Investigation of the Alternations in the Muscle Quality of Swimming Crab (Ovalipes punctatus) during Cold-Chain Transportation Using Physicochemical and TMT-Based Quantitative Proteomic Analysis.

Physicochemical properties and protein alterations in Ovalipes punctatus during cold-chain transportation were examined via sensory scores, water-holding capacity (WHC), glucose (GLU) content, catalase (CAT) activity, urea nitrogen (UN) content, and tandem mass tag (TMT)-based proteomic analysis. The results revealed that sensory characteristics and texture of crab muscle deteriorated during transportation. Proteomic analysis revealed 442 and 470 different expressed proteins (DEPs) in crabs after 18 h (FC) and 36 h (DC) of transportation compared with live crabs (LC). Proteins related to muscle structure and amino acid metabolism significantly changed, as evidenced by the decreased WHC and sensory scores of crab muscle. Glycolysis, calcium signaling, and peroxisome pathways were upregulated in the FC/LC comparison, aligning with the changes in GLU content and CAT activity, revealing the stress response of energy metabolism and immune response in crabs during 0-18 h of transportation. The downregulated tricarboxylic acid (TCA) cycle and carcinogenesis-reactive oxygen species pathways were correlated with the decreasing trend in CAT activity, suggesting a gradual retardation in both energy and antioxidant metabolism in crabs during 18-36 h of transportation. Furthermore, the regulated purine nucleoside metabolic and nucleoside diphosphate-related processes, with the increasing changes in UN content, revealed the accumulation of metabolites in crabs.

Wide Temperature Electrolytes for Lithium Batteries: Solvation Chemistry and Interfacial Reactions.

Improving the wide-temperature operation of rechargeable batteries is crucial for boosting the adoption of electric vehicles and further advancing their application scope in harsh environments like deep ocean and space probes. Herein, recent advances in electrolyte solvation chemistry are critically summarized, aiming to address the long-standing challenge of notable energy diminution at sub-zero temperatures and rapid capacity degradation at elevated temperatures (>45°C). This review provides an in-depth analysis of the fundamental mechanisms governing the Li-ion transport process, illustrating how these insights have been effectively harnessed to synergize with high-capacity, high-rate electrodes. Another critical part highlights the interplay between solvation chemistry and interfacial reactions, as well as the stability of the resultant interphases, particularly in batteries employing ultrahigh-nickel layered oxides as cathodes and high-capacity Li/Si materials as anodes. The detailed examination reveals how these factors are pivotal in mitigating the rapid capacity fade, thereby ensuring a long cycle life, superior rate capability, and consistent high-/low-temperature performance. In the latter part, a comprehensive summary of in situ/operational analysis is presented. This holistic approach, encompassing innovative electrolyte design, interphase regulation, and advanced characterization, offers a comprehensive roadmap for advancing battery technology in extreme environmental conditions.

Changes in the physicochemical characteristics and microbial community compositions of the abdomen and cheliped muscles in swimming crab (Portunus trituberculatus) during frozen storage.

The physicochemical indexes and microbial diversity were investigated to compare the altered quality properties of the abdomen and cheliped muscle in swimming crab (Portunus trituberculatus) during 100 days of frozen storage at -20℃. Over the extended duration of frozen storage, the sensory evaluation, moisture content, water activity (Aw), and water-holding capacity (WHC) in the abdomen and cheliped muscles of swimming crab decreased, while the pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) increased. The increase and decrease rates of these indicators were smaller in the abdomen than those in the cheliped muscle. High-throughput sequencing results indicated a reduction in the microbial richness and diversity in the abdomen and cheliped muscles of the swimming crab as frozen storage time extended. Proteobacteria, Actinobacteriota, and Firmicutes, Achromobacter, Kocuria, and Staphylococcus were the dominant phylum and genus in both muscle tissues, respectively. Furthermore, the correlation analysis between the composition of the microbiota and physiochemical properties revealed that the growths of Kocuria, Vibrio, Staphylococcus, and Aliiroseovarius were closely related to the physiochemical factors. The study provides a theoretical reference for quality deterioration and develops new products of different parts in the swimming crab during frozen storage.

