Effects of hydrogen sulfide on the growth and physiological characteristics of Miscanthus sacchariflorus seedlings under cadmium stress.

As a gas signal molecule, hydrogen sulfide (H2S) can participate in many physiological and biochemical processes such as seed germination and photosynthesis regulation. In order to explore the regulatory effect of H2S on the growth of Miscanthus sacchariflorus under Cd stress and to provide sufficient theoretical basis for the complex action of H2S and energy plants to remediate soil pollution. In this experiment, the effects of different concentrations of H2S (10, 25, 50, 100, 300, 400, 500 µmol·L-1 (µM)) pretreatment on the growth index, lipid peroxidation degree, chlorophyll (Chl) content, osmoregulation substance content, antioxidant enzyme activity and non-enzymatic antioxidant content of M. sacchariflorus under Cd stress (50 µM) were studied. The results showed that under Cd stress, the reactive oxygen species (ROS) content in the body of M. sacchariflorus was unbalanced, and the growth were severely inhibited, the activities of antioxidant enzymes, such as catalase (CAT) and superoxide dismutase (SOD) significantly decreased, and the content of osmoregulation substance, ascorbic acid (AsA) and glutathione (GSH) significantly increased. With the increase of H2S concentration, its effect on resisting Cd stress can be shown as "low concentration promotes, high concentration inhibits". When the concentration of H2S ≤ 300 µM, although there was no significant difference in Cd content compared with Cd treatment alone, it can regulate the activities of peroxidase (POD), SOD, glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR), increase the content of osmoregulation substances, oxidized glutathione (GSSG), and the transformation rate of AsA and dehydroascorbic acid (DHA) to reduce the oxidative damage and improve the growth and photosynthetic indicators of plants; when the concentration of H2S ≥ 400 µM, Cd content in the ground and root decreased significantly, but the transport factor increased significantly, the growth status of M. sacchariflorus were more severely inhibited by the combined stress of H2S and Cd. In this experiment, it was found that the concentration of H2S pretreatment ≤ 300 µM could regulate the growth of M. sacchariflorus under Cd stress to normal level, and when the treatment concentration was 50 µM, the effect was the best. It will provide a new idea for the treatment of contaminated soil by energy plants.

Characteristics of NtCCD1-3 from tobacco, and protein engineering of the CCD1 to enhance ß -ionone production in yeast.

Biosynthesis of ß-ionone by microbial cell factories has become a promising way to obtain natural ß-ionone. The catalytic activity of carotenoid cleavage dioxygenase 1 (CCD1) in cleavage of ß-carotene to ß-ionone severely limits its biosynthesis. In this study, NtCCD1-3 from Nicotiana tabacum with high ability to cleave ß-carotene was screened. Multiple strategies for improving the ß-ionone yield in Saccharomyces cerevisiae were performed. The results showed that NtCCD1-3 could cleave a variety of caroteniods at the 9,10 (9',10') double bonds and lycopene at the 5,6 (5',6') positions. The insertion site delta for NtCCD1-3 gene was more suitable for enhancing the yield of ß-ionone, showing 19.1-fold increase compared with the rox1 site. More importantly, mutant K38A of NtCCD1-3 in membrane-bonding domains could greatly promote ß-ionone production by more than 3-fold. We also found that overexpression of the NADH kinase Pos5 could improve ß-ionone yield up to 1.5 times. These results may provide valuable references for biosynthesis of ß-ionone.

Characteristics of a new carotenoid cleavage dioxygenase NtCCD10 derived from Nicotiana tabacum.

MAIN CONCLUSION: A new carotenoid cleavage dioxygenase NtCCD10 from tobacco was characterized. There is some difference between NtCCD10 and CCD1 in structure. NtCCD10 can cleave the C5-C6 (C5'-C6') and C9-C10 (C9'-C10') double bonds of carotenoids and has high catalytic activity. Carotenoid cleavage dioxygenases (CCDs) cleave carotenoids to produce a variety of apocarotenoids, which have important biological functions for organisms in nature. There are eleven CCDs subfamilies in the plant kingdom, many of which have been extensively characterized in their functions. However, as a newly classified subfamily, the function of CCD10 has rarely been studied. In this work, the function of an NtCCD10 gene from dicotyledonous Nicotiana tabacum was cloned and characterized, and its phylogeny, molecular structural modeling and protein structure were also systematically analyzed. Like other CCDs, NtCCD10 also possesses a seven bladed ß-propeller with Fe2+ cofactor in its center constituting the active site of the enzyme. The Fe2+ is also coordinated bonding with four conserved histidine residues. Meanwhile, NtCCD10 also has many unique features, such as its α1 and α3 helixes are not anti-parallel, a special ß-sheet and a longer access tunnel for substrates. When expressed in engineered Escherichia coli (producing phytoene, lycopene, ß-carotene, and zeaxanthin) and Saccharomyces cerevisiae (producing ß-carotene), NtCCD10 could symmetrically cleave phytoene and ß-carotene at the C9-C10 and C9'-C10' positions to produce geranylacetone and ß-ionone, respectively. In addition, NtCCD10 could also cleave the C5-C6 and C5'-C6' double bonds of lycopene to generate 6-methyl-5-heptene-2-one (MHO). NtCCD10 has higher catalytic activity than PhCCD1 in yeast, which provides a good candidate CCD for biosynthesis of ß-ionone and has potential applications in biotechnological industry. This study identified the taxonomic position and catalytic activity of the first NtCCD10 in dicotyledonous plants. This will provide a reference for the discovery and functional identification of CCD10 enzymes in dicotyledons.

