Über die Struktur der Pilzkörper des Insektenhirns

Zusammenfassung Die Organisation der -Loben der Pilzkörper im Gehirn von Acheta domesticus L. wird nach licht- und elektronenmikroskopischen Befunden beschrieben. Der säulenartige Faserkomplex des -Lobus besteht aus Fortsätzen von Pilzkörperzellfasern (intrinsischen Fasern, IF) und pilzkörperfremden Fasern (extrinsischen Fasern, EF), die in den Lobus eindringen. Die feinen IF durchziehen den Lobus hauptsächlich parallel zu seiner Längsachse, während die EF zumeist senkrecht zur Längsachse angeordnet sind. Der Lobus erscheint von seiner Peripherie bis zu seinem Zentrum durch IF-Zonen gegliedert. Die Verteilung der EF weist auf eine zusätzliche Ordnung von der Basis zur Spitze des Lobus hin. Zahlreiche polarisierte Synapsen verbinden IF mit EF. Die IF zeigen Vesikelanhäufungen und präsynaptische Apparate besonders in Erweiterungen, die auch in Golgi-Präparaten lichtmikroskopisch zu sehen sind. Es werden zwei EF-Typen unterschieden: 1. Postsynaptische EF (zahlreich) und 2. EF mit prä- und postsynaptischen Kontakten, die nur in einigen Regionen des -Lobus gefunden wurden. Präsynaptische IF konvergieren auf dendritische EF, die Verbindungen mit anderen Teilen des Hirns und des Nervensystems herstellen. Funktionelle Gesichtspunkte werden diskutiert.

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On the structure of the mushroom-bodies in the brain of insectsII. Synaptic connexions in the alpha-lobe of the cricket Acheta domesticus L.

Summary The organization of the -lobes of the corpora pedunculata in the brain of the cricket Acheta domesticus L. has been investigated in the light and electron microscopes. The cylindrical fibre complex is composed of branches of mushroom-body fibres (intrinsic fibres) and extrinsic fibres, which penetrate the -lobe. Intrinsic fibres (IF) run through the -lobe in the same direction, but not strictly parallel to each other or to the axis of the -lobe. Extrinsic fibres (EF) and their fine branches are often arranged perpendicular to the axis of the -lobe. There is some evidence that different IF zones occur in the -lobe when passing from its periphery to its centre. The distribution of EF may reflect a structural order when passing from the base of the lobe to its top. Numerous polarized synapses connect the IF with the EF. The IF show clusters of vesicles and presynaptic figures especially in their blebs, which can be seen in Golgi preparations for light microscopy. Two types of EF are distinguished on the basis of their synaptic junctions: (1) postsynaptic EF (abundant) and (2) EF with pre- and postsynaptic sites (perhaps restricted to some regions of the -lobe). Presynaptic IF converge on EF, which may transfer excitation from the -lobe to different parts of the brain and nervous system.

     

A Simple Method for Preparation of 18α-Glycyrrhetinic Acid and Its Derivatives

Treatment of 18-glycyrrhizic acid with a methanolic solution of HCl resulted in 1 : 1 mixture of methyl esters of 18- and 18-glycyrrhetinic acids. Benzoylation of the mixture led to methyl esters of 3-benzoyl-18-glycyrrhetinic acid and 3-benzoyl-18-glycyrrhetinic acid, which were separated by chromatography on silica gel. 18-Glycyrrhetinic acid was prepared by alkaline hydrolysis of methyl 3-benzoyl-18-glycyrrhetinate and was further used for the syntheses of 3-keto-18-glycyrrhetinic acid and methyl esters of 18-glycyrrhetinic acid and 3-keto-18-glycyrrhetinic acid.     

Concluding remarks

On the basis of symposium contributions onChlorella, Hibbertia, Eucalyptus, Ambrosia and on numerical approaches some fundamental problems of (bio)systematics, evolution, and taxonomic categories are discussed: Methods available for analysing affinities; conflicting evidence from phenetic, biochemical, cytogenetic and other analyses; further classification problems in cases of intermediacy, etc. While sibs of various levels and their natural hierarchy often can be objectively defined, this appears impossible for particular taxonomic levels itself (e. g. species). A single objective taxonomic system of organisms is unrealistic. Certain guiding lines for relative and practicable concepts of species and genus are proposed.Presented at the symposium Speciation and the Species Concept during the XIIth International Botanical Congress, Leningrad, July 8, 1975.     

