Zearalenone Does Not Show Genotoxic Effects in the Drosophila melanogaster Wing Spot Test, but It Induces Oxidative Imbalance, Development, and Fecundity Alterations.

Zearalenone (ZEN) is a non-steroidal mycoestrogen produced by the Fusarium genus. ZEN and its metabolites compete with 17-beta estradiol for cytosolic estrogen receptors, causing reproductive alterations in vertebrates. ZEN has also been associated with toxic and genotoxic effects, as well as an increased risk for endometrial adenocarcinomas or hyperplasia, breast cancer, and oxidative damage, although the underlying mechanisms remain unclear. Previous studies have monitored cellular processes through levels of transcripts associated with Phase I Xenobiotic Metabolism (Cyp6g1 and Cyp6a2), oxidative stress (hsp60 and hsp70), apoptosis (hid, grim, and reaper), and DNA damage genes (Dmp53). In this study, we evaluated the survival and genotoxicity of ZEN, as well as its effects on emergence rate and fecundity in Drosophila melanogaster. Additionally, we determined levels of reactive oxygen species (ROS) using the D. melanogaster flare and Oregon R(R)-flare strains, which differ in levels of Cyp450 gene expression. Our results showed that ZEN toxicity did not increase mortality by more than 30%. We tested three ZEN concentrations (100, 200, and 400 µM) and found that none of the concentrations were genotoxic but were cytotoxic. Taking into account that it has previously been demonstrated that ZEN administration increased hsp60 expression levels and apoptosis gene transcripts in both strains, the data agree with an increase in ROS and development and fecundity alterations. Since Drosophila lacks homologous genes for mammalian estrogen receptors alpha and beta, the effects of this mycotoxin can be explained by a mechanism different from estrogenic activity.

Effects of Fructose and Palmitic Acid on Gene Expression in Drosophila melanogaster Larvae: Implications for Neurodegenerative Diseases.

One of the largest health problems worldwide is the development of chronic noncommunicable diseases due to the consumption of hypercaloric diets. Among the most common alterations are cardiovascular diseases, and a high correlation between overnutrition and neurodegenerative diseases has also been found. The urgency in the study of specific damage to tissues such as the brain and intestine led us to use Drosophila melanogaster to study the metabolic effects caused by the consumption of fructose and palmitic acid in specific tissues. Thus, third instar larvae (96 ± 4 h) of the wild Canton-S strain of D. melanogaster were used to perform transcriptomic profiling in brain and midgut tissues to test for the potential metabolic effects of a diet supplemented with fructose and palmitic acid. Our data infer that this diet can alter the biosynthesis of proteins at the mRNA level that participate in the synthesis of amino acids, as well as fundamental enzymes for the dopaminergic and GABAergic systems in the midgut and brain. These also demonstrated alterations in the tissues of flies that may help explain the development of various reported human diseases associated with the consumption of fructose and palmitic acid in humans. These studies will not only help to better understand the mechanisms by which the consumption of these alimentary products is related to the development of neuronal diseases but may also contribute to the prevention of these conditions.

Variation in resistance to oxidative stress in Oregon-(R)R-flare and Canton-S strains of Drosophila melanogaster.

All aerobic organisms are susceptible to damage by reactive oxygen species (ROS). ROS-induced damage has been associated with aging and diseases such as metabolic syndrome and cancer. However, not all organisms develop these diseases, nor do they age at the same rate; this is partially due to resistance to oxidative stress, a quantitative trait attributable to the interaction of factors including genetics and environmental. Drosophila melanogaster represents an ideal system to study how genetic variation can affect resistance to oxidative stress. In this work, oxidative stress (total and mitochondrial ROS), antioxidant response, and Cap 'n' collar isoform C and Spineless gene expression, one pesticide resistant (Oregon R(R)-flare) and wild-type (Canton-S) strains of D. melanogaster, were analyzed to test resistance to basal oxidative stress. ROS, catalase, and superoxide dismutase were determined by flow cytometry, and Cap 'n' collar isoform C and Spineless expression by qRT-PCR. The intensity of oxidative stress due to the pro-oxidant zearalenone in both was evaluated by flow cytometry. Data confirm expected differences in oxidative stress between strains that differ in Cyp450s levels. The Oregon (R)R-flare showed greater ROS, total and mitochondrial, compared to Canton-S. Regarding oxidative stress genes expression Cap 'n' collar isoform C and Spineless (Ss), Oregon R(R)-flare strain showed higher expression. In terms of response to zearalenone mycotoxin, Canton-S showed higher ROS concentration. Our data show variation in the resistance to oxidative stress among these strains of D. melanogaster.

