不同浓度褪黑素对氯化钠胁迫下宝岛蕉幼苗的影响

为了研究不同浓度褪黑素对于宝岛蕉幼苗氯化钠胁迫的影响，通过不同浓度褪黑素处理宝岛蕉幼苗叶片，研究其对宝岛蕉幼苗叶片和根系的可溶性糖含量、MDA含量、脯氨酸含量及叶质膜透性的影响。结果表明，100μmol/L褪黑素能够降低宝岛蕉幼苗叶质膜透性，提高叶片和根系可溶性糖含量，降低叶片和根系MDA含量，提高叶片和根系脯氨酸含量，提高幼苗的耐盐性，以缓解氯化钠胁迫对宝岛蕉幼苗的伤害。     

Effects of melatonin implantation on cashmere yield,fibre characteristics,duration of cashmere growth as well as growth and reproductive performance of Inner Mongolian cashmere goats

Background

Exogenous melatonin could induce cashmere growth. However, induced growth of cashmere fleece by melatonin implants cannot be combined with the typical growth, resulting in earlier shedding followed by another cycle of cashmere growth. To address this issue, we examine the effects on the cashmere yield, fibre characteristics, and the growth and reproductive performance of cashmere goats of planned administration of melatonin.

Methods

Eighteen half-sib, female goats were assigned to two treatments (n = 9) including a control and a treatment where melatonin (2 mg/kg BW) was implanted at the end of April and end of June. Cashmere growth and shedding were observed for approximately 1 year following implantation. Fibre samples were collected monthly to determine cumulative cashmere length. Initiation and cessation dates for cashmere growth as well as the rate of cashmere growth were calculated. Cashmere yield, weight gain of dam, kidding date, litter size, and birth weight were also recorded.

Results

Melatonin implantation increased cashmere yield by 34.5 % (control 553.7 g vs. melatonin 745.0 g; P < 0.01), cashmere length by 21.3 % (control 95.2 mm vs. melatonin 115.4 mm; P < 0.01), and decreased fibre diameter by 4.4 % (control 14.6 μm vs. melatonin 14.0 μm; P < 0.03). In melatonin-treated goats, the average initiation date was earlier than in control goats (May 18, 2013 vs. July 2, 2013; P < 0.01) but there was a similar cessation date (March 22, 2014 vs. March 27, 2014). Consequently, the duration of cashmere growth was longer in melatonin-treated goats than in control goats (307 vs.270 days; P < 0.01). The final BW, average daily gain, kidding date, litter size, and birth weight were not influenced by melatonin implantation.

Conclusions

These data indicate that melatonin implantation (2 mg/kg BW) on two occasions (late April and June) increased cashmere yield by combining the induced growth of cashmere fleece with the typical growth and decreased the fibre diameter without changing dam growth rate or reproductive performance.     

Estrogen suppresses melatonin-enhanced hyperactivation of hamster spermatozoa

Hamster sperm hyperactivation is enhanced by progesterone, and this progesterone-enhanced hyperactivation is suppressed by 17β-estradiol (17βE₂) and γ-aminobutyric acid (GABA). Although it has been indicated that melatonin also enhances hyperactivation, it is unknown whether melatonin-enhanced hyperactivation is also suppressed by 17βE₂ and GABA. In the present study, melatonin-enhanced hyperactivation was significantly suppressed by 17βE₂ but not by GABA. Moreover, suppression of melatonin-enhanced hyperactivation by 17βE₂ occurred through non-genomic regulation via the estrogen receptor (ER). These results suggest that enhancement of hyperactivation is regulated by melatonin and 17βE₂ through non-genomic regulation.     

褪黑素浸种对盐碱胁迫下大豆种子萌发的影响

为研究褪黑素浸种对盐碱胁迫下大豆种子萌发的影响,以大豆品种垦丰16为试验材料,研究100μmol/L褪黑素浸种对不同浓度混合盐碱（NaCl和NaHCO₃物质的量按1:1混合,配制为0、25、50、100、200mmol/L的盐碱溶液）胁迫下大豆种子萌发的影响。结果表明：与对照相比,随盐碱浓度提升,大豆种子发芽率、发芽指数、芽鲜重和芽干重呈不断降低趋势,超氧化物歧化酶、过氧化物酶、过氧化氢酶、谷胱甘肽还原酶和谷胱甘肽过氧化物酶活性呈现先升高后降低的趋势,抗坏血酸过氧化物酶活性呈不断上升趋势;渗透调节物质可溶性糖、可溶性蛋白和脯氨酸含量呈现先升高后降低的趋势;膜脂过氧化产物丙二醛、H₂O₂含量、$\mathop{{O}}_{2}^{{\mathop{}_{\ .}^{-}}}$产生速率呈不断上升趋势。褪黑素浸种可提高不同浓度盐碱胁迫下大豆种子发芽率、发芽指数、芽鲜重、芽干重和抗氧化酶活性以及渗透调节物质含量,降低丙二醛、H₂O₂含量和$\mathop{{O}}_{2}^{{\mathop{}_{\ .}^{-}}}$产生速率。综上所述,褪黑素浸种可以缓解不同浓度盐碱胁迫对大豆种子发芽的抑制作用,并能提高抗氧化酶活性和渗透调节物质含量,降低膜脂过氧化程度。     

