Ectopic expression of the yeast Mn2+ transporter SMF2 enhances tolerance and resistance to cadmium and arsenic in transgenic Arabidopsis.

Vesicular sequestration is a potential strategy for enhancing plant tolerance to cadmium (Cd) and arsenic (As). In this study, the ectopic overexpression of yeast-derived ScSMF2 in Arabidopsis thaliana was found to enhance the accumulation and tolerance of Cd and As in transgenic plants. ScSMF2 was localized on vacuole membranes and formed puncta structures in plant cells when agro-infiltrated for transient expression. Transgenic Arabidopsis showed less retardation on root elongation and shoot weight and more accumulation of Cd, As (III) and As (V) when cultured on medium containing Cd or As. Overexpression of ScSMF2 promoted accumulation of Cd and arsenic in transgenic Arabidopsis, which were over twice higher than in WT plants when cultured in soil. This study provides insights into the mechanisms involved in the vesicular sequestration of heavy metals in plant and presents a potential strategy for enhancing the phytoremediation capacity of plants toward heavy metals.

Ectopic overexpression of the yeast Mn²⁺ transporter SMF2 in Arabidopsis thaliana substantially boosts the accumulation and tolerance to Cd and As in plants. This augmentation is attributed to the enhanced efficacy of intracellular vesicle sequestration, thereby bolstering the capacity of plants to sequester and detoxify these toxic heavy metals. This investigation introduces a potential approach for cultivating plants with improved phytoremediation capabilities, thereby advancing eco-friendly and sustainable remediation initiatives against heavy metal pollution.

Regenerating and repairing degenerative intervertebral discs by regulating the micro/nano environment of degenerative bony endplates based on low-tension mechanics.

BACKGROUND: Conservative treatment is the recommended first-line treatment for degenerative disc diseases. Traction therapy has historically been one of the most common clinical methods to address this, but the clinical effect remains controversial. METHODS: Forty-two six-month-old male Sprague-Dawley rats were randomly divided into six groups: the model group (Group A, four coccyx vertebrae (Co7-Co10) were fixed with customized external fixators, and the vertebral disc degeneration model was constructed by axial compression of the target segment Co8 - Co9 for 4 weeks), the experimental control group (Group B, after successful modeling, the external fixation device was removed and self-rehabilitation was performed) and four intervention groups (Groups C to F): Groups C and E: Co8 - Co9 vertebrae compressed for 4 weeks followed by two or 4 weeks of high tension traction (HTT), respectively, and Groups D and F: vertebrae compressed for 4 weeks followed by two or 4 weeks of low-tension traction (LTT), respectively. Imaging tests (X-ray and MRI) were performed to assess disc height and T2 signal intensity at each time point. After the experiment, the animals were euthanized, and the caudal vertebrae were collected for analysis of intervertebral disc histopathology, proteoglycan content, and micronanostructure of the annulus fibrosus, nucleus pulposus and bony endplate. RESULTS: Signs of tissue regeneration were apparent in all four intervention groups. After two to 4 weeks of intervention (HTT and LTT), the morphology of pores in the bony endplate, their number, and diameter had recovered significantly compared with those in Group A. The LTT group was superior to the HTT group, and the 4w in situ group was significantly superior to the 2w group. Meanwhile, the histological scores of discs, the mean fibril diameter and modulus of annulus fibrosus were significantly improved compared with the control groups, and the LTT group was superior to HTT group. CONCLUSIONS: Low-tension traction better promotes active reconstruction of bony endplates and improves the elastic modulus and micro/nanostructure of the disc. Thus, it further promotes the regeneration and repair of intervertebral discs.

Structural Tunability on Naphthalimide-Based Dendrimer Gelators via Glaser Coupling Interaction with Tailored Gelation Solvent Polarity and Stimuli-Responsive Properties.

To date, most of the low-molecular-weight gels are found serendipitously, and modification on known gelator structures via organic synthesis is an efficient methodology to prepare gel series. However, a simple, direct, and rational modification method for a known gelator is still a challenge. Herein, we employ Glaser coupling reaction to synthesize a novel dendrimer gelator BisDEC with the (ALS2)2 structure, starting from terminal alkyne-based gelator DEC with the ALS2 structure. This structural change results in gels with distinct gelation solvents, mechanical properties, and stimuli-responsive abilities. The gelation abilities of DEC and BisDEC in nonpolar and polar solvents, respectively, have been examined and discussed by several experiments and Hansen constants. It is also shown that the BisDEC gel system shows intriguing self-healing, self-supporting, and grinding chromism properties.

