Search results for "Amphibian"

Spatial Context of Breeding Ponds and Forest Management Affect the Distribution and Population Dynamics of the Great Crested Newt

2016

Intensive forest management and landscape degradation are threats to amphibian populations. We modelled and compared the extinction and colonization dynamics of the great crested newt in four different spatial contexts that describe landscape change from past to present and future forest landscapes in eastern Finland. In future landscape scenarios, we explored the effects of two forest use intensities with different logging rotation times. The introduction of fish into breeding ponds has been the main cause of local extinctions of the great crested newt. In the future, intensifying land-use and shorter logging rotation will decrease the connectivity between ponds the most. In conservation p…

Pentadactyl manus of the Metoposaurus krasiejowensis from the Late Triassic of Poland, the first record of pentadactyly among Temnospondyli

2020

Abstract Temnospondyli are commonly believed to have possessed four digits in the manus and five in the pes. However, actual finds of articulated autopodia are extremely rare. Therefore, an articulated, slightly incomplete forelimb skeleton with preserved manus of Metoposaurus krasiejowensis from the Late Triassic of Poland is important in providing new details about the structure and ossification sequence in the temnospondyl limb. The most important observation is the presence of five metacarpals in this specimen. This allows reconstructing the manus as pentadactyl. The number of phalanges and the distribution of distal articulation facets allow reconstruction of the digit formula as (2?)‐…

Breeding phenology of Bufo viridis Laurenti, 1768 in Sicily (S Italy)

2006

Inhibition of amphibian egg development by histones

1966

Uova di Anuri (Discoglossus pictus) sono state trattate con istoni. II trattamento con la frazione ricca in lisina (0,4-0,1 mg/ml) durante la segmentazione causa blocco alle prime divisioni. Con concentrazioni minori (0,05–0,025 mg/ml) lo sviluppo si arresta allo stadio di gastrula. La sensibilita al trattamento decresce notevolmente dopo la gastrulazione. La frazione ricca in arginina e risultata meno efficace.

Übertragung von Verhaltensweisen durch Transplantation von Anlagen neuroanatomischer Strukturen bei Amphibienlarven

2010

By replacing parts of the neural plate (prospective medulla oblongata) of Triturus vulgaris by neural ectoderm of Xenopus laevis larval chimaeras were obtained, which showed donorlike rhythmical movements of distinct parts of the visceral musculature according to the place of implantation. Especially the branchial region with its external gills showed rhythmical movements and is the special object of this investigation.

Amphibian Immune System

1998

The temnospondyl amphibian Cyclotosaurus from the Upper Triassic of Poland

2005

A gap in the Late Triassic fossil record of the capitosaur amphibian Cyclotosaurus is filled by new material from lacustrine deposits at Krasiejow, Poland, corresponding in age to the Lehrberg Beds (late Carnian) of Germany. The skull of the Polish cyclotosaur is intermediate in several respects between that of Cyclotosaurus robustus from the middle Carnian Schilfsandstein of Germany and the younger C. mordax from the early Norian Stubensandstein. It shows a decrease in the width of the skull and in the degree of con- cavity of the posterior margin of the skull roof. The differ- ences are significant enough to warrant erection of a novel species, the name Cyclotosaurus intermedius sp. nov. …

Is triploidy indisputably determinable in hybridogenetic hybrids by planimetric analyses of erythrocytes?

2008

The size of amphibian erythrocytes is positively correlated to their DNA content. Therefore, planimetry of erythrocytes has long been used to determine ploidy levels in amphibians. In Rana esculenta. a hybrid originating from Rana ridibunda x Rana lessonae natural crosses, planimetric determination of erythrocyte size is used to distinguish diploid and triploid specimen. In the present study we performed planimetric analyses on the hybrid Rana grafi, comprising a second hybridogenetic system with its parental species Rana ridibunda and Rana perezi in southern parts of France. We found size differences of diploid and triploid erythrocytes to range between 26 and 33% in studies on adult R. es…

Evolutionary History and Functional Characterization of the Amphibian Xenosensor CAR

2011

AbstractThe xenosensing constitutive androstane receptor (CAR) is widely considered to have arisen in early mammals via duplication of the pregnane X receptor (PXR). We report that CAR emerged together with PXR and the vitamin D receptor from an ancestral NR1I gene already in early vertebrates, as a result of whole-genome duplications. CAR genes were subsequently lost from the fish lineage, but they are conserved in all taxa of land vertebrates. This contrasts with PXR, which is found in most fish species, whereas it is lost from Sauropsida (reptiles and birds) and plays a role unrelated to xenosensing in Xenopus. This role is fulfilled in Xenopus by CAR, which exhibits low basal activity a…

Phylogeography of Ptychadena mascareniensis suggests transoceanic dispersal in a widespread African-Malagasy frog lineage

2004

Aim The Mascarene ridged frog, Ptychadena mascareniensis, is the only African amphibian species thought to occur on Madagascar and on the Seychelles and also Mascarene islands. We explored its phylogenetic relationships and intraspecific genetic differentiation to contribute to the understanding of transoceanic dispersal in amphibians. Methods Fragments of the mitochondrial 16S rRNA gene were sequenced from specimens collected over most of the distribution area of P. mascareniensis, including populations from Madagascar, Mascarenes and Seychelles. Results We identified five deeply divergent clades having pairwise divergences >5%, which probably all represent cryptic species in a P. mascaren…