池蝶蚌Sox2 基因在不同组织及不同月龄精巢中的表达

Sox 基因家族在胚胎发育过程和性别分化中起重要作用, 为研究池蝶蚌中Sox 基因的功能, 以人SRY基因HMG-box 保守区的序列设计简并引物, 以雌、雄池蝶蚌基因组DNA 和精巢cDNA 为模板进行扩增, 获得了2 个不完全相同的序列, 分别为DNA-HMG1、DNA-HMG2 和cDNA-HMG, 长度均为220 bp, 编码73个氨基酸。与人等物种Sox1、Sox2、Sox3 及Sox14 有很高的同源性, 雌雄个体之间没有序列差异性。采用RACE-PCR 扩增获得了池蝶蚌性腺Sox2 部分cDNA 片段, 长度为1774 bp, 该序列核苷酸与欧洲帽贝的SoxB和人类的Sox2 的同源性最高; 在部分开放阅读框249 个氨基酸残基中, 具有Sox 家族典型的HMG-box 结构域, 与人类、小鼠、原鸡和斑马鱼等Sox2 的HMG-box 同源性为98%。为了解该基因在各组织中的表达情况,采用实时荧光定量PCR 方法分析了外套膜、闭壳肌、鳃、肠、肝、肾、精巢和卵巢在内的8 种组织hs-Sox2的表达情况, 结果显示, hs-Sox2 基因在8 种组织中均有表达, 其中在肾脏中的表达量最高, 其次是肠与闭壳肌, 在雄性性腺中的表达量明显高于雌性性腺, 在肝脏中的表达量最低; 为了解hs-Sox2 在不同性腺发育时期的表达情况, 采用实时荧光定量PCR 方法分析了5 个不同月龄的精巢组织中hs-Sox2 的表达情况, 结果显示在39 月龄性腺的表达量最高, 其次是16 月龄性腺, 63 月龄蚌中的表达量最少。以上结果表明, hs-Sox2 基因可能参与了池蝶蚌精巢的发育及功能的维持。       

cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucata

Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca(2+)-binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca(2+)-dependent electrophoretic shift, Ca(2+)-binding activity and significant Ca(2+)-induced conformational changes. Ca(2+)-dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism.     

Molecular cloning and characterization of perlucin from the freshwater pearl mussel, Hyriopsis cumingii

Perlucin is an important functional protein that regulates shell and pearl formation. In this study, we cloned the perlucin gene from the freshwater pearl mussel Hyriopsis cumingii, designated as Hcperlucin. The full-length cDNA transcribed from the Hcperlucin gene was 1460 bp long, encoding a putative signal peptide of 20 amino acids and a mature protein of 141 amino acids. The mature Hcperlucin peptide contained six conserved cysteine residues and a carbohydrate recognition domain, similar to other members of the C-type lectin families. In addition, a “QPS” and an invariant “WND” motif near the C-terminal region were also found, which are extremely important for polysaccharide recognition and calcium binding of lectins. The mRNA of Hcperlucin was constitutively expressed in all tested H. cumingii tissues, with the highest expression levels observed in the mantle, adductor, gill and hemocytes. In situ hybridization was used to detect the presence of Hcperlucin mRNA in the mantle, and the result showed that the mRNA was specifically expressed in the epithelial cells of the dorsal mantle pallial, an area known to express genes involved in the biosynthesis of the nacreous layer of the shell. The significant Hcperlucin mRNA expression was detected on day 14 post shell damage and implantation, suggesting that the Hcperlucin might be an important gene in shell nacreous layer and pearl formation. The change of perlucin expression in pearl sac also confirmed that the mantle transplantation results in a new expression pattern of perlucin genes in pearl sac cells that are required for pearl biomineralization. These findings could help better understanding the function of perlucin in the shell and pearl formation.     

