Jasmonates and Ethylene Shape Floridoside Synthesis during Carposporogenesis in the Red Seaweed .

Floridoside is a galactosyl-glycerol compound that acts to supply UDP-galactose and functions as an organic osmolyte in response to salinity in Rhodophyta. Significantly, the UDP-galactose pool is shared for sulfated cell wall galactan synthesis, and, in turn, affected by thallus development alongside carposporogenesis induced by volatile growth regulators, such as ethylene and methyl jasmonate, in the red seaweed . In this study, we monitored changes in the floridoside reservoir through gene expression controlling both the galactose pool and glyceride pool under different reproductive stages of and we considered changing salinity conditions.

S-Assimilation Influences in Carrageenan Biosynthesis Genes during Ethylene-Induced Carposporogenesis in Red Seaweed .

The synthesis of cell-wall sulfated galactans proceeds through UDP galactose, a major nucleotide sugar in red seaweed, whilst sulfate is transported through S-transporters into algae. Moreover, synthesis of ethylene, a volatile plant growth regulator that plays an important role in red seaweed reproduction, occurs through S-adenosyl methionine. This means that sulfur metabolism is involved in reproduction events as well as sulfated galactan synthesis of red seaweed.

Expression of Genes Related to Carrageenan Synthesis during Carposporogenesis of the Red Seaweed .

Carrageenan, the foremost constituent of extracellular matrix of some rhodophyta, is a galactan backbone with a different number of sulphate groups attached. Variations of degree of sulphation are associated with different types of carrageenans, which vary according to seaweed life cycles, and have consequences for the exploitation of this raw material. In this work, we used three well-recognised stages of development thalli and two stages of cystocarp maturation to analyse genes that encode addition and elimination of sulphate groups to cell-wall galactan of the red seaweed .

Analysis of the Transcriptome of the Red Seaweed with Emphasis on Reproductive Potential.

is an intertidal marine seaweed and candidate model organism for both industry and academic research, owing to its ability to produce raw materials such as carrageenan. Here we report on the transcriptome of with the aim of providing new insights into the metabolic pathways and other functional pathways related to the reproduction of species. Next-generation sequencing was carried out with subsequent de novo assembly and annotation using state-of-the-art bioinformatic protocols.

Analysis of ethylene-induced gene regulation during carposporogenesis in the red seaweed Grateloupia imbricata (Rhodophyta).

Ethylene favors carposporogenesis in the red seaweed Grateloupia imbricata. Analyses of cystocarp development in vitro in thalli treated with ethylene suggest an interconnection between polyamine and ethylene biosynthesis pathways. Yet, little is known about molecular mechanisms underlying carposporogenesis.

Molecular mechanisms underlying Grateloupia imbricata (Rhodophyta) carposporogenesis induced by methyl jasmonate.

When applied in vitro, methyl jasmonate is sensed by the red seaweed Grateloupia imbricate, substantially and visually affecting its carposporogenesis. However, although there is some understanding of the morphological changes induced by methyl jasmonate in vitro, little is known about the genes that are involved in red seaweed carposporogenesis and how their protein products act. For the work reported herein, the expression of genes in red seaweed that encode enzymes involved in the synthesis of methyl jasmonate (jasmonic acid carboxyl methyl transferase and a putative methyl transferase) was monitored.

Furthering knowledge of seaweed growth and development to facilitate sustainable aquaculture.

Macroalgae (seaweeds) are the subject of increasing interest for their potential as a source of valuable, sustainable biomass in the food, feed, chemical and pharmaceutical industries. Compared with microalgae, the pace of knowledge acquisition in seaweeds is slower despite the availability of whole-genome sequences and model organisms for the major seaweed groups. This is partly a consequence of specific hurdles related to the large size of these organisms and their slow growth.

Occurrence of jasmonates during cystocarp development in the red alga Grateloupia imbricata.

In this study, we highlight the effects of methyl jasmonate (MeJa) on cystocarp development in the red macroscopic alga Grateloupia imbricata. In G. imbricata, jasmonate release is related to the reproductive state, as fertile thalli (i.

In silico characterization of DNA motifs associated with the differential expression of the ornithine decarboxylase gene during in vitro cystocarp development in the red seaweed Grateloupia imbricata.

