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A key determinant of overall morphogenesis in flowering plants such as Arabidopsis thaliana is the shoot apical meristem (growing tip of a shoot). Gene regulation networks can be used to model this system. We exhibit a very preliminary two-dimensional model including gene regulation and intercellular signaling, but omitting cell division and dynamical geometry. The model can be trained to have three stable regions of gene expression corresponding to the central zone, peripheral zone, and rib meristem. We also discuss a space-engineering motivation for studying and controlling the morphogenesis of plants using such computational models.

This article is from Development (Cambridge, England) , volume 140 . Abstract Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

This article is from Development (Cambridge, England) , volume 140 . Abstract Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

This article is from Development (Cambridge, England) , volume 140 . Abstract Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

This article is from Development (Cambridge, England) , volume 140 . Abstract Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

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The molecular composition and organization of dengue virus (DV) and Japense encephalitis virus (JEV) components released from infected cells is described in this report. Two forms of infectious particles with different molecular compositions were detected. Polypeptides associated with the two forms are tightly bound to the particles and appear to be integral envelope proteins. JEV and DV infected cells were found to release considerable amounts of viral polypeptides into cell culture medium. Radioimmune precipitation was used to pick out viral polypeptides from a large background of labeled material-Nonimmune separation of polypeptides was attempted using column chromatography. Bifunctional crosslinking reagents have been used to study the molecular organization of flaviviruses. Optimization of crosslinking conditions has lead to the detection of a number of crosslinked polypeptides. Suggested assignments of monomers constituting the crosslinked products is presented. Preliminary results of polypeptide composition analysis of uninfected and infected cell lysates and plasma membrane fractions are presented.

The molecular composition and organization of dengue virus (DV) and Japense encephalitis virus (JEV) components released from infected cells is described in this report. Two forms of infectious particles with different molecular compositions were detected. Polypeptides associated with the two forms are tightly bound to the particles and appear to be integral envelope proteins. JEV and DV infected cells were found to release considerable amounts of viral polypeptides into cell culture medium. Radioimmune precipitation was used to pick out viral polypeptides from a large background of labeled material-Nonimmune separation of polypeptides was attempted using column chromatography. Bifunctional crosslinking reagents have been used to study the molecular organization of flaviviruses. Optimization of crosslinking conditions has lead to the detection of a number of crosslinked polypeptides. Suggested assignments of monomers constituting the crosslinked products is presented. Preliminary results of polypeptide composition analysis of uninfected and infected cell lysates and plasma membrane fractions are presented.

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Description: Theories for the genetic control of morphogenesis -- covers work from the past in the field, highlights lacunae in the same and elaborates on cell types that may arise due to exposure to different proteins because of positioning of the cells. Accession Number: MS-003_3_3_12_4_0015-0019 Collection: Series:MS-003 Sub-Series: 3 Container 1: 3 Container 2: 12 Source: 4 Repository: KS Krishnan papers Dimensions: 21x29.7cm Extent: 5p Location: Unknown Access: Lecture Format: Typewritten

Bacillus spp. and Clostridium spp. form a specialized cell type, called a spore, during a multistep differentiation process that is initiated in response to starvation. Spores are protected by a morphologically complex protein coat. The Bacillus anthracis coat is of particular interest because the spore is the infective particle of anthrax. We determined the roles of several B. anthracis orthologues of Bacillus subtilis coat protein genes in spore assembly and virulence. One of these, cotE, has a striking function in B. anthracis: it guides the assembly of the exosporium, an outer structure encasing B. anthracis but not B. subtilis spores. However, CotE has only a modest role in coat protein assembly, in contrast to the B. subtilis orthologue. cotE mutant spores are fully virulent in animal models, indicating that the exosporium is dispensable for infection, at least in the context of a cotE mutation. This has implications for both the pathophysiology of the disease and next-generation therapeutics. CotH, which directs the assembly of an important subset of coat proteins in B. subtilis, also directs coat protein deposition in B. anthracis. Additionally, however, in B. anthracis, CotH effects germination; in its absence, more spores germinate than in the wild type. We also found that SpoIVA has a critical role in directing the assembly of the coat and exosporium to an area around the forespore. This function is very similar to that of the B. subtilis orthologue, which directs the assembly of the coat to the forespore. These results show that while B. anthracis and B. subtilis rely on a core of conserved morphogenetic proteins to guide coat formation, these proteins may also be important for species-specific differences in coat morphology.

