Regulation of prostaglandin synthesis by protein kinase C in mouse peritoneal macrophages.

Resident mouse peritoneal macrophages synthesized and released prostaglandins (PGs) when challenged with 12-O-tetradecanoylphorbol 13-acetate (TPA) or 1,2-dioctanoyl-sn-glycerol (DiC8). Both stimuli were found to activate Ca2+/phospholipid-dependent protein kinase C (PKC). 1-(5-Isoquinolinesulphonyl)-2-methylpiperazine ('H-7') and D-sphingosine, known to inhibit PKC by different mechanisms, were able to decrease the PKC activity of macrophages in a dose-dependent manner. Addition of either PKC inhibitor decreased PG synthesis and also the release of arachidonic acid (AA) from phospholipids induced by TPA or DiC8. Simultaneously TPA or DiC8 also decreased incorporation of free AA into membrane phospholipids of macrophages. AA incorporation could be restored, however, by pretreatment with the PKC inhibitors. Our results demonstrate an involvement of PKC in the regulation of PG synthesis in mouse peritoneal macrophages and provide further evidence that reacylation of released fatty acids may be an important regulatory step.     

Circadian and seasonal rhythms of 5-HT receptor subtypes, membrane anisotropy and 5-HT release in hippocampus and cortex of the rat.

Specific serotonin binding (5-HT1, 5-HT1A, and 5-HT2 subtypes) and membrane anisotropy were measured at 2 h intervals over a 24 h period in the hippocampus and cortex of Wistar WU rats, housed under a 12 h light-dark cycle, with lights on at 07.00. All experiments were performed both in March and December. In the hippocampus significant circadian rhythms could be ascertained for 5-HT1 binding sites in March and December while for 5-HT1A (subtype of 5-HT1) binding sites the circadian rhythm was only significant in March. The membrane anisotropy also showed significant variations only in March. Circadian rhythms were also found in the cortex for 5-HT1 (December) and 5-HT2 (March and December) binding sites as well as for the membrane anisotropy (December). A correlation was found between membrane anisotropy and 5-HT1 and 5-HT2 binding sites in hippocampus and cortex, respectively. A circadian rhythmicity was also observed for serotonin release as measured by in vivo voltammetry in both brain areas. The results obtained on the diurnal variations of serotonin receptor subtypes and serotonin release and the probable inverse relationship of these two parameters may be relevant in understanding the coupling of pre- and postsynaptic activity.     

Regeneration of transgenic plants of Prunus armeniaca containing the coat protein gene of Plum Pox Virus

Summary A system was developed which allows the transfer of foreign genes into apricot cultivars. We report the transformation and regeneration of Prunus armeniaca plants with Agrobacterium tumefaciens strain LBA 4404 containing various binary plasmids, pBinGUSint, carrying the marker gene ß-glucuronidase (GUS) and pBinPPVm, carrying the coat protein gene of Plum Pox Virus (PPV). The marker gene GUS was used for optical evaluation of the efficiency of the transformation system. The coat protein gene of PPV was used to introduce coat protein mediated resistance against one of the most important pathogens of stone fruit trees in Europe and the whole Mediterranean area. This is the first report of the successful integration of a viral coat protein gene into a fruit tree species, opening a new perspective on the control of the disease.Abbreviations GUS ß-glucuronidase - PPV Plum Pox Virus - BA 6-benzylaminopurine - NPTII neomycin phosphotransferase II - CP coat protein - CaMV Cauliflower Mosaic Virus - P35S 35S promoter - MS Murashige and Skoog - PCR polymerase chain reaction - P/C/I phenol/chloroform/isoamylalcohol - RNase ribonuclease - dNTP deoxyribonucleosidetriphosphate - DMSO dimethyl sulfoxide     

Induction of prostanoid synthesis in human platelets by the late complement components C5b-9 and channel forming antibiotic nystatin: inhibition of the reacylation of liberated arachidonic acid

