猪精子结合和内化外源基因的影响因素研究

精子介导基因转移(SMGT)是目前转基因动物研究中简单而高效的方法之一,其中精子结合和内化外源基因的效率是精子介导转基因成功的关键.本试验以DIG标记的线性化EGFP作为示踪基因来检测猪精子结合和内化外源基因的影响因素,结果表明:猪精子能够自发结合外源基因,结合部位主要在精子顶体后区.精子结合外源DNA的阳性率随共孵育时间延长而增加,在37℃或39℃时孵育60 min后,阳性率不再增加;在17℃时孵育90min后,阳性率不再增加.在检查的15只公猪样本中,精子与外源DNA的结合率为6.57%～35.81%,内化率为2.99%～24.66%,个体间差异显著(P<0.01).精浆能够强烈抑制外源基因的结合和内化,脂质体及DMSO能够显著提高转染效率.死精子能够结合外源基因,但不能将其内化;反复冻融导致质膜破裂的精子对外源基因有更高的结合率,且不受个体影响.     

获能处理对山羊精子结合外源DNA能力的影响

鲜精离心洗涤除去精浆,然后用0.4 μmol/L钙离子载体(IA组)作用10 min或用10 mg/L肝素(HE组)作用90 min获能后,与DNA孵育,再用地高锌(DIG)末端标记的线形外源DNA进行转染,用免疫组化的方法分别检测它们的转染效率;用透射电镜观察精子获能前后的超微结构变化,并用碘化丙锭和羟化荧光素双探针检测获能对精子质膜完整性的影响,探讨精子获能影响精子结合及内化外源DNA变化的原因.结果显示,获能处理降低了精子结合和内化外源DNA能力,IA组和HE组结合率分别为(17.41±4.69)%和(15.00±4.36)%,都极显著低于未经获能处理的精子(32.97±4.58)%(P<0.01).IA组、HE组和对照组(未获能)内化率分别为(12.09±2.50)%、(8.93±1.79)%和(25.52±2.57)%,IA组、HE组均极差异小于对照组(P<0.01).超微结构观察和双荧光探针检测都发现精子获能后质膜完整性降低.用IA或HE获能后的精子质膜完整率是分别是(33.16±6.46)%和(33.90±4.14)%,与对照组差异极显著(P<0.01).结果表明,精子结合及内化外源DNA不是纯粹的分子渗透现象,而是受严格的分子调控的.     

奶牛性控冷冻精液品质和转染外源DNA的特点

本研究分析了奶牛性控冻精与普通冻精解冻后精液品质和转染外源DNA的特点。奶牛性控冻精与普通冻精解冻后,分别检测精液品质和精子超微结构,并与地高辛标记的线性化pEGFP-N1质粒共育转染,用免疫组化的方法检测精子转染外源DNA的效率。结果表明:性控冻精与普通冻精相比,有效精子数少(P0.01),精子活力、顶体完整率差(P0.05);2组精子超微结构都出现一定程度的顶体破裂、脱落等形态变化;2组精子都具有自动结合和转运外源DNA的能力,性控冻精转染率极显著高于普通冻精(P0.01),分别为(11.34%±2.41%)和(7.30%±2.14%)。     

纳米化聚酰胺-胺型树枝状聚合物对猪精子介导基因转移效率的影响

为优化猪精子介导的基因转移(SMGT)技术,提高转基因效率,本试验利用纳米化聚酰胺-胺型树枝状聚合物(PAMAM-D)为载体介导猪精子转染外源DNA,经原位杂交检测其阳性率,体外受精(IVF)分析外源基因的表达.结果显示,0.5 μg线状质粒DNA中加入PAMAM-D(质量比20∶1)阳性率最高(P＜0.05)；孵育时间为90、120min时,阳性率显著高于30、60 min组(19.94％、18.57％与8.50％、13.87％；P＜0.05)；以此条件处理精子,阳性率显著高于无载体和脂质体处理组(23.93％与7.25％0、13.25％；P＜0.05).各处理精子经IVF后,PAMAM-D组EGFP表达率显著高于其他2组(9.19％与4.81％、3.43％;P＜0.05),各组绿色荧光胚胎经基因组PCR分析均能检测到EGFP基因.结果表明,PAMAM-D可有效介导猪精子转染外源DNA,并通过体外受精将外源基因导入胚胎中.     

