[Environmental exposure and blood levels of benzene in gas station attendants. Comparison with the general population]. / Esposizione ambientale e livelli ematici di benzene negli addetti agli impianti di distribuzione carburanti. Confronto con la popolazione generale.

Environmental benzene levels were measured in 26 petrol stations using both active and passive stationary and personal samplers. Simultaneously, benzene levels were measured in the petrol station operators on blood samples collected at the end of the work shift and the following morning before starting work. The petrol stations belonged to various different oil companies and were studied both during the winter (9 stations) and in the summer (17 stations). The environmental levels measured with active samplers in the 26 stations were on average 256 ng/l, were significantly lower (98 ng/l) in winter and higher (326 ng/l) in summer. The blood levels of benzene in 77 workers at the end of the work shift were on average 548 ng/l, were significantly lower (306 ng/l) in winter and higher (651 ng/l) in summer. The following morning, blood levels of benzene were lower than those found at the end of the work shift, on average 249 ng/l in winter and 427 ng/l in summer. Smokers had higher benzene levels than non-smokers, both in winter at the end of the work shift (617/170 ng/l) and the following morning (506/137 ng/l), and in summer at the end of the shift (742/517 ng/l) and the following morning (535/233 ng/l). A comparison with a sample of 243 "normal" subjects of the general population showed that their mean blood level of benzene of 165 ng/l was significantly lower than the level found in petrol station workers the morning after the work shift (364 ng/l).

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.

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.

A neutral theory of biogenesis.

The selective Darwinian theory of chemical evolution is critically reviewed and the tentative conclusion is reached that neither the theoretical analyses nor the experiments with phages can really prove it. An alternative proposal is put forth which considers the possibility that the biogenetic process has been driven by stochastic forces, e.g. it took place in the absence of Darwinian selection which, in turn, started only when the first protocells came into existence. The dynamics of the early self-organization of living structures should be understood in terms of self-assembly. The complexification of living matter is thus not represented as a gradual phenomenon but as a series of abrupt and relatively fast transitions consisting in the aggregation of pre-systems which had evolved by their own. The shift towards new and variegated states proposed by the bifurcation theory are not considered particularly relevant for reasons reported in the test, nor is it believed that dissipation can entirely account for the order observed in living cells.

Functional properties of hemoglobins from Triturus cristatus.

The functional properties of hemoglobins from Triturus cristatus carnifex have been characterized both from an equilibrium and a kinetic point of view. A special attention has been given to the effect of organic phosphates in view of their role in the modulation of the hemoglobin function. Under stripped conditions newt hemoglobins display a negative Bohr effect which becomes much less pronounced in the presence of 0.2 M inorganic phosphates. The effect of organic phosphates involves not only a drop in the O2 affinity but also a large change in the shape of the O2 Bohr effect which becomes markedly positive in the presence of myo-inositol hexakis(phosphate). The experimental data reported make it possible to give a complete picture of the functional behaviour of newt hemoglobins, making a contribution to clarifying the dependence of the sign of the Bohr effect on the acclimatization temperature of the animals that has been previously reported [Morpurgo, G., Battaglia, P. A. and Leggio, T. (1970) Nature (Lond.) 225, 76--77].

Unchanged antigenic properties of a nuclear non-histone protein during phylogenesis.

The phyletic distribution of Sm antigen in eukaryotes has been investigated by means of immuno-chemical techniques. This nuclear antigen, which is an acidic glycoprotein of about 7S with DNA binding ability, is present in all organisms examined. Such evidence suggests a very slow evolutionary rate for at least the antigenic determinant(s) of the Sm antigen.

An electrophoretic polymorphism that mimics a true genetic polymorphism in Triturus cristatus carnifex (Amiphibia, Urodela).

Phosphoglucomutase electrophoretic patterns have been studied in 60 tail homogenates of Triturus 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.

The measure-unit of evolution.

A theoretical study on evolution has been carried out, with the aim of disproving some value judgements essentially represented by the idea that the degree of evolution can increase. Our conclusions are based upon the preliminary statement that efficiency of survival is directly related to regulative ability. On this ground our reasoning led us to conclude that: (i) actual fitness measure units derive from an anthropocentric bias, and they mainly evaluate similarity to man rather than some objective parameter; (ii) a complete and meaningful unit is, at present, impossible to achieve in practice; (iii) since the study of evolution is only descriptive, and since the evolutionary process is time dependent, every ecological dominant living today must be considered as the most fitted to its environment; (iv) the view we can have of evolution is simply a transection, so that many generalized phyletic trees are trivial and it is impossible to claim the persistence today of those "ancestor organisms" upon which such trees are constructed. Moreover, a functional definition of the term "organism" is given, following criteria drawn from bioenergetics and from biological hierarchization. The concluding step is the assemblage of a slightly heterodox model for evolution.