Artificial selection for high activity favors mighty mini-muscles in house mice

After 14 generations of selection for voluntary wheel running, mice from the four replicate selected lines ran, on average, twice as many revolutions per day as those from the four unselected control lines. To examine whether the selected lines followed distinct strategies in the correlated responses of the size and metabolic capacities of the hindlimb muscles, we examined mice from selected lines, housed for 8 wk in cages with access to running wheels that were either free to rotate ("wheel access" group) or locked ("sedentary"). Thirteen of twenty individuals in one selected line (line 6) and two of twenty in another (line 3) showed a marked reduction ( approximately 50%) in total hindlimb muscle mass, consistent with the previously described expression of a small-muscle phenotype. Individuals with these "mini-muscles" were not significantly smaller in total body mass compared with line-mates with normal-sized muscles. Access to free wheels did not affect the relative mass of the mini-muscles, but did result in typical mammalian training effects for mitochondrial enzyme activities. Individuals with mini-muscles showed a higher mass-specific muscle aerobic capacity as revealed by the maximal in vitro rates of citrate synthase and cytochrome c oxidase. Moreover, these mice showed the highest activities of hexokinase and carnitine palmitoyl transferase. Females with mini-muscles showed the highest levels of phosphofructokinase, and males with mini-muscles the highest levels of pyruvate dehydrogenase. As shown by total muscle enzyme contents, the increase in mass-specific aerobic capacity almost completely compensated for the reduction caused by the "loss" of muscle mass. Moreover, the mini-muscle mice exhibited the lowest contents of lactate dehydrogenase and glycogen phosphorylase. Interestingly, metabolic capacities of mini-muscled mice resemble those of muscles after endurance training. Overall, our results demonstrate that during selection for voluntary wheel running, distinct adaptive paths that differentially exploit the genetic variation in morphological and physiological traits have been followed.     

Hormonal and behavioral responses of starlings during a confrontation with males or females at nest boxes during the reproductive season

We investigated in an aviary experiment the behavioral and hormonal responses of European starlings (Sturnus vulgaris) that were moved from a same sex group to an aviary containing either a nest box alone, a nest box and another male, or a nest box and a female. Luteinizing hormone (LH) and testosterone (T) levels increased significantly and independently of the situation, suggesting that nest boxes were the most important stimulus affecting the levels of these hormones. Some birds occupied more than two boxes (winners), and others a single or no box (losers). Levels of T increased less in males that did not acquire a nest box. However, the increase in LH was similar in all males after the test. Singing was positively correlated with T levels. Winners started singing earlier and sang more during a contest than losers. In the presence of females LH increased more in winners than in losers, while the increase in T was similar in both groups. In females, there was no increase in T but LH increased in the presence of males. Levels were higher in females paired with winners than in females paired with losers. Finally, winners advertised their nest boxes more frequently than losers. These results indicate that within a relatively short time frame levels of LH and T increase following the transfer from a flock to a territorial situation and can react independently from each other depending on reproductive circumstances. For males, the possession of a nest box and, for females, the qualities of the male seemed to be the most important factors stimulating reproduction.     

TGF-beta 1 regulates adhesion of mucosal mast cell homologues to laminin-1 through expression of integrin alpha 7

Mucosal mast cells (MMC) or their precursors migrate through the intestinal lamina propria to reside intraepithelially, where expression of mouse mast cell protease-1 indicates the mature phenotype. Alterations in expression of integrins that govern cell adhesion to the extracellular matrix may regulate this process. As the key cytokine mediating differentiation of mouse mast cell protease-1-expressing MMC homologues in vitro, TGF-beta1 was considered a likely candidate for regulation of the integrins that facilitate intraepithelial migration of MMC. Therefore, we examined adhesion of bone marrow-derived mast cells cultured with and without TGF-beta1 to laminin-1, fibronectin, and vitronectin along with expression of integrins likely to regulate this adhesion. Adhesion of PMA-stimulated cultured mast cells to laminin-1 increased from 5.3 +/- 3.6% (mean +/- SEM) in the absence of TGF-beta1 to 58.7 +/- 4.0% (p < 0.05) when cultured mast cells had differentiated into MMC homologues in the presence of TGF-beta1. Increased adhesion of MMC homologues to laminin-1 was also stimulated by FcepsilonRI cross-linking and the calcium ionophore A23187. Expression of the laminin-binding integrin alpha(7) by MMC homologues grown in the presence of TGF-beta1 was demonstrated by RT-PCR and flow cytometry, and preincubation of MMC homologues with the alpha(7)-neutralizing Ab 6A11 inhibited adhesion to laminin-1 by 98% (p < 0.05), demonstrating a novel role for this molecule in adhesion of a hemopoietic cell to laminin-1.     

