为探究陆生龟类胚胎间是否存在信息交流,本实验以红耳龟(Trachemys scripta elegans)为研究对象,将150枚龟卵随机均分为两组,分别置于27℃和31℃下孵化,分别在孵化15 d (第一个1/4孵化期)、30 d (第二个1/4孵化期)后,从I、II两组各取17枚卵组成第III、第IV组在27℃下混合孵化,检测各组胚胎的心率、孵化期及孵化率。结果显示:第III组整体孵化率和追溯卵的首次分组情况后孵化率都领先于其他各组,第IV组在追溯了卵的第二次分组情况后孵化率也较第I、II组有一定的上升。第I组破壳高峰期在第95~98 d,第II组破壳高峰期在第63~64 d,而第III、IV组破壳时间在I、II组之间。与第I组胚胎心率差异显著性比较可知,第III组和第IV组组合中的第I组的胚胎心率进程明显加快,说明第III、IV两组内的胚胎能够互相影响,推测可能通过信息交流促使发育进度不同的胚胎趋于同步孵化,有助于降低稚龟破壳初期被天敌捕食的比率。<br/>To explore whether information exchange existed between terrestrial turtle embryos, this experiment took the red-eared turtle (Trachemys scripta elegans) as the research object, and 150 turtle eggs were randomly and equally divided into two groups and incubated at 27˚C and 31˚C, respectively. After incubation for 15 d (the first quarter incubation period), and 30 d (after the second quarter incubation period), 17 eggs were collected from each of the two groups I and II to form group III and group IV, and then they were mixed and incubated at 27˚C. The heart rate, incubation period and hatchability of the embryos in each group were detected. The results showed that the overall hatchability and the hatchability after tracing the first grouping of eggs of group III were superior to other groups, while the hatchability of group IV after tracing the second group of eggs was also increased to a certain extent compared with groups I and II. The peak period of shelling in group I was 95~98 days, the peak period of shelling in group II was 63~64 days, and the time of shelling in groups III and IV was between I and II. The heart rate progression of the embryos from group I combined in groups III and IV was significantly faster than that of the initial group I, indicating that the embryos in Groups III and IV could influence each other, and it was speculated that the information exchange might promote the synchronous hatching of embryos with different development progress, which helps to reduce the rate of predation by natural enemies in the early stage of hatchling.
为探究陆生龟类胚胎间是否存在信息交流,本实验以红耳龟(Trachemys scripta elegans)为研究对象,将150枚龟卵随机均分为两组,分别置于27℃和31℃下孵化,分别在孵化15 d (第一个1/4孵化期)、30 d (第二个1/4孵化期)后,从I、II两组各取17枚卵组成第III、第IV组在27℃下混合孵化,检测各组胚胎的心率、孵化期及孵化率。结果显示:第III组整体孵化率和追溯卵的首次分组情况后孵化率都领先于其他各组,第IV组在追溯了卵的第二次分组情况后孵化率也较第I、II组有一定的上升。第I组破壳高峰期在第95~98 d,第II组破壳高峰期在第63~64 d,而第III、IV组破壳时间在I、II组之间。与第I组胚胎心率差异显著性比较可知,第III组和第IV组组合中的第I组的胚胎心率进程明显加快,说明第III、IV两组内的胚胎能够互相影响,推测可能通过信息交流促使发育进度不同的胚胎趋于同步孵化,有助于降低稚龟破壳初期被天敌捕食的比率。
红耳龟,孵化,信息交流,心率
Tiansheng Zhu, Ming Wang, Dongyun Chen
College of Life Sciences, Hainan Normal University, Haikou Hainan
Received: Feb. 28th, 2021; accepted: Mar. 8th, 2021; published: Mar. 29th, 2021
To explore whether information exchange existed between terrestrial turtle embryos, this experiment took the red-eared turtle (Trachemys scripta elegans) as the research object, and 150 turtle eggs were randomly and equally divided into two groups and incubated at 27˚C and 31˚C, respectively. After incubation for 15 d (the first quarter incubation period), and 30 d (after the second quarter incubation period), 17 eggs were collected from each of the two groups I and II to form group III and group IV, and then they were mixed and incubated at 27˚C. The heart rate, incubation period and hatchability of the embryos in each group were detected. The results showed that the overall hatchability and the hatchability after tracing the first grouping of eggs of group III were superior to other groups, while the hatchability of group IV after tracing the second group of eggs was also increased to a certain extent compared with groups I and II. The peak period of shelling in group I was 95~98 days, the peak period of shelling in group II was 63~64 days, and the time of shelling in groups III and IV was between I and II. The heart rate progression of the embryos from group I combined in groups III and IV was significantly faster than that of the initial group I, indicating that the embryos in Groups III and IV could influence each other, and it was speculated that the information exchange might promote the synchronous hatching of embryos with different development progress, which helps to reduce the rate of predation by natural enemies in the early stage of hatchling.
