Optimized electroencephalogram and functional near-infrared spectroscopy-based mental workload detection method for practical applications.

BACKGROUND: Mental workload is a critical consideration in complex man-machine systems design. Among various mental workload detection techniques, multimodal detection techniques integrating electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS) signals have attracted considerable attention. However, existing EEG-fNIRS-based mental workload detection methods have certain defects, such as complex signal acquisition channels and low detection accuracy, which restrict their practical application. METHODS: The signal acquisition configuration was optimized by analyzing the feature importance in mental workload recognition model and a more accurate and convenient EEG-fNIRS-based mental workload detection method was constructed. A classical Multi-Task Attribute Battery (MATB) task was conducted with 20 participating volunteers. Subjective scale data, 64-channel EEG data, and two-channel fNIRS data were collected. RESULTS: A higher number of EEG channels correspond to higher detection accuracy. However, there is no obvious improvement in accuracy once the number of EEG channels reaches 26, with a four-level mental workload detection accuracy of 76.25 ± 5.21%. Partial results of physiological analysis verify the results of previous studies, such as that the θ power of EEG and concentration of O2Hb in the prefrontal region increase while the concentration of HHb decreases with task difficulty. It was further observed, for the first time, that the energy of each band of EEG signals was significantly different in the occipital lobe region, and the power of [Formula: see text] and [Formula: see text] bands in the occipital region increased significantly with task difficulty. The changing range and the mean amplitude of O2Hb in high-difficulty tasks were significantly higher compared with those in low-difficulty tasks. CONCLUSIONS: The channel configuration of EEG-fNIRS-based mental workload detection was optimized to 26 EEG channels and two frontal fNIRS channels. A four-level mental workload detection accuracy of 76.25 ± 5.21% was obtained, which is higher than previously reported results. The proposed configuration can promote the application of mental workload detection technology in military, driving, and other complex human-computer interaction systems.

Insights into heat response mechanisms in Clematis species: physiological analysis, expression profiles and function verification.

KEY MESSAGE: Our results provide insights into heat response mechanisms among Clematis species. Overexpressing CvHSFA2 enhanced the heat resistance of yeast and silencing NbHSFA2 reduced the heat resistance of tobacco. Clematis species are commonly grown in western and Japanese gardens. Heat stress can inhibit many physiological processes mediating plant growth and development. The mechanism regulating responses to heat has been well characterized in Arabidopsis thaliana and some crops, but not in horticultural plants, including Clematis species. In this study, we found that Clematis alpina 'Stolwijk Gold' was heat-sensitive whereas Clematis vitalba and Clematis viticella 'Polish Spirit' were heat-tolerant based on the physiological analyses in heat stress. Transcriptomic profiling identified a set of heat tolerance-related genes (HTGs). Consistent with the observed phenotype in heat stress, 41.43% of the differentially expressed HTGs between heat treatment and control were down-regulated in heat-sensitive cultivar Stolwijk Gold, but only 9.80% and 20.79% of the differentially expressed HTGs in heat resistant C. vitalba and Polish Spirit, respectively. Co-expression network, protein-protein interaction network and phylogenetic analysis revealed that the genes encoding heat shock transcription factors (HSFs) and heat shock proteins (HSPs) may played an essential role in Clematis resistance to heat stress. Two clades of heat-induced CvHSFs were further identified by phylogenetic tree, motif analysis and qRT-PCR. Ultimately, we proposed that overexpressing CvHSFA2-2 could endow yeast with high temperature resistance and silencing its homologous gene NbHSFA2 reduced the heat resistance of tobacco. This study provides first insights into the diversity of the heat response mechanisms among Clematis species.

One Heat Shock Transcription Factor Confers High Thermal Tolerance in Clematis Plants.

