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Entamoeba shows reversible variation in ploidy under different growth conditions and between life cycle phases.

Mukherjee C, Clark CG, Lohia A - PLoS Negl Trop Dis (2008)

Bottom Line: Changes in DNA content during encystation-excystation were studied in the related reptilian parasite E. invadens.Based on the observed large changes in nuclear size and DNA content, and the minor differences in relative abundance of representative protein coding sequences, rDNA and tRNA sequences, it appears that gain or loss of whole genome copies may be occurring during changes in the growth conditions.Our studies demonstrate the inherent plasticity and dynamic nature of the Entamoeba genome in at least two species.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Bose Institute, Kolkata, India.

ABSTRACT
Under axenic growth conditions, trophozoites of Entamoeba histolytica contain heterogenous amounts of DNA due to the presence of both multiple nuclei and different amounts of DNA in individual nuclei. In order to establish if the DNA content and the observed heterogeneity is maintained during different growth conditions, we have compared E. histolytica cells growing in xenic and axenic cultures. Our results show that the nuclear DNA content of E. histolytica trophozoites growing in axenic cultures is at least 10 fold higher than in xenic cultures. Re-association of axenic cultures with their bacterial flora led to a reduction of DNA content to the original xenic values. Thus switching between xenic and axenic growth conditions was accompanied by significant changes in the nuclear DNA content of this parasite. Changes in DNA content during encystation-excystation were studied in the related reptilian parasite E. invadens. During excystation of E. invadens cysts, it was observed that the nuclear DNA content increased approximately 40 fold following emergence of trophozoites in axenic cultures. Based on the observed large changes in nuclear size and DNA content, and the minor differences in relative abundance of representative protein coding sequences, rDNA and tRNA sequences, it appears that gain or loss of whole genome copies may be occurring during changes in the growth conditions. Our studies demonstrate the inherent plasticity and dynamic nature of the Entamoeba genome in at least two species.

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Related in: MedlinePlus

E. histolytica trophozoites show heterogeneity in nuclear number during intestinal tissue invasion.Intestinal tissue sections were stained with polyclonal anti-Eh lectin antibody to identify amoeba cells followed by hematoxylin staining of the nuclei. (A) Two representative images are shown where amoeba cells (indicated by arrowheads) contain different number of nuclei (indicated by arrows). Scale bar is 10 µm. (The image of each amoeba cell was verified at high magnification to be of a single intact cell and the size of host cell nuclei was found to be double that of the amoeba nuclei- data not shown). (B) Intestinal tissue sections (n = 3) were counted for the presence of uni- (1), bi- (2) and multi- (>2) nucleated amoeba cells.
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pntd-0000281-g005: E. histolytica trophozoites show heterogeneity in nuclear number during intestinal tissue invasion.Intestinal tissue sections were stained with polyclonal anti-Eh lectin antibody to identify amoeba cells followed by hematoxylin staining of the nuclei. (A) Two representative images are shown where amoeba cells (indicated by arrowheads) contain different number of nuclei (indicated by arrows). Scale bar is 10 µm. (The image of each amoeba cell was verified at high magnification to be of a single intact cell and the size of host cell nuclei was found to be double that of the amoeba nuclei- data not shown). (B) Intestinal tissue sections (n = 3) were counted for the presence of uni- (1), bi- (2) and multi- (>2) nucleated amoeba cells.

Mentions: We next examined if E. histolytica cells showed similar heterogeneity during infection of the human host and tissue invasion. We stained human intestinal tissue sections from a case of amoebic colitis (Fig. 5A) and visually scored 296 amoebae for multi-nucleation (Fig. 5B). Our data showed that only 75% of the amoebae were uni-nucleated in the intestinal sections. The increased number of multi-nucleated amoebae in intestinal tissue sections is similar to amoebae growing under axenic conditions as shown above. Although the possibility of ingestion of host cell nuclei by some of the amoebae that appear to be multi-nucleated cannot be ruled out, it should be noted that the average size of host cell nuclei was at least two-fold larger (data not shown) than the amoeba nuclei and therefore did not affect our analysis of nuclear number estimation in tissue amoebae. However, estimation of intestinal amoeba nuclear size showed similarity with the size of nuclei in xenic cultures (data not shown). Taken together the data show that heterogeneity of nuclear DNA content and nuclear number appears to be an inherent property of Entamoeba irrespective of in vitro growth conditions and also reflects an in vivo phenomenon.


