The Function of Florigen in the Vegetative-to-Reproductive Phase Transition in and around the Shoot Apical Meristem.

Plants undergo a series of developmental phases throughout their life-cycle, each characterized by specific processes. Three critical features distinguish these phases: the arrangement of primordia (phyllotaxis), the timing of their differentiation (plastochron) and the characteristics of the lateral organs and axillary meristems. Identifying the unique molecular features of each phase, determining the molecular triggers that cause transitions and understanding the molecular mechanisms underlying these transitions are keys to gleaning a complete understanding of plant development. During the vegetative phase, the shoot apical meristem (SAM) facilitates continuous leaf and stem formation, with leaf development as the hallmark. The transition to the reproductive phase induces significant changes in these processes, driven mainly by the protein FT (FLOWERING LOCUS T) in Arabidopsis and proteins encoded by FT orthologs, which are specified as 'florigen'. These proteins are synthesized in leaves and transported to the SAM, and act as the primary flowering signal, although its impact varies among species. Within the SAM, florigen integrates with other signals, culminating in developmental changes. This review explores the central question of how florigen induces developmental phase transition in the SAM. Future research may combine phase transition studies, potentially revealing the florigen-induced developmental phase transition in the SAM.

Whole-Tissue Three-Dimensional Imaging of Rice at Single-Cell Resolution.

The three-dimensional (3D) arrangement of cells in tissues provides an anatomical basis for analyzing physiological and biochemical aspects of plant and animal cellular development and function. In this study, we established a protocol for tissue clearing and 3D imaging in rice. Our protocol is based on three improvements: clearing with iTOMEI (clearing solution suitable for plants), developing microscopic conditions in which the Z step is optimized for 3D reconstruction, and optimizing cell-wall staining. Our protocol successfully 3D imaged rice shoot apical meristems, florets, and root apical meristems at cellular resolution throughout whole tissues. Using fluorescent reporters of auxin signaling in rice root tips, we also revealed the 3D distribution of auxin signaling events that are activated in the columella, quiescent center, and multiple rows of cells in the stele of the root apical meristem. Examination of cells with higher levels of auxin signaling revealed that only the central row of cells was connected to the quiescent center. Our method provides opportunities to observe the 3D arrangement of cells in rice tissues.

WEG1, which encodes a cell wall hydroxyproline-rich glycoprotein, is essential for parental root elongation controlling lateral root formation in rice.

Lateral roots (LRs) determine the overall root system architecture, thus enabling plants to efficiently explore their underground environment for water and nutrients. However, the mechanisms regulating LR development are poorly understood in monocotyledonous plants. We characterized a rice mutant, wavy root elongation growth 1 (weg1), that produced higher number of long and thick LRs (L-type LRs) formed from the curvatures of its wavy parental roots caused by asymmetric cell growth in the elongation zone. Consistent with this phenotype, was the expression of the WEG1 gene, which encodes a putative member of the hydroxyproline-rich glycoprotein family that regulates cell wall extensibility, in the root elongation zone. The asymmetric elongation growth in roots is well known to be regulated by auxin, but we found that the distribution of auxin at the apical region of the mutant and the wild-type roots was symmetric suggesting that the wavy root phenotype in rice is independent of auxin. However, the accumulation of auxin at the convex side of the curvatures, the site of L-type LR formation, suggested that auxin likely induced the formation of L-type LRs. This was supported by the need of a high amount of exogenous auxin to induce the formation of L-type LRs. These results suggest that the MNU-induced weg1 mutated gene regulates the auxin-independent parental root elongation that controls the number of likely auxin-induced L-type LRs, thus reflecting its importance in improving rice root architecture.

Coexistence of periodic limb movements during sleep with restless legs syndrome and its association with hypertension in Japanese patients.

