Complement component C1q is an immunological rheostat that regulates Fc:Fc[Formula: see text]R interactions.

Though binding sites for the complement factor C1q and the canonical fragment crystallizable (Fc) gamma receptors (Fc[Formula: see text]Rs) on immunoglobulin G (IgG) molecules overlap, how C1q decoration of immune complexes (ICs) influences their ability to engage Fc[Formula: see text]Rs remains unknown. In this report, we use recombinant human Fc multimers as stable IC mimics to show that C1q engagement of ICs directly and transiently inhibits their interactions with Fc[Formula: see text]RIII (CD16) on human natural killer (NK) cells. This inhibition occurs by C1q engagement alone as well as in concert with other serum factors. Furthermore, the inhibition of Fc[Formula: see text]RIII engagement mediated by avid binding of C1q to ICs is directly associated with IC size and dependent on the concentrations of both C1q and Fc multimers present. Functionally, C1q-mediated Fc blockade limits the ability of NK cells to induce the upregulation of the cosignaling molecule, 4-1BB (CD137), and to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). Although C1q is traditionally viewed as a soluble effector molecule, we demonstrate that C1q may also take on the role of an "immunologic rheostat," buffering Fc[Formula: see text]R-mediated activation of immune cells by circulating ICs. These data define a novel role for C1q as a regulator of immune homeostasis and add to our growing understanding that complement factors mediate pleiotropic effects.

Techno-economic modeling and assessment of cultivated meat: Impact of production bioreactor scale.

Increases in global meat demands cannot be sustainably met with current methods of livestock farming, which has a substantial impact on greenhouse gas emissions, land use, water consumption, and farm animal welfare. Cultivated meat is a rapidly advancing technology that produces meat products by proliferating and differentiating animal stem cells in large bioreactors, avoiding conventional live-animal farming. While many companies are working in this area, there is a lack of existing infrastructure and experience at commercial scale, resulting in many technical bottlenecks such as scale-up of cell culture and media availability and costs. In this study, we evaluate theoretical cultivated beef production facilities with the goal of envisioning an industry with multiple facilities to produce in total 100,000,000 kg of cultured beef per year or ~0.14% of the annual global beef production. Using the computer-aided process design software, SuperPro Designer®, facilities are modeled to create a comprehensive analysis to highlight improvements that can lower the cost of such a production system and allow cultivated meat products to be competitive. Three facility scenarios are presented with different sized production reactors; ~42,000 L stirred tank bioreactor (STR) with a base case cost of goods sold (COGS) of $35/kg, ~211,000 L STR with a COGS of $25/kg, and ~262,000 L airlift reactor (ALR) with a COGS of $17/kg. This study outlines how advances in scaled up bioreactors, alternative bioreactor designs, and decreased media costs are necessary for commercialization of cultured meat products.

Multi-information source Bayesian optimization of culture media for cellular agriculture.

Culture media used in industrial bioprocessing and the emerging field of cellular agriculture is difficult to optimize due to the lack of rigorous mathematical models of cell growth and culture conditions, as well as the complexity of the design space. Rapid growth assays are inaccurate yet convenient, while robust measures of cell number can be time-consuming to the point of limiting experimentation. In this study, we optimized a cell culture media with 14 components using a multi-information source Bayesian optimization algorithm that locates optimal media conditions based on an iterative refinement of an uncertainty-weighted desirability function. As a model system, we utilized murine C2C12 cells, using AlamarBlue, LIVE stain, and trypan blue exclusion cell counting assays to determine cell number. Using this experimental optimization algorithm, we were able to design media with 181% more cells than a common commercial variant with a similar economic cost, while doing so in 38% fewer experiments than an efficient design-of-experiments method. The optimal medium generalized well to long-term growth up to four passages of C2C12 cells, indicating the multi-information source assay improved measurement robustness relative to rapid growth assays alone.

Metabolic flux sampling predicts strain-dependent differences related to aroma production among commercial wine yeasts.