Effects of cold atmospheric plasma pre-treatment on maintaining the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) stored at chilled conditions.

This present study investigated the effect of cold atmospheric plasma (CAP) pre-treatment on the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) during chilled storage. The shrimp were pre-treated with the CAP at 40 kV and 36 kH for 100 s in a plasma generating equipment before the drunken treatment and compared with an untreated control sample. The results showed that the CAP pre-treatment significantly inhibited the total viable count (TVC) values, total volatile basic nitrogen (TVB-N) content, and polyphenol oxidase (PPO) activity of the drunken shrimp compared to the control treatment. Furthermore, the CAP pre-treatment also significantly maintained the myofibrillar protein (MP) content, texture properties, and a more stable histological structure of muscle fibers compared to the control. High-throughput sequencing results confirmed that the CAP pre-treatment significantly reduced the diversity and abundance of several bacteria in the shrimp. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis detected that the CAP pre-treatment effectively maintained the stability of volatile organic compounds (VOCs). These findings provide valuable theoretical support for the processing and storage of drunken shrimp.

Spectrophotometric- and LC/MS-Based Lipidomics Analyses Revealed Changes in Lipid Profiles of Pike Eel (Muraenesox cinereus) Treated with Stable Chlorine Dioxides and Vacuum-Packed during Chilled Storage.

Spectrophotometric- and liquid chromatography/mass spectrometry (LC/MS)-based lipidomics analyses were performed to explore the changes of lipid profiles in pike eel (Muraenesox cinereus) under stable chlorine dioxides (ClO2) and vacuum-packed treatment during chilled storage. The peroxide value (PV) and malondialdehyde (MDA) content in ClO2 treated and vacuum-packaged (VP) samples were significantly reduced compared to simple-packaged (SP) samples during whole chilled storage. The LC/MS-based lipidomics analyses identified 2182 lipid species in the pike eel muscle classified into 39 subclasses, including 712 triglycerides (TGs), 310 phosphatidylcholines (PCs), 153 phosphatidylethanolamines (PEs), and 147 diglycerides (DGs), among others. Further, in comparison with fresh pike eel (FE) muscle, 354 and 164 higher and 420 and 193 lower abundant levels of differentially abundant lipids (DALs) were identified in SP samples and VP samples, respectively. Compared with the VP batch, 396 higher and 404 lower abundant levels of DALs were identified in the SP batch. Among these, PCs, PEs, TGs, and DGs were more easily oxidized/hydrolyzed, which could be used as biomarkers to distinguish FE, SP, and VP samples. This research provides a reference for controlling lipid oxidation in fatty fish.

Using Machine Learning for the Risk Factors Classification of Glycemic Control in Type 2 Diabetes Mellitus.

Several risk factors are related to glycemic control in patients with type 2 diabetes mellitus (T2DM), including demographics, medical conditions, negative emotions, lipid profiles, and heart rate variability (HRV; to present cardiac autonomic activity). The interactions between these risk factors remain unclear. This study aimed to use machine learning methods of artificial intelligence to explore the relationships between various risk factors and glycemic control in T2DM patients. The study utilized a database from Lin et al. (2022) that included 647 T2DM patients. Regression tree analysis was conducted to identify the interactions among risk factors that contribute to glycated hemoglobin (HbA1c) values, and various machine learning methods were compared for their accuracy in classifying T2DM patients. The results of the regression tree analysis revealed that high depression scores may be a risk factor in one subgroup but not in others. When comparing different machine learning classification methods, the random forest algorithm emerged as the best-performing method with a small set of features. Specifically, the random forest algorithm achieved 84% accuracy, 95% area under the curve (AUC), 77% sensitivity, and 91% specificity. Using machine learning methods can provide significant value in accurately classifying patients with T2DM when considering depression as a risk factor.

Changes in the lipid profiles of hairtail (Trichiurus lepturus) muscle during air-drying via liquid chromatography-mass spectrometry analysis.

