Showing papers in "Journal of Phycology in 1987"
TL;DR: The use of several independent biochemical, physiological, morphological, and behavioral assays has resulted in the reassessment of the taxonomy of the gymnodinioid symbionts of marine invertebrates which belong to the genus Symbiodinuim Freudenthal (Dinophyceae).
Abstract: The use of several independent biochemical, physiological, morphological, and behavioral assays has resulted in the reassessment of the taxonomy of the gymnodinioid symbionts of marine invertebrates which belong to the genus Symbiodinuim Freudenthal (Dinophyceae). The formal description of the type species S. microadriaticum Freudenthal is augmented, and three new species are introduced; S. goreauii, symbiotic with the Caribbean sea anemone Ragactis lucida; S. kawagutii, harbored by the Hawaiian stony coral Montipora verrucosa; and S. pilosum, inhabiting the Caribbean zoanthid Zoanthus sociatus.
225 citations
TL;DR: Experiments in which 14CO2 was provided at different times in the growth cycle demonstrated that enhanced lipid biosynthesis at low nitrogen levels resulted principally from de novo CO2 fixation.
Abstract: The green alga Nannochloropsis sp. QII was cultivated in media with sufficient and growth-limiting levels of nitrogen (nitrate). Nitrogen deficiency promoted lipid synthesis yielding cells with lipids comprising 55% of the biomass. The major lipids were triacylglycerols (79%), polar lipids (9%) and hydrocarbons (2.5%). The polar lipids consisted of a broad range of phospholipids, glycolipids and sulfolipids. Other lipids identified were pigments, free fatty acids, saponifiable and unsaponifiable sterol derivatives, various glycerides, a family of alkyl-1, 4-dioxane derivatives and a series of alkyl- and hydroxy-alkyl-dimethyl-acetals. Experiments in which /sup 14/CO/sub 2/ was provided at different times in the growth cycle demonstrated that enhanced lipid biosynthesis at low nitrogen levels resulted principally from de novo CO/sub 2/ fixation.
206 citations
TL;DR: Half‐saturation constants for the reduction of Cu(II) complexes with carbonate, phenanthroline and bathocuproinedisulfonate are in the range 2.3–14.7 μM, which suggests that trace metal complexes are not the main electron acceptor in natural waters.
Abstract: The phytoplankton cell surface reduces external copper(II) and iron(III) complexes and redox dyes. This reductive activity appears to be mediated by one or more plasmalemma redox enzymes. Trace metal complexes are directly reduced by the redox enzyme, therefore the reduction rate is not regulated by the metal free ion activity in solution. This is in direct contrast to previous measurements of trace metal interactions with the phytoplankton cell membrane. Half-saturation constants for the reduction of Cu(II) complexes with carbonate, phenanthroline and bathocuproinedisulfonate are in the range 2.3-14.7 ..mu..M, which suggests that trace metal complexes are not the main electron acceptor in natural waters. In the diatom Thalassiosira weissflogii there is additional reductive activity associated with the cell wall.
121 citations
TL;DR: The rate of photosynthesis and nitrate uptake are related to the iron concentration in the medium for the green alga Scenedesmus quadricauda (Turp.) Breb and these parameters all indicate that the efficiency of Photosynthesis is related to iron nutrition.
Abstract: The rate of photosynthesis and nitrate uptake are related to the iron concentration in the medium for the green alga Scenedesmus quadricauda (Turp.) Breb. Increased iron leads to changes in chlorophyll a concentration, carbon fixation rate per chlorophyll a and in vivo fluorescence characteristics. These parameters all indicate that the efficiency of photosynthesis is related to iron nutrition. Nitrate uptake rate is also a function of both Fe and light Iron-limited cultures had decreased nitrate uptake at low light whereas ammonium uptake was relatively constant. Iron-limited cultures fixed about twice as much carbon into protein relative to the total carbon fixed. Iron plays a crucial role in the bioenergetics of carbon and nitrogen metabolism and may be important in controlling patterns of productivity.
118 citations
TL;DR: The physiological basis of these adaptations is discussed in terms of observed changes in activities and kinetics of the Calvin cycle enzyme ribulose‐1, 5‐bisphosphate carboxylase (oxygenase) and efficiency of light harvesting‐electron transport systems.
