Toxicities of 4,5-Dihydroisoxazoles Against Root-Knot Nematodes and in Silico Studies of Their Modes of Action.

The present work sought to contribute to the development of new nematicides. Benzaldehydes were initially converted to nitrile oxides that underwent 1,3-dipolar cycloaddition reactions with methyl acrylate to generate 4,5-dihydroisoxazoles. In in vitro tests, methyl 3-phenyl-4,5-dihydroisoxazole-5-carboxylate (1) and methyl 3-(4-chlorophenyl)-4,5-dihydroisoxazole-5-carboxylate (4) increased the mortality of Meloidogyne exigua and Meloidogyne incognita second-stage juveniles (J2). Compounds 1 and 4 presented necessary concentrations of 398 and 501 µg mL-1, respectively, to kill 50% of M. incognita J2 (LC50 values), while the value for carbofuran (positive control) was 168 µg mL-1. In in vivo tests, compounds 1 and 4 reduced the number of M. incognita galls in tomato roots by 70 and 40%, respectively, and the number of eggs by 89 and 44%. Using an in silico approach, we showed that compounds 1 and 4 were toxic to the nematodes by binding to the allosteric binding sites of the agonist-binding domains of the nematode nicotinic acetylcholine receptors. These results opened up possibilities for further investigations aimed at developing novel commercial nematicides.

Impact of phenolic compounds on Meloidogyne incognita in vitro and in tomato plants.

Exposing second-stage juveniles (J2) of Meloidogyne incognita in vitro to a phenolic compound sometimes fails to cause J2 mortality, but in tests in vivo the same compound may reduce the infectivity and population of the nematode. This work aimed to study the effect of phenolic compounds on M. incognita through in vitro and in vivo assays. In the in vitro assay 49 phenolic compounds were screened for their toxicity to M. incognita J2. As a result, D-(-)-4-hydroxyphenylglycine, t-butylhydroquinone, L-3-(3,4-dihydroxyphenyl)alanine, sesamol, 2,4-dihydroxyacetophenone, and p-anisaldehyde increased the J2 mortality. These compounds presented, respectively, the following lethal concentrations to 50% of J2 (LC50): 365, 352, 251, 218, 210, and 85 µg/mL, while Carbofuran (positive control) had 150 µg/mL. However, none of these compounds were efficient in controlling the nematode in inoculated tomato plants, even when 2.77-fold of their LC50 were used. Although inactive in the in vitro test at 500 µg/mL, hydroquinone (3.5 mg per plant) reduced M. incognita population and galls by up to 99% to levels similar to the nematicide Carbofuran (1.2 mg per plant). Additionally, hydroquinone increased the root weight when compared to the negative and positive controls, water/NaOH and Carbofuran, respectively. In this study, we showed that some phenolic compounds, hydroquinone in particular, revealed a potential new option for the control of M. incognita.

Modification of the Alere GIARDIA Ag TEST immunochromatography KIT methodology for its use in frozen fecal sediment of dogs and cats.

Giardia duodenalis is a worldwide intestinal parasite and is one of the most frequent protozoa species infecting dogs and cats. This study aimed to modify the methodology of Alere GIARDIA Ag TEST KIT for its use in frozen fecal sediments with different storage times in a freezer (-20°C), thus expanding the range of use of this methodology. One hundred fecal sediments from dogs (n=50) and cats (n=50) previously examined by optical microscopy for Giardia cysts were selected for this study. The agreement between the modified immunochromatography and microscopy results was calculated by Kappa coefficient. To evaluate the performance of the modified immunochromatography assay on samples with different storage time, the fecal sediments were divided into three groups according to the time of storage in a freezer: (a) ≤ 1 year (n=37); (b) > 1 year and ≤ 3 years (n=39); (c) > 10 years (max. 13 years) (n=24). The results obtained by the modified immunochromatography assay demonstrates a higher sensitivity of this technique when compared with microscopy, regardless of the frozen storage time. These results allow for the use of this methodology in a greater scope of analysis, especially in frozen fecal sediment triage in sample collections, enabling epidemiological and comparative analysis along different decades.

