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Populations of the June beetle,Amphimallon solstitialis (Coleoptera: Scarabaeidae), were sampled from grasslands near Darmstadt, Germany, and found to be infected by a number of
diseases and parasitic nematodes. Several milky diseased larvac were found, andBacillus popilliae type A 1 isolated as the causative agent. The bacterium readily infected healthy larvae ofA. solstitialis when administeredper os in the laboratory, but was not infective to larvae ofMelolontha hippocastani by this route. A large mermithid nematode was found parasitising 10% of theA. solstitialis larvae at one site andHeterorhabditis bacteriophora was found infecting larvae at the other.
Résumé Des populations deAmphimallon solstitialis (Col.: Scarabaeidae) ont été échantillonnées dans deux prairies distinctes près de Darmstadt (Allemagne) et se sont révélées infestées par des maladies et des nématodes parasites. Plusieurs larves dans chaque site étaient infectées par la maladie laiteuse etBacillus popillae, type A1 a été isolé comme étant l'agent responsable. La bactérie infeste facilement des larves saines deA. solstitialis quand elle est administrée par voie orale au laboratoire mais n'a pas d'effet infectieux pour les larves deMelolontha hippocastani par cette même voie. Un grand nématode mermithide a été trouvé parasite de 10% des larves deA. solstitialis sur un seul site, mais comme seuls les jeunes ont été trouvés, la détermination à l'espèce n'a pu être faite.Heterorhabditis bacteriophora était responsable de l'infection de 1,5% des larves sur seulement un site. Plusieurs larves deA. solstitialis présentaient une couleur ambrée, identique à celle trouvée sur le scarabéeCostelytra zealandica infecté parSerratia spp., et ne se nourrissaient pas de carotte au laboratoire. Les bactéries isolées à partir de ces larves ne provoquent aucun effet visible quand elles sont données en nourriture à des larves saines.相似文献
65.
Different internal metabolites trigger the induction of glycolytic gene expression in Saccharomyces cerevisiae. 总被引:3,自引:1,他引:2
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In the yeast Saccharomyces cerevisiae, the sugar-induced expression of various genes coding for glycolytic enzymes is triggered by increases in the concentrations of different internal metabolites. Here, we show that the induction of the glycolytic isoenzyme enolase 2 is strictly dependent on the abilities of different mutant strains to increase the level of glucose-6-phosphate after the addition of sugars. In contrast, the induction of alcohol dehydrogenase I is dependent on increasing concentrations of metabolites in the late stages of glycolysis. 相似文献
66.
In the giant-celled marine algae Valonia utricularis the turgor-sensing mechanism of the plasmalemma and the role of the tonoplast in turgor regulation is unknown because of
the lack of solid data about the individual electrical properties of the plasmalemma and the vacuolar membrane. For this reason,
a vacuolar perfusion technique was developed that allowed controlled manipulation of the vacuolar sap under turgescent conditions
(up to about 0.3 MPa). Charge-pulse relaxation studies on vacuolarly perfused cells at different turgor pressure values showed
that the area-specific resistance of the total membrane barrier (tonoplast and plasmalemma) exhibited a similar dependence
on turgor pressure as reported in the literature for nonperfused cells: the resistance assumed a minimum value at the physiological
turgor pressure of about 0.1 MPa. The agreement of the data suggested that the perfusion process did not alter the transport
properties of the membrane barrier.
Addition of 16 μm of the H+-carrier FCCP (carbonylcyanide p-trifluoromethoxyphenyhydrazone) to the perfusion solution resulted in a drop of the total membrane potential from +4 mV to
−22 mV and in an increase of the area-specific membrane resistance from 6.8 × 10−2 to 40.6 × 10−2Ωm2. The time constants of the two exponentials of the charge pulse relaxation spectrum increased significantly. These results
are inconsistent with the assumption of a high-conductance state of the tonoplast (R. Lainson and C.P. Field, J. Membrane Biol.
29:81–94, 1976).
Depending on the site of addition, the pore-forming antibiotics nystatin and amphotericin B affected either the time constant
of the fast or of the slow relaxation (provided that the composition of the perfusion solution and the artificial sea water
were replaced by a cytoplasma-analogous medium). When 50 μm of the antibiotics were added externally, the fast relaxation process disappeared. Contrastingly, the slow relaxation process
disappeared upon vacuolar addition. The antibiotics cannot penetrate biomembranes rapidly, and therefore, the findings suggested
that the fast and slow relaxations originated exclusively from the electrical properties of the plasmalemma and the tonoplast
respectively. This interpretation implies that the area-specific resistance of the tonoplast is significantly larger than
that of the plasmalemma (consistent with the FCCP data) and that the area-specific capacitance of the tonoplast is unusually
high (6.21 × 10−2 Fm−2 compared to 0.77 × 10−2 Fm−2 of the plasmalemma). Thus, we have to assume that the vacuolar membrane of V. utricularis is highly folded (by a factor of about 9 in relation to the geometric area) and/or contains a fairly high concentration of
mobile charges of an unknown electrogenic ion carrier system.
