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Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds.

ABSTRACT: Two bolaamphiphilic compounds with identical acetylcholine (ACh) head groups, but with different lengths of an alkyl chain pendant adjacent to the head group, as well as differences between their hydrophobic skeleton, were investigated for their ability to self-assemble into vesicles that release their encapsulated content upon hydrolysis of their head groups by acetylcholinesterase (AChE). One of these bolaamphiphiles, synthesized from vernolic acid, has an alkyl chain pendant of five methylene groups, while the other, synthesized from oleic acid, has an alkyl chain pendant of eight methylene groups. Both bolaamphiphiles formed stable spherical vesicles with a diameter of about 130 nm. The ACh head groups of both bolaamphiphiles were hydrolyzed by AChE, but the hydrolysis rate was significantly faster for the bolaamphiphile with the shorter aliphatic chain pendant. Likewise, upon exposure to AChE, vesicles made from the bolaamphiphile with the shorter alkyl chain pendant released their encapsulated content faster than vesicles made from the bolaamphiphile with the longer alkyl chain pendant. Our results suggest that the steric environment around the ACh head group of bolaamphiphiles is a major factor affecting the hydrolysis rate of the head groups by AChE. Attaching an alkyl chain to the bolaamphiphile near the ACh head group allows self-assembled vesicles to form with a controlled release rate of the encapsulated materials, whereas shorter alkyl chains enable a faster head group hydrolysis, and consequently faster release, than longer alkyl chains. This principle may be implemented in the design of bolaamphiphiles for the formation of vesicles for drug delivery with desired controlled release rates.

SUBMITTER: Stern A

PROVIDER: S-EPMC3901739 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds.

Stern Avital A Guidotti Matteo M Shaubi Eleonora E Popov Mary M Linder Charles C Heldman Eliahu E Grinberg Sarina S

International journal of nanomedicine 20140120

Two bolaamphiphilic compounds with identical acetylcholine (ACh) head groups, but with different lengths of an alkyl chain pendant adjacent to the head group, as well as differences between their hydrophobic skeleton, were investigated for their ability to self-assemble into vesicles that release their encapsulated content upon hydrolysis of their head groups by acetylcholinesterase (AChE). One of these bolaamphiphiles, synthesized from vernolic acid, has an alkyl chain pendant of five methylene ...[more]

PMID: 24531296

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Project description:BACKGROUND: The cytochrome P450 aromatase (CYP19), catalyses the aromatisation of androgens to estrogens, a key mechanism in vertebrate reproductive physiology. A current evolutionary hypothesis suggests that CYP19 gene arose at the origin of vertebrates, given that it has not been found outside this clade. The human CYP19 gene is located in one of the proposed MHC-paralogon regions (HSA15q). At present it is unclear whether this genomic location is ancestral (which would suggest an invertebrate origin for CYP19) or derived (genomic location with no evolutionary meaning). The distinction between these possibilities should help to clarify the timing of the CYP19 emergence and which taxa should be investigated. RESULTS: Here we determine the "genomic environment" around CYP19 in three vertebrate species Homo sapiens, Tetraodon nigroviridis and Xenopus tropicalis. Paralogy studies and phylogenetic analysis of six gene families suggests that the CYP19 gene region was structured through "en bloc" genomic duplication (as part of the MHC-paralogon formation). Four gene families have specifically duplicated in the vertebrate lineage. Moreover, the mapping location of the different paralogues is consistent with a model of "en bloc" duplication. Furthermore, we also determine that this region has retained the same gene content since the divergence of Actinopterygii and Tetrapods. A single inversion in gene order has taken place, probably in the mammalian lineage. Finally, we describe the first invertebrate CYP19 sequence, from Branchiostoma floridae. CONCLUSION: Contrary to previous suggestions, our data indicates an invertebrate origin for the aromatase gene, given the striking conservation pattern in both gene order and gene content, and the presence of aromatase in amphioxus. We propose that CYP19 duplicated in the vertebrate lineage to yield four paralogues, followed by the subsequent loss of all but one gene in vertebrate evolution. Finally, we suggest that agnathans and lophotrocozoan protostomes should be investigated for the presence of aromatase.

Project description:People's characteristics can affect their perception of the physical environment, and the judgments and estimates they make about their surroundings. Estimates of the environment change based on observers' metabolic state, physical properties, and the potential effort they would need to exert for a certain action. The functional role of such scaling is to provide agents with information on possible actions and their energetic costs. Combining actions with costs facilitates both higher-level planning (e.g., choosing an optimal running speed on a marathon) as well as planning on lower levels of an action hierarchy, such as determining the best movement trajectories for energy-efficient action. Recently, some of the findings on reported effects of effort on perception have been challenged as arising from task demands-participants guessing the purpose of the experimental manipulation and adjusting their estimates as a result. Arguably however, the failed replications used overly distracting cover stories which may have introduced task demands of their own, and masked other effects. The current study tested the generality of effects of potential effort on height and distance perception, employing effective yet not distracting cover stories. Four experiments attempted to identify conditions under which anticipated effort may systematically change perceptual estimates. Experiment 1 found that height estimates were not influenced by the effort required to place objects of different weights onto surfaces of varying heights. Experiments 2, 3 used two different effort manipulations (walking vs. hopping; and carrying an empty vs. a heavy backpack, respectively) and found that these did not influence estimates of distance (to be) traveled. Experiment 4 also used backpack weight to manipulate effort but critically, unlike Exp. 1-3 it did not employ a cover story and participants did not traverse distances after giving estimates. In contrast with the first three experiments, distances in the final experiment were estimated as longer when participants were encumbered by a backpack. Combined, these results suggest that the measured effects on the estimation of distance were due to how participants construed the task rather than being of a perceptual nature.

Dataset Information

Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds.

Publications

Steric environment around acetylcholine head groups of bolaamphiphilic nanovesicles influences the release rate of encapsulated compounds.

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