An efficient synthesis of 3′-amino-3′-deoxythymidine derivatives

An efficient method of reduction of 3-azido-3-deoxythymidine and its 5-protected derivatives to 3-aminothymidine derivatives on a palladium catalyst using ammonium formate as a source of hydrogen was suggested.__________Translated from Bioorganicheskaya Khimiya, Vol. 31, No. 2, 2005, pp. 147–150.Original Russian Text Copyright © 2005 by Seregin, Chudinov, Yurkevich, Shvets.     

Syntheses of 1-O-benzyl-α-glucoside and 1-O-benzyl-α-maltoside by transglycosylation of α- amylase from soluble starch in aqueous solution

Glycosides, 1-O-benzyl--glucoside (BG) and 1- O-benzyl--maltoside (BM), were synthesized from soluble starch and benzyl alcohol by transglycosylation with an -amylase in a water system. BG was mostly obtained in a reaction mixture of pH 5.0, while BM was synthesized in pH 8.0. The synthesized glycosides had -configuration linkage between sugar and benzyl alcohol. The BG was rapidly hydrolyzed to benzyl alcohol and glucose by -glucosidase. The BM was hydrolyzed to BG and glucose below pH 5.0 by the -amylase used for its synthesis but it was not hydrolyzed above pH 8.0.     

Attenuation of changes in sarcoplasmic reticular gene expression in cardiac hypertrophy by propranolol and verapamil

The prothymosin a kinase (ProTK) is an apparently novel enzyme that is responsible for the phosphorylation of prothymosin (ProT), involved in the proliferation of mammalian cells. The present study investigated the properties of this enzyme. ProTK is more effectively activated by Mn²⁺ than by other divalent cations, and its activity is unaffected by RNA. Its principal substrate in proliferating cells appears to be ProTa. Both in vivo and in vitro, it is unable to phosphorylate the peptides thymosin ₁ and thymosin ₁₁, derived from the amino terminus of ProT, despite the fact that the sites of phosphorylation of ProT are contained within this part of its sequence. In trials in vivo, inhibition of gene expression abolished both phosphorylation of ProT and ProTK activity. ProTK is located in the cytosolic fractions throughout the cell cycle. Its activity, which is dependent on cell proliferation, increases markedly during S phase and begins to decline as the cell enters G2. Studies of the effects of activators and inhibitors of protein kinases involved in signal transduction pathways suggest that ProTK is activated by phosphorylation in a mitogen-initiated pathway that is dependent on PKC; however, PKC does not itself phosphorylate ProTK, which is therefore presumably phosphorylated by another kinase.     

Subunit structures of multiple hemoglobins in carp

Three hemoglobin components in carp designated CI, CII, and CIII, were isolated by DEAE-Toyopearl ion-exchange chromatography. Constituent globin chains, ¹, ², ¹ and ², were analyzed by urea-Triton acid polyacrylamide gel electrophoresis and isolated by high performance liquid chromatography with a reversed-phase column. Tryptic peptide mapping indicated that the -globin chains of the three hemoglobin components have slightly different structures. In addition, N-terminal amino acid sequence analysis indicated that the ¹-globin chain has a primary structure different from that of the ²-chain. A series of hybridization experiments between isolated hemoglobins, together with such structural properties of globin chains, suggested that the three hemoglobins have the following compositions: CI (^{1 2} ₂ ¹ ), CII (^{1 2 1 2}), and CIII (^{1 2} ₂ ² ). Hemoglobin CII was a hybrid between the two types each of - and -chain and could be constructed in vitro from two hemoglobin components CI and CIII.Abbreviations a-a amino acid - Hb hemoglobin - HPLC high performance liquid chromatography - P ₅₀ oxygen pressure at half saturation - PAGE polyacrylamide gel electrophoresis - TFA trifluoroacetic acid     

Action of rat liver Galβ1-4GlcNAc α(2-6)-sialyltransferase on Manβ1-4GlcNAcβ-OMe,GalNAcβ1-4GlcNAcβ-OMe,Glcβ1-4GlcNAcβ-OMe and GlcNAcβ1-4GlcNAcβ-OMe as synthetic substrates

