疣荔枝螺(Thais clavigera)性畸变现象的解剖学和组织学研究

以解剖学和组织学的方法研究了有机锡污染生物指示种——疣荔枝螺的正常雄、雌和性畸变个体的生殖系统。结果表明，性畸变个体除具有正常的雌性器官外，还有输精管或阴茎。当性畸变程度严重时，性畸变不育个体的卵囊腺组织出现破损，并具有不规则块状的不育卵囊和未排出的正常卵囊。虽然性畸变个体的雄性器官具有表现出雄性功能的潜能，但由于缺少精巢或完整的前列腺，不可能发展成为具有雄性功能的个体，这与性逆转有着本质上的区别。有机锡污染引起的性畸变已对疣荔枝螺种群生存构成了潜在的威胁，深化此类负面生态效应的研究是人类面临的重要课题。     

Dumpton syndrome reduces the tributyltin (TBT) sterilising effect on Nucella lapillus (L.) by limiting the development of the imposed vas deferens

TBT induces imposex and sterilisation in female Nucella lapillus. Interestingly, there are populations where individuals (both males and imposexed females) may suffer from a genetic aberration [Dumpton Syndrome (DS)] which results in the development of no penis (i.e. aphally). This anomaly confers a so far unexplained protection against TBT. Six populations with contrasting DS frequency were sampled; the imposex stage in females and the mean calibre of every vas deferens (VDC) were assessed. While the sex ratio in the 600 specimens examined was close to 1, aphally was more frequent in females than in males (31 and 7%, respectively). VDC was significantly higher in normal than in aphallic (DS) specimens, independently of sex and/or site. It is concluded that the vas deferens imposed by TBT onto DS females is less prone to develop thick enough so as to interfere with normal egg laying.     

Cytochrome P450 differences in normal and imposex-affected female whelk Buccinum undatum from the open North Sea

Normal and imposex-affected female Buccinum undatum were sampled from the open North Sea at three locations, one with low, and two with high shipping densities. Cytochrome P450 components and P450 aromatase activity were determined in the microsomal fractions isolated from pooled digestive gland/gonads. Cytochrome P450 aromatase activity was significantly higher (P < 0.05) in normal females collected in the low shipping density area (1,325 +/- 295 fmol/h/mg protein) than levels from imposex animals from a high shipping density area (620 +/- 287 fmol/h/mg protein). A negative correlation was found between aromatase activity and organotin body burden (r = -0.99). Levels of CYP450, cytochrome b5 and NADPH cytochrome c reductase activity did not show differences among groups. This is the first field evidence of depressed aromatase activity in imposex affected females, although additional research under laboratory controlled conditions is required to fully understand the mechanisms underlying the development of imposex in this species.     

方斑东风螺性畸变现象的解剖学和组织学研究

以解剖学和组织学方法研究了方斑东风螺未成熟和成熟的正常雌、雄个体以及性畸变个体的生殖系统结构.性畸变个体除具有正常的雌性器官外,还有输精管或阴茎.在正常雄性输精管的个体发育过程中再现了系统发育的过程,而且在性畸变个体输精管的形成过程和发育过程中组织学结构特征的变化与正常雄性输精管的个体发育过程的相似.性畸变雌体的性腺发育受阻.目前,性畸变现象仅存在于成熟个体,但这并不表明未成熟个体中不会发生性畸变现象.具有较高食用价值的方斑东风螺因有机锡污染可能会对人类健康不利,应引起人们的关注.     

The Mollusc Thais haemastoma -An Exhibitor of 'Imposex' and Potential Biological Indicator of Tributyltin Pollution

Abstract. In the Azores the gastropod Thais haemastoma shows varying degrees of imposex, the induction of male sex characters in the female. It is inferred that imposex in T. haemastoma is caused by tributyltin (TBT) associated with boats using organotin-based antifouling paints. The two indices - relative penis size and vas deferens sequence - employed previously for Nucella lapillus , were used without alteration. T. haemastoma is only the third species reported as exhibiting 'effective sterilisation' of the female. Unlike Nucella lapillus, T. haemastoma has a planktonic larva, allowing populations to be sustained even when local TBT pollution is high. This makes T. haemastoma potentially a better indicator species, as monitored populations can be maintained by the influx of larvae. T. haemastoma may thus provide a cheap method of assessing the extent of TBT contamination in warm waters, particularly in the Mediterranean and Atlantic Islands. Preliminary examination of material from a marina in Spain showed a high incidence of 'sterile' animals.     

