Veterinary Research Communications - Endometrial epithelial cells play a key defensive role as part of the innate immune response of cow uterus. An association between risk of acquiring infectious... 相似文献
ObjectiveTo evaluate clinical effects of romifidine and low doses of tiletamine‐zolazepam (TZ) in dogs.Study designRandomized “blinded” cross‐over study.AnimalsSix healthy beagle dogs (two males, four females).MethodsIn separate preliminary experiments dogs received intravenous (IV) tiletamine‐zolazepam (TZ) at 1 and 2 mg kg?1. For the main trial, dogs received romifidine (R) followed 5 minutes later by IV at six dose regimens: R40TZ1, R60TZ1, R80TZ1 (Romifidine at 40, 60, 80 μg kg?1 and TZ at 1 mg kg?1), R40TZ2, R60TZ2 and R80TZ2 (Romifidine at 40, 60, 80 μg kg?1 and TZ at 2 mg kg?1). Dogs underwent endotracheal intubation, but breathed room air. Cardiorespiratory variables were measured and arterial blood analyzed. Quality of sedation, duration of anaesthesia and time to recovery (TR) were recorded. Data were analysed by anova or Friedman test as relevant.ResultsEndotracheal intubation was possible with all romifidine/TZ combinations but not with TZ alone. Mean times (minutes) from TZ injection to return of pedal reflex were 1–3 minutes for TZ alone, and 9–17 minutes for romifidine combinations. In the main trial (romifidine combinations) mean time (minutes) to standing increased with increasing dosage (R40TZ1 13; R80TZ2 32). Five minutes after TZ administration, when compared with baseline arterial blood pressures and arterial carbon dioxide had increased, and respiratory rate, pH and arterial oxygen tensions decreased, these changes becoming statistically significant with the higher dose rates. One dog in R60TZ2 and three dogs in R80TZ2 became hypoxaemic.Conclusions and clinical relevanceRomifidine improves the quality and lengthens the duration of anaesthesia induced by TZ. The combination provides a suitable protocol for induction of or short‐term anaesthesia in healthy dogs. However, the higher doses cause cardiovascular stimulation and respiratory depression, and precautions should be taken accordingly. 相似文献
The aim of this work was to evaluate the effects of high temperatures in the pre-blooming and blooming periods on the growth of sexual gametes and yield of ‘Granada’ peach. The experiment was carried out in the commercial orchard of Charqueadas, under the subtropical conditions of the Central Depression at Rio Grande do Sul State, Brazil (28°57′S; 51°37′W; 30 m alt.). Two treatments were tested: (1) trees in the greenhouse with partial ventilation and (2) trees in the orchard. The phenology, morphologic constitutions of the pollen grains, ovule growth, yield and germination (%) of pollen grains and fruit set were evaluated. High temperatures in the pre-blooming and blooming periods anticipated the break of dormancy and blooming. These conditions also delayed the female gametophytes (embryo sac) and promoted anomalies in the formation of male gametophytes. Those factors promoted low pollen viability and a lack of synchrony in fertilization, thereby generating low fruit set percentages and yield. 相似文献
Relatively few studies have documented the impacts of afforestation, particularly production forestry, on belowground carbon dioxide (CO2) effluxes to the atmosphere. We evaluated the changes in the soil CO2 efflux—a proxy for soil respiration (Rs)—for three years following a native grassland conversion to eucalypt plantations in southern Brazil where minimum tillage during site preparation created two distinct soil zones, within planting row (W) and between-row (B). We used root-exclusion and carbon (C)- isotopic approaches to distinguish Rs components (heterotrophic-Rh and autotrophic-Ra respirations), and a CO2 profile tube (1-m deep) to determine the concentration ([CO2]) and isotopic C signature of soil CO2 (δ13[CO2]). The soil CO2 efflux in the afforested site averaged 0.37 g CO2 m?2 h?1, which was 56% lower than the soil CO2 efflux in the grassland. The δ13CO2 in the afforested site ranged from ? 14.1‰ to ? 29.4‰, indicating a greater contribution of eucalypt-derived respiration (both Rh and Ra) over time. Higher soil CO2 efflux and lower [CO2] were observed in W than B, indicating that soil preparation creates two distinct soil functional zones with respect to C cycling. The [CO2] and δ13[CO2] decreased in both zonal positions with eucalypt stand development. Although the equilibrium in C fluxes and pools across multiple rotations is needed to fully account for the feedback of eucalypt planted forests to climate change, we provide quantitative information on soil CO2 dynamics after afforestation and show how soil preparation can leverage the feedback of planted forests to climate change.
Tree populations at the rear edge of species distribution are sensitive to climate stress and drought. However, growth responses of these tree populations to those stressors may vary along climatic gradients.
