Biology subjects

Nakayama, R.

Publications and source records attributed to Nakayama, R..

3 recordsLinked to original sources

bioRxiv2022

Indirect CRISPR screening with photoconversion revealed key factors of drug resistance with cell-cell interactions

Comprehensive screenings to clarify indirect cell-cell interactions, such as those in the tumor microenvironment, especially comprehensive assessments of supporting cells effects, are challenging. Therefore, in this study, indirect CRISPR screening for drug resistance with cell-cell interactions was invented. The photoconvertible fluorescent protein Dendra2 was inducted to determine the drug resistance responsible factors of supporting cells with CRISPR screenings. Random mutated supporting cells co-cultured with leukemic cells induced drug resistance with cell- cell interactions. Supporting cells responsible for drug resistance were isolated with green-to-red photoconversion, and 39 candidate genes were identified. Knocking out C9orf89, MAGI2, MLPH, or RHBDD2 in supporting cells reduced the ratio of apoptosis of cancer cells. In addition, the low expression of RHBDD2 in supporting cells, specifically fibroblasts, of clinical pancreatic cancer showed a shortened prognosis, and a negative correlation with CXCL12 was observed. Indirect CRISPR screening was established to isolate the responsible elements of cell-cell interactions. This screening method could reveal new mechanisms in all kinds of cell-cell interactions by revealing live phenotype-inducible cells, and it could be a new platform for discovering new targets of drugs for conventional chemotherapies.

cancer biology↗

bioRxiv2020

Hallucination of moving objects revealed by a dynamic noise background

We show that on a dynamic noise background, the perceived disappearance location of a moving object is shifted in the direction of motion. This "twinkle goes" illusion has little dependence on the luminance- or chromaticity-based confusability of the object with the background, or on the amount of background motion energy in the same direction as the object motion. This suggests that the illusion is enabled by the dynamic noise masking the offset transients that otherwise accompany an objects disappearance. While these results are consistent with an anticipatory process that pre-activates positions ahead of the objects current position, additional findings suggest an alternative account: a continuation of attentional tracking after the object disappears. First, the shift was greatly reduced when attention was divided between two moving objects. Second, the illusion was associated with a prolonging of the perceived duration of the object, by an amount that matched the extent of extrapolation inferred from the effect of speed on the size of the illusion (~50 ms). While the anticipatory extrapolation theory does not predict this, the continuation of attentional tracking theory does. Specifically, we propose that in the absence of offset transients, attentional tracking keeps moving for several tens of milliseconds after the target disappearance, and this causes one to hallucinate a moving object at the position of attention.

neuroscience↗

bioRxiv2019

Attention updates the perceived position of moving objects

The information used by conscious perception may be somewhat different from that which drives certain actions. In support of this notion, recent studies reported that although internal grating motion can accumulate over seconds into a large illusory position shift, this position shift is not reflected in saccade targeting (action). Another possibility however is that rather than saccades and other actions having privileged access to the correct position, the attention shift thought to precede saccades resets the accumulated position shift to zero. Here we found that the accumulation of illusory position shift can be reset by transients near the moving object and also by the observer pressing a button at the time the object is perceived to reach a particular position. This creates a striking impression of the object jumping back to near its actual position. These results suggest that both stimulus-driven attention and attention associated with control of action may update the perceived position of moving objects and mediate the previously reported dissociation between conscious perception and saccades.

neuroscience↗