Histochemical changes of carbohydrate and protein contents in the digestive gland cells of the land snail Monacha cartusiana following starvation

The present study was designed to investigate histochemically the detection of carbohydrate and protein in the normally feeding snails and after 15 and 30 days of starvation. Generally, abundant carbohydrate and protein materials were detected in the component cells of the digestive gland of normally feeding snails. The results of this investigation revealed a pronounced decline of carbohydrates in the digestive gland cells of Monacha cartusiana snails after starvation. Severe decline in carbohydrate content was observed especially after 30 days of starvation. Moreover, protein inclusions have exhibited a week stainability in the digestive gland cells of these snails as a consequence of starvation.     

Polygyrid relations: a phylogenetic analysis of 17 subfamilies of land snails (Mollusca: Gastropoda: Stylommatophora)

The family of polygyrid land snails in North America is significant for its sympatric shell convergences, diversity of mating systems and complex zoogeography; its monophyly and its relation to other families has long been questionable. Cladistic analysis has been performed on one representative each of 17 subfamilies, including all three polygyrid subfamilies and one or more subfamilies each from all ten of the families that have been proposed as the polygyrid sister groups. Eighteen anatomical synapomorphies are used, of which eight are newly discovered, four are differently assessed from previous studies, and six are traditional. The resulting strict consensus tree of alternative maximum-parsimony cladograms is: (Acavidae (Ammonitellidae Corillidae ((Discidae Oreohelicidae) (Helminthoglyptidae Bradybaenidae Polygyridae (Thysanophoridae (Camaenidae Sagdidae)))))).
According to this working hypothesis, the Polygyridae are monophyletic, and their sister group remains unresolved, although the Acavidae, Ammonitellidae, Corillidae, Discidae and Oreohelicidae can be ruled out. Of the five classifications of stylommatophoran families that have been proposed in the past 12 years, the consensus tree is closest to that of Nordsieck. For future morphological work, three regions are recommended as potentially rich in unused phylogenetic information: the fertilization pouch-seminal receptacle complex, the ureter at the pneumostome and the ventral-chain ganglia. Simultaneous dissection, wkh side-by-side comparisons, is recommended over other methods for detecting homologies in land snails. Molecular characters should be exploited, because of the scarcity and the frequent homoplasy of morphological characters.     

Influence of dietary rice culture material containing cyclopiazonic acid on certain serum biochemical parameters of broiler chickens

Three hundred and forty-eight Vencob broiler chickens were fed diets containingPenicillium griseofulvum rice culture material with 0, 12.5, 25 and 50 ppm of the mycotoxin cyclopiazonic acid (CPA) for 28 days. Serum samples were collected from 9 birds in each group at weekly intervals to study the effect of sublethal doses of CPA on certain serum biochemical parameters. Significant reductions in weight gains (p<0.01) and feed consumptions (p<0.05) were observed at 25 and 50 ppm. Exocrine pancreas showed degenerative and necrotic changes in CPA fed chickens. The CPA had significant (p<0.05) influence on serum total protein, albumin, cholesterol, amylase and lipase levels. CPA did not affect serum glucose levels. There was a decline in levels of total serum protein and albumin in CPA fed groups. But serum cholesterol, amylase and lipase showed dose-dependent increases.Paper presented in XI Indian Association of Veterinary Pathologists conference held at Anand, India, Dec 13–15, 1994.     

Toxicity studies of nonylphenol on rosy barb (Puntius conchonious): a biochemical and histopathological evaluation

Acute and subacute toxicity of the nonylphenol (NP) on fish was investigated in laboratory toxicity tests with rosy barb (Puntius conchonious). The acute toxicity of NP to rosy barb was determined in semi-static bioassays. Median lethal concentration (LC50) for 96 h was 1.72 microM. The effects of sublethal concentrations of NP (0.17, 0.34 and 0.68 microM) on the structures and biochemical parameters [alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanin aminotransferase (ALT)] in gills, liver and kidney of rosy barb were studied after 14 days. The results showed that NP caused alteration of the structure in organs, as evidenced by the hyperplasia of epithelium and the fusion of secondary lamellae in the gills, the disappearance of the cell membrane and the cell necrosis in the liver as well as haemorrhages in the kidney. In addition, the functional enzyme activities were also changed. The increase trend in ALP activity in organs of fish treated with NP was recorded. The levels of AST and ALT in gills, liver and kidney were stimulated to rise at the lower concentration and fall at the higher concentration NP treatment compared to controls. This study suggests that NP can alter of the structures and biochemical parameters within non-endocrine tissue of fish and these changes may be mediated via destroying membrane structure and inducing cell necrosis.     

