Biofloc technology is considered as a method that degrades organic waste by microorganisms and produces microbial flocs. A 30-day experiment was performed to investigate the effects of partial replacement of daily feeding intake with biofloc on the growth performances, digestive enzymes activity and liver histology of the common carp Cyprinus carpio L. fingerlings. Two hundred and eight healthy fingerlings (58.6 ± 0.2 g) were randomly distributed in 12 tanks (30 L) at a density of 25.4 kg m?3 and fed experimental treatments (100 % daily feeding rate as a control, biofloc + 75 % daily feeding rate, biofloc + 50 % daily feeding rate, biofloc + 25 % daily feeding rate). At the end of experiment, the results indicated that the highest weight gain was observed in the fish fed BFT 75 % and control which differed significantly from those fed BFT 25 % (P < 0.05). Diet BFT 75 % improved total protease and pepsin activity compared with BFT 25 and 50 % (P > 0.05). No significant difference was observed in case of lipase, amylase and alkaline phosphatase activity between the treatments. In the liver, histological alterations were found in the treatments, and feeding the fish with BFT 75 % significantly improved hepatocellular quantification and qualification than the other groups. The results obtained in this experiment suggest that the biofloc improves growth performances, digestive enzyme activity and liver condition of the common carp fingerlings when 25 % of daily feeding rate (BFT 75 %) was replaced with one carbohydrate such as molasses in zero-water exchange system. 相似文献
The effectiveness of common carp pituitary extract (CPE), luteinizing hormone releasing hormone analogue (LHRH‐A2) injections and LHRH‐A2 implants for spawning induction in female sturgeon, Huso huso was examined. In the first trial, fish were injected with 7% physiological saline (control), 50 mg kg?1 CPE or LHRH‐A2 at 3.5, 7, 8 or 10 μg kg?1. In the second trial, fish were treated with LHRH‐A2 cholesterol pellet implants containing 0, 3.5, 7, 8 and 10 μg kg?1 LHRH‐A2. Ovulated eggs were removed using a minimally invasive surgical technique and were artificially fertilized. Injection of CPE and LHRH‐A2 at doses of 3.5, 7, 8 and 10 μg kg?1 resulted in the number of ovulated fish more than LHRH‐A2 implants (similar doses) or controls, although there was no significant difference at doses of 8 and 10 μg kg?1 (P ≥ 0.05). The latency period of fish receiving CPE and LHRH‐A2 injections was approximately 20 h, which was significantly lower than in fish receiving LHRH‐A2 implants (P ≤ 0.05). Furthermore, there were no significant differences in rates of fertilization or hatching among the progeny produced in any of the treatment groups (P ≥ 0.05). In conclusion, the data from this study could be useful for artificial propagation of not‐fully‐matured females of H. huso at sturgeon hatcheries. 相似文献
Over the past few decades, the usage of oxytetracycline(OTC), a kind of antibiotic, has increased with the development of aquaculture and livestock breeding. However, about 30–90% of the applied antibiotics are excreted as the parent compounds into the environment, especially with the application of animal manure to agricultural fields. This large influx of antibiotics may lead to the destruction of the natural microbial ecological community and pose great threats to human beings through the food chain. Therefore, the fate and toxicity of OTC in the environment are issues of great concern. Degradation of OTC, including the non-biodegradation and biodegradation, and the biological toxicity of its degradation products or metabolites, are reviewed in this paper. The non-biodegradation pathways include hydroxylation, quinonization, demethylation, decarbonylation, dehydration and secondary alcohol oxidation. Light(particularly UV light), pH and oxidizing substances play important roles in non-biodegradation. Biodegradation products include 4-epi-OTC(EOTC), 2-acetyl-2-decarboxy-amido-OTC(ADOTC), α-apo-OTC and β-apo-OTC. EOTC is an epimer and identied except for the configuration of the C4 dimethylamino group of OTC. Temperature and pH are the main factors affecting biodegradation pathways of OTC. In addition, this review discusses concerns over the biological toxicity of OTC degradation products. 相似文献
