Biology subjects

Kamiyama, T.

Publications and source records attributed to Kamiyama, T..

4 recordsLinked to original sources

bioRxiv2025

EC-isHCR: a rapid method for in situ hybridization chain reaction in diverse animal samples

The in situ hybridization chain reaction (isHCR) visualizes RNA across multiple spatial scales, from organs to subcellular structures, in diverse samples. We previously proposed a rapid protocol, EC-isHCR, for Drosophila embryos and ovaries. Whether EC-isHCR retains the features of conventional isHCR, including wide-spatial-scale analyses in various samples, however, has remained unclear. Here, we show that EC-isHCR enables robust RNA detection in a broad range of samples, such as whole-mount fruit fly, parasitoid wasp, and aphid preparations; paraffin sections of trout; frozen mouse sections; and human cultured cells. Moreover, EC-isHCR enabled detection of subcellular RNA localization. EC-isHCR also visualized co-localization of RNA with phase-separated condensates in fruit fly embryos and detected the protrusion-enriched mRNA in HeLa cells. To broaden the applicability of EC-isHCR, we developed an automated probe design tool (https://github.com/ShuntaYorimoto/hcrkit). By combining this tool with EC-isHCR, we provide a fast and versatile framework to visualize mRNAs. This framework will help reduce the barrier to using fast isHCR and thereby facilitate research across diverse areas of the life sciences. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/696653v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1852584org.highwire.dtl.DTLVardef@621682org.highwire.dtl.DTLVardef@1b3bf5corg.highwire.dtl.DTLVardef@1d86841_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- EC-isHCR enables rapid acquisition of high-contrast images. - EC-isHCR preserves features of conventional isHCR, including versatile sample compatibility and high-resolution imaging. - An automated probe design tool was developed for EC-isHCR. - EC-isHCR/probe tool framework will help reduce the barrier to using fast isHCR.

bioengineering↗

bioRxiv2024

Stress-induced organismal death is genetically regulated by the mTOR-Zeste-Phae1 axis

All organisms are exposed to various stressors, which can sometimes lead to organismal death, depending on their intensity. While stress-induced organismal death has been observed in many species, the underlying mechanisms remain unclear. In this study, we investigated the molecular mechanisms of stress-induced organismal death in the fruit fly Drosophila melanogaster. We identified a chymotrypsin-like serine protease Phaedra1 (Phae1) as a death mediator in D. melanogaster larvae. Phae1 expression was upregulated by lethal heat stress (40 {degrees}C) but not non-lethal heat stress (38 {degrees}C or lower). The most prominent induction of Phae1 occurred in the central nervous system (CNS). We found neuro-specific knockdown of Phae1 increased survival and reduced neuronal caspase activity following exposure to lethal heat stress, suggesting that the transcriptional upregulation of Phae1 in the CNS is essential for stress-induced organismal death. We next found via bioinformatic and biochemical analyses that the transcription factor Zeste (Z) bound the Phae1 enhancer region and that z loss-of-function impaired Phae1 induction in the CNS, increasing survival following lethal heat stress. In addition, we found via chemical screening that rapamycin, a chemical inhibitor of mechanistic target of rapamycin (mTOR), suppressed Phae1 expression. Neuro-specific knockdown of mTor reduced the protein levels of both Phae1 and Z, leading to an increase in survival following lethal heat stress. Together, these results indicate that heat stress-induced organismal death in D. melanogaster larvae is regulated by a genetically encoded transcriptional signaling pathway involving the mTOR-Z-Phae1 axis.

physiology↗

bioRxiv2024

Parasitoid wasp venoms degrade Drosophila imaginal discs for successful parasitism

Parasitoid wasps, one of the most diverse and species-rich animal taxa on Earth, produce venoms that manipulate host development and physiology to exploit host resources. However, mechanisms of venom action remain poorly understood. Here, we show that infection of host Drosophila by the endoparasitoid wasp, Asobara japonica, triggers imaginal disc degradation (IDD) by inducing apoptosis, autophagy, and mitotic arrest, leading to impaired host metamorphosis. A multi-omics approach identified two venom proteins of A. japonica necessary for IDD. Knockdown experiments targeting the venom genes revealed that in concert with host immune suppression, IDD is essential for successful parasitism. Our study highlights a venom-mediated hijacking strategy of the parasitoid wasp that allows host larvae to grow, but ultimately kills the hosts.

developmental biology↗

bioRxiv2021

The sugar-responsive enteroendocrine neuropeptide F regulates lipid metabolism through glucagon-like and insulin-like hormones in Drosophila melanogaster

The enteroendocrine cell (EEC)-derived incretins play a pivotal role in regulating the secretion of glucagon and insulins in mammals. Although glucagon-like and insulin-like hormones have been found across animal phyla, incretin-like EEC-derived hormones have not yet been characterised in invertebrates. Here, we show that the midgut-derived hormone, Neuropeptide F (NPF), acts as the sugar-responsive, incretin-like hormone in the fruit fly, Drosophila melanogaster. Secreted NPF is received by NPF receptor in the corpora cardiaca and in insulin-producing cells. NPF-NPFR signalling resulted in the suppression of the glucagon-like hormone production and the enhancement of the insulin-like peptide secretion, eventually promoting lipid anabolism. Similar to the loss of incretin function in mammals, loss of midgut NPF led to significant metabolic dysfunction, accompanied by lipodystrophy, hyperphagia, and hypoglycaemia. These results suggest that enteroendocrine hormones regulate sugar-dependent metabolism through glucagon-like and insulin-like hormones not only in mammals but also in insects.

physiology↗