Generation of Viable Plant-Vertebrate Chimeras

Abstract

The extreme dependence on external oxygen supply observed in animals causes major clinical problems and several diseases are related to low oxygen tension in tissues. The vast majority of the animals do not produce oxygen but a few exceptions have shown that photosynthetic capacity is physiologically compatible with animal life. Such symbiotic photosynthetic relationships are restricted to a few aquatic invertebrates. In this work we aimed to explore if we could create a chimerical organism by incorporating photosynthetic eukaryotic cells into a vertebrate animal model. Here, the microalgae Chlamydomonas reinhardtii was injected into zebrafish eggs and the interaction and viability of both organisms were studied. Results show that microalgae were distributed into different tissues, forming a fish-alga chimera organism for a prolonged period of time. In addition, microscopic observation of injected algae, in vivo expression of their mRNA and re-growth of the algae ex vivo suggests that they survived to the developmental process, living for several days after injection. Moreover microalgae did not trigger a significant inflammatory response in the fish. This work provides additional evidence to support the possibility that photosynthetic vertebrates can be engineered.

Photosymbiosis for Biomedical Applications

“…The fact that O. amblystomatis can stably survive inside the salamander suggests that these unicellular microalgae manage to evade destruction by the vertebrate host’s immune system. Attempts to reproduce this photosymbiont-vertebrate interaction under controlled experimental conditions have been undertaken by two independent research groups, who injected photosynthetic Synechococcus elongatus PCC 7942 cyanobacteria ( Agapakis et al, 2011 ) and Chlamydomonas reinhardtii ( C. reinhardtii ) microalgae ( Alvarez et al, 2015 ), respectively, into zebrafish embryos. In the first study, the authors showed higher biocompatibility of the cyanobacteria (relative to E. coli cells) with the zebrafish embryo.…”

“…They also showed that the photosynthetic organisms were capable of surviving and proliferating inside mammalian cells when cultured under illumination. In the second study, Alvarez et al (2015) established viable plant-vertebrate chimeras, and demonstrated that both the injected algae and the zebrafish embryo/larvae could survive for several days after injection, during which time no significant innate immune response against the “photosymbiont” nor any developmental impairment of the host was observed. The results presented in both studies suggest that, up to a certain level, photosynthetic organisms are well tolerated as foreign bodies by the developing zebrafish.…”

Synthetic transitions: towards a new synthesis

“…Interestingly, the algae remain alive and even reproduce while embryonic development takes place. This opens the possibility of future plant -vertebrate chimaeras where an additional engineering level would allow the production of useful metabolites other than oxygen [153,156].…”

“…On the other hand, C. reinhardtii metabolizes nitrite (NO 2 ) and releases ammonia (NH 3 ) as a nitrogen source for S. cerevisiae [151]. In (c), we display a microscope image of a chimaera zebra fish embryo containing living photosynthetic cells [152,153].…”

Planimal Cells: Artificial Photosynthetic Animal Cells Inspired by Endosymbiosis and Photosynthetic Animals

“…The second approach is microinjection of algae or photosynthetic bacteria into animal cells (Agapakis et al 2011). Recently, the green alga Chlamydomonas reinhardtii was microinjected into zebrafish eggs and survived in embryos and larvae for a few days (Alvarez et al 2015). The main problem in maintaining microinjected algae is preventing exclusion of the algae based on allorecognition including autophagy and the ubiquitin-proteasome system.…”