有机锡污染与海产腹足类性畸变

综述了海产腹足类性畸变发生的原因和形态变化,并对利用海产腹足类性畸变进行有机锡污染的生物监测,海产腹足类性畸变的生态毒理学等方面的研究进展及我国的研究现状作了详细的介绍。     

桶形芋螺和菖蒲芋螺的性畸变

2 0 0 1年 9月和 2 0 0 3年 8月在广东湛江的硇洲岛和 2 0 0 3年 6月在广东阳江的闸坡渔港采集桶形芋螺 (Conus betulinus)和菖蒲芋螺 (Conus vexillum) ,发现两个海区的芋螺雌性个体均发生性畸变 ,性畸变率均为 10 0 % ,但雌 /雄性比仍大于 1.0。两种芋螺的畸变阶段和类型多 ,桶形芋螺有 S3b、S3c、 S4 、S*4 、S5b、S5c,而菖蒲芋螺有 S1 c、S3b、S4 、S*4 、S6 b。 2 0 0 3年 6月在阳江采集的桶形芋螺畸变程度最高 ,种群 RPSI为 5 3.8% ,VDSI高达 4 .9,雌性不育率达 4 4 .0 %。 2 0 0 1年 9月在硇洲岛外海深水区采集的菖蒲芋螺的种群 RPSI虽然只有 14 .7% ,但性畸率为 10 0 % ,VDSI也达 4 .1%。由此可见 ,两种芋螺对有机锡污染均比较敏感 ,而且有个体大、易采集、性畸变率高、畸变阶段跨度大、畸变类型多、畸变特征易于鉴别等特点 ,是中国东南沿海低潮线和潮下带有机锡污染生物监测的理想指示种。如与潮间带有机锡污染指示种疣荔枝螺 (Thaisclavigera)结合起来 ,便可相互补充 ,能更加全面和准确地反映近岸海域有机锡污染的现状     

性畸变对腹足类生殖和种群的影响

具有内分泌干扰效应的三丁基锡能引起腹足类产生性畸变现象。在性畸变过程中 ,雌性个体会由于生殖孔口被前列腺取代或被输精管阻塞、贮精囊或卵囊腺开裂、卵囊腺内部被阻塞以及卵巢转化为精巢等多种原因而丧失生殖能力 ,甚至死亡。并由此引起雌、雄性比和幼、成年个体比的降低 ,导致种群衰退。有浮游幼体的种类可以通过外来种群的成功迁入使种群得以维持 ,而无浮游幼体的种类 ,由于幼体迁移能力差而最终导致种群的区域性灭绝。性畸变这种典型的功能效应对其他内分泌干扰物质的生态效应研究有启示作用。     

厦门海域岩相海岸带疣荔枝螺（Thais clavigera）与甲虫螺（Cantharus cecillei）性畸变

海产腹足类性畸变以其对有机锡的敏感性、特异性和不可逆性而成为海洋有机锡污染的理想指示种.调查研究了厦门海域岩相海岸带疣荔枝螺(Thais clavigera)和甲虫螺(Cantharus cecillei)的性畸变情况,通过生物学指标IOI(性畸变率)、RPSI(相对阴茎发展指数)、VDSI(输精管发展指数)及SRI(性比指数)综合评价其性畸变发展程度,间接指示厦门周边海域的有机锡污染程度.研究结果发现,在采集疣荔枝螺的17个站点中有5个站点种群性畸变率为100%,其中宝珠屿种群性畸变程度最为严重,VDSI达4,采集甲虫螺的4个站点的种群性畸变率均为100%.性畸变程度较严重的种群普遍集中于厦门西港,并且表现出由港内到港外逐渐减轻的趋势,而白城、会展中心和大嶝岛等位于开阔的厦门东海域的种群性畸变程度最轻,与往年厦门西海域有机锡污染监测数据相比一致,体现出性畸变程度与有机锡污染程度及海港码头远近之间的相互关系.     

