Unveiling the emerging role of curcumin to alleviate ochratoxin A-induced muscle toxicity in grass carp(Ctenopharyngodon idella):in vitro and in vivo studies

Background Ochratoxin A(OTA),a globally abundant and extremely hazardous pollutant,is a significant source of contamination in aquafeeds and is responsible for severe food pollution.The developmental toxicity of OTA and the potential relieving strategy of natural products remain unclear.This study screened the substance curcumin(Cur),which had the best effect in alleviating OTA inhibition of myoblast proliferation,from 96 natural products and investigated its effect and mechanism in reducing OTA myotoxicity in vivo and in vitro.Methods A total of 720 healthy juvenile grass carp,with an initial average body weight of 11.06±0.05 g,were randomly assigned into 4 groups:the control group(without OTA and Cur),1.2 mg/kg OTA group,400 mg/kg Cur group,and 1.2 mg/kg OTA+400 mg/kg Cur group.Each treatment consisted of 3 replicates(180 fish)for 60 d.Results Firstly,we cultured,purified,and identified myoblasts using the tissue block culture method.Through preliminary screening and re-screening of 96 substances,we examined cell proliferation-related indicators such as cell viability and ultimately found that Cur had the best effect.Secondly,Cur could alleviate OTA-inhibited myoblast differentiation and myofibrillar development-related proteins(Myo G and MYHC)in vivo and in vitro and improve the growth performance of grass carp.Then,Cur could also promote the expression of OTA-inhibited protein synthesis-related proteins(S6K1 and TOR),which was related to the activation of the AKT/TOR signaling pathway.Finally,Cur could downregulate the expression of OTA-enhanced protein degradation-related genes(murf1,foxo3a,and ub),which was related to the inhibition of the Fox O3a signaling pathway.Conclusions In summary,our data demonstrated the effectiveness of Cur in alleviating OTA myotoxicity in vivo and in vitro.This study confirms the rapidity,feasibility,and effectiveness of establishing a natural product screening method targeting myoblasts to alleviate fungal toxin toxicity.

Reproductive height determines the loss of clonal grasses with nitrogen enrichment in a temperate grassland

Tall clonal grasses commonly display competitive advantages with nitrogen(N)enrichment.However,it is currently unknown whether the height is derived from the vegetative or reproductive module.Moreover,it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization,and determines species diversity.In this study,the impacts on clonal grasses were studied in a field experiment employing two frequencies(twice a year vs.monthly)crossing with nine N addition rates in a temperate grassland,China.We found that the N addition decreased species frequency and increased extinction probability,but did not change the species colonization probability.A low frequency of N addition decreased species frequency and colonization probability,but increased extinction probability.Moreover,we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions.The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity,suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition.Overall,this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.

Anti-infective immune functions of type Ⅳ interferon in grass carp(Ctenopharyngodon idella):A novel antibacterial and antiviral interferon in lower vertebrates

Type Ⅳ interferon(IFN-υ)is a recently discovered cytokine crucial for host defense against viral infections.However,the role and mechanisms of IFN-υin bacterial infections remain unexplored.This study investigated the antibacterial and antiviral functions and mechanisms of grass carp(Ctenopharyngodon idella)IFN-υ(CiIFN-υ)both in vivo and in vitro.The CiIFN-υgene was first identified and characterized in grass carp.Subsequently,the immune expression of CiIFN-υsignificantly increased following bacterial challenge,indicating its response to bacterial infections.The eukaryotic recombinant expression plasmid of CiIFN-υwas then constructed and transfected into fathead minnow(FHM)cells.Supernatants were collected and incubated with four bacterial strains,followed by plate spreading and colony counting.Results indicated that CiIFN-υexhibited more potent antibacterial activity against gram-negative bacteria compared to gram-positive bacteria and aggregated gram-negative bacteria but not gram-positive bacteria.In vivo experiments further confirmed the antibacterial function,showing high survival rates,low tissue edema and damage,reduced tissue bacterial load,and elevated proinflammatory response at the early stages of bacterial infection.In addition,the antiviral function of CiIFN-υwas confirmed through in vitro and in vivo experiments,including crystal violet staining,survival rates,tissue viral burden,and reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR).This study highlights the antibacterial function and preliminary mechanism of IFN-υ,demonstrating that IFN-υpossesses dual functions against bacterial and viral infections.

