14CO2-Fixation by the endosymbiotic alga Platymonas convolutae within the turbellrian Convoluta roscoffensis

1975 ◽  
Vol 31 (3) ◽  
pp. 219-226 ◽  
Author(s):  
B. P. Kremer
Keyword(s):  
14Co2 Fixation ◽  
Endosymbiotic Alga ◽  
Convoluta Roscoffensis

A Physiological Comparison of the Symbiotic Alga Platymonas Convolutae and its Free-Living Relatives

1970 ◽  
Vol 50 (1) ◽  
pp. 199-208 ◽  
Author(s):  
G. W. Gooday
Keyword(s):  
Recent Work ◽  
Pure Culture ◽  
Type Species ◽  
Organic Nitrogen ◽  
Soluble Carbohydrates ◽  
Symbiotic Relationship ◽  
Symbiotic Alga ◽  
Free Living ◽  
Unialgal Culture ◽  
Convoluta Roscoffensis

Platymonas convolutae Parke et Manton is the natural algal partner of the symbiotic worm Convoluta roscoffensis Graff (Parke & Manton 1967). Recent work by Provasoli, Yamasu & Manton (1968) has shown that although several algae can form a symbiotic relationship with the worm if supplied in unialgal culture, the natural symbiont is the most effective and is able to eliminate competitors. The alga can be cultured in a denned medium away from its partner, and this paper presents some physiological characteristics of the alga in pure culture in comparison with some of its free-living relatives, in particular the type species of the genus Platymonas, P. tetrathele G. S. West. The present investigation has been concerned mainly with the uptake of carbohydrates and the utilization of organic nitrogen. Other aspects that are included are the excretion of metabolites into the medium and the soluble carbohydrates found within the algae. In addition, culturing the algae has revealed a difference in behaviour of possible relevance to the symbiotic relationship.

Establishment of the symbiosis in Convoluta roscoffensis

1983 ◽  
Vol 63 (2) ◽  
pp. 419-434 ◽  
Author(s):  
A. E. Douglas
Keyword(s):  
Central Region ◽  
Related Species ◽  
Initial Contact ◽  
Structural Studies ◽  
Algal Population ◽  
Recognition Mechanism ◽  
Wide Range ◽  
Algal Photosynthesis ◽  
Convoluta Roscoffensis

Of a wide range of algae tested, juvenile Convoluta roscoffensis ingested only Platymonas convolutae, the natural symbiont; related species of the genera Platymonas, Prasinocladus and Tetraselmis; and Chlamydomonas coccoides. Platymonas convolutae was not ingested to a greater extent than Prasinocladus marinus, Tetraselmis tetrathele and Tetraselmis verrucosa, or taken up in preference to T. verrucosa when animals were exposed to a choice between the two species. Convoluta ingested fewer cells of C. coccoides than P. convolutae and related species. Uptake of P. convolutae was not affected by pretreatment of the cells with lectins or proteases, incubation in media of pH 5·0–9·0 or inhibition of algal photosynthesis, but was substantially reduced if the algae were killed.Cells of P. convolutae, Pr. marinus, T. tetrathele and T. verrucosa persisted and divided in juvenile Convoluta. The algal population in the worms started to increase 2–3 d after ingestion and within 15–20 d the animals were uniformly green. These algae formed a viable symbiosis with Convoluta and promoted the growth of the animals. In contrast, C. coccoides cells did not persist in Convoluta for more than 12–24 h a nd were probably disrupted.P. convolutae cells lost their thecae within a few days of ingestion and before migration from the central to sub-epidermal region of the animal. Animal vacuoles surrounded recently ingested thecate algae. Structural studies of the adult symbiosis suggest that the algae were also intracellular and enclosed in vacuoles.It is proposed that Convoluta discriminates against algae unrelated to P. convolutae on initial contact and in the central region of the host. The nature of the recognition mechanism(s) has not been established.

