Breaking seasonal limitation: year-round sporogenesis in the brown alga Laminaria saccharina by blocking the transport of putative sporulation inhibitors     

Shao Jun Pang  Klaus Lüning   《Aquaculture (Amsterdam, Netherlands)》2004,240(1-4):531-541

Year-round induction of sporogenesis of Laminaria saccharina was performed by mechanically blocking the transport of the putative sporulation inhibitors produced by the blade meristem and culturing the plants in constant short days. Sporogenesis was successfully induced by removal of the blade meristem, either by cultivating distal blade fragments or by performing a transverse cut in the frond. The earliest sorus formation after artificial induction was 10 days. The age of the sporophytes used for induction was 6–11 months or 2 years in tank-grown or field-collected sporophytes, respectively. Zoospores were successfully released in all cases. Thus, by year-round artificial induction of sporogenesis, (1) sporeling production of L. saccharina and thereafter sporophyte cultivation could be achieved without seasonal limitation, and (2) the life cycle of L. saccharina (from spore to spore) could be completed within 8 months under controlled conditions.  相似文献   

Spectral sensitivity in the photodegradation of fir wood (Abies alba Mill.) surfaces: colour changes in natural weathering     

Vjekoslav Živković  Martin Arnold  Kristijan Radmanović  Klaus Richter  Hrvoje Turkulin 《Wood Science and Technology》2014,48(2):239-252

Activation spectra of wood under natural irradiation were investigated in detail in this work. The main purpose was to study colour changes on the wood surface over time and into the depth during natural light exposure and thus to further contribute to the optimization of surface-protecting treatments. In a natural weathering test, three 80-μm-thick strips of fir wood forming the surface layer of a wood composite were exposed to light under a series of glass cut-off filters. Samples were withdrawn at intervals and tested for colour changes. Identification of the most detrimental wavebands of light causing photodegradation was performed based on recorded colour changes. With chronological development of exposure, the colour changes shifted ever deeper into the surface and further into the visible region of the spectrum. A relatively narrow waveband from 360 to 435 nm was identified in the activation spectra to be the most active band, causing the greatest proportion of recorded colour changes. However, also visible light of wavelengths up to 515 nm significantly contributed to colour changes of the surface layers.  相似文献   

Weitere Versuche zur Magnesiumbestimmung in naßveraschten Pflanzenproben mittels Atomabsorptionsflammenphotometrie und Komplexometrie     

Eberhard Thalmann  Klaus Ebert 《Archives of Agronomy and Soil Science》2013,59(8):719-722

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Digestion and Assimilation of the Free-living Nematode Panagrellus redivivus Fed to First Feeding Coregonid Larvae: Evidence from Histological and Isotopic Studies     

Christian  Schlechtriem  Ulfert  Focken Klaus  Becker 《Journal of the World Aquaculture Society》2005,36(1):24-31

The free-living nematode Panagrellus redivivus is a potential source of live food for first feeding fish. The digestion and assimilation of nematodes by larval fish were investigated with the aid of a histological and stable isotope approach. Larvae of whitefish Coregonus lavaretus were reared for 8 d with nematodes and compared with an unfed control. Nematodes were readily ingested by 3-d-old larvae. Different stages of nematode digestion could be observed in transverse sections of fish larvae sampled on Day 6 at regular intervals after feeding. Nematodes were produced on corn medium. In this way nematodes with a stable carbon isotope signature clearly different from the isotopic pattern of the fish larvae could be obtained. Stable carbon isotope signatures for lipids and lipid-free matter of fish larvae sampled on Days 2 and 8 after first feeding were clearly influenced by the stable isotopic pattern of the nematodes. The high acceptance of the nematodes by Coregonus lavaretus larvae and the early onset of digestion and nutrient retention positively confirm the potential of PanagreUus redivivus as a live food for first feeding fish larvae.  相似文献   

Isolation and characterization of bone marrow-derived equine mesenchymal stem cells   总被引：4，自引：0，他引：4  

Arnhold SJ  Goletz I  Klein H  Stumpf G  Beluche LA  Rohde C  Addicks K  Litzke LF 《American journal of veterinary research》2007,68(10):1095-1105

OBJECTIVE: To isolate and characterize bone marrow-derived equine mesenchymal stem cells (MSCs) for possible future therapeutic applications in horses. SAMPLE POPULATION: Equine MSCs were isolated from bone marrow aspirates obtained from the sternum of 30 donor horses. PROCEDURES: Cells were cultured in medium (alpha-minimum essential medium) with a fetal calf serum content of 20%. Equine MSC features were analyzed to determine selfrenewing and differentiation capacity. For potential therapeutic applications, the migratory potential of equine MSCs was determined. An adenoviral vector was used to determine the transduction rate of equine MSCs. RESULTS: Equine MSCs can be culture-expanded. Equine MSCs undergo cryopreservation in liquid nitrogen without altering morphologic characteristics. Furthermore, equine MSCs maintain their ability to proliferate and differentiate after thawing. Immunocytochemically, the expression of the stem cell marker CD90 can be detected on equine MSCs. The multilineage differentiation potential of equine MSCs was revealed by their ability to undergo adipogenic, osteogenic, and chondrogenic differentiation. CONCLUSIONS AND CLINICAL RELEVANCE: Our data indicate that bone marrow-derived stromal cells of horses can be characterized as MSCs. Equine MSCs have a high transduction rate and migratory potential and adapt to scaffold material in culture. As an autologous cell population, equine MSCs can be regarded as a promising cell population for tissue engineering in lesions of the musculoskeletal system in horses.  相似文献   

