31份枇杷种质资源果实的蛋白质营养评价

利用化学评分(CS)、氨基酸评分(AAS)、必需氨基酸指数(EAAI)、氨基酸比值系数分(SRC)等4种非生物学评价法对31份枇杷种质资源的果实蛋白质营养价值进行评价。结果表明:含硫氨基酸(甲硫氨酸和胱氨酸)为第一限制氨基酸;不同的评价方法结果有所差异,CS的范围为8.36~21.46;AAS的范围为9.87~23.1;EAAI的范围为42.83~65.68;SRC的范围为54.90~63.20,31份种质的SRC均在50以上,有16份超过60;枇杷果实蛋白质具有较高的营养价值,红肉种质的CS、AAS、SRC显著高于白肉种质,而两者的EAAI差异不显著;野生种质的EAAI极显著高于栽培种质,CS、AAS、SRC差异不显著,不同来源地的种质之间CS、AAS、EAAI、SRC差异均不显著;类平均法欧氏距离通过聚类分析将31份种质分为3类。     

Characterization of an intravenous lipopolysaccharide inflammation model in calves with respect to the acute-phase response

Our objective was to develop a lipopolysaccharide (LPS) inflammation model in calves to evaluate the acute-phase response with respect to the release of pro-inflammatory cytokines and acute-phase proteins, fever development and sickness behaviour. Fourteen 4-week-old male Holstein Friesian calves were included and randomly assigned to a negative control group (n = 3) and an LPS-challenged group (n = 11). The latter received an intravenous bolus injection of 0.5 μg of LPS/kg body weight. Blood collection and clinical scoring were performed at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 18, 24, 28, 32, 48, 54 and 72 h post LPS administration (p.a.). In the LPS group, the following clinical signs were observed successively: tachypnoea (on average 18 min p.a.), decubitus (29 min p.a.), general depression (1.75 h p.a.), fever (5 h p.a.) and tachycardia (5 h p.a.). Subsequent to the recovery from respiratory distress, general depression was prominent, which deteriorated when fever increased. One animal did not survive LPS administration, whereas the other animals recovered on average within 6.1 h p.a. Moreover, the challenge significantly increased plasma concentrations of tumour necrosis factor-α, interleukin 6, serum amyloid A and haptoglobin, with peaking levels at 1, 3.5, 24 and 18 h p.a., respectively. The present LPS model was practical and reproducible, caused obvious clinical signs related to endotoxemia and a marked change in the studied inflammatory mediators, making it a suitable model to study the immunomodulatory properties of drugs in future research.     

低磷胁迫对红豆草光合、叶绿素荧光及内源激素的影响

为探究低磷胁迫对红豆草(Onobrychis viciaefolia)光合作用、叶绿素荧光以及内源激素的影响,本试验采用营养液沙培法,以耐低磷5号和磷敏感1号红豆草为试验材料,设置常磷(1.00 mmol·L^-1 KH₂PO₄)和低磷(0.01 mmol·L^-1 KH₂PO₄)胁迫处理,于不同胁迫天数后测定形态、光合以及内源激素含量变化。结果表明：低磷胁迫抑制红豆草生长和光合作用,在低磷胁迫下,除非光化学淬灭系数外,供试红豆草叶绿素荧光参数均下降。随着胁迫时间的延长,2份红豆草材料地上和地下部玉米素(ZT)、脱落酸(ABA)、生长素(IAA)和赤霉素(GA₃)及其之间的比值变化趋势不一致,耐低磷红豆草地上和地下部ZT,GA₃,IAA,ABA耐低磷系数大于磷敏感材料。相关性分析表明,IAA与光合作用和叶绿素荧光显著相关,ABA与IAA,ZT,GA₃呈负相关。研究结果可为红豆草耐低磷特性研究提供...     