Abstract: The effect of growth temperature on photosynthetic metabolism was studied in the kelp Laminaria saccharina (L.) Lamour. Photosynthesis was subject to phenotypic adaptation, with almost constant photosynthetic rates being achieved at growth temperatures between 0 and 20° C. This response involved: (1) an inverse relationship between growth temperature and photosynthetic capacity, (2) a reduction in the Q10 value for photosynthesis of L. saccharina grown at 0 and 5° C compared with 10, 15 and 20° C grown sporophytes, and (3) an acquired tolerance of photosynthesis to temperatures between 15–25° C (which inhibited photosynthesis in 0 and 5° C grown L. saccharina) in sporophytes grown at 10, 15 and 20° C. The physiological basis of these adaptations is discussed in terms of observed changes in activities and kinetics of the Calvin cycle enzyme ribulose-1, 5-bisphosphate carboxylase (oxygenase) and efficiency of light harvesting-electron transport systems.
111 citations
TL;DR: Lipid synthesis of three marine diatoms was studied with a 14CO2 incorporation technique in silicate limited batch cultures and growth rates were independent of the silicate concentration but the cellular yields were proportional to the initial amount of silicate.
Abstract: Lipid synthesis of three marine diatoms was studied with a /sup 14/CO/sub 2/ incorporation technique in silicate limited batch cultures. Growth rates were independent of the silicate concentration but the cellular yields were proportional to the initial amount of silicate. At the beginning of the stationary growth phase, lipid synthesis rates per unit culture volume increased by 1.7 times for Chaetoceros gracilis, 3.1 times for Hantzschia sp., and 2.8 times for Cyclotella sp., respectively compared to those during the exponential growth phase. Lipid carbon accounted for as much as 57% of the carbon in C. gracilis, 71% in Hantzschia sp., and 65% in Cyclotella sp., respectively. Additional enrichment with silicate during stationary growth phase allowed the cultures to grow further. Lipid synthesis rates were reduced during the subsequent growth phase, and the growth rates themselves were dependent on the level of biomass achieved during the previous stationary phase. However, the cellular yields were similar and probably controlled by light.
108 citations
TL;DR: It seems likely that the organism is an undescribed dinoflagellate containing an endosymbiont with chlorophylls a and b and that the reduction of the endosYMBiont nucleus and mitochondria has permitted a more initmate symbiosis.
Abstract: A green-colored marine unicell has been grown in unialgal culture and its morphology, chloroplast fine structure, and chlorophyll composition investigated. The organism is typical of dinoflagellates in its shape, flagellation, nucleus, mitochondria, and trichocysts. It is similar to Gymnodinium but possesses fine body scales. Chloroplasts and two kinds of vesicles bounded by double membranes, but no organelles obviously identifiable as nuclei or mitochondria, are associated in ribosome-dense cytoplasm separated by a double membrane from the dinophycean cytoplasm. The chloroplasts are unlike any previously reported for dinoflagellates. Each is enclosed by an envelope consisting of a double membrane. Chloroplast lamellae consist of three appressed thylakoids. Interlamellar pyrenoids are present. Pigment analysis reveals chlorophylls a and b but not chlorophyll c. It seems likely that the organism is an undescribed dinoflagellate containing an endosymbiont with chlorophylls a and b and that the reduction of the endosymbiont nucleus and mitochondria has permitted a more initmate symbiosis.
93 citations
TL;DR: The occurrence of two patterns of spatial dispersion indicates that growth forms bear far‐ranging ecological implications with respect to colonization strategies, immigration, and possibly impact by grazers.
Abstract: This paper evaluates the utilisation of space by epibenthic diatom cells, as a response to environmental variations. The aggregation pattern of five species of epibenthic diatoms was quantified and compared to provide evidence for the significance of cell motility as an adaptive mechanism for space occupation and monopoly. The epibenthic diatoms included (1) non-mobile colonial species forming either fan-shaped (Synedra tabulata (Ag)Kz.) or arborescent (Gomphonema kamtschaticum var. californicum Grun.) colonies; (2) slow-moving (Cocconeis costata Greg, and Amphora pusio Cl.), and (3) fast-moving (Navicula direct a (W. Sm.) Ra.) non-colonial species. The aggregation pattern of S. tabulata did not vary significantly among six different light intensities manipulated in nature. The major patterns of aggregation were identified using analysis of covariance and dummy-variable regression. Highly mobile N. directa are significantly less aggregated than the four other diatom species. Non-mobile and slow-moving species show a similar, highly aggregated pattern. The occurrence of two patterns of spatial dispersion indicates that growth forms bear far-ranging ecological implications with respect to colonization strategies, immigration, and possibly impact by grazers. An integrated model of growth form characteristics, biological properties, and ecological implications is presented for epibenthic diatoms.
91 citations
TL;DR: The organelle ultrastructure and photosynthetic pigments of a new isolate of the picoplanktonic alga Pelagococcus subviridis Norris from the East Australian Current was compared with the North Pacific Ocean type species, and showed two unusual features: the de novo appearance of centrioles prior to mitosis, and the formation of a small, extra‐nuclear spindle.
