杧果成花过程碳水化合物和可溶性蛋白含量的变化

以“南多美”和“椰香”两个杧果品种为试验材料,调查其物候期、抽梢率和成花率,选取花芽分化前后不同发育时期的顶芽,进行碳水化合物和可溶性蛋白含量的测定比较,探讨不同品种杧果成花过程中碳水化合物和可溶性蛋白的变化,为杧果花芽分化调控提供依据。结果表明,“南多美”和“椰香”在成花的各个时期,果糖、麦芽糖含量持续积累,其含量均以“南多美”含量高于“椰香”。两个品种的葡萄糖变化趋势不同,“南多美”呈先升后降,而“椰香”呈不断升高的趋势;蔗糖在花芽分化早期消耗,后期大量积累。两个品种的淀粉含量在成花过程中趋于稳定,可溶性蛋白不断积累;碳水化合物与可溶性蛋白含量的比值在成花早期增加,后期降低。“南多美”成花率显著高于“椰香”,且成花率与果糖、麦芽糖和可溶性蛋白含量均显著正相关,相关系数分别为0.816、0.506和0.456。说明杧果成花过程中碳水化合物和可溶性蛋白的积累有利于花芽分化,进入花芽分化期后,两者比值以易成花的“南多美”显著高于难成花的“椰香”。

Identification and quality evaluation of Lepidium meyenii. (Maca) based on gas chromatographic analysis of its essential oils from roots

Lepidium meyeniiWalp. （Maca）, a perennial herbaceous plant with narrow distdbution in the Andean region, was cultivated by local residents as early as 1600 B.C. It has high nutritional values and multiple medicinal effects. In recent years the plant source of Maca has been greatly scarce since Maca products are increasingly becoming popular in the world. This makes the study urgent on the identification and quality evaluation of Maca materials. In present work, four Mace samples of different origins or handlings and three other natural plants, including radish, odental ginseng and American ginseng, were investigated. Their essential oils （steam distillates） of the hypogeal parts were weighed and analyzed by GC/MS. Through comparison of the characteristics of their chromatograms, it was found that the essential oil of Maca had unique GC/MS behaviors, and the characteristic peaks produced by the major essential oil components （Phenylacetonitrile, Benzaldehyde, 3-Methoxyphenylacetonitrile, etc） were distinct. Furthermore, the chromatograms of several Maca samples showed a similar qualitative pattern except for some differences in the quantitative composition, and the percentage of total essential oils in the samples varied from 0.88 % to 1.59 %. These behaviors and technologies can be applied to the identification of Maca materials in the markets and be a supplement to assess the quality of Maca matedals.

Predictive ability of genomic selection models for breeding value estimation on growth traits of Pacific white shrimp Litopenaeus vannamei

Genomic selection(GS)can be used to accelerate genetic improvement by shortening the selection interval.The successful application of GS depends largely on the accuracy of the prediction of genomic estimated breeding value(GEBV).This study is a fi rst attempt to understand the practicality of GS in Litopenaeus vannamei and aims to evaluate models for GS on growth traits.The performance of GS models in L.vannamei was evaluated in a population consisting of 205 individuals,which were genotyped for 6 359 single nucleotide polymorphism(SNP)markers by specifi c length amplifi ed fragment sequencing(SLAF-seq)and phenotyped for body length and body weight.Three GS models(RR-BLUP,Bayes A,and Bayesian LASSO)were used to obtain the GEBV,and their predictive ability was assessed by the reliability of the GEBV and the bias of the predicted phenotypes.The mean reliability of the GEBVs for body length and body weight predicted by the dif ferent models was 0.296 and 0.411,respectively.For each trait,the performances of the three models were very similar to each other with respect to predictability.The regression coeffi cients estimated by the three models were close to one,suggesting near to zero bias for the predictions.Therefore,when GS was applied in a L.vannamei population for the studied scenarios,all three models appeared practicable.Further analyses suggested that improved estimation of the genomic prediction could be realized by increasing the size of the training population as well as the density of SNPs.

