Yeast and bacterial diversity, dynamics and fermentative kinetics during small-scale tequila spontaneous fermentation.

The study of microbial communities associated with spontaneous fermentation of agave juice for tequila production is required to develop starter cultures that improve both yield and quality of the final product. Quantification by HPLC of primary metabolites produced during the fermentations was determined. A polyphasic approach using plate count, isolation and identification of microorganisms, denaturing gradient gel electrophoresis and next generation sequencing was carried out to describe the diversity and dynamics of yeasts and bacteria during small-scale spontaneous fermentations of agave juice from two-year samplings. High heterogeneity in microbial populations and fermentation parameters were observed, with bacteria showing higher diversity than yeast. The core microorganisms identified were Saccharomyces cerevisiae and Lactobacillus fermentum. Practices in tequila production changed during the two-year period, which affected microbial community structure and the time to end fermentation. Bacterial growth and concomitant lactic acid production were associated with low ethanol production, thus bacteria could be defined as contaminants in tequila fermentation and efforts to control them should be implemented.

Effect of the earthquake-tsunami (Chile, 2010) on toxic metal content in the Chilean abalone mollusc Concholepas concholepas.

Toxic metal content were measured in samples of mollusc Concholepas concholepas obtained from the Chilean coast. Samples were collected during two periods, one before and one after the earthquake-tsunami which occurred in the Maule Region, Chile, February 27th, 2010 as a result of an earthquake with a magnitude of 8.8. Quantification of toxic metals in samples of hepatopancreas and muscle tissue was performed using flame atomic absorption spectroscopy. The analytical methodology was validated with certified reference material. The content means measured in muscle tissue for January 2010 were Cu: 10.3; Cr: 0.7; Cd: < 0.1; Mn: 3.6 and Zn: 38.6 µg g-1 (dry weight). For October 2014, the means were Cu: 8; Cr: 2.4; Cd: < 0.1; Mn: 5.6 and Zn: 45.4 µg g-1 (dry weight). In hepatopancreas tissue, the content means were Cu: 14.8; Cr: 2.4; Cd: 246.2; Mn: 4.4 and Zn: 1552.9 µg g-1 (dry weight). For October 2014, the means were Cu: 53.7; Cr: 3.5; Cd: 118; Mn: 13.4 and Zn: 1352.3 µg g-1 (dry weight). Cd, Cr, Cu, Mn and Zn content in the samples of hepatopancreas were generally higher than those recorded in muscle tissue however they were not always statistically significant. Statistical analysis showed that Cu and Mn content in the post-tsunami period increased in the hepatopancreas tissue. The concentrations of Cd, Cr, Cu, Mn, and Zn measured in the muscular tissue (edible part) of the species Conchalepas concholepas, were lower than the maximum contents allowed by the current legislation (FAO/WHO, 2004; EU, 2001) and its consumption is not a risk to human health.

Geology and geochemistry of the Atacama Desert.

The Atacama Desert, the driest of its kind on Earth, hosts a number of unique geological and geochemical features that make it unlike any other environment on the planet. Considering its location on the western border of South America, between 17 and 28 °S, its climate has been characterized as arid to hyperarid for at least the past 10 million years. Notably dry climatic conditions of the Atacama Desert have been related to uplift of the Andes and are believed to have played an important role in the development of the most distinctive features of this desert, including: (i) nitrates and iodine deposits in the Central Depression, (ii) secondary enrichment in porphyry copper deposits in the Precordillera, (iii) Li enrichment in salt flats of the Altiplano, and (iv) life in extreme habitats. The geology and physiography of the Atacama Desert have been largely shaped by the convergent margin present since the Mesozoic era. The geochemistry of surface materials is related to rock geochemistry (Co, Cr, Fe, Mn, V, and Zn), salt flats, and evaporite compositions in endorheic basins (As, B, and Li), in addition to anthropogenic activities (Cu, Mo, and Pb). The composition of surface water is highly variable, nonetheless in general it presents a circumneutral pH with higher conductivity and total dissolved solids in brines. Major water constituents, with the exception of HCO3-, are generally related to the increase of salinity, and despite the fact that trace elements are not well-documented, surface waters of the Atacama Desert are enriched in As, B, and Li when compared to the average respective concentrations in rivers worldwide.