Structure and mechanical properties of high-weight-bearing and low-weight-bearing areas of hip cartilage at the micro- and nano-levels.

BACKGROUND: Articular cartilage has a high-weight-bearing area and a low-weight-bearing area, the macroscopic elastic moduli of the two regions are different. Chondrocytes are affected by the applied force at the microscopic level. Currently, the modulus of the two areas at the micro and nano levels is unknown, and studies on the relationship between macro-, micro- and nano-scale elastic moduli are limited. Such information may be important for further understanding of cartilage mechanics. Moreover, the surface morphology, proteoglycan content, and micro and nano structure of the two areas, which influences the mechanical properties of cartilage should be discussed. METHODS: Safranin-O/Fast Green staining was used to evaluate the surface morphology and semi-quantify proteoglycan content of porcine femoral head cartilage between the two weight-bearing areas. The unconfined compression test was used to determine the macro elastic modulus. Atomic force microscope was used to measure the micro and nano compressive elastic modulus as well as the nano structure. Scanning electron microscope was employed to evaluate the micro structure. RESULTS: No significant differences in the fibrillation index were observed between two areas (P = 0.5512). The Safranin-O index of the high-weight-bearing area was significantly higher than that of the low-weight-bearing area (P = 0.0387). The compressive elastic modulus of the high-weight-bearing area at the macro and micro level was significantly higher than that of the low-weight-bearing area (P = 0.0411 for macro-scale, and P = 0.0001 for micro-scale), while no statistically significant differences were observed in the elastic modulus of collagen fibrils at the nano level (P = 0.8544). The density of the collagen fibers was significantly lower in the high-weight-bearing area (P = 0.0177). No significant differences were observed in the structure and diameter of the collagen fibers between the two areas (P = 0.7361). CONCLUSIONS: A higher proteoglycan content correlated with a higher compressive elastic modulus of the high-weight-bearing area at the micro level than that of the low-weight-bearing area, which was consistent with the trend observed from the macroscopic compressive elastic modulus. The weight-bearing level was not associated with the elastic modulus of individual collagen fibers and the diameter at the nano level. The micro structure of cartilage may influence the macro- and micro-scale elastic modulus.

Decreased Filamin b expression regulates trophoblastic cells invasion through ERK/MMP-9 pathway in pre-eclampsia.

OBJECTIVES: The purpose of this study was to investigate the expression of Filamin b in the placental placenta of patients with early or late onset pre-eclampsia (PE) and its potential effects on the pathophysiology of the disease. METHODS AND METHODS: Immunohistochemistry staining, western blot assays and real time PCR were used to detect the expression level of FLN-b. The expression levels of MMP-2, MMP-9 and ERK1/2 proteins from control and FLN-b-silenced JEG-3 cells were also detected by western blot and JEG-3 cell invasion. RESULTS: Compared with normal term pregnancies placentas, the FLN-b expression was significantly lower than that of women with PE, its level in late-onset PE is lower than in early-onset PE. In FLN-b-silenced JEG-3 cells, the protein levels of MMP-2, MMP-9 and phosphorylated ERK1/2 decreased markedly and the number of cells penetrating through the transwell chamber membrane is also greatly reduced. CONCLUSIONS: Down-regulation of FLN-b inhibits the ERK/MMP-2 and MMP-9 pathways, leading to trophoblastic invasion disorders in the PE placenta.

Intervertebral disc degeneration induced by long-segment in-situ immobilization: a macro, micro, and nanoscale analysis.