Relevance of body size and shell colouration for thermal absorption and heat loss in white garden snails,Theba pisana (Helicidae), from Northern France

The internal temperature of land snails depends on environmental factors, such as exposure to electromagnetic radiation and airflow as well as biotic factors including shell size, shell colouration and thickness or the resting position of the snail. In controlled field experiments, we quantified heating by thermal absorption of light and airflow-induced heat loss in the white garden snail, Theba pisana, from Normandy, France. Heating experiments revealed a significant positive relation of the internal body temperature with illumination period, shell temperature and air temperature at different times of day. The size of the snails was negatively related with both of the given illumination times: smaller animals heated up stronger than larger ones. The temperature at the surface of the shell significantly depended on the illumination period and the time of day. An AIC-based quality assessment of multiple linear modelling showed that, for explaining both shell surface and internal temperature of the soft body, several factors, i.e., exposure time, daytime, shell size and colouration contributed to the best models, respectively. Similarly, heat loss of the soft body after and during exposure of the snails to sunlight by a constant airflow depended on the initial body temperature, shell size, colouration and ambient air temperature. Our study revealed also the importance of both shell size and colouration for the loss of body temperature under natural conditions: small and banded animals that had heated up to temperatures above 30 °C cooled down faster than large and un-banded ones.     

Distribution of land snails (Mollusca, Gastropoda, Pulmonata) on the island of Gran Canaria (Canary Islands) in relation to protected natural areas

The oceanic island of Gran Canaria, part of the Macaronesian Archipelagos, is highly deteriorated, a situation which has had negative repercussions for endemic species. A recent law, however, established 32 Protected Natural Areas in an attempt to remedy the problem. In the present work we show the distribution of common (non-endemic) land snails on the island. The snails were largely introduced by man over the past five centuries. A comparison between the distribution of the endemic land snails and the protected areas shows the latter to be generally adequate. We also suggest some modifications to the law in two Areas and the addition to the list of two further Areas so as to guarantee protection of several endemic species currently under threat (according to the criteria of the IUCN): 2 critically endangered, Hemicycla saulcyi saulcyi and Napaeus isletae, 2 vulnerable, Theba arinagae and Obelus despreauxii, and 1 lower risk, Hemicycla berkeleyi.     

Multiple scale patterns of shell and anatomy variability in land snails: the case of the Sicilian Marmorana (Gastropoda: Pulmonata, Helicidae)

Certain major aspects of phenotypic diversity are still largely unexplained. When phenotypic patterns do not relate to habitat variables, fine analysis of morphological patterns and their distribution sheds light on the origin of diversity. Among invertebrates, snails are an ideal model for studying the roles of the neutral processes and selection involved in creating diversity. To understand patterns and processes of variability on different scales (regional: areas; local: sites), morphological variability of two sets of characters (shell and genitalia) was quantified in a group of rock-dwelling land snails of the genus Marmorana (Pulmonata, Helicidae). To analyse shell variability, partitioning of the overall variation into size and shape components was analysed by a principal component-based approach. Shell shape and size variability is not significantly influenced by any environmental pressure. Variability at site scale is mainly attributed to shell size, which is a trait demonstrated to have a high degree of phenotypic plasticity. No sharp changes were observed for genitalia. Moreover, allometries between shell size and genitalia measurements involve a few populations. The observed multiple scale patterns are in line with the hypothesis that genital variance may be selectively controlled to maintain function.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 359–370.     

