共查询到20条相似文献，搜索用时 31 毫秒
1.
Synechococcus sp.CC9311 is a marine cyanobacterium characterized by type IV chromatic acclimation(CA).A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA.The results show that Synechococcus sp.CC9311 cells were sensitive to four commonly used antibiotics:ampicillin,kanamycin,spectinomycin,and chloramphenicol.An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV,using a kanamycin resistance gene as selectable marker,was constructed by recombinant polymerase chain reaction.The plasmid was then transformed into Synechococcus sp.CC9311 via electroporation.High transformation efficiency was achieved at a field strength of 2 kV/cm.DNA analysis showed that mpeV was fully disrupted following challenge of the transformants with a high concentration of kanamycin.In addition,the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium. 相似文献
2.
Flavobacterium columnare causes columnaris disease in freshwater fish. In the present study, the antigenic regions of five outer membrane proteins (OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 kDa, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purified recombinant protein was used to vaccinate the grass carp, Ctenopharyngodon idella. Following vaccination of the fish their IgM antibody levels were examined, as was the expression of IgM, IgD and IgZ immunoglobulin genes and other genes such as MHC Iα and MHC IIβ, which are also involved in adaptive immunity. Interleukin genes (IL), including IL-1β, IL-8 and IL-10, and type I and type II interferon (IFN) genes were also examined. At 3 and 4 weeks post-vaccination (wpv), significant increases in IgM antibody levels were observed in the fish vaccinated with the recombinant fusion protein, and an increase in the expression levels of IgM, IgD and IgZ genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fish. At four wpv, the fish were challenged with F. columnare, and the vaccinated fish showed a good level of protection against this pathogen, with 39% relative percent survival (RPS) compared with the control group. It can be concluded, therefore, that the five OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fish and protection against F. columnare. 相似文献
3.
In recent years, Edwardsiella tarda has become one of the most deadly pathogens of Japanese flounder (Paralichthys olivaceus), causing serious annual losses in commercial production. In contrast to the rapid advances in the aquaculture of P. olivaceus, the study of E. tarda resistance-related markers has lagged behind, hindering the development of a disease-resistant strain. Thus, a marker-trait association analysis was initiated, combining bulked segregant analysis (BSA) and quantitative trait loci (QTL) mapping. Based on 180 microsatellite loci across all chromosomes, 106 individuals from the F1333 (♀: F0768 ×♂: F0915) (Nomenclature rule: F+year+family number) were used to detect simple sequence repeats (SSRs) and QTLs associated with E. tarda resistance. After a genomic scan, three markers (Scaffold 404-21589, Scaffold 404-21594 and Scaffold 270-13812) from the same linkage group (LG)-1 exhibited a significant difference between DNA, pooled/bulked from the resistant and susceptible groups (P <0.001). Therefore, 106 individuals were genotyped using all the SSR markers in LG1 by single marker analysis. Two different analytical models were then employed to detect SSR markers with different levels of significance in LG1, where 17 and 18 SSR markers were identified, respectively. Each model found three resistance-related QTLs by composite interval mapping (CIM). These six QTLs, designated qE1–6, explained 16.0%–89.5% of the phenotypic variance. Two of the QTLs, qE-2 and qE-4, were located at the 66.7 cM region, which was considered a major candidate region for E. tarda resistance. This study will provide valuable data for further investigations of E. tarda resistance genes and facilitate the selective breeding of disease-resistant Japanese flounder in the future. 相似文献
4.
Fenneropenaeus penicillatus (redtail shrimp) is an important marine commercial animal in China. Recently, its resources have been depleted rapidly as a result of, for example, over-exploitation and environmental degradation of spawning grounds. Therefore, we analyzed the genetic diversity and differentiation of nine wild populations of F. penicillatus of China (Ningde, Lianjiang, Putian, Xiamen, Quanzhou, Zhangpu, Dongshan, Nanao, and Shenzhen populations) by amplified fragment length polymorphism (AFLP) technology, to provide genetic information necessary for resource protection, rejuvenation, artificial breeding, and sustainable use of the resource. Eight AFLP primer pairs were used for amplification, and 508 bands were detected among the populations. The results show that the percentage of polymorphic loci (P) ranged from 41.34% to 63.58%; the Nei’s gene diversity (H) of the populations was 0.119 4-0.230 5; and Shannon’s Information Index (I) was 0.184 1-0.342 5. These genetic data indicate that the genetic diversity of F. penicillatus was high. The genetic differentiation coefficient (GST=0.216 2) and gene flow (Nm=1.812 4) show that there was a high level of genetic differentiation and a moderate level of gene flow among populations. More studies on the genetic differentiation mechanism of F. penicillatus along the south-eastern coast of China need to be conducted to find more effective scientific protection strategies for the conservation of F. penicillatus genetic resources. 相似文献
5.