In January 2011, symptomatic chickpea and faba bean plants were observed in fields located in the Gezira state (Sudan). Faba bean plants showed yellowing and stunting, whereas chickpea plants presented yellowing, reddening and little leaves. The disease etiology was investigated using nested polymerase chain reaction (PCR) with phytoplasma-specific primers which amplify a fragment of the 16S rRNA gene. Sequencing and restriction fragment length polymorphism (RFLP) analyses revealed that the tested phytoplasmas belonged to the group 16SrII. Phylogenetic analyses of the 16S rRNA gene of the obtained sequences indicated that the chickpea and faba bean phytoplasmas from Sudan were more closely related to the phytoplasmas subgroup 16SrII-D. To our knowledge, this is the first report of phytoplasmas from the group 16SrII-D infecting chickpea in Sudan, and faba bean worldwide. 相似文献
The compositions of essential oils of 19 accessions belonging to six different Achillea species, transferred from the natural habitats in 10 provinces of Iran to the field conditions, were assessed. The relationship between the leaf areas of selected accessions with their essential oil content was also investigated. Essential oil yield of dried plants obtained by hydro-distillation ranged from 0.1 to 2.7% in leaves. Results indicated a significant variation in oil composition among and within species. Total of 94 compounds were identified in 19 accessions belonging to the six species of A. millefolium, A. filipendulina, A. tenuifolia, A. santolina, A. biebersteinii and A. eriophora. The major constituents of the leaves in the tested genotypes were determined as germacrene-D, bicyclogermacrene, camphor, borneol, 1,8-cineole, spathulenol and bornyl acetate. According to the major compounds, four chemotypes were defined as: (I) spathulenol (1.64–34.31%) + camphor (0.2–15.61%) (7 accessions); (II1) germacrene-D (18.78–23.93%) + borneol (7.93–8.26%) + bornyl acetate (11.56–14.66%) (5 accessions); (II2) germacrene-D (13.28–36.28%) + bicyclogermacrene (5.93–8.4%) + 1,8-cineole (15.26–19.41%) + camphor (14.95–23.32%) (2 accessions); (III) borneol + camphor (52.04–63.27) (2 accessions); (IV) germacrene-D (45.86–69.64%) (3 accessions). The relationships of chemotypes with soil type and climatic conditions of collected regions were assessed, as probable reasons of high variations in essential oil components, and discussed. 相似文献
The distribution variability of soil electrical conductivity (EC), pH, clay, sand, CaCO3, organic carbon (OC) and available potassium (K) in the Naqade region was investigated using a geostatistical method and Geographical Information System (GIS) technique. Two hundred and eighty-two topsoil (0–30 cm) samples were randomly collected and analyzed. pH and clay followed a normal distribution, whereas sand EC, CaCO3, OC and K were log-transformed. The highest variation was observed for soil EC, and the lowest for soil pH. In the variography analysis, spherical, exponential and gaussian models were best fit on experimental semivariograms. The minimum effective spatial autocorrelation was 1500 m for OC and the maximum effective spatial autocorrelation was 4000 m for sand and K. Strong spatial correlations were noted with sand and CaCO3 (<25%), whereas values were moderate for clay, EC, OC and K (25–75%). Ordinary kriging was utilized for the interpolation of estimated variable determinations in unsampled sites. It was found that soil properties in this study area were strongly influenced by both environmental and natural factors. The results can be used as a source of information for the development and implementation of any further land management and soil and water conservation plans. 相似文献
Soybean mosaic virus (SMV) is a member of genus Potyvirus, which causes worldwide soybean [Glycine max (L.) Merr.] yield loss and seed quality deterioration. It is of great significance to find new resistance loci and genes for cultivation of soybean variety. In the present study, a recombinant inbred line (RIL) population and a genome-wide association study (GWAS) panel, which contained 193 lines and 379 germplasms, respectively, were used for QTL mapping of resistance to SMV. Linkage mapping identified a major QTL, qSMV13, on chromosome 13, conferring resistance to SMV SC3 and SC7 strains, explaining phenotypic variations 71.21 and 76.59?%, respectively. The QTL qSMV13 was located close to the known SMV resistance loci Rsv1-h. GWAS analysis revealed five single nucleotide polymorphisms (SNPs) significantly associated with resistance to SC3 on chromosomes 2, 11, 13, 14 and 16. One of the SNP markers, ss715614844, was the right flanking marker of qSMV13. Combining linkage mapping and GWAS analysis enabled us to delimit qSMV13 in a 97.2-kb genomic region containing seven genes. A LRR-RLK protein was proposed as the candidate gene of qSMV13. These results provided selection markers and candidate genes for SMV resistance in soybean molecular breeding programs.
