagotrophy inA. cryophilumseems to vary with light intensity. At low light intensities, cells feed phagotrophically and are nearly colorless, whereas at high light levels they feed much less frequently, if at all, and are brightly

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00600.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe endosymbioticChlorellasp. (Chlorophyceae) ofParamecium bursaria(Ciliata) can be infected by a double‐stranded DNA‐containing virus(Chlorella‐virus) that has a phagelike entry mechanism. Electron micrographs show that soon after attachment of the virus to the algal cell wall, a hole is formed through which the viral DNA enters the alga. Biochemical studies on a EuropeanChlorella‐virus system suggest that digestion of the algal cell wall is caused by glycolytic enzymes, one of which was identified as a β‐d‐glucosidase. Enzymes are bound to the virus capsid and are activated only after or by the attachment of the virus to its cognate alga or to preparations of the algal cell wall. Common features of viral cell wall‐digesting enzymes and algal autolysins

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00609.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe coding sequence for the large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase(rbcL)fromCodium fragile(Suringar) Hariot chloroplast DNA is 1428 bp in length and contains a 1813‐bp group II intron. The only other organisms in which introns have been found in therbcL gene areEuglenaandAstasia.TheCodiumintron likely had a separate origin from theEuglenaandAstasiaintrons, based on comparisons of intron sizes and sequences. Phylogenetic analyses ofrbcL nucleotide and amino acid sequences placeCodiumbetweenChlorellaand twoChlamydomonasspp., indicating that the Chlorophyceae may be polyphy

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00613.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY