Binding of opiates and endogenous opioid peptides to neuroleptic receptor sites in the corpus striatum.

Some opiates with morphinan- and benzomorphan-structures possess affinities for neuroleptic receptors as revealed by their abilities to compete with ³H-spiroperidol for common binding sites in rat striatum $\text{in vitro}$ (IC₅₀ in the range between 10^?6 and 10^?5M). The binding of these opiates to neuroleptic receptors appears to be of pharmacological significance, since $\text{in vivo}$ studies in mice revealed a small but significant displacement of spiroperidol by high doses of the opiate antagonist levallorphan from specific binding sites in the striatum. In addition, there exists some correlation between the ability of opiates to bind to neuroleptic receptor sites $\text{in vitro}$ and their potency to evoke “bizarre behavior” in rats $\text{in vivo}$. In contrast, a wide variety of other opiates having morphine-, morphinone- or oripavine-structure showed no affinity for neuroleptic binding sites $\text{in vitro}$ (IC₅₀ greater than 10^?4 M). Of the opioid peptides (methionine-enkephalin, leucine-enkephalin and β-endorphin) none has an affinity for neuroleptic binding sites. A variety of other peptides were also investigated but did not interfere with spiroperidol binding. Only ACTH showed a moderate affinity for neuroleptic binding sites.     

Adenosylhomocysteinase and adenosine nucleosidase activities in Lupinus luteus cotyledons during seed formation and germination

The activities of adenosylhomocysteinase (EC 3.3.1.1) and adenosine nucleosidase (EC 3.2.2.7) were assayed in extracts from yellow lupin (Lupinus luteus L.) cotyledons at different stages of seed formation and seedling development. Adenosylhomocysteinase activity was demonstrated in all the cotyledon extracts examined. Its lowest level was found in the dry seeds and the highest, in 4-day-old seedling cotyledons. Extracts from the cotyledons of maturating seeds, dry seeds, and seedlings up to the second day of growth exhibited no adenosine nucleosidase activity. Adenosine nucleosidase activity appeared in the cotyledons of 2-day-old seedlings and its highest level was reached in 4-to 5-day-old seedlings. There is no inhibitor of adenosine nucleosidase in the maturating and dry yellow lupin seeds. No activator of a possible zymogen form of adenosine nucleosidase from maturating or dry seeds occurs in the growing seedlings.     

Effects of oleate,palmitate, and octanoate on gluconeogenesis in isolated rabbit liver cells

The effect of oleate, palmitate, and octanoate on glucose formation was studied with lactate or pyruvate as substrate. Octanoate was much more quickly oxidized and utilized for ketone body production than were oleate and palmitate. Among fatty acids studied, only octanoate resulted in a marked increase of the 3-hydroxybutyrate/acetoacetate (3-$\text{OHB}\text{AcAc}$) ratio. Each of the fatty acids studied stimulated glucose synthesis from pyruvate. The enhancement of gluconeogenesis by long-chain fatty acids was abolished after the addition of ammonia. As concluded from the “crossover” plot, the stimulatory effect of fatty acids was due to: (i) a stimulation of pyruvate carboxylation, (ii) a provision of reducing equivalents for glyceraldehyde phosphate dehydrogenase, and (iii) an acceleration of flux through hexose diphosphatase. Moreover, palmitate and oleate resulted in an increased generation of mitochondrial phosphpenolpyruvate, while in the presence of octanoate, the activity of mitochondrial phosphoenolpyruvate carboxykinase was diminished. When lactate was used as the glucose precursor, palmitate and oleate increased glucose production by about 50% but did not affect the contribution of mitochondrial phosphoenolpyruvate carboxykinase to gluconeogenesis. In contrast, in spite of the stimulation of both pyruvate carboxylase and hexose diphosphatase, as judged from the crossover plot, the addition of octanoate resulted in a marked inhibition of both glucose formation and mitochondrial generation of phosphoenolpyruvate. The inhibitory effect of octanoate was reversed by ammonia. Results indicate that fatty acids and ammonia are potent regulatory factors of both the rate of glucose formation and the contribution of mitochondrial phosphoenolpyruvate carboxykinase to gluconeogenesis in hepatocytes of the fasted rabbit.     