BACKGROUND: Metabolomics coupled with genome-scale metabolic modeling approaches have been employed recently to quantitatively analyze the physiological states of various organisms, including Saccharomyces cerevisiae. Although yeast physiology in laboratory strains is well-studied, the metabolic states under industrially relevant scenarios such as winemaking are still not sufficiently understood, especially as there is considerable variation in metabolism between commercial strains. To study the potential causes of strain-dependent variation in the production of volatile compounds during enological conditions, random flux sampling and statistical methods were used, along with experimental extracellular metabolite flux data to characterize the differences in predicted intracellular metabolic states between strains. RESULTS: It was observed that four selected commercial wine yeast strains (Elixir, Opale, R2, and Uvaferm) produced variable amounts of key volatile organic compounds (VOCs). Principal component analysis was performed on extracellular metabolite data from the strains at three time points of cell cultivation (24, 58, and 144 h). Separation of the strains was observed at all three time points. Furthermore, Uvaferm at 24 h, for instance, was most associated with propanol and ethyl hexanoate. R2 was found to be associated with ethyl acetate and Opale could be associated with isobutanol while Elixir was most associated with phenylethanol and phenylethyl acetate. Constraint-based modeling (CBM) was employed using the latest genome-scale metabolic model of yeast (Yeast8) and random flux sampling was performed with experimentally derived fluxes at various stages of growth as constraints for the model. The flux sampling simulations allowed us to characterize intracellular metabolic flux states and illustrate the key parts of metabolism that likely determine the observed strain differences. Flux sampling determined that Uvaferm and Elixir are similar while R2 and Opale exhibited the highest degree of differences in the Ehrlich pathway and carbon metabolism, thereby causing strain-specific variation in VOC production. The model predictions also established the top 20 fluxes that relate to phenotypic strain variation (e.g. at 24 h). These fluxes indicated that Opale had a higher median flux for pyruvate decarboxylase reactions compared with the other strains. Conversely, R2 which was lower in all VOCs, had higher median fluxes going toward central metabolism. For Elixir and Uvaferm, the differences in metabolism were most evident in fluxes pertaining to transaminase and hexokinase associated reactions. The applied analysis of metabolic divergence unveiled strain-specific differences in yeast metabolism linked to fusel alcohol and ester production. CONCLUSIONS: Overall, this approach proved useful in elucidating key reactions in amino acid, carbon, and glycerophospholipid metabolism which suggest genetic divergence in activity in metabolic subsystems among these wine strains related to the observed differences in VOC formation. The findings in this study could steer more focused research endeavors in developing or selecting optimal aroma-producing yeast stains for winemaking and other types of alcoholic fermentations.

Considerations for the development of cost-effective cell culture media for cultivated meat production.

Innovation in cultivated meat development has been rapidly accelerating in recent years because it holds the potential to help attenuate issues facing production of dietary protein for a growing world population. There are technical obstacles still hindering large-scale commercialization of cultivated meat, of which many are related to the media that are used to culture the muscle, fat, and connective tissue cells. While animal cell culture media has been used and refined for roughly a century, it has not been specifically designed with the requirements of cultivated meat in mind. Perhaps the most common industrial use of animal cell culture is currently the production of therapeutic monoclonal antibodies, which sell for orders of magnitude more than meat. Successful production of cultivated meat requires media that is food grade with minimal cost, can regulate large-scale cell proliferation and differentiation, has acceptable sensory qualities, and is animal ingredient-free. Much insight into strategies for achieving media formulations with these qualities can be obtained from knowledge of conventional culture media applications and from the metabolic pathways involved in myogenesis and protein synthesis. In addition, application of principles used to optimize media for large-scale microbial fermentation processes producing lower value commodity chemicals and food ingredients can also be instructive. As such, the present review shall provide an overview of the current understanding of cell culture media as it relates to cultivated meat.

A combined phenolic extraction and fermentation reactor engineering model for multiphase red wine fermentation.