The Effect of Water and Salt Stress on Paspalum dilatatum,a Constituent of Pampas Natural Grasslands

The effects of the salt stress on plant growth are usually increased by the water stress.We studied the impact of both stresses in simultaneous pulses of drought and salinity on Paspalum dilatatum.This forage species is native to South America,spread in grasslands in many tropical,subtropical,and temperate areas of the world,and very common in grasslands of the Flooding Pampas of Argentina.Mimicking what happens in nature.We compared a pot experiment,a non-stressed control against water stress for a month(midpoint between field capacity and wilting point),and two saline stresses(moderate,6 d·Sm^(−1)and strong,12 d·Sm^(−1)),also for a month.Aerial biomass(green leaf;non-leaf green material,and dry material)and roots were harvested,weighed,and analyzed for nitrogen,phosphorus,and cations.The biomass of all components significantly decreased when both stresses were applied.Water plus strong saline stress reduced by half the total biomasses,compared to the control.The proportion of aerial biomass/root biomass ratio as well as aerial green component/dry materials ratio tend to decrease when subjected to both stresses.Nitrogen concentration in plants was not significantly affected,but phosphorus concentration increased in aerial biomass components,from 0.10 to 0.18 mg·kg^(−1)between the extreme treatments,but did not change in roots.Sodium concentration in plants increased(i.e.,in green leave sodium(Na)increased from 0.27 to 2.01 mg·kg^(−1)between the extreme treatments),whereas other cations either did not change or decreased,affecting the ratios between them.Sodium performance allows us to infer that the Na accumulation of P.dilatatum behaves in an intermediate range,compared to very tolerant to salts or non-salt tolerant species of the Paspalum genus.In agreement,when salts were applied in the form of a pulse,P.dilatatum tolerated higher salinity than that found by other authors for the same species,using continuous salinity.

Genome-Wide Analysis for Yield-Related Agronomic and Biochemical Traits of Chinese and Bangladeshi Grass Pea Genotypes Using SSR Markers

Grass pea(Lathyrus sativus L.)is an imperative food crop cultured in dryland agricultural ecology.It is a vital source of dietary protein to millions of populaces living in low-income countries in South-East Asia and Africa.This study highlights the improvement of genomic properties and their application in marker-trait relationships for 17 yield-related characters in 400 grass pea genotypes from China and Bangladesh.These characters were assessed via 56 polymorphic markers using general linear model(GLM)(P+G+Q)and mixed linear model(MLM)(P+G+Q+K)in the tassel software based on the linkage disequilibrium and population structure analysis.Population structure analysis showed two major groups and one admixed group in the populace.Statistically significant loci pairs of linkage disequilibrium(LD)mean value(D′)was 0.479.A total of 99 and 61 marker-trait associations in GLM and MLM models allied to the 17 traits were accepted at a 5%level of significance.Among these markers,21 markers were associated with more than one trait;12 marker-trait associations passed the Bonferroni correction threshold.Both models found six markers C41936,C39067,C34100,C47146,C47638,and C43047 significantly associated with days to maturity,flower color,plant height,and seed per pod were detected in the Hebei and Liaoyang location(p≤0.01),and the interpretation rate(R^(2)value)11.2%to 43.6%.Conferring to the consequences,the association analysis methodology may operative system for quantitative,qualitative,and biochemical traits related to gene position mapping and support breeders in improving novel approaches for advancing the grass pea quality.

