Morphological and Functional Recovery of the Planarian Photosensing System during Head Regeneration

Inoue, Takeshi; Kumamoto, Hiroshi; Okamoto, K.; Umesono, Yoshihiko; Shimizu, Masaki; Alvarado, Alejandro Sánchez; Agata, Kiyokazu

doi:10.2108/zsj.21.275

Cited by 139 publications

(185 citation statements)

References 35 publications

Supporting

Mentioning

165

Contrasting

Unclassified

Order By: Relevance

“…By using a phototaxis assay system that we developed to analyse light response recovery during head regeneration, we found that light evasion is robustly re-established 5 days after amputation. Interestingly, several genes are activated at the late stage of brain regeneration, suggesting that these genes may be involved in functional recovery (Cebrià et al 2002a;Inoue et al 2004). In conclusion, brain regeneration proceeds in a sequential manner accompanied by appropriate changes of gene expression, like embryogenesis.…”

Section: The Regeneration Processmentioning

confidence: 99%

Brain regeneration from pluripotent stem cells in planarian

Agata

Umesono

2008

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

How can planarians regenerate their brain? Recently we have identified many genes critical for this process. Brain regeneration can be divided into five steps: (1) anterior blastema formation, (2) brain rudiment formation, (3) pattern formation, (4) neural network formation, and (5) functional recovery. Here we will describe the structure and process of regeneration of the planarian brain in the first part, and then introduce genes involved in brain regeneration in the second part. Especially, we will speculate about molecular events during the early steps of brain regeneration in this review. The finding providing the greatest insight thus far is the discovery of the nou-darake (ndk; 'brains everywhere' in Japanese) gene, since brain neurons are formed throughout the entire body as a result of loss of function of the ndk gene. This finding provides a clue for elucidating the molecular and cellular mechanisms underlying brain regeneration. Here we describe the molecular action of the nou-darake gene and propose a new model to explain brain regeneration and restriction in the head region of the planarians.

show abstract

Section: The Regeneration Processmentioning

confidence: 99%

Brain regeneration from pluripotent stem cells in planarian

Agata

Umesono

2008

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

show abstract

“…Adult stem cell populations (neoblasts) underlie their remarkable regenerative abilities (Reddien and Sánchez Alvarado, 2004;Wagner et al, 2011), and whole worms can regenerate from only a small proportion of the adult worm: a cut off (or damaged) head is rebuilt perfectly within few days (Inoue et al, 2004;Umesono et al, 2011). Recently, planarians have become a popular molecular-genetic system for the investigation of the pathways that allow complex structures such as the head to be regenerated after damage (Aboobaker, 2011;Gentile et al, 2011;Lobo et al, 2012;Newmark and Sánchez Alvarado, 2002;Saló et al, 2009;Sánchez Alvarado, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…This stunning finding, suggesting that some memory may be stored outside of the head and imprinted on the new brain during regeneration, led to a myriad of subsequent associative learning studies (Cherkashin et al, 1966;Corning, 1966;Corning, 1967;McConnell, 1965;Morange, 2006;Sheiman and Tiras, 1996). The most common procedure was a classical conditioning protocol based on planarians' well-known photosensitivity (Dasheiff and Dasheiff, 2002;Inoue et al, 2004;Prados et al, 2013;Stephen, 1963). Acquired memories that could survive the process of head regeneration were demonstrated by measuring a direct display of a conditioned response or a faster learning rate ('savings') among worm fragments generated from head and tail pieces of previously trained planarians (McConnell et al, 1959).…”

Section: Introductionmentioning

confidence: 99%

An automated training paradigm reveals long-term memory in planaria and its persistence through head regeneration

Shomrat

Levin

2013

Journal of Experimental Biology

102

View full text Add to dashboard Cite

SUMMARYPlanarian flatworms are a popular system for research into the molecular mechanisms that enable these complex organisms to regenerate their entire body, including the brain. Classical data suggest that they may also be capable of long-term memory. Thus, the planarian system may offer the unique opportunity to study brain regeneration and memory in the same animal. To establish a system for the investigation of the dynamics of memory in a regenerating brain, we developed a computerized training and testing paradigm that avoided the many issues that confounded previous, manual attempts to train planarians. We then used this new system to train flatworms in an environmental familiarization protocol. We show that worms exhibit environmental familiarization, and that this memory persists for at least 14days -long enough for the brain to regenerate. We further show that trained, decapitated planarians exhibit evidence of memory retrieval in a savings paradigm after regenerating a new head. Our work establishes a foundation for objective, high-throughput assays in this molecularly tractable model system that will shed light on the fundamental interface between body patterning and stored memories. We propose planarians as key emerging model species for mechanistic investigations of the encoding of specific memories in biological tissues. Moreover, this system is likely to have important implications for the biomedicine of stem-cell-derived treatments of degenerative brain disorders in human adults. Supplementary material available online at

show abstract

“…The planarian nervous system consists of bilobed cerebral ganglia at the anterior end and two longitudinal nerve cords that underlie the ventral body wall musculature and run the length of the animal (Agata et al 1998;Okamoto et al 2005;Cebria 2008). Sensory structures (photoreceptors, chemoreceptors) located at the anterior of the animal send projections to the cephalic ganglia, which then process external signals and direct the appropriate behavioral responses (MacRae 1967;Inoue et al 2004).…”

Section: Introduction To Planarian Biologymentioning

confidence: 99%

Germ Cell Specification and Regeneration in Planarians

Newmark

Wang

Chong

2008

Cold Spring Harbor Symposia on Quantitative Biology

View full text Add to dashboard Cite

In metazoans, two apparently distinct mechanisms specify germ cell fate: Determinate specification (observed in animals including Drosophila, Caenorhabditis elegans, zebra fish, and Xenopus) uses cytoplasmic factors localized to specific regions of the egg, whereas epigenetic specification (observed in many basal metazoans, urodeles, and mammals) involves inductive interactions between cells. Much of our understanding of germ cell specification has emerged from studies of model organisms displaying determinate specification. In contrast, our understanding of epigenetic/inductive specification is less advanced and would benefit from studies of additional organisms. Freshwater planarians-widely known for their remarkable powers of regeneration-are well suited for studying the mechanisms by which germ cells can be induced. Classic experiments showed that planarians can regenerate germ cells from body fragments entirely lacking reproductive structures, suggesting that planarian germ cells could be specified by inductive signals. Furthermore, the availability of the genome sequence of the planarian Schmidtea mediterranea, coupled with the animal's susceptibility to systemic RNA interference (RNAi), facilitates functional genomic analyses of germ cell development and regeneration. Here, we describe recent progress in studies of planarian germ cells and frame some of the critical unresolved questions for future work.

show abstract

Morphological and Functional Recovery of the Planarian Photosensing System during Head Regeneration

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 139 publications

References 35 publications

Brain regeneration from pluripotent stem cells in planarian

Brain regeneration from pluripotent stem cells in planarian

An automated training paradigm reveals long-term memory in planaria and its persistence through head regeneration

Germ Cell Specification and Regeneration in Planarians

Contact Info

Product

Resources

About