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1.
Effects of carboxymethyl-chitosan with different molecular weights on wound healing were investigated in vivo and in vitro.A second degree burn model was performed in rats and the accelerative effects of carboxymethyl-chitosan on wound repair were observed.Contents of transforming growth factor(TGF)-β1,interleukin(IL)-6 and matrix metalloproteinase(MMP)-1 in wounds were determined by enzyme-linked immunosorbent assay(ELISA).In vitro study evaluated the influence of carboxy-methyl-chitosan on cytokines secretion of fibroblasts and macrophages.In vivo results showed that carboxymethyl-chitosan effec-tively accelerated the wound healing process in burned rats(P<0.05).Levels of TGF-β1,IL-6 and MMP-1 in carboxymethyl-chitosan groups were significantly elevated,compared with control group(P<0.05).In vitro results indicated that carboxymethyl-chitosan significantly promoted the proliferation of fibroblasts and stimulated its IL-8 and IL-10 secretion at different incubation time,but it did not affect collagen secretion of fibroblasts.Carboxymethyl-chitosan enhanced phagocytosis ability of macrophages,and in-creased its tumor necrosis factor(TNF)-α secretion.In conclusion,carboxymethyl-chitosan promoted wound healing by activating macrophages,accelerating fibroblasts growth and exerting considerable effects on the secretion of a series of cytokines.  相似文献   

2.
Atlantic salmon Salmo salar were reared at four stocking densities—high density D 1(final density ~39 kg/m 3), medium densities D 2(~29 kg/m 3) and D 3(~19 kg/m 3), and low density D 4(~12 kg/m 3)—for 40 days to investigate the effect of stocking density on their growth performance, body composition and energy budgets. Stocking density did not significantly affect specific growth rate in terms of weight(SGR w) but did affect specific growth rate in terms of energy(SGR e). Stocking density significantly influenced the ration level(RL w and RL e), feed conversion ratio(FCR w and FCR e) and apparent digestibility rate(ADR). Ration level and FCR w tended to increase with increasing density. Fish at the highest density D 1 and lowest density D 4 showed lower FCR e and higher ADR than at medium densities. Stocking density significantly affected protein and energy contents of the body but did not affect its moisture, lipid, or ash contents. The expenditure of energy for metabolism in the low-density and high-density groups was lower than that in the medium-density groups. Stocking density affected energy utilization from the feces but had no effect on excretion rate. The greater energy allocation to growth at high density and low density may be attributed to reduced metabolic rate and increased apparent digestibility rate. These findings provide information that will assist selection of suitable stocking densities in the Atlantic-salmon-farming industry.  相似文献   

3.
The objective of this study was to examine the effect of benzo[a]pyrene(Ba P) on the detoxification and antioxidant systems of two microalgae,Isochrysis zhanjiangensis and Platymonas subcordiformis.In our study,these two algae were exposed to Ba P for 4 days at three different concentrations including 0.5 μg~(L-1)(low),3 μg~(L-1)(mid) and 18 μg~(L-1)(high).The activity of detoxification enzymes,ethoxyresorufin O-deethylase(EROD) and glutathione S-transferase(GST) increased in P.subcordiformis in all Ba P-treated groups.In I.zhanjiangensis,the activity of these two enzymes increased at the beginning of exposure,and then decreased in the groups treated with mid-and high Ba P.The activity of antioxidant enzyme superoxide dismutase(SOD) increased in I.zhanjiangensis in all Ba P-treated groups,and then decreased in high Ba P-treated group,while no significant change was observed in P.subcordiformis.The activity of antioxidant enzyme catalase(CAT) increased in I.zhanjiangensis and P.subcordiformis in all Ba Ptreated groups.The content of malondialdehyde(MDA) in Isochrysis zhanjiangensis increased first,and then decreased in high Ba P-treated group,while no change occurred in P.subcordiformis.These results demonstrated that Ba P significantly influenced the activity of detoxifying and antioxidant enzymes in microalgae.The metabolic related enzymes(EROD,GST and CAT) may serve as sensitive biomarkers of measuring the contamination level of Ba P in marine water.  相似文献   