雌雄及性畸变疣荔枝螺P450芳香化酶差异的研究

有机锡(Organotin)是至少含有一个Sn-C共价键的金属有机化合物,由于其对水生生物具有显著的杀生作用,20世纪70年代就被作为新型防污涂料而广泛用于船坞事业,目前世界已超过60%深海船只均使用含有机锡的防污漆涂料。有机锡的半衰期较长,在天然水体中半衰期可达几个月,当与悬浮颗粒物结合转移到沉积物以后则更加稳定,半衰期高达2至10年以上。显然有机锡已成为人为引入海洋环境中毒性最大的物质之一。       

三种螽斯的性选择行为比较研究

本文通过设计Y形迷宫实验,对螽斯属的优雅蝈螽Gampsocleis gratiosa、暗褐蝈螽Gampsocleis sedakovii obscura和鸣螽属的鼓翅鸣螽Uvarovites inflatus雌虫的性选择行为和交配行为进行了观察研究。结果表明:3种螽斯的交配行为谱一致,但交配时间上有差别;3种螽斯雌虫趋于选择体重较大的雄虫交配;体重和精包重之间呈现较复杂的相关性,但均以三次函数的拟合度(R2)最大;雄虫精包重占体重均在10.0%以上,分别为优雅蝈螽11.1%、暗褐蝈螽12.5%、鼓翅鸣螽14.9%。     

三种毛枝藻的培养研究及其异丝性特征

毛枝藻属Stigeoclonium植物是异丝性藻类, 由直立系统和匍匐系统共同组成; 直立系统的形态高度变化, 虽然匍匐系统的形态比直立系统的形态稳定, 但野外采来的标本匍匐系统不全, 影响鉴定的效果。将采自野外的10号毛枝藻属样的标本通过实验室培养, 观察到它们从孢子萌发至匍匐系统和直立系统发育全过程的细节, 确定其中3种毛枝藻的种名为夏毛枝藻S. aestivale (Haz.) Coll.、偏生毛枝藻S. subsecundum Kütz.和丰满毛枝藻S. farctum Berthold。夏毛枝藻和偏生毛枝藻孢子萌发大致为匍匐式, 夏毛枝藻匍匐系统是分枝的丝状体, 不产生假根, 细胞圆球形或短圆柱形, 内具叶绿体; 偏生毛枝藻的匍匐系统是假二叉分枝的假根, 假根由单列长圆柱形细胞组成, 最后叶绿体消失变为无色; 丰满毛枝藻的孢子萌发是严格的匍匐式, 匍匐系统由主枝和分枝构成假薄壁组织的盘状结构。这3种毛枝藻的匍匐系统都各具其独特而持久的形态特征。它们的直立系统都是分枝的丝状体, 夏毛枝藻和偏生毛枝藻分枝较多, 一侧生或互生, 无对生, 枝顶尖细或为毛状, 前者细胞宽7-9 μm, 长17-30 μm, 长为宽的3-4倍; 后者宽10-14 μm, 长18-36 μm, 长为宽的2-3倍, 细胞外胶质层厚。丰满毛枝藻分枝稀少或不发育, 细胞宽8-10 μm, 长9-32 μm, 长为宽的2-4倍。但此3种毛枝藻直立系统的形态特点是不稳定而可变的, 故毛枝藻的分类应主要参考它们的匍匐系统而定。首次报道了中国产毛枝藻的培养研究。     

海南产桶形芋螺线粒体基因组DNA提取条件的优化

提取海南产桶形芋螺线粒体基因组完整DNA (mtDNA),并对提取条件进行优化。以桶形芋螺腹足肌肉、毒腺和肝胰脏三个不同组织为材料,分别采用改进高盐沉淀法、细胞器/磁珠法和试剂盒提取三种方法,提取桶形芋螺mtDNA,并利用琼脂糖凝胶电泳和紫外分光光度计对提取mtDNA的纯度和浓度进行测定。以coxⅠ-rRNA小亚基基因和α-芋螺毒素基因设计引物,通过PCR反应来确证所提取的DNA确实是mtDNA。试剂盒法提取肝胰脏、高盐沉淀法提取肝胰脏和腹足肌肉组织这三种方法的产率很高,分别为44.4μg/mg、43.3μg/mg和32.6μg/mg。A260/280比值表明,改进高盐沉淀法提取毒腺和腹足肌肉组织,细胞器磁珠法提取腹足肌肉组织的mtDNA纯度很高。综合比较,采用改进高盐沉淀法,利用桶形芋螺腹足肌肉组织所提取的mtDNA产率高、质量好、纯度高。高质量芋螺mtDNA的获取为利用分子生物学方法对芋螺进行遗传进化分析和系统分类提供了基础。     

