Notes on the colour of pollen

The spectral reflection of pollen in 67 plant species out of 28 families was measured by means of mass recording of pollen grains. Various types of spectral reflection curves were found, but 75% belonged to two categories: 1. Human-yellow pollen with strong reflection in the green and red, and low reflection in the ultraviolet and blue range of wavelengths. 2. Human-whitish pollen with strong reflection in the green and red and additional reflection of shorter wavelengths. It is shown that it is important to have information about the mode of the visual pollen display — crypsis or colour contrast against the corolla, pollen advertisement, or concealment — and the visual capabilities of the presumed pollinators in order to be able to discuss the signalling function of pollen colours.     

The use of luciferase as a reporter for response of plant cells to the fireblight pathogen Erwinia amylovora

Summary We have introduced the gene encoding luciferase from Photinus pyralis into pear and tobacco cells in order to judge the reaction of plant tissue to damaging conditions such as incubation at high temperature or inoculation with a pathogen. The constitutive expression of the luciferase gene via a strong promoter slowly decreased during propagation of the transformed pear cell line. After various stress treatments the resulting luciferase activity and the ATP content of the plant cells were determined by bioluminescence and found to correspond to each other. Inoculation of transformed pear cells with Erwinia amylovora resulted in a continuous decrease of luciferase activity in contrast to tobacco cells, where the enzyme activity was significantly higher in the first period after inoculation with bacteria compared to the untreated control cells. The pattern of the luciferase activity reflected the slow damage of the host-plant cells by E. amylovora and the elevated metabolism of the non-host cells after inoculation with the pathogen.Abbreviations 2,4-D 2,4-dichloro-phenoxyacetic acid - CaMV Cauliflower mosaic virus - DTT dithiothreitol - EDTA ethylenediaminetetraacetate - FDA fluorescein diacetate - HEPES (hydroxyethyl)piperazine(ethanesulfonic acid) - HR hypersensitive reaction - Tris tris (hydroxymethyl)amino-methane     

Deletion mutagenesis of Tn10 Tet repressor — localization of regions important for dimerization and inducibility in vivo

The gene for the Tn 10 Tet repressor (TetR) was subjected to deletion mutagenesis. Screening for a transdominant operator-binding negative phenotype yielded 10 mutants with internal deletions. Three deletions extend from residue D5 to residues L41, W75, or Q76, respectively, and two contain deletions of the α-helix-turn-α-helix DNA-binding motif. Five deletions range from residue K84 to residues between R87 and K98. Since residues from the N-terminus up to position 98 are not necessary for dimerization, this must take place in the C-terminal half of the protein. Ability to dimerize was probed by introducing ochre non-sense codons (oc) at residues G138, H151, E159, l174, or K202. Koc202 shows wild-type in vivo operator-binding and inducibility by tetracycline indicating that the six C-terminal residues of TetR are not important for activity. Mutants with longer C-terminal truncations are inactive and not transdominant. They show reduced steady-state protein levels and are probably impaired in folding and degraded in vivo . Two mutants (Δ151–166, Δ164–166) with deletions in a region variable in primary structure and length among Tet repressers from different resistance determinants bind tet operator efficiently, but are not inducibie by tetracycline. This result indicates that these residues are not important for dimer formation in the operator-binding form.     

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).     

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.

     

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.