Chemical and liquid chromatography-mass spectrometry (LC/MS)-based lipidomics analyses were performed to explore the alterations in lipid profiles in the hairtail muscle during air-drying. The peroxide value (POV) and carbonyl group value (CGV) in the air-dried hairtail (ADH) significantly increased with air-drying time. Lipidomics results revealed 1,326 lipids, which were grouped into 33 lipid categories, including 422 triglycerides (TGs), 170 phosphatidylcholines (PCs), 110 phosphatidylethanolamines (PEs), among others. In addition, ADH contained 131 and 201 differentially abundant lipids (DALs) at high and low levels, respectively. Among them, DALs, TGs, PCs, LPCs, and LPEs could be used to distinguish between ADH and FH samples. The apparent alterations in ADH and FH samples were attributed to lipid decomposition, side-chain modifications during oxidation, or oxygen- and salt-promoted lipid oxidation. Thus, this study provides a more comprehensive understanding of hairtail lipid profiles before and after air-drying which can be used as a guide for hairtail products.

Association of depression and parasympathetic activation with glycemic control in type 2 diabetes mellitus.

AIM: Patients with type 2 diabetes mellitus exhibited autonomic nervous system (ANS) dysfunction and comorbidities with depressive or anxiety symptoms were related to poor glycemic control. Heart rate variability (HRV) converted from electrocardiogram (ECG) has been used as the ANS index. The study aimed to explore the associations between depression, anxiety, HRV, and glycemic control in patients with type 2 diabetes mellitus. METHODS: The Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) questionnaires were used to assess depressive and anxiety symptoms in 647 patients with type 2 diabetes mellitus (mean age was 63 ± 10 years, 56 % males). The ECG raw signals were collected from a 5-min sitting and resting baseline and then transformed to HRV indices referring ANS activation. Blood glucose and lipid profiles including glycated hemoglobin (HbA1c), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglyceride were obtained from the electronic medical records. RESULTS: Ninety-nine (15 %) participants had depressive symptoms and 59 (9 %) had anxiety symptoms. Depression and HbA1c were negatively correlated with parasympathetic activation. Depression and anxiety were positively correlated with sympathetic activation. After controlling for demographic data and lipid profiles, depression was a significant positive predictor for HbA1c levels; and HRV indices (lnLF and lnHF) were the significant negative predictors for HbA1c levels. Mediation effect analysis showed that depression was a mediator between parasympathetic activation and glycemic control. CONCLUSIONS: Lower parasympathetic activation and higher depressive symptoms may affect glycemic control in patients with type 2 diabetes mellitus. Intervention programs targeting to increase parasympathetic activities and reducing depression could be further tested for their effects on glycemic outcomes for potential clinical use.

[Sleep-improving mechanism of Chaiqin Ningshen Granules in insomnia rats: based on hippocampal metabonomics].

With the ultra high performance liquid chromatography-quadruple-electrostatic field orbitrap high resolution mass spectrometry(UHPLC-Q Exactive Orbitrap-MS)-based metabonomics technology, this study aims to analyze the effect of Chaiqin Ningshen Granules(CNG) on endogenous metabolites in insomnia rats of liver depression syndrome and explore the sleep-improving mechanism of this prescription. Parachlorophenylalanine(PCPA, ip) and chronic stimulation were combined to induce insomnia of liver depression pattern in rats, and the effect of CNG on the macroscopic signs, hemorheology, and neurotransmitters in the hippocampus of insomnia rats of liver depression syndrome was observed. After the administration, rat hippocampus was collected for liquid chromatography-mass spectrometry(LC-MS) analysis of the metabolomics. Principal component analysis(PCA), partial least squares discriminant analysis(PLS-DA), and orthogonal partial least squares discriminant analysis(OPLS-DA) were employed for analyzing the metabolites in rat hippocampus and screening potential biomarkers. MetPA was used to yield the related metabolic pathways and metabolic networks. The results show that the drugs can significantly improve the mental state, liver depression, and blood stasis of rats, significantly increase the content of 5-hydroxytryptamine(5-HT) and gamma aminobutyric acid(GABA) in hippocampus(except low-dose CNG), and significantly reduce the content of glucose(Glu)(except low-dose CNG). Among them, estazolam and high-dose CNG had better effect than others. Metabolomics analysis yielded 27 potential biomarkers related to insomnia. MetPA analysis showed 4 metabolic pathways of estazolam in intervening insomnia and 3 metabolic pathways of high-dose CNG in intervening insomnia, involving purine metabolism, glycerophospholipid metabolism, histidine metabolism, and caffeine metabolism. CNG can alleviate insomnia by regulating endogenous differential metabolites and further related metabolic pathways. The result lays a basis for further elucidating the mechanism of CNG in improving sleep.

