Long distance communication between muscarinic receptors and Ca2+ release channels revealed by carbachol uncaging in cell-attached patch pipette

We have investigated the characteristics of cytosolic Ca2+ signals induced by muscarinic receptor activation of pancreatic acinar cells that reside within intact pancreatic tissue. We show that these cells exhibit global Ca2+ waves and local apical Ca2+ spikes. This is the first evidence for local Ca2+ signaling in undissociated pancreatic tissue. The mechanism of formation of localized Ca2+ signals was examined using a novel approach involving photolysis of caged carbachol inside a patch pipette attached to the basal surface of an acinar unit. This local activation of basal muscarinic receptors elicited local cytosolic Ca2+ spikes in the apical pole more than 15 microm away from the site of stimulation. In some experiments, local basal receptor activation elicited a Ca2+ wave that started in the apical pole and then spread toward the base. Currently, there are two competing hypotheses for preferential apical Ca2+ signaling. One invokes the need for structural proximity of the cholinergic receptors and the Ca2+ release channels in the apical pole, whereas the other postulates long distance communication between basal receptors and the channels. Our intrapipette uncaging experiments provide definitive evidence for long distance communication between basal muscarinic receptors and apical Ca2+ release channels.     

Laboratory Simulations of Cyanobacterial Mats of the Alkaline Geochemical Barrier

The goal of this work was to illustrate a possible interaction between the soda continent and the ocean. A laboratory simulation was undertaken of the development of alkaliphilic mat with calcium carbonate and calcium phosphate interlayers in the zone where ocean waters, containing calcium and manganese, come into contact with carbonate- and phosphate-rich alkaline waters. The macrostructure of the layered cyanobacterial mat turned out to be little dependent on the chemical conditions causing sediment formation. The chemical composition of freshly formed mineral interlayers of the mat was found to vary with the medium composition. The mineralogical composition of the sediment is determined by diagenesis conditions in its depth, which can cause mineral phase conversions.     

How to measure Ca2+ in cellular organelles?

The review will aim to briefly summarise information on calcium measurements in cellular organelles with emphases on studies conducted in live cells using optical probes. When appropriate we will try to compare the effectiveness of different indicators for intraorganellar calcium measurements. We will consider calcium measurements in endoplasmic reticulum, Golgi apparatus, endosomes/lysosomes, nucleoplasm, nuclear envelope, mitochondria and secretory granules.     

The distribution of the endoplasmic reticulum in living pancreatic acinar cells

Studies on pancreatic acinar cells provided the original evidence for the Ca(2+) releasing action of inositol 1,4,5-trisphosphate (IP(3)). Ironically, this system has presented problems for the general theory that IP(3) acts primarily on the endoplasmic reticulum (ER), because the IP(3)-elicited Ca(2+) release occurs in the apical pole, which is dominated by zymogen granules (ZGs) and apparently contains very little ER. Using confocal and two-photon microscopy and a number of different ER-specific fluorescent probes, we have now investigated in detail the distribution of the ER in living pancreatic acinar cells. It turns out that although the bulk of the ER, as expected, is clearly located in the baso-lateral part of the cell, there is significant invasion of ER into the granular pole and each ZG is in fact surrounded by strands of ER. This structural evidence from living cells, in conjunction with recent functional studies demonstrating the high Ca(2+) mobility in the ER lumen, provides the framework for a coherent and internally consistent theory for cytosolic Ca(2+) signal generation in the apical secretory pole, in which the primary Ca(2+) release occurs from ER extensions in the granular pole supplied with Ca(2+) from the main store at the base of the cell by the tunnel function of the ER.     

Proterozoic history and present state of cyanobacteria

The paper delves into the main regularities of the distribution of fossil microorganisms in Precambrian rocks, beginning from the Archean Eon about 3.5 billion years ago and ending in the Cambrian Period about 0.5 billion years ago. The paper analyzes facial peculiarities in the lateral differentiation of microfossils in Proterozoic basins and the main stages of temporal changes in fossil cyanobacterial communities, which are based on the irreversible succession of physicochemical conditions on the Earth and the evolution of eukaryotic microorganisms and their incorporation into prokaryotic ecosystems. To gain insight into Proterozoic fossil records, modern stratified cyanobacterial mats built up from layers of prokaryotes are considered. The analysis of phosphatization, carbonatization, and silification processes in modern algal-bacterial communities suggests that analogous processes took place in Proterozoic microbiotas. A comparison of modern and Precambrian living forms confirms the inference that cyanobacterial communities are very conservative and have changed insignificantly both morphologically and physiologically during the past two billion years.     

