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  • 1
    Digitale Medien
    Digitale Medien
    Microbial plankton across Drake Passage (1996)
    Springer
    Polar biology 16 (1996), S. 613-622 
    Details
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We determined biomass and activity of microbial plankton across the Polar Front (PF) in Drake Passage during January 1994. Temperature was around 0°C south and between 3 and 5°C north of the PF. Both biomass and activities of microorganisms were significantly lower in the Antarctic waters south of the PF than in the sub-Antarctic waters north of it. Thus, values of chlorophyll a, integrated between 0 and 200 m, reached 150 mg m-2 north, but only 25 mg m-2 south of the PF. Likewise, bacteria varied between 1014 and 4×1013 cells m-2. However, the abundance of heterotrophic nanoflagellates was extremely low throughout Drake Passage (around 3×1010 cells m-2). Bacterial doubling times were long (mean of 25 days). Bacterivory was estimated from the abundance of predators and prey and from temperature. The grazing impact on bacterioplankton biomass was insignificant (less that 0.05% per day) and low on bacterial heterotrophic production (15% per day). Neither biomass nor the activities of microorganisms were found to increase at the PF. The microbial food web was uncoupled and the bacteria did not seem to be controlled by predation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003000050096
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    A calibration model to overcome non-spectral interferences in flame atomic absorption spectrometry (1996)
    Springer
    Microchimica acta 124 (1996), S. 1-12 
    Details
    ISSN: 1436-5073
    Schlagwort(e): FAAS ; calibration ; standard addition ; matrix effects ; Fe determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A calibration model has been developed in order to overcome matrix effects in atomic absorption measurements. The model uses two independent variables for analyte quantification (the amount of the sample and the amount of analyte added). The dependent variable is the absorbance measured. The method also allows matrix interferences to be controlled without prior knowledge of matrix composition. The method is applied to iron determination by FAAS in the presence of large amounts of copper. Direct calibration and standard addition are also performed in order to compare them with the new empirical model. Results show that the error in iron determination could be −42% when direct calibration is applied and +10% when the standard addition method is used, whereas the proposed model decreases the error to −20%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01244951
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  • 3
    Digitale Medien
    Digitale Medien
    Complete cDNA sequences of the DRB6 gene from humans and chimpanzees: a possible model of a stop codon readingthrough mechanism in primates (1999)
    Springer
    Immunogenetics 49 (1999), S. 843-850 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words DRB6 ; MHC ; Primates ; Readingthrough mechanism ; Selenocysteine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The defective major histocompatibility complex (MHC) DRB6 gene is transcribed into mRNA in human [peripheral blood lymphocytes, transfected and Epstein-Barr virus (EBV)] and chimpanzee EBV cell lines. MHC-DRB6 presents several anomalies, which include stop codons in exon 2, lack of the usual polyadenilation signal of other MHC-DRB genes, and a promoter region and exon 1 taken from a locally inserted retrovirus. The complete cDNA sequences from human DRB6*0201 and three common chimpanzee alleles (Patr-DRB6*0108, Patr-DRB6*0109, Patr-DRB6*0111) have been obtained; two exon 1-exon 2 cDNA sequences from bonobos (Papa-DRB6*0101 and Papa-DRB6*0102) are also shown. In contrast to chimpanzee DRB6 transcripts, the human ones: (1) present an exon 1-exon 2 splicing site that includes the transcription of the first 141 nucleotides of intron 1, rendering a longer exon 1, and (2) show a duplication of exon 6, which would render a longer cytoplasmic tail in a putative DRB6 protein. These two characteristics are found in all the human sequences obtained, regardless of the cellular type tested, and they are not present in any of the chimpanzee alleles reported; consequently, they are human-specific. All the alleles reported here bear stop codons in the three possible reading frames; however, a certain level of expression of DRB6 has been observed by cytofluorometry. This could be due to the presence of a selenocysteine insertion sequence (SECIS) stem-loop structure located at the 3 untranslated region of the DRB6 mRNA, which directs selenocysteine incorporation at UGA codons. DRB6 transcription and translation would be the first gene model of a readingthrough stop codon mechanism in primate MHC. It is also feasible that the DRB6 gene might generate a population of short polypeptides, bound to plasmatic membranes, having non-antigen-presenting functions or which are presented by other MHC molecules as HLA-E presents HLA-G and -B leader sequence-derived peptides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050563