Clematis plants play an important role in botanical gardens. Heat stress can destroy the activity, state and conformation of plant proteins, and its regulatory pathway has been well characterized in Arabidopsis and some crop plants. However, the heat resistance response mechanism in horticultural plants including Clematis has rarely been reported. Here, we identified a heat-tolerant clematis species, Clematis vitalba. The relative water loss and electrolytic leakage were significantly lower under heat treatment in Clematis vitalba compared to Stolwijk Gold. Differential expression heat-tolerant genes (HTGs) were identified based on nonparametric transcriptome analysis. For validation, one heat shock transcription factor, CvHSF30-2, extremely induced by heat stimuli in Clematis vitalba, was identified to confer tolerance to heat stress in Escherichia coli and Saccharomyces cerevisiae. Furthermore, silencing of HSF30-2 by virus-induced gene silencing (VIGS) led to heat sensitivity in tobacco and Clematis, suggesting that the candidate heat-resistant genes identified in this RNA-seq analysis are credible and offer significant utility. We also found that CvHSF30-2 improved heat tolerance of Clematis vitalba by elevating heat shock protein (HSP) expression, which was negatively regulated by CvHSFB2a. Taken together, this study provides insights into the mechanism of Clematis heat tolerance and the findings can be potentially applied in horticultural plants to improve economic efficiency through genetic approaches.

Proteome and transcriptome reveal the involvement of heat shock proteins and antioxidant system in thermotolerance of Clematis florida.

Clematis florida Thun (CfT) is an ornamental and medicinal plant. It is a cold resistant but heat sensitive species and deserves to be further investigated to improve its adaptability to heat stress. Exploring the molecular mechanism potential via an omic-analysis constitutes a promising approach towards improving heat tolerance of CfT. Two CfT lines, heat resistance (HR) and heat sensitive (HS), with differential thermotolerance capacities were used for the integrative analyses of proteomics and transcriptomes. Transcriptomes analysis showed that various pathways were significantly enriched including plant hormone signal transduction and carbon fixation pathways in prokaryotes. Proteomics study revealed the enrichment of some other pathways comprising antioxidant activity and carbohydrates metabolism. Based on combined transcriptomes and proteomics analyses and following heat stress treatment, a total of 1724 annotated genes were overlapped between both CfT lines. Particularly, 84 differential expressed genes (DEGs) were overlapped in both CfT lines. Fifteen out of these 84 genes were up-regulated solely for HR line (PS) but not for HS one (SG). This strongly suggests a potential prominent role for these genes in the thermotolerance process in PS line. We corroborate that two Hsps (Hsp18 and Hsp70) out of 20 detected proteins with higher expression levels in PS than in SG based on either global transcripts or proteins levels. According to the transcriptomes and proteomics analyses, 6 proteins and their corresponding genes were found to be significantly abundant in HR line (PS). Data are available via ProteomeXchange with identifier PXD018192. The expressions levels of these 6 genes were checked also for both CfT lines to evaluate their potential contributions in the heat tolerance process. Thus, their expression levels were approximately 2~4 times higher in HR than in HS line. We provided as well a representative schematic model to highlight the key genes involved in ROS scavenging and photorespiratory pathway in CfT. This model could be helpful also in understanding the mechanism of heat tolerance in CfT.

Expression of RcHSP70, heat shock protein 70 gene from Chinese rose, enhances host resistance to abiotic stresses.

There exist differences in the heat tolerance of Chinese rose varieties, and high temperature in summer can lead to failure of blooming in non-heat-tolerant Chinese rose varieties. We cloned a heat shock protein 70 gene (designated RcHSP70) from heat-tolerant varieties of Chinese rose (Rosa hybrida L.) to elucidate the molecular mechanism of heat tolerance and improve the quality of Chinese rose. Degenerate primers were designed for RcHSP70 according to the 5'- and 3'-end sequences of HSP70 genes in apple and tea. RcHSP70 was cloned from heat-tolerant Chinese rose varieties after heat shock. The heat shock-induced expression patterns of RcHSP70 in different Chinese rose varieties were analyzed by RT-PCR. Following heat shock (38 °C/3 h), RcHSP70 was highly expressed in the heat-tolerant varieties but not in the non-heat-tolerant varieties, indicating a close relationship between RcHSP70 and heat resistance in Chinese rose. To verify the function of RcHSP70, we constructed a prokaryotic expression recombinant vector for this gene and transformed it into Escherichia coli BL21. The tolerance of recombinant strains to abiotic stresses, including high temperature, low temperature, high salt, heavy metals, high pH, and oxidation, was evaluated. Additionally, RcHSP70 was transformed into tobacco plants. Because of the overexpression of this gene, transgenic tobacco plants improved their tolerance to high temperature and cold. In addition, transgenic tobacco showed better photosynthetic performance, relative electrical conductivity and proline content than wild tobacco after heat stress and cold stress. Our findings indicate that RcHSP70 is involved in the resistance of Chinese rose to abiotic stresses.