The influence of light, sterilization conditions and some components of the nutrient medium on direct sprouting, callusogenesis and morphogenesis in the culture of mature barley embryos was studied. 

The influence of light, sterilization conditions and some components of the nutrient medium on direct sprouting, callusogenesis and morphogenesis in the culture of mature barley embryos was studied. 

robot swarms

This article is from Virology Journal , volume 8 . Abstract Background: PRV Fa is common in China and causes most of the pseudorabies in the pig industry. A PRV SA215 strain with deleted gE, gI, and TK genes was constructed to develop a commercial attenuated live vaccine. However, the physicochemical properties, growth pattern, penetration kinetics, and morphogenesis of the PRV SA215 and its parental PRV Fa strain are unclear. Results: A series of experiments were conducted to characterize both strains and provide more information. PRV Fa and PRV SA215 were found to have similar penetration patterns, with about 5 min half-time of penetration. The SA215 strain exhibited a slight delay in entry compared with PRV Fa. In the one-step growth test, the titers of the SA215 strain were first detected at 8 h, rapidly increased, and peaked at 12 h. A plateau was formed between 12-36 h of culturing. PRV SA215 showed delayed replication and approximately 10-30-fold lower titers during 0-16 h of culturing compared with the PRV-Fa strain. After 16 h, the PRV Fa titers dramatically decreased, whereas those of PRV SA215 were prolonged to 36 h and reached a titer value equal to that of PRV Fa and then decreased. Both strains were sensitive to both heat and acid-alkali treatments; however, PRV Fa was relatively more stable to heat treatment than PRV SA215. Both strains could propagate in the cultures with pH values from 5.0 to 9.0. Cultures with pH below 3.0 or above 11.0 were fatal to both strains. Both strains had considerable resistance to freeze-thawing treatments. Morphogenetic investigations showed that typical phases in the maturation pathway were observed in the PRV Fa-infected PK15 cells, whereas secondary envelopment was not observed in the PRV SA215 strain. Instead, capsid aggregations with concomitants of electrodense materials were observed. Conclusions: These results suggest that PRV SA215 is a promising strain for vaccine development

This article is from Cell , volume 156 . Abstract Transformation of pluripotent epiblast cells into a cup-shaped epithelium as the mouse blastocyst implants is a poorly understood and yet key developmental step. Studies of morphogenesis in embryoid bodies led to the current belief that it is programmed cell death that shapes the epiblast. However, by following embryos developing in vivo and in vitro, we demonstrate that not cell death but a previously unknown morphogenetic event transforms the amorphous epiblast into a rosette of polarized cells. This transformation requires basal membrane-stimulated integrin signaling that coordinates polarization of epiblast cells and their apical constriction, a prerequisite for lumenogenesis. We show that basal membrane function can be substituted in vitro by extracellular matrix (ECM) proteins and that ES cells can be induced to form similar polarized rosettes that initiate lumenogenesis. Together, these findings lead to a completely revised model for peri-implantation morphogenesis in which ECM triggers the self-organization of the embryo’s stem cells.

This article is from Cell , volume 156 . Abstract Transformation of pluripotent epiblast cells into a cup-shaped epithelium as the mouse blastocyst implants is a poorly understood and yet key developmental step. Studies of morphogenesis in embryoid bodies led to the current belief that it is programmed cell death that shapes the epiblast. However, by following embryos developing in vivo and in vitro, we demonstrate that not cell death but a previously unknown morphogenetic event transforms the amorphous epiblast into a rosette of polarized cells. This transformation requires basal membrane-stimulated integrin signaling that coordinates polarization of epiblast cells and their apical constriction, a prerequisite for lumenogenesis. We show that basal membrane function can be substituted in vitro by extracellular matrix (ECM) proteins and that ES cells can be induced to form similar polarized rosettes that initiate lumenogenesis. Together, these findings lead to a completely revised model for peri-implantation morphogenesis in which ECM triggers the self-organization of the embryo’s stem cells.

