EFFECT OF DIETARY CONCENTRATION OF CRUDE AFLATOXIN ON MEIOTIC CHROMOSOMES, SPERM MORPHOLOGY AND SPERM COUNT IN MICE, MUS MUSCULUS.

Abstract

THE CLASTOGENICITY OF THE DIETARY CONCENTRATION OF CRUDE AFLATOXIN (MAINLY B1 AND UNDETECTABLE AMOUNT OF B2, G1 AND G2), HITHERTO WELL-KNOWN IN MITOTICALLY DIVIDING CELLS, WAS TESTED IN METAPHASE-I CHROMOSOMES OF PRIMARY SPERMATOCYTES OF ALBINO SWISS MICE, MUS MUSCULUS. THE TOXIN WAS ADMINISTERED ORALLY IN 50 +/- 10 PPB CONCENTRATION @ 0.05 UGM/ANIMAL/DAY FOR DURATIONS CORRESPONDING TO THE SPAN OF ONE (6 WEEKS) AND TWO (12 WEEKS) SPERMATOGENIC CYCLES. THE RESULTS REVEALED THAT THE FREQUENCY OF ABNORMAL METAPHASE-I PLATES WAS 3% IN THE CONTROL SET, AND AS HIGH AS 47% AFTER 6 WEEKS AND 38% AFTER 12 WEEKS OF TREATMENT. THE ABNORMAL CHROMOSOMES HAD BOTH STRUCTURAL (BREAKS, GAPS, FRAGMENTS, TRANSLOCATIONS, TERMINAL ASSOCIATIONS) AND GROSS (NUMERICAL CHANGES, CLUMPING, STICKINESS) TYPE CHANGES. THE INCIDENCE OF UNIVALENTS OF AUTOSOMES AND SEX-CHROMOSOMES ALSO INCREASED. WHEN THE GIEMSA-STAINED SMEARS OF SPERMS COLLECTED FROM CAUDA EPIDIDYMIS WERE SCREENED, THE FREQUENCY OF SPERM WITH ABNORMAL HEAD INCREASED SIGNIFICANTLY - 2.3 +/- 0.4% IN CONTROL AND 34.5 +/- 1.4% IN 6-WEEK TREATED ANIMALS. THESE STRUCTURAL ABNORMALITIES WERE COINCIDENTAL WITH A REDUCTION IN SPERM COUNT (COLLECTED FROM CAPUT EPIDIDYMIS) BY ABOUT 3.5 TIMES. THE RESULTS THUS SUGGEST THAT THE LONG-TERM CHRONIC EXPOSURE OF MICE TO DIETARY CONCENTRATION OF AFLATOXIN IS (I) CLASTOGENIC FOR MEIOTIC CHROMOSOMES ALSO, (II) CAPABLE OF INDUCING ABNORMALITIES IN SPERM-HEAD MORPHOLOGY AND DECREASING SPERM COUNT. THESE RESULTS ARE IN CONFORMITY WITH EARLIER FINDINGS WHERE THE SAME DOSE AND CONCENTRATION OF THE TOXIN COULD CAUSE HISTOPATHOLOGIC DEGENERATION IN TESTES AND REDUCTION IN FERTILITY.