Fusion polypeptides in gene cloning: Potential problems due to conformational alterations at the junction

Summary Many eukaryotic genes are cloned in bacterial hosts as fusion polypeptides. Prediction of the secondary structures for some common prokaryotic fusion polypeptides shows that many junction sites correspond to important secondary structures. It is suggested that such structures could affect (hinder, etc.) the conformation or drive the folding of the neighboring eukaryotic counterparts. Thus the prokaryotic junction should be better performed, in random coil regions, or short fusion prokaryotic polypeptides should be sued.1 October 1986     

Rodent preimplantation stages: Mounting ’in toto’ and alterations due to anisotonic solutions

Zusammenfassung Anisotonische Lösungen verursachen bei der Durchführung histochemischer Reaktionen an freien Eiern von Nagern Artefakte. Es wird eine einfache Montagetechnik nach Durchführung der Reaktion beschrieben, bei der intrazelluläre Veränderungen vermieden und weder Form noch Grösse der Eier durch Anisotonie verändert werden. Die Technik erlaubt jede Art von Fixation und jede Reaktion, solange das Reaktionsprodukt wasserunlöslich ist.     

Occludin binds to the SH3-hinge-GuK unit of zonula occludens protein 1: potential mechanism of tight junction regulation

The interaction between tight junction proteins occludin and zona occludens protein 1 (ZO-1) was clarified. The sequence cc1 within the hinge region of ZO-1, connecting its SH3 and GuK domains, was identified as a new association site for the occludin C-terminus, core binding area GLRSSKRNLRKSR (mouse ZO-1^606-618). Occludin also bound to the sequence H2 within GuK, core area HKLRKNNH (ZO-1^759-766). In occludin, the binding core was ELSRLDKELDDYREESEEY (mouse occludin^455-473). Helicity of the sequences was suggested by circular dichroism. Because basic residues in ZO-1, acidic residues in occludin (underlined), coiled-coil helix-forming leucine heptad motifs (bold) in occludin and, probably, in cc1 were essential, we conclude that interactions were both helical and ionic. Moreover, the GuK domain bound other GuK molecules, suggesting oligomerization of ZO-1. Generally, the assumption is supported that the SH3-hinge-GuK region represents a functional and regulatory unit in ZO-1 forming a multiprotein tight junction complex with occludin.Received 12 January 2004; received after revision 23 February 2004; accepted 31 March 2004     

In situ aging of auricular chondrocytes is not due to the exhaustion of their replicative potential

Summary Multiplication of chondrocytes during growth of rabbit auricular cartilage was estimated on the basis of total DNA determination and compared with the population doubling level reached by these chondrocytes in vitro. The results indicate that the in situ aging of auricular chondrocytes is caused by factors other than the intrinsic depletion of their growth potential.     

Heterogeneity of molecular markers in chronic myelomonocytic leukemia: a disease associated with several gene alterations

The relatively homogenous clinical features and poor prognosis of chronic myelomonocytic leukemia (CMML) are associated with a molecular heterogeneity, with various mutations impacting several convergent pathways. Due to the restricted understanding of the mechanism involved in leukemogenesis, CMML still appears as a diagnostic and therapeutic undertaking, and poor prognosis of leukemia. Contrary to chronic myelogenous leukemia, BCR-ABL1-positive, cytogenetic, and molecular abnormalities of CMML are not specific and not pathognomonic, confirming the different levels of heterogeneity of this disease. Various mutations can be associated with a common phenotype not distinct at the clinical level, further demonstrating that molecular probings are needed for choosing individual targeted therapies.     

Tissue specific biochemical alterations prior to spinning in the eri-silkworm,Philosamia ricini

Summary Silkgland, fatbody, hemolymph and midgut of eri-silkworm present tissue specific turnover in their biochemical correlates in preparation for spinning of the cocoon which is followed by larval-pupal transformation.Acknowledgment. The authors are thankful to Dr R. N. Singh, Principal, for providing the necessary facilities, to Dr A. B. Das, Zoology Dept. Visvabharti University for valuable suggestions and to Indian Council of Agricultural Research, New Delhi, India, for financial assistance.     

Decision-making at the surface of the intact or barrier disrupted skin: potential applications for vaccination or therapy

The skin is a highly accessible organ and constitutes an active immunological site. Both these properties make this surface an attractive route for what promises to be a cost-effective, simple, practical and needle-free delivery of vaccines and immunomodulators. Less obvious is the fact that the state of the skin barrier can influence quantitative and qualitative aspects of antigen-specific immune responses. The everyday decision-making at the skin epithelium concerns the choice between the induction of an immune response and the establishment of a state of non-responsiveness (tolerance). This decision is influenced by various factors such as the dose, the route (intact vs barrier-disrupted skin), the cytokine microenvironment and the nature of the antigenic stimulus. By increasing our understanding of how immune responses are regulated in the epidermis we can envisage the development of immunisation protocols aimed at eliciting a protective immune response or inducing tolerance, with direct applications to preventive or therapeutic vaccination, respectively.Received 29 November 2004; received after revision 2 February 2005; accepted 22 February 2005     

Expression of nerve growth factor-like polypeptides and immunoreactivity related to the two types of neurotrophin receptors in earthworm tissues

Nerve growth factor (NGF) belongs by sequence homology to the neurotrophins, a family of proteins binding the same p75 receptor and closely related members of the Trk family of receptor tyrosine kinases. Fundamental in the vertebrate nervous system, neurotrophin signals have also been suggested as essential for relatively complex nervous systems occurring in invertebrate species that live longer than Caenorhabditis elegans and Drosophila melanogaster. Mammalian neurotrophins have been found to influence invertebrate neuronal growth. However, there are only a few data on the presence of molecules related to neurotrophin signalling components in invertebrates. Our studies provide evidence that analogues of neurotrophins and neurotrophin receptors are expressed in Eisenia foetida earthworms. In particular, NGF-like and Trk-like immunoreactive proteins are both expressed in the nervous system, whereas p75-like positivity identifies tubular structures associated with dorsal pores that are involved in the earthworm response to mechanical irritation or stress. Received 12 November 2001; received after revision 8 January 2002; accepted 8 January 2002     

Chemical mutagenesis in relation to the concept of the gene

Zusammenfassung Die vorliegende Arbeit gibt einen Überblick über neuere Untersuchungen chemischer Mutationsauslösungen mit besonderer Betonung der Induktion von Chromosomenbrüchen in Pflanzen und Rückmutationen beiNeurospora. Die Arbeit zeigt, dass jedes Allel ein charakteristisches Mutationsverhalten zeigt, das durch die Reaktion auf physikalische und chemische Mutagene definiert wird. Diese Ergebnisse werden unter dem Aspekt diskutiert, dass ein Gen die Einheit der Funktion, Rekombination und Mutation darstellt.     

Selection at the Adh locus inDrosophila melanogaster: Adult survivorship-mortality in response to ethanol

Summary Functionally significant biochemical properties of the naturally occurring electrophoretic variants at the Adh locus (ADH^fast and ADH^Slow) are correlated with the adult flies' ability to utilize and survive in an ethanol environment. The results are consistent with the idea that an environmentally dependent form of balancing selection is responsible, at least in part, for the maintenance of the polymorphism at this locus.Acknowledgment. This work was supported by NSF grant DEB 7815466 to J.M.