Abstract: The organelle ultrastructure and photosynthetic pigments of a new isolate of the picoplanktonic alga Pelagococcus subviridis Norris from the East Australian Current was compared with the North Pacific Ocean type species. No differences in the ultrastructure of the two isolates were observed. Mitosis was studied in detail in the Australian strain, and showed two unusual features: the de novo appearance of centrioles prior to mitosis, and the formation of a small, extra-nuclear spindle.
The major carotenoids in both strains were fucoxanthin and a 19′-butanoyloxyfucoxanthin-like pigment, with diadinoxanthin and diatoxanthin as secondary pigments. Several minor carotenoids have not yet been identified. In addition to chlorophylls a and c2, a new chlorophyll c derivative (chlorophyll c3), present in both strains, was separated by high-performance thin-layer chromatography (HPTLC). The Australian isolate, unlike the type material, showed no evidence of chlorophyllase activity during cell harvest and extraction.
While the pigment composition suggests affinities with certain newly examined prymnesiophytes, organelle ultrastructure indicates Pelagococcus to be a member of the Chrysophyceae. Mitosis is, however, atypical of both Prymnesiophyceae and Chrysophyceae, and if this picoplanktonic alga is to be retained in the Chrysophyceae it must be seen as a most unusual member.
88 citations
TL;DR: A new order, Parmales, in the Chrysophyceae has cells with siliceous walls made up of round, triradiate and sometimes oblong plates all fitting edge to edge.
Abstract: A new order, Parmales, in the Chrysophyceae has cells with siliceous walls made up of round, triradiate and sometimes oblong plates all fitting edge to edge. In the new family, Octolaminaceae, cell walls have eight plates. Cell walls in the new genus Tetraparma have four round plates and four triradiate plates. Cell walls in the new genus Triparma have three round plates of equal size, one larger round plate, one triradiate plate and three oblong plates. In the new family, Pentalaminaceae, cell walls have three round and two triradiate plates. A total of seven new species and four subspecies are described from subarctic Pacific and Antarctic waters.
83 citations
TL;DR: The intact symbiotic association of the spinose planktonic foraminifer with the dinoflagellate is characterized by a diurnal movement of the symbionts from the distal regions of the spines during the day, to perialgal vacuoles within the host cytoplasm at night.
Abstract: The symbiotic association of the spinose planktonic foraminifer, Orbulina universa, with the dinoflagellate, Gymnodinium beii sp. nov., was examined with light and electron microscopy, and the symbiont was isolated into unialgal culture. The intact association is characterized by a diurnal movement of the symbionts from the distal regions of the spines during the day, to perialgal vacuoles within the host cytoplasm at night. This diurnal migration involves a daily endo- exocytotic cycle.
Gymnodinium beii is non-motile and spindle-shaped within the host, whereas it is motile and gymnodinoid in shape when in culture. Ultrastructural examination revealed two or more stalked pyrenoids penetrated by lamellae, a typical dinokaryon nucleus and no trichocysts. A distinct ‘flange’projects over the sulcus from the hypocone. The swimming behavior of this dinoflagellate was characterized by intermittent darting events. Swimming speeds during a dart reached velocities of 770 μm. s−1 as compared to a mean, non-darting swimming velocity of 126 μm. s−1. Gymnodinium beii is eurythermal and division rates ranged between 0.16 and 0.65 divisions day−1 for culture temperatures between 6.5 and 25° C respectively.
TL;DR: Diatoms isolated from the benthic, planktonic and sea ice microbial communities in McMurdo Sound, Antarctica assimilated ambient concentrations of dissolved amino acids and glucose in both the light and dark, suggesting that these diatoms can use exogenous amino acids to synthesize the essential macromolecules for heterotrophic growth.
Abstract: Diatoms isolated from the benthic, planktonic and sea ice microbial communities in McMurdo Sound, Antarctica assimilated ambient concentrations of dissolved amino acids and glucose in both the light and dark. Uptake of amino acids but not glucose was influenced by the iucubation irradiance and amino acid uptake rates were up to 250 times greater than those of glucose. Amino acids were incorporated into proteins and other complex polymers and the rates of assimilation and patterns of polymer synthesis were similar to those of the light-saturated photosynthetic incorporation of inorganic carbon. This suggests that these diatoms can use exogenous amino acids to synthesize the essential macromolecules for heterotrophic growth. The assimilation of dissolved organic substrates could supplement light-limited growth during the austral spring and summer as well as potentially support the heterotrophic growth of these diatoms throughout the aphotic polar winter.
TL;DR: Irradiance‐dependent rates of photosynthesis and cell division of six species of microalgae isolated from the benthos, plankton and sea ice microbial community in McMurdo Sound, Antarctica were compared, suggesting that cell division buffers the influence of short term variations of irradiance on cellular metabolism.
