Effect of phospholipids on purified lipoamidase

Phospholipids were added to purified lipoamidase from porcine brain microsomal membranes, and changes in lipoamidase activity were examined. Approximately twofold activation of lipoamidase activity occurred upon the addition of phosphatidylethanolamine. On the other hand, phosphatidylserine, cardiolipin, and phosphatidic acid reduced the enzyme activity by approximately 80%. This pattern of the activation of lipoamidase by phosphatidylethanolamine and its inhibition by phosphatidylserine is similar to the pattern for adenylate cyclase, and contrasts with the pattern for ATPase.     

Effect of clofibrate on the phospholipid biosynthesis in rat liver.

The effect of clofibrate on rat liver phospholipid biosynthesis was studied using 32P as a precursor. Phospholipid classes, levels and specific radioactivity were evaluated. Significant increases in levels of phosphatidylethanolamine and phosphatidylcholine were found and could account for the observed increase in total phospholipids. Specific activity of phosphatidylserine increased and that of phosphatidylethanolamine decreased. This fact suggests that clofibrate seems to alter the systems engaged in the transformation occurring within the different classes of phospholipids but not the de novo biosynthesis.     

Effect of clofibrate on the phospholipid biosynthesis in rat liver

Summary The effect of clofibrate on rat liver phospholipid biosynthesis was studied using³²P as a precursor. Phospholipid classes, levels and specific radioactivity were evaluated. Significant increases in levels of phosphatidylethanolamine and phosphatidylcholine were found and could account for the observed increase in total phospholipids. Specific activity of phosphatidylserine increased and that of phosphatidylethanolamine decreased. This fact suggests that clofibrate seems to alter the systems engaged in the transformation occurring within the different classes of phospholipids but not the de novo biosynthesis.     

Genetic functional inactivation of neuronal nitric oxide synthase affects stress-related Fos expression in specific brain regions

To identify neuronal substrates involved in NO/stress interactions we used Fos expression as a marker and examined the pattern of neuronal activation in response to swim stress in nNOS knock-out (nNOS–/–) and wild-type (WT) mice. Forced swimming enhanced Fos expression in WT and nNOS–/– mice in several brain regions, including cortical, limbic and hypothalamic regions. Differences in the Fos response between the two groups were observed in a limited set (6 out of 42) of these brain areas only: nNOS–/– mice displayed increased stressor-induced Fos expression in the medial amygdala, periventricular hypothalamic nucleus, supraoptic nucleus, CA1 field of the hippocampus, dentate gyrus and infralimbic cortex. No differences were observed in regions including the septum, central amygdala, periaqueductal grey and locus coeruleus. During forced swimming, nNOS–/– mice displayed reduced immobility duration, while no differences in general locomotor activity were observed between the groups in the home cage and during the open field test. The findings indicate that deletion of nNOS alters stress-coping ability during forced swimming and leads to an altered pattern of neuronal activation in response to this stressor in specific parts of the limbic system, hypothalamus and the medial prefrontal cortex.Received 29 March 2004; accepted 21 April 2004     

Biosynthesis of phosphatidylethanolamine from CDP-ethanolamine by the Golgi complex of rat liver in vitro

Summary A Golgi-rich fraction from rat liver has been shown to synthesize phosphatidylethanolamine from CDP-ethanolamine in vitro. The implications of the existence of such a pathway for the membrane flow hypothesis are discussed.Acknowledgments. This study was supported by the Medical Research Council of Canada.     

Long-term 24-hour rest-activity pattern of sheep in stalls and in the field

Summary Motor activity of sheep was continuously recorded for 2–3 weeks with an ambulatory monitoring device. Recordings were obtained from free-ranging animals in the field and from animals maintained under various controlled conditions in stalls. The sheep were diurnal under all conditions. While the daily amount of activity and the frequency of rest episodes showed only small differences between the conditions, the rest-activity pattern showed prominent differences. The pattern differed particularly between the field and the stalls. In the field, activity started to increase one hour after dawn, reaching a first maximum towards noon; a second, higher peak in the evening was followed by a rapid decline after dusk. In the stalls the onset and offset of activity was more abrupt; activity peaks coincided with feeding and human activity; the onset of rest with lights off. Activity was lowest and rest most prominent in those stalls where the animals were most isolated from human influence.     

Characterization and localization of the rat,mouse and human testicular phosphatidylethanolamine binding protein

A cytosolic 23kDa protein was initially puified from bovine brain and shown to bind phosphatidylethanolamine. Later, it was also characterized in rat and human brain, and it is now known to be widespread, having been found in numerous tisues in several species. Here, we report the high level of mRNA and phosphatidyl ethanolamine binding protein expression in rat testis and to a lesser extent mouse testis. In human testis, although it was not detectable by Northern blot analysis, the mRNA was shown be present when PCR amplificatin was performed. Immunohistochemical experiments revealed that the testicular phosphatidylethanolamine binding protein (tPBP) is principally expressed in the elongated spermatids of both rat and mouse testis. This finding, and the association of tPBP with cellular membranes, suggest its possible implication in membrane remodelling during spermatid maturation.     

