小型腹足类齿舌的扫描电镜观察

介绍了应用扫描电镜观察小型腹足类齿舌的方法。描述了折叠萝卜螺和大脐圆扁螺齿舌带上齿片的排列方式。结果显示,两种螺齿舌的齿片排成许多横列,每一横列又包含多个齿片。齿片上缘或侧缘尖齿的数目和形态有差异。     

小型腹足类齿舌的扫描电镜观察

介绍了应用扫描电镜观察小型腹足类齿舌的方法。描述了折叠萝卜螺和大脐圆扁螺齿舌带上齿片的排列方式,结果显示,两种螺齿舌的齿片排成许多模列,每一横列又包含多个齿片,齿片上缘或侧缘尖齿的数目和形态有差异。     

嫁[虫戚]的齿舌带及其齿片的形态差异分析

在光镜和电镜下对嫁[虫戚]（Cellana toreuma）的齿舌形态进行观察研究。嫁[虫戚]的齿舌带每1横列具有2枚侧齿和2枚缘齿,缺乏中央齿,齿式为1.1.0.1.1。齿舌带前端弯曲,齿片排列松散且存在明显的磨损现象;中段齿片排列紧密、整齐;后端齿片无色且宽度有略微的缩小。侧齿呈镰刀型,具1个齿尖,基部呈三角形且具突起,尖齿部分细长;缘齿具3个齿尖,第2尖齿靠近第3尖齿。采用多个比例参数来比较嫁齿舌带及其前、中、后3段上的齿片形态,发现嫁齿舌带前、中、后3段各比例参数的值存在一定的关系,即中段大于前段、中段大于后段。     

嫁(虫戚)属2种的齿舌形态差异分析

在光镜和电镜下对嫁(虫戚)(Cellana toreuma)和斗嫁(虫戚)(C.grata)的齿舌形态进行观察比较。2种嫁(虫戚)的齿式都为1.1.0.1.1,即具有1枚侧齿和1枚缘齿,缺乏中央齿。齿舌前端都有1小段弯曲,齿片排列松散且存在明显的磨损现象。嫁(虫戚)和斗嫁(虫戚)的侧齿形状很相似,侧齿呈镰刀型且具1个齿尖,基部近似三角形且具突起,尖齿部分细长。两种嫁(虫戚)的缘齿存在一定的差异,嫁(虫戚)缘齿具3个齿尖,第2尖齿靠近第3尖齿。斗嫁(虫戚)缘齿具2个齿尖且比较细长,第2尖齿靠近缘齿基部。本文用17个参数对这两种嫁(虫戚)的齿舌带及其前中后3段上的齿片进行了测量比较,发现斗嫁(虫戚)齿舌带的长宽比明显大于嫁(虫戚)齿舌带的长宽比,即斗嫁(虫戚)的齿舌带显得更加细长。齿舌带前、中、后3段各比例参数的值存在一定的关系,即中段大于前段、中段大于后段。据此认为用齿舌作为2种嫁(虫戚)的分类依据是可行的。     

应用扫描电镜观察螺类齿舌

齿舌(Radula)是软体动物特有的一种消化器官,除了瓣鳃纲、腹足纲及头足纲的个别种类没有齿舌以外,其他种类都有。齿舌带上的齿舌形状,数目和排列方式在各科,属或种中都有一定的规律,齿舌带上布满了规则的舌齿,以一定方式排列成一条带状,每一横列的中央为一枚中央齿左右相对称有一对或数十对侧齿依次     

两种福寿螺与中国圆田螺齿舌的形态学特征比较

齿舌作为软体动物独特的摄食器官,是软体动物门重要的分类特征。利用扫描电镜对入侵物种福寿螺Pomacea canaliculata、P.maculata和本地物种中国圆田螺(Cipangopaludina chinensis)的齿舌形态进行了比较观察。两种福寿螺和中国圆田螺齿式均为2·1·1·1·2。两种福寿螺齿舌的差异主要体现在中央齿的第一突起,P.canaliculata中央齿第一突起宽而短,不如P.maculata锋利。P.canaliculata与P.maculata第一突起长与中央齿宽以及第一突起宽与中央齿宽的比值均具有显著差异。两种福寿螺与中国圆田螺齿舌的中央齿、侧齿、缘齿,不论是从形态还是数量上都明显不同。两种福寿螺中央齿第一突起大而尖,呈倒三角形,两侧对称排列3个小齿;中国圆田螺的中央齿第一突起短而宽,呈方形,两侧对称排列4个小齿。两种福寿螺的侧齿大突起内侧有1个小而尖的小齿,大突起外侧另有2个小齿;中国圆田螺侧齿上缘中间大突起外侧有3个小齿,呈锯齿状。两种福寿螺的内缘齿和外缘齿相似,缘齿上缘的中间尖齿尖锐,旁边再形成一小齿;中国圆田螺内缘齿上缘的中间尖齿突出,外缘齿基部细长,上缘有小的尖齿8~10个,呈梳状。两种福寿螺与中国圆田螺的第一突起宽与中央齿宽之比、第一突起长与中央齿宽之比、第二突起宽与中央齿宽之比、第二突起长与中央齿宽之比均差异显著。食性不同可能是造成种间齿舌结构差异的原因之一。     

