A high-performance system for automation of the polymerase chain reaction

A high-performance PCR system has been developed which reduces the time required for PCR, increases the throughput, reduces reagent consumption and ensures reproducibility of amplification. Integration of sophisticated temperature control with optimally designed vessels has resulted in an amplification system which produces unique benefits. These include rapid amplification, the elimination of the need for oil, even for small volumes, and a microplate format which provides liquid handling automation benefits.     

Differential effects of strychnine on crustacean slow, fast, and inhibitory neuromuscular systems

The effect of strychnine was studied on the slow, fast, and inhibitory systems in the abdominal extensor muscles of the crayfish. Strychnine nitrate (0.1 mg/ml and up) caused rapid block of the fast responses of the deep abdominal extensor muscles. The nerve and muscle remained directly excitable, and the blocked preparation contracted with added glutamate. It is concluded that strychnine acts mainly presynaptically or to neutralize the transmitter substance. No marked effect was observed on the purely slow superficial extensor muscles or on inhibitory systems. Essentially the same results were obtained in other slow and fast systems of Pachygrapsus and Panulirus. The possibility of a common transmitter substance for the slow and fast neuromuscular systems is discussed.     

Mg++-sensitivity of neuromuscular transmission in two crustaceans: Correlation with blood Mg++ levels

Neuromuscular transmission was measured in muscles of spider crabs (Hyasareneus) and lobsters (Homarus americanus). Solutions containing 40 and 10 mM/1 Mg⁺⁺, which were approximately the same as those measured in the blood of Hyas and Homarus, respectively, were used to soak the preparations prior to testing. In Homarus, neuromuscular transmission was severely depressed by 40 mM Mg⁺⁺. In spider crabs, neuromuscular transmission was not severely depressed. Although the amount of transmitter released by nerve impulses was reduced, total membrane depolarization during trains of impulses was not reduced because a compensating increase in muscle fiber membrane resistance occurred in Hyas preparations exposed to 40 mM Mg⁺⁺. Hyas, but not Homarus, is physiologically adapted to function at relatively high blood Mg⁺⁺ concentrations.