Diel plasma melatonin profile in a cyclostome, the river lamprey

Plasma melatonin levels in adult river lampreys Lampetra fluviatilis , sampled during their upstream migration showed a pronounced diel profile, with high levels during the night and lower levels during the day, showing that a cyclostome, in common with other vertebrates, exhibits such a diel plasma profile.     

Mitochondrial production of pro-oxidants and cellular senescence.

Mitochondria are the major intracellular producers of O2- and H2O2. The level of oxidative stress in cells, as indicated by the in vivo exhalation of alkanes and the concentration of molecular products of oxy-radical reactions, increases during aging in mammals as well as insects. In this paper, we discuss the relationship between mitochondrial generation of O2- and H2O2, and the aging process. The rate of mitochondrial O2- and H2O2 generation increases with age in houseflies and the brain, heart and liver of rat. This rate has been found to correspond to the life expectancy of flies and to the maximum life span potential (MLSP) of six different mammalian species, namely, mouse, rat, guinea pig, rabbit, pig and cow. In contrast, the level of antioxidant defenses provided by activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione concentration neither uniformly declines with age nor corresponds to variations in MLSP of different mammalian species. It is argued that the rate of mitochondrial O2- and H2O2 generation rather than the antioxidant level may act as a longevity determinant.     

Up-regulation of prostaglandin E2 binding and of prostanoid release in rabbits producing antibodies against prostaglandin E2

German Giant rabbits successfully immunized against prostaglandin (PG) E2 as shown by a rise in antibody titers developed gastric mucosal lesions. Enzymatically dispersed gastric mucosal cells of these animals had a significantly enhanced production of PG E2 and PG I2 as measured by specific radioimmunoassays. This may be explained by an increased supply with endogenous arachidonic acid (as indicated by an enhanced phospholipase A2/LAT ratio) and by a higher activity of the subsequent PG forming enzymes (as indicated by a more effective stimulation of PG production by exogenous arachidonic acid). Gastric mucosal plasma membranes of immunized rabbits had significantly higher PG E2 binding capacity (108 +/- 9 fmol/mg protein) than those of nonimmunized rabbits (72 +/- 5 fmol/mg protein). The ligand affinity was not affected by immunization. Neither histamine-stimulated 14C-amino-pyrine uptake of isolated parietal cells as a marker for acid production nor its inhibition by PG E2 were influenced by receptor up-regulation. The increased eicosanoid release can be regarded as an endogenous defense mechanism against increased mucosal vulnerability caused by PG E2 scavenging. The potential role of PG E2 receptor up-regulation in support of this process remains to be established.     

Untersuchungen zur Pollenentwicklung und Pollenschlauchbildung bei höheren Pflanzen

Zusammenfassung In reifen Pollenkörnern der beiden Sommergerstensorten Amsel und Wisa sowie der F₁-Pflanzen, die aus den Sorten-Kreuzungen Impala X Wisa und Union X Wisa hervorgegangen sind, wurde die DNS-Menge der Kerne cytophotometrisch bestimmt. Die Messungen wurden zugleich bei Spermakernen und vegetativen Kernen eines Pollenkorns vorgenommen. Außerdem wurde der DNS-Gehalt von Kernen von Wurzelspitzen-Zellen der Sorten Amsel und Wisa ermittelt.Amsel und Wisa unterscheiden sich signifikant im DNS-Gehalt der Kerne von Wurzelspitzen-Zellen.Die Befunde der Messungen des DNS-Gehalts von vegetativen und Sperma-Kernen bei vier Gerstenformen zeigen, daß zum Zeitpunkt der Anthese die DNS-Replikationsphase bei vegetativen und Sperma-Kernen noch nicht abgeschlossen ist. Der DNS-Gehalt vegetativer Kerne von Wisa ist signifikant niedriger als die entsprechenden Werte der übrigen drei Gerstenformen. Der Verlauf der DNS-Replikation erfolgt bei beiden Spermakernen synchron. Hingegen verläuft die DNS-Replikation bei vegetativen und Sperma-Kernen mit großer Wahrscheinlichkeit nicht gleichsinnig.Im Diskussionsteil wird erstens erläutert, daß bei allen bisher analysierten Pflanzenarten des zwei- oder dreikernigen Pollenkorn-Typs zum Zeitpunkt der Pollenreife die DNS-Replikation der generativen bzw. Sperma-Kerne eingesetzt hat, aber je nach Pflanzenart noch nicht beendet sein muß. Zum gleichen Zeitpunkt der Pollenkornentwicklung kann der vegetative Kern in Abhängigkeit von der Pflanzenart auf dem C-Niveau verharren, eine teilweise oder bereits abgeschlossene DNS-Replikation erfahren haben oder schon teilweise oder ganz degeneriert sein, ohne zuvor eine DNS-Replikation vollzogen zu haben. Zweitens wird in diesem Abschnitt diskutiert, daß mit großer Wahrscheinlichkeit im Ablauf der DNS-Replikation zwischen zwei- und dreikernigen Pollenkorn-Typen keine Unterschiede bestehen. Drittens wird die Hypothese vertreten, daß nur auf einem sehr frühen Stadium die normale Pollenkornentwicklung einschließlich des Ablaufs der DNS-Replikation insbesondere des vegetativen Kerns so abgewandelt werden kann, daß aus Pollenkörnern haploide Pflanzen erzeugt werden können.