Increasing imposex in populations of Bolinus brandaris (Gastropoda: Muricidae) in the northwestern Mediterranean.

The muricid gastropod Bolinus brandaris exhibited imposex, a phenomenon linked to the use of organotin biocides. Several stages of imposex development (1-5) could be distinguished and were documented with SEM-photographs for the first time in this species. Additional alterations of the genital tract in females (blocked vulva preventing copulation and deposition of egg capsules) and males (excrecences on the penis and vas deferens) were shown. Imposex intensity on the Catalan coast was very high. The frequency of imposex off Barcelona and Vilanova i la Geltrú was 100%, with all females showing stage 4. Imposex frequency off Sant Carles de la Ràpita was 99.7% and the VDS index scored 3.9. Despite regulations of TBT-containing antifouling paints in Spain since 1990, the present study revealed that frequency and intensity of imposex have increased on the Catalan coast, at least since 1997. However, at present, imposex does not apparently affect the population dynamics of B. brandaris in the studied area, since no serious consequences on female reproduction (only one case of female sterilization) were detected. Gonadal activity and oogenesis were not suppressed or supplanted by spermatogenesis. Sex ratios were not male-biased. Possible sources of organotin biocides are examined.     

Increasing imposex in populations of Bolinus brandaris (Gastropoda: Muricidae) in the north-western Mediterranean

The muricid gastropod Bolinus brandaris exhibited imposex, a phenomenon linked to the use of organotin biocides. Several stages of imposex development (1–5) could be distinguished and were documented with SEM-photographs for the first time in this species. Additional alterations of the genital tract in females (blocked vulva preventing copulation and deposition of egg capsules) and males (excrecences on the penis and vas deferens) were shown. Imposex intensity on the Catalan coast was very high. The frequency of imposex off Barcelona and Vilanova i la Geltrú was 100%, with all females showing stage 4. Imposex frequency off Sant Carles de la Ràpita was 99.7% and the VDS index scored 3.9. Despite regulations of TBT-containing antifouling paints in Spain since 1990, the present study revealed that frequency and intensity of imposex have increased on the Catalan coast, at least since 1997. However, at present, imposex does not apparently affect the population dynamics of B. brandaris in the studied area, since no serious consequences on female reproduction (only one case of female sterilization) were detected. Gonadal activity and oogenesis were not suppressed or supplanted by spermatogenesis. Sex ratios were not male-biased. Possible sources of organotin biocides are examined.     

Imposex and surface sediment speciation: a combined approach to evaluate organotin contamination in Guanabara Bay, Rio de Janeiro, Brazil

An integrated biological-chemical survey of organotin compounds was carried out in Guanabara Bay, the second most important Brazilian harbor complex. The biological survey revealed high levels of imposex in Stramonita haemastoma populations. Inside the bay values of relative penis length index from 42.7 to 107.6 and vas deferens sequence index from III to VI were found, while organisms collected outside the bay had values ranging from <0.1 to 35.2 and from 0 to II. None of the females sampled inside the bay were normal and imposex was found in all stations. Surface sediments in the bay are contaminated by tributyltin (10-522 ng/g d.w.) and triphenyltin (<3.9-39.4 ng/g d.w.) with greater concentrations close to shipyards and marinas. The observed predominance of parent compounds (TBT and TPT) is commonly found when recent inputs occur, but may also indicate slow degradation processes in the anoxic conditions of these sediments. To our knowledge, this is the first report of a combined imposex-sediment approach to evaluate organotin contamination in marine environments of South America, and also the first report of TPT detection in environmental matrices in this region.     