Aims
To analyze growth responses to climate and drought using dendrochronology in rear-edge Pinus nigra populations located along an aridity gradient.
Methods
Tree-ring width chronologies were built for the twentieth century and related to monthly climatic variables, a drought index (Standardized Precipitation–Evapotranspiration Index), and two atmospheric circulation patterns (North Atlantic and Western Mediterranean Oscillations).
Results
Growth was enhanced by wet and cold previous autumns and warm late winters before tree-ring formation. The influence of the previous year conditions on growth increased during the past century. Growth was significantly related to North Atlantic and Western Mediterranean Oscillations in two out of five sites. The strongest responses of growth to the drought index were observed in the most xeric sites.
Conclusion
Dry conditions before tree-ring formation constrain growth in rear-edge P. nigra populations. The comparisons of climate-growth responses along aridity gradients allow characterizing the sensitivity of relict stands to climate warming. 相似文献
Nothofagus nitida (Phil.) Krasser, an emergent tree of the Chilean evergreen forest, regenerates under the canopy. Nonetheless, it is common to find older saplings in clear areas. We hypothesized that this transition from shade to sun during the early developmental stages is made possible by an ontogenetic increase in the light acclimation capacity of photosynthesis. To test our hypothesis, we studied photosynthetic performance and photoprotection in N. nitida saplings at different developmental stages corresponding with three different height classes (short: 16.2 cm; medium-height: 48.0 cm; and tall: 73.7 cm) grown under contrasting light conditions (photosynthetic photon flux (PPF) of 20, 300 or 600 micromol m(-2) s(-1)) until newly expanded leaves had developed. Light-saturated CO(2) assimilation rate and light compensation and saturation points increased with increasing PPF. Medium-height and tall saplings acclimated to high light had higher electron transport rates and higher proportions of open Photosystem II reaction centers than shorter plants acclimated to high light. Short saplings showed higher thermal dissipation and contents of xanthophylls than taller saplings. Only medium-height and tall saplings acclimated to high light recovered after photoinhibition. State transitions were higher in short plants growing in low light, and decreased with plant height and growth irradiance. Thus, during development, N. nitida changes the balance of light energy utilization and photoprotective mechanisms, supporting a phenotypic transition from shade to sun during its early ontogeny. 相似文献
Six kinds of extracts drawn fromAjuga multiflora andA. multiflora var.brevispicata and A. multiflora var.serotina using methanol and acetone were used in this experiment to test their killing activity to the second instar larvae ofHyphantria cunea and their influence on its natural enemies. The average death rate caused by those extracts on the second instar larvae was
85.70%. The mortality rate caused by the extracts drawn with methanol was from 88.89% to 96.33%, which was significantly higher
than that caused by acetone extracts. Those extracts were safe toTrichogramma dendrolimi, Coccinella septempunctata, the natural enemies ofH. cunea. We did not found any evidence shown that those extracts had any influence the emergence and the development ofT. dendrolimi. Those methanolic extracts gotten fromA. multiflora andA. multiflora var.brevispicata had no significant effects on the mortality of the larvae and adults ofC. septempunctata. Those extracts could be used in the control ofH. cunea safely.
The research was sponsored by National Nature Science Fundation (39470586)
(Responsible Editor: Chai Ruihai) 相似文献
Journal of Pest Science - We evaluated the lethal and sublethal effects of azoxystrobin, cyhalofop-butyl, and thiamethoxam on Telenomus podisi after spraying rice plants in a greenhouse, as well as... 相似文献
The limited ability of Quercus species to regenerate naturally in Mediterranean forests has led to the development of various artificial regeneration methods;
however, there is no general consensus as to what specific method is the best one for this purpose. 相似文献
The present study aimed to assess the lethal and sublethal responses of five populations of S. zeamais to the essential oils of Ocimum basilicum and Piper hispidinervum, through toxicity, locomotor behavior (flight and walking activities) and physiological (respiration rate and body mass) evaluations. The populations of S. zeamais were obtained from Machado—MG, Paracatu—MG, Piracicaba—SP, Recife—PE and Tunápolis—SC. To estimate the LC50 of each oil for each population, fumigation tests were performed. The population from Recife exhibited the lowest instantaneous rate of increase (ri) as well the lowest consumption of grain mass. However, Piracicaba was considered the susceptibility pattern, presenting the lowest LC50 for both essential oils, no statistical difference was observed among populations or treatments in the flight activity bioassays. The essential oils effect on walking activity and respiration rates varied among populations. The population from Recife presented the highest walked distance and walk speed, with the lowest resting time and number of stops, as well as the lowest respiration rate and body mass. The present study highlights the importance of the study on population responses, as the five populations of S. zeamais exhibited different patterns of toxic and behavioral effects when subjected to the essential oils of P. hispidinervum and O. basilicum. 相似文献