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To date, the Chinese clam Anodonta woodiana Lea, native to the Amur and Yangtze river basins, has been reported from three localities in Poland. Since the early 1990s, the species has massively colonised its first Polish locality, i.e. heated lakes near Konin in central Poland. Since 2002 and 2003, the clam has also been found in, respectively, fish ponds near Sieraków (Greater Poland) and the heated channel of the Dolna Odra power station near Szczecin, NW. Poland. In order to estimate the genetic variability of the first, pioneer populations in Poland, 12 enzymatic loci were analysed using starch gel electrophoresis. A. woodiana exhibits a strong genetic variation, as demonstrated by the following parameters of genetic variability for its Polish populations: 66.7–83.3% polymorphic loci, 2.3 alleles on average per locus and 2.6–2.9 per polymorphic locus, an average of 2.53 genotypes per population, and average expected heterozygosity of 0.30–0.35. The results suggest either a massive colonisation by genetically diverse individuals, or a multiple colonisation by founder populations coming from various water bodies. The genetic similarity (Nei) between the populations of A. woodiana is high (0.83 to 1.00), which suggests a strong genetic homogeneity of this species in its first locality in Poland.
The populations of two indigenous Polish species, the noble crayfish (Astacus astacus) and the narrow-clawed crayfish (Astacus leptodactylus), were gradually reduced over the 20th century by extensive water pollution, the subsequent eutrophication over time of lakes and rivers, and the epizooty plague caused by the fungus Aphanomyces astaci. The crayfish populations were also adversely affected by the introduction of the American crayfish in 1890 (Orconectes limosus) and the signal crayfish (Pacifastacus lenisculus) in the late 1960s. This work aims at finding molecular markers that would permit objective identification of crayfish species. This could facilitate monitoring the distribution and protection of crayfish species, both in Poland and throughout the world. To this end, the PCR-RFLP technique was used for the analysis of the mitochondrial coxl gene, using 5 restriction enzymes. The best molecular marker was the restriction enzyme AluI, which proved efficient in differentiating all the studied crayfish. Five unique genotypes that occurred in a single species were observed, with most of them in the enzyme AluI, which therefore may be regarded as a species-diagnostic marker.
Five populations of the zebra mussel Dreissena polymorpha, from small, isolated, post-glacial water bodies and one reservoir formed in the 50s (all in the Western Pomerania) have been examined. Isoenzyme electrophoresis in starch gel was used in order to estimate their variation and genetic structure. The studied populations are widely variable genetically, and their genotypes are very diverse, in spite of their isolated character. The analysis revealed 86% polymorphic loci, 2.3–3.7 alleles per locus and 2.5–4.2 per polymorphic locus, 2.4–5.4 genotypes per locus and the expected heterozygosity of 0.338–0.487. The genetic similarity between the populations ranged from 0.828 to 0.949 and was somewhat lower, compared to other populations of the species. The level of genetic variability of D. polymorpha in the isolated populations was comparable to that found in large populations from the Western Pomerania and with the founder populations from the Great Lakes of North America. Colonisation by D. polymorpha is not accompanied by impoverishment of gene pool resulting from founder effect. The species seems to be expanding massively, using all of its genetic potential.
Doubly uniparental inheritance (DUI) of mitochondrial DNA, different from maternal inheritance, is known to occur in five bivalve families (Mytilidae, Veneridae, Unionidae, Margaritiferidae, Hyriidae). DUI involves two types of mitochondrial DNA: F type, inherited from the mother and M type, inherited from the father. Females have only F type mtDNA, males have both types, M type being located in their gonads, F type in their somatic tissues. Among freshwater bivalves known to show DUI, only Anodonta woodiana occurs in Poland. The aim of this study was to ascertain if DUI occurred in another native bivalve, Anodonta anatina, based on DNA sequence of mitochondrial gene of cytochrome oxidase subunit I (cox1). M haplotype was found in male gonads, and F haplotype in somatic tissues of both sexes. Seven sequences were obtained for each F andMhaplotypes, 625–709 base pairs long. Variation of 0.2 and 0.3% was found within F andMcox1 sequences, respectively, and 29–32% variation between them.
