Project description:Conditional differentiation between haploids and diploids has been proposed to drive the evolutionary stability of isomorphic biphasic life cycles. The cost of producing and maintaining genetic information has been posed as a possible driver of this conditional differentiation. Under this hypothesis, haploids benefit over diploids in resource-limited environments by halving the costs of producing and maintaining DNA. Spared resources can be allocated to enhance survival, growth or fertility. Here we test in the field whether indeed haploids have higher growth rates than diploids. Individuals of the red seaweed Agarophyton chilense, were mapped and followed during 2 years with 4-month census intervals across different stands within the Valdivia River estuary, Chile. As hypothesized, haploids grew larger and faster than diploids, but this was sex-dependent. Haploid (gametophyte) females grew twice as large and 15% faster than diploids (tetrasporophytes), whereas haploid males only grew as large and as fast as the maximum obtained by diploids in summer. However, haploid males maintained their maximum sizes and growth rates constant year-round, while diploids were smaller and had lower growth rates during the winter. In conclusion, our results confirm the conditional differentiation in size and growth between haploids and diploids but also identified important differences between males and females. Besides understanding life cycle evolution, the dynamics of A. chilense frond growth reported informs algal farmers regarding production optimization and should help in determining best planting and harvesting strategies.
| S-EPMC8247958 | biostudies-literature
Project description:Transcriptome of Kappaphycus alvarezii (a commercially important red seaweed)
Project description:The biomedical potential of the edible red seaweed Agarophyton chilense (formerly Gracilaria chilensis) has not been explored. Red seaweeds are enriched in polyunsaturated fatty acids and eicosanoids, which are known natural ligands of the PPARγ nuclear receptor. PPARγ is the molecular target of thiazolidinediones (TZDs), drugs used as insulin sensitizers to treat type 2 diabetes mellitus. Medical use of TZDs is limited due to undesired side effects, a problem that has triggered the search for selective PPARγ modulators (SPPARMs) without the TZD side effects. We produced Agarophyton chilense oleoresin (Gracilex®), which induces PPARγ activation without inducing adipocyte differentiation, similar to SPPARMs. In a diet-induced obesity model of male mice, we showed that treatment with Gracilex® improves insulin sensitivity by normalizing altered glucose and insulin parameters. Gracilex® is enriched in palmitic acid, arachidonic acid, oleic acid, and lipophilic antioxidants such as tocopherols and β-carotene. Accordingly, Gracilex® possesses antioxidant activity in vitro and increased antioxidant capacity in vivo in Caenorhabditis elegans. These findings support the idea that Gracilex® represents a good source of natural PPARγ ligands and antioxidants with the potential to mitigate metabolic disorders. Thus, its nutraceutical value in humans warrants further investigation.
Project description:The red macroalga Agarophyton chilensis is a well-known producer of eicosanoids such as hydroxyeicosatetraenoic acids, but the alga produces almost no prostaglandins, unlike the closely related A. vermiculophyllum. This indicates that the related two algae would have different enzyme systems or substrate composition. To carry out more in-depth discussions on the metabolic pathway of eicosanoids between the two algae, we investigated the characteristics of glycerolipids, which are the substrates of eicosanoids production, of A. chilensis and compared them to the reported values of A. vermiculophyllum. In A. chilensis, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylcholine (PC) were the major lipid classes and accounted for 44.4% of the total lipid extract. The predominant fatty acids were arachidonic acid (20:4n-6), an eicosanoids precursor, and palmitic acid (16:0). The 20:4n-6 content was extremely high in MGDG and PC (>70%), and the 16:0 content was extremely high in DGDG and SQDG (>40%). A chiral-phase HPLC analysis showed that fatty acids were esterified at the sn-1 and sn-2 positions of those lipids. The glycerolipid molecular species were determined by reversed-phase HPLC⁻ESI⁻MS analysis. The main glycerolipid molecular species were 20:4n-6/20:4n-6 (sn-1/sn-2) for MGDG (63.8%) and PC (48.2%), 20:4n-6/16:0 for DGDG (71.1%) and SQDG (29.4%). These lipid characteristics of A. chilensis were almost the same as those of A. vermiculophyllum. Hence, the differences of the eicosanoids producing ability between the two algae would not be due to the difference of substrate composition but the difference of enzyme system.
Project description:Purpose: Examining the transcriptome of human gut bacteria that grow on seaweed polysaccharides as a sole carbon source Methods: Strains were grown on 5 mg/ml seaweed polysaccharides (carrageenan, agarose and/or poprhyran respective to strain) or galactose as a sole carbon source in vitro. Fold change was calculated as seaweed polysaccharide over galactose with n=2 biological replicates. Once cells reached an optical density corresponding to mid-log phase growth, RNA was isolated and rRNA depleted. Samples were multiplexed for sequencing on the Illumina HiSeq platform at the University of Michigan Sequencing Core. Data was analyzed using Arraystar software (DNASTAR, Inc.) Genes with significant up- or down-regulation were determined by the following criteria: genes with an average fold-change >10-fold and with both biological replicates with a normalized expression level >1% of the overall average RPKM expression level. READS WERE ANALYZED .......GABRIEL FILL IN Results: We identified novel polysaccharide utiilization loci in 5 strains of human gut bacteria