The Structure of ZCZ Sequences Based on the Almost Perfect Sequence

2010 ◽  
Author(s):  
Zhiwen Chang ◽  
Liying Sun
Keyword(s):  
Perfect Sequence

scholarly journals Anaplasma marginale Superinfection Attributable to Pathogen Strains with Distinct Genomic Backgrounds

2014 ◽  
Vol 82 (12) ◽  
pp. 5286-5292 ◽  
Author(s):  
Eduardo Vallejo Esquerra ◽  
David R. Herndon ◽  
Francisco Alpirez Mendoza ◽  
Juan Mosqueda ◽  
Guy H. Palmer
Keyword(s):  
High Throughput Sequencing ◽  
Anaplasma Marginale ◽  
Host Population ◽  
Content Type ◽  
Tropical Regions ◽  
Disease Epidemiology ◽  
Infectious Disease Epidemiology ◽  
Perfect Sequence ◽  
Significant Difference ◽  
High Prevalence

ABSTRACTStrain superinfection occurs when a second pathogen strain infects a host already infected with a primary strain. The selective pressures that drive strain divergence, which underlies superinfection, and allow penetration of a new strain into a host population are critical knowledge gaps relevant to shifts in infectious disease epidemiology. In regions of endemicity with a high prevalence of infection, broad population immunity develops againstAnaplasma marginale, a highly antigenically variant rickettsial pathogen, and creates strong selective pressure for emergence of and superinfection with strains that differ in their Msp2 variant repertoires. The strains may emerge either bymsp2locus duplication and allelic divergence on an existing genomic background or by introduction of a strain with a differentmsp2allelic repertoire on a distinct genomic background. To answer this question, we developed a multilocus typing assay based on high-throughput sequencing of non-msp2target loci to distinguish among strains with different genomic backgrounds. The technical error level was statistically defined based on the percentage of perfect sequence matches of clones of each target locus and validated using experimental single strains and strain pairs. Testing ofA. marginale-positive samples from tropical regions whereA. marginaleinfection is endemic identified individual infections that contained unique alleles for all five targeted loci. The data revealed a highly significant difference in the number of strains per animal in the tropical regions compared to infections in temperate regions and strongly supported the hypothesis that transmission of genomically distinctA. marginalestrains predominates in high-prevalence areas of endemicity.

Many transcribed regions of the Onchocerca volvulus genome contain the spliced leader sequence of Caenorhabditis elegans

1990 ◽  
Vol 10 (6) ◽  
pp. 2765-2773
Author(s):  
W L Zeng ◽  
C M Alarcon ◽  
J E Donelson
Keyword(s):  
Caenorhabditis Elegans ◽  
Repeat Unit ◽  
5S Rrna ◽  
Onchocerca Volvulus ◽  
Rrna Genes ◽  
Free Living ◽  
Spliced Leader ◽  
C Elegans ◽  
Perfect Sequence ◽  
5S Rrna Genes

Genomic DNAs of the related parasitic nematodes Onchocerca volvulus and Dirofilariae immitis, and a cDNA library of O. volvulus, were examined for the presence of the 22-nucleotide spliced leader (SL) found at the 5' ends of 10 to 15% of the mRNAs in the free-living nematode Caenorhabditis elegans. As in C. elegans, genes for the SL RNA are linked to the repetitive 5S rRNA genes of O. volvulus and D. immitis, but unlike C. elegans, they are in the same orientation as the 5S rRNA genes within the repeat unit. In O. volvulus the SL sequence is also encoded at more than 30 additional genomic locations and occurs at interior sites within many transcripts. Sequence determinations of four different cDNAs of O. volvulus, each containing an internal copy of the SL within a conserved 25mer, and one corresponding genomic DNA clone indicate that this sequence is not trans spliced onto these RNAs, but is encoded within the genes. The RNAs of two of these cDNAs appear to be developmentally regulated, since they occur in adult O. volvulus but were not detected in the infective L3 stage larvae. In contrast, actin mRNAs are present at all developmental stages, and at least one actin mRNA species contains a trans-spliced 5' SL. The internal locations of the SL in various transcripts and its perfect sequence conservation among parasitic and free-living nematodes argues that it serves specific, and perhaps multiple, functions for these organisms.

