scholarly journals Silent-substitution stimuli silence the light responses of cones but not their output

2019 ◽  
Vol 19 (5) ◽  
pp. 14 ◽  
Author(s):  
Sizar Kamar ◽  
Marcus H. C. Howlett ◽  
Maarten Kamermans
Keyword(s):  
Light Responses ◽  
Silent Substitution

Nitrogen and Light Responses of Cotton Photosynthesis and Implications for Crop Growth

Crop Science ◽  
2003 ◽  
Vol 43 (3) ◽  
pp. 904 ◽  
Author(s):  
Stephen P. Milroy ◽  
Michael P. Bange
Keyword(s):  
Crop Growth ◽  
Light Responses

scholarly journals Genome communication in plants mediated by organelle–n­ucleus-located proteins

2020 ◽  
Vol 375 (1801) ◽  
pp. 20190397 ◽  
Author(s):  
Karin Krupinska ◽  
Nicolás E. Blanco ◽  
Svenja Oetke ◽  
Michela Zottini
Keyword(s):  
Chloroplast Development ◽  
Cell Cycle Control ◽  
Plastid Transformation ◽  
Light Responses ◽  
Dual Targeting ◽  
Dual Localization ◽  
Retrograde Signalling ◽  
Eukaryotic Proteins ◽  
Plastid Proteins ◽  
Associated Proteins

An increasing number of eukaryotic proteins have been shown to have a dual localization in the DNA-containing organelles, mitochondria and plastids, and/or the nucleus. Regulation of dual targeting and relocation of proteins from organelles to the nucleus offer the most direct means for communication between organelles as well as organelles and nucleus. Most of the mitochondrial proteins of animals have functions in DNA repair and gene expression by modelling of nucleoid architecture and/or chromatin. In plants, such proteins can affect replication and early development. Most plastid proteins with a confirmed or predicted second location in the nucleus are associated with the prokaryotic core RNA polymerase and are required for chloroplast development and light responses. Few plastid–nucleus-located proteins are involved in pathogen defence and cell cycle control. For three proteins, it has been clearly shown that they are first targeted to the organelle and then relocated to the nucleus, i.e. the nucleoid-associated proteins HEMERA and Whirly1 and the stroma-located defence protein NRIP1. Relocation to the nucleus can be experimentally demonstrated by plastid transformation leading to the synthesis of proteins with a tag that enables their detection in the nucleus or by fusions with fluoroproteins in different experimental set-ups. This article is part of the theme issue ‘Retrograde signalling from endosymbiotic organelles’.

Amacrine and ganglion cell contributions to the electroretinogram in amphibian retina

2001 ◽  
Vol 18 (1) ◽  
pp. 147-156 ◽  
Author(s):  
GAUTAM AWATRAMANI ◽  
JUE WANG ◽  
MALCOLM M. SLAUGHTER
Keyword(s):  
Contrast Agents ◽  
Ganglion Cell ◽  
Neuronal Activity ◽  
Opposite Effect ◽  
Cell Function ◽  
Ganglion Cells ◽  
Field Potential ◽  
Tiger Salamander ◽  
Third Order ◽  
Light Responses

The neuronal generators of the b- and d-waves of the electroretinogram (ERG) were investigated in the tiger salamander retina to determine if amacrine and ganglion cells contribute to this field potential. Several agents were used that affect third-order neurons, such as tetrodotoxin, baclofen, and NMDA agonists and antagonists. Baclofen, an agent that enhances light responses in third-order neurons, increased the d-wave and reduced the b-wave. In contrast, agents that decrease light responses in third-order neurons had the opposite effect of enhancing the b-wave and depressing the d-wave. The effect on the d-wave was particularly pronounced. The results indicate that third-order neuronal activity influences b- and d-waves of the ERG. The opposing actions suggest that the b-wave to d-wave ratio might serve as an measure of ganglion cell function.

scholarly journals Cyclodextrin‐Assisted Delivery of Azobenzene Photoswitches for Uniform and Long‐Term Restoration of Light Responses in Degenerated Retinas of Blind Mice

