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11.
Ute Mühlenhardt-Siegel 《Helgoland Marine Research》1988,42(1):37-65
Macrobenthic fauna and sediment structure were studied at 6 stations from June 1979 to April 1981. The investigations were
carried out in the outer estuary of the River Elbe at depths of 15–38 m near a sewage sludge dumping site. The sediment near
this area consisted of a high portion of silt. Usually, very few species and small numbers of individuals were found near
that dumping ground. During summer 1980, a mass development ofAbra alba and several polychaete species caused an increase in species number which broke down during the following winter. The mass
development observed in the study area was apparently not directly caused by the sludge dumping itself, but reflects the natural
variability of the community structure. The number of species recorded was significantly correlated with a grain size fraction>31
μm, especially in summer. The seasonal and spatial fluctuation of the benthic community could be well documented by the abundance
per species (N/S index). The Shannon-Wiener-Index (H′) and eveness (J) were also useful indicators of community variability.
The log-normal distribution did not show the seasonal and the spatial differences of the stations. Possible reasons are discussed.
The biomass at the stations near the dumping area was less except during the mass development ofA. alba. The average individual weight (B/N) was shown to be a good indicator of population fluctuations; polychaete biomass was
positively correlated to a grain size fraction≦6 μm, that of molluscs to a grain size fraction>31 μm.
相似文献
12.
Susanne Niemann-Seyde Ryszard Slomski Frauke Rininsland Ute Ellermeyer Jolanta Kwiatkowska Jochen Reiss 《Human genetics》1992,90(1-2):65-70
Summary A total of 56 Duchenne muscular dystrophy (DMD) patients and 11 Becker muscular dystrophy (BMD) patients was analyzed by extended multiplex amplification of the DMD/BMD gene; deletions were found in 60% of these patients. The data obtained were used to test the frameshift hypothesis and to compare the distribution of familial versus isolated cases. A significant correlation was found between deletions and isolated cases. Additional experiments were performed in order to determine the deletion breakpoints more precisely. These data are a prerequisite for carrier analysis in the respective families by detection or exclusion of aberrant cDNA fragments derived from ectopic lymphocyte RNA. This diagnostic technique is illustrated by 5 examples. 相似文献
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The synthesis of 5-aminolevulinic acid commences with the ligation of glutamate to a specific tRNAGlu by a glutamyl-tRNA synthetase (E.C. 6.1.1.17) (Huang et al., 1984, Science 225, 1482–1484). The synthetase from the yellow pigment mutant C-2A of the unicellular green alga Scenedesmus obliquus was purified by sequential column chromatography on Sephacryl S-300, Blue Sepharose, phosphocellulose P11 and by fast protein liquid chromatography (FPLC) on Mono Q. After denaturing sodium dodecylsulfate (SDS)-gel electrophoresis the purified enzyme preparation revealed a single protein band with a molecular mass of 55 kDa, proving the apparent homogeneity of the glutamyl-tRNA synthetase. A molecular mass of 105 ± 10 kDa was determined for the native protein by chromatography on Sephadex G-150. From these data it can be concluded that the glutamyl-tRNA synthetase from S. obliquus is a homodimer. The purified protein is active within a pH range from 7.0 to 9.0 with a maximum activity at pH 8.0. Kinetics for the binding of glutamate to the tRNA, performed with highly purified enzyme preparations, showed a K
m value of 2.3 M ± 0.3 for glutamate.Abbreviations ALA
5-aminolevulinic acid
- FPLC
fast protein liquid chromatography
- Glu
glutamate
- Hepes
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- SDS
sodium dodecylsulfate
- Tricine
N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]-glycine
This work was supported by a grant of the Deutsche Forschungsgemeinschaft. U.C. Vothknecht is grateful for a Nachwuchs-förderungsstipendium des Landes Hessen. The authors want to thank Ms. B. Böhm, J. Gade and K. Eckhardt for skillful technical assistance. The authors also want to thank Dr. C.G. Kannangara (Carlsberg Institute, Kopenhagen, Denmark) for the donation of tRNA from barley and Dr. D. Jahn (FB Biology/Microbiology, Philipps-University, Marburg, FRG) for the tRNAGlufrom E. coli. 相似文献
18.
