Protein polymorphism and geographic variation in the loach Misgurnus anguillicaudatus

Electrophoretic variations of enzymatic and non-enzymatic proteins were investigated in 8 populations of the loach Misgurnus anguillicaudatus. The cathodic hemoglobin and the muscle protein in the region II were shown to be polymorphic, in addition to the five polymorphic proteins previously reported (the anodic hemoglobin, muscle protein in the region III, 6-phosphogluconate dehydrogenase, phosphoglucomutase and aspartate aminotransferase; Kimura, 1976 & 1977). The muscle proteins in the regions I, IV and V were monomorphic. The values of genetic distances between loach populations, calculated over 10 loci, indicated that M anguillicaudatus should be classified into two local races.     

Geographical variation of lactate dehydrogenase and phosphoglucomutase in the loach Misgurnus anguillicaudatus.

One of the two loci controlling muscle lactate dehydrogenase (LDH) was shown to be polymorphic in the loach Misgurnus anguillicaudatus. The result of the survey on four populations suggests that the differences in the LDH gene frequencies are correlated with the geographical distribution of the loach. A fourth phosphoglucomutase allele (PGMD) was found in one of the loach populations examined.     

Geographical variation of lactate dehydrogenase and phosphoglucomutase in the loach Misgurnus anguillicaudatus

One of the two loci controlling muscle lactate dehydrogenase (LDH) was shown to be polymorphic in the loach Misgurnus anguillicaudatus. The result of the survey on four populations suggests that the differences in the LDH gene frequencies are correlated with the geographical distribution of the loach. A fourth phosphoglucomutase allele ( PGM ^D) was found in one of the loach populations examined.     

Protein polymorphism and genic variation in a population of the loach Cobitis delicata

Hemoglobin, non-enzymatic and enzymatic muscle proteins of the loach Cobitis delicata were examined electrophoretically. Eleven proteins were shown to be under control by 20 loci. Only two loci were defined as polymorphic and 14 loci were completely monomorphic. Estimated average heterozygosity over all 20 loci was 0.011 in the loach population.     

Electrophoretic patterns of aspartate aminotransferase in the loach Misgurnus anguillicaudatus

The loach Misgurnus anguillicaudatus is a fresh-water teleost and is known to be widely distributed through Japan, Formosa, Korea and into eastern Asia. The author has reported electrophoretic variation in five different proteins in the loach (Kimura, 1976a, b, c). This note describes a sixth example, electrophoretic variation of aspartate aminotransferase (AAT; EC 2.6.1.1.).     

Ploidy manipulation using diploid sperm in the loach, Misgurnus anguillicaudatus: a review

This paper assesses the present state of the art of ploidy manipulation in the loach, Misgurnus anguillicaudatus (Teleoste: Cobitidae). Diploid sperm can be obtained from natural tetraploid individuals with four sets of homologous chromosomes. Using diploid sperm, various polyploids and androgenetic diploids have been produced. Cryptic clonal lineages are also recognized in wild populations of the loach. They produce unreduced diploid eggs genetically identical to somatic cells of the mother fish and most diploid eggs develop gynogenetically as a member of the clone. However, some eggs develop to triploid and/or diploid-triploid mosaic individuals by incorporation of sperm nucleus. Diploid-triploid mosaic males exclusively generate fertile diploid sperm with clonal genotypes. Such diploid sperm can also be obtained from artificially sex-reversed clonal individuals. Recent population studies suggested that Japanese M. anguillicaudatus might not be a single species, but a complex involving cryptic species, because wild populations exhibited genetic differentiation at interspecific level. This implies possible relationship between atypical reproduction and natural hybridization in the loach.     

The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure

The loach Misgurnus anguillicaudatus inhabits rice fields in Southern China. It encounters drought during summer and ammonia loading during agricultural fertilization. In the laboratory, aerial exposure led to decreases in its ammonia and urea excretion. Ammonia accumulated to very high levels in the muscle and liver. Urea synthesis through the ornithine-urea cycle was not involved in ammonia detoxification in M. anguillicaudatus. However, M. anguillicaudatus was capable of partial amino acid catabolism leading to the accumulation of alanine in the first 24 h of aerial exposure. This was apparently coupled to a possible decrease in protein/amino acid catabolism. These are not detoxification mechanisms but mechanisms that avoid internal fouling by ammonia. Misgurnus anguillicaudatus was also capable of detoxifying internally produced ammonia in part to glutamine, which appears to be an important adaptation after 24 h of aerial exposure. However, unlike the case of the marble goby (Oxyeleotris marmoratus), there was no alteration to the kinetic properties of the hepatic glutamine synthetase. During dry seasons, M. anguillicaudatus moves actively on land until it encounters soft mud in which it can bury itself through several strong wriggling actions of the body. Hence, it is possible that M. anguillicaudatus uses partial amino acid catabolism to fuel its short period of activities on land and switches to the formation of glutamine to detoxify internally produced ammonia when it remains relatively inactive in the mud.     

