A model wheat cultivar for transformation to improve resistance to Fusarium Head Blight

Fusarium head blight (FHB), caused primarily by Fusarium graminearum, is a major disease problem in wheat (Triticum aestivum). Genetic engineering holds significant potential to enhance FHB resistance in wheat. Due to the requirement of screening for FHB resistance on flowers at anthesis, the number of screens carried out in a year is limited. Our objective was to evaluate the feasibility of using the rapid-maturing dwarf wheat cultivar Apogee as an alternative genotype for transgenic FHB resistance research. Our transformation efficiency (number of transgenic plants/number of embryos) for Apogee was 1.33%. Apogee was also found to exhibit high FHB susceptibility and reached anthesis within 4 weeks. Interestingly, microsatellite marker haplotype analysis of the chromosome 3BS FHB resistant quantitative trait locus (QTL) region indicated that this region maybe deleted in Apogee. Our results indicate that Apogee is particularly well suited for accelerating transgenic FHB resistance research and transgenic wheat research in general. C.A. Mackintosh and D.F. Garvin contributed equally to the article and should be considered co-first authors     

MRI Evidence for Altered Venous Drainage and Intracranial Compliance in Mild Traumatic Brain Injury

Purpose

To compare venous drainage patterns and associated intracranial hydrodynamics between subjects who experienced mild traumatic brain injury (mTBI) and age- and gender-matched controls.

Methods

Thirty adult subjects (15 with mTBI and 15 age- and gender-matched controls) were investigated using a 3T MR scanner. Time since trauma was 0.5 to 29 years (mean 11.4 years). A 2D-time-of-flight MR-venography of the upper neck was performed to visualize the cervical venous vasculature. Cerebral venous drainage through primary and secondary channels, and intracranial compliance index and pressure were derived using cine-phase contrast imaging of the cerebral arterial inflow, venous outflow, and the craniospinal CSF flow. The intracranial compliance index is the defined as the ratio of maximal intracranial volume and pressure changes during the cardiac cycle. MR estimated ICP was then obtained through the inverse relationship between compliance and ICP.

Results

Compared to the controls, subjects with mTBI demonstrated a significantly smaller percentage of venous outflow through internal jugular veins (60.9±21% vs. controls: 76.8±10%; p = 0.01) compensated by an increased drainage through secondary veins (12.3±10.9% vs. 5.5±3.3%; p<0.03). Mean intracranial compliance index was significantly lower in the mTBI cohort (5.8±1.4 vs. controls 8.4±1.9; p<0.0007). Consequently, MR estimate of intracranial pressure was significantly higher in the mTBI cohort (12.5±2.9 mmHg vs. 8.8±2.0 mmHg; p<0.0007).

Conclusions

mTBI is associated with increased venous drainage through secondary pathways. This reflects higher outflow impedance, which may explain the finding of reduced intracranial compliance. These results suggest that hemodynamic and hydrodynamic changes following mTBI persist even in the absence of clinical symptoms and abnormal findings in conventional MR imaging.     

Local and systemic cellular inflammation and cytokine release in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is a chronic airway inflammatory disease caused by repeated exposure to noxious gases or particles. It is now recognized that the disease also features systemic inflammation. The purpose of our study was to compare airway and systemic inflammation in COPD to that seen in healthy subjects and to relate the inflammation with the disease severity.

Methods

Ninety-five COPD patients, encompassing the whole severity spectrum of the disease, were recruited from our outpatient clinic and rehabilitation center and compared to 33 healthy subjects. Induced sputum and blood samples were obtained for measurement of inflammatory cell count. Interleukin (IL)-4, IL-6, IL-10, TNF-α and IFN-γ produced by 24 h sputum and blood cell cultures were measured.

Results

Compared to healthy subjects, COPD exhibited a prominent airway neutrophilic inflammation associated with a marked IL-10, IL-6 and TNF-α release deficiency that contrasted with a raised IFN-γ production. Neutrophilic inflammation was also prominent at blood level together with raised production of IFN-γ, IL-10 and TNF-α. Furthermore, sputum neutrophilia correlated with disease severity assessed by GOLD stages. Likewise the extent of TNF-α release from blood cells also positively correlated with the disease severity but negatively with that of sputum cell culture. Blood release of TNF-α and IL-6 negatively correlated with body mass index. Altogether, our results showed a significant relationship between cellular marker in blood and sputum but poor relationship between local and systemic release of cytokines.