Structural Evidence for the Evolution of Pyrogenic Toxin Superantigens

Cells from metazoan organisms are eliminated in a variety of physiological and pathophysiological processes by apoptosis. In this report, we describe the cloning and characterization of molecules from the marine sponges Geodia cydonium and Suberites domuncula, whose domains show a high similarity to those that are found in molecules of the vertebrate Bcl-2 superfamily and of the death receptors. The Bcl-2 proteins contain up to four Bcl-2 homology regions (BH). Two Bcl-2-related molecules have been identified from sponges that are provided with two of those regions, BH1 and BH2, and are termed Bcl-2 homology proteins (BHP). The G. cydonium molecule, BHP1_GC, has a putative size of 28,164, while the related sequence from S. domuncula, BHP1_SD, has a M _r of 24,187. Phylogenetic analyses of the entire two sponge BHPs revealed a high similarity to members of the mammalian Bcl-2 superfamilies and to the Caenorhabditis elegans Ced-9. When the two domains, BH1 and BH2, are analyzed separately, again the highest similarity was found to the members of the Bcl-2 superfamily, but a clearly lower relationship to the C. elegans BH1 and BH2 domains in Ced-9. In unrooted phylogenetic trees the sponge BH1 and BH2 are grouped among the mammalian sequences and are only distantly related to the C. elegans BH domains. The analysis of the gene structure of the G. cydonium BHP showed that the single intron present is located within the BH2 domain at the same position as in C. elegans and rat Bcl-x_L. In addition, a sponge molecule comprising two death domains has been characterized from G. cydonium. The two death domains of the potential proapoptotic molecule GC_DD2, M _r 24,970, share a high similarity with the Fas-FADD/MORT1 domains. A death domain-containing molecule has not been identified in the C. elegans genome. The phylogenetic analysis revealed that the sponge domain originated from an ankyrin building block from which the mammalian Fas-FADD/MORT1 evolved. It is suggested that the apoptotic pathways that involve members of the Bcl-2 superfamily and of the death receptors are already present in the lowest metazoan phylum, the Porifera. Received: 27 July 1999 / Accepted: 28 December 1999     

A new Hyphoderma from Europe

The new species Hyphoderma tibia (Aphyllophorales, Basidiomycotina) is described and illustrated using drawings and scanning electron microscope.     

Die Entstehung des Farbmusters beim Lakenfelder Huhn

Zusammenfassung Das Gefieder des erwachsenen Lakenfelder Huhnes ist im großen ganzen schwarzweiß gescheckt, doch enthalten sowohl die schwarzen als auch die weißen Gefiederregionen stets eine mehr oder weniger große Anzahl von gemusterten Federn.Obwohl die Zeichnung dieser gemusterten Federn sehr variabel ist, behalten die Federn aus ein und demselben Follikel in aufeinanderfolgenden Federgenerationen ihr Muster jeweils bei.Das Kücken der Lakenfelder besitzt ein anderes Muster als das erwachsene Huhn. Wie ein Vergleich zwischen den Embryonen der einfarbig schwarzen Rheinländer und denjenigen der Lakenfelder zeigt, entstehen die Melanocyten bei der letztgenannten Hühnerrasse in viel geringerer Anzahl, besiedeln die verschiedenen Körperregionen verspätet und bilden auch weniger Pigment.Die langsamere Wanderung und die spätere Pigmentsynthese führen zur Ausbildung des Kückenmusters, während das Muster des erwachsenen Huhnes vor allem auf der verringerten Melanocytenanzahl beruht. Nur an denjenigen Körperstellen, die in unmittelbarer Nähe der beiden Entstehungszentren der Melanocyten, d. h. am Kopf und am Hinterende liegen, erhalten die Federanlagen so viele Pigmentzellen, daß hier schwarze Federn entstehen können. Die wenigen, weiterwandernden Melanocyten dringen nur noch hier und dort in einzelne Federkeime ein und führen so zu der Entstehung der in das weiße Rumpfgefieder eingestreuten mehr oder weniger stark gemusterten Federn.Auch in vitro bildet Embryonalgewebe von Lakenfeldern sehr viel weniger Melanocyten als gleichaltriges Gewebe von schwarzen Rheinländern.     

