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At least 19 recordsLinked to original sources
PubMed1978

Experimental hybridization within the genus Triturus (Urodela: Salamandridae). I. Spermatogenesis of F1 species hybrids, Triturus cristatus carnifex female x T. vulgaris meridionalis male.

The spermatogenesis of 9 F1 hybrids of Triturus cristatus carnifex female x T. vulgaris meridionalis male was studied in squash preparations of testicular fragments, treated by the C-staining method. The chromosome number of these hybrids was examined in spermatogonial metaphases and found to be diploid. The two parental sets were always recognized, which means that a regular, although heterospecific, amphimixis occurred (2n = nfemale + nmale). Meiotic prophase I is greatly altered owing to a failure of typical chromosome pairing and chiasma formation. At metaphase I and/or meta-anaphase I, the effects of the hybrid combination of the 2 specific parental sets are clearly visable. Most primary spermatocytes contain only univalents. A few show chromosome associations (bivalents, trivalents and, more rarely, quadrivalent chains) besides univalents. Such associations are of 2 types: (a) intragenomal associations = associations of 2 chromosomes by a terminal (a1) or subterminal chiasma (a2); (b) intergenomal associations = associations of 2 chromosomes by a terminal (b1) or subterminal chiasma (b2). Univalents segregate at random while the associations often lag on the equatorial plane or migrate entire to a spindle pole. Primary spermatocytes with chromosome multivalents can encounter greater difficulties in accomplishing the first cytokinesis. Secondary spermatocytes are numerically and qualitatively unbalanced; however, some of them undergo spermiogenesis and can give rise to a small number of sperms, generally abnormal and never united in bundles. --Problems related to the occurrence of "anomalous" chiasmata and of intra- and inter-genomal homologies are discussed.

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PubMed1990

Differentiation of the brain stem reticular formation in the triturus, Triturus pyrrhogaster.

The brain stem of the triturus was observed to be initially composed exclusively of the mantle layer. A few days before hatching, a narrow marginal layer differentiated peripherally. At the time of hatching, the marginal layer was clearly visible throughout the brain stem, except for in a medial region of the optic tectum. Approximately one week after hatching, a few cells migrated into the marginal layer, and almost simultaneously, a few fibers in that layer were myelinated. Cells migrating into the marginal layer formed reticular neurons as well as the raphe nuclei and superficial cellular layers of the optic tectum. As the development proceeded, the number of myelinated fibers in the marginal layer increased, and cells in that layer, especially reticular neurons, were seen to be embedded among numerous myelinated fibers, assuming the characteristic features of the reticular formation.

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PubMed1989

Thermal behaviour of A4 lactate dehydrogenase purified from the heterothermic and sympatric vertebrate species Brook lamprey (Lampetra planeri), tench (Tenca tenca), smooth (Triturus vulgaris) and alpine newt (Triturus alpestris).

1. The A4 lactate dehydrogenase isozyme was purified to homogeneity from the tissues of Brook lamprey (Lampetra planeri), tench (Tenca tenca), smooth newt (Triturus vulgaris) and alpine newt (T. alpestris). 2. These four species share their geographical distribution in the same freshwater habitats, often live together in the same station and two of them are congeneric. Steady-state kinetic investigations have shown that: 3. Km (apparent) for pyruvate vs. temperature and (apparent) product Ki (Pyruvate) and Ki (Lactate) are fairly similar among species; 4. kcat/Km decreases with temperature in the case of the newts but increases in the case of both lamprey and tench; 5. Thermostability does not correlate to preferred ambient temperature and, in particular, tench LDH starts being inactivated up to 65 degrees C. 6. Thermostability does not correlate with activation energy either; 7. No clear relationships can be demonstrated either between activation energy and conformational transitions in the molecule (these latter indicated by breaks in the Arrhenius plots) nor between activation energy and molecular flexibility, investigated by melting experiments.

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PubMed2007

A Bayesian approach on molecules and behavior: reconsidering phylogenetic and evolutionary patterns of the Salamandridae with emphasis on Triturus newts.