Calorimetric studies of flavin-binding proteins: FMN and FAD binding to hen egg riboflavin-binding proteins

Systematic thermodynamic studies have been conducted for flavin (FMN, FAD) binding to purified riboflavin-binding proteins from hen egg white and egg yolk. These studies were conducted under a variety of temperature (14, 26, and 38 °C), pH (4.5, 5.5, 6.5, 7.4, and 9.0), and buffer conditions, and an extensive thermodynamic profile was constructed. Enthalpies of binding FMN to white riboflavin-binding protein and yolk riboflavin-binding protein were ?19.3 and ?14.4 kcal/mol, respectively, at pH 7.4 and 38 °C. FAD bound to white and yolk riboflavin-binding proteins under the same conditions with ΔH values of ?11.7 and ?6.0, respectively. Binding constants of about 10⁵ and 10⁴ were obtained for FMN and FAD, respectively, and were the same for both proteins under all conditions studied. Using established thermodynamic relationships, we were able to calculate entropy and free energy changes. Entropies indicated a large degree of ordering in the system upon flavin binding with FMN (about ?40 cal/mol/ °C) twice as large as FAD (about ?15 to ?25 cal/mol/ °C), which may indicate a structured solvent interaction with the charged phosphate group, or steric limitations placed on the ribityl side chain in the bound state. Our thermodynamic data support the idea that flavin binding is a mixture of forces, with no one predominant. Analysis of the data suggests that the nucleotide may bind both as the mono- or dianion, that flavin binding occurs with no significant change in the pK of any functional group in the system, except at low pH for FAD binding, and that the temperature variation of the enthalpy change is quite small. These findings are combined with other published data to outline a general scheme of flavin binding with a histidine residue implicated in hydrogen bonding to the adenine portion of FAD, which may be in the unstacked form.     

Replication variants of the human inactive X chromosome

The sequence of DNA replication was studied within the inactive X chromosome in human lymphocytes, by means of the FPG method. Several variants of the replication sequence were found. The number of variants in the cells of a single donor exceeded 2 in each of the 4 normal individuals studied. The phenomenon is discussed with respect to the regulation of DNA synthesis and to the cell differentiation process.     

Antibodies to the alpha q subfamily of guanine nucleotide-binding regulatory protein alpha subunits attenuate activation of phosphatidylinositol 4,5-bisphosphate hydrolysis by hormones.

The subfamily of guanine nucleotide-binding regulatory (G proteins) designated Gq has been shown to regulate the activity of phospholipase C by reconstitution. However, the role of these proteins in hormonal regulation of this activity has not been demonstrated. Two antisera were used in attempts to interrupt this pathway. Antiserum W082, developed against a peptide representing an internal sequence in alpha q, was specific for alpha q by immunoblots but did not recognize the native protein. Antiserum X384 was developed against a peptide representing the 12 amino acids of the common carboxyl termini of alpha q and alpha 11. It had a broader specificity for this subfamily of G protein alpha subunits and recognized the native proteins. Antiserum X384 specifically immunoprecipitated alpha q and its homologs from purified preparations and detergent extracts of membranes. Affinity-purified antibodies attenuated stimulation of phosphatidylinositide 4,5-bisphosphate hydrolysis by bradykinin, angiotensin, and histamine in membranes derived from NG108-15 cells, rat liver, and 1321N1 cells, respectively. Activation of the phospholipase C activity by guanosine 5'-3-O-(thio)triphosphate alone was also inhibited. Inclusion of the peptide to which the antisera were raised blocked the effect of the antibody. In contrast, affinity-purified W082, which did not recognize native proteins, did not alter regulation of phospholipase C. This indicates that the Gq family of signaling proteins can couple to several receptors and is responsible for the hormonal regulation of phospholipase C in these diverse systems. The further generality of this regulatory pathway remains to be established.     

Comparison of the effects of neurotensin and ACTH on the pituitary-adrenocortical axis of dexamethasone-suppressed rats.

Neurotensin (NT) (12-48 micrograms/kg-1/day-1, for 2 days, s.c.), like ACTH (60 micrograms/kg-1/day-1, for 2 days, s.c.), counteracted the dexamethasone (Dx)-induced (120 micrograms/kg-1/day-1, for 4 days, s.c.) adrenal zona-fasciculata cell atrophy. NT notably raised, in Dx-suppressed rats, the plasma concentration of ACTH, which reached about that found after exogenous ACTH administration. However, at variance with ACTH, NT did not enhance either plasma corticosterone (B) level or B production by adrenal quarters in vitro. The conclusion is drawn that NT modulates the function of the rat pituitary-adrenocortical axis, by simultaneously stimulating hypophyseal ACTH release and inhibiting steroidogenesis at the adrenal level.     