Incubation of synthetic Man\1-4GlcNAc-OMe, GalNAc1-4GlcNAc-OMe, Glc1-4GlcNAc-OMe, and GlcNAc1-4GlcNac-OMe with CMP-Neu5Ac and rat liver Gal1-4GlcNAc (2-6)-sialyltransferase resulted in the formation of Neu5Ac2-6Man1-4GlcNAc-OMe, Neu5Ac2-6GalNAc1-4GlcNAc-OMe, Neu5Ac2-6Glc1-4GlcNAc-OMe and Neu5Ac2-6GlcNAc1-4GlcNAc-OMe, respectively. Under conditions which led to quantitative conversion of Gal1-4GlcNAc-OEt into Neu5Ac2-6Gal1-4GlcNAc-OEt, the aforementioned products were obtained in yields of 4%, 48%, 16% and 8%, respectively. HPLC on Partisil 10 SAX was used to isolate the various sialyltrisaccharides, and identification was carried out using 1- and 2-dimensional 500-MHz¹H-NMR spectroscopy.Abbreviations 2D 2-dimensional - CMP cytidine 5-monophosphate - CMP-Neu5Ac cytidine 5-monophospho--N-acetylneuraminic acid - COSY correlation spectroscopy - DQF double quantum filtered - HOHAHA homonuclear Hartmann-Hahn - MLEV composite pulse devised by M. Levitt - Neu5Ac N-acetylneuraminic acid - Neu5Ac2en 2-deoxy-2,3-didehydro-N-acetylneuraminic acid     

Polymerization of nucleotide analogues I: Reaction of nucleoside 5′-phosphorimidazolides with 2′-amino-2′-deoxyuridine

Summary 2-Amino-2-deoxyuridine reacts efficiently with nucleoside 5-phosphorimidazolides in aqueous solution. The dinucleoside monophosphate analogues were obtained in yields exceeding 80% under conditions in which little reaction occurs with the natural nucleosides.In a similar way, the 5-phosphorimidazolide of 2-amino-2-deoxyuridine undergoes self-condensation in aqueous solution to give a complex mixture of oligomers.The phosphoramidate bond in the dinucleoside monophosphate analogues is stable for several days at room temperature and pH 7. The mechanisms of their hydrolysis under acidic and alkaline conditions are described.Abbreviations A adenosine - C cytidine - G guanosine - U uridine - T thymidine - U_{N 3} 2-azido-2-deoxyuridine - U_{NH 2} 2-amino-2-deoxyuridine - ImpA adenosine 5-phosphorimidazolide - ImpU uridine 5-phosphorimidazolide - ImpU_{N 3} 2-azido-2-deoxyuridine 5-phosphorimidazolide - ImpU_{NH 2} 2-amino-2-deoxyuridine 5-phosphorimidazolide - pA adenosine 5-phosphate - pU uridine 5-phosphate - pU_{N 3} 2-azido-2-deoxyuridine 5-phosphate - pU_{NH 2} 2-amino-2-deoxyuridine 5-phosphate - UpA uridylyl-[35]-adenosine - UpU uridylyl-[35]-uridine - U_NpA adenylyl-[52]-2-amino-2-deoxy-uridine - U_NpU uridylyl-[52]-2-amino-2-deoxyuridine (pU_N)_n n=2,3,4 [25]-linked oligomers of pU_{NH 2} poly(A) polyadenylic acid - Im imidazole - MeIm l-methylimidazole     

Interferons up-regulate with different potency HLA class I antigen expression in M14 human melanoma cell line. Possible interaction with glucocorticoid hormones

The relative potency of interferon (IFN), interferon (IFN), and interferon (IFN) in inducing the expression of HLA class I antigens, as well as their capacity to counteract the inhibition induced by glucocorticoid hormones on HLA class I antigen expression, were analysed in the human melanoma cell line M14, both at membrane and at mRNA level. The data obtained indicate that (a) IFN enhance with different potency (IFN>IFN>IFN) the expression of HLA class I antigens in M14 cells, (b) prednisone inhibits HLA class I antigen expresion, (c) glucocorticoid hormones, when associated with IFN or IFN, inhibit the HLA class I enhancement induced by IFN alone, and ffinally, (c) the association between 1 M prednisone or 1 M deflazacort and IFN seems to potentiate the enhancing capacity of IFN on the expression of HLA class I molecules at the mRNA level. These findings, if confirmed, might indicate that IFN and glucocorticoid hormones are not mutually exclusive in the management of human melanoma.     

