Different tissue distribution and hormonal regulation of messenger RNAs encoding rat insulin-like growth factor-binding proteins-1 and -2.

The insulin-like growth factor-binding proteins IGFBP-1 and IGFBP-2 are low mol wt IGFBPs that are similar in structure. They are not glycosylated and have a homologous amino acid sequence, including the number and position of 18 cysteine residues and a carboxyl-terminal Arg-Gly-Asp sequence that can be recognized by cell adhesion receptors. The present study demonstrates that expression of mRNAs encoding the two BPs differs in some fetal rat tissues and in the livers of adult rats after hypophysectomy, fasting, or streptozotocin-induced diabetes. As determined by Northern blot hybridization using cDNA probes for rat IGFBP-2 or human IGFBP-1, both mRNAs are expressed at high levels in liver of 21-day gestation and 1-day-old rats and at lower levels in 21- and 65-day-old rat liver. Levels of both mRNAs are higher in liver than in other fetal rat tissues. The relative abundance of the two mRNAs in most fetal tissues is similar to that in liver, except that kidney and brain have 8-fold and more than 25-fold higher relative levels of IGFBP-2 mRNA, respectively. IGFBP-2 mRNA is about 10- to 20-fold increased after hypophysectomy or fasting, whereas IGFBP-1 mRNA is relatively unchanged. IGFBP-2 mRNA levels are decreased completely by refeeding fasted rats for 3 days, but only partially decreased by treatment of hypophysectomized rats with GH, cortisone acetate, T4, and testosterone for 4 days.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of cell proliferation by cytosin-arabinoside and its interference with spatial and temporal differentiation patterns in the chick retina

Summary Incubation of chick embryos with 200 nmoles/ egg of cytosine arabinoside (AraC) completely inhibits cell proliferation in the embryo. At an age older than embryonic day 4 (E4) more than 90% of the embryos survive this treatment. The drug induces various malformations; in particular the retina is heavily affected. This simple method offers the possibility to study the effect of a more or less decreased cell production on processes of further differentiation and histogenesis of retinal tissue.The following results are obtained: (1) In spite of the inhibition of cell proliferation in the retina by AraC an abnormally thick basal lamina is found and the expansion of the eye still proceeds, indicating that eye growth is not only dependent on retinal cell numbers. (2) Stereotyped malformations of retinal histogenesis are induced and categorized into three groups: in addition to areas of normal structure cells are found arranged in rosettes and in half-rosettes sometimes linked by areas of undefined transient cell arrangements. The results point to a strong tendency of a severely diminished cell population to form regularly laminated retinal-like structures as long as a minimal ratio of cell types is given. (3) The spatio-temporal appearance of the type of retinal malformation in a given retinal area is dependent on the time of AraC exposure and thus on the degree of differentiation reached at a spatio-temporal spot: Full rosettes develop at earlier, and half-rosettes at later stages of AraC interference. Furthermore, deformities first appear on temporal and ventral sides. Thus, the establishment of these malformations follows and reflects the normal sequence of differentiation within the retina. (4) Cells within rosettes organize in specific layers and start to differentiate normally. This shows that earlier formed cells are not dependent on the influence of factors derived from cells that are formed later for their proper differentiation.Abbreviations AChE acetylcholinesterase - AraC cytosin arabinoside - d'cyt 2 desoxycytidine - FITC-Con A fluorescent concanavalin A - FITC-PNA fluorescent peanut agglutinin - GCL ganglion cell layer - INL inner nuclear layer - IPL inner plexiform layer - LY Lucifer Yellow Recipient of a grant from the Alexander von Humboldt-Stiftung     

Structure and expression of the rat insulin-like growth factor II (rIGF-II) gene. rIGF-II RNAs are transcribed from two promoters

Insulin-like growth factor II (IGF-II) is a mitogenic polypeptide present in rat plasma at high levels during fetal and early postnatal life and is believed to play an important, although as yet undefined, role in fetal development. Both in humans and rats, expression of the IGF-II gene results in the appearance of several mRNA species. In the present study, cDNA and synthetic oligonucleotide probes were used to isolate and characterize the rat IGF-II gene from genomic libraries. The rat IGF-II gene extends over 12 kilobase pairs and contains two 5'-noncoding exons and three protein-coding exons. The two 5' exons represent alternative 5' regions of different mRNA molecules and are expressed from two distinct promoters. The two promoters are transcribed with different efficiencies but exhibit similar tissue-specific expression and regulation with developmental age.     

Zur Dynamik der Entwicklung vonEctopleura dumortieri (Athecatae-Anthomedusae) bis zur Proactinula