Abstract: Irradiance-dependent rates of photosynthesis and cell division of six species of microalgae isolated from the benthos, plankton and sea ice microbial community in McMurdo Sound, Antarctica were compared. Microalgae isolated from different photic environments had distinct photosynthetic and growth characteristics. For benthic and ice algae, photosynthesis saturated at 6 to 20 μE.m−2.s−1 and was photoinhibited at 10 to 80 μE.m−2.s−1 while for the planktonic algae, saturation irradiances were up to 13 times higher and photoinhibition was not detected. The slope of the light-limited portion of the P-I relationship was up to 50 times greater for the benthic algae than for either the ice or planktonic algae suggesting that benthic algae used the low irradiances more efficiently for carbon uptake. Cell division was dependent on the incubation irradiance for all but one microalga examined. The dependence of division rates on irradiance was however much smaller than for carbon uptake, suggesting that cell division buffers the influence of short term variations of irradiance on cellular metabolism.
TL;DR: The diurnal variability of photosynthesis vs. irradiance (P‐I) curves was evaluated for the six most dominant species of macroalgae that occur annually in North Inlet Estuary, South Carolina and questions conclusions expressed by others that it is not possible to accurately determine diurnal photosynthesis of Macroalgae from light saturation curves that are measured over short time periods.
Abstract: The diurnal variability of photosynthesis vs. irradiance (P-I) curves was evaluated for the six most dominant species of macroalgae that occur annually in North Inlet Estuary, South Carolina. Three existing models best simulated the observed data: (1) the Hyperbolic Tangent Model of Jassby and Platt (1976), which was applied to data that showed no photoinhibition; (2) the Exponential Inhibition Model of Parker (1974); and (3) the Photoinhibition Model of Platt et al. (1980), which were employed when photo-inhibition was measured. Photoinhibition was observed in about 75% of the experiments, and in some cases at irradiance levels as low as 500 μE.m−2. s−1. Most of the resulting P-I curves did not differ significantly when measured at various times of the day. As a consequence of these results, we question conclusions expressed by others that it is not possible to accurately determine diurnal photosynthesis of macroalgae from light saturation curves that are measured over short time periods.
TL;DR: It is proposed that periplast plates are attached to the cell membrane by intramembrane particles (IMP's), consequently plate shapes are outlined by IMP distribution in fractured membranes.
Abstract: A quick-freezing technique for freeze fracturing was used to determine periplast plate types in 20 cryptomonads. With this technique cells are frozen so rapidly that major artifacts are eliminated. We propose that periplast plates are attached to the cell membrane by intramembrane particles (IMP's), consequently plate shapes are outlined by IMP distribution in fractured membranes. Round to oval, sometimes slightly angular, plates occur in Cryptomonas ovata, Cryptomonas tetrapyrenoidosa, Cryptomonas parapyrenoidifera, Cryptomonas obovata, Cryptomonas erosa and two unidentified species of Cryptomonas; large rectangular plates occur in Chroomonas pochmannii, Chroomonas coerulea and Hemiselmis sp.; small rectangular plates were found in Cryptomonas sp. (Strain SDB); square to slightly rounded plates occur in Cryptomonas chrysoidea and a single continuous plate or sheet, perforated by ejectisome pores, was observed in Cryptomonas caudata, Cryptomonas rostratiformis, Cryptomonas marssonii, Cryptomonas platyuris, Cryptomonas curvata, Cryptomonas ozolini, Chilomonas paramecium and Rhodomonas sp. Oval and square plates are described for the first time in Cryptomonas. Plate IMP's may be morphologically modified in size and shape, depending upon their location in relation to the plate, the plate ridges, and ejectisome chambers. Conformational changes in plate shapes, to form hexagons or polygons, may be induced when cells are subjected to fixation, desiccation, cryoprotectants or centrifugation.
TL;DR: UDPglucose pyrophosphorylase activity was detected in cell‐free extracts of the diatom Cyclotella cryptica TI3L Reimann, Lewin and Guillard and was relatively insensitive to feedback inhibition from UDPglucoses.
