Targeted Inactivation of the mecB Gene, Encoding Cystathionine-γ-Lyase, Shows that the Reverse Transsulfuration Pathway Is Required for High-Level Cephalosporin Biosynthesis inAcremonium chrysogenum C10 but Not for Methionine Induction of the Cephalosporin Genes

[EN] Targeted gene disruption efficiency in Acremonium chrysogenum was increased 10-fold by applying the double-marker enrichment technique to this filamentous fungus. Disruption of themecB gene by the double-marker technique was achieved in 5% of the transformants screened. Mutants T6 and T24, obtained by gene replacement, showed an inactive mecB gene by Southern blot analysis and no cystathionine-γ-lyase activity. These mutants exhibited lower cephalosporin production than that of the control strain, A. chrysogenum C10, in MDFA medium supplemented with methionine. However, there was no difference in cephalosporin production between parental strain A. chrysogenum C10 and the mutants T6 and T24 in Shen's defined fermentation medium (MDFA) without methionine. These results indicate that the supply of cysteine through the transsulfuration pathway is required for high-level cephalosporin biosynthesis but not for low-level production of this antibiotic in methionine-unsupplemented medium. Therefore, cysteine for cephalosporin biosynthesis in A. chrysogenum derives from the autotrophic (SH2) and the reverse transsulfuration pathways. Levels of methionine induction of the cephalosporin biosynthesis gene pcbC were identical in the parental strain and the mecB mutants, indicating that the induction effect is not mediated by cystathionine-γ-lyase.SIThis work was supported by a grant of the CICYT (BIO97-0289-C02-01). We thank A. Paszewski for providing Aspergillus nidulansstrains M63 and C47 and M. Mediavilla, B. Martı́n, R. Barrientos, and M. Corrales for excellent technical assistance

Arsenic in Water Resources of the Southern Pampa Plains, Argentina

Confronted with the need for accessible sources of good quality water and in view of the fact that the threat to public health posed by arsenic occurs mainly through the ingestion of contaminated drinking water, the presence and distribution of arsenic was evaluated in the southern Pampa Plains of Bahía Blanca district in Argentina. The findings show variable concentrations of arsenic in a complex distribution pattern. Complementary information is provided on the behavior of the groundwater resource and its salinity in terms of dissolved ions. Groundwater is the most severely affected, 97% of the samples exceeding the guideline value for arsenic in drinking water as recommended by the WHO (Guidelines for Drinking Water Quality, 2004). and showing maximum concentrations of up to 0.30 mg/L. Informing those responsible for preventive medicine and alerting the community at large will facilitate measures to mitigate exposure and ensure the safety of drinking water

Influence of Cellulose Characteristics on Pyrolysis Suitability

: Cellulose is the most abundant component of biomass and the one that requires the most activation energy (Ea) for pyrolysis. In this study, the dependence of Ea on the intrinsic cellulose characteristics, such as the degree of polymerization (DP), crystallinity, and crystal size, was studied in different cellulose samples, including samples from Eucalyptus globulus, Ulmus minor, Linun usitatissimum, Olea europaea, Robinia pseudoacacia, and Populus alba. Then, to describe the pyrolytic degradation of cellulose, the Ozawa–Flynn–Wall kinetic method was the most appropriate among the isoconversional models studied. An acceptable quadratic relationship of R2 > 0.9 between the Ea values of the different cellulose samples with their corresponding DP, crystallinity index, and crystal size values was found. Therefore, low crystallinity and low-to-medium crystal size values are desired to obtain lower Ea values for cellulose pyrolysis. On the other hand, DP did not present a clear effect on Ea in the studied DP rangeThis research was funded by Comunidad de Madrid and MCIU/AEI/FEDER, EU via Projects SUSTEC-CM S2018/EMT-4348 and RTI2018-096080-B-C22, respectively, and the Regional Ministry of Innovation, Science and Enterprise, Government of the Junta de Andalucía (Operational Programme FEDER Andalusia 2014-2020. Project UHU-1255540), Spain Universidad de Jaén is acknowledged for Olea europaea material. Silviculture and Forest Management Department (Forest Research Center, INIA, CSIC) is acknowledged for Robinia pseudoacacia and Populus alba materials. We thank the personnel at Puerta de Hierro Forest Breeding Centre (Ministerio para la Transición Ecológica y el Reto Demográfico) and the Spanish Elm Breeding Program for providing the Ulmus minor material. Finally, La Montañesa pulp mill (Lecta Group, Spain) and Celesa (Spain) are acknowledged for Eucalyptus globulus and Linun usitatissimum materials, respectivel

The BTB-zinc finger transcription factor abrupt acts as an epithelial oncogene in drosophila melanogaster through maintaining a progenitor-like cell state

The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state

A-didactic situations for the theaching of axial symmetry by using cabri as a means

We present the first activity of a didactic engineering using the Theory of Didactic Situations for the design and experimentation of a-didactic situations with Cabri as ‘milieu’. The activity’s a priori and a posteriori analyses show that the interaction with the ‘milieu’ led students to the construction of intuitive knowledge about reflection.Presentamos la primera actividad de una ingeniería didáctica que utilizó la Teoría de las Situaciones Didácticas para la creación y experimentación de situaciones a-didácticas utilizando Cabri como medio. El análisis a priori y a posteriori de la actividad presentada permite concluir que la interacción con el medio condujo a que los alumnos construyeran conocimientos intuitivos relativos a la simetría axial.    &nbsp

Situaciones a-didácticas para la enseñanza de la simetría axial utilizando Cabri como medio

Presentamos la primera actividad de una ingeniería didáctica que utilizó la Teoría de las Situaciones Didácticas para la creación y experimentación de situaciones a-didácticas utilizando Cabri como medio. El análisis a priori y a posteriori de la actividad presentada permite concluir que la interacción con el medio condujo a que los alumnos construyeran conocimientos intuitivos relativos a la simetría axial.   

A-didactic situations for the theaching of axial symmetry by using cabri as a means

We present the first activity of a didactic engineering using the Theory of Didactic Situations for the design and experimentation of a-didactic situations with Cabri as ‘milieu’. The activity’s a priori and a posteriori analyses show that the interaction with the ‘milieu’ led students to the construction of intuitive knowledge about reflection.Presentamos la primera actividad de una ingeniería didáctica que utilizó la Teoría de las Situaciones Didácticas para la creación y experimentación de situaciones a-didácticas utilizando Cabri como medio. El análisis a priori y a posteriori de la actividad presentada permite concluir que la interacción con el medio condujo a que los alumnos construyeran conocimientos intuitivos relativos a la simetría axial.    &nbsp

Searching for climate change consensus in broadsheet newspapers. Editorial policy and public opinion

The premise behind this paper is that, in order to reach social consensus on climate change, there must be consensus on the media first. This research study focuses on the search for consensus values in the editorial discourses of five proven influential broadsheet newspapers in their context and internationally, such as The Guardian, Le Monde, El País, Frankfurter Allgemeine Zeitung and The New York Times. These newspapers have published 535 opinion editorials on climate change over a 14-year period: from the Kyoto Summit in 1997 to the Durban Climate Change Conference in 2011. The methodology involves both frames and quantitative analyses. This research aims to detect the main actors and factors that influence editorial discourse, as politics and economic sources are most likely to be predominant (H1), and draw lines of possible consensus among the different media analysed (H2). The analysis shows how the political and economic connotations in editorial discourses were sometimes to the detriment of scientific and expert discourse, and the differences among countries. However, the research also underscores essential positions in common, such as the acceptance of climate change and its anthropogenic origin, or the criticism of the states’ inability to reach joint solutions to the problem