Gene inactivation system extension into a unique sequence outside of the II →> I insertional duplication in Aspergillus nidulans

1998 ◽  
Vol 44 (11) ◽  
pp. 1037-1044
Author(s):  
M Meilus ◽  
MAA Castro-Prado

The first report of the gene inactivation system (GIS) in Aspergillus nidulans came from crosses involving a II Gene inactivation system extension into a unique sequence outside of the II →> I insertional duplication. Duplicated segments trigger the GIS that acts through the methylation of cytosines present within repeats. Duplicated genes are probably inactivated during the premeiotic period between fertilization and karyogamy, but reactivation may occur spontaneously or after 5-azacytidine treatment. The aim of the present study was to determine the action of GIS on a single copy gene located near a duplicated segment. Aspergillus nidulans strains bearing the Dp(II,I) duplication were used in meiotic crosses homozygous for the y+ gene and yellow (y) segregants were recovered among the progenies. Data show that the GIS can act on a closely linked gene outside the duplicated segment, promoting reversible inactivation. Reduction of ascospore numbers and viability were observed in crosses parented by duplication strains. Inactivation of the w+ gene in a w/w+ duplication strain is also shown.Key words: Aspergillus nidulans, gene inactivation, DNA methylation, chromosomal duplication.

Genetics ◽  
2003 ◽  
Vol 163 (2) ◽  
pp. 803-810 ◽  
Author(s):  
Hideki Innan

Abstract The infinite-site model of a small multigene family with two duplicated genes is studied. The expectations of the amounts of nucleotide variation within and between two genes and linkage disequilibrium are obtained, and a coalescent-based method for simulating patterns of polymorphism in a small multigene family is developed. The pattern of DNA variation is much more complicated than that in a single-copy gene, which can be simulated by the standard coalescent. Using the coalescent simulation of duplicated genes, the applicability of statistical tests of neutrality to multigene families is considered.


1992 ◽  
Vol 84 (4) ◽  
pp. 561-567 ◽  
Author(s):  
Poul E. Jensen ◽  
Michael Kristensen ◽  
Tine Hoff ◽  
Jan Lehmbeck ◽  
Bjarne M. Stummann ◽  
...  

Genomics ◽  
1998 ◽  
Vol 48 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Yu-Ker Wang ◽  
Luis A. Pérez-Jurado ◽  
Uta Francke

2003 ◽  
Vol 10 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Tamece T. Knowles ◽  
A. Rick Alleman ◽  
Heather L. Sorenson ◽  
David C. Marciano ◽  
Edward B. Breitschwerdt ◽  
...  

ABSTRACT Canine monocytic ehrlichiosis, caused by Ehrlichia canis or Ehrlichia chaffeensis, can result in clinical disease in naturally infected animals. Coinfections with these agents may be common in certain areas of endemicity. Currently, a species-specific method for serological diagnosis of monocytic ehrlichiosis is not available. Previously, we developed two indirect enzyme-linked immunosorbent assays (ELISAs) using the major antigenic protein 2 (MAP2) of E. chaffeensis and E. canis. In this study, we further characterized the conservation of MAP2 among various geographic isolates of each organism and determined if the recombinant MAP2 (rMAP2) of E. chaffeensis would cross-react with E. canis-infected dog sera. Genomic Southern blot analysis using digoxigenin-labeled species-specific probes suggested that map2 is a single-copy gene in both Ehrlichia species. Sequences of the single map2 genes of seven geographically different isolates of E. chaffeensis and five isolates of E. canis are highly conserved among the various isolates of each respective ehrlichial species. ELISA and Western blot analysis confirmed that the E. chaffeensis rMAP2 failed to serologically differentiate between E. canis and E. chaffeensis infections.


