Alessandro Ferracin

An electrophoretic polymorphism that mimics a true genetic polymorphism inTriturus cristatus carnifex (Amphibia, Urodela)

Phosphoglucomutase electrophoretic patterns have been studied in 60 tail homogenates ofTriturus cristatus carnifex. Our results show that the same sample produces a different electrophoretic pattern with homogenate ageing; a new band of intermediate mobility appears, together with the one produced by the fresh preparation. The phenomenon can mimic a true genetic polymorphism when differently stored samples are analyzed.

An ecological note on Triturus alpestris apuanus (Bonaparte) and Triturus cristatus carnifex (Laurenti) in the Garfagnana (Lucca, Central Italy)

Abstract We report the results of a preliminary study on the biology of Triturus alpestris apuanus (Bonaparte) and Triturus cristatus carnifex (Laurenti). The sample zone chosen was the Garfagnana. The water analysis of 14 stations, of three unoccupied ponds and of the “Troscia” pond, reveal that these Salamanders behave as “eury” species to the physico-chemical parameters of their environments. It is suggested that they belong to “biological accomodated” communities. Furthermore, three stations are considered with some detail which show particular characteristics, e.g. i) coexistence of newts and fishes; ii) very high salinity values; iii) coexistence of T. a. apuanus, T. c. carnifex and T. a. apuanus neotenic stage; iv) high degree of morphological polymorphism.

Comparative studies of hemoglobins from newts (Triturus cristatus, triturus vulgaris, triturus alpestris): A kinetic approach

Abstract 1. 1. The functional properties of three different species of newts i.e. Triturus cristatus carnifex, Triturus vulgaris meridionalis and Triturus alpestris apuanus have been studied by flash photolysis. 2. 2. In spite of the very different habitats the hemoglobins of the adult form of the three species do not show significant differences in functional behaviour. 3. 3. However the neotenic form of Triturus alpestris apuanus is characterized by the presence of a higher multiplicity of hemoglobin components as compared to that of the adult form. 4. 4. The experiments show that the new hemoglobin(s) is characterized by a more marked pH dependence and by a much higher rate constant for CO combination. 5. 5. This finding may be relevant to the compulsory aquatic life of the neotenic form of this amphibian.

Unusual steady-state kinetic properties of a chilopod enzyme: L(+)lactate dehydrogenase purified from Scolopendra cingulata.

Abstract 1. 1. Lactate dehydrogenase was purified to homogeneity from the chilopod Scolopendra cingulata. 2. 2. The enzyme has the usual molecular weight of approximately 150,000 and exists as a tetramer. It is l (+)lactate specific and some lines of evidence ascribe the molecule to the A-class (muscle-type of vertebrates). 3. 3. Surprisingly it displays Kcat values for both substrates pyruvate and lactate which are about two orders of magnitude lower than those known for other lactate dehydrogenases. 4. 4. Additionally, both Km for lactate and Kcat/Km for pyruvate are independent from assay temperature. 5. 5. The most striking feature of this enzyme, however, is its stability, as it still retains activity either after incubation at 90°C or in the presence of urea concentrations as high as 7.5 M.

Thermal behavior of a 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.

Thermal behaviour of a heterothermic enzyme: A4 lactate dehydrogenase from Triturus cristatus

Abstract The behaviour of T. cristatus A 4 lactate dehydrogenase at different temperatures was studied on the pure isoenzyme. The molecule displays a number of properties which do not conform to any current model of biochemical adaptation to temperature. Our hypothesis is that the structure of newt LDH evolved is such a way to become able to sustain its physiological action over the entire thermal range of the species, and thus no adjustment in kinetic features is needed when temperature varies.

An Analysis of the Lactate Dehydrogenase Isozyme System in Triturus alpestris and Triturus vulgaris

Lactate Dehydrogenase is a tetrameric enzyme formed by the product of at least two loci (Holmes, 1972; Holbrook et al., 1975), designated Ldh-A and Ldh-B. The former is preferentially expressed in skeletal muscle cells and in liver, the latter in kidney and heart. In a majority of the known cases the products of these loci give rise to homotetramers (A4 and B4) and they also hybridize forming three heterotetramers (A3B, A2B2, AB3). Since several exceptions to this rule have been found in fishes (Markert et al., 1975) and amphibians (Vogel & Chen, 1976), we investigated the LDH system in two European newts, Triturus alpestris apuanus and Triturus aulgaris meridionalis. The problem was examined by others with the same species (Faulhaber & Lange-Lyra, 1978) but in our opinion deserved more attention because the genetic basis of LDH inheritance in these species was not clearly settled, nor were the thermostability properties of the enzymes investigated.

Lactate dehydrogenase from Lampetra planeri is composed of chains of unique type which shoe intermediate properties between the heart and the muscle isozymes of vertebrates

1. Like other lamprey species, Lampetra planeri displays LDH chains of a single type. Since lampreys are more related to vertebrates than myxines, which do have usual A and B monomers, we suspect that either a gene inactivation or a gene loss occurred in the former group. 2. The characterization of the enzyme gave interesting results. From the standpoint of its affinity for ion exchangers, it behaves as if it is composed of A-type chains. 3. From the standpoint of substrate and product inhibition, it resembles much more closely the B containing isozyme. 4. Since literature reports that the other known single-chained LDHs from lampreys are definitely of the A type, we suggest the possibility that L. planeri enzyme underwent some orthologous evolution which brought it to resemble the heart isozyme.