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Sakuta, K.

Publications and source records attributed to Sakuta, K..

2 recordsLinked to original sources

Afadin-deficient retinas exhibit severe neuronal lamination defects but preserve visual functions

Neural lamination is a common feature of the central nervous system (CNS), with several subcellular structures, such as adherens junctions (AJs), playing a role in this process. The retina is also heavily laminated, but it remains unclear how laminar formation impacts retinal cell morphology, synapse integrity, and overall retinal function. In this study, we demonstrate that the loss of afadin, a key component of AJs, in mice leads to significant pathological changes. These include the disruption of outer retinal lamination and a notable decrease as well as mislocalization of photoreceptors, their outer segments, and photoreceptor synapses. Interestingly, despite these severe impairments, we recorded small local field potentials, including the a- and b-waves. We also classified retinal ganglion cells (RGCs) into ON, ON-OFF, and OFF types based on their firing patterns in response to light stimuli. Additionally, we successfully characterized the receptive fields of certain RGCs. Overall, these findings provide evidence that retinal circuit function can be partially preserved even when there are significant disruptions in both retinal lamination and photoreceptor synapses. Our results indicate that retinas with severely altered morphology still retain some capacity to process light stimuli.

neuroscience↗

Novel endornaviruses infecting Phytophthora cactorum that attenuate vegetative growth, promote sporangia formation, and confer hypervirulence to the host oomycete.

Two novel endornaviruses were found in Phytophthora cactorum isolated from severe black lesions on Boehmeria nivea (B. nivea) var. nipononivea plants in a Japanese forest. These two endornaviruses were named Phytophthora cactorum alphaendornavirus 4 (PcAEV4) and Phytophthora cactorum alphaendornavirus 5 (PcAEV5), and have site-specific nick structures in their positive RNA strands, which are hallmarks of alphaendornaviruses. Ribavirin and cycloheximide treatment of the protoplasts effectively cured the host oomycete (Kara1) of the viruses. The resultant virus-free strain (Kara1-C) displayed luxuriant mycelial growth with less zoosporangia formation as compared to the Kara1 strain. Remarkably, the Kara1-C strain exhibited reduced ability to form black lesions on B. nivea leaves, suggesting that presence of PcAEV4 and PcAEV5 in the Kara1 strain led to enhanced virulence in host plants. Under osmotic pressure and cell wall synthesis inhibition, the Kara1 strain exhibited less growth inhibition compared with the Kara1-C strain. In contrast, the Kara1 strain showed more growth inhibition to membrane-permeable surfactant compared with the Kara1-C strain, indicating that these endornaviruses can alter the susceptibility of the host oomycete to abiotic stresses. Co-localization and cell fractionation analyses showed that PcAEV4 and PcAEV5 localized to intracellular membranes, particularly the ER membrane fraction. Further, infection with these 2 endornaviruses was found to affect the hosts response to exogenous sterols, which enhanced vegetative growth and zoosporangia formation, as well as virulence of the host oomycete. These results provide deep insights into the effects of endornavirus infection in the Phytophthora spp. and also highlight protoplast-based methods in advancing Phytophthora virus studies.

microbiology↗