The Role of the Proteinase Inhibitor Ovorubin in Apple Snail Eggs Resembles Plant Embryo Defense against Predation

BACKGROUND: Fieldwork has thoroughly established that most eggs are intensely predated. Among the few exceptions are the aerial egg clutches from the aquatic snail Pomacea canaliculata which have virtually no predators. Its defenses are advertised by the pigmented ovorubin perivitellin providing a conspicuous reddish coloration. The nature of the defense however, was not clear, except for a screening for defenses that identified a neurotoxic perivitellin with lethal effect on rodents. Ovorubin is a proteinase inhibitor (PI) whose role to protect against pathogens was taken for granted, according to the prevailing assumption. Through biochemical, biophysical and feeding experiments we studied the proteinase inhibitor function of ovorubin in egg defenses. METHODOLOGY/PRINCIPAL FINDINGS: Mass spectrometry sequencing indicated ovorubin belongs to the Kunitz-type serine proteinase inhibitor family. It specifically binds trypsin as determined by small angle X-ray scattering (SAXS) and cross-linking studies but, in contrast to the classical assumption, it does not prevent bacterial growth. Ovorubin was found extremely resistant to in vitro gastrointestinal proteolysis. Moreover feeding studies showed that ovorubin ingestion diminishes growth rate in rats indicating that this highly stable PI is capable of surviving passage through the gastrointestinal tract in a biologically active form. CONCLUSIONS: To our knowledge, this is the first direct evidence of the interaction of an egg PI with a digestive protease of potential predators, limiting predator's ability to digest egg nutrients. This role has not been reported in the animal kingdom but it is similar to plant defenses against herbivory. Further, this would be the only defense model with no trade-offs between conspicuousness and noxiousness by encoding into the same molecule both the aposematic warning signal and an antinutritive/antidigestive defense. These defenses, combined with a neurotoxin and probably unpalatable factors would explain the near absence of predators, opening new perspectives in the study of the evolution and ecology of egg defensive strategies

Distribution of Corbicula fluminea (Müller, 1774) in the invaded range: a geographic approach with notes on species traits variability

Corbicula fluminea is considered one of the most important non-native invasive species (NIS) in aquatic systems mainly due to its widespread distribution and ecological and economic impacts. This species is known to negatively affect native bivalves, also with severe effects on biodiversity and ecosystem functioning. Throughout an exhaustive bibliographic survey and with the aid of Geographic Information Systems tools, this study tracks the species dispersion from its native range, including the description of important physical and environmental barriers. Additional analyses were conducted to examine possible influences of latitudinal/ temperature gradients on important traits (e.g. life span, maximum and mean body length, growth at the end of first year). Altitude and winter minimum temperature appear to be delaying the invasion worldwide, but it seems inevitable that the species will spread across the globe. Latitude and summer temperature show a relationship with growth and life span. Overall, the information gathered in this review may be relevant to forecast future distribution patterns of this NIS, and to anticipate the possible implementation of effective management measures. Moreover, it may constitute a valuabletool inthe prediction of population responses to an increasingly changing environment.This research was supported by FCT (Portuguese Foundation for Science and Technology), through a PhD grant attributed to D. Crespo (SFRH/BD/80252/2011), a post-doc grant attributed to S. Leston (SFRH/BPD/91828/2012) and M Dolbeth (SFRH/BPD/41117/2007) and BIOCHANGED project (PTDC/MAR/111901/2009), subsidized by the European Social Fund and MCTES (Ministério da Ciência, Tecnologia e Ensino Superior) National Funds, through the POPH (Human Potential Operational Programme), QREN (National Strategic Reference Framework) and COMPETE (Programa Operacional Factores de Competitividade).info:eu-repo/semantics/publishedVersio

Distribuição sazonal e reprodução de Neocorbicula limosa (Maton) (Bivalvia, Corbiculidae) no Lago Guaíba, Rio Grande do Sul, Brasil Seasonal distribution and reproduction of Neocorbicula limosa (Maton) (Bivalvia, Corbiculidae) in the Guaíba Lake, Rio Grande do Sul, Brazil

<abstract language="eng">Neocorbicula limosa (Maton, 1811) is the only species of that South American genus that occurs in the hydrographic basins of Rio Grande do Sul State, Brazil. Seasonal quantitative collections between 1995 and 1996 in the lake Guaiba were accomplished, with the aim to know the reproductive dynamics and environmental preferences of populations of N. limosa. A substratum constituted by medium to coarse sands at an 'average depth around 2m shown to be favorable to installation of population of N. limosa. The largest population density (2.496 ind./m²) was registered in summer. Embryos at various development phases were registered inside individuals. The shell sizes of these individuals started from 8mm in length. The embryo's size could reach ¼ of the shell-mother's size, and their liberation occurs through the rupture of the gills

Bivalve distribution in hydrographic regions in South America: historical overview and conservation

Based on literature review and malacological collections, 168 native freshwater bivalve and five invasive species have been recorded for 52 hydrographic regions in South America. The higher species richness has been detected in the South Atlantic, Uruguay, Paraguay, and Amazon Brazilian hydrographic regions. Presence or absence data were analysed by Principal Coordinate for PhylogenyWeighted. The lineage Veneroida was more representative in hydrographic regions that are poorer in species and located West of South America. The Mycetopodidae and Hyriidae lineages were predominant in regions that are richest in species toward the East of the continent. The distribution of invasive speciesLimnoperna fortuneiis not related to species richness in different hydrographic regions there. The species richness and its distribution patterns are closely associated with the geological history of the continent. The hydrographic regions present distinct phylogenetic and species composition regardless of the level of richness. Therefore, not only should the richness be considered to be a criterion for prioritizing areas for conservation, but also the phylogenetic diversity of communities engaged in services and functional aspects relevant to ecosystem maintenance. A plan to the management of this fauna according to particular ecological characteristics and human uses of hydrographic regions is neededFil: Pereira, Daniel . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Dreher Mansur, Maria Cristina . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Duarte, Leandro D. S. . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Schramm de Oliveira, Arthur . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Mansur Pimpao, Daniel . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Tasso Callil, Claudia . Universidade Federal Do Mato Grosso Do Sul; BrasilFil: Ituarte, Cristian Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: Parada, Esperanza . Plataforma de Investigación en Ecohidrología y Ecohidráulica (ECOHYD); ChileFil: Peredo, Santiago . Plataforma de Investigación en Ecohidrología y Ecohidráulica (ECOHYD); ChileFil: Darrigran, Gustavo Alberto. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Div.zoologia Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Scarabino, Fabrizio . Museo Nacional de Historia Natural; UruguayFil: Clavijo, Cristhian. Museo Nacional de Historia Natural; UruguayFil: Lara, Gladys . Universidad Católica de Temuco; ChileFil: Miyahira, Igor Christo . Universidade do Estado do Rio de Janeiro; BrasilFil: Raya Rodriguez, Maria Teresa . Universidade Federal Do Rio Grande Do Sul; BrasilFil: Lasso, Carlos . Instituto de Investigacion de Recursos Biologicos Alexander von Humboldt; Colombi