Interaction of the amyloid imaging tracer FDDNP with hallmark Alzheimer's disease pathologies

The distinctive cortical uptake of the tracer ¹⁸F-FDDNP (2-(1-{6-[(2-fluoroethyl(methyl)amino]-2-naphthyl}ethylidene)malononitrile) in Alzheimer's disease (AD) is believed to be because of its binding to both neurofibrillary tangles (NFTs) and highly fibrillar senile plaques. We therefore investigated the binding of a tracer concentration of ³H-FDDNP to brain sections containing AD hallmark pathologies. Semi-adjacent sections were labelled with ³H-PIB (Pittsburgh compound-B, 2-[4'-(methylamino)phenyl]-6-hydroxybenzothiazole) and ¹⁴C-SB13 (4- N -methylamino-4'-hydroxystilbene) for comparison. Neocortical sections containing widespread senile plaques and cerebrovascular amyloid angiopathy, produced a sparse and weak labelling following incubation with ³H-FDDNP. Furthermore, in sections containing NFTs, there was no overt labelling of the pathology by ³H-FDDNP. In contrast, sections labelled with ³H-PIB displayed extensive labelling of diffuse plaques, classical plaques, cerebrovascular amyloid angiopathy and NFTs. ¹⁴C-SB13 produced a broadly similar binding pattern to PIB. Radioligand binding assays employing in vitro generated amyloid-β peptide fibrils demonstrated a ∼10-fold reduced affinity for ³H-FDDNP (85.0 ± 2.0 nM) compared with ³H-PIB (8.5 ± 1.3 nM). These data provide an alternative mechanistic explanation for the observed low cortical uptake of ¹⁸F-FDDNP in AD; in that the ligand is only weakly retained by the hallmark neuropathology because of its low affinity for amyloid structures.     

Secreted phospholipase A2-IIA modulates key regulators of proliferation on astrocytoma cells

Human group IIA secreted phospholipase A₂ (sPLA₂-IIA) has been characterized in numerous inflammatory and neoplastic conditions. sPLA₂-IIA can either promote or inhibit cell growth depending on the cellular type and the specific injury. We have previously demonstrated that exogenous sPLA₂-IIA, by engagement to a membrane structure, induces proliferation and activation of mitogen-activated protein kinases cascade in human astrocytoma cells. In this study, we used human astrocytoma 1321N1 cells to investigate the key molecules mediating sPLA₂-IIA-induced cell proliferation. We found that sPLA₂-IIA promoted reactive oxygen species (ROS) accumulation, which was abrogated in the presence of allopurinol and DPI, but not by rotenone, discarding mitochondria as a ROS source. In addition, sPLA₂-IIA triggered Ras and Raf-1 activation, with kinetics that paralleled ERK phosphorylation, and co-immunoprecipitation assays indicated an association between Ras, Raf-1 and ERK. Additionally, Akt, p70 ribosomal protein S6 kinase, and S6 ribosomal protein were also phosphorylated upon sPLA₂-IIA treatment, effect that was abrogated by N -acetylcysteine or LY294002 treatment indicating that ROS and phosphatidylinositol 3 kinase are upstream signaling regulators. As the inhibitors N -acetylcysteine, PD98059, LY294002 or rapamycin blocked sPLA₂-IIA-induced proliferation without activation of the apoptotic program, we suggest that inhibition of these intracellular signal transduction elements may represent a mechanism of growth arrest. Our results reveal new potential targets for therapeutic intervention in neuroinflammatory disorders and brain cancer in particular.     

Nutritional Status of the Cauliflower Cultivar ‘Verona’ Grown with Omission of out Added Macronutrients

Knowledge of plant nutritional status allows an understanding of the physiological responses of plants to crop fertilization. A hydroponic experiment evaluated the symptoms of macronutrient deficiency in cauliflower ‘Verona’ and determined: a) the macronutrient contents of foliar tissues when visual symptoms were observed, b) macronutrients content of foliar and inflorescence tissues at harvest. The effect of nutrient deficiency on inflorescence mass was also evaluated. Nitrogen deficiency caused chlorosis followed by purple color in the old leaves, while P deficiency caused only chlorosis in old leaves. Chlorosis at the edge of old leaves progressing to the center of the leaves was observed with the omission of K, and after was observed necrosis in the chlorotic areas. Ca deficiency caused tip burn in new leaves, while Mg deficiency caused internerval chlorosis in old leaves. The omission of each macronutrient reduced inflorescence dry matter. This deleterious effect was larger for N, P, and K deficiencies, reducing inflorescence dry matter by 87, 49, and 42%, respectively. When the nutrient solutions without N, P, K, Ca, or Mg were supplied to cauliflower plants, the macronutrient contents at harvest were 8.8, 0.6, 3.5, 13.0, and 0.8 g kg^-1 in the foliar tissues and 27.3, 2.2, 21.6, 1.1, and 0.7 g kg^-1 in the inflorescence tissues, respectively.     

