Evaluation of boar and bull sperm capacitation and the acrosome reaction using flow cytometry.

Flow cytometry can be used to evaluate many sperm attributes and Dr. Duane Garner was influential in developing assays to understand sperm physiology and function. We review some of Dr. Garner's work and describe experiments that evaluate sperm capacitation using Dr. Garner's philosophy. In exploratory experiments, boar sperm were cryopreserved in lactose egg yolk (LEY) or Beltsville Freezing Extender 5 (BF5) and incubated in one capacitating medium. In another experiment, frozen-thawed bull sperm were incubated in TALP-Ca or CFDM1 capacitating media. In both experiments, sperm viability and capacitation were evaluated using multiple probes. Boar sperm frozen in LEY had greater survival rates (38%) than sperm frozen in BF5 (22%; P < 0.05) but did not capacitate as effectively as sperm in BF5 (P < 0.05). In Experiment 2, bull sperm survived to a greater extent when incubated in TALP-Ca than in CFDM1 (P < 0.05) and had greater capacitation for most parameters (P < 0.05). Of particular interest, 77% of sperm incubated in TALP-Ca had activated second messenger systems involved in capacitation, compared with < 5% of sperm incubated in CFDM1. The results indicate different freezing and capacitating media induce different responses to sperm capacitation and functions. If only sperm viability and acrosomal integrity were evaluated, these results would be interpreted very differently. Dr. Garner's philosophy of evaluating multiple sperm parameters was an impetus to determine unique treatment differences which help in understanding sperm capacitation, and design further experiments to determine how media content causes sperm physiology differences.

[Susceptibility of the horn fly (Haematobia irritans) to insecticides in the Tabuleiros Costeiros region in states of Alagoas, Bahia and Sergipe, Brazil]. / Suscetibilidade da mosca-dos-chifres (Haematobia irritans) a inseticidas nos Tabuleiros Costeiros de Alagoas, Bahia e Sergipe, Brasil.

Susceptibility of horn fly populations to insecticides was evaluated at the Tabuleiros Costeiros region in the states of Alagoas, Bahia, and Sergipe from April 2001 to December 2002. A total of 37 bioassays were conducted in 23 ranches from 12 municipalities. Fly susceptibility was determined by the impregnated filter paper method using the active ingredients diazinon, permethrin, and cypermethrin. A high susceptibility to diazinon was found, with LC50 varying from 0.23 to 1.41 microg/cm2 and resistance ratios (RR) = 1.3. On the other hand, resistance to pyrethroids was detected in all studied populations. Cypermethrin LC50 ranged from 19.94 to 1,928 microg/cm2 and RR from 21.2 to 4,484.4. Although resistance levels to permethrin were much lower (RR<6), all LC50 were significantly higher than the LC50 obtained from the susceptible population. All ranches relied on pyrethroids for horn fly control, most cypermethrin (88.46%) and deltamethrin (80.77%) products. Spraying, by using manual backpack sprayers, was routinely used in all ranches. History of insecticide use as well as inadequate control practices help to explain the spread resistance of horn fly populations to pyrethroids detected in the region.