Sequential gentle hydration increases encapsulation in model protocells.

Small, spherical vesicles are a widely used chassis for the formation of model protocells and investigating the beginning of compartmentalized evolution. Various methods exist for their preparation, with one of the most common approaches being gentle hydration, where thin layers of lipids are hydrated with aqueous solutions and gently agitated to form vesicles. An important benefit to gentle hydration is that the method produces vesicles without introducing any organic contaminants, such as mineral oil, into the lipid bilayer. However, compared to other methods of liposome formation, gentle hydration is much less efficient at encapsulating aqueous cargo. Improving the encapsulation efficiency of gentle hydration would be of broad use for medicine, biotechnology, and protocell research. Here, we describe a method of sequentially hydrating lipid thin films to increase encapsulation efficiency. We demonstrate that sequential gentle hydration significantly improves encapsulation of water-soluble cargo compared to the traditional method, and that this improved efficiency is dependent on buffer composition. Similarly, we also demonstrate how this method can be used to increase concentrations of oleic acid, a fatty acid commonly used in origins of life research, to improve the formation of vesicles in aqueous buffer.

Cell-Free Expressed Membraneless Organelles Inhibit Translation in Synthetic Cells.

Compartments within living cells create specialized microenvironments, allowing multiple reactions to be carried out simultaneously and efficiently. While some organelles are bound by a lipid bilayer, others are formed by liquid-liquid phase separation such as P-granules and nucleoli. Synthetic minimal cells are widely used to study many natural processes, including organelle formation. In this work, synthetic cells expressing artificial membrane-less organelles that inhibit translation are described. RGG-GFP-RGG, a phase-separating protein derived from Caenorhabditis elegans P-granules, is expressed by cell-free transcription and translation, forming artificial membraneless organelles that can sequester RNA and reduce protein expression in synthetic cells. The introduction of artificial membrane-less organelles creates complex microenvironments within the synthetic cell cytoplasm and functions as a tool to inhibit protein expression in synthetic cells. The engineering of compartments within synthetic cells furthers the understanding of the evolution and function of natural organelles and facilitates the creation of more complex and multifaceted synthetic lifelike systems.

Sequential gentle hydration increases encapsulation in model protocells.

Small, spherical vesicles are a widely used chassis for the formation of model protocells and investigating the beginning of compartmentalized evolution. Various methods exist for their preparation, with one of the most common approaches being gentle hydration, where thin layers of lipids are hydrated with aqueous solutions and gently agitated to form vesicles. An important benefit to gentle hydration is that the method produces vesicles without introducing any organic contaminants, such as mineral oil, into the lipid bilayer. However, compared to other methods of liposome formation, gentle hydration is much less efficient at encapsulating aqueous cargo. Improving the encapsulation efficiency of gentle hydration would be of broad use for medicine, biotechnology, and protocell research. Here, we describe a method of sequentially hydrating lipid thin films to increase encapsulation efficiency. We demonstrate that sequential gentle hydration significantly improves encapsulation of water-soluble cargo compared to the traditional method, and that this improved efficiency is dependent on buffer composition. Similarly, we also demonstrate how this method can be used to increase concentrations of oleic acid, a fatty acid commonly used in origins of life research, to improve the formation of vesicles in aqueous buffer.

Cell-free expressed membraneless organelles sequester RNA in synthetic cells.

Compartments within living cells create specialized microenvironments, allowing for multiple reactions to be carried out simultaneously and efficiently. While some organelles are bound by a lipid bilayer, others are formed by liquid-liquid phase separation, such as P-granules and nucleoli. Synthetic minimal cells have been widely used to study many natural processes, including organelle formation. Here we describe a synthetic cell expressing RGG-GFP-RGG, a phase-separating protein derived from LAF-1 RGG domains, to form artificial membraneless organelles that can sequester RNA and reduce protein expression. We create complex microenvironments within synthetic cell cytoplasm and introduce a tool to modulate protein expression in synthetic cells. Engineering of compartments within synthetic cells furthers understanding of evolution and function of natural organelles, as well as it facilitates the creation of more complex and multifaceted synthetic life-like systems.

Toward synthetic life: Biomimetic synthetic cell communication.

Engineering synthetic minimal cells provide a controllable chassis for studying the biochemical principles of natural life, increasing our understanding of complex biological processes. Recently, synthetic cell engineering has enabled communication between both natural live cells and other synthetic cells. A system such as these enable studying interactions between populations of cells, both natural and artificial, and engineering small molecule cell communication protocols for a variety of basic research and practical applications. In this review, we summarize recent progress in engineering communication between synthetic and natural cells, and we speculate about the possible future directions of this work.

Place learning overrides innate behaviors in Drosophila.