Conclusions

COPD is characterized by prominent neutrophilic inflammation and raised IFN-γ production at both bronchial and systemic level. Overproduction of TNF-α at systemic level correlates with disease severity and inversely with body mass index.     

Acute Neuronal Injury and Blood Genomic Profiles in a Nonhuman Primate Model for Ischemic Stroke

The goal of this study was to characterize acute neuronal injury in a novel nonhuman primate (NHP) ischemic stroke model by using multiple outcome measures. Silk sutures were inserted into the M1 segment of the middle cerebral artery of rhesus macaques to achieve permanent occlusion of the vessel. The sutures were introduced via the femoral artery by using endovascular microcatheterization techniques. Within hours after middle cerebral artery occlusion (MCAO), infarction was detectable by using diffusion-weighted MRI imaging. The infarcts expanded by 24 h after MCAO and then were detectable on T2-weighted images. The infarcts seen by MRI were consistent with neuronal injury demonstrated histologically. Neurobehavioral function after MCAO was determined by using 2 neurologic testing scales. Neurologic assessments indicated that impairment after ischemia was limited to motor function in the contralateral arm; other neurologic and behavioral parameters were largely unaffected. We also used microarrays to examine gene expression profiles in peripheral blood mononuclear cells after MCAO-induced ischemia. Several genes were altered in a time-dependent manner after MCAO, suggesting that this ischemia model may be suitable for identifying blood biomarkers associated with the presence and severity of ischemia. This NHP stroke model likely will facilitate the elucidation of mechanisms associated with acute neuronal injury after ischemia. In addition, the ability to identify candidate blood biomarkers in NHP after ischemia may prompt the development of new strategies for the diagnosis and treatment of ischemic stroke in humans.Abbreviations: MCAO, middle cerebral artery occlusion; NHP, nonhuman primate; PBMC, peripheral blood mononuclear cellsStroke is a debilitating neurologic condition, and little progress has been made in the development of neuroprotective treatments for acute stroke. The Stroke Therapy Academic Industry Roundtable (STAIR) report suggested that preclinical candidates for stroke therapy should be validated by testing in large animals with similarities to humans, such as nonhuman primates (NHP).²⁶ NHP stroke models have been developed in several species, including rhesus monkeys, marmosets, and baboons, by using a variety of techniques for middle cerebral artery occlusion (MCAO).^{4,10,12,13,14,25,32} The rhesus macaque is ideal for stroke studies because of its structural similarities to human brain. The rhesus brain is gyrencephalic, which makes it preferable to those of lissencephalic primates (for example, marmosets) and is functionally similar to human brain.⁶ In addition, the immunologic profile of rhesus macaques is similar to that of humans; therefore these animals are the preferred model for the study of immune responses to infectious diseases such as HIV/SIV, Dengue virus, and others.^17,23,30In addition to their use for neuroprotection assessment, NHP stroke models can facilitate efforts to develop diagnostic tools for identifying and treating stroke symptoms. The use of genomics in peripheral blood cells has been shown to be an excellent method to identify candidate biomarkers and cellular mechanisms associated with stroke.^28,29 Blood biomarkers can be used to rapidly determine the occurrence, timing, subtype, and severity of stroke.^11,15 One possible reason for the lack of viable stroke biomarkers may be the research models used to search for these markers. Although rodent stroke models have yielded a wealth of information on the mechanisms associated with brain ischemia, the findings have not translated well to human clinical trials.²⁶ Recent studies in human patients showed promising results when genomic tools have been used to screen for novel stroke biomarkers.^3,16,27 However, validation of human studies is limited by the need for large data sets in light of heterogeneity in stroke onset, subtype, comorbidities, and other factors. In addition, it is also impossible to know the exact time of stroke onset in most patients.Here we characterized acute neuronal injury in a novel, minimally invasive permanent ischemic stroke model involving rhesus macaques. Using endovascular catheterization techniques, we introduced silk sutures into the M1 segment of the middle cerebral artery and permanently occluded it. This procedure reliably produced infarcts that could be measured by MRI of the macaque brains during the acute phase period. The procedure resulted in discrete and limited neurobehavioral deficits, indicating the potential of this stroke model for chronic neuroprotection studies in the future. In addition, we used microarrays to identify blood genomic profiles that were altered in a time-dependent manner after ischemia. These studies characterize a preclinical model that is suitable for elucidating the mechanisms associated with cerebral ischemia and that may aid in identifying strategies for the diagnosis and treatment of stroke in humans.     