This article is from Cell , volume 156 . Abstract Transformation of pluripotent epiblast cells into a cup-shaped epithelium as the mouse blastocyst implants is a poorly understood and yet key developmental step. Studies of morphogenesis in embryoid bodies led to the current belief that it is programmed cell death that shapes the epiblast. However, by following embryos developing in vivo and in vitro, we demonstrate that not cell death but a previously unknown morphogenetic event transforms the amorphous epiblast into a rosette of polarized cells. This transformation requires basal membrane-stimulated integrin signaling that coordinates polarization of epiblast cells and their apical constriction, a prerequisite for lumenogenesis. We show that basal membrane function can be substituted in vitro by extracellular matrix (ECM) proteins and that ES cells can be induced to form similar polarized rosettes that initiate lumenogenesis. Together, these findings lead to a completely revised model for peri-implantation morphogenesis in which ECM triggers the self-organization of the embryo’s stem cells.

This article is from Cell , volume 156 . Abstract Transformation of pluripotent epiblast cells into a cup-shaped epithelium as the mouse blastocyst implants is a poorly understood and yet key developmental step. Studies of morphogenesis in embryoid bodies led to the current belief that it is programmed cell death that shapes the epiblast. However, by following embryos developing in vivo and in vitro, we demonstrate that not cell death but a previously unknown morphogenetic event transforms the amorphous epiblast into a rosette of polarized cells. This transformation requires basal membrane-stimulated integrin signaling that coordinates polarization of epiblast cells and their apical constriction, a prerequisite for lumenogenesis. We show that basal membrane function can be substituted in vitro by extracellular matrix (ECM) proteins and that ES cells can be induced to form similar polarized rosettes that initiate lumenogenesis. Together, these findings lead to a completely revised model for peri-implantation morphogenesis in which ECM triggers the self-organization of the embryo’s stem cells.

The first major finding was the appearance of Dengue antigens on the surface of infected cells. This was of major importance since it has been hypothesized that dengue hemorraghic fever (DHF) is the result of DEN antigen interaction with anti Dengue antibody resulting complement mediated vascular endothelial injury. Findings then led us to postulate that Dengue antigens on the cell surface were composed of ordered arrays of Dengue polypeptides. As a first approach we proposed to examine the surface of the virus itself and then proceed to a study of the cell surface. To do this we studied the growth of Dengue in BHK cells. Our findings established new growth conditions and assay procedures for the virus. Since our approach was to use crosslinking reagents to study the organization of the Dengue polypeptides we examined the charge properties of viral glycoproteins on two other togaviruses. Results of these studies showed that the glycoproteins of two closely related viruses were quite different but that these differences probably would not significantly alter the organization of polypeptides on the surface of the virion. Protein-protein interactions on Japanese encephalitis virus (JEV), a virus closely related to Dengue, were analyzed. These results demonstrated that the major viral glycoprotein on the surface of the virion had as its nearest neighbor either one of its kind or another newly defined viral glycoprotein. Thus the clustering of viral antigens on flaviviruses had been demonstrated.

The first major finding was the appearance of Dengue antigens on the surface of infected cells. This was of major importance since it has been hypothesized that dengue hemorraghic fever (DHF) is the result of DEN antigen interaction with anti Dengue antibody resulting complement mediated vascular endothelial injury. Findings then led us to postulate that Dengue antigens on the cell surface were composed of ordered arrays of Dengue polypeptides. As a first approach we proposed to examine the surface of the virus itself and then proceed to a study of the cell surface. To do this we studied the growth of Dengue in BHK cells. Our findings established new growth conditions and assay procedures for the virus. Since our approach was to use crosslinking reagents to study the organization of the Dengue polypeptides we examined the charge properties of viral glycoproteins on two other togaviruses. Results of these studies showed that the glycoproteins of two closely related viruses were quite different but that these differences probably would not significantly alter the organization of polypeptides on the surface of the virion. Protein-protein interactions on Japanese encephalitis virus (JEV), a virus closely related to Dengue, were analyzed. These results demonstrated that the major viral glycoprotein on the surface of the virion had as its nearest neighbor either one of its kind or another newly defined viral glycoprotein. Thus the clustering of viral antigens on flaviviruses had been demonstrated.

This article presents formalistic tool for description of structural and biochemical relations between cells in the course of development of the body of plants. This is flexible formalistic space, based on the Category theory and the Petri Net approach, which embeds and mutually supplements biological data from methodically different sources. Relation between functional and morphological ways of plant description was mathematically realized with help of the adjoint functors. It was shown that histology and proliferative activity of the formative tissues give a template for the gene interaction networks.

Experiments of in vitro formation of blood vessels show that cells randomly spread on a gel matrix autonomously organize to form a connected vascular network. We propose a simple model which reproduces many features of the biological system. We show that both the model and the real system exhibit a fractal behavior at small scales, due to the process of migration and dynamical aggregation, followed at large scale by a random percolation behavior due to the coalescence of aggregates. The results are in good agreement with the analysis performed on the experimental data.