Genotypic and Phenotypic Characterization of Streptomyces Species Causing Potato Common Scab in Uruguay.

Isolation and characterization of common scab (CS) pathogen Streptomyces spp. from Uruguayan potato tubers and soil samples were done in response to significant economic losses due to CS on potato in autumn 2010. Seventy of the 331 isolates were classified as pathogenic owing to their ability to induce necrosis on tuber disks and stunting of radish seedling. Streptomyces spp. causing CS on potato in Uruguay were found to represent a range of different species by virtue of their diverse morphological and physiological traits as well as rep-PCR, rpoB phylogenetic analysis, and multi-locus sequences analysis. We identified isolates primarily as Streptomyces scabiei, S. acidiscabies, and S. europaeiscabiei. However, some of the pathogenic isolates still remain to be identified at the species level. This highlights the need for improved methods for discrimination among pathogenic Streptomyces species. The presence of Streptomyces pathogenicity island (PAI) genes was analyzed, including genes encoding for thaxtomin synthetase (txtA, txtB), tomatinase (tomA), and a necrosis protein (nec1). Among the isolates that were pathogenic, 50% contained the four pathogenicity genes, 33% had an atypical composition of PAI marker genes, and 17% did not contain any genes. The absence of the genes reported to be involved in thaxtomin biosynthesis (txtA, txtB) was confirmed by whole-genome sequencing of two representative strains of this group. This finding suggests the participation of other virulence factors in plant pathogenicity.

Susceptibility to rifaximin and other antimicrobials of bacteria isolated in patients with acute gastrointestinal infections in Southeast Mexico. / Susceptibilidad a la rifaximina y otros antimicrobianos de bacterias aisladas en pacientes con infecciones gastrointestinales agudas en el sureste de México.

INTRODUCTION: Enteropathogenic bacteria isolated in Mexico City have shown a high rate of resistance to different antibiotics, with the exception of rifaximin (RIF). RIF is a nonabsorbable antibiotic that reaches high fecal concentrations (≈ 8,000µg/g). Susceptibility to antimicrobials can vary in different geographic regions. AIM: To study the susceptibility to rifaximin and other antimicrobials of enteropathogenic bacteria isolated in patients with acute diarrhea in the southeastern region of Mexico. MATERIAL AND METHODS: A total of 614 strains of bacteria isolated from patients with acute diarrhea from 4 cities in Southeast Mexico were analyzed. An antibiogram with the following antibiotics was created: ampicillin (AMP), trimethoprim/sulfamethoxazole (T-S), neomycin (NEO), furazolidone (FUR), ciprofloxacin (CIP), chloramphenicol (CHL), and fosfomycin (FOS), assessed through the agar diffusion method at the standard concentrations recommended by the Clinical and Laboratory Standards Institute (CLSI) and the American Society for Microbiology (ASM), and RIF, assessed through microdilution at 4 concentrations. RESULTS: The bacteria were Escherichia coli (55%), as the majority, in all its pathogenic variants, Shigella (16.8%), Salmonella (15.3%), Aeromonas (7.8%), and less than 5% Campylobacter, Yersinia, Vibrio, and Plesiomonas. The accumulated overall susceptibility to RIF was 69.1, 90.8, 98.9, and 100% at concentrations of 100, 200, 400, and 800µg/ml, respectively. Overall susceptibility to other antibiotics was FOS 82.8%, CHL 76.8%, CIP 73.9%, FUR 64%, T-S 58.7%, NEO 55.8%, and AMP 23.8%. Susceptibility to RIF at 400 and 800µg was significantly greater than with the other antimicrobials (P<.001). CONCLUSIONS: The data of the present study were similar to those of a previous study carried out in Mexico City: susceptibility to RIF in > 98% of the bacterial strains and a high frequency of resistance to several common antimicrobials.

[The role of pulmonary hypertension on bronchopulmonary dysplasia]. / El rol de la hipertensión pulmonar en la displasia broncopulmonar.