Application of Transgenic Technology in Identification for Gene Function on Grasses

Perennial grasses have developed intricate mechanisms to adapt to diverse environments,enabling their resistance to various biotic and abiotic stressors.These mechanisms arise from strong natural selection that contributes to enhancing the adaptation of forage plants to various stress conditions.Methods such as antisense RNA technology,CRISPR/Cas9 screening,virus-induced gene silencing,and transgenic technology,are commonly utilized for investigating the stress response functionalities of grass genes in both warm-season and cool-season varieties.This review focuses on the functional identification of stress-resistance genes and regulatory elements in grasses.It synthesizes recent studies on mining functional genes,regulatory genes,and protein kinase-like signaling factors involved in stress responses in grasses.Additionally,the review outlines future research directions,providing theoretical support and references for further exploration of(i)molecular mechanisms underlying grass stress responses,(ii)cultivation and domestication of herbage,(iii)development of high-yield varieties resistant to stress,and(iv)mechanisms and breeding strategies for stress resistance in grasses.

Application and Adaptability of Ornamental Grasses in Road Flower Borders in Hefei, Anhui Province

In-depth research was conducted on the types,seasonal patterns,spatial levels,overwintering,summering,drought resistance,and disease and pest resistance of ornamental grasses in the road flower borders of Hefei,Anhui Province.Through field investigations,a total of 36 ornamental grasses were identified,with Liliaceae having the most species and the Lamiaceae the least.The results show that there are more warm season ornamental grasses,of 23 species;Acorus gramineus and Melinis minutiflora have poor overwintering ability;Arrhenatherum elatius,Festuca glauca,and Stipa tenuissima have poor summer tolerance;most ornamental grasses have strong drought resistance and resistance to pests and diseases.The comprehensive investigation shows that ornamental grasses have good application prospects and adaptability in the road flower borders in Hefei city.

Effect of Using Israel Napier Grass in Feed Ration on Growth Performance of Local Chicken of Cambodia

This study investigated the effect of Israel grass in feed formulation on growth performance of local chicken.The study was conducted from October 2023 until January 2024 in Kampong Chheutel Institute of Technology.The CRD(Completely Randomized Design)was used with 4 treatments and 4 replications.The local chicks were purchased from local famer at 1 day old and kept in whole pen by feeding commercial feed.At 21 days old the total 320 chicks were allocated into experimental treatments.The 4 feed formulas based on the level of Israel grass added such as 0,5%,7%and 9%,were called T1(control),T2,T3 and T4 respectively.The result showed that body weight gain,feed intake,ADG(Average Daily Gain)and FCR(Feed Conversion Ratio)in all treatments were not significantly different(p>0.05).However,there was strong correlation between living weight with carcass of al treatments,but no difference among carcass percentage of local chicken for all different diet in this study.In conclusion,the Israel grass did not affect growth performance of local chickens and can be used to replace some expensive feed ingredient,such as rice bran.

Effects of Using Softwood Pellet Biochar Prepared at Different Temperatures with Grass Chippings on Retention of Heavy Metals in Contaminated Soils

Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining, industrial activities, improper usage of fertilizers and pesticides, and indiscriminate open waste disposal bring about an increase in the presence of heavy metals in the environment. In the Keffi Metropolis, different elements lead to land contamination which debilitates soil quality, plant survival, human well-being, and the environment as a result of extensive dispersion or quantity of heavy metals in the soil and water. In recent years, biochar has emerged as a promising soil amendment for mitigating heavy metal pollution due to its unique physicochemical properties. This paper provides the effects of softwood pellet biochar on the retention of heavy metals in contaminated soils. A microcosm experiment was carried out to investigate the effects of biochar on the retention of heavy metals in contaminated soils. This research aimed to give an overview of the effects of softwood biochar at different temperatures (550˚C and 700˚C) on the retention of heavy metals and metalloids released from the soil during water inundation. The results show that the addition of organic matter (grass chippings) minimizes heavy metal mobilization. Also, biochar at high temperatures is more effective than those at low temperatures. The expected outcome of the research analysis includes providing insights into the role of biochar in retaining heavy metal contamination and further understanding the use of biochar as a sorbent for the management of contaminated soil.