4.
Based on SPOT5 satellite remote sensing images and land use data in five time phases covering the period 1988–2012, the distribution characteristics, spatial differentiation processes, and driving mechanisms affecting the residential land of the Jinshitan Tourist Resort were studied. The work included a combination of GIS technology, adoption of the differentiation index D, and the multi-group differentiation-measure model D(m). The results provided a basis for the following conclusions: 1) From 1988 to 2012, the degree of differentiation of the rural residential land first decreased, and then increased. The general residential, commercial residential and garden-house land-types all showed declining trends, of which the garden-house type presented the most intense volatility. 2) The overall background of the traditional residential land type was gradually replaced by a new residential land type, and the total area of residential land increased year by year, significantly improving the overall residential conditions. The areas of the new residential land type showed growth, and were increasingly widely distributed in the coastal tourist resorts, transportation corridors, and scenic areas. 3) Government policy, social differentiation, market mechanisms, and individual choices(along with other factors) were mutually promoted, although still restrained. However, all of these factors interacted to constrain the developmental direction and the processes affecting tourism real estate in the Dalian Jinshitan Tourist Resort.  相似文献   

5.
The vortex-induced vibration of two identical rigidly mounted risers in a parallel arrangement was studied using Ansys-CFX and model tests.The vortex shedding and force were recorded to determine the effect of spacing on the two-degree-of-freedom oscillation of the risers.CFX was used to study the single riser and two parallel risers in 2–8D spacing considering the coupling effect.Because of the limited width of water channel,only three different riser spacings,2D,3D,and 4D,were tested to validate the characteristics of the two parallel risers by comparing to the numerical simulation.The results indicate that the lift force changes significantly with the increase in spacing,and in the case of 3D spacing,the lift force of the two parallel risers reaches the maximum.The vortex shedding of the risers in 3D spacing shows that a variable velocity field with the same frequency as the vortex shedding is generated in the overlapped area,thus equalizing the period of drag force to that of lift force.It can be concluded that the interaction between the two parallel risers is significant when the risers are brought to a small distance between them because the trajectory of riser changes from oval to curve 8 as the spacing is increased.The phase difference of lift force between the two risers is also different as the spacing changes.  相似文献   

6.
Uniconazole, as a plant growth retardant, can enhance stress tolerance in plants, possibly because of improved antioxidation defense mechanisms with higher activities of superoxide dismutase(SOD) and peroxidase(POD) enzymes that retard lipid peroxidation and membrane deterioration. These years much attention has been focused on the responses of antioxidant system in plants to uniconazole stress, but such studies on aquatic organism are very few. Moreover, no information is available on growth and antioxidant response in marine microalgae to uniconazole. In this paper, the growth and antioxidant responses of two marine microalgal species, Platymonas helgolandica and Pavlova viridis, at six uniconazole concentrations(0-15 mg L-1) were investigated. The results demonstrated that 3 mg L-1 uniconazole could increase significantly chlorophyll a and carbohydrate contents of P. helgolandica(P 0.05). Higher concentrations(≥12 mg L-1) of uniconazole could inhibit significantly the growth, dry weight, chlorophyll-a and carbohydrate contents of P. helgolandica and P. viridis(P 0.05). Uniconazole caused a significant increase in lipid peroxidation production(MDA) at higher concentrations(≥ 9 mg L-1). The activities of antioxidant enzymes, superoxide dismutase(SOD) and catalase(CAT) were enhanced remarkably at low concentrations of uniconazole. However, significant reduction of SOD and CAT activities was observed at higher concentrations of uniconazole.  相似文献   

7.
The dinoflagellate Prorocentrum minimum, one of the most widespread red tide causing species, affects marine aquaculture and ecosystems worldwide. In this study, ridgetail white prawn Exopalaemon carinicauda were exposed to P. minimum cells (5 × 104 cells mL?1) to investigate its harmful effects on the shrimp. Antioxidant activities and histological changes were used as indicators of health status of the shrimp. In 72 hours, the mortality of E. carinicauda was not affected, but its antioxidant response and histology were statistically different from those of control. Elevated superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and depressed catalase (CAT) activity were observed in gill; while increased SOD, glutathione S-transferase (GST), CAT activities and modulated GPX activity were observed in hepatopancreas. Thus, antioxidant activities in gill and hepatopancreas seem to respond differentially to harmful alga exposure. Increased malondialdehyde (MDA) content in early a few hours indicates the damage of the antioxidant defense system. Although MDA content recovered to a low level thereafter, a series of histological abnormalities including accumulation or infiltration of hemocytes, tissue lesions and necrosis were discovered in gill and hepatopancreas. Exposure to P. minimum induced sublethal effects on E. carinicauda, including temporary oxidative damage and histological injury.  相似文献   

