Structure elecidation of mammalian TCDD-metabolites

Summary Thin layer and gas chromatographic examination of the bile of dogs which were given tritium-labelled TCDD revealed the presence of several polar biotransformation products. The structure of 5 phenolic metabolites was elecidated by combined gas chromatography-mass spectrometry. A metabolic breakdown scheme for TCDD in the dog is proposed.     

Similar pattern of fine structure in the basement lamella of the skin and the external sheath of the notochord inXenopus larvae

Zusammenfassung Auf Grund von elektronenmikroskopischen Beobachtungen wird nachgewiesen, dass die Basalmembran der Epidermis und die äussere Chordascheide im Schwanz vonXenopuslarven eine übereinstimmende Feinstruktur besitzen; sie ist gekennzeichnet durch orthogonal angeordnete Kollagenfibrillen.

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Supported by the Swiss National Science Foundation for the Promotion of Scientific Research.     

Application de l'analyse discriminante à l'étude des différences anthropométriques selon les groupes sanguins du système ABO

Summary Anthropological measurements on 193 Swiss recruits have been studied using discriminatory analysis. Out of the 9 characters measured on each individual, 3 were chosen to ascertain whether differences between the ABO blood groups exist. Discriminatory analysis gives a simultaneous evaluation of the differences of the 3 measurements. They are found not to be significant.     

Nachweis der Selbst-Erregung der circadianen Periodizität bei Carabiden (Coleoptera Ins.)

Summary Most of the active individuals ofCarabus cancellatus (Coleoptera) investigated were synchronized by zeitgeber-lengths of 8/8 10/10 or 16/16 h. On the other hand, a smaller number of beetles lost the periodicities of these Zeitgebers and showed a circadian activity rhythm. According to these experiments, the existence of a self-sustained circadian oscillation in carabid beetles is demonstrated. As we believe, a special numerical method of computing the length of activity periodicities was used for the first time.     

Untersuchungen zur Neurosekretion beiAcheta domesticus L

Summary PAF-positive material, which is found in the brain and stomatogastric system of adultAcheta domesticus, can in addition be demonstrated in the Nervus corporis allati II. In the suboesophageal ganglion and the ventral nerve cord 3 different types of neurosecretory cells are described.     

Functional architecture of an intracellular membrane t-SNARE

Lipid bilayer fusion is mediated by SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) located on the vesicle membrane (v-SNAREs) and the target membrane (t-SNAREs). The assembled v-SNARE/t-SNARE complex consists of a bundle of four helices, of which one is supplied by the v-SNARE and the other three by the t-SNARE. For t-SNAREs on the plasma membrane, the protein syntaxin supplies one helix and a SNAP-25 protein contributes the other two. Although there are numerous homologues of syntaxin on intracellular membranes, there are only two SNAP-25-related proteins in yeast, Sec9 and Spo20, both of which are localized to the plasma membrane and function in secretion and sporulation, respectively. What replaces SNAP-25 in t-SNAREs of intracellular membranes? Here we show that an intracellular t-SNARE is built from a 'heavy chain' homologous to syntaxin and two separate non-syntaxin 'light chains'. SNAP-25 may thus be the exception rather than the rule, having been derived from genes that encoded separate light chains that fused during evolution to produce a single gene encoding one protein with two helices.     

Crystallographic studies on the activity of glycogen phosphorylase b

High resolution studies on the crystal structure of glycogen phosphorylase b have identified the catalytic site to which the substrate glucose-1-phosphate binds strongly with some local conformational changes. The site is situated 8 A (phosphate-to-phosphate distance) from pyridoxal phosphate, an essential cofactor of all glycogen phosphorylases. The catalytic site is 33 A from the site in the N-terminal portion of the molecule to which adenine nucleotides bind. In contrast to phosphorylase a (the active form of the enzyme which is phosphorylated at Ser 14), the positions of the first 19 residues of phosphorylase b are not well defined.     

Amino-terminal fragments of Escherichia coli lac repressor bind to DNA.

The N-terminal fragments (residues 1-51 and 1-59) obtained by selective tryptic cleavage of native lac repressor retain the ability to bind DNA. These fragments (headpieces) are monomeric and form complexes which resemble those of tetrameric repressor with non-operator DNA. But, they do not show the high specificity of repressor for operator sequences. The DNA binding has been demonstrated by filter-binding assay as well as in solution using absorption, circular dichroism, and fluorescence measurements.