我国华东沿海4种石磺形态学比较

我国华东沿海分布有瘤背石磺(Onchidium struma)、平疣桑椹石磺(Platevindex mortoni)、里氏拟石磺(Paraoncidium reevesii)、紫色疣石磺(Peronia verruculata)4属4种石磺,后3种为我国大陆沿海新纪录种。通过野外实地调查和实验室暂养分别观察了其生态习性及外部形态,测定外形主要生物学性状指标进行统计分析;同时解剖比较4种石磺的生殖系统和消化系统等内部结构。结果显示,4种石磺的生活区域分别从潮间带中潮区至高潮区再到潮上带而呈现梯度分布状态,生活区域的不同导致生活习性、呼吸方式的不同;4种石磺外部形态差别明显,身体背部和腹足的颜色不同,平疣桑椹石磺没有背眼,腹足灰黑色或灰白色,惟紫色疣石磺有树枝状鳃;在内部结构中,平疣桑椹石磺无阴茎附属腺,里氏拟石磺无阴茎牵引肌且与紫色疣石磺一样不具有肛门腺。主要生物学性状数据分析得出足长和足宽是典型代表数据,判别分析得出呼吸孔至身体末端距离与肛门至呼吸孔距离的比例是属种间具有显著性意义的观察指标,从外形及内部主要结构比较发现将它们分属4个种是准确的。外部形态的特殊结构以及内部结构主要差异可作为石磺科分类的主要依据;比较我国华东沿海石磺的形态学差异能为石磺科贝类模式种资料的重新修订提供良好的研究基础。     

瘤背石磺和里氏拟石磺背部皮肤蛋白质组差异分析

从蛋白质水平探讨瘤背石磺和里氏拟石磺背部皮肤蛋白质组差异表达,为完善石磺科贝类从海洋到陆地进化的研究以及解释两种石磺不同的环境适应性提供蛋白质依据。应用Label-free非标定量蛋白质组学技术,结合软件Sequest HT和Proteome Discoverer (Thermo),对瘤背石磺和里氏拟石磺的背部皮肤进行蛋白质组搜库鉴定及定量分析,其中瘤背石磺中鉴定到1 491个蛋白质,里氏拟石磺中鉴定到1 030个蛋白质;用Pfind软件对表达图谱进行同源序列的鉴定及定量分析,检测到928个同源蛋白表达量有差异,瘤背石磺较里氏拟石磺上调表达406个(p0.05, FC1.5),下调表达339个(p0.05, FC0.5)。适应水下生活的里氏拟石磺背部皮肤角质化程度较低,差异同源蛋白序列分析显示与角质形成、细胞凋亡相关蛋白在里氏拟石磺背部皮肤中高表达,与皮肤保湿性能相关的神经酰胺类物质在瘤背石磺中高表达;KEGG分析显示,嘌呤代谢通路中存在的差异蛋白最多,共73个,其中瘤背石磺较里氏拟石磺上调表达22个,下调表达21个。蛋白组差异分析显示关键酶尿素酶在陆栖性较强的瘤背石磺中高表达,与前人所做动物从水生到陆生进化过程中尿素酶基因完全丢失的研究结论有所出入,属于特殊物种。里氏拟石磺的皮肤辅助呼吸能力和血窦数目均高于瘤背石磺,且背部皮肤中肌纤维更加粗壮,此生理现象在蛋白质组上的表现为两种石磺能量代谢及氧离子运输相关蛋白的差别较大;瘤背石磺背部皮肤中对环境污染反应灵敏的谷胱甘肽S转移酶和谷胱甘肽过氧化物酶的表达量高于里氏拟石磺,推测其与瘤背石磺较强的皮肤免疫能力和环境适应性相关。蛋白表达谱中928个差异表达同源序列为两种石磺表现差异和环境适应的分子机制研究提供了有意义的蛋白质组的基础数据。     

