DIEGO QUISPE MENDOZA - Academia.edu (original) (raw)
Papers by DIEGO QUISPE MENDOZA
En apoyo a la toma de decisiones empresariales que involucren múltiples criterios se usa con much... more En apoyo a la toma de decisiones empresariales que involucren múltiples criterios se usa con mucha frecuencia la metodología AHP Análisis Jerárquico de Procesos. En la literatura se encuentra evidencia empírica de la aplicación de la metodología AHP en cadenas de suministro en el tema de la logística inversa pero no en el fenómeno de Nearshoring/Offshoring. Esta investigación busca identificar qué factores inciden y su nivel de prioridad en el proceso de toma de decisiones relacionas con procesos de implementación de Nearshoring/Offshoring. Palabras-Clave: Cadenas de suministro globales, outsourcing, factores relevantes, AHP ABSTRACT:
ICIASF'97 Record. International Congress on Instrumentation in Aerospace Simulation Facilities
Quantitative pressure measurements can be acquired by pressure sensitive paint (PSP) instrumentat... more Quantitative pressure measurements can be acquired by pressure sensitive paint (PSP) instrumentation systems incorporating charge-coupled devices (CCD) for PSP photoluminescence image detection. However, intrinsic CCD noise corrupts the PSP image, manifesting in erroneous measurements of pressure and the corresponding coefficient of pressure (Cp). This manifestation is analyzed and quantified in terms of PSP image signal-to-noise ratio (SNR). The image acquisition
Journal of Bacteriology, 1983
Mutants of Escherichia coli K-12 deficient in pyruvate oxidase were isolated from an aceEF (pyruv... more Mutants of Escherichia coli K-12 deficient in pyruvate oxidase were isolated from an aceEF (pyruvate dehydrogenase-deficient) strain by selection for a complete absence of growth on medium lacking acetate. Extracts of two of the mutants were shown to contain normal levels of pyruvate oxidase antigen, although the enzymatic activities of the extracts were reduced or absent. The poxB locus was mapped by using closely linked transposon insertions to min 18.7 of the E. coli linkage map between the cmlA and aroA loci, a location far removed from that of the regulatory gene, poxA.
Journal of Bacteriology, 1982
A mutant of Escherichia coli has been characterized which overproduces cis -vaccenic acid in the ... more A mutant of Escherichia coli has been characterized which overproduces cis -vaccenic acid in the temperature range of 30 to 42°C. The mutational lesion acts within the fatty acid biosynthetic pathway rather than at the level of fatty acid incorporation into phospholipid.
Applied and Environmental Microbiology, 1998
Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrat... more Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrate permease P (CitP), which is encoded by the plasmidic citP gene. We have shown previously that citP is included in the citQRP operon, which is mainly transcribed from the P1 promoter in L. lactis subsp. lactis biovar diacetylactis. Furthermore, transcription of citQRP and citrate transport are not induced by the presence of citrate in the growth medium. In this work, we analyzed the influence of the extracellular pH on the expression of citP . The citrate transport system is induced by natural acidification of the medium during cell growth and by a shift to media buffered at acidic pHs. This inducible response to acid stress takes place at the transcriptional level and seems to be due to increased utilization of the P1 promoter. Increased transcription correlates with increased synthesis of CitP and results in higher citrate transport activity catalyzed by the cells. Finally, this acid ...
Applied and Environmental Microbiology, 1988
The shuttle plasmid pGK12, as well as several Staphylococcus aureus plasmids, was introduced into... more The shuttle plasmid pGK12, as well as several Staphylococcus aureus plasmids, was introduced into Streptococcus lactis by intergeneric protoplast fusion with Bacillus subtilis. The S. aureus plasmids were stably inherited in S. lactis, and so they may possibly be used as cloning vectors in lactic streptococci.
