Annotation of nerve cord transcriptome in earthworm Eisenia fetida

Abstract

In annelid worms, the nerve cord serves as a crucial organ to control the sensory and behavioral physiology. The inadequate genome resource of earthworms has prioritized the comprehensive analysis of their transcriptome dataset to monitor the genes express in the nerve cord and predict their role in the neurotransmission and sensory perception of the species. The present study focuses on identifying the potential transcripts and predicting their functional features by annotating the transcriptome dataset of nerve cord tissues prepared by Gong et al., 2010 from the earthworm Eisenia fetida. Totally 9762 transcripts were successfully annotated against the NCBI nr database using the BLASTX algorithm and among them 7680 transcripts were assigned to a total of 44,354 GO terms. The conserve domain analysis indicated the over representation of P-loop NTPase domain and calcium binding EF-hand domain. The COG functional annotation classified 5860 transcript sequences into 25 functional categories. Further, 4502 contig sequences were found to map with 124 KEGG pathways. The annotated contig dataset exhibited 22 crucial neuropeptides having considerable matches to the marine annelid Platynereis dumerilii, suggesting their possible role in neurotransmission and neuromodulation. In addition, 108 human stem cell marker homologs were identified including the crucial epigenetic regulators, transcriptional repressors and cell cycle regulators, which may contribute to the neuronal and segmental regeneration. The complete functional annotation of this nerve cord transcriptome can be further utilized to interpret genetic and molecular mechanisms associated with neuronal development, nervous system regeneration and nerve cord function.

Pontoscolex corethrurus: A homeless invasive tropical earthworm?

“…It is known that in diets of low nutritional quality, mutualistic bacteria residing in earthworm nephridia (in 19 of 23 species studied) provide vitamins to its host, stimulate earlier sexual maturity, and contribute to pesticide detoxification [56, 57, 58, 60, 70, 71]. The results reported here showed that the invasive species of smaller size (biomass) fed on a lower nutritional diet ( M .…”

“…Thus, the likely symbiotic evolution of P . corethrurus with the microbiome (gut, nephridia and cocoons) should be explored as a source of biogeography and phylogenetic information [11, 57, 68, 70, 71, 73, 74]. That is, we could “…explain why P .…”

Pontoscolex corethrurus:a Homeless Invasive Tropical Earthworm?

“…Cryptic invasions occur frequently, often go unnoticed, and are hard to recognize. Also, it is known that cryptic species may display markedly different responses to a given stimulus or stressor (Liebeke et al 2014;Schult et al 2016;Morais and Reichard 2018 (Kille et al 2013;Liu et al 2017;Ponesakki et al 2017;Fernández-Marchán et al 2018). Last, potential symbionts may be found for each agrotype, including bacteria, nematodes, enchytraeids and other life forms associated with earthworms (Coates 1990;Fernández-Marchán et al 2018).…”

“…This suggests that P. corethrurus consumes and degrades a greater variety of organic materials given its greater ability (efficiency), evidenced by: a) producing endogenous cellulases: Ean-Eg, EF-EG2, and GHF9(Nozaki et al 2009; Shweta 2012; Ueda et al. 2014;Park et al 2017); b) its association with the gut microbiota: Protobacteria, Firmicutes, Actinobacteria, Chloroflexi, and Bacteroidete(Thakuria et al 2010;Liu et al 2017;Gong et al 2018;Liu et al 2018); c) expressing genes (transcriptome) that contribute to the adaptation of its digestive system: salivation, gastric acid, and pancreatic secretion; d) improving its digestion efficiency according to the type of cecum(Nozaki et al 2013; Ikeda et al 2017); e) its association with nephridial Pedobacter bacteria(Davidson and Stahl 2006; Menezes et al 2018).It is known that in diets of low nutritional quality, mutualistic bacteria (Bacteroidetes, Betaproteobacteria and Alphaproteobacteria) residing in earthworm nephridia (in 19 of 23 species studied) provide vitamins to its host, stimulate earlier sexual maturity, and contribute to pesticide detoxificationLund et al 2010aLund et al , 2010bMøller et al 2015;Ponesakki et al 2017;Aira et al 2018). The results reported here showed that a lower nutritional quality of the diet (M. pruriens > corn stubble > soil) translated into invasive species of smaller size (biomass) that reached sexual maturity earlier than the native earthworm.…”

The draft genome of a new Verminephrobacter eiseniae strain: a nephridial symbiont of earthworms

“…The P-loop NTPase is a prevalent domain, characterized by the presence of 2 signature motifs called Walker A and Walker B, which binds to the NTPs and Mg2+ cation, respectively (Walker et al 1982). The domain assists in energy production by NTP hydrolysis and acts as a substrate for nucleotide binding (Ponesakki et al 2017). The P-loop containing nucleoside triphosphate hydrolase superfamily proteins play a crucial role in determining the host specificity of the endophyte Streptomyces scabrisporus NF3 during symbiosis (Ceapă et al 2018).…”