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131.
A population of the gill parasite Hatschekia pagellibogneravei (Hesse, 1878) was studied on one of its sparid fish hosts, the blackspot seabream, Pagellus bogaraveo (Brünnich), off the coast of Madeira Island, Portugal, northeast Atlantic. Very high infection levels of this copepod were detected, with no significant seasonal differences. Abundance was negatively correlated with fish size. There were significant differences in the distribution of this copepod among the gill arches of the host, which seem to be best explained by differences in water flow within the gill habitat. 相似文献
132.
Carlos Gutiérrez-Gutiérrez Carolina Cantalapiedra-Navarrete Wilfrida Decraemer Nicola Vovlas Tom Prior Juan E. Palomares Rius Pablo Castillo 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(3):561-597
During nematode surveys in southern Spain and Italy 14 populations of Xiphinema species tentatively identified as Xiphinema americanum-group were detected. Morphological and morphometrical studies identified three new species and six known Xiphinema americanum-group species, viz.: Xiphinema parabrevicolle n. sp., Xiphinema parapachydermum n. sp., Xiphinema paratenuicutis n. sp., Xiphinema duriense, Xiphinema incertum, Xiphinema opisthohysterum, Xiphinema pachtaicum, Xiphinema rivesi, and Xiphinema santos. The Xiphinema americanum-group is the most difficult Xiphinema species group for diagnosis since the morphology is very conservative and morphometric characters often overlap. This group includes vectors of several important plant pathogenic viruses that cause significant damage to a wide range of agricultural crops. Molecular characterisation of these species using D2-D3 expansion regions of 28S rRNA, 18S rRNA, ITS1-rRNA and the protein-coding mitochondrial gene, cytochrome oxidase c subunit 1 was carried out and maximum likelihood and Bayesian inference analysis were used to reconstruct phylogenetic relationships among these species and with other Xiphinema americanum-group species. 相似文献
133.
Radiative absorption enhancements due to the mixing state of atmospheric black carbon 总被引:3,自引:0,他引:3
CD Cappa TB Onasch P Massoli DR Worsnop TS Bates ES Cross P Davidovits J Hakala KL Hayden BT Jobson KR Kolesar DA Lack BM Lerner SM Li D Mellon I Nuaaman JS Olfert T Petäjä PK Quinn C Song R Subramanian EJ Williams RA Zaveri 《Science (New York, N.Y.)》2012,337(6098):1078-1081
Atmospheric black carbon (BC) warms Earth's climate, and its reduction has been targeted for near-term climate change mitigation. Models that include forcing by BC assume internal mixing with non-BC aerosol components that enhance BC absorption, often by a factor of ~2; such model estimates have yet to be clearly validated through atmospheric observations. Here, direct in situ measurements of BC absorption enhancements (E(abs)) and mixing state are reported for two California regions. The observed E(abs) is small-6% on average at 532 nm-and increases weakly with photochemical aging. The E(abs) is less than predicted from observationally constrained theoretical calculations, suggesting that many climate models may overestimate warming by BC. These ambient observations stand in contrast to laboratory measurements that show substantial E(abs) for BC are possible. 相似文献
134.
135.
Tor Espen Thorvaldsen Ane N?dtvedt Tom Grotmol Gjermund Gunnes 《Acta veterinaria Scandinavica》2012,54(1):52
Background
Seminomas in the dog have traditionally been assumed to resemble human spermatocytic seminomas, based on their low malignancy and high occurrence in old individuals. However, recently published studies indicate that canine seminomas can be classified as classical and spermatocytic seminomas in a similar way as in man, and that classical seminomas comprise a substantial proportion of seminomas in the dog. These two factors both contribute to increasing the potential of canine seminoma as a relevant model for human testicular cancer. The aim of the present study was to characterise seminoma in Norwegian dogs using morphology and immunohistochemistry, and determine whether these tumours are comparable with human classical seminoma.Methods
By applying diagnostic criteria from human pathology, 45 seminomas from the Norwegian Canine Cancer Register were examined histologically with hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) stains. All sections were stained immunohistochemically with antibodies against human placental alkaline phosphatase (PLAP) and the transmembrane receptor c-KIT.Results
Although two of the seminomas showed immunohistochemical staining characteristics indicative of classical seminoma (PLAP+/c-KIT+), all 45 examined seminomas were morphologically consistent with spermatocytic seminoma.Conclusions
The value of canine seminoma as a model for SE in man remains unclear. Among the 45 investigated tumours from Norwegian dogs, none were classified as classical seminoma based on morphological criteria consistent with human seminomas. Regional or breed differences in the occurrence of classical seminoma in the dog, as well as the lack of uniform diagnostic criteria, might explain the discrepancy between the findings in the current study and the results presented by other authors. 相似文献136.
