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81.
Cloning and sequencing of the genes encoding the large and the small subunits of the H2 uptake hydrogenase (hup) of Rhodobacter capsulatus 总被引:12,自引:0,他引:12
Michèle Leclerc Annette Colbeau Béatrice Cauvin Paulette M. Vignais 《Molecular & general genetics : MGG》1988,214(1):97-107
Summary The structural genes (hup) of the H2 uptake hydrogenase of Rhodobacter capsulatus were isolated from a cosmid gene library of R. capsulatus DNA by hybridization with the structural genes of the H2 uptake hydrogenase of Bradyrhizobium japonicum. The R. capsulatus genes were localized on a 3.5 kb HindIII fragment. The fragment, cloned onto plasmid pAC76, restored hydrogenase activity and autotrophic growth of the R. capsulatus mutant JP91, deficient in hydrogenase activity (Hup-). The nucleotide sequence, determined by the dideoxy chain termination method, revealed the presence of two open reading frames. The gene encoding the large subunit of hydrogenase (hupL) was identified from the size of its protein product (68108 dalton) and by alignment with the NH2 amino acid protein sequence determined by Edman degradation. Upstream and separated from the large subunit by only three nucleotides was a gene encoding a 34 256 dalton polypeptide. Its amino acid sequence showed 80% identity with the small subunit of the hydrogenase of B. japonicum. The gene was identified as the structural gene of the small subunit of R. capsulatus hydrogenase (hupS). The R. capsulatus hydrogenase also showed homology, but to a lesser extent, with the hydrogenase of Desulfovibrio baculatus and D. gigas. In the R. capsulatus hydrogenase the Cys residues, (13 in the small subunit and 12 in the large subunit) were not arranged in the typical configuration found in [4Fe–4S] ferredoxins. 相似文献
82.
Filtration rate capacities in 6 species of European freshwater bivalves 总被引:12,自引:0,他引:12
Summary Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect clearance and suction methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h-1) at 19–20°C as a function of dry tissue weight (DW, g) or ash-free dry weight (AFDW, g) could be expressed by the equations: 1.10 DW0.78, 6.82 DW0.88, and 2.14 AFDW0.92, respectively. In U. tumidus, U. pictorum, and U. crassus filtration rates were comparable with those of A. anatina. In D. polymorpha the b value of the corresponding regression of gill area on dry weight was 0.87. The rates of water transport in freshwater bivalves are 2–8 times lower than in marine bivalves of comparable size. A corresponding difference in the filtration rate per gill area unit is found. The measured filtration rates in undisturbed bivalves are substantially higher (at least 4 times) than previously reported. This indicates that the impact of bivalve water processing on freshwater ecosystems is greater than hitherto suggested. 相似文献
83.
Nattie E. E.; Mills J. W.; Ou L. C.; St John W. M. 《Journal of applied physiology》1988,65(4):1525-1534
We used the neurotoxin, kainic acid, which is known to stimulate neuronal cell bodies as opposed to axons of passage by binding to specific amino acid receptors to determine whether cells with such receptors have access to the ventrolateral medullary surface and are involved in central ventilatory chemosensitivity. Pledgets with 4.7 mM kainic acid were placed bilaterally on the rostral, intermediate, or caudal ventilatory chemosensitive areas for 1-2 min in chloralose-urethan-anesthetized, paralyzed, vagotomized, glomectomized, and servo-ventilated cats. Application of kainic acid on the caudal or intermediate areas produced no consistent significant effects on eucapnic phrenic output or on the slope or maximum value of the phrenic nerve response to increased end-tidal PCO2. Rostral area kainic acid produced immediate augmentation and then diminution of blood pressure and phrenic output. Apnea developed in six of nine cats by 40 min. In all five cats in which it could be tested, the slope of the CO2 response was clearly decreased. Of [3H]kainic acid applied to the rostral area, 88.4% was shown to be within 2 mm of the ventral surface. Comparison of surface application sites of this and other studies suggests that an area overlapping the border of the original rostral and intermediate areas allows access to neurons involved in the chemoreception process, which may also provide tonic facilitatory input to cardiorespiratory systems. 相似文献
84.
