Contactless Blood Oxygen Saturation Estimation from Facial Videos Using Deep Learning.

Blood oxygen saturation (SpO2) is an essential physiological parameter for evaluating a person's health. While conventional SpO2 measurement devices like pulse oximeters require skin contact, advanced computer vision technology can enable remote SpO2 monitoring through a regular camera without skin contact. In this paper, we propose novel deep learning models to measure SpO2 remotely from facial videos and evaluate them using a public benchmark database, VIPL-HR. We utilize a spatial-temporal representation to encode SpO2 information recorded by conventional RGB cameras and directly pass it into selected convolutional neural networks to predict SpO2. The best deep learning model achieves 1.274% in mean absolute error and 1.71% in root mean squared error, which exceed the international standard of 4% for an approved pulse oximeter. Our results significantly outperform the conventional analytical Ratio of Ratios model for contactless SpO2 measurement. Results of sensitivity analyses of the influence of spatial-temporal representation color spaces, subject scenarios, acquisition devices, and SpO2 ranges on the model performance are reported with explainability analyses to provide more insights for this emerging research field.

Deep Learning Methods for Remote Heart Rate Measurement: A Review and Future Research Agenda.

Heart rate (HR) is one of the essential vital signs used to indicate the physiological health of the human body. While traditional HR monitors usually require contact with skin, remote photoplethysmography (rPPG) enables contactless HR monitoring by capturing subtle light changes of skin through a video camera. Given the vast potential of this technology in the future of digital healthcare, remote monitoring of physiological signals has gained significant traction in the research community. In recent years, the success of deep learning (DL) methods for image and video analysis has inspired researchers to apply such techniques to various parts of the remote physiological signal extraction pipeline. In this paper, we discuss several recent advances of DL-based methods specifically for remote HR measurement, categorizing them based on model architecture and application. We further detail relevant real-world applications of remote physiological monitoring and summarize various common resources used to accelerate related research progress. Lastly, we analyze the implications of research findings and discuss research gaps to guide future explorations.

Counteraction of ABA-Mediated Inhibition of Seed Germination and Seedling Establishment by ABA Signaling Terminator in Arabidopsis.

Seed germination and seedling establishment are important for the reproductive success of plants, but seeds and seedlings typically encounter constantly changing environmental conditions. By inhibiting seed germination and post-germinative growth through the PYR1/PYL/RCAR ABA receptors and PP2C co-receptors, the phytohormone abscisic acid (ABA) prevents premature germination and seedling growth under unfavorable conditions. However, little is known about how the ABA-mediated inhibition of seed germination and seedling establishment is thwarted. Here, we report that ABA Signaling Terminator (ABT), a WD40 protein, efficiently switches off ABA signaling and is critical for seed germination and seedling establishment. ABT is induced by ABA in a PYR1/PYL/RCAR-PP2C-dependent manner. Overexpression of ABT promotes seed germination and seedling greening in the presence of ABA, whereas knockout of ABT has the opposite effect. We found that ABT interacts with the PYR1/PYL/RCAR and PP2C proteins, interferes with the interaction between PYR1/PYL4 and ABI1/ABI2, and hampers the inhibition of ABI1/ABI2 by ABA-bound PYR1/PYL4, thereby terminating ABA signaling. Taken together, our results reveal a core mechanism of ABA signaling termination that is critical for seed germination and seedling establishment in Arabidopsis.

GAI Functions in the Plant Response to Dehydration Stress in Arabidopsis thaliana.

DELLA (GAI/RGA/RGL1/RGL2/RGL3) proteins are key negative regulators in GA (gibberellin) signaling and are involved in regulating plant growth as a response to environmental stresses. It has been shown that the DELLA protein PROCERA (PRO) in tomato promotes drought tolerance, but its molecular mechanism remains unknown. Here, we showed that the gai-1 (gibberellin insensitive 1) mutant (generated from the gai-1 (Ler) allele (with a 17 amino acid deletion within the DELLA domain of GAI) by backcrossing gai-1 (Ler) with Col-0 three times), the gain-of-function mutant of GAI (GA INSENSITIVE) in Arabidopsis, increases drought tolerance. The stomatal density of the gai-1 mutant was increased but its stomatal aperture was decreased under abscisic acid (ABA) treatment conditions, suggesting that the drought tolerance of the gai-1 mutant is a complex trait. We further tested the interactions between DELLA proteins and ABF2 (abscisic acid (ABA)-responsive element (ABRE)-binding transcription factors) and found that there was a strong interaction between DELLA proteins and ABF2. Our results provide new insight into DELLA proteins and their role in drought stress tolerance.