BACKGROUND: Caucasian patients with restless legs syndrome (RLS) frequently exhibit periodic limb movements during sleep (PLMS), which may increase the risk of hypertension. We evaluated the positivity rate of PLMS and factors associated with positivity in Japanese patients with RLS, and tested whether the complications of PLMS are associated with the presence of hypertension. METHODS: We retrospectively investigated polysomnographic data and the presence or absence of hypertension in patients with RLS. Patients with systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg or those taking antihypertensive medication were categorized as the group with hypertension. RESULTS: Among 468 patients, 200 (42.7%) had periodic limb movement index (PLMI) values ≥ 15/h and 108 (23.1%) met the criteria of positivity for hypertension. Multiple logistic regression analysis revealed that only higher age was significantly associated with PLMI values ≥ 15/h. Multiple linear regression analyses of factors associated with an increased PLMI also showed that increased PLMI was significantly correlated with higher age and male sex, but not with the international restless legs scale scores. Multiple logistic regression analysis also revealed that higher age and body mass index, not PLMI values ≥ 15/h, were significantly associated with the presence of hypertension. CONCLUSION: The PLMS-positivity rate may be lower in Japanese patients with RLS than in Caucasian patients, and it increases with age and male sex, but not with the severity of the disorder. Furthermore, PLMS complications were not associated with the risk of hypertension in Japanese patients with RLS.

The prevalence and associated factors of seasonal exacerbation of subjective symptoms in Japanese patients with restless legs syndrome.

OBJECTIVES: To elucidate the prevalence of seasonal exacerbation in patients with restless legs syndrome (RLS) and identify its associated factors. METHODS: We investigated the presence/absence of seasonal exacerbation of RLS by distributing self-administered questionnaires with an interval of three years. Patients who reported having seasonal exacerbation in both surveys were defined as having seasonal exacerbation. RLS severity was determined using the International Restless Legs Syndrome Rating Scale (IRLS). RESULTS: Among 180 patients, 89 reported having seasonal exacerbation in the first survey. Among them, only two reported not having seasonal exacerbation in the second survey; thus, 87 (48.3%) patients were considered to have a seasonal exacerbation. Although many of them (68 out of 87, 78.2%) experienced exacerbation in spring or summer, 19 out of 87 (21.8%) reported that their symptoms worsened in fall or winter. All the patients in this study had mild to moderate degrees of RLS severity according to the IRLS score. Multiple logistic regression analyses revealed that having a family history of RLS (p < 0.05) and moderate RLS (p < 0.001) were significantly associated with the presence of seasonal exacerbation. CONCLUSIONS: This study revealed that approximately half of all RLS patients had seasonal exacerbation of the symptoms and that about 80% of the exacerbation was observed during the spring/summer season. Moreover, seasonal exacerbation is likely to be present even in patients whose symptoms had been improved to moderate severity with pharmacological treatment.

Improvement of obsessive-compulsive disorder after pallidothalamic tractotomy for cervical dystonia.

A 30-year-old woman with tardive dystonia in the cervical region from long-term antipsychotic meds was treated with radiofrequency ablation of the right pallidothalamic tract in the fields of Forel. The patient showed improvement in both cervical dystonia and obsessive-compulsive disorder after the procedure, with 77.4% improvement in cervical dystonia and 86.7% improvement in obsessive-compulsive disorder. Although the treatment site in this case was intended to treat cervical dystonia, the lesion was located in the optimal stimulation network for both obsessive-compulsive disorder and cervical dystonia, suggesting that neuromodulation of this region could potentially treat both simultaneously.

Auxin Distribution in Lateral Root Primordium Development Affects the Size and Lateral Root Diameter of Rice.

