Reproductive Failure in Populations of the Dog-Whelk, Nucella Lapillus, Caused by Imposex Induced by Tributyltin from Antifouling Paints

1986 ◽  
Vol 66 (4) ◽  
pp. 767-777 ◽  
Author(s):  
P. E. Gibbs ◽  
G. W. Bryan
Keyword(s):  
Vas Deferens ◽  
Early Stage ◽  
Premature Death ◽  
Intermediate Stage ◽  
Reproductive Failure ◽  
Nucella Lapillus ◽  
Egg Capsules ◽  
Male Characters ◽  
High Incidence ◽  
Declining Populations

The development of male characters, notably a penis and a vas deferens, on the female (the phenomenon of ‘imposex’) of the dog-whelk, Nucella lapillus, is described. Three stages are recognized: an ‘early’ stage involving the formation of a vas deferens and a small penis, an ‘intermediate’ stage characterized by the enlargement of the female penis to a size approaching that of the male and a ‘late’ stage during which the female opening (vulva) is occluded by overgrowth of vas deferens tissue. This blockage of the pallial oviduct prevents the release of egg capsules and renders the female sterile. The extent and cause of such reproductive failure is evident from the high incidence of females containing aborted capsules in declining populations close to sources of tributyltin (TBT) contamination. These same populations comprise fewer females than expected and it would appear that the accumulation of aborted capsules within the pallial oviduct eventually causes the premature death of the female.

The Effects of Tributyltin on Dogwhelks (Nucella Lapillus) From Scottish Coastal Waters

1989 ◽  
Vol 69 (2) ◽  
pp. 335-354 ◽  
Author(s):  
S.K. Bailey ◽  
I.M. Davies
Keyword(s):  
Reproductive Tract ◽  
Vas Deferens ◽  
Nucella Lapillus ◽  
Dioecious Species ◽  
Progressive Development ◽  
Egg Capsules ◽  
Reproductive Ability ◽  
Sexual Characteristics ◽  
Penis Length ◽  
The Mean

The common dogwhelk (Nucella lapillus) is a dioecious species. However, on exposure to low concentrations (<1 ng I-1, Gibbs et al., 1987) of tributyltin (TBT) females develop certain male sexual characteristics, notably a penis and vas deferens. This phenomenon, first reported by Blaber (1970) in dogwhelks from the Plymouth area, and later termed 'imposex' (Smith, 1981), is now recognised as the most sensitive and straightforward way to identify contamination of coastal areas by TBT. The degree of imposex may be readily quantified as the relative penis size index (RPSI), which expresses the relative bulk of the penes in females and males from a given sample. It is calculated as (mean cubed female penis length/the mean cubed male penis length) x 100% (Gibbs et al., 1987). Gibbs et al. (1987) have examined the development of imposex in greater detail, and have divided the process into six stages (known as the vas deferens sequence, or VDS) based upon the degree of development of the vas deferens and penis in the female animal. This classification enables an assessment to be made of the reproductive ability of an animal. Stages 1 to 4 show a progressive development of the penis and vas deferens. At a VDS of 5, vas deferens tissue proliferates over the opening of the reproductive tract, blocking it, and subsequently causing sterility due to the inability of the animal to release egg capsules. Aborted egg capsules then gradually accumulate in the capsule gland (stage 6). The vas deferens sequence index, VDSI, is the mean VDS in a given sample of females.

Sex Change in the Female Dog-Whelk, Nucella Lapillus, Induced by Tributyltin from Antifouling Paints

1988 ◽  
Vol 68 (4) ◽  
pp. 715-731 ◽  
Author(s):  
P. E. Gibbs ◽  
P. L. Pascoe ◽  
G. R. Burt
Keyword(s):  
Laboratory Experiments ◽  
Vas Deferens ◽  
Prolonged Exposure ◽  
Conclusive Evidence ◽  
Nucella Lapillus ◽  
Antifouling Paints ◽  
Widespread Occurrence ◽  
Marine Gastropods ◽  
Egg Capsules ◽  
Tributyltin Chloride

