Nuclear size changes dynamically during development and has long been observed to correlate with the space surrounding the nucleus, as well as with the volume of the cell. Here we combine an in vitro ...cell-free system of Xenopus laevis egg extract with microfluidic devices to systematically analyze the effect of spatial constraints. The speed of nuclear expansion depended on the available space surrounding the nucleus up to a threshold volume in the nanoliter range, herein referred to as the nuclear domain. Under spatial constraints smaller than this nuclear domain, the size of microtubule-occupied space surrounding the nucleus turned out to be limiting for the accumulation of membranes around the nucleus via the motor protein dynein, therefore determining the speed of nuclear expansion. This mechanism explains how spatial information surrounding the nucleus, such as the positioning of the nucleus inside the cell, can control nuclear expansion.
Display omitted
•The speed of nuclear expansion depends on the available volume around the nucleus•Spatial constraints limit the accumulation of membranes around the nucleus•The amount of accumulated membranes is controlled by microtubules and dynein
Nucleus size is dynamic and correlates with its spatial context. Hara and Merten use a cell-free system and microfluidic devices to show that nuclear expansion speed depends on spatial constraints around the nucleus and that active control of membrane accumulation around the nucleus by microtubules and dynein modulates nuclear growth.
In Arabidopsis, fungal chitin is recognized as a pathogen-associated molecular pattern (PAMP) by the chitin receptor complex containing the lysin-motif (LysM) receptor-like kinases CERK1 and LYK5. ...Upon the perception of chitin, CERK1 phosphorylates the receptor-like cytoplasmic kinase, PBL27, which activates the intracellular mitogen-activated protein kinase (MAPK) cascade. However, the mechanisms by which the CERK1-PBL27 complex is regulated remain largely unknown. We identified ubiquitin ligase PUB12 as a component of the PBL27 complex using co-immunoprecipitation and mass spectrometry. However, PUB12 did not interact directly with PBL27. Instead, the ARM domains of PUB12 and its paralog PUB13 interacted with the intracellular domain of CERK1 in a manner that was dependent on its autophosphorylation, suggesting that the phosphorylation-based auto-activation of CERK1 may be required for its interaction with PUB12. The co-expression of PUB12 in Nicotiana benthamiana reduced the accumulation of CERK1. The pub12 pub13 mutant exhibited enhanced chitin-induced immune responses such as ROS production, MAPK activation, and callose deposition. These results suggest that PUB12 and PUB13 are involved in the negative regulation of the chitin receptor complex, which may contribute to the transient desensitization of chitin-induced responses.
Gram-positive anaerobic (GPA) bacteria inhabit different parts of the human body as commensals but can also cause bacteremia. In this retrospective observational study, we analyzed GPA bacteremia ...pathogens before (2013-2015) and after (2016-2018) the introduction of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Most cases of P. micra bacteremia were identified after 2015, both, at our institute and from the literature review. They were of mostly elderly patients and had comorbid conditions (malignancies and diabetes). In our cases, laryngeal pharynx (7/25, 28%) and gastrointestinal tract (GIT; 6/25, 24%) were identified as the most likely sources of bacteremia; however, the infection source was not identified in 9 cases (36%). P. micra bacteremia were frequently associated with spondylodiscitis (29.6%), oropharyngeal infection (25.9%), intra-abdominal abscess (14.8%), infective endocarditis (11.1%), septic pulmonary emboli (11.1%), and GIT infection (11.1%) in the literature review. Almost all cases were treated successfully with antibiotics and by abscess drainage. The 30-day mortalities were 4 and 3.7% for our cases and the literature cases, respectively. Infection sites of P. micra are predominantly associated with GIT, oropharyngeal, vertebral spine, intra-abdominal region, pulmonary, and heart valves. Patients with P. micra bacteremia could have good prognosis following appropriate treatment.