冷冻保存对公猪精子功能的影响

试验旨在探究公猪精液冷冻保存对其精子功能的影响。取长白猪的鲜精和优质冻精,用精子分析仪检测精子的运动能力,台盼蓝染色检测精子活率,体外受精（IVF）试验检测卵裂率与囊胚率,采用不同功能检测试剂盒检测冻精和鲜精的顶体完整率、线粒体膜通道孔（MPTP）活性、线粒体膜电位（MMP）、线粒体活性、线粒体氧化应激活性氧（ROS）以及精子DNA完整性,实时荧光定量PCR检测弱精子症相关蛋白基因SMCP、TEKT3、DNAH1、TCTE3的表达。结果表明,与猪鲜精相比,猪冻精的活率及活力均显著降低（P<0.05）,冻精的顶体完整率也明显下降（P<0.05）;冻精的卵裂率和囊胚率显著低于鲜精（P<0.05）;精子线粒体功能分析结果显示,冻精的MPTP相对荧光单位值（RFU）、线粒体膜电位荧光比率以及线粒体活性光密度（OD）值均显著低于鲜精（P<0.05）;精子线粒体ROS检测发现,冻精的RFU值显著高于鲜精（P<0.05）;精子DNA完整性检测结果显示,冻精拖尾率显著高于鲜精（P<0.05）;而弱精子症相关蛋白基因的表达与鲜精相比,差异不显著（P>0.05）。综上所述,冷冻导致猪精子活率、活力、线粒体功能、DNA完整性下降,最终使得冷冻精液精子的受精能力降低。     

单精注射法生产转GFP基因猪胚胎的研究

卵胞质内单精子注射(ICSI)的出现为治疗人类男性不育提供了新的途径。作为一种家畜胚胎工程新技术，ICSI可以解决猪的多精子受精问题。本研究用冷冻/解冻的猪精子与GFP基因孵育后对猪IVM卵母细胞进行ICSI，通过对猪ICSI卵母细胞发育能力和基因表达效率的分析，初步研究以精子为载体的转基因与卵细胞质内单精注射相结合的技术(SMGT-ICSI)生产转基因猪胚胎的技术路线的可行性。用GFP基因转染的精子注射后化学激活的ICSI卵母细胞基因表达率显著高于电激活处理的ICSI卵母细胞的基因表达率。用精子头部注射的猪卵母细胞和用完整精子注射的猪卵母细胞总基因表达效率无显著差异(P>0.05)。结果表明，用冷冻/解冻后的猪精子或精子头部与外源DNA孵育后通过ICSI方法生产转基因胚胎是可行的。     

解冻稀释液及孵育温度对冷冻-解冻后犬精液品质的影响

实验旨在比较解冻后解冻稀释液(Tris-柠檬酸-葡萄糖稀释液)的添加比例(1:0、1:1、1:2)对精液品质的影响,并比较了4种孵育温度(37、34、25、4℃)对精子寿命及精子活力的影响,探索合适的冷冻-解冻后犬精液的孵育条件。结果显示:解冻稀释液的添加与否及添加比例对解冻后孵育30 min的精子活力、活率、质膜完整率及顶体完整率均无显著影响;解冻后,在不同温度下孵育30 min,4组精子活率和质膜完整率无显著差异,而4℃孵育温度下精子活力和顶体完整率高于37℃(P0.05);解冻后孵育2 h,4℃孵育温度下的精液品质(精子活率、精子活力、质膜完整率、顶体完整率)最佳(P0.05),34℃和25℃组之间差异不显著,而37℃组的精液品质最差。结果表明,解冻稀释液对解冻后精液的孵育效果无影响,而解冻后精液的孵育温度以4℃最佳。     

