Whole-Body Regeneration in the Lobate Ctenophore Mnemiopsis leidyi

Ctenophores (a.k.a. comb jellies) are one of the earliest branching extant metazoan phyla. Adult regenerative ability varies greatly within the group, with platyctenes undergoing both sexual and asexual reproduction by fission while others in the genus Beroe having completely lost the ability to replace missing body parts. We focus on the unique regenerative aspects of the lobate ctenophore, Mnemiopsis leidyi, which has become a popular model for its rapid wound healing and tissue replacement, optical clarity, and sequenced genome. M. leidyi’s highly mosaic, stereotyped development has been leveraged to reveal the polar coordinate system that directs whole-body regeneration as well as lineage restriction of replacement cells in various regenerating organs. Several cell signaling pathways known to function in regeneration in other animals are absent from the ctenophore’s genome. Further research will either reveal ancient principles of the regenerative process common to all animals or reveal novel solutions to the stability of cell fates and whole-body regeneration.

The Growth of Sea cucumber Stichopus herrmanni After Transverse Induced Fission in Two and Three Fission Plane

Transverse induced fission proven could be done in Teripang Tril, Stichopus herrmanni. This present works aimed to analyze wound recovery, regeneration period and growth of Teripang Trill after asexual reproduction by fission using two and three fission plane. Observations were made every day until the sea cucumber body separated into two or more (depending on treatment) and reared for 16 weeks. The results showed that there are differences in wound recovery, regeneration period and growth of S. herrmanni depend on their different fission plane. The wound recovery and regeneration period (days) of anterior, middle and posterior individu S. herrmanni resulted from two and three fission plane were varied but the two fission plane the anterior individu recover for longer period than posterior part and the wound recover process in both end for thee fission plane was same. Average growth of anterior and posterior fragment were longer for two fission plane than three fission plane. The middle fragment (M1 and M2) both fission plane was able to grow but very low. It showed that three fission plane gave very slow growth in every fragment of the body. Keywords: growth, post-fission, fission plane, Stichopus herrmanni

Phylotranscriptomic analysis uncovers a wealth of tissue inhibitor of metalloproteinases variants in echinoderms

Tissue inhibitors of metalloproteinases (TIMPs) help regulate the extracellular matrix (ECM) in animals, mostly by inhibiting matrix metalloproteinases (MMPs). They are important activators of mutable collagenous tissue (MCT), which have been extensively studied in echinoderms, and the four TIMP copies in humans have been studied for their role in cancer. To understand the evolution of TIMPs, we combined 405 TIMPs from an echinoderm transcriptome dataset built from 41 specimens representing all five classes of echinoderms with variants from protostomes and chordates. We used multiple sequence alignment with various stringencies of alignment quality to cull highly divergent sequences and then conducted phylogenetic analyses using both nucleotide and amino acid sequences. Phylogenetic hypotheses consistently recovered TIMPs as diversifying in the ancestral deuterostome and these early lineages continuing to diversify in echinoderms. The four vertebrate TIMPs diversified from a single copy in the ancestral chordate, all other copies being lost. Consistent with greater MCT needs owing to body wall liquefaction, evisceration, autotomy and reproduction by fission, holothuroids had significantly more TIMPs and higher read depths per contig. Ten cysteine residues, an HPQ binding site and several other residues were conserved in at least 70% of all TIMPs. The conservation of binding sites and the placement of echinoderm TIMPs involved in MCT modification suggest that ECM regulation remains the primary function of TIMP genes, although within this role there are a large number of specialized copies.

EXPERIMENT ON FISSION STIMULATION OF HOLOTHURIA ARTA (HOLOTHUROIDEA, ECHINODERMATA): CHANGING IN BODY WEIGHT AND MORPHOLOGY

Experiment on Holothuria atra provided evidence that asexual reproduction by fission was possible to be stimulated at laboratory. The success of the experiment was determined based on the high survival of stimulated individuals that grew into intact. After being tightened, induced individuals divided into anterior- and posteriorend individuals. During regenerating into intact individuals, the body weight decreased to relatively minimum weight. Developing of new tentacles in posterior-end individuals and anal aperture in anterior-end individuals required 7-8 weeks after fission. These indicators may lead to anatomical recovery which may be a sign of feeding necessity.

Evolution of regeneration and fission in annelids: insights from engrailed- and orthodenticle-class gene expression

The recent explosion of information on the role of regulatory genes in embryogenesis provides an excellent opportunity to study how these genes participate in post-embryonic developmental processes. We present a detailed comparison of regulatory gene expression during regeneration and asexual reproduction (by fission) in the segmented worm Pristina leidyi (Annelida: Oligochaeta). We isolated three genes from Pristina, one homolog of engrailed and two homologs of orthodenticle, and characterized their expression in different developmental contexts. In situ hybridization studies on worms undergoing normal growth, regeneration and fission demonstrate that in all three processes, Pl-en is expressed primarily in the developing nervous system, and Pl-Otx1 and Pl-Otx2 are expressed primarily in the anterior body wall, foregut and developing nervous system. Our data reveal extensive similarities between expression during regeneration and fission, consistent with the idea that similar developmental processes underlie these two types of development. Thus, we argue that in these annelids fission may have evolved by recruitment of regenerative processes. Furthermore, by comparing our data to existing data from leech embryos, we find evidence that embryonic processes are re-deployed during regeneration and fission.