Enzyme profiles of single muscle fibers never exposed to normal neuromuscular activity.

Do muscle fiber properties commonly associated with fiber types in adult animals and the population distribution of these properties require normal activation patterns to develop? To address this issue, the activity of an oxidative [succinic dehydrogenase (SDH)] and a glycolytic [alpha-glycerophosphate dehydrogenase (GPD)] marker enzyme, the characteristics of myosin adenosinetriphosphatase (myosin ATPase, alkaline preincubation), and the cross-sectional area of single fibers were studied. The soleus and medial gastrocnemius of normal adult cats were compared with cats that 6 mo earlier had been spinally transected at T12-T13 at 2 wk of age. In control cats, SDH activity was higher in dark than light ATPase fibers in the soleus and higher in light than dark ATPase fibers in the medial gastrocnemius. After transection, SDH activity was similar to control in both muscles. GPD activity appeared to be elevated in some fibers in each fiber type in both muscles after transection. The cross-sectional areas most affected by spinal transection were light ATPase fibers of the soleus and dark ATPase fibers of the medial gastrocnemius, the predominant fiber type in each muscle. These data demonstrate that although the muscle fibers of cats spinalized at 2 wk of age presumably were never exposed to normal levels of activation, the activity of an oxidative marker enzyme was maintained or elevated 6 mo after spinal transection. Furthermore, although the absolute enzyme activities in some fibers were elevated by transection, three functional protein systems commonly associated with fiber types, i.e., hydrolysis of ATP by myosin ATPase and glycolytic (GPD) and oxidative (SHD) metabolism, developed in a coordinated manner typical of normal adult muscles.     

Inbreeding and incompatibility in Trichogramma nr. brassicae: evidence and implications for quality control

Inbreeding effects and incompatibility relationships were examined in strains of the egg parasitoid Trichogramma nr brassicae (Hymenoptera: Trichogrammatidae) from southeastern Australia. Crosses between strains provided weak evidence of incompatibility in a few cases. However sex ratio in crosses within strains tended to be more female-biased than in crosses between strains. Inbreeding was imposed for four generations (F>0.59) of sib mating. The fitness of inbred strains was compared to that of outbred strains generated by crossing the inbred strains. No effects of inbreeding were found for any of the four female traits examined (fecundity, body length, head width and hind tibia length), indicating that T. nr. brassicae is not subjected to inbreeding depression. Inbreeding effects were also not found for male mating success as expected for the haploid sex. There were differences among strains for all traits apart from fecundity, indicating heritable variation. Strain differences for fitness measures were uncorrelated with wasp size. The potential use of inbreeding in the quality control of Trichogramma for mass-release is discussed. Inbreeding may be a useful tool in minimising the effects of laboratory adaptation, thereby extending the useful life of a strain.     

Polypeptide folding with off-lattice Monte Carlo dynamics: the method

The MC dynamics of an off-lattice all-atom protein backbone model with rigid amide planes are studied. The only degrees of freedom are the dihedral angle pairs of the C-atoms. Conformational changes are generated by Monte Carlo (MC) moves. The MC moves considered are single rotations (simple moves, SM's) giving rise to global conformational changes or, alternatively, cooperative rotations in a window of amide planes (window moves, WM's) generating local conformational changes in the window. Outside the window the protein conformation is kept invariant by constraints. These constraints produce a bias in the distribution of dihedral angles. The WM's are corrected for this bias by suitable Jacobians. The energy function used is derived from the CHARMM force field. In a first application to polyalanine it is demonstrated that WM's sample the conformational space more efficiently than SM's.Abbreviations CPU Central Processing Unit - MC Monte Carlo - MCD Monte Carlo Dynamics - MD Molecular Dynamics - RMS Root-Mean-Square - RMSD Root-Mean-Square-Deviation - SM Simple Move - WM Window Move     

Degradation of the fluoroquinolone enrofloxacin by wood-rotting fungi.

The veterinary fluoroquinolone enrofloxacin was degraded in vitro by four species of wood-rotting fungi growing on wetted wheat straw containing carbonyl-14C-labeled drug. A maximum 14CO2 production of 17% per week was observed with the brown rot fungus Gloeophyllum striatum, resulting in up to 53% after 8 weeks. However, rates reached at most 0.2 and 0.9% per week, if enrofloxacin was preadsorbed to native or gamma ray-sterilized soil, respectively.     

