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1.
快速、准确的根系原位观测方法是根系研究中的重要技术,本研究介绍了一种根管盆栽方法,该方法在透明PVC管内种植作物,通过遮光膜保持管内黑暗环境,以实现在作物生长过程中对其根系生长的原位动态观测,且根系生长环境更接近田间实际情况,并可通过改变根管长度、半径等将其应用于田间深根作物的研究中。利用此方法、结合根系扫描技术分析了油菜和冬小麦从发芽到出苗后16 d时的根系生长情况。结果表明,出苗后7和16 d冬小麦根系和地上部干物重均大于油菜,出苗后16 d冬小麦和油菜根冠比分别为0.513和0.372。大部分根系分布在0~16 cm表层土壤中,出苗后16 d冬小麦和油菜表层土壤中的根长在总根长中的比例分别为62.60%和67.76%,根系总表面积、总体积和一级侧根数均为表层土壤中占比最多,在出苗后7 d,总根长、总表面积、总体积和一级侧根数均为冬小麦显著高于油菜,而在出苗后16 d,两种作物的总根长和总表面积差别不大,说明油菜根系生长呈先缓后快趋势。表层土壤中根系平均直径小于底层土壤,油菜根系平均直径小于冬小麦,油菜和冬小麦的根系直径均大部分在0~0.50 mm之间,随着根系生长,较细的侧根逐渐增多,根系平均直径变小。出苗后16 d内的冬小麦根系伸长速率为1.83 cm/d,大于油菜的1.51 cm/d。因此,冬小麦苗期根系生长快于油菜,油菜根系呈先缓后快的生长特性。本研究介绍的根管法是一种原位研究根系的有效方法。  相似文献   

2.
Prior to introduction of a new method to the diagnostic laboratory, analytical performance must be validated to ensure operation within the manufacturer's specifications and/or within predetermined quality requirements. In addition, the new method may require diagnostic performance assessment to ensure it differentiates between diseased and nondiseased individuals as intended. These 2 phases of assessment, while complementary, are not equivalent and require a different set of experiments, statistical analyses, and interpretation. Studies of analytical performance typically include a method comparison experiment, the purpose of which is to identify bias (inaccuracy) of the “test” (or “index”) method (new method) relative to a “comparative method” (established method). Analysis of method comparison data is facilitated by commercial software programs that present the statistical significance of identified bias; however, the clinical relevance of any bias also should be considered. Studies of diagnostic performance should not be pursued until analytical performance is fully characterized and may not be required for well‐established tests or for those for which results are nonspecific (ie, not referable to a specific disease or condition). Diagnostic performance assessment may include assessment of sensitivity, specificity, predictive values, odds ratios, and/or likelihood ratios. The purpose of this review is to clarify differences between the assessment of analytical and diagnostic performance, and to explore the method comparison study and bias assessment from a perspective not addressed in prior veterinary articles.  相似文献   

3.
紫花苜蓿是世界最重要的豆科牧草之一,干旱是影响其产量和地理分布的关键瓶颈。在紫花苜蓿响应干旱胁迫过程中,转录因子发挥着重要的调控作用。TCP(teosinte branchesd 1/cycloidea/pro-liferating cell factors)为植物特有的转录因子,在植物生长、发育、响应逆境胁迫中都具有重要的生物学功能。截至目前,该基因家族在紫花苜蓿中的分布以及响应干旱胁迫的生物学功能仍未见报道。因此,为进一步挖掘紫花苜蓿中响应干旱胁迫功能基因,本研究利用生物信息学方法在全基因组水平对TCP基因家族进行了鉴定,并对其系统进化、基因结构、染色体定位、共线性分析以及干旱胁迫下的表达模式进行了分析。结果表明,紫花苜蓿基因组中共鉴定出40个MsTCP基因,不均匀地分布于20条染色体上,其中包括17对旁系同源基因对,且都是基因片段复制事件。系统发育和保守结构域分析发现,MsTCP基因可以分为2个大分支和3个亚家族(PCF, CIN与CYC/TB1),同一分支中的成员具有相同氨基酸数目的TCP结构域,同亚家族中的成员具有相似的保守基序与基因结构。此外,通过分析紫花苜蓿响应干旱转录组数据共鉴定出4个可能与紫花苜蓿响应干旱胁迫有关的MsTCP基因(MsTCP23,MsTCP27,MsTCP29,MsTCP33)。qRT-PCR结果进一步表明PEG模拟干旱胁迫处理后,这4个基因的表达量在根和叶中均显著上调,进一步确定了这些基因的确响应紫花苜蓿干旱胁迫。该研究为后期深入解析紫花苜蓿响应干旱胁迫理论以及通过基因工程技术创制高抗旱紫花苜蓿新种质奠定基础。  相似文献   