Using genetic tools to inform conservation of fragmented populations of Asian elephants (Elephas maximus) across their range in China

A herd of 15 Chinese elephants attracted international attention during their 2021 northward trek, motivating the government to propose establishment of an Asian elephant national park. However, planning is hampered by a lack of genetic information on the remaining populations in China. We collected DNA from 497 dung samples from all 5 populations encompassing the entire range of elephants in China and used mitochondrial and microsatellite markers to investigate their genetic and demographic structure. We identified 237 unique genotypes (153 females, 84 males), representing 81% of the known population. However, the effective population size was small (28, range 25–32). Historic demographic contraction appeared to account for low haplotype diversity (H_d = 0.235), but moderate nucleotide and nuclear diversity (π = 0.6%, H_e = 0.55) was attributable to post-bottleneck recovery involving recent population expansion plus historical gene exchange with elephants in Myanmar, Lao PDR, and Vietnam. The 5 populations fell into 3 clusters, with Nangunhe elephants differing consistently from the other 4 populations (F_ST = 0.23); elephants from Mengyang, Simao, and Jiangcheng belonged to a single population (henceforth, MSJ), and differed from the Shangyong population (F_ST = 0.11). Interpopulation genetic variation reflected isolation by distance and female-biased dispersal. Chinese elephants should be managed as 2 distinct units: Nangunhe and another combining Shangyong and MSJ; their long-term viability will require restoring gene flow between Shangyong and MSJ, and between elephants in China and neighboring countries. Our results have the potential to inform conservation planning for an iconic megafaunal species.     

氟吡呋喃酮与8种杀虫剂复配对温室白粉虱的联合毒力

为了筛选出对温室白粉虱高效的农药复配组合,本试验选择9种杀虫单剂对田间采集的温室白粉虱进行了毒力测定,并利用共毒因子和共毒系数对氟吡呋喃酮与8种杀虫剂复配组合的联合毒力进行评价,同时对筛选出的药剂进行田间药效试验。结果表明：杀虫单剂毒力测定中,LC₅₀最低的为鱼藤酮,最高的为螺虫乙酯,48 h LC₅₀分别为0.43μg/mL和78.59μg/mL;毒力大小顺序为鱼藤酮>氟啶虫胺腈>除虫菊素>苦参·印楝素>d-柠檬烯>氟吡呋喃酮>啶虫脒>高效氯氰菊酯>螺虫乙酯。共毒系数大于120的复配组合为氟吡呋喃酮与d-柠檬烯5∶1、氟吡呋喃酮与苦参·印楝素1∶2和1∶5,共毒系数分别为268.31、247.80和241.46,LC₅₀分别为5.76、4.51μg/mL和4.34μg/mL。氟吡呋喃酮与d-柠檬烯5∶1复配增效作用明显,为最佳配比。田间药效试验表明,10 d后,17%氟吡呋喃酮可溶液剂与1%苦参·印楝素乳油、5%d-柠檬烯可溶液剂复配对温室白粉虱的防效达到83.5%～83...     

县域耕地土壤养分时空变异特征研究

土壤养分空间变异研究是精准农业实施的前提,对提高粮食作物单位面积产量和保护农业生态环境具有重要作用。为掌握陕西渭北旱塬区土壤养分时空变异规律,综合空间自相关和重心模型,分析1980—2007年、2007—2017年白水县耕地土壤有机质(SOM)、速效磷(AP)和速效钾(AK)的时空变异特征。结果表明：(1)研究区土壤SOM的平均含量分别增加了1.29、3.22 g·kg^-1,AP的平均含量分别增加了6.89、24.45 mg·kg^-1,仅有AK的平均含量呈现出先减少后增加的趋势。(2)三期耕地土壤养分的变异系数范围为30.2%～90.8%,属于中等变异。1980—2017年,耕地土壤SOM、AP和AK的全局Moran’s I指数均降低,空间结构性减弱,随机因素作用增强。(3)土壤SOM、AP和AK含量均有不同程度的增加,土壤SOM含量总体呈北低南高分布,土壤AP、AK含量分布情况较为一致,呈东高西低。(4)土壤SOM含量重心在东南方向发生偏移,AP、AK含量重心在东北方向发生偏移。土壤养分标准差椭圆空间分布格局同研究区分布方向一致,转角呈现“...     

