Structural basis of terephthalate recognition by solute binding protein TphC.

Biological degradation of Polyethylene terephthalate (PET) plastic and assimilation of the corresponding monomers ethylene glycol and terephthalate (TPA) into central metabolism offers an attractive route for bio-based molecular recycling and bioremediation applications. A key step is the cellular uptake of the non-permeable TPA into bacterial cells which has been shown to be dependent upon the presence of the key tphC gene. However, little is known from a biochemical and structural perspective about the encoded solute binding protein, TphC. Here, we report the biochemical and structural characterisation of TphC in both open and TPA-bound closed conformations. This analysis demonstrates the narrow ligand specificity of TphC towards aromatic para-substituted dicarboxylates, such as TPA and closely related analogues. Further phylogenetic and genomic context analysis of the tph genes reveals homologous operons as a genetic resource for future biotechnological and metabolic engineering efforts towards circular plastic bio-economy solutions.

Genetically encoded biosensors for lignocellulose valorization.

Modern society is hugely dependent on finite oil reserves for the supply of fuels and chemicals. Moving our dependence away from these unsustainable oil-based feedstocks to renewable ones is, therefore, a critical factor towards the development of a low carbon bioeconomy. Lignin derived from biomass feedstocks offers great potential as a renewable source of aromatic compounds if methods for its effective valorization can be developed. Synthetic biology and metabolic engineering offer the potential to synergistically enable the development of cell factories with novel biosynthetic routes to valuable chemicals from these sustainable sources. Pathway design and optimization is, however, a major bottleneck due to the lack of high-throughput methods capable of screening large libraries of genetic variants and the metabolic burden associated with bioproduction. Genetically encoded biosensors can provide a solution by transducing the target metabolite concentration into detectable signals to provide high-throughput phenotypic read-outs and allow dynamic pathway regulation. The development and application of biosensors in the discovery and engineering of efficient biocatalytic processes for the degradation, conversion, and valorization of lignin are paving the way towards a sustainable and economically viable biorefinery.

[Causes of non-use of postpartum contraceptive method among adolescent mothers]. / Causas de no uso de método anticonceptivo posparto entre madres adolescentes.

OBJECTIVE: To determine the causes of non postpartum contraceptive use among adolescent mothers. PATIENTS AND METHODS: We conducted a cross-section descriptive study. We included women who asked for attention of an obstetric event in 2002, we identified those were in immediate postpartum period, and we selected those that did not began a birth-control method. Data were collected directly with an interview and revision of the file, later on they were coded and processed manually; the causes of non contraceptive use were classified in: attributable causes to patient: personal, religious, moral, familiar, cultural, etc. Reasons, when they received information and advice or when they did not assist to educational actions; attributable causes to hospital: technique administrative factors, insufficient educational communication activities by service provider; and attributable causes to medical indication: presence of risk factors for health women. The statistical analysis was carried out using frequencies and percentages. RESULTS: We found 261 women, we identified 160 (61%) in immediate postpartum period, 52 (32%) they did not began contraceptive use. CONCLUSION: The causes of non postpartum contraceptive use among adolescent mothers were attributable to themselves in 75%, in 21% to the medical unit, and 4% to medical indication.

[Causes of non-use of contraceptives in the immediate postpartum period]. / Causas de no uso de anticonceptivo durante el periodo posparto inmediato.

OBJECTIVE: To determine the causes of not use of contraceptive during immediate postpartum period. METHODOLOGY: Cross-section observational descriptive study. We include women that went for attention of obstetric event, we identified those were in immediate postpartum period, and we selected the women which not started contraceptive use. Data were collected directly with an interview; the causes of not use of contraceptive were classified in three groups. Group I: causes be derived by patient: personal, religious, moral, families, culture, etc. reasons, when they received information, and advice or when they did not attend to educational actions. Group II: causes be derived by the hospital: technique administrative factors, insufficient educational communication activities by service provider. Group III: Medic Indication: presence of risk factors for health women. We found 2,593 women, we identified 1,493 (57.5%) in immediate postpartum period, 478 (32%) not started contraceptive use. In 349 (73%) women the causes were group I, in 91 (19%) group II, and 38 (8%) group III. CONCLUSION: Is necessary more research to know users concerns, ideas and perspectives in relation with methods of contraception, contraceptive counseling, informants, advisers, and with health service institution, to improve educational communication strategies; and to unify medical criterions for not use contraceptive during immediate postpartum period.