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231.
Fuyong Wu Feifei Xu Xiaona Ma Wanqing Luo Laiqing Lou Ming Hung Wong 《Journal of Soils and Sediments》2018,18(11):3177-3185
Purpose
Although arsenic (As) hyperaccumulation is a constitutive property for Pteris vittata, there is intraspecific variation in As accumulation among metallicolous (from As-contaminated soils) and nonmetallicolous populations (from uncontaminated soils) and the related mechanisms is still not clear.Materials and methods
Pot trials, hydroponic culture, and manual simulation were conducted to investigate the roles of arsenate reductase and root exudates in accumulating As in P. vittata, which were collected from two uncontaminated sites including Sun Yat-sen University campus, Guangdong Province (ZD), and a botanical garden in Guangxi Academy of Forestry Sciences, Nanning City, Guangxi Province (NN), and two As and Pb/Zn mining and/or smelting sites located in Shaoguan of Guangdong Province (SG) and Guiyang of Hunan Province (GY).Results and discussion
The nonmetallicolous populations (ZD and NN) possessed more efficient uptake of arsenate and arsenite than the metallicolous populations (SG and GY). There were significant (p?<?0.05) difference in arsenate reductase activities in roots among the four populations of P. vittata and that the higher arsenate reductase activities were recorded in the nonmetallicolous populations (110 nkat mg?1 protein for ZD, 160 nkat mg?1 protein for NN) compared with the metallicolous populations (62.9 nkat mg?1 protein for SG, 78.1 nkat mg?1 protein for GY). Root exudates from the nonmetallicolous population (NN) and the metallicolous population (GY) of P. vittata contained similar compositions of organic acids including oxalic, malic, and succinic acids, of which oxalate were dominant (>?67%). The NN population exuded 4.23 times more oxalate than the SG population. Root exudates from the NN population mobilized significantly (p?<?0.05) more As from As-contaminated soils than those from the SG population, of which oxalate had the most effective in As mobilization.Conclusions
The present study suggests that higher arsenate reductase activities and oxalate exudation in the nonmetallicolous populations may play an important role in increasing their efficiency in phytoremediation of As-contaminated soils.232.
Temperature,density and ammonia effects on growth and fecundity of the ramshorn snail (Helisoma anceps) 下载免费PDF全文
Tien‐Chieh Hung Troy Stevenson Marade Sandford Tewdros Ghebremariam 《Aquaculture Research》2018,49(2):1072-1079
Ramshorn snail (Helisoma anceps) is a freshwater gastropod found all over North America and is also an essential component to the larval and juvenile culture of endangered Delta Smelt (Hypomesus transpacificus) at the UC Davis Fish Conservation and Culture Lab (FCCL). H. anceps has been proven effective in cleaning the excess algae while not harming the larvae. A challenge at the FCCL has been having a reliable source of these snails, since previously it has been dependent upon nature and never guaranteed there would be enough to meet the needs of the FCCL. Experiments were conducted to assess the effects of temperature, food types, rearing density and total ammonia nitrogen (TAN) concentrations. Procedures recommended to increase snail fecundity for the FCCL are to rear spawning parent snails and the resultant eggs at a high temperature (16–20°C) and with a low TAN concentration (0–5 mg/L). Newly hatched snails need to be cultured at a low density (about one snail/20 cm2). After the snails grow to an acceptable size (1.3 cm diameter), they could be set aside and cultured in an environment with less optimal water quality parameters such as a high TAN level (as high as 20 mg/L) and low temperature (12°C) for quantity control prior to use. 相似文献
233.
The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is considered a major pest for crucifers in Malaysia. New control materials are constantly required as P. xylostella population develops resistance to most of the insecticides used against them. In this study, vinegar derived from Azadirachta excelsa (Jack) Jacobs was evaluated against the third-instar larvae of P. xylostella and an appropriate application dose required to control the pest was determined in the laboratory trial. Results indicated A. excelsa vinegar to be a useful control measure, significantly reducing P. xylostella leaf consumption and adult size of P. xylostella. Interestingly, mortality rate of larval, pupae and adult was significantly increased by the application of A. excelsa vinegar. An in-diet EC50 of 80× against larvae was achieved, whilst obvious defects in adult moth were also recorded. The results indicate that A. excelsa vinegar exhibits potential to be used against P. xylostella. 相似文献
234.
