Environmental influences on life history strategies in partially anadromous brown trout (Salmo trutta,Salmonidae)     

Marie Nevoux  Bengt Finstad  Jan Grimsrud Davidsen  Ross Finlay  Quentin Josset  Russell Poole  Johan Hjesj  Kim Aarestrup  Lo Persson  Oula Tolvanen  Bror Jonsson 《Fish and Fisheries》2019,20(6):1051-1082

This paper reviews the life history of brown trout and factors influencing decisions to migrate. Decisions that maximize fitness appear dependent on size at age. In partly anadromous populations, individuals that attain maturity at the parr stage typically become freshwater resident. For individual fish, the life history is not genetically fixed and can be modified by the previous growth history and energetic state in early life. This phenotypic plasticity may be influenced by epigenetic modifications of the genome. Thus, factors influencing survival and growth determine life‐history decisions. These are intra‐ and interspecific competition, feeding and shelter opportunities in freshwater and salt water, temperature in alternative habitats and flow conditions in running water. Male trout exhibit alternative mating strategies and can spawn as a subordinate sneaker or a dominant competitor. Females do not exhibit alternative mating behaviour. The relationship between growth, size and reproductive success differs between sexes in that females exhibit a higher tendency to migrate than males. Southern populations are sensitive to global warming. In addition, fisheries, aquaculture with increased spreading of salmon lice, introduction of new species, weirs and river regulation, poor water quality and coastal developments all threaten trout populations. The paper summarizes life‐history data from six populations across Europe and ends by presenting new research questions and directions for future research.  相似文献   

The nature of soil erosion and possible conservation strategies in Ntabelanga area,Eastern Cape Province,South Africa     

Cosmas Parwada  Johan Van Tol 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(6):544-552

Soil erosion is a major land degradation problem in South Africa (SA) that has economic, social and environmental implications due to both on-site and off-site effects. High rates of soil erosion by water are causing rapid sedimentation of water bodies, ultimately leading to water crisis in SA. Lots of financial and human resources are channelled towards controlling of soil erosion but unfortunately with little success. The level of soil erosion in a particular area is governed by the site properties. Therefore, it is inappropriate to generalize data on soil erosion at a large-scale spatial context. The literature on soil erosion in SA classifies Eastern Cape Province as a high-erosion-potential area using data collected at a large-scale spatial context. Collecting soil erosion data at a large spatial scale ignores site-specific properties that could influence soil erosion and has resulted in failure of many traditional soil erosion control measures applied in the province. Moreover, scientific principles underlying the processes and mechanisms of soil erosion in highly erodible soils are missing in SA. This review was to find effective soil erosion control measures by having an insight on what happens during soil erosion and how soil erosion occurs in Ntabelanga. The literature suggested that erosion in Ntabelanga could be influenced by both the erosivity and erodibility factors though the erodibility factors being more influential. Soil permeability contrast between the horizons could be influencing the rate and nature of soil erosion. To mitigate the impact of soil erosion in Ntabelanga, efforts should aim to improve the vertical flow capacity in the B horizon. Clay spreading, clay delving, addition of gypsum, deep ploughing and mulching could aid the water permeability problems of the subsurface horizons. However for effective soil management and control option, detailed studies of specific site properties are needed. The generated information can assist in formulating soil erosion policies and erosion control strategies in the Ntabelanga area and SA at large.  相似文献   

Isolation and characterization of Panax ginseng geranylgeranyl-diphosphate synthase genes responding to drought stress     

Shadi Rahimi  Yu-Jin Kim  Balusamy Sri Renuka Devi  Altanzul Khorolragchaa  Johan Sukweenadhi  Deok-Chun Yang 《European journal of plant pathology / European Foundation for Plant Pathology》2015,142(4):747-758

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Lipopolysaccharides from Commensal and Opportunistic Bacteria: Characterization and Response of the Immune System of the Host Sponge Suberites domuncula     

Johan Gardères  Gilles Bedoux  Vasiliki Koutsouveli  Sterenn Crequer  Florie Desriac  Ga?l Le Pennec 《Marine drugs》2015,13(8):4985-5006