The eukaryotic cells can change the size of the cell nucleus, including the genomic DNA, depending on the environment surrounding the cell nucleus. How cells can scale the nuclear size by sensing the ...environment has remained an enigma for over a century in the field of cell biology. Here, we found a general scaling rule of nuclear size to cell size among eukaryotes and another new aspect for size scaling to the chromatin status inside the nucleus. In this review, I describe the known mechanisms underlying these size scaling characteristics and discuss putative physiological significances for the size scaling.
We present a rare tumor of adenoid cystic carcinoma, solid-basaloid subtype of the breast. Solid-basaloid adenoid cystic carcinoma may have a worse prognosis than classical adenoid cystic carcinoma. ...A 70-year-old woman presented with a mass in her left breast. Malignancy was suspected on imaging and confirmed via core needle biopsy. Left breast partial mastectomy and sentinel lymph node biopsy were performed. Histologically, the tumor was composed of basaloid cells with hyperchromatic nuclei and frequent mitotic figures, as are small-cell neuroendocrine carcinomas. Immunohistochemical analysis of the tumor cells showed high expression of KIT and CD10 and focal expression of keratin 7. Synaptophysin, chromogranin A, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 were not expressed. This patient should be followed up carefully for distant metastases and recurrences.
The eukaryotic nucleus exhibits remarkable plasticity in size, adjusting dynamically to changes in cellular conditions such as during development and differentiation, and across species. ...Traditionally, the supply of structural constituents to the nuclear envelope has been proposed as the principal determinant of nuclear size. However, recent experimental and theoretical analyses have provided an alternative perspective, which emphasizes the crucial role of physical forces such as osmotic pressure and chromatin repulsion forces in regulating nuclear size. These forces can be modulated by the molecular profiles that traverse the nuclear envelope and assemble in the macromolecular complex. This leads to a new paradigm wherein multiple nuclear macromolecules that are not limited to only the structural constituents of the nuclear envelope, are involved in the control of nuclear size and related functions.
Metal ions are used in various situations in living organisms and as a part of functional materials. Since the excessive intake of metal ions can cause health hazards and environmental pollution, the ...development of new molecules that can monitor metal ion concentrations with high sensitivity and selectivity is strongly desired. DNA can form various structures, and these structures and their properties have been used in a wide range of fields, including materials, sensors, and drugs. Guanine-rich sequences respond to metal ions and form G-quadruplex structures and G-wires, which are the self-assembling macromolecules of G-quadruplex structures. Therefore, guanine-rich DNA can be applied to a metal ion-detection sensor and functional materials. In this study, the IRDAptamer library originally designed based on G-quadruplex structures was used to screen for Mn2+, which is known to induce neurodegenerative diseases. Circular dichroism and fluorescence analysis using Thioflavin T showed that the identified IRDAptamer sequence designated MnG4C1 forms a non-canonical G-quadruplex structure in response to low concentrations of Mn2+. A serum resistance and thermostability analysis revealed that MnG4C1 acquired stability in a Mn2+-dependent manner. A Förster resonance energy transfer (FRET) system using fluorescent molecules attached to the termini of MnG4C1 showed that FRET was effectively induced based on Mn2+-dependent conformational changes, and the limit of detection (LOD) was 0.76 µM for Mn2+. These results suggested that MnG4C1 can be used as a novel DNA-based Mn2+-detecting molecule.
This study aimed to evaluate the nerve regenerative effect and behavior of Schwann cells (SCs) on local administration of autologous platelet‐rich plasma (PRP).
Methods
Twenty‐eight Japanese white ...rabbits were used. A 15‐mm sciatic nerve defect was created on the left limb. The resected nerve was used as a reverse autologous nerve. The rabbits were randomly divided into two groups. In group A (n = 10), only nerve grafting was performed. In group B (n = 18), nerve grafting was performed with local PRP administration. Right limbs were used as control (group C, n = 28). The rabbits in each group were equally divided into two subgroups based on the evaluation period of 4 and 12 weeks after grafting. Electrophysiological evaluation, muscle wet‐weight, histological evaluation, and multiple immunofluorescence staining were performed to investigate the regenerative effect of PRP.