Camalote Grass (Paspalum fasciculatum Willd) as a Sustainable Raw Material for the Production of Lignocellulosic Ethanol

The current trend of replacing a percentage of gasoline with ethanol has promoted the development of new processes for its production from lignocellulosic biomass. This work reports the production of ethanol from the Camalote grass (Paspalum fasciculatum Willd). The lignocellulosic biomass was subjected to acid hydrolysis at 125C and 15 psi with H2SO4 concentrations at 5%, 10%, and 20%, obtaining an average of reducing sugars (pentoses and hexoses) from the hydrolyzed juice with 12.3%, 10%, and 17% Brix, respectively. The sugars were fermented using yeast of the Saccharomyces cerevisiae at 30C for 48 hours. Finally, the ethanol was distilled at 78C, and the average yields were obtained through analysis of variance with a 95% confidence level. The values indicate that there is a significant difference (p > 0.05), the Tukey study shows that all the % v/v averages are different from each other. For H2SO4 concentration at 5% (10.33 ± 2), H2SO4 at 10% (9.33 ± 1.8), and H2SO4 at 20% (6.33 ± 2). The acidity analysis for the ethanol obtained from each treatment gave a value of 1.8 mg/L of acetic acid in all cases.

The Tallest Grass-Bamboo

Although bamboo is really a kind of grass,it looks more like tree-a beautiful tree.Chinese poets write poems and songs about bamboo,the artists paint it in pictures.

Decoding the Genetic Blueprint of Grass Skyscrapers

In the lush forests of Asia,towering bamboos stand tall,defying the folk expectations for grassy plants.These woody giants,some reaching the staggering height of nearly 40 meters,are the world’s largest members of the grass family.

Mannan oligosaccharides alleviate oxidative injury in the head kidney and spleen in grass carp(Ctenopharyngodon idella)via the Nrf2 signaling pathway after Aeromonas hydrophila infection

Background Mannan oligosaccharides(MOS)are recommended as aquaculture additives owing to their excellent antioxidant properties.In the present study,we examined the effects of dietary MOS on the head kidney and spleen of grass carp(Ctenopharyngodon idella)with Aeromonas hydrophila infection.Methods A total of 540 grass carp were used for the study.They were administered six gradient dosages of the MOS diet(0,200,400,600,800,and 1,000 mg/kg)for 60 d.Subsequently,we performed a 14-day Aeromonas hydrophila challenge experiment.The antioxidant capacity of the head kidney and spleen were examined using spectrophotometry,DNA fragmentation,qRT-PCR,and Western blotting.Results After infection with Aeromonas hydrophila,400-600 mg/kg MOS supplementation decreased the levels of reactive oxygen species,protein carbonyl,and malonaldehyde and increased the levels of anti-superoxide anion,antihydroxyl radical,and glutathione in the head kidney and spleen of grass carp.The activities of copper-zinc superoxide dismutase,manganese superoxide dismutase,catalase,glutathione S-transferase,glutathione reductase,and glutathione peroxidase were also enhanced by supplementation with 400-600 mg/kg MOS.Furthermore,the expression of most antioxidant enzymes and their corresponding genes increased significantly with supplementation of 200-800 mg/kg MOS.mRNA and protein levels of nuclear factor erythroid 2-related factor 2 also increased following supplementation with 400-600 mg/kg MOS.In addition,supplementation with 400-600 mg/kg MOS reduced excessive apoptosis by inhibiting the death receptor pathway and mitochondrial pathway processes.Conclusions Based on the quadratic regression analysis of the above biomarkers(reactive oxygen species,malondialdehyde,and protein carbonyl)of oxidative damage in the head kidney and spleen of on-growing grass carp,the recommended MOS supplementation is 575.21,557.58,531.86,597.35,570.16,and 553.80 mg/kg,respectively.Collectively,MOS supplementation could alleviate oxidative injury in the head kidney and spleen of grass carp infected with Aeromonas hydrophila.