在4℃降温平衡过程中0.2g/L咖啡因与精子共孵育时间对猪颗粒冻精质量的影响

实验旨在探讨在猪精液于4℃平衡2 h过程中0.2 g/L咖啡因与精液共孵育2 h、1 h和0.5 h,对颗粒冻精解冻后精子活率、活力、质膜完整性和顶体完整性以及解冻后精子体外存活时间等指标的影响,以期进一步提高猪颗粒冻精质量。实验结果表明,在精液冷冻之前,咖啡因不同平衡时间组的精子活率和活力都呈现出升高趋势,但与对照组差异不显著;咖啡因与精液共孵育2 h、1 h和0.5 h组的精子顶体完整率和质膜完整率显著低于对照组,前3组之间差异均不显著。而颗粒冻精解冻后,咖啡因与精液共孵育2 h、1 h和0.5 h组精子活率和活力均显著高于对照组,其中共孵育1 h组显著高于其他3组(P0.05),共孵育2 h组和0.5 h组间差异不显著(P0.05);共孵育2 h组精子顶体完整率和质膜完整率显著低于对照组和共孵育0.5 h、1 h组(P0.05),但后3组之间差异不显著;共孵育2 h组精子存活时间显著低于对照组、共孵育1 h和0.5 h组(P0.05),其中共孵育1 h组精子存活时间最长,达7 d以上。总之,在精液4℃降温平衡过程中咖啡因与精液共孵育1 h对冷冻后精子质量最有利,解冻后精子活率和活力显著高于其他各组,且解冻后精子体外存活时间最长。     

精子载体法转基因技术研究进展

精子载体法是以精子作为外源基因的载体,在受精过程中将外源基因导入动物胚胎,从而使外源基因进入子代的基因组中。作者就精子结合外源基因的机制,精子与外源基因结合的方法、影响精子转染外源基因和生产转基因动物的精子因素进行简要介绍,并对发展起来的输精管内注射转染法、曲细精管微注射法和睾丸直接注射法等精子载体转基因新途径进行综述。     

精子结合与内化外源DNA的分子机制研究进展

精子具有主动结合、转运、整合外源DNA的能力,并能在受精时导入卵母细胞,获得转基因动物。精子介导基因转移(sperm-mediated gene transfer,SMGT)是目前获得转基因动物简单而高效的方法之一,但该方法存在着极大的随机性和不确定性。研究精子结合与内化外源DNA的分子机制、外源DNA进入精子后的定位及命运,对提高利用SMGT方法生产转基因动物效率和稳定性是十分重要的。精子与外源DNA的结合、内化和整合是受到严格调控的一种现象。     

Liposome-mediated uptake of exogenous DNA by equine spermatozoa and applications in sperm-mediated gene transfer

REASON FOR PERFORMING STUDY: Sperm-mediated gene transfer has been reported as a method for production of transgenic animals in a variety of species, and this technique represents a possible method for production of transgenic equids. OBJECTIVES: To evaluate the uptake of exogenous DNA (enhanced green fluorescent protein; pEGFP) by equine spermatozoa and to assess the ability of transfected spermatozoa to introduce this transgene into early equine embryos. METHODS: To evaluate incorporation of pEGFP into equine spermatozoa, washed spermatozoa were incubated with 32P-pEGFP, with or without lipofection. Spermatozoa were also transfected with fluorescently-labelled DNA (Alexa647-pEGFP) and changes in sperm viability and DNA uptake were assessed. Mares were inseminated with pEGFP-transfected spermatozoa and embryos recovered. Expression of pEGFP was assessed by epifluorescence microscopy of embryos, and the presence of pEGFP DNA and mRNA was assessed by PCR and RT-PCR, respectively. RESULTS: Liposome-mediated transfection increased the incorporation of 32P-pEGFP into spermatozoa compared to controls. Flow cytometric evaluation of spermatozoa after transfection with Alexa647-pEGFP revealed a linear increase in the proportion of live, Alexa647+ spermatozoa with increasing DNA concentrations. After insemination with transfected spermatozoa, 8 embryos were recovered. There was no evidence of EGFP expression in the recovered embryos; however, PCR analysis revealed evidence of the pEGFP transgene in 2 of 5 embryos analysed. CONCLUSIONS: The incorporation of exogenous DNA by equine spermatozoa was enhanced by liposome-mediated transfection and this did not adversely affect sperm viability, acrosomal integrity or fertility. Although the EGFP transgene was detected in a proportion of Day 7-10 embryos, there was no evidence of expression of EGFP in these embryos. POTENTIAL RELEVANCE: Sperm-mediated gene transfer offers a potential technique for the generation of transgenic equids.     

