A Novel Strategy to Construct Yeast Saccharomyces cerevisiae Strains for Very High Gravity Fermentation

Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes

Retinoic Acid-Dependent Signaling Pathways and Lineage Events in the Developing Mouse Spinal Cord

Studies in avian models have demonstrated an involvement of retinoid signaling in early neural tube patterning. The roles of this signaling pathway at later stages of spinal cord development are only partly characterized. Here we use Raldh2-null mouse mutants rescued from early embryonic lethality to study the consequences of lack of endogenous retinoic acid (RA) in the differentiating spinal cord. Mid-gestation RA deficiency produces prominent structural and molecular deficiencies in dorsal regions of the spinal cord. While targets of Wnt signaling in the dorsal neuronal lineage are unaltered, reductions in Fibroblast Growth Factor (FGF) and Notch signaling are clearly observed. We further provide evidence that endogenous RA is capable of driving stem cell differentiation. Raldh2 deficiency results in a decreased number of spinal cord derived neurospheres, which exhibit a reduced differentiation potential. Raldh2-null neurospheres have a decreased number of cells expressing the neuronal marker β-III-tubulin, while the nestin-positive cell population is increased. Hence, in vivo retinoid deficiency impaired neural stem cell growth. We propose that RA has separable functions in the developing spinal cord to (i) maintain high levels of FGF and Notch signaling and (ii) drive stem cell differentiation, thus restricting both the numbers and the pluripotent character of neural stem cells

Epigenetic regulation of centromeric chromatin: old dogs, new tricks?

The assembly of just a single kinetochore at the centromere of each sister chromatid is essential for accurate chromosome segregation during cell division. Surprisingly, despite their vital function, centromeres show considerable plasticity with respect to their chromosomal locations and activity. The establishment and maintenance of centromeric chromatin, and therefore the location of kinetochores, is epigenetically regulated. The histone H3 variant CENP-A is the key determinant of centromere identity and kinetochore assembly. Recent studies have identified many factors that affect CENP-A localization, but their precise roles in this process are unknown. We build on these advances and on new information about the timing of CENP-A assembly during the cell cycle to propose new models for how centromeric chromatin is established and propagated

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Presentación clínica, diagnóstico y evolución a largo plazo en 29 pacientes con enfermedad de Wilson Clinical presentation, diagnosis, and long-term outcome of 29 patients with Wilson's disease

Objetivo: analizar las características clínicas, el tratamiento y evolución de los pacientes diagnosticados de enfermedad de Wilson (EW) en la región de Murcia. Pacientes y método: se realizó un análisis retrospectivo de las historias clínicas de los 29 pacientes (edad media &plusmn; DE, 20,3 &plusmn; 13,4 años) con EW diagnosticados en los últimos 16 años. Resultados: el motivo de consulta más frecuente fue el descubrimiento de transaminasas elevadas, en casi la mitad de los pacientes, seguido de temblor o distonía en el 17% respectivamente. El anillo de Kayser-Fleischer se objetivó en 17 de los 29 (58,6%) pacientes (100% de los pacientes con afectación neurológica pura y en el 35,3% de los pacientes con clínica hepática pura; p < 0,001). Los niveles de cobre total en sangre y no unido a ceruloplamina, así como los niveles de cupruria fueron significativamente superiores en los pacientes con síntomas neurológicos y en aquellos con cirrosis hepática, en el momento del diagnóstico. Con D-penicilamina o trientina permanecieron estables o mejoraron durante el periodo de seguimiento 18 pacientes (62%), mientras que 11 pacientes (38%) empeoraron. Diez pacientes fueron sometidos a trasplante hepático. Conclusiones: en nuestra región, los pacientes con EW fueron diagnosticados en edades jóvenes y en la mayoría de casos por enfermedad predominantemente hepática. Los pacientes con enfermedad neurológica o con cirrosis hepática tuvieron cifras más elevadas de cobre libre no unido a ceruloplasmina y de cupruria. La enfermedad evolucionó favorablemente en todos los pacientes excepto en aquellos que fueron diagnosticados con enfermedad hepática o neurológica avanzada.<br>Objective: to analyze the clinical characteristics, treatment, and follow-up of a cohort of 29 patients with Wilson's disease (WD) within the region of Murcia. Patients and method: we reviewed the medical records of 29 cases of WD (mean age, 20.3 &plusmn; 13.4 years) diagnosed during the last 16 years. Results: the most frequent reason for consultation was upon discovering a high transaminase level in almost half the patients, followed by tremors or dystonia in 17% of patients, respectively. A Kayser-Fleischer ring was observed in 17/29 (58.6%) of patients (100% of patients with pure neurological involvement and 35% of patients with pure clinical hepatic disease; p < 0.001). Blood copper levels not associated with ceruloplasmin as well as cupruria were notably superior in patients with neurological symptoms and in those with liver cirrhosis at the time of diagnosis. Patient clinical symptoms remained stable with D-penicillamine or trientine, or improved during the observation period, for 18 out of 29 patients (62%), while 11 out of 29 patients (38%) got worse. Conclusions: in our region patients with WD are diagnosed at a younger age, and in most cases for hepatic disease. Patients with neurological disease o liver cirrhosis had a high level of free copper not associated to ceruloplasmin and cupruria. The disease had a favorable evolution in all patients but those diagnosed with hepatic disease or advanced neurological disease

Printed Disposable Colorimetric Array for Metal Ion Discrimination

One of the main limiting factors in optical sensing arrays is the reproducibility in the preparation, typically by spin coating and drop casting techniques, which produce membranes that are not fully homogeneous. In this paper, we increase the discriminatory power of colorimetric arrays by increasing the reproducibility in the preparation by inkjet printing and measuring the color from the image of the array acquired by a digital camera, using the H coordinate of the HSV color space as the analytical parameter, which produces robust and precise measurements. A disposable 31 mm × 19 mm nylon membrane with 35 sensing areas with 7 commercial chromogenic reagents makes it possible to identify 13 metal ions and to determine mixtures with up to 5 ions using a two-stage neural network approach with higher accuracy than with previous approaches