The monophyly of European newts of the genus Triturus within the family Salamandridae has for decades rested on presumably homologous behavioral and morphological characters. Molecular data challenge this hypothesis, but the phylogenetic position of Triturus within the Salamandridae has not yet been convincingly resolved. We addressed this issue and the temporal divergence of Triturus within the Salamandridae with novel Bayesian approaches applied to DNA sequence data from three mitochondrial genes (12S, 16S and cytb). We included 38 salamandrid species comprising all 13 recognized species of Triturus and 16 out of 17 salamandrid genera. A clade comprising all the "Newts" can be separated from the "True Salamanders" and Salamandrina clades. Within the "Newts" well-supported clades are: Tylototriton-Pleurodeles, the "New World Newts" (Notophthalmus-Taricha), and the "Modern Eurasian Newts" (Cynops, Pachytriton, Paramesotriton=together the "Modern Asian Newts", Calotriton, Euproctus, Neurergus and Triturus species). We found that Triturus is a non-monophyletic species assemblage, which includes four groups that are themselves monophyletic: (i) the "Large-Bodied Triturus" (six species), (ii) the "Small-Bodied Triturus" (five species), (iii) T. alpestris and (iv) T. vittatus. We estimated that the last common ancestor of Triturus existed around 64 million years ago (mya) while the root of the Salamandridae dates back to 95 mya. This was estimated using a fossil-based molecular dating approach and an explicit framework to select calibration points that least underestimated their corresponding nodes. Using the molecular phylogeny we mapped the evolution of life history and courtship traits in Triturus and found that several Triturus-specific courtship traits evolved independently.

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PubMed1990

Characterisation of a short, highly repeated and centromerically localised DNA sequence in crested and marbled newts of the genus Triturus.

A 32-33 bp highly repeated DNA sequence, TkS1, has been isolated from genomic DNA of the newt Triturus karelini digested with the restriction endonucleases HaeIII or AluI. TkS1 is known to be localised in the centromeric heterochromatin of all the chromosomes in T. karelini and the related species T. cristatus. TkS1 has been shown to be present in varying amounts in the genomic DNA of a range of species of Triturus, including representatives of the two main subgenera Triturus and Palaeotriton. A programme of sequencing of monomers, dimers and trimers of TkS1 was carried out in order to determine the level of conservation of the sequence within and between species of Triturus. Altogether 204 monomer (32/33 bp) clones were made of TkS1 from three individuals of T. karelini, and one individual each of T. cristatus, T. carnifex, T. dobrogicus and T. marmoratus, all members of the subgenus Triturus and the cristatus species group. A number of dimer (64 bp) and trimer (96 bp) clones were also made from DNA of a single specimen of T. karelini digested with HaeIII or AluI. Three distinct types of TkS1 were identified in all species examined, except for T. marmoratus where only two of the types were found. The types were distinguished on the basis of certain recurring divergent patterns in monomers sequenced from T. karelini. Type 1 is mainly characterised by the presence of an AluI site at positions 24-27 and type 3 mainly by the presence of an additional base (C) at position 14. Type 2 normally lacks the AluI site and the C at position 14, as well as having a number of other distinguishing features. TkS1 and its three types have remained remarkably constant in sequence since before the divergence of T. marmoratus from other species in the cristatus species group, about 10 million years ago. Examination of all 204 monomer clones and comparison with consensus sequences for the three types shows less than 5% divergence at any one position in the sequence. There is good evidence from examination of dimer and trimer clones of TkS1 that the different types are intermingled with each other, and all three types are likely to be present on all chromosomes. Dimeric (64 bp) TkS1 clones constructed from AluI fragments of T. karelini DNA show evidence of a trimeric (96 bp) "supertype" with the pattern type 1-type 3-type 1 that is much more common than would be expected on a random basis.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1991

Two dispersed highly repeated DNA families of Triturus vulgaris meridionalis (Amphibia, Urodela) are widely conserved among Salamandridae.

Two BamHI families of repeated sequences were characterized from the genome of the Italian smooth newt, Triturus vulgaris meridionalis (Amphibia, Urodela). The first family, which is divided into subfamilies, consists of tandemly arranged arrays whose basic repeat is around 398 bp long; these arrays are dispersed throughout the entire chromosome sets of the various species of Triturus tested. Moreover the family is widely conserved among Salamandridae, being detected by genomic DNA blotting of Notophthalmus viridescens, Taricha granulosa, Salamandrina terdigitata and Euproctus platycephalus. The second BamHI family is represented by a cloned sequence of 419 bp, which is dispersed in the chromosome set of several species of Triturus. The sequence is also conserved in S. terdigitata and in E. platycephalus but is not detectable in N. viridescens or T. granulosa. The cloned sequence is most probably only part of a longer unit interspersed within the Triturus genome.

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