The freshwater snails (Gastropoda) of Iran, with descriptions of two new genera and eight new species

Using published records and original data from recent field work and revision of Iranian material of certain species deposited in the collections of the Natural History Museum Basel, the Zoological Museum Berlin, and Natural History Museum Vienna, a checklist of the freshwater gastropod fauna of Iran was compiled. This checklist contains 73 species from 34 genera and 14 families of freshwater snails; 27 of these species (37%) are endemic to Iran. Two new genera, Kaskakia and Sarkhia, and eight species, i.e., Bithynia forcarti, Bithynia starmuehlneri, Bithynia mazandaranensis, Pseudamnicola georgievi, Kaskakia khorrasanensis, Sarkhia sarabensis, Valvata nowsharensis and Acroloxus pseudolacustris are described as new to science; Ecrobia grimmi (Clessin & Dybowski, 1888), Heleobia dalmatica (Radoman, 1974) and Hippeutis complanatus (Linnaeus, 1758) are reported for the first time from Iran. Additional field work is highly desirable for a more appropriate evaluation of the extant freshwater snail biodiversity in Iran.     

Influence of collagen gel substrata on certain biochemical activities of hepatocytes in primary culture

In order to study the influence of cell shape as modulated by the extracellular matrix on the cellular activity, hepatocytes isolated from liver were maintained on collagen I coated plastic substrata and collage I gel substrata and certain hepatocyte specific functions were investigated. The incorporation of³[H]-leucine into total proteins and albumin secreted by cells maintained on collagen gel was found to be significantly higher compared to those maintained on a collagen coated plastic substrata, indicating that hepatocytes on collagen gel have an enhanced albumin synthesizing capacity. Increased incorporation of³⁵[S]-sulphate into total proteoglycans (PG) and a relatively higher fraction of the³⁵[S]-PG in the extracellular space showed an increased rate of synthesis and secretion of sulphated PGs by cells maintained on collagen gels. But in contrast to the above results, the incorporation of³[H]-leucine into cytokeratins C₈, C₁₈ and actin were significantly low in cells maintained on collagen gel. The tyrosine amino transferase activity exhibited by hepatocytes preincubated with dexamethasone on collagen gel was also significantly low. The different forms of collagen substrata appeared to have no effect on the amino acid transport by hepatocytes, further suggesting that the various hepatocyte specific functions are not uniformly altered when hepatocytes are maintained on three-dimensional collagen gel substrata. These results indicate that the shape of the cell as determined by the nature of the matrix substratum influences the synthetic activity of secretory proteins and those remaining intracellularly, differently.     

Surface electromyographic measurements on land prior to and after 90 min of submersion (swimming) are highly reliable

The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after submersion (swimming) for 90 min. Isometric maximal voluntary contractions (MVC) on land and in water were collected from eight muscles on the right side of the body in 12 healthy participants (6 women and 6 men). Repeated measures analyses of variance (general linear model ANOVA) showed no significant differences in the peak amplitude MVC scores between land pre and post measurements for all muscles, p > .05. The mean of the Intraclass correlation coefficient (1, 1) for land pre and land post was .985 with (95% Cl = .978–.990), for land pre and water pre .976 (95% Cl = .964–.984) and for land pre and post, water pre and post .981 (95% Cl = .974–.987). Measuring sEMG on land before and after a prolonged submersion is highly reliable without additional waterproofing when using electrodes with 57 mm diameter.     

Species richness, environmental heterogeneity and area: a case study based on land snails in Skyros archipelago (Aegean Sea, Greece)

Aim To test the performance of the choros model in an archipelago using two measures of environmental heterogeneity. The choros model is a simple, easy‐to‐use mathematical relationship which approaches species richness as a combined function of area and environmental heterogeneity. Location The archipelago of Skyros in the central Aegean Sea (Greece). Methods We surveyed land snails on 12 islands of the archipelago. We informed the choros model with habitat data based on natural history information from the land snail species assemblage. We contrast this with habitat information taken from traditional vegetation classification to study the behaviour of choros with different measures of environmental heterogeneity. R² values and Akaike's information criterion (AIC) were used to compare the choros model and the Arrhenius species–area model. Path analysis was used to evaluate the variance in species richness explained by area and habitat diversity. Results Forty‐two land snail species were recorded, living in 33 different habitat types. The choros model with habitat types had more explanatory power than the classic species–area model and the choros model using vegetation types. This was true for all islands of the archipelago, as well as for the small islands alone. Combined effects of area and habitat diversity primarily explain species richness in the archipelago, but there is a decline when only small islands are considered. The effects of area are very low both for all the islands of the archipelago, and for the small islands alone. The variance explained by habitat diversity is low for the island group as a whole, but significantly increases for the small islands. Main conclusions The choros model is effective in describing species‐richness patterns of land snails in the Skyros Archipelago, incorporating ecologically relevant information on habitat occupancy and area. The choros model is more effective in explaining richness patterns on small islands. When using traditional vegetation types, the choros model performs worse than the classic species–area relationship, indicating that use of proxies for habitat diversity may be problematic. The slopes for choros and Arrhenius models both assert that, for land snails, the Skyros Archipelago is a portion of a larger biogeographical province. The choros model, informed by ecologically relevant habitat measures, in conjunction with path analysis points to the importance of habitat diversity in island species richness.     