6.
The swimming endurance of whiteleg shrimp(Litopenaeus vannamei, 87.66 mm ± 0.25 mm, 7.73 g ± 0.06 g) was examined at various concentrations of dissolved oxygen(DO, 1.9, 3.8, 6.8 and 13.6 mg L-1) in a swimming channel against one of the five flow velocities(v1, v2, v3, v4 and v5). Metabolite contents in the plasma, hepatopancreas and pleopods muscle of the shrimp were quantified before and after swimming fatigue. The results revealed that the swimming speed and DO concentration were significant factors that affected the swimming endurance of L. vannamei. The relationship between swimming endurance and swimming speed at various DO concentrations can be described by the power model(ν·tb = a). The relationship between DO concentration(mg L-1) and the swimming ability index(SA∫ 9000I), defined as SAI =vdt( cm), can be described as SAI = 27.947 DO0.137(R2 = 0.9312). The 0level of DO concentration directly affected the physiology of shrimp, and exposure to low concentrations of DO led to the increases in lactate and energetic substrate content in the shrimp. In responding to the low DO concentration at 1.9 mg L-1 and the swimming stress, L. vannamei exhibited a mix of aerobic and anaerobic metabolism to satisfy the energetic demand, mainly characterized by the utilization of total protein and glycogen and the production of lactate and glucose. Fatigue from swimming led to severe loss of plasma triglyceride at v1, v2, and v3 with 1.9 mg L-1 DO, and at v-11 with 3.8, 6.8 and 13.6 mg L DO, whereas the plasma glucose content increased significantly at v3, v4 and v5 with 3.8 and 6.8 mg L-1 DO, and at v5 with 13.6 mg L-1 DO. The plasma total protein and hepatopancreas glycogen were highly depleted in shrimp by swimming fatigue at various DO concentrations, whereas the plasma lactate accumulated at high levels after swimming fatigue at different velocities. These results were of particular value to understanding the locomotory ability of whiteleg shrimp and its physiological changes, further contributing to the improvement of capture and rearing technique. 相似文献
7.
Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids. 相似文献
8.
We used preliminary data to estimate the growth volume of artificially reforested Pinus densiflora in a post-fire area on three different contour conditions. We compared the growth of P. densiflora on a south-facing slope (Ssth), north-facing slope (Snth) and ridge area (Ridge), using 7 trees selected from each stand aspect. The tree height, diameter and growth volume were measured and the dry weight of each plant part were compared and analyzed. The results revealed that the total dry weight was highest on Ssth (5992.3 g), followed by Snth (4833.2 g) and lowest on Ridge (3160.1 g). The height growth was highest on Snth (285.8 cm), followed by Ssth (274.5 cm) and lowest on Ridge (211.5 cm). The diameter growth was greatest on Ssth (7.37 cm), followed by Snth (7.10 cm) and lowest on Ridge (5.72 cm). The volume growth was highest on Ssth (4257.7 cm3), followed by Snth (3750.7 cm3) and lowest on Ridge (2093.7 cm3). Therefore, we should consider and include the concept of slope orientation together with differences in habitat environments in afforestation projects when creating artificial forests with P. densiflora. These study results can serve as important preliminary data for future establishment of artificial forest of P. densiflora in a post-fire plantation. 相似文献
9.
Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae Heterosigma akashiwo and Prorocentrum micans. Inhibitory effects of fresh and dried tißsues of green alga Ulva intestinalis were assessed and the main algicidal compounds were isolated, purified, and identified. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/mL of U. intestinalis dissolved in media significantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate (EtOAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/mL, respectively, were fatal to H. akashiwo, while its water and EtOAc extracts in excess of 0.96 and 0.32 mg/mL, respectively, were lethal to P. micans. Three algicidal compounds in the EtOAc extracts were identified as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid (I), (6E,9E,12E)-(2-acetoxy-β-D-glucose)-octadecatrienoic acid ester (II) and hexadecanoic acid (III). Of these, compound II displayed the most potent algicidal activity with IC50 values of 4.9 and 14.1 µg/mL for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC50 values of 13.4 and 24.7 µg/mL for H. akashiwo and P. micans, respectively. These findings suggested that certain macroalgae or products therefrom could be used as effective biological control agents against red tide algae. 相似文献
10.
We investigated the effects of dried macroalga Gracilaria lemaneiform （Rhodophyta） on photosynthesis of the bloom-forming microalga Chaetoceros curvisetus. C. curvisetus was cultured with different amounts of dried G. lemaneiformis under controlled laboratory conditions. We measured the photosynthetic oxygen evolution rate and established the chlorophyll a fluorescence transient （OJIP） curve coupled with its specific parameters. We observed concentration-dependent and time-dependent relationships between dried G. lemaneiformis and inhibition of photosynthesis in C. curvisetus. Co-culture with dried G. lemaneiformis also resulted in a decrease in the light-saturated maximum photosynthetic oxygen evolution rate （P~ax） in C. curvisetus, and a decrease in the OJIP curve along with its specific parameters; the maximum photochemical efficiency of PSII （FJFm）, the amount of active PSII reaction centers per excited cross section at t=0 and t=--tFM （RC/CS0 and RC/CSm, respectively）, the absorption flux per excited cross section at t=0 （ABS/ CS0）, and the efficiency with which a trapped exciton moves an electron into the electron transport chain （~u0）. The dark respiration rate （Rd） increased in C. curvisetus co-cultured with dried G. lemaneiformis. The JIP-test and the oxygen evolution results indicated that dried G. lemaneiJbrmis decreased the number of active reaction centers, blocked the electron transport chain, and damaged the oxygen-evolving complex of C. curvisetus. This result indicated that dried fragments of G. lemaneiformis could effectively inhibit photosynthesis of C. curvisetus, and thus, could serve as a functional product to control and mitigate C. curvisetus blooms. 相似文献
11.
12.
Abdul Hameed Shahida Hasnain 《中国海洋湖沼学报》2005,23(4):433-441
Many unicellular cyanobacteria were isolated from different places： fields, ponds, polluted water, and soils from Muredkey and Kasur tannery areas, near Lahore, Pakistan. Different media like BG 11 medium, Bold Basal medium, Chu＇s # 10 medium and Gotham＇s medium, in standard forms and with slight variations of ingredients, and different pH, temperature and light regimes were checked for the optimum growth of the isolates. The isolation pro- cedure was repeated with different concentrations of chromium to select the resistant strains. These selected strains grew on chromium of the range 100-200 μg/ml in BG 11 medium. Cyanobacteria were maintained in solid and liquid media with/without shaking. Cyanobacterial strains were collected from natural habitats that were accompanied by a diversified group of organisms including bacteria, protozoan, and rotifers etc. In order to eliminate these agents termed as contaminants, we used several methods including phenol treatment, use of antibiotic and careful manual picking of unicellular cyanobacteria. Resistance of these strains against different heavy metals （ZnSO4, MnSO4, NiSO4, COCl2, Pb（NO3）3, CuSO4, HgCl2, AgNO3 and CdCl2） and antibiotics （erythromycin, streptomycin, kanamycin, chloramphenicol, neomycin） was evaluated. Optimum temperature was 30℃ with variable pH for the reduction of Cr^6＋ in to Cr^3＋ in majority of strains. 相似文献
13.
14.
Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata (Porphyra haitanensis) is an economically important genus that is cultured widely in China. P. haitanensis is cultured on a larger scale than Pyropia yezoensis, making up an important part of the total production of cultivated Pyropia in China. However, the majority of molecular mechanisms underlying the physiological processes of P. haitanensis remain unknown. P. haitanensis could utilize inorganic carbon and the sporophytes of P. haitanensis might possess a PCK-type C4-like carbon-fixation pathway. To identify microRNAs and their probable roles in sporophyte and gametophyte development, we constructed and sequenced small RNA libraries from sporophytes and gametophytes of P. haitanensis. Five microRNAs were identified that shared no sequence homology with known microRNAs. Our results indicated that P. haitanensis might posses a complex sRNA processing system in which the novel microRNAs act as important regulators of the development of different generations of P. haitanensis. 相似文献
15.