4.
本试验以优化PCR条件,建立快速性别鉴定方法为目的,从家鸡雏鸡血样、鸡胚羊水和尿囊液中获得DNA进行性别鉴定.通过对家鸡的两个性别鉴定候选基因CHD1和xho Ⅰ重复片段进行PCR扩增引物筛选和反应体系的优化.结果显示CHD1基因PCR法可稳定、准确地用于鉴定家鸡性别,该体系经改进和优化后,缩短了鉴定时间,提高了鉴定的稳定性和准确性.在此基础上利用12.5日龄鸡胚羊水和尿囊液建立了早期胚胎的性别鉴定体系.该方法为家鸡早期胚胎性别鉴定批量化的快速操作提供了可行的依据,同时也为鸟类性别决定机制的研究奠定了基础.  相似文献   

5.
DNA barcoding has been proposed as a method for species identification. However, this method has been criticised for its over-reliance on a single mitochondrial gene. In this study, four mitochondrial gene regions and one nuclear gene region were used to investigate their different abilities to identify tissue associated with museum specimens of Aethomys chrysophilus, Aethomys ineptus and Micaelamys namaquensis. Aethomys chrysophilus and the more recently elevated A. ineptus are indistinguishable on morphological grounds; however, their ranges are largely parapatric with only one syntopic locality currently known. All of the mitochondrial gene regions were able to separate M. namaquensis from A. chrysophilus and A. ineptus, but they varied in their abilities to resolve differences between A. chrysophilus and A. ineptus. The sequence results identified a specimen from KwaZulu-Natal that was misclassified and should have been identified as A. ineptus. Seven specimens that had not been reclassified following the elevation of A. ineptus to species level were identified as A. ineptus. Individuals of A. chrysophilus from Malawi could not be classified as either A. chrysophilus or A. ineptus, and may be a hybrid or a new, distinct species. This study indicates that DNA barcoding may be used to separate M. namaquensis from A. chrysophilus and A. ineptus, and although it was not able to separate A. chrysophilus and A. ineptus, it did indicate specimens from Malawi may be a new cryptic species.  相似文献   

6.
Summary The influence of light colours on growth and stress response in rainbow trout Oncorhyncus mykiss (15.16 ± 0.29 cm; 32.27 ± 1.18 g) was studied. Fish were reared in 16 glass aquaria (140 × 30 × 80 cm) each with 12 fish under one of four different lighting spectra: yellow (546 nm), red (605 nm), blue (470 nm) and white (full spectrum, control). Experiments lasted 125 days. The stress response was evaluated by measuring cortisol levels. Body weight and total length of the fish reared under yellow light were greater compared with the other colour regimes while feed conversion ratio significantly lowers. Condition factor and specific growth rate, however, were not differentiated among experimental light treatments. Stressed fish showed lower cortisol levels under yellow light compared with other light exposures. The study indicates that under laboratory conditions, rainbow trout grow best under yellow light and that yellow light lowers the stress‐induced cortisol response in this fish species.  相似文献   

