Genomic regulation in imature females of Schistosoma mansoni

Rumjanek, Franklin David; Braga, Vania; Silveira, Alda Maria Soares; Rabelo, Élida Mara Leite; Campos, Élida G.; Rodriguez, Vanderlei

doi:10.1590/s0074-02761987000800036

Cited by 3 publications

(1 citation statement)

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“…We hypothesize that in addition to directly supplying nutrients, male parasites provide a growth factor signal that allows female parasites to access key nutrients, and that this process is of value only if the nutrients are present in the environment. Supportive of the idea that female parasites are receiving signals and/or nutrients from male parasites in vitro is our finding that males can induce p14 expression in females in culture, a result that is compatible with previous reports that extracts of males worms are able to promote the development of vitelline cells [42] and the expression of p14 in female parasites [43] . Of note however, in our hands p14 expression is not sustained, nor indicative of wholesale vitelline cell survival in this setting, indicating that other key requirements are missing.…”

Section: Discussionsupporting

confidence: 91%

Cell Death and Reproductive Regression in Female Schistosoma mansoni

2012

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The vitellarium is a highly proliferative organ, producing cells which are incorporated along with a fertilized ovum into the schistosome egg. Vitellarial growth fails to occur in virgin female schistosomes in single sex (female-only) infections, and involution of this tissue, which is accompanied by physical shrinkage of the entire worm, occurs when mature females sexually regress upon removal from their male partners. We have found that upon removal from their hosts into tissue culture, female parasites regress whether they are mated or not, but that cessation of egg production and a decline in expression of the vitelline gene p14 is delayed by mating. We used BrdU labeling to investigate whether there was a loss of proliferation in the vittelarium that might account for regression and found that the proliferation rate declined equally in paired and singled females once placed into culture. However, TUNEL staining and Caspase 3 activity measurements indicate that the loss of vitrellarial cellularity associated with regression is associated with profound apoptotic vitelline cell death, which is not apparent in the vitellaria of paired females immediately ex vivo, and which develops in vitro regardless of whether males are present or not. Furthermore, primordial vitellaria in virgin females have a high frequency of apoptotic cells but are characterized by a proliferation rate that is indistinguishable from that in fully developed vitellaria in mature paired females. Taken together, our data suggest that the vitelline proliferation rate is independent of pairing status. In contrast, the survival of vitelline cells, and therefore the development of the vitellarium, is highly male-dependent. Both processes are negatively affected by removal from the host regardless of whether male worms are present or not, and are unsustainable using standard tissue culture approaches.

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Section: Discussionsupporting

confidence: 91%