盐度对花鲈幼鱼鳃、脾及肌肉组织结构的影响*

2020-02-13 06:56温久福蓝军南区又君李加儿
渔业科学进展 2020年1期
关键词:幼鱼血细胞盐度

温久福 蓝军南,2 曹 明 周 慧 区又君 李加儿

盐度对花鲈幼鱼鳃、脾及肌肉组织结构的影响*

温久福1蓝军南1,2曹 明3周 慧1区又君1①李加儿1

(1. 中国水产科学研究院南海水产研究所 农业农村部南海渔业资源开发利用重点实验室 广州 510300;2. 上海海洋大学 水产种质资源发掘与利用教育部重点实验室 水产科学国家级实验教学示范中心 海洋动物系统分类与进化上海高校重点实验室 上海 201306;3. 广东省渔业种质保护中心 广州 511453)

为了探究不同盐度对花鲈()幼鱼组织结构的影响,用组织学方法对不同盐度条件下(0、10、15、20、30)花鲈幼鱼的鳃、脾及肌肉组织结构进行研究。结果显示,盐度为0时,花鲈幼鱼鳃丝排列紧密,顶端膨大呈棒状,鳃小片细胞饱满,有少量泌氯细胞。花鲈幼鱼鳃丝宽度随盐度的升高而缩小,鳃小片间距则逐渐增大,差异显著(<0.05);盐度为20时,部分鳃小片变形脱落,鳃丝上的泌氯细胞明显增多增大;盐度为30时,鳃丝宽度较大,出现断裂脱落,鳃丝上细胞排列疏松,泌氯细胞明显膨大,有溶解现象。脾脏在淡水条件下(盐度为0),淋巴细胞数目较少,血细胞较多;在低盐环境中(盐度为10、15),淋巴细胞增大,数量增多,黑色素巨噬细胞中心数量增加;在高盐度下(盐度为30),脾细胞和部分淋巴细胞出现肿大、空泡化现象,细胞排列疏松。盐度为0时,花鲈幼鱼肌纤维排列较为疏松,多角形或长椭圆形,长径和短径较大、密度较小;盐度为15时,肌纤维短径变小、密度增大,与0、10盐度组均差异显著,盐度为30时,肌纤维长径增大、密度减小;随着盐度的增加,肌纤维长径和短径均有先减小后增加的趋势,单位面积肌纤维数量则先增加后减小,差异显著(<0.05)。结果表明,花鲈幼鱼鳃、脾及肌肉组织结构变化特征与其所处的环境盐度有关。

盐度;花鲈;鳃;脾脏;肌肉;组织结构

1 材料与方法

1.1 实验材料

实验用鱼采自中国水产科学研究院南海水产研究所珠海基地,为淡水培育幼苗,暂养于蓝色养殖箱中(55 cm×30 cm×42 cm),养殖用水为曝气处理的自来水,盐度为0,水温为27℃~29℃,连续24 h充气,每日定时投喂2次配合饲料,日换水量为总水量的1/3,暂养时间为7 d。暂养结束后,挑选体格健壮,规格相近[平均体长为(4.01±0.27) cm]的个体进行实验。

1.2 实验设计

实验设5个实验组S0、S10、S15、S20和S30,对应盐度分别为0、10、15、20和30,其中,S0为对照组,每组设3个平行,每个实验组放幼鱼50尾。实验用水为曝气自来水与净化处理的自然海水调配而成。实验开始前,盐度每隔24 h提高5,用盐度计进行校准,误差不超过0.5,达到相应盐度后开始实验。实验期间,充气、水温控制、换水量及投喂管理与暂养时相同。实验时间为30 d。

1.3 实验方法

实验结束后,在各实验组随机取样,取幼鱼右侧鳃丝、脾脏及躯干部右侧肌肉组织样品,于4%多聚甲醛溶液中固定24 h。将固定好的组织样品制成石蜡切片,常规HE染色,中性树脂封片,Zeiss显微镜下观察并拍照。

1.4 数据测量及分析

采用Image-ProPlus 5.1软件测量鳃丝宽度、鳃小片长度、鳃小片宽度、鳃小片间距;参考秦桂香等(2010)的方法测量肌纤维的长径和短径,以实验用显微镜(200×)拍摄的图片(视野的一个内切矩形)为单位面积计算肌纤维密度。测量所得数据均用SPSS 22.0软件和Excel 2010软件进行统计学分析。

