Determinants of food security in Tanzania: gendered dimensions of household headship and control of resources     

Ryan Mason  Patrick Ndlovu  John R. Parkins  Marty K. Luckert 《Agriculture and Human Values》2015,32(3):539-549

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Expression of porcine endogenous retroviruses (PERVs) in melanomas of Munich miniature swine (MMS) Troll   总被引：1，自引：0，他引：1  

Dieckhoff B  Puhlmann J  Büscher K  Hafner-Marx A  Herbach N  Bannert N  Büttner M  Wanke R  Kurth R  Denner J 《Veterinary microbiology》2007,123(1-3):53-68

Porcine endogenous retroviruses (PERVs) are integrated in the genome of all pig breeds. Since some of them are able to infect human cells, they might represent a risk for xenotransplantation using pig cells or organs. However, the expression and biological role of PERVs in healthy pigs as well as in porcine tumours is largely unknown. Since we and others have recently shown overexpression of a human endogenous retrovirus, HERV-K, in human melanomas, we studied the expression of PERVs in melanomas of selectively bred Munich miniature swine (MMS) Troll. This breeding herd of MMS Troll is characterised by a high prevalence of melanomas, which histologically resemble various types of cutaneous melanomas in humans. Several genetic factors have been defined when studying inheritance of melanomas and melanocytic nevi in MMS Troll. Here we show that the polytropic PERV-A and PERV-B as well as the ecotropic PERV-C are present in the genome of all melanoma bearing MMS Troll investigated. Most interestingly, in the spleen, but not in other organs, recombinant PERV-A/C proviruses were found. PERV expression was found elevated in melanomas when compared to normal skin and viral proteins were expressed in melanomas and pulmonary metastasis-derived melanoma cell cultures. During passaging of these cells in vitro the expression of PERV mRNA and protein increased and virus particles were released as shown by RT activity in the supernatant and by electron microscopy. Genomic RNA of PERV-A, -B and -C were found in pelleted virus particles. Although PERV expression was elevated in melanomas and pulmonary metastasis-derived cell cultures, the function of the virus in tumour development is still unclear.  相似文献   

Unraveling the morphological patterns of a subantarctic eelpout: a geometric morphometric approach     

Fernanda S. ORREGO  Mathias HÜNE  Hugo A. BENÍTEZ  Mauricio F. LANDAETA 《Integrative zoology》2023,18(2):372-384

Phenotypic variation in organisms depends on the genotype and the environmental constraints of the habitat that they exploit. Therefore, for marine species inhabiting contrasting aquatic conditions, it is expected to find covariation between the shape and its spatial distribution. We studied the morphology of the head and cephalic sensory canals of the eelpout Austrolycus depressiceps (4.5–22.5 cm TL) across its latitudinal distribution in South Pacific (45°S–55°S). Geometric morphometric analyses show that the shape varied from individuals with larger snout and an extended suborbital canal to individuals with shorter snouts and frontally compressed suborbital canal. There was size variation across the sampled populations, but that size does not have a clear latitudinal gradient. Only 8% of the shape variation relates to this size variation (allometry), represented by a decrease in the relative size of the eye, and a depression of the posterior margin of the head. There were spatial differences in the shape of the head, but these differences were probably caused by allometric effects. Additionally, 2 of the canals of the cephalic lateralis pores and the head shape showed modularity in its development. This study shows that the morphology of marine fish with a shallow distribution varies across distances of hundreds of kilometers (i.e., phenotypic modulation).  相似文献   

Development of <Emphasis Type="Italic">Peronospora parasitica</Emphasis> epidemics on radish as modelled by the effects of water vapour saturation deficit and temperature     

Andreas Kofoet  Mathias Fink 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(4):369-381