Genome-wide identification and gene expression analysis of SOS family genes in tuber mustard (Brassica juncea var. tumida).

The Salt Overly Sensitive (SOS) pathway in Arabidopsis thaliana plays important roles in maintaining appropriate ion homeostasis in the cytoplasm and regulating plant tolerance to salinity. However, little is known about the details regarding SOS family genes in the tuber mustard crop (Brassica juncea var. tumida). Here, 12 BjSOS family genes were identified in the B. juncea var. tumida genome including two homologous genes of SOS1, one and three homologs of SOS2 and SOS3, two homologs of SOS4, two homologs of SOS5 and two homologs of SOS6, respectively. The results of conserved motif analysis showed that these SOS homologs contained similar protein structures. By analyzing the cis-elements in the promoters of those BjSOS genes, several hormone- and stress-related cis-elements were found. The results of gene expression analysis showed that the homologous genes were induced by abiotic stress and pathogen. These findings indicate that BjSOS genes play crucial roles in the plant response to biotic and abiotic stresses. This study provides valuable information for further investigations of BjSOS genes in tuber mustard.

Genome-Wide Identification and Gene Expression Analysis of ABA Receptor Family Genes in Brassica juncea var. tumida.

Abscisic acid (ABA) plays important roles in multiple physiological processes, such as plant response to stresses and plant development. The ABA receptors pyrabactin resistance (PYR)/ PYR1-like (PYL)/regulatory components of ABA receptor (RCAR) play a crucial role in ABA perception and signaling. However, little is known about the details regarding PYL family genes in Brassica juncea var. tumida. Here, 25 PYL family genes were identified in B. juncea var. tumida genome, including BjuPYL3, BjuPYL4s, BjuPYL5s, BjuPYL6s, BjuPYL7s, BjuPYL8s, BjuPYL10s, BjuPYL11s, and BjuPYL13. The results of phylogenic analysis and gene structure showed that the PYL family genes performed similar gene characteristics. By analyzing cis-elements in the promoters of those BjuPYLs, several hormone and stress related cis-elements were found. The results of gene expression analysis showed that the ABA receptor homologous genes were induced by abiotic and biotic stress. The tissue-specific gene expression patterns of BjuPYLs also suggested those genes might regulate the stem swelling during plant growth. These findings indicate that BjuPYLs are involved in plant response to stresses and organ development. This study provides valuable information for further functional investigations of PYL family genes in B. juncea var. tumida.

Genome-Wide Analysis of Auxin Receptor Family Genes in Brassica juncea var. tumida.

Transport inhibitor response 1/auxin signaling f-box proteins (TIR1/AFBs) play important roles in the process of plant growth and development as auxin receptors. To date, no information has been available about the characteristics of the TIR1/AFB gene family in Brassica juncea var. tumida. In this study, 18 TIR1/AFB genes were identified and could be clustered into six groups. The genes are located in 11 of 18 chromosomes in the genome of B. juncea var. tumida, and similar gene structures are found for each of those genes. Several cis-elements related to plant response to phytohormones, biotic stresses, and abiotic stresses are found in the promoter of BjuTIR1/AFB genes. The results of qPCR analysis show that most genes have differential patterns of expression among six tissues, with the expression levels of some of the genes repressed by salt stress treatment. Some of the genes are also responsive to pathogen Plasmodiophora brassicae treatment. This study provides valuable information for further studies as to the role of BjuTIR1/AFB genes in the regulation of plant growth, development, and response to abiotic stress.

The RCC1 family protein SAB1 negatively regulates ABI5 through multidimensional mechanisms during postgermination in Arabidopsis.

Abscisic acid-insensitive 5 (ABI5) is an essential and conserved plant basic leucine zipper transcription factor whose level controls seed germination and postgerminative development. It has been demonstrated that activity of ABI5 is transcriptionally and post-translationally regulated. However, transcriptional regulation of ABI5 is not fully understood. Here, we identified SAB1 (Sensitive to ABA 1) as a novel negative regulator of ABI5 that simultaneously regulates its stability, promoter binding activity and histone methylation-mediated gene silencing of ABI5. SAB1 encodes a Regulator of Chromatin Condensation 1 (RCC1) family protein and is expressed in an opposite pattern to that of ABI5 during early seedling growth in response to abscisic acid (ABA). SAB1 mutation results in enhanced ABA sensitivity and acts upstream of ABI5. SAB1 physically interacts with ABI5 at phosphoamino acid Ser-145, and reduces the phosphorylation of ABI5 and the protein stability. SAB1 reduces ABI5 binding activity to its own promoter, leading to reduced transcriptional level of ABI5. SAB1 inactivates ABI5 transcription by increasing the level of histone H3K27me2 in the ABI5 promoter. Our findings have identified SAB1 as a crucial new component of ABA signaling which modulates early development of plant by precisely controlling ABI5 activity through multiple mechanisms.

