AMPA receptors (AMPARs) are responsible for most fast excitatory synaptic transmission in the central nervous system, including hippocampal neurons, studied here. AMPARs are highly dynamic in the plasma membrane. Within dendritic spines, they transition by membrane trafficking between intracellular compartments and the plasma membrane. Once at the surface, they move through lateral brownian diffusion and can reversibly anchor to postsynaptic density proteins or return to endocytic compartments. Aβ oligomers (oAβ) increase endocytosis of AMPARs, diminish dendritic spine density and cause overall failures in excitatory transmission. These effects, among others, are englobed in the term “oAβ synaptotoxicity” and are a main focus on the study of Alzheimers disease ethiology. On the contrary, Wnt5a - an endogenous Wnt ligand known to activate the non-canonical pathway in hippocampal neurons - generates an increase in excitatory currents, clusters of PSD95 and protects neurons against oAβ synaptotoxicity. Given the fact that Wnt5a seems to counteract the distresses caused by oAβ, we proceeded to study the mechanism through which Wnt5a protects from oAβ synaptotoxicity. This led us to evaluate the effect of Wnt5a on one of the most important factors in glutamatergic transmission, i.e. AMPARs dynamics. By using super-resolution microscopy in live hippocampal neurons, we found that Wnt5a modulates the dynamic and localization of AMPARs. Specifically, Wnt5a stabilizes AMPARs in spine and dendritic compartments. This correlates with an increase in co-localization and interaction between GluA2 and PSD95. These effects are exerted only by non-canonical activation of Wnt signaling, through Wnt5a ligand and not by the canonical effects of Wnt7a. Interestingly, pre-incubation of Wnt5a prevents toxicity of oAβ and maintains basal AMPARs dynamics. Our data suggest that Wnt5a prevents oAβ effects by promoting their stabilization in synaptic sites.
Syndecan-4 (Syn4) is a proteoglycan that is involved in the migration of cells cultured in vitro, and it has been proposed as a key regulator of RhoA and Rac activities, focal adhesion formation and planar cell polarity (PCP) signaling (for a review, see Alexopoulou et al., 2007). In this study, we examined the role of Syn4 in neural crest migration in Xenopus and zebrafish embryos. We show that syn4 is expressed specifically in the migrating neural crest and that it is essential for its migration. In addition, we show that Syn4 controls directional migration by regulating the polarized formation of cell protrusions, in a manner similar to non-canonical Wnt signaling. In order to understand the molecular mechanism by which Syn4 and planar cell polarity (PCP) signaling control the orientation of cell protrusions, we performed fluorescence resonance energy transfer (FRET) analysis to measure the activity of the small GTPases, Cdc42, RhoA and Rac. This is the first time that this kind of FRET analysis has been carried out in vivo. Our results indicate that whereas Syn4 inhibits Rac activity, PCP signaling activates RhoA. In addition, we show that RhoA, through Rock, is an inhibitor of Rac activity in the neural crest. Thus, the
characters according to some non-trivial permutation of the alphabet, but then we must store that permutation such that we can evaluate and invert it quickly. In Section 3 we consider another kind of non-canonical prefix-free code, which Claude, Navarro, and Ord´ o˜ nez  introduced recently to reduce the space usage of their wavelet matrices. (Wavelet matrices are alternatives to wavelet trees [6, 10] that are more space efficient when the alphabet is large.) They showed how to build an optimal prefix-free code such that the codewords’ lengths are non- decreasing when they are arranged such that their reverses are in lexicographic order. They represent the code in O(σL) bits, and encode and decode a codeword of length ` in time O(`). We show how to store such a code in O(σ log L) bits, and still encode and decode any character in O(`) time. We also show that, by using O σ log L + 2 L
In a previous study, we demonstrated that activation of the canonical Wnt signaling pathway in hippocampal neurons pre- vents the neurotoxicity triggered by Aβ aggregates formed by amyloid fibrils (Alvarez et al., 2004). In the present study we showed for the first time that the activation of canonical and non- canonical Wnt signaling exerts a neuroprotective effect against A β oligomers at different levels: (1) firstly, the canonical Wnt/ β - catenin pathway primarily affects the whole neuronal repertoire; (2) secondly, the non-canonical Wnt pathway through the Wnt- 5a ligand specifically affects the mitochondrial compartment. In order to activate the canonical Wnt pathway we incubated hip- pocampal neurons with a GSK-3 β inhibitor (6-BIO) (Meijer et al., 2004). In these studies, the pre-incubation with 6-BIO, in a con- centration selected to inhibit GSK-3β (Polychronopoulos et al., 2004) prevented the decrease of β-catenin accumulation observed in neurons treated with A β oligomers, indicating that 6-BIO acts through the activation of the canonical Wnt/ β -catenin path- way protecting neurons from A β oligomer toxicity. On the other hand, our previous work (Silva-Alvarez et al., submitted) together with these results, suggest that the non-canonical Wnt path- way activation, using Wnt-5a ligand, protects neurons against the toxicity induced by A β oligomers, producing a regulation of calcium homeostasis, which is altered by the presence of A β oligomers.
