Speciation and Phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: Analysis of the Cytochrome b Gene of mtDNA from Diverse Populations

Gao-Yan Li, Xu-Zhen Wang, Ya-Hui Zhao, Jie Zhang, Chun-Guang Zhang, and Shun-Ping He (2009) Speciation and phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: analysis of the cytochrome b gene of mtDNA from diverse populations. Zoological Studies 48(4): 569-583. The cyprinid fish Opsariichthys bidens Gunther is distributed in all major river systems of continental East Asia, and represents an attractive model for phylogeographic studies among cyprinid species or within a given species. In this study, we investigated the phylogeographic and demographic history of this species, using partial sequences of the cytochrome (cyt) b gene in mitochondrial (mt)DNA. Fish samples were collected from almost all major river systems where O. bidens is distributed in China. Sequence analysis showed remarkably high polymorphism, with 125 haplotypes in the 234 specimens examined, and with 89.8% of haplotypes occurring in only 1 specimen. A neutrality test indicated that some groups were not at mutation-drift equilibrium, suggesting a past population expansion. These results were supported by a mismatch distribution analysis. Based on our analysis, O. bidens consists of 4 groups belonging to 2 clades. The divergence time of the 2 clades was estimated to be 11.06-8.04 my. This value corresponds to the time of the 2nd uplift of the Qinghai-Tibet Plateau, the emergence of the East Asian monsoon, and the Epoch-6 Event. A two species scheme is proposed. http://zoolstud.sinica.edu.tw/Journals/48.4/569.pdf

The complete mitochondrial genome of the Chinese hook snout carp Opsariichthys bidens (Actinopterygii : Cyprinifonnes) and an altemative pattem of mitogenomic evolution in vertebrate

The complete mitochondrial genome sequence of the Chinese hook snout carp, Opsariichthys bidens, was newly determined using the long and accurate polymerase chain reaction method. The 16,611-nucleotide mitogenome contains 13 protein-coding genes, two rRNA genes (12S, 16S) 22 tRNA genes, and a noncoding control region. We use these data and homologous sequence data from multiple other ostariophysan fishes in a phylogenetic evaluation to test hypothesis pertaining to codon usage pattern of O. bidens mitochondrial protein genes as well as to re-examine the ostariophysan phylogeny. The mitochondrial genome of O. bidens reveals an alternative pattern of vertebrate mitochondrial evolution. For the mitochondrial protein genes of O. bidens, the most frequently used codon generally ends with either A or C, with C preferred over A for most fourfold degenerate codon families; the relative synonymous codon usage of G-ending codons is greatly elevated in all categories. The codon usage pattern of O. bidens mitochondrial protein genes is remarkably different from the general pattern found previously in the relatively closely 9 related zebrafish and most other vertebrate mitochondria. Nucleotide bias at third codon positions is the main cause of codon bias in the mitochondrial protein genes of O. bidens, as it is biased particularly in favor of C over A. Bayesian analysis of 12 concatenated mitochondrial protein sequences for O. bidens and 46 other teleostean taxa supports the monophyly of Cypriniformes and Otophysi and results in a robust estimate of the otophysan phylogeny. (C) 2007 Published by Elsevier B.V.

Population dynamics and maturation cycle of Camallanus cotti (Nematoda : Camallanidae) in the Chinese hooksnout carp Opsariichthys bidens (Osteichthyes : Cyprinidae) from a reservoir in China

The seasonal population dynamics and maturation cycle of the nematode Camallanus cotti in the posterior intestine of Chinese hooksnout carp Opsariichthys bidens have been studied in the Danjiangkou Reservoir of the Hubei Province in central China from September 2004 to November, 2005. The overall prevalence, mean abundance and intensity of C cotti among fish sampled (n = 700 fish) were 47%, 2.29 +/- 12.38 ( +/- S.D.) and 1-307 (average 4.89 +/- 17.74), respectively. The overall sexual ratio of female to male nematodes (excluding L3 and L4 juveniles) was 1.17:1. Statistical results showed weakly positive correlations betweerl fish length and the number of nematodes per host. The dynamics of infection of the nematode exhibited significant seasonal pattern in changes in mean abundance. A similar pattern was found for changes in nematode prevalence, although this was not statistically significant. Higher levels of infection were observed among fish sampled in summer months and the lower in the winter. Neither the prevalence nor the abundance of the parasite was significantly different between male and female hosts. The pattern of frequency distribution of the parasite in the host was found to be over-dispersed throughout the sampling period. In addition, studies on the development and maturation of the parasite in O. bidens revealed that development (maturation), recruitment of the next generation, and reproduction may be continuous year-round, although reproduction may peak during the winter. (c) 2007 Elsevier B.V. All rights reserved.