Characterization of cyclophilin D in freshwater pearl mussel (Hyriopsis schlegelii)

Cyclophilin D (referred to as HsCypD) was obtained from the freshwater pearl mussel (Hyriopsis schlegelii).The full-length cDNA was 2 671 bp,encoding a protein consisting of 367 amino acids.HsCypD was determined to be a hydrophilic intracellular protein with 10 phosphorylation sites and four tetratricopeptide repeat (TPR) domains,but no signal peptide.The core sequence region YKGCIFHRIIKDFMVQGG is highly conserved in vertebrates and invertebrates.Phylogenetic tree analysis indicated that CypD from all species had a common origin,and HsCypD had the closest phylogenetic relationship with CypD from Lottia gigantea.The constitutive mRNA expression levels of HsCypD exhibited tissue-specific patterns,with the highest level detected in the intestines,followed by the gonads,and the lowest expression found in the hemocytes.     

Cloning and expression of a pivotal calcium metabolism regulator: calmodulin involved in shell formation from pearl oyster (Pinctada fucata)

The shells of bivalves are mainly composed of calcium carbonate, a product of calcium metabolism. In the process of shell formation, the uptake, transport and recruitment of calcium ion are highly regulated and involved in many factors. Among these regulatory factors, calmodulin (CaM), a pivotal multifunction regulator of calcium metabolism in nearly all organisms, is thought to play an important role in the calcium metabolism involved in shell formation. In this study, a full-length CaM cDNA was isolated from the pearl oyster (Pinctada fucata). The oyster calmodulin encodes a 16.8 kDa protein which shares high similarity with vertebrate calmodulin. The oyster CaM mRNA shows the highest level of expression in the gill, a key organ involved in calcium uptake in oyster calcium metabolism. In situ hybridization results revealed that oyster CaM mRNA is expressed at the folds and the outer epithelial cells of the dorsal region of the mantle, suggesting that CaM is involved in regulation of calcium transport and secretion. Oyster CaM also showed a typical Ca2+ dependent electrophoretic shift characterization and calcium binding activity. Taken together, we have identified and characterized a pivotal calcium metabolism regulator of the oyster that may play an important role in regulation of calcium uptake, transport and secretion in the process of shell formation.     

基于转录组的池蝶蚌系统发育及其遗传分析

池蝶蚌(Hyriopsis schlegelii)和三角帆蚌(Hyriopsis cumingii)的亲缘关系一直存在争议,为了更深入地对淡水珠蚌进行系统发育分析,研究对池蝶蚌及其3个近缘物种三角帆蚌、褶纹冠蚌(Cristaria plicata)和背角无齿蚌(Anodonta woodiana)的转录组进行了比较分析。对它们共有单拷贝同源基因进行多序列联配后计算这4种淡水珠蚌之间的遗传距离,结果表明池蝶蚌和三角帆蚌的遗传距离只有0.00746(小于1%),而其他淡水珠蚌之间的遗传距离几乎是它的10倍(平均大于6%)。系统发育分析表明,小方蚌亚科与无齿蚌亚科大约在5144万年前发生分歧,而池蝶蚌和三角帆蚌发生分化的时间大约在424万年前。进一步的遗传差异分析鉴定了池蝶蚌转录组中的特有基因,其中KEGG通路富集的结果表明这些基因主要富集在免疫细胞膜分子和蛋白消化吸收等通路上。同时, GO注释结果表明有很多特有基因与池蝶蚌的优良性状相关,如与发育相关的生长发育、系统发育和动物器官发育等生物学过程,及与免疫相关的免疫系统过程、抗原处理和呈递等生物学过程。以上结果表明,池蝶蚌和三角帆蚌具有更近...     

池蝶蚌HsPif基因的克隆及表达分析

为了探究池蝶蚌(Hyriopsis schlegelii)酸性基质蛋白Pif基因的基本功能,研究通过RACE-PCR技术首次在池蝶蚌中获得了Pif基因的cDNA全长序列,命名为HsPif,其全长为3457 bp, 5′端非翻译区(5′UTR)为485 bp,3′端非翻译区(3′UTR)为363 bp,开放阅读框(ORF)3072 bp,共编码1023个氨基酸,生物信息学分析结果显示HsPif蛋白含有一个von-Willebrand因子A型结构域和三个几丁质结合结构域;氨基酸组成成分结果表明天冬氨酸含量最高,组氨酸含量最低; HsPif蛋白亲水指数为–0.566,为亲水蛋白。构建系统进化树分析显示Pif基因保守性较高,与三角帆蚌(Hyriopsis cumingii)Pif相似度最高,且与其他贝类在同一个大支上。组织荧光定量PCR结果表明:HsPif基因主要在外套膜中表达;分子原位杂交显示杂交反应主要在外套膜上皮细胞发生。进行植核手术后进行qPCR检测HsPif基因的表达量变化,实验结果表明, HsPif基因可能与珍珠层的分泌有关,有助于进一步了解珍珠形成的机制,为珍珠养殖提供参考。     

