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Biology subjects

Ishiwata, K.

Publications and source records attributed to Ishiwata, K..

2 recordsLinked to original sources

A chromosome-level genome resource for the lethal tapeworm Sparganum proliferum, with candidate genomic safe harbours for functional genetics

Sparganum proliferum is an enigmatic and highly proliferative cestode known for its ability to form invasive larval infections in mammalian hosts. Here, we present the first chromosome-level genome assembly for a member of the order Diphyllobothriidea, generated using a hybrid sequencing approach that integrates Oxford Nanopore/PacBio long-read sequencing, Illumina short-read sequencing, and Hi-C scaffolding. The final genome assembly spanned approximately 681 megabases (Mb) across nine chromosomes. BUSCO analysis revealed 81.9% completeness, whereas repeat annotation identified 55.8% of the genome as repetitive elements. Gene annotation uncovered approximately 29,000 protein-coding genes including [~]6200 transposon associated genes, highlighting the complex genomic landscape underlying parasitic lifestyles. Synteny analysis with other cestode linages including Echinococcus and Hymenolepis provided insights into the structural organisation and evolutionary trajectory of S. proliferum. In addition, we identified candidate genomic safe harbour (GSH) loci and promoters from housekeeping genes, offering potential for stable transgene integration. This high-quality genome serves as a critical resource for studying parasite evolution, host adaptation mechanisms, and the molecular basis of invasive proliferation in cestodes.

genomics↗

Pseudoautosomal gene SHOX exhibits sex-biased random monoallelic expression and contributes to sex difference in height

Adult men are, on average, [~]13 cm taller than adult women. Although previous studies have suggested a significant contribution of sex chromosomal genes to sexual dimorphism in height, all attempts to identify a male-specific growth gene have failed. In the present study, we analyzed transcripts from cartilage tissues, and found that the expression of SHOX, a growth-promoting gene in the pseudoautosomal region on the X and Y chromosomes, was lower in females than in males. DNA methylation analyses showed that SHOX has some characteristics of genes subjected to X chromosome inactivation (XCI). These findings indicate that sex difference in human height is mainly ascribed to incomplete spreading of XCI on a pseudoautosomal gene. More importantly, RT-PCR of fibroblast clones revealed XCI-independent random clonal monoallelic expression of SHOX. We presume that during eutherian evolution, SHOX translocated from an autosome to the proto-sex chromosome without losing the epigenetic memory of random clonal monoallelic expression and subsequently underwent partial XCI. This study provides a novel model of epigenetic gene regulation leading to phenotypic diversity in humans.

genetics↗