Toxicity evaluation of novel imidacloprid nanoribbons, using somatic mutation and fitness indexes in Drosophila melanogaster.

Nanoribbons of imidacloprid, a systemic and chloronicotinyl insecticide, were successfully synthesized by laser-induced fragmentation/exfoliation of imidacloprid powders suspended in water, with widths ranging from 160 to 470 nm, lengths in the micron scale, and thickness of a few atoms layers. The aim of the present study was to examine the effects of acute and chronic exposure to imidacloprid (IMC) bulk and compare its effects with synthesized imidacloprid nanoribbons (IMCNR) on larval and adult viability, developmental time, olfactory capacity, longevity, productivity, and genotoxicity in Drosophila melanogaster. Larvae or adults were exposed at 0.01, 0.02, or 0.03 ppm to IMC or IMCNR. Results demonstrated that IMCNR produced a significant reduction in viability and olfactory ability. IMC did not significantly alter viability and olfactory ability. Similarly, marked differences on longevity were detected between treatment with IMC and IMCNR where the lifespan of males treated with IMC was significantly higher than control while IMCNR produced a reduction. As for productivity, developmental time, and genotoxicity, no marked differences were found between both forms of IMC.

Genotoxic action of bifenthrin nanoparticles and its effect on the development, productivity, and behavior of Drosophila melanogaster.

Rapid development of nanotechnology, particularly nanoparticles of pesticides, has facilitated the transformation of traditional agriculture. However, testing their effectiveness is essential for avoiding any environmental or adverse human health risk attributed to nanoparticle-based formulations, especially insecticides. Recently, organic nanoparticles of bifenthrin, a pyrethroid insecticide, were successfully synthesized by laser ablation of solids in liquid technique, with the most probable size of 5 nm. The aim of the present study was to examine the effects of acute exposure to bifenthrin (BIF) or bifenthrin nanoparticles (BIFNP) on larval-adult viability, developmental time, olfactory capacity, longevity, productivity defined as the number of eggs per couple, and genotoxicity in Drosophila melanogaster. Data demonstrated that BIFNP produced a marked delay in developmental time, significant reduction in viability and olfactory ability compared to BIF. No marked differences were detected between BIF and BIFNP on longevity and productivity. Genotoxicity findings indicated that only BIF, at longer exposure duration increased genetic damage.

Relationship between viability and genotoxic effect of gamma rays delivered at different dose rates in somatic cells of Drosophila melanogaster.

The role of dose rate (DR) on biological effects of ionizing radiation is an area of significant research focus and relevant to environmental exposures. The present investigation was aimed to examine the direct relationship between viability and genotoxicity in Drosophila melanogaster, induced by gamma rays in a range of doses from 2 to 35 Gy administered at three different DR. Results indicated that larval-adult viability was reduced in relation to dose but not DR. No marked differences were found in the LD50 produced by differing DR tested. Frequencies of somatic mutation and recombination increased in direct correlation with dose and DR. Data demonstrate the importance of determination of the relationship between viability and genotoxicity induced by DR in in vivo systems for toxicological and radioprotection studies.

Evaluating the effect of low dose rate of gamma rays in germ cells of Drosophila melanogaster.

Purpose: Evaluation of genetic risk in germ cells is still matter of research, mainly due to their role in the transmission of genetic information from one generation to another. Although numerous experiments have been carried out in Drosophila in order to study the effect of radiation on germ cells, the role of dose rate (DR) has not been fully explored. The purpose of this study was to evaluate the action of DR on the radioprotection induction on male germ cell of D. melanogaster.Material and method: The productivity and the sex-linked recessive lethal (SLRL) tests were used to evaluate the radio-sensitivity of different states of the germ line of males. Two-day-old males of Canton-S wild type strain were pretreated with 0.2 Gy at 5.4 or 34.3 Gy/h of gamma rays from a 60Co source, three hours later, they were irradiated with 20 Gy at 907.7 Gy/h. Thereafter, each single male was crossed with 3 five-day old Basc virgin females, that were replaced every other day by new females. This procedure was conducted three times, to test the whole germ cell stages.Results: Females crossed with males irradiated with 0.2 Gy at both DR tested, laid a higher number of eggs than control, but egg-viability was reduced. On the other hand, in the group of 0.2 Gy + 20 Gy -combined treatments- the total number of eggs laid decreased only when 0.2 Gy were delivered at 34.3 Gy/h however, the egg-viability increased. The dose of 0.2 Gy at both DR did not modify the baseline frequency of SLRL. A tendency to decrease in the frequency of lethals in brood III was found in combined treatments at both DR.Conclusion: The fact that 0.2 Gy at 5.4 or 34.3 Gy/h induced an increase in the egg-viability and a tendency to decrease the genetic damage in pre-meiotic cells provoked by 20 Gy, might indicate the induction of any mechanism that could be interpreted as radioprotection in male germ cells of D. melanogaster. Results emphasize the need to carry out more studies on the effect of the DR on the induction of genetic damage in germ cells.

Antimutagenic action of the live yeast can be transmitted to the offspring of Drosophila melanogaster. A genetic study using the wing spot assay.

The present study evaluates whether the protective effect of live yeast (LY) against direct and indirect mutagenic agents, persists in the offspring from individuals fed with LY. The wing-spot test in Drosophila was used; four different mates were performed: a) neither females nor males were fed with LY-enriched food (NLYxNLY); b) only females were fed (LYxNLY); c) males were fed (NLYxLY) or d) both progenitors were fed (LYxLY). Results confirm that LY strongly stimulates fecundity in females but not in males and provides strength to the egg for survive. A greater reduction in mutation rate was observed when females were feed, in the following relationship: LYxNLY>LYxLY>NLYxLY. No protection was found against action in any of the promutagens tested. Results suggest that LY has a very powerful antimutagenic action, predominantly against the action of ionizing radiation and Chromium trioxide that can be transmitted mainly through the female.

Evidence that the radioprotector effect of ascorbic acid depends on the radiation dose rate.

Many studies have revealed that ascorbic acid (Aa) acts as a powerful inhibitor of genetic damage. The objetive of the present study was to evaluate the radioprotector effect of Aa at two diferent radiation dose rates. The somatic mutation and recombination test in Drosophila melanogaster was used. 48 h larvae were treated for 24 h with 25, 50 and 100 mM of Aa. After pretreatment, larvae were irradiated with 20 Gy of gamma rays administered at 36 or 960 Gy/h. Toxicity, development rate and frequency of mutant spots were recorded. Results provide evidence of a radioprotective effect for all tested concentrations of Aa only when 20 Gy were delivered at 36 Gy/h and only with 25 mM using the 960 Gy/h. To consider the use of Aa as radioprotector or therapeutic agent, it is necessary to know its potential under different situations to avoid unwanted injuries.

A Further Study of the Role of Copper in Regard to the Antimutagenic Action of Sodium Copper Chlorophyllin (SCC) in Somatic Cells of Drosophila melanogaster.

Previous findings suggest that copper plays a crucial role in the antimutagenic effect of sodium copper chlorophyllin (SCC). The objective of the current research was to compare the antimutagenic effects of two SCC compounds with different amounts of copper (3.7% and 5.4%, respectively) on the genetic damage induced by gamma rays in somatic cells of Drosophila. Data indicate that an increase in copper content of 31.5% in SCC-5.4 resulted in a greater inhibition of gamma ray genetic damage of 49% whereas only a 2% inhibition with SCC-3.7 occurred. Of greater interest is the association of SCC with a variety of uses in humans, such as a chemo preventive agent and food supplement. A greater attention to the concentration of copper in the SCC product in use should be required.