Figure 6. Non-canonical splice sites are prone to be misannotated. (A) UCSC Genome Browser image shows a splice site area of ITPR1 where RNA- seq reads can be aligned in two ways. The difference between the two alignments relies on a TGAG sequence (yellow letters) that can be aligned with three mismatches, evidencing a canonical GT–AG splice junction (red alignment) or without mismatches, but evidencing a non-canonical GA–AG splice junction (green alignment). A GENCODE isoform is based on the suboptimal alignment (highlighted in red). Assembled transcript of ITPR1 based on Tophat RNA-seq alignments is based on the suboptimal alignment (highlighted in red). RT-PCR coupled to Sanger sequencing probed that this transcript does not have any mismatches with the genome. (B) ETV1 gene has a constitutive TT–AG non-canonical splice junction that is annotated in GENCODE, but Cufflinks cannot assemble a continuous transcript for ETV1 due to TopHat’s inability to align non-canonical splice junctions.
Furthermore DNA nanostructures with hydrophobic regions on the outside could be inserted into the hydrophobic patch of membrane cell in gene-delivery techniques. For example, non–viral vectors such as functionalized cationic lipids or polymers that can condense DNA in a non-aqueous media (Strobel and Dervan 1990; Feng Y. 1999; Pereira G.G. 2001; Montesi A. 2004), show great advantages over viruses in terms of safety and low immunogenicity (Brown 2001). However, the transfection efficiency of non-viral vectors is lower than achievable with viruses, which is likely to be related to the nature of the structure formed by the DNA interaction with cationic lipids or polymers (Koltover 1998; Ewert 2004; Ewert 2005). Knowledge of the dependence between solvent and structure will certainly favor our ability to desire more efficient nucleic acids carriers. The first part of this thesis aims to elucidate the behavior of nucleic acids in apolar environment, in particular to estimate the free energy barrier to overcome polar/apolar boundary, i.e. water/lipid barrier useful for gene delivery application.
After having indicated the pedagogical objectives of this study, we deal with the theory of language and the theory of leaning. We are going to begin with the theory of language, that in this case is the interactional perspective, this theory focuses on the idea that children have the desire to communicate with others, defined the language as a vehicle that allows the human relations as well as the interaction in the society. Following that thought, Rigg (1991) states that “Language use is always in a social context and it applies to both oral and written language”. (p.523) when the language is seen from an interactional perspective it is important to mention the relevance of locating the language as authentic, it means, that language needs to be developed in an environment where the student can express ideas facing real communicative situations. Hirtle (1996) claims “language has the function of mediator between the learner and the world” (p.91) based on those words, we as researchers during our pedagogical intervention, stated different communicative situations where students could express ideas about social issues like the poverty, the inequity, the power relations about gender, etc. These topics were born from the implementation of the readings from the non- canonical perspective which allowed us to see the way the students felt themselves in relation to aspects they could contextualize with their daily life, by doing processes focuses on
2010). By contrast, the Wnt/β-catenin pathway is activated by the binding of a Wnt ligand to its Fz receptor and to the co- receptor LRP5/6 (Willert and Nusse, 2012; Liu et al., 2014). This interaction activates Dvl and causes the dissociation of the destruction complex to inhibit the glycogen synthase kinase- 3β (GSK-3β) and to prevent β-catenin degradation through the proteasome, inducing its accumulation into the cytoplasm, which finally translocates to the nucleus and triggers the expression of Wnt target genes (Arrázola et al., 2009; Clevers and Nusse, 2012). Canonical Wnt signaling has been implicated in neuroprotection against Aβ-induced neuronal damage (Cerpa et al., 2009). In fact, its activation protects hippocampal neurons from Aβ-induced cell death (Alvarez et al., 2004), and also prevents the intracellular calcium increase generated by Aβ in neurons, which directly affects mitochondrial calcium levels (Quintanilla et al., 2005; Dinamarca et al., 2010). In addition, we have demonstrated that the non-canonical Wnt pathway, through its ligand Wnt5a, also has a neuroprotective response against Aβ exposition through the modulation of mitochondrial dynamics (Silva-Alvarez et al., 2013). However, the mechanism by which this protection occurs is unknown. Recently, our lab explored whether Wnt signaling could exert its neuroprotective role against Aβ-induced toxicity through the protection of the mitochondria (Arrázola and Inestrosa, 2013).
