Effect of high-intensity endurance training on isokinetic muscle power

The purpose of this study was to determine the effects of high-intensity endurance training on isokinetic muscle power. Six male students majoring in physical-education participated in high intensity endurance training on a cycle ergometer at 90% of maximal oxygen uptake (VO2max) for 7 weeks. The duration of the daily exercise session was set so that the energy expenditure equalled 42 kJ.kg-1 of lean body mass. Peak knee extension power was measured at six different speeds (30 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees.s-1) with an isokinetic dynamometer. After training, VO2max increased significantly from mean values of 51.2 ml.kg-1.min-1, SD 6.5 to 56.3 ml.kg-1.min-1, SD 5.3 (P less than 0.05). Isokinetic peak power at the lower test speeds (30 degrees, 60 degrees and 120 degrees.s-1) increased significantly (P less than 0.05). However, no significant differences in muscle peak power were found at the faster velocities of 180 degrees, 240 degrees, and 300 degrees.s-1. The percentage improvement was dependent on the initial muscle peak power of each subject and the training stimulus (intensity of cycle ergometer exercise).     

Myosatellite cells of Cyprinus carpio (Teleostei) in vitro: isolation,recognition and differentiation

Summary We have developed a method for the dissociation and purification of myosatellite cells from white epaxial muscle of carp. The dissociated myosatellite cells were identified by their morphology, their ultrastructure, the formation of multinucleated myotubes containing myofibrils and the immunocytochemical demonstration of desmin. Desmin and 5-bromo-2-deoxyuridine (BrdU) were used to identify terminally differentiated and proliferating myosatellite cells, respectively. The in vitro behavior of myosatellite cells dissociated from carp of 5 cm standard length differed from that described for myosatellite cells of mammals and birds. No substantial proliferation of the myosatellite cells could be observed. Most cells were differentiated (desmin-positive, BrdU-negative) 17 h after plating, regardless of the medium used. This indicates that the investigated white epaxial muscle of carp of 5 cm standard length contains subpopulations of myosatellite cells, arrested at various stages of differentiation.     

Core substructure in Mastigocladus laminosus phycobilisomes

A native high molecular complex (M_r 850000) containing about 50% of the allphycocyanin of the phycobilisome but lacking allophycocyanin B was separated from isolated phycobilisomes by gel electrophoresis. It was designated AP_CM since the large linker polypeptide L_CM was exclusively localized in this complex. The complex exhibited a ?196°C fluorescence emission maximum at 673 nm (671 nm at 25°C). In addition, a core complex (designated AP_C, M_r≥1000000) consisting of both AP_CM and AP 680 was isolated by combined gel filtration and linear gradient centrifugation. At 25°C this complex showed dual emission peaks at 670 and 680 nm demonstrating functional independence of the terminal emitters. A complex similar to AP_CM can be isolated from phycobilisomes of Anabaena variabilis. This is evidence that AP_CM is the constitutive center of the tricylindrical core of hemidiscoidal cyanobacterial phycobilisomes. Two models summarizing the structural and functional consequences of the results are presented in the discussion.     

The cis-acting DNA sequences required in vivo for bacteriophage Mu helper-mediated transposition and packaging

The 37,000 bp double-stranded DNA genome of bacteriophage Mu behaves as a plaque-forming transposable element of Escherichia coli. We have defined the cis-acting DNA sequences required in vivo for transposition and packaging of the viral genome by monitoring the transposition and maturation of Mu DNA-containing pSC101 and pBR322 plasmids with an induced helper Mu prophage to provide the trans-acting functions. We found that nucleotides 1 to 54 of the Mu left end define an essential domain for transposition, and that sequences between nucleotides 126 and 203, and between 203 and 1,699, define two auxiliary domains that stimulate transposition in vivo. At the right extremity, the essential sequences for transposition require not more than the first 62 base pairs (bp), although the presence of sequences between 63 and 117 bp from the right end increases the transposition frequency about 15-fold in our system. Finally, we have delineated the pac recognition site for DNA maturation to nucleotides 32 to 54 of the Mu left end which reside inside of the first transposase binding site (L1) located between nucleotides 1–30. Thus, the transposase binding site and packaging domains of bacteriophage Mu DNA can be separated into two well-defined regions which do not appear to overlap.Abbreviations attL attachment site left - attR attachment site right - bp base pairs - Kb kilobase pair - nt nucleotide - Pu Purine - Py pyrimidine - Tn transposable element State University of New York, Downstate Medical Center, Brooklyn, NY 11204 USA     

Energetics of syntrophic ethanol oxidation in defined chemostat cocultures

The ethanol-oxidizing, proton-reducing Pelobacter acetylenicus was grown in chemostat cocultures with either Acetobacterium woodii, Methanobacterium bryantii, or Desulfovibrio desulfuricans. Stable steady state conditions with tightly coupled growth were reached at various dilution rates between 0.02 and 0.14 h^-1. Both ethanol and H₂ steady state concentrations increased with growth rate and were lower in cocultures with the sulfate reducer < methanogen < homoacetogen. Due to the higher affinity for H₂, D. desulfuricans outcompeted M. bryantii, and this one A. woodii when inoculated in cocultures with P. acetylenicus. Cocultures with A. woodii had lower H₂ steady state concentrations when bicarbonate reduction was replaced by the energetically more favourable caffeate reduction. Similarly, cocultures with D. desulfuricans had lower H₂ concentrations with nitrate than with sulfate as electron acceptor. The Gibbs free energy (G) available to the H₂-producing P. acetylenicus was independent of growth rate and the H₂-utilizing partner, whereas the G available to the latter increased with growth rate and the energy yielding potential of the H₂ oxidation reaction. The critical Gibbs free energy (G_c), i.e. the minimum energy required for H₂ production and H₂ oxidation, was-5.5 to-8.0 kJ mol^-1 H₂ for P. acetylenicus,-5.1 to-6.3 kJ mol^-1 H₂ for A. woodii,-7.5 to-9.1 kJ mol^-1 H₂ for M. bryantii, and-10.3 to-12.3 kJ mol^-1 H₂ for D. desulfuricans. Obviously, the potentially available energy was used more efficiently by homoacetogens > methanogens > sulfate reducers.     

