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  • 1
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Five qualitative and seven quantitative colouration and spotting pattern features were measured in 23 brown trout Salmo trutta populations and two hatchery stocks. Simultaneously, the LDH-C1*, a diagnostic locus fixed for *90 and *100 alleles in stocking and native populations from southern Europe, respectively, was analysed to classify the brown trout studied according to their origin: native, hatchery stock and hybrids. The three genotypes showed significant differences in the colouration and spotting features and a discriminant function analysis could correctly identify 79% of the individuals. The most discriminating variables were dorsal fin margin colour, number of opercular spots, presence of the preopercular mark and diameter of black spots. Given the low cost, ease and possibility of field identification of native fish, the results indicate great opportunities for the application of morphological-based classification models on the conservation and management of native brown trout stocks.
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The heat shock response in Caulobacter crescentus was previously shown to be positively regulated by the alternative sigma factor of RNA polymerase (RNAP) σ32, and negatively modulated by DnaK during the induction phase of the heat shock response but not during the recovery phase. In the present work we have investigated the involvement of the chaperone ClpB in the control of the heat shock response in C. crescentus. Data obtained indicated a role of ClpB in downregulation of heat shock protein (HSP) synthesis, as cells lacking this chaperone showed a prolonged shutoff phase of the heat shock response. In Escherichia coli, it has been proposed that the DnaK chaperone system switches transcription back to constitutively expressed genes through simultaneous reactivation of heat-aggregated σ70, as well as sequestration of σ32 away from RNAP. In C. crescentus, results obtained with a clpB null mutant indicate that ClpB could be involved in the reactivation of the major sigma factor σ73. In support of this hypothesis, we showed that transcription directed from σ73-dependent promoters is not switched back in the clpB null mutant during the recovery phase. Furthermore, we observed that resolubilization of heat-aggregated σ73 is dependent on the presence of ClpB. Our findings also indicated that the absence of ClpB made cells more sensitive to heat shock and ethanol but not to other stresses, and unable to acquire thermotolerance.
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  • 3
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The purpose of the present study was to characterize daily variations in haematology and blood biochemistry in healthy male and female tench (Tinca tinca) in the four seasons of the year. Red blood cells, haematocrit and haemoglobin presented a similar daily profile in spring and summer, with high values during the scotophase. Total and differential types of leucocytes showed significant daily fluctuations, with a different pattern depending on the season and/or the type of leucocytes studied. A daily rhythm in plasma glucose and triglycerides was detected in winter, but significant changes in cholesterol concentrations were only detected in females during summer. The lowest mean level for triglycerides and cholesterol was observed in winter. The daily profile of plasma total proteins was similar in the four seasons, without a significant daily oscillation. All these daily and seasonal changes in haematology and blood biochemistry indicate that the time of the day and the season must be considered when such parameters are used for assessing the physiological status of the fish, and as biomarkers for disease and/or pollutant exposure.
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  • 4
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Agriculture has claimed a large share of terrestrial environments in the tropics and subtropics through cultivation of native grasslands or forests. The impact of this anthropogenic change on speciation, dynamics, and ecological significance of sulphur (S) compounds is still poorly understood. We combined degradative wet-chemical reduction and S K-edge X-ray absorption near edge structure (XANES) spectroscopy techniques to evaluate the impact of long-term agricultural management of native grassland soils in South African Highveld on the amount, form and dynamics of S species. Sulphur XANES in the humic substances extracted by 0.1 m NaOH/0.4 m NaF solution showed the presence of strongly reduced (polysulphides, disulphides, thiols, monosulphides and thiophenes), intermediate (sulphoxides and sulphonates) and strongly oxidized (ester sulphates) organic-S. It showed that strongly oxidized-S is the predominant form (39–54%) of the total organic-S in the humic substances, and organic-S in the intermediate oxidation state represented 30–37% (78–93% of which was attributed to sulphonates). The strongly reduced organic-S comprised only 17–24% of the total organic-S. We did not find a close correlation between the results of a degradative wet-chemical procedure and XANES spectroscopy conducted in both the bulk soils (ester SO4-S from XANES versus HI-fractionation, r = 0.27; P 〈 0.05) and the humic substance extracts (ester SO4-S from XANES versus HI-fractionation, r= 0.39; P 〈 0.05). The ratio of reduced-S to strongly oxidized-S (R-S/O-S) in the humic substances decreased from 0.61 to 0.21, while the ratio of intermediate-S to strongly oxidized-S (I-S/O-S) declined from 0.93 to 0.61 after 90 years of arable cropping of the native grassland soils. Hence, there was a shift in oxidation state towards strongly oxidized-S (+6) and, thereby, a change in the relative proportion of the organic-S moieties associated with each oxidation state following cultivation of the native grassland soils. Therefore, we conclude that changes in land-use practice brought about not only quantitative change but also altered the composition of organic-S functional groups in these native subtropical grassland soils.
