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Background: The PDX2 gene serves as a critical catalytic component in vitamin B6 (VB6) biosynthesis pathways and plays pivotal regulatory roles in plant growth. Methods: To investigate the metabolic regulation of PDX2 (GbPDX2) from Ginkgo biloba in VB6 biosynthesis during kernel development, we successfully cloned this gene and conducted systematic expression profiling through qRT-PCR across multiple tissues and developmental stages. Results: Bioinformatic characterization revealed that GbPDX2 contains a 765-bp coding sequence encoding a 254-amino acid polypeptide. The encoded protein displays typical hydrophilic properties (average hydrophobicity index: −0.32) and was predicted to be an unstable cytosolic protein (instability index: 45.7) lacking signal peptides or transmembrane domains with cytoplasmic localization. Phylogenetic analysis demonstrated that GbPDX2’s closest evolutionary relationship was with its ortholog in Picea sitchensis, which had an amino acid sequence similarity of 83.7% with spruce PsPDX2. Tissue-specific expression analysis revealed a gradient expression profile of Kernel > Exocarp > Leaves > Stems > Roots. The expression level in kernels was significantly higher than that in other tissues (19.7 times that in roots, 8.3 times that in stems, and 5.9 times that in leaves; p < 0.01), with peak transcript levels observed in mature kernels. HPLC quantification established a strong positive correlation between GbPDX2 expression dynamics and VB6 accumulation patterns during kernel maturation (r = 0.92, p < 0.01), and the peak period of VB6 reached 288.9 ± 7.1 μg/g. Conclusions: Our findings provide the first experimental evidence that GbPDX2 spatiotemporally regulates VB6 biosynthesis in ginkgo kernels, offering novel insights into the evolutionary adaptation of vitamin metabolism in gymnosperms.

Vitamin B6 is an essential coenzyme involved in various metabolic processes critical for plant growth and development. However, its biosynthesis and regulatory mechanisms remain poorly understood in the ancient gymnosperm Ginkgo biloba. In this study, we identified two members of the PDX2 gene family (Gb_34755 and Gb_34990) through genome-wide analysis and characterized their molecular and functional properties. Bioinformatic analysis revealed distinct physicochemical traits and subcellular localizations, with Gb_34755 predicted in the cytoplasm and Gb_34990 in both chloroplasts and cytoplasm. Both proteins contain the glutaminase-related PLN02832 domain, indicating involvement in VB6 biosynthesis. Chromosomal mapping placed the genes in transcriptionally active regions on chromosomes 6 and 9. Phylogenetic analysis showed close evolutionary relationships between Ginkgo PDX2 genes and those in ferns and gymnosperms, distinct from angiosperms. Promoter analysis revealed differential enrichment of cis-elements: Gb_34990 harbored low-temperature and salicylic acid-responsive elements, while Gb_34755 showed motifs related to development. Gene expression profiling indicated significant upregulation (p < 0.05) of both genes during the late developmental stages of Ginkgo kernels, coinciding with peak VB6 content. Functional validation via transient overexpression in Nicotiana benthamiana confirmed a positive regulatory role, with VB6 levels increasing from 3.38 μg/g to 12.17 μg/g (p < 0.05). This study provides the first comprehensive functional analysis of the PDX2 gene family in Ginkgo and confirms their critical role in VB6 biosynthesis. These findings enhance our understanding of vitamin metabolism in gymnosperms and present promising targets for metabolic engineering in plants.

