Heart disease is a major threat to human health due to the high morbidity and mortality rates. As a result, the discovery of adult zebrafish heart regeneration provides a new perspective for the study and treatment of human heart diseases. This study reviewed the zebrafish heart injury models for heart regeneration, such as apex amputation, cryoinjury, genetic ablation of cardiomyocyte models and so on. In addition, we also explored the essential mechanisms underlying heart regeneration, including the spatiotemporal activation of multiple signaling pathways in different cell types, epigenetic reprogramming, coronary revascularization, activation of key development-related transcription factors, and the disassembly and reassembly of cardiomyocyte sarcomeric structure. Analysis of the mechanism of heart regeneration provides more references basis for therapeutic strategies to overcome heart disease in the future.

In order to further explore the genes related to cold tolerance in cotton, we utilized transcriptome sequencing of leaf tissues of TM-1 (Gossypium hirsutum) and Hai7124 (G. barbadense) under cold treatment (4 ℃) and the control treatment (28 ℃) at different stages to compare and analyze their differences in cold tolerance related gene’s functions, expression patterns, and metabolic pathways. The results showed that Hai7124 was more sensitive to cold stress than TM-1, and its phenotype changed faster and more obviously under cold stress. Transcriptome analysis showed that TM-1 and Hai7124 contained 8 713 and 12 461 genes in response to cold stress, respectively. According to the orthologs between TM-1 and Hai7124, there were 1 518 and 3 577 specific response genes in TM-1 and Hai7124, respectively. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the specific response genes in TM-1 were mostly involved in hormone signal transduction, circadian rhythm, and other regulation processes, while specific response genes in Hai7124 were mostly involved in amino acid metabolism processes such as lysine, arginine, serine and threonine. Fatty acid metabolism genes related to cold tolerance and genes in key families of fatty acid synthesis pathways, such as acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-ACP desaturase (SAD), fatty acid desaturase (FAD), long chain acyl-CoA synthetase (LACS) from TM-1 and Hai7124 were further analyzed. During the whole cold stress treatment, TM-1 had 11 up-regulated genes, while Hai7124 had 10 down-regulated genes. The real time quantitative reverse polymerase chain reaction (RT-qPCR) was used to verify expression levels of five response genes. It was found that their expression levels were highly correlated with the expression levels of transcriptome. This study is helpful to analyze the molecular mechanism of different cold tolerance of TM-1 and Hai7124 and provide important genetic resources for the improvement of cold tolerance in cotton breeding.

Sixty-eight simple sequence repeat (SSR) primer pairs were designed based on the transcriptome data of Cymbidium faberi and 25 primer pairs with stable amplification and better polymorphism were selected for genetic diversity analysis of 41 C. hybridum cultivars. The results showed that a total of 187 SSR bands were amplified, and 171 (91.44%) of them were polymorphic with the average of 6.84 bands per primer pair. The mean value of polymorphism information content (PIC) and the number of genotypes per SSR marker were 0.770 3 and 12.88, respectively. Genetic similarity coefficient among 41 cultivars ranged from 0.57 to 0.99 with an average of 0.72. A dendrogram of genetic relationship constructed using unweighted pair-group method with arithmetic mean (UPGMA) showed that the tested accessions could be classified into five clustering groups with the similarity coefficient of 0.71, which were consistent to some extent with the plant size, branch type and flower color. The above results reveal the genetic diversity and relationships among the tested accessions. The newly developed SSR markers will be useful tools for molecular breeding of C.hybridum.