Imposex, the development of a penis and vas deferens in the female (Smith, 1971) is known to occur in over 30 species of marine gastropods but, to date, in only one species has this syndrome been demonstrated to have a serious deleterious effect. This species is the dog-whelk, Nucella lapillus L. Both field and laboratory observations have provided conclusive evidence that imposex in N. lapillus is initiated by tributyltin (TBT), used as a biocide in antifouling paints, at concentrations in water of less than 1 ng Sn/1. This feature is manifest in the widespread occurrence of imposex even in areas far removed from centres of boating activity (see Bryan et al. 1986). Imposex appears to have little effect on the reproductive biology of N. lapillus until this syndrome is developed to its fullest extent when it sterilises the female because the pallial oviduct becomes occluded by vas deferens tissue thus preventing expulsion of the egg capsules (Gibbs & Bryan, 1986). Laboratory experiments have indicated that this condition, found in females close to harbours and marinas, may prevail after prolonged exposure during the first few years of life to TBT levels as low as 2 ng Sn/1 (Gibbs et al. 1987). Of six organotin compounds tested by Bryan, Gibbs & Burt (1988), tributyltin chloride proved the most effective in promoting imposex in N. lapillus.

The use of the dog-whelk, Nucella lapillus, as an indicator of tributyltin (TBT) contamination

1987 ◽  
Vol 67 (3) ◽  
pp. 507-523 ◽  
Author(s):  
P. E. Gibbs ◽  
G. W. Bryan ◽  
P. L. Pascoe ◽  
G. R. Burt
Keyword(s):  
Vas Deferens ◽  
Nucella Lapillus ◽  
Male Characters ◽  
South West ◽  
Nassarius Obsoletus ◽  
South West England

The term ‘imposex’ was coined by Smith (1971) to describe the superimposition of male characters onto unparasitized and parasitized females of gonochoristic gastropods. In Nassarius obsoletus (Say) the development of imposex results in the female having one or more of the following characters: (1) a penis with a duct leading to (2) a vas deferens which passes back to the ventral channel of the capsule gland and (3) convolution of the normally straight gonadial oviduct (Smith, 1980). Imposex in the similarly gonochoristic Nucella lapillus (L.) was first noted by Blaber (1970) who found females with penis-like outgrowths in Plymouth Sound populations. Subsequent studies (Bryan et al. 1986; Gibbs & Bryan, 1986) have demonstrated that the incidence and intensity of imposex have since increased markedly in the same populations and that the phenomenon is widespread around south-west England.

scholarly journals Chest computed tomography imaging features in patients with coronavirus disease 2019 (COVID-19)

2021 ◽  
Vol 49 (5) ◽  
pp. 030006052110106
Author(s):  
Hoda Salah Darwish ◽  
Mohamed Yasser Habash ◽  
Waleed Yasser Habash
Keyword(s):  
Computed Tomography ◽  
Intermediate Phase ◽  
Early Stage ◽  
Lower Lobe ◽  
Ground Glass Opacity ◽  
Intermediate Stage ◽  
Mediastinal Lymphadenopathy ◽  
Imaging Features ◽  
Stage Disease ◽  
Bilateral Lesions

Objective To analyze computed tomography (CT) features of symptomatic patients with coronavirus disease 2019 (COVID-19). Methods Ninety-five symptomatic patients with COVID-19 confirmed by reverse-transcription polymerase chain reaction from 1 May to 14 July 2020 were retrospectively enrolled. Follow-up CT findings and their distributions were analyzed and compared from symptom onset to late-stage disease. Results Among all patients, 15.8% had unilateral lung disease and 84.2% had bilateral disease with slight right lower lobe predilection (47.4%). Regarding lesion density, 49.4% of patients had pure ground glass opacity (GGO) and 50.5% had GGO with consolidation. Typical early-stage patterns were bilateral lesions in 73.6% of patients, diffuse lesions (41.0%), and GGO (65.2%). Pleural effusion occurred in 13.6% and mediastinal lymphadenopathy in 11.5%. During intermediate-stage disease, 47.4% of patients showed GGO as the disease progressed; however, consolidation was the predominant finding (52.6%). Conclusion COVID-19 pneumonia manifested on lung CT scans with bilateral, peripheral, and right lower lobe predominance and was characterized by diffuse bilateral GGO progressing to or coexisting with consolidation within 1 to 3 weeks. The most frequent CT lesion in the early, intermediate, and late phases was GGO. Consolidation appeared in the intermediate phase and gradually increased, ending with reticular and lung fibrosis-like patterns.

