Turnover and transport of quinolizidine alkaloids. Diurnal fluctuations of lupanine in the phloem sap,leaves and fruits of Lupinus albus L.

Quinolizidine alkaloids formed in the leaves of Lupinus albus L. are translocated via the phloem to the other plant organs, especially the maturing fruits. Compared with amino-acid transport in the phloem, the alkaloids contribute about 8% to the overall nitrogen being exported from the leaf. Since it is likely that the alkaloids are subsequently degraded in the target tissues a minor role of quinolizidine alkaloids might be nitrogen transport. A marked diurnal fluctuation of alkaloids was observed in the leaves, the phloem sap, the roots and the fruits with an increase during the day and an amplitude of several hundred percent thus providing evidence for a rapid turnover of endogenous alkaloids.Abbreviations QA quinolizidine alkaloids - GLC gas-liquid chromatography     

Die postembryonale Entwicklung und die funktionelle Anatomie des Gnathosoma in der Milbenfamilie Erythraeidae (Acarina,Prostigmata)

Zusammenfassung Das Gnathosoma von sieben Arten der Milbenfamilie Erythraeidae wurde untersucht. Die postembryonale Entwicklung der Cuticula-Strukturen, der Muskulatur und der Drüsen wird beschrieben.Das Gnathosoma der Larven weist Cheliceren auf, die aus Grundglied und klauenförmigem Digitus mobilis bestehen. Sie liegen dem Infracapitulum dorsal auf und inserieren an einem Paar Capitular-Apophysen. Bei den Protound Tritonymphen unterliegt das Gnathosoma der Histolyse und wird anschließend jeweils neu ausgebildet. Bei der Deutonymphe und beim Adultus ist es gegenüber der Larve stark abgewandelt: Die Tracheenstämme sind aus den Capitular-Apophysen der Larve abzuleiten. Die Stech-Cheliceren entsprechen dem Grundglied der larvalen Cheliceren, und ihre medialen Protraktoren gehen aus den Levator-Muskeln der Cheliceren der Larve hervor.Der Weg der Sekrete der podocephalischen und infracapitulären Drüsen über die Dorsalfläche des Infracapitulum erfährt mit dem Erwerb schmaler Stech-Cheliceren eine radikale Umstellung des Schutzes gegen Austrocknung. Während bei der Larve die breiten Cheliceren-Grundglieder den Sekretweg überdecken, und der Raum zwischen den Grundgliedern und dem Infracapi-tulum zusätzlich durch das ölartige Sekret der Intercheliceraldrüse ausgefüllt wird, schließen sich bei der Deutonymphe und beim Adultus die Lateralkiele der Genae über den Stech-Cheliceren zusammen, und der hintere Abschnitt des Cervix wird in das Idiosoma eingesenkt. Dadurch wird der Cervix zu einem internen Cervicalkanal umgebildet.Der Mundraum wird bei den aktiven Stadien durch die lipidartigen Sekrete der Buccal- und Labialdrüsen geschützt.Die phylogenetischen Beziehungen der Parasitengona innerhalb der Prostigmata und der Erythraeidae innerhalb der Parasitengona werden diskutiert.

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Postembryonic development and functional anatomy of the gnathosoma in the family Erythraeidae (Acarina, Prostigmata)

Summary The gnathosoma of seven species of the Erythraeidae was investigated. The postembryonic development of the cuticular structures, the musculature and the glands are described.In the larval gnathosoma, the chelicerae consist of a basal segment and a claw. They rest upon the dorsal surface of the infracapitulum. The basal segments are attached to a pair of capitular apophyses (sigmoid pieces). During the two molts larva to protonymph and deutonymph to tritonymph, the gnathosoma is histolysed. Directly afterwards it is rebuilt. Compared to the larva, in the deutonymph and in the adult it undergoes profound changes: The capitular apophyses are transformed to parts of the tracheae, the basal segment of each chelicera to a styliform chelicera, and the levator muscles of the chelicerae to medial protractors of the styliform chelicerae.The secretions of the podocephalic and infracapitular glands proceed along the dorsal surface of the infracapitulum to the buccal cavity. In the larva, the way of the secretions is protected against desiccation by the broad basal segments of the chelicerae, that cover the infracapitulum. In addition the oily secretion of the intercheliceral gland seals the space between the infracapitulum and the chelicerae. By obtaining styliform chelicerae the protection against desiccation undergoes a radical change: The lateral ridges of the infracapitulum join above the chelicerae, and the posterior part of the cervix is transferred back into the idiosoma. Thus the cervix is transformed into an internal canal.In the active instars, the buccal cavity is protected by the lipid-like secretions of the buccal glands and labial glands.The phylogenetic relationships of the Parasitengona within the Prostigmata, and of the Erythraeidae within the Parasitengona are discussed.

