SENSITIVE TO FREEZING2 is crucial for growth of Marchantia polymorpha under acidic conditions.

Land plants have evolved many systems to adapt to a wide range of environmental stresses. In seed plants, oligogalactolipid synthesis is involved in tolerance to freezing and dehydration, but it has not been analyzed in non-vascular plants. Here we analyzed trigalactosyldiacylglycerol (TGDG) synthesis in Marchantia polymorpha. TGDG is synthesized by galactolipid: galactolipid galactosyltransferase [GGGT; SENSITIVE TO FREEZING2 (SFR2) in Arabidopsis]. We analyzed the subcellular localization and GGGT activity of two M. polymorpha SFR2 homologs (MpGGGT1 and MpGGGT2, each as a GFP-fusion protein) using a transient expression system in Nicotiana benthamiana leaves and found that MpGGGT1-GFP localized in the chloroplast envelope membrane. We produced mutants Mpgggt1 and Mpgggt2 and found that TGDG did not accumulate in Mpgggt1 upon treatment of the thallus with acetic acid. Moreover, growth of Mpgggt1 mutants was impaired by acetic acid treatment. Microscopy revealed that the acetic acid treatment of M. polymorpha plants damaged intracellular membranes. The fact that the effect was similar for wild-type and Mpgggt1 plants suggested that MpGGGT has a role in recovery from damage. These results indicate that MpGGGT plays a crucial role in M. polymorpha growth under conditions of acid stress, which may have been encountered during the ancient terrestrial colonization of plants.

Nonlinear age-related differences in probabilistic learning in mice: A 5-armed bandit task study.

This study explores the impact of aging on reinforcement learning in mice, focusing on changes in learning rates and behavioral strategies. A 5-armed bandit task (5-ABT) and a computational Q-learning model were used to evaluate the positive and negative learning rates and the inverse temperature across three age groups (3, 12, and 18 months). Results showed a significant decline in the negative learning rate of 18-month-old mice, which was not observed for the positive learning rate. This suggests that older mice maintain the ability to learn from successful experiences while decreasing the ability to learn from negative outcomes. We also observed a significant age-dependent variation in inverse temperature, reflecting a shift in action selection policy. Middle-aged mice (12 months) exhibited higher inverse temperature, indicating a higher reliance on previous rewarding experiences and reduced exploratory behaviors, when compared to both younger and older mice. This study provides new insights into aging research by demonstrating that there are age-related differences in specific components of reinforcement learning, which exhibit a non-linear pattern.

Monitoring sodium caseinate and whey protein isolate interaction with mild preheat treatment using ultrasound spectroscopy and confocal laser scanning microscopy.

Ultrasound spectroscopy and confocal laser scanning microscopy (CLSM) methods were developed to visualize the interaction between sodium caseinate (SC) and whey protein isolate (WPI) with a mild preheat treatment (57°C, 10 min) followed by adding glucono-δ-lactone (GDL). Ultrasonic velocity changes during incubation at 25°C after adding GDL for four kinds of mixtures (no-treated SC plus no-treated WPI, preheated SC plus no-treated WPI, no-treated SC plus preheated WPI and preheated SC plus preheated WPI) were monitored. The results reveal that the mild preheating treatment of the proteins affected the timing of the increase in compressibility of each system. CLSM observation with individualized dyes which have different maxima of excitation and emission wavelengths, showed the preheated SC plus no-treated WPI mixture had a slightly coarse structure and the highest correlation coefficient, suggesting the highest colocalization of the SC and WPI among the four kinds of mixed-protein systems. Furthermore, the scanning electron microscopy (SEM) observation suggests that there are some differences among the gels, namely, preheated WPI leads to the formation of developed three-dimensional gel networks with filamentous structures, whereas SC promotes the formation of cluster-like crowded networks composed of more fine aggregated particles instead of developed filamentous structures. These results demonstrated that although SC is known as a heat-stable protein, pretreated SC could lead to an increase of the collaboration with WPI in the presence of GDL. This finding anticipated the possibility creating a food material with another texture using a milk-protein mixed system.

BK channel dysfunction disrupts attention-controlled behaviors and altered perseverative responses in murine instrumental learning.

This study examined the effect of knockout of KCNMA1 gene, coding for the BK channel, on cognitive and attentional functions in mice, with an aim to better understand its implications for human neurodevelopmental disorders. The study used the 3-choice serial reaction time task (3-CSRTT) to assess the learning performance, attentional abilities, and repetitive behaviors in mice lacking the KCNMA1 gene (KCNMA1-/-) compared to wild-type (WT) controls. Results showed no significant differences in learning accuracy between the two groups. However, KCNMA1-/- mice were more prone to omitting responses to stimuli. In addition, when the timing of cue presentation was randomized, the KCNMA1-/- showed premature responses. Notably, these mice also demonstrated a marked reduction in perseverative responses, which include repeated nose-poke behaviors following decisions. These findings highlight the involvement of the KCNMA1 gene in managing attention, impulsivity, and potentially moderating repetitive actions.

