Biology subjects

Yamamoto, C.

Publications and source records attributed to Yamamoto, C..

3 recordsLinked to original sources

bioRxiv2024

Apusomonad photophobic behavior highlights cytoskeletal responses to blue light in early eukaryotes

Light response is a fundamental characteristic of eukaryotic organisms, both unicellular and multicellular. However, no photoresponse has previously been reported in Apusomonadida, a group of small, free-living biflagellates phylogenetically positioned as a sister group to Opisthokonta (animals, fungi, and their unicellular relatives). Apusomonads are thus crucial for understanding the evolution of opisthokonts. Here, we report for the first time an avoidance response to blue light in the apusomonad Podomonas kaiyoae. This avoidance response is accompanied by an increase in gliding velocity, transient changes in flagellar waveforms, and alterations in cell shape. Dynamic cell contraction is induced by an increase in intracellular free Ca2+ and is inhibited by either a dynein inhibitor or an actin-disrupting drug. These findings suggest that the photophobic behavior of Podomonas kaiyoae relies on cytoskeletal responses mediated by both the dynein/tubulin and myosin/actin systems, which were acquired early in eukaryotic evolution. The dominance of the posterior flagellum in cilia-driven directional changes further supports the phylogenetic placement of apusomonads as a sister group to opisthokonts rather than other eukaryotic lineages.

evolutionary biology↗

bioRxiv2024

Development of a metabolic engineering technology to simultaneously suppress the expression of multiple genes in yeast and application in carotenoid production

In yeast metabolic engineering, there is a need for technologies that simultaneously suppress and regulate the expression of multiple genes and improve the production of target chemicals. In this study, we aimed to develop a novel technology that simultaneously suppresses the expression of multiple genes by combining RNA interference with global metabolic engineering technology (GMES). Furthermore, using {beta}-carotene as the target chemical, we attempted to improve its production by using the technology. First, we developed a technology to suppress the expression of the target genes with various strengths using RNA interference. Using this technology, total carotenoid production was successfully improved by suppressing the expression of a single gene out of 10 candidate genes. Then, using this technology, RNA interference strain targeting 10 candidate genes for simultaneous suppression was constructed. The total carotenoid production of the constructed RNA interference strain was 1.7 times compared with the parental strain. In the constructed strain, the expression of eight out of the 10 candidate genes was suppressed. We developed a novel technology that can simultaneously suppress the expression of multiple genes at various intensities and succeeded in improving carotenoid production in yeast. Because this technology can suppress the expression of any gene, even essential genes, using only gene sequence information, it is considered a useful technology that can suppress the formation of by-products during the production of various target chemicals by yeast.

bioengineering↗

bioRxiv2022

Overexpression profiling reveals cellular requirements in context of genetic backgrounds and environments

Overexpression due to copy number variation, promoter mutation, or aneuploidy is often observed, but its adaptive role is not clearly understood. Using a novel "overexpression profiling" method designated ADOPT, we systematically obtained genes whose overexpression was functionally adaptive (GOFAs) under stress conditions in budding yeast to elucidate the nature of adaptive overexpression. GOFAs obtained under heat, salt, and oxidative stress were unique genes that differed from known stress response genes. GOFAs under salt (NaCl) stress were genes involved in calcium homeostasis, reflecting the calcium deficiency of the medium. GOFAs from different genetic backgrounds and co-overexpressing strains revealed that calcium and potassium requirements in salt stress tolerance differ among strains, which is reflected. Profiling of the knockout collection suggested that the effect of calcium was to prevent mitochondrial outbursts. Mitochondria-enhancing GOFAs were adaptive only when calcium was sufficient and conversely non-adaptive in calcium deficiency, supporting the above hypothesis. Adaptive overexpression, thus, reflects the cellular requirements for maximizing the organisms adaptive capacity within a given environmental and genetic context.

systems biology↗