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1.
Aimin Wang Yan Wang Zhifeng Gu Sifa Li Yaohua Shi Ximing Guo 《Marine biotechnology (New York, N.Y.)》2011,13(2):275-283
The pearl oyster, Pinctada martensii, is the primary species used for the aquaculture production of marine pearls in China and Japan. Genetic tools and resources
are needed to study the genome of this species and to understand the molecular basis of development, growth, host defense,
pearl formation, and other important traits. In this study, we developed a set of expressed sequence tags (ESTs) for P. martensii. We constructed cDNA libraries from adult tissues and sequenced 7,128 ESTs. Clustering analysis identified 788 contigs (covering
5,769 ESTs) and 1,351 singletons, yielding a total of 2,139 unique genes. Of these unique genes, only 935 had significant
(E-value ≤ 0.005) hits in GenBank, and the remaining 1,204 (56.3%) were novel. Most of the known genes are related to cellular
structure, protein binding, and metabolic processes. Putative host-defense genes (86) were identified including C-type lectin,
ferritin, polyubiquitin, proteases, protease inhibitors, scavenger receptors, heat shock proteins, and RAS oncogenes. The
EST sequences developed in this study provide a valuable resource for future efforts on gene identification, marker development,
and studies on molecular mechanism of host defense in pearl oysters. 相似文献
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The asymptotic quasi‐likelihood method is considered for the model yt = ft(θ) + Mt, t = 0,1, …,T where ftθ) is a linear predictable process of the parameter of interest θ, Mt is a martingale difference, and the nature of E(Mt2 | ℱt–1) is unknown. This paper is concerned with the limiting distribution of the asymptotic quasi‐score function of such a model. Confidence intervals and hypothesis testing of θ is derived from the limiting distribution. Comparison is made between the estimates obtained through this method and those obtained through the least squares method. 相似文献
4.
Sifa Mvoi Yan-Xia Lin Riccardo Biondini 《Biometrical journal. Biometrische Zeitschrift》1998,40(1):57-78
Consider a model yt = ft(θ) + Mt, 0 ⩽ t ⩽ T where θ∈ Θ in an unknown parameter, ft(θ) is a linear predictable process, Mt is a martingale difference, and the nature of E(M2t/ℱt—1) is unknown. This paper presents an estimating procedure for θ based on the asymptotic quasi-likelihood methodology. Conditions under which the asymptotic quasi-likelihood estimate converges to the true parameter θ0 are discussed. This method is applied to several simulated examples, and estimates of the unknown parameter are obtained by means of a two-stage technique. Comparison is made between the estimates obtained via this method and those obtained via the ordinary least squares method. Discussion is provided on the application of the model. 相似文献
5.
Genome comparison has shed light on many fields of both basic and applied research, including the study of species phylogeny. Grass carp (Ctenopharyngodon idella) belongs to Cyprinidae, the largest freshwater fish family; but which subfamily it belongs to remains a controversial issue. In this study, the complete mitochondrial genome (mitogenome) sequence of grass carp was determined and phylogenetic analyses of all mitochondrial protein-coding genes and a nuclear gene (RAG 2) were conducted to explore the evolutionary relationship of grass carp with other cyprinid species. The mitogenome of grass carp is 16,609 bp in length. As with most other vertebrates, it contains the same gene order and an identical number of genes or regions, including 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one putative control region. Phylogenetic analyses using two different datasets (mitochondrial and nuclear) and three different computational algorithms (Bayesian, MP and ML) all revealed two distinct groups with high statistical support, indicating that Cyprininae and Leuciscinae are two separate, valid subfamilies. Importantly, our phylogenetic result provides strong molecular evidence in support of the placement of Ctenopharyngodon in Leuciscinae rather than in Cyprininae. 相似文献
6.
