一种脱水洋葱制品中微生物菌落总数的检测方法

建立一种准确检测脱水洋葱制品中菌落总数的方法.利用离心法对出口脱水洋葱制品中沙门氏菌进行预富集,以提高国标检测方法的致病菌检出率,弥补国标方法的不足,并对该方法的准确度进行评价.试验结果表明,样液中菌体经过高速离心后,99％以上的菌体可以从样液分离.与标准方法比对,高速离心法很好地解决了脱水洋葱粉样液中的抑菌成分的干扰,结果可靠准确,基本满足国标中食品安全标准要求,具有一定的实际推广意义.     

离心除精浆对提高冷冻精液品质的作用

采用离心洗涤法去除精浆后,对精液进行冷冻处理。发现:1、除精浆精子冻后的活率、Ⅰ类顶体率和精子畸形率与未除精浆组存在显著差异(P<0．05);2、除精浆使稀释后精液精浆中GOT和LDH活性明显升高(P<0．05)。从平衡后到解冻后各组GOT和LDH活性都呈上升趋势。但除精浆试验组比未除精浆试验组上升缓慢;3、除精浆试验组精子的穿卵率、卵内平均精子数都显著高于未除精浆试验组(P<0．05);4除精浆离心洗涤液用生理盐水和脱脂乳-卵柠液．两者之间无显著差异(P>0．05)。     

桃基因组DNA提取方法及部位的比较研究

通过对桃基因组DNA几种提取方法所得的DNA质量分析,表明分步离心法是最为理想的提取方法,能满足RAPD及其他分子生物学研究的需要。用此方法提取桃不同部位基因组DNA,结果分析表明,从嫩叶和幼嫩果实提取DNA产率较高。     

Single-Layer Colloid Centrifugation as a Method to Process Urine-Contaminated Stallion Semen After Freezing-Thawing

Urospermia is a major ejaculatory dysfunction affecting stallions. It has been thought that urine-contaminated semen should not be cryopreserved; however, on select cases, urine contamination of semen cannot be avoided. A recent study suggested that urospermic semen can be cryopreserved after cushion centrifugation and extension. Thus, this study aimed to assess the use of single-layer colloid centrifugation (SLC) to process frozen-thawed urine-contaminated stallion semen. Raw ejaculates (n = 55) from eight stallions were split into three groups: no urine, low (20%), or high (50%) urine contamination. Semen was extended 1:1, cushion-centrifuged, and resuspended at 200 million sperm/mL in BotuCrio. Resuspended semen was loaded in 0.5 mL straws and cryopreserved in liquid nitrogen. Samples were thawed (37°C for 30 seconds) and processed by SLC (400 g/30 minutes). Percentages of total motility (TM) and progressive motility (PM) were assessed with computer-assisted semen analyzer. Sperm viability (%VIAB) and yield were assessed with a NucleoCounter before and after gradient centrifugation. Data were analyzed with two-way ANOVA and Tukey’s test. The motility parameters TM before SLC (control: 35 ± 2; low: 33 ± 0.7; high: 22 ± 1.8) after SLC (control: 51 ± 3.6; low: 42 ± 2.2; high: 25 ± 2.8) and PM before SLC (control: 24 ± 1.8; low: 21 ± 1.14; high: 12 ± 1.5) and after SLC (control: 40.3 ± 3.2; low: 31 ± 3.9; high: 14 ± 2) significantly decreased with increasing urine contamination. Urine contamination marginally reduced (P < .05) sperm viability after cryopreservation before SLC (control: 45 ± 0.7; low: 27 ± 0.2; high: 27 ± 0.3) and after SLC (control: 54 ± 0.5; low: 49 ± 0.7; high: 38 ± 0.6). Recovery rates of sperm after centrifugation were not significantly different between groups. In conclusion, urine contamination affects sperm motility parameters in a dose-dependent manner. Post-thaw SLC selected sperm with higher motility and viability in control and low groups but only selected sperm with higher viability in the high group.     

牛精子不同获能方法对体外受精效果的影响

为了提高牛体外受精率,探讨牛冷冻精液不同获能方法对体外受精效果的影响,对牛冷冻解冻精液进行了两次离心获能法与一次离心加上游法获能对体外受精效果影响试验.结果表明,两次离心组受精率卵裂率(75.6-±4.5)％与一次离心加上游法组受精卵裂率(76.4±1.9)％无显著差异(P＞0.05);二次离心组囊胚率(35.7±4.1)％与一次离心加上游法组(36.3±2.7)％差异不显著(P＞0.05).而两次离心组却可以大大节省了体外获能时间.     

