The influence of various confounding factors on mechanical nociceptive thresholds in the donkey

ObjectiveTo evaluate a mechanical nociceptive threshold (MNT) testing device in the donkey, and to investigate the influence of potential confounders on MNTs generated.Study designProspective, randomised.AnimalsSixteen castrated male donkeys aged 4–9 years, weighing 105–170 kg.MethodsMechanical nociceptive thresholds were measured using an actuator with three pins placed on the dorsal aspect of the distal limb, connected to a force meter. The pins (surface area 15 mm²) were extruded onto the limb by pressurising an air-filled syringe, until the MNT force (when foot-lift was observed) or 25 N (cut-off force) was reached. Effect on MNT of presence of a companion donkey, the limb tested, rate of application of force, testing location, level of distraction, ambient temperature and hair cover at the test site was evaluated. Long and short-term repeatability of MNT was assessed. Data were analysed using general linear models and Mann–Whitney U tests, p < 0.05 was considered significant.ResultsIncreasing the rate of force application significantly increased the mean ± SD MNT from 9.2 ± 2.0 N when applied at 0.4 N sec^?1 to 10.6 ± 2.1 N when applied at 1.2 N sec^?1 (p = 0.001). No other factors significantly influenced MNT. Mean MNT remained stable over a 3 week period, however MNTs were significantly (p = 0.006) higher (12.8 ± 3.0 N cf 10.3 ± 1.9 N) after a 12 month interval.Conclusions and clinical relevanceWhen designing studies measuring MNT in donkeys, rate of application of force must be standardised. Donkeys’ MNTs have good short-term stability suggesting this technique is appropriate for short-term analgesiometry studies; however variability of MNTs over the long-term is greater.     

昆虫病原线虫JLSY 003的鉴定及其生物学特性测定

经28S rDNA和ITS序列分析,从吉林省松原市土样中分离到的昆虫病原线虫JLSY 003为Oscheius myriophila品系。本研究以大蜡螟末龄幼虫为寄主,测定该线虫的生物学特性。结果表明,JLSY 003浓度为80 IJs/larva时具有较高的侵染力,致死中时间LT₅₀为15.409 h,侵染24、48 h时,致死中浓度LC₅₀分别为46.067、25.297 IJs/larva。JLSY 003高温耐受性强且繁殖力高,36 ℃、8 h时线虫死亡率为19.27%,产量为1.873×10⁵ IJs/larva,4.695×10⁵ IJs/g。结果表明该线虫具有较高的致病力、耐热性和繁殖力。     

Consistent responses of yield and resistance of wheat cultivars to the root-lesion nematode,Pratylenchus thornei,in the Australian northern subtropical region,but not in the temperate southern region

To understand the yield response of cereal cultivars to Pratylenchus thornei, eight experiments were conducted within the subtropical northern, and temperate southern grain-producing regions of Australia. Wheat cultivars (Triticum aestivum) ranging from susceptible to moderately resistant to P. thornei were grown in Year 1 to establish a range of population densities. In Year 2 before sowing, P. thornei was quantified in each plot and six cereal cultivars were each grown on a similar range of population densities (average minimum to maximum of 3.4–60.6 P. thornei/g soil); P. thornei was quantified again at harvest. In the four experiments in the northern region there was a significant, negative logarithmic response of yield of the three most intolerant/susceptible cultivars as P. thornei population densities increased (yield decreased 172–479 kg/ha per unit increase in log_e-transformed P. thornei/g soil). The responsiveness of yield to increasing P. thornei population densities diminished as the tolerance and resistance of the cultivars improved. In the southern region, there was no relationship between yield and P. thornei in three experiments and minor, positive increases in one experiment (1.6 kg/ha per unit increase in P. thornei/g soil). Across both regions, the change in P. thornei population densities from sowing to harvest was logarithmic and positive, and generally greatest in the northern region. The contrast of responses of cereal cultivars between the regions, despite similar population densities of P. thornei, is indicative of the influence of the environment particularly on tolerance, therefore management with a regional focus is essential.     