The latest versions of the Ross-Li model include kernels that represent isotropic reflection of the surface, describe backward reflection of soil and vegetation systems, characterize strong forward reflection of snow, and adequately consider the hotspot effect (i.e., RossThick-LiSparseReciprocalChen-Snow, RTLSRCS), theoretically able to effectively characterize BRDF/Albedo/NBAR features for various land surface types. However, a systematic evaluation of the RTLSRCS model is still lacking for various land cover types. In this paper, we conducted a thorough assessment of the RTLSRCS and RossThick-LiSparseReciprocalChen (RTLSRC) models in characterizing BRDF/Albedo/NBAR characteristics by using the global POLDER BRDF database. The primary highlights of this paper include the following: (1) Both models demonstrate high accuracy in characterizing the BRDF characteristics across 16 IGBP types. However, the accuracy of the RTLSRC model is notably reduced for land cover types with high reflectance and strong forward reflection characteristics, such as Snow and Ice (SI), Deciduous Needleleaf Forests (DNF), and Barren or Sparsely Vegetated (BSV). In contrast, the RTLSRCS model shows a significant improvement in accuracy for these land cover types. (2) These two models exhibit highly consistent albedo inversion across various land cover types (R2 > 0.9), particularly in black-sky and blue-sky albedo, except for SI. However, significant differences in white-sky albedo inversion persist between these two models for Evergreen Needleleaf Forests (ENF), Evergreen Broadleaf Forests (EBF), Urban Areas (UA), and SI (p < 0.05). (3) The NBAR values inverted by these two models are nearly identical across the other 15 land cover types. However, the consistency of NBAR results is relatively poor for SI. The RTLSRC model tends to overestimate compared to the RTLSRCS model, with a noticeable bias of approximately 0.024. This study holds significant importance for understanding different versions of Ross-Li models and improving the accuracy of satellite BRDF/Albedo/NBAR products.

Background As the number of Asian and African students studying medicine in China increases, it is imperative to evaluate the educational experiences of these international medical students (IMSs). This study was intended to investigate opinions of China-educated IMSs towards the medical curriculum and the impact of Chinese language capability on their clinical studies. Methods A self-administered questionnaire was circulated to the final-year IMSs during the graduation time from May 2019 to July 2019 in 4 universities in China. The questionnaire asked IMSs to assess the quality of medical education and provide a self-evaluation of their Chinese language capability. One-way Analysis of Variance (ANOVA) was used to determine whether IMSs’ Chinese language capability was associated with their clinical experiences and clinical competence. Results Overall, we received 209 valid responses, of which 76.1% were satisfied with the quality of medical education. Genetics, physics, and mathematics were perceived as the least relevant basic courses for medical practice, and 21.5% of student reported that community-oriented medicine was a neglected subject. Notably, 58.9% of students had positive views about discussions on ethical topics during their clerkships, and 71.3% believed they had acquired sufficient clinical skills to begin a residency program. Chinese speaking skills and communication initiatives were found to be critical factors in influencing students’ clinical experiences and competence. Conclusion This study presents the perceptions of China-educated IMSs towards medical curriculum from various aspects. Results show that language influences the education experiences of IMSs. Collectively, these results indicate that the curriculum for IMSs in China should be more problem-based and community-engaged to improve IMSs’ learning experiences and preparation for community deployment. Furthermore, training curriculum for the oral Chinese should be improved to equip IMSs with sufficient language competence to enable them to efficiently carry out clinical clerkship and rotations. Our findings provide evidence for benchmarking medical curricular codifications tailored for Asian and African students.

Leaf angle distribution (LAD) is an important attribute of forest canopy architecture and affects the solar radiation regime within the canopy. Terrestrial laser scanning (TLS) has been increasingly used in LAD estimation. The point clouds data suffer from the occlusion effect, which leads to incomplete scanning and depends on measurement strategies such as the number of scans and scanner location. Evaluating these factors is important to understand how to improve LAD, which is still lacking. Here, we introduce an easy way of estimating the LAD using open source software. Importantly, the influence of the occlusion effect on the LAD was evaluated by combining the proposed complete point clouds (CPCs) with the simulated data of 3D tree models of Aspen, Pin Oak and White Oak. We analyzed the effects of the point density, the number of scans and the scanner height on the LAD and G-function. Results show that: (1) the CPC can be used to evaluate the TLS-based normal vector reconstruction accuracy without an occlusion effect; (2) the accuracy is slightly affected by the normal vector reconstruction method and is greatly affected by the point density and the occlusion effect. The higher the point density (with a number of points per unit leaf area of 0.2 cm−2 to 27 cm−2 tested), the better the result is; (3) the performance is more sensitive to the scanner location than the number of scans. Increasing the scanner height improves LAD estimation, which has not been seriously considered in previous studies. It is worth noting that relatively tall trees suffer from a more severe occlusion effect, which deserves further attention in further study.