Genetically diversified populations in the loach Misgurnus anguillicaudatus inferred from newly developed microsatellite markers

The loach Misgurnus anguillicaudatus is a freshwater fish which include natural polyploids and clones besides most bisexually reproducing diploids. Recent genetic studies using allozymes differentiated the populations in northern region of Hokkaido from other populations in Japan. Here, we developed 23 new sets of polymerase chain reaction primers to detect polymorphic microsatellites loci and tested them in 20 individuals from Memanbetsu town (northern Hokkaido) and Kita village (southern Hokkaido). These markers can be potentially diagnostic for identification of two populations.     

Geographic variation of muscle adenylate kinase in the loach Misgurnus anguillicaudatus

The electrophoretic pattern of the loach muscle adenylate kinase was composed of one or two major bands. Each major band was preceded by two minor bands. Three codominant alleles were postulated to segregate in loach. Each allele coded for one major band with different mobility.
Adenylate kinase (AK. E.C. 2.7.4.3.) catalyses the reaction 2ADP ATP + AMP. and is known as a heat stable protein constituent of skeletal muscle. Electrophoretic variation of AK has been reported in the pika Ochotona r. rufescens (Vergnes et al. 1974). the teleostean fish Zoarces viviparus (Frydenberg & Si-monsen, 1973), the mussel Mvtilus edulis (Ahmad et al. 1977). and the tunicate Ciona intestinalis (Schmidtke & Engel. 1980). In this note, individual variation of AK in muscle extracts of the fresh-water fish Misgurnus anguillicaudatus is described.
Loach were collected in ponds or purchased from fish shops (Table 1 & Fig. 1). Three populations (OS. AS and KN) were purchased from fish shops in Osaka. Akashi and Kanazawa cities, respectively. Their exact sampling locations were not known. For reference, the locations of these cities are indicated by an open circle in Fig. i. Fish were collected and stored frozen at – 20 ^oC at the sampling time given in Table 1. Muscle extracts were prepared and examined in the period February-April 1981.The method for preparing muscle extract and-the starch gel electrophoretic procedures were the same as those reported previously (Kimura, 1976). The amine-citrate buffer system as described by Clayton & Tretiak (1972) was used. AK was stained by the method of Allendorf et al. (1977). After electrophoresis, an inhibition test was also performed by immersing the gel in 10^-3 M 5.5'-dithiobis-(2-nitrobenzoate) solution for 30 minutes at room temperature.
Under the electrophoretic condition used in the present study, all of the AK     

Molecular characteristics of mitochondrial DNA and phylogenetic analysis of the loach (Misgurnus anguillicaudatus) from the Poyang Lake

The goal of our study was to investigate the molecular characteristics of mitochondrial DNA (mtDNA) and phylogenetic construction of the weather loach (Misgurnus anguillicaudatus) in Poyang Lake. The complete mitochondrial genome was 16,634?bp, and the gene order was identical to that of teleost fishes. Compared with the previous reported weather loach in China, there were numerous nucleotide substitutions and length polymorphisms on the structural genes of mitochondrial DNA in the loach from the Poyang Lake. The Phylogenetic tree indicated that the loach had its own molecular characteristics and was somewhat different from those in other regions of China. Fourteen unique haplotypes of the cytochrome b (cyt b) gene were obtained from 300 weather loaches. The Phylogenetic tree based on the cyt b gene showed that the loaches were substructured into two different populations in The Poyang Lake. Results indicated that the loaches in Poyang Lake not only showed the same phylogeny as the loaches in other areas of China, but also generated its own unique phylogenetic relationships.     

First record of the natural occurrence of hexaploid loach Misgurnus anguillicaudatus in Hubei Province, China

Natural occurrence of hexaploid loach Misgurnus anguillicaudatus detected in central China is reported here for the first time. The evidences from karyotyping, DNA content analysis and nuclear volume measurements were described to confirm the hexaploid nature of the identified individual.     