New insights into the mechanism of imposex induction in the dogwhelk Nucella lapillus

In an attempt to clarify the mechanism(s) of tributyltin-mediated imposex induction in females of the neogastropod Nucella lapillus, dogwhelks collected in an almost imposex free population were exposed to several treatments for a 3 month-period, and the effects on imposex induction and testosterone/estradiol levels were evaluated. As a positive control, tributyltin (50 ng TBT Sn/L) clearly induced imposex and led to a significant increase in the severity of the phenomenon. In contrast, although a selective P450 aromatase inhibitor (formestane at 0.3 mg/L) was capable of imposex induction, it failed to increase its severity. A vertebrate androgen receptor (AR) antagonist (cyproterone acetate at 1.25 mg/L) in combination with TBT completely blocked the imposex induction capacity of TBT. On the other hand, an estrogen receptor antagonist (tamoxifen at 0.3 mg/L) rendered no effect. The determination of steroid levels in female specimens revealed that TBT induces an elevation of free testosterone (but not the total amount, free+esterified), while the co-administration of the anti-androgen and TBT was able to rescue the increase of free testosterone levels. Despite a minor decrease in the amount of testosterone-fatty acid esters in the TBT group, significant differences in esterified testosterone were not found among treatments. On the contrary, free estradiol levels were elevated in the TBT, anti-androgens and TBT plus anti-androgens groups. These results indicate that free estradiol biosynthesis in TBT-exposed females does not seem to be affected. Overall, our results demonstrate that a selective aromatase inhibitor can induce imposex in N. lapillus but not to a similar extent of TBT, which may suggest the involvement of other mechanism in imposex induction, besides aromatase inhibition. Additionally, the study points to the involvement of AR receptors in imposex induction.     

Histological and enzymatic studies on the renal tubules of some marine elasmobranchs

Renal tubules in the dog shark, leopard shark, and red skate were examined histologically and analyzed histochemically for enzymes. Cells of the distal and collecting tubules exhibit extensive interdigitations and large intercellular spaces, suggesting that these tubules are sites of sodium reabsorption. Although Na-K-ATPase is very scarce to nonexistent in the distal and collecting tubules, very intense carbonic anhydrase activity in these segments indicates that they secrete large amounts of hyrogen ion and reabsorb sodium by H⁺/Na⁺ exchange process. Epithelial cells of the necks are not interdigitated, tightly join adjacent cells, and have low enzyme activities. They seem to be passively permeable to the water. Necks are attached to the distal tubules with scant intervening stroma. It seems likely that the stroma has a high osmotic pressure resulting from absorption of solutes in the distal tubules. Water may be reabsorbed from necks to stroma because of a concentration gradient of the solutes distributed between these sites.     

Comparison of imposex response in three Prosobranch species

A comparative study of the three gastropod species Nucella lapillus (L.), Ocenebra erinacea (L.) and Hinia (Nassarius) reticulata (L.) reveals that Nucella is the most TBT sensitive species while Hinia is the least sensitive. Of the two imposex indices VDSI and RPSI, good interspecies correlations were obtained only for VDSI. The three species can be considered as complementary not only in terms of their ecology but also for their levels of sensitivity. Indeed, Nucella and Ocenebra are useful test species at TBT concentrations below 2 ng Sn 1⁻¹ while Hinia is the more appropriate species at higher TBT levels. For the first time, two sterilised Hinia females are recorded. This sterilization does not seem to be due to proliferation of vas deferens tissue in the vaginal opening and further investigation is needed to find intermediary VDS stages between stage 4⁺ and sterilization. Studies using Nucella show that the use of narcotization in imposex analysis leads to an underestimation of RPSI compared with non-narcotization methods. Indeed, narcotization straightens the penis and increases its length when compared with non-narcotized animals, but this increase is proportionally higher in males than in females.     

