The experiment lasted 7 days and were performed two intraperitoneal injections with saline buffer (control) or bacterial endotoxin from Escherichiacoli (lipopolysaccharide, LPS) at day 0 and day 2. After 5 days from the second injection, the fish were euthanatized, and plasma and two immune tissues (liver and head-kidney) were collected.The principal findings showed that the average plasma Fe2+ ion concentration was unaffected by treatment in any of the species. However, the gene expression response to LPS varied between tissues and species, being stronger in N.coriiceps and more prominent in the head-kidney than liver. The reaction to LPS was marked by increased individual variability in most genes analyzed, even when the change in expression was not statistically significant, suggesting different individual sensitivity and coping responses in these wild fish.ens.

Authors also found that iron related genes had an attenuated and homogenous response to LPS but there was no detectable relationship between plasma Fe2+ ion and gene expression. As conclusion, in both tissues and species LPS exposure set a multilevel response that concur to promote intracellular accumulation of iron, an indication that Antarctic Notothenoids use innate nutritional immunity as a resistance mechanism against pathogens.

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Source: Martínez, D. P., Sousa, C., Oyarzún, R., Pontigo, J. P., Canario, A. V. M., Power, D. M., et al. (2020). LPS Modulates the Expression of Iron-Related Immune Genes in Two Antarctic Notothenoids. Front. Physiol. 11, 102. DOI: 10.3389/fphys.2020.00102

Author: Cármen Sousa

The venom of the octopus, present on the saliva, is one of the tools that this organism uses to interact with the ecosystem. This venom is produced on the salivary glands (Fig. 1) and is composed by cephalotoxins (Ctx), a combination of proteins with the capacity to inhibit blood coagulation, to paralyze and partially digest externally prey. Among octopus species, the differences registered on venom’s chemical composition and venom’s apparatus suggest that there is an evolutive mechanism strongly dependent on the venom’s importance for the feeding ecology of the species (e.g. prey preference, preying strategies, etc.).

Generally, the venom’s enzymes present an optimal activity at temperatures surrounding 30 °C, dropping rapidly at temperatures below 10-20 °C. Therefore, studying the venom of Antarctic octopus species, where the water temperature is close to 0°C, is a unique opportunity to understand how the venom evolved adapting to the extreme environmental conditions and its importance to the ecology of the species.

Besides evolutionary and ecological studies, molecular biology research may provide crucial insights regarding chemical properties of certain compounds that may have potentially valuable applications on areas, such as Pharmacology.

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Source: Undheim, E. A. B., Georgieva, D. N., Thoen, H. H., Norman, J. A., Mork, J., Betzel, C., & Fry, B. G. (2010). Venom on ice: First insights into Antarctic octopus venoms. Toxicon, 56, 897–913. https://doi.org/10.1016/j.toxicon.2010.06.013

Author: Ricardo Matias