BACKGROUND: Cervical spine fixation or immobilization has become a routine treatment for spinal fracture, dislocation, subluxation injuries, or spondylosis. The effects of immobilization of intervertebral discs of the cervical spine is unclear. The goal of this study was to evaluate the effects of long-segment in-situ immobilization of intervertebral discs of the caudal vertebra, thereby simulating human cervical spine immobilization. METHODS: Thirty-five fully grown, male Sprague-Dawley rats were used. Rats were randomly assigned to one of five groups: Group A, which served as controls, and Groups B, C, D, and E, in which the caudal vertebrae were in-situ immobilized using a custom-made external device that fixed four caudal vertebrae (Co7-Co10). After 2 weeks, 4 weeks, 6 weeks, and 8 weeks of in-situ immobilization, the caudal vertebrae were harvested, and the disc height, the T2 signal intensity of the discs, disc morphology, the gene expression of discs, and the structure and the elastic modulus of discs was measured. RESULTS: The intervertebral disc height progressively decreased, starting at the 6th week. At week 6 and week 8, disc degeneration was classified as grade III, according to the modified Pfirrmann grading system criteria. Long-segment immobilization altered the gene expression of discs. The nucleus pulposus showed a typical cell cluster phenomenon over time. The annulus fibrosus inner layer began to appear disordered with fissure formation. The elastic modulus of collagen fibrils within the nucleus pulposus was significantly decreased in rats in group E compared to rats in group A (p < 0.05). On the contrary, the elastic modulus within the annulus was significantly increased in rats in group E compared to rats in group A (p < 0.05). CONCLUSION: Long-segment in-situ immobilization caused target disc degeneration, and positively correlated with fixation time. The degeneration was not only associated with changes at the macroscale and microscale, but also indicated changes in collagen fibrils at the nanoscale. Long-segment immobilization of the spine (cervical spine) does not seem to be an innocuous strategy for the treatment of spine-related diseases and may be a predisposing factor in the development of the symptomatic spine.

Essential role of NbNOG1 in ribosomal RNA processing.

Nucleolar GTP-binding protein 1 (NOG1) is a highly conserved GTPase first reported in Trypanosoma as required for ribosome biogenesis. We characterized NbNOG1, a Nicotiana benthamiana NOG1 ortholog sharing more than 45% amino acid identity with Trypanosoma, yeast, and human NOG1. N. benthamiana plants silenced for NbNOG1 were stunted and produced sterile flowers. NbNOG1 is functionally interchangeable with yeast NOG1 (ScNOG1), rescuing yeast lethality caused by loss of ScNOG1. Finally, NbNOG1 silencing caused over-accumulation of pre-rRNA processing intermediates, and concomitant loss of mature rRNAs. Collectively, these data support a role for NbNOG1 in ribosomal RNA processing.

Autophagy contributes to leaf starch degradation.

Transitory starch, a major photosynthetic product in the leaves of land plants, accumulates in chloroplasts during the day and is hydrolyzed to maltose and Glc at night to support respiration and metabolism. Previous studies in Arabidopsis thaliana indicated that the degradation of transitory starch only occurs in the chloroplasts. Here, we report that autophagy, a nonplastidial process, participates in leaf starch degradation. Excessive starch accumulation was observed in Nicotiana benthamiana seedlings treated with an autophagy inhibitor and in autophagy-related (ATG) gene-silenced N. benthamiana and in Arabidopsis atg mutants. Autophagic activity in the leaves responded to the dynamic starch contents during the night. Microscopy showed that a type of small starch granule-like structure (SSGL) was localized outside the chloroplast and was sequestered by autophagic bodies. Moreover, an increased number of SSGLs was observed during starch depletion, and disruption of autophagy reduced the number of vacuole-localized SSGLs. These data suggest that autophagy contributes to transitory starch degradation by sequestering SSGLs to the vacuole for their subsequent breakdown.

The bean pod mottle virus RNA2-encoded 58-kilodalton protein P58 is required in cis for RNA2 accumulation.

