Variability of imposex development and reproductive alterations in the Patagonian gastropod Buccinanops globulosus inhabiting a polluted harbour area

El objetivo de este trabajo fue estudiar parámetros reproductivos y desarrollo de imposex en el caenogasterópodo Buccinanops globulosus que habita en una zona portuaria de alto tráfico marítimo y con presencia de contaminantes. Los resultados mostraron una mayor incidencia de imposex en hembras sin ovicápsulas que en hembras con ovicápsulas. Entre las hembras con imposex, el desarrollo del pene fue significativamente mayor en aquellas sin ovicápsulas (3.4 mm) que en las hembras con ovicápsulas (1,5 mm). En B. globulosus comúnmente un solo juvenil eclosiona por cada cápsula, sin embargo, en este estudio se registraron capsulas con múltiples embriones. Todos estos resultados sugieren una relación entre el desarrollo de imposex y alteraciones en los parámetros reproductivos de las hembras de B. globulosus que habitan en sitios con condiciones ambientales adversas (área contaminada).The aim of this work was to study the reproductive output and imposex parameters of the caenogastropod Buccinanops globulosus inhabiting a harbour area, with high maritime traffic and pollution. The results showed higher imposex incidence for non-gravid females than for gravid females (carrying egg capsules). Among imposex-affected females, mean penis size was significantly larger in non-gravid (3.4 mm) than gravid (1.5 mm) females. In B. globulosus usually a single juvenile hatches per egg capsule, but in this study capsules with multiple embryos were found. Overall, these results suggest a relationship between imposex development and alterations on the reproductive output of B. globulosus females living in adverse environmental conditions (polluted area).Fil: Primost, Monica Angelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentin

Synoptic review of the Literature on the southern oyster drill Thais haemastoma floridana

This literature search identifies a majority of the publications in the period 1880-1980 concerned with the marine gastropod, Thais haemastomafloridmul (Conrad). The southern oyster drill is an economically important oyster predator in the western Atlantic and Gulf of Mexico littoral. Major contributions of each paper to our knowledge of the drill's biology are briefly categorized. Hitherto unpublished research by the author on the snail's biology is documented. (PDF file contains 15 pages.

Invertebrate Zooid Polymorphism: Hydractinia Polyclina And Pagurus Longicarpus Interactions Mediated Through Spiralzooids

Evaluating the net interaction between symbionts can be challenging when one participant is a colonial animal with polymorphic zooids, because each zooid type has unique functions. The colonial hydroid Hydractinia polyclina has three distinct zooid types, each of which contributes particular components to the interaction with host hermit crabs. Of these three zooid types, the function of spiralzooids is not well understood. Previously, spiralzooids have been proposed to contribute a strong negative interaction component by directly reducing their host hermit crab’s reproductive output. However, this hypothesis is not supported by past or current data. I propose that spiralzooids instead function to prevent hosts from foraging on the colonies in their own shells. I conducted a series of experiments and surveys that explored spiralzooid distribution, structure, and function. Spiralzooid distribution at the species level was quantified through an examination of the scientific literature, which documented that spiralzooids only form in colonies living on hermit crab occupied gastropod shells, regardless of crab species or geographic region. Within the local species H. polyclina, only colonies that were living on gastropod shells occupied by hermit crabs contained spiralzooids, regardless of collection site or colony gender. Next, I assessed spiralzooid structure. Spiralzooids had a mean length of 1.17 ± 0.62mm and occurred at a mean density of 1.91 ± 1.03 per mm2 along the aperture edge. Spiralzooids contain microbasic eurytele nematocysts, organized into nematocyst batteries, and battery abundance at zooid tips can be categorized into four levels. These nematocyst batteries adhered to hermit crab bodies and appendages, and adherence did not vary significantly among body parts. Spiralzooid function was studied through several experiments. Increased hermit crab contact and the presence of a host stimulated spiralzooid formation throughout a shell, in parts of the colony that are normally devoid of spiralzooids. Although hermit crabs are active scavengers, those that are symbiotic with H. polyclina have never been documented consuming their own epibiont colonies. Yet, hermit crabs are commonly observed feeding on polyps in colonies on other shells. If spiralzooids prevent crabs from foraging on the colonies on their own shells, then crabs should respond to contact with spiralzooids. The act of spiralzooid lashing, as tested by probing hydroid covered shells (with a bare shell control), significantly altered hermit crab behavior. Six crab behaviors were in turn analyzed to determine their effects on initiating spiralzooid lashing. Foraging on H. polyclina stimulating spiralzooid lashing significantly more frequently than other hermit crab behaviors. Lastly, hermit crab prey caloric values compiled from the literature were compared to the empirically determined caloric value for H. polyclina (4,011.55 ± 65.47 cal/g dry wt); hydroids ranked in the top 10% of potential hermit crab prey. In light of these findings I suggest the data support my guiding hypothesis that spiralzooids prevent hosts from foraging on their own colonies. Under this proposed function, I suggest that gonozooids actually contribute a weak positive interaction with the host crab by potentially providing caloric value, and spiralzooids in turn contribute a weak negative interaction. Therefore, the resulting net interaction between H. polyclina and Pagurus longicarpus should be considered commensal, or weakly mutualistic

