scholarly journals GRANULES ASSOCIATED WITH THE CHLOROPLAST LAMELLAE OF PORPHYRIDIUM CRUENTUM

1966 ◽  
Vol 29 (3) ◽  
pp. 423-434 ◽  
Author(s):  
E. Gantt ◽  
S. F. Conti
Keyword(s):  
Red Algae ◽  
Close Association ◽  
Red Alga ◽  
Culture Conditions ◽  
Porphyridium Cruentum ◽  
Acetone Extraction

Small granules with a diameter of approximately 350 A are attached to the chloroplast lamellae of the red alga Porphyridium cruentum. To some extent, their size depends on the culture conditions and the age of the cell. It was possible to preserve the granules only with aldehyde prefixation. It can be seen that fixed or negatively stained granules are comprised of smaller subunits. The granules are arranged regularly on the lamellae in repeating rows with a center-to-center granule distance of 400 to 500 A. Attempts at characterization of these chloroplast granules revealed that they are resistant to hydrolysis by ribonuclease and appear to be structurally unaffected by methanol-acetone extraction. Because of their close association with the chloroplast lamellae, they are considered as possible sites of phycobilin concentration. This possibility is supported by two observations: when the phycobilins are removed, the granules disappear; and, when the chlorophyll and stainable membrane portions are selectively removed, the phycobilins and granules are still present. It was found that all other marine red algae examined had granules which were associated with the chloroplast lamellae.

scholarly journals The Quantum Yield of Photosynthesis in Porphyridium cruentum, and the Role of Chlorophyll a in the Photosynthesis of Red Algae

1959 ◽  
Vol 43 (2) ◽  
pp. 251-264 ◽  
Author(s):  
Marcia Brody ◽  
Robert Emerson
Keyword(s):  
Quantum Yield ◽  
Red Algae ◽  
Photosynthetic Efficiency ◽  
Red Alga ◽  
Porphyridium Cruentum ◽  
Maximum Efficiency ◽  
Minor Role ◽  
Algal Groups ◽  
A Minor

Quantum yield measurements were made with the red alga Porphyridium cruentum, cultured so as to give different proportions of chlorophyll and phycobilins. Totally absorbing suspensions were used so that there was no uncertainty in the amount of energy absorbed. These measurements have shown that chlorophyll, in this alga, has a photosynthetic efficiency as high as in other algal groups, and higher than the phycobilins—at least at wave lengths shorter than about 650 mµ. Wave lengths longer than this are beyond the range of maximum efficiency of chlorophyll. Under specified conditions of temperature and supplementary light full efficiency may be extended to longer wave lengths. The results of these measurements have made it unnecessary to suppose that in red algae chlorophyll plays a minor role while the phycobilins are the photosynthetic sensitizers of primary importance.

Isolation and characterization of Photosystems I and II from the red alga Porphyridium cruentum

1994 ◽  
Vol 1188 (3) ◽  
pp. 357-366 ◽  
Author(s):  
Gregory R. Wolfe ◽  
Francis X. Cunningham ◽  
Beatrice Grabowski ◽  
Elisabeth Gantt
Keyword(s):  
Red Alga ◽  
Porphyridium Cruentum ◽  
Isolation And Characterization ◽  
Photosystems I And Ii

scholarly journals Studies on the Regulation of Algal Growth by Gibberellin

1971 ◽  
Vol 24 (4) ◽  
pp. 1115 ◽  
Author(s):  
RC Jennings
Keyword(s):  
Red Algae ◽  
Algal Growth ◽  
Red Alga ◽  
General Phenomenon ◽  
Hypnea Musciformis ◽  
Fast Growing ◽  
High Concentrations ◽  
Amo 1618 ◽  
Slow Growing

