Search results for "modified"

Reduced levels of membrane-bound alkaline phosphatase in Vip3Aa-resistant Heliothis virescens

2020

ABSTRACTThe Vip3Aa insecticidal protein fromBacillus thuringiensis(Bt) is produced by specific transgenic corn and cotton varieties for efficient control of target lepidopteran pests. The main threat to this technology is the evolution of resistance in targeted insect pests, thus understanding the mechanistic basis of resistance is crucial to deploy the most appropriate strategies for resistance management. In this work, a laboratory-selected colony ofHeliothis virescens(Vip-Sel) highly resistant to the Vip3Aa protein was used to test whether an alteration of membrane receptors in the insect midgut might explain the resistance phenotype. Binding of125I-labeled Vip3Aa to brush border membran…

Resistant management of Bt corn and sustainability in Italy

2006

The Resistant Management (RM) of Bt corn in US requires 20% refuge area planted with non transgenic maize to preserve susceptible individuals of the pest. In Europe, especially in Italy, different considerations are necessary when RM plans are to be applied. In fact, when determining the size of the refuge areas other aspects around the transgenic corn, such as the surface of co-existing plans and other crops, must be considered. ECB is a polyphagous insect and its biology must be taken into account in the RM, especially in Italy where several crops and natural areas exist close to each other, and where field surfaces are clearly smaller than in the US. An important aspect of RM is the dete…

Novel NG2-CreERT2 knock-in mice demonstrate heterogeneous differentiation potential of NG2 glia during development

2014

NG2 (nerve/glia antigen-2) is a type I transmembrane glycoprotein and also known as chondroitin sulfate proteoglycan 4. In the parenchyma of the central nervous system, NG2-expressing (NG2(+) ) cells have been identified as a novel type of glia with a strong potential to generate oligodendrocytes (OLs) in the developing white matter. However, the differentiation potential of NG2 glia remained controversial, largely attributable to shortcomings of transgenic mouse models used for fate mapping. To minimize these restrictions and to more faithfully mimic the endogenous NG2 expression in vivo, we generated a mouse line in which the open reading frame of the tamoxifen-inducible form of the Cre D…

Safe and Effective Adoptive T-Cell Receptor Transfer with a High Affinity Single Chain p53(264–272)-Specific TCR

2012

Abstract Abstract 4226 Several studies have demonstrated the clinical efficacy of adoptive T cell therapy for targeting cancer. Using HLA-A2.1 transgenic mice, we have demonstrated the feasibility of T-cell receptor (TCR) gene transfer into T cells to circumvent self-tolerance to the widely expressed human p53(264–272) tumor-associated antigen and developed approaches to generate high-affinity CD8-independent TCR. A safety concern of TCR gene transfer is the pairing of endogenous and introduced TCR chains resulting in the potential generation of self-reactive T cells (off-target autoimmunity). Several strategies to favor matched TCR chains pairing and thus enhancing TCR cell surface express…

Cutting Edge: TGF-β Signaling Is Required for the In Vivo Expansion and Immunosuppressive Capacity of Regulatory CD4+CD25+ T Cells

2004

Abstract Data regarding the role of TGF-β for the in vivo function of regulatory CD4+CD25+ T cells (Treg) are controversial. A transgenic mouse model with impaired TGF-β signaling specifically in T cells was used to assess the role of endogenous TGF-β for the in vivo function of CD4+CD25+ Treg in a murine model of colitis induced by dextran sulfate. Transfer of wild-type, but not transgenic CD4+CD25+ Treg was found to suppress colitis in wild-type mice. In addition, by transferring CFSE-labeled CD4+CD25+ Treg we could demonstrate that endogenous TGF-β promotes the expansion of CD4+CD25+ Treg in vivo. Transgenic mice themselves developed reduced numbers of peripheral CD4+CD25+ Treg and were …

A Potent Tumor-Reactive p53-Specific Single-Chain TCR without On- or Off-Target Autoimmunity In Vivo

2018

Genetic engineering of T cells with a T cell receptor (TCR) targeting tumor antigen is a promising strategy for cancer immunotherapy. Inefficient expression of the introduced TCR due to TCR mispairing may limit the efficacy and adversely affect the safety of TCR gene therapy. Here, we evaluated the safety and therapeutic efficiency of an optimized single-chain TCR (scTCR) specific for an HLA-A2.1-restricted (non-mutated) p53(264–272) peptide in adoptive T cell transfer (ACT) models using our unique transgenic mice expressing human p53 and HLA-A2.1 that closely mimic the human setting. Specifically, we showed that adoptive transfer of optimized scTCR-redirected T cells does not induce on-tar…

Plasma clearance of human low-density lipoprotein in human apolipoprotein B transgenic mice is related to particle diameter.

2004

To test for intrinsic differences in metabolic properties of low-density lipoprotein (LDL) as a function of particle size, we examined the kinetic behavior of 6 human LDL fractions ranging in size from 251 to 265 A injected intravenously into human apolipoprotein (apo) B transgenic mice. A multicompartmental model was formulated and fitted to the data by standard nonlinear regression using the Simulation, Analysis and Modeling (SAAM II) program. Smaller sized LDL particles (251 to 257 A) demonstrated a significantly slower fractional catabolic rate (FCR) (0.050 +/- 0.045 h(-1)) compared with particles of larger size (262 to 265 A) (0.134 +/- -0.015 h(-1), P.03), and there was a significant …

2004

With advancing age, thymic efficiency shows progressive decline due to thymic involution allowing impaired cell-mediated immunity and the appearance of age-related diseases. The intrinsic cause of thymic involution is still undefined. Chronic inflammation and high glucocorticoids (GCs) may be involved. However, transgenic mice, with increased GC sensitivity and over expression of GC receptors, display delayed age-associated thymic involution. This fact suggests that other substances may affect thymic involution. Among them, both isoforms of metallothioneins (MTs) I+II and III are the major candidates because their increments leads to organ atrophy in constant stress and are induced by IL-6,…

T Cell-Specific Overexpression of TGFß1 Fails to Influence Atherosclerosis in ApoE-Deficient Mice

2013

Clinical data have indicated a negative correlation between plasma TGFß1 concentrations and the extent of atherosclerosis and have thus led to the hypothesis that the pleiotropic cytokine may have anti-atherogenic properties. T-cells are currently discussed to significantly participate in atherogenesis, but the precise role of adaptive immunity in atherogenesis remains to be elucidated. TGFß1 is known to strongly modulate the function of T-cells, however, inhibition of TGFß1 signalling in T-cells of atherosclerosis-prone knock-out mice failed to unequivocally clarify the role of the cytokine for the development of atherosclerosis. In the present study, we thus tried to specify the role of T…

No effect of C-reactive protein on early atherosclerosis in LDLR-/- / human C-reactive protein transgenic mice

2008

summaryThe association between increased concentrations of C-reactive protein (CRP) and future cardiovascular events is well established. However, it is currently unclear whether this clinical observation represents an epiphenomenon or whether the pentraxin may actively promote the development of atherosclerosis. Experimental studies with knockout mice with a defect in apolipoprotein E (ApoE-/-) have been used to investigate the role of CRP in atherogenesis, but the results obtained have been contradictory so far. Since knockout mice with a defect in low density lipoprotein receptor (LDLR-/-) may represent a better model of atherogenesis compared to ApoE-/- animals, we undertook experiments…