Laccases, as early as 1959, were proposed to catalyze the oxidative polymerization of monolignols. Genetic evidence in support of this hypothesis has been elusive due to functional redundancy of laccase genes. An Arabidopsis double mutant demonstrated the involvement of laccases in lignin biosynthesis. We previously identified a subset of laccase genes to be targets of a microRNA (miRNA) ptr-miR397a in Populus trichocarpa. To elucidate the roles of ptr-miR397a and its targets, we characterized the laccase gene family and identified 49 laccase gene models, of which 29 were predicted to be targets of ptr-miR397a. We overexpressed PtrMIR397a in transgenic P. trichocarpa. In each of all nine transgenic lines tested, 17 PtrLACs were down-regulated as analyzed by RNAseq. Transgenic lines with severe reduction in the expression of these laccase genes resulted in an ∼40% decrease in the total laccase activity. Overexpression of Ptr-MIR397a in these transgenic lines also reduced lignin content, whereas levels of all monolignol biosynthetic gene transcripts remained unchanged. A hierarchical genetic regulatory network (GRN) built by a bottom-up graphic Gaussian model algorithm provides additional support for a role of ptr-miR397a as a negative regulator of laccases for lignin biosynthesis. Full transcriptome-based differential gene expression in the overexpressed transgenics and protein domain analyses implicate previously unidentified transcription factors and their targets in an extended hierarchical GRN including ptr-miR397a and laccases that coregulate lignin biosynthesis in wood formation. Ptr-miR397a, laccases, and other regulatory components of this network may provide additional strategies for genetic manipulation of lignin content.L ignin, an abundant biological polymer affecting the ecology of the terrestrial biosphere, is vital for the integrity of plant cell walls, the strength of stems, and resistance against pests and pathogens (1). Lignin is also a major barrier in the pulping and biomass-to-ethanol processes (2-4). For extracting cellulose (pulping) or for enzymatic degradation of cellulose for bioethanol, harsh chemical or physical treatments are used to reduce interactions with lignin or other cell wall components (2-4). Reducing lignin content or altering lignin structure to reduce its recalcitrance are major goals for more efficient processing.Lignin is polymerized primarily from three monolignol precursors, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol (1, 5). Over five decades, efforts have been made to understand the biosynthesis of the primary monolignols and to modify the quantity or composition of lignin. The polymerization of monolignols into a lignin polymer has long been thought to occur through oxidative polymerization catalyzed by either laccases or peroxidases (6). The mechanisms and specificity of the roles of the oxidative enzymes in lignin polymerization have been controversial (7).Laccases (EC. 1.10.3.2) are multicopper oxidoreductases. Plant laccase was the first enzyme sh...

Skin denervation was common in Ala97Ser, and degeneration of cutaneous nerve terminals was correlated with the severity of clinical phenotypes and the level of CSF protein.

Due to the Covid‐19 pandemic, National Taiwan University anatomy teachers adopted asynchronous online video teaching and reduced the size of anatomy laboratory groups in April 2020. The aim of this study was to investigate the impact of these changes on medical students’ learning. Before Covid‐19, the performance of the 2019–2020 cohort was significantly better than that of the 2018–2019 cohort. However, the implementation of modified teaching strategies significantly lowered the laboratory midterm score of the 2019–2020 cohort in the second semester. Conversely, the final laboratory examination score of the 2019–2020 cohort was significantly higher than that of the 2018–2019 cohort. Through correlation analysis, lecture and laboratory examination scores were highly correlated. Additionally, the difference in lecture and laboratory z‐scores between two cohorts, the Likert scale survey and free‐text feedback of the 2019–2020 cohort, were conducted to show the impact of modified teaching strategies. There were several important findings in this study. First, the change in teaching strategies may temporarily negatively influence medical students to learn anatomy. Besides, analyzing the performance of laboratory assessments could be a complementary strategy to evaluate online assessments. Applying lecture examination scores to predict laboratory performance was a feasible way to identify students who may have difficulty in learning practical dissection. Finally, reducing group size together with reduced peer discussion may have a negative effect on learning cadaver dissection for students with low academic performance. These findings should be taken into consideration when anatomy teachers apply new teaching strategies in anatomy courses.

We assessed the effects of treatment with 4-methylcatechol (4MC), a known inducer of nerve growth factor, on peripheral nerve regeneration by analyzing cutaneous and muscular reinnervation in mice after sciatic nerve crush injury. At 3 months postinjury, the skin innervation index was significantly higher in the 4MC group than the control group (p=0.0002); there was also increased unmyelinated fiber density (p=0.0042) and unmyelinated fibers/Remak bundle (p = 0.001) in sural nerves, indicating unmyelinated nerve fiber regeneration. These changes were accompanied by increases of transcripts for nerve growth factor (p = 0.0026) and glial cell line-derived neurotrophic factor (p=0.03) in the 4MC group. In contrast, muscle innervation indices were similar in both groups and were higher than the skin innervation index (p < 0.0001). The regeneration of myelinated nerve fibers, as assessed by fiber density, diameter and g ratio analyses in sural nerves, and amplitudes of muscle action potential in sciatic nerves, was similar in both groups. Taken together, these data suggest that 4MC specifically promoted the regeneration of unmyelinated nerve fibers and reinnervation of the skin by increasing the expression of nerve growth factor and glial cell line-derived neurotrophic factor.

No abstract