Nguyen Van Hung Peter Bossier Nguyen Thi X. Hong Christine Ludeseve Linsey Garcia‐Gonzalez Nancy Nevejan Peter De Schryver 《Journal of fish diseases》2019,42(6):777-787
The natural amorphous polymer poly‐β‐hydroxybutyrate (PHB‐A: lyophilized Ralstonia eutropha containing 75% PHB) was used as a biological agent to control bacterial pathogens of blue mussel (Mytilus edulis) larvae. The larvae were supplied with PHB‐A at a concentration of 1 or 10 mg/L for 6 or 24 hr, followed by exposure to either the rifampicin‐resistant pathogen Vibrio splendidus or Vibrio coralliilyticus at a concentration of 105 CFU/ml. Larvae pretreated 6 hr with PHB‐A (1 mg/L) survived a Vibrio challenge better relative to 24 hr pretreatment. After 96 hr of pathogen exposure, the survival of PHB‐A‐treated mussel larvae was 1.41‐ and 1.76‐fold higher than the non‐treated larvae when challenged with V. splendidus and V. coralliilyticus, respectively. Growth inhibition of the two pathogens at four concentrations of the monomer β‐HB (1, 5, 25 and 125 mM) was tested in vitro in LB35 medium, buffered at two different pH values (pH 7 and pH 8). The highest concentration of 125 mM significantly inhibited the pathogen growth in comparison to the lower levels. The effect of β‐HB on the production of virulence factors in the tested pathogenic Vibrios revealed a variable pattern of responses. 相似文献
235.
236.
The aims of this study were to evaluate the probiotic efficiency of Bacillus subtilis E20 (109 colony‐forming units kg?1) on the growth and apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein (CP), amino acids (AAs), and crude lipids (CLs) of the white shrimp, Litopenaeus vannamei. A control diet without probiotic supplementation was used. Shrimp exhibited significant increases in growth performance and feed utilization after being fed the test diet for 56 days. Shrimp were then used to evaluate the apparent nutrient digestibility using 0.1% Cr2O3 in the diet as an indicator. During the trial, faeces was collected from triplicate groups of shrimp twice daily. ADCs of CP and DM in the test diet significantly increased compared to those of the control diet. Although the ADCs of CLs did not significantly differ between the control and probiotic group, the ADC of CLs was higher in the probiotic group than in the control group. In addition, ADCs of most AAs in the test diet were significantly higher compared to those of the control diet. These results suggest that shrimp in the test group had significantly better growth performance, which was due to increases in nutrient digestibility and absorption. 相似文献
237.
This study investigated the effects of coconut oil as a dietary supplement on the growth, lipid metabolism and related gene expressions of juvenile orange‐spotted grouper Epinephelus coioides. Coconut oil at concentrations of 0, 10, 30 and 50 g/kg was used to replace dietary lipids in a basal diet containing 150 g/kg lipids. The four experimental diets were, respectively, fed to triplicate groups of juvenile groupers (initial weight: 8.53 ± 0.13 g) in a recirculating system for 8 weeks. Fish fed the diet containing 50 g/kg coconut oil exhibited lower (p < .05) weight gain than did fish fed the diet containing 30 g/kg coconut oil; however, no significant differences in weight gain were observed between fish fed diets containing 0 and 10 g/kg coconut oil. Hepatic carnitine palmitoyltransferase‐1, fatty acid synthase, fatty acid elongase, fatty acid desaturase and peroxisome proliferator‐activated receptor gamma gene expressions were all the highest in fish fed the diet containing 10 g/kg coconut oil. Fish fed the coconut oil‐free basal diet demonstrated upregulated gene expression of neuropeptide Y. The results suggest that dietary supplementation with 10 g/kg coconut oil exerted beneficial effects on lipid metabolism by E. coioides. 相似文献
238.