8.
Oyster extract is an effective bioactivity component. It has abundant nutritional value and antiviral, antitumor and immune defense functions. The role of oyster extract in treating liver injury has been paid more attention. We use Wistar rats to make alcoholic liver disease model through injecting alcohol into rats' stomachs. These rats were randomly divided into five groups: model group, control group, low-dose, middle-dose and high-dose experimental group with a dose of 0.12 g kg-1, 0.40 g kg-1, and 1.20 g kg-1 alcoholic. After nine weeks, serum biomarkers(ALT, AST, TG and TCHO), malondialdehyde(MDA), glutathione(GSH), C3a, C5a, IL-17, TNF-ɑ, anti-MAA-HAS IgG, CD3+, CD4+, CD8+, NK cell activation and zinc content were assessed. The results showed that the serum biomarkers(ALT, AST, TG and TCHO), MDA content, anti-MAA-HSA IgG, serum C3a, C5a IL-17 and TNF-ɑ levels of oyster extract treatment groups were significantly decreased in comparison with model group. On the contrary, GSH showed adverse trend. Serum CD3+, CD4+ and NK cell activation were significantly increased in middle-dose group and high-dose group compared with model group, and there was decrease of CD8+ activity in high-dose group. Plasma Zn level was decreased in model group compared with that in control group. Meanwhile, Mean plasma Zn levels increased dramatically following the dose increase of a given oyster extract.  相似文献   

9.
A study on the nonspecific immunity of Litopenaeus vannamei ever inhabiting freshwater and seawater was carried out at different molt stages by comparing their total hemocyte count(THC) and respiratory burst(RB) and activity of phenol oxidase(PO), nitric oxide synthase(NOS) and lysozyme(LY). Two-way ANOVA showed that salinity and molt stage independently affected THC and RB and the activity of PO, NOS and LY of juvenile L. vannamei significantly(P 0.05). The THC and RB and the activity of NOS gradually increased from the post-molt stages(A and B) to the pre-molt stages(D0–D3), which were common in shrimps inhabiting freshwater and seawater. The activity of PO peaked at the inter-molt stage(C), and touched the lowest at the post-molt stage in freshwater and pre-molt stage in seawater. The activity of LY was stable over the molt cycle. The RB and the activity of PO, NOS and LY of juvenile L. vannamei were significantly lower in freshwater than in seawater; whereas THC was significantly higher in freshwater than in seawater(P 0.05). It was concluded that the post-molt stage(especially stage A) was critical to shrimp culture, which should be intensively attended when L. vannamei was cultured in freshwater.  相似文献   

10.
The antioxidant enzyme activity and malondialdehyde (MDA) content of Cephalothrix hongkongiensis were studied to assess variations in the biochemical/physiological parameters of nemerteans under heavy metal stress. Worms were exposed to copper, zinc and cadmium solutions at different concentrations, and the activity of three antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX), and MDA content were measured. The results show that the activity of each enzyme changed immediately after exposure to heavy metals. CAT was invariably inhibited throughout the experimental period, while the SOD activity was significantly elevated by exposure to Cu2+ for 48 h, but then decreased. SOD was inhibited by Zn2+during the first 12 h of exposure, but activated when exposed for longer periods. Under Cd2+ stress, SOD activity decreased within 72 h. GPX activity varied greatly, being significantly increased by both Cu2+ and Zn2+, but significantly inhibited by Cd2+ in the first 12–24 h after exposure. MDA content increased on Cu2+ exposure, but normally decreased on Zn2+ exposure. MDA content followed an increase-decrease-increase pattern under Cd2+ stress. In conclusion, the antioxidant system of this nemertean is sensitive to heavy metals, and its CAT activity may be a potential biomarker for monitoring heavy metal levels in the environment.  相似文献   