Long-term 24-hour rest-activity pattern of sheep in stalls and in the field

Motor activity of sheep was continuously recorded for 2-3 weeks with an ambulatory monitoring device. Recordings were obtained from free-ranging animals in the field and from animals maintained under various controlled conditions in stalls. The sheep were diurnal under all conditions. While the daily amount of activity and the frequency of rest episodes showed only small differences between the conditions, the rest-activity pattern showed prominent differences. The pattern differed particularly between the field and the stalls. In the field, activity started to increase one hour after dawn, reaching a first maximum towards noon; a second, higher peak in the evening was followed by a rapid decline after dusk. In the stalls the onset and offset of activity was more abrupt; activity peaks coincided with feeding and human activity; the onset of rest with lights off. Activity was lowest and rest most prominent in those stalls where the animals were most isolated from human influence.     

Effect of taurine administration on liver lipids in guinea pig

The oral administration of 0.4% taurine in drinking water for 14 consecutive days showed the following hepatic effects in male guinea pig. The percentage of tauro-conjugated biliary bile acids was increased from 17.2-54.2%; the ratio liver weight/body weight was increased, and fatty change was induced. Liver triglyceride concentration was accordingly increased; diglyceride and phosphatidylcholine concentrations were reduced by the treatment, while phosphatidylethanolamine level was not affected. These changes suggest an adverse effect of taurine administration on phosphatidylcholine hepatic synthesis.     

Rhythms of enzymatic activity in maternal and umbilical cord blood

The 24-h activity patterns of variouns enzymes were determined in human serum, red blood cells and white blood cells of maternal and umbilical cord blood. Blood was drawn from the brachial vein of mothers and from the umbilical cord within ten minutes after delivery. Corresponding blood specimens were obtained from 83 spontaneous labors, occurring at different hours over a period of 60 days. For each variable (variable=activity of a specific enzyme in one of the blood components) the results were grouped according to delivery hour, forming a 24-h pattern which was analyzed to elucidate time dependency. Five out of six corresponding maternal and fetal variables were similar with regard to pattern and peak time. The activity rhythms of glyceraldehyde-3-phosphate dehydrogenase and glucose phosphate isomerase in red blood cells of mothers and fetuses possessed a significant bimodal pattern. The activity rhythms of the latter enzyme in white blood cells and sera exhibited a significant 24-h period. Hexosaminidase activity exhibited a distinct 24-h rhythm in maternal white blood cells, but no significant rhythm could be detected in the fetal white blood cells. The activity of hexosaminidase showed, identical 24-h patterns in maternal and cord serum when analyzed by best fit cosine, and no significant time-dependency when analyzed by ANOVA.     

Rhythms of enzymatic activity in maternal and umbilical cord blood.

The 24-h activity patterns of various enzymes were determined in human serum, red blood cells and white blood cells of maternal and umbilical cord blood. Blood was drawn from the brachial vein of mothers and from the umbilical cord within ten minutes after delivery. Corresponding blood specimens were obtained from 83 spontaneous labors, occurring at different hours over a period of 60 days. For each variable (variable = activity of a specific enzyme in one of the blood components) the results were grouped according to delivery hour, forming a 24-h pattern which was analyzed to elucidate time dependency. Five out of six corresponding maternal and fetal variables were similar with regard to pattern and peak time. The activity rhythms of glyceraldehyde-3-phosphate dehydrogenase and glucose phosphate isomerase in red blood cells of mothers and fetuses possessed a significant bimodal pattern. The activity rhythms of the latter enzyme in white blood cells and sera exhibited a significant 24-h period. Hexosaminidase activity exhibited a distinct 24-h rhythm in maternal white blood cells, but no significant rhythm could be detected in the fetal white blood cells. The activity of hexosaminidase showed, identical 24-h patterns in maternal and cord serum when analyzed by best fit cosine, and no significant time-dependency when analyzed by ANOVA.     

Effect of taurine administration on liver lipids in guinea pig

Summary The oral administration of 0.4% taurine in drinking water for 14 consecutive days showed the following hepatic effects in male guinea pig. The percentage of tauro-conjugated biliary bile acids was increased from 17.2–54.2%; the ratio liver weight/body weight was increased, and fatty change was induced. Liver triglyceride concentration was accordingly increased; diglyceride and phosphatidylcholine concentrations were reduced by the treatment, while phosphatidylethanolamine level was not affected. These changes suggest an adverse effect of taurine administration on phosphatidylcholine hepatic synthesis.     

Methylation of hippocampal phosphatidylethanolamine and proteins during long-lasting potentiation

Summary Whereas the monomethylation of hippocampal phosphatidylethanolamine is decreased following the induction of long-lasting potentiation of the CA₁ population spike, carboxymethylation of proteins is unaffected.This work was supported by The University of British Columbia.     