The effects of spraying selenium (Se) at different stages on Se contents and fruit quality of citrus were studied to provide basic data for rational Se application. A foliar spray of 200 mg/L sodium selenite solution was applied to 15 years’ ‘Bendizao’ mandarin (Citrus succosa Hort. Ex Tanaka) at the young fruit stage, fruit expansion stage and fruit coloring stage, respectively. Leaf and fruit samples were collected at the maturing stage to detect Se contents, organic degree of Se, other nutrient contents and fruit quality. The result showed that spraying Se before the fruit coloring stage increased total Se contents in the leaves and fruits. Se organic proportion of fruit decreased with the delay of Se spraying date. The activities of superoxide dismutase and peroxidase under the spraying Se treatments were higher, but the content of malondialdehyde was lower. Se promoted the absorption of total nitrogen and total potassium, but inhibited the absorption of total phosphorus, total calcium and total magnesium. The fruit peel was thinner, the content of total acid was lower, and the contents of soluble solid, total sugar and vitamin C were higher by spraying Se at the young fruit stage. In conclusion, foliar spraying Se can improve the fruit quality by increasing the Se contents and affecting the balance of nutrient absorption, thus improving the antioxidant capacity and the quality of citrus fruits. The comprehensive effect of foliar spraying Se at the fruit young stage is the best.

In this study, we explored the effects of exogenous melatonin (MEL) and epibrassinolide (EBL) on the regeneration of callus subcultured for 17 years of Zoysia matrella (L.) Merr. under simulated drought stress, aiming to select the optimal MEL or EBL concentrations that improved the regeneration capacity of callus, and obtain plants with strong drought resistance. The results showed that 0.20 mmol/L MEL markedly promoted the regeneration of callus, and the regeneration rate was 61.1%. Different degrees of drought stress significantly affected the regeneration capacity of callus, and the regeneration rate decreased as polyethylene glycol (PEG) concentration increased. Under 5% and 10% PEG-6000 stress, the regeneration plants of Z. matrella with strong drought tolerance could be obtained. Under 5%-15% PEG-6000 stress, addition of 0.05-0.20 mmol/L MEL or 0.05-0.50 μmol/L EBL promoted the recovery of callus regeneration. Under 10% PEG-6000 stress, 0.20 mmol/L MEL was the best treatment to promote the callus regeneration, and the regeneration rate was as high as 55.6%. High concentrations of MEL and EBL inhibited callus regeneration rates. Moreover, when adding 0.05-0.20 mmol/L MEL under 5% or 10% PEG stress, catalase activity of callus increased markedly; when adding 0.05-0.10 μmol/L EBL, peroxidase, superoxide dismutase activities of callus significantly increased, and the two exogenous hormones evoked response of different antioxidant enzymes during the regeneration of Z. matrella callus. It can be seen that, 0.05-0.20 mmol/L MEL or 0.05-0.10 μmol/L EBL notably promote the regeneration capacity of Z. matrella callus. This study provides new pathways for improving the regeneration capacity of callus in long-term subculture and drought-resistant selection of Z. matrella.

The positioning test was carried out in the Chongzhou Experimental Base of Sichuan Agricultural University in 2018—2019, aiming at exploring the effects of straw returning and nitrogen (N) fertilizer management on soil N supply and yield of direct seeding rice under the wheat (rape)-rice rotation. The two-factor split-zone design was adopted. The main area was wheat/rape straw being turned over to field (M₁) and straw being not returned to field (control, M₀). In the sub-area, on the basis of 150 kg/hm² of N application, there were three kinds of N fertilizer operation, including N fertilizer moving forward (N₁), balanced N application (N₂) and N fertilizer moving backward (N₃), with no N fertilizer application as a control (N₀). Then, the contents of soil ammonium-N, nitrate-N and total N, N accumulation and yield of direct seeding rice were determined. The results showed that the N accumulation of rice plant increased by 7.13% (8.50%) and the yield increased by 0.94% (1.43%) in 2018, and which increased to 15.17% (17.12%) and 6.60% (7.42%) in 2019 under the wheat (rape)-rice rotation at the maturing stage compared with those without straw returning. At the jointing stage in 2018, N accumulation amounts of direct seeding rice in the wheat (rape) stubble field were N₁＞N₂＞N₃ treatments as a whole. At the full heading stage and maturing stage, N accumulation amounts and yields of rice plants were N₃＞N₂＞N₁ treatments under the no straw returning, as well as N₂＞N₃＞N₁ treatments under the straw returning. Compared with the no straw returning, the ammonium-N contents in 0-10 and ＞10-20 cm soil layers at the rice maturing stage under the wheat (rape)-rice rotation increased or decreased after straw returning. While the nitrate-N contents decreased by 44.22% (30.99%) and 8.05% (20.09%) overall. Soil total N contents had little change in each growth stage of direct seeding rice, and the contents of nitrate-N, ammonium-N and total N in the soils under the N₁ treatment remained at a high level in each growth stage. In conclusion, continuous straw returning is beneficial to increase soil total N content; under the wheat (rape)-rice rotation, the balanced N application could effectively promote the N uptake by rice plants and significantly increase the rice yield, and the effect of increasing yield is better under the rape-rice rotation.

