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

Modulation of hepatic inflammation and energy-sensing pathways in the rat liver by high-fructose diet and chronic stress

Purpose High-fructose consumption and chronic stress are both associated with metabolic inflammation and insulin resistance. Recently, disturbed activity of energy sensor AMP-activated protein kinase (AMPK) was recognized as mediator between nutrient-induced stress and inflammation. Thus, we analyzed the effects of high-fructose diet, alone or in combination with chronic stress, on glucose homeostasis, inflammation and expression of energy sensing proteins in the rat liver. Methods In male Wistar rats exposed to 9-week 20% fructose diet and/or 4-week chronic unpredictable stress we measured plasma and hepatic corticosterone level, indicators of glucose homeostasis and lipid metabolism, hepatic inflammation (pro- and anti-inflammatory cytokine levels, Toll-like receptor 4, NLRP3, activation of NF kappa B, JNK and ERK pathways) and levels of energy-sensing proteins AMPK, SIRT1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha). Results High-fructose diet led to glucose intolerance, activation of NF kappa B and JNK pathways and increased intrahepatic IL-1 beta, TNF alpha and inhibitory phosphorylation of insulin receptor substrate 1 on Ser(307). It also decreased phospho-AMPK/AMPK ratio and increased SIRT1 expression. Stress alone increased plasma and hepatic corticosterone but did not influence glucose tolerance, nor hepatic inflammatory or energy-sensing proteins. After the combined treatment, hepatic corticosterone was increased, glucose tolerance remained preserved, while hepatic inflammation was partially prevented despite decreased AMPK activity. Conclusion High-fructose diet resulted in glucose intolerance, hepatic inflammation, decreased AMPK activity and reduced insulin sensitivity. Chronic stress alone did not exert such effects, but when applied together with high-fructose diet it could partially prevent fructose-induced inflammation, presumably due to increased hepatic glucocorticoids

Estudo soroepidemiológico da cisticercose humana em um município do Estado do Piauí, Região Nordeste do Brasil Seroepidemiological survey of human cysticercosis in a municipality of Piaui State, Northeast Brazil

Integrando as pesquisas sobre parasitoses na região do entorno do Parque Nacional Serra da Capivara, Piauí, Brasil, realizadas entre 1999 e 2001, o presente estudo tem como objetivo avaliar a situação epidemiológica da cisticercose humana no Município de João Costa, no Nordeste do Brasil. Foram obtidas informações clínico-epidemiológicas e coletadas amostras de sangue para testes sorológicos imunoenzimáticos (ELISA e Western blot), empregando cisticercos de Taenia crassiceps como antígeno. Na primeira etapa, em 1999, foram investigadas 169 pessoas com história confirmada ou suspeita de infecção/doença pelo complexo teníase-cisticercose, e seus familiares. Na análise, 13,6% das pessoas apresentaram soros reagentes para cisticercose pelo método ELISA. Na segunda etapa, em 2001, foram avaliadas 92 amostras de soro de indivíduos reativos para cisticercose detectados no primeiro momento e seus familiares, sendo que 24,0% das amostras de soro foram reagentes para cisticercose pelo ELISA, e 29,0%, pelo WB. Nessa mesma etapa, realizou-se inquérito coprológico em 701 pessoas, incluindo voluntários. A prevalência de parasitoses intestinais foi de 51,0%, tendo sido observada uma maior prevalência de protozoários (95,0%) em relação aos helmintos (5,0%). Os resultados do estudo indicam o caráter endêmico da cisticercose na área, além da elevada freqüência de protozooses intestinais.<br>As part of parasitological studies in the area surrounding the Serra da Capivara National Park, Piauí State, Northeast Brazil, from 1999 to 2001, the current study aimed to evaluate the epidemiological profile of human cysticercosis in the Municipality of João Costa. Clinical and epidemiological data were obtained, and blood samples were drawn for immunoenzymatic serological tests (ELISA and Western blot), using Taenia crassiceps as the antigen. The first stage, in 1999, investigated 169 individuals with a confirmed history or suspicion of infection/disease involving the teniasis/cysticercosis complex, along with the family members. Some 13.6% of the individuals were seroreactive for cysticercosis by the ELISA method. The second stage, in 2001, evaluated 92 serum samples of individuals who had been detected as reactive for cysticercosis in the first stage, along with their family members; 24% of the samples were reactive to cysticercosis by ELISA and 29% by Western blot. During this same stage a coprological survey was performed with 701 individuals, including volunteers. Prevalence of intestinal parasites was 51%, with a higher prevalence of protozoans (95%) than helminths (5%). The results indicate the endemicity of cysticercosis in the area, in addition to the high frequency of intestinal protozoan infections