Red wine production begins with a simultaneous fermentation and solid-phase extraction process. Red wine color and mouthfeel is the result of the extraction of phenolics from grape skins and seeds during fermentation, where extraction is a strong function of temperature and ethanol concentration. During fermentation, grape solids form a porous "cap" at the top of the fermentor, resulting in a heterogeneous fermentation system with significant temperature and concentration gradients. In this work, we present a spatial, time-variant reactor engineering model for phenolic extraction during red wine fermentation, incorporating fermentation kinetics, mass transfer, heat transfer, compressible fluid flow, and phenolic extraction kinetics. The temperature and ethanol concentration profiles predicted by this model allow for the calculation of phenolic extraction rates over the course of fermentation. Phenolic extraction predictions were validated against prior experimental data to good agreement and compared to a well-mixed model's predictions to show the utility of a spatial model over well-mixed models.

The Effects of Temperature and Ethanol on Proanthocyanidin Adsorption to Grape Cell Wall Material in the Presence of Anthocyanins.

The quantitative and qualitative impacts of anthocyanins on proanthocyanidin adsorption to grape-derived cell wall material were investigated in fifteen unique systems of varying temperatures, ethanol concentrations, and proanthocyanidin concentrations. Proanthocyanidin solutions were exposed to cell wall material and monitored for changes in concentration over 24 h. Increases in both temperature and ethanol resulted in a larger retention of proanthocyanidins in solution and typically faster adsorption kinetics. Analysis of the solution after exposure to cell wall revealed a significant reduction in the molecular weight of proanthocyanidins present in solution, suggesting that anthocyanins do not alter a previously described mechanism of preferentially binding large molecular weight molecules. Additionally, a reduction in polymeric pigment abundance was noted in most conditions, suggesting rapid formation of polymeric pigment in the model solution and preferential adsorption of the polymeric pigment to cell wall material. Compared to a previous study of proanthocyanidin adsorption in the absence of anthocyanins, a significantly larger percentage of proanthocyanidin material was lost via adsorption-up to 70% of available material. In a winemaking context, this may suggest a preferential loss of polymeric pigment via adsorption to cap cell wall material compared to non-pigmented proanthocyanidins and free anthocyanins.

Creation and validation of a reactor engineering model for multiphase red wine fermentations.

Red wine fermentations are performed in the presence of grape skins and seeds to ensure the extraction of color and other phenolics. The presence of these solids results in two distinct phases in the fermentor, as the solids float to the top to form a "cap." Modeling of red wine fermentation is, therefore, complex and must consider spatial heterogeneity to predict fermentation kinetics. We have developed a reactor-engineering model for red wine fermentations that includes the fundamentals of fermentation kinetics, heat transfer, diffusion, and compressible fluid flow. To develop the heat transfer component of the model, the heat transfer properties of grapes were experimentally determined as a function of fermentation progression. COMSOL was used to solve all components of the model simultaneously utilizing a finite element analysis approach. Predictions from this model were validated using prior experimental work. Model prediction and experimental data showed excellent agreement. The model was then used to predict spatial profiles of active yeast cell concentration and ethanol productivity, as well as liquid velocity profiles. Finally, the model was used to predict how these gradients would change with differences in initial bioavailable nitrogen concentration, a key parameter in predicting fermentation outcome in nitrogen-limited wine fermentations.

A Mechanistic Model for the Extraction of Phenolics from Grapes During Red Wine Fermentation.

Phenolic extraction is a critical part of red wine making. Though empirical models of phenolic extraction kinetics exist, the current level of mechanistic understanding does not allow for accurate predictions. In this work, we propose a mechanistic model for the extraction of phenolics from grape skins and seeds as a function of temperature and ethanol. This model examines the release of phenolics, the adsorption of phenolics onto grape material, and the disappearance of anthocyanins from solution. Additionally, we performed epifluorescence microscopy to explore our finding that seed tannins' release rate appears independent of concentration, and found that the grape seed appears to ablate over fermentation. We also determined the activation energy of anthocyanin disappearance, in good agreement with similar systems. The proposed model results in an excellent fit, and increases the understanding of phenolic extraction and the ability to predict and optimize product outcome in red wine making.