Journal of Bacteriology, 1999
Measurement of the flux through the citrate fermentation pathway in resting cells of Lactococcus ... more Measurement of the flux through the citrate fermentation pathway in resting cells of Lactococcus lactis CRL264 grown in a pH-controlled fermentor at different pH values showed that the pathway was constitutively expressed, but its activity was significantly enhanced at low pH. The flux through the citrate-degrading pathway correlated with the magnitude of the membrane potential and pH gradient that were generated when citrate was added to the cells. The citrate degradation rate and proton motive force were significantly higher when glucose was metabolized at the same time, a phenomenon that could be mimicked by the addition of lactate, the end product of glucose metabolism. The results clearly demonstrate that citrate metabolism in L. lactis is a secondary proton motive force-generating pathway. Although the proton motive force generated by citrate in cells grown at low pH was of the same magnitude as that generated by glucose fermentation, citrate metabolism did not affect the grow...
Journal of Bacteriology, 1999
The Bacillus subtilis des gene encodes the cold-inducible Δ5 lipid desaturase involved in the for... more The Bacillus subtilis des gene encodes the cold-inducible Δ5 lipid desaturase involved in the formation of unsaturated fatty acids from saturated phospholipid precursors. Here, we describe the expression pattern of the des gene in response to a temperature downshift from 37 to 20°C. We found that the synthesis of des mRNA is undetectable at 37°C but dramatically induced upon the temperature downshift. Decay characteristics of the des transcript as well as the in vivo decay of B. subtilis bulk mRNA were investigated. The results showed that the stability of the des transcript as well as of bulk mRNA lasted substantially longer at 20°C than at 37°C. Functional expression of des at 37°C was achieved by exchanging its promoter with the non-cold shock spac promoter. These data provide the first direct evidence that temperature-mediated control of transcription is the major mechanism regulating the mRNA levels of the B. subtilis desaturase. The present results also demonstrate that the on...
Universidad Colegio Mayor Nuestra Senora Del Rosario Universidad Del Rosario Edocur Repositorio Institucional Disponible En Http Repository Urosario Edu Co, Nov 11, 2014
Boletin Mexicano De Derecho Comparado, Aug 1, 2014
Microbiology, 2000
Sulphate permeases in the plasma membrane are responsible for uptake of environmental sulphate us... more Sulphate permeases in the plasma membrane are responsible for uptake of environmental sulphate used in the sulphate assimilation pathway in bacteria and plants. Here it is reported that the ORF designated cysP, located on the Bacillus subtilis chromosome between cysH and five putative genes involved in sulphate assimilation, encodes a sulphate permease. cysP is able to complement Escherichia coli cysteine auxotrophs with mutations affecting either the membrane or periplasmic components of the sulphate-thiosulphate permease. Transport studies with cell suspensions of a cysA97 E. coli strain transformed with a plasmid expressing the B. subtilis cysP gene indicated that CysP catalyses sulphate uptake. Analysis of the primary sequence showed that CysP (354 amino acids, estimated molecular mass 24 kDa) is a highly hydrophobic protein which has 11 putative transmembrane helices. Sequence comparisons revealed that CysP, together with the phosphate permease of Neurospora crassa, Pho-4, and E. coli PitA, belongs to the family of related transporters, the inorganic phosphate transporter (Pit) family. Among the putative phosphate permeases, CysP shows a similar size and the same domain organization as the archaeal transporters. This is the first report of a sulphate permease in a Gram-positive organism.
Proceedings of the National Academy of Sciences, 2015
Significance The ability to sense and respond to environmental signals is essential for cell surv... more Significance The ability to sense and respond to environmental signals is essential for cell survival. Unraveling the molecular mechanisms underlying signaling processes remains a challenge, however. Here we present a model for the mode of action of a bacterial thermosensor. The physical stimulus for activation appears to be a temperature-induced increase in membrane thickness, to which the sensor responds by elongation of its transmembrane helix. This leads to exposure of three serine residues on one side of the helix, inducing reorientation of adjacent helices to allow the formation of a serine zipper, which then acts as trigger for kinase activation. The reversible formation of a serine zipper represents a novel mechanism by which membrane-embedded sensors may detect and transmit signals.