Abstract: UDPglucose pryophosphorylase activity was detected in cell-free extracts of the diatom Cyclotella cryptica T13L Reimann, Lewin and Guillard. When assayed in the direction of UDPglucose formation, the enzyme had maximal activity at pH 7.8 and was stimulated by Mg/sup 2 +/ and Mn/sup 2 +/ ions. 3-Phosphoglycerate and inorganic phosphate had little effect on enzymatic activity, and the enzyme was relatively insensitive to feedback inhibition from UDPglucose. A glucan was formed from UDP-(/sup 14/C)glucose in cell-free extracts of C. cryptica. This glucan had a median molecular weight of 4600 (as determined by gel filtration chromatography) and could be hydrolyzed by laminarinase. Partial acid hydrolysis of the glucan resulted in the formation of glucose and laminaribiose, but not cellobiose. These results suggest that the synthesis of chrysolaminarin (the major storage carbohydrate of diatoms) occurs via the activity of UDPglucose pyrophosphorylase, followed by glucosyl transfer from UDPglucose to the growing ..beta..(1 ..-->.. 3)-linked glucan.
TL;DR: Evidence strongly suggests that the rosette type of terminal complex morphology is an additional characteristic of charophycean algae and lends further support to the hypothesis that this group of algae represents the evolutionary line that gave rise to vascular plants.
Abstract: A freeze-fracture investigation of the putative cellulose synthesizing complex (terminal complex) morphology in Nitella translucens var. axillaris (A. Br.) R.D.W. internodal cells revealed single solitary EF globules and PF rosettes on the plasma membrane. The average density of rosettes in elongating internodal cells was 5.6 μm−2 with slight spatial variation observed. In only three other algal genera (all zygnematalean) have rosette / globule terminal complexes been observed, while this characteristic is common to all vascular plants and one moss thus far investigated. This evidence strongly suggests that the rosette type of terminal complex morphology is an additional characteristic of charophycean algae and lends further support to the hypothesis that this group of algae represents the evolutionary line that gave rise to vascular plants.
Observations were also made from the freeze-fracture of Nitella internodal cells concerning the orientation of cell wall microfibrils and cytoskeletal elements near the plasma membrane. The pattern of microfibril orientation in growing internodal cells is initially transverse to the cell long axis, becoming progressively axial presumably due to the strain of elongation. In mature internodal cells, the pattern of microfibril orientation is helicoidal. Microtubules appressed to the inner surface of the plasma membrane are oriented parallel to the most recently formed microfibrils in elongating and mature internodal cells.
TL;DR: The conditions which give optimal growth and conchospore release in laboratory cultures of free conchocelis of the red alga Porphyra torta Krishnamurthy are determined.
Abstract: We have determined the conditions which give optimal growth and conchospore release in laboratory cultures of free conchocelis of the red alga Porphyra torta Krishnamurthy With cool white fluorescent light on a 16L8D photoregime, the fastest sustained growth (5% volume increase d−1) was observed from 10–15°C and 25–100 μE-m −2s−1; slightly faster growth was observed at 15°C and 300 μEm−2s−1, but such conditions are close to lethal Conchoporangin will form under a wide range of conditions in conchocelis of this species However, conchospores will mature and release only when the cultures are exposed to a short day photoperiod The critical pholoperiod is just shorter than 12 h, The minimum number of photoinductive cycles for complete conchospore release is four for a range of conditions but can be just one depending on pretreatment
TL;DR: The data suggest that the Bacillariophyceae may be monophyletic, and that the primary structure of the diatom light‐harvesting complex is not closely related to pigment‐protein complexes with similar function in other chlorophyll c‐containing unicellular algal groups.
Abstract: Monospecific, polyclonal antibodies raised against the apoprotein of the major light-harvesting pigment-protein of Phaeodactylum tricornutum Bohlin UTEX 646 were used to determine (1) whether this complex was common to the class Bacillariophyceae, whose members contain chlorophylls a and c and fucoxanlhin; (2) whether antigenically-related apoproteins were present in other chlorophyll c-containing groups, and (3) whether there was immunological homology with the light-hanvsting chlorophyll a/b protein of similar photosynthetic function in the Chlorophyta and vascular plants. We have used protein blotting techniques to show that antibodies against the two P. tricornutum light-harvesting complex polypeptides cross-reacted with one or two polypeptides of similar molecular weight (17–21 kD) in all ten diatom species examined, representing two orders and six families. No cross-reactivity was obtained with total membrane polypeptides from isolated representatives of three chromophyte algal divisions (Chrysophyta, Cryptophyta, Pyrrophyta), all of which contained chlorophyll c. No cross-reactivity was observed with membrane Polypeptides isolated from members of two classes of Chlorophte algae. These data suggest that the Bacillariophyceae may be monophyletic, and that the primary structure of the diatom light-harvesting complex is not closely related to pigment-protein complexes with similar function in other chlorophyll c-containing unicellular algal groups. Lastly, it may be possible to use the antibodies to the diatom light-harvesting polypeptides as specific markers for diatoms in natural phytoplankton assemblages.
TL;DR: Results suggest a common evolutionary origin for these light‐harvesting complexes, in apparent contrast to the great differences in cell structure between prymnesiophytes and diatoms.