scholarly journals On the Dvoretzky-Rogers theorem

1984 ◽  
Vol 27 (2) ◽  
pp. 105-113
Author(s):  
Fuensanta Andreu
Keyword(s):  
Sequence Space ◽  
Normed Space ◽  
Sequence Spaces ◽  
Finite Dimensional ◽  
Banach Sequence Spaces ◽  
Perfect Sequence ◽  
Normal Topology ◽  
Banach Sequence

The classical Dvoretzky-Rogers theorem states that if E is a normed space for which l1(E)=l1{E} (or equivalently , then E is finite dimensional (see [12] p. 67). This property still holds for any lp (l<p<∞) in place of l1 (see [7]p. 104 and [2] Corollary 5.5). Recently it has been shown that this result remains true when one replaces l1 by any non nuclear perfect sequence space having the normal topology (see [14]). In this context, De Grande-De Kimpe [4] gives an extension of the Devoretzky-Rogers theorem for perfect Banach sequence spaces.

scholarly journals II.—On the Continuity and Breaks Between the Various Divisions of the Silurian Strata in the Lake District

1872 ◽  
Vol 9 (100) ◽  
pp. 441-442 ◽  
Author(s):  
W. Talbot Aveline
Keyword(s):  
Lake District ◽  
Perfect Sequence ◽  
Volcanic Series

In a former communication I stated that the line of division between the Skiddaw Slates and the overlying Volcanic series (Green Slates and Porphyries), in the neighbourhood of Keswick, was a faulted one, and not an unconformity, as supposed by Mr. Dakyns. I added that the evidence of an unconformity (if there was one), between these two series of beds, must be sought for elsewhere than in the district described by Mr. Dakyns. Since then I have examined many miles of boundary between these formations, and have as yet only seen one unfaulted junction, and this is near Bootle, in the Black Combe district, Cumberland; but this section at once sets at rest the question of unconformity or conformity. Not only do the Volcanic series lie at the same inclination with the Skiddaw Slates below them, but beds of the latter alternate with beds of the former, showing a perfect sequence and conformity. When the whole of the boundaries between the Skiddaw Slates and Volcanic series are traced, there may be found other spots also showing conformity and passage.

On Langford’s Problem (I)

1959 ◽  
Vol 43 (346) ◽  
pp. 250-253
Author(s):  
C. J Priday
Keyword(s):  
Perfect Sequence

For numbers a ≥ b ≥ l we shall denote by (a, b) the set of numbers b, b + 1, …, a. We shall say that a set S of numbers is perfect if there exists a sequence containing just one pair of each of the numbers in S, satisfying the condition: for every number r in the set, the two r’s are separated by exactly r places, and having no gaps (a perfect sequence).

scholarly journals Non-Target Effects of dsRNA Molecules in Hemipteran Insects

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 407
Author(s):  
Arinder K. Arora ◽  
Seung Ho Chung ◽  
Angela E. Douglas
Keyword(s):  
Acyrthosiphon Pisum ◽  
Insect Pest ◽  
Pest Species ◽  
Sequence Identity ◽  
Specific Effects ◽  
Perfect Sequence ◽  
Sap Feeding ◽  
Aphid Feeding ◽  
Target Effects

Insect pest control by RNA interference (RNAi)-mediated gene expression knockdown can be undermined by many factors, including small sequence differences between double-stranded RNA (dsRNA) and the target gene. It can also be compromised by effects that are independent of the dsRNA sequence on non-target organisms (known as sequence-non-specific effects). This study investigated the species-specificity of RNAi in plant sap-feeding hemipteran pests. We first demonstrated sequence-non-specific suppression of aphid feeding by dsRNA at dietary concentrations ≥0.5 µg µL−1. Then we quantified the expression of NUC (nuclease) genes in insects administered homologous dsRNA (with perfect sequence identity to the target species) or heterologous dsRNA (generated against a related gene of non-identical sequence in a different insect species). For the aphids Acyrthosiphon pisum and Myzus persicae, significantly reduced NUC expression was obtained with the homologous but not heterologous dsRNA at 0.2 µg µL−1, despite high dsNUC sequence identity. Follow-up experiments demonstrated significantly reduced expression of NUC genes in the whitefly Bemisia tabaci and mealybug Planococcus maritimus administered homologous dsNUCs, but not heterologous aphid dsNUCs. Our demonstration of inefficient expression knockdown by heterologous dsRNA in these insects suggests that maximal dsRNA sequence identity is required for RNAi targeting of related pest species, and that heterologous dsRNAs at appropriate concentrations may not be a major risk to non-target sap-feeding hemipterans.

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