Fast trap jaws and giant neurons in the ant odontomachus

Ants of the ponerine genus Odontomachus use a trap jaw mechanism when hunting fast prey. When particular trigger hairs, located on the inner edge of the mandibles, are touched by prey, the jaws close extremely rapidly and trap the target. This trap jaw response lasts only 0.33 to 1 millisecond. Electrophysiological recordings demonstrated that the trigger hairs function as mechanoreceptors. Associated with each trigger hair are large sensory cells, the sensory axons of which measure 15 to 20 micrometers in diameter. These are among the largest sensory neurons, and their size implies that these axons conduct information very rapidly.     

Polioencephalomalacia in cattle consuming water with elevated sodium sulfate levels: A herd investigation

Polioencephalomalacia (PEM), hereafter used to refer to the specific lesion of cerebrocortical necrosis, developed in 11 of 110 mature cattle on pasture in central Saskatchewan. The primary water source contained a markedly elevated level of sodium sulfate (7200 ppm). The significant clinical findings of the herd investigation included depression, ataxia, cortical blindness, dysphagia, and death. Diagnosis of PEM was confirmed by histopathological evidence of cerebrocortical and subcortical necrosis with microvascular fibrinoid necrosis predominantly in the thalamic region of three affected cattle. The histopathology of sulfate-associated PEM observed in this herd appears to be unique and its features are presented and discussed. Mean levels for serum transketolase, copper, red blood cell transketolase activity, and thiamine (vitamin B₁) in all exposed young (n = 100) and mature (n = 99) animals did not reveal evidence of deficiencies. Although the blood thiamine status of the seven surviving, affected animals was not evaluated before treatment with exogenous thiamine, 199 members of the herd had blood thiamine levels within the reference range at the time of the outbreak. The outbreak resolved after cattle were moved to a water source containing acceptable levels of sodium sulfate.