Entamoeba shows reversible variation in ploidy under different growth conditions and between life cycle phases.

Mukherjee C, Clark CG, Lohia A - PLoS Negl Trop Dis (2008)

E. histolytica trophozoites show heterogeneity in nuclear number during intestinal tissue invasion.Intestinal tissue sections were stained with polyclonal anti-Eh lectin antibody to identify amoeba cells followed by hematoxylin staining of the nuclei. (A) Two representative images are shown where amoeba cells (indicated by arrowheads) contain different number of nuclei (indicated by arrows). Scale bar is 10 µm. (The image of each amoeba cell was verified at high magnification to be of a single intact cell and the size of host cell nuclei was found to be double that of the amoeba nuclei- data not shown). (B) Intestinal tissue sections (n = 3) were counted for the presence of uni- (1), bi- (2) and multi- (>2) nucleated amoeba cells.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2500184&req=5

pntd-0000281-g005: E. histolytica trophozoites show heterogeneity in nuclear number during intestinal tissue invasion.Intestinal tissue sections were stained with polyclonal anti-Eh lectin antibody to identify amoeba cells followed by hematoxylin staining of the nuclei. (A) Two representative images are shown where amoeba cells (indicated by arrowheads) contain different number of nuclei (indicated by arrows). Scale bar is 10 µm. (The image of each amoeba cell was verified at high magnification to be of a single intact cell and the size of host cell nuclei was found to be double that of the amoeba nuclei- data not shown). (B) Intestinal tissue sections (n = 3) were counted for the presence of uni- (1), bi- (2) and multi- (>2) nucleated amoeba cells.
Mentions: We next examined if E. histolytica cells showed similar heterogeneity during infection of the human host and tissue invasion. We stained human intestinal tissue sections from a case of amoebic colitis (Fig. 5A) and visually scored 296 amoebae for multi-nucleation (Fig. 5B). Our data showed that only 75% of the amoebae were uni-nucleated in the intestinal sections. The increased number of multi-nucleated amoebae in intestinal tissue sections is similar to amoebae growing under axenic conditions as shown above. Although the possibility of ingestion of host cell nuclei by some of the amoebae that appear to be multi-nucleated cannot be ruled out, it should be noted that the average size of host cell nuclei was at least two-fold larger (data not shown) than the amoeba nuclei and therefore did not affect our analysis of nuclear number estimation in tissue amoebae. However, estimation of intestinal amoeba nuclear size showed similarity with the size of nuclei in xenic cultures (data not shown). Taken together the data show that heterogeneity of nuclear DNA content and nuclear number appears to be an inherent property of Entamoeba irrespective of in vitro growth conditions and also reflects an in vivo phenomenon.

Bottom Line: Changes in DNA content during encystation-excystation were studied in the related reptilian parasite E. invadens.Based on the observed large changes in nuclear size and DNA content, and the minor differences in relative abundance of representative protein coding sequences, rDNA and tRNA sequences, it appears that gain or loss of whole genome copies may be occurring during changes in the growth conditions.Our studies demonstrate the inherent plasticity and dynamic nature of the Entamoeba genome in at least two species.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, Bose Institute, Kolkata, India.

ABSTRACT
Under axenic growth conditions, trophozoites of Entamoeba histolytica contain heterogenous amounts of DNA due to the presence of both multiple nuclei and different amounts of DNA in individual nuclei. In order to establish if the DNA content and the observed heterogeneity is maintained during different growth conditions, we have compared E. histolytica cells growing in xenic and axenic cultures. Our results show that the nuclear DNA content of E. histolytica trophozoites growing in axenic cultures is at least 10 fold higher than in xenic cultures. Re-association of axenic cultures with their bacterial flora led to a reduction of DNA content to the original xenic values. Thus switching between xenic and axenic growth conditions was accompanied by significant changes in the nuclear DNA content of this parasite. Changes in DNA content during encystation-excystation were studied in the related reptilian parasite E. invadens. During excystation of E. invadens cysts, it was observed that the nuclear DNA content increased approximately 40 fold following emergence of trophozoites in axenic cultures. Based on the observed large changes in nuclear size and DNA content, and the minor differences in relative abundance of representative protein coding sequences, rDNA and tRNA sequences, it appears that gain or loss of whole genome copies may be occurring during changes in the growth conditions. Our studies demonstrate the inherent plasticity and dynamic nature of the Entamoeba genome in at least two species.

Show MeSH
Related in: MedlinePlus