摘要:

ABSTRACTThe cysts (statospores) ofOchromonas tuberculataHibberd are produced within a cytoplasmic silica deposition vesicle (SDV) whose membrane (silicalemma) appears to be formed by the coalescence of golgi vesicles. Silica is first deposited as small nodules and the collar and spines develop by centrifugal growth only after a complete but still thin wall has been laid down. Small vesicles appear to be attached to the SDV only in the region overlying the developing collar; a cap of radially arranged, moderately electron‐dense material occurs at the tip of the growing spines. The cyst pore is formed at the anterior end of the flagellate cell, by lack of silica deposition over a small region of the SDV and rupture of the SDV and other membranes crossing this region. When the cyst wall is complete, an extracystic plug is formed in the pore, resulting in the loss of some extracystic cytoplasm and the plasmalemma, and the inner SDV membrane becomes the functional plasmalemma. The plug develops first by coalescence with the cell membrane of golgi‐derived vesicles containing dense but apparently nonsiliceous spicules surrounded by amorphous material. During later stages of plug formation only fibrous material is deposited, some of which may be extruded through the pore forcing out some of the spiculate component. Scanning electron micrographs of the mature wall show it is smooth except for the concentrically wrinkled inner face of the flared collar and that the real pore diameter is only ca. half that of the collar. At germination the plug completely disappears in an unknown way and a single cell, similar to a normal vegetative cell emerges through the pore. Chrysophycean cyst formation generally resembles cell wall formation in diatoms, but differs in some deta

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02933.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTA Feulgen microspectrophotometric analysis of successive generations ofFritschiella tuberosaIyengar revealed an asexual repeating of one generation rather than an obligate alternation of isomorphic generations as previously described.F. tuberosaregularly reproduces asexually by the release of one quadriflagellate zoospore produced/cell in all parts of the upright and prostrate portions of the thallus. In the vegetative thalli, nuclei in the G1(pre‐synthesis), synthesis, and G2(post‐synthesis) phases of the mitotic cycle are all well‐repres

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02934.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTCritical‐point dried (CPD) cells from clonal cultures ofEuglena gracilisKlebs (Z strain),E. desesEhrb.,E. tripteris(Duj.) Klebs andE. myxocylindraceaBold&MacEntee were examined by scanning electron microscopy. Flagellated motile cells ofE. gracilisare naked except for a few strands of mucilage on the posterior tip. Flagellated cells ofE. tripterishave a permanent mucilage coating often of uneven distribution and usually not as well developed as that of nonflagellated creeping cells which have a distinctive mucilage. InE. desesthe coating appears rough due to the aggregation of isolated groups of strands above the cell surface. InE. tripteristhe coating appears smooth except for breaks near the articulation of the pellicular strips where the mucilage may rise above the surface to form waves. At high magnification this mucilage consists of a network of strands generally lying parallel to the cell surface; the strands become obscure in some specimens. InE. myxocylindraceaelongated, mucilage‐coated cells contract to form spheres which undergo further mucilage deposition producing the mucilage covering of palmellae. As palmellae mature, the mucilage surface becomes less porous and the individuality of most mucilage strands is l

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02935.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTProduction ofAscophyllum nodosum(L.) LeJolis ecads andFuscus vesiculosusL. was calculated from measurements of in situ growth, seasonal variations in standing‐crops and seasonal variations in photosynthetic capacity. A computer model for predicting daily, monthly and yearly net production from photosynthesis data was constructed. This model used daily irradiation, actual biomass of algae/m2contributing to production and photosynthesis vs. light intensity relationships as data inputs. Comparison of production estimated from in situ growth, standing‐crops and photosynthesis indicated that both marsh fucoids turn over biomass twice per year. Total net production of both fucoids, estimated from photosynthesis data, was ca. 315 g C · m−2· yr−1. On the other hand, production of both fucoids calculated from standing‐crop data was only 155 g C

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02936.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThirty‐four heterocyst‐producing strains of Rivulariaceae (29Calothrix,1Dichothrix,2Gloeotrichia, 2Rivularia),which produced tapered trichomes in medium minus combined nitrogen, were grown in the presence of nitrate. One strain was unchanged in morphology under this condition. The remaining 33 strains developed trichomes lacking heterocysts. In 19 strains almost all the trichomes became untapered and in the other 14, similar untapered trichomes were produced, but also many tapered trichomes resemblingHomoeothrixorHammatoidea.Similar results were obtained when representative strains were incubated with ammonia as the source of combined N. Only five strains formed colorless hairs in the control medium (minus combined N). The presence of combined N did not diminish hair development in the two strains which had only a few short hairs, but hair frequency and length were both reduced considerably in the three strains with many long hairs in the control medium. Two strains of the non‐heterocystous genusHomoeothrixwere incubated in medium without combined N. Neither strain showed any growth or heterocyst development, indicating that neither is simply a growth form of a heterocystous

