Are the unusual morphological and physiological features of the leatherback turtle (Dermochelys coriacea) paralleled at the molecular level? A study on A4 (muscle-type) isozyme of its lactate dehydrogenase.

A4 (muscle-type) Lactate Dehydrogenase was purified to homogeneity from Dermochelys coriacea. The steady-state kinetic features of the enzyme show remarkable similarities with those displayed by many other heterothermal LDH's from cold-blooded vertebrates.

Characterization of glutathione transferase from Gammarus italicus.

1. By using affinity chromatography and chromatofocusing analysis at least two major glutathione transferases, named GST II and GST III can be isolated from Gammarus italicus. 2. GST II has an isoelectric point at pH 5.0 and is composed of two subunits with an apparent molecular mass of 28 KDa. 3. GST III which has an isoelectric point at pH 4.6 was found to be an heterodimer of 27 KDa and 28 KDa. 4. The 28 KDa subunit cross-reacted in immunoblotting analysis with antisera raised against pi class GST, whereas none of the antisera raised against alpha, mu and pi class GSTs cross-reacted with the 27 KDa subunit.

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.

Lactate dehydrogenase from Lampetra planeri is composed of chains of unique type which show 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 LDH's 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.

[Contribution to the knowledge of the biology of Cyclostomes: activity of aldolase in Lampetra planeri (Bloch) during its biological cycle]. / Contributo alla conoscenza della biologia dei Ciclostomi: attivita' aldolasica in Lampetra planeri (Bloch) durante il ciclo biologico.

It has been ascertained that in the Lampetra planeri (Bloch) the muscle and liver aldolase level in the last larval period in which lipids are accumulated strongly increases; this may be due to an increased synthesis or diminished degradation of the enzyme.

Early effects of cobalt chloride treatment on certain blood parameters and on urine composition.

The authors studied the variations of some blood parameters and urine composition during the first hours after CoCl2 treatment in rats and rabbits. These showed an increase in hematocrit with a decrease in plasma volume and, at the same time, a decrease in total proteinemia as well as in the albumin (rabbits) and gamma-globulin fractions. On the basis of observations carried out in rabbits, these phenomena are not seen if the cobalt is complexed with cysteine before treatment; moreover, they are at least partly reversed by cysteine administration soon after cobalt. Plasma Na+ and K+ concentrations do not show significant changes in CoCl2-treated rabbits; on the contrary, the excretion of such electrolytes, as well as urinary protein content, decreases. In addition, the urine of CoCl2-treated rabbits contains at least two pigmented substances with different molecular weights, which are separable by dialysis and DEAE-cellulose chromatography and both contain cobalt in different percentages. The authors believe that CoCl2 treatment leads to an early and profound increase in vascular permeability with depletion of plasmatic material in the tissues and hemoconcentration; moreover, the above stated phenomena seem to be correlated with the forming of cobalt complexes.

Erythrocyte acetylcholinesterase activity changes in the early stages of anemic and hypobaric hypoxia or after CoCl2 treatment in rabbits.

The authors studied the changes of erythrocyte acetylcholinesterase (AChE) activity in rabbits respectively subjected to bleeding, hypobaric hypoxia and CoCl2 treatment; in such conditions a rise of the enzyme activity was observed. Similar increases take place also as a consequence of intravenous infusions carried out by using lactic or hydrochloric acid. The authors suggest that these increases in the erythrocyte AChE activity are connected with the decrease of the pCO2 that occurs in the various experimental conditions achieved.