267 research outputs found
Bourgeois males of the peacock blenny, Salaria pavo, discriminate female mimics from females?
In a Portuguese population of Salaria pavo, two types of reproductively active
males occur: large bourgeois males that defend nests and have fully developed
secondary sex characters (SSC) and small sneaker males that mimic the females
morphology and behaviour to approach nests and parasitize fertilizations. These
two alternative reproductive tactics are sequential, as sneakers develop into
bourgeois males. We investigated whether bourgeois males were able to discriminate
between sneakers and females of different sizes. In a laboratory experiment
bourgeois males were sequentially presented with a female and a sneaker matched
for size. Complementary field observations were conducted on the interactions
between females and sneakers with bourgeois males. If bourgeois males discriminated
females from sneakers, we predicted that they should direct more aggressive
behaviours towards sneakers and more courtship acts towards females. In general,
bourgeois males courted and attacked small females and sneakers equally.
However, large sneakers were courted less and attacked more than large females.
Larger sneakers, beginning to develop SSC, were attacked more and courted less
by the bourgeois male than smaller sneakers, and larger females were attacked less
and courted more than smaller females. These results strongly suggest that only
small female-mimicking males were able to deceive bourgeois males. In S. pavo, if
the sneakers fertilization success correlates with their female-mimicking ability, a
fitness decrease with an increasing body size can be predicted
Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water
The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio
Novel coumarins active against Trypanosoma cruzi and toxicity assessment using the animal model Caenorhabditis elegans
From 2nd Latin American Congress of Clinical and Laboratorial Toxicology
Porto Alegre, Brazil. 3-6 June 2018Background: Chagas disease (CD) is a tropical parasitic disease. Although the number of people infected is very
high, the only drugs available to treat CD, nifurtimox (Nfx) and benznidazole, are highly toxic, particularly in the
chronic stage of the disease. Coumarins are a large class of compounds that display a wide range of interesting
biological properties, such as antiparasitic. Hence, the aim of this work is to find a good antitrypanosomal drug with less toxicity. The use of simple organism models has become increasingly attractive for planning and simplifying efficient drug discovery. Within these models, Caenorhabditis elegans has emerged as a convenient and versatile tool with significant advantages for the toxicological potential identification for new compounds. Methods: Trypanocidal activity: Forty-two 4-methylamino-coumarins were assayed against the epimastigote form of Trypanosoma cruzi (Tulahuen 2 strain) by inhibitory concentration 50% (IC50). Toxicity assays: Lethal dose 50% (LD50) and Body Area were determined by Caenorhabditis elegans N2 strain (wild type) after acute exposure. Structure-activity relationship: A classificatory model was built using 3D descriptors. Results: Two of these coumarins demonstrated near equipotency to Nifurtimox (IC50 = 5.0 ± 1 ΌM), with values of:
11 h (LaSOM 266), (IC50 = 6.4 ± 1 ΌM) and 11 g (LaSOM 231), (IC50 = 8.2 ± 2.3 ΌM). In C. elegans it was possible to observe that Nfx showed greater toxicity in both the LD50 assay and the evaluation of the development of worms. It is possible to observe that the efficacy between Nfx and the synthesized compounds (11 h and 11 g) are similar. On the other hand, the toxicity of Nfx is approximately three times higher than that of the compounds. Results from the QSAR-3D study indicate that the volume and hydrophobicity of the substituents have a significant impact on the trypanocidal activities for derivatives that cause more than 50% of inhibition. These results show that the C. elegans model is efficient for screening potentially toxic compounds. Conclusion: Two coumarins (11 h and 11 g) showed activity against T. cruzi epimastigote similar to Nifurtimox, however with lower toxicity in both LD50 and development of C. elegans assays. These two compounds may be a feasible starting point for the development of new trypanocidal drugs
IncidĂȘncia do mĂldio em cebola sob adubação mineral e orgĂąnica.
Analisou-se a relação entre adubação mineral e orgĂąnica sobre a incidĂȘncia de mĂldio (Peronospora destructor) em cebola (Allium cepa). O trabalho constituiu-se de dois experimentos localizados em Ituporanga, conduzidos entre agosto e dezembro de 1998. O experimento 1, com fontes orgĂąnicas, constou dos tratamentos: esterco de suĂnos, esterco de aves, composto, esterco de peru e hĂșmus, na dosagem de 75 kg/ha de N; esterco de suĂnos, na dosagem de 37,5 kg/ha de N; adubação mineral, 30-120-60 kg/ha de N-P2O5-K2O; 60-240-120 kg/ha de N-P2O5-K2O e testemunha sem adubação. O experimento 2 constou dos tratamentos: fontes minerais, 30-120-60 kg/ha de N-P2O5-K2O; 90-360-180 kg/ha de N-P2O5-K2O; 75 kg/ha de N; 225 kg/ha de N; 80 kg/ha de P2O5; 240 kg/ha de P2O5; 60 kg/ha de K2O; 180 kg/ha de K2O; esterco de suĂnos + fosfato natural, em trĂȘs combinaçÔes, 7,9+0,1, 15,7+0,2 e 47,2+0,6 t/ha, respectivamente;
testemunha sem adubação. NĂŁo houve diferença entre as fontes mineral e orgĂąnica sobre a incidĂȘncia de mĂldio. A relação entre nutrientes e doença foi variĂĄvel entre datas de amostragem e distinta para fontes minerais e orgĂąnicas
Aluminium Matrix Composites Reinforced with Co-continuous Interlaced Phases Aluminium-alumina Needles
Africanized honey bees (Apis mellifera L.) are more efficient at removing worker brood artificially infested with the parasitic mite Varroa jacobsoni Oudemans than are Italian bees or Italian/Africanized hybrids
Efeitos de nĂveis crescentes de fibra em detergente neutro na dieta sobre a digestĂŁo ruminal em bubalinos e bovinos
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