Cloning,differential tissue expression of a novel hcApo gene,and its correlation with total carotenoid content in purple and white inner-shell color pearl mussel Hyriopsis cumingii

As a molecular carrier and storage protein, apolipoprotein (Apo) mediates the intracellular uptake of lipids, proteins, vitamins and carotenoids. In this study, we identified a novel Apo gene, designated hcApo, from the freshwater pearl mussel Hyriopsis cumingii. The complete hcApo cDNA consists of 4104 nucleotides with an open reading frame encoding 1155 amino acid residues. The hcApo protein contains a conserved lipoprotein N-terminal domain (LPD-N) that is a characteristic of the large lipid transfer protein (LLTP) superfamily. The hcApo mRNA is constitutively expressed in a wide range of tissues with the highest expression level in the liver. Moreover, differential expression analysis revealed that the hcApo gene is more highly expressed in the liver, kidney, mantle and gill of purple line mussels compared to white line mussels. In situ hybridization investigations of the precise expression site of hcApo mRNA in the mantle showed that hcApo mRNA is specifically expressed in the outer epithelial cells of the middle fold and the inner epithelial cells of the outer fold of the mantle, as well as throughout the outer epithelium of the outer fold and ventral mantle. Another very important finding is that significantly positive correlation existed between the hcApo gene expression level and the total carotenoid content in purple line mussels. These findings may provide a better understanding of the roles of hcApo in the molecular mechanisms of shell formation and coloring of H. cumingii.     

三角帆蚌Hc-GSK3β基因鉴定及内壳色性状相关SNP筛选

为了探究三角帆蚌(Hyriopsis cumingii)糖原合成激酶-3β(GSK3β)基因对壳色的影响,研究采用RACE技术获得Hc-GSK3β基因cDNA全长1867 bp,其中包含1261 bp的ORF区编码420个氨基酸, ORF中含有一个S＿TKc结构域,该结构域序列高度保守。组织差异表达分析发现Hc-GSK3β基因在紫色蚌鳃、斧足、内脏团和边缘膜组织中表达量高于白色蚌的表达量(P<0.05),且在斧足和边缘膜表达差异水平达到极显著(P<0.01),而在紫色蚌闭壳肌组织中表达量显著低于白色蚌(P<0.05)。原位杂交(ISH)实验结果显示在三角帆蚌外套膜的外褶、中褶、內褶、背膜区和腹膜区均有阳性信号产生,且在外褶的信号表达较强烈。该基因经重测序比较,共鉴定出6个SNP位点,其中在C+185A位点的CA基因型在紫色蚌的分布频率显著高于白色三角帆蚌(P<0.05);在紫色蚌中, T+341G位点TT基因型三角帆蚌内壳颜色参数b值显著低于TG基因型(P<0.05)。研究表明, Hc-GSK3β基因参与了三角帆蚌壳色形成,筛选的SNP标记可用于三角帆蚌壳...     

Impacts of invasive crayfish (Pacifastacus leniusculus) on endangered freshwater pearl mussels (Margaritifera laevis and M. togakushiensis) in Japan