Dietary protein levels changed the hardness of muscle by acting on muscle fiber growth and the metabolism of collagen in sub-adult grass carp(Ctenopharyngodon idella)

Background:Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish.As a necessary nutrient for fish growth,protein accounts for the highest proportion in the fish diet and is expensive.Although our team found that the effect of protein on the muscle hardness of grass carp was probably related to an increased collagen content,the mechanism for this effect has not been deeply explored.Moreover,few studies have explored the protein requirements of sub-adult grass crap(Ctenopharyngodon idella).Therefore,the effects of different dietary protein levels on the growth performance,nutritional value,muscle hardness,muscle fiber growth,collagen metabolism and related molecule expression in grass carp were investigated.Methods:A total of 450 healthy grass carp(721.16±1.98 g)were selected and assigned randomly to six experimen-tal groups with three replicates each(n=25/replicate),and were fed six diets with 15.91%,19.39%,22.10%,25.59%,28.53%and 31.42%protein for 60 d.Results:Appropriate levels of dietary protein increased the feed intake,percentage weight gain,specific growth rate,body composition,unsaturated fatty acid content in muscle,partial free amino acid content in muscle,and muscle hardness of grass carp.These protein levels also increased the muscle fiber density,the frequency of new muscle fibers,the contents of collagen and IGF-1,and the enzyme activities of prolyl 4-hydroxylases and lysyloxidase,and decreased the activity of matrix metalloproteinase-2.At the molecular level,the optimal dietary protein increased col-lagen type Iα1(Colα1),Colα2,PI3K,Akt,S6K1,La ribonucleoprotein domain family member 6a(LARP6a),TGF-β1,Smad2,Smad4,Smad3,tissue inhibitor of metalloproteinase-2,MyoD,Myf5,MyoG and MyHC relative mRNA levels.The levels of the myostatin-1 and myostatin-2 genes were downregulated,and the protein expression levels of p-Smad2,Smad2,Smad4,p-Akt,Akt,LARP6 and Smad3 were increased.Conclusions:The appropriate levels of dietary protein promoted the growth of sub-adult grass carp and improved muscle hardness by promoting the growth of muscle fibers,improving collagen synthesis and depressing collagen degradation.In addition,the dietary protein requirements of sub-adult grass carp were 26.21%and 24.85%according to the quadratic regression analysis of growth performance(SGR)and the muscle hardness(collagen content),respectively.

Implications of vitamin D for flesh quality of grass carp(Ctenopharyngodon idella):antioxidant ability,nutritional value,sensory quality,and myofiber characteristics