UNLABELLED: Bean pod mottle virus (BPMV) is a bipartite, positive-sense (+) RNA plant virus in the Secoviridae family. Its RNA1 encodes proteins required for genome replication, whereas RNA2 primarily encodes proteins needed for virion assembly and cell-to-cell movement. However, the function of a 58-kDa protein (P58) encoded by RNA2 has not been resolved. P58 and the movement protein (MP) of BPMV are two largely identical proteins differing only at their N termini, with P58 extending MP upstream by 102 amino acid residues. In this report, we unveil a unique role for P58. We show that BPMV RNA2 accumulation in infected cells was abolished when the start codon of P58 was eliminated. The role of P58 does not require the region shared by MP, as RNA2 accumulation in individual cells remained robust even when most of the MP coding sequence was removed. Importantly, the function of P58 required the P58 protein, rather than its coding RNA, as compensatory mutants could be isolated that restored RNA2 accumulation by acquiring new start codons upstream of the original one. Most strikingly, loss of P58 function could not be complemented by P58 provided in trans, suggesting that P58 functions in cis to selectively promote the accumulation of RNA2 copies that encode a functional P58 protein. Finally, we found that all RNA1-encoded proteins are cis-acting relative to RNA1. Together, our results suggest that P58 probably functions by recruiting the RNA1-encoded polyprotein to RNA2 to enable RNA2 reproduction. IMPORTANCE: Bean pod mottle virus (BPMV) is one of the most important pathogens of the crop plant soybean, yet its replication mechanism is not well understood, hindering the development of knowledge-based control measures. The current study examined the replication strategy of BPMV RNA2, one of the two genomic RNA segments of this virus, and established an essential role for P58, one of the RNA2-encoded proteins, in the process of RNA2 replication. Our study demonstrates for the first time that P58 functions preferentially with the very RNA from which it is translated, thus greatly advancing our understanding of the replication mechanisms of this and related viruses. Furthermore, this study is important because it provides a potential target for BPMV-specific control, and hence could help to mitigate soybean production losses caused by this virus.

Study on the Variations of Key Groups and Thermal Characteristic Parameters during Coal Secondary Spontaneous Combustion.

To investigate the effect of preoxidation on the secondary spontaneous combustion of coal, the changes in the key groups and thermal characteristic parameters in coal after preoxidation were investigated through Fourier transform infrared spectroscopy (FTIR), laser thermal conductivity, and thermogravimetric experiments. Results showed that the aromatic hydrocarbons in coal gradually decrease with the rise in the preoxidation temperature, the aliphatic hydrocarbons increase and then decrease, the -C-O- group gradually decreases, and the -C=O and -COO- group content slowly increases. Preoxidation promotes the breakdown of aromatic hydrocarbons and the oxidation of oxygen-containing functional groups in coal. Meanwhile, the thermal diffusivity of coal decreases after preoxidation, while the specific heat capacity and thermal conductivity increase and then decrease. The results of the thermogravimetric analysis indicate that preoxidation changes the characteristic temperature, but it does not change the process of spontaneous combustion. The spontaneous combustion process of raw and preoxidized coals can be divided into three stages: water evaporation, oxygen adsorption, and combustion. Further, the apparent activation energy increases and then decreases with a rise in the preoxidation temperature during the moisture evaporation stage, increases during the oxygen adsorption stage, and decreases during the combustion stage.

Experimental investigation of the creep damage evolution of coal rock around gas extraction boreholes at different water contents.

The creep process of the coal rock around the extraction boreholes under stress-water coupling is an important factor affecting the stability of the boreholes. To study the influence of the water content of perimeter of the coal rock around the boreholes on its creep damage, a creep intrinsic model considering water damage was established by introducing the plastic element model from the Nishihara model. To study the steady-state strain and damage evolution of coal rocks containing pores, and verify the practicality of the model, a graded loading water-bearing creep test was designed to explore the role of different water-bearing conditions in the creep process. The following conclusions were obtained: 1) water has a physical erosion and softening water wedge effect on the perimeter of the coal rock around the boreholes, which affects the loading axial strain and displacement of the perforated specimens; 2) an increase in water content reduces the time taken for perforated specimens to enter the creep phase, making the accelerated creep phase come earlier; 3) the parameters of the water damage model are considered to be exponentially related with the water content. The experimental data are similar to the results of the model parameters, and the model shows some practicality; 4) the damage variables in the accelerated creep phase increase rapidly throughout the creep process, leading to local instability in the borehole. The findings of the study provide important theoretical implications for the study of instability in gas extraction boreholes.

Establishment of Ferroptosis-Related Key Gene Signature and Its Validation in Compression-Induced Intervertebral Disc Degeneration Rats.