For classification of wood species with similar microstructure, 19 high-value hardwood species of Papilionaceae, Ebenaceae, and Caesalpiniaceae were used as experimental objects. Images of transverse sections, radial sections, and tangential sections were collected by Micro CT. Local binary patterns (LBP) are often used for feature extraction. LBP deformed forms such as uniform LBP, rotation-invariant LBP, and rotation-invariant uniform LBP were fused with Gray-Level Co-Occurrence Matrix (GLCM) to form three fusion features. The fusion features were combined with support vector machine (SVM) or BP neural network to realize wood classification. The texture feature fusion method was found to be better than the single feature classification. Among them, the effect of uniform LBP and GLCM fusion was the best, and the classification accuracy combined with SVM was the highest. The evaluation of the classification of 19 kinds of hardwood mainly depended on transverse sections, and its accuracy was higher than that of the radial and tangential sections. Therefore, the classification results of transverse sections should be taken as the main evaluation basis for the classification of the 19 high-value hardwood species.

Both leaf inclination angle distribution (LAD) and leaf area index (LAI) dominate optical remote sensing signals. The G-function, which is a function of LAD and remote sensing geometry, is often set to 0.5 in the LAI retrieval of coniferous canopies even though this assumption is only valid for spherical LAD. Large uncertainties are thus introduced. However, because numerous tiny leaves grow on conifers, it is nearly impossible to quantitatively evaluate such uncertainties in LAI retrieval. In this study, we proposed a method to characterize the possible change of G-function of coniferous canopies as well as its effect on LAI retrieval. Specifically, a Multi-Directional Imager (MDI) was developed to capture stereo images of the branches, and the needles were reconstructed. The accuracy of the inclination angles calculated from the reconstructed needles was high. Moreover, we analyzed whether a spherical distribution is a valid assumption for coniferous canopies by calculating the possible range of the G-function from the measured LADs of branches of Larch and Spruce and the true G-functions of other species from some existing inventory data and three-dimensional (3D) tree models. Results show that the constant G assumption introduces large errors in LAI retrieval, which could be as large as 53% in the zenithal viewing direction used by spaceborne LiDAR. As a result, accurate LAD estimation is recommended. In the absence of such data, our results show that a viewing zenith angle between 45 and 65 degrees is a good choice, at which the errors of LAI retrieval caused by the spherical assumption will be less than 10% for coniferous canopies.

The MODerate Resolution Imaging Spectroradiometer (MODIS) MCD43A products have been extensively applied in the remote sensing field, but recent researchers have demonstrated that these products still had the potential to be further improved by using the latest development of the kernel-driven model [RossThick-LiSparseReciprocal-Snow (RTLSRS)] in snow-covered areas, since the MCD43A product algorithm [RossThick-LiSparseReciprocal (RTLSR)] needed to be improved for the accurate simulation of snow bidirectional reflectance distribution function (BRDF) signatures. In this paper, we proposed a practical approach to improve the MCD43A products, which used the Polarization and Directionality of the Earth's Reflectance (POLDER) observations and random forest algorithm to establish the relationship between the BRDF parameters (MCD43A1) estimated by the RTLSR and RTLSRS models. We applied this relationship to correct the MCD43A1 product and retrieve the corresponding albedo (MCD43A3) and nadir reflectance (MCD43A4). The results obtained highlight several aspects: (a) The proposed approach can perform well in correcting BRDF parameters [root mean square error (RMSE) = ~0.04]. (b) The corrected BRDF parameters were then used to retrieve snow albedo, which matched up quite well with the results of the RTLSRS model. (c) Finally, the snow albedo retrieved by the proposed approach was assessed using ground-based albedo observations. Results indicated that the retrieved snow albedo showed a higher accuracy as compared to the station measurements (RMSE = 0.055, bias = 0.005), which was better than the results of the MODIS albedo product (RMSE = 0.064, bias = −0.018), especially at large angles. These results demonstrated that this proposed approach presented the potential to further improve the MCD43A products in snow-covered areas.

