Hydrothermal vents are chemosynthetically driven ecosystems and one of the most extreme environments on Earth. Vent communities exhibit remarkable taxonomic novelty at the species and supra-species levels, and over 80% of vent species are endemic. Here, we used mitochondrial DNA to identify the biogeographic distribution of Munidopsis lauensis and the heme-binding regions of A1-type COX1 from six species (including M. lauensis) to investigate whether genetic variation in the protein structure affects oxygen-binding ability. We verified the identity of Indian Ocean specimens by comparing sequences from the barcoding gene mitochondrial cytochrome oxidase subunit 1 (COI) with known M. lauensis sequences from the NCBI database. The data show that these are the first recorded specimens of M. lauensis in the Indian Ocean; previously, this species had been reported only in the southwest Pacific. Our findings support the hypothesis that vent fauna in the Pacific and Indian Oceans can interact via active ridges. In the case of the mitochondrial DNA-binding site, the arrangement of heme-binding ligands and type A1 motif of M. lauensis was identical to that in other species. Moreover, our findings suggest that the mechanism of oxygen binding is well conserved among species from terrestrial organisms to hydrothermal extremophiles. Overall, dispersal of the same species to geologically separated hydrothermal vents and conserved heme-binding regions in mitochondrial proteins suggest that hydrothermal species might have evolved from shallow sea organisms and became distributed geographically using a dispersion corridor.

In the crustacean immune system, leucine-rich repeat (LRR) is one of the major structures for recognizing pathogen-associated molecular patterns (PAMPs). LRR domain-containing proteins belong to the LRR family, which is a large group of proteins with more than 6000 genes in the database. They are involved in very diverse physiological functions mainly by interacting with other proteins. In a previous study, the LvLRRm, a transmembrane protein containing only LRR domain, was identified in the white leg shrimp, Litopenaeus vannamei. Its versatile role in performing multiple immunomodulation activities has been reported. However, there is still a lack of research on its efficient function at the protein level. To investigate its interactions with other proteins, we applied a convenient method called ‘Hybrid LRR technique’ to produce a recombinant LvLRRm. The LvLRRm and hagfish’s variable lymphocyte receptors (VLRs) fragments were fused to the conserved LxxLxLxxN motif while retaining the β-strand. In addition, we established interactions between hybrid-proteins and flagellin of Salmonella by performing surface plasmon resonance (SPR) analysis. The designed hybrid proteins showed potential for universal applications without losing protein functions.

Anthropogenic vibrational disturbances in the marine environment can affect benthic organisms, but these effects on marine animals remain poorly understood. To examine whether anthropogenic substrate-borne vibrations induce physiological stress in the white-clawed fiddler crab (Austruca lactea), individuals were exposed to vibrations at 120 Hz and 250 Hz (~100 dB re 1 µm/s²), and physiological indicators were measured. Lactate and ATP concentrations in the leg muscle were measured, and heat shock protein 70 kDa (HSP70) gene expression in the hepatopancreas was analyzed using RT-PCR with newly designed primers. At 120 Hz, ATP and lactate levels in the leg muscle did not differ significantly between the exposure and control groups. However, at 250 Hz, ATP levels were lower and lactate levels were higher in the exposure group compared to the control. HSP70 gene expression in the hepatopancreas did not differ significantly between the exposure and control groups at either frequency, although one individual exposed to 250 Hz exhibited markedly elevated expression, inducing higher expression variability in the exposed group. These results suggest that anthropogenic vibrational pollution may induce physiological stress in A. lactea, and that such physiological indices could serve as biomarkers for assessing vibroacoustic pollution on marine animals.

In the crustacean immune system, leucine-rich repeat (LRR) is one of the major structures for recognizing pathogen-associated molecular patterns (PAMPs). LRR domain-containing proteins belong to the LRR family, which is a large group of proteins with more than 6000 genes in the database. They are involved in very diverse physiological functions, mainly by interacting with other proteins. In a previous study, the LvLRRm, a transmembrane protein containing only LRR domain, was identified in the white leg shrimp, Litopenaeus vannamei. Its versatile role in performing multiple immunomodulation activities has been reported. However, there is still a lack of research on its efficient function at the protein level. To investigate its interactions with other proteins, we applied a convenient method called the ‘Hybrid LRR technique’ to produce a recombinant LvLRRm. The LvLRRm and hagfish’s variable lymphocyte receptors (VLRs) fragments were fused to the conserved LxxLxLxxN motif while retaining the β-strand. In addition, we established interactions between hybrid proteins and the flagellin of Salmonella typhimurium by performing surface plasmon resonance (SPR) analysis. The results of the SPR analysis demonstrated notable affinity for both LvLRRm and hybrid proteins towards Salmonella flagellin. The designed LvLRRm hybrid proteins bring insight for universal applications without losing protein functions.