The impact of tributyltin from large vessels on dogwhelk (Nucella lapillus) populations around Scottish oil ports

Surveys of imposex in dogwhelk (Nucella lapillus) populations around oil terminals in Sullom Voe (Shetland) and Scapa Flow (Orkney) have confirmed that the effects of tributyltin (TBT) released from large vessels in coastal waters can be recognised. The impact of large vessels can be separated from the effects of other inputs of TBT in the areas studied. The intensity of the effects was greater in Shetland than in Orkney, reflecting the higher exposure to TBT resulting from the greater volume of traffic using the Shetland terminal, and the more restricted water exchange in that area. A large proportion of the female dogwhelks in Sullom Voe were unable to reproduce. Females in Scapa Flow were still able to reproduce, except for a small proportion close to two fish farm sites where TBT net-treatments were used prior to 1987.     

Mechanisms of imposex induction in the mud snail,Ilyanassa obsoleta: TBT as a neurotoxin and aromatase inhibitor

The occurrence of imposex, imposition of male sex characteristics on female snails, has been extensively documented throughout the world. Tributyltin (TBT) and other organotins have been causally linked to imposex induction at levels as low as 2 ng/l. There are several proposed mechanisms of action. First, TBT has been shown to be neurotoxic and to accumulate in snail ganglia. Peptide hormones control sexual differentiation in gastropods, and one hypothesis is that TBT acts as a neurotoxin to abnormally release the peptide hormone Penis Morphogenic Factor (PMF). However, PMF has not been characterized to date. The neuropeptide APGWamide significantly induces imposex in the mud snail, Ilyanassa obsoleta, at 10(-16) moles sub-cutaneous (SQ) injection over 2 weeks, and could be the PMF in this species. A second hypothesis is that TBT inhibits aromatase activity leading to increased testosterone levels and decreased estradiol. In vitro studies with snail digestive gland microsomes showed that TBT-dosed snails not exhibiting imposex had a 52% reduction in aromatase activity. Although the role of vertebrate sex steroids is not known in gastropods, it is possible that the combination of changes in peptide and steroid hormones may lead to imposex induction at extremely low doses of TBT.     

Ovo-testis and disturbed reproductive cycle in the giant abalone, Haliotis madaka: possible linkage with organotin contamination in a site of population decline.

Histological examination of gonads as well as chemical analysis of organotin compounds in tissues of the giant abalone, Haliotis madaka, was conducted to evaluate possible endocrine disruption and to consider the causal factors for the decline of abalone stocks in Japan. Abalone specimens were collected from two different areas, Tsushima as a reference site and Jogashima as a site representative of declining abalone populations, each month from September 1995 to November 1996. Scores were given to the development stages of reproductive cells in the ovary and testis. The degree of sexual maturation was evaluated by calculating the mean value of a histogram of these scores for the reproductive cells of each abalone. The temporal variations in degree of sexual maturation showed that female and male abalone from Tsushima matured synchronously, while those from Jogashima did not. The observed maximum reproductive developmental score in abalone from Jogashima was much lower than that from Tsushima, because immature females were present at the former site throughout the spawing season. Approximately 20% of the abalone from Jogashima were masculinized females with an ovo-testis. The masculinization of female abalone was similar to the imposex, typically induced in other gastropod molluscs by tributyltin (TBT) and triphenyltin (TPhT) from antifouling paints. Concentrations of TBT and TPhT in the muscles of abalone from Jogashima (n = 83) of 4.9 +/- 4.4 ng/g wet wt and 6.3 +/- 6.6 ng/g wet wt, respectively, were significantly higher than those from Tsushima (n = 125) (P < 0.01) of 0.8 +/- 0.8 ng/g wet wt and 0.6 +/- 1.3 ng/g wet wt, respectively. In situ exposure of abalone from Tsushima caged near a dockyard in Jogashima for 7 months (from the immature to the mature stage) resulted in spermatogenesis in the ovary of approximately 90% of females. Endocrine disruption may be caused in the giant abalone by organotin compounds from antifouling paints, which are possibly one of the causal factors for the decline of Japanese abalone stocks.     