Background To investigate the differences between physicians in target delineation in intensity-modulated radiation therapy for nasopharyngeal carcinoma as well as their impact on target dose coverage. Methods Ninety-nine in-hospital patients were randomly selected for retrospective analysis, and the target volumes were delineated by 2 physicians. The target volumes were integrated with the original plans, and the differential parameters, including the Dice similarity coefficient (DSC), Hausdorff distance (HD), and Jaccard similarity coefficient (JSC) were recorded. The dose–volume parameters to evaluate target dose coverage were analyzed by superimposing the same original plan to the 2 sets of images on which the target volumes were contoured by the 2 physicians. The significance of differences in target volumes and dose coverage were evaluated using statistical analysis. Results The target dose coverage for different sets of target volumes showed statistically significant differences, while the similarity metrics to evaluate geometric target volume differences did not. More specifically, for PGTVnx, the median DSC, JSC, and HD were 0.85, 0.74, and 11.73, respectively; for PCTV1, the median values were 0.87, 0.77, and 11.78, respectively; for PCTV2, the median values were 0.90, 0.82, and 16.12, respectively. For patients in stages T3-4, DSC, and JSC were reduced but HD was increased compared to those in stages T1-2. Dosimetric analysis indicated that, for the target volumes, significant differences between the 2 physicians were found in D95, D99, and V100 for all the target volumes (ie, PGTVnx, PCTV1, and PCTV2) across the whole group of patients, as well as in patients with disease stages T3-4 and T1-2. Conclusions The target volumes delineated by the 2 physicians had a high similarity, but the maximal distances between the outer contours of the 2 sets were significantly different. In patients with advanced T stages, significant differences in dose distributions were found, stemming from the deviations of target delineation.

Background To determine appropriate timing of an adaptive radiation therapy (ART) replan by evaluating anatomic and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods Nineteen NPC patients were recruited. Each patient had repeat computed tomography (CT) scans after each five fractions and at treatment completion. Automatic re-contouring the targets and OARs by using deformable registration algorithm was conducted through CT-CT fusion. Anatomic changes were assessed by comparing the initial CT and repeated CT. Hybrid plans with re-contouring were generated and the dose-volume histograms (DVH) of the hybrid plan and the original plan were compared. Results Progressive volume reductions in gross target volume for primary disease (GTVnx), gross target volume for involved lymph nodes (GTVnd), and parotids were observed over time. Comparing with the original plan, each hybrid plan had no significant difference in homogeneity index (HI) for all the targets. Some parameters for planning target volumes for primary disease and high-risk clinical target volume (PTVnx and PTV1, respectively) improved significantly, notably starting from the 10th fraction. These parameters included mean dose (Dmean), dose to 95 % of the volume (D95), percentage of the volume receiving 95 % of the prescription dose (V95), and conformity index (CI) for PTVnx, and Dmean, D95, and CI for PTV1. The dosimetric parameters for PTVnd remained the same in general except for D95 and V95 which had significant improvement at specific time points; whereas for PTV2, similar trend of dosimetric changes was also observed. Dose to some OARs increased significantly at some time points. Conclusions There were significant anatomic and dosimetric changes in the targets and OARs. The target dose coverage in the hybrid plans did not get worse, but overdose occurred in some critical structures. Significant dosimetric changes should be considered as a trigger point at which ART replanning is indicated. D95/V95/CI for PTV2, Dmax for the brain stem, spinal cord, right eyeball and left lens, and Dmean/V30 for the parotids and glottis were taken into account for predicting the need for ART. Two replans at the 5th and 15th fractions were suggested.