To gain a better understanding of the regulatory mechanism(s) modulating expression of the ornithine decarboxylase gene ODC during cystocarp development in the red seaweed Grateloupia imbricata, DNA motifs found in the 5'-upstream region of the gene were identified by in silico analysis. In addition, when infertile G. imbricata thalli were treated with ethylene, methyl jasmonate, or light as an elicitor of cystocarp development, different ODC expression patterns were observed.

On reproduction in red algae: further research needed at the molecular level.

Multicellular red algae (Rhodophyta) have some of the most complex life cycles known in living organisms. Economically valuable seaweeds, such as phycocolloid producers, have a triphasic (gametophyte, carposporophyte, and tetrasporophyte) life cycle, not to mention the intricate alternation of generations in the edible "sushi-alga" nori. It is a well-known fact that reproductive processes are controlled by one or more abiotic factor(s), including day length, light quality, temperature, and nutrients.

Production of volatiles by the red seaweed Gelidium arbuscula (Rhodophyta): emission of ethylene and dimethyl sulfide.

The effects of different light conditions and exogenous ethylene on the emission of volatile compounds from the alga Gelidium arbuscula Bory de Saint-Vincent were studied. Special emphasis was placed on the possibility that the emission of ethylene and dimethyl sulfide (DMS) are related through the action of dimethylsulfoniopropionate (DMSP) lyase. The conversion of DMSP to DMS and acrylate, which is catalyzed by DMSP lyase, can indirectly support the synthesis of ethylene through the transformation of acrylate to ethylene.

EFFECTS OF ETHYLENE ON TETRASPOROGENESIS IN PTEROCLADIELLA CAPILLACEA (RHODOPHYTA)(1).

The effects of ethylene (C2 H4 ) on tetrasporogenesis of the red seaweed Pterocladiella capillacea (S. G. Gmelin) Bornet were investigated.

Polyamines increase carpospore output and growth during in vitro cultivation of Hydropuntia cornea.

Carpospore output and development in the marine red alga Hydropuntia cornea J. Agardh. were increased by adding polyamines (PAs) (putrescine, spermidine and spermine) singly or in combinations at 10(-9), 10(-6) and 10(-3) M.

Differential expression of the ornithine decarboxylase gene during carposporogenesis in the thallus of the red seaweed Grateloupia imbricata (Halymeniaceae).

This paper describes the cloning of the ornithine decarboxylase gene from a red seaweed, Grateloupia imbricata (Rhodophyta), the characterization of its expression throughout the reproductive process, and demonstrates how polyamines are involved in seaweed reproduction. In addition, the data indicate that the basal perennial and non-spore-forming thalli behave physiologically and genetically differently from the distal reproductive tissue. The common polyamines putrescine, spermidine and spermine have been associated with carposporogenesis in red seaweeds.

Transglutaminase activity decrease during acclimation to hyposaline conditions in marine seaweed Grateloupia doryphora (Rhodophyta, Halymeniaceae).

Polyamines (PAs), such as diamine putrescine (PUT), triamine spermidine (SPD) and tetraamine spermine (SPM) have been related to environmental stress, including salt stress. A marine red macrophyte alga Grateloupia doryphora (Montagne) Howe was used to investigate the role of PAs during acclimation to moderate hyposaline conditions (incubation 24h in 18 psu seawater as compared to 36 psu of natural seawater). The results obtained showed that a moderate hyposaline shock caused an increase in the free fraction of PUT, SPD and SPM, mainly due to a decrease in TGase activity, together with an apparent increase in the l-arginine dependent PAs synthesis (ODC and arginase decreased, and ADC slightly increased).

Chemical composition of the sponge Hymeniacidon sanguinea from the Canary Islands.

The fatty acid composition of the lipids from the sponge Hymeniacidon sanguinea was investigated and 73 acids were identified. Three of them were new and their structures, elucidated by gas chromatography/mass spectrometry, were identified as 13-methyl-icosanoic, 15-methyl-docosanoic and 3,13-dimethyl-tetradecanoic. Only 12 sterols were present, with cholestanol predominating in the volatile fraction; 22 compounds were identified, mainly hydrocarbons and fatty acids.