Biology subjects

Miki, T.

Publications and source records attributed to Miki, T..

3 recordsLinked to original sources

bioRxiv2020

Gsx2 is involved in specification of neurons in the inferior olivary nuclei from Ptf1a-expressing neuronal progenitors in zebrafish

Neurons in the inferior olivary nuclei (IO neurons) send climbing fibers to Purkinje cells to elicit functions of the cerebellum. IO neurons and Purkinje cells are derived from neural progenitors expressing the proneural gene ptf1a. In this study, we found that the homeobox gene gsx2 was co-expressed with ptf1a in IO progenitors in zebrafish. Both gsx2 and ptf1a zebrafish mutants showed a strong reduction or loss of IO neurons. The expression of ptf1a was not affected in gsx2 mutants and vice versa. In IO progenitors, the ptf1a mutation increased apoptosis whereas the gsx2 mutation did not, suggesting that ptf1a and gsx2 are independently regulated and have distinct roles. The fibroblast growth factors (Fgf) 3/8a and retinoic acid signals negatively and positively, respectively, regulated gsx2 expression and thereby the development of IO neurons. mafba and hox genes are at least partly involved in the Fgf- and retinoic acid-dependent regulation of IO neuronal development. Our results indicate that gsx2 mediates the rostro-caudal positional signals to specify the identity of IO neurons from ptf1a-expressing neural progenitors. SummaryThe homeobox gene gsx2 mediates rostro-caudal positional signaling to specify the identify of neurons in the inferior olivary nuclei from neural progenitors expressing the proneural gene ptf1a.

developmental biology↗

bioRxiv2020

Intravenous edaravone plus therapeutic hypothermia offers limited neuroprotection in the hypoxic-ischaemic newborn piglet

Therapeutic hypothermia is a standard therapy for neonatal hypoxic-ischaemic encephalopathy. One potential additional therapy is the free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one). To compare the neuroprotective effects of edaravone plus therapeutic hypothermia with those of therapeutic hypothermia alone after a hypoxic-ischaemic insult in the newborn piglet, anaesthetized piglets were subjected to 40 min of hypoxia (3-5% inspired oxygen) and cerebral ischaemia was assessed by cerebral blood volume. Body temperature was maintained at 38.5 {degrees}C in the normothermia group (NT, n = 8) and at 34 {degrees}C (24 h after the insult) in the therapeutic hypothermia (TH, n = 7) and therapeutic hypothermia plus edaravone (3 mg intravenous every 12 h for 3 days after the insult; TH+EV, n = 6) groups under mechanical ventilation. Five days after the insult, the mean (standard deviation) neurological scores were 10.9 (5.7) in the NT group, 17.0 (0.4) in the TH group (p = 0.025 vs. NT) and 15.0 (3.9) in the TH+EV group. The histopathological score of the TH+EV group showed no significant improvement compared with that of the other groups. In conclusion, edaravone plus therapeutic hypothermia had no additive neuroprotective effects after hypoxia-ischaemia in neurological and histopathological assessments.

neuroscience↗

bioRxiv2020

Long-term warming weakens stabilizing effects of biodiversity in aquatic ecosystems

Despite the consensus that warming will affect biodiversity, alter physicochemical environments, and disrupt biological interactions, the relative importance of these key processes and how they interact to determine overall ecosystem function is poorly understood. Here, we analyze long-term (16[~]39 years) time series data from ten aquatic ecosystems and use convergent cross mapping (CCM) to quantify the hidden causal network linking species diversity, ecosystem function, and physicochemical factors. We observe that aquatic ecosystems subject to stronger warming exhibit decreased stability (larger fluctuations in phytoplankton biomass). We further show that this effect can be attributed to a weakening of stabilizing causal pathways between biodiversity, nutrient cycling, and phytoplankton biomass. Thus, rather than thinking in terms of separate factors, a more holistic view, that causally links biodiversity and the other ecosystem components, is required to understand and predict climate impacts on the temporal stability of aquatic ecosystems.

ecology↗