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At least 19 recordsLinked to original sources
PubMed1978

Adenine nucleotides in foetal rat liver cells. Compartmentation and variation with age.

The digitonin method for the separation of cytosolic and mitochondrial fractions was applied to liver cells isolated from foetal rats. The cytosolic [ATP]/[ADP] ratio approximately doubles during the last 4 days of gestation, whereas the mitochondrial ratio remains constant. In the presence of oligomycin and added glucose, the cytosolic [ATP]/[ADP] ratio does not increase with age, but is still considerably higher than the mitochondrial ratio. Without added glucose, and when the glycogen content of foetal liver is still very low (more than 3 days before birth), the cytosolic [ATP]/[ADP] ratio in the presence of oligomycin becomes very low and equal to the mitochondrial ratio. It is concluded that the increasein the cytosolic [ATP]/[ADP] ratio during the last 4 days of gestation is solely due to enhanced mitochondrial activity in this period. Atractyloside and bongkrekic acid do not influence the O2 consumption, nor the [ATP]/[ADP] ratios in either compartment of foetal liver cells. Respiration of isolated foetal mitochondria, however, is strongly inhibited by both compounds. The implications of these findings are discussed.

Adenosine Diphosphate↗
PubMed1991

IFN-gamma- and IL-5-producing cells compartmentalize to different lymphoid organs in Trichinella spiralis-infected mice.

The differential induction of cytokines associated with Th1 and Th2 subsets has recently been described during Trichinella spiralis infection. Increased levels of resistance appear to correlate with elevated levels of the Th1-associated cytokines, IFN-gamma and IL-2. In the present report, a filter immunoplaque assay is used to quantify the actual numbers of cells that secrete IFN-gamma and IL-5. It is demonstrated that, in T. spiralis-infected B10.Q mice, Th1- and Th2-associated responses are compartmentalized to different lymphoid organs. Thus, Ag-induced IFN-gamma-producing cells predominate in the spleen, whereas IL-5-producing cells prevail in the mesenteric lymph nodes (MLN). A corresponding compartmentalization of Ag-specific IgA and IgG1 antibody-secreting cells to the MLN is also noted. The virtual absence of Th1-associated responses in the MLN appears to be an Ag-associated phenomenon. MLN from either naive or T. spiralis-infected mice do have the capacity to secrete IFN-gamma if stimulated with Con A. The striking compartmentalization of Ag-driven cytokine responses seen in this parasite system may facilitate study of the mechanisms that regulate the induction of Th1 and Th2 subsets.

Animals↗
PubMed1992

Metallothionein biodegradation in rat hepatoma cells: a compartmental analysis aided 35S-radiotracer study.

Disappearance rates, synthesis and biodegradation of rat HTC cell metallothioneins (MT) were examined by measurements of [35S]MT, and expressed by their rate constants in experiments carried out under steady-state conditions, with physiological doses of zinc and copper. Overall rates of disappearance of [35S]MT did not obey first-order kinetics, apparently due to the presence of chemically and/or spatially distinguishable MT (sub)pools. Application of compartmental analysis yielded results indicating that: (a) MT in copper-treated cells is stabler than MT in zinc-treated cells, (b) apparent half-lives for MT disappearance are 22-25 h under the conditions as described, (c) addition of 0.1 mM chloroquine reduces the overall rate of MT disappearance by 25%, (d) total MT should be regarded as significantly consisting of at least two MT sub-forms, i.e., Apo-MT and M-MT and/or cytosolic MT and lysosomal MT, each being depleted and replenished at different rates, (e) mean half-lives for total MT, based on actual degradation rates, were 3-7 h, (f) addition of 0.1 mM chloroquine resulted in both increased synthesis and increased degradation of non-lysosomal MT, the latter probably due to free amino acid depletion in the cells, and (g) MT behaviour may be best examined by combination of tracer experiments (35S-labeled amino acids), simultaneous determination of MT levels in all (sub)MT pools, and application of compartmental analysis.

Animals↗
PubMed1992

Primary biphasic lymphoplasmacytic lymphoma of the lung. A mucosa-associated lymphoid tissue lymphoma with compartmentalization of plasma cells in the lung and lymph nodes.

A primary mucosa-associated lymphoid tissue lymphoma of the lung in a 27-year-old man was found. The tumor was composed mainly of centrocyte-like cells and plasma cells. These two components were demarcated sharply from each other, resulting in a zoning or biphasic pattern. This characteristic pattern also was present in the involved regional lymph nodes. Monoclonality of tumor cells was shown immunohistochemically and by in situ hybridization techniques. This article also highlights the use of in situ hybridization in detecting light chain mRNA in paraffin sections.