Effect of Centrifugation Technique on Post-storage Characteristics of Stallion Spermatozoa

Three ejaculates were collected from four stallions and used to compare the effects of three centrifugation methods on post-storage motility and recovery of available sperm. Two aliquots per ejaculate were diluted with skim milk-glucose (SKMG) extender to 50×10⁶ sperm/mL, placed in 50-mL conical bottom tubes, and centrifuged at either 700g for 15 minutes (700g) or 600g for 12 minutes (600g). A third aliquot was diluted 1:1 with SKMG, placed in 15-mL conical tubes, and centrifuged at 400g for 7 minutes (400g). Subsamples from each pre-treated diluted ejaculate were held at room temperature and evaluated for motility at the same time as the post-centrifugation pre-storage motility evaluation was made for treated aliquots. After centrifugation, samples from each aliquot were stored at 5°C for evaluation after 24 and 48 hours or frozen in liquid nitrogen. Percentage of available sperm harvested was higher (P ≤ .05) for aliquots centrifuged in 15-mL tubes at 400g versus 600g in 50-mL tubes. After centrifugation, total but not progressive motility of aliquots centrifuged at 700g was lower than that for noncentrifuged controls and sperm from aliquots centrifuged at 400g in 15-mL tubes. After cold storage, values for total but not progressive motility or velocity were higher (P ≤ .05) for aliquots centrifuged in 15-mL tubes at 400g compared with those centrifuged in 50-mL tubes at both 600g and 700g. Postthaw motility of frozen sperm was not different between centrifugation treatments. Poststorage percentages of intact acrosomes and detached heads did not differ because of centrifugation treatment.     

除精浆提高冷冻精液品质的实验研究

采用离心洗涤法去除精浆后,对精液进行冷冻处理。发现:1、除精浆精子冻后的活率、Ⅰ类顶体率和精子畸形率与未除精浆组存在显著差异(P<0．05);2、除精浆使稀释后精液精浆中GOT和LDH活性明显升高(P<0．05)。从平衡后到解冻后各组GOT和LDH活性都呈上升趋势。但除精浆试验组比未除精浆试验组上升缓慢;3、除精浆试验组精子的穿卵率、卵内平均精子数都显著高于未除精浆试验组(P<0．05);4除精浆离心洗涤液用生理盐水和脱脂乳-卵柠液．两者之间无显著差异(P>0．05)。     

不同离心处理对低发芽率玉米种子发芽的影响

以一批已检测为低发芽率的玉米杂交种郑单958为试验材料,进行10种不同处理,研究离心对低发芽率玉米种子发芽势、发芽率、根长、根重以及苗长和苗重的影响。结果表明:不同离心处理对低发芽率玉米种子的发芽势和发芽率有显著促进作用,其中以10 000 r/min离心5～10 min效果最为显著。发芽7 d后的根长、根重、苗长和苗重以10 000 r/min离心5 min处理最好。     

气相色谱—电子捕获检测器测定黄瓜中多种有机氯农药和除草剂残留

为了探索建立固相萃取-气相色谱法-电子捕获检测器同时测定黄瓜中的六氯苯等多种农药和除草剂残留的方法,样品用乙腈提取,经SPE小柱(弗罗里硅土)净化,采用电子捕获检测器进行测定,外标法定量,分别对黄瓜进行3个水平(0.02、0.04、0.08 mg·kg-1)(敌稗和丁草胺在0.04、0.08、0.16 mg·kg-1)的添加回收试验。结果表明,平均添加回收率为68.0%¹20.3%,RSD为2.0%120.3%,RSD为2.0%²0.8%,方法的最低检测限为0.000 920.8%,方法的最低检测限为0.000 9⁰.027 4 mg·kg-1,在103的范围内线性较好,相关系数r≥0.998 7。该方法灵敏度高、重复性好,可以作为测定蔬菜中这几种农残的测定方法。9种农药在黄瓜基质中存在不同程度的基质效应,其中敌稗和丁草胺存在较强的基质抑制效应,其他几种存在较弱的基质增强效应。