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  • 5
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The protection of cultured sole, Solea senegalensis, against Vibrio harveyi and Photobacterium damselae subsp. piscicida was evaluated following the use of a divalent vaccine prepared with formalized whole cells and extracellular products of virulent strains of both pathogenic microorganisms and administered by the immersion route. Two prolonged immersions of 5–10 g fish in the divalent bacterin at a 1-month interval gave high levels of protection similar to those obtained when the respective monovalent vaccines were administered by the intraperitoneal route [relative percentage of survival (RPS) values 〉70%], which indicates that the former procedure can be a useful strategy with small fish. The high protection afforded by the divalent vaccine in sole lasted for 4 months after which the RPS values against both pathogens decreased significantly.
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  • 6
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Root-knot nematodes (Meloidogyne spp.) are among the main pathogens of tomato (Lycopersicon esculentum) worldwide. Plant resistance is currently the method of choice for controlling these pests and all the commercially available resistant cultivars carry the dominant Mi gene, which confers resistance to the three main species Meloidogyne arenaria, M. incognita and M. javanica. However the emergence of virulent biotypes able to overcome the tomato resistance gene may constitute a severe limitation to such a control strategy. To date, little was known of the possible influence of the homozygous vs heterozygous allelic state of the Mi locus, or the tomato genetic background, on the expression of the resistance. In order to test both these factors, the resistance was evaluated of a large panel of L. esculentum genotypes (selected from the Vilmorin germplasm stock collection) to seven M. incognita lines avirulent or virulent against the Mi gene. Plant resistance was estimated by counting the egg masses on the root systems after inoculation with second-stage juveniles (J2). Reproduction of the nematodes was similar or, more often, significantly higher on heterozygous tomato genotypes than on homozygous ones, suggesting a possible dosage effect of the Mi gene. Data also indicated that the tomato genetic background had a major effect on the variations observed in nematode reproduction, especially when tomato genotypes were heterozygous for the Mi gene. These results have important consequences in terms of breeding strategies and durability of the resistance conferred by the Mi gene.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 54 (2005), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The response of a susceptible coffee cultivar (Caturra) to infection by the root-knot nematode Meloidogyne exigua was compared histologically with that of cv. Iapar 59 possessing the recently identified Mex-1 resistance gene. The reproductive behaviour of the nematode was also compared in the two cultivars. Penetration and development in resistant plants were reduced in comparison with susceptible plants. Several cell features, including dark-stained cytoplasm and altered organelle structure, were observed in the resistant cultivar, indicating a hypersensitive-like (HR) response of the infested host cells. Features of giant cells were sometimes found beside necrotic-like areas, but the corresponding feeding sites were frequently associated with nematodes displaying abnormal shape. Six weeks after inoculation, root systems of cv. Caturra contained significantly more nematodes than those of cv. Iapar 59 (mean values 1574 and 41, respectively). The susceptible cultivar presented a minimum of 11 galls per plant, compared with only one or two galls per plant in the resistant cultivar. The findings are discussed in the context of plant–pathogen interactions.