2 结果

2.1 不同盐度条件下花鲈幼鱼存活率

不同盐度条件下花鲈幼鱼养殖死亡率见表1,除盐度为30条件下有3尾鱼死亡外,其他组均无死亡。

表1 不同盐度下花鲈幼鱼的死亡率

Tab.1 Mortality of L. maculatus juveniles under different salinities

2.2 鳃

盐度为0时,花鲈幼鱼鳃丝排列紧密,形状较长,顶端膨大呈棒状,内有大量的血细胞;鳃丝两侧有较长的扁平囊状鳃小片平行排列;鳃小片由扁平细胞、柱细胞、血细胞及泌氯细胞组成,细胞饱满,排列紧密;有少许泌氯细胞分布于鳃小片基部,近乎椭圆形,体积较小细胞核呈蓝紫色,细胞质着色较浅;鳃小片上有较多的血细胞,扁平细胞较厚,排列紧密(图1.1)。盐度为10时,泌氯细胞增大,数量增多,血细胞减少(图1.2);鳃丝宽度显著小于S0组,鳃小片变宽,扁平细胞增厚,其他结构无明显变化(表2)。盐度为15时,鳃丝较长,排列整齐,宽度显著变窄(<0.05);鳃小片间距增大,长度缩短,宽度变窄,与S0、S10组均差异显著(<0.05);泌氯细胞体积增大,数量增多(图1.3)。盐度为2时,鳃丝较S15组宽,鳃小片减少,鳃小片间距较宽,长度缩短(表2);泌氯细胞体积明显增大,细胞排列疏松,扁平上皮细胞有脱落溶解现象(图1.4)。盐度为30时,鳃丝宽度较大,出现断裂脱落现象,鳃丝上细胞排列疏松,泌氯细胞明显膨大,见溶解状态(图1.5);鳃小片数量较少,形态不规则,小片间距和长度显著增大(<0.05) (表1)。

图1 盐度对花鲈幼鱼鳃的影响

1:盐度0;2:盐度10;3:盐度15;4:盐度20;5:盐度30

BC:血细胞;CSC:泌氯细胞;GL:鳃小片;PVC:扁平上皮细胞;PC:柱细胞;CC:软骨细胞

1:Salinity 0; 2:Salinity 10; 3:Salinity 15; 4:Salinity 20; 5:Salinity 30

BC: Blood cell;CSC: Chloride secreting cell;GL: Gill lamellae;PVC: Pavement cell;PC: Pillar cell;CC: Chondrocyte

表2 盐度对花鲈幼鱼鳃组织测量性状的影响

Tab.2 The effect of salinity on the gill meristic characters of L. maculatus juveniles (μm)

注:同列数据上标不同字母表示组间差异显著(<0.05),下同

Note: Different superscripts in the same column indicate significant differences between groups (<0.05), the same as below

2.3 脾脏

花鲈脾脏外层为由结缔组织和扁平细胞组成的被膜,被膜往里为实质组织,结缔组织往内部延伸使实质组织形成脾小叶,小叶间排列紧密界限不明显。脾脏内有大量的血管和血细胞。脾实质由红髓质和白髓组成,二者分界不明显,互相穿插;红髓染色较浅,主要由红细胞组成;白髓染色较深,主要由大量的淋巴细胞和少量巨噬细胞及颗粒细胞组成;脾细胞形态多样,呈圆形、椭圆形或多角形(图2)。盐度为0时,脾脏有较多血细胞,淋巴细胞较少(图2.1);盐度为10时,血细胞减少,有较多的巨噬细胞,淋巴细胞聚集中心明显(图2.2);盐度为15时,出现较多的黑色素巨噬细胞中心(图2.3);盐度为20时,脾窦范围增大,血细胞增多(图2.4)。盐度为30时,见部分脾细胞和淋巴细胞肿大,并出现空泡,细胞间排列较为疏松,有少许细胞溶解,差异较为明显(图2.5)。