Apple snail perivitellin precursor properties help explain predatorsï feeding behavior

Fil: Cadierno, María Pilar. Universidad Nacional de La Plata. Instituto de Investigaciones Bioquímicas de La Plata; ArgentinaFil: Dreon, Marcos Sebastián. Universidad Nacional de La Plata. Instituto de Investigaciones Bioquímicas de La Plata; ArgentinaFil: Heras, Horacio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Química Biológica; Argentin

Pond Snail Reproduction as Model in the Environmental Risk Assessment: Reality and Doubts

In European limnetic systems, the most relevant endocrine-disrupting chemicals (EDCs) of steroid type are the natural and synthetic hormones, phytosterols, pesticides, biocides and other chemicals produced by the plastic industry. Their presence in aquatic ecosystems represents a potentially adverse environmental and public health impact. Furthermore, this is a warning signal that the current handling of pharmaceuticals needs to be further improved. Nowadays, it has become clear that EDCs have specific disturbing effects on the neuroendocrine system of invertebrate and vertebrate aquatic animals, particularly gastropods. Among a latter, pond snail (Lymnaea stagnalis) has been used as the first aquatic non-arthropod test organism in studying the effect of EDCs because they are sensitive to various anthropogenic steroids, like progestogens. Investigating a variety of reproductive endpoints of Lymnaea, such as fecundity, oocyte production, egg mass production, the quality of egg masses, the shell size in development and after egg-laying, the time window of cell division in the offspring, the metabolite content of single-cell zygotes and egg albumen has concluded that progestogen contaminations in water are detrimental for reproduction and early stage development of Lymnaea. This chapter is an attempt to show whether Lymnaea reproduction, despite many altering reproductive endpoints, is a suitable model for environmental risk assessment or not

Apple Snail Perivitellin Precursor Properties Help Explain Predators’ Feeding Behavior