Epidemics of Peronospora parasitica are strongly affected by temperature and air moisture, and the interaction of these factors. Because a significant percentage of radish plants are grown in greenhouses, it may be possible to influence epidemics by altering the greenhouse climate. The objective of this study was to test the hypothesis that epidemics of P. parasitica can be modelled by the effects of air temperature and moisture in the greenhouse. Such a model could then be used to analyse greenhouse climate control strategies with regard to managing downy mildew. Five radish crops were grown under greenhouse conditions with set-points for heating and ventilation intended to obtain favourable conditions for disease development during the first part of the growing cycle. Subsequent to this first phase, unfavourable conditions were set until harvest. Disease incidence was measured once a week until the radishes reached marketable size. In addition, experiments were carried out in growth chambers in which inoculated plants were subjected to air temperatures between 8 and 27°C, and disease incidence and sporulation intensity were measured. Data from these two experiments were then used to estimate model parameters. In this model, the interactions of air temperature (T) and water vapour saturation deficit (SD) were adequately described by a multiplicative relationship. The simulated epidemics by the fitted model were highly correlated with the observed epidemics (r = 0.91, R ² = 0.83, n = 29). Parameter estimates indicated that T of ca. 20°C and SD < 0.03 hPa resulted in the highest rates of disease development and that the rate was zero when SD > 2.0 hPa. Both experimental data and simulations showed that epidemics of P. parasitica can be effectively controlled by managing the greenhouse climate.  相似文献   

Upscaling as ecological information transfer: a simple framework with application to Arctic ecosystem carbon exchange     

Paul C. Stoy  Mathew Williams  Mathias Disney  Ana Prieto-Blanco  Brian Huntley  Robert Baxter  Philip Lewis 《Landscape Ecology》2009,24(7):971-986

Transferring ecological information across scale often involves spatial aggregation, which alters information content and may bias estimates if the scaling process is nonlinear. Here, a potential solution, the preservation of the information content of fine-scale measurements, is highlighted using modeled net ecosystem exchange (NEE) of an Arctic tundra landscape as an example. The variance of aggregated normalized difference vegetation index (NDVI), measured from an airborne platform, decreased linearly with log(scale), resulting in a linear relationship between log(scale) and the scale-wise modeled NEE estimate. Preserving three units of information, the mean, variance and skewness of fine-scale NDVI observations, resulted in upscaled NEE estimates that deviated less than 4% from the fine-scale estimate. Preserving only the mean and variance resulted in nearly 23% NEE bias, and preserving only the mean resulted in larger error and a change in sign from CO₂ sink to source. Compressing NDVI maps by 70–75% using wavelet thresholding with the Haar and Coiflet basis functions resulted in 13% NEE bias across the study domain. Applying unique scale-dependent transfer functions between NDVI and leaf area index (LAI) decreased, but did not remove, bias in modeled flux in a smaller expanse using handheld NDVI observations. Quantifying the parameters of statistical distributions to preserve ecological information reduces bias when upscaling and makes possible spatial data assimilation to further reduce errors in estimates of ecological processes across scale.  相似文献   

The effects of drying temperature on chemical composition and nutritive value of some tropical fodder shrubs     

L. Hove  L.R. Ndlovu  S. Sibanda 《Agroforestry Systems》2003,59(3):231-241

The effects of drying temperature on chemical composition and nutritive value of leaves of the shrub legumes Acacia angustissima (Miller) Kuntze, Calliandra calothyrsus Meissn and Leucaena leucocephala (Lam.) de Wit were determined in two studies in Zimbabwe. In the first study, the effects of shade-, sun- and oven-drying leaves on chemical composition and protein precipitation capacity of tannin extracts were studied. Drying method affected (P<0.01) chemical composition, with cell wall polysaccharides increasing from shade drying to oven drying. Calliandra calothyrsus leaves had the highest total phenolics, tannin phenolics and the lowest N content. About 40% of phenolics in L. leucocephala were non-tannin compared to less than 15% in A. angustissima and C. calothyrsus. Extractable proanthocyanidins and their capacity to precipitate protein were affected (P<0.01) by drying method; extracts from shade-dried leaves were 10% and 20% more reactive than extracts from sun- and oven-dried leaves, respectively. The relative degree of polymerisation of the proanthocyanidins was higher (P<0.01) for oven-dried (1.44) leaves compared to shade-dried (1.01) and sun-dried (1.00) leaves. Drying temperature influences the nutrient–polyphenolic interactions in A. angustissima, C. calothyrsus and L. leucocephala leaves and these interactions have important implications for feed evaluation protocols and for use of these leaves in ruminant feeding systems. The second study considered the effects of feeding sun-dried or fresh leaves of the three shrub legumes as supplements to native pasture hay on nutrient intake and digestion by goats. Feeding the fresh or dry leaves made no difference in terms of dry matter intake and digestion, and N digestion. This offers farmers flexibility in terms of feeding strategies, as they can feed the browse in any form that suits their farm situation. Increasing the level of C. calothyrsus in the diet increased faecal N. Nitrogen retention was lower for animals fed with C. calothyrsus compared to those fed with the other browses.  相似文献   