Cell death and functional loss of nucleus pulposus cell play essential roles in intervertebral disc degeneration (IDD). Ferroptosis is a newly identified cell death type, and its role in IDD is still under investigation. Identifying the key genes of ferroptosis in IDD helps to identify the therapeutic targets of IDD. In this study, we downloaded the human IDD mRNA microarray data from the Gene Expression Omnibus and ferroptosis genes from FerrDb, then performed a series of analyses using strict bioinformatics algorithms. In general, we obtained 40 ferroptosis-related differential expression genes (FerrDEGs) and identified six ferroptosis key gene signatures, namely, ATF3, EIF2S1, AR, NQO1, TXNIP, and AKR1C3. In addition, enrichment analysis of the FerrDEGs was conducted, the protein-protein interaction network was constructed, the correlations between ferroptosis key genes and immune infiltrating cells were analyzed, and the lncRNA-miRNA-mRNA ceRNA network was constructed. In particular, ATF3 and EIF2S1 showed the strongest correlation with immune cell function, which might lead to the development of IDD. Finally, the expressions of ferroptosis key genes were verified in the rat compression-induced IDD. In conclusion, this preliminary study analyzed and verified the mechanism of ferroptosis in IDD, laid a foundation for the follow-up study of the mechanism of ferroptosis in IDD, and provided new targets for preventing and delaying IDD.

A Device for Isolation of Selected Single Adherent Cells.

In recent years, extensive research has been focused on the field of single cell analysis. The isolation of single cells is the first step in this type of research. However, the techniques used for direct isolation and acquisition of single adherent cells are limited. Here, we present a method of obtaining selected single adherent cells using a separation device. Compared with other single cell isolation methods, this method has the advantages of simple operation, low cost, minimal cell damage, and preservation of cell morphology. Our methodology is, therefore, suitable for the collection of selected single adherent cells.

Ovary-derived Decellularized Extracellular Matrix-based Bioink for Fabricating 3D Primary Ovarian Cells-laden Structures for Mouse Ovarian Failure Correction.

Fertility preservation is becoming a clinical duty in practice. Three-dimensional (3D) bioprinting technology is potentially realize ovarian morphological repair and reproductive endocrine function rebuild. There is no published work on 3D bioprinting ovary using a decellularized extracellular matrix (dECM)-based bioink, though dECM is the preferred matrix choice for an artificial ovary. The study aimed to explore swine ovarian dECM-based bioink to fabricate 3D primary ovarian cells (POCs)-laden structures for mouse ovarian failure correction. In this study, the ovarian dECM was converted to dECM-based bioink by dECM solution mixed with a seaweed gelatin blend solution of bioink that was characterized using scanning electron microscopy, circular dichroism, rheology, hematoxylin and eosin staining, and immunohistochemistry. The 3D scaffolds were, then, printed with or without POCs by the extrusion 3D bioprinter. The laden POCs viability was detected with the live/dead assay kit. A female castrated mouse model was established, and the mice were treated with five different methods. The results revealed that the 3D scaffold encapsulating POCs group had more positive signals in neoangiogenesis, cell proliferation and survival than the 3D scaffold group, and ensured sex hormone secretion. Meanwhile, the expression of germ cells in the 3D scaffold encapsulating POCs group was more intensely than the non-printed hydrogel encapsulating POCs group. The work shows that the 3D bioprinting ovary employing ovarian dECM-based bioink is a promising approach for ovarian failure correction.

Switchable Supramolecular Configurations of Al3+/LysTPY Coordination Polymers in a Hydrogel Network Controlled by Ultrasound and Heat.

Coordination-driven self-assembly with controllable properties has attracted increasing interest because of its potential in biological events and material science. Herein, we report on the remote, instant, and switchable control of competitive coordination interactions via ultrasound and heat stimuli in a hydrogel network. Configurational coordination changes result in the transformation of blue-emissive and opaque Al3+-amide aggregations to yellow-green-emissive and transparent Al3+-terpyridine aggregations. Interestingly, circularly polarized luminescence "off-on" switches of the metallo-supramolecular assembly are also created by these configuration changes. Additionally, the impact of the stoichiometric ratio of Al3+ and LysTPY on the assembly is also studied in detail. With a higher content of Al3+, the hydrogel with branched and abundant junctions exhibited robust, self-healing, and self-supporting properties. This in-depth understanding of the coordination interaction adjustment will afford new insights into the preparation of stimuli-responsive metallogels.