In contrast with vitellogenin maturation, it is unknown whether gastropod perivitellin precursors are subject to large structural changes. The gastropod reproductive tract includes an accessory organ, the albumen gland (AG), that produces and secretes perivitelline fluid. In the apple snail Pomacea canaliculata, the large, reddish-pink AG provides eggs with perivitellins that are defensive against predators. Although the AG makes a considerable contribution to apple snail biomass, field observations indicate that it is rejected by avian and mammalian predators, although the underlying reason remains unknown. By analyzing the structure-function properties of P. canaliculata perivitellin precursors, we provide insight into perivitellin maturation and its relationship with apple snail predator feeding behavior. Structural analysis using small-angle X-ray scattering, absorption and fluorescence spectroscopy, circular dichroism, electrophoresis, chromatography, and partial proteolysis showed that the size, shape, and structure of perivitellin precursors resemble those of egg mature forms. Functional analysis indicates that the precursors of the defensive perivitellins ovorubin (PcOvo) and perivitellin-2 (PcPV2) are highly stable and antinutritive, withstanding proteinase digestion and displaying structural stability of their quaternary structure under a wide pH range (4.0–10.0). Furthermore, AG extracts limit a predator’s ability to digest nutrients and are toxic to mice (median lethal concentration 96 h after administration: 5.9 mg/kg). Treated mice displayed neurologic signs similar to those produced by egg PcPV2. Results indicate that apple snails store active precursors of egg proteins inside the AG, providing evidence that gastropod perivitellin precursors do not experience the large structural processing of invertebrate vitellogenin maturation. These defensive proteins provide the apple snail AG with neurotoxic, antinutritive, and antidigestive activity, a likely explanation for the predators’ feeding behavior.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias Naturales y Muse

Apple Snail Perivitellin Precursor Properties Help Explain Predators’ Feeding Behavior

In contrast with vitellogenin maturation, it is unknown whether gastropod perivitellin precursors are subject to large structural changes. The gastropod reproductive tract includes an accessory organ, the albumen gland (AG), that produces and secretes perivitelline fluid. In the apple snail Pomacea canaliculata, the large, reddish-pink AG provides eggs with perivitellins that are defensive against predators. Although the AG makes a considerable contribution to apple snail biomass, field observations indicate that it is rejected by avian and mammalian predators, although the underlying reason remains unknown. By analyzing the structure-function properties of P. canaliculata perivitellin precursors, we provide insight into perivitellin maturation and its relationship with apple snail predator feeding behavior. Structural analysis using small-angle X-ray scattering, absorption and fluorescence spectroscopy, circular dichroism, electrophoresis, chromatography, and partial proteolysis showed that the size, shape, and structure of perivitellin precursors resemble those of egg mature forms. Functional analysis indicates that the precursors of the defensive perivitellins ovorubin (PcOvo) and perivitellin-2 (PcPV2) are highly stable and antinutritive, withstanding proteinase digestion and displaying structural stability of their quaternary structure under a wide pH range (4.0–10.0). Furthermore, AG extracts limit a predator’s ability to digest nutrients and are toxic to mice (median lethal concentration 96 h after administration: 5.9 mg/kg). Treated mice displayed neurologic signs similar to those produced by egg PcPV2. Results indicate that apple snails store active precursors of egg proteins inside the AG, providing evidence that gastropod perivitellin precursors do not experience the large structural processing of invertebrate vitellogenin maturation. These defensive proteins provide the apple snail AG with neurotoxic, antinutritive, and antidigestive activity, a likely explanation for the predators’ feeding behavior.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias Naturales y Muse

A foam model highlights the differences of the macro- and microrheology of respiratory horse mucus

Native horse mucus is characterized with micro- and macrorheology and compared to hydroxyethylcellulose (HEC) gel as a model. Both systems show comparable viscoelastic properties on the microscale and for the HEC the macrorheology is in good agreement with the microrheology. For the mucus, the viscoelastic moduli on the macroscale are several orders of magnitude larger than on the microscale. Large amplitude oscillatory shear experiments show that the mucus responds nonlinearly at much smaller deformations than HEC. This behavior fosters the assumption that the mucus has a foam like structure on the microscale compared to the typical mesh like structure of the HEC, a model that is supported by cryogenic-scanning-electron-microscopy (CSEM) images. These images allow also to determine the relative amount of volume that is occupied by the pores and the scaffold. Consequently, we can estimate the elastic modulus of the scaffold. We conclude that this particular foam like microstructure should be considered as a key factor for the transport of particulate matter which plays a central role in mucus function with respect to particle penetration. The mesh properties composed of very different components are responsible for macroscopic and microscopic behavior being part of particles fate after landing.Comment: Accepted for publication in the Journal of the Mechanical Behavior of Biomedical Material