Chromatin-Based Regulation of Plant Root Development.

Plant is endowed with sessile habit and nutrient acquisition mainly through the root organ, which also provides an excellent model to study stem cell fate and asymmetric division due to well-organized cell layers and relatively simple cell types in root meristem. Besides genetic material DNA wrapped around histone octamer, chromatin structure determined by chromatin modification including DNA methylation, histone modification and chromatin remodeling also contributes greatly to the regulation of gene expression. In this review, we summarize the current progresses on the molecular mechanisms of chromatin modification in regulating root development.

RcLEA, a late embryogenesis abundant protein gene isolated from Rosa chinensis, confers tolerance to Escherichia coli and Arabidopsis thaliana and stabilizes enzyme activity under diverse stresses.

The late embryogenesis abundant (LEA) protein family is a large protein family that is closely associated with resistance to abiotic stresses in many organisms, such as plants, bacteria and animals. In this study, we isolated a LEA gene, RcLEA, which was cytoplasm-localized, from Rosa chinensis. RcLEA was found to be induced by high temperature through RT-PCR. Overexpression of RcLEA in Escherichia coli improved its growth performance compared with the control under high temperature, low temperature, NaCl and oxidative stress conditions. RcLEA was also overexpressed in Arabidopsis thaliana. The transgenic Arabidopsis showed better growth after high and low temperature treatment and exhibited less peroxide according to 3, 3-diaminobenzidine staining. However, RcLEA did not improve the tolerance to NaCl or osmotic stress in Arabidopsis. In vitro analysis showed that RcLEA was able to prevent the freeze-thaw-induced inactivation or heat-induced aggregation of various substrates, such as lactate dehydrogenase and citrate synthase. It also protected the proteome of E. coli from denaturation when the proteins were heat-shocked or subjected to acidic conditions. Furthermore, bimolecular fluorescence complementation assays suggested that RcLEA proteins function in a complex manner by making the form of homodimers.

A DEAD box RNA helicase is critical for pre-mRNA splicing, cold-responsive gene regulation, and cold tolerance in Arabidopsis.

Cold stress resulting from chilling and freezing temperatures substantially reduces crop production worldwide. To identify genes critical for cold tolerance in plants, we screened Arabidopsis thaliana mutants for deregulated expression of a firefly luciferase reporter gene under the control of the C-REPEAT BINDING FACTOR2 (CBF2) promoter (CBF2:LUC). A regulator of CBF gene expression1 (rcf1-1) mutant that is hypersensitive to cold stress was chosen for in-depth characterization. RCF1 encodes a cold-inducible DEAD (Asp-Glu-Ala-Asp) box RNA helicase. Unlike a previously reported DEAD box RNA helicase (LOW EXPRESSION OF OSMOTICALLY RESPONSIVE GENES4 [LOS4]) that regulates mRNA export, RCF1 does not play a role in mRNA export. Instead, RCF1 functions to maintain proper splicing of pre-mRNAs; many cold-responsive genes are mis-spliced in rcf1-1 mutant plants under cold stress. Functional characterization of four genes (PSEUDO-RESPONSE REGULATOR5 [PRR5], SHAGGY-LIKE SERINE/THREONINE KINASE12 [SK12], MYB FAMILY TRANSCRIPTION FACTOR CIRCADIAN1 [CIR1], and SPFH/PHB DOMAIN-CONTAINING MEMBRANE-ASSOCIATED PROTEIN [SPFH]) that are mis-spliced in rcf1-1 revealed that these genes are cold-inducible positive (CIR1 and SPFH) and negative (PRR5 and SK12) regulators of cold-responsive genes and cold tolerance. Together, our results suggest that the cold-inducible RNA helicase RCF1 is essential for pre-mRNA splicing and is important for cold-responsive gene regulation and cold tolerance in plants.