Partial purification of human placental 15-hydroxyprostaglandin dehydrogenase: Kinetic properties

The enzyme system, 15-hydroxyprostaglandin dehydrogenase, which catalyzes the first inactivation step in the catabolism of the prostaglandins has been isolated and purified 107-fold from human placenta. Kinetic studies reveal different Michaelis-Menten constants for most of the naturally occurring prostaglandins. The K_m for PGE₂ was found to be 10 μM, for PGE₁, 27 μM; for PGA₂, 32 μM; for PGA₁, 33 μM; and for PGF_2α 59 μM. The enzyme has a sharp pH-optimum between 7.5 and 8.8. Prostaglandin dehydrogenase appears to be isoenzymic as judged by separation on polyacrylamide disc gel electrophoresis. Inhibition studies with the partially purified enzyme indicate that progesterone and estrogen may influence the conversion of biologically active prostaglandins into the biologically inactive 15-ketoprostaglandins. These findings offer evidence for the control of prostaglandin metabolism in the human placenta.     

Different interactions used by Cro repressor in specific and nonspecific DNA binding

The mode of interaction of Cro repressor with specific and nonspecific sites on DNA was explored by chemical modification and protection of lysine and tyrosine residues. Cro has 8 lysines. In the presence of DNA, lysines 32 and 56 are fully protected and lysines 21, 62, and 63 are partially protected from alkylation. However, the terminal amino group and lysines 8, 18, and 39 are not protected. Location of the protected and unprotected lysines on the three-dimensional Cro structure defines a DNA-binding region. The results provide direct experimental support for a mode of interaction between Cro and DNA, in which Cro buries its 2-fold related alpha-helices in consecutive DNA major grooves (Anderson, W. F., Ohlendorf, D. H., Takeda, Y., and Matthews, B. W. (1981) Nature 290, 754-758; Ohlendorf, D. H., Anderson, W. F., Fisher, R. G., Takeda, Y., and Matthews, B. W. (1982) Nature 298, 718-723). In the model, the carboxyl-terminal part of Cro was tentatively presumed to interact with the DNA minor groove. Protection of lysines 62 and 63 confirms the involvement of the carboxyl terminus in DNA binding. Although nonspecific and specific DNA protect the same lysine residues, there are differences in the nature of the interaction of Cro with nonspecific and specific DNA. Cro-nonspecific DNA interaction is salt-sensitive, suggesting that the interaction is predominantly electrostatic. On the other hand, Cro-specific DNA interaction is salt-resistant, suggesting that the interaction may include nonelectrostatic components (hydrogen bonds and hydrophobic interactions) as well. Protection experiments of tyrosine residues (against iodination) suggest that the conformation of Cro repressor changes in two stages: first, when Cro binds at nonspecific sites, and, second, when Cro binds to specific sites on DNA.     

Monoclonal tobacco cell lines with enhanced recombinant protein yields can be generated from heterogeneous cell suspension cultures by flow sorting

Plant cell suspension cultures can be used for the production of recombinant pharmaceutical proteins, but their potential is limited by modest production levels that may be unstable over long culture periods, reflecting initial culture heterogeneity and subsequent genetic and epigenetic changes. We used flow sorting to generate highly productive monoclonal cell lines from a heterogeneous population of tobacco BY‐2 cells expressing the human antibody M12 by selecting the co‐expressed fluorescent marker protein DsRed located on the same T‐DNA. Separation yielded ～35% wells containing single protoplasts and ～15% wells with monoclonal microcolonies that formed within 2 weeks. Thus, enriching the population of fluorescent cells from initially 24% to 90–96% in the six monoclonal lines resulted in an up to 13‐fold increase in M12 production that remained stable for 10–12 months. This is the first straightforward procedure allowing the generation of monoclonal plant cell suspension cultures by flow sorting, greatly increasing the potential of plant cells as an economical platform for the manufacture of recombinant pharmaceutical proteins.     

Psoralen/UVA treatment and chromosomes

Summary Treatment of human lymphocytes in vitro with trimethylpsoralen or 8-methoxypsoralen and UVA irradiation (PUVA) induced chromosome damage, mainly constrictions and gaps, but also breaks and exchanges, and increased the frequency of sister chromatid exchange (SCE). The localization of the chromosome aberrations was nonrandom. The coincidence of many PUVA hits with mercaptoenthanol hits suggests that PUVA may have other targets in the cell than the DNA, perhaps the folding proteins of the chromosomes and the nuclear membrane/chromatin attachment organelles.Caffeine increased in a synergistic way the chromosome aberration yield if added after PUVA treatment, but there was no effect when caffeine was present before and during PUVA treatment. The SCE frequency was increased in the presence of caffeine.