Effective Techniques for the Feeding and Ex Situ Culture of a Brooding Scleractinian Coral, Pocillopora acuta.

Climate change is affecting the survival, growth, and recruitment of corals globally, with large-scale shifts in abundance and community composition expected in reef ecosystems over the next several decades. Recognition of this reef degradation has prompted a range of novel research- and restoration-based active interventions. Ex situ aquaculture can play a supporting role through the establishment of robust coral culture protocols (e.g., to improve health and reproduction in long-term experiments) and through the provision of a consistent broodstock supply (e.g., for use in restoration projects). Here, simple techniques for the feeding and ex situ culture of brooding scleractinian corals are outlined using the common and well-studied coral, Pocillopora acuta, as an example. To demonstrate this approach, coral colonies were exposed to different temperatures (24 °C vs. 28 °C) and feeding treatments (fed vs. unfed) and the reproductive output and timing, as well as the feasibility of feeding Artemia nauplii to corals at both temperatures, was compared. Reproductive output showed high variation across colonies, with differing trends observed between the temperature treatments; at 24 °C, fed colonies produced more larvae than unfed colonies, but the opposite was found in colonies cultured at 28 °C. All colonies reproduced before the full moon, and differences in reproductive timing were only found between unfed colonies in the 28 °C treatment and fed colonies in the 24 °C treatment (mean lunar day of reproduction ± standard deviation: 6.5 ± 2.5 and 11.1 ± 2.6, respectively). The coral colonies fed efficiently on Artemia nauplii at both treatment temperatures. These proposed feeding and culture techniques focus on the reduction of coral stress and the promotion of reproductive longevity in a cost-effective and customizable manner, with versatile applicability in both flow-through and recirculating aquaculture systems.

[The Nodal regulated dusp4 inhibits mesendoderm formation during zebrafish gastrulation].

MAP kinase phosphatase-2 (MKP-2/DUSP4), a dual specificity protein phosphatase with tyrosine/serine/ threonine phosphatase activity, is associated with cellular proliferation and differentiation, but its functions during embryo development are unclear. To study the developmental function of dusp4, we first examined the spatiotemporal expression pattern of this gene during zebrafish embryonic development by whole mount in situ hybridization. We found that dusp4 was maternally expressed since its transcripts were present from the one-cell to the 256-cell stages. At early gastrulation stages, dusp4 transcripts specifically distributed at margin region, where the mesendodermal cells were located. Further-more, Nodal signal was crucial for dusp4 expression. The expression of dusp4 was obviously increased in Nodal ligand overexpressed embryos, while its expression was almost lost in the Nodal signal-deficient MZoep mutants. In addition, dusp4 MO was also designed to knock down its expression in embryos. The mesendoderm formation was significantly in-creased in dusp4 morphants, but not obviously changed in dusp4 overexpressed embryos, suggesting that dusp4 is necessary, but not sufficient for the inhibitory of mesendoderm induction. Thus, our results indicate that Nodal regulated dusp4 plays a repressive role in mesendoderm induction.