Physiological polymorphism of grass frog populations. IV. Effect of stress on the phenotypic expression of population polymorphism judged by the level of heat resistance of muscle tissue

A study was made on the polymorphism of the population of Rana temporaria by the heat resistance of muscle tissue. Stress resulted in the elimination of group differences in the heat resistance of muscles. Thus, the phenotypical response of individuals to stress is masking the genotypical heterogeneity of the population judged from the heat resistance of muscle tissue.     

Physiological polymorphism in a population of the common frog. I. The polymorphism of a population of the common frog for the trait of muscle tissue heat resistance]

A study was made of heat resistance (36+/-0.2 degrees C) of m. interphalangealis of the third finger of a hind extremity in animals of one population of Rana temporaria L. living on the boundary between Leningrad region and Pskov region. Within this population, the existence of three groups of individuals differing in heat resistance levels of their m. interphalangealis is postulated. This conclusion is based on the distribution curve of heat resistance values and on the application of the probit-method. The distribution of the frequency of occurrence of individuals in these three groups follows Hardy-Weinberg's equation.     

Physiological polymorphism of a population of the common frog. II. The polymorphism of the type of muscle tissue heat resistance in stress]

A study was made of the dynamics in the heat resistance of m. interphalangealis of individual grass frogs under stress. The response of muscle tissue to injury can be differentiated into three types according to the initial heat resistance level: increase, decrease and phase change of the resistance. The pattern of response of muscle tissue of individual frogs to stress is one of manifestationss of physiological polymorphism of the population.     

Investigation of the muscle tissue biostructure by means of the pressing-out method. III. The water in the rabbit striated muscle tissue

In the rabbit striated muscle tissue the free and biostructured water content have been investigated using the pressing-out method. The following percent values have been found: 20% bound water to cell colloids and different cell particles, 61% biostructure-integrated water and 19% free water.     

The effect of isogenization on the phenotypic manifestation of quantitative traits in Drosophila melanogaster

A comparative analysis of the phenotypic values of the proximal and distal fragments of the radial wing vein was carried out in heterogeneous lines of Drosophila melanogaster and in isogenic lines derived from them with the help of a balancer line. The mean values of the traits in the isogenic lines were shown to significantly differ from the corresponding values in the "parental" heterogeneous lines. Apparently, the change in the trait values was caused by a double recombination exchange between the inverted and the "normal" chromosomes, which suggests partial crossing over suppression in the balancer lines.     

The transducer and encoder of frog muscle spindles are essentially nonlinear. Physiological conclusions from a white-noise analysis

1. Nonlinear second order white-noise analysis has been applied to the isolated frog muscle spindle. Power (²) of the Gaussian white noise (GWN) and the average prestretch level L were varied and the response of both the isolated receptor potential (transducer) and the action potential (encoder) level were analysed. 2. The standard white-noise method is briefly presented. Particular emphasis, however, is put on the limitations in the range of validity of the method and, consequently, on the use and interpretation of the kernels as a Wiener model. Conclusions in the present paper are within this frame and are mainly of qualitative nature. 3. The analysis reveals that the nonlinear contributions of the model are essential for approximating physiological results, thus ruling out purely linear modelling for this receptor organ. 4. The dependence of the transducer kernels on are compatible with the behaviour of a rectifier. Rectification is represented by the lack of hyperpolarization within the isolated receptor potential and is enhanced by the substantial memory in the linear and nonlinear kernels as demonstrated by their extent in time. This is equivalent to low power in high frequencies of the response. Obviously, the hyperpolarizing potentials following each spike counteract the long transducer memory. 5. At the encoder level the memory of the system is strongly reduced. This is achieved by using predominantly high frequency components of the receptor potential for triggering the process of impulse generation, and by the precise coupling and high frequency content of the impulses. This coupling precision is possible because of the sensitivity of the spike-generating mechanism to steep rising transients of the receptor potential and also owing to the reduction in transducer memory by the hyperpolarizing afferpotentials. 6. The preference given to the high frequency components is also read from the structure of the second order transducer kernel and from both the linear and the second order encoder kernels, which allows the most effective input waveform for triggering action potentials to be determined. 6. When the operating point is changed to higher prestretch values, kernel heights increase strongly implying higher response strength of the muscle spindle. The kernel structure is changed as well in the direction of reducing the effective memory already at the level of the receptor potentials, probably a means to prevent too high depolarization values.     

The physostigmine depolarization potentiating effect of salicylate in frog skeletal muscle.

1) The frog's sartorius muscle was depolarized depending on the degree of concentration 2--4 times more intensely by physostigmine salicylate than by physostigmine sulphate. 2) In normal Ringer's solution, 1 mM physostigmine salicylate decreased the sensitivity of the membrane to potassium depolarization by about 90%. Under similar experimental conditions, physostigmine sulphate and Na salicylate, respectively, decrease the sensitivity of the membrane to potassium depolarization by about 30%. 3) The difference manifested in the depolarizing effect of salicylate and other physostigmine salts (chloride, sulphate, phosphate, formiate, acetate, monochloracetate, benzoate and para-oxy-benzoate) is expressed already at 1 mM concentration (about 10-fold), if the muscle had been equilibrated in chloride-free glucuronate or sulphate milieu. 4) The depolarization develops slowly. It takes 30--60 minutes for the new steady state to develop even in the superficial sartorius fibres. If depolarization has reached its maximum on an average 100 mV, the membrane potential remains unchanged for hours. 5) Depolarization ensues at an unchanged degree in the presence of Na-free (choline) Ringer as well as in the presence of 2X10(-8) g/ml tetrodotoxin; therefore, it is not a Na-dependent process. 6) Under the influence of 1 mM physostigmine salicylate the membrane's resistance to the inward potassium current increased about twofold, while the increase was only 15% to the outward potassium current. It is assumed that the salicylate anion is characteristically capable of potentiating the decreasing effect of physostigmine on potassium permeability, though the role of the metabolic effect of salicylate cannot be excluded.