Effect of Dopamine Injection on the Hemocyte Count and Prophenoloxidase System of the White Shrimp Litopenaeus vannamei

Effects of dopamine injection on the hemocyte count, phenoloxidase activity, serine proteinase activity, proteinase in-hibitor activity and α2-macroglobulin-like activity in L. vannamei were studied. Results showed that dopamine injection resulted in a significant effect on the parameters measured (P < 0.05), while no significant difference was observed in the control group (0.85% NaCl). In the experimental groups,the hemocyte count reached the minimum in 3 h;granular and semi-granular cells became stable after 12 h and hyaline cells and the total hemocyte count became stable after 18 h. Phenoloxidase activity reached the minimum in 6 h, and then became stable after 9 h. Serine protease activity and proteinase inhibitor activity reached the minimum in 3 h, and α2-macro-globulin-like activity reached the maximum in 3 h,and all the three parameters became stable after 12 h. The results suggest that the activating mechanisms of the proPO system triggered by dopamine are different from those triggered by invasive agents or sponta-neously activated under a normal physical condition.

EST-derived SNP discovery and selective pressure analysis in Pacific white shrimp(Litopenaeus vannamei)

Pacific white shrimp has become a major aquaculture and fishery species worldwide.Although a large scale EST resource has been publicly available since 2008,the data have not yet been widely used for SNP discovery or transcriptome-wide assessment of selective pressure.In this study,a set of 155 411 expressed sequence tags(ESTs) from the NCBI database were computationally analyzed and 17 225 single nucleotide polymorphisms(SNPs) were predicted,including 9 546 transitions,5 124 transversions and 2 481 indels.Among the 7 298 SNP substitutions located in functionally annotated contigs,58.4%(4 262) are non-synonymous SNPs capable of introducing amino acid mutations.Two hundred and fifty nonsynonymous SNPs in genes associated with economic traits have been identified as candidates for markers in selective breeding.Diversity estimates among the synonymous nucleotides were on average 3.49 times greater than those in non-synonymous,suggesting negative selection.Distribution of non-synonymous to synonymous substitutions(Ka/Ks) ratio ranges from 0 to 4.01,(average 0.42,median 0.26),suggesting that the majority of the affected genes are under purifying selection.Enrichment analysis identified multiple gene ontology categories under positive or negative selection.Categories involved in innate immune response and male gamete generation are rich in positively selected genes,which is similar to reports in Drosophila and primates.This work is the first transcriptome-wide assessment of selective pressure in a Penaeid shrimp species.The functionally annotated SNPs provide a valuable resource of potential molecular markers for selective breeding.

Species Composition and Gear Characteristics of the Macrobrachium Fishery of the Cross River Estuary,Nigeria

The Cross River Estuary,Nigeria,is an important shrimping area for artisanal fishermen of the coastal communities.The multi-species Macrobrachium fishery is exploited with three main gears,namely beach seine,push net and trap.Studies on species composition of this fishery recorded thirteen shrimp species,one swimming crab (Callinectes amnicola) and two fish species (Eleotris sp.and Pellonula leonensis).The shrimp species identified included Macrobrachium macrobrachion (83.39% and 55.69% by number and weight,respectively),M.vollenhovenii (9.66% and 37.18%),M.equidens (3.8% and 2.87%),juveniles-sub-adults of Penaeus notialis (1.11% and 1.3%),M.dux,M.felicinum,Palaemonetes africanus,Palaemon maculatus,Palaemon elegans,Desmocaris sp.,Leander sp.,Nematopalaemon hastatus and Alpheus pontederiae.While the selectivity index for trap was 0.25,beach seine and push net had a lower index of 0.063.The results present the first comprehensive and representative report for the Estuary shrimp fishery and will assist in the management of the biodiversity of this ecosystem.