Mikaela Schmitt-Harsh Tom P. Evans Edwin Castellanos J. C. Randolph 《Agroforestry Systems》2012,86(2):141-157
Tree removal in Latin American coffee agroforestry systems has been widespread due to complex and interacting factors that include fluctuating international markets, government-supported agricultural policies, and climate change. Despite shade tree removal and land conversion risks, there is currently no widespread policy incentive encouraging the maintenance of shade trees for the benefit of carbon sequestration. In facilitation of such incentives, an understanding of the capacity of coffee agroforests to store carbon relative to tropical forests must be developed. Drawing on ecological inventories conducted in 2007 and 2010 in the Lake Atitlán region of Guatemala, this research examines the carbon pools of smallholder coffee agroforests (CAFs) as they compare to a mixed dry forest (MDF) system. Data from 61 plots, covering a total area of 2.24 ha, was used to assess the aboveground, coarse root, and soil carbon reservoirs of the two land-use systems. Results of this research demonstrate the total carbon stocks of CAFs to range from 74.0 to 259.0 Megagrams (Mg)?C ha?1 with a mean of 127.6?±?6.6 (SE)?Mg?C ha?1. The average carbon stocks of CAFs was significantly lower than estimated for the MDF (198.7?±?32.1?Mg?C?ha?1); however, individual tree and soil pools were not significantly different suggesting that agroforest shade trees play an important role in facilitating carbon sequestration and soil conservation. This research demonstrates the need for conservation-based initiatives which recognize the carbon sequestration benefits of coffee agroforests alongside natural forest systems. 相似文献
137.
The landscape matrix modifies the effect of habitat fragmentation in grassland butterflies 总被引:1,自引:0,他引:1
Erik ?ckinger Karl-Olof Bergman Markus Franzén Tomá? Kadlec Jochen Krauss Mikko Kuussaari Juha P?yry Henrik G. Smith Ingolf Steffan-Dewenter Riccardo Bommarco 《Landscape Ecology》2012,27(1):121-131
The landscape matrix is suggested to influence the effect of habitat fragmentation on species richness, but the generality
of this prediction has not been tested. Here, we used data from 10 independent studies on butterfly species richness, where
the matrix surrounding grassland patches was dominated by either forest or arable land to test if matrix land use influenced
the response of species richness to patch area and connectivity. To account for the possibility that some of the observed
species use the matrix as their main or complementary habitat, we analysed the effects on total species richness and on the
richness of grassland specialist and non-specialist (generalists and specialists on other habitat types) butterflies separately.
Specialists and non-specialists were defined separately for each dataset. Total species richness and the richness of grassland
specialist butterflies were positively related to patch area and forest cover in the matrix, and negatively to patch isolation.
The strength of the species-area relationship was modified by matrix land use and had a slope that decreased with increasing
forest cover in the matrix. Potential mechanisms for the weaker effect of grassland fragmentation in forest-dominated landscapes
are (1) that the forest matrix is more heterogeneous and contains more resources, (2) that small grassland patches in a matrix
dominated by arable land suffer more from negative edge effects or (3) that the arable matrix constitutes a stronger barrier
to dispersal between populations. Regardless of the mechanisms, our results show that there are general effects of matrix
land use across landscapes and regions, and that landscape management that increases matrix quality can be a complement to
habitat restoration and re-creation in fragmented landscapes. 相似文献
138.
Cryopreserved boar sperm is not used extensively for artificial insemination, owing to the poor fertility rates of the sperm after freezing and thawing. The sperm membrane is damaged as the cells are cooled from body temperature to 5°C (cold shock), as well as during the freeze–thaw process. Increasing the cholesterol content of boar sperm membranes could help them survive cryopreservation, similar to sperm from other species that are cold shock sensitive. The aim of this study was to determine the optimal cholesterol‐loaded cyclodextrin (CLC) concentration to use for boar sperm cryopreservation, and the influence of CLCs on the cryosurvival of sperm from boars classified as good or poor freezers. Treating boar sperm with 1 mg of CLC/120 × 106 sperm slightly improved (p < 0.05) the percentage of viable sperm after freezing–thawing. On the other hand, sperm, from both good and poor freezers, responded similarly to CLC treatment. Nevertheless, additional studies will be needed to study the effect of this treatment on other parameters of sperm quality. 相似文献
139.
140.
Butler CM Sloet van Oldruitenborgh-Oosterbaan MM Stout TA van der Kolk JH Wollenberg Lv Nielen M Jongejan F Werners AH Houwers DJ 《Veterinary journal (London, England : 1997)》2012,193(2):381-385
Equine piroplasmosis (EP) has not been considered indigenous in The Netherlands. However, following the detection of an apparently indigenous subclinical Babesia caballi infection in a horse on Schouwen-Duiveland (an island in the Zeeland Province), a survey was undertaken between May and September 2010 to assess the prevalence of the causative agents of EP in the South-West of The Netherlands. Blood samples from 300 randomly selected horses were tested for specific antibodies against Theileria equi and B. caballi using an indirect fluorescence antibody test (IFAT), and for parasite DNA using a specific polymerase chain reaction combined with reverse line blotting (PCR-RLB). Twelve of the horses (4%) were seropositive for EP. Of these, nine (75%) were positive (titre?1:160) for B. caballi alone and three (25%) were also positive for T. equi. PCR-RLB detected T. equi DNA in five horses (1.6%), two of which were seronegative. Four (1.3%) of the positive horses (three positive for T. equi and one for both B. caballi and T. equi) were considered truly indigenous. During the study, two indigenous ponies from a farm situated outside the sampling area were diagnosed with acute clinical piroplasmosis characterized by severe anaemia and pyrexia. Blood smears showed T. equi - like inclusions in red blood cells, and T. equi infection was confirmed in both ponies by PCR-RLB. The initial subclinical B. caballi infection, the survey results and the two acute clinical EP cases confirmed the autochthonous transmission of B. caballi and T. equi infections in The Netherlands. 相似文献