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We studied population size, genetic diversity and differentiation of common frog ( Rana temporaria) populations at urban golf courses and reference natural ponds in the greater Helsinki region, southern Finland. A total of 248 tadpoles from 12 locations (six golf courses, six reference sites) were genotyped with 13 polymorphic microsatellite markers. The most urban populations, situated in northern Helsinki, were the largest breeding sites having >120 (golf courses) and >200 (reference sites) spawn clumps at the time of sampling. On average, there was no difference in the number of spawns between the anthropogenic ponds at golf courses and the natural water bodies. Genetic variation within populations was substantial ( H = 0.68) while genetic differentiation between populations was low ( F = 0.016; average distance = 17.6 km). The golf course populations did not differ from natural populations in terms of genetic variability or differentiation. Hence, our results suggest that golf courses contribute positively to urban amphibian populations by providing suitable water bodies for reproduction and green corridors for dispersal, thus preventing isolation and loss of genetic variability within populations. [ABSTRACT FROM AUTHOR]

Non-invasive DNA sampling is an important tool in amphibian conservation. Buccal swabs are nowadays replacing the wounding toe-clipping method. Skin and cloaca swabbing are even less invasive and easier to handle than buccal swabbing, but could result in contaminations of genetic material. Therefore, we test if external skin and cloaca swabs are as reliable as buccal swabs for genetic analysis of amphibians. We analysed eight microsatellite loci for the common frog ( Rana temporaria, Linnaeus 1758) and compared genotyping results for buccal, skin and cloaca swabs regarding allelic dropouts and false alleles. Furthermore, we compared two DNA extraction methods regarding efficiency and cost. DNA quality and quantity (amplification success, genotyping error rate, in nanogram per microlitre) were comparable among DNA sources and extraction methods. However, skin and cloaca samples exhibited high degrees of contamination with foreign individuals, which was due to sample collection during mating season. Here, we established a simple low budget procedure to receive DNA of amphibians avoiding stressful buccal swabbing or harmful toe clipping. However, the possibility of contaminations of external swabs has to be considered. [ABSTRACT FROM AUTHOR]

Graph-based analysis is a promising approach for analyzing the functional and structural connectivity of landscapes. In human-shaped landscapes, species have become vulnerable to land degradation and connectivity loss between habitat patches. Movement across the landscape is a key process for species survival that needs to be further investigated for heterogeneous human-dominated landscapes. The common frog ( Rana temporaria) was used as a case study to explore and provide a graph connectivity analysis framework that integrates habitat suitability and dispersal responses to landscape permeability. The main habitat patches influencing habitat availability and connectivity were highlighted by using the software Conefor Sensinode 2.2. One of the main advantages of the presented graph-theoretical approach is its ability to provide a large choice of variables to be used based on the study's assumptions and knowledge about target species. Based on dispersal simulation modelling in potential suitable habitat corridors, three distinct patterns of nodes connections of differing importance were revealed. These patterns are locally influenced by anthropogenic barriers, landscape permeability, and habitat suitability. And they are affected by different suitability and availability gradients to maximize the best possible settlement by the common frog within a terrestrial habitat continuum. The study determined the key role of landscape-based approaches for identifying the 'availability-suitability-connectivity' patterns from a local to regional approach to provide an operational tool for landscape planning. [ABSTRACT FROM AUTHOR]

The inhibitor of gap junctions 18α-glycerretinic acid inhibits the maturation of follicle-enclosed common frog oocytes stimulated by low progesterone concentrations. The inhibitory effect of 18α-glycyrrhetinic acid does not depend on concentrations within the limits of 5–40 μM. The progesterone concentrations, at which oocyte maturation can be inhibited, differed markedly in different females. The inhibitory effects of actinomycin D (5 μg/ml) and 18α-glycyrrhetinic acid (5 μg/ml) were expressed when the same progesterone concentrations were used. When injected in an intact oocyte, Lucifer yellow was transferred into the follicle cells, thus suggesting the presence of gap junction between these latter and the oocyte. The data obtained suggest that the previously described transcription-dependent factor formed in the follicle cells under the influence of low progesterone concentrations and stimulating oocyte maturation is transferred in the oocyte via gap junctions. [ABSTRACT FROM AUTHOR]

The major water-soluble polypeptide with molecular weight of approximately 23 kDa (the 23 kDa polypeptide) was identified in the lens of common frog Rana temporaria L. According to the gel filtration data, the peptide is a part of an oligomeric protein with molecular weight over than 300 kDa (α-crystallin fraction). A highly pure fraction of the 23 kDa polypeptide was isolated by two-step ion-exchange chromatography and SDS electrophoresis and the specific antibodies were obtained. Immunohistochemistry showed the presence of the 23 kDa polypeptide in the cytoplasm of lens epithelial cells (including its central region) and in the zones neighboring the plasma membranes in the cortical fibers. The 23 kDa polypeptide was not found in the lens central zone (nucleus). It was also present in the retina (in the cells of inner nuclear layers), but not in the other tissues and organs of adult frog. Immunochemical analysis showed that the 23 kDa polypeptide was different from all known crystallins of frogs and other animals (bull, mouse, rat, and chicken). The nature of the 23 kDa polypeptide and the relation of its expression with the lens cell differentiation are discussed. [ABSTRACT FROM AUTHOR]