Biology subjects

Sasakura, Y.

Publications and source records attributed to Sasakura, Y..

3 recordsLinked to original sources

bioRxiv2023

Uncovering novel endolysins against methicillin-resistant Staphylococcus aureus using microbial single-cell genome sequencing

Endolysins, peptidoglycan hydrolases derived from bacteriophages (phages), are being developed as a promising alternative to conventional antibiotics. To obtain highly active endolysins, a diverse library of endolysins is vital. We here propose microbial single-cell genome sequencing as an efficient tool to discover dozens of previously unknown endolysins, owing to its culture-independent sequencing method. As a proof-of-concept, we analyzed and recovered endolysin genes within prophage regions of Staphylococcus single-amplified genomes (SAGs) in human skin microbiome samples. We constructed a library of chimeric endolysins by shuffling domains of the natural endolysins and performed high-throughput screening against Staphylococcus aureus. One of the lead endolysins, bbst1027, exhibited desirable antimicrobial properties such as rapid bactericidal activity, no detectable resistance development, and in vivo efficacy. We foresee that this endolysin discovery pipeline is in principle applicable to any bacterial target, and boost the development of novel antimicrobial agents.

microbiology↗

bioRxiv2022

Error-acceptable vertical transmission fostered uncoupled phylogenetic relationships between longicorn beetles and their symbionts

The Coleoptera Cerambycidae (longicorn beetles) use wood under different states (living healthy, freshly snapped, completely rot, etc.) in a species-specific manner for their larval diet. Larvae of some Cerambycidae groups have mycetomes, accessory organs associated with the midgut that harbor fungal symbiont cells. The symbionts are thought to improve nutrient conditions; however, this has yet to be shown experimentally. To deduce the evolutionary history of this symbiosis, we investigated the characteristics of the mycetomes in the larvae of longicorn beetles collected in Japan. Lepturinae, Necydalinae, and Spondylidinae are the only groups that possess mycetomes, and these three groups mycetomes and corresponding fungal cells exhibit different characteristics between the groups. However, the phylogenetic relationship of symbiont yeasts does not coincide with that of the corresponding longicorn beetle species, suggesting they have not co-speciated. The imperfect vertical transmission of symbiont yeasts from female to offspring is a mechanism that could accommodate the host-symbiont phylogenetic incongruence. Some Lepturinae species secondarily lost mycetomes. The loss is associated with their diet choice, suggesting that different conditions between feeding habits could have allowed species to discard this organ. We found that symbiont fungi encapsulated in the mycetomes are dispensable for larval growth if sufficient nutrients are given, suggesting that the role of symbiotic fungi could be compensated by the food larvae take. Aegosoma sinicum is a longicorn beetle classified to the subfamily Prioninae, which does not possess mycetomes. However, this species contains a restricted selection of yeast species in the larval gut, suggesting that the symbiosis between longicorn beetles and yeasts emerged before acquiring the mycetomes.

ecology↗

bioRxiv2021

CatSper mediates the chemotactic behavior and motility of the ascidian sperm

Sperm motility, including chemotactic behavior, is regulated by changes in the intracellular Ca2+ concentration. The cation channel of sperm (CatSper), plays an important role in the regulation of intracellular Ca2+ concentration. In mammals, CatSper is the only Ca2+ channel that functions in the sperm, and the mice that lack the genes for the subunits of CatSper, which make up the pore region of the Ca2+ channel, are infertile due to the inhibition of hyperactivation of the sperm. CatSper is also thought to be involved in chemotaxis in sea urchins. In contrast, in the ascidian, Ciona intestinalis, the sperm-activating and -attracting factor (SAAF) interacts with Ca2+/ATPase, which is a Ca2+-pump. Although the existence of CatSper genes has been reported, it is not clear whether CatSper is the specific Ca2+ channel that functions in the ascidian sperm. Therefore, in this study, we generated Catsper3 knockout (KO) animals that found that they were significantly less motile, with few motile sperms not exhibiting any chemotactic behavior. These results suggest that CatSper plays important roles in the spermatogenesis and basic motility mechanisms of sperms in both ascidians and mammals.

developmental biology↗