Die „selbstamputation” der eintagsfliegen

Ohne Zusammenfassung     

Influence of light and temperature on daily activity patterns of three Israeli forms of Ptyodactylus (Reptilia: Gekkoninae)*

Activity of the gecko Ptyodactylus hasselquistii was recorded by Aktograph in cyclic light and temperature, continuous darkness or light with constant 30°C or cyclic temperature. The northern P. h. puiseuxi was more diurnal and the southern P. h. cf. hasselquistii more nocturnal than the common P. h. guttatus. Except in constant temperature and continuous light, activity was not randomly distributed throughout the day. The more nocturnal the animal was, the more the temperature played a role in determining its daily activity pattern.     

Cloning, mapping and functional characterization of the hemB gene of Pseudomonas aeruginosa, which encodes a magnesium-dependent 5-aminolevulinic acid dehydratase

During tetrapyrrole biosynthesis 5-aminolevulinic acid dehydratase (ALAD) catalyzes the condensation of two molecules of 5-aminolevulinic acid (ALA) to form one molecule of the pyrrole derivative porphobilinogen. In Escherichia coli, the enzyme is encoded by the gene hemB. The hemB gene was cloned from Pseudomonas aeruginosa by functional complementation of an E. coli hemB mutant. An open reading frame of 1011?bp encoding a protein of 336 amino acids (M_r?=?37?008) was identified. The gene was mapped to SpeI fragment G and DpnI fragment G of the P. aeruginosa chromosome, corresponding to the 10 to 12?min region of the new map or 19 to 22?min interval of the old map. The 5′ end of the hemB mRNA was determined and the ?10 and ?35 regions of a potential σ⁷⁰-dependent promoter were localized. No obvious regulation of the hemB gene by oxygen, nitrate, heme or iron was detected. Alignment of the amino acid sequences deduced from hemB revealed a potential metal-binding site and indicated that the enzyme is Mg²⁺-dependent. P.?aeruginosa hemB was overexpressed in an E. coli hemB mutant using the phage T7 RNA polymerase system and its Mg²⁺-dependent activity was directly demonstrated.     

Conservation of Glycerolated Cultures of Ochromonas danica and O. malhamensis at −10 C

SYNOPSIS. Ochromonas danica in a complex natural growth medium dies at 6–10 C in 4 days; O. malhamensis in ∼2 days. O. danica grown in the medium supplemented with 4.0% glycerol survived at −10±2 C for 35 days, and with 8% glycerol 29 days. O. malhamensis lasted only to 5 days in these media supplemented with 4% glycerol. Ethylene glycol and dimethylsulfoxide were too toxic to be effective. Difficulties in freeze-preservation of certain other phagocytic cells, notably blood granulocytes having comparatively simple flexuous outer membranes, add interest to use of O. danica and O. malhamensis as test organisms for preservation methods, especially in the convenient, inexpensive -10 to -20 C range. Biphasic media with an overlay of distilled water serve for conservation at room temperature. Problems of mutational erosion of these photosynthetic phagotrophs are discussed.