     

Structure of the murine leukemia virus envelope glycoprotein precursor.

The glycosylated env gene precurosr (Pr80env) of Moloney murine leukemia virus has been isolated by selective immunoprecipitation. Use of the drug tunicamycin to inhibit nascent glycosylation or specific cleavage with endoglycosidase H demonstrated that the precursor contained an apoprotein with a molecular weight of 60,000. The finished virion glycoprotein (gp70) was largely resistant to the action of endoglycosidase H. Chromatography of the glycopeptides of Pr80env in conjunction with endoglycosidase H digestion studies suggested that the precursor contained two distinct major glycosylation sites. Analysis of partial proteolytic cleavage fragments of Pr80env before and after endoglycosidase H treatment placed the two glycosylation sites within a 30,000-dalton region of the apoprotein sequence. Kinetic experiments showed that carbohydrate processing as well as proteolytic cleavage are late steps in the maturation of Pr80env.     

Peroxidases in Relation to Removal of Dormancy and Germination of Apple Embryos

The changes in germination, peroxidase activity and isoperoxidase spectrum have been studied in apple embryos at 5°C (stratification) and at 20°C in the presence or absence of seed coats. The embryo dormancy is progressively released at 5°C, but not at 20°C. The peroxidase activity in embryos covered with seed coats is very low at 5°C as well as at 20°C which corresponds to a restricted number of isoenzymes. In isolated embryos the peroxidase activity increases significantly. This is due to an increase in both the number and the activity of the isoperoxidases and it is more pronounced at 20°C than at 5°C. The obtained results suggest that the soluble peroxidases are not involved in the process of the release of embryo dormancy. The variations observed are attributed to the growth process following germination, which can occur even at low temperature.     

Coordinate developmental regulation of purine catabolic enzyme expression in gastrointestinal and postimplantation reproductive tracts

Using histochemical detection, we have visualized in situ the complete metabolic pathway for the degradation of purine nucleotides. From the tongue to the ileum, diverse epithelial cell types lining the lumen of the mouse gastrointestinal (GI) tract strongly coexpress each of the five key purine catabolic enzymes. Dramatic increases in the expression of each enzyme occurred during postnatal maturation of the GI tract. Using in situ hybridization, an intense accumulation of adenosine deaminase (ADA) mRNA was detected only within GI epithelial cells undergoing postmitotic differentiation. In a similar manner, at the developing maternal-fetal interface, high level expression of the purine catabolic pathway also occurred in a unique subset of maternal decidual cells previously known to express high levels of alkaline phosphatase and ADA. This induction occurred almost immediately after implantation in the periembryonic maternal decidual cells, shortly thereafter in antimesometrial decidual cells, and later in cells of the placental decidua basalis: all of which contain cell types thought to be undergoing programmed cell death. The expression of the pathway at the site of embryo implantation appears to be critical because its pharmacologic inhibition during pregnancy has been found to be embryolethal or teratogenic. Purine destruction at these nutritional interfaces (placenta and gastrointestinal tract) seem to override any potential economy of purine salvage, and may represent biochemical adaptation to nucleic acid breakdown occurring in the context of dietary digestion or extensive programmed cell death.     

Rapid stimulation of Ser/Thr protein kinases following treatment of Swiss 3T3 cells with bombesin. Involvement of casein kinase-2 in the signaling pathway of bombesin.

Treatment of quiescent Swiss 3T3 mouse fibroblasts with bombesin resulted in a rapid 6-8-fold stimulation of cytosolic Ser/Thr kinase activities toward the S6 peptide (RRLSSLR), myelin basic protein (MBP), and the G peptide (SPQPSRRGSESSEE). Anion exchange Mono Q chromatography resolved multiple S6 peptide- and G peptide kinase activities and two MBP kinase peaks. Both MBP- and several S6 peptide kinase peaks could be inactivated by PCSL (PP2A2) phosphatase action. This indicates that the bombesin-induced activation of these enzymes is mediated by a Ser/Thr phosphorylation event. The S6 peptide kinases as well as the two MBP kinases stimulated in response to bombesin are similar to those activated by epidermal growth factor in Swiss 3T3 fibroblasts which suggests that the early events of the signal transduction pathway mediated by these growth factors in Swiss 3T3 cells may converge in the activation of common Ser/Thr kinases. Bombesin, which acts as a sole mitogen for Swiss 3T3 fibroblasts, also produced a several-fold increase in the kinase activity toward the RRREEESEEE peptide, a specific substrate for CK-2. This kinase activity was heparin-sensitive and also measurable with the G peptide (SPQPSRRGSESSEE) and GS-1 peptide (YRRAAVPPSPSPSLSRHSSPHQSEDEE), which contain consensus sequences for phosphorylation by CK-2. The bombesin-stimulated CK-2 activity could not be measured in whole cytosols but was revealed by the anion exchange chromatography step. The activation of CK-2 was not reversed by PCSL phosphatase action. The implication of CK-2 in the signal transduction pathway of bombesin is discussed.     