Keywords:The Red-Eared Slider Turtle, Hatching, Information Exchange, Heart Rate
Copyright © 2021 by author(s) and Hans Publishers Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY 4.0).
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胚胎时期是生命最脆弱的时期,早期认为胚胎只能被动地响应环境的变化。进一步的研究表明,胚胎具有主动响应环境变化的行为调节能力 [
目前,有关温度、湿度、光照等非生物因子影响稚龟健康状况的研究已取得大量成果。例如在相对较高的温度下(适宜范围内),胚胎对卵黄的利用率 [
因此,本实验从红耳龟的胚胎入手,通过对胚胎心率的测定及不同组龟卵孵化率的统计,以探究出陆生龟类胚胎个体间是否会互相影响,促进胚胎的发育进度达到同步孵化。为进一步研究陆生龟胚胎的信息交流提供基础数据。
试验采用购自海口东山鸿旺水产养殖场的产于同一天的红耳龟卵150枚,龟卵的形态学指标没有显著性差异。在实验室短暂静置稳定后用于分组孵化。
SPS-250智能生化培养箱购自宁波海曙赛福实验仪器厂;0~150游标卡尺购自上海申韩量具有限公司;心率仪(NEWTON ABBOT-ENGLAND BUDDY01);电子天平。
图1. 分组孵化示意图
如图1所示,将150枚龟卵随机均分为I、II两组(各75枚),分别将I组和II组置于27℃和31℃的孵化箱中恒温孵化。15 d后,从I、II组中各随机取17枚卵组合为第III组,将第III组(34枚)放置于27℃的孵化箱中恒温孵化至破壳,I组(58枚)和II(58枚)组依旧分别放置于27℃和31℃的孵化箱中恒温孵化。
孵化30 d后,从I、II组中各随机取17枚卵组合为第IV组,将第IV组(34枚)放置于27℃的孵化箱中恒温孵化出壳,I组(41枚)、II组(41枚)依旧分别放置于27℃、31℃的孵化箱中恒温孵化出壳,整个孵化期间严格控制四组的光线、湿度保持一致。
在胚胎孵化期间,每隔15天(理想状态下的四分之一孵化期)对所有胚胎的心率进行测量并统计。
如表1,通过对各组孵化率情况进行差异显著性分析可知,第III组总孵化率为83.3%,显著高于其他各组;其中来自I组中的卵孵化率为87.5%,与第I组相比具有差异显著性(P < 0.05),与第IV组中来自第I组卵的孵化率无显著差异(P > 0.05),来自II中的卵孵化率为78.5%,显著高于第II组和第IV组中来自第II组卵的孵化率(P < 0.05);第IV组总孵化率为58.6%,其中来自I,II组中的卵孵化率分别为75.0%和38.4%,与第I组和第II组卵的孵化率无显著差异(P > 0.05)。
组别 | 入孵卵数 (n) | 受精卵 (n) | 出壳数 (n) | 胚胎死亡 (n) | 孵化率 (%) |
---|---|---|---|---|---|
第I组 | 41 | 35 | 23 | 12 | 65.7 |
第II组 | 41 | 33 | 10 | 23 | 30.3 |
第III组(I组卵) | 17 | 16 | 14 | 2 | 87.5 |
第III组(II组卵) | 17 | 14 | 11 | 3 | 78.5 |
第IV组(I组卵) | 17 | 16 | 12 | 4 | 75.0 |
第IV组(II组卵) | 17 | 13 | 5 | 8 | 38.4 |
表1. 孵化率情况统计表
孵化期/d | 第I组/(n) | 第II组/(n) | 第III组/(n) | 第IV组/(n) | ||
---|---|---|---|---|---|---|
I组卵 | II组卵 | I组卵 | II组卵 | |||