11.
It is difficult to scale up measurements of the sap flux density (Js) for the characterization of tree or stand transpiration (E) due to spatial variations in JS and their temporal changes. To assess spatial variations in the sap flux density of Korean pine (Pinus koraiensis) and their effects on E estimates, we measured the Js using Granier-type sensors. Within trees, the Js decreased exponentially with the radial depth, and the Js of the east aspects were higher than those of the west aspects. Among trees, there was a positive relationship between Js and the tree diameter at breast height, and this positive relationship became stronger as the transpiration demand increased. The spatial variations that caused large errors in E estimates (i.e., up to 110.8 % when radial variation was ignored) had varied systematically with environmental factors systematic characteristics in relation to environmental factors. However, changes in these variations did not generate substantial errors in the E estimates. For our study periods, the differences in the daily E (E D) calculated by ignoring radial, azimuthal and tree-to-tree variations and the measured E D were fairly constant, especially when the daily vapor pressure deficit (D_D) was higher than 0.6 kPa. These results imply that the effect of spatial variations changes on sap flow can be a minor source of error compared with spatial variations (radial, azimuthal and tree-to-tree variations) when considering E estimates.  相似文献   

12.
Cadmium flux through a lab food chain (Phaeodactylum tricornutum Bohlin- Penaeus orientate Kishinouye- Hexagrammos otakii Jordan et Starks) and its genotoxicity were investigated. The results are as follows:1. High doses of cadmium (>0.003 mol / L) induced flocculation and quick precipitation of Phaeodactylum tricornutum; lower doses of cadmium could be adsorbed on and absorbed by P. tricornutum without delaying its growth. Cadmium concentrations in algae increased with dosage, and cadmium ions removed from the medium were in proportion to dosage. In vivo chelation and organizable combination of absorbed cadmium ions by metabolites of P. tricornutum can be considered as bio-detoxification.2. Cadmium concentration decreased in the transfers from P. tricornutum to P. orientalis and from the latter to H. otakii. Transfer coefficient of cadmium in the first flux was 66.6% and 29.9% in the second. Results of t tests showed that mutagenicity of ashed internal organs of experimental prawns was significantly hi  相似文献   

13.
Temporal variations in multimodal structures of diurnal (D 1) and semidiurnal (D 2) internal tides were investigated on the continental slope of the Dongsha Plateau, based on 2-month moored acoustic Doppler current profiler observations. Harmonic analysis indicated that the D 1 components (K 1 and O 1) dominated the internal tide field. The vertical structure of the K 1 constituent presented a first-mode structure while the M 2 constituent seemed to exhibit a high-mode structure. Amplitude spectra analysis of the current data revealed differences in baroclinic current amplitudes between different water depths. Temporal variations in modal structures ware analyzed, based on the D 1 and D 2 baroclinic tides extracted from the baroclinic velocity field with band-pass filters. Analysis showed that the magnitude of the D 1 internal tide current was much larger than the D 2 current, and temporal variations in the modal structure of the D 1 internal tide occurred on an approximately fortnightly cycle. The EOF analyses revealed temporal transformation of multimodal structures for D 1 and D 2 internal tides. The enhancement of the D 1 internal tide was mainly due to the superposition of K 1 and O 1, according to the temporal variation of coherent kinetic energy.  相似文献   

14.
In this study, we examined the effect of elevated temperature on the expression patterns of genes, i.e., nacrein, irr, n16, n19, and hsp70 in the pearl oyster Pinctada fucata. The experiment was carried out at 4 temperatures, i.e., 20℃(ambient, control), 24, 28℃, and 32℃. The expression levels of target genes in P. fucata were assayed at 0, 6, 24, 48, and 96 h via real-time polymerase chain reaction. Results showed that the expression levels of nacrein and irr had no significant variations among different time points below 28℃, but significantly increased over time at 32℃. The expression levels of n16 and n19 did not change markedly at 20℃. The former increased significantly at 6 h and 24 h while the latter substantially decreased during 6–96 h at 24, 28 and 32℃. Among different temperatures, the level of n16 was significantly lower at 20℃ than at other temperatures during 6–96 h, and the level of n19 significantly varied among different temperatures at 48 h and 96 h. The expression level of hsp70 was significantly higher at 32℃ than at 20, 24 and 28℃ at 24 h. These results demonstrated that elevated temperature impacted the physiological processes of P. fucata and potentially influenced its adaptability to thermal stress.  相似文献   

