Conditionality of phase resetting by inhibitors of 80 S translation inGonyaulax polyedra

Summary Gonyaulax polyedra was subjected to a cold treatment of 18 h at 10 °C leading to arrhythmicity. Subsequently, the circadian rhythm of bioluminescence was investigated at the permissive temperature of 20 °C. 1-h pulses of 10 M cycloheximide or 2 M anisomycin, when given after the temperature step-up, resulted only in a very weak resetting of the circadian oscillator, in marked contrast to the behaviour of cells kept continuously in oscillatory conditions at 20 °C. The extremely reduced sensitivity to 80 S inhibition was characteristic for the first cycle after the temperature step-up, whereas cells treated with cycloheximide in the second cycle after re-initiation of rhythmicity showed a gradual recovery of resettability, though the phase response curve was still atypical; treatment in the 3rd cycle after step-up led to a relatively normal phase response curve. The observed insensitivity in the 1st cycle was neither a consequence of insufficient drug action, nor of a transient non-oscillatory behaviour after temperature step-up. Already in the first hours after transfer to 20 °C, 80 S translation was strongly suppressed by cycloheximide, and the cells were also efficiently reset by changes of the light-dark zeitgeber. Resettability of the circadian oscillator by 80 S inhibitors is, therefore, conditional.Abbreviations Ani anisomycin - Chx cycloheximide - CT circadian time - LD light-dark cycle - LL constant light - TCA trichloroacetic acid This work was supported by the Deutsche Forschungsgemeinschaft     

Polyamine metabolism in hants : Arginine and omithine decarboxylase activity in ripeningTrlticum durum seeds

The pattern of the activity of arginine decarboxylase (ADC) and omithine decarboxylase (ODC) involved in polyamine synthesis in ripening wheat seeds was examined. The aim was to study the polyamines and the activity of the two enzymes in correlation with the growth processes occurring in the developing wheat seeds. The results obtained showed a very different pattern of polyamine content in the two organs of caryopsis, and that the two enzymes in the embryos have a higher activity than in the endosperms. Moreover, while in the embryos the ADC exhibits higher activity than the ODC, in the endosperms the activity of ODC is about similar to that of ADC. This pattern is discussed in relation to the different histological characteristics of embryo and endosperm tissues during seed development.     

Phenotypic and genetic differentiation of human populations with respect to morphologic and psychophysiological traits

Four groups of human characters (mendelian markers, anthropometry, neurodynamics and psychodynamics) were studied in eight human populations characterized by different degrees of isolation and different ethnic backgrounds, and located in different ecological conditions. The populations examined were proved to display phenotypic and genetic differentiation for the studied groups of characters which were compared with linguistic and geographical distances. The role of genetic factors and that of environmental factors was shown to diminish and to increase, respectively, as the degree of complexity of expression of the group of characters under study (from anthropometry to psychodynamics) goes up.     

The genes coding for human pro alpha 1(IV) collagen and pro alpha 2(IV) collagen are both located at the end of the long arm of chromosome 13.

We have isolated and characterized a cDNA clone containing DNA sequences coding for the noncollagenous carboxy-terminal domain of human pro alpha 2(IV) collagen. Using this cDNA clone in both Southern blot analysis of DNA isolated from human-mouse somatic-cell hybrids and in situ hybridization of normal human metaphase chromosomes, we have demonstrated that the gene coding for human pro alpha 2(IV) collagen is located at 13q33----34, in the same position on chromosome 13 as the pro alpha 1(IV) collagen gene.     

Abnormal electrophoretic mobility of spectrin tetramers in hereditary elliptocytosis

Summary Hereditary elliptocytosis (HE) is a genetically determined disorder of the red cell membrane. The main protein which composes the proteinaceous skeleton of the membrane is an elongated molecule named spectrin which is a heterodimer composed of two chains, and . In the membrane spectrin dimers are associated head-to-head to form tetrameric structures. We and other authors have reported that spectrin studied from many HE patients exhibited a dimer self-association defect (type I HE). A mutation in the head of the spectrin chain was mostly found in type I HE. We have previously described one of the three known spectrin pathological variants shown on mild tryptic digest pattern. This variant was characterized by the appearance of an abnormal 65,000-dalton peptide (Sp ^I/65). Using nondenaturating gel electrophoresis, we describe in this paper a triplicated pattern of the spectrin tetramer bands which is found in heterozygous HE cases displaying the 65,000-dalton variant. Study of a homozygous case allowed us to characterize the electrophoretic mobility of the abnormal symmetrical spectrin tetramer (₂ ^I/65-₂) and to study the correlation between the fraction of this abnormal symmetrical tetramer found in heterozygous patients and the amount of the 65,000-dalton peptide observed in spectrin tryptic digests.     