Impact of Temperature, Ethanol and Cell Wall Material Composition on Cell Wall-Anthocyanin Interactions.

The effects of temperature and ethanol concentration on the kinetics of anthocyanin adsorption and desorption interactions with five cell wall materials (CWM) of different composition were investigated. Using temperatures of 15 °C and 30 °C and model wine with ethanol concentrations of 0% and 15% (v/v) over 120 min, the adsorption and desorption rates of five anthocyanin-glucosides were recorded in triplicate. Small-scale experiments were conducted using a benchtop incubator to mimic a single berry fermentation. Results indicate that more than 90% of the adsorption occurs within the first 60 min of the addition of anthocyanins to CWM. However, desorption appears to occur much faster, with maximum desorption being reached after 30 min. The extent of both adsorption and desorption was clearly dependent not only on temperature and ethanol concentration but also on the CWM composition.

Heat-Dependent Desorption of Proanthocyanidins from Grape-Derived Cell Wall Material under Variable Ethanol Concentrations in Model Wine Systems.

Desorption of proanthocyanidins (PA) from grape cell wall material (CWM) was investigated in solutions of varying ethanol concentrations and increasing temperature. The results reveal the reversibility of PA-CWM interactions and the role that temperature and ethanol concentration play in the extent of PA desorption. Sequentially raising temperature from 15 to 35 °C resulted in desorption of up to 48% of the initial adsorbed PA. A comparison to a phenolic extraction model showed significant differences between the predicted and actual amount of PA that desorbed from the CWM. This suggests that the initial conditions of temperature and ethanol concentration must be considered when estimating PA extraction in red wine production. Under typical winemaking conditions, a significant amount of PA may be irreversibly adsorbed if exposed to CWM at low temperature (i.e., cold soak). A compositional analysis suggests the selective desorption of large molecular weight PA from CWM under all experimental conditions. Additionally, a preferential desorption of skin-derived PA over seed-derived PA was noted in the absence of ethanol.

Impact of cold soak duration on Cabernet Sauvignon fermentation and phenolic composition.

BACKGROUND: Cold soak is a prefermentative maceration technique believed to enhance grape skin extraction. Studies show variable results depending on cold soak and winemaking conditions. To investigate the effect of cold soak more fully, systematic and highly reproducible Cabernet Sauvignon fermentations with increasing cold-soak durations were performed. RESULTS: Phenolic extraction during cold soak and fermentation showed significant differences among all treatments for monitored phenolics at the end of the cold soak. At the end of alcoholic fermentation only gallic acid, (-)-epicatechin, and the flavonols were significant, and only (-)-epicatechin was significant after bottle ageing. Descriptive analysis of the bottled wines showed that the 4- and 7-day treatments were significantly higher in caramelized/vanilla/browned flavor compared to the 1-day treatment and lower levels of bitterness were observed up to 2 days of cold soak. While oligosaccharide content increased with increasing cold-soak duration, differences were not large enough to result in sensory differences. CONCLUSION: While increased cold soak duration led to differences in phenolic extraction during early fermentation, these differences did not last through to the end product. Thus, under the conditions of this study, cold-soak duration had little overall impact on Cabernet Sauvignon wine composition and style. © 2018 Society of Chemical Industry.

Conversion of cassava leaf to bioavailable, high-protein yeast cell biomass.