In order to determine whether Fz1 could have a presynap- tic role, we evaluated Bassoon clustering during the initial stages of synaptic assembly in neurons treated for 24 h with different concentrations of the soluble Fz1 CRD (Fig- ure 4A). In these hippocampal neurons at 9 DIV, there was a significant decrease in the density of Bassoon clus- ters after treatment with 1 μg/ml Fz1-CRD (34.42 ± 0.98 Bassoon puncta per 100 μm neurite length) compared to control (40.12 ± 1.07). This decrease was not observed when neurons were treated with 1 μg/ml of the soluble CRD of the Fz2 receptor, which has been shown to be involved in non-canonical Wnt pathways [22,23] (40.18 ± 0.73 Bassoon puncta per 100 μm), indicating a specific effect of Fz1 on Bassoon clustering that is not mediated by all Fz receptors. Figure 4B shows representative images of control neurons and neurons treated with 1 μg/ml Fz1- CRD or Fz2-CRD. This result suggests that Fz1 may nor- mally participate in the presynaptic differentiation. To fur- ther assess this hypothesis, we overexpressed Fz1 in hippocampal neurons. First, to evaluate whether overex- pressed Fz1 localizes at presynaptic sites, neurons were transfected with GFP-tagged Fz1. We observed that this receptor was present in axons stained with phosphor- ylated MAP1B (MAP1BP) antibody (Figure 4C, upper
Given a group theoretical property P , a P -critical group or a minimal non- P -group is a group which is not P -group but all of whose proper subgroups are P -groups. There are many remarkable examples about the minimal non- P -groups: minimal non-abelian groups (Miller and Moreno ), minimal non- nilpotent groups (Schmidt), minimal non-supersolvable groups (), minimal non- p-nilpotent groups (Itˆ o), minimal non-PN-groups (), minimal non-M SP -groups (), and minimal non-NSN-groups (). In this paper, by applying the structure of B -groups, we give the classification of minimal non- B -groups.
The analytical expressions presented above not only reflect the non-reciprocity of the lattice, but also accurately predict the simulation results including the more general scenario with multiple crossings. Also, it is found that the power is very susceptible to the system speed as it moves across the Bragg scattering points, where the passage time determines the amount of energy gained/lost by the light beam. This mechanism can be used as a way to control the intensity of the light beam in a complex waveguide array.
This philosophical difference can be explained with the help of the Nash Equilibrium. Using the classic “prisoner’s dilemma,” the mathematician John Nash showed that it is precisely the non-coopera- tion of parties that results in equi- librium. The possibility of getting a reduced sentence is so strong an incentive for the prisoner that betrayal of his partner in crime — the most selfish choice — be- comes his best option. However, Nash extended the two-party, zero- sum scenario to any situation with n number of participants. He ar- gued that there are games in which pla yers coordinate their choices and negotiate among themselves. He called this phenomenon “the bargaining solution”.
34 “... Utrum ecclesia peccet permittendo iudeos ritus suos observare. Responde quod non, quia non approbat sed permittit. Quod autem permittimus nolentes precipimus, id est concedimus, quia malorum hominum voluntatem ad plenum non possumus prohibere...”, A. Carletti, Summa Angelica, nr. 33, fol. 186ra. 35 “... Sexto, prohibetur eis ne novas synagogas erigant, … Possunt tamen antiquas reedificare vel rui- nosas resarcire, ita tamen quod nova edificatio non perdat antiquam formam...”, A. Carletti, Summa Angelica, nr. 11, fol. 185ra.
Nas peculiaridades e arbitrariedades españolas, nas malas traducións fillas das men- tes colonizadas contan casos parecidos ao anterior. Un é moi vello, «ciencia ficción» (science fiction: ficción científica); outro agora está de moda no xornalismo (lémbrese a recente guerra do Iraq) e na telemática: «embebido» (embedded: incrustado ou embutido. Parece estraño que non se traducise por «encamado»).
We see that various model of linear gravity theories involving non-geometrical ﬁelds acting as Lagrange multipliers can be constructed. From the gauge in- variant point of view two diﬀerent members can be distinguished: The original model[1, 2] based on the SO(2, 1) group and the ”string-inspired” model[3, 4] based on the extended Poincar´ e group. In particular in Ref. the model is based on an unconventional contraction of the SO(2, 1) model. This last is possible because of the ambiguity of two-dimensional angular momentum. Re- ally, in Eqs.(6) it can be replaced J by J + sI/i and λ by λ/s and set s → ∞ giving rise to the Eqs. (8).