The Soybean GmNARK Affects ABA and Salt Responses in Transgenic Arabidopsis thaliana.

GmNARK (Glycine max nodule autoregulation receptor kinase) is the homolog of Arabidopsis thaliana CLAVATA1 (CLV1) and one of the most important regulators in the process of AON (Autoregulation of Nodulation), a process that restricts excessive nodule numbers in soybean. However, except for the function in AON, little is known about this gene. Here, we report that GmNARK plays important roles in process of plant response to abiotic stresses. Bioinformatic analysis and subcellular localization experiment results showed that GmNARK was a putative receptor like kinase and located at membrane. The promoter of GmNARK contains manifold cis regulatory elements that are responsive to hormone and stresses. Gene transcript expression pattern analysis in soybean revealed GmNARK was induced by ABA and NaCl treatment in both shoot and root. Overexpression of GmNARK in Arabidopsis resulted in higher sensitivity to ABA and salt treatment during seed germination and greening stages. We also checked the expression levels of some ABA response genes in the transgenic lines; the results showed that the transcript level of all the ABA response genes were much higher than that of wild type under ABA treatment. Our results revealed a novel role of GmNARK in response to abiotic stresses during plant growth and development.

SCFAtPP2-B11 modulates ABA signaling by facilitating SnRK2.3 degradation in Arabidopsis thaliana.

The phytohormone abscisic acid (ABA) is an essential part of the plant response to abiotic stressors such as drought. Upon the perception of ABA, pyrabactin resistance (PYR)/PYR1-like (PYL)/regulatory components of ABA receptor (RCAR) proteins interact with co-receptor protein phosphatase type 2Cs to permit activation Snf1-related protein kinase2 (SnRK2) kinases, which switch on ABA signaling by phosphorylating various target proteins. Thus, SnRK2 kinases are central regulators of ABA signaling. However, the mechanisms that regulate SnRK2 degradation remain elusive. Here, we show that SnRK2.3 is degradated by 26S proteasome system and ABA promotes its degradation. We found that SnRK2.3 interacts with AtPP2-B11 directly. AtPP2-B11 is an F-box protein that is part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex that negatively regulates plant responses to ABA by specifically promoting the degradation of SnRK2.3. AtPP2-B11 was induced by ABA, and the knockdown of AtPP2-B11 expression markedly increased the ABA sensitivity of plants during seed germination and postgerminative development. Overexpression of AtPP2-B11 does not affect ABA sensitivity, but inhibits the ABA hypersensitive phenotypes of SnRK2.3 overexpression lines. These results reveal a novel mechanism through which AtPP2-B11 specifically degrades SnRK2.3 to attenuate ABA signaling and the abiotic stress response in Arabidopsis.

RBM25 Mediates Abiotic Responses in Plants.

Alternative splicing (AS) of pre-mRNAs is one of the most important post-transcriptional regulations that enable a single gene to code for multiple proteins resulting in the biodiversity of proteins in eukaryotes. Recently, we have shown that an Arabidopsis thaliana RNA recognition motif-containing protein RBM25 is a novel splicing factor to modulate plant response to ABA during seed germination and post-germination through regulating HAB1 pre-mRNA AS. Here, we show that RBM25 is preferentially expressed in stomata and vascular tissues in Arabidopsis and is induced by ABA and abiotic stresses. Loss-of-function mutant is highly tolerant to drought and sensitive to salt stress. Bioinformatic analysis and expression assays reveal that Arabidopsis RBM25 is induced by multiple abiotic stresses, suggesting a crucial role of RBM25 in Arabidopsis responses to adverse environmental conditions. Furthermore, we provide a comprehensive characterization of the homologous genes of Arabidopsis RBM25 based on the latest plant genome sequences and public microarray databases. Fourteen homologous genes are identified in different plant species which show similar structure in gene and protein. Notably, the promoter analysis reveals that RBM25 homologs are likely controlled by the regulators involved in multiple plant growth and abiotic stresses, such as drought and unfavorable temperature. The comparative analysis of general and unique cis regulatory elements of the RBM25 homologs highlights the conserved and unique molecular processes that modulate plant response to abiotic stresses through RBM25-mediated alternative splicing.