Isolation of the Chinese rose sHSP gene promoter and its differential regulation analysis in transgenic Arabidopsis plants.

In our previous study, we identified a Rosa chinensis heat shock protein (HSP) gene, RcHSP17.8, which was induced by abiotic stresses, such as high temperature and osmotic stress. To analyze the expression of RcHSP17.8 and the function of cis-acting elements in the promoter region, a 1,910 bp fragment of the upstream sequence of the RcHSP17.8 translation initiation codon and five promoter deletion fragments were fused to a ß-glucuronidase (GUS) report gene. These plasmids were transferred to Arabidopsis thaliana via Agrobacterium. GUS staining was seen in all the organs, especially in the vascular tissues after heat treatment. In transgenic Arabidopsis, GUS expression driven by the full length promoter was significantly higher under heat shock, but no GUS activity was detected under other abiotic stresses. Deletion analysis indicated that the region from -178 to -771 was essential for the promoter's response to high temperature.

RceIF5A, encoding an eukaryotic translation initiation factor 5A in Rosa chinensis, can enhance thermotolerance, oxidative and osmotic stress resistance of Arabidopsis thaliana.

Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein known to contain the unusual amino acid hypusine. It is a highly conserved protein found in all eukaryotic organisms. Although originally identified as a translation initiation factor, recent studies suggest that eIF5A is mainly involved in translation elongation, mRNA turnover and decay, cell proliferation, and programmed cell death. However, the precise cellular function of eIF5A remains largely unknown, especially in plants. Here, we report the identification and characterization of RceIF5A from Rosa chinensis. RceIF5A expression is up-regulated in Rosa chinensis under high temperature, and oxidative and osmotic stress conditions. We produced transgenic Arabidopsis that constitutively enhanced or suppressed expression of RceIF5A. The RceIF5A over-expression plants exhibited increased resistance to heat, and oxidative and osmotic stresses, while the suppressed expression plants (three AteIF5A isoforms in Arabidopsis were down-regulated) showed more susceptibility to these stresses. These results reveal a new physiological role for eIF5A in plants and contribute to the elucidation of the molecular mechanisms involved in the stress response pathway.

A cytosolic class I small heat shock protein, RcHSP17.8, of Rosa chinensis confers resistance to a variety of stresses to Escherichia coli, yeast and Arabidopsis thaliana.

Among the heat shock proteins (HSPs) of higher plants, those belonging to the small HSP (sHSP) family remain the least characterized in functional terms. To improve our understanding of sHSPs, we have characterized RcHSP17.8 from Rosa chinensis. Sequence alignments and phylogenetic analysis reveal this to be a cytosolic class I sHSP. RcHSP17.8 expression in R. chinensis was induced by heat, cold, salt, drought, osmotic and oxidative stresses. Recombinant RcHSP17.8 was overexpressed in Escherichia coli and yeast to study its possible function under stress conditions. The recombinant E. coli and yeast cells that accumulated RcHSP17.8 showed improved viability under thermal, salt and oxidative stress conditions compared with control cultures. We also produced transgenic Arabidopsis thaliana that constitutively expressed RcHSP17.8. These plants exhibited increased tolerance to heat, salt, osmotic and drought stresses. These results suggest that R. chinensis cytosolic class I sHSP (RcHSP17.8) has the ability to confer stress resistance not only to E. coli and yeast but also to plants grown under a wide variety of unfavorable environmental conditions.