Anyuan He Yongju Luo Hong Yang Liping Liu Sifa Li Chenghui Wang 《Molecular biology reports》2011,38(3):2015-2021
Cichlid fishes have played an important role in evolutionary biology and aquaculture industry. Nile tilapia (Oreochromis niloticus), blue tilapia (Oreochromis aureus) and Mozambique tilapia (Oreochromis mossambicus), the useful models in studying evolutionary biology within Cichlid fishes, are also mainly cultured species in aquaculture
with great economic importance. In this paper, the complete nucleotide sequence of the mitochondrial genome for O. niloticus and O. aureus were determined and phylogenetic analyses from mitochondrial protein-coding genes were conducted to explore their phylogenetic
relationship within Cichlids. The mitogenome is 16,625 bp for O. niloticus and 16,628 bp for O. aureus, containing the same gene order and an identical number of genes or regions with the other Cichlid fishes, including 13 protein-coding
genes, two rRNA genes, 22 tRNA genes and one putative control region. Phylogenetic analyses using three different computational
algorithms (maximum parsimony, maximum likelihood and Bayesian method) show O. niloticus and O. mossambicus are closely related, and O. aureus has remotely phylogenetic relationship from above two fishes. 相似文献
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Long-term static leaching experiments were conducted to investigate characteristics of magnesium phosphate cement (MPC) solidified/stabilized Zn-contaminated soil under impact of acid rain. Effects of initial pH values of acid rain, binder agent types and compositions, as well as curing age on strength and leaching characteristics of the sample were analyzed. Standard sand was used as raw material, with the content of cement at 15%. Our study used two types of MPC with MgO/KH2PO4(M/P) ratio of 3:1 and 6:1 (respectively referred to as M3 and M6), and also ordinary Portland cement with content at 15% (referred to as C15) as test control. Experimental results show that acid rain with pH = 2 has the greatest weakening effect on unconfined compressive strength (qu) of the sample, while with pH = 4 and 7 such weakening effects on qu are similar. Research findings also indicate that M6 is the most effective in immobilizing Zn-spiked soils, M3 is next and C15 is the least. The effect of Zn2+ on hydration of MPC is much lower than that of C15. Precuring method can improve qu of the MPC-solidified samples and its resistance to acid rain. Compared with non-renewal, replacing acid rain leachant at designated intervals decreases qu of the sample. 相似文献
8.
Chenghui Wang Sifa Li Cuizhang Fu Xiaoling Gong Len Huang Xiao Song Yan Zhao 《Biological invasions》2009,11(2):389-399
Chinese mitten crab (Eriocheir sinensis), a native species in China, has populated Continental Europe and North America since 1912. In this paper, the nucleotide
variation in the fragments of mitochondrial COII (693 bp), Cytb (766 bp), and nucleotide ITS (706 bp) was analyzed in native
(Yantgze, Yellow, and Liaohe Rivers in China) and colonized (Elbe, Rhine, and Thames Rivers in Europe, and San Francisco Bay
in North America) populations of the Chinese mitten crab. The major findings are as follows. First, the genetic variability
in the native populations is higher than that in the colonized European and North American populations, with the exception
of the Elbe River population, which possesses a similar level of variability with the native populations. Second, a remarkable
loss of singletons has been associated with the colonization of Chinese mitten crabs. Third, the AMOVA and F
ST results demonstrate that there are no significant genetic differentiations among the populations from the three continents,
but there is a significant differentiation between pairwise populations within and among continents. Fourth, it is found that
expansion-drift and gene flow pattern are involved in the European populations. The neutrality test and R
2 statistics suggest that a moderate founder population exists in the colonized populations, and only the Yangtze River population
has undergone a recent population expansion. Finally, the results demonstrate that the European populations originate from
multiple rivers in China on multiple occasions. The San Francisco population originates from both the native Chinese populations
and the colonized European populations, most likely the Thames population. 相似文献
9.
本文根据1976-1977年的调查研究,讨论姚江鱼类种群生态特点,并参照对杭州青山水库的一些调查及中国科学院水生生物研究所对武昌东湖的研究,估量姚江的鱼产力,旨在为拟定增产措施提供科学根据。
相似文献
10.
The northern pike (Esox lucius L.), an important predatory freshwater species, is undergoing significant population decline. In this study, 18 novel polymorphic microsatellite loci were isolated and used for assessing genetic variation in the Chinese Ulungur and Hungarian Balaton populations of the species. The number of alleles ranged from 2 to 13, observed heterozygosity from 0.154 to 0.920 and expected heterozygosity from 0.145 to 0.921, thereby indicating the specific usefulness of these suites of markers for investigating genetic variability. 相似文献