Enzymes in cardenolide-accumulating shoot cultures of Digitalis purpurea L.

In contrast to undifferentiated cell suspension cultures of Digitalis lanata, photomixotrophic shoot cultures of Digitalis purpurea accumulate cardiac glycosides in substantial concentrations. They are used to investigate enzymes of the cardenolide pathway. All cardenolides are 5-configurated. The progesterone 5-reductase and the 3-hydroxysteroid-5-oxidoreductase are present in shoot cultures but not in undifferentiated cell cultures. These enzymes provide precursors for cardenolides, whereas the presence of the progesterone 5-reductase, also present in shoot cultures, is discussed with regard to its role in phytosterol biosynthesis and may be attributed to the general steroid pathway. The progesterone 5-reductase had an activity maximum during the early growth period seven days after onset of cultivation, whereas the corresponding progesterone 5-reductase activity was highest on day 11. The maximum cardenolide accumulation was after 24 days. The enzyme activities present in crude extracts from shoot cultures were characterized with regard to their requirements for NADPH and NADH, pH-optimum, temperature optimum, affinity to their substrates and their localization in the cell. The progesterone 5-reductase was purified 769-fold.Abbreviations DW dry weight - FW fresh weight - PVP polyvinylpyrrolidone     

Conformationally constrained opioid peptide analogs with novel activity profiles

Novel conformationally constrained opioid peptide analogs with antagonist, mixed agonist/ antagonist or agonist properties were developed. TIP(P)-related antagonists showed unprecedented antagonist potency and receptor selectivity, and may have potential for use in analgesia in combination with agonists. A definitive model of their receptor-bound conformation was developed. Three prototype mixed agonist/ antagonists were discovered. They represent the only known compounds with this pharmacological profile and, as expected, one of them was shown to be a potent analgesic and to produce no dependence and less tolerance than morphine. Novel dipeptide derivatives turned out to be potent and selective agonists. Because of their low molecular weight and lipophilic character, these compounds may cross the blood-brain barrier and, thus, may have potential as centrally acting analgesics.     

Effect of “restricted ovulator” gene on uptake of yolk-precursor protein

Summary The bulk of the yolk proteins and lipoproteins constituting the yolks of mature oocytes in birds are synthesized by the liver and transported via the plasma to the oocytes where they are incorporated by micropinocytosis. Evidence is presented indicating that oocytes of hens possessing a mutation identified by Jones, Briles, and Schjeide as a restricted ovulator gene fail to incorporate normal amounts and proportions of low density lipoproteins, lipovitellin and possibly other proteins making up the bulk of the yolk material. Plasma albumin is taken into the yolks but the other proteins synthesized by the liver for deposition within the oocytes accumulate in the plasma, attaining very high levels. The possible nature of the lock preventing normal deposition of the excluded yolk proteins is discussed.     

Evaluation of hydrophobicity versus chaperonelike activity of bovine alphaA- and alphaB-crystallin

Calf lens A-crystallin isolated by reversed-phase HPLC demonstrates a slightly more hydrophobic profile than B-crystallin. Fluorescent probes in addition to bis-ANS, like cis-parinaric acid (PA) and pyrene, show higher quantum yields or Ham ratios when bound to A-crystallin than to B-crystallin at room temperature. Bis-ANS binding to both A- and B-crystallin decreases with increase in temperature. At room temperature, the chaperone-like activity of A-crystallin is lower than that of B-crystallin whereas at higher temperatures, A-crystallin shows significantly higher protection against aggregation of substrate proteins compared to B-crystallin. Therefore, calf lens A-crystallin is more hydrophobic than B-crystallin and chaperone-like activity of -crystallin subunits is not quantitatively related to their hydrophobicity.     