Background Muscle represents a unique and complex system with many components and comprises the major edible part of animals.Vitamin D is a critical nutrient for animals and is known to enhance calcium absorption and immune response.In recent years,dietary vitamin D supplementation in livestock has received increased attention due to biological responses including improving shear force in mammalian meat.However,the vitamin D acquisition and myofiber development processes in fish differ from those in mammals,and the effect of vitamin D on fish flesh quality is poorly understood.Here,the influence of dietary vitamin D on fillet quality,antioxidant ability,and myofiber development was examined in grass carp(Ctenopharyngodon idella).Methods A total of 540 healthy grass carp,with an initial average body weight of 257.24±0.63 g,were allotted in 6 experimental groups with 3 replicates each,and respectively fed corresponding diets with 15.2,364.3,782.5,1,167.9,1,573.8,and 1,980.1 IU/kg vitamin D for 70 d.Results Supplementation with 1,167.9 IU/kg vitamin D significantly improved nutritional value and sensory quality of fillets,enhancing crude protein,free amino acid,lipid,and collagen contents;maintaining an ideal pH;and reduc-ing lactate content,shear force,and cooking loss relative to respective values in the control(15.2 IU/kg)group.Average myofiber diameter and the frequency of myofibers>50μm in diameter increased under supplementation with 782.5–1,167.9 IU/kg vitamin D.Levels of oxidative damage biomarkers decreased,and the expression of antioxi-dant enzymes and nuclear factor erythroid 2-related factor 2 signaling molecules was upregulated in the 1,167.9 IU/kg vitamin D treatment compared to respective values in the control group.Furthermore,vitamin D supplementation activated cell differentiation by enhancing the expression of myogenic regulatory factors and myocyte enhancer factors compared to that in the control group.In addition,supplementation with 1,167.9 IU/kg vitamin D improved protein deposition associated with protein synthesis molecule(target of rapamycin)signaling and vitamin D receptor paralogs,along with inhibition of protein degradation(forkhead box protein 1)signaling.Conclusions Overall,the results demonstrated that vitamin D strengthened antioxidant ability and myofiber devel-opment,thereby enhancing nutritional value and sensory quality of fish flesh.These findings suggest that dietary vitamin D supplementation is conducive to the production of nutrient-rich,high quality aquaculture products.

Sporting Usefulness Potential of Nine Local Taxa of Grasses for Lawns in the Agro-Ecological Zone with Bimodal Rainfall in Cameroon

The Cameroonian flora has a very high biodiversity that remains largely unexplored. It contains many grasses that can be used for sports lawns, but are currently underutilized. In order to contribute to the improvement of the quality of sports lawns, nine local grass taxa from the agro-ecological zone with bimodal rainfall in Cameroon were evaluated for their potential for sporting use in natural lawns. The method of the Study and Control Group for Varieties and Seeds was used to evaluate the sports lawn characteristics of the taxa. The resistance to trampling and pulling, the density of the lawn, and the aesthetic appearance, which are factors in calculating the sports index, were monitored at two sites, including the experimental space at the University of Yaounde 1 in the Center region and Kagnol 2 in the East region, from January 2017 to January 2020. The monthly lawn characteristic data allowed for the differentiation between the means and the determination of the sports index of the taxa compared to commercialized lawn varieties. The sports index of the evaluated taxa varied: Cynodon dactylon (6.989), Eleusine indica (6.338), Sporobolus natalensis (6.301), Cynodon cf Cynodon dactylon (6.257), Eragrostis tremula (5.939), Sporobolus pyramidalis (5.583), Agrostis rupestris (5.335), Axonopus compressus (4.991), and Digitaria sp. (4.544). These results show that these grass taxa have potential for sporting use in lawn mixtures at different levels of sports disciplines.

The Destruction of Diasporic White Individuals’Sense of Identity in The Grass is Singing

The importance of diaspora identity has grown in recent years as the world becomes more interconnected and diaspora individuals are increasingly involved in matters among different ethnics.The Grass is Singing by Doris Lessing is considered one of the most outstanding works of literature after World War II.Interest in ethnic identity has been heightened.The book is recognized as an introspective reflection of the spiritual crisis suffered by diaspora people and societal crises of the time.The thesis will examine the oppression imposed by dominant white group by exploring the transformation of diasporic white individuals’identity.