Adult↗
PubMed1992

Calcium-activated neutral proteinase (calpain) activity in C6 cell line: compartmentation of mu and m calpain.

Calcium-activated neutral proteinase (calpain) activity was determined, including in cytosol and membrane fractions, in rat glioma C6 cell line. The mu and m forms of calpain were separated by DEAE and phenylsepharose column chromatography and with removal of the endogenous inhibitor calpastatin. C6 cells contained more mcalpain than the mu isoform. More than 70% of mcalpain activity was membrane-associated and 20% was cytosolic. Isolated plasma membrane also contained 69% of the mcalpain activity. In contrast, approximately 80% of mucalpain activity was cytosolic and 16% was membranous. Half-maximal activity for mu and mcalpain was obtained at 1 microM and 0.2 mM CaCl2, respectively. Trypsin dissociation of cells reduced activity. Triton X-100 stimulated mcalpain activity of the whole homogenate and the membrane pellet but not of the cytosol. Activity of the myelin marker enzyme adenosine 2'3'-cyclic nucleotide 3'-phosphohydrolase (CNPase), was also found in C6 cells. The identification of calpain and CNPase in C6 cells is in keeping with an interpretation that C6 differentiation resembles, at least in part, that of the myelin-forming oligodendroglial cells.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1991

Compartmentalized mast cell degranulations in the ovarian hilum, fat pad, bursa and blood vessel regions of the cyclic hamster: relationships to ovarian histamine and blood flow.

Ovaries from hamsters on each day of the oestrous cycle at 09.00 h were observed for the number of mast cells, the pattern of mast cell degranulation, histamine concentration and blood flow. On day 4 (pro-oestrus), ovaries were also observed at 9.00, 15.00 and 21.00 h. Mast cell degranulation was evaluated by 3 criteria: (1) no degranulation = less than 5 granules dispersed from the cell; (2) moderate degranulation = 5 or more granules dispersed but less than 15, and (3) extensive degranulation = 15 or more granules released. Blood flow was determined using radio-active microspheres in anaesthetized animals. Mast cells were observed in fat pad (beyond 2 mm of the bursal mesothelium), bursa (within 2 mm of the bursal mesothelium), hilum and near ovarian blood vessels (these 4 regions are collectively called the ovarian complex). The distribution of ovarian mast cells was not uniform. Most mast cells were near ovarian blood vessels (42.2%) and in the fat pad (37.2%). A moderate number of cells were in the bursal wall (20%) and only a few cells were observed in the hilum (0.64%). Mast cell number remained unchanged on days 1-4 of the cycle in each ovarian compartment. However, summation of the number of mast cells in the entire ovarian complex revealed a significant decline in number at 15.00 h on pro-oestrus. Alterations in mast cell degranulation were primarily restricted to 2 periods of the cycle (pro-oestrus and di-oestrus). An increase in moderate but not extensive degranulation was observed in only the fat pad and bursa on day 2 when compared with day 1 values. In most ovarian compartments on pro-oestrus, degranulation was higher than on any other day of the cycle. At 15.00 h on pro-oestrus, extensive degranulation in bursa, fat pad and blood vessel regions (but not hilum) coincided with an increase in ovarian histamine and decline in number of mast cells; ovarian blood flow also increased at the time but remained unchanged the remainder of the cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a COOH-terminal microbody targeting signal.

Trypanosomes compartmentalize most of their glycolytic enzymes in a peroxisome-like microbody, the glycosome. The specificity of glycosomal targeting was examined by expression of chloramphenicol acetyltransferase fusion proteins in trypanosomes and monkey cells. Compartmentalization was assessed by cell fractionation, differential detergent permeabilization, and immunofluorescence. The targeting signal of trypanosome phosphoglycerate kinase resides in the COOH-terminal hexapeptide, NRWSSL; a basic amino acid is not required. The minimal targeting signal is, as for mammalian cells, a COOH-terminal tripeptide related to -SKL. However, the acceptable degeneracy of the signal for glycosomal targeting in trypanosomes is considerably greater than that for peroxisomal targeting in mammals, with particularly relaxed requirements in the penultimate position.

Amino Acid Sequence↗
PubMed1977

Effect of glucagon on metabolite compartmentation in isolated rat liver cells during gluconeogenesis from lactate.

