ETD system

Electronic theses and dissertations repository


Tesi etd-01272014-153514

Thesis type
Tesi di laurea magistrale
email address
The marine flatworm M.lignano as model for nervous system regeneration: role of pro neural genes in the CNS.
Corso di studi
relatore Dott. Tiozzo, Stefano
controrelatore Dott.ssa Isolani, Maria Emilia
controrelatore Dott.ssa Vannini, Claudia
tutor Prof.ssa Batistoni, Renata
Parole chiave
  • Neurogenin
  • scute
  • Achaete
  • Olig
  • NSCL
  • Atonal
  • NeuroD
  • pro neural genes
  • central nervous system
  • CNS
  • Macrostomum lignano
  • developmental biology
  • regeneration
  • flatworm
Data inizio appello
Riassunto analitico
Research using marine organisms has brought to light universal biological concepts, ever since the beginning of experimental biology. Especially marine invertebrates have always been attractive to cell and developmental biologists due to their inherent practical advantages, which include abundant gametes, external fertilization, large and transparent cells, rapid and synchronous early development, diversity of forms and life cycles, and high regenerative potentials. In particular, Plathelminthes (flatworms) is one of the most exploited taxa for study on regenerative biology. Macrostomum lignano, the most basal taxon of rhabditophoran flatworms, if amputated transversally, can regenerate with different efficacy, according to the level of the amputation. This extraordinary regenerative capacity of M.lignano is brought by a population of pluripotent stem cells, called neoblasts.
In this study I took advantage of the regenerative power of M.lignano and try to understand if and how neoblasts can lead to the reconstruction of the anterior central nervous system (aCNS).
By immunohistochemistry (IHC) I first described the aCNS, providing a simple mapping of the FRMFergic, Cholinergic and Serotonergic neurons. This allowed to develop a microdisection technique aimed to remove only the aCNS without this killing the worm. Confuting what was previously described in literature a complete regeneration of the aCNS was observed within a week.
In order to follow the dynamic of the neoblasts during the regenerative process, Bromodeoxyuridine (BrdU) pulse-chase experiments and cell proliferation assay have been performed at different time points after the aCNS ablation. These experiments showed that during the regeneration the neoblasts migrates from the posterior part of the body to the wound point and proliferate in situ.
I then screened the genome and transcriptome for candidate genes, known to play an early role in neurogenesis in other organisms. Six genes encoding helix-loop-helix (HlH) transcription factors were investigated: homology of NeuroD, Atonal, Acheate scute, NSCL, Olig and Neurogenin has been found;
Analyses of spatio and temporal expression via in situ hybridization quantitative PCR showed that those genes have a low expression during adul homeostasis but gets activated during the regeneration between 18 and 30 hours post injury.
Taken together these preliminary showed that: 1) the regeneration of the aCNS in M.lignano is possible, this opens new possibilities of using this versatile model for study of neurogenesis; 2) the possible co-option of developmental genes during regeneration of a nervous system.