Constant representation of signal spatial location in the cricket cercal system]

Directional sensitivity of the abdominal giant fibers of the cricket to auditory stimulation has been investigated with special interest to the effect of the cerci position on the directional sensitivity of the giant neurons of the terminal abdominal ganglion. It has been shown that at least for some giant neurons the preferred directions of stimulation are practically independent of cerci position. (Fig. 2, 3). By other words these neurons have constant preferred directions in relation to the insect body, but not to the cerci. This property of giant neurons can be accounted for their changeable connections with many receptors having different directional selectivity. If innervation of the giant neuron is artificially restricted to one group of receptors with identical directional selectivity the described constancy of preferred directions in relation to the body disappears (Fig. 4).     

Two types of lateral inhibition in the frog retina

Two independent types of lateral inhibition were distinguished in experiments on the frog eye in which the effects of pharmacological agents on the electroretinogram were studied: proximal or picrotoxin-sensitive, and distal or strychnine-sensitive. Distal lateral inhibition (at distances up to 1.5 mm) is the familiar type already well investigated and based on a spike mechanism of transmission of the inhibitory signal. The proximal (up to 400 µ) picrotoxin-sensitive inhibition has a different mechanism of transmission, not dependent on spikes. The localization of the two types of lateral inhibition in the synaptic layers of the frog retina is discussed.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 13, No. 5, pp. 549–555, September–October, 1981.     

Chromosome changes and human malignant tumors

The data from home and foreign literature on chromosome changes in human tumours of different genesis and localization are analyzed. The role and significance of changes in the chromosome structure in malignant cells are discussed.     

Golgi in copper homeostasis: a view from the membrane trafficking field

Copper is essential for a variety of important biological processes as a cofactor and regulator of many enzymes. Incorporation of copper into the secreted and plasma membrane-targeted cuproenzymes takes place in Golgi, a compartment central for normal copper homeostasis. The Golgi complex harbors copper-transporting ATPases, ATP7A and ATP7B that transfer copper from the cytosol into Golgi lumen for incorporation into copper-dependent enzymes. The Golgi complex also sends these ATPases to appropriate post-Golgi destinations to ensure correct Cu fluxes in the body and to avoid potentially toxic copper accumulation. Mutations in ATP7A or ATP7B or in the proteins that regulate their trafficking affect their exit from Golgi or subsequent retrieval to this organelle. This, in turn, disrupts the homeostatic Cu balance, resulting in copper deficiency (Menkes disease) or copper overload (Wilson disease). Research over the last decade has yielded significant insights into the enzymatic properties and cell biology of the copper ATPases. However, the mechanisms through which the Golgi regulates trafficking of ATP7A/7B and, therefore, maintains Cu homeostasis remain unclear. This review summarizes current data on the role of the Golgi in Cu metabolism and outlines questions and challenges that should be addressed to understand ATP7A and ATP7B trafficking mechanisms in health and disease.     

Endophytic Bacilli Producing Type II Restriction Endonucleases

Two of thirteen bacillar strains isolated from the inner tissues of cotton plants were found to produce type II restriction endonucleases. The investigation of the site specificity of these enzymes showed that they are AsuI and Eco31I isoschizomers.