Mixed modelling for QTL × environment interaction analysis   总被引：2，自引：0，他引：2  

Hans-Peter Piepho  Klaus Pillen 《Euphytica》2004,137(1):147-153

Phenotypic data for quantitative trait loci (QTL) mapping studies are typically generated at multiple environments in order to broaden the inference space. Many aspects of the usually complex design call for a mixed modelling approach taking into account various sources of variation, e.g., incomplete blocks, a spatial error structure, genetic correlations due to the pedigree, and random environmental effects, including QTL × E interaction. Perhaps the most important source of random variation is the genetic correlation across environment, which arises when the same set of lines is tested in each environment. This correlation is likely to be positive, and ignoring it will lead to an increased rate of false positives. In this paper, we present a mixed modelling framework for QTL mapping based on complex data from multiple environments. Our main focus is on an appropriate modelling for the non-QTL part. The methodology will be illustrated using a barley data set from a BC₂F_2:5 advanced backcross trial. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Genetic basis of grain filling rate in wheat (Triticum aestivum L. emend. Thell.)     

Nehemia Anthony Mashiringwani  Kingstone Mashingaidze  Josephine Kangai  Klaus Olsen 《Euphytica》1994,76(1-2):33-44

Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P < 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P < 0.001) in LE and WPE.It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.  相似文献   

Succession of Diptera on dead beech wood: A 10-year study     

Klaus Hvemeyer  Jürgen Schauermann 《Pedobiologia》2003,47(1):61-75

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Determination of Atrazine Residues in Electro-Ultrafiltration Soil Extracts by a Sensitive Enzyme Immunoassay     

Norbert Staimer  Klaus Bürcky  Georg Steinle  Bertold Hock 《植物养料与土壤学杂志》1994,157(1):41-46

A sensitive enzyme immunoassay (EIA) based on polyclonal antibodies from sheep was used to screen for atrazine in electro-ultrafiltration (EUF) soil extracts without clean-up. Matrix effects were circumvented by diluting the aqueous EUF extracts. The EUF proved to be a convenient method for the extraction of atrazine residues in soil. The efficiency of EUF appeared to be equivalent to that of organic extraction methods except on weathered residues, which generally resulted in lower yields. Both the combined gas chromatography/automated Soxhlet (GC/Soxtec) and the immunochemical technique EIA/EUF yielded similar data for the 26 soil samples identified as positive (> 0.02 mg/kg) during the first screening of 479 EUF extracts by the EIA.  相似文献   

Physiological and biochemical characterization of quinclorac resistance in a false cleavers (Galium spurium L.) biotype     

Van Eerd LL  Stephenson GR  Kwiatkowski J  Grossmann K  Hall JC 《Journal of agricultural and food chemistry》2005,53(4):1144-1151

The physiological and biochemical basis for quinclorac resistance in a false cleavers (Galium spurium L.) biotype was investigated. There was no difference between herbicide resistant (R) and susceptible (S) false cleavers biotypes in response to 2,4-D, clopyralid, glyphosate, glufosinate-ammonium, or bentazon. On the basis of GR(50) (growth reduction of 50%) or LD(50) (lethal dose to 50% of tested plants) values, the R biotype was highly resistant to the acetolactate synthase (ALS) inhibitor, thifensulfuron-methyl (GR(50) resistance ratio R/S = 57), and quinolinecarboxylic acids (quinclorac R/S = 46), resistant to MCPA (R/S = 12), and moderately resistant to the auxinic herbicides picloram (R/S = 3), dicamba (R/S = 3), fluroxypyr (R/S = 3), and triclopyr (R/S = 2). The mechanism of quinclorac resistance was not due to differences in [(14)C]quinclorac absorption, translocation, root exudation, or metabolism. Seventy-two hours after root application of quinclorac, ethylene increased ca. 3-fold in S but not R plants when compared to controls, while ABA increased ca. 14-fold in S as opposed to ca. 3-fold in R plants suggesting an alteration in the auxin signal transduction pathway, or altered target site causes resistance in false cleavers. The R false cleavers biotype may be an excellent model system to further examine the auxin signal transduction pathway and the mechanism of quinclorac and auxinic herbicide action.  相似文献