Lateral roots (LRs) occupy a large part of the root system and play a central role in plant water and nutrient uptake. Monocot plants, such as rice, produce two types of LRs: the S-type (short and thin) and the L-type (long, thick, and capable of further branching). Because of the ability to produce higher-order branches, the L-type LR formation contributes to efficient root system expansion. Auxin plays a major role in regulating the root system development, but its involvement in developing different types of LRs is largely unknown. Here, we show that auxin distribution is involved in regulating LR diameter. Dynamin-related protein (DRP) genes were isolated as causative genes of the mutants with increased L-type LR number and diameter than wild-type (WT). In the drp mutants, reduced endocytic activity was detected in rice protoplast and LRs with a decreased OsPIN1b-GFP endocytosis in the protoplast. Analysis of auxin distribution using auxin-responsive promoter DR5 revealed the upregulated auxin signaling in L-type LR primordia (LRP) of the WT and the mutants. The application of polar auxin transport inhibitors enhanced the effect of exogenous auxin to increase LR diameter with upregulated auxin signaling in the basal part of LRP. Inducible repression of auxin signaling in the mOsIAA3-GR system suppressed the increase in LR diameter after root tip excision, suggesting a positive role of auxin signaling in LR diameter increase. A positive regulator of LR diameter, OsWOX10, was auxin-inducible and upregulated in the drp mutants more than the WT, and revealed as a potential target of ARF transcriptional activator. Therefore, auxin signaling upregulation in LRP, especially at the basal part, induces OsWOX10 expression, increasing LR diameter.

Improved clearing method contributes to deep imaging of plant organs.

Tissue clearing methods are increasingly essential for the microscopic observation of internal tissues of thick biological organs. We previously developed TOMEI, a clearing method for plant tissues; however, it could not entirely remove chlorophylls nor reduce the fluorescent signal of fluorescent proteins. Here, we developed an improved TOMEI method (iTOMEI) to overcome these limitations. First, a caprylyl sulfobetaine was determined to efficiently remove chlorophylls from Arabidopsis thaliana seedlings without GFP quenching. Next, a weak alkaline solution restored GFP fluorescence, which was mainly lost during fixation, and an iohexol solution with a high refractive index increased sample transparency. These procedures were integrated to form iTOMEI. iTOMEI enables the detection of much brighter fluorescence than previous methods in tissues of A. thaliana, Oryza sativa, and Marchantia polymorpha. Moreover, a mouse brain was also efficiently cleared by the iTOMEI-Brain method within 48 h, and strong fluorescent signals were detected in the cleared brain.

Combined effect of diazepam and polystyrene microplastics on the social behavior of medaka (Oryzias latipes).

The combined effect of microplastics and pharmaceuticals on aquatic organisms is an issue of concern. In this laboratory study, we evaluated the combined effect of polystyrene microplastics (2-µm diameter) and diazepam on the social behavior of medaka (Oryzias latipes) by using the shoaling behavior test with five treatment groups: solvent control, polystyrene microplastics exposure (0.04 mg/L), low-concentration diazepam exposure (0.03 mg/L), high-concentration diazepam exposure (0.3 mg/L), and polystyrene microplastics and low-concentration diazepam co-exposure. After 7 days of exposure, the shoal-leaving behavior of the high-concentration diazepam exposure group (8.9 ± 8.3 counts/medaka) and the co-exposure group (6.8 ± 6.7 counts/medaka) was significantly greater than that in the solvent control group (1.8 ± 2.6 counts/medaka). Even after 5 days of recovery, medaka in the co-exposure group left the shoal more often (7.3 ± 5.0 counts/medaka) than those in the solvent control group (2.6 ± 2.6 counts/medaka), whereas the shoal-leaving behavior in other exposure groups, except for the high-concentration diazepam exposure group, was restored. Our findings show that the combined effects of diazepam and polystyrene microplastics suppressed medaka social behavior, suggesting that the presence of microplastics can enhance the adverse effects of pollutants on the social behavior of aquatic organisms.

Mutation of OUR1/OsbZIP1, which encodes a member of the basic leucine zipper transcription factor family, promotes root development in rice through repressing auxin signaling.