BACKGROUND: Cassava leaves are an abundant global agricultural residue because the roots are a major source of dietary carbohydrates. Although cassava leaves are high in protein, the protein is not bioavailable. This work aimed to convert cassava leaves to a bioavailable protein-rich animal feed ingredient using high-protein yeasts. RESULTS: The structural proteins (ca 200 g kg-1 d.b.) from sundried cassava leaves were solubilized by mild alkali pretreatment, and the resulting cassava leaf hydrolysate (CLH) was used to screen for growth of 46 high-protein yeasts from 30 species. Promising candidates from the initial screen cultivated at a 10 mL scale demonstrated increases in relative abundance of essential amino acids over that of CLH. In particular, lysine, growth-limiting for some livestock, was increased up to 226% over the CLH content. One yeast, Pichia kudriavzevii UCDFST 11-602, was grown in 3 L of CLH in a bioreactor to examine the scale-up potential of the yeast protein production. While glucose was completely consumed, yeast growth exited log phase before depleting either carbon or nitrogen, suggesting other growth-limiting factors at the larger scale. CONCLUSIONS: High-value animal feed with enriched essential amino acid profiles can be produced by yeasts grown on agricultural residues. Yeasts convert structural protein solubilized from cassava leaves to essential amino acid-enriched, digestible protein. The low carbohydrate content of the leaves (ca 200 g kg-1 d.b.), however, necessitated glucose supplementation for yeast growth. © 2018 Society of Chemical Industry.

Anti-CD20 Antibody with Multimerized Fc Domains: A Novel Strategy To Deplete B Cells and Augment Treatment of Autoimmune Disease.

We developed a fully recombinant anti-CD20 protein derived from cDNA encoding one Fab domain, two IgG1 Fc regions, the IgG2 hinge, and an isoleucine zipper. This protein, called GB4542, contained both the homodimer and higher-order multimers. Binding studies revealed that GB4542 preferentially bound CD20(+) cells yet also recognized CD20(-)FcγR(+) PBMC. In contrast, a control mAb containing the identical Fab region, GB4500, failed to bind CD20(-)FcγR(+) PBMC. Consistent with these findings, interactions between GB4542 and the canonical FcγRs had substantially lower KD values than correlate interfaces between GB4500 and these receptors. At low concentrations, GB4542 showed enhanced Ab-dependent cellular cytotoxicity, Ab-dependent cellular phagocytosis, and complement-dependent cytotoxicity compared with GB4500. However, at higher concentrations, an Fc analog of GB4542 inhibited anti-CD20 mAb-mediated B cell clearance through direct blocking of both Fc-FcγR interactions and C1q deposition on target cells. Furthermore, the higher-order multimer fraction of GB4542 demonstrated greater binding avidity with the canonical FcγRs and was associated with inhibitory effects observed in Ab-dependent cellular phagocytosis and complement-dependent cytotoxicity assays. These data suggest that GB4542 might have utility in the treatment of autoimmune diseases by combining both mAb-mediated B cell depletion and multimerized Fc-mediated tolerogenic effects.

Recombinant human IgG1 based Fc multimers, with limited FcR binding capacity, can effectively inhibit complement-mediated disease.

There is a lack of effective targeted therapies for the treatment of complement dependent diseases. We developed two recombinant Fc multimers, G207 and G211, with limited ability to interact with low/moderate affinity FcγRs, but with high avidity for C1q. These drugs effectively inhibited complement dependent cytotoxicity (CDC) in vitro, and prevented the deposition of C1q, C3b and MAC, on the surface of Ab-opsonized cells. Importantly, these inhibitory effects were both C1q dependent and independent. In order to determine the biologic relevance of our findings, we evaluated the clinical efficacy of these drugs in three different animal models, acute RBC hemolysis, anti-Thy-1 nephritis and passive Heymann's nephropathy (PHN), in which disease pathophysiology relies preferentially on complement activation. While G207 was protective in the anti-Thy-1 nephritis and PHN models, G211 was protective in all of the models tested and could effectively treat PHN. In the anti-Thy-1 nephritis model, G211 prevented the characteristic histologic changes associated with the disease and limited glomerular deposition of C3. Collectively, these data suggest that "complement preferential" Fc multimers offer a novel approach to the treatment of complement mediated diseases.