六种石磺科贝类超氧化物歧化酶和酯酶同工酶分析

采用聚丙烯酰胺垂直板凝胶电泳分离技术对中国东南沿海的石磺科6种石磺的腹足、肝胰脏两种组织的超氧化物歧化酶和酯酶同工酶进行分析.明确了其酶谱的特征及分布,并利用聚类分析方法对种间的亲缘关系进行了研究.同工酶聚类分析显示,紫色疣石磺(Peronia verruculata)和小紫疣石磺(Peronia sp.)的亲缘关系最近;里氏拟石磺(Paraoncidium reevesii)和白底拟石磺(Paraoncidium sp.)聚为一类;平疣桑椹石磺(Platevindex mortoni)和瘤背石磺(Onchidium struma)聚为一类.种间的个体酶谱表型有差异,同属的种间差异小于不同属的种间差异.酶谱的差异程度与形态分类学中的亲缘关系相近.利用超氧化物歧化酶同工酶和酯酶同工酶酶谱表型也可以作为一种蛋白分子标记应用于石磺科属种的分类鉴定.     

瘤背石磺低频听力基因PMCA2的克隆、相对表达及神经组织原位杂交分析

低频听力基因PMCA2在生物听力方面占据着重要位置,基因突变或缺失后会引发神经性耳聋和平衡功能障碍.为探究基因PMCA2在瘤背石磺潮汐感知中的作用,本研究通过RACE技术克隆得到瘤背石磺PMCA2基因的全长cDNA,并进行系统进化分析.利用实时荧光定量PCR(RT-qPCR)技术和原位杂交技术分析两组(暂养无处理组和潮汐干扰刺激组)瘤背石磺PMCA2基因在各组织中相对表达量和在神经组织各神经节中的相对表达部位.实验结果表明,瘤背石磺PMCA2基因cDNA全长5 091 bp,包含492 bp的5'非编码区(UTR)以及972 bp的3'UTR,3 627bp的开放阅读框,共编码1 208个氨基酸,基因序列较为保守.序列分析结果显示,瘤背石磺与加州海兔、绿色海蜗牛和福寿螺PMCA2氨基酸序列同源性分别为81.79％,78.25％和72.91％.通过系统进化树分析研究得出,瘤背石磺与加州海兔进化关系相对较近.RT-qPCR结果显示,两组石磺神经组织PMCA2基因表达量皆高于其他组织的,且潮汐干扰刺激组神经组织表达量明显高于暂养无处理组,有显著性差异.两组瘤背石磺神经组织原位杂交实验结果显示,相较于暂养无处理组,潮汐干扰刺激组石磺神经组织杂交信号明显增强,该结果与荧光定量PCR结果相符.实验初步表述了瘤背石磺PMCA2基因的生物信息学特征,在瘤背石磺各组织中的表达情况及在神经组织中的分布部位,为研究滩涂生物感知潮汐能力提供原创性成果.     

Main patterns of radula formation and ontogeny in Gastropoda

Gastropoda is morphologically highly variable and broadly distributed group of mollusks. Due to the high morphological and functional diversity of the feeding apparatus gastropods follow a broad range of feeding strategies: from detritivory to highly specialized predation. The feeding apparatus includes the buccal armaments: jaw(s) and radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. A unique characteristic of the radula is its continuous renewal during the entire life of a mollusk. The teeth and the membrane are continuously synthesized in the blind end of the radular sac and are shifted forward to the working zone, while the teeth harden and are mineralized on the way. Despite the similarity of the general mechanism of the radula formation in gastropods, some phylogenetically determined features can be identified in different phylogenetic lineages. These mainly concern shape, size, and number of the odontoblasts forming a single tooth. The radular morphology depends on the shape of the formation zone and the morphology of the subradular epithelium. The radula first appears at the pre- and posttorsional veliger stages as an invagination of the buccal epithelium of the larval anterior gut. The larval radular sac is lined with uniform undifferentiated cells. Each major phylogenetic lineage is characterized by a specific larval radula type. Thus, the docoglossan radula of Patellogastropoda is characterized by initially three and then five teeth in a transverse row. The larval rhipidoglossan radula has seven teeth in a row with differentiation into central, lateral, and marginal teeth and later is transformed into the adult radula morphology by the addition of lateral and especially marginal teeth. The taenioglossan radula of Caenogastropoda is nearly immediately formed in adult configuration with seven teeth in a row.     