7.
本试验研究了温室盆栽条件下带内生真菌(E+)和不带内生真菌(E-)的多年生黑麦草喷施不同浓度水杨酸(SA)后,持续干旱胁迫15 d和对照水分两种条件下,多年生黑麦草的叶片相对含水量(RLWC)、叶绿素含量(Chl)、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、脯氨酸(Pro)和可溶性糖(SS)含量等生理指标的变化,以明确干旱胁迫下SA和内生真菌对多年生黑麦草的影响。结果表明,在干旱胁迫下,感染内生真菌的多年生黑麦草叶片相对含水量、叶绿素含量、POD活性、SS含量显著(P<0.05)高于未感染内生真菌的多年生黑麦草植株;一定浓度的 SA增加了多年生黑麦草叶片相对含水量、叶绿素含量、POD活性、SOD活性、Pro和SS含量,降低了MDA含量,且最适水杨酸浓度为0.25和0.50 mmol·L-1;内生真菌与SA互作显著(P<0.05)提高了多年生黑麦草SOD活性、POD活性和叶绿素含量。该结果说明内生真菌与SA都能提高多年生黑麦草的抗旱性,即内生真菌和SA通过提高寄主的渗透调节和活性氧清除系统进而提高了寄主的抗旱性。  相似文献   

8.
为探究K^+对高盐胁迫下红豆草生长及相关生理指标的影响,在高盐胁迫(100 mmol·L^-1 NaCl)下添加不同浓度(5、10、25和50 mmol·L^-1)KCl对4周龄幼苗处理7d后进行测定。结果表明,高盐胁迫显著抑制了红豆草幼苗的生长;然而,添加不同浓度KCl明显减轻了高盐胁迫对幼苗生长的抑制作用。高盐胁迫下,随着KCl浓度的升高,红豆草幼苗的鲜重、干重、组织含水量和叶绿素含量逐渐增加,当浓度为25 mmol·L^-1时达到最大值,随后有所降低;叶和根中的Na^+浓度逐渐降低,而K^+浓度和K^+/Na^+呈逐渐升高趋势;脯氨酸、可溶性糖和可溶性蛋白含量在KCl浓度为25 mmol·L^-1时达到峰值,而后下降;丙二醛(MDA)含量、细胞壁、细胞质和液泡转化酶活性逐渐减小,而超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物(APX)、蔗糖合成酶(SS)及蔗糖磷酸合成酶(SPS)活性、蔗糖和葡萄糖含量呈逐渐增加趋势。添加K^+可通过维持植株体内K^+、Na^+稳态平衡、提高抗氧化酶活性和增强蔗糖的合成与积累,来减轻高盐胁迫对红豆草幼苗的毒害作用。  相似文献   

9.
A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Malpura rams. Twenty‐eight adult Malpura rams (average body weight (BW) 66.0 kg) were used in this study. The rams were divided into four groups: CON (n = 7; control), HES (n = 7; heat stress), NUS (n = 7; nutritional stress) and COS (n = 7; combined stress). The study was conducted for a period of 2 months. CON and HES rams had ad libitum access to their feed while NUS and COS rams were under restricted feed (30% intake of CON rams) to induce nutritional stress. The HES and COS rams were kept in climatic chamber at 42 °C and 55% relative humidity for 6 h a day between 10 : 00 h and 16 : 00 h to induce heat stress. Body weight increased significantly (p < 0.05) in CON as compared to NUS and COS. When compared within groups, scrotal width morning, scrotal width afternoon, scrotal circumference morning and scrotal circumference afternoon were significantly (p < 0.05) larger in CON while smaller in COS rams. The higher testicular length was recorded both during morning (p < 0.05) and afternoon (p < 0.01) in COS rams while the lowest in NUS rams. The highest plasma testosterone concentration was recorded in CON and lowest in COS rams. Semen volume and mass motility also differed significantly (p < 0.05) between the groups. The highest semen volume and mass motility was recorded in CON and NUS while lowest in both HES and COS rams. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on reproductive performance of rams.  相似文献   

