The size distribution ofTetrahymena in relation to its position in the cell cycle

Summary Tetrahymena size distribution during the cell cycle was analyzed by means of radioautography with the aid of a sonic-digitizer, and a computer. The study demonstrates that as the organism ages and passes through the various cell cycle phases the volume distribution of the organisms in each phase remains lognormal.Acknowledgments. This work was supported by a research grant from Gtiftung Volkswagenwerk No. 112273 toA. Ron. The authors wish to acknowledge the technical help of Mrs.O. Horovitz and MissS. Urieli, as well as the expert photomicrography of Mrs.E. Salomon.     

Dynamics of increase in muscle fibers in fishes in relation to size and growth

Summary Dynamics of increase of white myotomal muscle fibers of four species of freshwater teleosts (Salmo gairdneri, Pimephales notatus, Esox masquinongy andE. americanus vermiculatus) from three families (Salmonidae, Cyprinidae, Esocidae) representing a variety of maximum attainable sizes and growth rates, have been investigated. There are at least three major differences in these dynamics, and there appears to be an association between the ability of a fish species to attain large size (and grow fast) and its ability to recruit new fibers into this predominant tissue of the myotomal mass.     

Localization of integrated adenovirus DNA in the hamster genome

Adenovirus DNA integrated into the genomes of adenovirus-transformed hamster cells or of adenovirus type 12 (Ad12)-induced hamster tumor cells can be located at many different chromosomal sites. This raises the question as to whether distinct isochores of the hamster cell genome might be more accessible to recombination with adenovirus DNA. In Ad12- or Ad2-transformed hamster cell lines, and in Ad12 revertants, the investigated integrated viral DNA sequences were assigned to isochore families by analyzing DNA fractions from preparative CsCl density gradients for their buoyant densities (and, therefore, GC levels) and for the presence of viral DNA. Adenovirus DNA sequences were found in different isochores, which did not generally match the base composition of viral sequences. This is in apparent contrast to what was previously observed with retroviral integration. However, in cell lines carried in culture for many years, the viral DNA sequences might have been transposed to different isochore positions, since the host sequences flanking the viral DNA appear to have been conserved.Received 6 July 2004; received after revision 23 August 2004; accepted 6 October 2004     

Alkaline phosphatase activity in relation to DNA synthesis in synchronized hela S3 cells

Zusammenfassung In synchronisierten HeLa S3-Zellen wurde die Aktivität der alkalischen Phosphatase in Bezug auf den Zellteilungszyklus untersucht. Die geringste Aktivität wurde während der S-Phase und die höchste beim Minimum der DNS-Syntheseaktivität festgestellt, und es wird angenommen, dass die alkalische Phosphatase als Transphosphorylase zur Regulation der Polgrösse von Nucleotiden dient.

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Acknowledgment. This research was supported in part by a grant from the Israel Cancer Association.     

DNA sequence relatedness of someNeurospora isolates

Summary DNAs from several isolates ofNeurospora were characterized by thermal denaturation and DNA-DNA hybridization. All the DNAs were found to have 3 components. Based on the percentage of DNA hybridization and the degree of base pair complementation with reference DNAs it has been possible to assign some of the isolates to the known species groups.     

Mitotic rate in organs and tissues in relation to metabolic body size (kg3/4)

Zusammenfassung Das Verhältnis zwischen Lebendauer und stoffwechselbedingter Körpergrösse (kg^3/4) wird zur Analyse des Differenzialwachstums einzelner Gewebe und Organe herangezogen.     

Short-range linkage relationships, genomic organisation and sequence comparisons of a cluster of five HSP70 genes in Fugu rubripes

Twelve cosmids containing sequences resembling genes encoding members of the 70-kDa heat-shock protein family, HSP70, have been isolated from Fugu rubripes. They can be broadly divided into three groups of overlapping cosmids. Restriction analysis and sequencing of one set of five cosmids have revealed five intronless Fugu HSP70 genes spanning 42 kb, arranged in a combined head-to-head, tail-to-tail and head-to-tail orientation. The levels of DNA and amino acid identity are very high with respect to one another, and are most similar to HSP70 sequences linked to the major histocompatibility complex (MHC) region in other species. Putative heat-shock consensus elements are identified. Non-HSP70 sequences with homology to known genes have been found physically linked to this Fugu HSP70 cluster: the Drosophila melanogaster SOL gene, the Drosophila melanogaster nemo gene, the Caenorhabditis elegans T17E9.1 gene and the sequence encoding the serine protease domain. The linkage relationships described here so far bear no resemblance to those of HSP70 in other organisms. Convergence of mammalian HSP70 and MHC class I and II loci probably occurred after fish had diverged. Received 17 November 1998; received after revision 25 February 1999; accepted 26 February 1999     

Multiple hemoglobins in birds

Zusammenfassung Papierelektrophorese des Hämoglobins von zwanzig Vogelarten aus vier verschiedenen Ordnungen ergab zweiteilige Diagramme. Nur bei der Taube ist das Hämoglobin einheitlich, während sonst ziemlich allgemein in der Klasse der Aves zwei Komponenten nachweisbar sind.

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Approved by the Washington Agricultural Experiment Stations for publication. The investigation reported herein was supported, in part, from funds provided for biological and medical research by the State of Washington Initiative Measure No. 171.     

Olfactory navigation in birds

Summary Many bird species rely on an osmotactic mechanism to find food sources even at a considerable distance. Pigeons also rely on local odours for homeward orientation, and they integrate those perceived during passive transportation with those at the release site. It is possible to design experiments in which birds are given false olfactory information, and predictions about the effects of this can be made and tested. Pigeons build up their olfactory map by associating wind-borne odours with the directions from which they come; this was shown by experiments which aimed at preventing, limiting or altering this association. Some objections have been made to this conclusion; namely that even anosmic pigeons are sometimes homeward oriented, that they may be demotivated in flying or disturbed in their general behaviour, and that olfactory cues may be only one component of pigeo's navigational repertoire. The most recent experiments, however, confirm that pigeons derive directional information from atmospheric odouts. The lack of any knowledge about the chemical nature and distribution of the odorants which allow pigeons to navigate hinders progress in this area of research.     

Variation of nuclear size of neurons of the ventromedial nucleus in relation to spermatogenesis in the squirrel monkey (Saimiri sciureus)

Zusammenfassung Nachweis, dass bei ausgewachsenen Totenkopfaffen (Saimiri sciureus) die Zellkerndurchmesser im Nucleus ventromedialis hypothalami in der Periode der hochaktiven Spermiogenese kleiner sind als zu Beginn der Brunstperiode. Da das limbische System mit diesem Kern zusammenhängt, sind direkte Einflüsse nicht auszuschliessen.     

Lipids in the cell: organisation regulates function

Lipids are fundamental building blocks of all cells and play important roles in the pathogenesis of different diseases, including inflammation, autoimmune disease, cancer, and neurodegeneration. The lipid composition of different organelles can vary substantially from cell to cell, but increasing evidence demonstrates that lipids become organised specifically in each compartment, and this organisation is essential for regulating cell function. For example, lipid microdomains in the plasma membrane, known as lipid rafts, are platforms for concentrating protein receptors and can influence intra-cellular signalling. Lipid organisation is tightly regulated and can be observed across different model organisms, including bacteria, yeast, Drosophila, and Caenorhabditis elegans, suggesting that lipid organisation is evolutionarily conserved. In this review, we summarise the importance and function of specific lipid domains in main cellular organelles and discuss recent advances that investigate how these specific and highly regulated structures contribute to diverse biological processes.