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101.
102.
Kellen?Regina?Boldrini Eleniza?de?Victor Adamowski Hugo?Message Vergílio?Calisto Maria?Suely?PagliariniEmail author Cacilda?Borges?do?Valle 《Euphytica》2011,182(3):317-324
Brachiaria humidicola is a tropical grass that grows in seasonally swampy grasslands in Africa. In Brazil, two apomictic cultivars (2n = 54) of this species are widely used as pastures in poorly drained soils. The recent discovery of a sexual polyploid accession
(2n = 36) in the germplasm collection at the Embrapa Beef Cattle Research Center allowed intraspecific hybridization with the
objective of broadening the genetic variability and selection of superior genotypes in this species. Hybridization, however,
depends on accessions with the same ploidy level. Cytological analyses of 55 accessions revealed that 19 apomictic accessions
also presented 2n = 36 chromosomes. Chromosome pairing in hexavalent association at diakinesis and metaphase I suggested that the basic chromosome
number for this species is x = 6. Cytological analysis revealed abnormalities in variable frequencies in the meiosis of these hexaploid (2n = 6x = 36) accessions. The most common were those related to irregular chromosome segregation which led to unbalanced gamete formation,
but chromosome stickiness was also recorded. These results clearly demonstrate the value of cytogenetics in the choice of
genitors and for superior hybrids to be obtained in the breeding of this species. For that both the ploidy level and the frequency
of abnormalities need to be considered, besides other favorable agronomic characteristics. 相似文献
103.
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105.
Carmen Rocío Rodríguez Pleguezuelo Víctor Hugo Durán Zuazo José Ramón Francia Martínez José Luis Muriel Fernández Dionisio Franco Tarifa 《Irrigation and Drainage Systems》2011,25(2):61-79
Agricultural nonpoint-source pollution is the leading cause of water-quality degeneration of rivers and groundwater. In this
context, the coast of Granada province (SE Spain) is economically an important area for the subtropical fruit cultivation.
This intensively irrigated agriculture often uses excessive fertilizers, resulting to water pollution. Therefore, a 2-year
experiment was conducted using drainage lysimeters to determine the potential risk of nutrient pollution in mango (Mangifera indica L. cv. Osteen) and cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards. These lysimeters were used to estimate the nutrient budgeting for each crop. NO3-N, NH4-N, PO4-P and K losses according to lysimeters were, respectively, 55.1, 12.4, 3.7, and 0.6 for mango and 61.8, 17.8, 4.9, and 0.5 kg ha−1 yr−1, for cherimoya. NO3, concentrations in the leachates ranged from 1.8 to 44.3 mg L−1, and from 23.0 to 51.0 mg L−1, for mango and cherimoya, respectively, in some cases exceeding the limits for safe drinking water. PO4 also exceeded the permitted concentrations related to eutrophication of water, ranging from 0.07 to 0.5 mg L−1 and from 0.12 to 0.68 mg L−1 from mango and cherimoya lysimeters, respectively. With respect to the nutrient balance, N, P, and K removed by cherimoya
fruits was 76.4, 5.5, and 22.6 kg ha−1 yr−1, and for mango fruits 30.2, 3.3 and 27.8 kg ha−1 yr−1, respectively. Nutrient losses in the leachates were surprisingly low, considering total N, P, and K applied during the year,
in mango lysimeters 3.8, 0.11, and 12.6%, and in cherimoya lysimeters 7.7, 0.23 and 16.0%, respectively, indicating a potential
soil accumulation and eventual loss risk, especially during torrential rains. Crop coefficient (Kc) values of mango trees varied within ranges of 0.35–0.67, 0.55–0.89, and 0.39–0.80 at flowering, fruit set, and fruit growth,
respectively. Kc values for cherimoya trees had ranges of 0.58–0.67, 0.61–0.68, and 0.43–0.62 at flowering, fruit set and fruit growth, respectively.
In this study, the Kc values of mango and cherimoya were significantly correlated to julian days. Therefore, the estimated WUE in the mango and
cherimoya orchards reached 21.2 and 14.0 kg ha−1 mm−1, respectively. Thus, this study highlights the urgency to establish the optimal use of fertilizers and irrigation water with
respect to crop requirements, to preserve surface-water and groundwater quality, thereby achieving more sustainable agriculture
in orchard terraces. 相似文献
106.
