Faculty Opinions recommendation of vsp gene expression by Giardia lamblia clone GS/M-83-H7 during antigenic variation in vivo and in vitro.

2001 ◽  
Author(s):  
Jacqueline Upcroft
Keyword(s):  
Gene Expression ◽  
Giardia Lamblia ◽  
Antigenic Variation

scholarly journals A Novel Spo11 Homologue Functions as a Positive Regulator in Cyst Differentiation in Giardia lamblia

2021 ◽  
Vol 22 (21) ◽  
pp. 11902
Author(s):  
Yu-Chien Chen ◽  
Szu-Yu Tung ◽  
Chia-Wei Huang ◽  
Soo-Wah Gan ◽  
Bo-Chi Lin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cyst Wall ◽  
Giardia Lamblia ◽  
Genetic Material ◽  
Cyst Formation ◽  
Positive Regulator ◽  
Double Stranded Dna ◽  
Recombination Processes

Giardia lamblia persists in a dormant state with a protective cyst wall for transmission. It is incompletely known how three cyst wall proteins (CWPs) are coordinately synthesized during encystation. Meiotic recombination is required for sexual reproduction in animals, fungi, and plants. It is initiated by formation of double-stranded breaks by a topoisomerase-like Spo11. It has been shown that exchange of genetic material in the fused nuclei occurs during Giardia encystation, suggesting parasexual recombination processes of this protozoan. Giardia possesses an evolutionarily conserved Spo11 with typical domains for cleavage reaction and an upregulated expression pattern during encystation. In this study, we asked whether Spo11 can activate encystation process, like other topoisomerases we previously characterized. We found that Spo11 was capable of binding to both single-stranded and double-stranded DNA in vitro and that it could also bind to the cwp promoters in vivo as accessed in chromatin immunoprecipitation assays. Spo11 interacted with WRKY and MYB2 (named from myeloblastosis), transcription factors that can activate cwp gene expression during encystation. Interestingly, overexpression of Spo11 resulted in increased expression of cwp1-3 and myb2 genes and cyst formation. Mutation of the Tyr residue for the active site or two conserved residues corresponding to key DNA-binding residues for Arabidopsis Spo11 reduced the levels of cwp1-3 and myb2 gene expression and cyst formation. Targeted disruption of spo11 gene with CRISPR/Cas9 system led to a significant decrease in cwp1-3 and myb2 gene expression and cyst number. Our results suggest that Spo11 acts as a positive regulator for Giardia differentiation into cyst.

scholarly journals vsp Gene Expression byGiardia lamblia Clone GS/M-83-H7 during Antigenic Variation In Vivo and In Vitro

2001 ◽  
Vol 69 (9) ◽  
pp. 5278-5285 ◽  
Author(s):  
M. Bienz ◽  
M. Siles-Lucas ◽  
P. Wittwer ◽  
N. Müller
Keyword(s):  
Gene Expression ◽  
Antigenic Variation ◽  
Expression Patterns ◽  
Amino Acid Level ◽  
Late Time ◽  
Continuous Change ◽  
Ancestral Gene ◽  
Time Points

ABSTRACT Giardia lamblia infections are associated with antigenic variation of the parasite, which is generated by a continuous change of the variant-specific surface proteins (VSPs). Many investigations on the process of antigenic variation were based on the use of G. lamblia clone GS/M-83-H7, which expresses VSP H7 as its major surface antigen. In the present study, mice were infected with the aforementioned clonal line to investigatevsp gene expression during the complex process of antigenic variation of the parasite. Trophozoites collected from the intestines of individual animals at different time points postinfection (p.i.) were analyzed directly for their vsp gene expression patterns, i.e., without cultivating the recovered parasites in vitro. Because few trophozoites were recovered at late time points p.i., a combined 5′ rapid amplification of cDNA ends–reverse transcription-PCR approach was utilized. This allowed detection and subsequent sequence analysis of vsp gene transcripts upon generation of amplified cDNA analogues. The same PCR approach was applied for analysis of vsp gene expression in variants obtained after negative selection of axenic GS/M-83-H7 trophozoites by treatment with a cytotoxic, VSP H7-specific monoclonal antibody. In an overall view of the entire panel of in vivo- and in vitro-derived parasite populations, expression of 29 different vspgene sequences could be demonstrated. In vivo antigenic variation ofG. lamblia clone GS/M-83-H7 was shown to be a continuous process involving the consecutive appearance of relatively distinct sets of vsp transcripts. During the 42-day infection period investigated, this process activated at least 22 differentvsp genes. Comparative molecular analyses of the amino acid level demonstrated that all cDNA segments identified encode structural elements typical of the terminal segment ofGiardia VSP. The similarity of most of the GS/M-83-H7 VSP sequences identified in the present study supports previous suggestions that vsp gene diversification in G. lamblia is the result of ancestral gene duplication, mutation, and/or recombination events.

scholarly journals Influence of Antibodies in Mother’s Milk on Antigenic Variation of Giardia lamblia in the Murine Mother-Offspring Model of Infection

1998 ◽  
Vol 66 (4) ◽  
pp. 1287-1292 ◽  
Author(s):  
S. Stäger ◽  
B. Gottstein ◽  
H. Sager ◽  
T. W. Jungi ◽  
N. Müller
Keyword(s):  
Giardia Lamblia ◽  
Antigenic Variation ◽  
Surface Protein ◽  
In Vitro Cultivation ◽  
New Variant ◽  
Iga Antibodies ◽  
Mother's Milk ◽  
Mother’S Milk