Animals in a natural environment confront many sensory cues. Some of these cues bias behavioral decisions independent of experience, and action selection can reveal a stimulus-response (S-R) connection. However, in a changing environment it would be a benefit for an animal to update behavioral action selection based on experience, and learning might modify even strong S-R relationships. How animals use learning to modify S-R relationships is a largely open question. Three sensory stimuli, air, light, and gravity sources were presented to individual Drosophila melanogaster in both naïve and place conditioning situations. Flies were tested for a potential modification of the S-R relationships of anemotaxis, phototaxis, and negative gravitaxis by a contingency that associated place with high temperature. With two stimuli, significant S-R relationships were abandoned when the cue was in conflict with the place learning contingency. The role of the dunce (dnc) cAMP-phosphodiesterase and the rutabaga (rut) adenylyl cyclase were examined in all conditions. Both dnc1 and rut2080 mutant flies failed to display significant S-R relationships with two attractive cues, and have characteristically lower conditioning scores under most conditions. Thus, learning can have profound effects on separate native S-R relationships in multiple contexts, and mutation of the dnc and rut genes reveal complex effects on behavior.

The Drosophila Gr28bD product is a non-specific cation channel that can be used as a novel thermogenetic tool.

Extrinsic control of single neurons and neuronal populations is a powerful approach for understanding how neural circuits function. Adding new thermogenetic tools to existing optogenetic and other forms of intervention will increase the complexity of questions that can be addressed. A good candidate for developing new thermogenetic tools is the Drosophila gustatory receptor family, which has been implicated in high-temperature avoidance behavior. We examined the five members of the Gr28b gene cluster for temperature-dependent properties via three approaches: biophysical characterization in Xenopus oocytes, functional calcium imaging in Drosophila motor neurons, and behavioral assays in adult Drosophila. Our results show that Gr28bD expression in Xenopus oocytes produces a non-specific cationic current that is activated by elevated temperatures. This current is non-inactivating and non-voltage dependent. When expressed in Drosophila motor neurons, Gr28bD can be used to change the firing pattern of individual cells in a temperature-dependent fashion. Finally, we show that pan-neuronal or motor neuron expression of Gr28bD can be used to alter fruit fly behavior with elevated temperatures. Together, these results validate the potential of the Gr28bD gene as a founding member of a new class of thermogenetic tools.

Cost and Use of Pasteurized Donor Human Milk at a Children's Hospital.

OBJECTIVE: To determine the cost and use of pasteurized donor human milk (PDHM) at a children's hospital with a strong human milk culture. DESIGN: A retrospective descriptive cohort study. SETTING: A children's hospital in the northeastern region of the United States. PARTICIPANTS: Infants (N = 281) younger than 1 year of age at the time of hospitalization who received PDHM between January 2011 and November 2014. Infants older than 1 year of age at the time of hospitalization were excluded from the study sample. METHODS: For each eligible infant, the following descriptive characteristics were abstracted from the electronic health record: gestational age, birth weight, primary diagnosis, unit/floor, total volume of PDHM fed to infant, total number of days the infant received PDHM, diet order on day of discharge, and total length of stay in days. Descriptive statistics were used to analyze all data. RESULTS: Of the sample, 70% (n = 197/281) were cared for in the NICU and 30% (n = 84/281) were cared for outside of the NICU. The mean number of days an infant received PDHM was 23 days (range = 1-134 days) and the mean volume consumed daily was 195 ml (range = 6-1,335 ml). Using a purchase cost of U.S. $4.50 per ounce, the average purchase cost of PDHM per day was U.S. $29.19 (range = U.S. $0.90 to U.S. $200.23). CONCLUSION: PDHM is a low-cost intervention compared with many other interventions for the care of hospitalized infants.

'Epileptic', 'epileptic person' or 'person with epilepsy'? Bringing quantitative and qualitative evidence on the views of UK patients and carers to the terminology debate.

How to refer to someone with epilepsy is a divisive topic. Arguments for and against different approaches, including traditional adjective labels, disability-first labels, and person-first terms have been presented. The preferences of those with epilepsy and their family and friends have, though, never been determined. This study provides this information for the first time. Via epilepsy interest groups and organizations in the UK and Republic of Ireland, 638 patients and 333 significant others completed an online survey. Three distinct phrases were presented: "They're epileptic" (traditional label), "They're an epileptic person" (disability-first) and "That person has epilepsy" (person-first). Participants identified which they preferred and explained their choices. Patients' median age was 39, with 69% having experienced seizures in the prior 12months. Significant others were typically parents. Most (86.7%) patients and significant others (93.4%) favored the person-first term. Traditional and disability-first terms were "Disliked"/"Strongly disliked". Regression found it was not possible to reliably distinguish between participants favoring the different terms on the basis of demographics. Qualitative analysis of answers to open-ended questions, however, revealed most favored person-first terminology as by not including the word 'epileptic' and by affirming personhood before disability, it was felt to less likely restrict a listener's expectations or evoke the condition's negative association. It was also considered to suggest the person being referred to might have some mastery over their condition. The findings indicate consensus amongst these key stakeholders others for the use of person-first terminology in English. A truly informed debate on the topic can now begin.