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BackgroundBiofuel production from plant cell walls offers the potential for sustainable and economically attractive alternatives to petroleum-based products. Fuels from cellulosic biomass are particularly promising, but would benefit from lower processing costs. Clostridium thermocellum can rapidly solubilize and ferment cellulosic biomass, making it a promising candidate microorganism for consolidated bioprocessing for biofuel production, but increases in product yield and titer are still needed.ResultsHere, we started with an engineered C. thermocellum strain where the central metabolic pathways to products other than ethanol had been deleted. After two stages of adaptive evolution, an evolved strain was selected with improved yield and titer. On chemically defined medium with crystalline cellulose as substrate, the evolved strain produced 22.4 ± 1.4 g/L ethanol from 60 g/L cellulose. The resulting yield was about 0.39 gETOH/gGluc eq, which is 75 % of the maximum theoretical yield. Genome resequencing, proteomics, and biochemical analysis were used to examine differences between the original and evolved strains.ConclusionsA two step selection method successfully improved the ethanol yield and the titer. This evolved strain has the highest ethanol yield and titer reported to date for C. thermocellum, and is an important step in the development of this microbe for industrial applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0528-8) contains supplementary material, which is available to authorized users.

During the evolution of SARS-CoV-2 in humans a D614G substitution in the spike (S) protein emerged and became the predominant circulating variant (S-614G) of the COVID-19 pandemic. However, whether the increasing prevalence of the S-614G variant represents a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains elusive. Here, we generated isogenic SARS-CoV-2 variants and demonstrate that the S-614G variant has (i) enhanced binding to human ACE2, (ii) increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a novel human ACE2 knock-in mouse model, and (iii) markedly increased replication and transmissibility in hamster and ferret models of SARS-CoV-2 infection. Collectively, our data show that while the S-614G substitution results in subtle increases in binding and replication in vitro, it provides a real competitive advantage in vivo, particularly during the transmission bottle neck, providing an explanation for the global predominance of S-614G variant among the SARS-CoV-2 viruses currently circulating.

PurposeComprehensive evaluation of anaphylaxis in China is currently lacking. In this study, we characterized the clinical profiles, anaphylactic triggers, and emergency treatment in pediatric and adult patients.MethodsOutpatients diagnosed with "anaphylaxis" or "severe allergic reactions" in the Department of Allergy, Peking Union Medical College Hospital from January 1, 2000 to June 30, 2014 were analyzed retrospectively.ResultsA total of 1,952 episodes of anaphylaxis in 907 patients were analyzed (78% were adults and 22% were children). Foods are the most common cause (77%), followed by idiopathic etiologies (15%), medications (7%) and insects (0.6%). In food-induced anaphylaxis, 62% (13/21) of anaphylaxis in infants and young children (0-3 years of age) were triggered by milk, 59% (36/61) of anaphylaxis in children (4-9 years of age) were triggered by fruits/vegetables, while wheat was the cause of anaphylaxis in 20% (56/282) of teenagers (10-17 years of age) and 42% (429/1,016) in adults (18-50 years of age). Mugwort pollen sensitization was common in patients with anaphylaxis induced by spices, fruits/vegetables, legume/peanuts, and tree nuts/seeds, with the prevalence rates of 75%, 67%, 61%, and 51%, respectively. Thirty-six percent of drug-induced anaphylaxis was attributed to traditional Chinese Medicine. For patients receiving emergency care, only 25% of patients received epinephrine.ConclusionsThe present study showed that anaphylaxis appeared to occur more often in adults than in infants and children, which were in contrast to those found in other countries. In particular, wheat allergens played a prominent role in triggering food-induced anaphylaxis, followed by fruits/vegetables. Traditional Chinese medicine was a cause of drug-induced anaphylaxis. Furthermore, exercise was the most common factor aggravating anaphylaxis. Education regarding the more aggressive use of epinephrine in the emergency setting is clearly needed.

Cobamides such as vitamin B12 are structurally conserved, cobalt-containing tetrapyrrole biomolecules with essential biochemical functions in all domains of life. In organohalide respiration, a vital biological process for the global cycling of natural and anthropogenic organohalogens, cobamides are the requisite prosthetic groups for carbon–halogen bond-cleaving reductive dehalogenases. This study reports the biosynthesis of a new cobamide with unsubstituted purine as the lower base, and assigns unsubstituted purine a biological function by demonstrating that Coα-purinyl-cobamide (purinyl-Cba) is the native prosthetic group in catalytically active tetrachloroethene reductive dehalogenases of Desulfitobacterium hafniense. Cobamides featuring different lower bases are not functionally equivalent, and purinyl-Cba elicits different physiological responses in corrinoid-auxotrophic, organohalide-respiring bacteria. Given that cobamide-dependent enzymes catalyze key steps in essential metabolic pathways, the discovery of a novel cobamide structure and the realization that lower bases can effectively modulate enzyme activities generate opportunities to manipulate functionalities of microbiomes.