The invasive alien crayfish Pacifastacus leniusculus is considered harmful to freshwater pearl mussels Margaritifera laevis and M. togakushiensis. It also often colonises mussel habitats in Japan. In order to test the negative effects of alien crayfish on mussels, we evaluated the predation impact of signal crayfish on freshwater pearl mussels in vitro. We tested the relationship between the survival/injury rates of mussels and crayfish predation with respect to different sizes of mussels (four classes based on shell length: 10, 30, 50 and 70 mm). Crayfish selectively fed on the flesh of the 10-mm size class mussels after breaking their shells. The shell margins of mussels in all size classes were injured by crayfish. Results also showed that crayfish particularly injured the 50-mm size class of mussels. This observation could be attributed to this mussel size being the most suitable shell size (29.56–37.73 mm in carapace length) that the crayfish can effectively hold. This study shows that the presence of invasive crayfish reduces freshwater pearl mussel populations by damaging the shell margins and/or killing the mussels. This negative impact of invasive crayfish not only decreases the mussel population but could also limit mussel recruitment, growth and reproduction.     

水体Ca2+对三角帆蚌珍珠质沉积的影响

为研究不同水体Ca2+浓度(10-80 mg/L)下三角帆蚌生长和珍珠质沉积量和晶体结构的变化, 采用鱼蚌混养的养殖模式养殖10周。结果表明, 1龄幼蚌生长的适宜Ca2+浓度为40 mg/L, 2龄未植片三角帆蚌生长的适宜Ca2+浓度为40-70 mg/L, 2龄植片三角帆蚌珍珠沉积的适宜Ca2+浓度为40 mg/L。拉曼光谱分析和珍珠层小片的扫描电镜观察结果表明, 适宜Ca2+浓度影响三角帆蚌珍珠质沉积可能是通过促进外套膜组织有机基质分泌从而调节CaCO3晶体形成和生长实现的。研究结果提示, 在三角帆蚌生长快速季节, 养殖水体中添加一定的钙源如生石灰等将有利于蚌体和珍珠的生长。同时研究结果也为加快珍珠培育, 提高珍珠品质提供理论依据和实践操纵手段。     

美国紫踵劈蚌与三角帆蚌和褶纹冠蚌的形态比较与判别分析

描述了紫踵劈蚌(Potamilus alatus)贝壳外部和内部特征,并对紫踵劈蚌、三角帆蚌(Hyriopsis cumingii)和褶纹冠蚌(Cristaria plicata)进行了形态学比较。运用多变量形态度量学方法分析了3种淡水育珠蚌的形态差异。主成分分析构建了2个主成分,其中第一主成分的方差贡献率为66·90%,第二主成分的贡献率为33·10%,2个主成分的累计贡献率达到100%;采用逐步判别法,从11个比例性状中筛选出6个主要性状建立了3种育珠蚌的形态判别函数,其综合判别准确率达到100%。     

Molecular properties and immune defense of two ferritin subunits from freshwater pearl mussel,Hyriopsis schlegelii

Ferritin is a conserved iron-binding protein involved in cellular iron metabolism and host defense. In the present study, two distinct cDNAs for ferritins in the freshwater pearl mussel Hyriopsis schlegelii were identified (designated as HsFer-1 and HsFer-2) by SMART RACE approach and expressed sequence tag (EST) analysis. The full-length cDNAs of HsFer-1 and HsFer-2 were of 760 and 877 bp, respectively. Both of the two cDNAs contained an open reading frame (ORF) of 522 bp encoding for 174 amino acid residues. Sequence characterization and homology alignment indicated that HsFer-1 and HsFer-2 had higher similarity to H-type subunit of vertebrate ferritins than L-type subunit. Analysis of the HsFer-1 and HsFer-2 untranslated regions (UTR) showed that both of them had an iron response element (IRE) in the 5′-UTR, which was considered to be the binding site for iron regulatory protein (IRP). Quantitative real-time PCR (qPCR) assays were employed to examine the mRNA expression profiles. Under normal physiological conditions, the expression level of both HsFer-1 and HsFer-2 mRNA were the highest in hepatopancreas, moderate in gonad, axe foot, intestine, kidney, heart, gill, adductor muscle and mantle, the lowest in hemocytes. After stimulation with bacteria Aeromonas hydrophila, HsFer-1 mRNA experienced a different degree of increase in the tissues of hepatopancreas, gonad and hemocytes, the peak level was 2.47-fold, 9.59-fold and 1.37-fold, respectively. Comparatively, HsFer-2 showed up-regulation in gonad but down-regulation in hepatopancreas and hemocytes. Varying expression patterns indicate that two types of ferritins in H. schlegelii might play different roles in response to bacterial challenge. Further bacteriostatic analysis showed that both the purified recombinant ferritins inhibited the growth of A. hydrophila to a certain degree. Collectively, our results suggest that HsFer-1 and HsFer-2 are likely to be functional proteins involved in immune defense against bacterial infection.     