Doubly Uniparental Inheritance (DUI), a peculiar way of inheritance of mitochondrial DNA in animals, has been detected in seven families of marine and freshwater bivalves, including Unionidae. DUI involves two independently inherited mitochondrial genomes: maternal (F genome) and paternal (M genome), which show different tissue localisation and wide genetic variation. F genomes occur in somatic tissues of both sexes and are inherited maternally (Strict Maternal Inheritance, SMI). M genomes are located in male germ cells and transmitted to next generations along the male lineage, i.e. from fathers to male offspring. The objective of this study was detection of M genomes and characteristics of DUI in unionid bivalves from Poland, based on sequential analyses of seven mitochondrial genes. This is the study to analyse F and M haplotypes at intra- and interspecific level in seven species of freshwater mussels. DUI was first observed in species of the genus Unio (U. crassus, U. pictorum and U. tumidus), and the best M haplotype marker was gene cox1. In the studiem bivalves F and M sequences showed a similar intraspecific variation, with differences among the genes. Three tRNA genes showed the smallest (ca. 20%) nucleotide variation, followed by the gene coding for RNA for the small ribosomal subunit, srRNA (24%); a significantly greater variation (exceeding 30%) was recorded for protein-coding genes (cox1, cytb) and the gene coding for RNA for the large ribosomal subunit, lrRNA. Interspecific variation of F sequences of the studied unionids ranged from 5% for tRNAs to18% for cytb. Higher values were observed for M sequences: from 7% for tRNAs to19% for cox1. The Chinese mussel occurring in Poland, despite the morphology-based identification as Anodonta / Sinanodonta woodiana, proved to be genetically more similar to A. arcaeformis than toAsian specimens of A. woodiana. Phylogenetic analyses showed that in the genus Unio the youngest species were U. pictorum and U. mancus, and the earliest species was U. tumidus showing the greatest genetic distinctness.
Age structure, sex ratio and shell mass of a recently introduced bivalve Anodonta woodiana (Lea) were analysed in three sampling sites at its only locality in Poland – the cooling system of two power plants near Konin (C Poland). The youngest population is that in the lake Licheńskie, the oldest individual (6+) was found in the population inhabiting the warmest canal. In the material examined, the most numerous individuals were those aged three years (43%), followed by four years (33%) and five years old (12%) individuals. The shell mass (Sm) was positively correlated with the individual age, the highest shell mass increment being observed in specimens aged 2+, 3+ and 4+. No dependence was found between the Sm parameter and sex. The shell mass varied widely (V% > 30). The highest Sm values were found in individuals from the initial cooling reservoir, the lowest in those from the lake Licheñskie, the respective water temperatures during the summer stagnation being 33 and 30°C. Except for the population from the lake Licheñskie, the sex ratio was 1:1.
The objective of the study was to sequence the complete female mitochondrial genomes of Sinanodonta woodiana and Unio pictorum, and toascertain their intra- and inter-specific variation within all the genes and non-coding regions. Complete sequence of maternally inherited mitochondrial genome of Sinanodonta woodiana is 16,243 bp long and is one of the three longest mt genomes in unionids; mt genome of Unio pictorum with its 15,761 bp is one of the smallest in the family. Each genome includes 14 protein-coding genes (13 as in most Metazoa, plus one open reading frame F ORF), 2 ribosomal RNA genes and 22 genes for transfer RNA with typical secondary structures, except for tRNA for serine1. S. woodiana has 25, and U. pictorum 27 non-coding sequences, which constitute 7.8 and 4.9% of mt genome, respectively. The content of A+T bases is 65.8% in S. woodiana and 65.1% in U. pictorum; the difference between the twospecies is 21%. Intra-specific variation in S. woodiana is three times greater than in U. pictorum. Lower nucleotide diversity within the second species suggests a small effective population size of the Polish U. pictorum. The twospecies show a similar usage of the most frequent and least frequent codons; the differences pertain to the usage of both stop codons. Gene trnS1 (serine, UGA) in unionids is very little variable with respect to tRNA secondary structure (absence of DHU arm), and nucleotide composition, while its inter-specific variation is half lower than in other mt-tRNAs.
Thirty two populations of Dreissena polymorpha (Pall.) from Poland were electrophoretically studied with respect to enzymatic loci Got1, Est1, Pgi1, Mdh1, Me1, Idh1 and Pgm1. The variation analysis focused on the possible differences between populations inhabiting lakes of different character. Populations from heated lakes displayed a higher genetic variation compared to unheated reservoirs. Populations from brackish waters showed an excess of homozygotes (loci Got1 and Pgi1) compared to freshwaters. Gradual eutrophication of lakes seems to cause no significant changes in the genetic structure of zebra mussel populations.
