Acclimatation of three co-occurring tree species to water stress and their role as site indicators in mixed pine-oak forests in the Sierra Madre Oriental,Mexico     

Wibke Himmelsbach  Eduardo J. Treviño-Garza  Humberto González-Rodríguez  Marco A. González-Tagle  Marco V. Gómez Meza  Oscar A. Aguirre Calderón  A. Eduardo Estrada Castillón  Ralph Mitlöhner 《European Journal of Forest Research》2012,131(2):355-367

Water availability and salt excess are limiting factors in Mexican mixed pine-oak forest. In order to characterise the acclimatation of native species to these stresses, leaf water (Ψ_w) and osmotic potentials (Ψ_s) of Juniperus flaccida, Pinus pseudostrobus and Quercus canbyi were measured under natural drought and non-drought conditions under two different aspects in the Sierra Madre Oriental. Factorial ANOVA revealed significant differences in Ψ_w and Ψ_s between two aspects, species and sampling dates. In general, all species showed high predawn and low midday values that declined progressively with increasing drought and soil–water loss. Seasonal and diurnal fluctuation of Ψ_w and Ψ_s were higher for J. flaccida and Q. canbyi than for P. pseudostrobus. Leaf Ψ_w and Ψ_s were mainly correlated with soil water content, while Ψ_s of P. pseudostrobus were hardly correlated with environmental variables. Thus, species have different strategies to withstand drought. P. pseudostrobus was identified as a species with isohydric water status regulation, while J. flaccida and Q. canbyi presented water potential patterns typical for anisohydric species. The type of water status regulation may be a critical factor for plant survival and mortality in the context of climate change. Nevertheless, for precise conclusions about the advantages and disadvantages of each type, further long-term investigations are required.  相似文献   

A Conus regularis Conotoxin with a Novel Eight-Cysteine Framework Inhibits CaV2.2 Channels and Displays an Anti-Nociceptive Activity     

Johanna Bernáldez  Sergio A. Román-González  Oscar Martínez  Samanta Jiménez  Oscar Vivas  Isabel Arenas  Gerardo Corzo  Roberto Arreguín  David E. García  Lourival D. Possani  Alexei Licea 《Marine drugs》2013,11(4):1188-1202

A novel peptide, RsXXIVA, was isolated from the venom duct of Conus regularis, a worm-hunting species collected in the Sea of Cortez, México. Its primary structure was determined by mass spectrometry and confirmed by automated Edman degradation. This conotoxin contains 40 amino acids and exhibits a novel arrangement of eight cysteine residues (C-C-C-C-CC-CC). Surprisingly, two loops of the novel peptide are highly identical to the amino acids sequence of ω-MVIIA. The total length and disulfide pairing of both peptides are quite different, although the two most important residues for the described function of ω-MVIIA (Lys2 and Tyr13) are also present in the peptide reported here. Electrophysiological analysis using superior cervical ganglion (SCG) neurons indicates that RsXXIVA inhibits Ca_V2.2 channel current in a dose-dependent manner with an EC₅₀ of 2.8 μM, whose effect is partially reversed after washing. Furthermore, RsXXIVA was tested in hot-plate assays to measure the potential anti-nociceptive effect to an acute thermal stimulus, showing an analgesic effect in acute thermal pain at 30 and 45 min post-injection. Also, the toxin shows an anti-nociceptive effect in a formalin chronic pain test. However, the low affinity for Ca_V2.2 suggests that the primary target of the peptide could be different from that of ω-MVIIA.  相似文献   

Determinants of adoption of alternative response to foot and mouth disease: micro-level evidence of smallholder pastoralist in north East District,Botswana     

Masole  Charity  Ayuya  Oscar Ingasia  Moreki  John Cassius 《Tropical animal health and production》2019,51(2):373-382

Tropical Animal Health and Production - This paper examines factors influencing the adoption of alternative response to Foot and Mouth Disease (FMD) among smallholder beef producers in the dry...  相似文献   

Conception rates and calving intervals of different beef breeds at a farm in the semi-arid region of Namibia     

Samkange  Alaster  Kandiwa  Erick  Mushonga  Borden  Bishi  Alec  Muradzikwa  Erdwin  Madzingira  Oscar 《Tropical animal health and production》2019,51(7):1829-1837

Tropical Animal Health and Production - A retrospective study from 2004 to 2017 investigated the effect of bull age, cow age and breed on conception rates, and calving intervals of beef cattle at...  相似文献   

PALLIATIVE RADIOTHERAPY OF APPENDICULAR OSTEOSARCOMA IN 95 DOGS     

Oscar  Ramirez  III  DVM  Richard K.  Dodge  MS  Rodney L.  Page  DVM  MS  G. Sylvester  Price  DVM  PhD  Marlene L.  Hauck  DVM  PhD  Tracy A.  Ladue  DVM Felicia  Nutter  DVM  Donald E.  Thrall  DVM  PhD 《Veterinary radiology & ultrasound》1999,40(5):517-522