Luis Fernando Aranguren Caro Hung N. Mai Linda Nunan Joshua Lin Brenda Noble Arun K. Dhar 《Journal of fish diseases》2020,43(4):403-411
White spot syndrome virus has been a threat to the global shrimp industry since it was discovered in Taiwan in 1992. Thus, shrimp-producing countries have launched regulations to prevent import of WSSV-infected commodity shrimp from endemic areas. Recently, cooked shrimp that is infected with WSSV tested positive by PCR. However, there is no study to determine the infectivity of WSSV in cooked shrimp that tested positive by PCR. In the present study, WSSV-infected shrimp were cooked at boiling temperature for different times including 0, 1, 3, 5, 10 and 30 min. Upon exposure to boiling temperature, WSSV-infected shrimp were fed to SPF shrimp (Litopenaeus vannamei). The result showed experimentally challenged shrimp from 0-min treatment (positive control) indeed got infected with WSSV. However, experimentally challenged shrimp that were fed tissues boiled at 1, 3, 5, 10 and 30 min were not infected with WSSV. Mortality data showed that only the positive control (0-min) treatment displayed high mortality, whereas no mortality was observed in any other treatment category. These findings suggest that cooking shrimp at boiling temperature for at least 1 min might prevent any potential spread of WSSV from endemic countries to other geographical areas where WSSV has not yet been reported. 相似文献
239.
Kakuta Yoshii Fumiaki Takakuwa Hung Phuc Nguyen Toshiro Masumoto Haruhisa Fukada 《Fisheries Science》2010,76(1):139-145
A growth trial was conducted to evaluate the effect of dietary lipid level on juvenile kelp grouper Epinephelus bruneus. Juvenile kelp grouper were fed isonitrogenous diets (470 g/kg crude protein) with four levels of crude lipid at 60 g/kg (CL60), 130 g/kg (CL130), 210 g/kg (CL210), and 270 g/kg (CL270) for 56 days. The highest growth performance and feed utilization were found in the CL130 diet group. A high dietary lipid level (CL270 diet) significantly decreased growth performance and feed utilization. A significant difference in apparent digestibility was only observed in protein, which was highest in the CL130 diet groups. The highest retention for protein, energy, and lipid was found in the CL130 diet group. The dietary lipid levels significantly changed whole-body and liver compositions, the highest being the CL60 diet group for crude protein level and the CL210 diet group for crude lipid level. Based on a second-order polynomial regression analysis of crude lipid level against specific growth rate and protein efficiency ratio, the optimum dietary lipid level for kelp grouper was estimated to be 152 and 154 g/kg diet, respectively. 相似文献
240.
This study aimed to determine whether dietary carotenoid (CD) supplements could affect the antioxidant capacity of characins Hyphessobrycon callistus upon hypoxia stress at live transportation. Two types of CD [astaxanthin (AX), β‐carotene (BC)] and their 1:1 combination (MX) at three concentrations (10, 20 and 40 mg kg?1) were supplemented, resulting in nine CD diets. After 8 weeks' rearing, the resulting fish were divided into two subgroups and exposed to hypoxia or normoxia. Hypoxia involved a gradual decrease in dissolved oxygen (DO) from 6.5 to <1.0 mg L?1. Normoxia was DO kept in saturation. Hypoxia led to an increase in the total antioxidant status (TAS), superoxide dismutase (SOD), glutathione peroxidases (GPx) and aspartate aminotransferase (AST) activity of blood serum in fish, but had no effect on alanine aminotransferase (ALT). Under hypoxia, fish fed CD diets had lower SOD, GPx and ALT activity than control fish, showing that dietary CD could increase the antioxidant capacity and protection of the liver. Dietary AX was more effective for antioxidant capacity than BC and MX when under hypoxia stress, because GPx, ALT and AST were lower in AX‐fed fish. Except TAS, the other four enzyme activities showed decreasing trends with increasing dietary CD concentrations. 相似文献