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda,Gastropoda)

The radular morphology of the patellid species Testudinalia testudinalis (O. F. Müller, 1776) from the White Sea was studied using light, electron, and confocal microscopy. The radula is of the docoglossan type with four teeth per row and consisting of six zones. We characterize teeth formation in T. testidinalis as follows: one tooth is formed by numerous and extremely narrow odontoblasts through apocrine secretion; this initially formed tooth consists of numerous vesicles; the synthetic apparatus of the odontoblasts is localized in the apical and central parts of the cells throughout the cytoplasm and is penetrated by microtubules which are involved in the transport of the synthesized products to the apical part of the odontoblast; the newly formed teeth consist of unpolymerized chitin. Mitotic activity is located in the lateral parts of the formation zone. The first four rows contain an irregular arrangement of teeth, but the radular teeth are regularly arranged after the fifth row. The irregularly arranged teeth early on could be a consequence of the asynchronous formation of teeth and the distance between the odontoblasts and the membranoblasts. The morphological data obtained significantly expands our knowledge of the morphological diversity of the radula formation in Gastropoda.     

Radula formation in two species of Conoidea (Gastropoda)

The radula is the basic feeding structure in gastropod molluscs and exhibits great morphological diversity that reflects the exceptional anatomical and ecological diversity occurring in these animals. This uniquely molluscan structure is formed in the blind end of the radular sac by specialized cells (membranoblasts and odontoblasts). Secretion type, and the number and shape of the odontoblasts that form each tooth characterize the mode of radula formation. These characteristics vary in different groups of gastropods. Elucidation of this diversity is key to identifying the main patterns of radula formation in Gastropoda. Of particular interest would be a phylogenetically closely related group that is characterized by high variability of the radula. One such group is the large monophyletic superfamily Conoidea, the radula of which is highly variable and may consist of the radular membrane with five teeth per row, or the radular membrane with only two or three teeth per row, or even just two harpoon-like teeth per row without a radular membrane. We studied the radulae of two species of Conoidea (Clavus maestratii Kilburn, Fedosov & Kantor, 2014 [Drilliidae] and, Lophiotoma acuta (Perry, 1811) [Turridae]) using light and electron microscopy. Based on these data and previous studies, we identify the general patterns of the radula formation for all Conoidea: the dorsolateral position of two groups of odontoblasts, uniform size, and shape of odontoblasts, folding of the radula in the radular sac regardless of the radula configuration. The morphology of the subradular epithelium is most likely adaptive to the radula type.     

The relation between excitation-contraction coupling and fine structure of a molluscan muscle,the radular retractor of the whelk,Buccinum undatum

The Buccinum radula is of the rachiglossate type with two outer rows of fierce hook-like attack teeth and a medial row of straight sharp-pointed shredding teeth. Individual cells of the radular retractor muscle are 10–12 m in diameter and separated at the closest by gaps of only 40 nm, providing areas of potential electrical contact. The cell membranes are heavily invested with long finger-like invaginations, associated with sarcoplasmic reticular cisternae, and surface caveolae; the latter are associated with the numerous dense body membrane attachment plaques found in this muscle. The radular retractor muscle possesses a significant sarcoplasmic reticulum of peripheral cisternae and deeper vesicles associated with mitochondria. The surface caveolae may result from myofilament force exerted via attachment plaques at the cell membrane, while deeper invaginations may constitute a rudimentary transverse tubular system to relay surface depolarization to associated sarcoplasmic reticular cisternae inducing calcium release to effect excitation-contraction coupling. The radular retractor muscle possesses the usual thick paramyosin and thin actin myofilaments, the latter associated with dense bodies and attachment plaques presumably to transduce force to the cell membrane. The mitochondria are unusually large and packed into dense central clusters surrounded by large deposits of glycogen granules. The nerve endings on the radular retractor muscle fibres show four different types of transmitter vesicle, presumably related to the four kinds of agonist action in this muscle, cholinergic, serotonergic, peptidergic and purinergic. All nerve endings have mixed vesicle populations, clear evidence of co-transmission. In this muscle we see a modification of usual smooth muscle structure to effect fast sustained contractions, an ultrastructural configuration functionally designed for the muscle's central role in the feeding cycle.Abbreviations ABRM anterior byssus retractor muscle - EC coupling excitation-contraction coupling - RP radular protractor muscle - RR radular retractor muscle - SR sarcoplasmic reticulum - T-system transverse tubular system     

RADULAR PRODUCTION RATES IN TWO SPECIES OF LACUNA TURTON (GASTROPODA: LITTORINIDAE)