Investigation of the activity of cathepsin B in red shrimp (Solenocera crassicornis) and its relation to the quality of muscle proteins during chilled and frozen storage.

Cathepsin B is a cysteine protease that has important effects on the quality of muscle products. In this study, the changes of cathepsin B activity and its relation to muscle proteins were investigated in intact and beheaded shrimp during chilled and frozen storage. The obtained results indicated that the water holding capacity (WHC), shear force, hardness, and myofibrillar protein (MP) content all significantly decreased in both the intact and beheaded shrimp samples with increasing storage period (p < 0.05). Specifically, beheading shrimp exhibited much more stable characteristics than intact shrimp samples during both chilled and frozen storage. The enzyme activity results suggested that cold temperature and storage induced the release of cathepsin B from the lysosomes to the mitochondria, sarcoplasm, and myofibrils in the muscle tissues. Furthermore, SDS-PAGE and transmission electron microscopy (TEM) analysis revealed that beheading the shrimp greatly inhibited the dissociation of shrimp muscle proteins during storage. The current findings suggest that cathepsin B located in the head of shrimp was likely transferred to the muscle through the first abdominal segment during storage, accelerating the dissociation of the muscle proteins. Therefore, beheading the shrimp was conducive to prolonging the shelf-life of stored shrimp products.

Network Anonymity and Cyberbullying among Chinese Adolescents: A Moderated Mediation Model.

Cyberbullying is an important issue which prevails among children and adolescents. The present study aimed to investigate the association between network anonymity and cyberbullying behavior and examine the mediating role of network morality and the moderating role of self-control in the linkage of network anonymity and cyberbullying behavior. A total of 620 participants were recruited from three high schools in southeast China and were required to complete a questionnaire measuring network anonymity, cyberbullying behavior, network morality, and self-control. A moderated mediation model was conducted by using PROCESS Macro for SPSS 3.5. The results showed that network anonymity was negatively associated with cyberbullying behavior among Chinese adolescents. Network morality mediated the association and self-control moderated the indirect association between network anonymity and cyberbullying behavior via network morality. These findings indicate that improving the network morality and self-control of adolescents with the joint efforts of individuals, families, government, and society as a whole may be an effective intervention strategy for cyberbullying behavior under the framework of digital citizens.

Analysis of volatile compounds and flavor fingerprint in hairtail (Trichiurus lepturus) during air-drying using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS).

In the present study, changes in volatile compounds during processing were analyzed using the headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), to investigate the generation of aroma in hairtails (Trichiurus lepturus) during air-drying. Physicochemical indices, such as moisture content and thiobarbituric acid reactive substances (TBARS), were also detected. Flavor fingerprints were studied and developed to distinguish the samples of fresh hairtails (0 day) from air-dried hairtails (2 and 4 days). A total of 75 volatile organic compounds (VOCs) were identified in hairtails, in which alcohols, aldehydes, ketones, and esters were the principal contributors to the formation of the overall flavor of hairtails during air-drying. Seven flavor compounds (ethanol, 3-methyl-1-butanol, 1-pentanol, hexanal, octanal, benzaldehyde, and 3-methylbutanal), two flavor compounds (acetoin and dimethyl sulfide), and eight flavor compounds (1-hexanol, 1-octen-3-ol, nonanal, heptanal, 2-heptanone, ethyl acetate, trimethylamine, and ammonia) were identified in 0, 2, and 4 air-dried hairtails as biomarkers, respectively. The results showed that HS-GC-IMS could detect VOCs in different air-dried hairtails rapidly and comprehensively.

