Biology subjects

Aoyama, T.

Publications and source records attributed to Aoyama, T..

4 recordsLinked to original sources

bioRxiv2024

Plant Cleavage Factor I complex is essential for precise cleavage and polyadenylation site determination

Cleavage factor I (CFI) is a four-subunit protein complex of the pre-mRNA 3 end processing machinery in eukaryotes. In Arabidopsis, AtCFI25a, AtCFI25b, AtCFI59, and AtCFI68 have been identified as potential components of AtCFI, in silico. Here, we show that the AtCFI25a, AtCFI59, and AtCFI68 proteins each pulled down all components of the CFI, confirming that these subunits form the plant CFI complex. Furthermore, either AtCFI59 or AtCFI68 was essential for nuclear localization of the smallest subunit, AtCFI25a. Mutants with single loss-of-function for AtCFI59 or AtCFI68 showed no obvious morphological defects compared to wild-type plants, while the double mutant displayed pleiotropic morphological defects, identical to those previously reported for AtCFI25a loss-of-function plants. Moreover, these morphological defects correlated with alterations in the usage of 3 UTR cleavage and polyadenylation sites. atcfi25a, atcfi25a atcfi25b and atcfi59 atcfi68 double mutants showed widespread changes in the choice of cleavage and polyadenylation sites. In most cases, more proximal cleavage and polyadenylation sites were used, leading to shorter 3 UTRs. In particular, genes involved in light intensity, light harvesting, photosynthesis and cold responses showed significant dependence on AtCFI function. Furthermore, transcripts coding for AtCFI subunits showed altered 3 end processing in these mutants, suggesting self-regulation function of AtCFI in plants.

molecular biology↗

bioRxiv2023

Can Colpoda travel across oceans? Salinity tolerance of resting cysts may enable global dispersal of the species.

Protist species are distributed worldwide. The processes that enabled this global distribution are unclear. One possible means is through the oceanic dispersal of freshwater protists, although this has not been investigated in detail to date. Here, the ability of resting cysts to tolerate saline conditions is examined as a possible mechanism that enables the oceanic dispersal of protists. Resting cysts of Colpoda cucullus, a freshwater soil protist, can tolerate saline conditions of at least 3.5% NaCl for more than one week. A transcriptome analysis showed that the relative levels of expression of genes associated with membrane function are increased in resting cysts, indicating that salinity tolerance is associated with reconstruction of the cell membrane. Additionally, the outer layer of the cyst wall, a shell-like ectocyst, includes chitin. This may function as a form of "biological armor" that protects the cell from physical stress during oceanic dispersal. Teaser: Fresh water protists may be dispersed across oceans by formation of resting cysts that can tolerate saline conditions.

zoology↗

bioRxiv2023

Application of fluorescence lifetimes to multi-imaging analysis in plant cells

Multi-imaging analysis has become an indispensable technique to visualize multiple target proteins and intracellular components simultaneously. While current multi-imaging analysis relies on the differences in emission spectra of fluorescent molecules, the use of fluorescence lifetime imaging microscopy (FLIM), which exploits the differences in fluorescence lifetimes of fluorescent proteins, in multi-imaging analysis is quite limited. In this study, we successfully discriminated fluorescent proteins with similar colors but different fluorescence lifetimes in vitro and in planta. We found that four fluorescent proteins with similar emission spectra could be distinguished by FLIM. In addition, we found that FLIM could clearly separate fluorescent proteins if they differ by at least 0.2 ns. In a proof-of-concept experiments for plant live imaging, we transiently expressed fluorescent proteins with different subcellular localization tags in Physcomitrium patens by particle bombardment. Each fluorescent protein exhibited its fluorescence lifetime at the subcellular localization corresponding to the localization tag in P. patens with little or no effect of chlorophyll autofluorescence. Our results demonstrate the effectiveness of FLIM in revealing the spatiotemporal dynamics of a large number of fluorescent proteins in living plant cells.

cell biology↗

bioRxiv2023

Mechanical signalling via membrane tension drives saltatory neuronal migration

Neurons migrate in a saltatory manner by repeating two distinct steps: extension of the leading process and translocation of the cell body. The former step is critical for determining the migratory route in response to extracellular guidance cues. In the latter step, neurons must generate robust forces that translocate the bulky soma against mechanical barriers of the surrounding three-dimensional environment. However, the link between the leading process extension and subsequent somal translocation remains unknown. By using scanning ion conductance microscopy, we show that leading process extension increases plasma membrane tension. The tension elevation activated mechanosensitive ion channels and triggered Ca2+ influx, leading to actomyosin activation at the rear of the cell. Blockade of this signaling pathway disturbed somal translocation, thereby inhibiting neuronal migration in three-dimensional environments. Thus, mechanical signaling through plasma membrane tension and mechano-channels links the leading process extension to somal translocation, allowing rapid and saltatory neuronal migration.

cell biology↗