Experimental and clinical studies of neonatal eeg mapping--methodical prerequisites and data interpretation.

To investigate whether the sampling theorem was fulfilled up to now in experimental and clinical EEG-mapping of neonates and to determine the "smearing effect" of EEG transmission by the leading media up to the skin, EEG-maps from 5 slightly anaesthetized term newborn piglets and 8 healthy human newborns were calculated. A spatial sampling rate of 1-2 cycles per cm is necessary for a sufficient reproduction of surface EEG topology in newborn piglets showing activity maxima within motor projection zones. In human neonates, 8-channel mapping gave insufficient results, whereas state and EEG pattern related 16-channel maps provided sufficiently constant, but not complete pattern. Simultaneous maps from epidural and epiossal, and epiossal, and surface recordings in newborn piglets showed only small "smearing" effects. We conclude, the more topical interpretation chances exist, like in neonates with smaller "smearing" effects of transmission media, the more complete uptake of original data for mapping is necessary. Up to now, it is done seldomly.     

Metabolism of p-fluorophenylalanine in p-fluorophenylalanine sensitive and resistant tobacco cell cultures

The metabolism of D- and L-p-fluorophenylalanine (PFP) in DL-PFP resistant and sensitive tobacco cell cultures (Nicotiana tabacum), cell lines TX4 and TX1, respectively, has been compared. The amino acid analogue was taken up at a lower rate by the resistant cell line TX4. Incorporation of PFP into protein was also considerably reduced in TX4 cells, compared to TX1 cells. This, however, resulted mainly from a diminished availability of PFP due to a more rapid conversion of PFP by TX4 cells. TX1 cells and TX4 cells converted PFP qualitatively in the same way. The only detectable metabolite of D-PFP was N-malonyl-D-PFP, while all metabolites of L-PFP were identified as sequent products of the initial deamination of L-PFP by the enzyme phenylalanine ammonia-lyase (PAL). As TX4 cells were endowed with higher PAL-activity than TX1 cells, the resistant cells were able to metabolize L-PFP more rapidly to give, e.g., p-fluorocinnamoyl glucose ester and p-fluorocinnamoyl putrescine. In the presence of the specific PAL-inhibitor -aminooxy--phenylpropionic acid TX4 cells were slightly more sensitive to PFP. This suggests that the better detoxification contributes to the acquired resistance. The use of PFP as specific indicator for cell lines with increased PAL-activity, and hence increased levels of phenolic compounds, is discussed.Abbreviations AOPP -aminooxy--phenylpropionic acid - MCW methanol:chloroform:water - PAL phenylalanine ammonia-lyase - PFP p-fluorophenylalanine - Phe phenylalanine     

Abelson murine leukemia virus-induced tumors elicit antibodies against a host cell protein, P50.

When BALB/c mice were injected with a syngeneic cell line transformed by Abelson murine leukemia virus (A-MuLV), the tumor was usually lethal. In sera from tumor-bearing mice, and at highest levels in sera from mice that reject their tumors, was an antibody that immunoprecipitates a specific protein from [35S]-methionine-labeled A-MuLV-transformed BALB/c cells. This protein was not the previously characterized A-MuLV-specific protein (P120) but a 50,000-molecular-weight protein (P50). Such sera may also immunoprecipitate P120, but no other protein was reproducibly precipitated by them. A monoclonal antibody (RA3-2C2) that has been shown to stain normal B-lymphocytes also selectively immunoprecipitated P50. P50 was present in A-MuLV-transformed lymphoid and fibroblastic cells of a variety of mouse strains. One A-MuLV-transformed cell line had a very low P50 level, the L1-2 tumor of C57L origin. This tumor was previously shown to be rejected by C57L mice and is used to produce anti-P120 (anti-AbT) sera. P50 was not a Moloney MuLV protein and was found at low levels in normal cells of cells transformed by agents other than A-MuLV; thus, it was probably a host cell protein whose concentration was selectively accentuated by A-MuLV transformation. P50 was phosphorylated and, by using indirect immunofluorescence, anti-P50 serum stained live A-MuLV-transformed cells. The protein was not glycosylated and did not label by lactoperoxidase-catalyzed iodination. Thus, P50 was very like P120 in its cellular localization and properties, but it did not exhibit proptein kinase activity in vitro. The selective accentuation of this protein in A-MuLV transformants and its strong antigenicity in syngeneic animals suggest that it is a unique and functionally important protein.