Long-term potentiation (LTP) is considered a cellular correlate of learning and memory. The presence of G protein-activated inwardly rectifying K(+) (GIRK) channels near excitatory synapses on dendritic spines suggests their possible involvement in synaptic plasticity. However, whether activity-dependent regulation of channels affects excitatory synaptic plasticity is unknown. In a companion article we have reported activity-dependent regulation of GIRK channel density in cultured hippocampal neurons that requires activity oF receptors (NMDAR) and protein phosphatase-1 (PP1) and takes place within 15 min. In this study, we performed whole-cell recordings of cultured hippocampal neurons and found that NMDAR activation increases basal GIRK current and GIRK channel activation mediated by adenosine A(1) receptors, but not GABA(B) receptors. Given the similar involvement of NMDARs, adenosine receptors, and PP1 in depotentiation of LTP caused by low-frequency stimulation that immediately follows LTP-inducing high-frequency stimulation, we wondered whether NMDAR-induced increase in GIRK channel surface density and current may contribute to the molecular mechanisms underlying this specific depotentiation. Remarkably, GIRK2 null mutation or GIRK channel blockade abolishes depotentiation of LTP, demonstrating that GIRK channels are critical for depotentiation, one form of excitatory synaptic plasticity.
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Answer:
esta es una expresión de admiración ante la belleza de los mecanismos evolutivos
Explanation:
El concepto de evolución como mecanismos naturales que está actualmente en boga fue originalmente planteado por Charles Darwin en su celebre publicación "El origen de las especies" (1859). La teoría de la evolución de Darwin está basada en la idea que las especies cambian constantemente con el tiempo a través del proceso de selección natural. Este mecanismo es responsable de la inmensa biodiversidad biológica observada en la naturaleza, la cual incluye la evolución de las especies, poblaciones y organismos individuales. Desde una perspectiva biológica, es imposible no quedar fascinado ante la naturaleza y contemplación de los procesos evolutivos.
Answer:
In a chemical reaction, the atoms and molecules that interact with each other are called reactants. In a chemical reaction, the atoms and molecules produced by the reaction are called products.
Answer: c) amino acid
Explanation: A codon is an mRNA sequence which contains three nucleotides that codes for a particular amino acid. The codons on the mRNA are read by the ribosome during translation and the amino acid coded for by each codon is used to make a protein. There are 64 different codons in existence, each amino acid is coded for by at least one codon. Some amino acids have more than one codon. For example, the amino acid Leucine is coded for by six codons: UUA, UUG, CUU, CUC, CUA and CUG while the amino acid phenylalanine is coded for by two codons: UUU and UUC.
