Positive selection pressure within teleost toll-like receptors tlr21 and tlr22 subfamilies and their response to temperature stress and microbial components in zebrafish

AbstractThe high degree of conservation of toll-like receptors (TLRs), and yet their subtle variations for better adaptation of species in the host–pathogen arms race make them worthy candidates for understanding evolution. We have attempted to track the trend of TLR evolution in the most diverse vertebrate group—teleosts, where Clarias batrachus was given emphasis, considering its traits for terrestrial adaptation. Eleven C. batrachus TLRs (TLR1, 2, 3, 5, 7, 8 9, 13, 22, 25, 26) were identified in this study which clustered in proximity to its Siluriformes relative orthologues in the phylogenetic analysis of 228 TLRs from 25 teleosts. Ten TLRs (TLR1, 2, 3, 5, 7, 8 9, 13, 21, 22) with at least 15 member orthologues for each alignment were processed for selection pressure and coevolutionary analysis. TLR1, 7, 8 and 9 were found to be under positive selection in the alignment-wide test. TLR1 also showed maximum episodic diversification in its clades while the teleost group Eupercaria showed the maximum divergence in their TLR repertoire. Episodic diversification was evident in C. batrachus TLR1 and 7 alignments. These results present a strong evidence of a divergent TLR repertoire in teleosts which may be contributing towards species-specific variation in TLR functions.

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994 Combination therapy for hepatitis C: positive selection pressure at baseline is associated with virologic response to therapy

Hepatology ◽

10.1016/s0270-9139(03)81032-7 ◽

2003 ◽

Vol 38 ◽

pp. 634-635

Author(s):

V PARK ◽

S MENON ◽

B MASON ◽

R LI ◽

J KRUSHKAL ◽

...

Keyword(s):

Hepatitis C ◽

Combination Therapy ◽

Positive Selection ◽

Selection Pressure ◽

Virologic Response ◽

Response To Therapy ◽

Positive Selection Pressure

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Diversity analysis of amp gene sequences in the ‘Candidatus Phytoplasma meliae’

10.1101/2020.06.01.128413 ◽

2020 ◽

Author(s):

Franco D. Fernández ◽

Luis R. Conci

Keyword(s):

Membrane Proteins ◽

Positive Selection ◽

Selection Pressure ◽

Pathogenic Bacteria ◽

Extracellular Domain ◽

Gene Sequences ◽

Positive Selection Pressure ◽

Host Cytoplasm ◽

A Cell ◽

First Time

AbstractPhytoplasmas are plant pathogenic bacteria transmitted by insects. As endosymbiotic bacteria that lack a cell wall, their membrane proteins are in direct contact with host cytoplasm. In phytoplasmas the immunodominant membrane proteins (IDPs), are the most abundant proteins of the cell membrane. The antigenic membrane protein (Amp), one of the three types of IDPs, is characterized by a positive selection pressure acting in their extracellular domain. In South America, the ‘Candidatus Phytoplasma meliae’ has been associated to chinaberry yellows disease. In the present work, we describe for the first time the structure, phylogeny and selection pressure of amp gene in sixteen ‘Candidatus Phytoplasma meliae’ isolates. Our results indicate that amp gene sequences preserve the structure, large extracellular domain flanked by to hydrophobic domains in the N- (signal peptide) and C-termini (transmembrane), previously described in its orthologues and high divergence in the amino acids residues from extracellular domain. Moreover, a positive selection pressure was detected predominantly in this region confirming previous reports.

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