1. The subcellular distribution of adenine nucleotides, acetyl-CoA, CoA, glutamate, 2-oxoglutarate, malate, oxaloacetate, pyruvate, phosphoenolpyruvate, 3-phosphoglycerate, glucose 6-phosphate, aspartate and citrate was studied in isolated hepatocytes in the absence and presence of glucagon by using a modified digitonin procedure for cell fractionation. 2. In the absence of glucagon, the cytosol contains about two-thirds of cellular ATP, some 40-50% of ADP, acetyl-CoA, citrate and phosphoenolpyruvate, more than 75% of total 2-oxoglutarate, glutamate, malate, oxaloacetate, pyruvate, 3-phosphoglycerate and aspartate, and all of glucose 6-phosphate. 3. In the presence of glucagon the cytosolic space shows an increase in the content of malate, phosphoenolpyruvate and 3-phosphoglycerate by more than 60%, and those of aspartate and glucose 6-phosphate rise by about 25%. Other metabolites remain unchanged. After glucagon treatment, cytosolic pyruvate is decreased by 37%, whereas glutamate and 2-oxoglutarate decrease by 70%. The [NAD(+)]/[NADH] ratios calculated from the cytosolic concentrations of the reactants of lactate dehydrogenase and malate dehydrogenase were the same. Glucagon shifts this ratio and also that of the [NADP(+)]/[NADPH] couple towards a more reduced state. 4. In the mitochondrial space glucagon causes an increase in the acetyl-CoA and ATP contents by 25%, and an increase in [phosphoenolpyruvate] by 50%. Other metabolites are not changed by glucagon. Oxaloacetate in the matrix is only slightly decreased after glucagon, yet glutamate and 2-oxoglutarate fall to about 25% of the respective control values. The [NAD(+)]/[NADH] ratios as calculated from the [3-hydroxybutyrate]/[acetoacetate] ratio and from the matrix [malate]/[oxaloacetate] couple are lowered by glucagon, yet in the latter case the values are about tenfold higher than in the former. 5. Glucagon and oleate stimulate gluconeogenesis from lactate to nearly the same extent. Oleate, however, does not produce the changes in cellular 2-oxoglutarate and glutamate as observed with glucagon. 6. The changes of the subcellular metabolite distribution after glucagon are compatible with the proposal that the stimulation of gluconeogenesis results from as yet unknown action(s) of the hormone at the mitochondrial level in concert with its established effects on proteolysis and lipolysis.

Animals↗
PubMed2026

Mapping subcellular microenvironments using oligonucleotide-directed proximity labeling.

Understanding how cells compartmentalize their biomolecules into discrete structures remains one of the fundamental goals of cell biology. The proliferation of proximity labeling (PL) technologies has been invaluable toward this goal, enabling biochemical "dissection" of compartments that would be intractable to classical biochemical methods. While robust PL approaches have long been established for targeting proteins of interest, targeting nucleic acids-RNAs and genomic loci-has remained significantly more challenging. Here, we review recent advancements in the field that overcome this longstanding roadblock by using programmable DNA oligonucleotides to direct PL enzyme localization. These tools are already revealing new insights into the molecular architecture of cellular compartments that lie at the heart of gene expression. They also provide a foundation for developing a new generation of PL tools that exploit the modularity and programmability of oligonucleotide-based devices to enable precise spatiotemporal control at previously inaccessible targets and in challenging specimen types.

Oligonucleotides↗
PubMed1991

Relationship between the calcium-mobilizing action of inositol 1,4,5-trisphosphate in permeable AR4-2J cells and the estimated levels of inositol 1,4,5-trisphosphate in intact AR4-2J cells.

Various experimental strategies were employed in an effort to explain the previously reported [Horstman, Takemura & Putney (1988) J. Biol. Chem. 263, 15297-15303] paradoxically high levels of inositol 1,4,5-trisphosphate [(1,4,5)IP3] in resting and substance-P-stimulated AR4-2J cells. The concentration-effect curves for substance-P-induced [3H](1,4,5)IP3 formation in [3H]inositol-labelled cells and substance-P-induced increase in intracellular [Ca2+] were essentially superimposable, suggesting that formation of (1,4,5)IP3 is limiting for cellular Ca2+ mobilization. In electrically permeabilized AR4-2J cells, (1,4,5)IP3 and other inositol polyphosphates stimulated Ca2+ release with potencies similar to those reported for other cell types, including the parent pancreatic acinar cell. Compartmentalization of basal (1,4,5)IP3 was suggested by the fact that this material was stable in the presence of antimycin A, although this toxin completely blocked agonist stimulation of phospholipase C. However, subcellular fractionation as well as permeabilization of the cells with Staphylococcus aureus alpha-toxin failed to provide evidence for binding or sequestration of [3H](1,4,5)IP3 in AR4-2J cells. The density of (1,4,5)IP3 receptors in AR4-2J cells was not sufficiently large to impose non-linearity in the relationship between (1,4,5)IP3 concentration and (1,4,5)IP3-induced Ca2+ release. Thus the apparent high concentrations of (1,4,5)IP3 in resting and stimulated AR4-2J cells are not indicative of atypically low sensitivity or high concentration of (1,4,5)IP3 receptors, nor is there evidence for compartmentalization of (1,4,5)IP3 outside of the cytoplasm in these cells. It is possible that soluble factors in the cytoplasm of AR4-2J cells regulate the free concentration of (1,4,5)IP3 or the sensitivity of receptors to (1,4,5)IP3.