Effect of Caffeine and Pentoxifylline Added Before or After Cooling on Sperm Characteristics of Stallion Sperm

Different additives have been tested in cooled stallion sperm, in order to maintain sperm quality and to ameliorate the decrease in sperm fertility potential. In several species, caffeine and pentoxifylline promote sperm motility by increasing energy production. We evaluate the effects of caffeine and pentoxifylline when added to stallion sperm before or after cooling. Three ejaculates from five stallions each were processed and resuspended in skim milk extender. Caffeine (5 mM), pentoxifylline (3.5 mM), or both additives combined were included to sperm before or after cooling (4°C for 24 hours). Cooled sperm were incubated at 37°C and evaluated at 0, 30, 60, and 120 minutes for motility, morphology, viability (flow cytometry), and membrane functionality (hypo-osmotic swelling test). Results were analyzed by two-factor mixed model for repeated measures and Tukey comparisons. As main effects, the caffeine and pentoxifylline affected significantly motility and kinematic parameters, without interaction between treatment and incubation after cooling. No differences were observed whether the additives were added prior or after cooling. Pentoxifylline added after cooling reduced significantly motility during incubation, but with higher values at 30 minutes. We detected a decrease in morphologically normal sperm (P < .0001), caused by an increase of tail defects (P < .003) in the presence of both additives. Viability and membrane functionality were also significantly impaired by additives. Pentoxifylline when added after cooling improved sperm motility and kinematic parameters for a short period of time. However, sperm characteristic related to fertility potential was compromised after a prolonged exposure to caffeine or pentoxifylline.     

Effect of relaxin on in vitro fertilization of porcine oocytes

Porcine relaxin is a peptide hormone belonging to the insulin super family that has a variety of biological functions. The present experiment was designed to investigate the effects of relaxin on sperm function and on in vitro fertilization (IVF) of porcine oocytes. Porcine spermatozoa were washed, swum-up, and incubated for 1-4 h in mTALP medium supplemented with 0, 20 or 50 ng/ml porcine relaxin. Motility was determined by observing the type of forward movement of the spermatozoa, and acrosome status was evaluated by applying the triple staining technique. Immature oocytes were aspirated from antral follicles and matured in IVM medium (modified NCSU-37). Matured oocytes were co-cultured with spermatozoa in IVF medium (mTALP) supplemented with 0, 5, 10, 15 or 20 ng/ml relaxin. After 6 h of sperm-oocyte co-incubation, putative zygotes were cultured for 18 h in oocyte culture medium NCSU-37 and then assessed for the rates of monospermy, polyspermy, and male pronucleus formation after acetic orcein staining. Relaxin improved (P<0.05) sperm motility and increased the percentage of acrosome-reacted live spermatozoa during 1-4 h of incubation, although viability was not significantly improved. Significantly (P<0.05) the highest percentage of monospermic (31.7%) and lowest percentage of polyspermic (16.5%) fertilization was achieved from the sperm-oocyte co-culture group treated with 20 ng/ml relaxin as compared to other groups. The percentage of male pronucleus formation was significantly (P<0.05) greater in the 20 ng/ml relaxin-treated sperm-oocyte co-culture group than in the other groups. These results indicate that supplementation with relaxin is capable of improving sperm function and fertilization of porcine oocytes in vitro.     