Associations among Haemophilus parasuis,Mycoplasma hyorhinis,and porcine reproductive and respiratory syndrome virus infections in pigs with polyserositis     

Andreas Palzer  Kristina Haedke  Karl Heinritzi  Susanne Zoels  Andrea Ladinig  Mathias Ritzmann 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(3):285-287

The objective of this study was to determine the associations among Haemophilus parasuis, Mycoplasma hyorhinis, and porcine reproductive and respiratory syndrome (PRRS) virus (EU-field strain) infections in 95 pigs with polyserositis. A significant association between H. parasuis and M. hyorhinis was identified. H. parasuis and M. hyorhinis were significantly more often detected in PRRS virus positive pigs.  相似文献   

Kinetic modeling of malonylgenistin and malonyldaidzin conversions under alkaline conditions and elevated temperatures     

Vaidya NA  Mathias K  Ismail B  Hayes KD  Corvalan CM 《Journal of agricultural and food chemistry》2007,55(9):3408-3413

The conversion and degradation of malonylglucosides were kinetically characterized under elevated pH/heat conditions. Malonylgenistin and malonyldaidzin were heated at 60, 80, and 100 degrees C and pH values of 8.5, 9, and 9.5. A simple kinetic model was developed, which adequately predicted the conversion and degradation reactions. The conversion and degradation rates increased as temperature and pH increased. The rates of conversion of both malonylglucosides into their respective beta-glucosides were comparable under all pH/heat treatments. However, at 100 degrees C, the rates of degradation of malonyldaidzin were approximately double those of malonylgenistin, under all pH treatments. When malonlydaidzin was heated at 100 degrees C and pH 9.5, degradation of the produced daidzin occurred. Therefore, an alternative kinetic model was developed to better predict the conversion and degradation of malonyldaidzin occurring at 100 degrees C and pH 9.5. The models developed provide soy food manufacturers with guidelines for better control of the profile and level of isoflavones..  相似文献   

Crown allometry and growing space requirements of four rare domestic tree species compared to oak and beech: implications for adaptive forest management     

Schmucker  Julia  Uhl  Enno  Steckel  Mathias  Pretzsch  Hans 《European Journal of Forest Research》2022,141(4):587-604

European Journal of Forest Research - Rare domestic tree species are increasingly being viewed as promising alternatives and additions to current main tree species in forests facing climate change....  相似文献   

Functional investigation of a QTL affecting resistance to Haemonchus contortus in sheep     

Guillaume Sallé  Carole Moreno  Simon Boitard  Julien Ruesche  Aurélie Tircazes-Secula  Frédéric Bouvier  Mathias Aletru  Jean-Louis Weisbecker  Fran?oise Prévot  Jean-Paul Bergeaud  Cathy Trumel  Christelle Grisez  Emmanuel Liénard  Philippe Jacquiet 《Veterinary research》2014,45(1):68

This study reports a functional characterization of a limited segment (QTL) of sheep chromosome 12 associated with resistance to the abomasal nematode Haemonchus contortus. The first objective was to validate the identified QTL through the comparison of genetically susceptible (N) and resistant (R) sheep produced from Martinik × Romane back-cross sheep. The R and N genotype groups were then experimentally infected with 10 000 H. contortus larvae and measured for FEC (every three days from 18 to 30 days post-challenge), haematocrit, worm burden and fertility. Significant differences in FEC and haematocrit drop were found between R and N sheep. In addition, the female worms recovered from R sheep were less fecund. The second step of the characterization was to investigate functional mechanisms associated with the QTL, thanks to a gene expression analysis performed on the abomasal mucosa and the abomasal lymph node. The gene expression level of a candidate gene lying within the QTL region (PAPP-A2) was measured. In addition, putative interactions between the chromosome segment under study and the top ten differentially expressed genes between resistant MBB and susceptible RMN sheep highlighted in a previous microarray experiment were investigated. We found an induction of Th-2 related cytokine genes expression in the abomasal mucosa of R sheep. Down-regulation of the PAPP-A2 gene expression was observed between naïve and challenged sheep although no differential expression was recorded between challenged R and N sheep. The genotyping of this limited region should contribute to the ability to predict the intrinsic resistance level of sheep.  相似文献