Tardiphaga alba sp. nov., a heavy-metal-tolerant bacterium isolated from garden soil.

A previously undescribed, heavy-metal-tolerant, motile, Gram-negative bacterium, designated strain SK50-23T, was characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SK50-23T was closely related to Tardiphaga robiniae LMG 26467T and the non-phototrophic 'Rhodopseudomonas boonkerdii' NS23T (98.1 and 97.3 % 16S rRNA gene sequence similarity, respectively). Strain SK50-23T possessed a circular genome of 5.86 Mb, with a DNA G+C content of 61.9 mol%. Digital DNA-DNA hybridization showed 20.8-21.6 % similarity between strain SK50-23T and related species. In addition, the whole-genome average nucleotide identity values between strain SK50-23T and related species ranged from 75.1 to 83.5 %. The major cellular fatty acid identified in strain SK50-23T was C18 : 1ω7c, and the main isoprenoid quinone present was ubiquinone Q-10. Strain SK50-23T could be assigned to the genus Tardiphaga with the species name Tardiphaga alba sp. nov. based on morphological, chemotaxonomic and genome-based taxonomic characteristics, and 16S rRNA gene-based phylogenetic characteristics. The type strain of the proposed novel species is SK50-23T (=NBRC 108825T=CGMCC No. 1.12037T).

An ABCB transporter regulates anisotropic cell expansion via cuticle deposition in the moss Physcomitrium patens.

Anisotropic cell expansion is crucial for the morphogenesis of land plants, as cell migration is restricted by the rigid cell wall. The anisotropy of cell expansion is regulated by mechanisms acting on the deposition or modification of cell wall polysaccharides. Besides the polysaccharide components in the cell wall, a layer of hydrophobic cuticle covers the outer cell wall and is subjected to tensile stress that mechanically restricts cell expansion. However, the molecular machinery that deposits cuticle materials in the appropriate spatiotemporal manner to accommodate cell and tissue expansion remains elusive. Here, we report that PpABCB14, an ATP-binding cassette transporter in the moss Physcomitrium patens, regulates the anisotropy of cell expansion. PpABCB14 localized to expanding regions of leaf cells. Deletion of PpABCB14 resulted in impaired anisotropic cell expansion. Unexpectedly, the cuticle proper was reduced in the mutants, and the cuticular lipid components decreased. Moreover, induced PpABCB14 expression resulted in deformed leaf cells with increased cuticle lipid accumulation on the cell surface. Taken together, PpABCB14 regulates the anisotropy of cell expansion via cuticle deposition, revealing a regulatory mechanism for cell expansion in addition to the mechanisms acting on cell wall polysaccharides.

Trigeminal Sensitization in a Closed Head Model for Mild Traumatic Brain Injury.

Mild traumatic brain injury (mTBI) is often accompanied by neurological and ocular symptoms that involve trigeminal nerve pathways. Laser-induced shock wave (LISW) was applied to the skull of male rats as a model for mTBI, while behavioral and neural recording methods were used to assess trigeminal function. The LISW caused greater eye wiping behavior to ocular instillation of hypertonic saline (Sham = 4.83 ± 0.65 wipes/5 min, LISW = 12.71 ± 1.89 wipes/5 min, p < 0.01) and a marked reduction in the time spent in bright light consistent with enhanced periocular and intraocular hypersensitivity, respectively (Sham = 16.3 ± 5.6 s, LISW = 115.5 ± 27.3 s, p < 0.01). To address the early neural mechanisms of mTBI, single trigeminal brainstem neurons, identified by activation to corneal or dural mechanical stimulation, were recorded in trigeminal subnucleus interpolaris/caudalis (Vi/Vc) and trigeminal subnucleus caudalis/upper cervical cord (Vc/C1) regions. The LISW caused marked sensitization to hypertonic saline and to exposure to bright light in neurons of both regions (p < 0.05). Laser speckle imaging revealed an increase in meningeal arterial blood flow to bright light after LISW (Sham = 4.7 ± 2.0 s, LISW = 469.0 ± 37.9 s, p < 0.001). Local inhibition of synaptic activity at Vi/Vc, but not at Vc/C1, by microinjection of CoCl2, prevented light-evoked increases in meningeal blood flow in LISW-treated rats. By contrast, topical meningeal application of phenylephrine significantly reduced light-evoked responses of Vi/Vc and Vc/C1 neurons. These data suggested that neurons in both regions became sensitized after LISW and were responsive to changes in meningeal blood flow. Neurons at the Vi/Vc transition and at Vc/C1, however, likely serve different roles in mediating the neurovascular and sensory aspects of mTBI.