Cyano-bridged cluster-metal coordination compound: synthesis and crystal structure of [Cu(NH3)3][Cu(NH3)4][Cu(NH3)5][W4Te4(CN)12]·5H2O

Dark-brown single crystals of the title compound 1 were obtained in high yield by layering a CuCl₂ solution in 25% aqueous ammonia on a glycerol solution of K₆[W₄Te₄(CN)₁₂]·5H₂O. The complex 1 was characterized by single crystal X-ray diffraction analysis and IR spectroscopy. The X-ray structure of 1 reveals a polymeric chain cyano-bridged cluster-metal coordination compound. The [W₄Te₄(CN)₁₂]⁶⁻ cluster anions are linked one to another by Cu²⁺ cations through coordination by nitrogen atoms of the CN groups.     

Murine neuroblastoma cells absorb anti-cytoplasmic tetrodotoxin-sensitive protein antibodies

The properties were investigated of polyclonal antibodies obtained by immunizing with a fraction of cytoplasmic glycoproteins forming sodium channels in liposomes. It was shown that these antibodies can be absorbed by intact murine neuroblastoma cells. Graphs plotting intensity of absorption against numbers of absorbant cells follow a characteristic course dependent on life of the cells in culture and serum concentration in the culture medium.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 98–105, January–February, 1988.     

Isolation of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine from the bull heart

A novel efficient procedure based on silica gel column chromatography has been developed for isolating chromatographically pure diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine. For this purpose the lipid extract is treated with aqueous MgCl2, whereas aqueous ammonia is added to the eluent systems. To raise the yield of lipids, a fractional loading of columns with portions of lipid extracts is employed, each loading being followed by partial elution of neutral lipids with chloroform. Optimal phospholipid--silica gel ratio is 1:20 for such a procedure. The presence of cation exchange between the lipid extract and silica gel is confirmed and its influence on the efficacy of phospholipid separation is discussed.     

Evaluation of lumbar enlargement motor neuron excitability: Comparison between H-reflex and transcutaneous spinal cord stimulation

Multisegmental muscle responses (MMR) are reflexes in the leg muscles evoked by transcutaneous electrical spinal cord stimulation over the Th11–Th12 vertebrae. We have used MMR to evaluate the excitability of lumbosacral motor neurons in individuals having paraplegia of low limbs. Ten individuals were tested using H-reflexes and MMR bilaterally before (n ₀ = 20) and during 4-weeks course of rehabilitation (n=76). The H-reflex and MMR of m. gastrocnemius lateralis were obtained in: 15 and 13 cases out of 20, respectively. Both reflexes were recorded in 11 and were absent in 3 cases, matched up to 70% of recordings. In dynamic, the both methods were 100% reproducible and the responses’ amplitude varied in similar directions in 67% of records. The data confirm the validity and reproducibility of the MMR for evaluation of the motor neurons excitability in lumbosacral cord. The H-reflex magnitude shows moderate correlation with MMR in m. gastrocnemius lateralis (r = 0.59, p < 0.001), and weak correlation with MMR in mm. rectus femoris, biceps femoris, and tibialis anterior (r < 0.40, p < 0.001). These findings do not allow extrapolate the results from the H-reflex measurement on the state of lumbosacral cord on the whole. At the same time, measurements of the MMR allow estimate simultaneously the excitability of motor pools innervating several muscle groups. This gives the possibility to assess the functional state of the motor neurons in the lumbosacral cord for clinical and experimental studies, including the spinal cord damage.     

Sensorimotor regulation of movements: Novel strategies for the recovery of mobility

A series of observations have provided important insight into properties of the spinal as well as supraspinal circuitries that control posture and movement. We have demonstrated that spinal rats can regain full weight-bearing standing and stepping over a range of speeds and directions with the aid of electrically enabling motor control (eEmc), pharmacological modulation (fEmc), and training [1, 2]. Also, we have reported that voluntary control movements of individual joints and limbs can be regained after complete paralysis in humans [3, 4]. However, the ability to generate significant levels of voluntary weight-bearing stepping with or without epidural spinal cord stimulation remains limited. Herein we introduce a novel method of painless transcutaneous electrical enabling motor control (pcEmc) and sensory enabling motor control (sEmc) strategy to neuromodulate the physiological state of the spinal cord. We have found that a combination of a novel non-invasive transcutaneous spinal cord stimulation and sensory-motor stimulation of leg mechanoreceptors can modulate the spinal locomotor circuitry to state that enables voluntary rhythmic locomotor movements.