Chromosome fragility in two sheep flocks exposed to dioxins during pasturage.

In the last 3 years several farms raising cattle, river buffalo and sheep have been unable to sell dairy milk due to the presence of high levels of dioxins. Furthermore, several cases of abortion (around 25% of total births) and abnormal foetuses (2.5% of total births) were recorded in two flocks of sheep raised in the province of Naples where a higher level of dioxins (5.27 pg/g fat, as human WHO TCDD equivalent) have been found in the milk mass than that permitted (3.0 pg/g fat, as human WHO TCDD equivalent). Cytogenetic investigations were carried out on 24 sheep (all females), randomly sampled from the two different flocks, one abnormal foetus and 11 female sheep (control) raised approximately 80 km from the area where the two exposed flocks were raised. Frequencies of aneuploid cells, gaps, chromatid breaks, chromosome breaks, fragments and sister chromatid exchange (SCE) were determined. While no differences were observed between the number of aneuploid cells (15% of total cell population) of both exposed animals and controls, significant (P < 0.001) increases in the frequencies of other chromosome abnormalities (mean chromosome abnormality/cell = 0.76 +/- 1.1) and SCEs (mean SCE/cell = 9.4 +/- 3.7) were found in the exposed animals, compared with the control (mean chromosome abnormality/cell = 0.18 +/- 0.4; mean SCE/cell = 7.1 +/- 3.0). Significantly higher values of SCEs (mean SCE/cell = 10.9 +/- 4.4) were also found in the abnormal foetus compared with the control. Chemical analyses on soil, grass and water at two sites where the two flocks were pastured established that doses of dioxins (17 different types) were below the legally permitted limits.

The accumulation of alpha-Tocopherol and Retinol in the milk of water buffalo is correlated with the plasma levels of triiodothyronine.

Milk is the most important source of Retinol and alpha-Tocopherol for calves. These antioxidants save the food quality and prevent lipid oxidation in the mammary gland and the calf growing tissues. In Bubalus bubalis, seasonal changes for the plasma levels of both antioxidants were not found. The levels of Retinol and alpha-Tocopherol in the milk were 2 and 1.7 times higher in winter than in summer, respectively. These levels were correlated with the plasma level of triiodothyronine, and markedly increased in cows injected with triiodothyronine in summer. The cytosol from alveolar epithelial cells of mammary glands was incubated with alpha-Tocopherol and 3H-Retinol and, after gel filtration chromatography, both antioxidants were found associated with proteins migrating as a single peak of 33 kD. The amount of alpha-Tocopherol and Retinol binding proteins was 1.5 and 2.3 times higher in winter than in summer respectively. The Retinol binding proteins migrated as two bands (33 and 16 kD) by electrophoresis in denaturing and reducing conditions. Our data suggest that triiodothyronine enhances the transport of both liposoluble antioxidants through the blood-mammary barrier, and demonstrate that proteins of the mammary epithelial cells are involved in such a transport.