10.
采用稀释平板法从6种表面消毒的紫花苜蓿种子中分离和纯化出3株阪崎克罗诺杆菌疑似分离物。选取代表分离物1gF3室内条件下通过菌悬液(≈109 cfu·mL-1)浸种紫花苜蓿种子,皿内发芽;腹腔注射洁净级昆明小白鼠试验;测定阪崎克罗诺杆菌疑似分离物对紫花苜蓿和小鼠的致病性。结果表明,阪崎克罗诺杆菌疑似分离物对紫花苜蓿不致病;小鼠在接种分离物1gF3 12 h后病理特征显示化脓性脑炎、心肌水肿扩张,局部心肌纤维有断裂、肝脏局部坏死、急性脾炎、肺部急性弥散性出血以及肾脏弥散性血管内凝血等症状,1gF3对小鼠具有致病性。发病小鼠血液涂板分离到阪崎克罗诺杆菌疑似分离物TM2。结合表型特征和16S rDNA鉴定,确定分离物1gF3和TM2为阪崎克罗诺杆菌。在此基础上,测定了菌株1gF3的生物学特性,该菌对数生长期为24~36 h,之后衰退;干旱胁迫加重其生长量线性下降;菌株1gF3能在较宽温度(10~41 ℃)和pH (3~11)范围内生长;该菌不需盐生长,NaCl浓度上升该菌的生长量受到抑制;黑暗交替的光照有利其生长。研究材料为具有动物和植物跨域寄主特点的一类病原菌资源,研究结果对隐藏于植物或动物材料中跨域病原菌侵染传播特征及相关检疫防控提供了理论基础。  相似文献   

11.
为揭示丛枝菌根真菌(AMF)对增强枳实生苗耐盐性的作用,以期为盐渍土条件下提高柑橘生长提供依据。在正常水分和盐胁迫(100 mmol /L NaCl)下,研究接种Funneliformis mosseae对盆栽枳实生苗生长和生理代谢的影响。结果显示:接种AMF显著提高了盐胁迫下枳的株高、叶片数、总鲜重、二级和三级侧根数、根系总长、投影面积、表面积和体积;接种AMF还显著提高了盐胁迫下枳叶片中叶绿素a、叶绿素b和总叶绿素的含量,以及枳根系和叶片的蔗糖含量。此外,盐胁迫下接种AMF显著抑制了叶片MDA和H2O2以及根系H2O2和O2?-的积累,显著提高了盐胁迫下根系和叶片Cu/Zn-SOD、Mn-SOD、POD和CAT的活性以及根系Fe-SOD活性。本研究表明盐胁迫下接种AMF的植株维持了更高的植物生长、根系发育、光合色素、蔗糖含量和抗氧化酶活性,因而具有高的耐盐性。  相似文献   

12.
为了研究氨氮胁迫下饥饿与复投喂对黄颡鱼脂质代谢的影响,将360尾黄颡鱼幼鱼[初始体重为(14.95±0.03)g]随机分配到12个养殖桶中,每桶30尾。对照组人工饱食投喂42 d,试验组饥饿14 d后恢复投喂28 d。对照组和试验组分别被暴露到总氨氮浓度为0(低氨氮处理,正常养殖环境)和5.70 mg/L(高氨氮处理,氨氮胁迫)的水体中,每组分配3桶试验鱼。结果显示:饥饿14 d后,高氨氮处理黄颡鱼肝脏中6-磷酸葡萄糖酸脱氢酶(6PGD)、脂肪酸合酶(FAS)活性以及6PGD、葡萄糖-6-磷酸脱氢酶(G6PD)、FAS、胆固醇调节元件结合蛋白-1(SREBP-1)、过氧化物酶体增殖物激活受体α(PPARα)和过氧化物酶体增殖物激活受体γ(PPARγ)基因的mRNA相对表达量显著低于低氨氮处理(P<0.05),而肝脏中肉碱棕榈酰转移酶(CPT)、脂蛋白脂酶(LPL)活性以及肉碱棕榈酰转移酶1(CPT1)和LPL基因的mRNA相对表达量则显著高于低氨氮处理(P<0.05);在氨氮胁迫或正常养殖环境下,饥饿14 d后,试验组黄颡鱼肝脏中6PGD、FAS活性以及6PGD、G6PD、FAS、SREBP-1和PPARγ基因的mRNA相对表达量显著低于对照组(P<0.05),而CPT、LPL活性以及PPARα、CPT1和LPL基因的mRNA相对表达量显著高于对照组(P<0.05);恢复投喂28 d后,高氨氮处理黄颡鱼肝脏中6PGD、FAS活性以及6PGD、G6PD、FAS和PPARα基因的mRNA相对表达量显著低于低氨氮处理(P<0.05),而肝脏中CPT、LPL活性以及CPT1和LPL基因的mRNA相对表达量则显著高于低氨氮组(P<0.05);在氨氮胁迫或正常养殖环境下,恢复投喂28 d后,试验组黄颡鱼肝脏中6PGD活性以及6PGD和G6PD基因的mRNA相对表达量显著高于对照组(P<0.05),而肝脏中LPL活性显著低于对照组(P<0.05);此外,在氨氮胁迫下,试验组黄颡鱼肝脏中FAS、SREBP-1和PPARγ基因的mRNA相对表达量显著高于对照组(P<0.05),而LPL基因的mRNA相对表达量则显著低于对照组(P<0.05)。综上可知,氨氮胁迫和饥饿胁迫均会促进黄颡鱼的脂质分解代谢,并抑制脂质合成代谢;氨氮胁迫下饥饿后复投喂能够恢复黄颡鱼的脂质代谢稳态。  相似文献   

