N-banding in polytene chromosomes of Chironomus and Drosophila

The N-banding patterns of the polytene chromosomes of Drosophila melanogaster, Chironomus melanotus, Ch. th. thummi and Ch. th. thummi x Ch. th. piger were studied. In Chironomus the polytene N-banding patterns correspond to the polytene puffing patterns. This is revealed by comparison of the puffing and N-banding patterns of identical chromosomes. Size and staining intensity of the N-bands reflect the size of the puffs as shown by puff induction. There is no evidence that the N-bands are also located in Chironomus heterochromatin or are restricted to the nucleolar organizer regions. In Drosophila the -heterochromatin is strongly N-positive, whereas the -heterochromatin, as well as the Chironomus heterochromatin is not N-banded. Contrary to Chironomus, the puffs in Drosophila polytene chromosomes do not give rise selectively to well stained N-bands. — The N-banding method is interpreted to stain specifically non-histone protein which is (1) accumulated in genetically active chromosome regions and (2) present in a specific type of heterochromatin (-heterochromatin of Drosophila).     

Calliphorin,a major protein of the blowfly: Correlation between the amount of protein,its biosynthesis,and the titer of translatable calliphorin-mRNA during development

The amount of calliphorin, its biosynthesis, and the levels of translatable calliphorin-mRNA have been determined during the postembryonic development of Calliphora vicina R.-D. The amount of calliphorin increases in early third-instar larvae, reaching maximal levels in 6-day-old animals. It continuously decreases during late larval and pupal development to approximately one-half of the maximal levels and abruptly sinks during eclosion. The biosynthesis of calliphorin takes place only in 3- to 5-day-old larvae. Poly(A)⁺-RNA has been translated into proteins in a wheat germ cell-free system. Calliphorin-mRNA can be detected in 3- to 7-day-old larvae; maximal concentrations are observed in 4- and 5-day-old animals. No calliphorin-mRNA can be detected in prepupae, pupae, or imagos. The biosynthesis of calliphorin in blowfly larvae stops before a decrease of translatable calliphorin-mRNA is observed. This finding raises the question of the mechanism of in vivo inactivation of this specific mRNA.     

Imitieren Buchfinken(Fringilla coelebs) auf Bornholm den Alarmruf des Sprossers(Luscinia luscinia)?

Zusammenfassung 1979 und 1980 wurde in Ostbornholm ein einheitlicher Regenrufdialekt des Buchfinken gefunden, der dem Alarmruf des Sprossers sehr ähnlich klingt. Auch im Sonagramm zeigen sich morphologische Entsprechungen. Nach demMann-Whitney-Test sind die Mittelwerte der Frequenzen und Impulsdauer hochsignifikant verschieden, was jedoch im felde ohne direkten Vergleich nicht wahrnehmbar ist. Trotz der Differenzen wird Fremdimitaton für sehr wahrscheinlich gehalten, Zufallskonvergenz jedoch nicht ganz ausgeschlossen.

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A case of vocal appropriation in the Chaffinch to the alarm-call of the Thrush Nightingale at Bornholm?

Summary In 1979 and 1980 in the east of Bornholm (Baltic Sea, Danmark), an uniform dialect of the rain-call was found in the Chaffinch, which resembles the alarm call of the Thrush Nightingale(Luscinia luscinia). The sonagrams of the two calls are very similar in structure. The frequency and duration differ significantly. In the field, however, one can hardly take apart the two calls without direct comparison. Despite these differences, it is speculated, that the rain-call is an imitation, but convergence by chance can not be excluded.

     

Proteinchemical characterization of three structurally distinct domains along the protofilament unit of desmin 10 nm filaments

Limited chymotryptic cleavage of soluble chicken gizzard desmin protofilaments allows the characterization of three structurally distinct domains. A surface-exposed very basic amino-terminal region (the headpiece) with an amino acid sequence excluding a-helical organization (7.5 kd) is separated from the perhaps globular carboxy-terminal 48 residues (the tailpiece) by a distinctly different middle domain of approximately 330 residues. This 38 kd domain is very rich in α-helix (at least 83%), and electron microscopy reveals a thin rod with a length of 500 ± 50 Å. Amino acid sequence data also show that the rod domain is interrupted by a nonhelical portion. An a-helical array is able to form a coiled-coil spanning the carboxy-terminal half of the 38 kd domain. The a-type diffraction pattern of 10 nm filaments arises from a coiled-coil conformation displayed through most but not all of the middle domain of the protofilaments.     

Kinetics of the appearance of mRNA for light-harvesting chlorophyll a/b protein in polysomes of barley

Polysomes from dark-grown and illuminated barley seedlings were translated in cell-free systems. The translation products reacting with the antibody against the light-harvesting chlorophyll a/b protein (LHCP) were analyzed by polyacrylamide gel electrophoresis. It was found that, in addition to the precursor protein of LHCP, a product was obtained that co-migrated with the mature protein. Furthermore, the results show that the light-induced proly(A)RNA for LHCP is integrated into the polysomal complex without delay, indicating that the integration of LHCP into the membrane is controlled at a higher level of gene expression.