50 years ago, Northway described Broncopulmonary Dysplasia (BPD) in preterm infants exposed to mechanical ventilation. Since then, their survival has increased, nevertheless a "new BPD" has appeared and its incidence has not diminished. One of the characteristics of this pathology is the the abnormal vascular remodeling, which in its most severe expression is known as Pulmonary Hyper tension (PH); with an incidence of 17% in patients with BPD, which is proportional to the severity of the disease (33% in severe BPD), and as mortality factor (up to 48% 2-year mortality in PH-BPD). Thereby, it is important to know the diagnostic methods and therapeutic alternatives, topics discus sed in this review. Considering the high mortality in BPD associated PH, screening strategies in at risk population become important. The gold standard is cardiac catheterization; however, transtho-rathic echocardiography is a useful tool for the screening and diagnosis of PH in displasic patients, using cuantitive measures and cualitative changes in the evaluation. Seric type-B natriuretic peptide has shown to be useful for follow-up; regarding images, CT scan is used in severe cases. In terms of therapy; inhaled Nitric Oxide as a pulmonary vasodilator, phosphodiesterase inhibitors -sildenafil-, endotelin antagonists -bosentan-, and prostacyclin analogues -iloprost-, have been proposed. Their use, dosis and treatment lenght still lack support of high quality evidence, but diverse clinical expe riences have been described. Interdisciplinary care is also important, highlighting to optimize nu trition. Therefore, the challenge is to effectively prevent BPD and its complications. A PH screening protocol should be associated with risk stratification and treatment guidelines.

Mitochondrial ATP is required for the maintenance of membrane integrity in stallion spermatozoa, whereas motility requires both glycolysis and oxidative phosphorylation.

To investigate the hypothesis that oxidative phosphorylation is a major source of ATP to fuel stallion sperm motility, oxidative phosphorylation was suppressed using the mitochondrial uncouplers CCCP and 2,4,-dinitrophenol (DNP) and by inhibiting mitochondrial respiration at complex IV using sodium cyanide or at the level of ATP synthase using oligomycin-A. As mitochondrial dysfunction may also lead to oxidative stress, production of reactive oxygen species was monitored simultaneously. All inhibitors reduced ATP content, but oligomycin-A did so most profoundly. Oligomycin-A and CCCP also significantly reduced mitochondrial membrane potential. Sperm motility almost completely ceased after the inhibition of mitochondrial respiration and both percentage of motile sperm and sperm velocity were reduced in the presence of mitochondrial uncouplers. Inhibition of ATP synthesis resulted in the loss of sperm membrane integrity and increased the production of reactive oxygen species by degenerating sperm. Inhibition of glycolysis by deoxyglucose led to reduced sperm velocities and reduced ATP content, but not to loss of membrane integrity. These results suggest that, in contrast to many other mammalian species, stallion spermatozoa rely primarily on oxidative phosphorylation to generate the energy required for instance to maintain a functional Na+/K+ gradient, which is dependent on an Na+-K+ antiporter ATPase, which relates directly to the noted membrane integrity loss. Under aerobic conditions, however, glycolysis also provides the energy required for sperm motility.

Susceptibility of bacteria isolated from acute gastrointestinal infections to rifaximin and other antimicrobial agents in Mexico.

BACKGROUND: Bacterial resistance may hamper the antimicrobial management of acute gastroenteritis. Bacterial susceptibility to rifaximin, an antibiotic that achieves high fecal concentrations (up to 8,000µg/g), has not been evaluated in Mexico. OBJECTIVE: To determine the susceptibility to rifaximin and other antimicrobial agents of enteropathogenic bacteria isolated from patients with acute gastroenteritis in Mexico. MATERIAL AND METHODS: Bacterial strains were analyzed in stool samples from 1,000 patients with diagnosis of acute gastroenteritis. The susceptibility to rifaximin (RIF) was tested by microdilution (<100, <200, <400 and <800µg/ml) and susceptibility to chloramphenicol (CHL), trimethoprim-sulfamethoxazole (T-S), neomycin (NEO), furazolidone (FUR), fosfomycin (FOS), ampicillin (AMP) and ciprofloxacin (CIP) was tested by agar diffusion at the concentrations recommended by the Clinical & Laboratory Standards Institute and the American Society for Microbiology. RESULTS: Isolated bacteria were: enteropathogenic Escherichia coli (E. coli) (EPEC) 531, Shigella 120, non-Typhi Salmonella 117, Aeromonas spp. 80, enterotoxigenic E. coli (ETEC) 54, Yersinia enterocolitica 20, Campylobacter jejuni 20, Vibrio spp. 20, Plesiomonas shigelloides 20, and enterohemorrhagic E. coli (EHEC 0:157) 18. The overall cumulative susceptibility to RIF at <100, <200, <400, and <800µg/ml was 70.6, 90.8, 99.3, and 100%, respectively. The overall susceptibility to each antibiotic was: AMP 32.2%, T-S 53.6%, NEO 54.1%, FUR 64.7%, CIP 67.3%, CLO 73%, and FOS 81.3%. The susceptibility to RIF <400 and RIF <800µg/ml was significantly greater than with the other antibiotics (p<0.001). CONCLUSIONS: Resistance of enteropathogenic bacteria to various antibiotics used in gastrointestinal infections is high. Rifaximin was active against 99-100% of these enteropathogens at reachable concentrations in the intestine with the recommended dose.