Abstract: A fucoxanthin-chlorophyll a/c-protein complex has been isolated from the prymnesiophyte Pavlova gyrans. Thylakoid membranes were treated with the mild anionic detergent sodium taurodeoxycholate followed by sucrose density gradient centrifugation. The brown fraction produced by this procedure was treated with Triton X-100 followed by a second sucrose density gradient centrifugation. A brown fraction isolated from this gradient was shown to be a light-harvesting complex nearly identical to that which is present in the diatom Phaeodactylum tricornutum. The complexes from the two organisms have nearly identical absorption and flourescence spectra, both complexes contain fucoxanthin and two other carotenoids, both contain four polypeptides of similar molecular weights, and polypeptides from both complexes cross react with antibodies raised to polypeptides of the Phaeodactylum tricornutum complex. Results suggest a common evolutionary origin for these light-harvesting complexes, in apparent contrast to the great differences in cell structure between prymnesiophytes and diatoms.
TL;DR: Periphytic communities in running waters were examined as they developed on granite rocks, concrete balls and glass slides, finding no differences in pigment concentrations, species diversity or production levels among the different substrata examined.
Abstract: Periphytic communities in running waters were examined as they developed on granite rocks, concrete balls and glass slides. At equivalent cell densities, no differences in pigment concentrations, species diversity or production levels were found among the different substrata examined. Development of the assemblage appeared to result from the elongation of short algal filaments which had initially settled on the surface. As these communities matured, a distinct canopy and understory developed. Cellular metabolisms were comparable among the communities. In the understory of the communities, even though the cellular content of chl a and b did not differ, chl c and carotenoid pigment concentrations were higher than those in the over-story.
Bicarbonate assimilation of Tabellaria fenestrata (Lyng.) Kulz. and Eunotia pectinalisi var. pectinalis (O. F. Mull?) Rabh. was higher than that of the more abundant Tabellaria flocculosa (Roth.)Kutz. var. flocculosa IV (sensu Koppen) at both high and low cell densities. This probably reflects a seasonal succession of colonizing species.
Glucose assimilation appeared to be mainly attributable to bacterial activity, and algal cells of the upper layer were less active than those of the bottom. The small amount of glucose that was incorporated by the algal cells was probably absorbed passively since its amount was in direct proportion to cell volumes.
TL;DR: In this paper, the costs and benefits of ploidy level, as measured by net photosynthesis, calorific content, structural makeup and resistance to predation, were not sufficient to result in statistically significant differences (P > 0.05 ANOA) for the various reproductive phases.
Abstract: Morphologically identical but different life-history phases of the red alga Polycavernosa debilis (Forsskal) Fredericq and J. Norris showed no conspicuous differences in physiological or ecological performances. The costs and benefits of ploidy level, as measured by net photosynthesis, calorific content, structural makeup and resistance to predation, were not sufficient to result in statistically significant differences (P > 0.05 ANOA) for the various reproductive phases [haploid male or female (including cystocarps) and diploid tetrasporic]. The lack of measurable functional responses leads to two hypotheses: (1) that adaptive ecological-physiological differences between life-history phases are subtle, or (2) that predominantly genetic / reproductive factors are implicated in maintaining isomorphic life-history phases.
TL;DR: Chlorophyll pigments in 100% mrthanol extracts from ten axenic cultured diatoms and three green algae were examined using reverse phase HPLC with Jluoromelric detector and field desorption mass spectrometry to identify same unknown peaks tn HPLC chromatograms from natural phytoplankton samples.
Abstract: Chlorophyll pigments in 100% mrthanol extracts from ten axenic cultured diatoms and three green algae were examined using reverse phase HPLC with Jluoromelric detector and field desorption mass spectrometry to identify same unknown peaks tn HPLC chromatograms from natural phytoplankton samples.
Characteristics of the HPLC chromatograms were the presence of chlorophyllide and two unknown peaks. Field desorption mass spectrometry of the oxidation products of authentic chlorophyll a suggested that the peaks were due to 10-hydroxy and 10-hydroxy lactone chlorophylls a and 10-methoxy and 10-methoxy lactone chlorophylls a fanned during each process of filtration, storage at -20°C and extraction in methanol.
The present results indicated that a new type of chlorophyll c derivative may exist and, as far as we use filtration to collect phytoplankton and store the sample under air even at -20°C, the formation of oxidation products of chlorophyll pigments may he unavoidable.
TL;DR: Flagellar root correlation with the reservoir cytoskeletal bands strengthens their homologies with the bodonid bands and further supports the hypothesis that the euglenoids are derived from the kinetoplastid flagellates.