Cardiology; Pediatrics

Cardiology; Pediatrics

Cardiology; Pediatrics

Cardiology; Pediatrics

Cardiology; Pediatrics

Classical article by A. Turing, see, e.g.  The Chemical Basis of Morphogenesis - Wikipedia

http://uf.catalog.fcla.edu/uf.jsp?st=UF030099975&ix=pm&I=0&V=D&pm=1

http://uf.catalog.fcla.edu/uf.jsp?st=UF030099975&ix=pm&I=0&V=D&pm=1

http://uf.catalog.fcla.edu/uf.jsp?st=UF030099975&ix=pm&I=0&V=D&pm=1

Stromal-epithelial interactions regulate mammary epithelial cell (MEC) fate via integrin-growth factor receptor (GFR) interactions. Integrin-GFR crosstalk influences MEC behavior through activation of tyrosine kinase signaling that is tempered by protein tyrosine phosphatase (PTP) activity of which we know little about. Using a degenerate RT-PCR to amplify PTPs expressed in differentiated versus non-differentiated MECs, we identified the Band 4.1 PTPs MEG1 and Dl as two candidate PTP metastasis suppressors. Our studies show that during MEC differentiation PTP MEGl and Dl expression rise dramatically, coincident with assembly of E-cadherin/Beta-catenin adherens junction formation. However, both mRNA and protein expression of MEGl and Dl become repressed following MEC tissue differentiation. Because we could not establish any correlation between MEC growth, or tissue polarization, this suggests that MEG1 and Dl expression may be functionally linked to adherens junction assembly. Consistently, malignant MECs that fail to assemble adherens junctions do not modulate MEGl or Dl expression. Moreover, MEGl expression is not induced in phenotypically reverting tumors, or down regulated in dormant structures. This suggests that these Band 4.1 PTPs may be functionally-linked to molecules mediating adherens junction formation.

Nipah virus (NiV) is an emerging paramyxovirus distinguished by its ability to cause fatal disease in both animal and human hosts. Together with Hendra virus (HeV), they comprise the genus Henipavirus in the Paramyxoviridae family. NiV and HeV are restricted to Biosafety Level-4 (BSL-4) containment and this has hampered progress towards examining the details of their replication and morphogenesis mechanisms. Here, recombinant gene expression systems to study NiV particle assembly and budding through the formation of virus-like particles (VLPs) have been established to circumvent these obstacles. When expressed by recombinant Modified Vaccinia virus Ankara (rMVA) or by plasmid vector transfection, individual NiV matrix (M), fusion (F) and attachment (G) proteins were released into cell culture supernatants in a membrane associated state as determined by sucrose density gradient flotation and immunoprecipitation analysis. However, co-expression of F and G along with M revealed a shift in their distribution across the gradient, indicating association with M in VLPs.

Nipah virus (NiV) is an emerging paramyxovirus distinguished by its ability to cause fatal disease in both animal and human hosts. Together with Hendra virus (HeV), they comprise the genus Henipavirus in the Paramyxoviridae family. NiV and HeV are restricted to Biosafety Level-4 (BSL-4) containment and this has hampered progress towards examining the details of their replication and morphogenesis mechanisms. Here, recombinant gene expression systems to study NiV particle assembly and budding through the formation of virus-like particles (VLPs) have been established to circumvent these obstacles. When expressed by recombinant Modified Vaccinia virus Ankara (rMVA) or by plasmid vector transfection, individual NiV matrix (M), fusion (F) and attachment (G) proteins were released into cell culture supernatants in a membrane associated state as determined by sucrose density gradient flotation and immunoprecipitation analysis. However, co-expression of F and G along with M revealed a shift in their distribution across the gradient, indicating association with M in VLPs.