A well-developed root system is essential for efficient water uptake, particularly in drought-prone environments. However, the molecular mechanisms underlying the promotion of root development are poorly understood. We identified and characterized a rice mutant, outstanding rooting1 (our1), which exhibited a well-developed root system. The our1 mutant displayed typical auxin-related phenotypes, including elongated seminal root and defective gravitropism. Seminal root elongation in the our1 mutant was accelerated via the promotion of cell division and elongation. In addition, compared with the wild type, the density of short and thin lateral roots (S-type LRs) was reduced in the our1 mutant, whereas that of long and thick LRs (L-type LRs) was increased. Expression of OUR1, which encodes OsbZIP1, a member of the basic leucine zipper transcription factor family, was observed in the seminal root tip and sites of LR emergence, wherein attenuation of reporter gene expression levels controlled by the auxin response promoter DR5 was also observed in the our1 mutant. Taken together, our results indicate that the our1 gene promotes root development by suppressing auxin signaling, which may be a key factor contributing to an improvement in root architecture.

Transovarial persistence of Babesia ovata DNA in a hard tick, Haemaphysalis longicornis, in a semi-artificial mouse skin membrane feeding system.

Bovine piroplasmosis, a tick-borne protozoan disease, is a major concern for the cattle industry worldwide due to its negative effects on livestock productivity. Toward the development of novel therapeutic and vaccine approaches, tick-parasite experimental models have been established to clarify the development of parasites in the ticks and the transmission of the parasites by ticks. A novel tick-Babesia experimental infection model recently revealed the time course of Babesia ovata migration in its vector Haemaphysalis longicornis, which is a dominant tick species in Japan. However, there has been no research on the transovarial persistence of B. ovata DNA using this experimental infection model. Here we assessed the presence of B. ovata DNA in eggs derived from parthenogenetic H. longicornis female ticks that had engorged after semi-artificial mouse skin membrane feeding of B. ovata-infected bovine red blood cells. The oviposition period of the engorged female ticks was 21-24 days in the semi-artificial feeding. Total egg weight measured daily reached a peak by day 3 in all female ticks. Nested PCR revealed that 3 of 10 female ticks laid B. ovata DNA-positive eggs after the semi-artificial feeding. In addition, B. ovata DNA was detected at the peak of egg weight during oviposition, indicating that B. ovata exist in the eggs laid a few days after the onset of oviposition in the tick. These findings will contribute to the establishment of B. ovata-infected H. longicornis colonies under laboratory conditions.

Self-assembled construction of a sheet-type coordination polymer bearing cationic M2L4 cages: creation of channel-like space for removal of ClO4(-) and NO3(-) from aqueous solutions.

Treatment of CuCl2 with a bis-benzimidazole-type ligand, p-bbiteb, afforded a new 2D coordination polymer bearing cationic Cu2L4 cages on the sheet framework. The regular arrangement of the cages created channel-like space for anions. The compound removed ClO4(-) and NO3(-) from aqueous solutions by exchange with Cl(-) in the channels.

Rice Stomatal Closure Requires Guard Cell Plasma Membrane ATP-Binding Cassette Transporter RCN1/OsABCG5.

Water stress is one of the major environmental stresses that affect agricultural production worldwide. Water loss from plants occurs primarily through stomatal pores. Here, we report that an Oryza sativa half-size ATP-binding cassette (ABC) subfamily G protein, RCN1/OsABCG5, is involved in stomatal closure mediated by phytohormone abscisic acid (ABA) accumulation in guard cells. We found that the GFP-RCN1/OsABCG5-fusion protein was localized at the plasma membrane in guard cells. The percentage of guard cell pairs containing both ABA and GFP-RCN1/OsABCG5 increased after exogenous ABA treatment, whereas they were co-localized in guard cell pairs regardless of whether exogenous ABA was applied. ABA application resulted in a smaller increase in the percentage of guard cell pairs containing ABA in rcn1 mutant (A684P) and RCN1-RNAi than in wild-type plants. Furthermore, polyethylene glycol (drought stress)-inducible ABA accumulation in guard cells did not occur in rcn1 mutants. Stomata closure mediated by exogenous ABA application was strongly reduced in rcn1 mutants. Finally, rcn1 mutant plants had more rapid water loss from detached leaves than the wild-type plants. These results indicate that in response to drought stress, RCN1/OsABCG5 is involved in accumulation of ABA in guard cells, which is indispensable for stomatal closure.