The Drosophila PROS-28.1 gene is a member of the proteasome gene family

In the present communication, we report the identification of a new gene family which encodes the protein subunits of the proteasome. The proteasome is a high-M_r complex possessing proteolytic activity. Screening a Drosophila λgt11 cDNA expression library with the proteasome-specific antibody N19-28 we isolated a clone encoding the 28-kDa No. 1 proteasome protein subunit. In accordance with the nomenclature of proteasome subunits in Drosophila, the corresponding gene is designated PROS-28.1, and it encodes an mRNA of 1.1 kb with an open reading frame of 249 amino acids (aa). Genomic Southern-blot hybridization shows PROS-28.1 to be a member of a family of related genes. Analysis of the predicted aa sequence reveals a potential nuclear targeting signal, a potential site for tyrosine kinase and a potential cAMP/cGMP-dependent phosphorylation site. The aa sequence comparison of the products of PROS-28.1 and PROS-35 with the C2 proteasome subunit of rat shows a strong sequence similarity between the different proteasome subunits. The data suggest that at least a subset of the proteasome-encoding genes belongs to a family of related genes (PROS gene family) which may have evolved from a common ancestral PROS gene.     

Efficient integrative transformation of the phytopathogenic fungus Alternaria alternata mediated by the repetitive rDNA sequences

An attempt was made to transform Alternaria alternata protoplasts using a plasmid vector, pDH25, bearing the Escherichia coli hygromycin B (Hy) phosphotransferase gene (hph) under the control of the Aspergillus nidulans trpC promoter. Transformants arose on a selective medium containing 100 μg Hy/ml. There were two types of transformants, forming large and small colonies on the selective medium. Transformation with one μg of the vector produced an average of 4.5 large colonies and 600 small ones. In large-colony transformants, the vector often integrated into the recipient chromosome in the form of highly rearranged tandem arrays. To increase transformation efficiency, fragments of the highly repetitive ribosomal RNA gene cluster (rDNA) of A. alternata were used to construct four new vectors for homologous recombination system. Use of these vectors gave higher transformation efficiency than the original plasmid. The best vector, pDH25r1a, gave rise to large-colony transformants at a frequency 20 times higher than pDH25. Transformation events in A. alternata with pDH25r1a occured by homologous recombination as a single crossover between the plasmid-borne rDNA segment and its homologue in the chromosome, often giving rise to tandemly repeated vector DNA.     

δ and κ Opiate receptors in primary astroglial cultures from rat cerebral cortex

The effects of , , and receptor-agonists on forskolin stimulated cyclic adenosine-3, 5-monophosphate (cAMP) formation were examined in astroglial enriched primary cultures from the cerebral cortex of newborn rats. Intracellular cAMP accumulation was quantified by radioimmunoassay. Morphine was used as a -receptor agonist, D-Ala-D-Leu-Enkephalin (DADLE) as a -receptor agonist and dynorphine 1–13 (Dyn) as a -receptor agonist. Basal cAMP levels were unaffected by either the opiate agonists or the antagonists used. In the presence of the cAMP stimulator forskolin, morphine had no significant effect on the cytoplasmic cAMP levels. DADLE caused a dose related inhibition of the forskolin stimulated cAMP accumulation. The effects of this receptor stimulation was blocked with the selective antagonist ICI 174.864. In the presence of Dyn, the forskolin stimulated cAMP accumulation was inhibited in a dose related manner. This receptor stimulation was blocked with the selective antagonist MR 2266. Co-administration of DADLE and Dyn resulted in a non additive inhibition of the forskolin stimulated accumulation of cAMP. These findings indicate that astroglial enriched cultures from the cerebral cortex of rats express and -receptors co-localized ont he same population of cells, and that these receptors are inhibitory coupled to adenylate cyclase.     

Regional distribution of DNA and RNA in rat brain: A sensitive determination using high-performance liquid chromatography with electrochemical detection

DNA and RNA contents in 20 brain regions or nuclei of the rat were determined by a highly sensitive method using high-performance liquid chromatography with electrochemical detection. The high DNA and RNA contents were found in the hypothalamic nuclei, especially the median eminence-arcuate nucleus. These results may be available for the preparation of nucleic acids as the regional control.     

Plasmid content in Yersinia pestis strains of different origin

Plasmid content in 242 Yersinia pestis strains from various natural plague foci of the U.S.S.R. and other countries was studied. Of these strains, 172 (71%) were shown to carry three plasmids described previously of about 6, 45-50 and 60 MDa, respectively. Twenty strains (8%) from different foci harboured additional cryptic plasmids, most often of about 20 mDa in size. Plasmid pPst displayed considerable constancy of its molecular mass. On the contrary, size variations of pCad (45-49 MDa) and, especially, pFra (60-190 MDa) were found. Molecular mass of these plasmids correlated with the host strain origin.