62 | 0 | 1 | 0 | 0 | 0 | 0 |
63 | 0 | 5 | 0 | 0 | 0 | 0 |
64 | 0 | 4 | 0 | 0 | 0 | 0 |
71 | 0 | 0 | 0 | 0 | 0 | 1 |
73 | 0 | 0 | 0 | 0 | 1 | 3 |
76 | 0 | 0 | 0 | 3 | 0 | 0 |
78 | 0 | 0 | 0 | 4 | 0 | 0 |
79 | 0 | 0 | 0 | 1 | 0 | 0 |
80 | 0 | 0 | 1 | 1 | 0 | 0 |
81 | 0 | 0 | 2 | 1 | 0 | 1 |
82 | 0 | 0 | 1 | 1 | 0 | 0 |
83 | 0 | 0 | 3 | 0 | 1 | 0 |
84 | 0 | 0 | 1 | 0 | 2 | 0 |
85 | 0 | 0 | 2 | 0 | 1 | 0 |
86 | 0 | 0 | 1 | 0 | 0 | 0 |
87 | 0 | 0 | 2 | 0 | 1 | 0 |
88 | 0 | 0 | 1 | 0 | 0 | 0 |
90 | 2 | 0 | 0 | 0 | 2 | 0 |
92 | 3 | 0 | 0 | 0 | 4 | 0 |
93 | 1 | 0 | 0 | 0 | 0 | 0 |
94 | 2 | 0 | 0 | 0 | 0 | 0 |
95 | 7 | 0 | 0 | 0 | 0 | 0 |
97 | 2 | 0 | 0 | 0 | 0 | 0 |
98 | 4 | 0 | 0 | 0 | 0 | 0 |
102 | 2 | 0 | 0 | 0 | 0 | 0 |
合计 | 23 | 10 | 14 | 11 | 12 | 5 |
表2. 稚龟具体破壳时间统计表
由表2可知,第I组的孵化期为第90至102天,其中第95至98天为孵化高峰期。第II组的孵化期为第62至64天,集中在第63和64两天出壳。第III组的孵化期为第76至88天。第IV组的孵化期为第71至92天,该期间破壳数量分布极为分散。通过比对III、IV组中各稚龟来源发现,第III组中来自I组卵的孵化期略短于第I组卵的孵化期,来自第II组卵的孵化期显著长于第II组卵的孵化期,同时,来自第II组的卵孵化期略短于来自第I组的卵,但其来自I、II的卵孵化期有一定的时间交叉。第IV组中来自第I组卵的孵化期略短于第I组卵,来自第II组卵的孵化期长于第II组卵,且显著短于来自第I组卵的孵化期,两者之间几乎不存在时间交叉。
在孵化期间多次进行心率值测量发现,可根据心率情况将胚胎发育进度人为地概括为五个阶段:
① 无心率阶段,该阶段心率值为0次/分(下面简称为“一阶段”);
② 心率值不断波动无法准确测量阶段(下面简称为“二阶段”),该阶段心率值在100~500次/分之间不断跳动,无定值,无法测量;
③ 心率值极高却稳定可测量阶段(下面简称“三阶段”),该阶段心率值稳定在100~500次/分之间的某一数值,可测量;
④ 心率值较低且稳定可测量阶段(下面简称“四阶段”),该阶段心率值稳定在35~65次/分之间的某一数值,可测量;
⑤ 心率值较高且稳定可测量阶段(下面简称“五阶段”),该阶段心率值稳定在78~92次/分钟之间的某一数值,可测量。
图2. 各组心率值变化情况图
若以时间为标准,每15天作为一个区间,可将胚胎的孵化时间分为四个时期(即一期,二期,三期,四期分别对应孵化的第1~15天,第16~30天,第31~45天,第46~60天)。结合图2以及3.2.1的内容可得出:
组别 | 一期 (1~15 d) | 二期 (16~30 d) | 三期 (31~45 d) | 四期 (46~60 d) |
---|---|---|---|---|
I组 | 一阶段 | 二阶段 | 三阶段 | 四阶段 |
II组 | 二阶段 | 三阶段 | 四阶段 | 五阶段 |