新疆哈密瓜苗期耐冷性评价

为了挖掘新疆哈密瓜耐冷资源,为设施耐冷品种的选育提供研究基础,笔者以14份哈密瓜为试材,采用人工模拟低温的方法,在4℃低温处理下,测定相关生长、生理指标,并采用主成分分析和隶属函数分析,对14份哈密瓜幼苗的耐冷性进行综合评价。对原有的12个单项指标进行主成分分析,得到5个新的相互独立的综合指标;通过聚类分析,把所有品种分为3类。其中,阿克陶1号等3个品种为耐冷性强的品种,西开心等8个品种为中度耐冷品种,其里甘等3个品种为冷敏感品种;通过逐步回归分析,建立了评估哈密瓜苗期耐冷性的数学模型:D=-0.31+0.62RDW0.18SPC+0.10SSC-0.21SOD,并筛选出根干质量、可溶性蛋白含量、可溶性糖含量、超氧化物歧化酶活性等4个指标可作为哈密瓜苗期耐冷性评价的有效指标。     

VA 菌根真菌对酸枣实生苗抗旱性的影响

 在盆栽条件下, 研究了VA 菌根对酸枣实生苗生长和抗旱性的影响。结果表明, 在土壤相对含水量为20 %、40 %、60 %条件下, VA 菌根能显著增加酸枣实生苗的生长量(株高、叶面积、鲜样质量、干样质量等) , 降低叶片自然饱和亏和脯氨酸含量, 提高植株叶片气孔导度、蒸腾速率、光合速率, 显著增强了植株的抗旱能力。在土壤相对含水量相同状况下, 接种菌根真菌植株制造1 g 干物质的需水量低于不接种的处理, 节水效果为16. 5 %～29. 8 %。干旱条件对VA 菌根的侵染影响不大。播种时进行控水处理和在播种后40 d 开始控水两个水分试验对菌根的侵染率、植株的生长及水分状况影响差异不大。     

等渗Ca(NO3)2和NaCl对番茄幼苗生长的影响

 等渗Ca(NO₃)₂和NaCl溶液对番茄幼苗具有不同的盐效应。28、56 mmol/L Ca (NO₃)₂溶液对其生长的抑制作用小于等渗的NaCl 溶液, 而84 mmol/L Ca (NO₃)₂溶液对幼苗生长的抑制程度与等渗的NaCl 溶液无显著差异。Ca(NO₃)₂主要通过渗透胁迫影响植株生长;而NaCl主要通过离子胁迫抑制植株的生长, 包括细胞质膜结构的破坏和K吸收的减少。     

Managing Grazing Intensity Linked to Forage Quantity and Quality Trade-off in Semiarid Rangelands

Knowledge of herbivory tolerance of dominant plant species and their responses to varying grazing intensity is required for sustainable grazing management in semiarid rangeland ecosystems. In a field experiment, we studied the effects of simulated grazing 0%, 30%, 50%, and 80% leaf removal (control, partial, intermediate, and heavy leaf removal) of three dominant perennial legumes: Astragalus cyclophyllon, Astragalus effuses, and Hedysarum criniferum in semiarid rangelands of southwestern Iran for 2 yr and tested 1) differential herbivory tolerance in terms of regrowth ability of belowground and aboveground biomass (AGB), fecundity, and nonstructural carbohydrate reserves; and 2) trade-off between forage quantity and quality—less defoliated plants produce larger amount of biomass with less forage quality and vice versa. The results showed a reduction in AGB and reproduction in each of the three plants. However, three forbs exhibited some sort of variations in shoot and root growth, reproduction and forage quality under intermediate and heavy leaf removal. Leaf removal in individuals of A. effusus and H. criniferum are more likely to compensate for tissue loss by allocating the available resources to the expansion of root biomass, at the cost of AGB and reproductive effort. Leaf removal also led to an increase in forage quality in each of the three forb species, depending on the level of height removal. The control plant had a higher amount of biomass production and lower amount of crude protein compared with heavy leaf removal treatments (i.e., 80%), by contrasting responses of acid detergent fiber and neutral detergent fiber, indicating a trade-off between forage quality and forage quantity. The results indicate that there is a balance among forage quantity, quality, and regrowth ability of belowground and aboveground tissues in intermediate leaf removal treatments of these forb species. This balance is used to develop principles for grazing management of steppe rangelands because such a regime meets different criteria including forage quantity, quality, and nonstructural carbohydrate reserves.     