Über die Ultrastruktur des „Nervus opticus“ und des Ganglion opticum I von Daphnia pulex

Zusammenfassung Die Opticusfasern (Neuriten der Rezeptorzellen) und das Ganglion opticum I von Daphnia pulex wurden elektronenmikroskopisch untersucht. Die 8 Neuriten jeweils eines Ommatidiums werden in einem Bündel zusammengefaßt, in dem die Neuriten nur unvollständig von einem Gliafortsatz umhüllt sind, das Bündel jedoch vollständig von einer Basalmembran bedeckt ist. Die Neuriten weisen quervernetzte Mikrotubuli auf. In der Peripherie des Ganglion opticum liegen große und kleine unipolare Nervenzellen, deren Fortsätze ins zentrale Neuropil ziehen, wo sie u.a. synaptische Kontakte mit den Neuriten bilden. Es werden 3 Formen von Synapsen beschrieben: 1. eine bisher nicht beschriebene Synapsenform, 2. Synapsen von gewöhnlichem Typ und 3. Ribbon Synapsen. Die peripher gelegenen Gliazellen umhüllen die Nervenzellen und senden lamelläre Fortsätze in das Neuropil, wo sie sich den benachbarten Zellelementen derart anpassen, daß der extrazelluläre Raum zu einem System von Interzellularfugen eingeengt wird. Außer den beschriebenen Zellformen kommen weniger häufig neurosekretorische Nervenzellen vor, deren Fortsätze an der Ganglionoberfläche nur von Basalmembranen bedeckt sind. Ferner sind selten multipolare Ganglienzellen zu finden.

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On the ultrastructure of the optic nerve and the ganglion opticum I of Daphnia pulex

Summary Optical fibres (neurites of receptor cells) and ganglion opticum I of Daphnia pulex were studied electron microscopically. The 8 neurites of each ommatidium are bundled by a complete wrapping of basement membrane, while each neurite is incompletely enveloped by a glial process. The neurites contain transversally interconnected microtubules. Processes of large and small unipolar nerve cells situated at the periphery of the ganglion reach the central neuropile, where they establish synaptic contacts, f.i., with optical fibres. 3 types of synapses occur: 1. one type of synapse which has not yet been described, 2. synapses of the usual type, 3. ribbon synapses. Glial cells situated peripherally in the ganglion envelope the nerve cells. Their lamellar processes projecting into the neuropile adapt their surfaces to all neighboring elements so that the extracellular space is reduced to a labyrinth of narrow intercellular clefts. The number of multipolar ganglion cells and neurosecretory elements is relatively small. The processes of neurosecretory cells contact the surface of the ganglion where they are covered by a basement membrane.

     

The rapid switch-off of nitrogenase activity in obligate methane-oxidizing bacteria

Nitrogenase activity in the obligate methaneoxidizing bacterium Methylococcus capsulatus (Bath) was added ammonia. This observation was extended to include other ammonia. This observation was extended to include other representative N₂-fixing species of methanotrophs. The ammonia switch-off of nitrogenase in M. capsulatus (Bath) was reversed on washing cells to remove excess ammonia, in the presence of chloramphenicol, suggesting that a form of covalent modification of nitrogenase may occur. Replacing the oxidizable substrate methanol with formaldehyde, formate, ethanol or hydrogen had no effect on nitrogenase switch-off. A number of potential nitrogen sources or intermediates of nitrogen metabolism such as glutamine, asparagine, glutamate and alanine when tested, did not effect switch-off. However, the rapid inhibition of nitrogenase activity of M. capsulatus (Bath) could be achieved by adding the uncoupler carbonylcyanide m-chlorophenylhydrazone or nitrite. The glutamine synthetase inhibitor methionine sulphoximine blocked the switch-off effect of ammonia, indicating that the metabolism of ammonia may be essential for switch-off to occur. Inhibitors of glutamate synthase did not alleviate the ammonia switch-off response. Methionine sulphoximine did not alleviate the rapid inhibition of nitrogenase by carbonylcyanide m-chlorophenylhydrazone indicating that the shortterm regulation of nitrogenase by uncouplers and ammonia proceed via different mechanisms.Abbreviations MSX methionine-DL-sulphoximine - DON 6-diazo-5-oxo-L-norleucine - GS glutamine synthetase - GOGAT glutamine 2-oxoglutarate aminotransferase (glutamate synthase) - CCCP carbonylcyanide m-chlorophenyl hydrazone     

The involvement of the 3′:5′-cyclic-AMP phosphodiesterase in transformation and growth of crown-gall tumors in Bryophyllum daigremontianum

In crown-gall tumor tissue obtained from leaves of Bryophyllum daigremontianum an adenosine 3:5-cyclic phosphate (3:5-cyclic-AMP) degrading activity increases up to 2.5 fold until the fifth day after inoculation with Agrobacterium tumefaciens, declining to the value of the control in the solid tumor. Theophylline up to 1 mmol l^–1 given to wounded leaves of Bryophyllum daigremontianum has no effect on the number of tumors. The effect of higher concentrations given over extended periods can be explained otherwise. Therefore it seems likely that the 3:5-cyclic-AMP phosphodiesterase (EC 3.1.4.17) has no effect on transformation and growth of crown-gall tumors in Bryophyllum daigremontianum.     

