Évaluation de l'impact de produits toxiques sur le criquet de montagne Gomphocerus sibiricus (colchicine et 6-mercaptopurine)

Abstract

We use Gomphocerus sibiricus, a very common locust, strictly located between 2 000 and 2 800 m, in order to test its degree of susceptibility when treated with toxic agents. This species is extremely useful for histological investigations, all its organs having large cells, the fine structure of which appears quite remarkable. Our aim is to establish a practical method for evaluating industrial air poisoning, the consequences of which are soil and grass-eater poisoning.The present work is only a first step where we use two well known drugs, 6-mercaptopurine, a powerful antimetabolite, and colchicine, strongly antimitotic. We studied three mitotic rich tissues: testis, midgut epithelium and cœcal epithelium. (i) 6-MP induces chromosomal abnormalities even with a low dosage of the drug. During prophase, it appears that the colorability into each chromosome can be extremely irregular, leading to the idea of an excessive asynchronism. Breakage and loss of chromosomes have been frequently observed, inducing multinuclear and giant cell formation. All this corresponds to what can be called ‘antimetabolic syndrome’, (ii) Colchicine induces well known mitotical abnormalities depending on microtubule disturbance: at 3.6 and 1.7·10⁻⁴ M, this drug induces essentially classical ball and exploded metaphases which are considered as arrested mitosis (stathmocinesis). Moreover, we saw that a low dosage, 0.8·10⁻⁴ M, first induces a stimulation of mitosis for 4 hours, then a true antimitotic effect finally leading to synchronization (13^th hour) as a recovery. We can underline the fact that Gomphocerus clearly shows a differential cellular and mitotical sensitivity when treated with the drugs we used; consequently, this species appears very useful for experimental histo-cytological research. The complex, but clear-cut organisation of locusts is an advantage which gives us opportunities for ulterior research, histological or not, working with other drugs the effects of which could also concern other organs.