ABSTRACT In the present study, neonatal ZU.ICR mice and their mothers were infected with trophozoites of Giardia lamblia clone GS/M-83-H7 expressing the variant surface protein (VSP) H7. The infection experiments included a detailed analysis of the specificities of anti-Giardia immunoglobulin A (IgA) antibodies in mother’s milk and a determination of the effects of the milk antibodies on both the growth of the parasite during in vitro cultivation and colonization of the parasite within the intestine of suckling offspring. These investigations revealed that transiently emerging milk IgA antibodies against a variant-specific 314-amino-acid N-terminal region of VSP H7 exhibit a strong parasiticidal effect on VSP H7-type trophozoites both in vitro and in vivo. These findings indicated that parasiticidal effects of local IgA antibodies against the N-terminal part of VSP H7 select for new variant types within the intestinal parasite population of suckling mice. The selective influence of such antibodies promotes in vivo antigenic variation ofG. lamblia clone GS/M-83-H7 and modulates the early course of parasite infection in these animals.

Effect of X-irradiation on gene expression of rat liver chemokines: in vivo and in vitro studies

2008 ◽  
Vol 46 (01) ◽  
Author(s):  
F Moriconi ◽  
H Christiansen ◽  
H Christiansen ◽  
N Sheikh ◽  
J Dudas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rat Liver ◽  
In Vitro Studies ◽  
X Irradiation

Vibrio harveyi virulence gene expression in vitro and in vivo during infection in black tiger shrimp Penaeus monodon

2020 ◽  
Vol 139 ◽  
pp. 153-160
Author(s):  
S Peeralil ◽  
TC Joseph ◽  
V Murugadas ◽  
PG Akhilnath ◽  
VN Sreejith ◽  
...  
Keyword(s):  
Gene Expression ◽  
Virulence Genes ◽  
Vibrio Harveyi ◽  
Penaeus Monodon ◽  
Challenge Test ◽  
Virulence Gene ◽  
Economic Losses ◽  
Virulence Gene Expression

Luminescent Vibrio harveyi is common in sea and estuarine waters. It produces several virulence factors and negatively affects larval penaeid shrimp in hatcheries, resulting in severe economic losses to shrimp aquaculture. Although V. harveyi is an important pathogen of shrimp, its pathogenicity mechanisms have yet to be completely elucidated. In the present study, isolates of V. harveyi were isolated and characterized from diseased Penaeus monodon postlarvae from hatcheries in Kerala, India, from September to December 2016. All 23 tested isolates were positive for lipase, phospholipase, caseinase, gelatinase and chitinase activity, and 3 of the isolates (MFB32, MFB71 and MFB68) showed potential for significant biofilm formation. Based on the presence of virulence genes, the isolates of V. harveyi were grouped into 6 genotypes, predominated by vhpA+ flaB+ ser+ vhh1- luxR+ vopD- vcrD+ vscN-. One isolate from each genotype was randomly selected for in vivo virulence experiments, and the LD50 ranged from 1.7 ± 0.5 × 103 to 4.1 ± 0.1 × 105 CFU ml-1. The expression of genes during the infection in postlarvae was high in 2 of the isolates (MFB12 and MFB32), consistent with the result of the challenge test. However, in MFB19, even though all genes tested were present, their expression level was very low and likely contributed to its lack of virulence. Because of the significant variation in gene expression, the presence of virulence genes alone cannot be used as a marker for pathogenicity of V. harveyi.

Evidence that gene expression of ovarian follicular tight junction proteins is regulated in vivo and in vitro in cattle

2017 ◽  
Vol 95 (3) ◽  
pp. 1313 ◽  
Author(s):  
L. Zhang ◽  
L. F. Schütz ◽  
C. L. Robinson ◽  
M. L. Totty ◽  
L. J. Spicer
Keyword(s):  
Gene Expression ◽  
Tight Junction ◽  
Tight Junction Proteins ◽  
Junction Proteins

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

scholarly journals CircFAM13B promotes the proliferation of hepatocellular carcinoma by sponging miR-212, upregulating E2F5 expression and activating the P53 pathway

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ying Xie ◽  
Xiaofeng Hang ◽  
Wensheng Xu ◽  
Jing Gu ◽  
Yuanjing Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hepatocellular Carcinoma ◽  
Gene Expression Omnibus ◽  
Differentially Expressed ◽  
In Vivo Studies ◽  
Circular Rnas ◽  
Novel Target ◽  
Underlying Mechanisms

Abstract Background Most of the biological functions of circular RNAs (circRNAs) and the potential underlying mechanisms in hepatocellular carcinoma (HCC) have not yet been discovered. Methods In this study, using circRNA expression data from HCC tumor tissues and adjacent tissues from the Gene Expression Omnibus database, we identified out differentially expressed circRNAs and verified them by qRT-PCT. Functional experiments were performed to evaluate the effects of circFAM13B in HCC in vitro and in vivo. Results We found that circFAM13B was the most significantly differentially expressed circRNA in HCC tissue. Subsequently, in vitro and in vivo studies also demonstrated that circFAM13B promoted the proliferation of HCC. Further studies revealed that circFAM13B, a sponge of miR-212, is involved in the regulation of E2F5 gene expression by competitively binding to miR-212, inhibits the activation of the P53 signalling pathway, and promotes the proliferation of HCC cells. Conclusions Our findings revealed the mechanism underlying the regulatory role played by circFAM13B, miR-212 and E2F5 in HCC. This study provides a new theoretical basis and novel target for the clinical prevention and treatment of HCC.

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