Caspase activation, hydrogen peroxide production and Akt dephosphorylation occur during stallion sperm senescence.

To investigate the mechanisms inducing sperm death after ejaculation, stallion ejaculates were incubated in BWW media during 6 h at 37°C. At the beginning of the incubation period and after 1, 2, 4 and 6 h sperm motility and kinematics (CASA), mitochondrial membrane potential and membrane permeability and integrity were evaluated (flow cytometry). Also, at the same time intervals, active caspase 3, hydrogen peroxide, superoxide anion (flow cytometry) and Akt phosphorylation (flow cytometry) were evaluated. Major decreases in sperm function occurred after 6 h of incubation, although after 1 h decrease in the percentages of motile and progressive motile sperm occurred. The decrease observed in sperm functionality after 6 h of incubation was accompanied by a significant increase in the production of hydrogen peroxide and the greatest increase in caspase 3 activity. Additionally, the percentage of phosphorylated Akt reached a minimum after 6 h of incubation. These results provide evidences that sperm death during in vitro incubation is largely an apoptotic phenomena, probably stimulated by endogenous production of hydrogen peroxide and the lack of prosurvival factors maintaining Akt in a phosphorylated status. Disclosing molecular mechanisms leading to sperm death may help to develop new strategies for stallion sperm conservation.

Identification of apoptotic bodies in equine semen.

Apoptosis in the testis is required to ensure an efficient spermatogenesis. However, sometimes, defective germ cells that are marked for elimination during this process escape elimination in the testes, giving rise to ejaculates with increased percentages of abnormal and apoptotic spermatozoa and a high percentage of apoptotic bodies. Apoptosis markers in the ejaculate have been associated with low fertility, either in animals or humans. Therefore, the goal of this study was to investigate whether fresh equine semen contains apoptotic bodies [initially named Merocyanine 540 (M540) bodies] and to study the relationship between the quantity of these bodies and cell concentration, the volume of ejaculate, viability and motility. Moreover, we also studied whether the presence apoptotic bodies in fresh semen was related to the resistance of the stallion spermatozoa to being incubated at 37 °C or being frozen and thawed. Fresh equine semen was stained with fluorescent dyes such as M540 and Annexin-V. Active Caspase 3 was studied in fresh semen through Western blotting and immunofluorescence with a specific antibody. Sperm kinematics was assessed in fresh, incubated and thawed samples using computer-assisted semen analysis, and viability was evaluated with the LIVE/DEAD Sperm Viability Kit. Overall, our results demonstrate for the first time the presence of apoptotic bodies in equine semen. The quantity of apoptotic bodies was highly variable among stallions and was positively correlated with Caspase 3 activity in fresh samples and negatively correlated with the viability and motility of stallion spermatozoa after the cryopreservation process.

High-Resolution Transcriptomic Landscape of the Human Submandibular Gland.

