Biology subjects

Chan, B. K. K.

Publications and source records attributed to Chan, B. K. K..

3 recordsLinked to original sources

bioRxiv2026

Northward expansion of the barnacle Fistulobalanus albicostatus in Japan

Fistulobalanus albicostatus Pilsbry, 1916 (Thoracica: Balanidae) is a tropical to temperate species distributed in the NW Pacific. The previously known northernmost record of this species in Japan was from Aomori Prefecture, at the northern end of Honshu Island, Japan. However, field surveys conducted in 2023 and 2026 confirmed the occurrence of F. albicostatus in Hakodate Bay, the southern end of Hokkaido, Japan, across the Tsugaru Strait, thereby extending the northern limit of its known distribution. A line transect survey conducted in May 2026 recorded seven living individuals within an area of 128 m. F. albicostatus was rare on the mid-high shores, accounting for only 2% of all barnacle individuals in a quadrat survey. The basal diameter of the living individuals ranged from 0.76 to 1.23 cm, and all individuals possessed ovaries. Based on characteristics of both morphological and COI gene, the specimens were identified as F. albicostatus, and belonged to the same haplotype of populations that are present in Honshu Island. The establishment of F. albicostatus in Hokkaido suggests an ongoing northward range shift of this warm-water species, with the potential for further expansion under continued ocean warming.

ecology↗

bioRxiv2022

Utilisation of Oxford Nanopore sequencing to generate six complete gastropod mitochondrial genomes as part of a biodiversity curriculum

High-throughput sequencing has enabled genome skimming approaches to produce complete mitochondrial genomes (mitogenomes) for species identification and phylogenomics purposes. In particular, the portable sequencing device from Oxford Nanopore Technologies (ONT) has the potential to facilitate hands-on training from sampling to sequencing and interpretation of mitogenomes. In this study, we present the results from sampling and sequencing six gastropod mitogenomes (Aplysia argus, Cellana orientalis, Cellana toreuma, Conus ebraeus, Conus miles and Tylothais aculeata) from a graduate level biodiversity course. The students were able to produce mitochondrial genomes from sampling to annotation using existing protocols and programs. Approximately 4Gb of sequence was produced from 15 Flongle and two R9.4 Flowcells, averaging 235Mb and N50=4.4kb per Flowcell. Five of the six 14.1-18kb mitogenomes were circlised containing all 13 core protein coding genes. Additional Illumina sequencing reveal that the ONT assemblies were able to span over highly AT rich sequence in the control region that was otherwise missing in Illumina-assembled mitogenomes, but still contained a base error of one every 70.8-346.7bp with the majority occurring at homopolymer regions. Our findings suggest that ONT are portable and can be used to rapidly produce mitogenomes at low cost and tailored to genomics-based training in biodiversity research.

ecology↗

bioRxiv2018

Transcriptional dynamics following freezing stress reveal selection for mechanisms of freeze tolerance at the poleward range margin in the cold water intertidal barnacle Semibalanus balanoides

The ability to survive freezing has repeatedly evolved across multiple phyla. This suggests that the mechanisms of freeze tolerance must be readily evolvable from basal physiological traits. While several biochemical correlates to freeze tolerance have been described, the mechanism that confers freeze tolerance is still not well understood. To understand both the basic biochemical mechanisms of freeze tolerance as well as their role in local adaptation at the poleward range edge, we conducted a transcriptomic study on two populations (one from the poleward range margin in the White Sea, Russia, and one from the central coast of British Columbia, Canada) of the cold water acorn barnacle Semibalanus balanoides on a time series following a freezing event. We found that the British Columbia population (at the equatorward range margin) was significantly less freeze tolerant than the White Sea population (at the poleward range margin). After assembling and annotating a de novo transcriptome for S. balanoides, we found that the patterns of differential transcript expression following freezing were almost entirely non-overlapping between the two populations, with the White Sea population expressing a series of heat shock proteins in response to freezing stress as well as several aquaporins, while the British Columbia population expressed a series of proteases instead, indicating severe protein damage. We found strong evidence of purifying selection on the significantly upregulated transcripts in the White Sea population, suggesting local adaptation to freezing threat. Taken together, this shows the importance of freeze tolerance to population survival at the poleward range margin, and highlights the central roles of aquaporins and heat shock proteins to the trait of freeze tolerance across taxa.

physiology↗