Browsing by Author "Heesch, Svenja"
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- Origin and evolutionary trajectories of brown algal sex chromosomes.Publication . Barrera-Redondo, Josué; Lipinska, Agnieszka P.; Liu, Pengfei; Dinatale, Erica; Cossard, Guillaume; Bogaert, Kenny; Hoshino, Masakazu; Craig, Rory J.; Avia, Komlan; Leiria, Goncalo; Avdievich, Elena; Liesner, Daniel; Luthringer, Rémy; Godfroy, Olivier; Heesch, Svenja; Nehr, Zofia; Brillet-Guéguen, Loraine; Peters, Akira F.; Hoarau, Galice; Pearson, Gareth Anthony; Aury, Jean-Marc; Wincker, Patrick; Denoeud, France; Cock, J Mark; Haas, Fabian B.; Coelho, Susana M.Research on the biology and evolution of sex chromosomes has primarily focused on diploid XX/XY and ZW/ZZ systems. In contrast, the rise, evolution and demise of U/V systems has remained an enigma. Here we analyse genomes of nine brown algal species with different sexual systems to determine the history of their sex determination. U/V sex chromosomes emerged between 450 and 224 million years ago, when a region containing the pivotal male-determinant MIN ceased recombining. Seven ancestral genes within the sex-determining region show remarkable conservation over this vast evolutionary time, although nested inversions caused expansions of the sex locus, independently in each lineage. We evaluate whether these expansions are associated with increased morphological complexity and sexual differentiation, and show that taxonomically restricted genes evolve unexpectedly often in U and V chromosomes. We also investigate two situations in which U/V-linked regions have changed. First, we demonstrate that convergent evolution of two monoicous species occurred by ancestral males acquiring U-specific genes. Second, the Fucus dioecious system involves new sex-determining gene(s), acting upstream of formerly V-specific genes during development. Both situations have led to the demise of U and V chromosomes and erosion of their specific genomic characteristics.
- Red algal extracts from Plocamium lyngbyanum and Ceramium secundatum stimulate osteogenic activities in vitro and bone growth in zebrafish larvaePublication . Carson, Matthew A.; Nelson, John; Cancela, M. Leonor; Laizé, Vincent; Gavaia, Paulo J.; Rae, Margaret; Heesch, Svenja; Verzin, Eugene; Maggs, Christine; Gilmore, Brendan F.; Clarke, Susan A.Through the current trend for bioprospecting, marine organisms-particularly algae-are becoming increasingly known for their osteogenic potential. Such organisms may provide novel treatment options for osteoporosis and other musculoskeletal conditions, helping to address their large healthcare burden and the limitations of current therapies. In this study, extracts from two red algae-Plocamium lyngbyanum and Ceramium secundatum-were tested in vitro and in vivo for their osteogenic potential. In vitro, the growth of human bone marrow stromal cells (hBMSCs) was significantly greater in the presence of the extracts, particularly with P. lyngbyanum treatment. Osteogenic differentiation was promoted more by C. secundatum (70 mu g/ml), though P. lyngbyanum had greater in vitro mineralisation potential. Both species caused a marked and dose-dependent increase in the opercular bone area of zebrafish larvae. Our findings therefore indicate the presence of bioactive components in P. lyngbyanum and C. secundatum extracts, which can promote both in vitro and in vivo osteogenic activity.
- Screening for osteogenic activity in extracts from Irish marine organisms: the potential of Ceramium pallidumPublication . Carson, Matthew A.; Nelson, John; Cancela, M. Leonor; Laizé, Vincent; Gavaia, Paulo; Rae, Margaret; Heesch, Svenja; Verzin, Eugene; Gilmore, Brendan F.; Clarke, Susan A.Extracts and compounds derived from marine organisms have reportedly shown some osteogenic potential. As such, these bioactives may aid in the treatment of musculoskeletal conditions such as osteoporosis; helping to address inefficacies with current treatment options. In this study, 72 fractions were tested for their in vitro osteogenic activity using a human foetal osteoblast (hFOB) cell line and bone marrow derived mesenchymal stem cells (MSCs), focusing on their cytotoxic, proliferative and differentiation effects. Extracts dissolved in dimethyl sulfoxide and ethanol showed no significant osteogenic potential. However, two extracts derived from powder residues (left over from original organic extractions) caused a significant promotion of MSC differentiation. Bioactivity from powder residues derived from the epiphytic red algae Ceramium pallidum is described in detail to highlight its treatment potential. In vitro, C. pallidum was shown to promote MSC differentiation and extracellular matrix mineralisation. In vivo, this extract caused a significant increase in opercular bone growth of zebrafish larvae and a significant increase in bone density of regenerated adult caudal fins. Our findings therefore show the importance of continued screening efforts, particularly of novel extract sources, and the presence of bioactive compounds in C. pallidum extract.