13.
盐胁迫下外源Si对甘草种子萌发及幼苗K~+、Na~+含量的影响   总被引:1,自引:0,他引:1  
以乌拉尔甘草(Glycyrrhiza uralensis)种子为试验材料,研究在NaCl(100和200mmol/L)胁迫下,不同浓度Si(0、0.4、0.8、1.2、1.6和2.0mmol/L)对种子萌发及幼苗根冠比和K~+、Na~+含量的影响。结果表明:外源Si对盐胁迫下种子的发芽率、发芽势和发芽指数均具有显著的促进作用,且Si浓度在0.4和2.0mmol/L下作用最佳;Si可显著增加幼苗的根冠比,幼苗可通过增加K~+吸收,减少Na~+吸收来维持根系内K~+、Na~+的平衡。  相似文献   

14.
The aim of this experiment was to determine the effect of polyphenols extracted from tamarind (Tamarindus indica L.) seed coat on physiological changes, oxidative stress and production of male broilers maintained at high environmental temperatures. The results found that body temperature and respiratory rate of broilers maintained at 38 ± 2°C was higher than broilers maintained at 26 ± 2°C (P < 0.05). On day 1, the heterophil/ lymphocyte ratio of broilers maintained at 38 ± 2°C and received polyphenols at 300 and 400 mg/kg in diets was lower than broilers that received polyphenols at 0 and 200 mg/kg in diets (P < 0.05). At week 1, the malondialdehyde of the broilers maintained at 38 ± 2°C who received polyphenols at 400 mg/ kg in their diet was lower than broilers that received polyphenols at 100 and 200 mg/kg in diets (P < 0.05). At week 1, the body weights of broilers that were maintained at 38 ± 2°C who received polyphenols at 100–500 mg/ kg in diets, and broilers maintained at 26 ± 2°C were higher than that of the control group which had not been treated with a polyphenol diet (P < 0.05). This study indicated that polyphenols could reduce heat stress, oxidative stress and improve the growth rate of heat‐stressed broilers.  相似文献   

15.
A study was conducted to assess the effect of thermal, nutritional and combined stresses (thermal and nutritional) on the growth, oestradiol and progesterone levels during oestrus cycles in Malpura ewes. Twenty‐eight adult Malpura ewes were used in the present study. The ewes were randomly allocated into four groups, viz., GI (n = 7; control), GII (n = 7; thermal stress), GIII (n = 7; restricted feeding) and GIV (n = 7; combined stress). The animals were stall fed with a diet consisting of 60% roughage and 40% concentrate. GI and GII ewes were provided with ad libitum feeding while GIII and GIV ewes were provided with restricted feed (30% intake of GI and GII ewes) to induce nutritional insufficiency. GII and GIV ewes were kept in climatic chamber at 40°C and 55% RH for 6 h a day between 10:00 and 16:00 hours to induce thermal stress for a period of two oestrous cycles. Parameters studied were body weight, oestrus incidences, plasma oestradiol 17‐β, plasma progesterone, conception rate, gestation period, lambing rate, and birth weight of lambs. The results indicate that combined stress significantly (p < 0.05) reduced body weight, oestrus duration, birth weight of lambs, and oestradiol 17‐β whereas significantly (p < 0.05) increased oestrus cycle length and progesterone. Furthermore, the results reveal that on comparative basis, ewes were able to better adapt in terms of growth and reproduction to restricted feeding than thermal stress. However, when restricted feeding was coupled with thermal stress it had significant (p < 0.05) influence on body weight, average daily gain, oestradiol 17‐β and progesterone concentrations. This showed that combined stress were more detrimental for these reproductive hormones in Malpura ewes under a hot semi‐arid environment.  相似文献   

