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:
295
Explanation:
Antibodies (also known as immunoglobulins) are immune system-related proteins that circulate in the bloodstream in order to recognize pathogenic harmful substances (antigens) and neutralize them. An antibody consists of two immunoglobulin heavy chains and two immunoglobulin light chains. There are two types of immunoglobulin light chains: 1-the kappa (κ) light chain, which is encoded by the immunoglobulin κ locus; and 2-the lambda (λ) light chain, which is encoded by the immunoglobulin λ locus. The immunoglobulin light chain is a multidomain protein composed of two domains: 1- the N-terminal variable (V) domain and 2-the C-terminal constant (C) domain. V(D)J recombination is a type of somatic rearrangement process by which T and B cells can assemble different gene segments, which are referred to as variable (V), diversity (D) and joining (J) gene segments. In the question above the number of possible genomic recombination events between immunoglobulin gene segments can be calculated as >> (5 x 35) + (4 x 30) = 295.
Definition: "Copying of information from DNA to RNA which exit nucleus is known as transcription"
Explanation: Transcription is a vital process for living organisms, because it is a staring point for protein synthesis. It occurs inside the nucleus and is carried out by RNA polymerase enzyme. In eukaryotes RNA pol is of three types: these are RNA Pol 1, RNA Pol 2, and RNA Pol 3. In prokaryotes it is of only one type.
Steps in transcription: Transcription consists of three main steps
1. Initiation: In this step RNA pol attach to DNA template at 5 prime end in the promoter region to start the formation of complementary strand of RNA. In prokaryotes there is a region called
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Pribnow box, with the </span>consensus sequence<span> TATAAT present about 10 base pair away from site that serves as a transcription initiation. In eukaryotes the promoter region is more complex it contain activator and enhancer.
2. Strand elongation: </span><span>Once transcription is initiated, the DNA double helix unwinds and RNA polymerase reads the template strand, adding nucleotides to the 3′ end of the growing chain.
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3. Transcription Termination:
Terminator sequences are found close to the ends of non-coding sequences. Before termination polyadenylation occurs. <span>
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They are composed of actin, troponin, tropomyosin, and myosin
CONSTRUCTION OF HYPOTHESIS is missing from the experiment. The correct option is B.
A scientific hypothesis is a foundation that must be well laid in any scientific experimental research. A research hypothesis refers to statements made by a researcher which defines his speculations on the outcomes of the research, it is an educated guess that is based on prior knowledge and observations.