Stramonita haemastoma as a bioindicator for organotin contamination in coastal environments

Stramonita haemastoma was investigated as a suitable bioindicator of TBT and TPhT contamination in the tropical Atlantic Ocean by: 1. Imposex induction in healthy females after inoculation with TBT and TPhT in the laboratory; and 2. Determining incidence of imposex in S. haemastoma collected from areas with various levels of tributyltin (TBT) and triphenyltin (TPhT) and determining the concentrations of these chemical in its tissues and that of its prey, the mussell Perna pernas. Imposex intensities and organotin concentrations in tissues showed good correlation, indicating S. haemastoma as a reliable bioindicator of TBT and TPhT contamination in coastal waters. Body burden threshold of TBT and TPhT for imposex induction was estimated to be 10-20 ng g(-1).     

Mechanisms of imposex induction in the mud snail, Ilyanassa obsoleta: TBT as a neurotoxin and aromatase inhibitor

The occurrence of imposex, imposition of male sex characteristics on female snails, has been extensively documented throughout the world. Tributyltin (TBT) and other organotins have been causally linked to imposex induction at levels as low as 2 ng/l. There are several proposed mechanisms of action. First, TBT has been shown to be neurotoxic and to accumulate in snail ganglia. Peptide hormones control sexual differentiation in gastropods, and one hypothesis is that TBT acts as a neurotoxin to abnormally release the peptide hormone Penis Morphogenic Factor (PMF). However, PMF has not been characterized to date. The neuropeptide APGWamide significantly induces imposex in the mud snail, Ilyanassa obsoleta, at 10⁻¹⁶ moles sub-cutaneous (SQ) injection over 2 weeks, and could be the PMF in this species. A second hypothesis is that TBT inhibits aromatase activity leading to increased testosterone levels and decreased estradiol. In vitro studies with snail digestive gland microsomes showed that TBT-dosed snails not exhibiting imposex had a 52% reduction in aromatase activity. Although the role of vertebrate sex steroids is not known in gastropods, it is possible that the combination of changes in peptide and steroid hormones may lead to imposex induction at extremely low doses of TBT.     

Assessment of imposex in the common whelk, Buccinum undatum (L.) from the Eastern Scheldt, The Netherlands

Several cruises were carried out on the Eastern Scheldt between September 1992 and March 1995 to study the frequency and appearance of imposex in the common whelk, Buccinum undatum L. Incidences of imposex were always > 90%. For the first time several stages of imposex in Buccinum undatum are reported. The evolution of imposex in the whelk seems to follow a similar route as in Hinia reticulata belonging to the same superfamily (Buccinacea). Tissue organotin concentrations of animals collected in February 1995 showed the highest organotin concentrations in the digestive gland and lowest in the foot of the animals. Concentrations of phenyltin compounds (up to 625 ngSn/g DW) were much higher than those of butyltin compounds (up to 40 ngSn/g DW).     

Imposex and organotin concentrations in Buccinum undatum and Neptunea antiqua from the North Sea: relationship to shipping density and hydrographical conditions

The presence and the development of imposex were investigated in the common whelk (Buccinum undatum) and the red whelk (Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (< 63 microm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of > or = 100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (> 10 ships day(-1)), intermediate (5--10 ships day(-1)), and low (< 5 ships day(-1)). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction < 63 microm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea.     

Movement and Home Ranges of Dugongs Around the Lease Islands, East Indonesia

Abstract. Four individual dugongs Dugong dugong , MÜLLER, 1776 were tracked with buoyant, tethered. conventional and satellite radio transmitters. The dugongs three adult females and one immature male were encircled with a net at a catch site near Haruku Island, East Indonesia, and tracked for between 41 and 285 days. The animals showed individualistic patterns of movement, moving between 2 and 3 core areas, travelling between 17 and 65 km from the site of capture. One adult female spent most of the time at two distinct inshore seagrass beds separated by about 17 km; she made five trips between the two sites. Two other females made separate trips to two distinct sites, one of them returning to the catch site at Haruku Island. The immature male journeyed between two areas about 65 km apart. completing the journey in four days. The patterns of movement confirmed a practice of regular recropping of restricted grazing swards by small, loose feeding assemblages rather than fixed herds with a strong social bond. Mean home ranges covered 4.1 km² 50% harmonic mean and 43.4 km² 95% harmonic mean.     