Treatment of human platelets by the purified late complement components C5b-9 results in a dose- and time-dependent release of prostaglandin E (PGE) and thromboxane B2 (TXB2). To study the mechanism underlying the complement-induced prostanoid synthesis, we examined whether C5b-9 affected the enzyme acyl-coA:lysolecithin acyltransferase (E.C.2.3.1.2.3) that catalyzes the reinsertion of liberated arachidonic acid, the precursor molecule of the prostanoids. With C5b-9 doses sufficient to induce prostanoid synthesis, the activity of lysolecithin acyltransferase, measured as conversion of lysophosphatidyl choline to phosphatidyl choline, was inhibited. For comparison, another channel-forming substance, nystatin, was studied. Nystatin had an effect similar to C5b-9: PGE and TXB2 release was stimulated, whereas acyltransferase activity was inhibited. These finding support the concept that inhibition of lysolecithin acyltransferase might be the prerequisite for prostanoid production.     

Simple sequences

Simple sequences (or microsatellites) are stretches of monotonous repetitions of short (1–5 bp) nucleotide motifs that are distributed across the whole genome in eukaryotes. They are probably generated by slippage during replication and their primary mutation rate seems to be controlled predominantly by the efficiency of the mismatch repair system. Although most mutations in simple sequence loci appear to be neutral, some mutations in particular stretches have been implicated as having a role in human genetic diseases.     

Asynchronous mitotic domains during blastoderm formation inMusca domestica L. (Diptera)

Summary We describe the mitotic cleavage patterns during blastoderm stage of the house flyMusca domestica L. Nuclear divisions up to mitotic stage 11 are apparently synchronous. Beginning with stage 12, nuclear divisions in the posterior third of the embryo lag behind, resulting first in a parasynchronous and finally in an asynchronous cleavage pattern. Thus a stage exists where all nuclei in the anterior region have completed 14 nuclear division cycles, while those in the posterior region have completed only 13 cycles. The border region between these nuclei is well defined and lies at 35% EL (egg length), the expression border of a gap gene. This border region is about 4–5 nuclei wide and shows a specialized mitotic behaviour.     

Identification of a Rapidly Labelled 350K Histidine-Rich Protein in Neonatal Mouse Epidermis

Abstract. The major histidine-rich protein (HRP) found in the stratum corneum of neonatal mouse epidermis (band 2 protein, molecular weight 27,000) is a relatively late product of epidermal differentiation and incorporates labelled amino acids in vivo only after a 6–9 h lag period. A number of putative precursor HRPs in the 70–300 K molecular weight range were initially identified using short pulse labelling times and our previously described methods for isolation of epidermis and extraction of proteins. However, when steps were taken to minimise proteolysis during preparation, a single species of approximately 350 K molecular weight was the most strongly labelled protein following a 1 h in vivo pulse of [³H]-histidine. This protein was stable in sodium dodecyl sulphate dithiothreitol at 100°C and in 4 M urea, suggesting a single covalently linked polypeptide. The kinetics of labelling and the localisation of the 350 K HRP in the lower granular layers suggest that it is a precursor of the stratum corneum HRP. The processing of the 350 K HRP to the stratum corneum species appears to involve a complex series of specific cleavage steps which give rise to a number of HRPs of intermediate molecular weight.     

Veränderungen des Gibberellingehaltes von Salatsamen nach Belichtung

Zusammenfassung Samen der obligat lichtkeimenden Salatsorte Tenax wurden auf ihren Gibberellingehalt untersucht. Sie enthalten bei Quellung im Dunkeln nur wenig gibberellinähnliche Substanzen. Nach Belichtung mit hellrotem Licht nimmt der Gibberellingehalt innerhalb 1 Std sehr stark zu. Es wird gefolgert, daß Lichtkeimer einen zu niedrigen Gibberellingehalt besitzen, um im Dunkeln keimen zu können, und daß unter dem Einfluß des Lichtes die zur Keimungsauslösung notwendige Gibberellinmenge entsteht.

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Changes in gibberellin-like substances of lettuce seeds after light exposure

Summary The contents of gibberellin-like substances in lettuce seeds were determined. In darkness the seeds contain only small amounts of gibberellin-like substances, but upon illumination with near red light there is a sharp increase in the gibberellin content within one hour. It is concluded that lettuce seeds in darkness do not contain the amounts of gibberellin necessary for germination and that under the influence of light these amounts are provided.