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  • 8
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Phenoloxidase and peroxidase activity were analysed in haemolymph of juvenile shrimp, Litopenaeus schmitti, exposed to different salinity levels (35%, 18%, 8%) for 48 h. A significant reduction (P〈0.05) in total glucose and phenoloxidase activity in animals exposed to lower salinities (18% and 8%) was recorded, while peroxidase activity and total protein concentration did not vary. Histology revealed the occurrence of oedema in gills in shrimp exposed to 8%. The work demonstrates for the first time that in L. schmitti, low salinities can decrease glucose levels in haemolymph and create an immunosuppressive state by reducing phenoloxidase activity.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 36 (2005), S. 0 
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Results of a 1-year intensive monitoring of Vibrio bacteria, as thiosulphate citrate billar salt sucrose (TCBS) counts, in a hatchery for molluscs, are presented. Surface seawater, well seawater, tap water from a freshwater well, microalgae system, including pasteurized well seawater, f/2 medium, starter cultures of eight micro algal species, mass-produced microalgae and compressed air were studied as possible sources of Vibrio. Additionally, recently collected broodstock of the catarina scallop Argopecten ventricosus (Sowerby II 1842) was also subjected for investigation for their possible role in discharging Vibrio during spawning. Efficiency of a cartridge–ultraviolet (UV)-filtration system and of a steam gun employed for sterilizing tanks, hoses and utensils was also determined. Results indicated that Vibrio were present in surface seawater throughout the year. In well seawater these bacteria were only found during the first 5 months soon after construction of the well and before commencement of continuous operations, but not after this period. Vibrio was never detected in pasteurized well seawater, f/2 medium, starter cultures of microalgae and compressed air. However, mass-produced microalgae contained Vibrio, possibly as a result of the use of contaminated tap water for washing and rinsing the fibreglass culture tanks. Scallop broodstock was found to be an important source of Vibrio in the hatchery. Biopsy on female gonads of live organisms demonstrated higher numbers of colony-forming units than male gonads. At spawning, Vibrio was released into water, producing bacterial blooms in tanks after 24 h. The cartridge–UV-filteration system was not sufficient to eliminate the bacteria from seawater, but the steam gun proved to be a good tool to eliminate Vibrio biofilms on tank walls or tools used in the hatchery. Some recommendations are given, which could be useful for other mollusc hatcheries.
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  • 10
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Zooplankton, macrozoobenthos and feeding habits of Litopenaeus stylirostris and L. vannamei in monoculture and polyculture semi-intensive experimental ponds were evaluated. Zooplankton was more abundant in monoculture of L. stylirostris (1002±670 organisms (org.) L−1) than in monoculture of L. vannamei (470±37 org. L−1), and polyculture (321±188 org. L−1). The main zooplanktonic groups were polychaeta larvae, nauplii, copepods and polychaeta. Macrozoobenthos was more abundant in polyculture (6898±11 137 org. m−2) compared with monoculture of L. stylirostris (3201±350 org. m−2) and L. vannamei (2384±3752 org. m−2). The main benthic groups were copepods, polychaeta, ostracods, nematodes and insects. Differences in feeding habits were found between species and regimes. Litopenaeus vannamei showed to be a more voracious species and fed mostly on organic detritus and benthos in both culture regimes. Litopenaeus stylirostris had a more restricted sources of feed in the ponds. The major component in the stomach content of both species was detritus. Macroalgae, sand, exuvia, formulated feed, prey and microalgae were minor components for both species (〈7%). Ingestion of formulated feed was 〈4% for L. stylirostris and was not detected for L. vannamei. The stomach repletion rates were larger for L. vannamei (55.6% and 48.8%) than for L. stylirostris (43.75% and 44.89%). Litopenaeus stylirostris grew better in polyculture (10.3±3.4 g) that in monoculture (9.0±3.8 g). Litopenaeus vannamei grew better in monoculture (16.1±4.8 g) than in polyculture (13.4±4.5 g). For both species, feed conversion ratio was lower in polyculture.
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