15.
Different amounts of vitamin C were added to diets fed to juveniles(2.5 ± 0.15 g) of sea cucumber Apostichopus japonic u s(Selenka) in an attempt to reduce the stress response of specimens exposed to nitrite stress. A commercial feed was used as the control diet and three experimental diets were made by supplementing 1 000, 1 500, or 2 000 mg vitamin C/kg diet to control diet separately in a 45-day experiment. Sea cucumbers were exposed to three different levels(0.5, 1.0, and 1.5 mg/L) of nitrite stress for 4, 8, and 12 h at four time intervals(0, 15, 30, and 45 d). Growth of the animals was recorded during the experiment. Reactive oxygen species(ROS)(i.e. hydroxyl free radical(-OH), malondialdehyde(MDA) and total antioxidant capacity(T-AOC)) and antioxidant enzyme activities(i.e., superoxide dismutase(SOD) and catalase(CAT)) were measured. Response surface methodology(RSM) was used to analyze the effect of multiple factors on ROS indices and enzyme activities. Weight gain(WG) and special growth rate(SGR) of vitamin C supplementation groups were significantly higher than those of control group( P 0.05). The levels of-OH and MDA increased under exposure time extending and nitrite concentration increasing, whereas T-AOC level decreased. SOD and CAT activities increased at 4 h and 8 h and decreased at 12 h. During the days in which the animal consumed experimental diets, the levels of-OH and MDA decreased and that of T-AOC increased. This result suggests that diets containing vitamin C could reduce the nitrite stress response in the animals and increase their antioxidant capacity. The multifactor regression equation of growth performance, ROS indices, and duration of feeding results suggest that vitamin C supplementation of 1 400–2 000 mg/kg diet for 29–35 days could reduce effectively the effects of nitrite exposure.  相似文献   

16.
Nitrogen (N) and phosphorus (P) are limited nutrients in terrestrial ecosystems, and their limitation patterns are being changed by the increase in N deposition. However, little information concerns the plant growth and the soil biological responses to N and P additions among different soils simultaneously, and these responses may contribute to understand plant-soil interaction and predict plant performance under global change. Thus, this study aimed to explore how N and P limitation changes in different soil types, and reveal the relationship between plant and soil biological responses to nutrient additions. We planted Dodonaea viscosa, a globally distributed species in three soil types (Lixisols, Regosols and Luvisols) in Yuanmou dry-hot valley in Southwest China and fertilized them factorially with N and P. The growth and biomass characters of D. viscosa, soil organic matter, available N, P contents and soil carbon (C), N, P-related enzyme activities were quantified. N addition promoted the growth and leaf N concentration of D. viscosa in Lixisols; N limitation in Lixisols was demonstrated by lower soil available N with higher urease activity. P addition promoted the growth and leaf P concentration of D. viscosa in Luvisols; severe P limitation in Luvisols was demonstrated by a higher soil available N: P ratio with higher phosphatase activity. Urease activity was negatively correlated with soil available N in Nlimited Lixisols, and phosphatase activity was negatively correlated with soil available P in P-limited Luvisols. Besides, the aboveground biomass and leaf N concentration of D. viscosa were positively correlated with soil available N in Lixisols, but the aboveground biomass was negatively correlated with soil available P. Our results show similar nutrient limitation patterns between plant and soil microorganism in the condition of enough C, and the nutrient limitations differ across soil types. With the continued N deposition, N limitation of the Lixisols in dry hot valleys is expected to be alleviated, while P limitation of the Luvisols in the mountaintop may be worse in the future, which should be considered when restoring vegetation.  相似文献   