The effect of tributyltin upon steroid titres in the female dogwhelk, Nucella lapillus, and the development of imposex

Exposure of female Nucella lapillus to tributyltin (TBT) in seawater at a concentration of 40 ng Sn/litre led to accumulation of TBT in the tissues, and an increase in penis length compared to control animals. Investigation of the steroid concentrations by radioimmunoassay revealed a significant increase in testosterone after 28 days exposure to TBT. No significant effect was noted upon the amounts of progesterone or estradiol-17β. When testosterone was injected into female N. lapillus in the absence of TBT, penis length was found to increase significantly. These observation suggest that there may be an association between the change in testosterone titre in response to exposure to TBT and the development of imposex in the dogwhelk.     

三种织纹螺性畸变的发展过程与雄性结构效应

从2000年3月到2002年10月对中国沿海海产腹足类性畸变的大范围调查过程中．在广东省汕头港、湛江港和厦门港分别采集到西格织纹螺(Nassarius siquijorensis)、胆形织纹螺(Nassarius thersites)和节织纹螺(Nassarius hepaticus)等3个种，解剖观察发现3种织纹螺的雌性个体都发生了性畸变现象。根据织纹螺性畸变的发展过程，对目前的性畸变发展划分体系作了新的修改和补充。通过对比性畸变个体与正常雄性个体的特征．探讨了雄性个体结构特征在性畸变过程中的效应。     

Tributyltin and triphenyltin induce spermatogenesis in ovary of female abalone,Haliotis gigantea

Two-month flow-through exposure experiments of tributyltin (TBT) and triphenyltin (TPhT) were conducted with abalone, Haliotis gigantea. Nominal concentrations of 100 ng TBT/l and 100 ng TPhT/l caused significant spermatogenesis in ovaries of exposed females. There were also significantly more contracted primary oocytes observed in females exposed to either TBT or TPhT than controls. The incidence of two types of unknown cells was also significant in females exposed to TPhT. No significant histological changes were observed in testis of exposed males. This ovarian spermatogenesis caused by TBT and/or TPhT resembles gastropod imposex. Remarkably high concentrations of TBT and TPhT were observed in the head (including central nervous system ganglia), compared to muscles concentrations. Accumulation of TBT and TPhT in the head may disturb reproductive hormonal regulators through neuropeptides released from ganglia. This, as well as possible aromatase inhibition, may be one of the inducers for spermatogenesis in the abalone ovaries.     

Contamination of organotin compounds and imposex in molluscs from Vancouver,Canada

Gastropods and bivalves were collected at 15 sites at Vancouver and Victoria, Canada between 24 May and 7 June, 1999, to establish tissue concentrations of butyltin and phenyltin compounds, to record imposex symptoms in gastropods, and to assess the present status of organotin contamination around Vancouver. No neogastropods (such as Nucella lima) were found around Vancouver. Neogastropod populations could have been extirpated by severe TBT contamination in Vancouver, as relatively high concentrations of TBT were detected in tissues of Mytilus trossulus from Vancouver, and the neogastropods distributed in Vancouver might be sensitive to TBT. Recovery from imposex, however, was observed in neogastropod populations from three sites at Victoria and Mission Point. TBT contamination has continued around Vancouver, arising from continuous use of TBT in antifouling paints for vessels larger than 25 m in length; however, TBT has decreased around Victoria and Mission Point. Different patterns of TBT accumulation in tissue were observed among the bivalve species from Vancouver. The highest TBT concentration detected in Tresus capax suggested some possible adverse effects. TBT was the most predominant butyltin component in almost all bivalve specimens surveyed, suggesting a low rate of TBT metabolism. Phenyltin compounds were not detected in any molluscan specimens in this study.