The oil-bee/oil-flower relationships: parallelism and other aspects of their evolution in space and time A survey is given of our present knowledge and existing hypotheses concerning the biogeography, history, and phylogeny of plant taxa yielding fatty oil as a floral reward, and of the bee genera involved in their pollination. Four syngenetic complexes of the symbiosis arose convergently: The neotropical, the paleotropical, the holarctic, and the capensic complex. On the basis of the mutual structural adaptations of bees and flowers it is concluded that, in addition, parallelism within related groups as a result of a common tendency to develop the respective organs, has played an important role in the evolution of the oil-based floral interrelationships. 相似文献
85.
Roselyne Rousseaux-Prvost Ren-Pierre Engelhardt Jean Rousseaux Danile Wouters-Tyrou Pierre Sautire 《Molecular reproduction and development》1988,19(3):277-290
The changes in basic nuclear proteins throughout cuttle-fish spermiogenesis were investigated both by immunocytochemical procedures and by isolation of late spermatid nuclei (by virtue of their resistance to sonication). Antibodies were raised in rabbits to a protein, named protein T, isolated from testis chromatin. The anti-protein T immune serum was found to recognize protein T and not histones from the testis. Immunoperoxidase staining of sections or of smears of testis with anti-protein T antibodies showed that protein T appears in the nuclei of round spermatids, is abundant in elongating spermatid nuclei, but cannot be detected in elongated spermatids. Nuclei from these elongated spermatids were isolated by sonication treatment of testis cells. A protein, named protein Sp, with the characteristic mobility of a protamine, was isolated from elongated spermatid nuclei. This protein has the same mobility as the protamine present in mature spermatozoa. Taken together, the results indicate that in cuttle-fish, nuclear protein transitions involve the replacement of histones by a spermatid-specific protein (protein T), which is replaced at the end of elongation of the nucleus by a protamine (protein Sp). Thus, spermiogenesis of the cuttle-fish (and perhaps of other cephalopods), shows two basic nuclear protein transitions, which are similar to the transitions observed in higher vertebrates such as mammals. 相似文献
86.
Improved media for normal human muscle satellite cells: Serum-free clonal growth and enhanced growth with low serum 总被引:5,自引:0,他引:5
Richard G. Ham Judy A. St. Clair Cecelia Webster Helen M. Blau 《In vitro cellular & developmental biology. Plant》1988,24(8):833-844
Summary We have developed a serum-free medium for clonal growth of normal human muscle satellite cells (HMSC). It consists of an optimized
nutrient medium MCDB 120, plus a serum-free supplement, designated SF, that contains epidermal growth factor (EGF), insulin,
dexamethasone, bovine serum albumin, and fetuin. Fibroblast growth factor was needed with dialyzed fetal bovine serum (dFBS)
as the only other supplement, but in media containing SF, it was only slightly beneficial, and was omitted from the final
medium without significant loss. Clonal growth of HMSC in MCDB 120 plus SF is as good as with 15% serum and 0.5% chicken embryo
or bovine pituitary extract. However, growth is further improved by use of a doubly-supplemented (DS) medium containing both
SF and 5% dFBS. Clonal growth of HMSC in the DS medium far exceeds that in previous media with any amount of serum, and monolayer
growth is at least equal to that in conventional media with higher levels of serum. Cells grown in these media exhibit little
differentiation, even when grown to high densities. However, they retain the capacity for extensive fusion and synthesis of
increased creatine kinase when transferred to a serum-free differentiation-promoting medium, such as Dulbecco's modified Eagle's
medium plus insulin. All experiments were done with clonal cultures of HMSC to insure that observed growth responses were
always those of muscle cells.
This research was supported by a grant from the Muscular, Dystrophy Association.
Editor's statement This article describes the optimization of both the basal nutrient medium and growth factor requirements
for human muscle cells in vitro. This system is critical for studies of normal muscle cell and molecular biology, as well
as for understanding diseases of muscle such as Duchenne, Muscular Dystrophy. 相似文献
87.
Lise Stengård Hansen 《BioControl》1988,33(1):33-42
The phytoseiid miteAmblyseius barkeri (Hughes) (=Amblyseius mckenziei Sch. & Pr.) was used for biological control ofThrips tabaci Lind. in 7 commercial glasshouses with cucumber (a total of 5780 m2). Predatory mites were introduced 3–4 times in densities ranging from 40 to 300/m2 at each release. In 6 of the 7 glasshouses, control of thrips was satisfactory throughout the growing season. Thrips densities
were kept below 15 individuals per leaf. In 1 glasshouse, thrips damage was seen on the fruits at densities of 25 thrips per
leaf, but the thrips population was quickly reduced and remained at low densities for the next 3 months.
相似文献
88.