Marine sponges harbor a rich bacterioflora with which they maintain close relationships. However, the way these animals make the distinction between bacteria which are consumed to meet their metabolic needs and opportunistic and commensal bacteria which are hosted is not elucidated. Among the elements participating in this discrimination, bacterial cell wall components such as lipopolysaccharides (LPS) could play a role. In the present study, we investigated the LPS chemical structure of two bacteria associated with the sponge Suberites domuncula: a commensal Endozoicomonas sp. and an opportunistic Pseudoalteromonas sp. Electrophoretic patterns indicated different LPS structures for these bacteria. The immunomodulatory lipid A was isolated after mild acetic acid hydrolysis. The electrospray ionization ion-trap mass spectra revealed monophosphorylated molecules corresponding to tetra- and pentaacylated structures with common structural features between the two strains. Despite peculiar structural characteristics, none of these two LPS influenced the expression of the macrophage-expressed gene S. domuncula unlike the Escherichia coli ones. Further research will have to include a larger number of genes to understand how this animal can distinguish between LPS with resembling structures and discriminate between bacteria associated with it.  相似文献   

Porcine CD18 mediates Actinobacillus pleuropneumoniae ApxIII species-specific toxicity     

Philippe G.A.C. Vanden Bergh  Laurent L.M. Zecchinon  Thomas Fett    Daniel Desmecht 《Veterinary research》2009,40(4)

Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, produces Apx toxins that are recognized as major virulence factors. Recently, we showed that ApxIIIA-cytotoxic activity specifically targets Sus scrofa leukocytes. Since both LtxA from Aggregatibacter actinomycetemcomitans (aggressive periodontitis in humans) and LktA from Mannheimia haemolytica (pneumonia in ruminants) share this characteristic, respectively towards human and ruminant leukocytes, and because both use the CD18 subunit to interact with their respective LFA-1, we hypothesized that ApxIIIA was likely to bind porcine CD18 to exercise its deleterious effects on pig leukocytes. A β ₂−integrin-deficient ApxIIIA-resistant human erythroleukemic cell line was transfected either with homologous or heterologous CD11a/CD18 heterodimers using a set of plasmids coding for human (ApxIIIA-resistant), bovine (-resistant) and porcine (-susceptible) CD11a and CD18 subunits. Cell preparations that switched from ApxIIIA-resistance to -susceptibility were then sought to identify the LFA-1 subunit involved. The results showed that the ApxIIIA-resistant recipient cell line was rendered susceptible only if the CD18 partner within the LFA-1 heterodimer was that of the pig. It is concluded that porcine CD18 is necessary to mediate A. pleuropneumoniae ApxIIIA toxin-induced leukolysis.  相似文献   

Ozone impairs autumnal resorption of nitrogen from birch (Betula pendula) leaves, causing an increase in whole-tree nitrogen loss through litter fall     

Uddling J  Karlsson PE  Glorvigen A  Selldén G 《Tree physiology》2006,26(1):113-120

Saplings of one half-sib family of birch, Betula pendula Roth, were exposed to three ozone concentrations (non-filtered air (NF); non-filtered air + 10-20 nmol O(3) mol(-1) (NF+); non-filtered air + 40-60 nmol O(3) mol(-1) (NF++)) in open-top chambers during two growing seasons from 1997 to 1998. Shed leaves were collected regularly during both growing seasons and, in 1998, the dry mass (DM) and nitrogen (N) concentrations ([N]) of the shed leaves were measured to quantify the total amount of N lost through litter fall. Dry mass and [N] were also determined in mid-August for attached, mature and non-senescent leaves, in order to estimate autumnal leaf N resorption efficiency and proportional leaf DM decrease. Net photosynthetic capacity was measured during August and September 1998, in a population of leaves that emerged in mid-July. Photosynthesis declined with increasing leaf age in the NF++ treatment, whereas it remained high throughout the measurement period in the NF and NF+ treatments. In both years, leaves abscised prematurely in the NF++ treatment, whereas this effect was only significant in 1998 in the NF+ treatment. There was a strong linear relationship between proportional leaf shedding and daylight ozone exposure above a threshold of 40 nmol mol(-1) (daylight AOT40) during the growing season. The resorption of N was significantly impaired by ozone, and the smaller autumnal decrease in leaf DM in elevated ozone concentrations suggested that the bulk resorption of leaf DM was also inhibited. Nitrogen resorption efficiencies were 81, 73 and 63% and leaf mass decreases were 45, 36 and 30% in the NF, NF+ and NF++ treatments, respectively. Compared with the NF treatment, total N loss through litter fall was increased by 16 and 122% in the NF+ and NF++ treatments, respectively. We conclude that ozone impaired N resorption from birch leaves before abscission, causing a substantial increase in whole-tree N loss through litter fall.  相似文献   