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The development of pollen grains and formation of pollen tubes in higher plantsIII. DNA-replication of vegetative and sperm nuclei in mature pollen grains of barley

Summary The DNA-content of vegetative and sperm nuclei in mature pollen grains of the barley varieties Amsel and Wisa and the F₁-plants of crossings of the barley varieties Impala X Wisa and Union X Wisa was determined by cytophotometry. In addition, the DNA-content of nuclei of root tips of Amsel and Wisa was cytophotometrically measured.The DNA contents of the nuclei in root tips of Amsel and Wisa differed significantly.The data obtained from the measurements of the vegetative and sperm nuclei of the four types of barley show that DNA-replication continues in the nuclei of mature pollen grains. The DNA values of vegetative nuclei of Wisa are significantly lower than the values of Amsel and of the F₁ plants. The DNA values of the different nuclei indicate that DNA replication of both types of sperm nuclei is synchronous, whereas it probably is not synchronous in vegetative and sperm nuclei respectively.In the discussion it is pointed out that a survey of the literature shows that in all of the plant species having binucleate or trinucleate pollen DNA replication of generative and of sperm nuclei has started at the time of pollen grain maturation. Depending on the plant species, replication may or may not be completed in the mature pollen grain. At a given stage of development of the pollen grain the vegetative nucleus may be arrested at the C-stage, may have partially or completely finished its DNA replication or may be partially or completely degenerated without prior replication of DNA.In the second part of the discussion it is stated that the course of DNA replication is likely to be similar in binucleate and trinucleate pollen grains. Thirdly, the hypothesis is discussed that in order to get haploid plants from pollen grains, changes in the normal development of the pollen grain and in the pattern of DNA replication must occur at a very early stage of pollen grain development.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Angenommen durch F. Mechelke

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Mein Dank grit Herrn Prof. Dr. F. Mechelke fiir die Anregung zu diesen Untersuchungen sowie fiir die Unterstfitzung und die kritischen Diskussionen w/ihrend ihres Verlaufs und Fr/iulein H. Nagel fiir zuverl/issige technische Hilfe.     

Structural characterization of canine PYY

PYY was purified from canine colonic mucosa by sequential steps of reverse phase HPLC and ion-exchange FPLC. Microsequence, amino acid and mass spectral analyses of the purified peptide and its tryptic fragments were consistent with the structure: YPAKPEAPGEDASPEELSRYYASLRHYLNLVTRQRY-amide. Canine PYY(1-36) has the identical sequence as porcine and rat PYY but differs from human PYY at position 3, with Ala instead of Ile, and position 18, with Ser instead of Asn. A smaller form, PYY(3-36), was also purified and characterized. It may differ in its biological activity from the intact peptide and could act as a partial antagonist or agonist of PYY(1-36).