Studies on polytene chromosomes of Smittia parthenogenetica (Chironomidae,Diptera)

In polytene chromosome II of Smittia parthenogenetica a heterochromatin insertion has been studied which is derived from a germ-line limited chromosome section (Bauer, 1970). This insertion is C-banding positive, late replicating, inactive in RNA synthesis, fluoresces brightly with quinacrine and is polytenized. After N-banding a major part of the heterochromatin insertion is N-banding negative, whereas in the centre of the insertion a N-banding positive body is present. The properties of the N-positive and N-negative parts of the inserted heterochromatin section are compared with the properties of the heterochromatin of Chironomus melanotus and Drosophila melanogaster. It is concluded that the heterochromatin insertion consists of two different heterochromatin types and it is discussed whether the N-banding positive part within the insertion represents a heterochromatin type which is underreplicated during polytenization.Dedicated to Professor Dr. Hans Bauer in honour of his 75th birthday on September 27, 1979     

Monophagie und „subsequent evolution“ in ihrer theoretischen Bedeutung für die Insekt-Pflanze-Beziehung

The term monophagy is applied to animal species which are linked to a single plant-reprospecies at least during part of their ontogeny. Aspects of subsequent evolution of monophagous animal species and their plant host species are discussed.     

Modifying effects of ultraviolet irradiation on the development of abnormal body patterns in centrifuged insect embryos (Smittia sp., Chironomidae,Diptera)

In Smittia and other chironomid embryos, both anterior and posterior egg halves can give rise to either anterior or posterior segments. Upon various types of experimental interference, eggs may develop one of four basic body patterns: normal embryos, double cephalons, double abdomens, or inverted embryos. From a previous model of anteroposterior determination, we derive four sets of predictions for the results of combined ultraviolet irradiation and centrifugation experiments. While most of the actual results are in agreement with the predictions, some are not. Most of the discrepancies are resolved in a modified version of the model. According to the new model, anterior and posterior egg halves contain both anterior and posterior cytoplasmic determinants. These are thought to be mutually repressive, and to control an overall determination for either anterior or posterior development. Centrifugation and ultraviolet irradiation appear to affect the relative strength of anterior determinants in one or both of the egg halves, thus modifying the probabilities for the four basic body patterns to develop. Different frequencies of these patterns, which have been obtained after similar experimental treatment of different chironomid species, can be ascribed to species-specific variation in the ultraviolet sensitivity of anterior and posterior determinants.     

Synthesis of type IV collagen and laminin in cultures of skeletal muscle cells and their assembly on the surface of myotubes

The synthesis of two components of the basal lamina, laminin and type IV collagen, and their extracellular deposition on the surface of myotubes was studied in cultures of embryonic mouse and quail skeletal muscle cells and in the rat myoblast cell line L6. Production of type IV collagen and laminin by myoblasts and muscle fibroblasts was demonstrated by incorporation of radioactive amino acids into proteins and by immunoprecipitation with specific antibodies and electrophoretic analysis of labeled proteins. Immunofluorescence staining experiments revealed strong intracellular reactions with antibodies to laminin and type IV collagen in mononucleated myogenic and fibrogenic cells. Cells of fibroblast-like morphology showed a more intense staining than bipolar, spindle-shaped cells which perhaps represented postmitotic myoblasts. Myotubes did not show detectable intracellular staining. The formation of a basal lamina on myotubes was indicated by the deposition of laminin and type IV collagen on the surface of myotubes as viewed by immunofluorescence examination of unfixed cells. Staining for extracellular laminin was stronger in mass cultures than in myogenic clones, suggesting that secretion and deposition of components of the basal lamina on the myotube surface are complex processes which may involve cooperation between myogenic and fibrogenic cells.     

Engineering of lactose metabolism inE. coli by introducing β-galactosidase/galactokinase fusion enzymes

Summary A series of plasmids encoding -galactosidase/galactokinase fusion proteins with connecting linkers of different lengths and properties separating the enzyme moieties were made.E. coli cells harbouring the genes for these bifunctional enzymes were grown on minimal media with lactose as carbon source in order to asses possible metabolic effects. Differences in growth rates were observed when the cells contained a scavenger enzyme, galactose dehydrogenase, competing with galactokinase for the galactose formed by -galactosidase.E. coli cells coding for fusion proteins with long linkers then reflected markedly slower growth rates.     