Low pH and aluminum tolerance of Bradyrhizobium strains isolated from acid soils in Indonesia

Sixty-seven strains of Bradyrhizobium isolated from soybean plants growing on acid soils in West Java and Sumatra, Indonesia, were examined for the effect of the pH and aluminum concentration on their growth in nutrient media, compared with 61 strains of Bradyrhizobium from soils in Japan. The results in this study indicated that the indigenous population of Bradyrhizobium in the soils of Indonesia showed a large difference in acid- and Al-tolerance from that of Japan. Eighty-five and 48% of the isolates from Japanese soils and Indonesian soils, respectively, were unable to grow in YEM broth at pH below 4.5. The acid-tolerance was correlated with AI-tolerance of the isolates on YEM agar plates at pH 4.4. Seventy-five percent of the isolates that grew in YEM broth at pH 4.5 were also resistant to 400 µM Al on the YEM plates. Acetylene reduction assay of the root nodules revealed that 3 of the acid- and Al-tolerant isolates from Indonesian soils showed a significantly high nitrogen fixation activity.     

The plasma membrane intactness of root-tip cells is a primary factor for Al-tolerance in cultivars of five species

We investigated the role of the cell wall and plasma membrane (PM) of root-tip cells in Al tolerance in Al-tolerant and Al-sensitive cultivars of five plant species (rice, maize, pea, wheat, and sorghum). No correlation was found between the differences in Al tolerance and the cation exchange capacity of cell walls isolated from root-tips (0–1 em). Preliminary exposure to Al for 1 h was sufficient to inhibit subsequent root re-elongation in an Al-free solution, and the inhibitory effect was more pronounced in the Al-sensitive cultivars than in the Al-tolerant ones. Together with the inhibition of root re-elongation, the PM of the root-tip cells of all the Al-sensitive cultivars was more permeabilized than that of the Al-tolerant cultivars, based on the FDA-PI fluorescence staining technique. Exposure for 30 min to Al treatment at 100 µM significantly increased the PM permeability of protoplasts isolated from the root-tips for the Al-sensitive pea cultivar placed in a moderately hypotonic medium. Protoplasts from root-tip portions of all the Al-sensitive cultivars took up more Al than those of the Al-tolerant ones when treated with 100 pM Al under isotonic conditions for 30 min. The co-existence of DNP or hypotonic conditions led to a larger increase of Al uptake by the protoplasts from Al-sensitive maize cultivars. These results suggest that Al ions rapidly alter the PM of the root-tip portion in the Al-sensitive cultivars, irrespective of plant species, resulting in an increase of the PM permeability.     

Salt tolerance of grain crops in relation to ionic balance ability to absorb microelements

A greenhouse experiment was conducted to investigate the effect of exchangeable Na on the growth and absorption of metal elements in barley, rye, and maize. The plants were cultivated in soils whose exchangeable sodium percentages (ESP) were 6.6 (saline soil: Saline), 17.4 (saline-sodic soil: Sodic 1), and 39.6 (sodic soil: Sodic 2), which were prepared from Tottori sand dune soil (Control). The dry weight (DW) and concentrations of metal elements Ca, Mg, Mn, Zn, and Cu) in shoots were analyzed. The shoot DW was smaller with higher ESP, but in barley the difference between all the treatments was no longer observed with time. In Sodic soils, the growth of barley was vigorous, whereas rye growth was poor, and maize plants died by 5 weeks after planting. The Na concentration in shoots of all the species was higher with higher ESP. The K concentration in shoots was low at the early growth stage, but in barley it was higher in the Saline and both Sodic soils than in the Control at the subsequent stages. The concentrations of Ca and Mg in shoots of barley and maize in the Saline and both Sodic soils were higher than those in the Control, but in rye the concentrations were lowest in Sodic 2. The concentrations of Mn, Zn, and Cu in barley shoots in the Saline and bothSodic soils tended to be higher than those in the Control, whereas in rye they were lower than in the Control in both Sodic soils. Barley showed a higher ability to absorb low available microelements than rye and maize. These results indicate that barley is tolerant to sodicity as well as salinity, maize is tolerant to salinity, but is very sensitive to sodicity, and rye is moderately sensitive to both stresses. We suggest that the tolerance of grain crops to ESP involves a tolerance to a high Na concentration in shoots, the ability to keep suitable concentrations of essential cations in the presence of a high concentration of Na in shoots and the ability to absorb low available microelements.