Genotoxicity and cytotoxicity evaluation of two thallium compounds using the Drosophila wing somatic mutation and recombination test.

Thallium (Tl) is a heavy and toxic metal and a byproduct of several human activities, such as cement production, mining, and coal combustion. Thallium is found in fruits, vegetables, and animal fodder with high Tl contamination; therefore, it is an environmental pollution issue and a toxicological contamination problem for human beings and other organisms when exposed to it. The mutagenic potential of Tl and its compounds is controversial, and there are few in vivo studies on its effects. We conducted the animal bioassay Drosophila wing somatic mutation and recombination test (SMART) to test for genotoxicity and assessed the genotoxic effects of Tl acetate (TlCH3COO) and Tl sulfate (Tl2SO4) on Drosophila melanogaster. Third instar larvae from the SMART standard cross (ST) were fed Tl acetate [0.2, 2, 20, 200, 600 and 1200 µM] and Tl sulfate [0.2, 2, 20, 200, and 600 µM]. Hexavalent chromium [CrO3, 500 µM] served as the positive control, and Milli-Q water served as the negative control. Only the high Tl2SO4 [600 µM] concentration resulted in genotoxicity with 87.6% somatic recombination, and both salts disrupted cell division of wing imaginal disc cells, showing the expected cytotoxic effects. Genotoxic risks due to high metal levels by bioaccumulation of Tl+1 or its compounds require further evaluation with other in vivo and in vitro assays.

Genotoxicity assessment of four novel quinazoline-derived trypanocidal agents in the Drosophila wing somatic mutation and recombination test.

Chagas disease, caused by the protozoan Trypanosoma cruzi, has increased in the world due to migration, travelling and climate change; at present, the principal problem is that common trypanocidal agents have resulted in toxic or inconvenient side effects. We tested for genotoxicity in the standard (ST) and high bioactivation (HB) crosses of Drosophila wing somatic mutation and recombination test, four novel trypanocidal agents derived from 2, 4, 6-triaminquinazoline (TAQ): 2,4-diamino-6 nitro-1,3 diazonaftalene (S-1QN2-1), 2,4-diacetamino-6-amino 1,3 diazonaftalene (D-1), N6-(4,methoxybenzyl)quinazoline-2,4,6-triamine (GHPM) and N6-[4-(trifluoromethoxy)benzyl]quinazoline-2,4,6-triamine (GHPMF) at 1.9, 3.9, 7.9 and 15 µM, respectively. Also, high-pressure liquid chromatography (HPLC) analysis was run to determine the remanence of either drug in flare, and Oregon R(R)-flare flies emerged from treated larvae. S-1QN2-1 showed genotoxicity only in the ST cross, increasing the small, large and total spot frequencies at all concentrations and twin spots only at 1.9 µM; D-1 and GHPM showed significant increments of large spots only at 15 µM in the ST cross; GHPMF was not genotoxic at any concentration or either cross. In the mwh clones accumulated distribution frequencies analysis, associated with disrupted cell division, S-1QN2-1 caused alterations in the ST cross at all concentrations but only at 15 µM in the HB cross; D-1 caused alterations at 3.9, 7.9 and 15 µM in the ST cross and at 1.9 and 15 µM in the HB cross; GHPM caused alterations at 7.9 and 15 µM in the ST cross and also at 1.9, 3.9 and 7.9 µM in the HB cross; GHPMF caused those alterations at all concentrations in the ST cross and at 1.9, 3.9 and 7.9 µM in the HB cross. The HPLC results indicated no traces of either agent in the flare and Oregon R(R)-flare flies. We conclude that S-1QN2-1 is clearly genotoxic, D-1 and GHPM have an unclear genotoxicity and GHPMF was not genotoxic; all quinazoline derivatives disrupted cell division. GHPMF is a good candidate to be tested in other genotoxicity and cytotoxic bioassays. The differences in the genotoxic activity of these trypanocidal agents are correlated with differences in their chemical structure.