Plant traits shape soil legacy effects on individual plant–insect interactions

Plant-mediated soil legacy effects can be important determinants of the performance of plants and their aboveground insect herbivores, but, soil legacy effects on plant–insect interactions have been tested for only a limited number of host plant species and soils. Here, we tested the performance of a polyphagous aboveground herbivore, caterpillars of the cabbage moth Mamestra brassicae, on twelve host plant species that were grown on a set of soils conditioned by each of these twelve species. We tested how growth rate (fast- or slow-growing) and functional type (grass or forb) of the plant species that conditioned the soil and of the responding host plant species growing in those soils affect the response of insect herbivores to conditioned soils. Our results show that plants and insect herbivores had lower biomass in soils that were conditioned by fast-growing forbs than in soils conditioned by slow-growing forbs. In soils conditioned by grasses, growth rate of the conditioning plant had the opposite effect, i.e. plants and herbivores had higher biomass in soils conditioned by fast-growing grasses, than in soils conditioned by slow-growing grasses. We show that the response of aboveground insects to soil legacy effects is strongly positively correlated with the response of the host plant species, indicating that plant vigour may explain these relationships. We provide evidence that soil communities can play an important role in shaping plant–insect interactions aboveground. Our results further emphasize the important and interactive role of the conditioning and the response plant in mediating soil–plant–insect interactions.     

Ir-LBP,an Ixodes ricinus Tick Salivary LTB4-Binding Lipocalin,Interferes with Host Neutrophil Function

Background

During their blood meal, ticks secrete a wide variety of proteins that can interfere with their host''s defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response.

Methodology/Principal Findings

We previously identified 14 new lipocalin genes in the tick Ixodes ricinus. One of them codes for a protein that specifically binds leukotriene B4 with a very high affinity (Kd: ±1 nM), similar to that of the neutrophil transmembrane receptor BLT1. By in silico approaches, we modeled the 3D structure of the protein and the binding of LTB4 into the ligand pocket. This protein, called Ir-LBP, inhibits neutrophil chemotaxis in vitro and delays LTB4-induced apoptosis. Ir-LBP also inhibits the host inflammatory response in vivo by decreasing the number and activation of neutrophils located at the tick bite site. Thus, Ir-LBP participates in the tick''s ability to interfere with proper neutrophil function in inflammation.

Conclusions/Significance

These elements suggest that Ir-LBP is a “scavenger” of LTB4, which, in combination with other factors, such as histamine-binding proteins or proteins inhibiting the classical or alternative complement pathways, permits the tick to properly manage its blood meal. Moreover, with regard to its properties, Ir-LBP could possibly be used as a therapeutic tool for illnesses associated with an increased LTB4 production.     

The expression pattern of plasma membrane aquaporins in maize leaf highlights their role in hydraulic regulation

Leaves are key organs for evaporation and photosynthesis and play a crucial role in plant growth and development. In order to function properly, they need to maintain a balanced water content. Water movement through a leaf occurs by a combination of different pathways: water can follow an apoplastic route through the cell wall or a cell-to-cell route via the symplastic and transcellular paths. As aquaporins (AQPs) play an important role in regulating transcellular water flow and CO(2) conductance, studies on AQP mRNA and protein expression in leaves are essential to better understand their role in these physiological processes. Here, we quantified and localized the expression of Zea mays plasma membrane aquaporins (ZmPIPs, plasma membrane intrinsic proteins) in the leaf using quantitative RT-PCR and immunodetection. All ZmPIP genes except ZmPIP2;7 were expressed in leaves. Expression was found to be dependent on the developmental stage of the leaf tissue, with, in general, an increase in expression at the end of the elongation zone and a decrease in mature leaf tissue. These data correlated with the cell water permeability, as determined using a protoplast swelling assay. The diurnal expression of ZmPIPs was also investigated and expression was found to be higher during the first hours of the light period than at night. Immunocytochemical localization of four ZmPIP isoforms indicated that they are involved in leaf radial water movement, in particular in vascular bundles and the mesophyll.