A Bayesian model based computational analysis of the relationship between bisulfite accessible single-stranded DNA in chromatin and somatic hypermutation of immunoglobulin genes.

The B cells in our body generate protective antibodies by introducing somatic hypermutations (SHM) into the variable region of immunoglobulin genes (IgVs). The mutations are generated by activation induced deaminase (AID) that converts cytosine to uracil in single stranded DNA (ssDNA) generated during transcription. Attempts have been made to correlate SHM with ssDNA using bisulfite to chemically convert cytosines that are accessible in the intact chromatin of mutating B cells. These studies have been complicated by using different definitions of "bisulfite accessible regions" (BARs). Recently, deep-sequencing has provided much larger datasets of such regions but computational methods are needed to enable this analysis. Here we leveraged the deep-sequencing approach with unique molecular identifiers and developed a novel Hidden Markov Model based Bayesian Segmentation algorithm to characterize the ssDNA regions in the IGHV4-34 gene of the human Ramos B cell line. Combining hierarchical clustering and our new Bayesian model, we identified recurrent BARs in certain subregions of both top and bottom strands of this gene. Using this new system, the average size of BARs is about 15 bp. We also identified potential G-quadruplex DNA structures in this gene and found that the BARs co-locate with G-quadruplex structures in the opposite strand. Using various correlation analyses, there is not a direct site-to-site relationship between the bisulfite accessible ssDNA and all sites of SHM but most of the highly AID mutated sites are within 15 bp of a BAR. In summary, we developed a novel platform to study single stranded DNA in chromatin at a base pair resolution that reveals potential relationships among BARs, SHM and G-quadruplexes. This platform could be applied to genome wide studies in the future.

Deciphering hierarchical organization of topologically associated domains through change-point testing.

BACKGROUND: The nucleus of eukaryotic cells spatially packages chromosomes into a hierarchical and distinct segregation that plays critical roles in maintaining transcription regulation. High-throughput methods of chromosome conformation capture, such as Hi-C, have revealed topologically associating domains (TADs) that are defined by biased chromatin interactions within them. RESULTS: We introduce a novel method, HiCKey, to decipher hierarchical TAD structures in Hi-C data and compare them across samples. We first derive a generalized likelihood-ratio (GLR) test for detecting change-points in an interaction matrix that follows a negative binomial distribution or general mixture distribution. We then employ several optimal search strategies to decipher hierarchical TADs with p values calculated by the GLR test. Large-scale validations of simulation data show that HiCKey has good precision in recalling known TADs and is robust against random collisions of chromatin interactions. By applying HiCKey to Hi-C data of seven human cell lines, we identified multiple layers of TAD organization among them, but the vast majority had no more than four layers. In particular, we found that TAD boundaries are significantly enriched in active chromosomal regions compared to repressed regions. CONCLUSIONS: HiCKey is optimized for processing large matrices constructed from high-resolution Hi-C experiments. The method and theoretical result of the GLR test provide a general framework for significance testing of similar experimental chromatin interaction data that may not fully follow negative binomial distributions but rather more general mixture distributions.

Body Weight Misperception and Its Association with Unhealthy Eating Behaviors among Adolescents in China.

This study aims to examine associations between body weight misperception and eating behaviors among Chinese adolescents. Students (N = 2641) from a middle school and a high school in Wuhan, China participated in a cross-sectional study in May 2016. A questionnaire based on the World Health Organization’s Global School-Based Student Health Survey was employed to assess responses. Self-reported data, including weight, height, body weight perception, and eating habits, were collected. Body Mass Index (BMI) for age z-score was calculated from self-reported height and weight using WHO AnthroPlus. We used descriptive, logistic regression analysis and a Kappa test to analyze the data using SPSS. Overall, 56.6% of participants did not correctly categorize their weight status; these were much more likely to be girls. Compared with the correctly-perceived group, those who underestimated their weight tended to report eating late at night, having dinners with family, and checking nutrition labels. In contrast, weight overestimating students were less likely to report eating late at night, having breakfasts with family, having dinners with family, and discussing nutrition topics over meals. Body weight misperception was associated with unhealthy eating behaviors among Chinese adolescents.