Low energy extracorporeal shock wave therapy combined with low tension traction can better reshape the microenvironment in degenerated intervertebral disc regeneration and repair.

BACKGROUND: Low-tension traction is more effective than high-tension traction in restoring the height and rehydration of a degenerated disc and to some extent the bony endplate. This might better reshape the microenvironment for disc regeneration and repair. However, the repair of the combination of endplate sclerosis, osteophyte formation, and even collapse leading to partial or nearly complete occlusion of the nutrient channel is greatly limited. PURPOSE: To evaluate the effectiveness of low-intensity extracorporeal shock wave therapy (ESWT) combined with low tension traction for regeneration and repair of moderately and severely degenerated discs; to explore the possible mechanism of action. STUDY DESIGN: Animal study of a rat model of degenerated discs. METHODS: A total of thirty-five 6-month old male Sprague-Dawley rats were randomly assigned to one of five groups (n=7, each group). In Group A (model group), caudal vertebrae were immobilized using a custom-made external device to fix four caudal vertebrae (Co7-Co10) whereas Co8-Co9 underwent 4 weeks of compression to induce moderate disc degeneration. In Group B (experimental control group), as in Group A, disc degeneration was successfully induced after which the fixed device was removed for 8 weeks of self-recovery. The remaining three groups of rats represented the intervention Groups (C-E): after successful generation of disc degeneration in Group C (com - 4w/tra - 4w) and Group D (com - 4w/ESWT), as described for group A, low-tension traction (in-situ traction) or low-energy ESWT was administered for 4 weeks (ESWT parameters: intensity: 0.15 Mpa; frequency: 1 Hz; impact: 1,000 each time; once/week, 4 times in total); Group E (com - 4w/tra - 4w/ESWT): disc degeneration as described for group A, low-tension traction combined with low-energy ESWT was conducted (ESWT parameters as Group D). After experimentation, caudal vertebrae were harvested and disc height, T2 signal intensity, disc morphology, total glycosaminoglycan (GAG) content, gene expression, structure of the Co8-Co9 bony endplates and elastic moduli of the discs were measured. RESULTS: After continuous low-tension traction, low energy ESWT intervention or combined intervention, the degenerated discs effectively recovered their height and became rehydrated. However, the response in Group D was weaker than in the other intervention groups in terms of restoration of intervertebral disc (IVD) height, whereas Group E was superior in disc rehydration. Tissue regeneration was evident in Groups C to E using different interventions. No apparent tissue regeneration was observed in the experimental control group (Group B). The histological scores of the three intervention groups (Groups C-E) were lower than those of Groups A or B (p<.0001), and the scores of Groups C and E were significantly lower than those of Group D (p<.05), but not Group C versus Group E (p>.05). Compared with the intervention groups (Groups C-E), total GAG content of the nucleus pulposus (NP) in Group B did not increase significantly (p>.05). There was also no significant difference in the total GAG content between Groups A and B (p>.05). Of the three intervention groups, the recovery of NP GAG content was greatest in Group E. The expression of collagen I and II, and aggrecan in the annulus fibrosus (AF) was up-regulated (p<.05), whereas the expression of MMP-3, MMP-13, and ADAMTS-4 was down-regulated (p<.05). Of the groups, Group E displayed the greatest degree of regulation. The trend in regulation of gene expression in the NP was essentially consistent with that of the AF, of which Group E was the greatest. In the intervention groups (Groups C-E), compared with Group A, the pore structure of the bony endplate displayed clear changes. The number of pores in the endplate in Groups C to E was significantly higher than in Group A (p<.0001), among which Group C versus Group D (p=.9724), and Group C versus Group E (p=.0116). There was no significant difference between Groups A and B (p=.5261). In addition, the pore diameter also increased, the trend essentially the same as that of pore density. There was no significant difference between the three intervention groups (p=.7213). It is worth noting that, compared with Groups A and B, peripheral pore density and size in Groups D and E of the three intervention groups recovered significantly. The elastic modulus and diameter of collagen fibers in the AF and NP varied with the type of intervention. Low tension traction combined with ESWT resulted in the greatest impact on the diameter and modulus of collagen fibers. CONCLUSIONS: Low energy ESWT combined with low tension traction provided a more stable intervertebral environment for the regeneration and repair of moderate and severe degenerative discs. Low energy ESWT promoted the regeneration of disc matrix by reducing MMP-3, MMP-13, and ADAMTS-4 resulting in inhibition of collagen degradation. Although axial traction promoted the recovery of height and rehydration of the IVD, combined with low energy ESWT, the micro-nano structure of the bony endplate underwent positive reconstruction, tension in the annulus of the AF and nuclear stress of the NP declined, and the biomechanical microenvironment required for IVD regeneration and repair was reshaped.