Received: 22 October 1996/Revised: 16 January 1997 相似文献
67.
Astrid Zimmermann Anke Haina Ute Gröschel-Stewart 《Development genes and evolution》1995,204(4):271-275
The development of the autonomic ganglia of Auerbach's plexus and gizzard smooth muscle was studied in chicken embryos. Nervous system and smooth-muscle-specific antibodies were employed in immunofluorescence stainings on tissue sections to investigate the temporal and spatial frame of neural and muscular differentiation in relation to each other. Subserosal clusters of neural cells were clearly demonstrable at embryonic day 5 (ED5), the earliest stage analysed, with the monoclonal antibody El (SGIII-1). Fine nerve fibres (ED6) and, later, large axon bundles projecting from subserosal neuron clusters towards the lumen were followed and found to reach the luminal border by ED11. Already in early development the area of the future laminar tendons on the ventral and dorsal surface of the gizzard was devoid of neuroblasts, and nerve fibres were not extending to the muscle-tendon borderline until ED16. Double stainings with antibodies to smooth muscle myosin (SMM) and El revealed that SMM expression, taken as an indicator for muscle differentiation, followed neural growth. It was first detectable in close apposition to the differentiating neuroblasts in the caudal and cranial portion of the gizzard at ED6. With further development, myosin expression proceeded inward towards the lumen in a wave which followed the ingrowth of E1-positive nerve fibres from the prospective Auerbach plexus. Neuromuscular differentiation deviated from this pattern in the lateral tendon area where nerve growth was delayed and myosin expression preceeded the arrival of E1-positive nerve fibres. The findings suggest that the gizzard could serve as a model system for the analysis of potential early nervous system imprints on smooth premuscle mesenchyme differentiation. 相似文献
68.
The alpha 1-adrenergic receptor ligand, 3H-WB4101, and the alpha 2-adrenergic receptor ligand, 3H-para-aminoclonidine, were utilized at a 1.0 nM incubation concentration to determine relative alpha 1-and alpha 2-adrenergic receptor binding by cell membranes from selected tissues within the brain, ovary and oviduct of the domestic fowl. Significant specific alpha 1-adrenergic binding was observed in the hypothalamus, anterior pituitary, pineal, cerebrum and cerebellum but only the cerebrum had significant alpha 2-receptor binding. Significant levels of alpha 1-adrenergic binding were observed in the granulosa cells of the three largest ovarian follicles and in the postovulatory follicle. Significant specific alpha 2-adrenergic binding was measured in the infundibulum, magnum, isthmus and shell gland of the oviduct. The physiological implications of alpha-adrenergic receptors in these tissues are discussed. 相似文献
69.
A method is described for the preparation of haemoglobin free human erythrocyte ghosts in isotonic solutions using dielectric breakdown technique. In this single haemolytic procedure, almost complete removal of haemoglobin (? 0.1%) was achieved by subjecting the erythrocytes suspended in phosphate buffered, isotonic KCl solution at 0°C to three consecutive electrical field pulses of 16 kV/cm in the presence of 10 mM EDTA; EDTA was used to prevent electrical haemolysis. Haemolysis is induced by subsequent dilution with isotonic and isoionic solution to lower the EDTA concentration. Haemolysis is complete after 5 min; the cells are centrifuged, washed and resuspended in a solution of the same composition and osmolarity containing 4 mM MgCl2, but no EDTA. The resealing process, carried out at 37°C, was complete in about 1 h. Measurements of the size distribution of the ghost cells in the hydrodynamically focusing Coulter Counter at varying field strengths in the orifice revealed that the ghost population is nearly uniform. The mean (modal) volume of the ghost cells was 110–120 when suspended in phosphate buffered NaCl solution. The apparent breakdown voltage was about 1.3 V. 相似文献
70.
M. D. Ter-Avanesyan J. Zimmermann S. G. Inge-Vechtomov A. B. Sudarikov V. N. Smirnov A. P. Surguchov 《Molecular & general genetics : MGG》1982,185(2):319-323
Summary Recessive suppressor mutations in yeast Saccharomyces cerevisiae alter a component of the cytoplasmic ribosomes, relaxing the control of translational fidelity. As a consequence ribosomes can misread nonsense codons as amino acids (Surguchov et al. 1980a).The suppressor mutants are often respiratory deficient, being unable to grow on non-fermentable substrates. The study of the cytochrome spectra has revealed that the cytochrome b and aa3 contents were lower in the mutants than in the parent strains. Furthermore, the suppresor mutations often cause hypersensitivity to paromomycin and neomycin on media with a non-fermentable source of carbon. Some of the suppressor mutants exhibited both erythromycin and chloramphenicol-dependent growth on media containing ethanol or glycerol as a sole carbon source.These results suggest that the mutations altering cytoplasmic ribosomes may simultaneously impair the mitochondrial translation. A coupling of cytoplasmic and mitochondrial protein synthesis in yeast cells is proposed. The existence of a common protein component participating both in mitochondrial and cytoplasmic protein synthesis apparatus is discussed. 相似文献