3种海藻凝集素组分及糖抑制作用的初步研究

从 3种海藻 (铁钉菜IshigeokamuraeYenda、坛紫菜PorphyrahaitanensisChangetZheng和脆江蓠Gracilariabursa pastorisSilva)中分离纯化得到铁钉菜凝集素 (IOL)、坛紫菜凝集素 (PHL)及脆江蓠凝集素 (GBL)。经测定 ,它们分别含有 7%、14 %和 11%的中性糖。氨基酸组成中 ,苯丙氨酸含量最高 ,蛋氨酸和精氨酸次之。 3种海藻凝集素的凝血活性均可被单糖或双糖所抑制 ,在所测试的 13种糖类中 ,能够抑制GBL活性的糖类最多 ,达 5种 ,抑制IOL的糖类最少 ,仅 2种。 3种糖蛋白 (胃粘蛋白、卵粘蛋白和甲状腺球蛋白 )对IOL没有抑制作用 ,而卵粘蛋白能够抑制PHL和GBL的凝血活性     

Origins of diverse feeding ecologies within Conus, a genus of venomous marine gastropods

Specialized predators on polychaetes, fishes, hemichordates or other molluscs, members of the predominantly tropical gastropod genus Conus diversified rapidly during the Miocene to constitute the most species-rich modern marine genus. We used DNA sequence data from mitochondrial and nuclear loci of 76 Conus species to generate species-level phylogenetic hypotheses for this genus and then mapped known diets onto the phylogenies to elucidate the origins and evolutionary histories of different feeding specializations. The results indicate that dramatically new feeding modes arose only a few times, that the most derived feeding modes likely arose in the Miocene, and that much of the known diversity of Conus that was generated during Miocene radiations has survived to the present.     

海洋碳循环研究进展

海洋碳循环是全球碳循环的重要组成部分,是影响全球变化的关键控制环节。海洋作为一个巨大的碳库,具有吸收和贮存大气CO2的能力,影响着大气CO2的收支平衡,研究碳在海洋中的转移和归宿,对于预测未来大气中CO2含量乃至全球气候变化具有重要意义。综述了海洋CO2通量,海水中碳的迁移和海洋沉积物及河口通量的研究状况,介绍了生物泵作用,碳循环模型的发展以及分析方法的最新发展等,并展望了海洋碳循环研究的未来发展趋势。     

Histological studies on the development of porcine tonsils after birth

Tonsils form the topographically first immune barrier of an organism against the invasion of pathogens. We used histology to study the development of tonsils of pigs after birth. At birth, the tonsils consist of diffuse lymphoid tissue without any lymphoid follicle aggregations. At the age of 7 days, lymphoid follicles appeared in the soft palate tonsil. The lymphoid layer of the nasopharyngeal tonsil, soft palate tonsil, and lingual tonsil became thicker, and lymphoid follicles in the lamina propria were clearly visible at the age of 21 days. Secondary lymphoid follicles were present in the nasopharyngeal tonsil at the age of 50 days, and in the soft palate tonsil at the age of 120 days. Dendritic cells (DCs), CD3⁺ T cells and IgA⁺ B cells in the soft palate tonsil, nasopharyngeal tonsil and lingual tonsil increased continuously, especially during the first 21 days. The results suggested that tonsils have an important role in local immune defense against invading antigens after birth and will be beneficial for understanding the mechanisms of immunity in these animals after nasal and oral vaccination.     

Comparative ultrastructural studies of the zona radiata of marine fish eggs in three genera in Perciformes

The eggs of Mugil cephalus were significantly larger than those of Epinephelus malabaricus , and E. coioides , while those of Sciaenops ocellatus were intermediate between E. coioides and M. cephalus . The distribution density of pores in the egg envelope of S. ocellatus was significantly different from that of E. malabaricus and E. coioides . The micropyle diameters were significantly different in the four species. The ultrastructure of the zona radiata surface, the distribution density of pores and the size of eggs were also useful characters for distinguishing among the four species, but the ultrastructural features of the micropyles were the most important of all for egg identification.