Clinical Outcome of Surgical Hip Dislocation Combined with Impacting Bone Grafts and Implanting Iliac Bone Flaps in the Treatment of Osteonecrosis of the Femoral Head: A Mid-term Retrospective Study.

OBJECTIVE: To report the medium-term outcomes of surgical hip dislocation (SHD) combined with impacting bone grafts and implanting iliac bone flaps in the treatment of osteonecrosis of the femoral head (ONFH) and to define the indications for this treatment. METHODS: This was a single-center retrospective study. In total, 64 patients (70 hips) with ONFH treated from January 2014 to December 2017 were included in this study. There were 51 males and 13 females aged 18-55 years with an average age of 32 years. All patients underwent surgery for SHD combined with impacting bone grafts and implanting iliac bone flaps. Preoperative and postoperative clinical outcomes were assessed. The clinical outcome was assessed using the Harris hip score (HHS) and the conversion rate of total hip arthroplasty (THA). Univariate and multivariate logistic regression analyses were performed to identify risk factors affecting the clinical outcome. Kaplan-Meier (K-M) analysis was applied to calculate the survival rate of the femoral head. RESULTS: At the last follow-up (60 ± 15.08 months), the HHS was excellent for 41 hips, good for 17 hips, fair for three hips, and poor for nine hips. All nine hips with poor HHS underwent THA, including five in the first 2 years following the index surgery and four between three and 5 years. The conversion rate of total hip arthroplasty was 12.86%. Univariate and multivariate logistic regression analyses showed that the duration of hip pain and JIC classification type were significantly associated with clinical outcomes. Elderly age and advanced ONFH stage tended to lead to worse surgical outcomes. The overall survival rate of JIC classification type C1 and duration of pain ≤6 months was 98.1% and 97.8% at 72 months, respectively, as estimated by the Kaplan-Meier method. CONCLUSION: Surgical hip dislocation combined with impacting bone grafts and implanting iliac bone flaps in the treatment of ONFH had a good mid-term clinical outcome, especially for patients with retention of the lateral column of the femoral head and hip pain less than 1 year.

What happens to the gluteus medius in young and middle-aged patients with hip dysplasia?

BACKGROUND: Much research has focused on quantifying the bony characteristics of patients with developmental dysplasia of the hip (DDH). Far less attention, however, has been paid to muscle abnormalities around the hip such as those in the gluteus medius (GM). METHODS: We retrospectively examined clinical and imaging data, such as the age of onset and computed tomography (CT) findings, in 108 consecutive hips. Subjects for the control group were selected from our radiology database. Two readers independently evaluated the length (LGM), cross-sectional area (CSA), width (WGM), and thickness (TGM) of the GM and arm of GM (AGM) and angle of the GM activation (AOA) and bony parameters including the acetabulum-head index (AHI), lateral central edge angle (LCEA), acetabular index (AI), femoral offset (FO), and height of the rotation centre of femoral head (HCFH) among all cases using the imaging data. RESULTS: The patient group included 108 hips. The AGM, LGM, CSA, and TGM were lower in the DDH patients, while AOA was higher. However, there was no significant difference in the WGM between the two groups. Multiple linear regression analysis showed that AGM and AOA were independent factors affecting LCEA. The following regression equation was used: Y(LCEA) = 5.377 * X1 (AGM) - 0.310 * X2 (AOA) - 11.331. The mechanical characteristics of the GM and many bony parameters were significantly correlated (the AGM and AHI, LCEA, AI, FO, but not HCFH; AOA and AHI, LCEA, AI, but not FO or HCFH). The CSA was positively correlated with only HCFH. The rest were not statistical significance linear correlation. The multivariate regression results showed that the age of onset was positively correlated with AGM (r = 0.467). The regression equation used was Y = 9.0 * X (age of onset) - 11.4. CONCLUSION: We found difference in the morphological and mechanical characteristics of the GM between hips with DDH and hips of normal morphology. Of note, the mechanical characteristics of the GM were influenced by bony parameters in patients with DDH.