Kinetic studies of the electron exchange reaction between the octaheme cytochrome c3 (Mr 26000) and the hydrogenase from Desulfovibrio desulfuricans Norway.

The octaheme cytochrome c3 (Mr 26000) from Desulfovibrio desulfuricans Norway was studied using cyclic voltammetry at the pyrolytic graphite electrode. The kinetics of reduction of the octaheme cytochrome c3 (Mr 26000) from D. desulfuricans Norway by the Ni-Fe-Se hydrogenase purified from the same organism was investigated by an electrochemical method. From cyclic voltammetry experiments a value of 8.108M-1S-1 was obtained for the second order homogenous rate constant of the electron transfer between the two proteins. Results are compared with similar experiments performed on the electron exchange between the tetrahemic cytochrome c3 (Mr 13000) and hydrogenase.     

Plasmatic carbonic anhydrase IX as a diagnostic marker for clear cell renal cell carcinoma

Carbonic anhydrase (CA, EC 4.2.1.1) IX is regarded as a tumour hypoxia marker and CA inhibitors have been proposed as a new class of antitumor agents, with one such agent in Phase II clinical trials. The expression of some CAs, in particular the isoforms CA IX and CA XII, has been correlated with tumour aggressiveness and progression in several cancers. The aim of this study was to evaluate the possibility that CA IX could represent a marker related to clear cell Renal Cell Carcinoma (ccRCC). Bcl-2 and Bax, and the activity of caspase-3, evaluated in tissue biopsies from patients, were congruent with resistance to apoptosis in ccRCCs with respect to healthy controls, respectively. In the same samples, the CA IX and pro-angiogenic factor VEGF expressions revealed that both these hypoxia responsive proteins were strongly increased in ccRCC with respect to controls. CA IX plasma concentration and CA activity were assessed in healthy volunteers and patients with benign kidney tumours and ccRCCs. CA IX expression levels were found strongly increased only in plasma from ccRCC subjects, whereas, CA activity was found similarly increased both in plasma from ccRCC and benign tumour patients, compared to healthy volunteers. These results show that the plasmatic level of CA IX, but not the CA total activity, can be considered a diagnostic marker of ccRCCs. Furthermore, as many reports exist relating CA IX inhibition to a better outcome to anticancer therapy in ccRCC, plasma levels of CA IX could be also predictive for response to therapy.     

Nucleo-cytosolic Shuttling of ARGONAUTE1 Prompts a Revised Model of the Plant MicroRNA Pathway

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A study of gene expression changes at the <Emphasis Type="Italic">Bp-2</Emphasis> locus associated with bitter pit symptom expression in apple (<Emphasis Type="Italic">Malus pumila</Emphasis>)

Bitter pit is a physiological disorder of apples that develops in the latter stages of fruit development and during storage. It is characterized by localized necrotic cells that collapse and form pits in the epidermis and outer cortex of fruit. The disorder has been associated with low calcium concentrations, and poor calcium distribution within the fruit. To date, the mechanism that leads to individual cell necrosis, while surrounding cells remain healthy, is not fully understood. In order to ascertain the underlying process of bitter pit incidence in apple fruit, a large mapping population of “Braeburn” (susceptible to bitter pit)?×?“Cameo” (resistant to bitter pit) was used to map the trait over two growing seasons. A subset of 94 genotypes from the mapping population representing the full range of phenotypes in the same ratio as the full population were selected for genotyping and functional characterization. RNA-Seq analysis on fruit samples of three resistant and three susceptible lines at seven developmental stages (21, 42, 63, 84, 105, 126, and 147 days post fertilization) identified a number of candidate genes displaying differential gene expression. A subset of candidate genes selected based on their position within the identified QTL interval on linkage group 16 were validated by RT-qPCR, and two candidate genes displaying differential gene expression were highlighted as strong candidates for the control of bitter pit symptom expression at the Bp-2 locus.     

Modelling the distribution and compositional variation of plant communities at the continental scale

Aim

We investigate whether (1) environmental predictors allow to delineate the distribution of discrete community types at the continental scale and (2) how data completeness influences model generalization in relation to the compositional variation of the modelled entities.

Location

Europe.

Methods

We used comprehensive datasets of two community types of conservation concern in Europe: acidophilous beech forests and base‐rich fens. We computed community distribution models (CDMs) calibrated with environmental predictors to predict the occurrence of both community types, evaluating geographical transferability, interpolation and extrapolation under different scenarios of sampling bias. We used generalized dissimilarity modelling (GDM) to assess the role of geographical and environmental drivers in compositional variation within the predicted distributions.