Aldehyde dehydrogenase plays crucial roles in response to lower temperature stress in Solanum tuberosum and Nicotiana benthamiana.

The aim of this study is to elucidate the role of ALDH2B7a during the response to lower temperature in Solanum tuberosum. This gene was found to have altered intragenic DNA methylation status in our previous reports. A total of 18 orthologs of StALDH2B7a were identified in the S. tuberosum genome, which were then divided into 8 aldehyde dehydrogenase (ALDH) subfamilies. The methylation statuses of four intragenic cytosine sites in intron 5 and exon 6 of genomic StALDH2B7a were altered by lower temperature stress, resulting in changes in the expression of StALDH2B7a. Silencing of NbALDH2C4, a homolog of StALDH2B7a in Nicotiana benthamiana, resulted in plants which were sensitive to lower temperature and accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). These data suggested that the expression of StALDH2B7a was upregulated by alteration of its intragenic cytosine methylation status during lower temperature stress, and additional StALDH2B7a enzymes scavenged excess aldehydes resulting from ROS in a response to cold stress in potato. Our study expands the understanding of the mechanisms involved in plant responses to lower temperature, and provides a new gene source to improve potato tolerance to cold stress in northern China, where lower temperature is one of the key limiting factors for crop production.

Nano and micro biomechanical analyses of the nucleus pulposus after in situ immobilization in rats.

Immobilization can lead to intervertebral disc degeneration. The biomechanical characteristics of such discs have not so far been investigated at the micro- or nanoscale, the level at which cells sense and respond to the surrounding environment. This study aimed to characterize changes in the elastic modulus of the collagen fibrils in the nucleus pulposus at the nanoscale and correlate this with micro-biomechanical properties of the nucleus pulposus after immobilization, in addition to observation of tissue histology and its gene expressions. An immobilization system was used on the rat tail with an external fixation device. The elastic modulus was measured using both nano and micro probes for atomic force microscopy after 4 and 8 weeks of immobilization. Histology of the tissue was observed following hematoxylin and eosin staining. Gene expression in the annulus fibrosus tissue was quantified using real-time reverse transcription-polymerase chain reaction. The elastic modulus of the collagen fibrils in the nucleus pulposus at the nanoscale increased from 74.07 ± 17.06 MPa in the control to 90.06 ± 25.51 MPa after 8 weeks (P = 0.007), and from 33.51 ± 9.33 kPa to 43.18 ± 12.08 kPa at the microscale (P = 0.002). After immobilization for 8 weeks, a greater number of cells were observed by histology to be aggregated within the nucleus pulposus. Collagen II (P = 0.007) and aggrecan (P = 0.003) gene expression were downregulated whereas collagen I (P = 0.002), MMP-3 (P < 0.001), MMP-13 (P < 0.001) and ADAMTs-4 (P < 0.001) were upregulated. Immobilization not only influenced individual collagen fibrils at the nanoscale, but also altered the micro-biomechanics and cell response in the nucleus pulposus. These results suggest that significant changes occur in intervertebral discs at both scales after immobilization, a situation about which clinicians should be aware when immobilization has to be used clinically.

Stable mechanical environments created by a low-tension traction device is beneficial for the regeneration and repair of degenerated intervertebral discs.