Saliva-secreting and transporting cells are part of the complex cellular milieu of the human salivary gland, where they play important roles in normal glandular physiology and diseased states. However, comprehensive molecular characterization, particularly at single-cell resolution, is still incomplete, in part due to difficulty in procuring normal human tissues. Here, we perform an in-depth analysis of male and female adult human submandibular gland (SMG) samples by bulk RNA sequencing (RNA-seq) and examine the molecular underpinnings of the heterogeneous cell populations by single-cell (sc) RNA-seq. Our results from scRNA-seq highlight the remarkable diversity of clusters of epithelial and nonepithelial cells that reside in the SMG that is also faithfully recapitulated by deconvolution of the bulk-RNA data sets. Our analyses reveal complex transcriptomic heterogeneity within both the ductal and acinar subpopulations and identify atypical SMG cell types, such as mucoacinar cells that are unique to humans and ionocytes that have been recently described in the mouse. We use CellChat to explore ligand-receptor interactome predictions that likely mediate crucial cell-cell communications between the various cell clusters. Finally, we apply a trajectory inference method to investigate specific cellular branching points and topology that offers insights into the dynamic and complex differentiation process of the adult SMG. The data sets and the analyses herein comprise an extensive wealth of high-resolution information and a valuable resource for a deeper mechanistic understanding of human SMG biology and pathophysiology.

Influence of shell thickness on the thermal stability and melting-like behavior of Al@Fe core-shell nanoparticles from atomistic simulations: a structural and dynamic description.

Core-shell nanoparticles (CSNPs) are a class of functional materials that have received important attention nowadays due to their adjustable properties by a controlled tuning of the core or shell. Understanding the thermal response and structural properties of these CSNPs is relevant to carrying out an analysis regarding their synthesis and application at the nanoscale. The present work is aimed to investigate the shell thickness effect on thermal stability and melting behavior of Al@Fe CSNPs by using molecular dynamics simulations. The results are discussed considering the influence of the Fe shell on the Al nanoparticle and analyzing the effect of different shell thicknesses in Al@Fe CSNPs. In general, calorific curves show a smooth energy decline for temperatures greater than room temperature for different shell thicknesses and sizes, corresponding to the inward and outward atomic movement of Al and Fe atoms, respectively, that produce a mixed Al-Fe nanoalloy. Here, the thermal stability of the Al@Fe nanoparticle is gradually lost passing to a liquid-Al@solid-Fe configuration and reaching a mixed Al-Fe state by an exothermic mechanism. Combining quantities of the atomic diffusion and structural identification, a stepped structural transition of the system is subsequently observed, where the melting-like point was estimated. Furthermore, it is observed that the Al@Fe CSNPs with greater stability are obtained with a thick shell and a large size. The ability to control shell thickness and vary the size opens up attractive opportunities to synthesize a broad range of new materials with tunable catalytic properties.

[Caso clínico: síndrome de DRESS por hidroxicloroquina].

Background: DRESS syndrome (Drug reaction with eosinophilia and systemic symptoms) is an idiosyncratic reaction characterized by peripheral eosinophilia and systemic symptoms: fever, exanthema, lymphadenopathy, hepatitis, atypical lymphocytes and elevated liver enzymes. The incidence is 1 per 10,000 exposures, mortality 10-20%. Treatment is based on suspension of the suspected drug and steroids. Case report: A 42-year-old male with the following important antecedents. AHF: mother and father with Diabetes Mellitus type 2. APP: Arterial Hypertension, Diabetes Mellitus type 2, and bee sting allergy. Current Condition: He started 8 days after ingestion of hydroxychloroquine for probable SARS-COV-2 infection, with headache, facial and neck edema, desquamative dermatosis on trunk and upper extremities, went to private clinic with torpid evolution sent to third level for increased facial and neck edema, which merited orotracheal intubation, management with intravenous steroids and antihistamines. Labs on admission: Leukocytes 20090, platelets 322 thousand, eosinophilia (5%), elevated liver enzymes and acute kidney injury, fulfilling J-SCAR criteria. The patient was discharged due to adequate evolution with follow-up by Allergy and Clinical Immunology, the patient persists with desquamative lesions after 4 weeks and normalization of laboratory parameters. Conclusions: DRESS is a delayed adverse reaction. It is important the diagnostic presumption and the causal relationship with the drugs due to the high mortality rate.