The Effect of Vitamin A on Fracture Risk: A Meta-Analysis of Cohort Studies.

This meta-analysis evaluated the influence of dietary intake and blood level of vitamin A (total vitamin A, retinol or ß-carotene) on total and hip fracture risk. Cohort studies published before July 2017 were selected through English-language literature searches in several databases. Relative risk (RR) with corresponding 95% confidence interval (CI) was used to evaluate the risk. Heterogeneity was checked by Chi-square and I² test. Sensitivity analysis and publication bias were also performed. For the association between retinol intake and total fracture risk, we performed subgroup analysis by sex, region, case ascertainment, education level, age at menopause and vitamin D intake. R software was used to complete all statistical analyses. A total of 319,077 participants over the age of 20 years were included. Higher dietary intake of retinol and total vitamin A may slightly decrease total fracture risk (RR with 95% CI: 0.95 (0.91, 1.00) and 0.94 (0.88, 0.99), respectively), and increase hip fracture risk (RR with 95% CI: 1.40 (1.02, 1.91) and 1.29 (1.06, 1.57), respectively). Lower blood level of retinol may slightly increase total fracture risk (RR with 95% CI: 1.11 (0.94, 1.30)) and hip fracture risk (RR with 95% CI: 1.27 (1.05, 1.53)). In addition, higher ß-carotene intake was weakly associated with the increased risk of total fracture (RR with 95% CI: 1.07 (0.97, 1.17)). Our data suggest that vitamin A intake and level may differentially influence the risks of total and hip fractures. Clinical trials are warranted to confirm these results and assess the clinical applicability.

Associations among Screen Time and Unhealthy Behaviors, Academic Performance, and Well-Being in Chinese Adolescents.

Screen time is negatively associated with markers of health in western youth, but very little is known about these relationships in Chinese youth. Middle-school and high-school students (n = 2625) in Wuhan, China, completed questionnaires assessing demographics, health behaviors, and self-perceptions in spring/summer 2016. Linear and logistic regression analyses were conducted to determine whether, after adjustment for covariates, screen time was associated with body mass index (BMI), eating behaviors, average nightly hours of sleep, physical activity (PA), academic performance, and psychological states. Watching television on school days was negatively associated with academic performance, PA, anxiety, and life satisfaction. Television viewing on non-school days was positively associated with sleep duration. Playing electronic games was positively associated with snacking at night and less frequently eating breakfast, and negatively associated with sleep duration and self-esteem. Receiving electronic news and study materials on non-school days was negatively associated with PA, but on school days, was positively associated with anxiety. Using social networking sites was negatively associated with academic performance, but positively associated with BMI z-score, PA and anxiety. Screen time in adolescents is associated with unhealthy behaviors and undesirable psychological states that can contribute to poor quality of life.

[Clinical comparative study on the treatment characteristics of secretory otitis media between cleft and non-cleft palate patients].

