ORIGIN OF THE MESODERM AND BEHAVIOR OF THE NUCLEOLUS IN REGENERATION IN<i>LUMBRICULUS</i>

Sayles, Leonard P.

doi:10.2307/1537098

Cited by 18 publications

(3 citation statements)

References 5 publications

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“…The observed increase in NUCLEOSTEMIN signal (nucleolar marker) within neoblast progeny cells at wounds suggests these cells have an increased growth rate. Nucleolar size also increases at the wound site in the regenerating organism Lumbriculus (Sayles, 1927). At 48h post amputation, we also found an accumulation of neoblast progeny expressing differentiation markers.…”

Section: Discussionmentioning

confidence: 99%

Planarian regeneration involves distinct stem cell responses to wounds and tissue absence

Wenemoser

Reddien

2010

Developmental Biology

295

368

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Regeneration requires signaling from a wound site for detection of the wound, and a mechanism that determines the nature of the injury to specify the appropriate regenerative response. Wound signals and tissue responses to wounds that elicit regeneration remain poorly understood. Planarians are able to regenerate from essentially any type of injury and present a novel system for the study of wound responses in regeneration initiation. Newly developed molecular and cellular tools now enable study of regeneration initiation using the planarian Schmidtea mediterranea. Planarian regeneration requires adult stem cells called neoblasts and amputation triggers two peaks in neoblast mitoses early in regeneration. We demonstrate that the first mitotic peak is a body-wide response to any injury and that a second, local, neoblast response is induced only when injury results in missing tissue. This second response was characterized by recruitment of neoblasts to wounds, even in areas that lack neoblasts in the intact animal. Subsequently, these neoblasts were induced to divide and differentiate near the wound, leading to formation of new tissue. We conclude that there exist two functionally distinct signaling phases of the stem cell wound response that distinguish between simple injury and situations that require the regeneration of missing tissue.

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Section: Discussionmentioning

confidence: 99%

Planarian regeneration involves distinct stem cell responses to wounds and tissue absence

Wenemoser

Reddien

2010

Developmental Biology

295

368

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“…The slider cells we identified in our time-lapse movies closely match descriptions of neoblasts made from static images of a range of clitellate annelid species. Neoblasts have been reported to be spindle-shaped cells, with a large nucleus to cytoplasm ratio, located primarily on the dorsal surface of the ventral nerve cord, and, based on sequential still shots during regeneration, inferred to migrate to wound sites [ 42 , 46 , 51 , 56 , 59 ]. The slider cells of P. leidyi match this description, strongly suggesting that these cells in whole or in part comprise the same cell type that has been referred to as neoblasts in other clitellate species.…”

Section: Resultsmentioning

confidence: 99%

Long-term time-lapse live imaging reveals extensive cell migration during annelid regeneration

2016

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BackgroundTime-lapse imaging has proven highly valuable for studying development, yielding data of much finer resolution than traditional “still-shot” studies and allowing direct examination of tissue and cell dynamics. A major challenge for time-lapse imaging of animals is keeping specimens immobile yet healthy for extended periods of time. Although this is often feasible for embryos, the difficulty of immobilizing typically motile juvenile and adult stages remains a persistent obstacle to time-lapse imaging of post-embryonic development.ResultsHere we describe a new method for long-duration time-lapse imaging of adults of the small freshwater annelid Pristina leidyi and use this method to investigate its regenerative processes. Specimens are immobilized with tetrodotoxin, resulting in irreversible paralysis yet apparently normal regeneration, and mounted in agarose surrounded by culture water or halocarbon oil, to prevent dehydration but allowing gas exchange. Using this method, worms can be imaged continuously and at high spatial-temporal resolution for up to 5 days, spanning the entire regeneration process. We performed a fine-scale analysis of regeneration growth rate and characterized cell migration dynamics during early regeneration. Our studies reveal the migration of several putative cell types, including one strongly resembling published descriptions of annelid neoblasts, a cell type suggested to be migratory based on “still-shot” studies and long hypothesized to be linked to regenerative success in annelids.ConclusionsCombining neurotoxin-based paralysis, live mounting techniques and a starvation-tolerant study system has allowed us to obtain the most extensive high-resolution longitudinal recordings of full anterior and posterior regeneration in an invertebrate, and to detect and characterize several cell types undergoing extensive migration during this process. We expect the tetrodotoxin paralysis and time-lapse imaging methods presented here to be broadly useful in studying other animals and of particular value for studying post-embryonic development.Electronic supplementary materialThe online version of this article (doi:10.1186/s12861-016-0104-2) contains supplementary material, which is available to authorized users.

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“…Many of the proliferating cells ingress from the epidermis and start forming a mass of unpigmented, undifferentiated cells known as blastema ( Figure 1E ). Randolph (1891) , Randolph (1892) , Iwanow (1903) , von Wagner (1906) and Sayles (1927) describe the migration of large cells (named neoblasts) that migrate towards the wound site, proliferate there and contribute to formation of the blastema ( Figures 1D,F,H ); other studies in this species failed to find neoblast migration, especially during anterior regeneration ( Stephenson, 1930 ). At this stage, it is also common to see muscle cells losing their fibrilar shapes and detaching as free myocytes into the coelomic cavity ( Figure 1E ).…”

Section: The Past: the Pioneers Who Described Lumbriculus Regenerationmentioning

confidence: 98%

It Cuts Both Ways: An Annelid Model System for the Study of Regeneration in the Laboratory and in the Classroom

Acosta¹,

Arellano‐Carbajal²,

Gillen³

et al. 2021

Front. Cell Dev. Biol.

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The mechanisms supporting regeneration and successful recovery of function have fascinated scientists and the general public for quite some time, with the earliest description of regeneration occurring in the 8th century BC through the Greek mythological story of Prometheus. While most animals demonstrate the capacity for wound-healing, the ability to initiate a developmental process that leads to a partial or complete replacement of a lost structure varies widely among animal taxa. Variation also occurs within single species based on the nature and location of the wound and the developmental stage or age of the individual. Comparative studies of cellular and molecular changes that occur both during, and following, wound healing may point to conserved genomic pathways among animals of different regenerative capacity. Such insights could revolutionize studies within the field of regenerative medicine. In this review, we focus on several closely related species of Lumbriculus (Clitellata: Lumbriculidae), as we present a case for revisiting the use of an annelid model system for the study of regeneration. We hope that this review will provide a primer to Lumbriculus biology not only for regeneration researchers but also for STEM teachers and their students.

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ORIGIN OF THE MESODERM AND BEHAVIOR OF THE NUCLEOLUS IN REGENERATION INLUMBRICULUS

Abstract: nucleus are the result of an increase in nucleolar substance beyond the amount which can exist within the nucleus as a single droplet. Their presence is not a step in amitosis.

Cited by 18 publications

References 5 publications

Planarian regeneration involves distinct stem cell responses to wounds and tissue absence

Planarian regeneration involves distinct stem cell responses to wounds and tissue absence

Long-term time-lapse live imaging reveals extensive cell migration during annelid regeneration

It Cuts Both Ways: An Annelid Model System for the Study of Regeneration in the Laboratory and in the Classroom

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