2.4 肌肉

花鲈幼鱼肌肉组织由神经、结缔组织、血管以及形状大小不规则的肌纤维组成,肌纤维由结缔组织包围成纤维束,肌纤维有许多细胞核,排列在基膜附近,椭圆形或梭形,呈蓝紫色。肌肉横切肌纤维呈多角形、椭圆形或梭形,排列较紧密,直径不均一(图3)。盐度为0时,肌纤维排列较为疏松,多角形或长椭圆形,长径和短径较大,密度较小(表3)。盐度为10时,肌纤维长径变小,短径变化不明显,排列较紧密,形状较规则,呈多角形,密度显著增大(图3、表3)。盐度为15时,肌纤维短径变小,密度增大,与S0、S10组均差异显著(<0.05)。盐度为20时,肌纤维椭圆形或多角形,排列疏松,纤维束间隙较大(图3d)。盐度为30时,肌纤维长径增大,密度减小(表3)。

图2 盐度对花鲈幼鱼脾脏的影响

1:盐度0;2:盐度10;3:盐度15;4:盐度20;5:盐度30,“↑”示淋巴细胞肿大和空泡化BC:血细胞;E:椭圆体;EC:内皮细胞;C:脾索;G:粒细胞;L:淋巴细胞;LC:淋巴细胞中心;M:巨噬细胞;MC:黑色素巨噬细胞中心;S:脾窦;ST:脾小梁;SRBC:衰老红细胞

1:Salinity 0; 2:Salinity 10; 3:Salinity 15; 4:Salinity 20; 5:Salinity 30. “↑”indicate lymphocyte enlargement and vacuolation BC: Blood cell; C: Splenic cord; E: Ellipsoid; G: Granulocyte; L: Lymphocyte; LC: Lymphocytes center; M: Macrophage;MC: Melano-macrophage center; S: Splenic sinus; ST: Spleen trabecular; SRBC: Senile red blood cell

图3 盐度对花鲈幼鱼肌肉的影响

1:盐度0;2:盐度10;3:盐度15;4:盐度20;5:盐度30

BC:毛细血管;CT:结缔组织;MF:肌纤维;MN:肌细胞核;NF:神经纤维

1:Salinity 0; 2:Salinity 10; 3:Salinity 15; 4:Salinity 20; 5:Salinity 30

BC: Blood capillary; CT: Connective tissue; MF: Muscel fiber; MN: Myocyte nucleus; NF: Nerve fiber

表3 盐度对花鲈幼鱼肌肉测量性状的影响

Tab.3 The effect of salinity on the muscle meristic characters of L. maculatus juveniles

3 讨论

该实验中各组花鲈幼鱼的存活率都较高,表明在0~30的盐度范围内,花鲈幼鱼能够保持完整的渗透调节能力,能够生长、存活。

该实验结果显示,花鲈在淡水和低盐环境中(S0和S10)其鳃丝和鳃小片较宽、形态较长,细胞饱满,排列紧密,有利于与水体充分接触,更易摄入水中的无机离子以适应低渗环境;泌氯细胞体积较小,数量很少,表现出适应低渗环境的形态特征;扁平细胞较厚,排列紧密,可能是防止离子自由渗漏(Evans, 2005)。随着盐度的增加,鳃丝宽度变小,鳃小片间距增大,长度变短;泌氯细胞体积显著增大。当盐度达到20时,部分鳃小片变形脱落,鳃丝上的泌氯细胞明显增多增大;盐度为30时,鳃丝宽度较大,出现断裂脱落,鳃丝上细胞排列疏松,泌氯细胞明显膨大,见溶解状态。这与鲻鱼()、罗非鱼()(于娜等, 2012; Nolan, 1999)的研究结果基本一致。随着盐度的增加,花鲈幼鱼为适应环境需增加水、氧交换量以维持渗透平衡,其鳃丝的结构发生一定程度的萎缩,鳃丝细胞缩小和鳃小片间距增大,当盐度超过一定的耐受范围(盐度为30时),其鳃丝结构不同程度的脱落或分离。鳃丝上的泌氯细胞数量明显增加,胞体变大,说明其泌氯功能和细胞的代谢水平明显提高,发挥了Na+、K+、Cl–等离子代谢平衡调节作用(Prunet, 1994)。花鲈为维持机体渗透平衡,在不同盐度下,鳃组织发生适应性改变,过高的盐度波动会造成组织损伤。