DU Guoying WU Feifei MAO Yunxiang GUO Shenghua XUE Hongfan and BI Guiqi 《中国海洋大学学报(英文版)》2014,13(1):97-103
An assessment with assistance of DNA barcoding was conducted on green macroalgae in coastal zone around Qingdao, China, during the period of April–December, 2011. Three markers were applied in molecular discrimination, including the plastid elongation factor tufA gene, the internal transcribed spacer (ITS) region of the ribosomal cistron and rubisco large subunit gene 3′ regions (rbcL-3P). DNA barcoding discriminated 8 species, excluding species of genus Cladophora and Bryopsis due to failures in amplification. We ascertained and corrected 4 species identified by morphological methods for effectively assisting the classification. The gene tufA presented more advantages as an appropriate DNA marker with the strongest amplification success rate and species discrimination power than the other two genes. The poorest sequencing success largely handicapped the application of ITS. Samples identified by tufA and rbcL as Ulva flexuosa were clustered into the clade of U. prolifera by ITS in the neighbor-joining tree. Confusion with discrimination of the complex of U. linza, U. procera and U. prolifera (as the LPP complex) still existed for the three DNA markers. Based on our results, rbcL is recommended as a preferred marker for assisting tufA to discriminate green macroalgae. In distinguishing green-tide-forming Ulva species, the free-floating sample collected from the green tide in 2011 was proved to be identical with U. prolifera in Yellow Sea for ITS and rbcL genes. This study presents a preliminary survey of green macroalgae distributed in the coastal area around Qingdao, and proves that DNA barcoding is a powerful tool for taxonomy of green macroalgae. 相似文献
16.
Growth and mortality of small yellow croaker (Larimichthys polyactis) inhabiting Haizhou bay of China 总被引：1，自引：0，他引：1
Length frequency data of small yellow croaker(Larimichthys polyactis) were acquired from the survey vessel in May,July,September and December,2011 in Haizhou Bay of China.In this study,921 fish individuals were analyzed for the estimation of growth and mortality parameters.Between length and weight,the power coefficient b was 2.7321,2.9703,3.0418 and 2.7252 for the 4 surveying months,respectively.The estimated von Bertalanffy growth function parameters were 230mm(L ∞) and 0.26yr-1(K) as were calculated with ELEFAN method equipped in FiSAT computer package.With length-converted catch curve analysis,the total mortality rate(Z) and its 95% confidence interval were 2.16(1.69-2.64) yr-1,0.59(0.15-1.04) yr-1,1.16(0.80-1.52) yr-1 and 0.96(0.70-1.23) yr-1 for the 4 surveying months,respectively,with the pooled data the value was 1.15(0.81-1.48) yr-1.The natural mortality rate(M) was 0.516 yr-1 as was calculated with Pauly’s equation(the annual average sea water temperature was 11℃).Therefore,fish mortality rate was 0.634 yr-1.The yield-per-recruit analysis indicated that when t c was 1,F max was 0.7 and F 0.1 was 0.55.Currently,the age at first capture is about 1 year and F current was 0.634.Therefore,F current was larger than F 0.1 and less than F max.This indicates that current fish mortality is at a dangerously high level.With Gulland method,the biological reference point for fishery(F opt) was estimated as 0.516 yr-1,lower than current fish mortality.Accordingly,reducing catch in the region was strongly recommended. 相似文献
17.
Effects of forest gaps on some microclimate variables in Castanopsis kawakamii natural forest 总被引：1，自引：0，他引：1
Zhongsheng He Jinfu Liu Caiting Wu Shiqun Zheng Wei Hong Songjin Su Chengzhen Wu 《山地科学学报》2012,9(5):706-714
The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features of air temperature (TA ), soil temperature (TS ), relative humidity (h) and soil water content (Ψ) were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that: (1) the variations of TA , h, and TS in four seasons were extremely significant. The variations of Ψ in four seasons were extremely significant except for those between spring and summer. (2) The diurnal variations of TA and T S were expressed with a single peak curve. The diurnal variations of h and Ψ presented a high-low-high trend. (3) The variations of TA , h, and TS were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were just contrary to medium gaps. The variations of Ψ were extremely significant for large, medium and small gaps except those between the medium and large gaps. (4) The TA , h, TS and Ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest. 相似文献
18.