The influence of the ecological characteristics of phytocoenoses on the percentage proportions of zoogeographical elements in the malacocoenoses of land snails (Mollusca: Gastropoda terrestria)

The influence of 11 forest phytocoenoses in a single area (the Medvednica Mountain in north-western Croatia) on the composition of the zoogeographical elements of the land malacofauna was analysed. It was established that malacocoenoses in different plant associations of the same phytogeographical and zoogeographical area have different compositions in respect to the zoogeographical elements of the land snail fauna. Zoogeographical elements located on borders of the range display the widest divergences in their percentage representation in the malacocoenoses of the forest phytocoenoses of a single area. This is due to varying ecological conditions in the phytocoenoses under investigation.Abbreviations as. = association - subas.= subassociation     

Experimental hybridization between two sub-species of snails (Helix aspersa aspersa and Helix aspersa maxima): consequences for fertility,survival and growth

Summary

The experimental laboratory pairing of hermaphroditic snails of different sub-species, Helix aspersa aspersa (H.a.a) and H. aspersa maxima (H.a.m.), made it possible to obtain both reciprocal hybrids for the first time and to describe their growth. The relatively small number of matings observed (20–25%) was partly responsible for the small number of clutches obtained (10–13%). The cross H.a.a.M × H.a.m.F is more fertile than the reciprocal. The observed tendency to reproductive isolation (behavioural and anatomical) suggests that H.a.a. and H.a.m. should be considered as two sub-species. Hybridization is not accompanied by a beneficial heterosis effect since significant juvenile mortality and an increased variation in growth were observed. The small size of H.a.a. is a dominant characteristic, whereas the colour of the mantle edge in the Fl individuals is intermediate between the black of H.a.m. and the white of H.a.a. The Fl generation is fertile and gives F2 snails with an adult size close to that of H.a.a. but slower growing. This approach allows investigations into the mechanisms underlying the reproductive isolation of parental sub-species.     

Scale and structure of time-averaging (age mixing) in terrestrial gastropod assemblages from Quaternary eolian deposits of the eastern Canary Islands

Quantitative estimates of time-averaging (age mixing) in gastropod shell accumulations from Quaternary (the late Pleistocene and Holocene) eolian deposits of Canary Islands were obtained by direct dating of individual gastropods obtained from exceptionally well-preserved dune and paleosol shell assemblages. A total of 203 shells of the gastropods Theba geminata and T. arinagae, representing 44 samples (= stratigraphic horizons) from 14 sections, were dated using amino acid (isoleucine) epimerization ratios calibrated with 12 radiocarbon dates. Most samples reveal a substantial variation in shell age that exceeds the error that could be generated by dating imprecision, with the mean within-sample shell age range of 6670 years and the mean standard deviation of 2920 years. Even the most conservative approach (Monte Carlo simulations with a non-sequential Bonferroni correction) indicates that at least 25% of samples must have undergone substantial time-averaging (e.g., age variations within those samples cannot be explained by dating imprecision alone). Samples vary in shell age structure, including both left-skewed (17 out of 44) and right-skewed distributions (26 out of 44) as well as age distributions with a highly variable kurtosis. Dispersion and shape of age distributions of samples do not show any notable correlation with the stratigraphic age of samples, suggesting that the structure and scale of temporal mixing is time invariant. The statistically significant multi-millennial time-averaging observed here is consistent with previous studies of shell accumulations from various depositional settings and reinforces the importance of dating numerous specimens per horizon in geochronological studies. Unlike in the case of marine samples, typified by right-skewed age distributions (attributed to an exponential-like shell loss from older age classes), many of the samples analyzed here displayed left-skewed distributions, suggestive of different dynamics of age mixing in marine versus terrestrial shell accumulations.     