Abstract: The three flagellar roots of Colacium Ehrenberg give rise to the three microtublar bands of the reservoir cytoskeleton. The dorsal root (DR) originates at the basal body (bb1) of the emergent flagellum. It is initiated on the left side of the cell, runs toward the right side under the posterior end of the reservoir and thence anteriorly in a spiral path over the dorsal surface of the reservoir until it terminates on the left side of the eyespot. Along its length, it appears to initiate a dorsal band (DB) which forms the major dorsal portion of the reservoir cytoskeleton—the dorsal microtubules (DMT). Two roots originate at the basal body (bb2) of the non-emergent flagellum. The ventral root (VR) runs up the left side of the cell and initiates the band of microtubules which forms part of the presumptive vestigial cytopharynx. Therefore, it forms the reinforcing microtubules (MTR) of Colacium. The intermediate root (IR) forms the para-reservoir microtubules (PMT). Flagellar root correlation with the reservoir cytoskeletal bands strengthens their homologies with the bodonid bands and further supports the hypothesis that the euglenoids are derived from the kinetoplastid flagellates.
TL;DR: The banding patterns and satellites on chromosomes suggest that three pairs of homologous chromosomes are present in filaments of the original clonal culture and that these filaments are themselves autopolyploid (diploid) descendants of ancestral form with a base chromosome number of x = 3.
Abstract: A species complex in Spirogyra consists of the series of filament morphotypes of various ploidal levels arising from an original morphotype within a clonal culture or in nature. A clonal culture of filaments identified as Spirogyra maxima (Hassall) Kutzing produced several morphotypes, i.e. filament types of distinctly different widths and ploidal levels. Banding patterns and satellites were visible on chromosomes stained at mitotic prophase and metaphase. The original culture of S. maxima contained filaments averaging 127 μ wide. Vegetative cells of the original culture contained six large chromosomes (>4 μ long), identifiable as three distinct pairs based on banding patterns and presence of satellites: (1) one pair of short chromosomes (ca. 5.0 μ); (2) one pair of long chromosomes (ca. 8.0 μm); and (3) a second pair of long chromosomes (ca. 9.0 μm) including a nucleolar organizing region and satellite. A larger morphotype averaging 175 μm in width contained 12 chromosomes, with two pairs of short chromosomes and four pairs of long chromosomes (satellites were usually indistinct). Aneuploid chromosome numbers ranging from 5 to 13 were observed in a few cells. Binucleate and trinucleate cells were also observed. A twobanded chromosome fragment was observed in a few cells with 6 chromosomes and a few cells with 12 chromosomes. The variety of morphotypes derived in this study could be identified as four different species of Spirogyra by conventional taxonomic criteria. The banding patterns and satellites on chromosomes suggest that three pairs of homologous chromosomes are present in filaments of the original clonal culture and that these filaments are themselves autopolyploid (diploid) descendants of ancestral form with a base chromosome number of x = 3.
TL;DR: Culture experiments and herbarium studies provide evidence that E, gelidium and E. acantghocladum are conspecific and Meristiella is assigned to the tribe Agardhielleae.
Abstract: Eucheuma acanthocladum (Harvey) J. Agardh, E. gelidium (J Agardh) J. Agardh, E. echinocarpum Areschoug and E. schrammii(P. et H. Crouan) J. Agardh from the tropical and warm temperate waters of the western Atlantic Ocean and Caribbean Sea are transferred to a new genus, Meristiella. Meristiella exhibits the following Unique combination of characters among genera in the Solieriaceae: (1) rotated periaxial cells, (2) a loosely filamentous medulla. (3) an auxiliary cell complex, (4) Single and twin connecting filaments and (5) spinose cystocarps composed of a central, small-celled placentum, based on its reproductive features, Meristiella. is assigned to the tribe Agardhielleae. Culture experiments and herbarium studies provide evidence that E, gelidium and E. acantghocladum are conspecific. Lectotypes are designated for the included species.
TL;DR: The apparently normal meiosis of triploid zygospores and the high viability of F1 progeny suggested that the genome of Group A contains several sets of chromosome complements with mechanisms by which bivalents are regularly formed in the first meiotic division.
