De novo Assembly and Analysis of Tissue-Specific Transcriptomes of the Edible Red Sea Urchin Loxechinus albus Using RNA-Seq

Edible red sea urchin (Loxechinus albus) is an endemic echinoderm species of the Chilean coasts. The worldwide demand for high-quality gonads of this species has addressed the depletion of its natural populations. Studies on this sea urchin are limited, and genomic information is almost nonexistent. Hence, generate a transcriptome is crucial information that will considerably enrich molecular data and promote future findings for the L. albus aquaculture. Here, we obtained transcriptomic data of the edible red sea urchin by Illumina platform. Total RNA was extracted from gonads, intestines, and coelomocytes of juvenile urchins, and samples were sequenced using MiSeq Illumina technology. A total of 91,119,300 paired-end reads were de novo assembled, 185,239 transcripts produced, and a reference transcriptome created with 38.8% GC content and an N50 of 1769 bp. Gene ontology analysis revealed notable differences in the expression profiles between gonads, intestines, and coelomocytes, allowing the detection of transcripts associated with specific biological processes and KEGG pathways. These data were validated using 12 candidate transcripts by real-time qPCR. This dataset will provide a valuable molecular resource for L. albus and other species of sea urchins.

Chilean benthic species identified as a new source of antibiotic substances

Benthic marine organisms are a natural source of bioactive substances with applications in medicine to treat infections, cancer and other diseases. In Chile, this community possesses rich biodiversity that has been scarcely studied as a producer of bioactive substance so far. For that reason, we studied the potential production of antibiotic substances in 28 benthic species that inhabit the coast of the Tarapacá region in northern Chile, and belong to phylum Porifera, Cnidaria, Mollusca, Sipuncula, Annelida, Echinodermata and Chordata. The antibiotic activity was evaluated on ethanol extract obtained from their entire body or dissected tissues and was tested against Staphylococcus aureus ATCC 25923 with the diffusion agar method. According to the halo diameter, the antibiotic potency was classified as mild, regular or high. In this way, we could identify 21 benthic species as a producer of antibiotic substances with different antibiotic potency. This activity was found in more than one tissue and with regular or high antibiotic activity in the species; Acanthopleura echinata, Chiton cumingsii, Aulacomya atra, Fissurella crassa, Fissurella latimarginata, Luidia magellanica, Stichaster striatus, Arbacia spatuligera, and Loxechinus albus. The extracts obtained from the entire body and showed regular and high antibiotic activity were from the species; Phymanthea pluvia, Abarenicola affinis, Glycera americana, and Ophiactis kroyeri. In conclusion, northern Chile possesses a rich biodiversity of benthic species producer of antibiotic substances, and more research is encouraged to identify these substances with application in medicine.

Sampling Procedure for Establishing Criteria for Sea Urchin (Loxechinus albus) Proportion under the Legal Minimum Length of landings

Sea urchin (Loxechinus albus) is one of the most economically important species in the northeast of Chilean Patagonia, forming part of the highly diverse benthic community. This resource is being harvested under selective fishing pressure, which suppresses growth rates. In response, the National Standards Institute established Regulation 44 as a quality control measure, based on a sampling approach considering the percentage of sea urchin under the minimum legal size (UMLS) through an acceptance sampling plan. In 2019, the Chilean Undersecretary of Fisheries and Aquaculture (SUBPESCA), under Exempt Resolution No. 910, ruled that any vessel that landed 15% with sea urchin of 6.5 cm UMLS of the total catch weight will be sanctioned. In this paper, a sampling design is presented to establish criteria regarding compliance with this provision. The plan provides a statistical methodology for the evaluation of the percentage of UMLS sea urchin, which corroborates and certifies the current legislation that sanctions and fines the capture of sea urchin that does not comply with UMLS values outlined in Regulation 44. Assuming a systematic sampling plan and under assumed UMLS values of 6.0, 6.5, and 7.0 cm, it is determined that 15% of total landings (margin of tolerance) of sea urchin under 6.5 cm is the optimal level. Thus, a correct specification of the UMLS allows protecting the most vulnerable fraction of the population from overexploitation for growth.

Microbial Diversity of the Red Sea Urchin Loxechinus albus during Controlled Farming in Puerto Montt, Chile, Using 16S rRNA Gene Amplicon Sequencing

Loxechinus albus is a shallow-water sea urchin, and its distribution is related to the cold water of the Southern Hemisphere. Recently, bacterial communities, also called microbiota, in sea urchins have started being explored. In this report, we have characterized the surface, testa, and gonad microbiota using 16S rRNA sequencing.

Abundancia y estructura poblacional de dos recursos pesqueros bentónicos fuera y dentro del área de una concesión marítima portuaria en Caldera, Región de Atacama, Chile

This study compares density and size structure of kelp Lessonia berteroana and sea urchins Loxechinus albus inside and outside a port concession area in Caldera. Greater abundance and larger adult individuals in populations of both benthic resources in this zone preliminarily indicates that this might be replicating a marine protected area. In the future, this port concession could contribute to the conservation of benthic resources as a reference site, without access to fisheries, useful for validating or implementing measures and actions in management plans or other instruments to support conservation.

Diagnóstico de las Actividades Pesqueras en la Región Tacna, Periodo 1998-2007

En el presente artículo se realiza el análisis de las diversas actividades pesqueras desarrolladas en el ámbito marino y continental de la región Tacna. La pesquería en esta región es de carácter netamente artesanal, no existe pesca industrial. El producto de la pesquería marítima (peces, moluscos, crustáceos y equinodermos) está destinado mayormente para el consumo humano directo. Los únicos recursos hidrobiológicos utilizados en el procesamiento o transformación, además de las ovas de erizo de mar Loxechinus albus y de pez volador, es la anchoveta Engraulis ringens, exportada con el nombre de "anchoa". En el ámbito continental la actividad pesquera se circunscribe a la extracción de trucha arco iris Oncorhynchus mykiss en los ríos y lagunas altoandinas y del recurso camarón de río Cryphiops caementarius en la cuenca baja del río Sama.