Background: Schistosomiasis, or bilharzia, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. Infection by Schistosoma mansoni in humans results when cercariae emerge into water from freshwater snails in the genus Biomphalaria and seek out and penetrate human skin. The snail Biomphalaria straminea is native to South America and is now also present in Central America and China, and represents a potential vector host for spreading schistosomiasis. To date, genomic information for the genus is restricted to the neotropical species Biomphalaria glabrata. This limits understanding of the biology and management of other schistosomiasis vectors, such as B. straminea. Findings: Using a combination of Illumina short-read, 10X Genomics linked-read, and Hi-C sequencing data, our 1.005 Gb B. straminea genome assembly is of high contiguity, with a scaffold N50 of 25.3 Mb. Transcriptomes from adults were also obtained. Developmental homeobox genes, hormonal genes, and stress-response genes were identified, and repeat content was annotated (40.68% of genomic content). Comparisons with other mollusc genomes (including Gastropoda, Bivalvia, and Cephalopoda) revealed syntenic conservation, patterns of homeobox gene linkage indicative of evolutionary changes to gene clusters, expansion of heat shock protein genes, and the presence of sesquiterpenoid and cholesterol metabolic pathway genes in Gastropoda. In addition, hormone treatment together with RT-qPCR assay reveal a sesquiterpenoid hormone responsive system in B. straminea, illustrating that this renowned insect hormonal system is also present in the lophotrochozoan lineage. Conclusion: This study provides the first genome assembly for the snail B. straminea and offers an unprecedented opportunity to address a variety of phenomena related to snail vectors of schistosomiasis, as well as evolutionary and genomics questions related to molluscs more widely.

The sesquiterpenoid hormone juvenile hormone (JH) controls development, reproduction, and metamorphosis in insects, and has long been thought to be confined to the Insecta. While it remains true that juvenile hormone is specifically synthesized in insects, other types or forms of sesquiterpenoids have also been discovered in distantly related animals, such as the jellyfish. Here, we combine the latest literature and annotate the sesquiterpenoid biosynthetic pathway genes in different animal genomes. We hypothesize that the sesquiterpenoid hormonal system is an ancestral system established in an animal ancestor and remains widespread in many animals. Different animal lineages have adapted different enzymatic routes from a common pathway, with cnidarians producing farnesoic acid (FA); non-insect protostomes and non-vertebrate deuterostomes such as cephalochordate and echinoderm synthesizing FA and methyl farnesoate (MF); and insects producing FA, MF, and JH. Our hypothesis revolutionizes the current view on the sesquiterpenoids in the metazoans, and forms a foundation for a re-investigation of the roles of this important and yet neglected type of hormone in different animals.

Chitons (Polyplacophora) are marine molluscs that can be found worldwide from cold waters to the tropics, and play important ecological roles in the environment. However, only two chiton genomes have been sequenced to date. The chiton Liolophura japonica (Lischke, 1873) is one of the most abundant polyplacophorans found throughout East Asia. Our PacBio HiFi reads and Omni-C sequencing data resulted in a high-quality near chromosome-level genome assembly of ∼609 Mb with a scaffold N50 length of 37.34 Mb (96.1% BUSCO). A total of 28,233 genes were predicted, including 28,010 protein-coding ones. The repeat content (27.89%) was similar to that of other Chitonidae species and approximately three times lower than that of the Hanleyidae chiton genome. The genomic resources provided by this work will help to expand our understanding of the evolution of molluscs and the ecological adaptation of chitons.

The long-spined sea urchin Diadema setosum is an algal and coral feeder widely distributed in the Indo-Pacific that can cause severe bioerosion on the reef community. However, the lack of genomic information has hindered the study of its ecology and evolution. Here, we report the chromosomal-level genome (885.8 Mb) of the long-spined sea urchin D. setosum using a combination of PacBio long-read sequencing and Omni-C scaffolding technology. The assembled genome contains a scaffold N50 length of 38.3 Mb, 98.1% of complete BUSCO (Geno, metazoa_odb10) genes (the single copy score is 97.8% and the duplication score is 0.3%), and 98.6% of the sequences are anchored to 22 pseudo-molecules/chromosomes. A total of 27,478 gene models have were annotated, reaching a total of 28,414 transcripts, including 5,384 tRNA and 23,030 protein-coding genes. The high-quality genome of D. setosum presented here is a valuable resource for the ecological and evolutionary studies of this coral reef-associated sea urchin.

Soil biodiversity plays important roles in nutrient recycling in both the environment and agriculture. However, they are generally understudied worldwide. To reveal the diversity of soil macrofauna in Hong Kong, here we initiated a citizen science project involving university, non-governmental organisations and secondary school students and teachers. It is envisioned that the citizen science approach used in this study could be used as a demonstration to future biodiversity sampling and monitoring studies. Throughout a year of monitoring and species sampling across different localities in Hong Kong, 150 soil macrofaunal morphospecies were collected. Eighty five of them were further identified by morphology and DNA barcoding was assigned to each identified morphospecies, yielding a total of 646 DNA barcodes, with new millipede sequences deposited to the GenBank. The soil macrofauna morphospecies in Hong Kong found in this study are mainly dominated by millipedes (23 out of 150) and oligochaetes (15 out of 150). Amongst the twenty three identified millipedes, two polyxenid millipedes, Monographis queenslandica Huynh & Veenstra, 2013 and Alloproctoides remyi Marquet and Condé, 1950 are first recorded in Hong Kong. Information has been curated on an online platform and database (http://biodiversity.sls.cuhk.edu.hk/millipedes). A postcard summarising the findings of millipedes in Hong Kong has also been made as a souvenir and distributed to citizen participants. The identified macrofauna morphospecies and their 646 DNA barcodes in this study established a solid foundation for further research in soil biodiversity.