Simultaneous production of intracellular triacylglycerols and extracellular polyol esters of fatty acids by Rhodotorula babjevae and Rhodotorula aff. paludigena.

Microbial oils have been analyzed as alternatives to petroleum. However, just a handful of microbes have been successfully adapted to produce chemicals that can compete with their petroleum counterparts. One of the reasons behind the low success rate is the overall economic inefficiency of valorizing a single product. This study presents a lab-scale analysis of two yeast species that simultaneously produce multiple high-value bioproducts: intracellular triacylglycerols (TG) and extracellular polyol esters of fatty acids (PEFA), two lipid classes with immediate applications in the biofuels and surfactant industries. At harvest, the yeast strain Rhodotorula aff. paludigena UCDFST 81-84 secreted 20.9 ± 0.2 g L-1 PEFA and produced 8.8 ± 1.0 g L-1 TG, while the yeast strain Rhodotorula babjevae UCDFST 04-877 secreted 11.2 ± 1.6 g L-1 PEFA and 18.5 ± 1.7 g L-1 TG. The overall glucose conversion was 0.24 and 0.22 g(total lipid) g (glucose)-1 , respectively. The results present a stable and scalable microbial growth platform yielding multiple co-products.

Oligosaccharides Released from Milk Glycoproteins Are Selective Growth Substrates for Infant-Associated Bifidobacteria.

UNLABELLED: Milk, in addition to nourishing the neonate, provides a range of complex glycans whose construction ensures a specific enrichment of key members of the gut microbiota in the nursing infant, a consortium known as the milk-oriented microbiome. Milk glycoproteins are thought to function similarly, as specific growth substrates for bifidobacteria common to the breast-fed infant gut. Recently, a cell wall-associated endo-ß-N-acetylglucosaminidase (EndoBI-1) found in various infant-borne bifidobacteria was shown to remove a range of intact N-linked glycans. We hypothesized that these released oligosaccharide structures can serve as a sole source for the selective growth of bifidobacteria. We demonstrated that EndoBI-1 released N-glycans from concentrated bovine colostrum at the pilot scale. EndoBI-1-released N-glycans supported the rapid growth of Bifidobacterium longum subsp. infantis (B. infantis), a species that grows well on human milk oligosaccharides, but did not support growth of Bifidobacterium animalis subsp. lactis (B. lactis), a species which does not. Conversely, B. infantis ATCC 15697 did not grow on the deglycosylated milk protein fraction, clearly demonstrating that the glycan portion of milk glycoproteins provided the key substrate for growth. Mass spectrometry-based profiling revealed that B. infantis consumed 73% of neutral and 92% of sialylated N-glycans, while B. lactis degraded only 11% of neutral and virtually no (<1%) sialylated N-glycans. These results provide mechanistic support that N-linked glycoproteins from milk serve as selective substrates for the enrichment of infant-associated bifidobacteria capable of carrying out the initial deglycosylation. Moreover, released N-glycans were better growth substrates than the intact milk glycoproteins, suggesting that EndoBI-1 cleavage is a key initial step in consumption of glycoproteins. Finally, the variety of N-glycans released from bovine milk glycoproteins suggests that they may serve as novel prebiotic substrates with selective properties similar to those of human milk oligosaccharides. IMPORTANCE: It has been previously shown that glycoproteins serve as growth substrates for bifidobacteria. However, which part of a glycoprotein (glycans or polypeptides) is responsible for this function was not known. In this study, we used a novel enzyme to cleave conjugated N-glycans from milk glycoproteins and tested their consumption by various bifidobacteria. The results showed that the glycans selectively stimulated the growth of B. infantis, which is a key infant gut microbe. The selectivity of consumption of individual N-glycans was determined using advanced mass spectrometry (nano-liquid chromatography chip-quadrupole time of flight mass spectrometry [nano-LC-Chip-Q-TOF MS]) to reveal that B. infantis can consume the range of glycan structures released from whey protein concentrate.