2021 ◽  
Vol 9 (8) ◽  
pp. 1610
Author(s):  
Christian Klotz ◽  
Elke Radam ◽  
Sebastian Rausch ◽  
Petra Gosten-Heinrich ◽  
Toni Aebischer

Giardiasis in humans is a gastrointestinal disease transmitted by the potentially zoonotic Giardia duodenalis genotypes (assemblages) A and B. Small wild rodents such as mice and voles are discussed as potential reservoirs for G. duodenalis but are predominantly populated by the two rodent species Giardia microti and Giardia muris. Currently, the detection of zoonotic and non-zoonotic Giardia species and genotypes in these animals relies on cumbersome PCR and sequencing approaches of genetic marker genes. This hampers the risk assessment of potential zoonotic Giardia transmissions by these animals. Here, we provide a workflow based on newly developed real-time PCR schemes targeting the small ribosomal RNA multi-copy gene locus to distinguish G. muris, G. microti and G. duodenalis infections. For the identification of potentially zoonotic G. duodenalis assemblage types A and B, an established protocol targeting the single-copy gene 4E1-HP was used. The assays were specific for the distinct Giardia species or genotypes and revealed an analytical sensitivity of approximately one or below genome equivalent for the multi-copy gene and of about 10 genome equivalents for the single-copy gene. Retesting a biobank of small rodent samples confirmed the specificity. It further identified the underlying Giardia species in four out of 11 samples that could not be typed before by PCR and sequencing. The newly developed workflow has the potential to facilitate the detection of potentially zoonotic and non-zoonotic Giardia species in wild rodents.


1989 ◽  
Vol 9 (1) ◽  
pp. 329-331
Author(s):  
M Winey ◽  
I Edelman ◽  
M R Culbertson

Saccharomyces cerevisiae glutamine tRNA(CAG) is encoded by an intronless, single-copy gene, SUP60. We have imposed a requirement for splicing in the biosynthesis of this tRNA by inserting a synthetic intron in the SUP60 gene. Genetic analysis demonstrated that the interrupted gene produces a functional, mature tRNA product in vivo.


Genetics ◽  
2021 ◽  
Author(s):  
Takahiro Sakamoto ◽  
Hideki Innan

Abstract Muller’s ratchet is a process in which deleterious mutations are fixed irreversibly in the absence of recombination. The degeneration of the Y chromosome, and the gradual loss of its genes, can be explained by Muller’s ratchet. However, most theories consider single-copy genes, and may not be applicable to Y chromosomes, which have a number of duplicated genes in many species, which are probably undergoing concerted evolution by gene conversion. We developed a model of Muller’s ratchet to explore the evolution of the Y chromosome. The model assumes a non-recombining chromosome with both single-copy and duplicated genes. We used analytical and simulation approaches to obtain the rate of gene loss in this model, with special attention to the role of gene conversion. Homogenization by gene conversion makes both duplicated copies either mutated or intact. The former promotes the ratchet, and the latter retards, and we ask which of these counteracting forces dominates under which conditions. We found that the effect of gene conversion is complex, and depends upon the fitness effect of gene duplication. When duplication has no effect on fitness, gene conversion accelerates the ratchet of both single-copy and duplicated genes. If duplication has an additive fitness effect, the ratchet of single-copy genes is accelerated by gene duplication, regardless of the gene conversion rate, whereas gene conversion slows the degeneration of duplicated genes. Our results suggest that the evolution of the Y chromosome involves several parameters, including the fitness effect of gene duplication by increasing dosage and gene conversion rate.


1985 ◽  
Vol 5 (5) ◽  
pp. 1151-1162
Author(s):  
D J Bergsma ◽  
K S Chang ◽  
R J Schwartz

We identified a novel chicken actin gene. The actin protein deduced from its nucleotide sequence very closely resembles the vertebrate cytoplasmic actins; accordingly, we classified this gene as a nonmuscle type. We adopted the convention for indicating the nonmuscle actins of the class Amphibia (Vandekerckhove et al., J. Mol. Biol. 152:413-426) and denoted this gene as type 5. RNA blot analysis demonstrated that the type 5 actin mRNA transcripts accumulate in adult tissues in a pattern indicative of a nonmuscle actin gene. Genomic DNA blots indicated that the type 5 actin is a single copy gene and a distinct member of the chicken actin multigene family. Inspection of the nucleotide sequence revealed many features that distinguished the type 5 gene from all other vertebrate actin genes examined to date. These unique characteristics include: (i) an initiation Met codon preceding an Ala codon, a feature previously known only in plant actins, (ii) a single intron within the 5' untranslated region, with no interruptions in the coding portion of the gene, and (iii) an atypical Goldberg-Hogness box (ATAGAA) preceding the mRNA initiation terminus. These unusual features have interesting implications for actin gene diversification during evolution.


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