BACKGROUND: By blocking the cascade of reactions leading to intervertebral disc degeneration through immobilization-traction, a delay in intervertebral disc degeneration and its regeneration, to some extent, has been observed. However, the precise balance of regulation of the microenvironment of intervertebral disc biomechanics and coordination of the complex spatiotemporal reconstruction of the extracellular matrix have not yet been solved, and clinical results are far from successful. PURPOSE: In the present study, a mechanical degeneration model was constructed to evaluate the possibility and effectiveness of disc regeneration or repair through low-tension traction of degenerated discs so as to provide basic biomechanical information for clinical optimization of the traction device and to establish traction parameters for prevention and treatment of disc degeneration. STUDY DESIGN: A macro-, micro-, and nano-level structural analysis of degenerative discs of rat tail before and after controlled traction. METHODS: Six-month-old male Sprague-Dawley rats were randomly divided into seven groups: Group A: control group (instrumented with Kirschner [K]-wires only); Group B: Model group (caudal vertebrae immobilized using a custom-made external device to fix four caudal vertebrae [Co7-Co10], while Co8-Co9 vertebrae underwent 4 weeks of compression to induce disc degeneration); Group C: experimental control group (devices removed after the 4 week compression described in Group B, and recovered by themselves for 4 weeks). The remaining four groups represented intervention groups (Groups D and F: Co8-Co9 vertebrae compressed for 4 weeks followed by 2 or 4 weeks of in situ traction, respectively; Groups E and G: vertebrae compressed for 4 weeks followed by 2 or 4 weeks of excessive traction, respectively). X-ray and magnetic resonance imaging were performed at each time point to measure disc height and T2 signal intensity. At the end of the experiment, the animals were euthanized and tail vertebrae harvested for analysis of intervertebral disc histopathology, proteoglycan content, elastic modulus of fibers of the annulus fibrosus (AF) and nucleus pulposus (NP), and microstructure of the bony end plate. RESULTS: After 2 to 4 weeks of continuous traction (in situ and excessive traction), the Co8-Co9 intervertebral disc space of rats in Groups D to G increased significantly compared with Groups B and C (p < .05). In addition, signs of tissue regeneration were apparent in all four intervention groups (D-G). In addition, histologic scores of the intervention groups (D-G) were significantly lower than those in the model and experimental control groups (Groups B and C, respectively), although no significant difference was found between those four groups. Compared with the model group (Group B), total proteoglycan content of the NP in the intervention groups (D-G) increased significantly (p < .05). After 2 to 4 weeks of intervention (in situ and excessive traction), the morphology of pores in the bony end plate, their number, and the diameter had recovered significantly compared with those in Group B. The in situ traction group was superior to the excessive traction group, and 4 weeks in situ group significantly superior to the 2 weeks group. In all intervention groups, in both the inner and outer AF, mean fibril diameter decreased significantly (p < .05), although they remained larger in the excessive traction group than that in the in situ traction group. Consistent with trend in collagen fiber diameter, the outer AF was stiffer than the inner, and the modulus of the AF in each intervention group not significantly different from that of the control group (Group A) except Group C. However, within the NP, the variation in trend in diameter and modulus of collagen fibers was essentially inconsistent with that of the AF. CONCLUSIONS: Degenerated discs exhibit greater reconstruction after low tension traction. It is clear that the intervertebral disc mechanical microenvironment depends to a greater extent on low-tension traction than high-tension traction.

In vivo live imaging of bone using shortwave infrared fluorescent quantum dots.

Bone plays an increasingly critical role in human health and disease. More noninvasive multi-scale imaging techniques are urgently required for investigations on the substructures and biological functions of bones. Our results firstly revealed that SWIR QDs prepared by us acted as a bone-specific imaging contrast to achieve real-time observation of bone structures both in vivo and ex vivo. The major bone structures of both Balb/C nude mice and Balb/C mice including their skull, spine, pelvis, limbs, and sternum could be rapidly and gradually identified via blood circulation after QD injection in vivo. More importantly, the binding capability of our QDs mainly depended on the biological activities of bone tissues, suggesting that our technique is suitable for in vivo live imaging. In addition, the cell imaging results suggested that the potential mechanism of our bone imaging could be ascribed to the highly specific interaction between QDs and MC3T3-E1 cells. In a word, the skeletal structures and biological activities of bones are anticipated to be observed and monitored with this QD-guided SWIR imaging strategy, respectively. This radiation-free QD-guided SWIR live imaging of bone can add new insights into a comprehensive study of bones in vivo and provide a basis for early diagnosis of bone diseases.