Soil Depth and Changes in Dry Mass and Competitive Intensity of Two C₄Grasses

The presence of grassland biomes and species cannot be predicted by examining bottom up causes such as precipitation and temperature. Top down causes including herbivory and fire seem to be major controlling aspects with other factors secondary. We examined soil depth and competitive ability of two North American C4 grasses in a greenhouse experiment. Changes in dry mass were determined and competitive intensity was calculated for both species. Species were grown separately or together in pots 30, 90, or 180 cm deep. When grown in monoculture, Schizachyrium scoparium total and belowground dry mass increased from the 30 to 90 cm depth, with no further significant increase from 90 to 180 cm. Aboveground dry mass did not increase significantly with depth. Total dry mass of Buchloe dactyloides increased significantly with depth when grown in monoculture. Aboveground dry mass increased from 30 to 90 cm depth but not from 90 to 180 cm. Belowground dry mass of B. dactyloides did not increase significantly with depth. In 180 cm pots, 53% of S. scoparium root dry mass was in the top 30 cm;74% of B. dactyloides root dry mass was in the top 30 cm. Roots of B. dactyloides were not found deeper than 90 cm. Aboveground dry mass of S. scoparium was not different in mixture or monoculture at any depth. Buchloe dactyloides aboveground dry mass in mixture was significantly lower than monoculture at the 30 cm depth, but not at 90 or 180 cm. The greatest competitive intensity was in the shallow soil pots. Soil depth could partially explain mosaics found in C4 grasslands where both species were found together with S. scoparium on deeper soils and B. dactyloides on shallower soils.

Comparative Microsatellite Analysis of Grass Carp Genomes of Two Gynogenetic Groups and the Xiangjiang River Group

The genomes of three groups of grass carp, namely the Xiangjiang River grass carp group （Xiangjiang group）, a one-generation artificially induced meio-gynogenetic grass carp group （meio-gynogenetic-1 group）, and a two-generation artificially induced meio-gynogenetic grass carp group （meio-gynogenetic-2 group）, were comparatively analyzed with microsatellite markers. Genetic polymorphism had been observed in the Xiangjiang group and most of the examined loci had more than two alleles. But the degree of genetic diversity was not very high. Although all the examined genetic loci in the analyzed individuals were in homozygous state, the genotypes of different individuals of the group were not identical in the meio-gynogenetic-1 group. In the meio-gynogenetic-2 group, not only the examined genetic loci of each individual were homozygous but also the genotypes of all the analyzed individuals of the group were the same. These results suggested that the examined meio-gynogenetic-2 group is a homozygous group and homozygous clone could be produced by continuous artificial induction of gynogenesis for two generations. It was found that the polymorphism existed not only at the allele level but also at the locus level; many alleles of the microsatellite loci and some of the microsatellite loci had been lost during the process of artificial gynogenesis. Therefore, both protection of the diversity of natural grass carp resource and selection of homozygous traits with desired economic genotypes are very important aspects for grass carp breeding.

Comparative Analysis on Growth and Morphology in Yangtze River ♀,Zhujiang River ♂ and Their F_1 Hybrids of Juvenile Grass Carp

[ Objective] The aim of this study was to investigate the growth and morphological characteristics of juvenile hybrids of grass carp. [Method] Three inbred generations of YR （Yangtze River stock ♀×Yangtze River stock ♂ ）, ZR （Zhujiang River stock ♀ ×Zhujiang River stock♂ ） and hybrids F1 （ Yangtze River stock ♀ × Zhujiang River stock ♂ ） were established, and their growth or morphological data were also measured. [ Result] The orders of body weight, standard length and absolute growth rate were F1 〉 ZR 〉 YR. No significant difference was found in body weight or standard length of 50 day-old generations （ P〉0. 05）, while there was an extremely significantly difference in those of 170 day-old generations （ P 〈0.01 ）. However, the absolute growth rate of F1 was 20.00% and 50.00% higher than that of ZR and YR respectively, and no significant difference was found between F1 and ZR （ P 〉 0.05）, but significant difference between F1 and YR （ P 〈 0.05）. F1 showed a significant hybrid vigor with rate of 20.09%. There was no significant difference among three inbred generations in standard length/total length （ P 〉 0.05）, while significant difference in head length/total length, body height/standard length and body width/standard length （ P 〈 0.05）, which indicated that F1 had the characteristics of shorter head, higher and wider body. [ Conclusion]F1 has advantages in growth performance and morphological characteristics.