基于多源遥感数据的高寒草地生物量反演模型精度——以夏河县桑科草原试验区为例

基于MODIS、Landsat-8 OLI和HJ-1A/1B CCD卫星遥感资料,结合2013-2014年甘南州夏河县桑科草原试验区野外实测数据,建立了高寒草地地上生物量遥感反演模型,筛选出基于不同遥感资料植被指数的生物量最优反演模型,比较分析了生物量最优模型的空间效应。同时,分析了2000-2013年基于MODIS植被指数估算的试验区产草量的年际变化特征。结果表明,草地生物量最优反演模型为基于Landsat-8 OLI NDVI数据的对数模型(y=727.54lnx1+495.23,R2=0.772,RMSE=31.333 kg DM·hm-2);在30和250 m空间分辨率下,基于MODIS NDVI及EVI、Landsat-8 OLI NDVI和HJ-1A/1B CCD NDVI最优模型估算的生物量均高于实测生物量,其中Landsat-8 OLI NDVI数据估算的草地生物量与实测生物量值最接近;2000-2013年试验区草地总生物量整体上具有显著增加的趋势(R2=0.590 7,P0.001),平均增加速率达50.57 kg DM·hm-2·a-1。     

紫花针茅生殖器官形态的变异及其与环境因子的关系

紫花针茅(Stipa purpurea)是青藏高原分布面积最广的植物之一,对高原环境具有广泛的适应性。该植物具有的锥形繁殖体(包括种子和附属结构),是其适应环境的主要特征之一。为揭示该植物对高原环境的适应性表现,本研究对不同纬度的20个紫花针茅种群繁殖体的形态特征及其与环境的关系进行比较研究。结果表明,1)种长的变化幅度为0.692~1.255 cm,种宽的变化幅度为0.392~0.713 mm,芒长的变化幅度为2.394~8.736cm,种子重的变化幅度为0.678~1.560 mg。芒长和种子重具有较高的种群间变异系数。种子重与种长呈极显著正相关关系(P0.01),和芒长呈显著正相关关系(P0.05);种长、种宽、芒长相互之间均呈极显著正相关关系。2)种长、种子重与等效纬度均呈显著正相关关系,与年均降水量均呈显著负相关关系;种长与年均温呈现出凸型变异的关系。3)20个种群依据繁殖体特征进行聚类分析可分为3组,聚类结果与地理分布基本一致。     

Egg trait variation in a large hawk‐cuckoo (Hierococcyx sparverioides) host population of Chinese babax (Babax lanceolatus)

Mutual interaction between brood parasites and their hosts is a well‐known model system for studying host–parasite coevolution. Both parties have acted reciprocally, resembling an evolutionary arms race, in which adaptations and counter‐adaptations have evolved as a result of host–parasite dynamics, such as the classical cuckoo–host system. Discrimination among parasite and cuckoo eggs and rejection of foreign eggs is regarded as an important anti‐parasitism strategy. The Chinese babax (Babax lanceolatus) is a large hawk‐cuckoo (Hierococcyx sparverioides) host distributed in southwest China. A previous study shows that the babax is an intermediate egg rejector, and most cuckoo eggs are accepted by the Chinese babax, although a small proportion of hosts reject cuckoo eggs. Interestingly, the large hawk‐cuckoo lays non‐mimetic eggs in contrast to the uniform blue eggs of babaxes. Because egg coloration is a critical cue used by host species in favor of the recognition of parasitic eggs by hosts, we used a spectrometer to quantify egg color variation to understand the differentiation in discrimination ability between the egg rejectors and acceptors. We found that the chroma of intra‐clutch variation of babax eggs was more consistent in egg rejectors than in acceptors. However, no statistical significance was found in inter‐clutch variation between these two types of hosts. Our results suggest that hosts lay eggs with a low level of intra‐clutch variation without the necessity of a high level of inter‐clutch variation simultaneously as predicted by the egg signature hypothesis. This study may further indicate that selection pressures from evolutionarily recent parasites can drive individual‐based differences in an anti‐parasitism strategy.