17.
A herringbone water-sediment separation structure(hereinafter referred to as "herringbone structure") has been shown to be effective in separating coarse inorganic debris; however, less is known regarding the large wood(LW) filtration effect in this structure. This paper presents preliminary research on the wood filtration effect of the herringbone structure based on physical model tests.The results show that the herringbone structure exhibited effective performance in large wood size segregation, with a 100% component filtration rate for LW that diameter(D) larger than ribbed beam opening width(a). The total filtration rate also exceeded 80% when the Fraud number(Fr) is larger than 2.64 and increased with the increase of Fr. After exceeding Frmax, total filtration rate would be decreased due to overflow. Beside flow condition,structure parameters influence significantly on LW filtration rate. We attempt to explain the filtration process via particle contact trajectory and particle movement trajectory. The inclined angle of ribbed beam(γ) contributed the most variation to the filtration rate via influencing the coincidence with particle contact trajectory and particle movement trajectory. The high sensitivity coefficient of ribbed beam(θ) under relatively low Fr conditions implies remarkable influences on LW filtration effects by causing clogging problem. The ribbed beam opening width(a) together with LW diameter(D) influenced the size segregation performance.  相似文献   

18.
Excessive alcohol consumption leads to liver disease. Extensive evidence suggests that C-phycocyanin (C-PC), a chromophore phycocyanobilin derived from Spirulina platensis, exerts protective effects against chemical-induced organ damage. In this study, we investigated whether C-PC could protect against ethanol-induced acute liver injury. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (CHOL), low-density lipoprotein (LDL), liver homogenate malondialdehyde (MDA), superoxide dismutase (SOD) content were measured, and pathological examination of liver sections were examined. C-PC showed obvious inhibitory effects on serum ALT, AST, TG, CHOL, LDL and MDA, and SOD content significantly increased in the liver. The structure of hepatic lobules was clear, liver sinus returned to normal, and liver cell cords were arranged in neat rows. Cloudiness, swelling, inflammatory cell infiltration and spotty necrosis of liver cells were significantly reduced. Therefore, C-PC can significantly protect against ethanol-induced acute liver injury.  相似文献   

19.
We measured the concentrations and distribution of major polyamines(spermine, putrescine and spermidine) in seawater during successive spring algal blooms in an area of frequent harmful blooms in the East China Sea. Spermine, putrescine, and spermidine concentrations were analyzed by high performance liquid chromatography and ranged from 1–64, 7–81, and 0–19 nmol/L. Spermine was present at the highest concentrations, followed by putrescine and spermidine. In late April, when a diatom bloom dominated by Skeletonema costatum dispersed, polyamine concentrations increased, presumably as a result of diatom decomposition. In early May, when a dinoflagellate bloom dominated by Prorocentrum donghaiense occurred, the polyamine concentration decreased from the level seen in late April. The abundant polyamines that decomposed and were released during the diatom bloom in late April may have promoted the growth of P. donghaiense, resulting in its dominance.  相似文献   

20.
By using field survey data from the sixth forest inventory of Jiangxi Province in 2003, the biomass and carbon storage for three studied species (Pinus massoniana, Cunninghamia lanceolata, and Pinus elliottii) were estimated in Taihe and Xingguo counties of Boyang Lake Basin, Jiangxi Province, China. The relationship between carbon density and forest age was analyzed by logistic equations. Spatio-temporal dynamics of forest biomass and carbon storage in 1985-2003 were also described. The results show that total stand area of the three forest species was 3.10 × 10^5 ha, total biomass 22.20 Tg, vegetation carbon storage 13.07 Tg C, and average carbon density 42.36 Mg C/ha in the study area in 2003. Carbon storage by forest type in descending order was: P. massoniana, C. lanceolata and P. elliottii. Carbon storage by forest age group in descending order was: middle stand, young stand, near-mature stand and mature stand. Carbon storage by plantation forests was 1.89 times higher than that by natural forests. Carbon density of the three species increased 8.58 Mg C/ha during the study period. The carbon density of Taihe County was higher in the east and west, and lower in the middle. The carbon density of Xingguo County was higher in the northeast and lower in the middle. In general, the carbon density increased with altitude and gradient. Afforestation projects contribute significantly to increasing stand area and carbon storage. Appropriate forest management may improve the carbon sequestration capacity of forest ecosystems.  相似文献   

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