CCC and Amo.1618, at relatively high concentrations only, inhibited the growth of excised branch apices of the red alga Hypnea musciformis. Neither GA3 nor GA7 stimulated growth of the alga in the presence or absence of these compounds, and gibberellin-like material extracted from H. musciformis also failed to stimulate growth. However, both gibberellins stimulated the growth of slow-growing, but not fast-growing, branch apices of the related red alga Gracilaria verucosa. It is concluded that endogenous gibberellins may not regulate the growth of H. musciformis, but this is likely to be a peculiarity of this species and not a general phenomenon in red algae.

scholarly journals Insights into the Functionality of the Putative Residues Involved in Enterocin AS-48 Maturation

2010 ◽  
Vol 76 (21) ◽  
pp. 7268-7276 ◽  
Author(s):  
Rubén Cebrián ◽  
Mercedes Maqueda ◽  
José Luis Neira ◽  
Eva Valdivia ◽  
Manuel Martínez-Bueno ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
High Efficiency ◽  
Specific Protein ◽  
Culture Conditions ◽  
Site Directed Mutagenesis ◽  
Circular Structure ◽  
Cleavage Enzyme ◽  
Site Recognition ◽  
Biosynthetic Machinery

ABSTRACT AS-48 is a 70-residue, α-helical, cationic bacteriocin produced by Enterococcus faecalis and is very singular in its circular structure and its broad antibacterial spectrum. The AS-48 preprotein consists of an N-terminal signal peptide (SP) (35 residues) followed by a proprotein moiety that undergoes posttranslational modifications to yield the mature and active circular protein. For the study of the specificity of the region of AS-48 that is responsible for maturation, three single mutants have been generated by site-directed mutagenesis in the as-48A structural gene. The substitutions were made just in the residues that are thought to constitute a recognition site for the SP cleavage enzyme (His-1, Met1) and in those involved in circularization (Met1, Trp70). Each derivative was expressed in the enterococcal JH2-2 strain containing the necessary native biosynthetic machinery for enterocin production. The importance of these derivatives in AS-48 processing has been evaluated on the basis of the production and structural characterization of the corresponding derivatives. Notably, only two of them (Trp70Ala and Met1Ala derivatives) could be purified in different forms and amounts and are characterized for their bactericidal activity and secondary structure. We could not detect any production of AS-48 in JH2-2(pAM401-81 His-1Ile ) by using the conventional chromatographic techniques, despite the high efficiency of the culture conditions applied to produce this enterocin. Our results underline the different important roles of the mutated residues in (i) the elimination of the SP, (ii) the production levels and antibacterial activity of the mature proteins, and (iii) protein circularization. Moreover, our findings suggest that His-1 is critically involved in cleavage site recognition, its substitution being responsible for the blockage of processing, thereby hampering the production of the specific protein in the cellular culture supernatant.

Ultrastructural characterization of a pigment mutant of the red alga Palmaria palmata

1984 ◽  
Vol 62 (6) ◽  
pp. 1101-1107 ◽  
Author(s):  
C. M. Pueschel ◽  
J. P. van der Meer
Keyword(s):  
Red Alga ◽  
Palmaria Palmata ◽  
Wild Type ◽  
Ultrastructural Examination ◽  
Dark Treatment ◽  
Prolamellar Bodies ◽  
Ultrastructural Characterization ◽  
Wild Type Control

Ultrastructural examination of a green-pigmented mutant of the red alga Palmaria palmata (L.) O. Kuntze revealed unusual features of the chloroplasts. Encircling peripheral thylakoids, characteristic of the wild-type plastids and florideophyte plastids generally, were lacking. Parallel evenly spaced thylakoids occurred in groups, leaving large volumes of thylakoid-free stroma. Irregularly shaped, electron-dense inclusions with an amorphous substructure and diameters up to 3 μm occurred in some plastids. Cells of the sporeling holdfasts contained structures resembling prolamellar bodies. Attempts to induce formation of prolamellar bodies in blades by dark treatment for 5 weeks were unsuccessful. However, some plastids did develop highly corrugated thylakoids with the crests of one thylakoid apposed to the troughs of the adjacent thylakoid. Thylakoid morphology of the wild-type control was not altered by the absence of light.

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