Antecedentes: El síndrome DRESS (Drug reaction with eosinophilia and systemic symptoms) es una reacción idiosincrática, se caracteriza por eosinofilia perifé- rica y síntomas sistémicos: fiebre, exantema, linfadenopatía, hepatitis, linfocitos atípicos y elevación de enzimas hepáticas. La incidencia es de 1 por cada 10,000 exposiciones, mortalidad de 10 a 20%. El tratamiento se basa en la suspensión del fármaco sospechoso y en la aplicación de esteroides. Reporte de caso: Masculino de 42 años con los siguientes antecedentes de importancia. AHF: madre y padre con Diabetes Mellitus tipo 2. APP: Hipertensión Arterial, Diabetes Mellitus tipo 2, y alergia a picadura de abeja. Padecimiento Actual: Lo inicia posterior a 8 días tras la ingesta de hidroxicloroquina por probable infección por SARS-COV-2, con cefalea, edema facial y de cuello, dermatosis descamativa en tronco y extremidades superiores, acude a clínica particular con evolución tórpida enviado a tercer nivel por aumento de edema facial y cuello, que amerito intubación orotraqueal, manejo con esteroides intravenosos y anti- histamínicos. Laboratorios a su ingreso: Leucocitos 20090, plaquetas 322 mil, eosinofilia (5%), elevación de enzimas hepáticas y lesión renal aguda, cumpliendo criterios J-SCAR. Se egresa por adecuada evolución con seguimiento por Alergia e Inmunología Clínica, el paciente persiste con lesiones descamativas posterior a 4 semanas y normalización de parámetros de laboratorios. Conclusión: DRESS es una reacción adversa retardada. Es importante la presunción diagnóstica y la relación causal con los fármacos por la alta tasa de morta- lidad.

Consequences of butylated hydroxytoluene in the freezing extender on post-thaw characteristics of stallion spermatozoa in vitro.

Ejaculates from six pure Spanish stallions were split, and one subsample frozen in a commercial extender supplemented with the lipid soluble antioxidant butylated hydroxytoluene (BHT), while the other subsample served as control. After at least 4 weeks of storage, samples were thawed and post-thaw sperm quality analysed: sperm motility and kinematics using a CASA system, membrane and acrosome integrity and mitochondrial membrane potential using flow cytometry. The outcome of cryopreservation varied significantly among stallions. However, the supplementation with 1 mm BHT had no significant effect on any of the sperm parameters evaluated post-thaw.

The membrane of the mammalian spermatozoa: much more than an inert envelope.

Sperm plasma membrane is a very important structure that functions to protect sperm against extracellular injuries and to respond to physiological challenges. It plays a crucial role during sperm capacitation, in sperm-egg interaction and, finally, in fertilization. Concerning sperm technology, possibly the most important factors causing damage in mammalian spermatozoa membranes are initiated by the osmotic stress generated by dehydration of the cells during freezing and thawing. These changes are rapidly derived to the plasma and organelle membranes that gradually experiment loss of membrane architecture, causing unbalanced production of reactive oxygen species and increased lipid peroxidation. Other procedures such as sperm sorting or liquid storage of sperm also induce harmful changes in the integrity of the membrane. The specific composition of lipids of the sperm membranes may provide clues for understanding the mechanisms behind the differences found in the response to stress in different species. In the present review, we deal with the composition, architecture and organization of the sperm plasma membrane, emphasizing the factors that can affect membrane integrity. The intracellular signalling pathways related with membrane reorganization during capacitation and acrosome reaction are also reviewed.

Dimethylformamide improves the in vitro characteristics of thawed stallion spermatozoa reducing sublethal damage.

