ABSTRACT
Lipids in avocados have been widely studied due to their nutritional value and several reported bioactivities. Aliphatic acetogenins are a relevant component of the avocado lipidome and have been tested for several potential food and pharma industries applications. This work followed the evolution of avocado fatty acids (FAs) and aliphatic acetogenins during seed germination and leaf growth. Oil extracts of embryonic axes, cotyledons, and leaves from seedlings and trees were divided to analyze free acetylated acetogenins (AcO-acetogenins), and free FAs. Embryonic axes from germinating seeds contained the highest amount of AcO-acetogenins and FAs; this tissue also accumulated the most diverse FA profile with up to 22 detected moieties. Leaves presented the highest variations in AcO-acetogenin profiles during development, although leaves from seedlings accumulated the simplest FA profile with only 10 different FAs. Remarkably, AcO-acetogenins represented half of the carbons allocated to lipids in grown leaves, while embryonic axes and cotyledons always contained more carbons within FAs during germination. Thus, we hypothesized the use of the AcO-acetogenin acyl chain for energy production toward ß-oxidation. Also, α-linolenic and docosahexaenoic acids (DHAs) were proposed as close AcO-acetogenin intermediaries based on a correlation network generated using all these data. Another part of the oil extract was fractionated into different lipid classes before transesterification to profile FAs and acetogenins bound to lipids. Acetogenin backbones were identified for the first time in triglycerides from cotyledons and mainly in polar lipids (which include phospholipids) in all developing avocado tissues analyzed. Seed tissues accumulated preferentially polar lipids during germination, while triglycerides were consumed in cotyledons. Seedling leaves contained minute amounts of triglycerides, and polar lipids increased as they developed. Results from this work suggest acetogenins might be part of the energy and signaling metabolisms, and possibly of membrane structures, underlining the yet to establish role(s) of these unusual lipids in the avocado plant physiology.
ABSTRACT
We previously reported that the Trichinella nematode showed higher parasite loads in one gender than another, but also the parasite molting rate decreased when it was cultivated in the presence of progesterone. In this study we explored the hypothesis that the direct effect of progesterone on Trichinella spiralis could be mediated by a steroid-binding parasite protein. We sequenced, cloned and amplified the Cyt-domain of the progesterone receptor membrane component-2 of Trichinella spiralis (PGRMC2-Ts). Furthermore, we expressed the protein and developed an antibody to perform confocal microscopy and flow cytometry. The expression of the PGRMC2-Ts protein was exclusively detected at the oocyte and the parasite's cuticle in cross-sections of the parasite, and this expression was confirmed by western blot and flow cytometry. Molecular modeling studies and computer docking for the PGRMC2-Ts protein showed that it is potentially able to bind to progesterone, estradiol, testosterone, and dihydrotestosterone with different affinities. Furthermore, phylogenetic analysis demonstrated that T. spiralis PGRMC2 is related to a steroid-binding protein of another platyhelminth. Progesterone probably acts upon Trichinella spiralis oocytes by binding to PGRMC2-Ts. Our data showed that the PGRMC2-Ts protein is present in the parasite's oocytes, a development step that is crucial for the life cycle of the parasite. Indeed, this research might have implications in the field of host-parasite co-evolution and the sex-associated susceptibility to this infection. In a more practical matter, these results may contribute to the design of new drugs with anti-parasite effects.