Impacts of nanoparticles and phosphonates in the behavior and oxidative status of the mediterranean mussels (Mytilus galloprovincialis)

The current study investigated the exposure of the Mediterranean mussel (Mytilus galloprovincialis) to gold nanoparticles decorated zinc oxide (Au-ZnO NPs) and phosphonate [Diethyl (3-cyano-1-hydroxy-1-phenyl-2-methylpropyl)] phosphate (PC). The mussels were exposed to concentrations of 50 and 100 µg L^-1 of both compounds alone, as well as to a mixture of both pollutants (i.e. Mix). The singular and the combined effect of each pollutant was investigated by measuring the concentration of various metals (i.e., Cu, Fe, Mn, Zn and Au) in the the digestive glands and gills of mussels, their filtration capacity (FC), respiration rate (RR) and the response of oxidative biomarkers, respectively, following 14 days of exposure. The concentrations of Cu, Fe, Mn, Zn and Au increased directly with Au-ZnO NPs in mussel tissues, but significantly only for Zn. In contrast, the mixture of Au-ZnO100 NPs and PC100 did not induce any significant increase in the content of metals in digetsve glands and gills, suggesting antagonistic interactions between contaminants. In addition, FC and RR levels decreased following exposure to Au-ZnO100 NPs and PC100 treatments and no significant alterations were observed after the exposure to 50 µg.L^-1 of both contaminants and Mix. Hydrogen peroxide (H₂O₂) level, GSH/GSSG ratio, superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) activities showed significant changes following the exposure to both Au-ZnO NPs and PC, in the gills and the digestive glands of the mussel. However, no significant modifications were observed in both organs following the exposure to Mix. The current study advances the understanding of the toxicity of NPs and phosphonates on M. galloprovincialis and sets the path for future ecotoxicological studies regarding the synergic effects of these substances on marine species. Moreover, the current experiment suggests that the oxidative stress and the neurotoxic pathways are responsive following the exposure of marine invertebrates to both nanoparticles and phosphonates, with potential antagonist interactions of these substances on the physiology of targeted species.     

Physiological adjustment of the genus Limicolaria (Gastropoda: Pulmonata) during aestivation and activity in tropical agro-ecosystem

Comparisons of sympatric species inhabiting the same ecological habitat may elucidate adaptive processes. We studied the physiological patterns of two species of the genus Limicolaria (L. aurora and L. flammea) that thrive in a hot tropical habitat. We examined changes in water content, biochemical fuel reserves and haemolymph enzyme activities during aestivation and activity. Our results indicate that both species had the potential to conserve body water during aestivation. A definite pattern in foot muscle biochemical fuel reserves was observed. Both species depleted glycogen during aestivation while building up lipids. Catabolism of protein was observed during aestivation. Lactate levels and the activity of lactate dehydrogenase both decreased during aestivation, and both variables later increased at the onset of activity. Significantly higher enzyme activities were recorded during aestivation than during the active period. Stepwise discrimination analysis revealed lactate as the significant predictor of differences between the two periods, with 97.9% of the cases correctly classified. No significant correlation was observed between the measured variables and climatic data. Our results suggest that the physiological adaptation of Limicolaria is not environmentally predictable, rather it is inherently determined for ensuring physiological adjustment for survival in the tropics.     

Effects of exposure to multiple trace metals on biochemical, histological and ultrastructural features of gills of a freshwater fish, Channa punctata Bloch

The trace metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of a mixture of four essential and toxic metals (Cu, Cd, Fe and Ni) on biochemical and morphological characteristics of the gills of a biomarker freshwater fish Channa punctata (Bloch) using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days. Biochemical studies as well as light microscopy (LM) and scanning electron microscopy (SEM) revealed significant metal exposure-induced alterations in gills. Besides ultastructural changes, activities of antioxidant enzymes such catalase (CAT), glutathione S-transferase (GST) and superoxide dismutase (SOD) were significantly altered in the gills of exposed fish. The reduced glutathione (GSH) was significantly (p<0.001) decreased, while lipid peroxidation (LPO) was significantly (p<0.001) increased. The main alterations in general morphology of fish gills included spiking and fusion of secondary lamellae, formation of club-shaped filaments, and vacuolization and necrosis of filament epithelium in the interlamellar regions. SEM studies showed gradual increase of the density and apical surface area of the chloride cells and transformation of the surface structure of the pavement cells. The results of this study indicate adaptive as well a toxic responses in fish gills exposed to mixture of trace metals. Low concentrations of trace metal appear to compromise the antioxidant defense of gills. Lesions in the gill morphology caused by the effect of low concentrations of trace metals could lead to functional alterations and interference with fundamental processes such as maintenance of osmoregulation, gas exchange and xenobiotic metabolism in the exposed fish populations.     