Impact of shoulder internal rotation on ulnar nerve excursion and strain in embalmed cadavers. A pilot study.

DESIGN: Laboratory study, repeated-measures design. OBJECTIVE: To determine if the substitution of shoulder internal rotation for external rotation during the upper limb neurodynamic test (ULNT3) evokes a comparable ulnar nerve excursion and strain in embalmed cadavers. Shoulder external rotation is a primary movement component of the ULNT3. It has been suggested that shoulder internal rotation may provide a similar load to the nervous system. There are no data to either support or negate this claim. METHODS: Excursion and strain were measured in the ulnar nerve of six embalmed cadavers during the traditional ULNT3 and an experimental maneuver using shoulder internal rotation. RESULTS: The total means±SD of excursion for the traditional and experimental maneuvers were 2·11±0·89 and 2·09±0·92 mm, respectively. The total means±SD of strain for the traditional and experimental maneuvers were 5·274±2·223 and 5·241±2·308%, respectively. A very strong correlation (r = 0·98) was shown to exist between maneuvers and this relationship was determined to be significant (P = 0·001). DISCUSSION: The results of this study provide evidence that there is no appreciable difference in excursion or strain when substituting shoulder internal rotation for external rotation during the ULNT3. Patients who exhibit limitation of shoulder external rotation mobility may benefit from this substitution when presenting with signs of ulnar nerve pathodynamics. Further research involving patients will be needed to assess the validity of the experimental maneuver for clinical application.

Investigating the Effect of Cold Soak Duration on Phenolic Extraction during Cabernet Sauvignon Fermentation.

The impact of increasing cold soak (CS) duration (0, 1, 4, 7, and 10 days at 10 °C) on the extraction of phenolic compounds during the CS period and primary fermentation as well as the final composition of Cabernet Sauvignon wine was investigated. The results showed that CS duration had no effect on hydroxycinnamate and flavonol extractions. Greater amounts of gallic acid, (+)-catechin, (-)-epicatechin, and total tannins were extracted with increasing CS duration, with differences maintained during bottle aging. Anthocyanin extraction and color density increased with longer periods of CS; however, by the end of primary fermentation, as well as three months' bottle aging, there were no significant differences due to CS duration. The wines made with seven and 10 days of CS had higher seed tannin contributions and total tannin compared to the non-CS wine, which could potentially result in increased astringency.

Examining the role of membrane lipid composition in determining the ethanol tolerance of Saccharomyces cerevisiae.

Yeast (Saccharomyces cerevisiae) has an innate ability to withstand high levels of ethanol that would prove lethal to or severely impair the physiology of other organisms. Significant efforts have been undertaken to elucidate the biochemical and biophysical mechanisms of how ethanol interacts with lipid bilayers and cellular membranes. This research has implicated the yeast cellular membrane as the primary target of the toxic effects of ethanol. Analysis of model membrane systems exposed to ethanol has demonstrated ethanol's perturbing effect on lipid bilayers, and altering the lipid composition of these model bilayers can mitigate the effect of ethanol. In addition, cell membrane composition has been correlated with the ethanol tolerance of yeast cells. However, the physical phenomena behind this correlation are likely to be complex. Previous work based on often divergent experimental conditions and time-consuming low-resolution methodologies that limit large-scale analysis of yeast fermentations has fallen short of revealing shared mechanisms of alcohol tolerance in Saccharomyces cerevisiae. Lipidomics, a modern mass spectrometry-based approach to analyze the complex physiological regulation of lipid composition in yeast and other organisms, has helped to uncover potential mechanisms for alcohol tolerance in yeast. Recent experimental work utilizing lipidomics methodologies has provided a more detailed molecular picture of the relationship between lipid composition and ethanol tolerance. While it has become clear that the yeast cell membrane composition affects its ability to tolerate ethanol, the molecular mechanisms of yeast alcohol tolerance remain to be elucidated.