Journal of bacteriology, 2004
Although Lactococcus is one of the most extensively studied lactic acid bacteria and is the parad... more Although Lactococcus is one of the most extensively studied lactic acid bacteria and is the paradigm for biochemical studies of citrate metabolism, little information is available on the regulation of the citrate lyase complex. In order to fill this gap, we characterized the genes encoding the subunits of the citrate lyase of Lactococcus lactis CRL264, which are located on an 11.4-kb chromosomal DNA region. Nucleotide sequence analysis revealed a cluster of eight genes in a new type of genetic organization. The citM-citCDEFXG operon (cit operon) is transcribed as a single polycistronic mRNA of 8.6 kb. This operon carries a gene encoding a malic enzyme (CitM, a putative oxaloacetate decarboxylase), the structural genes coding for the citrate lyase subunits (citD, citE, and citF), and the accessory genes required for the synthesis of an active citrate lyase complex (citC, citX, and citG). We have found that the cit operon is induced by natural acidification of the medium during cell g...
Annals of hepatology
Both prokaryotes and eukaryotes respond to a decrease in temperature with the expression of a spe... more Both prokaryotes and eukaryotes respond to a decrease in temperature with the expression of a specific subset of proteins. We are investigating how Bacillus subtilis cells sense and transduce low-temperature signals to adjust its gene expression. One important step has been accomplished in the dissection of a novel pathway for the adjustment of unsaturated fatty acid synthesis in B.subtilis, termed the Des pathway. It responds to a decrease in growth temperature by enhancing the expression of the des gene, coding for an acyl-lipid desaturase. The Des pathway is uniquely and stringently regulated by a tw-component system composed of a membrane-associated kinase, DesK, and a soluble transcriptional activator, DesR. The temperature sensing ability of the DesK protein is regulated by the extent of disorder within the membrane lipid bilayer. In this work, we present the mechanism by which the sensor protein DesK controls the signal decay of its cognate partner, DesR, and how this respons...
En apoyo a la toma de decisiones empresariales que involucren múltiples criterios se usa con much... more En apoyo a la toma de decisiones empresariales que involucren múltiples criterios se usa con mucha frecuencia la metodología AHP Análisis Jerárquico de Procesos. En la literatura se encuentra evidencia empírica de la aplicación de la metodología AHP en cadenas de suministro en el tema de la logística inversa pero no en el fenómeno de Nearshoring/Offshoring. Esta investigación busca identificar qué factores inciden y su nivel de prioridad en el proceso de toma de decisiones relacionas con procesos de implementación de Nearshoring/Offshoring. Palabras-Clave: Cadenas de suministro globales, outsourcing, factores relevantes, AHP ABSTRACT:
ICIASF'97 Record. International Congress on Instrumentation in Aerospace Simulation Facilities
Quantitative pressure measurements can be acquired by pressure sensitive paint (PSP) instrumentat... more Quantitative pressure measurements can be acquired by pressure sensitive paint (PSP) instrumentation systems incorporating charge-coupled devices (CCD) for PSP photoluminescence image detection. However, intrinsic CCD noise corrupts the PSP image, manifesting in erroneous measurements of pressure and the corresponding coefficient of pressure (Cp). This manifestation is analyzed and quantified in terms of PSP image signal-to-noise ratio (SNR). The image acquisition
Journal of Bacteriology, 1983
Mutants of Escherichia coli K-12 deficient in pyruvate oxidase were isolated from an aceEF (pyruv... more Mutants of Escherichia coli K-12 deficient in pyruvate oxidase were isolated from an aceEF (pyruvate dehydrogenase-deficient) strain by selection for a complete absence of growth on medium lacking acetate. Extracts of two of the mutants were shown to contain normal levels of pyruvate oxidase antigen, although the enzymatic activities of the extracts were reduced or absent. The poxB locus was mapped by using closely linked transposon insertions to min 18.7 of the E. coli linkage map between the cmlA and aroA loci, a location far removed from that of the regulatory gene, poxA.