福寿螺和田螺消化酶活性比较

为比较福寿螺(Pomacea canaliculata(Lamarck,1828))和当地中国圆田螺(Cipangopaludina chinensis(Gray,1832))消化能力的差异,探索福寿螺成功入侵的机制,以田螺为对照,测定了1—4龄的福寿螺和田螺的胃和肝脏的消化酶——纤维素酶(羧甲基纤维素法)、淀粉酶(3,5-二硝基水杨酸法)和脂肪酶(滴定法)的活性。结果表明:1)相同年龄的福寿螺胃和肝脏中的消化酶活性明显高于田螺。其中,纤维素酶活性分别高出1.00—2.11倍、1.66—2.84倍;淀粉酶活性分别高出1.53—3.47倍、1.47—1.80倍;脂肪酶活性分别高出2.07—4.73倍、6.13—9.93倍。2)在生长发育过程中,福寿螺胃和肝脏中的消化酶活性变化幅度(51.2%—131.2%)明显高于田螺(23.3%—47.1%)。3)福寿螺的各种消化酶之间存在协同作用。如福寿螺的淀粉酶活性与脂肪酶活性呈极显著正相关(胃中r=0.736**、肝脏中r=0.867**)。此外,胃中的淀粉酶活性还与纤维素酶活性呈显著正相关关系(r=0.696*)。相应地,田螺胃中的淀粉酶和脂肪酶之间也存在显著的正相关关系(r=0.706*),而肝脏中的纤维素酶与脂肪酶活性呈显著负相关(r=-0.593*)。4)福寿螺对纤维素类和淀粉类物质都有较强的消化能力,且能较好地消化脂肪类物质,而田螺能消化纤维素类和淀粉类物质,对脂肪的消化能力却很弱。福寿螺的纤维素酶和淀粉酶活性分别是田螺的2.42和1.88倍,脂肪酶活性达到了5.66倍。可见,福寿螺具有较高的消化酶活性,且各消化酶之间存在正协同性。这可能是导致福寿螺食量大、食性杂,使其能快速生长和成功入侵的重要原因之一。     

Growth and survival of juvenile Pomacea canaliculata (Gastropoda: Ampullariidae) in plain streams associated to different land uses

Pomacea canaliculata is an apple snail that has become an invasive species in several countries. In this research, through two simultaneous experiments, we assessed the effects of different land uses (urban, agriculture, cattle grazing, farms and recreation) on the growth and survival of snails from native populations. The survival was not affected by the water quality of the three streams studied, whereas the growth of snails exposed to the water of the urban stream was impaired. Therefore, our results suggest that the growth rate of P. canaliculata could be useful for the assessment of a moderate urban impact.     

Synthesis and biochemical evaluation of novel and potent inhibitors of the enzyme oestrone sulphatase (ES)

In an effort to investigate the structural requirements for the inhibition of the enzyme oestrone sulphatase (ES), we have previously undertaken extensive structure-activity relationship studies. Using the data from molecular modelling and structure–activity relationship determination studies, we have designed a number of compounds based upon 4-sulphamated phenyl ketones. Here, we report the results of our study into a series of these compounds as potential inhibitors of ES. The results of the study show that these compounds are potent inhibitors the possessing greater inhibitory activity than 4-methylcoumarin-7-O-sulphamate derivative (COUMATE) (a potent non-steroidal inhibitor), but are weaker than oestrone-3-sulphamate (EMATE) and the recently reported 667- and 669-COUMATE, however, they provide good lead compounds in the search for potent inhibitors of ES. Furthermore, the compounds are observed to be irreversible inhibitors. From the consideration of the structure-activity relationship of these novel compounds, we have attempted to rationalise the significance of the log P factor in the inhibition of ES and suggest that a log P requirement of approximately 3.5 aids the inhibition through the rapid expulsion of the carbon backbone from the active site. We also propose that the same factor is responsible for the hydrolysis of oestrone sulphate reaction, appearing to be an irreversible process.