A total of 42 ejaculates were used in the experiment; six ejaculates per stallion, obtained from seven Pure Spanish stallions (PRE), were split and frozen in freezing media with different concentrations and combinations of cryoprotectant (CPA): (i) Cáceres (skim milk based extender) containing 2.5% glycerol (2.5GL), (ii) Cáceres containing 1.5% glycerol and 1.5% dimethylformamide (1.5%GL-1.5%DMFA), (iii) Cáceres extender supplemented with 1.5% glycerol and 2.5% dimethylformamide (1.5%GL-2.5%DMFA) and (iv) Cáceres extender supplemented with 4% dimethylformamide (4%DMFA). After at least 4 weeks of storage in liquid nitrogen (LN), straws were thawed and semen analysed by computer-assisted sperm analysis and flow cytometry (membrane lipid architecture (Merocyanine 540), integrity and sublethal damage (YoPro-1) and mitochondrial membrane potential (JC-1)). After thawing, better results were observed in samples frozen in 4%DMFA or in combinations of 1.5%GL-2.5%DMFA, in fact total motility increased by 16% in the 4%DMFA group compared to 2.5%GL (P < 0.05). Also, there was an increment in the percentage of progressive motile sperm in the 1.5%GL-2.5%DMFA group (9.8% 2.5GL vs 19% in the 1.5%GL-2.5%DMFA group p < 0.05); also, samples frozen in the 4%DMFA group had more intact (YoPro-1 negative) sperm post-thawing, 29.3% in 2.5%GL vs 36.7% in 4%DMFA group (p < 0.05). Membrane lipid architecture was not affected by any of the cryoprotectants tested, while samples frozen in 4%DFMA had a lower percentage of mitochondria with lower membrane potential. It is concluded that DMFA improves the outcome of cryopreservation of stallion spermatozoa mainly reducing sublethal cryodamage.

Fermentation conditions for yeast selection and effect of yeast-bacterial interaction in developing a starter culture for tequila fermentation.

Similar to other beverages, tequila fermentation can be improved using selected native strains. During fermentation, yeast and bacteria frequently act together and can improve product quality. However, their influence during tequila fermentation is not fully understood. Three Saccharomyces cerevisiae strains isolated in a previous study were used to determine their fermentation parameters. Fermentation of agave juice by a selected yeast strain in the presence of seven native bacterial species (individually and in consortium) was also evaluated. Optimal temperature, initial fructose, and pH were determined using a rotatory central composite design, and concomitant fermentative parameters were used to select the best tequila yeast strain. The yeast strain Teq-199 presented the best fructose consumption (91.0%), ethanol production (33.5 g/L), and yield (72%), as well as produced low concentrations of acetic acid (0.2 g/L). The optimal fermentation temperature was 32°C, similar to that used at distilleries. During fermentation of agave juice by strain Teq-199 in the presence of individual native bacteria, the yeast dominated fermentation, while bacterial species impaired its quality due to lactic acid production (>3.3 g/L). In the presence of a bacterial consortium, strain Teq-199 also dominated fermentation; however, a high concentration of acetic acid (6.5 g/L) was generated, reducing the quality of the fermentation parameters. A comparison with a commercial wine strain K1-V1116, revealed that the strain Teq-199 exhibited the best fermentation parameters, indicating its potential use as an inoculant in industrial processing. Since bacteria were detrimental, distilleries should exert efforts to reduce their impact. PRACTICAL APPLICATION: The optimal fermentation conditions for pre-selected yeast strains isolated during tequila production were determined, which led to the selection of the best-adapted yeast strain to fulfill the actual requirements and conditions in the tequila industry. This study allows the selection of yeast strains that could be used by local producers. In addition, this yeast was able to overcome a well-adapted bacterial consortium, showing dominance throughout the fermentation process. This study is unique since it explored bacterial interactions during fermentation process and proposes a method to assess the effect of these concomitant microorganisms to properly select and design a starter culture.

Membrane lipids of the stallion spermatozoon in relation to sperm quality and susceptibility to lipid peroxidation.

Lipids were extracted from ejaculated spermatozoa from seven individual stallions to distinguish neutral lipids (NL) and polar lipids (PL) and determine their variation among stallions and their relationship with sperm quality and sperm susceptibility to lipid peroxidation. The isolated fatty acids were correlated with sperm quality (membrane integrity, mitochondrial membrane potential (ΔΨm) and expression of active caspases) and the sensitivity of the sperm plasma membrane to LPO. The miristic (C14: 0), palmitic (C16: 0), stearic (C18: 0) and oleic (C18: 1n9) acids were predominant among the NLs. Within the phospholipid fraction, the docosapentanoic acid (C22: 5n6) was dominant, albeit varying among stallions. Surprisingly, the percentage of polyunsaturated fatty acids was positively correlated with sperm quality and a low propensity for LPO, probably because these particular fatty acids provide a higher fluidity of the plasma membrane. The stallion showing the poorest sperm membrane integrity plus a high level of LPO in his ejaculate had a lower percentage (p<0.05) of this fatty acid in his sperm plasma membranes.