Zusammenfassung 1. Mit Hilfe der Laufbild- und Teilbildanalyse von Mikrozeitrafferaufnahmen wird die Dynamik der Entwicklung vonEctopleura dumortieri van Beneden untersucht.2. Medusen vonEctopleura wurden im Sommer 1964 an der Biologischen Anstalt Helgoland über längere Zeit lebend gehalten und zu ausreichender Eiablage gebracht. Die Entwicklung konnte in lückenloser Serie von der ersten Teilung bis zum Sternchen-Stadium unter Zeitraffung aufgenommen werden. Es entwickelten sich 40 % der abgelegten Eier normal.3. Trotz einseitig vordringender schneidender Furchen ist der Furchungstypus als total-äqual zu bezeichnen.4. Vor der völligen Durchschnürung eines Blastomer schneiden bereits die Furchen der nächsten und übernächsten Teilung ein.5. Der Grund der schneidenden Furche erscheint auf dem optischen Querschnitt tropfenförmig; die Furchenränder klaffen auf dem Querschnitt durch die Furche (Abstand zwischen den Trennungsflächen). Die schneidende Kante weist zuerst nur geringe Länge auf, nimmt beim Vordringen bis zum Zelläquator zu und dann wieder ab entsprechend der Gestalt der sich teilenden Furchungszelle.6. Nach den vier ersten Teilungen sind die Blastomere in einer Reihe angeordnet.7. Die Tendenz zur aktiven Aneinanderpressung der Blastomere in der Interphase ist in abgewandelter Form noch vorhanden; sie wird zum Teil durch den zur Medianlinie gekrümmten Verlauf der Furchen gekennzeichnet.8. Bereits das 8-Zellen-Stadium wölbt sich in der Mitte auf (50 Minuten nach Entwicklungsbeginn). In Korrelation zu dem rhythmischen Teilungsablauf folgen Krümmungen und Streckungen des Keimes gesetzmäßig aufeinander.9. Die 8 vierten Furchen schnüren den langgestreckten Keim nicht mehr durch, da unterdessen die ersten Querteilungen an den Enden eingesetzt haben.10. Auf die höchste Aufwölbung des Keimes (1 Stunde 16 Minuten seit Entwicklungsbeginn) folgt eine sehr langsame Verkürzung. Drei Stunden nach der 1. Teilung ist die Gestalt eines Ellipsoid angenommen.11. Erst nach weiteren 3 Stunden und 20 Minuten (7 Stunden 13 Minuten seit der ersten Teilung) beginnt die Ausbreitung des Keimes in der Fläche. Die ersten Anlagen der Aboraltentakel (meist 6) werden erkennbar.12. Unter Zeitraffung werden zwei verschiedene strömungsähnliche Bewegungsabläufe im Cytoplasma während des Einschneidens der Furchen sichtbar: (a) Eine Verdrängungsbewegung infolge des Vordringens der schneidenden Furchen (passive Bewegung). (b) Eine hin- und hergehende Massenausgleichbewegung, die als aktiv-passive Bewegung aufzufassen ist.13. Aus der Teilbild-Analyse von Zeitraffer-Aufnahmen gewonnene kinematische Diagramme (Normentafeln) geben einen exakten Überblick über das gesamte dynamische Geschehen während derEctopleura-Entwicklung.

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On the dynamics of development inectopleura dumortieri (athecatae-anthomedusae) to proactinula. Film projection and single-frame analyses of micro-time lapse movies

Employing the technique of micro-time lapse movies (analyses of projection and single frames) the dynamics of the development ofEctopleura dumortieri van Beneden is thoroughly investigated until attainment of the proactinula (starlet stage). Characteristic are sharp cleavage furrows (schneidende Furchen); the blastomeres formed are arranged along a single line. The long, stretched embryo bends and stretches in rhythms caused by cell divisions. Cross divisions start relatively late; they begin at the front and hind end of the embryo. It follows a re-organization, resulting in an elipsoid shape; this procedure takes several hours. Following flattening and formation of the tentacle-analgen, the rather strange starlet stage is reached about 10 1/2 hours after the first division. Special attention is given to the dynamics of the incision of cleavage furrows and to the more or less passive motions in the cytoplasm correlated herewith. The kinetic diagrams produced by the partial-picture analysis of time lapse movies give an exact survey of the whole development; they have the value of Normentafeln (norm tables).

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Wir widmen diese Untersuchung Herrn Prof. Dr.Friedrich Seidel zum 70. Geburtstag.     

The type I insulin-like growth factor receptor is a motility receptor in human melanoma cells

Insulin-like growth factors I and II (IGF-I and II) and insulin are chemotactic agents for the human melanoma cell line A2058. As shown in this report, the motility receptor mediating this response is the heterodimeric type I IGF receptor. These three factors are able to compete with 125I-labeled IGF-I for binding to the cell surface with IC50 values equal to approximately 2 (IGF-I), approximately 150 (IGF-II), and approximately 300 nM (insulin). Cross-linking of 125I-IGF-I to the cell surface with disuccinimidyl suberate followed by analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography reveals a 130-kDa protein (reduced) consistent with the alpha component of a type I receptor and a 38-kDa protein which does not bind insulin, and thus could be another IGF-I cell surface binding protein. The anti-IGF-I receptor monoclonal antibody (alpha IR-3) also competes with labeled IGF-I in binding experiments. In contrast, a control monoclonal antibody, matched to alpha IR-3 with respect to IgG subclass, has no significant effect on IGF-I binding. While alpha IR-3 inhibits the motility induced by IGF-I, IGF-II, and insulin, pertussis toxin (0.01-1.0 micrograms/ml) has no significant effect on the motility induced by the insulin-like growth factors or insulin on this cell line. Therefore, the type I IGF receptor appears to mediate a highly potent pertussis toxin-insensitive motility response to IGF-I, IGF-II, and insulin. In contrast, motility induced by the autocrine motility factor, a cytokine produced by the A2058 cells, is not affected by alpha IR-3 but is extremely sensitive to pertussis toxin. When mixtures of autocrine motility factor and IGF-I are employed to induce chemotaxis, the resulting motility is greater than that induced by either agent alone. These data indicate that motility in this melanoma cell line can be initiated through multiple receptors that stimulate the cells by separate transduction pathways. This capability to respond to multiple stimuli could enhance the metastatic potential.     

Untersuchungen über das bewegungsverhalten von Trichoplax adhaerens F. E. Schulze (Zeittransformation: Zeitraffung)

Ohne Zusammenfassung     

Phylogeny reconstruction for protein sequences based on amino acid properties

This paper presents an essentially new method used to construct phylogenetic trees from related amino acid sequences. The method is based on a new distance measure which describes sequence relationships by means of typical steric and physicochemical properties of the amino acids and is advantageous in some essential points. The method was applied to different sets of protein sequences and the results were compared with other well-established methods.