Regeneration of NADH with immobilized systems of alanine dehydrogenase and hydrogen dehydrogenase

Summary An alternative approach to the regeneration of coenzymes using immobilized hydrogen dehydrogenase (hydrogenase) is described. Hydrogenase isolated from Alcaligenes Eutrophus was immobilized to porous glass particles and used in combination with alanine dehydrogenase for formation of alanine, while the NADH consumed was regenerated by molecular hydrogen. Different physical arrangements of the two enzymes were compared. Alanine was conveniently assayed with a specially designed enzyme thermistor method.     

Involvement of smooth and coated vesicles in the function of the contractile vacuole complex of some cryptophycean flagellates

The contractile vacuole complex of cryptophycean flagellates comprises the contractile vacuole, a pore and a vesicular spongiome. A minority of spongiome vesicles bear a 15-nm coat on the cytoplasmic surface of the membrane. The coat superficially resembles a clathrin coat. The majority of vesicles are smooth surfaced. Both types of vesicles are found at the same time. Smooth vesicles can be seen in profile suggesting vesicle-vesicle and vesicle-vacuole fusion. It is suggested that smooth vesicles are involved in the segregation of fluid from the cytoplasm and in filling the vacuole. Coated elements exist only as independent vesicles and as coated pits in the contractile vacuole membrane. There is no evidence of fusion of coated vesicles. It is suggested that coated vesicles function to retrieve specific membrane components from the contractile vacuole.     

Versuche zum angenommenen Kontrastverlust im Gesang der Blaumeise (Parus caeruleus) auf Teneriffa

Zusammenfassung Der Gesang von Blaumeisen-Populationen in Mitteleuropa, Spanien, Marokko und auf Teneriffa wurde miteinander verglichen (Abb. 1). In Süddeutschland und auf Teneriffa wurden Klang-Attrappen-Versuche durchgeführt.1. Der Blaumeisen-Gesang ist in Marokko und auf Teneriffa sehr ähnlich. Er unterscheidet sich vom Blaumeisengesang in Europa (Mitteleuropa und Spanien) in folgenden Eigenschaften (2.–4.):2. Ihm fehlen phrasierte Strophen (Abb. 2 a–c, e, 3, 4 a, b, f, g), also Strophen, in denen dasselbe Element mindestens viermal nacheinander wiederholt wird.3. Er enthält mehr verschiedene Elemente (Abb. 5, 7).4. Die interindividuelle Variation ist größer (Abb. 6, 7).5. Die Unterschiede zwischen dem Blaumeisen-Gesang in Europa und auf Teneriffa lassen sich nicht mit der Kontrast-Betonungs- und der Kontrast-Verlust-Hypothese nachLack &Southern (1949) undMarler (1960) erklären. Die Lernentzugs-Hypothese erklärt sie besser.6. Die Blaumeisen von Teneriffa und Marokko sind sehr nahe miteinander verwandt, aber vermutlich sind sie von den europäischen Blaumeisen artlich nicht getrennt.

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The song of the Blue Tit (Parus caeruleus) on Tenerife: Experiments on a presumed loss of contrast

Summary Songs of Blue Tit populations from Central Europe, Spain, Morocco and Tenerife (fig. 1) were compared. Playback experiments were made in South Germany and on Tenerife.1. Blue Tit songs from Morocco and Tenerife are very similar. They differ from songs of Blue Tits in Europe (Central Europe and Spain) in the following characteristics (2–4):2. Lack of phrased songs (fig. 2 a–c, e, 3, 4 a, b, f, g), i. e. songs with the same notes repeated successively at least four times.3. A greater number of different types of notes (fig. 5, 7).4. Greater interindividual variation (fig. 6, 7).5. Differences between Blue Tit song from Europe and from Tenerife cannot be explained by the hypothesis of contrast reinforcement and loss of contrast, according toLack &Southern (1949) andMarler (1960). The withdrawal of learning hypothesis is a better explanation.6. Blue Tits on Tenerife and Morocco are very closely related to each other but are probably not a different species from the Blue Tits of Europe.

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Für die Übersetzung danken wir FrauR. Jellis und HerrnP. Lundberg.