16.
本试验分为生长试验和低温胁迫试验2部分.先分别投喂大黄鱼(Larimichthys cro-cea)仔鱼经不同浓度(0、0.5、1.0、2.0和3.0 mL/m3)小肽营养强化后的轮虫和卤虫12 d,以探讨小肽对大黄鱼仔鱼生长和小肠发育的影响;再将大黄鱼仔鱼暴露在温度为12℃的水体中24 h,以探讨小肽对低温胁迫下大黄...  相似文献   

17.
The effects of three levels of manure application (0, 4 and 8 ton/10 a) with basic fertilizer (N : P : K = 10:10:10 kg/10 a) on the yield and chemical composition of maize (Pioneer 32K61) and sorghum (FS501) forages were examined in 2 successive years, 2001–2002. Maize was harvested at yellow ripe stage, while sorghum at dough stage. Dry matter yield (DMY) of sorghum was significantly higher than that of maize in both 2001 and 2002. Although, DMY of both sorghum and maize were not significantly affected by manure levels in 2001, they increased with the level of manure in 2002. Maize had higher levels of crude protein (CP) and lower crude fiber concentration than those of sorghum in both 2001 and 2002. Manure application had no effect on chemical compositions of both maize and sorghum except for CP in both years and organic a fraction (Oa) concentration in 2002. The higher manure application might have greater effects on sorghum and maize production because of higher DMY in the second year without any increase in fiber fraction.  相似文献   

18.
本试验旨在研究酶制剂对刺参生长、体成分、免疫能力及氨氮胁迫下免疫酶活力和热休克蛋白70含量的影响。试验共配制粗蛋白质含量为20%的试验饲料5种,首先配制不含酶制剂的基础饲料作为对照,然后分别以0.04%木聚糖酶、0.10%纤维素酶、0.01%淀粉酶和0.15%复合酶(由0.04%木聚糖酶、0.10%纤维素酶和0.01%淀粉酶组成)等量替代基础饲料配方中的α-淀粉。每种饲料设3个重复,每个重复放养体重(4.02±0.04) g 的幼参40头。试验期为56 d。结果表明:1)木聚糖酶、纤维素酶、淀粉酶、复合酶组的增重率分别比对照组提高了17.38%(P<0.05)、7.63%(P<0.05)、1.88%(P>0.05)和20.75%(P<0.05),特定生长率分别比对照组提高了0.25%/d(P<0.05)、0.03%/d(P<0.05)、0.01%/d(P>0.05)、0.30%/d(P<0.05)。2)饲料中添加木聚糖酶显著提高了刺参体壁粗蛋白质的含量( P<0.05),添加纤维素酶、淀粉酶和复合酶显著提高了刺参体壁粗蛋白质、粗脂肪和粗灰分的含量( P<0.05)。3)饲料中添加木聚糖酶、纤维素酶和复合酶显著提高了体腔液中过氧化氢酶的活力( P<0.05);添加淀粉酶显著提高了体腔液中溶菌酶、超氧化物歧化酶、过氧化氢酶活力( P<0.05)。4)在120 h氨氮胁迫过程中,各组体腔液中溶菌酶、超氧化物歧化酶、过氧化氢酶活力及热休克蛋白70含量基本呈先上升后下降趋势。除纤维素酶组外,其余加酶组体腔液中热休克蛋白70含量的最大值均高于对照组。综上,饲料中适量添加木聚糖酶、纤维素酶、淀粉酶或其复合酶均能显著促进刺参生长,改善体成分,提高免疫能力,木聚糖酶的促生长作用更明显,而淀粉酶的促免疫作用更明显。氨氮胁迫下,饲料中适量添加木聚糖酶、纤维素酶、淀粉酶或其复合酶均能使刺参更迅速和强烈地表现出免疫抵抗反应。  相似文献   

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