HIV envelope proteins are bound by human epidermal Langerhans cells by a binding site which differs from the site on the CD4 molecule, and are internalized by receptor endocytosis

Langerhans cells (LC) are epidermal dendritic cells which express several surface antigens among them the CD4 antigens. We investigated the fate of HIV envelope glycoproteins (gp 120 and gp 160) incubated with healthy human trypsinized LC in suspension. After trypsin treatment only the epitope for OKT4 appeared to be resistant. In absence of antigenic sites identified by OKT4A, Leu 3a or BL4, LC fixed and internalized gp 120 or gp 160 recombinant HIV proteins. This finding support the hypothesis that there exists at the surface of LC a second molecule which may act as a HIV receptor.     

Characterization of a highly structured domain in Tbp2 from Neisseria meningitidis involved in binding to human transferrin.

The binding of iron-loaded human transferrin at the surface of Neisseria meningitidis is mediated by two polypeptides, Tbp1 and Tbp2. Predicted Tbp amino acid sequences from N. meningitidis strains are highly divergent. This variability is particularly pronounced throughout the Tbp2 polypeptide. In this study, a highly structured and extremely stable Tbp2 domain of about 270 to 290 amino acids which is involved in the binding to transferrin and whose position is well conserved has been characterized. The conservation of such a remarkable structure in a very divergent protein domain (there is only 43% amino acid identity within this region) suggests that is plays an essential biological role and raises a number of questions regarding tbp2 evolution.     

Effect of serum,fibronectin, and laminin on adhesion of rabbit intestinal epithelial cells in culture

Rabbit intestinal epithelial cells, obtained after a limited hyaluronidase digestion, were incubated in medium with or without calf serum, on bacteriological plastic dishes. The dishes, either plain or coated with an air-dried type I collagen film, were pretreated with medium alone or with medium containing purified laminin or purified fibronectin. Cells did not attach in significant numbers to untreated bacteriological plastic, even in the presence of serum. Cells did attach to collagen-coated dishes, and were judged viable on the basis of their incorporation of radiolabeled leucine into cell protein. Cell adhesion to the collagen substrate increased in proportion to the concentration of serum in the medium, with maximal attachment at 5% serum or greater. Pretreatment of plain or collagen-coated dishes with increasing amounts of fibronectin enhanced cell adhesion in a concentration-dependent manner. Either serum, or fibronectin-free serum in the medium enhanced cell attachment to substrates pretreated with cither fibronectin or laminin. Thus, intestinal epithelial cells appear to possess surface receptors for both laminin and fibronectin. The evidence further suggests that calf serum may contain factors, other than fibronectin, capable of enhancing intestinal epithelial cell attachment to collagen substrates.     

Serologische Untersuchungen zur Gliederung derBrassicaceae

The serological investigations support the opinion ofJanchen (1942) to combine the generaBunias, Isatis, andSisymbrium in the tribeSisymbrieae; Cheiranthus, Erysimum, andMatthiola in the tribeHesperideae; andBrassica, Crambe, Sinapis, andSuccowia in the tribeBrassiceae. They further underline the central position of theSisymbrieae and the isolated position of theHeliophileae. In accordance withEigner (1973) theBrassiceae are placed closer to theSisymbrieae than inJanchen; the same holds for thePringleeae. No serological justification could be found to uniteArabis andBarbarea in the tribeArabideae, andAlyssum andLunaria in theAlysseae. From the antigen-systems used among the representatives ofJanchen's Lepidieae the generaLepidium andNeslia show remarkable correspondence both toCamelina andThlaspi, but not toCochlearia which appears distant fromCamelina andThlaspi also.

Teil 1/Part 1.