Resonance Raman experiments were performed on different green bacteria. With blue excitation, i.e. under Soret resonance or preresonance conditions, resonance Raman contributions were essentially arising from the chlorosome pigments. By comparing these spectra and those of isolated chlorosomes, it is possible to evaluate how the latter retain their native structure during the isolation procedures. The structure of bacteriochlorophyll oligomers in chlorosomes was interspecifically compared, in bacteriochlorophyllc- and bacteriochlorophylle- synthesising bacteria. It appears that interactions assumed by the 9-keto carbonyl group are identical inChlorobium limicola, Chlorobium tepidum, andChlorobium phaeobacteroides. In the latter strain, the 3-formyl carbonyl group of bacteriochlorophylle is kept free from intermolecular interactions. By contrast, resonance Raman spectra unambiguously indicate that the structure of bacteriochlorophyll oligomers is slightly different in chlorosomes fromChloroflexus auranticus, either isolated or in the whole bacteria. 相似文献
19.
Nucleotide sequence information from a partial genomic clone, a cDNA clone, a RACE clone and a PCR fragment was combined to reconstruct the first reported complete gene sequence encoding a large legumin subunit, designated LelB3. The length difference to the well-characterized major legumin subunits is caused by an extended glutamin/glutamic acid-rich region encoded by the C-terminal part of the chain. Amino acid sequence comparisons reveal that gene LelB3 is more closely related to B-type than to A-type legumin genes of Vicia faba. Gene LelB3 is a member of a small gene family as indicated by published (Pich and Schubert, Biol Zbl 112 (1993); 342–350) and limited own data. 相似文献
20.
Heber Ulrich; Wagner Ute; Kaiser Werner; Neimanis Spidola; Bailey Karen; Walker David 《Plant & cell physiology》1994,35(3):479-488
Induction of photosynthesis in leaves was prolonged, and steadystate photosynthesis was inhibited by very high CO2 concentrationswhich cause cytoplasmic acidification. Prolonged exposure tohigh CO2 relieved initially observed inhibition of photosynthesisat least partially. The sensitivity of carbon assimilation tohigh CO2 was different in different plant species. Acidificationby CO2 (or subsequent alkalization) was detected by measuringrapid CO2-release from the tissue and by monitoring fluorescenceof pH-indicating dyes which had been fed to the leaves throughthe petiole. The results indicate that two different mechanismsoperate in leaves to achieve and maintain pH homeostasis. Rapidand efficient pH-adjustment is provided by proton/cation exchangeacross the tonoplast. Slower and less efficient regulation occursby formation or consumption of base. In the presence of highCO2 concentrations, protons are pumped from the cytosol intoalready acidic vacuoles. In turn, vacuolar cations replace exportedprotons in the cytosol permitting bicarbonate accumulation andincreasing the pH of the acidified cytosol. Similarly effectiveand fast proton/cation exchange relieves acid-stress in thechloroplast stroma and permits photosynthesis to proceed withhigh quantum efficiency or high light-saturated rates in thepresence of CO2 concentrations which would, in the absence offast cytoplasmic pH regulation, inhibit photosynthesis. By inference,proton/cation exchange must also occur across the mitochondrialboundary. After cytoplasmic pH adjustment in the presence ofhigh CO2, removal of CO2 results in transient cytoplasmic alkalizationand, subsequently, in the return of cytoplasmic pH values tolevels observed prior to acid-stress. In addition to fast pHregulation by rapid proton/cation exchange across biomembranes,slow base production (e.g. NH3-formation) also contributes torelieving acid stress. Base produced in the presence of highCO2 is rapidly consumed after removal of CO2. Implications of the findings in regard to forest damage by potentiallyacidic air pollutants such as SO2 are briefly discussed. (Received November 8, 1993; Accepted February 3, 1994) 相似文献