In order to scientifically identify and evaluate the soil heavy metal pollution and ecological risk in the background area with high heavy metal contents, 309 sets of maize and rhizosphere soil samples were collected in Hezhen Town of Hezhang County of Guizhou Province, and 20 maize samples from different parts of roots, stems and leaves were collected. The contents of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were analyzed in topsoil and maize samples. Also, speciations of heavy metals in the rhizosphere soil samples were analyzed (Cr was not measured). The results showed that the contents of heavy metals in the soils were relatively high, and the averages were remarkably higher than the national soil background value (NBV), and the content of Cd element was nearly seven times higher than the NBV. The soil was mainly acidic, and the ecological risk was high based on the total amount of heavy metals. Speciation analysis indicated that heavy metals (As, Cu, Hg, Ni, Pb, and Zn) mainly existed in the forms of strong organic binding state and residual state, with low bioavailability, and the bioavailability of Cd was high. The ecological risk was mainly caused by Cd based on speciation of heavy metals. In the soil-corn system, the bioconcentration factors and translocation factors were both low, so heavy metals were difficult to be enriched in the corn. The contents of heavy metals in corn seeds did not exceed the standard, and the crops were safe. The above results provide a theoretical basis for further studying the migration and transformation law of heavy metals in rock-soil-gas-biota media, integrating geology, pedology and biology to establish a unified standard, and scientifically evaluating the ecological environment risk and health risk.

The effects of Tieguanyin extracts from different fragrance types (Qingxiang, Tgy-Q; Nongxiang, Tgy-N; and Chenxiang, Tgy-C) on the behavior of APP/PS1 double transgenic Alzheimer’s disease (AD) mice were studied, and the mechanisms of oxidative stress and inflammation were analyzed. Forty six-month-old female APP/PS1 mice were equally divided into five groups, which named as model group, donepezil group, Tgy-Q, Tgy-N and Tgy-C groups, and the control group consisted of 10 C57BL/6J mice. The drug was given by oral gavage for 70 consecutive days, and Y-maze test and open field test were performed during administration. At the end of the behavioral study, they were executed, and their plasma and brain tissue were collected, and then the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) content in plasma of mice were determined, and the morphological changes of glial cells were observed by immunohistochemical assay. The spontaneous alternation behavior rates of Tgy-Q, Tgy-N, Tgy-C extract treatments in the Y-maze experiment of mice groups were increased by 17.3%, 17.6% and 19.8% compared with the model group, respectively (P＜0.001), and the learning and memory abilities of mice in each group were significantly improved as compared with the model group. The results of open field test showed that the movement distances and residence time in the central area of mice fed with Tieguanyin extracts were significantly increased. The effective movement distances in the central area of mice was increased by 93.0% in the Tgy-C group (P＜0.001), followed by 82.0% in the Tgy-N group (P＜0.001) and 49.2% in the Tgy-Q group (P＜0.001). The optimal retention time in the central area of mice was 105.0% in the Tgy-C group (P＜0.01), followed by 84.1% in the Tgy-N group (P＜0.01), and 66.8% in the Tgy-Q group (P＜0.05). In the open field test, the spatial exploration ability and anxiety behavior of Tgy-C group were the best in all the treatments. In this experiment, oxidative stress levels of three Tieguanyin treatments were decreased, which are the main mechanisms of Tieguanyin against Alzheimer’s disease of APP/PS1 mice. Compared with the model group, the MDA contents of plasma in the Tgy-Q, Tgy-N, Tgy-C treatments were significantly reduced by 18.44%, 12.97% and 15.11%, respectively, and the SOD activities in the three groups were increased by 15.31%, 13.69% and 18.80%, respectively. Tieguanyin extracts also improved the morphological recovery of microglia and astrocytes in the brain of AD mice. The above research results indicate that three Tieguanyin extracts had a certain alleviating or protective effect on AD mice.