The objective of this study was to determine the effects of different transport times on broilers during summer on stress, meat quality, and early postmortem muscle metabolites. Arbor Acres broiler chickens (n = 105) were randomly categorized into 5 treatments: unstressed control, 0.5 h, 1 h, 2 h, and 4 h transport. Each treatment consisted of 3 replicates with 7 birds each. All birds (except the control group) were transported according to a designed protocol. With the extension of transport time, the activities of plasma creatine kinase (CK) and lactate dehydrogenase (LDH) gradually increased. The content of heat shock protein 70 (Hsp70) did not change significantly during 0.5 h transport compared to the control group, but was significantly higher (P < 0.05) at 1 h or more of transport time. Also, transport times of 2 h or more resulted in a death rate of 20%-33% of broilers. We found that the breast meat in the 0.5 h transport group had significantly (P < 0.05) higher L* values, drip loss, cooking loss, AMP/ATP ratio, and phosphorylation of AMP-activated protein kinase (p-AMPK). In addition, pH24h was lower compared to the control group, increasing the likelihood of pale, soft, and exudative (PSE)-like meat. However, no significant variations were found in meat color, drip loss, or cooking loss in other transport groups compared to the control group under the condition of this study. Muscle glycogen content decreased with time of transportation. There were significant correlations among p-AMPK and meat quality (P < 0.05). These results indicate that preslaughter transport during summer may cause severe physiological and biochemical changes of broilers. Further investigations studying the deeper relationship between biological indicators and meat quality according to the similar transport conditions would provide a better understanding of the effect of transport duration on meat quality.

Introduction Postorgasmic illness syndrome (POIS) is a rarely described syndrome characterized by transient flu-like symptoms and cognition disorders. Recent studies suggest that immunogenic reactivity to autologous semen is the underlying mechanism in POIS. However, there are no data published on immunoglobulin E (IgE)-mediated allergy to autologous semen in men without POIS. Aim The purpose of the current work was to characterize the first diagnosed POIS patient in China and to study the allergic response of autologous semen in the affected patient and in three healthy males. Methods Specific IgE was tested with seminal fluid and common perennial aeroallergens in vitro. Skin prick tests and intracutaneous tests with autologous diluted semen were performed in the patient and three healthy donors. The pattern of IgE reactivity to patient's semen was identified using immunoblotting and ELISA. Main Outcome Measure Clinical features of POIS, skin reactions with autologous diluted seminal fluid, and the IgE reactivity patterns of immunoblotting and ELISA in vitro. Results A patient was diagnosed with POIS. The patient complained of lifelong premature ejaculation symptoms and allergic rhinitis. Routine laboratory and hormonal assessments were generally within normal range. The patient had a positive skin test with his own semen. Three healthy donors also showed positive skin tests. No semen-specific IgE to autologous semen was detected in the serum of the affected patient or healthy males. Conclusions This is the first report of a man with POIS in China. He had positive skin reactions after injection of autologous seminal fluid but no detectable serum concentrations of specific IgE antibodies. IgE-mediated semen allergy in men may not be the potential mechanism of POIS.

The aim of this study was to determine the effects of pre-slaughter transport during summer and subsequent water shower spray on stress, postmortem glycolysis, energy metabolism and adenosine monophosphate-activated protein kinase (AMPK) in Pectoralis major (PM) muscle of broilers. Results indicated that transport during high ambient temperature induced the release of plasma corticosterone, which significantly affected stress conditions. Moreover, we found a lower energy status in the early postmortem period compared to the control group. AMPK was activated in this situation, following by the rapid glycolysis and accumulation of lactic acid, leading to a high incidence of pale, soft, exudative (PSE)-like meat. Water shower spray with resting after transport relieved the stress situation, recovered energy homeostasis and lessened the deterioration of meat quality. As a key molecular target for the control of energy status, AMPK has a similar potential in regulating postmortem muscle glycolysis of broilers as in mammals.