The impact of land use on the mussel Margaritifera margaritifera and its host fish Salmo trutta

Today, land use impacts a major proportion of all streams. Here, landscape features in corridors along streams and water chemical factors were analyzed in relation to recruitment of the threatened freshwater pearl mussel (Margaritifera margaritifera) and its host fish the brown trout (Salmo trutta). Mussel recruitment and trout density were negatively related to forest clear-cuts. Mussel recruitment was negatively related to water color and turbidity. Therefore, the threats to the mussel may be severe, as low mussel recruitment may be caused by direct effects on the juvenile mussels and indirect effects on the host fish. High proportions of lakes and ponds were found to be positive for recruitment and for trout, and deciduous forest was positively related to trout. The combination of investigations at different scales at the landscape level and at in-stream levels may be applicable to find threats to other threatened species. The results indicate that forestry activities may negatively affect recruitment of freshwater pearl mussels and its host fish. Reductions of forestry activities and the retaining of intact quantity and quality of the riparian zones next to streams, both for the mussel and its host fish may be important conservation measures to restore freshwater pearl mussel populations.     

Strategies for the conservation of endangered freshwater pearl mussels (<Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> L.): a synthesis of Conservation Genetics and Ecology

Freshwater pearl mussels (Margartifera margaritifera L.) are among the most critically threatened freshwater bivalves worldwide. The pearl mussel simultaneously fulfils criteria of indicator, flagship, keystone and umbrella species and can thus be considered an ideal target species for the process conservation of aquatic ecosystem functioning. The development of conservation strategies for freshwater pearl mussels and for other bivalve species faces many challenges, including the selection of priority populations for conservation and strategic decisions on habitat restoration and/or captive breeding. This article summarises the current information about the species’ systematics and phylogeny, its distribution and status as well as about its life history strategy and genetic population structure. Based on this information, integrative conservation strategies for freshwater mollusc species which combine genetic and ecological information are discussed. Holistic conservation strategies for pearl mussels require the integration of Conservation Genetics and Conservation Ecology actions at various spatial scales, from the individual and population level to global biodiversity conservation strategies. The availability of high resolution genetic markers for the species and the knowledge of the critical stages in the life cycle, particularly of the most sensitive post-parasitic phase, are important prerequisites for conservation. Effective adaptive conservation management also requires an evaluation of previous actions and management decisions. As with other freshwater bivalves, an integrative conservation approach that identifies and sustains ecological processes and evolutionary lineages is urgently needed to protect and manage freshwater pearl mussel diversity. Such research is important for the conservation of free-living populations, as well as for artificial culturing and breeding techniques, which have recently been or which are currently being established for freshwater pearl mussels in several countries.     

Regional monitoring of freshwater pearl mussel <Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> in the County of Norrbotten,Sweden

A total of 16 freshwater pearl mussel Margaritifera margaritifera rivers out of 64 known freshwater pearl mussel rivers are included in the Administrative County of Norrbotten regional monitoring program. First surveys were done in 1994 and the results show that only three rivers have viable populations according to national criteria despite little visible human impact and that juvenile mussels (<50 mm in length) have been found in all rivers at every occasion. The results also indicate that there might be “missing years” for juvenile recruitment suggesting that freshwater pearl mussel populations at the extreme end of the species range might be dependent on “golden moments” in order to keep up viable populations. Deeper knowledge and better tools for determining viable populations might be necessary in order to make the right decisions on how to manage the rivers and the freshwater pearl mussel populations.     