In order to observe the effects of bioactive peptides from black-bone chicken on diabetic mice, the peptide was extracted from the breast muscles of black-bone chicken, through the steps of enzymolysis, centrifugation, ultrafiltration and freeze-drying, whose molecular mass is less than 5 kDa. Then the diabetic mice induced by streptozotocin (STZ) were randomly divided into low-dose, high-dose, drug and positive control groups (n=10), fed with 100 mg/kg bioactive peptide, 400 mg/kg bioactive peptide, 30 mg/kg acarbose and saline placebo, respectively. Besides, the normal control group was set and fed with saline. The initial body mass, fasting blood glucose level, and the final body mass, biochemical parameters after 30 d of continuous feeding were measured. Meanwhile, the pathological changes were observed. The results showed that at the end of the experiment, the body mass of positive control group decreased significantly (P＜0.05), whereas those of the other four groups increased. Compared with the positive control group, the low-dose, high-dose and drug groups had lower final fasting blood glucose levels (high-dose and drug groups, P＜0.05), lower total cholesterol level and low density lipoprotein cholesterol level, but higher high density lipoprotein cholesterol level (high-dose group, P＜0.05); higher superoxide dismutase activity, but lower malondialdehyde content (high-dose group, P＜0.05). In the low-dose, high-dose and drug groups, insulin level and islet area were significantly higher than those in the positive control group (P＜0.05); their liver and renal indexes were higher than those in the normal control group, but the pathological changes such as cell swelling and vacuolation were less than those in the positive control group. In conclusion, bioactive peptides from black-bone chicken have certain effects on hypoglycemia, hypolipidemia and tissue-protection of the pancreas, liver and kidney. In addition, the feeding dose of 400 mg/kg has better effect than that of 100 mg/kg.

There are sporadic immature individuals in the natural migration population of Chinese mitten crab (Eriocheir sinensis). The low temperature environment with high latitude and high altitude can significantly increase the proportion of immature individuals and facilitate collection. In this study, experiments were carried out to verify whether it can grow or reproduce normally in the subsequent third-year-old stage. In the spring of 2018, the two-year-old immature individuals from the Koluke Lake in Qinghai Province were collected as crab larvae and moved back to the ponds in the Yangtze River Basin for breeding, and the third-year-old crab was obtained for the first time. The experimental results showed that: 1) After domestication, the Chinese mitten crab population could successfully molt and grow in the ponds; the growth performance was similar to that of the conventional cultured crab, and the cultivated size was larger than that of the adult crab in the Koluke Lake area. 2) The third-year-old male and female individuals could be sexually mature, and the fecundity was similar to that of conventional crabs, and their offspring could be obtained by raising seedlings in earth ponds. 3) The nutritional compositions of third-year-old crabs cultured in ponds were intact, and some indexes were significantly different from those of conventional crabs, which might be related to the life history of plateaus and lakes. The results also showed that the size of the two-year-old immature crab was smaller than that of the conventional crab of the same age, and the size of the pond-cultured crab in the third-year-old stage was significantly larger than that of the Koluke Lake crab in the same period, indicating the existence of low temperature diapause and compensatory growth in the life history of E. sinensis. To sum up, the life cycle of the third-year-old crab population is more complex, and its nutrient deposition characteristics, mineral element contents, phased growth and accumulated temperature differences can provide new references for exploring the mechanism of low temperature diapause, life cycle prolongation and compensatory growth of the invertebrates.