A decadal study of biometric and imposex indices in two gastropods

2019 ◽  
Vol 99 (7) ◽  
pp. 1601-1614
Author(s):  
J. M. Ruiz ◽  
B. Carro ◽  
N. Albaina ◽  
L. Couceiro ◽  
M. Quintela ◽  
...  
Keyword(s):  
Vas Deferens ◽  
Shell Height ◽  
Chemical Analyses ◽  
Nucella Lapillus ◽  
Nw Spain ◽  
Potential Applications ◽  
Penis Length ◽  
The Mean ◽  
Tbt Biomonitoring ◽  
Tbt Pollution

AbstractWe have monitored tributyltin (TBT) pollution in Galicia (NW Spain) for more than a decade by means of assessing gastropod imposex in populations of Nucella lapillus (N ≥ 34) and Tritia reticulata (N ≥ 18) at regular intervals. Several thousand specimens were processed to obtain their shell height (SH), penis length (PL) and vas deferens sequence (VDS); imposex indices (including the VDS index, VDSI) were subsequently calculated. The regional mean SH of both females and males has not changed significantly in either species throughout the study. This also applies to the mean male PL in N. lapillus, but male T. reticulata penises surprisingly enlarged. On the contrary, the regional mean female PL (MFPL) and all imposex indices significantly decreased in both snails. Results confirm previous conclusions based on the chemical analyses of tissues and partial imposex observations. In addition, the close correlations between MFPL and VDSI show some potential applications to TBT biomonitoring.

Male genital defect (Dumpton Syndrome) in the dog-whelk Nucella lapillus (Neogastropoda): Mendelian inheritance inferred, based on laboratory breeding experiments

2005 ◽  
Vol 85 (1) ◽  
pp. 143-150 ◽  
Author(s):  
P.E. Gibbs
Keyword(s):  
Vas Deferens ◽  
Mendelian Inheritance ◽  
Nucella Lapillus ◽  
F1 Progeny ◽  
Antifouling Agent ◽  
Ambient Concentrations ◽  
Laboratory Breeding ◽  
F2 Progeny ◽  
Male Genital

Laboratory breeding of the dog-whelk, Nucella lapillus, has established that the male-sterilizing Dumpton Syndrome (DS)—underdevelopment, or non-development (aphally), of the penis, incomplete formation (non-closure) of the vas deferens, resulting in a split prostate—can be readily observed in male F1 progeny. Cultivated under high ambient concentrations of the antifouling agent tributyltin (TBT), DS-carrying females can be recognized by their lesser degree of masculinization (imposex): sterilization is thereby avoided. When Dumpton females are crossed, under high ambient TBT, with individuals from a non-DS-affected population (Bude, North Cornwall) DS is absent from both sexes. Crosses of these F1 progeny result in F2 progeny exhibiting the classic DS symptoms in both sexes. A Mendelian mechanism for DS inheritance is suggested by the data.

