Regeneration in the Segmented Annelid Capitella teleta

The segmented worms, or annelids, are a clade within the Lophotrochozoa, one of the three bilaterian superclades. Annelids have long been models for regeneration studies due to their impressive regenerative abilities. Furthermore, the group exhibits variation in adult regeneration abilities with some species able to replace anterior segments, posterior segments, both or neither. Successful regeneration includes regrowth of complex organ systems, including the centralized nervous system, gut, musculature, nephridia and gonads. Here, regenerative capabilities of the annelid Capitella teleta are reviewed. C. teleta exhibits robust posterior regeneration and benefits from having an available sequenced genome and functional genomic tools available to study the molecular and cellular control of the regeneration response. The highly stereotypic developmental program of C. teleta provides opportunities to study adult regeneration and generate robust comparisons between development and regeneration.

Resolving Transcriptional States and Predicting Lineages in the Annelid Capitella teleta Using Single-Cell RNAseq

Evolution and diversification of cell types has contributed to animal evolution. However, gene regulatory mechanisms underlying cell fate acquisition during development remains largely uncharacterized in spiralians. Here we use a whole-organism, single-cell transcriptomic approach to map larval cell types in the annelid Capitella teleta at 24- and 48-h post gastrulation (stages 4 and 5). We identified eight unique cell clusters (undifferentiated precursors, ectoderm, muscle, ciliary-band, gut, neurons, neurosecretory cells, and protonephridia), thus helping to identify uncharacterized molecular signatures such as previously unknown neurosecretory cell markers in C. teleta. Analysis of coregulatory programs in individual clusters revealed gene interactions that can be used for comparisons of cell types across taxa. We examined the neural and neurosecretory clusters more deeply and characterized a differentiation trajectory starting from dividing precursors to neurons using Monocle3 and velocyto. Pseudotime analysis along this trajectory identified temporally-distinct cell states undergoing progressive gene expression changes over time. Our data revealed two potentially distinct neural differentiation trajectories including an early trajectory for brain neurosecretory cells. This work provides a valuable resource for future functional investigations to better understanding neurogenesis and the transitions from neural precursors to neurons in an annelid.

ANTIBIOFILM ACTIVITY OF Β-HAIPRIN ANTIMICROBIAL PEPTIDES FROM MARINE POLYCHAETA

Recombinant β-hairpin antimicrobial peptides were obtained from marine polychaeta Capitella teleta and Abarenicola pacifica, and their antibiofilm activity was studied.

Structure Elucidation and Functional Studies of a Novel β-hairpin Antimicrobial Peptide from the Marine Polychaeta Capitella teleta

Endogenous antimicrobial peptides (AMPs) are evolutionary ancient molecular factors of innate immunity that play a key role in host defense. Among the most active and stable under physiological conditions AMPs are the peptides of animal origin that adopt a β-hairpin conformation stabilized by disulfide bridges. In this study, a novel BRICHOS-domain related AMP from the marine polychaeta Capitella teleta, named capitellacin, was produced as the recombinant analogue and investigated. The mature capitellacin exhibits high homology with the known β-hairpin AMP family—tachyplesins and polyphemusins from the horseshoe crabs. The β-hairpin structure of the recombinant capitellacin was proved by CD and NMR spectroscopy. In aqueous solution the peptide exists as monomeric right-handed twisted β-hairpin and its structure does not reveal significant amphipathicity. Moreover, the peptide retains this conformation in membrane environment and incorporates into lipid bilayer. Capitellacin exhibits a strong antimicrobial activity in vitro against a wide panel of bacteria including extensively drug-resistant strains. In contrast to other known β-hairpin AMPs, this peptide acts apparently via non-lytic mechanism at concentrations inhibiting bacterial growth. The molecular mechanism of the peptide antimicrobial action does not seem to be related to the inhibition of bacterial translation therefore other molecular targets may be assumed. The reduced cytotoxicity against human cells and high antibacterial cell selectivity as compared to tachyplesin-1 make it an attractive candidate compound for an anti-infective drug design.

Makrozoobentos sebagai Bioindikator Kualitas Perairan di Senggarang Besar Kota Tanjungpinang

Makrozoobentos merupakan organisme yang peka terhadap perubahan lingkungan sehingga sangat baik digunakan sebagai indikator biologis suatu perairan. Penelitian ini bertujuan untuk mengetahui jenis makrozoobentos, tingkat keanekaragaman, keseragaman, dominansi makrozoobentos dan kualitas perairan Senggarang Besar berdasarkan keberadaan makrozoobentos (menggunakan Family Biotic Index). Penelitian menggunakan metode survei. Penentuan stasiun menggunakan metode purposive sampling. Pengambilan sampel makrozoobentos menggunakan line transect dengan transek kuadrat dan core sampler. Makrozoobentos yang ditemukan di Perairan Senggarang Besar yaitu: Anadara granosa, Canarium urceus, Capitella teleta, Cerithium coralium, Nerita ritena, Luidia columbia, Tapes literatus, Nassarius olivaceus, Pirenella cingulata, Planaxis sulcatus, Polymesoda erosa, Pythia scarabaeus, Semiricinula tissoti, dan Terebralia sulcata. Keanekaragaman tertinggi terdapat pada stasiun 2 (H'= 1,91) dan makrozoobentos yang mendominasi dari famili Certhiidae. Keseragaman tertinggi terdapat pada stasiun 3 (E= 0,94) dan makrozoobentos yang mendominasi dari famili Potamididae. Dominansi tertinggi terdapat pada stasiun 1 (C= 0,52) dan makrozoobentos yang mendominasi dari famili Potamididae dan Cerithiidae. Dari keseluruhan parameter fisika-kimia, parameter nitrat dan fosfat tidak memenuhi baku mutu berdasarkan KepMen LH No.51 Tahun 2004 untuk biota laut. Kualitas perairan Senggarang Besar berdasarkan makrozoobentos sebagai bioindikator didapatkan bahwa, stasiun 1 (FBI= 6,94) dengan kategori buruk, stasiun 2 (FBI= 5,6) dengan kategori cukup, stasiun 3 (FBI= 7) dengan kategori buruk.