Biology ofTrichogramma ostriniae (Hym.: trichogrammatidae) reared onOstrinia nubilalis (Lep.: pyralidae) and survey for additional hosts

Trichogramma ostriniae has been identified as a candidate for biological control ofOstrinia nubilalis. As little was known about the biology of this parasitoid when reared onO. nubilalis, we undertook experiments to quantify biological parameters important to mass-rearing and ase ofT. ostriniae. When reared continuously onO. nubilalis, femaleT. ostriniae on average lived 2.7 days and produced 24 progeny. Continuous access to honey resulted in a four-fold increase in longevity and fecundity and a significant increase in the percentage of females parasitizing eggs. Rates of fecundity and parasitism decreased with age of female. Likewise, emergence rates and percentage of female progeny decreased with age of parental female.T. ostriniae successfully parasitizedO. nubilalis eggs until the blackhead stage. Most parasitism of eggs and eclosion of adults occurred during the first half of photophase. Eggs of 13 Lepidopterans were parasitized byT. ostriniae. Eggs of the Noctuidae, Pyralidae, and Plutellidae experienced higher levels of parasitism than others tested.T. ostriniae appears to be similar to other species ofTrichogramma in several respects and does not possess any characteristics that limit its potential for mass rearing and use for augmentative biological control ofO. nubilalis.     

Inactivation of a Synechocystis sp strain PCC 6803 gene with homology to conserved chloroplast open reading frame 184 increases the photosystem II-to-photosystem I ratio.

A gene of the unicellular cyanobacterium Synechocystis sp strain PCC 6803 that is homologous to the conserved chloroplast open reading frame orf184 has been cloned and sequenced. The nucleotide sequence of the gene predicts a protein of 184 amino acids with a calculated molecular mass of 21.5 kD and two membrane-spanning regions. Amino acid sequence analysis showed 46 to 37% homology of the cyanobacterial orf184 with tobacco orf184, rice orf185, liverwort orf184, and Euglena gracilis orf206 sequences. Two orf184-specific mutants of Synechocystis sp PCC 6803 were constructed by insertion mutagenesis. Cells of mutants showed growth characteristics similar to those of the wild type. Their pigment composition was distinctly different from the wild type, as indicated by an increase in the phycocyanin-to-chlorophyll ratio. In addition, mutants also had a two- to threefold increase in photosynthetic electron transfer rates as well as in photosystem II-to-photosystem I ratio-a phenomenon hitherto not reported for mutants with altered photosynthetic characteristics. The observed alterations in the orf184-specific mutants provide strong evidence for a functional role of the orf184 gene product in photosynthetic processes.     

Activation of the phosphatase activity of human cdc25A by a cdk2-cyclin E dependent phosphorylation at the G1/S transition.

Progression through the cell cycle is monitored at two major points: during the G1/S and the G2/M transitions. In most cells, the G2/M transition is regulated by the timing of p34cdc2 dephosphorylation which results in the activation of the kinase activity of the cdc2-cyclin B complex. The timing of p34cdc2 dephosphorylation is determined by the balance between the activity of the kinase that phosphorylates p34cdc2 (wee1 in human cells) and the opposing phosphatase (cdc25C). Both enzymes are regulated and it has been shown that cdc25C is phosphorylated and activated by the cdc2-cyclin B complex. This creates a positive feed-back loop providing a switch used to control the onset of mitosis. Here, we show that another member of the human cdc25 family, cdc25A, undergoes phosphorylation during S phase, resulting in an increase of its phosphatase activity. The phosphorylation of cdc25A is dependent on the activity of the cdc2-cyclin E kinase. Microinjection of anti-cdc25A antibodies into G1 cells blocks entry into S phase. These results indicate that the cdc25A phosphatase is required to enter S phase in human cells and suggest that this enzyme is part of an auto-amplification loop analogous to that described at the G2/M transition. We discuss the nature of the in vivo substrate of the cdc25A phosphatase in S phase and the possible implications for the regulation of S phase entry.     

Insect immunity. A transgenic analysis in Drosophila defines several functional domains in the diptericin promoter.

Diptericins are antibacterial polypeptides which are strongly induced in the fat body and blood cells of dipteran insects in response to septic injury. The promoter of the single-copy, intronless diptericin gene of Drosophila contains several nucleotide sequences homologous to mammalian cis-regulatory motifs involved in the control of acute phase response genes. Extending our previous studies on the expression of the diptericin gene, we now report a quantitative analysis of the contribution of various putative regulatory elements to the bacterial inducibility of this gene, based on the generation of 60 transgenic fly lines carrying different elements fused to a reporter gene. Our data definitively identify two Kappa B-related motifs in the proximal promoter as the sites conferring inducibility and tissue-specific expression to the diptericin gene. These motifs alone, however, mediate only minimal levels of expression. Additional proximal regulatory elements are necessary to attain some 20% of the full response and we suspect a role for sequences homologous to mammalian IL6 response elements and interferon-gamma responsive sites in this up-regulation. The transgenic experiments also reveal the existence of a distal regulatory element located upstream of -0.6 kb which increases the level of expression by a factor of five.