Light quality effects on subsequent dark 14CO2-fixation in Fucus serratus

Hydrobiologia ◽  
1993 ◽  
Vol 260-261 (1) ◽  
pp. 471-475 ◽  
Author(s):  
G. Tremblin ◽  
P. Jolivet ◽  
A. Coudret
Keyword(s):  
Light Quality ◽  
14Co2 Fixation ◽  
Fucus Serratus

Effect of Salinity on Photosynthetic 14CO2 Fixation and Amino Acid Pools of Bellerochea yucatanensis (v. Stosch) and Thalassiosira rotula (Meunier)

1985 ◽  
Vol 40 (7-8) ◽  
pp. 527-530
Author(s):  
Günter Döhler ◽  
Joachim Zink
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Marine Diatoms ◽  
14Co2 Fixation ◽  
Low Salt ◽  
Photosynthetic Products ◽  
Sugar Phosphates ◽  
Total Amino Acids

Abstract The marine diatoms Bellerochea yucatanensis and Thalassiosira rotula were grown at different salinities (20/25, 35, and 40/45‰ salinity (S), respectively) under normal air (0.035 vol.% CO2). No significant variations in the percentage of gross photosynthetic products (e.g. total amino acids, sugar phosphates) were found as a function of salinity during growth. The bulk of the soluble 14C-radioactivity was detected in amino acids. 14C-labelling of glutamine increased markedly with salinity. Low salt - grown algae are characterized by enhanced amino acid pools, mainly of aspartic acid, asparagine and glutamine. It was found that the tested amino acids are not involved in osmoregulation.

scholarly journals Photosynthetic 14CO2 Fixation in the Leaves of Rice and Some Other Species

1977 ◽  
Vol 46 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Ryuichi ISHII ◽  
Muneaki SAMEJIMA ◽  
Yoshio MURATA
Keyword(s):  
14Co2 Fixation

scholarly journals Dinoflagellates with relic endosymbiont nuclei as models for elucidating organellogenesis

2020 ◽  
Vol 117 (10) ◽  
pp. 5364-5375 ◽  
Author(s):  
Chihiro Sarai ◽  
Goro Tanifuji ◽  
Takuro Nakayama ◽  
Ryoma Kamikawa ◽  
Kazuya Takahashi ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Evolutionary Process ◽  
Dna Transfer ◽  
Free Living ◽  
Genus Level ◽  
Green Algal ◽  
Endosymbiotic Alga ◽  
Two Systems ◽  
Algal Groups ◽  
Genetic Level

Nucleomorphs are relic endosymbiont nuclei so far found only in two algal groups, cryptophytes and chlorarachniophytes, which have been studied to model the evolutionary process of integrating an endosymbiont alga into a host-governed plastid (organellogenesis). However, past studies suggest that DNA transfer from the endosymbiont to host nuclei had already ceased in both cryptophytes and chlorarachniophytes, implying that the organellogenesis at the genetic level has been completed in the two systems. Moreover, we have yet to pinpoint the closest free-living relative of the endosymbiotic alga engulfed by the ancestral chlorarachniophyte or cryptophyte, making it difficult to infer how organellogenesis altered the endosymbiont genome. To counter the above issues, we need novel nucleomorph-bearing algae, in which endosymbiont-to-host DNA transfer is on-going and for which endosymbiont/plastid origins can be inferred at a fine taxonomic scale. Here, we report two previously undescribed dinoflagellates, strains MGD and TGD, with green algal endosymbionts enclosing plastids as well as relic nuclei (nucleomorphs). We provide evidence for the presence of DNA in the two nucleomorphs and the transfer of endosymbiont genes to the host (dinoflagellate) genomes. Furthermore, DNA transfer between the host and endosymbiont nuclei was found to be in progress in both the MGD and TGD systems. Phylogenetic analyses successfully resolved the origins of the endosymbionts at the genus level. With the combined evidence, we conclude that the host–endosymbiont integration in MGD/TGD is less advanced than that in cryptophytes/chrorarachniophytes, and propose the two dinoflagellates as models for elucidating organellogenesis.

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