Identification and localization of growth factor genes in the sea cucumber, Holothuria scabra.

The sea cucumber Holothuria scabra is both an economically important species in Asian countries and an emerging experimental model for research studies in regeneration and medicinal bioactives. Growth factors and their receptors are known to be key components that guide tissue repair and renewal, yet validation of their presence in H. scabra has not been established. We performed a targeted in silico search of H. scabra transcriptome data to elucidate conserved growth factor family and receptor genes. In total, 42 transcripts were identified, of which 9 were validated by gene cloning and sequencing. The H. scabra growth factor genes, such as bone morphogenetic protein 2A (BMP 2A), bone morphogenetic protein 5-like (BMP5-like), neurotrophin (NT) and fibroblast growth factor 18 (FGF18), were selected for further analyses, including phylogenetic comparison and spatial gene expression using RT-PCR and in situ hybridization. Expression of all genes investigated were widespread in multiple tissues. However, BMP 2A, BMP5-like and NT were found extensively in the radial nerve cord cells, while FGF18 was highly expressed in connective tissue layer of the body wall. Our identification and expression analysis of the H. scabra growth factor genes provided the molecular information of growth factors in this species which may ultimately complement the research in regenerative medicine.

Vision Guides Selection of Freeze or Flight Defense Strategies in Mice.

In prey species such as mice, avoidance of predators is key to survival and drives instinctual behaviors like freeze or flight [1, 2]. Sensory signals guide the selection of appropriate behavior [3], and for aerial predators only vision provides useful information. Surprisingly, there is no evidence that vision can guide the selection of escape strategies. Fleeing behavior can be readily triggered by a rapidly looming overhead stimulus [4]. Freezing behavior, however, has previously been induced by real predators or their odors [5]. Here, we discover that a small moving disk, simulating the sweep of a predator cruising overhead, is sufficient to induce freezing response in mice. Looming and sweeping therefore provide visual triggers for opposing flight and freeze behaviors and provide evidence that mice innately make behavioral choices based on vision alone. VIDEO ABSTRACT.