This article is from PLoS Pathogens , volume 10 . Abstract Candida albicans, the most important fungal pathogen of humans, has a unique interaction with macrophages in which phagocytosis induces a switch from the yeast to hyphal form, allowing it to escape by rupturing the immune cell. While a variety of factors induce this switch in vitro, including neutral pH, it is not clear what triggers morphogenesis within the macrophage where the acidic environment should inhibit this transition. In vitro, C. albicans grown in similar conditions in which amino acids are the primary carbon source generate large quantities of ammonia to raise the extracellular pH and induce the hyphal switch. We show here that C. albicans cells neutralize the macrophage phagosome and that neutral pH is a key inducer of germination in phagocytosed cells by using a mutant lacking STP2, a transcription factor that regulates the expression of multiple amino acid permeases, that is completely deficient in alkalinization in vitro. Phagocytosed stp2Δ mutant cells showed significant reduction in hypha formation and escaped from macrophages less readily compared to wild type cells; as a result stp2Δ mutant cells were killed at a higher rate and caused less damage to RAW264.7 macrophages. Stp2p-regulated import leads to alkalinization of the phagosome, since the majority of the wild type cells fail to co-localize with acidophilic dyes, whereas the stp2Δ mutant cells were located in acidic phagosomes. Furthermore, stp2Δ mutant cells were able to form hyphae and escape from neutral phagosomes, indicating that the survival defect in these cells was pH dependent. Finally, these defects are reflected in an attenuation of virulence in a mouse model of disseminated candidiasis. Altogether our results suggest that C. albicans utilizes amino acids to promote neutralization of the phagosomal pH, hyphal morphogenesis, and escape from macrophages.

This article is from Respiratory Research , volume 12 . Abstract Background: Alveolar septation marks the beginning of the transition from the saccular to alveolar stage of lung development. Inflammation can disrupt this process and permanently impair alveolar formation resulting in alveolar hypoplasia as seen in bronchopulmonary dysplasia in preterm newborns. NF-κB is a transcription factor central to multiple inflammatory and developmental pathways including dorsal-ventral patterning in fruit flies; limb, mammary and submandibular gland development in mice; and branching morphogenesis in chick lungs. We have previously shown that epithelial overexpression of NF-κB accelerates lung maturity using transgenic mice. The purpose of this study was to test our hypothesis that targeted deletion of NF-κB signaling in lung epithelium would impair alveolar formation. Methods: We generated double transgenic mice with lung epithelium-specific deletion of IKKβ, a known activating kinase upstream of NF-κB, using a cre-loxP transgenic recombination strategy. Lungs of resulting progeny were analyzed at embryonic and early postnatal stages to determine specific effects on lung histology, and mRNA and protein expression of relevant lung morphoreulatory genes. Lastly, results measuring expression of the angiogenic factor, VEGF, were confirmed in vitro using a siRNA-knockdown strategy in cultured mouse lung epithelial cells. Results: Our results showed that IKKβ deletion in the lung epithelium transiently decreased alveolar type I and type II cells and myofibroblasts and delayed alveolar formation. These effects were mediated through increased alveolar type II cell apoptosis and decreased epithelial VEGF expression. Conclusions: These results suggest that epithelial NF-κB plays a critical role in early alveolar development possibly through regulation of VEGF.

This article is from Respiratory Research , volume 12 . Abstract Background: Alveolar septation marks the beginning of the transition from the saccular to alveolar stage of lung development. Inflammation can disrupt this process and permanently impair alveolar formation resulting in alveolar hypoplasia as seen in bronchopulmonary dysplasia in preterm newborns. NF-κB is a transcription factor central to multiple inflammatory and developmental pathways including dorsal-ventral patterning in fruit flies; limb, mammary and submandibular gland development in mice; and branching morphogenesis in chick lungs. We have previously shown that epithelial overexpression of NF-κB accelerates lung maturity using transgenic mice. The purpose of this study was to test our hypothesis that targeted deletion of NF-κB signaling in lung epithelium would impair alveolar formation. Methods: We generated double transgenic mice with lung epithelium-specific deletion of IKKβ, a known activating kinase upstream of NF-κB, using a cre-loxP transgenic recombination strategy. Lungs of resulting progeny were analyzed at embryonic and early postnatal stages to determine specific effects on lung histology, and mRNA and protein expression of relevant lung morphoreulatory genes. Lastly, results measuring expression of the angiogenic factor, VEGF, were confirmed in vitro using a siRNA-knockdown strategy in cultured mouse lung epithelial cells. Results: Our results showed that IKKβ deletion in the lung epithelium transiently decreased alveolar type I and type II cells and myofibroblasts and delayed alveolar formation. These effects were mediated through increased alveolar type II cell apoptosis and decreased epithelial VEGF expression. Conclusions: These results suggest that epithelial NF-κB plays a critical role in early alveolar development possibly through regulation of VEGF.