Results

For the two community types, CDMs computed for the whole study area provided good performance when evaluated by random cross‐validation and external validation. Geographical transferability provided lower but relatively good performance, while model extrapolation performed poorly when compared with interpolation. Generalized dissimilarity modelling showed a predominant effect of geographical distance on compositional variation, complemented with the environmental predictors that also influenced habitat suitability.

Main conclusions

Correlative approaches typically used for modelling the distribution of individual species are also useful for delineating the potential area of occupancy of community types at the continental scale, when using consistent definitions of the modelled entity and high data completeness. The combination of CDMs with GDM further improves the understanding of diversity patterns of plant communities, providing spatially explicit information for mapping vegetation diversity and related habitat types at large scales.

     

Genomic prediction ability for beef fatty acid profile in Nelore cattle using different pseudo-phenotypes

The aim of the present study was to compare the predictive ability of SNP-BLUP model using different pseudo-phenotypes such as phenotype adjusted for fixed effects, estimated breeding value, and genomic estimated breeding value, using simulated and real data for beef FA profile of Nelore cattle finished in feedlot. A pedigree with phenotypes and genotypes of 10,000 animals were simulated, considering 50% of multiple sires in the pedigree. Regarding to phenotypes, two traits were simulated, one with high heritability (0.58), another with low heritability (0.13). Ten replicates were performed for each trait and results were averaged among replicates. A historical population was created from generation zero to 2020, with a constant size of 2000 animals (from generation zero to 1000) to produce different levels of linkage disequilibrium (LD). Therefore, there was a gradual reduction in the number of animals (from 2000 to 600), producing a “bottleneck effect” and consequently, genetic drift and LD starting in the generation 1001 to 2020. A total of 335,000 markers (with MAF greater or equal to 0.02) and 1000 QTL were randomly selected from the last generation of the historical population to generate genotypic data for the test population. The phenotypes were computed as the sum of the QTL effects and an error term sampled from a normal distribution with zero mean and variance equal to 0.88. For simulated data, 4000 animals of the generations 7, 8, and 9 (with genotype and phenotype) were used as training population, and 1000 animals of the last generation (10) were used as validation population. A total of 937 Nelore bulls with phenotype for fatty acid profiles (Sum of saturated, monounsaturated, omega 3, omega 6, ratio of polyunsaturated and saturated and polyunsaturated fatty acid profile) were genotyped using the Illumina BovineHD BeadChip (Illumina, San Diego, CA) with 777,962 SNP. To compare the accuracy and bias of direct genomic value (DGV) for different pseudo-phenotypes, the correlation between true breeding value (TBV) or DGV with pseudo-phenotypes and linear regression coefficient of the pseudo-phenotypes on TBV for simulated data or DGV for real data, respectively. For simulated data, the correlations between DGV and TBV for high heritability traits were higher than obtained with low heritability traits. For simulated and real data, the prediction ability was higher for GEBV than for Yc and EBV. For simulated data, the regression coefficient estimates (b_(Yc,DGV)), were on average lower than 1 for high and low heritability traits, being inflated. The results were more biased for Yc and EBV than for GEBV. For real data, the GEBV displayed less biased results compared to Yc and EBV for SFA, MUFA, n-3, n-6, and PUFA/SFA. Despite the less biased results for PUFA using the EBV as pseudo-phenotype, the b_(Yi,DGV estimates obtained for the different pseudo-phenotypes (Yc, EBV and GEBV) were very close. Genomic information can assist in improving beef fatty acid profile in Zebu cattle, since the use of genomic information yielded genomic values for fatty acid profile with accuracies ranging from low to moderate. Considering both simulated and real data, the ssGBLUP model is an appropriate alternative to obtain more reliable and less biased GEBVs as pseudo-phenotype in situations of missing pedigree, due to high proportion of multiple sires, being more adequate than EBV and Yc to predict direct genomic value for beef fatty acid profile.     

Bicoid gradient formation mechanism and dynamics revealed by protein lifetime analysis

Embryogenesis relies on instructions provided by spatially organized signaling molecules known as morphogens. Understanding the principles behind morphogen distribution and how cells interpret locally this information remains a major challenge in developmental biology. Here, we introduce morphogen‐age measurements as a novel approach to test models of morphogen gradient formation. Using a tandem fluorescent timer as a protein age sensor, we find a gradient of increasing age of Bicoid along the anterior–posterior axis in the early Drosophila embryo. Quantitative analysis of the protein age distribution across the embryo reveals that the synthesis–diffusion–degradation model is the most likely model underlying Bicoid gradient formation, and rules out other hypotheses for gradient formation. Moreover, we show that the timer can detect transitions in the dynamics associated with syncytial cellularization. Our results provide new insight into Bicoid gradient formation and demonstrate how morphogen‐age information can complement knowledge about movement, abundance, and distribution, which should be widely applicable to other systems.