The molluscan radula is a dynamic organ, both in terms of itsuse and production. New rows of teeth are constantly producedat the posterior end of the radula, while older, worn teethare shed anteriorly, producing a dynamic equilibrium. We useda cold-shock to mark the radular ribbon and measure tooth rowproduction rates in two gastropod species, Lacuna vincta (Montagu)and L. vanegata Carpenter. We found that the average tooth rowproduction rate at 10–11°C did not differ betweenthese two species, and was 2.94 (SE = 0.002) rows per day forLacuna vincta and 2.97 (SE = 0 002) for L. vanegata Inter-individualvariability in production rate was very low, and was correlatedwith shell length, smaller individuals had slightly higher productionrates. The total length of the radular nbbon varied greatlyamong individuals, ranging from 47 to 94 (2.57 to 5.68 mm) rowsin L vincta and 53 to 99 rows (2.80 to 7.14 mm) in L vanegata,and was only somewhat correlated with the length of the shelLThis great variability will result in large differences amongindividuals in the time it takes to replace the radula totally,from 14.96 to 35.44 days in L vincta and from 17 43 to 39 69days in L. vanegata. (Received 1 September 1995; accepted 20 November 1995)     

红条毛肤石鳖齿舌主侧齿中铁还原酶分布及与生物矿化的关系

以红条毛肤石鳖Acanthochiton rubrolineatus(Lischke)齿舌为材料,通过切片和酶组织化学技术,在光镜和电镜下对齿舌主侧齿的微结构及高铁还原酶的存在进行观察,从微观角度了解齿舌主侧齿齿尖的矿化机理。结果显示,成熟主侧齿由齿尖和齿基组成。齿尖结构由外至内分为三层,最外层为磁铁矿层,前后齿面磁铁矿层的厚度不等,后齿面约50μm,前齿面约5-10μm。向内依次为棕红色的纤铁矿层,厚约10μm,及略显黄色的有机基质层,有机基质层占据着齿尖内部的大部分结构。高分辨透射电镜下显示磁铁矿由条状四氧化三铁颗粒组成,长约2-3μm,宽约100-150nm。齿舌的矿化是一个连续过程,不同部段处于不同的矿化阶段,齿舌囊上皮细胞沿囊腔分布,并形成齿片。未矿化的新生主侧齿齿尖中存在由有机基质构成的网状结构。随矿化的进行,有机基质内出现矿物颗粒。初始矿化的齿尖外表面有一个细胞微突层,微突的另一端为囊上皮细胞,矿物质经由微突层达齿尖并沉积于有机基质中,齿尖随之矿化并成熟。初始矿化齿尖的外围有大量的三价铁化物颗粒,稍成熟的齿尖外围同时还出现二价铁化物。新生或初始矿化主侧齿齿尖外围的囊上皮细胞中有大量球形类似于铁蛋白聚集体的内容物,直径0.6-0.8μm,球体由膜包围。齿舌囊上皮组织中存在三价高铁还原酶,此酶分布于上皮细胞的膜表面,可能与齿尖表面磁铁矿的生成有一定的关系。       

Original molluscan radula: comparisons among Aplacophora,Polyplacophora, Gastropoda,and the Cambrian fossil Wiwaxia corrugata

As the original molluscan radula is not known from direct observation, we consider what the form of the original radula may have been from evidence provided by neomenioid Aplacophora (Solenogastres), Gastropoda, Polyplacophora, and the Cambrian fossil Wiwaxia corrugata (Matthews). Conclusions are based on direct observation of radula morphology and its accessory structures (salivary gland ducts, radular sac, anteroventral radular pocket) in 25 species and 16 genera of Aplacophora; radula morphogenesis in Aplacophora; earliest tooth formation in Gastropoda (14 species among Prosobranchia, Opisthobranchia, and Pulmonata); earliest tooth formation in four species of Polyplacophora; and the morphology of the feeding apparatus in W. corrugata. The existence of a true radula membrane and of membranoblasts and odontoblasts in neomenioids indicates that morphogenesis of the aplacophoran radula is homologous to that in other radulate Mollusca. We conclude from p redness of salivary gland ducts, a divided radular sac, and a pair of anteroventral pockets that the plesiomorphic state in neomenioids is bipartite, formed of denticulate bars that are distichous (two teeth per row) on a partially divided or fused radula membrane with the largest denticles lateral, as occurs in the genus Helicoradomenia. The tooth morphology in Helicoradomenia is similar to the feeding apparatus in W. corrugata. We show that distichy also occurs during early development in several species of gastropods and polyplacophorans. Through the rejection of the null hypothesis that the earliest radula was unipartite and had no radula membrane, we conclude that the original molluscan radula was similar to the radula found in Helicoradomena species.