Biology subjects

Sezutsu, H.

Publications and source records attributed to Sezutsu, H..

5 recordsLinked to original sources

bioRxiv2025

An ATP-binding cassette subfamily C is crucial for flavonoid sequestration in the domestic silkworm, Bombyx mori

Some herbivorous insects have evolved sequestration mechanisms, the ability to take up and accumulate plant secondary metabolites for their own benefit. The domestic silkworm, Bombyx mori, and its wild ancestor, B. mandarina, take up flavonoids from mulberry leaves and accumulate the molecules as their glucosides in their tissues and cocoon shell. This sequestration enhances the cocoons protective property against ultraviolet or bacterial proliferation. Here, we show that an ATP-binding cassette transporter subfamily C (ABCC) gene, BmABCC4, plays a crucial role in the flavonoid sequestration in the silkworms. BmABCC4 is located at Green c, a cocoon color-associated locus predicted in 1941 and whose detailed position we previously identified. This transporter is expressed in the midgut and silk glands, and the expression is upregulated in the midgut in late period of final instar larva. Knockout of BmABCC4 significantly reduced the total flavonoid content in the tissues and cocoon shell. Our results suggest that BmABCC4 transports flavonoid glucosides from the midgut cells to hemolymph and from the silk gland cells to the silk gland lumen.

genetics↗

bioRxiv2024

Time-course transcriptome data of silk glands in day 0-7 last-instar larvae of Bombyx mori (w1 pnd strain)

Time-course transcriptome expression data were constructed for four parts of the silk gland (anterior, middle, and posterior parts of the middle silk gland, along with the posterior silk gland) in the domestic silkworm, Bombyx mori, from days 0 to 7 of the last-instar larvae. For sample preparation, silk glands were extracted from one female and one male larva every 24 hours accurately after the fourth ecdysis. The reliability of these transcriptome data was confirmed by comparing the transcripts per million (TPM) values of the silk gene and quantitative reverse transcription PCR results. Hierarchical cluster analysis results supported the reliability of transcriptome data. These data are likely to contribute to the progress in molecular biology and genetic research using B. mori, such as elucidating the mechanism underlying the massive production of silk proteins, conducting entomological research using a meta-analysis as a model for lepidopteran insect species, and exploring medical research using B. mori as a model for disease species by utilising transcriptome data.

molecular biology↗

bioRxiv2023

A major endogenous glycosidase mediating quercetin uptake in Bombyx mori

Quercetin is a common plant flavonoid that is involved in herbivore-plant interactions. Mulberry silkworms (domestic silkworm, Bombyx mori, and wild silkworm, Bombyx mandarina) uptake quercetin from mulberry leaves and accumulate the metabolites in the cocoon, thereby improving its protective properties. Here we identified and characterized a glycosidase, named LPH-like quercetin glycoside hydrolase 1 (LQGH1), that initiates quercetin metabolism in the domestic silkworm. LQGH1 is expressed in the midgut where it mediates quercetin uptake by deglycosylating the three most common quercetin glycosides present in mulberry leaf: rutin, quercetin-3-O-malonyl-glucoside, quercetin-3-O-glucoside. Despite being located in an unequal crossing-over hotspot, LQGH1 is conserved in some species in clade Macroheterocera, including the wild silkworm, indicating the adaptive significance of quercetin uptake. LQGH1 is important also in breeding: defective mutations of LQGH1, which result in discoloration of the cocoon and increased silk yield, are homozygously conserved in 27 of the 32 Japanese white-cocoon domestic silkworm strains and 12 of the 30 Chinese ones we investigated.

genetics↗

bioRxiv2022

Highly accurate genome assembly of an improved high-yielding silkworm strain, Nichi01

The silkworm (Bombyx mori) is an important lepidopteran model insect, and an industrial domestic animal traditionally used for silk production. Here, we report the genome assembly of an improved Japanese strain Nichi01, in which the cocoon yield is comparable to that of commercial silkworm strains. The integration of PacBio Sequel II long-read and ddRAD-seq-based high-density genetic linkage map achieved the highest quality genome assembly of silkworms to date; 22 of the 28 pseudomolecules contained telomeric repeats at both ends, and only four gaps were present in the assembly. A total of 452 Mbp of the assembly with an N50 of 16.614 Mbp covered 99.3% of the complete orthologs of the Arthropod core genes. Although the genome sequence of Nichi01 and that of the previously reported low-yielding tropical strain p50T assured their accuracy in most regions, we corrected several regions, misassembled in p50T, in our assembly. A total of 18,397 proteins were predicted using over 95 Gb of mRNA-seq derived from 10 different organs, covering 96.9% of the complete orthologs of the Arthropod core genes. The final assembly and annotation files are available in KAIKObase (https://kaikobase.dna.affrc.go.jp/index.html) along with a genome browser and BLAST searching service, which would facilitate further studies and the breeding of silkworms and other insects.

genomics↗

bioRxiv2019

Reference transcriptome data in silkworm, Bombyx mori

BackgroundThe silkworm Bombyx mori is a lepidopteran model insect with biological and industrial importance. Its high-quality genome sequence has recently become available and the utilization of this information in combination with extensive transcriptomic analyses is expected to provide an elaborate gene model. It will also be possible to clarify gene expression in detail using this approach. ResultsWe herein performed RNA-seq analysis of ten major tissues/subparts of silkworm larvae. Sequences were mapped onto the reference genome assembly and reference transcriptome data was successfully constructed. The reference data provided a nearly complete sequence for sericin-1, a major silk gene with a complex structure. We also markedly improved the gene model for other genes. Transcriptomic expression was investigated in each tissue and a number of transcripts were identified that were exclusively expressed in tissues such as the testis. Transcripts strongly expressed in the midgut formed tight genomic clusters, suggesting that they originated from tandem gene duplication. Transcriptional factor genes expressed in specific tissues or the silk gland subparts were also identified. ConclusionsWe successfully constructed reference transcriptome data in the silkworm and found that a number of transcripts showed unique expression profiles. These results will facilitate basic studies on the silkworm and accelerate its applications, which will contribute to further advances in lepidopteran and entomological research and the practical use of these insects.

genomics↗