Ninety-five dogs with either a presumptive (n = 24) or biopsy confirmed diagnosis (n = 71) of osteosarcoma received palliative radiotherapy using 60Co photons. Parallel opposed beams were used with each dog receiving either 10 Gy on days 0, 7 and 21 (n = 58) or 8 Gy on days 0 and 7 (n = 37). The 8 Gy fractionation scheme was given with the intent of retreating upon relapse from pain relief. Only 9 of 37 (24%) dogs in the 8 Gy group returned for retreatment. Forty-seven of the 95 dogs (49%) received concurrent or sequential chemotherapy. Seventy of the 95 dogs (74%) experienced pain relief following treatment. In dogs experiencing pain relief the median duration of response was 73 days. Numerous clinical variables were evaluated as predictors of response. The only variable significantly related to achieving a response was the use of chemotherapy. The following variables were significantly related to the duration of response: extent of bone lysis, chemotherapy use, length of bone involved and tumor site (humerus). In a multivariate analysis (n = 73 dogs), after adjusting for chemotherapy use, extent of bone involvement (p = 0.01) and tumor site (p = 0.02) retained statistical significance, while degree of bone lysis did not (p = 0.11). No difference in response incidence or duration was found between 3 fractions of 10 Gy vs. 2 fractions of 8 Gy. Administration of a low initial dose with the intent of retreatment was not a successful strategy.  相似文献   

Confirmation of the spawning area of the striped marlin, Tetrapturus audax, in the so-called core area of the eastern tropical Pacific off Mexico     

Rogelio GonzÁlez Armas  Oscar Sosa-Nishizaki  RenÉ Funes RodrÍguez  & Victor AndrÉS Levy PÉrez 《Fisheries Oceanography》1999,8(3):238-242

We report the presence of striped marlin larvae in coastal waters of the mouth of the Gulf of California, collected during seven oceanographic cruises during 1990 to 1993. From 169 sampled stations, 30 produced a total of 68 larvae of 2.4–30.5 mm total length. Most of the larvae were about 3 mm, indicating a recent spawn. The sea surface temperature at the sampled stations ranged from 19.4°C to 32.0°C, but larvae were caught at stations with temperatures between 27.8°C and 31.5°C. These results clarify the existence of a spawning area of striped marlin in the eastern Pacific, located closer to the coast than previously believed, during several months of the year.  相似文献   

Genetic differentiation between and within ecotypes of pike (Esox lucius) in the Baltic Sea     

Oscar Nordahl  Per Koch‐Schmidt  Johanna Sunde  Yeerin Y&#x;ld&#x;r&#x;m  Petter Tibblin  Anders Forsman  Per Larsson 《水产资源保护:海洋与淡水生态系统》2019,29(11):1923-1935

Reducing copper use in the environment: the use of larixol and larixyl acetate to treat downy mildew caused by Plasmopara viticola in viticulture          下载免费PDF全文

Barbara Thuerig  Emily E James  Hans‐Jakob Schärer  Moses K Langat  Dulcie A Mulholland  Jonas Treutwein  Ina Kleeberg  Mathias Ludwig  Praveen Jayarajah  Oscar Giovannini  Emilia Markellou  Lucius Tamm 《Pest management science》2018,74(2):477-488

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Effect of potassium and manganese phosphites in the control of Pythium damping‐off in soybean: a feasible alternative to fungicide seed treatments          下载免费PDF全文

Marcelo A Carmona  Francisco J Sautua  Pablo E Grijalba  Mariano Cassina  Oscar Pérez‐Hernández 《Pest management science》2018,74(2):366-374

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RGB and multispectral UAV image fusion for Gramineae weed detection in rice fields   总被引：1，自引：0，他引：1  

Oscar Barrero  Sammy A. Perdomo 《Precision Agriculture》2018,19(5):809-822

In this paper, a new method to fuse low resolution multispectral and high resolution RGB images is introduced, in order to detect Gramineae weed in rice fields with plants at 50 days after emergence (DAE).The images are taken from a fixed-wing unmanned aerial vehicle (UAV) at 60 and 70 m altitude. The proposed method combines the texture information given by a high resolution red–green–blue (RGB) image and the reflectance information given by a low resolution multispectral (MS) image, to obtain a fused RGB-MS image with better weed discrimination features. After analyzing the normalized difference vegetation index (NDVI) and normalized green red difference index (NGRDI) for weed detection, it was found that NGRDI presents better features. The fusion method consists of decomposing the RGB image using the intensity, hue and saturation (IHS) transformation, then, a second order Haar wavelet transformation is applied to the intensity layer (I) and the NGRDI image. From this transformation, the low–low (LL) coefficients of the NGRDI image are replaced by the LL coefficients of the I layer. Finally, the fused image is obtained by transforming the new wavelet coefficients to RGB space. To test the method, a one hectare experimental plot with rice plants at 50 DAE with Gramineae weeds was selected. Additionally, to compare the performance of the method, two indices were used, specifically, the M/M_GT index which is the percentage of detected weed area, and the MP index which indicates the precision of weed detection. These indices were evaluated in four validation zones using three Neural Networks (NN) detection systems based on three types of images; namely, RGB, RGB + NGRDI, and fused RGB-NGRDI. The best weed detection performance was obtained by the NN with the fused image, with M/M_GT index between 80 and 108% and MP between 70 and 85%.  相似文献