Institute of Hydrobiology, Chinese Academy Of Sciences
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Development of microsatellite markers and genetic diversity in wild and cultured populations of black carp (Mylopharyngodon piceus) along the Yangtze River
No full textBlack carp (Mylopharyngodon piceus) is one of traditionally important aquaculture fishes in China; however, population genetic studies are relatively rare for this species. In the present study, we developed a set of microsatellite markers by FIASCO method and used ten of these polymorphic markers to evaluate genetic diversity of black carp (three wild populations and six cultured populations including larvae from fish seed farms and adults from fish markets,n = 269) along the Yangtze River basin. Among these samples, mean number of alleles (Na) and effective number of alleles (Ne) were 14 and 6, respectively. Genetic diversities of wild populations were higher than that of cultured populations, represented byHoof 0.767 vs 0.730,Heof 0.806 vs 0.722, andpolymorphism information contentof 0.767 vs 0.6731, respectively, although a few cultured populations were exceptional.Fst from 0.010 to 0.159 showed a moderate level of population differentiations, and Bayesian and clustering analysis consistently supported that these populations could be divided into 7 clusters. This study generated novel microsatellites and new evidence of genetic differentiation between wild and cultured populations of black carp, which are useful for conservation and sustainable utilization of fishery resources
PGRL1 overexpression inPhaeodactylum tricornutuminhibits growth and reduces apparent PSII activity
No full textProton gradient regulation 5-like photosynthetic phenotype 1 (PGRL1)-dependent cyclic electron transport around photosystem I (PSI) plays important roles in the response to different stresses, including high light. Although the function of PGRL1 in higher plants and green algae has been thoroughly investigated, little information is available on the molecular mechanism of PGRL1 in diatoms. We created PGRL1 overexpression and knockdown transformants ofPhaeodactylum tricornutum, the diatom model species, and investigated the impact on growth and photosynthesis under constant and fluctuating light conditions. PGRL1 over-accumulation resulted in significant decreases in growth rate and apparent photosystem II (PSII) activity and led to an opposing change of apparent PSII activity when turning to high light, demonstrating a similar influence on photosynthesis as a PSII inhibitor. Our results suggested that PGRL1 overexpression can reduce the apparent efficiency of PSII and inhibit growth inP. tricornutum. These findings provide physiological evidence that the accumulation of PGRL1 mainly functions around PSII instead of PSI
Co-regulatory role of Microcystis colony cell volume and compactness in buoyancy during the growth stage
No full textThe buoyancy of Microcystis colonies determines the occurrence and dominance of bloom on the water surface. Besides the cell density regulation and the formation of larger size aggregates, increases in cell volume per colony (V-cell) and the colony's compactness (i.e., volume ratio of cells to the colony, VR) may promote Microcystis colony buoyancy. Yet only a few studies have studied the relationship between the internal structure variation of colonies and their buoyancy, and the co-regulatory role of V-cell and VR of Microcystis colonies in the floating velocity (FV) remains largely unexplored. In the present study, we optimized a method for measuring the compactness of Microcystis colonies based on the linear relationship between total V(cell )and chlorophyll a. Different relationships between the VRs and FVs were observed with different colony size and V-cell range groups. Both field and laboratory experiments showed that FV/(D-50, median diameter)(2) had a significant linear relationship with VR, indicating that the cell density and extracellular polysaccharides were unchanged over a short time period and could be estimated via the slope and intercept of a fitted line. We also constructed a functional relationship between FV, VR, and V-cell and found that high VR and V-cell can promote Microcystis buoyancy. This means that increasing cell compactness or V(cell )may be an active regulation strategy for Microcystis colonies to promote buoyancy. Therefore, quantifying the internal structure of Microcystis colonies is strongly recommended for the assessment of Microcystis bloom development and their management
Growth performance, fast muscle development and chemical composition of juvenile lumpfish ( Cyclopterus lumpus ) fed diets incorporating soy and pea protein concentrates
No full textLumpfish ( Cyclopterus lumpus ) are widely applied as biological delousers in open net -pen farming of Atlantic salmon. As a species new to farming it is necessary to obtain a comprehensive understanding of the capacity of lumpfish to utilize plant derived feed ingredients. A feeding trial lasting for 54 days was conducted to investigate the effects of replacing fishmeal (FM) with a mix of soy protein concentrate (SPC) and pea protein concentrate (PPC) on growth, body chemical composition, and fast muscle fiber cellularity in juvenile lumpfish. Four iso- nitrogenous and isoenergetic diets (52 % crude protein and 14 % crude lipid) were formulated; a FM based diet was used as control (CTRL), and three experimental diets containing SPC and PPC (equal proportions of 1:1), replacing FM on weight basis at 25 % (PP25) 50 % (PP50) and 75 % (PP75). The fish grew from approximately 6.9 g to an average weight of 40.2 g in 54 days. Fish fed PP50 had significantly higher body weight, length and height compared to the other dietary groups. The whole body crude protein content of fish fed PP50 was sig- nificantly higher compared to the CTRL diet, while crude lipids were lower than those on CTRL and PP25 diets. Ash and dry matter did not differ among groups. Probability density functions showed no differences in fast muscle fiber size distributions amongst feeding groups. A higher percentage of smaller fibers in all feeding groups indicated hyperplasia was the dominant mechanism of muscle growth during the experimental period. These results suggest that a mixture of SPC and PPC can replace up to 50 % of FM in diets for juvenile lumpfish without any adverse effects on growth, chemical composition and fast muscle fiber cellularity
Growth performance, fast muscle development and chemical composition of juvenile lumpfish ( Cyclopterus lumpus ) fed diets incorporating soy and pea protein concentrates
No full textLumpfish ( Cyclopterus lumpus ) are widely applied as biological delousers in open net -pen farming of Atlantic salmon. As a species new to farming it is necessary to obtain a comprehensive understanding of the capacity of lumpfish to utilize plant derived feed ingredients. A feeding trial lasting for 54 days was conducted to investigate the effects of replacing fishmeal (FM) with a mix of soy protein concentrate (SPC) and pea protein concentrate (PPC) on growth, body chemical composition, and fast muscle fiber cellularity in juvenile lumpfish. Four iso- nitrogenous and isoenergetic diets (52 % crude protein and 14 % crude lipid) were formulated; a FM based diet was used as control (CTRL), and three experimental diets containing SPC and PPC (equal proportions of 1:1), replacing FM on weight basis at 25 % (PP25) 50 % (PP50) and 75 % (PP75). The fish grew from approximately 6.9 g to an average weight of 40.2 g in 54 days. Fish fed PP50 had significantly higher body weight, length and height compared to the other dietary groups. The whole body crude protein content of fish fed PP50 was sig- nificantly higher compared to the CTRL diet, while crude lipids were lower than those on CTRL and PP25 diets. Ash and dry matter did not differ among groups. Probability density functions showed no differences in fast muscle fiber size distributions amongst feeding groups. A higher percentage of smaller fibers in all feeding groups indicated hyperplasia was the dominant mechanism of muscle growth during the experimental period. These results suggest that a mixture of SPC and PPC can replace up to 50 % of FM in diets for juvenile lumpfish without any adverse effects on growth, chemical composition and fast muscle fiber cellularity
Responses of four submerged macrophytes to freshwater snail density (Radix swinhoei) under clear-water conditions: A mesocosm study
No full textMacrophytes play a key role in stabilizing clear-water conditions in shallow freshwater ecosystems. Their populations are maintained by a balance between plant grazing and plant growth. As a freshwater snail commonly found in shallow lakes,Radix swinhoeican affect the growth of submerged macrophytes by removing epiphyton from the surface of aquatic plants and by grazing directly on macrophyte organs. Thus, we conducted a long-term (11-month) experiment to explore the effects of snail density on macrophytes with distinctive structures in an outdoor clear-water mesocosm system (with relatively low total nitrogen (TN, 0.66 +/- 0.27 mg/L) and total phosphorus (TP, 36 +/- 20 mu g/L) and a phytoplankton chlorophylla(Chla) range of 14.8 +/- 4.9 mu g/L) based on two different snail densities (low and high) and four macrophyte species treatments (Myriophyllum spicatum,Potamogeton wrightii,P. crispus, andP. oxyphyllus). In the high-density treatment, snail biomass and abundance (36.5 +/- 16.5 g/m(2)and 169 +/- 92 ind/m(2), respectively) were approximately twice that observed in the low-density treatment, resulting in lower total and aboveground biomass and ramet number in the macrophytes. In addition, plant height and plant volume inhabited (PVI) showed species-specific responses to snail densities, that is, the height ofP. oxyphyllusand PVI ofM. spicatumwere both higher under low-density treatment. Thus, compared with low-density treatment, the inhibitory effects of long-term high snail density on macrophytes by direct feeding may be greater than the positive effects resulting from epiphyton clearance when under clear-water conditions with low epiphyton biomass. Thus, under clear-water conditions, the growth and community composition of submerged macrophytes could be potentially modified by the manual addition of invertebrates (i.e., snails) to lakes if the inhibitory effects from predatory fish are minor
Kisspeptin2 regulates hormone expression in female zebrafish (Danio rerio) pituitary