Animals↗
PubMed1978

Mechanism of densensitization in DNCB-contact sensitive guinea pigs.

Contact sensitivity to dinitrochlorobenzene (DNCB) in guinea pigs could be rapidly suppressed by intravenous injection of dinitrobenzene sulfonic acid sodium salt (DNBSO3). This suppression is transient and antigen-specific. Macrophages from desensitized animals are not inactivated as shown by their ability to react, both in vivo and in vitro to lymphokines produced in a separate system. Therefore, effector lymphocytes are considered the target for the desensitizing antigen. Using an adoptive transfer system it was demonstrated that effector lymphocytes are inactivated by a direct effect of the hapten. Since this inactivation can be reversed by trypsin treatment, a receptor blockade of effector lymphocytes is proposed as the mechanism of desensitization of DNCB-contact sensitive guinea pigs. This does not exclude the possibility that additional mechanisms such as suppressor cells, compartmentalization or endogenous proliferation of lymph node lymphocytes may play an additional role.

Animals↗
PubMed1975

On the physiological functions of teichoic acids.

The choline-containing teichoic acids of pneumococci can be modified by biosynthetic replacement of the choline residues with certain structural analogues, such as ethanolamine (EA) or the N-monomethyl-(MEA) and N-dimethyl-(DEA) amino derivatives of ethanolamine. Cells containing such analogues in their teichoic acids develop pleiomorphic alterations in several physiological properties, which include resistance to detergent-induced lysis and inhibition of cell separation (chain formation). We report here the results of physiological studies on the mechanism of these two phenomena. Our results are summarized in the following: (a) Pneumococci grown on various amino alcohols produce cell walls of identical amino sugar and amino acid composition. (b) Both choline- and EA-containing teichoic acids seem to follow the same conservative pattern of segregation during growth and cell division.(c)Lysis sensitivity of pneumococci requires the juxtaposition oflysissensitive (choline-containing) cell walls and endogenous autolysin at the cell wall growth zone. (d) Upon readdition of choline to ethanolamine-containing cells, lysis sensitivity and catalytically active (C-type) autolysin reappear in the bacteria with the same kinetics. (e) The chains of EA-grown pneumococci contain fully compartmentalized cells and normal cross walls.

Amino Alcohols↗
PubMed1992

Fine structural evaluation of altered Schmidt-Lanterman incisures in human sural nerve biopsies.

Fine structural alterations of Schmidt-Lanterman incisures (SLI) were investigated in a series of 242 unselected sural nerve biopsies that had been examined for diagnostic purposes. The series included cases with Friedreich's ataxia, HSAN I, HMSN I-III, HMSN VI, tomaculous neuropathy, metachromatic leukodystrophy, ceroidlipofuscinosis, dysproteinemic neuropathies, and myotonic dystrophy, in addition to several neuropathies less-specifically classified as either of a predominantly demyelinating, axonal, or neuronal type. The following classification of SLI alterations is proposed: (A) abnormal inclusions; (B) changes in shape and dimension; and (C) modes of disintegration. Abnormal inclusions comprised membranous whorls, uniform and pleomorphous lysosome-like bodies, and accumulation of granular substances at the site of the major dense line, or granular deposits at the site of the intraperiod line of the myelin sheath. Variations of incisural shape and dimension included folding, dilatation, and pocket formation (compartmentalization). Disintegration at incisures comprised a fine, vesicular and a gross, vacuolar type. Various combinations of these changes were observed. The most frequent change consisted of membranous whorls, detected in SLI of 89 biopsies. They were most prominent in chloroquine neuropathy where they occurred in SLI as well as in the adaxonal and abaxonal cytoplasm of Schwann cells. Compartmentalization of the myelin sheath at incisures associated with formation of myelin loops was a frequent feature in myotonic dystrophy. It is concluded, that changes of incisural ultrastructure are sensitive indicators of human neuropathies offering clues to the type of the underlying pathomechanism.

Adolescent↗
PubMed1992

Modulation of the mutagenic response in prokaryotes.