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02937.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe distribution of radioactivity into storage and intermediary metabolites during photosynthesis over periods of up to three hours was followed in the siphonous green algaCaulerpa simpliciuscula C.Ag. After the first hour, almost all the carbon assimilated was recovered as insoluble 1,4‐α‐glucan. There was rapid movement of carbon into insoluble 1,3‐β‐glucans during the first 20 min of photosynthesis, but little additional carbon moved into these compounds after that time. This contrasted with the movement of carbon into the soluble 1,3‐β‐glucan fraction, which continued for 2 h. Sucrose accumulated very little14C during the entire period of photosynthesis. There was a very slow transfer of14C into lipid throughout the period but the rate was linear. Protein labelling showed a lag of 2 h before it reached the same rate of14C accumulation as shown by the lipid initially. It is suggested that the distribution of radioactivity can be explained in part by proposing that the tissue is in the latter stages of recovery from the wounding which look place at the time of dividing the thallus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02938.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTAlcian Blue, a cationic copper phthalocyanine dye, complexes with the anionic carboxyl and half‐ester sulfate groups of acidic algal polysaccharide in aqueous solution to form an insoluble precipitate. The quantity of dye removed from solution is proportional to the quantity of polyanion in solution, and this principle forms the basis for the quantitative determination of acid and/or sulfated algal polysaccharides. The assay is linear between 0 and 100 μg/ml agar, alginic acid, carrageenan, pectin andPorphyridium aerugineumGeit. polysaccharide. In addition, the technique is used to determine the anion density of acid polysaccharides on a molar or weight equivalency bas

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02939.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTThe stalk ofColacium mucronatumBourr.&Chad. is composed primarily of a cylindrical shaft with a lightly staining inner core and diffuse peripheral cortex. The shaft and cortex arise from a ring‐shaped region around the canal opening whereas the core appears continuous with the canal which may be associated with initial cell attachment. All parts of the stalk, as well as the lining and contents of the reservoir, canal and flagellum exhibit stain reactions associated with neutral or mildly acidic carbohydrate with widely spaced anionic groups in low concentratio

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02940.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTAn examination of the pigments of the binucleate dinoflagellatePeridinium balticum(Levander) Lemmerman revealed the presence of chlorophyllsa, c1andc2and the carotenoids: fucoxanthin (most abundant), diadinoxanthin, diatoxanthin, an unidentified fucoxanthin‐like xanthophyll, β‐carotene, γ‐carotene and astaxanthin. A comparison of the pigments ofP. balticumandP. foliaceum(Stein) Biecheler, also a binucleate dinoflagellate, demonstrated similar compositions. HoweverP. balticumlacked the β‐carotene precursors (e.g. phytoene) which accumulated outside the chloroplast inP. foliaceum.This study indicates thatP. balticumandP. foliaceumare closely related; each species is a heterotrophic dinoflagellate with a photosynthetic endosymbiont taxonomically affiliated with the Chrysophyta (Chrysophyceae or Bacillar

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02941.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY

摘要:

ABSTRACTA detailed ultrastructure study was made of cell division and colony development inEudorina elegansEhrenberg. At the onset of cell division and prior to nuclear division the nucleus moved from the cell center to the cell surface. During nuclear division the nuclear membrane remained intact, except for openings occurring at the nuclear poles. The spindle microtubules appeared to arise from a MTOC‐like (microtubule organizing centers) structure, while centrioles were absent from the nuclear poles. Following telophase, daughter nuclei formed which were separated by several distinct bands of endoplasmic reticulum. Cytokinesis occurred with formation of a cleavage furrow, associated with a typical phycoplast band of microtubules. However, cytokinesis was incomplete, resulting in formation of cytoplasmic bridges between the plakeal cells. Upon completion of up to five successive cell divisions, the plakea underwent inversion, which appeared to involve the production of colonial envelope material and rearrangement of cytoplasmic bridges. A new hypothesis concerning inversion is postulated based on these observation

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1977.tb02942.x

出版商:Blackwell Science Inc    

年代:1977

数据来源: WILEY