Evidence of a secondary interspecific mitochondrial DNA introgression in the pond loach Misgurnus dabryanus (Teleostei: Cobitidae) population introduced in Japan

The pond loach Misgurnus dabryanus is a freshwater fish with a distribution range spanning the eastern part of the Asian continent, the Korean Peninsula, and Taiwan. The pond loach was transplanted to the Japanese archipelago through the co-inclusion with dojo loach (Misgurnus anguillicaudatus species complex) populations, which were imported live from China for food materials, and it is currently distributed widely across Japan. A previous mitochondrial DNA (mtDNA) analysis revealed that a pond loach population in Ehime Prefecture (Shikoku Island, Japan) included two highly diverged mtDNA groups (Groups I and II). To examine the origin of these two distinct forms of mtDNA within the Japanese pond loach population, we performed phylogenetic analyses using sequences based on the mtDNA of cytochrome oxidase b (cyt b) and the nuclear DNA recombination activating gene 1 (RAG-1). We also conducted a random amplified polymorphic DNA (RAPD) analysis to examine the establishment of reproductive isolation between sympatric pond loaches with two different mtDNA groups. Our mtDNA phylogenetic results indicated that the two diverged pond loach mtDNA sequences showed polyphyletic relationships among Misgurnus species and its related genus Cobitis. In contrast, there were no clear divergence in nuclear DNA among the pond loaches irrespective of their mtDNA groups, and they all formed monomorphic clades in the phylogenetic relationships among the species. The discrepancy between the mtDNA and nuclear DNA genes support that the existence of two diverged forms of DNA within the pond loach population could be attributed to past mtDNA introgressions from other species rather than convergent evolution. Previous mtDNA phylogenetic studies among Cobitidae revealed that the dojo loach also consisted of two genetically diverged polyphyletic clades: an original Misgurnus mtDNA and an introgressed mtDNA from Cobitis species. In our mtDNA result, the Group II haplotype of the pond loach was included in the mtDNA from the introgressed dojo loach. This suggested that the Group II haplotype was derived from introgressed dojo loach mtDNA. The close relationships between the introgressed dojo loach and the pond loach mtDNA indicated that this secondary introgression had recently occurred via hybridization in a recent artificial aquaculture or transportation process. Common RAG-1 alleles and RAPD bands were shared between the sympatric pond loaches with original and introgressed mtDNAs. This indicates that the introgressed mtDNA haplotype is included as one of the polymorphic genotypes within the pond loach populations, and does not represent existence of different cryptic species.     

Vitellogenic effects of 17beta-estradiol in male Chinese loach (Misgurnus anguillicaudatus)

Male Chinese loaches (Misgurnus anguillicaudatus) were exposed to 17beta-estradiol (E2) in the ambient water at nominal concentrations of 0.5, 1, 5 and 10 mug/L continuously for 8 weeks using a semi-static system. The gonadosomatic index (GSI), total plasma protein, total plasma calcium, magnesium and zinc, and plasma vitellogenin (Vtg) were determined as test endpoints. Our results indicate no significant changes in the GSI between exposed and control groups (P<0.05). All exposure concentrations of E2 dramatically induced the production of Vtg within 7 days. The vitellogenic response of male loach was time- and dose-dependent. At higher concentrations of E2 (5 and 10 microg/L), total plasma protein, total plasma calcium, and total plasma magnesium presented a significant time- and dose-dependent increase, and the three parameters were significantly correlated with plasma Vtg. We conclude that Chinese loaches are sensitive to estrogenic compounds and may be chosen as potential sentinel species in field and laboratory studies. In addition, total plasma protein, total plasma calcium, and total plasma magnesium can be used as indirect indicators to predict Vtg levels in estrogenized Chinese loach.     

枯草芽孢杆菌对泥鳅养殖池塘水水质的改善研究

通过在泥鳅(Misgurnus anguillicaudatus Cantor)养殖水体中施加一定浓度梯度枯草芽孢杆菌(Bacillus subtili Cohns),测定了水化学指标并观察泥鳅生长情况。试验结果表明:枯草芽孢杆菌能够稳定养殖水体的pH值,对COD_Mn、TN和NO₃^--N降解极为显著,其降解速率分别为1.2、0.24和2.7g·L^-1·d^-1,TP在一定范围内波动;当菌液浓度大于149mL·L^-1时,随着浓度的增加,停食后的泥鳅体重变化减小,因此,枯草芽孢杆菌对泥鳅养殖池塘水水质改善效果明显。     

Developmental stages and germ cell lineage of the loach (Misgurnus anguillicaudatus)