The study was carried out on 9 species of freshwater bivalves (Dreissena polymorpha, D. bugensis, Unio crassus, U. pictorum, U. tumidus, Anodonta anatina, A. cygnea, A. woodiana, and Pseudanodonta complanata). The mitochondrial COI gene studied with PCR-RFLP and 6 restriction enzymes (ScrFI, Csp6I, BsiZI, EcoRI, BamHI and AluI) showed the absence of individual variability within each species studied. The genetic variability of the COI involved differences at the species, genus, and family level, depending on the restriction enzyme used. Four restriction enzymes (ScrFI, Csp6I, BsiZI and AluI) proved efficient in differentiating between D. polymorpha and D. bugensis as well as in identifying the three Unio species (Csp6I and AluI), U. crassus, and P. complanata (ScrFI and AluI). EcoRI and AluI made it possible to identify A. anatina and P. complanata. Two (for EcoRI), 3 (for Csp6I, BsiZI), 5 (for ScrFI) and 9 (for AluI) unique genotypes that occurred in a single species each were observed; the enzymes may therefore be regarded as species-specific markers. Only restriction enzyme AluI can differentiate between A. cygnea and A. woodiana.
Within the last decades the slug Arion lusitanicus has expanded its range over wide areas of Europe, in most of them it is now a serious pest. Poland has been invaded relatively recently (since the late 1980s). Considering the ecological importance of the slug, very little is known yet about the mechanism of invasion, establishment of new populations and influence on the native fauna and flora. The analysis of nucleotide sequences of mitochondrial cytochrome oxidase subunit 1 gene (cox1) revealed a great inter- and intrapopulation variation in the Polish populations of A. lusitanicus. The differentiation of all the studied Polish populations of A. lusitanicus is 0.2–2.2%, while two analysed Belgian populations are monomorphic and moderately genetically diverse at 0.8%. This indicates a heterogeneous origin of the Polish populations, probably resulting from multiple independent introduction events. The genotype found in the first four Polish populations (S. Poland) suggests that their origin is different from the remaining populations.
The study evaluated weed infestation of pea (Pisum sativum L.) cultivated under conditions of conventional (CT), reduced (RT) and herbicide tillage (HT). It demonstrated the highest weed density per m2 in plots with the herbicide (HT) and reduced (RT) systems and significantly lower weed infestation in plots cultivated in the conventional system (CT). In addition, more weeds occurred at the third leaf stage (13/14 in BBCH scale) than at the pod development stage (73/74 BBCH) of pea. The highest biomass was produced by weeds in the herbicide system (HT), a lower one – in the reduced system (RT), and the lowest one – in the conventional system (CT). The air-dry weight of weeds depended also on pea development stage. At the pod development stage (73/74 BBCH), the air-dry weight of weeds was significantly higher than at the third leaf stage (13/14 BBCH). The tillage system was also observed to influence the species composition of weeds. This trait was also affected by the period of weed infestation assessment. At the third leaf stage of pea (13/14 BBCH), there occurred 26 weed species, including 24 annual ones. The most abundant species included: Chenopodium album L., Stellaria media (L.) Vill., Capsella bursa-pastoris (L.) Med., Matricaria inodora L., Thlaspi arvense L., and Fallopia convolvulus (L.) A. Löve. At the pod development stage (73/74 BBCH), the pea crop was colonized by 24 weed species, including 3 perennial ones. At this stage the predominant species included: Avena fatua L., Amaranthus retroflexus L., Papaver rhoeas L., Echinochloa crus-galli (L.) P.B., Matricaria inodora L., and Galeopsis tetrahit L.
Mitochondrial genomes are frequently used to infer phylogenetic relationships. Some taxa are, however, poorly represented. To facilitate better understanding of the potential of mitochondrial genome data in freshwater mussels, we present here, for the first time, the mitochondrial sequences of 4 complete F-type mitochondrial genomes from the European freshwater bivalve Unio pictorum (Unionidae). These genomes are very compact (15 761 bp) but have atypical gene complement for bilaterian mitochondrial genomes and a very similar organization to other unionid genomes available in databases. Very low nucleotide diversity within the species suggests a small effective population size of Polish U. pictorum, a phenomenon of potential importance for environmental management policies.
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