Strain differences in the pattern and intensity of wheel running activity in laboratory rats

Summary Wheel running activity rhythms of three inbred rat strains, ACI/Ztm, BH/Ztm, and LEW/Ztm, were compared in order to evaluate the effect of genetic differences on circadian rhythm parameters. Significant strain differences were found in the general pattern of the activity rhythms and their characteristic periodicities as well as in the amount and duration of wheel running activity and the timing of activity onsets and offsets. The results suggest that genetic differences exist in the coupling of the multiple circadian oscillators that generate the overall pattern of wheel running activity.     

Functional impact of PTP1B-mediated Src regulation on oxidative phosphorylation in rat brain mitochondria

Given the presence of Src and PTP1B within rat brain mitochondria, we have investigated whether PTP1B regulates Src activity in mitochondria as in the cytosol. Results showed that Src was stimulated by in vitro addition of ATP to mitochondria, and this stimulation was reversed by a membrane-permeable allosteric inhibitor of PTP1B and by a potent selective Src inhibitor. They also indicated a direct action of PTP1B on phosphorylated tyrosine 527 residue of Src, thus implicating a role for PTP1B in the modulation of Src activity in mitochondria. Putative Src and PTP1B substrates were identified by liquid chromatography tandem mass spectrometry and two-dimensional blue native/SDS-PAGE. Both inhibitors inhibited ADP-stimulated respirations concurrently with Src activation and complex IV activation by ATP, while having no effect or increasing the activity of the other complexes. Our analysis emphasizes the regulatory function of Src and its modulation by PTP1B on oxidative phosphorylation in mitochondria.     

Involvement of xanthine oxidase and hypoxia-inducible factor 1 in Toll-like receptor 7/8-mediated activation of caspase 1 and interleukin-1β

Inflammatory reactions to ssRNA viruses are induced by the endosomal Toll-like receptors (TLRs) 7 and 8. TLR7/8-mediated inflammatory reaction results in activation of the Nalp3 inflammasome via an unknown mechanism. Here we report for the first time that TLR7/8 mediate activation of xanthine oxidase (XOD) in an HIF-1α-dependent manner. XOD produces uric acid and reactive oxygen species, which could activate Nalp3 and therefore induce activation of caspase 1, known to convert inactive pro-IL-1β into active IL-1β. Specific inhibition of the XOD activity attenuates TLR7/8-mediated activation of caspase 1 and IL-1β release. These results were obtained using human THP-1 myeloid macrophages. The findings were verified by conducting in vivo experiments on mice.     

Strain differences in the pattern and intensity of wheel running activity in laboratory rats

Wheel running activity rhythms of three inbred rat strains, ACI/Ztm, BH/Ztm, and LEW/Ztm, were compared in order to evaluate the effect of genetic differences on circadian rhythm parameters. Significant strain differences were found in the general pattern of the activity rhythms and their characteristic periodicities as well as in the amount and duration of wheel running activity and the timing of activity onsets and offsets. The results suggest that genetic differences exist in the coupling of the multiple circadian oscillators that generate the overall pattern of wheel running activity.     

The effect of endotoxin on membrane fatty acid composition in BCG-sensitized mice

The effects of endotoxin on mouse liver phospholipid fatty acid composition have been investigated. Administration of endotoxin from Salmonella abortus equi led to a decrease in the polyunsaturated fatty acid content of livers from mice sensitized with Bacille Calmette Guérin (BCG). The content of arachidonic acid fell significantly in both the phosphatidylcholine and phosphatidylinositol fractions whereas in the phosphatidylethanolamine fraction the linoleic acid content was significantly reduced. The polyunsaturated fatty acids were replaced by increased amounts of oleic acid and palmitic acid, leading to a reduction in the polyunsaturated to saturated fatty acid ratio.     

Memory

Recent research in a variety of systems indicates that memory formation can involve the activation of a wide range of molecular cascades. In assessing this recent work it is clear that no single cascade is uniquely important for all forms of memory, nor is a single form of memory uniquely dependent on a single cascade. Rather, it appears that molecular networks are differentially engaged in the induction of various forms of memory. Despite this highly interactive array of possible cascades, specific 'molecular nodes' have emerged as critical regulatory points in memory formation. Functionally, these nodes can operate in two sequential steps, beginning with a convergence of inputs which coordinately influence the activation state of the node, in which the nature of stimulation determines the dynamics of nodal activity, followed by a divergence of substrate selection, in which the node serves as a gateway that activates specific downstream effectors. Finally, specific nodes can be differentially engaged (i.e. have different 'weights') depending upon the nature and pattern of the activating stimulus. The marine mollusk Aplysia has proven useful for a molecular analysis of memory formation. We will use this system to highlight some of the molecular strategies employed by the nervous system in the formation of memory for sensitization, and we will focus on extracellular signal-related kinase as a candidate node integral to these processes.     

Methylation of hippocampal phosphatidylethanolamine and proteins during long-lasting potentiation

Whereas the monomethylation of hippocampal phosphatidylethanolamine is decreased following the induction of long-lasting potentiation of the CA1 population spike, carboxymethylation of proteins is unaffected.