In order to achieve high-efficiency expression of exogenous protein in sheep lung fibroblasts OAR-L1, and to explore a suitable transfection method for the cell line, the transfection efficiencies of polyethyleneimine (PEI), Lipofectamine^TM 2000 transfection reagent (Lipo 2000), Cytofect^TM fibroblast transfection kit (CF2) and lentivirus mediated cell transfection in the OAR-L1 cells were compared. The results showed that when OAR-L1 cells were transfected with fluorescent plasmids pLentiCMV-EGFP-Puro or pLentiCMV-mCherry-Puro, PEI-, Lipo 2000- and CF2-mediated transfection could be affected by the cell density and the amount of transfection reagents, besides the best transfection efficiency of each method was less than 30%. While the number of fluorescent cells obtained by lentivirus-mediated cell infection was not limited by these two factors, and was significantly higher than the former three methods. The recombinant virus solution could be stored at 4 or －80 ℃ for at least 15 d without decline of the infection efficiency. To co-express two exogenous proteins in the OAR-L1 cells, mixing two packaged lentivirus in equal proportions followed by infection could achieve a higher co-transformation rate. The above results show that lentivirus infection is a cell transfection method that could achieve high expression of exogenous proteins in the OAR-L1 cells, and provide certain references for the selection of transfection methods for other difficult-to-transfect cells.

Light stress can restrict the normal growth and development of rapeseed seedlings. In order to realize the early diagnosis of light stress in rapeseed seedlings, a 21 d experiment was conducted on rapeseed seedlings of two leaves and one heart stage using hyperspectral imaging technology. After preprocessing the collected canopy leaf spectra, the light-stress-sensitive bands were extracted through spectral reflectance and continuous wavelet transform. Then successive projection algorithm was used to extract characteristic wavelengths, and the continuous wavelet transform-stepwise discriminant analysis method was used to extract wavelet features. To further improve the accuracy of the stress detection model, a total of four features including the area under curvein the 939-978 nm band, the tangent value of the characteristic angle (tan θ), the reflectances at 984 and 1 408 nm were selected by analyzing the characteristics of the spectral band and the evolution of the spectral characteristics at the seedling stage of rapeseed to establish a multi-feature fusion Fisher discriminant model. The results showed that the average classification accuracy of the model was 86.88%, which achieved the best classification effect in the d₂₀ family, with an accuracy of 95.00%. The research provides a powerful reference for the rapid diagnosis of light stress in rapeseed based on hyperspectral imaging technology.

In order to study the change rule of the internal flow field of the self-cleaning mesh filter with different inlet flow rates during the filtration and sewage processes, we used Fluent software to carry out the numerical simulation of the clear-water flow field for the filtration and sewage processes of the self-cleaning mesh filter, and obtained the pressure field and velocity field at the different inlet flow rates. Comparing the numerical simulation results with the physical test results, the relative error was within 10%, which confirmed the reliability of the numerical simulation. Meanwhile, the results of the numerical simulation showed that the higher the water flow rate was, the more violent the mixing of water was in the tank and the sewage system, which could reduce the sedimentation and help to improve the filtration and sewage effects. Moreover, with the increase of the inlet flow rate, the pressure difference between the inlet and outlet of the tank and the sewage system increased, and the head loss also increased, and the requirement for the stability of the filter structure was higher. The above research results can provide a reference for the optimization of the horizontal self-cleaning mesh filter structure.

To investigate the impact of soil physical properties and driving velocity on the driving performance of a tracked tractor and obtain better operating conditions on paddy soils in the plastic state, a paddy soil mechanical model and a tracked tractor physical model were established using the RecurDyn, a multi-body dynamics software. The method of the quadratic orthogonal rotating combination design of four factors and five levels was applied to determine the impacts of clay content, moisture content, density of soils and driving velocity on the driving resistance and subsidence depth. The modeling results indicated that the driving resistance was positively associated with clay content and moisture content of soils, but negatively associated with soil density and driving velocity. The contribution rates of the factors to the driving resistance from high to low followed the order as soil moisture content, driving velocity, soil density, and soil density combined with soil clay content. The subsidence depth increased with greater soil moisture content but decreased with higher soil clay content, soil density, and driving velocity. The contribution rates of the variables to subsidence depth were ordered as soil moisture content, soil density, soil clay content, clay content combined with moisture content, clay content combined with driving velocity, and moisture content combined with driving velocity. Overall, this study quantifies the relationships among soil clay content, soil moisture content, soil density, driving velocity and driving resistance, subsidence depth of a tracked tractor using the modeling approach; and according to the soil clay content and density, the model can be used to optimize the soil moisture content and driving velocity when the driving resistance is minimum.