Tina Pallesen Annette Vangsted Lars Drivsholm Henrik Clausen Jesper Zeuthen Håkan Wallin 《Glycoconjugate journal》1992,9(6):331-335
We here report an enzyme linked immunosorbent assay (ELISA) and a scintillation proximity assay (SPA) for detection of the ganglioside FucGM1 in sera from small cell lung cancer (SCLC) patients. The SPA was more sensitive and reproducible than the ELISA. In this assay, monoclonal antibodies specific for FucGM1 were bound to SPA particles and incubated with labelled FucGM1 and 100 µl test-serum overnight, and counted in a -counter. The sensitivity was 0.2 ng. Seven out of twenty sera from SCLC patients were positive, whereas none of twenty sera from healthy individuals were positive for FucGM1. The SPA was more sensitive than the previously reported HPTLC as well as a direct ELISA.Abbreviations MAb
monoclonal antibody
- SPA
scintillation proximity assay
- HPTLC
high performance thin layer chromatography
- SCLC
small cell lung cancer
- FucGM1
Fuc1-2Gal1-3GalNAc1-4(NeuAc2-3)-Gal1-4Glc1-1Cer
- ELISA
enzyme linked immunosorbent assay
- FCS
foetal calf serum
- PBS
phosphate buffered saline 相似文献
89.
Enterochromaffin-like cells in the rat stomach: effect of α-fluoromethylhistidine-evoked histamine depletion 总被引:2,自引:0,他引:2
Kjell Andersson Duan Chen Rolf Håkanson Hillevi Mattsson Frank Sundler 《Cell and tissue research》1992,270(1):7-13
Summary In the rat, gastric histamine is stored predominantly in the enterochromaffin-like (ECL) cells, which are located basally in the oxyntic mucosa. The functional significance of histamine in the ECL cells is a matter of speculation. In this study the effect of depletion of histamine on the properties and ultrastructure of the ECL cells was examined. Histamine synthesis was inhibited with -fluoromethylhistidine (3 mg·kg-1·h-1) given via osmotic minipumps over a period of 24 h. The treatment reduced the histidine decarboxylase activity (approximately 20% remaining) and histamine concentration (less than 20% remaining) in the oxyntic mucosa, as well as the intensity of histamine- and chromogranin A-immunostaining in the ECL cells, compared to control rats. The cytoplasmic (secretory) granules/vesicles were greatly reduced in number and size following -fluoromethylhistidine administration. The histamine immunostaining of the mast cells, which occurs at the mucosal surface and in the submucosa, appeared unaffected. We conclude that ECL cell histamine accounts for at least 80% of the total oxyntic mucosal histamine in the rat and that it represents a more mobile pool than mast cell histamine. The reduction in the number and size of the ECL cell granules/vesicles following histamine depletion is in accord with the idea that they represent the storage site for histamine. 相似文献
90.
Changes in brain serotonergic activity during hierarchic behavior in Arctic charr (Salvelinus alpinus L.) are socially induced 总被引:1,自引:0,他引:1
Svante Winberg Göran E. Nilsson K. Håkan Olsén 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(1):93-99
Summary The experiment was performed in two phases. During the first phase (phase 1) the dominance hierarchy was determined in 4 groups of Arctic charr (Salvelinus alpinus L.), each group consisting of 4 fish. Phase 2 was started by rearranging phase 1 fish into 4 new groups. Group 1 consisted of previously dominant fish and groups 2, 3 and 4 of fish that previously held rank 2, 3 and 4, respectively. After phase 2 telencephalon and brain stem were analyzed with regard to their contents of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), the principle metabolite of 5-HT. No correlation was found between the social rank (measured as dominance index) during phase 1 and the brain serotonergic activity (measured as the ratio 5-HIAA/5-HT) determined after phase 2. However, most important, the 5-HIAA/5-HT ratio was significantly correlated with the last experienced social rank, i.e. that acquired during phase 2. These results shows that the difference in brain serotonergic activity between dominant and subordinate fish develops through social interactions. Further, we found that previous subordinate experience inhibited aggressive behavior, an effect which, in the light of available information on stress and 5-HT, could be related to the increase in brain serotonergic activity. We hypothesize that stress induces an increased serotonergic activity which in turn inhibits the neuronal circuitry which mediates aggressive behavior.Abbreviations
5-HT
serotonin (5-hydroxytryptamine)
-
5-HIAA
5-hydroxyindoleacetic acid 相似文献