III组(I组卵) | / | 二阶段 | 三阶段 | 四阶段 |
III组(II组卵) | / | 三阶段 | 略低于四阶段 | 四五阶段间 |
IV组(I组卵) | / | / | 三阶段 | 四阶段 |
IV组(II组卵) | / | / | 四阶段 | 五阶段 |
表3. 胚胎发育时间与发育阶段比对表
组别 | 一期 | 二期 | 三期 | 四期 |
---|---|---|---|---|
第I组 | 10% | 74% | 73% | 56% |
第II组 | 48% | 30% | 43% | 27% |
第III组 | / | 79% | 73% | 73% |
第IV组 | / | / | 50% | 50% |
表4. 各组心率值有无情况统计表
由表4可知,第I组中有心率的胚胎占卵量百分比在一期极低,二期显著升高,三、四期接连有所降低,但数据一直保持在中等偏上水平。第II组中有心率的胚胎占卵量百分比在一期相对I组较高,之后则波动降至极低水平。第III组中有心率的胚胎占卵量百分比在二期极高,三、四期略微下降但仍处于极高水平。第IV组中有心率的胚胎占卵量百分比在三、四期无变化,处于中等水平。
从统计结果可知,第I组和第II组受精卵孵化率都比较低。据李新民 [
第IV组孵化率较低且来源不同的龟卵孵化率差距较大,可能是由于受精卵混合时间较晚,胚胎间相互影响程度降低,前期孵化温度成为影响孵化率的主要因素 [
实验结果可知,第II组卵破壳用时远短于其他组。而第I组卵破壳用时最长,说明在一定范围内,高温会使胚胎发育速度加快 [
第III组卵整体集中在第76至88天破壳,且来自第I、II组的卵的孵化期有所重合,研究报道孵化期胚胎之间存在信息交流和能量交换 [
第IV组卵孵化期跨度较长,且中间多处有明显间隔。其中来自第II组的卵由于受到孵化温度的影响,孵化时长明显长于第II组。来自第I组的卵整体领先于第I组可能是因为来自第II组的胚胎通过释放生物信号加速了其整体的发育速度 [
研究报道鸟类和海龟受精卵孵化时,不同时期心率有不同的特点,心率值直接反映胚胎发育的进度 [
一阶段:在孵化初期,胚胎进入有丝分裂,还未分化出心脏,因此在使用心率仪测定心率时无法测出心率值;二阶段:卵内发育出心脏,产生了心率,但此时的心脏自律性较差,受外界刺激高度敏感,因此在测量过程中心率值会不断波动无法准确测量;三阶段:神经系统发育不完全,胚胎新陈代谢旺盛,心脏自律性很高;四阶段:在神经系统的调控下胚胎心率逐渐趋于正常龟类心率值;五阶段:孵化末期,稚龟即将破壳,短时间内需要消耗较多的营养物质提供能量破壳,心率值又有所偏高。
从实验结果可知,第I组胚胎心率出现较晚,而第II组心率出现的较早。耿军 [
从表3可知,第III组从二期始,其中来自第II组胚胎心率的五个阶段明显降速,最终与来自第I组胚胎的进度几乎相同,可能是因为孵化温度的降低。徐意 [
从统计结果来看,各组稚龟的孵化时长与其心率值情况完全契合,说明心率值直接用于反映胚胎发育进度在红耳龟上有较高的可靠性。若准确地将心率值情况与孵化时间相匹配,在日后的龟类研究及养殖中,可通过较为简便的心率测量方法确定龟类所处的发育阶段,及时调整孵化环境,从而一定程度控制龟类胚胎的生长发育。
通过各项指标检测,认为在陆生龟胚胎发育过程中,可能也存在信息交流,可使不同发育进程中的胚胎趋于同步,从而提高了稚龟破壳时的存活率,对于维系物种繁衍和进化起到了重要作用。
朱天生,王 明,陈栋芸. 不同孵化组合对红耳龟胚胎发育的影响Effects of Different Hatching Combinations on Embryonic Development of Red-Eared Tortoise[J]. 水产研究, 2021, 08(01): 9-16. https://doi.org/10.12677/OJFR.2021.81002