丹江口水库马口鱼肠道寄生蠕虫群落结构

从2004年8月到2005年11月在丹江口水库调查的847尾马口鱼(Opsariichthys bidens)肠道内共检得寄生蠕虫14种,其中线虫7种,复殖吸虫4种,棘头虫2种,绦虫1种。该寄生蠕虫群落以广谱性寄生虫为主。杜父鱼驼形线虫(Camallanus cotti)、头槽绦虫(Bothriocephalus acheilognathi)、卡斯杆咽线虫(Rhabdochona cascadilla)和木村小棘吻虫(Micracanthorhynchina motomurai)为群落的核心种。研究结果

A new species of Allocreadium (Trematoda : Allocreadiidae) from freshwater fishes in the Danjiangkou Reservoir in China

A new species of Allocreadium, Allocreadium danjiangensis n. sp., is described from the intestine of several species of freshwater fish, including Abbottina rivularis (Basilewsky, 1855), Sarcocheilichthys nigripinnis nigripinns (Gunther, 1873), Gnathopogon argentatus (Sauvage et Dabry 1874), Opsariichthys uncirostris bidens (Gunther, 1873), and Erythroculter mongolicus mongolicus (Basilewsky, 1855) (Cyprinidae) from the Danjiangkou Reservoir in central China. The main morphological characters of the new species are as follows: vitelline follicles numerous, extending from the level of acetabulum to posterior extremity, distributed over both sides around the ceca; cirrus sac relatively large, developed, lying obliquely anterior to the acetabulum, extending from the level of the intestinal bifurcation to the central level of acetabulum, and overlapping left or right cecal; and ovary much smaller than testes, generally close to or even overlapping the anterior border of anterior testis. Observation by scanning electron microscopy shows only 2 kinds of tegumental formations, i.e., papillae and tubercles, instead of 3 types of tegumental formations, i.e., papillae, bosses, and minute sensor receptors observed on other species of the Allocreadiidae. The tegumental striations of the present species vary on the different parts of the body. In addition, a new structure, identified as the "groove" with a tonguelike tubercle, was observed on the inner wall of acetabulum.

Identification of novel SINEs from Cyprinidae and their evolutionary significance

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through BLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-B. The Zb-SINE-A group comprises subfamilies of -Al--A5, and the Zb-SINE-B group is a dimer of the tRNA(Ala)-derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5 end tRNA-derived region, a tRNA-unrelated region and a 3 end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 6p. Zb-SINEs account for as much as 0.1% of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNA(Ala) gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA(Ala) sequence or a tRNA(Ala)-like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