Journal of Bacteriology, 1982
A mutant of Escherichia coli has been characterized which overproduces cis -vaccenic acid in the ... more A mutant of Escherichia coli has been characterized which overproduces cis -vaccenic acid in the temperature range of 30 to 42°C. The mutational lesion acts within the fatty acid biosynthetic pathway rather than at the level of fatty acid incorporation into phospholipid.
Applied and Environmental Microbiology, 1998
Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrat... more Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrate permease P (CitP), which is encoded by the plasmidic citP gene. We have shown previously that citP is included in the citQRP operon, which is mainly transcribed from the P1 promoter in L. lactis subsp. lactis biovar diacetylactis. Furthermore, transcription of citQRP and citrate transport are not induced by the presence of citrate in the growth medium. In this work, we analyzed the influence of the extracellular pH on the expression of citP . The citrate transport system is induced by natural acidification of the medium during cell growth and by a shift to media buffered at acidic pHs. This inducible response to acid stress takes place at the transcriptional level and seems to be due to increased utilization of the P1 promoter. Increased transcription correlates with increased synthesis of CitP and results in higher citrate transport activity catalyzed by the cells. Finally, this acid ...
Applied and Environmental Microbiology, 1988
The shuttle plasmid pGK12, as well as several Staphylococcus aureus plasmids, was introduced into... more The shuttle plasmid pGK12, as well as several Staphylococcus aureus plasmids, was introduced into Streptococcus lactis by intergeneric protoplast fusion with Bacillus subtilis. The S. aureus plasmids were stably inherited in S. lactis, and so they may possibly be used as cloning vectors in lactic streptococci.
Journal of Bacteriology, 1999
Measurement of the flux through the citrate fermentation pathway in resting cells of Lactococcus ... more Measurement of the flux through the citrate fermentation pathway in resting cells of Lactococcus lactis CRL264 grown in a pH-controlled fermentor at different pH values showed that the pathway was constitutively expressed, but its activity was significantly enhanced at low pH. The flux through the citrate-degrading pathway correlated with the magnitude of the membrane potential and pH gradient that were generated when citrate was added to the cells. The citrate degradation rate and proton motive force were significantly higher when glucose was metabolized at the same time, a phenomenon that could be mimicked by the addition of lactate, the end product of glucose metabolism. The results clearly demonstrate that citrate metabolism in L. lactis is a secondary proton motive force-generating pathway. Although the proton motive force generated by citrate in cells grown at low pH was of the same magnitude as that generated by glucose fermentation, citrate metabolism did not affect the grow...
Journal of Bacteriology, 1999
The Bacillus subtilis des gene encodes the cold-inducible Δ5 lipid desaturase involved in the for... more The Bacillus subtilis des gene encodes the cold-inducible Δ5 lipid desaturase involved in the formation of unsaturated fatty acids from saturated phospholipid precursors. Here, we describe the expression pattern of the des gene in response to a temperature downshift from 37 to 20°C. We found that the synthesis of des mRNA is undetectable at 37°C but dramatically induced upon the temperature downshift. Decay characteristics of the des transcript as well as the in vivo decay of B. subtilis bulk mRNA were investigated. The results showed that the stability of the des transcript as well as of bulk mRNA lasted substantially longer at 20°C than at 37°C. Functional expression of des at 37°C was achieved by exchanging its promoter with the non-cold shock spac promoter. These data provide the first direct evidence that temperature-mediated control of transcription is the major mechanism regulating the mRNA levels of the B. subtilis desaturase. The present results also demonstrate that the on...