OBJECTIVE: To discuss the treatment characteristics of secretory otitis media (SOM) in cleft palate children. METHODS: A total of 319 patients (524 ears) with SOM and cleft palate (3-14 years old) who accepted treatment were divided into experiment group A, group B, and group C according to effusion characteristics in the middle ear and tympanic pressure. Group A included 112 patients with serous effusion (198 ears). Group B included 162 patients with mucinous effusion (248 ears). Group C included 45 patients (78 ears) with negative pressure in the middle ear without effusion and an acoustic immittance. A total of 208 patients (246 ears) with SOM and tonsil and adenoid hypertrophy were divided into control group Al, group B1, and group Cl matched with the same effusion characteristics in the middle ear and tympanic pressure. Group A and Al accepted puncture in the tympanic cavity, group B and B1 accepted tympanostomy tubes, and group C and Cl accepted puncture in the tympanic cavity after palatoplasty, adenoidectomy, and tonsillectomy. All groups were treated with antibiotics and ear drops. Cure rate and recurrence rate between the experiment group and the control group were compared. RESULTS: The control group had a better cure rate [93.09% (229/246)] than the experiment group [77.29% (405/524)] 12 months after treatment. The experiment group had a higher recurrence rate [14.57% (59/405)] than the control group [3.93% (9/229)]. Statistical differences were observed between the two groups (P<0.05). SOM with cleft palate initially had a low cure rate, and thus it was treated repeatedly for many times. CONCLUSION: SOM with cleft palate is different from normal otitis media in terms of clinical manifestation, treatment, outcome, and prognosis. This case should be considered a special otitis media to be treated with special examination and therapy to obtain better results. Repeated puncture in the tympanic cavity and tympanostomy tubes for six months according to effusion characteristics are better treatment options for patients with SOM and cleft palate.

Epidermal cell differentiation in cotton mediated by the homeodomain leucine zipper gene, GhHD-1.

Gossypium hirsutum L. (cotton) fibres are specialized trichomes a few centimetres in length that grow from the seed coat. Few genes directly involved in the differentiation of these epidermal cells have been identified. These include GhMYB25-like and GhMYB25, two related MYB transcription factors that regulate fibre cell initiation and expansion. We have also identified a putative homeodomain leucine zipper (HD-ZIP) transcription factor, GhHD-1, expressed in trichomes and early fibres that might play a role in cotton fibre initiation. Here, we characterize GhHD-1 homoeologues from tetraploid G. hirsutum and show, using reporter constructs and quantitative real-time PCR (qRT-PCR), that they are expressed predominantly in epidermal tissues during early fibre development, and in other tissues bearing epidermal trichomes. Silencing of GhHD-1 reduced trichome formation and delayed the timing of fibre initiation. Constitutive overexpression of GhHD-1 increased the number of fibres initiating on the seed, but did not affect leaf trichomes. Expression of GhHD-1 in cotton silenced for different fibre MYBs suggest that in ovules it acts downstream of GhMYB25-like, but is unaffected in GhMYB25- or GhMYB109-silenced plants. Microarray analysis of silencing and overexpression lines of GhHD-1 indicated that it potentially regulates the levels of ethylene and reactive oxidation species (ROS) through a WRKY transcription factor and calcium-signalling pathway genes to activate downstream genes necessary for cell expansion and elongation.

GhMYB25-like: a key factor in early cotton fibre development.

MYB transcription factors have been implicated in regulation of the development of ovule epidermal cells into the elongated seed fibres of cotton. An R2R3 MYB, GhMYB25-like, identified from its reduced expression in a fibreless mutant of cotton (Xu142 fl), is here shown to play a key role in the very early stages of fibre cell differentiation. A GhMYB25-like promoter-GUS construct was expressed predominantly in the epidermal layers of cotton ovules before anthesis (-3days post-anthesis, dpa), increasing in expression in 0-dpa ovules, primarily in those epidermal cells expanding into fibres, and then in elongating fibres at +3dpa, declining thereafter. This was consistent with GhMYB25-like transcript abundance during fibre development. RNA interference suppression of GhMYB25-like resulted in cotton plants with fibreless seeds, but normal trichomes elsewhere, phenocopying the Xu142 fl mutant. Like Xu142 fl these plants had reduced expression of the fibre-expressed MYBs, GhMYB25 and GhMYB109, indicating that GhMYB25-like is upstream from those MYBs. This hierarchy was supported by the absence of any change in transcript level of GhMYB25-like in GhMYB25- and GhMYB109-silenced transgenic lines. Transgenic cotton with an additional copy of the native gene had elevated expression of GhMYB25-like in ovules, but no obvious increase in fibre initials, suggesting that there may be other factors that interact with GhMYB25-like to differentiate epidermal cells into fibre cells.