Moran G Buechner-Maxwell VA Folch H Henriquez C Galecio JS Perez B Carrasco C Barria M 《Veterinary research communications》2011,35(7):447-456
Recurrent airway obstruction (RAO, also known as equine heaves) is an inflammatory condition similar to human asthma caused
by exposure of susceptible horses to poorly ventilated stable environments. The disease is characterized by neutrophilic airway
inflammation, mucus hypersecretion and reversible bronchoconstriction. This inflammatory process is mediated by several factors,
including antibodies, cytokines, resident cells of the airway and inflammatory cellular components that arrive in the respiratory
tract. An increasing body of evidence has lent support to the concept that a dysregulation of T cell apoptosis may play a
central role in the development of airway inflammation and the associated asthma. Therefore, the aim of this study was to
investigate early and late apoptosis of CD4 and CD8 T cell subpopulations obtained from the airways of acute RAO-positive
animals after exposure to hay/straw. The percentages of CD4 and CD8 T cells and their associated frequencies of apoptosis
were quantified using flow cytometry. Hay/straw exposure induced clinical airway obstruction, airway neutrophilia and increased
airway mucus production in RAO-positive horses. In addition, allergen exposure increased the percentage of CD4 T cells in
RAO-positive horses as well as the frequency of early and late apoptosis in both CD4 and CD8 lymphocyte subpopulations. These
results suggest that the higher frequency of lymphocyte apoptosis may play a role in disease progression of horses afflicted
with RAO and may partially explain the characteristic remission of this pathological condition once the allergen source is
removed. However, further studies are needed to clarify the role of T cell apoptosis in RAO-affected horses. 相似文献
107.
Castillo JA Medina RD Villalobos JM Gayosso-Vázquez A Ulloa-Arvízu R Rodríguez RA Ramírez HP Morales RA 《Veterinary parasitology》2011,177(3-4):339-344
The objective of this study was to assess the correlation among traits associated with resistance or susceptibility to Haemonchus contortus infestation and to evaluate the participation of the ovine major histocompatibility complex (MHC) in Pelibuey sheep, a prevalent breed in tropical and sub-tropical regions in Mexico and elsewhere. Association among the fecal egg count (FEC), blood packed cell volume (PCV), antibody (AB) levels, serum proteins (SP) and blood eosinophil count (EOS) was assessed in 52 lambs experimentally infected with H. contortus, and the participation of the MHC was evaluated using polymorphisms in three microsatellites, located at the class I (OMHC1) and class II (OLADRB1, OLADRB2) regions of the MHC. Spearman correlation analysis among the traits showed a negative association (P<0.01) between FEC and PCV (-0.35), EOS (-0.50), SP (-0.30) and AB (-0.57), and a positive correlation of antibodies with EOS (0.50). The homozygotes for the OMHC1-188 and OLADRB2-282 alleles were associated with a reduction in FEC (-813 and -551, respectively). Conversely, the OMHC1-200 and OMHC1-206 alleles were associated with an increase in FEC (1704 and 1008, respectively). Furthermore, the OLADRB1-482 allele was associated with an increase of 163 EOS by allele copy, while the OMHC1-200 allele showed a reduction of 95 EOS in homozygotes. The associations among microsatellite MHC loci and the remaining variables were not significant. These results reinforce the evidence that MHC polymorphisms have an important role in parasite resistance or susceptibility in Pelibuey sheep and could be used as genetic markers to assist selection and improve parasite resistance to H. contortus. 相似文献
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109.
Churria CD Spinsanti E Origlia J Marcantoni H Piscopo M Loyola MH Petruccelli M 《Journal of zoo and wildlife medicine》2011,42(1):164-165
Two adult male Crimson rosellas (Platycercus elegans) and an adult female eastern rosella (Platycercus eximius) were found dead in their cages in a private aviary in March 2009, April 2010, and February 2010, respectively, without premonitory signs. Their postmortem examination showed pectoral muscle atrophy and a distended proventriculus. The proventricular mucosal surface was covered with a gelatinous, whitish material, where a large number of nematode parasites identified as Dispharynx nasuta were present. A histologic examination revealed a hyperplastic mucosa, spirurid nematodes in the mucosal layer and inflammatory mononuclear cells in the lamina propria. This is the first report of a D. nasuta infection associated with proliferative proventriculitis and subsequent death in psittacine birds. 相似文献
110.
Mendoza-Magaña ML Godoy-Martinez DV Guerrero-Cazares H Rodriguez-Peredo A Dueñas-Jimenez JM Dueñas-Jiménez SH Ramírez-Herrera MA 《Veterinary journal (London, England : 1997)》2007,173(2):428-436
Pig neural cells express glycoproteins with sialylated N-linked oligosaccharide chains (SNOC) which are used by the porcine rubulavirus (PoRv) as receptors. Pig neuronal or glial cell cultures were employed to investigate (a) whether PoRv infects such cells using a molecule expressing SNOC, and (b) the role of viral envelope glycoproteins in establishing the infection. Enriched neuronal or glial cell cultures were exposed to PoRv and infection was detected immunocytochemically. Neuronal cultures prepared from neonatal pigs were treated enzymatically to eliminate sialic acid or N-linked oligosaccharide chains. Primary neural cultures were exposed to anti-HN or anti-F preincubated with PoRv to study the role of the viral glycoproteins. In enriched cultures, PoRv infected neurons and glial cells, and sialic acid expressed in N-linked oligosaccharide chains appeared to play a central role in infection. It was concluded that HN and F viral glycoproteins are required to infect neurons and glial cells. 相似文献