Community structure of epiphytic algae on three different macrophytes at Acarlar floodplain forest （northern Turkey） 总被引：2，自引：2，他引：0
Hatice TUNCA Tugba ONGUN SEVINDIK Dilek Nur BAL Sevil ARABACI 《中国海洋湖沼学报》2014,32(4):845-857
The aim of this study was to determine the species composition, biodiversity and, relative abundance of epiphytic algae and their relationship with environmental variables on three different macrophytes( Nymphaea alba, Ceratophyllum demersum, Typha latifolia) at Acarlar Floodplain Forest(AFF). Epiphytic algae were gathered monthly by collecting aquatic plants between November 2011 and October 2012, except in winter when there were no plants. In this study, 67 taxa on N. alba, 66 taxa on C. demersum and 66 taxa on T. latifolia were identified as epiphytic algae. The mean value of species richness was 17, that of diversity was 1.5 and that of evenness was 0.54 for epiphytic algae on N. alba, 17, 1.1, and 0.39 on C. demersum, and 18, 1.64, and 0.56 on T. latifolia, respectively. Oscillatoria sp. and Komvophoron crassum(Vozzen) Anagnostidis and Komárek were the most abundant and consistent epiphytic algal species, occurring in high abundance on all macrophytes. Results show that species composition of epiphytic algae was different, but diversity values were similar on all the macrophytes. The hydrological pulse is one of the most important factors determining the physical and chemical environment of the epiphytic algal community. However, substrate type also affected the colonization by F. capucina, O. sancta, P. catenata, and L. truncicola more than the epiphytic algal seasonality. 相似文献
19.
Seven microsatellite markers were used to evaluate the genetic diversity and differentiation of seven stocks of Litopenaeus vannamei, which were introduced from Central and South America to China. All seven microsatellite loci were polymorphic, with polymorphism information content(PIC) values ranging from 0.593 to 0.952. Totally 92 alleles were identified, and the number of alleles(Na) and effective alleles(Ne) varied between 4 and 21 and 2.7 and 14.6, respectively. Observed heterozygosity(Ho) values were lower than the expected heterozygosity(He) values(0.526–0.754), which indicated that the seven stocks possessed a rich genetic diversity. Thirty-seven tests were detected for reasonable significant deviation from Hardy-Weinberg equilibrium. Fis values were positive at five loci, suggesting that there was a relatively high degree of inbreeding within stocks. Pairwise Fst values ranged from 0.0225 to 0.151, and most of the stock pairs were moderately differentiated. Genetic distance and cluster analysis using UPGMA revealed a close genetic relationship of L. vannamei between Pop2 and Pop3. AMOVA indicated that the genetic variation among stocks(11.3%) was much lower than that within stocks(88.7%). Although the seven stocks had a certain degree of genetic differentiation and a rich genetic diversity, there is an increasing risk of decreased performance due to inbreeding in subsequent generations. 相似文献
20.
Unbalanced parental contribution and small effective population size(N e)are common issues during the artifi cial breeding of marine bivalves.The impact of hatchery-spawning practices on parental contribution,effective population size,the N e/N ratio,and genetic diversity are largely unknown.To address this,we conducted a parentage analysis on a complete 3×3 diallel cross of clam M eretrix meretrix using eight microsatellite markers.The genetic diversity of the parents was higher than that of their respective offspring in most crosses(8/9).Sires or dams from the same family contributed unequally to the pool of offspring from a particular cross,and the same parent clam exhibited large variation in parental contribution among different crosses.The variance in male contribution was higher than that of the female contribution in most crosses,suggesting that male contribution was more skewed than for females.The N e/N ratio for nine crosses ranged from 0.58 to 0.86.There was no linear relationship between the sex ratio and the N e/N ratio(P0.05).Moreover,a sex ratio closer to one-to-one does not necessarily mean a larger effective population size.A solution to small effective population size in commercial breeding programs is increasing broodstock numbers and attempting to maintain a balanced sex ratio. 相似文献