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Identification and characterization of mutations in patients with holocarboxylase synthetase deficiency (1999)
    Springer
    Human genetics 〈Berlin〉 104 (1999), S. 143-148 
    Details
    ISSN: 1432-1203
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Holocarboxylase synthetase deficiency (HCS) is an autosomal recessive disorder characterized by metabolic ketoacidosis, abnormal urine organic metabolites, and dermatitis. These symptoms are improved by pharmacological doses of biotin. In this study, we have analyzed seven patients with HCS deficiency found in European and Middle Eastern countries by using reverse transcription/polymerase chain reaction/single-stranded conformation polymorphism and a sequencing analysis. Although we had previously reported that two mutations were frequent in Japanese patients, no frequent mutations were found in the patients analyzed in this study. Seven novel mutations were identified in the cDNA of the patients; these included three missense mutations, two single-base deletions that resulted in a termination codon, a three-base in-frame deletion, and a 68-bp deletion. A new polymorphism C1121T was also identified in four alleles. A transient expression study demonstrated that the HCS activities of three missense mutations and one amino acid deletion were 1%–14% that of wild-type cDNA; in contrast, the activities of the two single-base deletions followed by a termination codon and Asp571Asn were nearly undetectable. These data suggest that a variety of mutations is responsible for decreasing HCS activity and that the aspartate residue at amino acid position 571 may be crucial for the catalytic activity of HCS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004390050927
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Pentachlorophenol and Pentachloroanisole in Oil Samples Associated with the Toxic Oil Syndrome (1999)
    Springer
    Bulletin of environmental contamination and toxicology 62 (1999), S. 1-7 
    Details
    ISSN: 1432-0800
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001289900833
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Bacterial expression of an active class Ib chitinase from Castanea sativa cotyledons (1996)
    Springer
    Plant molecular biology 32 (1996), S. 1171-1176 
    Details
    ISSN: 1573-5028
    Schlagwort(e): antifungal protein ; Castanea sativa ; chitinase ; seed defence protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Ch3, an endochitinase of 32 kDa present in Castanea sativa cotyledons, showed in vitro antifungal properties when assayed against Trichoderma viride. The characterization of a cDNA clone corresponding to this protein indicated that Ch3 is a class Ib endochitinase that is synthesized as a preprotein with a signal sequence preceding the mature polypeptide. Bacterial expression of mature Ch3 fused to the leader peptide of the periplasmic protein ompT resulted in active Ch3 enzyme. A plate assay was adapted for semi-quantitative determination of chitinase activity secreted from cultured bacteria, which should facilitate the identification of mutants with altered capacity to hydrolyse chitin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00041402
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Microbial plankton across Drake Passage (1996)
    Springer
    Polar biology 16 (1996), S. 613-622 
    Details
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We determined biomass and activity of microbial plankton across the Polar Front (PF) in Drake Passage during January 1994. Temperature was around 0°C south and between 3 and 5°C north of the PF. Both biomass and activities of microorganisms were significantly lower in the Antarctic waters south of the PF than in the sub-Antarctic waters north of it. Thus, values of chlorophyll a, integrated between 0 and 200 m, reached 150 mgm−2 north, but only 25 mg m−2 south of the PF. Likewise, bacteria varied between 1014 and 4×1013 cells m−2. However, the abundance of heterotrophic nanoflagellates was extremely low throughout Drake Passage (around 3×1010 cells m−2). Bacterial doubling times were long (mean of 25 days). Bacterivory was estimated from the abundance of predators and prey and from temperature. The grazing impact on bacterioplankton biomass was insignificant (less that 0.05% per day) and low on bacterial heterotrophic production (15% per day). Neither biomass nor the activities of microorganisms were found to increase at the PF. The microbial food web was uncoupled and the bacteria did not seem to be controlled by predation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02329059