1. The objective of this study was to determine the prevalence and antimicrobial resistance of Arcobacter spp. isolated from different species of retail poultry meat in Iran.
2. From August 2012 to April 2013, a total of 540 raw poultry meat samples from chicken (n = 100), turkey (n = 100), quail (n = 100), partridge (n = 80), duck (n = 50), ostrich (n = 60) and geese (n = 50) were purchased from randomly selected retail outlets in Shahrekord, Isfahan, Sari and Rasht, Iran.
3. Using culture techniques, 71 of 540 poultry meat samples (13.1%) were positive for Arcobacter spp. The highest prevalence of Arcobacter spp. was found in chicken meat (28.0%), followed by quail (12.0%), duck (11.4%), turkey (11.0%), geese (8.0%), partridge (7.5%) and ostrich (3.3%) meat. The number of A. butzleri isolated from poultry meat samples (90.1%) was significantly higher than A. cryaerophilus (7.1%) and A. skirrowii (2.8%). Significantly more poultry meat samples were found to contain Arcobacter spp. by the PCR assay than by the culture method.
4. Susceptibilities of Arcobacter isolates were determined for 14 antimicrobial drugs using the disk diffusion method. All of the 71 Arcobacter isolates tested were resistant to one or more antimicrobial agents. Resistance to cephalothin and vancomycin (95.8%) was the most common finding, followed by resistance to methicillin, azithromycin and ampicillin. All Arcobacter isolates were susceptible to gentamicin, streptomycin, tetracyclin and kanamycin.
5. The results of this study indicated the importance of poultry meat, especially chicken meat, as potential sources of Arcobacter spp. infection in people. Furthermore, the strains indicated resistance to a broad spectrum of antibiotics. 相似文献
The city of Tehran,like many polluted metropolises of the world,has higher emissions of greenhouse gases than other cities in Iran,due to heavy consumption of fossil fuel and landuse changes.To estimate carbon sequestration in two 40 year-old stands of planted Cupressus arizonica and Fraxinus rotundifolia in degraded lands surrounding Tehran,sampling of above-and below-ground biomass,soil(at two depths of 0-15 and 15-30 cm),and leaf litter was done by systematic random sampling.The total carbon stocks of C.arizonica and F.rotundifolia stands were respectively 328.20 and 150.69 Mg·ha-1.The aboveground biomass with 233.16(71%)Mg·ha-1 in C.arizonica and88.16(58.50%)Mg·ha-1 in F.rotundifolia contributed the most shares to carbon sequestration.The diameter at breast height,total height,basal area,total volume,and biomass of C.arizonica were significantly(p0.01)higher than those of F.rotundifolia.Also the depth of 0-30 cm of soil contributed between 18.29%and 32.15%of total ecosystem carbon,respectively.The economic value of carbon sequestration in the two stands in 2011 was calculated at 3.5 and 2.5 million dollars,respectively.Our results indicate that afforestation of the degraded land surrounding Tehran would sequester more carbon than would continuously degraded land,the current status quo.These stands can absorb atmospheric CO2 at different rates,thus tree species selection and stand development should be considered in planning future afforestation projects. 相似文献
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