Universidad Colegio Mayor Nuestra Senora Del Rosario Universidad Del Rosario Edocur Repositorio Institucional Disponible En Http Repository Urosario Edu Co, Nov 11, 2014
Boletin Mexicano De Derecho Comparado, Aug 1, 2014
Microbiology, 2000
Sulphate permeases in the plasma membrane are responsible for uptake of environmental sulphate us... more Sulphate permeases in the plasma membrane are responsible for uptake of environmental sulphate used in the sulphate assimilation pathway in bacteria and plants. Here it is reported that the ORF designated cysP, located on the Bacillus subtilis chromosome between cysH and five putative genes involved in sulphate assimilation, encodes a sulphate permease. cysP is able to complement Escherichia coli cysteine auxotrophs with mutations affecting either the membrane or periplasmic components of the sulphate-thiosulphate permease. Transport studies with cell suspensions of a cysA97 E. coli strain transformed with a plasmid expressing the B. subtilis cysP gene indicated that CysP catalyses sulphate uptake. Analysis of the primary sequence showed that CysP (354 amino acids, estimated molecular mass 24 kDa) is a highly hydrophobic protein which has 11 putative transmembrane helices. Sequence comparisons revealed that CysP, together with the phosphate permease of Neurospora crassa, Pho-4, and E. coli PitA, belongs to the family of related transporters, the inorganic phosphate transporter (Pit) family. Among the putative phosphate permeases, CysP shows a similar size and the same domain organization as the archaeal transporters. This is the first report of a sulphate permease in a Gram-positive organism.
Proceedings of the National Academy of Sciences, 2015
Significance The ability to sense and respond to environmental signals is essential for cell surv... more Significance The ability to sense and respond to environmental signals is essential for cell survival. Unraveling the molecular mechanisms underlying signaling processes remains a challenge, however. Here we present a model for the mode of action of a bacterial thermosensor. The physical stimulus for activation appears to be a temperature-induced increase in membrane thickness, to which the sensor responds by elongation of its transmembrane helix. This leads to exposure of three serine residues on one side of the helix, inducing reorientation of adjacent helices to allow the formation of a serine zipper, which then acts as trigger for kinase activation. The reversible formation of a serine zipper represents a novel mechanism by which membrane-embedded sensors may detect and transmit signals.
Journal of bacteriology, 2004
Although Lactococcus is one of the most extensively studied lactic acid bacteria and is the parad... more Although Lactococcus is one of the most extensively studied lactic acid bacteria and is the paradigm for biochemical studies of citrate metabolism, little information is available on the regulation of the citrate lyase complex. In order to fill this gap, we characterized the genes encoding the subunits of the citrate lyase of Lactococcus lactis CRL264, which are located on an 11.4-kb chromosomal DNA region. Nucleotide sequence analysis revealed a cluster of eight genes in a new type of genetic organization. The citM-citCDEFXG operon (cit operon) is transcribed as a single polycistronic mRNA of 8.6 kb. This operon carries a gene encoding a malic enzyme (CitM, a putative oxaloacetate decarboxylase), the structural genes coding for the citrate lyase subunits (citD, citE, and citF), and the accessory genes required for the synthesis of an active citrate lyase complex (citC, citX, and citG). We have found that the cit operon is induced by natural acidification of the medium during cell g...
Annals of hepatology
Both prokaryotes and eukaryotes respond to a decrease in temperature with the expression of a spe... more Both prokaryotes and eukaryotes respond to a decrease in temperature with the expression of a specific subset of proteins. We are investigating how Bacillus subtilis cells sense and transduce low-temperature signals to adjust its gene expression. One important step has been accomplished in the dissection of a novel pathway for the adjustment of unsaturated fatty acid synthesis in B.subtilis, termed the Des pathway. It responds to a decrease in growth temperature by enhancing the expression of the des gene, coding for an acyl-lipid desaturase. The Des pathway is uniquely and stringently regulated by a tw-component system composed of a membrane-associated kinase, DesK, and a soluble transcriptional activator, DesR. The temperature sensing ability of the DesK protein is regulated by the extent of disorder within the membrane lipid bilayer. In this work, we present the mechanism by which the sensor protein DesK controls the signal decay of its cognate partner, DesR, and how this respons...