Treating experimentally induced vibriosis (Listonella anguillarum) in cod, Gadus morhua L., with florfenicol     

Seljestokken B  Bergh Ø  Melingen GO  Rudra H  Hetlelid Olsen R  Samuelsen OB 《Journal of fish diseases》2006,29(12):737-742

This study was performed to determine the efficacy of orally administered florfenicol in the treatment of experimentally induced vibriosis (Listonella anguillarum) in cod, Gadus morhua. The L. anguillarum strain HI-610 was used. This strain has a minimal inhibitory concentration value of 0.5 mg L(-1) against florfenicol. Fifteen groups of 40 fish each were challenged by bath with 1.7 x 10(5) CFU mL(-1) for 1 h. Three days following challenge, medication with florfenicol was introduced in 12 of the groups. The dosages used were 10 mg kg(-1) day(-1) for 10 consecutive days in marine or salmonid pellets, 10 mg kg(-1) day(-1) for five consecutive days in marine pellets or administered at days 1, 2, 4, 6 and 8 following initiation of treatment. Among challenged unmedicated fish mortality started at day 3 post-challenge reaching a final cumulative mortality of 77% at day 15. The experiment was terminated at day 26. In the medicated groups, the majority of deaths occurred from days 3-7 post-challenge reaching final cumulative mortalities of 31% and 52%, respectively, for the fish given marine and salmonid pellets for 10 consecutive days. The fish treated with medicated marine pellets for five consecutive days and at days 1, 2, 4, 6 and 8 (sequential feeding) following initiation of treatment had cumulative mortalities of 52% and 38%, respectively. Survival of medicated fish in all groups was significantly (P < 0.005) greater than survival of challenged unmedicated fish. Furthermore, a significant difference (P < 0.001) in survival was found between fish treated for 10 consecutive days using marine pellets and the groups using marine pellets for five consecutive days and salmonid pellets for 10 consecutive days. Twenty four hours following last medication, six fish had mean plasma concentrations of 3.3 +/- 1.7 and 3.5 +/- 2.8 microg mL(-1), respectively, in fish treated for 10 consecutive days using marine and salmonid pellets. Corresponding values for fish treated for five consecutive days and by sequential feeding were 2.2 +/- 2.3 and 1.7 +/- 0.7 microg mL(-1), respectively.  相似文献   

Induction of 2n pollen formation in <Emphasis Type="Italic">Begonia</Emphasis> by trifluralin and N<Subscript>2</Subscript>O treatments     

Angelo Dewitte  Tom Eeckhaut  Johan Van Huylenbroeck  Erik Van Bockstaele 《Euphytica》2010,171(2):283-293

In this study, treatments of both trifluralin (at 10, 100 and 1000 μM) and N₂O (in the form of gas under pressure) were applied to Begonia flower buds to induce the formation of 2n pollen. Three male fertile species (B. cucullata, B. subvillosa var. leptotricha and B. fischeri) and two male sterile hybrids (B. schmidtiana × B. cucullata and B. subvillosa var. leptotricha × B. cucullata) were treated. Pollen size, which is related to pollen DNA content, increased after both N₂O and trifluralin treatments, but the induction of large pollen was genotype dependent. Trifluralin induced large pollen only in the male fertile species, while N₂O treatments induced fertile 2n pollen in the male sterile B. schmidtiana × B. cucullata. Cytological studies showed that trifluralin induced multinuclear monads that resulted in 4n gametes in stead of 2n gametes. In general, large pollen obtained after trifluralin treatments showed low germination capability, while large pollen obtained after N₂O treatments retained high germination capability. Seedlings with raised ploidy level could only be obtained after crosses were performed with large pollen obtained from N₂O treatments. Hence, N₂O treatments are preferable to the use of trifluralin to induce 2n gametes in Begonia.  相似文献   

GGG-najaarsdag: 'Variation'     

Haneveld JK 《Tijdschrift voor diergeneeskunde》2010,135(23):920-921

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KNMVD-year congress: "People are not an isolated animal breed"     

Haneveld JK 《Tijdschrift voor diergeneeskunde》2010,135(21):821-824

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