In vitro proliferation of achondroplastic and normal mouse chondrocytes, before and after basic fibroblast growth factor stimulation.

Achondroplasia in mice is a recessive genetic disorder, characterized by disproportionate dwarfism with reduced bone growth. The cause of this chondrodystrophy is unknown. In this study normal and achondroplastic mouse chondrocytes were cultured in monolayer primary culture, their differentiation was verified by immunofluorescence and their growth was compared. The results showed that achondroplastic cells exhibited a higher proliferative activity than control cells of the same age, confirmed also by a thymidine incorporation assay. Furthermore, basic fibroblast growth factor treatment was found to induce a strong increase in growth of normal mouse chondrocytes, while it did not stimulate statistically significant proliferation of achondroplastic mouse cells. We suppose that this different growth rate could play a role in achondroplastic phenotype development.

Induction of micronuclei in bone marrow by two pesticides and their differentiation with CREST staining: an in vivo study in mice.

Two pesticides, organophosphate phosphamidon (PHO) and organochlorine dieldrin (DED) were assayed by the mouse bone marrow micronucleus test, to ascertain whether they showed genotoxic activity in vivo. Two doses, sub-lethal (PHO=3 mg/kg b.wt.; DED=60 mg/kg b.wt.) and lethal (PHO=5 mg/kg b.wt.; DED=90 mg/kg b.wt.), of each substance were administered intraperitoneally to 9-10-week old CBA male mice, in acute and repeated exposure. The sub-lethal dose was also administered at two different times and twice at 24-h intervals. Both PHO and DED proved able to induce a dose-dependent increase of micronucleated polychromatic erythrocytes (PCE). The two pesticides also showed a different detoxification time. Furthermore, the CREST staining with antikinetochore antibodies allowed us to conclude that the two chemicals are clastogens.

The 'natural' hybrid haemoglobin from mule. Interrelationships with its parent haemoglobins from horse and donkey.

The equilibrium O2-binding properties of the hybrid haemoglobin (Hb) present in vivo in erythrocytes from mule and of its parent Hbs from horse and donkey were compared with special reference to the effect of heterotropic ligands such as Cl-, D-glycerate 2,3-bisphosphate (DPG) and inositol hexakisphosphate. All these Hbs display a decreased effect by polyphosphates, confirming that what has been observed for horse Hb [Giardina, Brix, Clementi, Scatena, Nicoletti, Cicchetti, Argentin & Condò (1990) Biochem. J. 266, 897-900] is common to other equine species, at least from a qualitative standpoint. However, different quantitative aspects can be detected, which can be accounted for by a different role for the two types of chain in characterizing the binding free energy for the various heterotropic effectors. In particular, it is shown that the binding mode of DPG and inositol hexakisphosphate displays different features since long-range effects can be observed clearly for inositol hexakisphosphate but not for DPG. In general terms, in spite of a different intrinsic O2 affinity, the modulation of functional properties by third ligands leads these Hbs to behave, under physiological conditions, similarly to human HbA. It might represent an interesting example of how different species with similar functional needs find different ways to produce a similar functional behaviour.

Investigations on the PGM (phosphoglucomutase) polymorphism by isoelectric focusing in Drosophila melanogaster.

Pgm allele frequencies of 383 individuals were determined in a sample of Drosophila melanogaster from three laboratory Sardinian populations, using the techniques of standard electrophoresis, heat denaturation, and isoelectric focusing. The analysis of the progeny obtained from informative crosses showed that the isoelectric focusing patterns segregate in a Mendelian way. The Pgm1.00 and Pgm0.70 electrophoretic alleles displayed different isoelectric points, whereas the Pgm1.00,tr and Pgm1.00,ts isoelectrophoretic alleles could not be differentiated when tested by isoelectric focusing. Moreover, the Pgm0.70,ts allele was split into two classes, with isoelectric points of pH 6.4 and pH 6.6.

Differences between horse and human haemoglobins in effects of organic and inorganic anions on oxygen binding.

Despite the fact that the horse is one of the more common domesticated animals, there are few reports dealing with the properties of its blood, and no comprehensive study has been performed on the reactivity of horse haemoglobin towards organic and inorganic ions. Here we report data on the effects of the organic phosphates D-glycerate-2,3-bisphosphate (2,3-DPG) and InsP6, and of chloride on the properties of horse haemoglobin. Thus the effect of saturating concentrations of 2,3-DPG on the oxygen affinity of horse haemoglobin is about 60% lower than with human adult haemoglobin under the same experimental conditions. The same applies also to InsP6, whose effect on oxygen binding to horse haemoglobin is decreased by about 55% compared with human adult haemoglobin. On the whole, horse haemoglobin appears to be much less sensitive to organic phosphates than previously believed. These results are discussed in the light of the primary structure of the molecule.

The segregation distortion (SD) phenomenon in wild populations of Drosophila melanogaster: interaction between chromosomes 3 and SD chromosomes 2.

The Segregation Distortion (SD) phenomenon is a typical case of non-Mendelian segregation in Drosophila melanogaster, due to the dysfunction of sperm bearing a non-SD homologous chromosome. In nature, several factors involved in the expression of the SD phenomenon have been described; among these, a genetic modifier carried by chromosome 3, which enhances the distortion effect of the SD chromosomes. The analysis of natural Sardinian populations, carried out in order to evaluate the presence of chromosome 3 bearing these enhancer factors, has enabled us to ascertain that (a) also in these populations chromosomes 3 with enhancer factors are present, although with frequencies lower than those previously reported in other publications; (b) among these enhancer chromosomes 3, some increase the k of certain chromosomes 2 from values of chromosomes considered non-distorting (k less than or equal to 0.66) to value typical of SD chromosomes. The data obtained also allow us to put forward some considerations regarding the dynamics of the SD phenomenon in Sardinian populations, where the frequency of SD chromosomes is fairly elevated.