The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly

In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling in aposematism is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments directly responsible for colouration and in protecting against oxidative lipid damage. Here we study a model aposematic system - the monarch butterfly (Danaus plexippus) and make use of the variable phytochemistry of its larval host-plant, milkweeds (Asclepiadaceae), to manipulate the concentration of sequestered cardenolides. We test two fundamental assumptions of resource competition models: that (1) the possession of secondary defences is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (2) that oxidative damage or decreases in antioxidant defences can reduce the capacity of individuals to produce aposematic displays. Monarch caterpillars that sequestered the highest concentrations of cardenolides exhibited higher levels of oxidative lipid damage as adults. The relationship between warning signals, cardenolide concentrations and oxidative damage differed between the sexes. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: as males sequester more cardenolides, those with high levels of oxidative damage become less conspicuous, while those that sequester lower levels of cardenolides equally invest in conspicuous with increasing oxidative damage. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate physiological linkage between the production of coloration and protection from autotoxicity, that warning signals can be honest indicators of defensive capability, and that the relationships are different between the sexes.

Fatty Dihydropyridines With Anti-Hypertensive and Cardioprotective Potential During Ischemia and Reperfusion

In this study, three fatty dihydropyridines, were tested for their anti-hypertensive and cardioprotective properties. Dihydropyridines 2c, 8c, and 9a contain the oleic chain and the nitro unit, the oleic chain and the chlorine unit, and the palmitic chain and the chlorine unit, respectively. For the experiments, animals were treated with N(ω)-nitro-L-arginine methyl ester to induce hypertension and after treated with the new dihydropyridine compounds and the standard drug nifedipine. Then, the heart was removed and subjected to global ischemia and reperfusion. Analyses of cardiac parameters were performed to monitor cardiac functionality; lactate dehydrogenase values were quantified in perfusates. After ischemia and reperfusion were performed, analyses to check the oxidative status and lipid damage. The results of the present study suggest that the new fatty DHPs have anti-hypertensive effects offering protection against ischemia to the heart of rats, accomplished by increasing antioxidants that defend and prevent the decline in cardiac function.

Neurotoxicity mechanism of Ochratoxin A

Mycotoxins, such as Ochratoxins, are widely distributed in nature and are common contaminants of human foodstuffs. Ochratoxins are a group of mycotoxins produced by a wide range of molds. Ochratoxin A (OTA), the most prominent member of this toxin family, is produced by various Aspergillus and Penicillium species. OTA is frequently found in foods such as cereals, oleaginous seeds, coffee, and meat products. This mycotoxin has been described as teratogenic, genotoxic, carcinogenic, and immunotoxic, and has been proven to be a potent neurotoxin. In the present study, the neurotoxicological perspective of OTA was reviewed and discussed. The main possible mechanisms of neurotoxicity are oxidative DNA, protein and lipid damage, and apoptosis. However, further studies are needed to conclude the exact neurotoxicity mechanism of OTA and find the approaches that reduce the neurotoxicity induced by OTA.

Implication of total replacement of fish oil with vegetable oils on nutritional and lipid profiles of fish

In this study, the effects of using vegetable oils solely in finfish feed on nutritional status as well as lipid damage were evaluated. Polyene index (PI), atherogenic index (AI) as well as hypocholesterolemic and hypercholesterolemic fatty acids were assessed. Also, n-3/n-6 and n-6/n-3 ratios were assessed. In all, 32 articles were used for this study after carefully assessing them. Eighteen (18) articles had studied Freshwater species (FWF) whiles fourteen (14) had studied Marine species (MF). TI, n-3/n-6, and n-6/n-3 were significantly higher in fish-fed saturated fatty acids (SFA), n-3, and n-6 dominant vegetables. We document that using vegetable oils without supplementing fish diets with fish oil does not compromise the nutritional status as well as lipid damage. This work provides important information about the effect of using 100% vegetable oils in fish with respect to the nutritional composition of the final product.

Plasma Concentration of Advanced Glycation End-Products From Wild Canids and Domestic Dogs Does Not Change With Age or Across Body Masses

Dogs provide a physiological paradox: In domestic dogs, small breeds live longer lives than large breed dogs. Comparatively, a wild canid can be a similar size than many large breed dogs and outlive their domestic cousin. We have previously shown that oxidative stress patterns between domestic and wild canids differ, so that wild canids invest in a robust antioxidant system across their lives; whereas domestic dogs tend to accumulate lipid damage with age. There is a close association between oxidative stress and the production of a carbohydrate based-damage, Advanced Glycation End-products (AGEs). AGEs can bind to their receptor (RAGE), which can lead to increases in reactive oxygen species (ROS) production, and decreases in antioxidant capacity. Here, I used plasma from wild and domestic canids to address whether blood plasma AGE-BSA concentration associated with body mass and age in domestic dogs; And whether AGE-BSA concentration patterns in blood plasma from wild canids are similar to those found in domestic dogs. I found no correlation between circulating AGE-BSA concentration and body size or age in either domestic dogs and wild canids. These data suggest that AGEs formation may be a conserved trait across the evolution of domesticated dogs from wild ancestors, in opposition to oxidative stress patterns between these two groups. And, that, in domestic dogs, lipid metabolism, rather than carbohydrate metabolism, may be upregulated to yield the previously found differences in circulating lipid damage across lifespan and body sizes.

Untangling life span and body mass discrepancies in canids: phylogenetic comparison of oxidative stress in blood from domestic dogs and wild canids

Canids are a morphological and physiological diverse group of animals, with the most diversity found within one species, the domestic dog. Underlying observed morphological differences, there must also be differences at other levels of organization that could lead to elucidating aging rates and life span disparities between wild and domestic canids. Furthermore, small-breed dogs live significantly longer lives than large-breed dogs, while having higher mass-specific metabolic rates and faster growth rates. At the cellular level, a clear mechanism underlying whole animal traits has not been fully elucidated, although oxidative stress has been implicated as a potential culprit of the disparate life spans of domestic dogs. We used plasma and red blood cells from known aged domestic dogs and wild canids, and measured several oxidative stress variables: total antioxidant capacity (TAC), lipid damage, and enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase (GPx). We used phylogenetically informed general linear mixed models and nonphylogenetically corrected linear regression analysis. We found that lipid damage increases with age in domestic dogs, whereas TAC increases with age and TAC and GPx activity increases as a function of age/maximum life span in wild canids, which may partly explain longer potential life spans in wolves. As body mass increases, TAC and GPx activity increase in wild canids, but not domestic dogs, highlighting that artificial selection may have decreased antioxidant capacity in domestic dogs. We found that small-breed dogs have significantly higher circulating lipid damage compared with large-breed dogs, concomitant to their high mass-specific metabolism and higher growth rates, but in opposition to their long life spans.