The staging of embryonic and larval development, and the germ cell lineage of the loach, Misgurnus anguillicaudatus, are described. Fertilized eggs were obtained by artificial insemination. For the convenience of detailed observation and photography of the external appearance, we use dechorionated embryos. Through a series of operations, these embryos were cultured at 20 degrees C in an incubator. Embryonic and larval development of the loach was divided into five periods: cleavage, blastula, gastrula, segmentation, and hatching. Stages were assigned within each of these periods. Developmental stages were determined and named by morphological features and somite number. The staging series were photographed and tabulated. The germ cell lineage was then elucidated by whole mount in situ hybridization of mRNA expression of the germ-cell-specific marker vasa and histological analysis. Primordial germ cells (PGCs) of the loach derived from the cleavage furrows of 8-cell stage embryos began proliferation in the late blastula period and migrated to the gonadal anlagen through a migration pathway similar to that of the zebrafish. However, it is characteristic of the loach that PGCs migrate a long distance and stay in the posterior part of the yolk-extension region.     

Genome survey of Misgurnus anguillicaudatus to identify genomic information,simple sequence repeat (SSR) markers,and mitochondrial genome

Molecular Biology Reports - The dojo loach Misgurnus anguillicaudatus is an important economic species in Asia because of its nutritional value and broad environmental adaptability. Despite its...     

Phosphoglucomutase electrophoretic patterns of the loach Cobitis biwae

Phosphoglucomutase of two groups of the loach Cobitis biwae , a fresh-water teleost, was examined by starch gel electrophoresis. Some of the fishes had six-banded electrophoretic patterns not observed in other loach species (e.g. Misgurnus anguillicaudatus and Cobitis delicata ). The complexity of the pattern is explainable by an assumption that the loaches are tetraploid fishes. The result suggests that a diploid-tetraploid relationship exists within the species Cobitis biwae .     

一个新的泥鳅雄性特异DNA片段（简报）

世界上现存鱼类多达24000余种．是脊椎动物中分布最广,种类最多的类群．具有多种多样的生物学特性和重大的经济价值。与高等脊椎动物相比．其性别决定具有多样性和可塑性。大多数鱼类的性别决定机制很原始。性染色体的分化处于萌芽状态。在已进行细胞遗传学研究的1700多种鱼类中．大约有176种（占10．4％）发现有明显的异型性染色体。     

大鳞副泥鳅、泥鳅和北方泥鳅肉质比较分析

文章采用组织切片、生化组分分析以及实时荧光定量PCR等方法, 研究了大鳞副泥鳅(Paramisgurnus dabryanus)、泥鳅(Misgurnus anguillicaudatus)和北方泥鳅(Misgurnus bipartitus)肉质差异。结果显示: 大鳞副泥鳅、泥鳅和北方泥鳅的肌纤维横截面积分别为 (3589.17±2326.01)、(2809.7±1818.69) 和(2511.93±1949.03) μm2。粗蛋白和粗脂肪含量均是大鳞副泥鳅最高[分别为(17.07±0.31)%和(2.57±0.38)%], 依次为泥鳅[分别为(14.57±0.59)%和(1.37±0.12)%]和北方泥鳅[分别为(12.33±0.15%和0.57±0.06%]。必需氨基酸指数(EAAI)依次为泥鳅(74.38)、大鳞副泥鳅(65.11)和北方泥鳅(60.14); 呈味氨基酸含量依次为泥鳅(32.60±1.64)%、大鳞副泥鳅(27.75±2.13)%和北方泥鳅(24.86±1.00)%; 除亚油酸以外的总多不饱和脂肪酸含量依次为北方泥鳅(24.43±0.26)%、泥鳅(24.18±1.99)%和大鳞副泥鳅(7.86±0.24)%。大鳞副泥鳅的肌肉生长相关基因myod的表达量高, myog和mrf4的表达量低; 泥鳅和北方泥鳅的myog和mrf4的表达量高, myod的表达量低。elovl5等8个脂肪代谢相关基因的表达特征: 大鳞副泥鳅整体表达水平最高, 北方泥鳅次之, 泥鳅最低。结果表明, 大鳞副泥鳅肉质油润, 但是质地相对粗糙; 泥鳅营养价值高且鲜味程度高; 北方泥鳅肉质细嫩, 但是氨基酸营养价值不高, 鲜味程度较差。三种鳅的上述肉质差异可能与肌肉生长和脂肪代谢活动不同有关。