Biology subjects

Tsuchida, T.

Publications and source records attributed to Tsuchida, T..

4 recordsLinked to original sources

bioRxiv2024

Parasitic-plant parasite utilizes flowering pathways at unconventional stages to form stem-derived galls

Galls induced by various organisms exhibit diverse morphological and physiological characteristics, involving complex plant-insect interactions. Most transcriptome analyses to date have focused on leaf-derived galls. To better understand gall formation mechanisms, we investigated stem-derived galls induced by the weevil Smicronyx madaranus on the parasitic plant Cuscuta campestris at gene expression, cellular, and physiological levels. RNA-seq across four developmental stages identified differentially expressed genes and associated gene ontology terms. Consistent with histological observations, genes related to cell division and the cell cycle were upregulated early but decreased as the gall matured. Similar to leaf-derived galls, we found high expression of PLETHORA and meristem-related homeobox genes in early gall development, suggesting that stem cell induction and maintenance are involved in various gall types. Like leaf- derived galls, the expression of genes related to floral organ development increased through the gall development. However, their expression patterns were dramatically different: downstream genes in the flowering pathway were highly expressed at the initial gall stage, whereas upstream genes were highly expressed later. This suggests that the weevil might activate the flowering pathway at unconventional stages, potentially rerouting the typical flowering cascade to influence gall development. Unlike the decrease in photosynthesis-related genes in leaf-derived galls, we observed an increase in these genes in galls formed on the stem of the holoparasitic plant. Shading experiments confirmed that photosynthesis is crucial for both gall growth and the weevil. This study highlights how gall-inducers can co-opt host resources and genetic pathways, offering new insights into the complexity of plant-insect interactions.

plant biology↗

bioRxiv2024

The first example of extreme and independent host plant shifts mediated by parasitic plants in insects

Phytophagous insects have specialized on virtually every plant lineage. Parasitic plants, however, are uncommon hosts. Among insects, only a single lineage of weevils, the Smicronychini, has successfully radiated on both parasitic and non-parasitic plants in a large panel of distantly related Asterid families. This unusual pattern suggests that major host plant shifts have occurred over the course of their diversification. Through the analysis of a phylogenomic dataset, we reconstruct for the first time their evolutionary history and ancestral host plant associations. Our results show that independent host plant shifts occurred both from parasitic to non-parasitic hosts and between distinct parasitic lineages. These results suggest that host shift mechanisms can be driven by ecological opportunities provided by plant-plant interactions. This first evidence of extreme insect host plant shifts apparently mediated by parasitic plant-plant interactions emphasizes the core importance of ecological interactions as driving forces behind insect host plant shifts.

evolutionary biology↗

bioRxiv2023

Hepatic stellate cells maintain liver homeostasis through paracrine neurotrophin-3 signaling

Organ homeostasis is maintained by regulated proliferation of distinct cell populations. In mouse liver, cyclin D1-positive hepatocytes in the midlobular zone repopulate the parenchyma at a constant rate to preserve liver homeostasis. The mitogenic cues that underlie this process are unknown. Hepatic stellate cells, the livers pericytes, are in close proximity to hepatocytes and have been implicated in supporting hepatocyte proliferation, but their role in liver homeostasis is unknown. Here, we employ a T cell-mediated hepatic stellate cell ablation model to remove nearly all hepatic stellate cells in the murine liver, enabling the unbiased characterization of hepatic stellate cell functions. In the normal murine liver, complete loss of hepatic stellate cells persists for up to 6 weeks and reduces liver mass. Our results show that hepatic stellate cells induce cyclin D1 in midlobular hepatocytes by release of neurotrophin-3 to promote hepatocyte proliferation via tropomyosin receptor kinase B signaling. These findings establish that hepatic stellate cells form the niche for midlobular hepatocytes and reveal a novel hepatocyte growth factor signaling pathway. One-Sentence SummaryHepatic stellate cells provide mitogenic cues for midlobular hepatocyte proliferation and metabolic zonation by secreting neurotrophin-3.

cell biology↗

bioRxiv2021

Purification of immunostimulatory glucose homopolymer from broccoli (Brassica oleracea var. italica)

We prepared broccoli (Brassica oleracea var. italica) neutral polysaccharides (flow-through fractions of anion exchange column chromatography from hot water extracts) from different broccoli cultivars and compared their immunostimulatory effects in the silkworm muscle contraction assay. The cultivars showed a wide range of activity, with the cultivar Winter dome showing the highest specific activity (more than 100 times higher than curdlan). Furthermore, the active substance was purified by gel filtration column chromatography. The active substance showed heterogeneous molecular weights of more than 270 kDa. Sugar composition analysis of the purified fraction revealed that more than 95% of its sugar component was glucose, suggesting that the immunostimulatory neutral polysaccharide from broccoli cultivar Winter dome was a homopolymer of glucose. The purified fraction also induced TNF production in cultured mouse macrophage cells. These results suggest that the glucose homopolymer in broccoli has an immunostimulatory effect on both arthropod and mammalian immune system.

biochemistry↗