Biology subjects

Nishikawa, T.

Publications and source records attributed to Nishikawa, T..

4 recordsLinked to original sources

bioRxiv2021

Green spotted puffer can detect an almost nontoxic TTX analog odor using crypt olfactory sensory neurons

Tetrodotoxin (TTX) is a well-known neurotoxin that functions as a defense substance for toxic puffers. Several behavioral studies reported that TTX attracts toxic puffers belonging to the genus Takifugu. Although our electrophysiological and behavioral studies showed that a TTX analog, 5,6,11-trideoxyTTX, acts as an olfactory chemoattractant for grass puffers (T. alboplumbeus), it is unclear whether toxic puffers are commonly attracted to 5,6,11-trideoxyTTX, and which types of olfactory sensory neurons (OSNs) detect 5,6,11-trideoxyTTX. Here we investigated whether the green spotted puffer (Dichotomyctere nigroviridis), a phylogenetically different species from the grass puffer, is attracted to 5,6,11-trideoxyTTX. Administration of 5,6,11-trideoxyTTX attracted green spotted puffers, but TTX or vehicle did not. Furthermore, immunohistochemistry of the olfactory epithelium exposed to 5,6,11-trideoxyTTX with an antibody against phosphorylated ribosomal protein S6 (pS6), a neuronal activity marker, labeled oval cells with apical invagination. These oval cells were also labeled by the antibody against S100, a specific marker of crypt OSNs. Thus, our results suggest that 5,6,11-trideoxyTTX acts as an olfactory chemoattractant that is detected by crypt-type OSNs in the olfactory epithelium of green spotted puffers. Toxic puffers may use 5,6,11-trideoxyTTX as an olfactory chemoattractant involved in reproduction and parental care or as an olfactory cue of TTX-bearing organisms for effective toxification. Summary statementBehavioral and immunohistochemical experiments suggest that an almost nontoxic TTX analog, 5,6,11-trideoxyTTX, acts as an olfactory chemoattractant for green spotted puffers, and crypt-type olfactory sensory neurons detect it.

zoology↗

bioRxiv2021

Almost nontoxic tetrodotoxin analog, 5,6,11-trideoxytetrodotoxin, as an olfactory chemoattractant for the grass puffer

Toxic puffers contain the potent neurotoxin, tetrodotoxin (TTX). Although TTX is considered to serve as a defense substance, previous behavioral studies have demonstrated that TTX acts as an attractive pheromone for some toxic puffers. To elucidate the physiological mechanism of putative pheromonal action of TTX, we examined whether grass puffers Takifugu alboplumbeus can detect TTX. Electroolfactogram (EOG) results suggest that the olfactory epithelium (OE) of grass puffers responded to a type of TTX analog (5,6,11-trideoxyTTX), although it did not respond to TTX. We also examined the attractive action of 5,6,11-trideoxyTTX on grass puffers by recording their swimming behavior under dark conditions. Grass puffers preferred to stay on the side of the aquarium where 5,6,11-trideoxyTTX was administered, and their swimming speed decreased. Additionally, odorant-induced labeling of olfactory sensory neurons by immunohistochemistry against neural activity marker (phosphorylated extracellular signal regulated kinase; pERK) revealed that labeled olfactory sensory neurons were localized in the region surrounding "islets" where there was considered as nonsensory epithelium. 5,6,11-trideoxyTTX has been known to accumulate in grass puffers, but its toxicity is much lower (almost nontoxic) than TTX. Our results suggest that toxic puffers may positively use this TTX analog, which has been present in their body with TTX but whose function was unknown, as an odorant for chemical communication or effective TTX accumulation.

zoology↗

bioRxiv2021

Reciprocal differentiation via GABAergic components and ASD-related phenotypes in hES with 1q21.1 CNV

Copy number variations (CNVs) in the distal 1q21.1 region, both deletion (1q del) and duplication (1q dup), are associated with autism spectrum disorder, epilepsy and schizophrenia. Besides common phenotypes, 1q del and 1q dup manifest opposite clinical phenotypes--e.g., microcephaly in 1q del and macrocephaly in 1q dup. However, molecular and cellular mechanisms are still elusive. We generate isogenic human ES (hES) cell lines with reciprocal 1q21.1 CNVs using CRISPR/Cas9 system and differentiate them into 2-dimensional (2-D) neurons and 3-D cortical organoids. Our study recapitulates opposite organoid size and shows dosage-dependent differentiation changes i.e., more mature and GABAergic components in 1q del and more proliferative state in 1q dup. In contrast, both CNVs show hyperexcitability and altered expressions of glutamate system as common features. These results demonstrate that 1q21.1 CNVs dramatically affect cell fate in the early neurodevelopmental periods. This is the first isogenic model of hES CNVs and our findings provide new insights into the underlying mechanisms of neurodevelopmental disorders.

genomics↗

bioRxiv2021

Anti-CoVid19 plasmid DNA vaccine induces a potent immune response in rodents by Pyro-drive Jet Injector intradermal inoculation

There is an urgent need to limit and stop the worldwide coronavirus disease 2019 (COVID-19) pandemic via quick development of efficient and safe vaccination methods. Plasmid DNA vaccines are one of the most remarkable vaccines that can be developed in a short term. pVAX1-SARS-CoV2-co, which is a plasmid DNA vaccine, was designed to express severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein. The produced antibodies lead to Immunoreactions against S protein, anti-receptor-binding-domain, and neutralizing action of pVAX1-SARS-CoV2-co, as confirmed in a previous study. To promote the efficacy of the pVAX1-SARS-CoV2-co vaccine, a pyro-drive jet injector (PJI) was employed. PJI is an injection device that can adjust the injection pressure depending on various target tissues. Intradermally-adjusted PJI demonstrated that pVAX1-SARS-CoV2-co vaccine injection caused a strong production of anti-S protein antibodies, triggered immunoreactions and neutralizing actions against SARS-CoV-2. Moreover, a high dose of pVAX1-SARS-CoV2-co intradermal injection via PJI did not cause any serious disorders in the rat model. Finally, virus infection challenge in mice, confirmed that intradermally immunized (via PJI) mice were potently protected from COVID-19 infection. Thus, pVAX1-SARS-CoV2-co intradermal injection via PJI is a safe and promising vaccination method to overcome the COVID-19 pandemic.

immunology↗