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81.
Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon. 相似文献
82.
BACKGROUND: Fluensulfone, a new nematicide of the fluoroalkenyl group, has proved to be very effective in controlling root‐knot nematodes, Meloidogyne spp., by soil application. The systemic activity of this compound against M. incognita on peppers via soil drenching and foliar spray was evaluated. RESULTS: Root application of fluensulfone via soil drenching showed slight and no nematode control activity when applied 4 and 10 days, respectively, after inoculation. A single foliar spray of peppers with a fluensulfone solution at 3.0 g L?1 prior to inoculation reduced the galling index by 80% and the number of nematode eggs by 73–82% of controls. The reduction in these parameters by fluensulfone was much higher than that obtained with oxamyl or fenamiphos at the same concentration. This activity was also observed when the plants were sprayed 21 days before inoculation. A series of experiments suggested that foliar spray with fluensulfone prior to inoculation reduces nematode invasion. However, foliar spray after inoculation did not inhibit nematode development inside roots. CONCLUSION: Fluensulfone showed relatively high nematode control activity when sprayed on the foliage before inoculation. Fluensulfone may be used as a foliar application, in addition to soil application, for root‐knot nematode control. Copyright © 2011 Society of Chemical Industry 相似文献
83.
Chérif N Thiéry R Castric J Biacchesi S Brémont M Thabti F Limem L Hammami S 《Veterinary research communications》2009,33(4):345-353
Viruses belonging to the Nodaviridae family cause disease worldwide among a large number of species of marine fish, and have
been described in all continents. In the present study, a total of 69 farmed Tunisian sea bass (Dicentrarchus labrax) and
24 sea bream (Sparus aurata) samples were tested monthly for the detection of betanodavirus. The virus was identified in both
species using indirect immunofluorescence assays (IFAT) and RT-PCR. In addition sequence analysis of part of the coat protein
gene indicated that both species were infected by highly related, but distinct, strains belonging to the RGNNV genotype. The
sequence of the coat protein gene of several strains was identical but up to 9 different sequences were detected in a single
farm. In addition, viral sequences obtained from fish that were held at lower temperature (<20°C) were distinct from the rest
of the sequences. 相似文献
84.
85.
Species that belong to the genus Triticum L. and the genetically related Aegilops L. genus are important genetic and economic resources because they have an evolutionary relationship with the two main agricultural
crops T. aestivum (bread wheat) and T. durum (durum wheat). Therefore, it is important to understand the genetic relationships among the cultivated wheat species and
their wild relatives. The latter have a great role in the improvement of cultivated wheat. Molecular markers are the best
choice and most reliable means to study these relationships accurately. In this study, we compared the efficiency of the biochemical
methods A–PAGE and SDS–PAGE on seed storage proteins and the molecular methods RAPDs and ISSRs to explore the genetic relationships
among seven species of Triticum and 20 Aegilops species. Three phylogenetic trees obtained in this study were compared with available classifications and phylogenetic trees
constructed earlier for these species. It was noted that the tree based on ISSRs data was the most congruent with those classification
and trees. This may be attributed to the fact that ISSRs is more specific, and therefore more reliable. This study is the
first to study genetic relationships among all species studied here using biochemical and molecular techniques. 相似文献
86.
KAMALI Nadia 《干旱区科学》2020,12(4):690-700
Wind erosion is one of the main drivers of soil loss in the world, which affects 20 million hectare land of Iran. Besides the soil loss, wind erosion contributes to carbon dioxide emission from the soil into the atmosphere. The objective of this study is to evaluate monthly and seasonal changes in carbon dioxide emission in four classes i.e., low, moderate, severe and very severe soil erosion and the interactions between air temperature and wind erosion in relation to carbon dioxide emission in the Bordekhun region, Boushehr Province, southwestern Iran. Wind erosion intensities were evaluated using IRIFR (Iran Research Institute of Forests and Ranges) model, in which four classes of soil erosion were identified. Afterward, we measured carbon dioxide emission on a monthly basis and for a period of one year using alkali traps in each class of soil erosion. Data on emission levels and erosion classes were analyzed as a factorial experiment in a completely randomized design with twelve replications in each treatment. The highest rate of emission occurred in July (4.490 g CO2/(m2?d)) in severely eroded lands and the least in January (0.086 g CO2/(m2?d)) in low eroded lands. Therefore, it is resulted that increasing erosion intensity causes an increase in soil carbon dioxide emission rate at severe erosion intensity. Moreover, the maximum amount of carbon dioxide emission happened in summer and the minimum in winter. Soil carbon dioxide emission was just related to air temperature without any relationship with soil moisture content; since changes of soil moisture in the wet and dry seasons were not high enough to affect soil microorganisms and respiration in dry areas. In general, there are complex and multiple relationships between various factors associated with soil erosion and carbon dioxide emission. Global warming causes events that lead to more erosion, which in turn increases greenhouse gas emission, and rising greenhouse gases will cause more global warming. The result of this study demonstrated the synergistic effect of wind erosion and global climate warming towards carbon dioxide emission into the atmosphere. 相似文献
87.
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89.
Mohamed Boukharta Nadia Touil Elmostafa El Fahim Meriame Terta Bachir Kissi Chafiqua Loutfi Mehdi El Harrak My Mustapha Ennaji 《Journal of Equine Veterinary Science》2014
Reported here are the results of antigenic and genetic characterization of equine influenza strains causing local outbreaks reported in Morocco, respectively, in 1997 and 2004. The antigenic and genetic characterizations of the equine influenza virus H3N8 are reported here. The highest similarity between the HA1 nucleotide sequences of A/equine/Nador/1/1997 and those of A/equine/Rome/5/1991 and A/equine/Italy/1199/1992 demonstrate that A/equine/Nador/1/1997 belongs to the European lineage. On the other hand, A/equine/Essaouira/2/2004 and A/equine/Essaouira/3/2004 were classified in the predivergent lineage. The present work emphasizes the importance of a national influenza survey program, which requires a collaborative laboratory network to promote the collection and characterization (antigenic and genetic) of equine influenza viruses in real time. 相似文献
90.
Nadia T. Rubio-Cisneros Octavio Aburto-Oropeza Jason Murray Charlotte E. Gonzalez-Abraham Jeremy Jackson Exequiel Ezcurra 《Human Dimensions of Wildlife》2014,19(1):1-16
This article explores transnational ecosystem services in North America, provided by winter habitat for waterfowl in western Mexico coastal lagoons, and the hunting industry supported by these birds in the United States. This article shows that the number of waterfowl harvested in the United States is related to the abundance of waterfowl wintering in Mexico. On average, this flow of ecosystem services annually yields US$ 4.68 million in hunting stamp sales in the western United States. A demand curve, fitted to duck hunting licenses as a function of stamp price and previous-year waterfowl harvest, estimated US$3–6 million in consumer surplus produced in addition to governmental stamp sales revenue. This strongly suggests that waterfowl wintering habitat in western Mexico is economically valuable to U.S. hunters. Because hunters may benefit substantially from these habitats they may be willing to pay for conservation efforts in western Mexico that can result in transnational benefits received in the United States. 相似文献