Overfishing in the Baltic Sea basin in Russia,its impact on the pearl mussel,and possibilities for the conservation of riverine ecosystems in conditions of high anthropogenic pressure

In recent studies nine populations of the freshwater pearl mussel have been described in the Baltic Sea basin in Russia. They are very scarce, although the condition of their habitats seems to be rather good. Overfishing of the host fish is a limiting factor for them. The number of salmon has decreased by at least 100 times over the past 200 years. Such a scale of decline tends to be hidden over time, and estimation of the normal conditions of the salmon–pearl mussel ecosystem becomes problematic. A significant increase in the number of salmon is necessary to prevent extinction of pearl mussels. Effective protected areas appear to be the only possibility for conservation of the pearl mussels and its host fish species.     

嗜水气单胞菌诱导的池蝶蚌血细胞cDNA 文库的构建和亲环蛋白基因序列的初步分析

实验利用灭活的嗜水气单胞菌(Aeromonas hydrophila)诱导处于四龄池蝶蚌(Hyriopsis schlegelii)14h,将诱导后的池蝶蚌血细胞的总RNA 进行逆转录, 用LD-PCR 法合成双链cDNA, 从而首次成功构建池蝶蚌血细胞的全长cDNA 文库。原始文库的滴度为4106 cfu/cm3, 重组率为90%, 扩增后文库的滴度为3.55109pfu/mL。目前文库已随机测序672 个样品, 将所得双向序列进行拼接, 去除载体, 并多序列比对去除重复序列后, 发现436 条为已知功能序列, 其余为未知功能序列。序列中最小长度270 bp, 最大长度为2153 bp, 平均大小608.6 bp, 表明插入片段大小理想。从文库中筛选获得免疫相关基因池蝶蚌亲环蛋白A(HsCyp A)全长基因并进行序列分析。结果显示, HsCyp A 全长1229 bp, 序列包括52 bp 的5非编码区、495 bp 的开放阅读框、682 bp 的3非编码区和29 bp 的poly(A)尾, 没有明显的加尾信号。对Cyp A 氨基酸序列二级结构进行了较详细的分析并进行了三维建模, 同时构建了其系统进化树, 分析表明亲环蛋白家族是一个在进化上非常保守的蛋白家族。综合分析, Cyp A 在水生动物中不仅仅只是一种组成型蛋白, 而是可能在病原感染防御中发挥重要作用。       

Ontogenetic morphometrics of individual freshwater pearl mussels (<Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> (L.)) reconstructed from geometric conchology and trigonometric sclerochronology

This study bridges two conchological approaches to model the growth characteristics of freshwater pearl mussel shell: size-at-age and sclerochronology. We demonstrate a simple numerical model that transfers sclerochronological data into realistic estimates of ontogenetic shell sizing. This model was constructed for a subset of shell growth data dealing with morphometrics and annual shell growth increments. Further, validation of the model was performed using a dataset that was withheld from the calibration. Both subsets of data showed significant correlations between the observed (measured by vernier callipers) and reconstructed size-at-age data, indicating a successful model. The practical applicability of the model was exemplified for the studied Finnish freshwater pearl mussel populations. In accordance with the previously set theory about the plasticity of life history traits of the species, the southern mussels showed higher growth rates than the northern mussels. Handling editor: K. Martens     

Variation in the <Emphasis Type="Italic">COI</Emphasis> gene of the freshwater pearl mussel <Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> from River Vuokkijoki

The freshwater pearl mussel Margaritifera margaritifera L. is one of the most endangered freshwater mussels in the world. Effective conservation of threatened species requires not only ecological, but also genetic information from the target species and populations. Since low genetic diversity can reduce the ability of a species to adapt to environmental changes, maintaining genetic diversity has been identified as one of the key elements in successful conservation programs. We examined genetic variation of the freshwater pearl mussel from the River Vuokkijoki, Karelia, Russia. We sequenced a fragment of the cytochrome c oxidase subunit I gene (COI) from 22 individuals and compared the data to 32 previously published COI sequences available in GenBank. We identified 10 different COI haplotypes in the sequenced samples, three of which had not been previously reported. Our results show that the River Vuokkijoki has high genetic diversity and suggest that the colonization of this northern freshwater pearl mussel population might have occurred from multiple and even distant refugia. Therefore, the freshwater pearl mussel population of the River Vuokkijoki is valuable for the conservation of the whole species.