矿山环境中锑的表生地球化学研究—以贵州半坡锑矿区为例

锑(antimony，Sb)是一种典型的毒害重金属元素。我国作为世界上最主要的锑生产国，有关锑的表生地球化学及锑污染防治研究还很薄弱。贵州省位于我国西南低温成矿域中心，具有高Sb地球化学背景值，是我国重要的锑工业基地，境内分布着大量Sb矿床，锑矿储量居全国第四位。贵州又地处我国西南喀斯特中心区域，岩溶地貌极其发育，生态环境脆弱。由于大规模锑矿资源的开采利用，锑矿区土壤和水体中Sb污染十分突出，并通过水体或食物链对矿区及流域居民健康形成潜在威胁。因此，研究矿山环境中Sb的表生地球化学对于认识Sb污染的环境效应和寻求Sb污染修复方式具有至关重要的意义。 本文以贵州半坡大型锑矿区为研究对象，系统研究了Sb在矿区岩石、固体废弃物、土壤、水体和植物体等表生环境介质中的分布、迁移、富集规律与赋存机制，阐明了矿区Sb的表生地球化学过程规律，评价了矿区围岩、（废）矿石和尾矿砂等样品的产酸潜力，筛选出新的锑潜在超富集植物和超耐受性植物，并获得以下主要认识： （1） 独山半坡锑矿区是典型高锑地质地球化学背景区，不仅矿石中Sb含量很高，而且围岩中Sb含量也远高于上地壳Sb的平均含量。辉锑矿是锑的主要载体和释放源。 （2） 在固体废弃物中，冶炼废渣中Sb含量最高，其次为废石堆和尾砂库。废石中元素特征基本与围岩一致，继承了围岩的元素特征，而尾矿砂由于破碎、浮选过程的改造，其元素含量特征与围岩存在差异。尾砂砂中Sb以中层最富，底层和表层依次降低，与Fe、Al矿物的分布特征相似，这种分布模式主要受氧化还原条件、雨水淋滤、Fe/Al矿物吸附机制等因素控制。尾矿砂中不同相态的锑含量依次为残渣态>碳酸盐结合态>有机物结合态>可交换态>铁锰氧化物结合态，其中生物易利用态Sb的空间分布特征与总Sb分布特征一致。 （3） 所有的（废）矿石样品都具有潜在产酸能力，需要采取必要的措施抑制酸性矿山排水的产生。尾矿砂没有产酸潜力，这与矿石在选冶过程中加入石灰处理和S含量过低等原因有关，这种碱性环境可能有利于锑的表生地球化学活化和迁移。 （4） 研究区土壤受到严重锑污染，土壤中Sb含量高达51~7369 mg/kg，且随深度增加而逐渐降低，底层含量与对照区相近。这种高含量的Sb可能是与锑矿化有关的裸露岩石和土壤的自然风化淋滤过程和采矿、冶炼活动等造成的。研究区土壤中不同相态的Sb含量依次为残渣态>铁/锰氧化物结合态>碳酸盐结合态>有机物/硫化物结合态>可交换态。土壤中Sb的生物有效性很低。土壤中Sb的迁移与As密切相关。 （5） 研究区水体为SO4/HCO3-Ca型，水体中的Sb以溶解态、悬浮态和沉积物形式存在，并通过吸附-解吸附和水流推移方式进行迁移。洪水期和枯水期水体中Sb的扩散迁移机制存在差异，洪水期研究区内水体对岔河下游水体污染危害更大。在枯水期，岔河水体中溶解态Sb含量和沉积物中Sb含量存在显著正相关关系，表明枯水期沉积物和水体界面间达到物质交换平衡。水体的氧化还原条件和pH值控制着水体中Sb的存在形态。沉积物中不同相态Sb含量依次为残渣态>碳酸盐结合态，铁锰氧化物结合态>可交换态，有机物/硫化物结合态。研究区水体中Sb主要受矿区采矿、选冶活动的强烈影响。水体中硫同位素示踪研究发现，岔河下游水体中59%的S来自于矿山硫源的贡献，表明矿山活动严重影响到岔河下游水体水质。 （6） 植物对土壤中Sb的吸收与植物部位和种类有关。大体上地下部分>地上部分，且根>叶片>茎。在农作物中，白菜>甘蓝>辣椒和稻谷。研究发现，土荆芥(Chenopodium ambrosioides Linn.)是新的Sb潜在超富集植物，鬼针草(Bidens pilosa Linn.)、一年蓬(Erigeron annuus (Linn.) Pers.)、佛甲草(Sedum lineare Thun)、凹叶景天(Sedum emarginatum Migo)、灰灰菜(Chenopodium album Linn.)和鼠麹草(Gnaphalium affine D. Don)也能大量富集Sb，并有很强耐受性。 （7） 研究区这种特殊的高Sb地质环境和人为活动的影响，导致表生环境中Sb的高度富集，造成农作物、水体中Sb含量极高，通过食物链和水体严重影响当地居民的身体健康。