Summary — One hundred and eighty-three larvae of Melipona compressipes were fed with mixed food collected from 391 cells containing eggs of various ages. Nine recently provisioned cells had an average of 238 mg of food; the maximum quantity of food a cell can receive if completely full averages 308 mg. Larvae were reared in wax cups receiving 350, 300 and 240 mg of food (control). Death rate was high due to the handling of larvae. In the 350 mg group, 17 workers and 4 queens were obtained and 34 died before the pupal stage. In the 300 mg group, 39 workers and 8 queens pupated and 38 died. In all there were 56 workers and 12 queens. If quality of food were decisive in queen determination, no segregation of queens and workers should occur, as the food was a homogenized mixture. Weight of last larval stage and genetics were the preponderant caste determinants. Below 184.7 mg of last larval weight no queens are produced; above it, a 3 workers to one queen segregation was observed; we therefore conclude that genetics is the ultimate determining factor of caste in Melipona.
Leishamaniasis is a neglected disease caused by over 20 Leishmania species, occurring in more than a hundred countries. Miltefosine (hexadecylphosphocholine) is the single oral drug used in treatment for leshmaniases, including cases of infections resistant to pentavalent antimony. Our group has recently demonstrated the ability of miltefosine to cause genomic lesions by DNA oxidation. Acknowledging that antioxidant compounds can potentially modulate Reactive Oxygen Species (ROS), our study verified whether ascorbic acid reduces the genotoxic and mutagenic effects caused by miltefosine, and whether it interferes with drug efficacy. For this purpose, uninfected Swiss mice received simultaneous (single dose treatment) miltefosine and ascorbic acid (gavage and intraperitoneally), besides pre and post treatments (ascorbic acid 24 h before and after drug administration); furthermore, Balb/c mice infected with Leishmania infantum received miltefosine plus ascorbic acid (repeated doses treatment). We conducted comet assays, micronucleus tests, dosages of superoxide dismutase enzyme and parasitic burden by the limiting dilution assay. We observed that ascorbic acid administered intraperitoneally displayed a protective effect over damage caused by miltefosine. However, this effect was not not observed when the same doses were administered via gavage, possibly due to low serum levels of this antioxidant. Ascorbic acid's protective effect reinforces that miltefosine damages DNA by oxidizing its nitrogenous bases, which is reduced by ascorbic acid due to its ability of protecting genetic material from the action of ROS. Therefore, our results show that this drug is efficient in reducing parasitic burden of L. infantum.
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