Selective impairment of protein kinase C isotypes in murine macrophage by Leismania donovani

Leishmania donovani, an obligate intracellular parasite resides and multiplies within macrophage of the reticuloendothelial system. The intracellular signalling mechanism involved in the impaired oxidative response in leishmaniasis has not yet been clearly established. Generation of superoxide anion (O₂ ^–) is supposed to be the first line of host defence during microbial invasion. We found a substantial inhibition of superoxide anion generation in parasitized macrophages, which was just the reverse in case of macrophages challenged with Lipophosphoglycan (LPG) deficient attenuated leishmanial parasite UR-6. The generation of O₂ ^– essentially needs the prior activation of protein kinase C (PKC) mediated phosphorylation events. Our study proposed that phosphorylation of 67, 54, 47 and 36 kDa proteins was attenuated during infection. This was supported by PKC activity study, where Ca-dependent PKC activity was inhibited but, Ca-independent PKC activity was enhanced. This result was further confirmed by using isotype specific pseudosubstrate inhibitors of Ca-dependent PKC and Ca-independent PKC . Application of -pseudosubstrate could not alter the Ca-dependent PKC activity but -pseudosubstrate inhibited the Ca-independent PKC activity in infected macrophages. Our immunoblot analysis with specific antibody against PKC and PKC isotypes showed down regulation of PKC -II expression with concomitant induction of PKC . Such inhibition of Ca-dependent PKC was reversed in macrophages treated with UR-6. Taken together, our observations revealed that infection with L. donovani selectively attenuates both the expression and activity of Ca-dependent PKC .     

Purification and characterization of (1→3, 1→4)-β-glucan endohydrolases from germinated wheat (Triticum aestivum)

A (13, 14)--glucan 4-glucanohydrolase [(13, 14)--glucanase, EC 3.2.1.73] was purified to homogeneity from extracts of germinated wheat grain. The enzyme, which was identified as an endohydrolase on the basis of oligosaccharide products released from a (13, 14)--glucan substrate, has an apparent pI of 8.2 and an apparent molecular mass of 30 kDa. Western blot analyses with specific monoclonal antibodies indicated that the enzyme is related to (13, 14)--glucanase isoenzyme EI from barley. The complete primary structure of the wheat (13, 14)--glucanase has been deduced from nucleotide sequence analysis of cDNAs isolated from a library prepared using poly(A)⁺ RNA from gibberellic acid-treated wheat aleurone layers. One cDNA, designated LW2, is 1426 nucleotide pairs in length and encodes a 306 amino acid enzyme, together with a NH₂-terminal signal peptide of 28 amino acid residues. The mature polypeptide encoded by this cDNA has a molecular mass of 32085 and a predicted pI of 8.1. The other cDNA, designated LW1, carries a 109 nucleotide pair sequence at its 5 end that is characteristic of plant introns and therefore appears to have been synthesized from an incompletely processed mRNA. Comparison of the coding and 3-untranslated regions of the two cDNAs reveals 31 nucleotide substitutions, but none of these result in amino acid substitutions. Thus, the cDNAs encode enzymes with identical primary structures, but their corresponding mRNAs may have originated from homeologous chromosomes in the hexaploid wheat genome.     

Rna-mediated regulation of Receptor-Ck gene in human platelets

The study addressed to understand the regulation of Receptor-C_k gene atthe translational level revealed that exogenous cholesterol has the inherentcapacity to regulate the endogenous synthesis of Receptor-C_k by initiatingintracellular targeting of the Receptor-C_k to the mRNP pool within humanplatelets and this effect could be reversed when the platelets wereincubated with cholesterol coupled with either dB cAMP or dB cGMP. Basedupon these observations, we propose that Receptor-C_k initiated signalling,which involves second messengers like PA, cAMP and cGMP, may be responsiblefor the autoregulation of Receptor-C_k gene expression at the translationallevel.