Short-term tests investigating genetic end-points in prokaryotes have been extensively used worldwide not only for risk assessment purposes but also for evaluating the modulation of the mutagenic response. In spite of some intrinsic limitations, such as the lack of cell compartmentalization or the need for an exogenous metabolic system working extracellularly, experimental systems in bacteria can provide useful preliminary indications and some information on the mechanisms involved. In the large majority of studies the putative modulator is mixed with a known mutagen and then assayed in target bacteria, with suitable controls. However, under natural conditions exposure of target cells to modulators may either precede, co-exist with, or follow exposure to mutagens. Therefore, a variety of methodological variations, involving pre-treatment, co-treatment, or post-treatment of bacteria with the putative modulator, have been designed. Application of these procedures showed that the effects of modulators can be completely upset, from inhibition to enhancement, or vice versa, by changing the experimental conditions. Use of methodological variations may provide more complete information on the spectrum of possible effects in bacteria as well as a better insight into modulation mechanisms. Several examples illustrating the flexibility of the Salmonella test in this field of research are available. On the other hand, the widespread use of these relatively simple techniques, yet requiring skillfulness and experience, may lead to some misuse or oversimplifications. A rather common inadequacy is to use excessive amounts of test mutagens, or to express the results in terms of revertants/survivors, rather than revertants/plate. In fact, in the Salmonella test the number of revertants is rather unrelated to the initial number of plated bacteria, provided a normal background lawn of bacterial growth is formed. Thus, a 50% killing of bacteria will not appreciably influence the number of revertants/plate, but expressed as revertants/survivors the effect will look twice as large.

Antimutagenic Agents↗
PubMed1977

Kinetics of hepatocellular proliferation as a function of the microvascular structure and functional state of the liver.

An analysis of hepatocellular proliferation in regenerating rat liver reveals a dependence of kinetic parameters on the microvascular structure of the liver. Influx kinetics of hepatocytes into DNA synthesis as well as cell cycle phases vary in different parts of the liver lobule between the afferent and efferent vascular poles. Heterogeneity of the proliferative response and size limitations on cell cycle compartments appear to be intimately related to the actual functional state of the individual liver cell. Modifications of liver cell functions result in variations of the proliferative activity. Phenobarbital-induced hypertrophy of hepatocytes reveals a permissive action on G1- S influx. Selective destruction of the subpopulations, by allyl formate, leads to a new functional determination of the residual liver and to a change in proliferative compartments. Maximum modulation of cell cycle compartments is obtained by hydroxyurea-induced synchronization of hepatocytes after partial liver resection. During hydroxyurea treatment, the regenerating liver shows a pronounced cellular hypertrophy. After release from hydroxyurea block, cells embark on DNA synthesis simultaneously. The DNA synthesizing compartment comprises almost the entire liver cell population. Heptotrophic factors might play a part in regulating or modifying hepatocellular function and proliferative response after cell loss.

Allyl Compounds↗
PubMed1992

Molecular movements in oocyte patterning and pole cell differentiation.

Central to the differentiation and patterning of the Drosophila oocyte is the asymmetric intracellular localization of numerous mRNA and protein molecules involved in developmental signalling. Recent advances have identified some of the molecules mediating oocyte differentiation, specification of the anterior pole of the embryo, and determination of the embryonic germ line. This work is considered in the context of the classical model of the germ plasm as a cytoplasmic determinant for germ cell formation.

Animals↗
PubMed1991

Cross-linking of surface IgM activates NF-kappa B in B lymphocyte.

In B lymphocytes, cross-linking of surface IgM activates changes in both the cell cycle and differentiation. In normal B cells and B cell tumors, many stimuli induce the activation of NF-kappa B and its translocation from the cytoplasm to the nucleus. In this study we sought to determine if cross-linking of surface IgM led to the activation of NF-kappa B. Our results show that activation of B cells by cross-linking anti-IgM antibodies activated NF-kappa B in the murine B lymphoid cell lines 70Z/3 and M12, and in the dense fraction of splenic cells. The activation of NF-kappa B required optimal doses of anti-IgM antibodies and took 5 to 10 min to reach maximal levels. Cross-linking of IgM has also been shown to activate protein kinases including protein kinase C (PKC). To test whether PKC activation was required for NF-kappa B translocation, we treated 70Z/3 cells for 18 h with phorbol 12-myristate 13-acetate, a procedure which depletes these cells of functional PKC. This treatment did not abrogate the nuclear translocation of NF-kappa B following anti-IgM cross-linking. These results indicate that the nuclear translocation of NF-kappa B is rapidly induced by surface IgM cross-linking and that this activation appears to use a pathway which does not require PKC.

Animals↗