褪黑素在牛体外胚胎生产中的应用研究进展

近年来牛体外胚胎生产取得很大进展,可以稳定地在体外获得囊胚,但体外生产效率偏低,不能满足产业需要。在牛体外胚胎生产过程中很容易产生活性氧和活性氮,导致配子和胚胎受到氧化应激或硝化应激。褪黑素作为一种强有力的抗氧化剂和抗凋亡剂,可以直接清除有毒的氧衍生物,减少活性氧的形成,在牛体外胚胎生产过程中发挥积极作用。本文主要对褪黑素在牛卵母细胞体外成熟、体外受精、早期胚胎发育、配子和胚胎冷冻保存等方面的研究进行综述,为后续体外胚胎生产技术的优化研究和推广应用提供参考。     

Effects of melatonin on gut motility

AIM: To investigate the influence of melatonin at different concentrations on the gut motility. METHODS: Male C57BL mice were used in the study. The mice were intraperitoneally injected with melatonin at doses of 1 mg/kg, 5 mg/kg, 50 mg/kg and 75 mg/kg. The colon bead expulsive time was measured at 15 min and 45 min after injection. The melatonin antagonist luzindole at a dose of 5 mg/kg was used before injection of 75mg/kg melatonin. The gut transit time was also recorded with oral Evens blue after injection of melatonin. RESULTS: Compared with control group, melatonin at the dose of 1 mg/kg at 15 min decreased the colon bead expulsive time. However, melatonin at high dose (75 mg/kg) prolonged the colon bead expulsive time compared with the control, which was effectively blocked by melatonin antagonist luzindole. Compared with control group, injection of melatonin at the dose of 5 mg/kg at 45 min decreased the colon bead expulsive time. However, melatonin at high dose (75 mg/kg) prolonged the colon bead expulsive time. No difference of colon bead expulsive time between using 1 mg/kg and 50 mg/kg melatonin was observed. In whole gut transit time test, after injection of melatonin at the doses of 1 mg/kg and 5 mg/kg, the time was decreased. The expulsive time of fecal pellet with Evens blue was shorten as compared with control group. However, the gut transit time was significantly prolonged after high dose of melatonin (75 mg/kg) was used. CONCLUSION: Low dose of melatonin increases while high dose decreases the gut motility. Melatonin antagonist luzindole effectively blocks the latter effect.     

小鼠褪黑激素注射的毒理性研究

[目的]进一步为褪黑激素的腹腔注射毒理性评价提供依据。[方法]分别进行急性毒性试验、亚急性毒性试验和小鼠Ames、微核、精子畸形试验,研究小鼠褪黑激素注射的毒理性。[结果]褪黑激素小鼠腹腔注射急性毒性试验LD50为（255．910±41．188）mg／kg;亚急性毒性试验结果显示,各组红细胞数和白细胞数均在正常范围内,淋巴细胞、中性粒细胞、单核细胞、嗜酸性细胞、嗜碱性细胞差异不显著;解剖未发现异常变化,各组织切片亦无病理性变化。小鼠Ames、微核试验和精子畸形试验结果表明,小鼠腹腔注射褪黑激素无致突变作用。不会诱发小鼠体细胞染色体和精子发生畸变。[结论]小鼠腹腔注射褪黑激素,血象、部分血液生化指标和组织均未产生毒性影响,同时也无染色体畸变、诱发突变和精子致畸作用,但推测褪黑激素可能对神经有一定的毒性。     

埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响

为研究非长绒期埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响,本试验选择2～6岁能繁母羊150只,每个年龄段根据产绒量和体重将母羊随机分为对照组和试验组,试验组于2014年4月30日和6月30日埋植2 mg/kg BW褪黑激素于耳部皮下。自埋植开始至试验结束(2015年4月底抓绒),逐月观察山羊绒生长情况,并于抓绒时采集绒样,分析埋植对山羊绒生长的影响。结果表明:与对照组相比,试验组所有年龄段山羊绒产量和绒长度均显著提高,绒细度显著降低(P<0.05),其中5岁埋植组山羊的产绒量提高幅度和细度下降幅度最大,分别达到28.75%、4.94%,6岁埋植组山羊绒长度增加幅度最大,为29.27%。综上,不同年龄内蒙古绒山羊埋植外源褪黑激素均有促进山羊绒生长和提高产量作用,但不同年龄绒山羊增产效果不一致,并且褪黑激素对于提高内蒙古绒山羊后期的生产力作用更大。     

干旱胁迫下褪黑素对小麦幼苗生长、光合和抗氧化特性的影响

为探究褪黑素对小麦幼苗抗旱性的调节作用,明确褪黑素提高小麦抗旱能力的作用途径,以小麦水地品种西农9871为材料,通过盆栽试验,分析了干旱胁迫下根施褪黑素（100 μmol·L^-1）对小麦幼苗生长、光合特性及活性氧代谢的影响。结果表明,干旱胁迫抑制了小麦的生长,降低了叶片叶绿素含量、气孔导度、净光合速率及PSⅡ最大光化学效率,导致过氧化氢（H₂O₂）与丙二醛（MDA）积累增加及抗氧化酶活性、抗氧化剂含量升高。在干旱胁迫下根施褪黑素可增加小麦幼苗的生物量和根冠比,维持较高的相对叶片含水量、叶绿素含量、净光合速率及光化学效率,并进一步提高过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、过氧化物酶(POD)活性及抗坏血酸（ASA）和谷胱甘肽（GSH）的含量,减少了H₂O₂ 与MDA的积累。复水后,根施褪黑素处理的小麦幼苗生长表现出较快的恢复能力。以上结果说明,在干旱胁迫下,褪黑素通过增加根冠比,促进水分吸收,改善叶片的水分状况,并通过增强抗氧化能力,减轻氧化伤害。褪黑素处理的植株表现出较好的水分状况和较轻的氧化伤害,有利于其维持较高的光合能力,从而提高小麦幼苗的抗旱性及恢复生长的能力。