Abstract: Two pairs of stable diploid clones were obtained as aberrant forms among F1 progeny of an intragroup (intraspecific) cross between R-11-4 (mating type +) and M-16-4b (mating type -) of Group A of Closterium ehrenbergii Menegh. Each pair was derived from the two germination products of a single zygospore, and both clones were mating type minus. The cell size range of these four diploid minus clones was considerably above that of normal (haploid) Group A clones. Chromosome counts at the second meiotic metaphase indicated that these clones were diploid with approximately 200 chromosomes, which was double the number for normal Group A clones. Diploid minus clones conjugated normally with any haploid Group A plus clones, and yielded many triploid zygospores. Triploid zygospores germinated normally as did intragroup diploid zygospores. In metaphase I preparations, only bivalents were observed except on a few occasions where some uni- and multivalents were also detected. Viability of F1 progeny from triploid zygospores (55–74%) was somewhat lower than from diploid zygospores of Japanese Group A populations (65–90%), but higher than intergroup (interspecific) hybrid zygospores from Groups A, B and H (0–12%). In addition to lower viability, some F1 progeny from triploid zygospores exhibited slow vegetative growth. Almost all pairs of F1 clones from single triploid zygospores were of opposite mating type, similar to normal diploid zygospores of the intragroup cross. Morphological variability of F1 progeny of triploid zygospores was great. The apparently normal meiosis of triploid zygospores and the high viability of F1 progeny suggested that the genome of Group A contains several sets of chromosome complements with mechanisms by which bivalents are regularly formed in the first meiotic division.
TL;DR: The apical meristems of Splachnidium and species of the Fucales have several important features in common, including the growth‐regulatory role of the apical cell and the process of conceptacle initiation, and the taxa may possibly have a common evolutionary origin.
Abstract: The meristem of Splachnidium rugosum consists of a central apical cell surrounded by a region of actively dividing cells, many of which bear hairs. Conceptacle initials are scattered throughout the surface layer of the meristematic region. Conceptacle initials and apical hairs differentiate adjacent to the apical cell. The apical cell and the conceptacle initials are distinctive, pear-shaped cells possessing similar cytological features that are consistent with significant metabolic activity. They have a nucleus surrounded by dictyosomes, a stellate chloroplast, mitochondria, and numerous vesicles and physodes. When the apical cell is damaged as a result of experimental manipulation, growth ceases. It is inferred that the apical cell controls cell division in the meristematic region and also the differentiation of conceptacle initials and apical hairs. The apical meristems of Splachnidium and species of the Fucales have several important features in common, including the growth-regulatory role of the apical cell and the process of conceptacle initiation. The taxa may possibly have a common evolutionary origin. The problematic and unresolved taxonomic status of Splachnidium is discussed.
TL;DR: The discoid thallus of Erythrocladia irregularis is the result of a pattern of cellular divisions expressed by mono‐and endospores; the latter are described for the first time in Erythropeltidaceae.
Abstract: The discoid thallus of Erythrocladia irregularis is the result of a pattern of cellular divisions expressed by mono-and endospores; the latter are described for the first time in Erythrocladia. In nutrient enriched growth conditions the discoid thallus becomes a shapeless aggregate of unicells with a wrinkled wall surface, whose plane of division is unpredictable. The cells are able to produce monosporangia with a curved wall or they form eight-celled endosporangia. Chloroplasts have an internal pyrenoid, as is characteristic of the Erythropeltidaceae.
The observation that E. irregularis can form either a colonial cluster of unicells or a discoid thallus would lead to the assignment of the genus to the Porphyridiales; however, since this order is reserved to organisms in which only the unicellular organization can be expressed, it is suggested to maintain Erythrocladia in the Erythropeltidales.
TL;DR: These two species can be clearly distinguished by the differences in the position of pyrenoids in the cupshaped chloroplasts and stability ofpyrenoid appearance in relation to the culture age, as well as in the fate of parental pyrenoid during daughter colony formation.
Abstract: The appearances of pyrenoids in the vegetative cells of Volvulina steinii Playfair and V. pringsheimii Starr were observed in detail by light and electron microscopy in relation to the culture age to clarify the taxonomic relationship between the two species. In V. pringsheimii, the pyrenoids were always present in the bottom of the cupshaped chloroplasts and their gross morphology did not vary in relation to the culture age, while those of V. steinii appeared de novo and developed as the culture aged. In 24-h cultures of V. steinii, pyrenoids were not observed in the chloroplasts. In 48-h cultures, a pyrenoid matrix developed apparently de novo in the brim of the cupshaped chloroplast. Subsequently, starch grains appeared around the pyrenoid matrix in 72-h cultures. The volume of the matrix and the associated starch grains increased and tubular channels entered into the pyrenoid matrix in 96-h cultures. In addition, the pyrenoid in the parental chloroplast of V. pringsheimii divided and was distributed to each daughter cell during cell divisions in daughter colony formation, while the parental pyrenoid of V. steinii did not divide and went to one of the daughter cells. Therefore, these two species can be clearly distinguished by the differences in the position of pyrenoids in the cupshaped chloroplasts and stability of pyrenoid appearance in relation to the culture age, as well as in the fate of parental pyrenoids during daughter colony formation.