Verbascoside is not genotoxic in the ST and HB crosses of the Drosophila wing spot test, and its constituent, caffeic acid, decreases the spontaneous mutation rate in the ST cross.

Verbascoside (VB) is a phenylpropanoid isolated from Buddleja species, some of which originate in Mexico, and was first described in the sixteenth century in the codices of Mexican traditional medicine. VB is present in alcohol extracts and is widely used in the north of Mexico as a sunscreen. VB absorbs UV-A and UV-B radiation and has high antioxidant and anti-inflammatory capacities. VB and its constituent caffeic acid (CA) were screened to determine their genotoxic activity using the Drosophila wing spot test. Third instar larvae (72±4 h) of the standard (ST) and high bioactivation (HB) crosses, with regulated and high levels of cytochrome P450s (Cyp450s), respectively, were exposed to VB or CA (0, 27, 57, 81, 135, and 173 mM). VB was not genotoxic at any of the concentrations tested in both crosses. The amount of VB residue as determined by HPLC in the adult flies that were fed with VB indicated a low metabolism of this compound, which explains the absence of genotoxicity. CA decreased the spontaneous frequencies of small and total spots and showed putative toxicity in the ST cross.

Genotoxicity studies of organically grown broccoli (Brassica oleracea var. italica) and its interactions with urethane, methyl methanesulfonate and 4-nitroquinoline-1-oxide genotoxicity in the wing spot test of Drosophila melanogaster.

Broccoli (Brassica oleracea var. italica) has been defined as a cancer preventive food. Nevertheless, broccoli contains potentially genotoxic compounds as well. We performed the wing spot test of Drosophila melanogaster in treatments with organically grown broccoli (OGB) and co-treatments with the promutagen urethane (URE), the direct alkylating agent methyl methanesulfonate (MMS) and the carcinogen 4-nitroquinoline-1-oxide (4-NQO) in the standard (ST) and high bioactivation (HB) crosses with inducible and high levels of cytochrome P450s (CYPs), respectively. Larvae of both crosses were chronically fed with OGB or fresh market broccoli (FMB) as a non-organically grown control, added with solvents or mutagens solutions. In both crosses, the OGB added with Tween-ethanol yielded the expected reduction in the genotoxicity spontaneous rate. OGB co-treatments did not affect the URE effect, MMS showed synergy and 4-NQO damage was modulated in both crosses. In contrast, FMB controls produced damage increase; co-treatments modulated URE genotoxicity, diminished MMS damage, and did not change the 4-NQO damage. The high dietary consumption of both types of broccoli and its protective effects in D. melanogaster are discussed.

Genotoxicity of triasulfuron in the wing spot test of Drosophila melanogaster is modulated by winter wheat seedlings.

Triasulfuron (TS) is a widely used sulfonylurea herbicide which inhibits the acetolactate synthase in broad-leaf weeds and in some wheat crop grasses (Triticum aestivum L.). Residues can be found in soil and superficial water with high toxicity to primary producers. In cereals, TS metabolism depends on cytochromes P450 (CYPs), the age of seedlings and the interaction with compounds. The genotoxicity of TS was demonstrated in the wing spot test of Drosophila melanogaster, an in vivo assay based on the loss of heterozygosity of the mwh and flr markers in the wing imaginal disk cells of larvae fed with chemical agents. Chronic treatments with analytical grade TS, commercial formulation TS (Amber) 75WG) (0.5mg/mL) and commercial formulation bentazon (Basagran) 480) (0.24mg/mL) were performed with three-day-old larvae of the standard (ST) and the high bioactivation (HB) crosses with regulated and high constitutive levels of CYPs, respectively. To demonstrate the effect of winter wheat metabolism on TS genotoxicity, T. aestivum L. seedlings were immersed for 4h in these herbicides, and aqueous extracts (AEs) of the roots were prepared to expose the larvae. TS and Amber 75WG produced similar genotoxic effects in both crosses. Wheat metabolism modulated the genotoxicity because the AEs yielded statistically significant lower spot frequencies in the HB cross than in the ST cross. Differences between the two crosses of the wing spot test in D. melanogaster must be related to CYPs levels. Basagran 480 was genotoxic only in the HB cross, and wheat metabolism did not modulate its genotoxicity.