Results
The mean regenerative axon diameter of the graft portion in group B (2.02 ± 0.22‐μm) was significantly larger than that in group A (1.89 ± 0.16‐μm) at 4 weeks. The regenerative axon number at the distal portion showed a greater increase in group B (9017 ± 2224/mm2) than in group A (4955 ± 3117/mm2) at 12 weeks. Electrophysiological evaluation and muscle wet‐weight revealed no significant differences. On immunohistological evaluation, the number of activated SCs increased to a larger extent in group B (188 ± 90/mm2) than in group A (117 ± 51/mm2).
Conclusions
Local PRP administration increases the regenerative axon diameter and the regenerative axon number at the distal portion. PRP accelerates SC proliferation in vivo.
Size of the nucleus, a membrane‐bound organelle for DNA replication and transcription in eukaryotic cells, varies to adapt nuclear functions to the surrounding environment. Nuclear size strongly ...correlates with cytoplasmic size and genomic content. Previous studies using Xenopus laevis have unraveled two modes, cytoplasmic and chromatin‐based mechanisms, for controlling nuclear size. However, owing to limited comparative analyses of the mechanisms among eukaryotic species, the contribution of each mechanism in controlling nuclear size has not been comprehensively elucidated. Here, we compared the relative contribution utilizing a cell‐free reconstruction system from the cytoplasmic extract of unfertilized eggs of Xenopus tropicalis to that of the sister species X. laevis. In this system, interphase nuclei were reconstructed in vitro from sperm chromatin and increased in size throughout the incubation period. Using extracts from X. tropicalis, growth rate of the reconstructed nuclei was decreased by obstructing the effective cytoplasmic space, decreasing DNA quantity, or inhibiting molecules involved in various cytoplasmic mechanisms. Although these features are qualitatively identical to that shown by the extract of X. laevis, the sensitivities of experimental manipulation for each cellular parameter were different between the extracts from two Xenopus species. These quantitative differences implied that the contribution of each mode to expansion of the nuclear envelope is coordinated in a species‐specific manner, which sets the species‐specific nuclear size for in vivo physiological function.
Mechanisms for controlling nuclear size are qualitatively conserved between the two Xenopus species, X. laevis and X. tropicalis. Using a cell‐free reconstructing system from egg cytoplasmic extract, we found that the degrees of the contribution of known two mechanisms differ between the two Xenopus species. Our novel findings certify that the contribution of multiple overlapping mechanisms to interphase nuclear growth should be coordinated to adapt to changes in the surrounding environment.
This study performed three-dimensional (3D) magnetic resonance imaging (MRI)-based statistical shape analysis (SSA) by comparing patellofemoral instability (PFI) and normal femur models, and ...developed a machine learning (ML)-based prediction model. Twenty (19 patients) and 31 MRI scans (30 patients) of femurs with PFI and normal femurs, respectively, were used. Bone and cartilage segmentation of the distal femurs was performed and subsequently converted into 3D reconstructed models. The pointwise distance map showed anterior elevation of the trochlea, particularly at the central floor of the proximal trochlea, in the PFI models compared with the normal models. Principal component analysis examined shape variations in the PFI group, and several principal components exhibited shape variations in the trochlear floor and intercondylar width. Multivariate analysis showed that these shape components were significantly correlated with the PFI/non-PFI distinction after adjusting for age and sex. Our ML-based prediction model for PFI achieved a strong predictive performance with an accuracy of 0.909 ± 0.015, and an area under the curve of 0.939 ± 0.009 when using a support vector machine with a linear kernel. This study demonstrated that 3D MRI-based SSA can realistically visualize statistical results on surface models and may facilitate the understanding of complex shape features.
PDF