Effects of (−)‐Epigallocatechin Gallate on the Motility and Penetrability of Frozen–Thawed Boar Spermatozoa Incubated in the Fertilization Medium

Epigallocatechin gallate (EGCG) is the major polyphenol in green tea (Camellia sinensis) and is known for its antioxidant effects. The objective of the present study was to examine the effects of EGCG during in vitro fertilization (IVF) on the sperm quality and penetrability into oocytes. In the first experiment, the effects of concentration and incubation period of EGCG on the motility and penetrability of spermatozoa were examined. When frozen–thawed spermatozoa were incubated in IVF medium supplemented with 0 (control), 1, 50 and 100 μm EGCG for 1, 3 and 5 h, supplementation with 50 and 100 μm EGCG improved motility of the spermatozoa (p < 0.05), but not viability, as compared with the control group. When frozen–thawed spermatozoa were co‐incubated with in vitro‐matured (IVM) oocytes in IVF medium supplemented with 50 and 100 μm EGCG for 5 h, supplementation of EGCG had positive effects on sperm penetration rates. In the second experiment, the effects of supplementation of EGCG in IVF medium on penetrability of sperm from different boars and development of fertilized oocytes were evaluated. When frozen–thawed spermatozoa from six boars were co‐incubated with IVM oocytes in IVF medium supplemented with 50 μm EGCG, the effect of EGCG on sperm penetration and development of oocytes after fertilization was found to vary with individual boar. Our results indicate that motility and penetrability of boar spermatozoa are improved by co‐incubation with 50 μm EGCG, but the effects vary with individual boars.     

Utilisation of a sperm quality analyser to evaluate sperm quantity and quality of turkey breeders

1. A relatively new instrument known as a Sperm Quality Analyzer (SQA) offers a rapid assessment of sperm quality and quantity by providing a sperm quality index (SQI). The SQA measures a combination of the intensity of sperm activity and motile concentration by determining the number and amplitude of sperm movements per second in a capillary tube as detected through light beam interference. 2. Because the SQA has not been tested for its potential use in turkeys, the objective was to determine if the SQA could accurately respond to changes in turkey sperm concentration, viability, and motility in semen collected from turkey breeders. 3. The effect of varying concentrations of sperm on SQI values was evaluated by diluting replicate pools of semen from 4 different aged turkey breeder flocks with saline. Results from all 4 flocks showed that semen dilutions greater than 20-fold resulted in a linear decline in SQI values. 4. Additional in vitro analysis evaluated the effects of turkey sperm viability on the SQI under conditions of constant sperm concentration. Incubated, live sperm was mixed in various proportions with thawed, dead sperm to determine changes in viability. Increased proportions of dead sperm caused a decline in the SQI. 5. To assess sperm motility, turkey semen was incubated under either aerobic (motile) or anaerobic (immotile) conditions. Varied amounts of immotile and motile sperm samples were mixed. A linear increase in the SQI was observed as per cent motile sperm increased. 6. These results indicate that the SQA can respond to differences in turkey sperm concentration, viability, and motility using in vitro analyses.     

Effect of caspase inhibitor Z-VAD-FMK on bovine sperm cryotolerance

The aim of this study was to evaluate the treatment of bovine semen with the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK), before or after freezing on semen quality. After the initial assessment, sperm from 4 bulls were pooled (Experiment 1) and cryopreserved in BioXcell containing 0, 20 and 100 μM Z-VAD-FMK. After thawing semen viability, motility, membrane integrity, as well as DNA fragmentation and ΔΨm were evaluated. In Experiment 2, bovine frozen/thawed sperm were incubated for 1 hr with 0, 20 and 100 µM Z-VAD-FMK before assessing the semen quality. The treatment with Z -VAD-FMK before cryopreservation improved post-thawing sperm motility compared to the control group (p < .05), while no differences were recorded in sperm viability and membrane integrity among groups (on average 86.8 ± 1.5 and 69.1 ± 1.4, respectively). Interestingly, at the highest concentration, DNA fragmentation decreased (p < .05), while the percentage of spermatozoa with high ΔΨm increased (p < .05). The results of Experiment 2 showed that 1-hr treatment with Z-VAD-FMK did not affect sperm motility and viability (on average 63.4 ± 5.8 and 83.7.1 ± 1.2, respectively). However, Z-VAD-FMK improved sperm membrane integrity (p < .05) and at the highest concentration tested decreased the proportion of sperm showing DNA fragmentation (p < .05). No differences were recorded in the percentage of spermatozoa with high ΔΨm (on average 57.0 ± 11.4). In conclusion, the treatment with 100 µM of the caspase inhibitor Z-VAD-FMK before freezing increased bovine sperm mass motility and ΔΨm, while decreasing sperm DNA fragmentation. Treatment of semen after thawing with 100 µM Z-VAD-FMK improved sperm membrane integrity and reduced DNA fragmentation.     