Modification of the Alere GIARDIA Ag TEST immunochromatography KIT methodology for its use in frozen fecal sediment of dogs and cats

ABSTRACT Giardia duodenalis is a worldwide intestinal parasite and is one of the most frequent protozoa species infecting dogs and cats. This study aimed to modify the methodology of Alere GIARDIA Ag TEST KIT for its use in frozen fecal sediments with different storage times in a freezer (-20°C), thus expanding the range of use of this methodology. One hundred fecal sediments from dogs (n=50) and cats (n=50) previously examined by optical microscopy for Giardia cysts were selected for this study. The agreement between the modified immunochromatography and microscopy results was calculated by Kappa coefficient. To evaluate the performance of the modified immunochromatography assay on samples with different storage time, the fecal sediments were divided into three groups according to the time of storage in a freezer: (a) ≤ 1 year (n=37); (b) > 1 year and ≤ 3 years (n=39); (c) > 10 years (max. 13 years) (n=24). The results obtained by the modified immunochromatography assay demonstrates a higher sensitivity of this technique when compared with microscopy, regardless of the frozen storage time. These results allow for the use of this methodology in a greater scope of analysis, especially in frozen fecal sediment triage in sample collections, enabling epidemiological and comparative analysis along different decades.

Desempenho de novilhas leiteiras em pastagem de capim-Xaraés (Brachiaria brizantha cv. Xaraés) suplementadas com dois tipos de misturas minerais / Performance of dairy heifers raised on Xaraés palissadgrass (Brachiaria brizantha cv. Xaraés) pasture supplemented with two types of mineral mixture

The effects of selective (e.g. mineral supplement formulated on the basis of nutritional and clinical examination of the herd) or commercial mineral supplementation of crossbred dairy heifers (Holstein-Mantiqueira), on daily weight gain (DWG), body condition score (BCS), age at first mating (AFM) and the intake of mineral mixture (IMM) managed on Xaraés palissadgrass pasture (Brachiaria brizantha cv. Xaraés) were evaluated from February 2006 to March 2008. Structural characteristics, forage allowance and nutritional value of Xaraés palissadgrass were also evaluated. The structural variables of pasture, allowances and nutritive value of forage, besides the DWG were only affected (p<0.05) by season, with highest results for spring and summer. Throughout the experimental period (730 days), no sign of mineral deficiency was detected in heifers that ingested the selective supplement. The DWG and AFM were not influenced by the mineral mixture offered (0.52 and 0.33 kg/day during the spring/summer and in fall/winter for DWG, respectively, and 813 days of AFM). The IMM was higher for commercial mineral mixture than for selective (61.6 and 51.0g/day respectively). The BCS was slightly higher for selective (3.17) than for the commercial (3.02) mineral mixture. Thus, the selective mineral supplement was a strategy to prevent mineral deficiency in this herd and resulted in similar performance at lower costs (e.g. due to less IMM) of crossbred heifers when compared with the commercial mineral supplementation.

Foram avaliados os efeitos da suplementação mineral seletiva (i.e. aquela feita com base no exame clínico-nutricional do rebanho) ou comercial sobre o desempenho de novilhas leiteiras Holandês-Mantiqueira, com base em seus ganhos de peso diários (GMD), escores da condição corporal (ECC), idades à primeira cobertura (IPC) e consumos de mistura mineral (CMM), criadas em pastagem de capim-Xaraés (Brachiaria brizantha cv. Xaraés), no período de fevereiro de 2006 a março de 2008. Foram também avaliadas as características estruturais do pasto, oferta e valor nutritivo da forragem. Durante todo período experimental (730 dias), nenhum sinal de deficiência mineral foi detectado nas novilhas que ingeriram o suplemento seletivo. As variáveis estruturais do pasto, as ofertas e o valor nutritivo da forragem, além do GMD, somente foram influenciadas (p<0,05) pela estação do ano, com maiores e melhores resultados obtidos para a primavera e verão. O GMD e a IPC não foram influenciados pela mistura mineral ofertada (0,52 e 0,33 kg/dia durante a primavera/verão e outono/inverno para GMD, respectivamente, e 813 dias de IPC). O CMM foi maior para mistura mineral comercial que para seletiva (61,6 e 51,0g/UA/dia, respectivamente). O ECC foi superior para mistura mineral seletiva (3,17) que para comercial (3,02). Esta suplementação mineral seletiva foi uma estratégia que permitiu evitar o aparecimento de estados carenciais no rebanho e obter desempenho similar e com menor custo quando comparada com a suplementação mineral comercial.