Outward potassium current in neurons of aestivated land snail Achatina fulica.

Aestivation and hibernation represent distinct forms of animal quiescence, characterized by physiological changes, including ion composition. Intracellular ion flows play a pivotal role in eliciting alterations in membrane potential and facilitating cellular communication, while outward K+ currents aid in the restitution and upkeep of the resting membrane potential. This study explores the relationship between inward and outward currents during aestivation in Achatina fulica snails. Specimens were collected near MSUBIT University in Shenzhen and divided into two groups. The first group was kept on a lattice diet, while the second one consisted of aestivating individuals, that were deprived of food and water until a cork-like structure sealed their shells. Recording of current from isolated neurons were conducted using the single-electrode voltage clamp mode with an AxoPatch 200B amplifier. Electrophysiological recordings on pedal ganglia neurons revealed significant differences in the inactivation processes of the Ia and Ikdr components. Alterations in the Ikdr component may inhibit pacemaker activity in pedal ganglion neurons, potentially contributing to locomotion cessation in aestivated animals. The KS current remains unaffected during aestivation. Changes in slow K+ current components could disrupt the resting membrane potential, possibly leading to cell depolarization and influx of Ca2+ and Na+ ions, impacting cell homeostasis. Thus, maintaining the constancy of outward K+ current is essential for cell stability.

[2'-Deoxynucleoside-5'-triphosphate, modified via the carbohydrate and triphosphate residues, in the DNA synthesis reaction]. / 2'-Dezoksinukleozid-5'-trifosfaty, modifitsirovannye po uglevodnomu i trifosfatnomu ostatkam, v reaktsii sinteza DNK.

We have investigated the substrate properties of deoxyribonucleoside 5'-triphosphate analogues, modified in the carbohydrate and triphosphate moieties, in DNA synthesis catalyzed by different DNA polymerases and reverse transcriptases. It was shown that (3'-azido-2',3'-dideoxythymidine-5'-O-methylenephosphonate) diphosphate, (3'-azido-2',3'-dideoxythymidine 5'-phosphate) dibromomethylenediphosphonate, (3'-azido-2',3'-dideoxythymidine 5'-phosphate) phosphonoacetate terminate DNA synthesis catalyzed by reverse transcriptases. (2'-Deoxythymidine 5'-phosphate) phosphonoacetate displays substrate properties for DNA polymerase beta, different reverse transcriptases, terminal deoxynucleotidyl transferase, but not for DNA polymerase alpha, Klenow's fragment DNA polymerase I. The Km value for this substance in DNA synthesis reactions catalyzed by reverse transcriptases was two of orders magnitude higher than that for native 2'-deoxythymidine 5'-triphosphate.