Wound plug chemistry and morphology of two species of Caulerpa – a comparative Raman microscopy study

Abstract

Caulerpa spp. form a polymer wound plug that seals their giant cells after mechanical injury, in order to prevent fatal loss of cell material. Initial mass spectrometry and Raman spectroscopy investigations revealed the involvement of the secondary metabolite caulerpenyne in wound sealing polymer formation. In this work, we introduce a comparative Raman spectroscopic study of the wound plug formation in the invasive Caulerpa taxifolia (Valh) Agardh, 1817 and the non-invasive Caulerpa prolifera J.V. Lamour. In both species, the enzymatic transformation of the main secondary metabolite caulerpenyne plays a key role in wound plug formation. An accumulation of caulerpenyne is observed at the inner border of the wound plugs. Furthermore, caulerpenyne and products resulting from its enzymatic transformation and co-polymerization with proteins are found within the wound plug. However, there are significant differences in the chemistry of the wound plugs between the species. The Raman spectra reveal a zonation of the wound plug of C. taxifolia into four chemically distinguishable regions, while that of C. prolifera consists of only three regions with specific chemical composition. These results explain differences in the morphology of the wound plug in both species.

Danger signals – damaged-self recognition across the tree of life

“…Both fungi and macroalgae respond to wounding with the formation of wound plugs that serve to seal the wound. This response can be elicited by mechanical, sterile wounding alone and, thus, clearly depends on the sensing of some kind of DAMP ( Weissflog et al, 2008 ; Hernández-Oñate et al, 2012 ; Grosser et al, 2014 ). Unfortunately, we are not aware of many studies that investigated the early signaling events that lead to wound plug formation in algae.…”

Rising nutrient nitrogen reverses the impact of temperature on photosynthesis and respiration of a macroalga Caulerpa lentillifera (Ulvophyceae, Caulerpaceae)

“…At the end of cultivation 0.10 g fresh algal samples were collected and cut into small sections (about 1.0 cm) with a razor blade. Considering Caulerpa species can form the wound plug after physical injury within less than 1 h (Menzel 1988;Grosser et al 2014), we put the algal sections back to culture condition for 2-h recovery to eliminate the impacts of injury. Then, the small sections were transferred into a photosynthetic chamber.…”