2021 ◽  
pp. 2100127
Author(s):  
Kevin J. Cao ◽  
Elijah F. Lyons ◽  
Benjamin E. Smith ◽  
Bristol L. Denlinger ◽  
Hong Ma ◽  
...  
Keyword(s):  
Light Responses ◽  
Assisted Delivery

Likelihood Models of Somatic Mutation and Codon Substitution in Cancer Genes

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 695-705 ◽  
Author(s):  
Ziheng Yang ◽  
Simon Ro ◽  
Bruce Rannala
Keyword(s):  
Amino Acid ◽  
Gene Mutation ◽  
Somatic Mutation ◽  
Mutation Rates ◽  
Functional Domains ◽  
Cancer Gene ◽  
Structural Domains ◽  
Specific Amino Acid ◽  
Silent Substitution ◽  
Codon Substitution

Abstract The role of somatic mutation in cancer is well established and several genes have been identified that are frequent targets. This has enabled large-scale screening studies of the spectrum of somatic mutations in cancers of particular organs. Cancer gene mutation databases compile the results of many studies and can provide insight into the importance of specific amino acid sequences and functional domains in cancer, as well as elucidate aspects of the mutation process. Past studies of the spectrum of cancer mutations (in particular genes) have examined overall frequencies of mutation (at specific nucleotides) and of missense, nonsense, and silent substitution (at specific codons) both in the sequence as a whole and in a specific functional domain. Existing methods ignore features of the genetic code that allow some codons to mutate to missense, or stop, codons more readily than others (i.e., by one nucleotide change, vs. two or three). A new codon-based method to estimate the relative rate of substitution (fixation of a somatic mutation in a cancer cell lineage) of nonsense vs. missense mutations in different functional domains and in different tumor tissues is presented. Models that account for several potential influences on rates of somatic mutation and substitution in cancer progenitor cells and allow biases of mutation rates for particular dinucleotide sequences (CGs and dipyrimidines), transition vs. transversion bias, and variable rates of silent substitution across functional domains (useful in detecting investigator sampling bias) are considered. Likelihood-ratio tests are used to choose among models, using cancer gene mutation data. The method is applied to analyze published data on the spectrum of p53 mutations in cancers. A novel finding is that the ratio of the probability of nonsense to missense substitution is much lower in the DNA-binding and transactivation domains (ratios near 1) than in structural domains such as the linker, tetramerization (oligomerization), and proline-rich domains (ratios exceeding 100 in some tissues), implying that the specific amino acid sequence may be less critical in structural domains (e.g., amino acid changes less often lead to cancer). The transition vs. transversion bias and effect of CpG dinucleotides on mutation rates in p53 varied greatly across cancers of different organs, likely reflecting effects of different endogenous and exogenous factors influencing mutation in specific organs.

scholarly journals Neurospora crassa Light Signal Transduction Is Affected by ROS

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Tatiana A. Belozerskaya ◽  
Natalia N. Gessler ◽  
Elena P. Isakova ◽  
Yulia I. Deryabina
Keyword(s):  
Neurospora Crassa ◽  
Zinc Fingers ◽  
White Collar ◽  
Photochemical Activity ◽  
Light Signal ◽  
Pas Domain ◽  
Light Responses ◽  
Expression Of Genes ◽  
Heterodimeric Complex ◽  
Light Signals

In the ascomycete fungus Neurospora crassa blue-violet light controls the expression of genes responsible for differentiation of reproductive structures, synthesis of secondary metabolites, and the circadian oscillator activity. A major photoreceptor in Neurospora cells is WCC, a heterodimeric complex formed by the PAS-domain-containing polypeptides WC-1 and WC-2, the products of genes white collar-1 and white collar-2. The photosignal transduction is started by photochemical activity of an excited FAD molecule noncovalently bound by the LOV domain (a specialized variant of the PAS domain). The presence of zinc fingers (the GATA-recognizing sequences) in both WC-1 and WC-2 proteins suggests that they might function as transcription factors. However, a critical analysis of the phototransduction mechanism considers the existence of residual light responses upon absence of WCC or its homologs in fungi. The data presented point at endogenous ROS generated by a photon stimulus as an alternative input to pass on light signals to downstream targets.

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