Young's double-slit experiment with undulator vortex radiation in the photon-counting regime.

Young's double-slit interference experiments with undulator vortex radiation were conducted, focusing on photon-counting regime. To isolate the second harmonic radiation in the ultraviolet range emitted from the helical undulator and achieve successful counting measurements, an ultranarrow bandpass filter was utilized under an extremely low-current mode of the electron storage ring. It was observed that the photon spots on the detector, after passing through the double slits, appeared to be randomly distributed. However, upon integrating these photon spots, it was confirmed that interference fringes with characteristic features of optical vortices, such as dark and broken/distorted stripes in the center, were formed. The reproducibility of these interference fringes was confirmed by calculating the optical path difference for the optical vortex reaching the double slits, as well as the optical path difference resulting from normal double-slit interference. Consequently, these findings indicate that even in the state of a single photon, the radiation emitted spontaneously by a high-energy electron in spiral motion possesses the nature of an optical vortex, characterized by a spiral wavefront.

Detection and isolation of a new member of Burkholderiaceae-related endofungal bacteria from Saksenaea boninensis sp. nov., a new thermotolerant fungus in Mucorales.

Thermotolerance in Mucorales (Mucoromycotina) is one of the factors to be opportunistic pathogens, causing mucormycosis. Among thermotolerant mucoralean fungi, Burkholderiaceae-related endobacteria (BRE) are rarely found and the known range of hosts is limited to Rhizopus spp. The phylogenetic divergence of BRE has recently expanded in other fungal groups such as Mortierellaceae spp. (Mortierellomycotina); however, it remains unexplored in Mucorales. Here, we found a thermotolerant mucoralean fungus obtained from a litter sample collected from Haha-jima Island in the Ogasawara (Bonin) Islands, Japan. The fungus was morphologically, phylogenetically, and physiologically characterized and proposed as a new species, Saksenaea boninensis sp. nov. Besides the fungal taxonomy, we also found the presence of BRE in isolates of this species by diagnostic PCR amplification of the 16S rRNA gene from mycelia, fluorescence microscopic observations, and isolation of the bacterium in pure culture. Phylogenetic analysis of the 16S rRNA gene of BRE revealed that it is distinct from all known BRE. The discovery of a culturable BRE lineage in the genus Saksenaea will add new insight into the evolutional origin of mucoralean fungus-BRE associations and emphasize the need to pay more attention to endofungal bacteria potentially associated with isolates of thermotolerant mucoralean fungi causing mucormycosis.

Phosphatidic acid phosphohydrolase modulates glycerolipid synthesis in Marchantia polymorpha and is crucial for growth under both nutrient-replete and -deficient conditions.

MAIN CONCLUSION: The phosphatidic acid phosphohydrolase of Marchantia polymorpha modulates plastid glycolipid synthesis through the ER pathway and is essential for normal plant development regardless of nutrient availability. Membrane lipid remodeling is one of the strategies plant cells use to secure inorganic phosphate (Pi) for plant growth, but many aspects of the molecular mechanism and its regulation remain unclear. Here we analyzed membrane lipid remodeling using a non-vascular plant, Marchantia polymorpha. The lipid composition and fatty acid profile during Pi starvation in M. polymorpha revealed a decrease in phospholipids and an increase in both galactolipids and betaine lipids. In Arabidopsis thaliana, phosphatidic acid phosphohydrolase (PAH) is involved in phospholipid degradation and is crucial for tolerance to both Pi and nitrogen starvation. We produced two M. polymorpha PAH (MpPAH) knockout mutants (Mppah-1 and Mppah-2) and found that, unlike Arabidopsis mutants, Mppah impaired plant growth with shorter rhizoids compared with wild-type plants even under nutrient-replete conditions. Mutation of MpPAH did not significantly affect the mole percent of each glycerolipid among total membrane glycerolipids from whole plants under both Pi-replete and Pi-deficient conditions. However, the fatty acid composition of monogalactosyldiacylglycerol indicated that the amount of plastid glycolipids produced through the endoplasmic reticulum pathway was suppressed in Mppah mutants. Phospholipids accumulated in the mutants under N starvation. These results reveal that MpPAH modulates plastid glycolipid synthesis through the endoplasmic reticulum pathway more so than what has been observed for Arabidopsis PAH; moreover, unlike Arabidopsis, MpPAH is crucial for M. polymorpha growth regardless of nutrient availability.