Satelliten-Telemetrie beim Wei?storch (Ciconia ciconia) auf dem Wegzug — eine Pilotstudie

Zusammenfassung (1) 1991 konnten erstmals 4 mit Kleinsendern ausgerüstete Weißstörche mit Hilfe der Satelliten-Telemetrie auf Teilstrecken ihres Wegzugs bis zu 46 Tage lang verfolgt werden. Die japanischen Sender betrugen nur etwa 2 % des Körpergewichts der Vögel; die Ortung erfolgte durch das ARGOS-System. Die Versuchsvögel zeigten völlig normales Zugverhalten. — (2) Drei der in Brandenburg und Sachsen-Anhalt markierten Vögel waren Ostzieher und konnten über Strecken von etwa 640–4700 km verfolgt werden, 1 Storch bis zur ägyptisch-sudanesischen Grenze. Ein Westzieher konnte rund 1400 km bis zu den Pyrenäen geortet werden. — (3) Die Vögel wanderten individuell recht verschieden. 2 zogen weitgehend kontinuierlich bis in den Sudan bzw. zu den Pyrenäen, die anderen legten längere Pausen ein. Die ermittelten Zugstrecken verliefen recht geradlinig; Richtungsänderungen erfolgten vor allem an der Donau, den Karpaten, am Mittelmeer und auf der Sinai-Halbinsel. Tagesetappen betrugen mindestens bis zu 370 km, in einem Fall in 21 Tagen durchschnittlich 224 km/Tag. Die Zuggeschwindigkeit lag in der Größenordnung von 30–90 km/h. — (4) Verbesserte Sender mit längerer Lebensdauer und mehreren Ortungen pro Tag dürften es bald ermöglichen, individuelle Wanderrouten von Weißstörchen und anderen Großvögeln praktisch lückenlos zu ermitteln. Begleitmannschaften werden zudem die Zug- und Rastökologie mit Sendern ausgerüsteter Vögel mit erfassen können. Damit dürfte der Vogelschutz auf dem Zug eine neue Dimension gewinnen.

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Satellite tracking of White Storks during the autumn migratory period — a pilot study

Summary (1) In 1991 parts of the routes of White Storks migrating in autumn could be recorded for the first time by satellite tracking. Four individuals could be followed for up to 46 days. Transmitter weight accounted for only about 2 % of body mass. Locations were obtained by the ARGOS system. Migratory behaviour of the experimental birds appeared to be absolutely normal. — (2) The birds were equipped with transmitters in eastern Germany. Three of them followed the eastern migration route and could be tracked from 640 up to 4700 km, the latter reaching the borders of Egypt and Sudan. A western migrant could be followed over a distance of about 1400 km towards the Pyrenees. — (3) Migration showed considerable individual variation. Whereas in two birds migration was largely continuous towards the Sudan and the Pyrenees, respectively, the other birds rested for longer periods. The tracked migration routes were fairly straight. Marked directional shifts occurred towards the Danube valley, at the Carpathian mountains, the Mediterranean and on the Sinai. Capacity per day was at least 370 km. One bird covered 224 km/day on average during a period of 21 days. Migration speed ranged in the magnitude of 30–90 km/h. — (4) Improved transmitters with increased lifetime giving several locations per day will presumably allow to record migration routes of White Storks and other large birds more completely in the near future. Escorts should then be able to closely analyse the ecology of migration and staging of their test birds. These possibilities may give a new dimension to bird conservation measures during migration.

     

On the evolution of the bacterial major sigma factors

Summary The existence of internal sequence homologies between the N-terminal halves of the gram-negative bacterial major sigma factors and their C-terminal halves, which correspond to minor factors, is reported. In the case of Escherichia-Salmonella sigma-70, an apparent homology was even found between the C-terminal helix-turn-helix DNA-binding motif and the corresponding region of the peptide N half, which, however, is not directly engaged in promoter recognition. It is proposed that major sigma factors may have originated by duplication and fusion of a DNA unit related to the ancestral gene for the whole sigma family. Coevolution of major sigma structures and complex promoters is suggested.