Survival of larvae of Nippostrongylus brasiliensis (nematoda) in solutions of toxic substances.

The aim of this study was to determine the action of zinc, copper, lead and cadmium compounds upon N. brasiliensis invasive nematode larvae. The tested larvae were kept in ZnCl2, CuCl2, Pb(NO3)2 and CdCl2 solutions. The concentrations of toxic substances applied for the study corresponded with level of environmental pollution. All toxins reduced life-space of larvae. In control group they survived about 69 days. In solutions of the Zn, contaminated with 10, 50, 100 and 200 ppm of toxic substance, they survived 42, 16, 14 days and 72 hours. In solution of Cu, contaminated with 5, 10, 50 and 200 ppm of toxin, life--space was reduced to 51, 21, 7 days and 54 hours, respectively. Lead reduced live--space of larvae to 26 days already at the low concentration of 10 ppm and in all higher concentrations (20, 50 and 200 ppm) their survival changed insignificantly (to 22 days). In solution of Cd, contaminated with 0.1 and 0.3 ppm larvae died after 39 and 17 days, respectively, while at higher concentrations of this toxin (3 and 10 ppm) larvae survived only 54 and 30 hours, respectively.

Effect of zinc on invasive capacity and reproduction of Nippostrongylus brasiliensis (Nematoda) in rats.

The influence of zinc on the invasive capacity and reproduction of Nippostrongylus brasiliensis nematodes was examined in three successive generations: P-the larvae which were exposed to zinc solution (in the concentration of 50 ppm), and F1 and F2 derived from these intoxicated larvae. Migration and settlement capacity were defined by the number of larvae in lungs 24 hours post infection (hpi), and the number of adult nematodes in the small intestine 96, 114 and 236 hpi. Reproduction capacity was defined by the number of eggs in 1 g of faeces of infected rats. The invasive capacity of larvae declined in relation to control (C) group in all examined generations of N. brasiliensis. Surprisingly the decline was the lowest in generation P (directly intoxicated) and the greatest in generation F2. Reproduction of the nematodes declined considerably in P and F1, being similar in these two generations, while in F2 it was higher than in two former generations, and almost the same as in group C.

[Adaptability of Nippostrongylus brasiliensis (Travassos, 1914) to lead contamination]. / Adaptacje Nippostrongylus brasiliensis (Travassos, 1914) do skazenia olowiem.

It was investigated whether toxicity of lead (Pb) is so high that its effect on Nippostrongylus brasiliensis larvae could be transferred into subsequent (3) generations of the nematode. Wistar rats were infected with a dose of 1000 N. brasiliensis larvae contaminated with Pb (9 days at 200 ppm in solution). The number of larvae in lungs after 24 and 42 hours and the number of adult nematodes in the small intestine after 90, 114 and 236 hours after infection were examined. To determine reproduction of the N. brasiliensis the number of eggs was determined. Eggs of the first generation subjected to Pb (P generation) were used to culture a subsequent generation of invasive larvae (F1) which were used to infect rats. Eggs from that generation were used to culture the next invasive larvae generation (F2) used again to infect rats. Lungs dissection after 24 hours has shown that the P generation produced 12 times less larvae than the control, while generations F1 and F2 produced 4,9-5 times less larvae than the control. Dissection data for the small intestine show the highest loss in invasive capability of this nematode in generation F1. The dynamics of eggs excretion is the lowest in F1 and excretion period is shorter by 1 day. In F2, the number of eggs excreted is 5.8 times higher than in the control group. It seems that in F2 generation mechanisms enabling the species to survive under unfavorable environmental conditions were started.

[Effect of lead on invasion and reproduction of Nippostrongylus brasiliensis (Travassos, 1914)]. / Wplyw olowiu na inwazyjnosc i rozrodczosc nicienia Nippostrongylus brasiliensis (Travassos, 1914).

Influence of the lead on the biology of Nippostrongylus brasiliensis was examined. N. brasiliensis larvae exposed to the action of 200 ppm lead during 9 days were used to infect rats. The first group of the rats were infected with 1000 larvae kept in the solution of PBS whereas the larvae contaminated with the lead were given to the second group of rats. Capability to invasion of the contaminated larvae decreased by 28.7-57.2%. Reproduction of the N. brasiliensis decreased by 40.6% and the maximum point of production of the eggs was moved back by one day.