No full textKisspeptin2 is a neuropeptide widely found in the brain and multiple peripheral tissues in the zebrafish. The pituitary is the center of synthesis and secretes various endocrine hormones. However, Kiss2 innervation in the zebrafish pituitary is unknown. In this study, the organization of Kiss2 cells and structures in the zebrafish pituitary by promoter-driving mCherry-labeling Kiss2 neurons were investigated. Kiss2 neurons in the hypothalamus do not project into the pituitary. Kiss2 cells are found in the female pituitary. Unidentified Kiss2 cells and extensions are located in the proximal pars distalis (PPD), similar to the distribution of Gnrh3 fibers. Kiss2 structures reside alongside Gnrh3 fibers. No Kiss2 structures are found in the male pituitary. The transcriptional expression of the kisspeptin receptor kiss1rb is detected in both female and male pituitaries. In situ hybridization shows that kiss1rb-positive cells are located in the PPD and pars intermedia (PI). In vitro Kiss2-10 treatment stimulates Akt and Erk phosphorylation and significantly induces lh beta, fsh beta, and prl1 mRNA expression in the female pituitary. The results in this study suggest that Kiss2 and Kiss1rb may form an independent paracrine or autocrine system in the female zebrafish pituitary. Kiss2 and Kiss1rb signaling regulates the expression of pituitary hormones
The Morphology and Phylogeny of ThreeDiophrysCiliates Collected from the Subtropical Waters of China, Including a New Species (Ciliophora; Euplotia)
No full textThreeDiophrysspecies,D. quadrinucleatan. sp.,D. oligothrixBorror, 1965 andD. scutum(Dujardin, 1841) Kahl, 1932, were identified from the subtropical brackish waters in China, their morphology was investigated using live observation and protargol impregnation.D. quadrinucleatan. sp. can be distinguished from the congeners by four ellipsoidal macronuclear nodules. Phylogenetic analyses show that the three species with single marginal cirrus are closely related, namelyD. quadrinucleatan. sp.,D. apoligothrixSonget al., 2009 andD. japonicaHu, 2008. Our population ofD. oligothrixcorresponds very well with previous populations in both living morphology and ciliature. However, the SSU rDNA sequences of three well-described populations differ from each other by 11 to 18 nucleotides, indicating that there might be cryptic species inD. oligothrix. Moreover, we provided a detailed description of the symbiotic bacteria/archaeobacteria (?) concentrated on the back surface ofD. scutumbased on the present population, which was either overlooked or misinterpreted as cortical granules previously
Simulation modeling reveals the evolutionary role of landscape shape and species dispersal on genetic variation within a metapopulation
No full textDifferent shapes of landscape boundaries can affect the habitat networks within them and consequently the spatial genetic-patterns of a metapopulation. In this study, we used a mechanistic framework to evaluate the effects of landscape shape, through watershed elongation, on genetic divergence among populations at the metapopulation scale. Empirical genetic data from four, sympatric stream-macroinvertebrates having aerial adults were collected from streams in Japan to determine the roles of species-specific dispersal strategies on metapopulation genetics. Simulation results indicated that watershed elongation allows the formation of river networks with fewer branches and larger topographic constraints. This results in decreased interpopulation connectivity but a lower level of spatial isolation of distal populations (e.g. those found in headwaters) occurring in the landscapes examined. Distal populations had higher genetic divergence when their downstream-biased dispersal (relative to upstream- and/or overland-biased dispersal) was high. This underscores the importance of distal populations influencing genetic divergence at the metapopulation scale for species having downstream-biased dispersal. In turn, lower genetic divergence was observed under watershed elongation when the genetic isolation of distal populations was decreased in such species. This strong association between landscape shape and evolutionary processes highlights the importance of natural, spatial architecture in assessing the effectiveness of conservation and management strategies
Identification and Biotechnical Potential of a Gcn5-Related N-Acetyltransferase Gene in Enhancing Microalgal Biomass and Starch Production
No full textMicroalgae are promising feedstocks for starch production, which are precursors for bioenergy and chemicals manufacturing. Though starch biosynthesis has been intensively studied in the green algaChlamydomonas reinhardtii, regulatory mechanisms governing starch metabolism in this model species have remained largely unknown to date. We proposed that altering triacylglycerol (TAG) biosynthesis may trigger intrinsic regulatory pathways governing starch metabolism. In accordance with the hypothesis, it was observed in this study that overexpression of the plastidial lysophosphatidic acid acyltransferase gene (i.e.LPAAT1) inC. reinhardtiisignificantly enhanced TAG biosynthesis under nitrogen (N)-replete conditions, whereas the starch biosynthesis was enhanced in turn under N depletion. By the exploitation of transcriptomics analysis, a putative regulatory gene coding Gcn5-related N-acetyltransferase (GNAT19) was identified, which was up-regulated by 11-12 times in theCrLPAAT1OE lines. Overexpression of the cloned full-lengthCrGNAT19cDNA led to significant increase in the starch content ofC. reinhardtiicells grown under both N-replete and N-depleted conditions, which was up to 4 times and 26.7% higher than that of the empty vector control, respectively. Moreover, the biomass yield of theCrGNAT19OE lines reached 1.5 g L(-1)after 2 days under N-depleted conditions, 72% higher than that of the empty vector control (0.87 g L-1). Overall, the yield of starch increased by 118.5% inCrGNAT19OE lines compared to that of the control. This study revealed the great biotechnical potentials of an unprecedentedGNAT19gene in enhancing microalgal starch and biomass production