肌肉的组织结构主要由构成肌肉的肌纤维数量、肌纤维的直径大小、长度以及肌原纤维决定,而肌纤维直径是描述肌肉特征的重要参数。研究表明,营养水平、运动方式、环境因子等直接影响肌纤维的发育(郭琼林等, 1993; Johnston, 2000、2003)。研究结果显示,随着盐度的增加,花鲈幼鱼肌纤维长径和短径均有先减小后增加的趋势,单位面积肌纤维数量则呈先增加后减小的趋势,差异显著(<0.05)。研究表明,肌纤维数目在出生前已固定,因此,在出生后的生长发育中主要是肌纤维直径与长度的增加(Stickland, 1975)。肌纤维密度反映了肌肉增生速率的大小,推测是鱼类增长速度在不同盐度下差异的原因之一(关文静等, 2008)。本研究在不同盐度条件下,花鲈幼鱼的肌肉组织结构产生差异,随着肌纤维增粗,肌肉间结缔组织与脂肪组织的增加,肌纤维密度下降,该结果可为解析其生长调控机理提供参考。

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Effects of Salinity on the Histological Structure of the Gills, Spleen, and Muscle inJuveniles

WEN Jiufu1, LAN Junnan1,2, CAO Ming3, ZHOU Hui1, OU Youjun1①, LI Jiaer1

(1. South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Key Laboratory of South China Sea Fishery Resources Exploitation andUtilization, Ministry of Agriculture and Rural Affairs, Guangzhou 510300; 2. Shanghai Ocean University, Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education; National Demonstration Center for Experimental Fisheries, Science Education; Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai 201306; 3. Guangdong Provincial Fishery Germplasm Conservation Center, Guangzhou 511453)

To explore the histological features ofjuveniles cultured at different salinities, the structures of the gills, spleen, and muscle were analyzed at different salinities (0, 10, 15, 20, and 30) via histological analysis. The results showed that at salinity 0, the gill filaments ofjuveniles were closely arranged, the top of the gills expanded into a rod shape, and the gill cells were plump with more chlorine-secreting cells; the breadth of the gill filaments decreased, and the intervals of the gill lamella became larger as the salinity increased (<0.05). At salinity 20, some gill lamellas decomposed and fell off, the number of chlorine-secreting cells on the gill filaments increased significantly. At salinity 30, the number and size of chloride cells increased as the salinity increased and some chloride cells expanded and dissolved. In freshwater, more blood cells and fewer lymphocytes were observed in the spleen, whereas in the hyposaline environment (salinity 10 and 15), the lymphocytes were enlarged and the number of melanin macrophages increased. At high salinity (30), the spleen cells and some lymphocytes showed swelling and vacuolation and were loosely arranged. At salinity 0, the muscle fibers of the juveniles were loosely arranged, polygonal or oblong, with larger major and minor diameters and smaller densities. With the increasing salinity, both the major and minor diameters of muscle fibers tended to decrease first and then increase again. At salinity 15, the short diameter of muscle fibers decreased and their densities increased, which were significantly different from that observed at salinity 0 and 10. At salinity 30, the long diameter of muscle fibers increased and their densities decreased. In summary, as the salinity increased, both the long and short diameters of muscle fibers tended to decrease first and then increase (<0.05). The results indicated that the histological structures of the gill, spleen, and muscle ofjuveniles were affected by the environment and salinity.

Salinity;; Gills; Spleen; Muscle; Histological structure

S917.4

A

2095-9869(2020)01-0112-07

10.19663/j.issn2095-9869.20181101001

* 中国水产科学研究院南海水产研究所中央级公益性科研院所基本科研业务费专项资金(2016TS02)资助 [This work was supported by Central Public-Interest Scientific Institution Basal Research Fund, South China Sea Fisheries Research Institute, CAFS (2016TS02)]. 温久福,E-mail: nhswjf@163.com

区又君,研究员,E-mail: ouyoujun@126.com

2018-11-01,

2018-12-10

http://www.yykxjz.cn/

温久福, 蓝军南, 曹明, 周慧, 区又君, 李加儿. 盐度对花鲈幼鱼鳃、脾及肌肉组织结构的影响. 渔业科学进展, 2020, 41(1): 112–118

Wen JF, Lan JN, Cao M, Zhou H, Ou YJ, Li JE. Effects of salinity on the histological structure of the gills, spleen, and muscle injuveniles. Progress in Fishery Sciences, 2020, 41(1): 112–118

OU Youjun, E-mail: ouyoujun@126.com

(编辑 马璀艳)

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