Transition phenomena in diffusive motions due to the change of memory effects

2019 ◽  
Vol 34 (01) ◽  
pp. 2050013
Author(s):  
Dongmi Kim ◽  
Hyun-Joo Kim
Keyword(s):  
Stochastic Process ◽  
Memory Effect ◽  
Stochastic Models ◽  
Hurst Exponent ◽  
Early Stage ◽  
Intermediate Stage ◽  
Memory Effects ◽  
Replication Process ◽  
Normal Diffusion ◽  
Previous Step

In the anomalous diffusions, the transition phenomena from superdiffusion (or subdiffusion) to normal diffusion have been found in several experiments and studied by stochastic models. In this study, we found the diffusion transition which occurs twice in a stochastic process, first from superdiffusion to subdiffusion, and then from subdiffusion to normal diffusion by using the nonstationary Markovian replication process with the memory of the previous step exponentially decaying with time. In the early stage, when the walker strongly follows the previous step, superdiffusive behaviors occur, while in the intermediate stage in which the memory effect decays exponentially, the motion of the walker shows subdiffusive behaviors. Eventually, as the memory effect almost disappears, the motion reduces to normal diffusion. We also found that the Hurst exponent in the intermediate subdiffusive region becomes smaller when the change of the memory effect is more abrupt.

A Possible Role of Midbrain Dopamine Neurons in Short- and Long-Term Adaptation of Saccades to Position-Reward Mapping

2004 ◽  
Vol 92 (4) ◽  
pp. 2520-2529 ◽  
Author(s):  
Yoriko Takikawa ◽  
Reiko Kawagoe ◽  
Okihide Hikosaka
Keyword(s):  
Visual Cues ◽  
Early Stage ◽  
Intermediate Stage ◽  
Saccade Latency ◽  
Dopamine Neurons ◽  
Neuronal Responses ◽  
Sensory Stimuli ◽  
Reward Delivery ◽  
Midbrain Dopamine

Dopamine (DA) neurons respond to sensory stimuli that predict reward. To understand how DA neurons acquire such ability, we trained monkeys on a one-direction-rewarded version of memory-guided saccade task (1DR) only when we recorded from single DA neurons. In 1DR, position-reward mapping was changed across blocks of trials. In the early stage of training of 1DR, DA neurons responded to reward delivery; in the later stages, they responded predominantly to the visual cue that predicted reward or no reward (reward predictor) differentially. We found that such a shift of activity from reward to reward predictor also occurred within a block of trials after position-reward mapping was altered. A main effect of long-term training was to accelerate the within-block reward-to-predictor shift of DA neuronal responses. The within-block shift appeared first in the intermediate stage, but was slow, and DA neurons often responded to the cue that indicated reward in the preceding block. In the advanced stage, the reward-to-predictor shift occurred quickly such that the DA neurons' responses to visual cues faithfully matched the current position-reward mapping. Changes in the DA neuronal responses co-varied with the reward-predictive differentiation of saccade latency both in short-term (within-block) and long-term adaptation. DA neurons' response to the fixation point also underwent long-term changes until it occurred predominantly in the first trial within a block. This might trigger a switch between the learned sets. These results suggest that midbrain DA neurons play an essential role in adapting oculomotor behavior to frequent switches in position-reward mapping.

STUDIES IN FOREST PATHOLOGY: XI. DECAY IN BLACK COTTONWOOD IN THE MIDDLE FRASER REGION, BRITISH COLUMBIA

1953 ◽  
Vol 31 (5) ◽  
pp. 675-692 ◽  
Author(s):  
G. P. Thomas ◽  
D. G. Podmore
Keyword(s):  
Early Stage ◽  
Populus Trichocarpa ◽  
Significant Loss ◽  
Tree Age ◽  
Relative Importance ◽  
Average Volume ◽  
Black Cottonwood ◽  
Infected Tree ◽  
High Incidence ◽  
Low Probability

A study of decay of black cotton wood, Populus trichocarpa Torr. and Gray, revealed that, although 70 species of fungi caused decay, only six caused significant loss in living trees and that two of these, Polyporus delectans Peck and Pholiota destruens (Brand.) Quél., caused 92% of this loss. The sporophores and associated decays of certain of the fungi are described and their relative importance is indicated. Data on the relation of decay to tree age showed that, despite a high incidence of infection, the average volume of decay per infected tree was low. In general, decay proved important only to the recovery of specialty products such as plywood. A significant reduction of strength was found to occur in wood containing an early stage of decay caused by P. destruens. The practicability of segregating trees having a high or low probability of being decayed was demonstrated through the use of decay indicators.

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