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Process Integration of Embedded FeRAMs (1999)
    Springer
    Journal of electroceramics 3 (1999), S. 135-142 
    Details
    ISSN: 1573-8663
    Schlagwort(e): ferroelectric memories ; integrated ferroelectrics ; embedded microcontrollers ; ferroelectric material and integration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Maschinenbau
    Notizen: Abstract This paper describes the general aspects of embedding Ferroelectric Memories (FeRAMs) with logic circuits and/or microcontrollers. These devices and stand-alone memories constitute the main thrust of applications of ferroelectric memories. The problems associated with embedding test the robustness and compatibility of the FeRAM process with established CMOS integrated circuits. As integrated circuits technology advances in lithography, FeRAMs meet the challenge, but new problems appear. In this review, existing embedded FeRAMs of the 0.8/0.6 μ generation will be discussed. A program for the 0.35/0.25 μ generation, and the 0.18 μ challenges are outlined and addressed. The paper also reviews the application of FeRAM Smart Cards. This application is becoming the best example of embedded FeRAMs in which to demonstrate the “System-One-Chip” technology direction. Smart Card ICs clearly take advantage of the low power, high-write speed and long endurance characteristics of Ferroelectric Memories.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009991026077
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  • 9
    Digitale Medien
    Digitale Medien
    A preliminary report on the application of Macrobrachium amazonicum Heller, 1862 (Decapoda: Palaemonidae) as a biomarker (1999)
    Springer
    Hydrobiologia 412 (1999), S. 119-121 
    Details
    ISSN: 1573-5117
    Schlagwort(e): biomarker ; biomonitoring ; bioassay ; paraquat ; Macrobrachium amazonicum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A method is described for the rapid evaluation of water quality through monitoring the respiratory response of Macrobrachium amazonicum a dominant benthic macroinvertebrate of Northeast Brazil constituting a source of nutrients for fish and humans. By maintaining the organism in a respiratory chamber supplied with test water (gravity-feed) at a rate of 10 ml min-1, it is possible to identify when the organism is in stress. Respiration rates were determined before (control) and after test concentrations were introduced. The herbicide paraquat was used because of its popularity with sugar cane cultivators and reported low toxicity. There was a discrete increase in respiration associated with acute toxicity at all concentrations tested above 0.035 μg l-1. At 0.01 μg l-1 no increase in respiration was observed and prawn survival continued until the experiment was terminated (25 days).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003864702924
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Close association of gonadotropin-releasing hormone fibers and gonadotropin, growth hormone, somatolactin and prolactin expressing cells in pejerrey, Odontesthes bonariensis (1999)
    Springer
    Fish physiology and biochemistry 21 (1999), S. 121-127 
    Details
    ISSN: 1573-5168
    Schlagwort(e): fish ; immunocytochemistry ; pituitary gland ; pituitary hormones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The purpose of this study was to determine if there is any association between immunoreactive (ir) gonadotropin-releasing hormone (GnRH) fibers with different pituitary endocrine cell types in the pejerrey, Odontesthes bonariensis. Using a monoclonal antibody raised against mammalian GnRH (mGnRH) (LRH13), ir-GnRH fibers were observed passing through the pituitary stalk and reaching the three areas of the pituitary gland: rostral (RPD) and proximal pars distalis (PPD) and pars intermedia (PI). Double labeled immunocytochemistry showed ir-GnRH fibers in close association with prolactin (PRL)-producing cells in the RPD, growth hormone (GH)-producing cells in the PPD, gonadotropin (GtH)-producing cells in the PPD and the external border of the PI, and with somatolactin (SL)-producing cells in the PI. Our results show, direct morphological evidences of a close association of GnRH fibers with GH, PRL, GtH and SL-expressing cells. These results would suggest that GnRH has a broad role in the regulation of the secretion of different pituitary hormones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007781606592
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