Influence of mare uterine tubal fluids on the metabolism of stallion sperm.

Three experiments were conducted on the metabolism of stallion sperm. In experiment 1, whole and washed sperm were incubated under aerobic and anaerobic enviroments and analyzed before and after controlled incubation for motility, pH, lactic acid, glucose, fructose, and O2 comsumption. In experiment 2, whole and washed sperm were incubated aerobically and anaerobically with and without uterine tubal fluids. Experiment 3 was the same as experiment 2, except added substrates of glucose and lactic acid were studied. The same examinations were made in experiments 2 and 3 as for experiment 1. Motility decreased significantly during incubation for all treatments, with the greatest decrease occurring for whole semen where only trace amounts of substrate (fructose) were present. Exogenous glucose plus uterine tubal fluid maintained sperm motility better than did added lactate. However, sperm respiration rates were highest when exogenous lactate was the only substrate in the incubation medium. The mean pH values for gel-free stallion semen at the start of controlled aerobic and anaerobic incubation were 7.08 and 7.34. Lactic acid accummulation for 1 hour increased from 0.05 mg to 0.09 mg/10(9) sperm when uterine tubal fluid was added to the incubation medium. Washed spermatozoa incubated in 0.03 M glucose plus uterine tubal fluid utilized less glucose than did sperm incubated in the glucose medium. These results, along with the increased oxygen utilization (ZO2) values produced by adding uterine tubal fluid to the incubation mediums, might indicate utilization of a uterine tubal substrate. Added uterine tubal fluid resulted in increased ZO2 values (expressed in mul of O2 utilized by 10(8) sperm in 1 hour at 37 C) for whole semen from 10.45 to 12.63. Washed spermatozoa also respired at a significantly greater rate than whole sperm. Respiration rates were greater for sperm incubated with 0.01 M lactic acid than for any other substrate or experiment.     

谷胱甘肽对犬精液冷冻保存效果的影响

为探讨在冷冻稀释液中添加谷胱甘肽（GSH）对犬精液冷冻保存效果的影响,采用按摩法采集5只杂种土犬的精液,离心去精清后,在冷冻液中分别加入0.5、1.0、1.5、2.0、2.5 mmol/L的GSH,制成0.25 mL的冻精进行冷冻保存,以不添加GSH的处理组作为对照组。解冻后在含有5% CO₂的空气、37 ℃、相对饱和湿度条件下孵育10 h,分别在孵育0、2、4、6、8、10 h时检查精子活力。结果显示：冻融后0 h,0.5、1.0 mmol/L GSH处理组的精子活力较高,分别为0.36和0.38,均显著（P<0.05）高于对照组和2.0、2.5 mmol/L处理组,且两者之间差异不显著（P>0.05）;1.0 mmol/L处理组的精子顶体完整率最高,为85.10%,显著（P<0.05）高于对照组,同时,其精子畸形率最低,为23.00%,显著（P<0.05）低于对照组。冻融后体外孵育2、4 h时,0.5、1.0 mmol/L处理组的精子活力均较高,其中,0.5 mmol/L处理组在体外孵育4 h时,其精子活力仍可达到0.30;孵育6 h时,1.0 mmol/L处理组精子活力最高,显著（P<0.05）高于对照组和2.0、2.5 mmol/L处理组;孵育8 h时,各GSH处理组的精子活力均显著（P<0.05）高于对照组;在孵育至10 h时,各GSH处理组的精子活力较其他孵育时间均有较大幅度的下降,未检测到对照组中有呈直线运动的精子。综上提示,在犬精液冷冻液中添加0.5~1.0 mmol/L的GSH能够显著提高冻融后的精子质量和体外存活时间。