BackgroundDetailed descriptions of the early development of parasitic nematodes are seldom available. The embryonic development of the plant-parasitic nematode Meloidogyne incognita was studied, focusing on the early events.ResultsA fixed pattern of repeated cell cleavages was observed, resulting in the appearance of the six founder cells 3 days after the first cell division. Gastrulation, characterized by the translocation of cells from the ventral side to the center of the embryo, was seen 1 day later. Approximately 10 days after the first cell division a rapidly elongating two-fold stage was reached. The fully developed second stage juvenile hatched approximately 21 days after the first cell division.ConclusionsWhen compared to the development of the free-living nematode Caenorhabditis elegans, the development of M. incognita occurs approximately 35 times more slowly. Furthermore, M. incognita differs from C. elegans in the order of cell divisions, and the early cleavage patterns of the germ line cells. However, cytoplasmic ruffling and nuclear migration prior to the first cell division as well as the localization of microtubules are similar between C. elegans and M. incognita.Electronic supplementary materialThe online version of this article (doi:10.1186/s12861-016-0109-x) contains supplementary material, which is available to authorized users.
SummaryDuring preimplantation development, the embryo must establish totipotency and enact the earliest differentiation choices, processes that involve extensive chromatin modification. To identify novel developmental regulators, we screened for genes that are preferentially transcribed in the pluripotent inner cell mass (ICM) of the mouse blastocyst. Genes that encode chromatin remodeling factors were prominently represented in the ICM, including Chd1l, a member of the Snf2 gene family. Chd1l is developmentally regulated and expressed in embryonic stem (ES) cells, but its role in development has not been investigated. Here we show that inhibiting Chd1l protein production by microinjection of antisense morpholinos causes arrest prior to the blastocyst stage. Despite this important function in vivo, Chd1l is non-essential for cultured ES cell survival, pluripotency, or differentiation, suggesting that Chd1l is vital for events in embryos that are distinct from events in ES cells. Our data reveal a novel role for the chromatin remodeling factor Chd1l in the earliest cell divisions of mammalian development.
Objective: To define criteria for determining when preimplantation genetic testing for aneuploidy (PGT-A) results are suggestive of a potential balanced chromosomal rearrangement in the egg or sperm source and warrant karyotyping. Design: Performance evaluation of criteria developed to assess PGT-A results for patterns of imbalances suggestive of a balanced chromosomal rearrangement in the egg or sperm source. Setting: A single PGT-A laboratory and multiple in vitro fertilization centers. Patients: Reproductive couples who underwent routine PGT-A testing. Interventions: Karyotyping of reproductive couples for whom patterns of imbalances observed in PGT-A results suggested a balanced chromosomal rearrangement in the egg or sperm source. Main Outcome Measures: Correct or incorrect flagging of predicted translocation in either the egg or sperm source based on chromosome analysis. Results: Proposed criteria correctly predicted a balanced reciprocal translocation in 97% of cases (n ¼ 33), a (13;14) Robertsonian translocation in all cases (n ¼ 3), and an inversion in all cases (n ¼ 2). Other criteria evaluated were determined to be ineffective because of relatively low occurrences that met the criteria and/or low predictive value. Conclusions: Our results showed that the proposed criteria were effective for evaluating patterns of imbalances observed in PGT-A results suggestive of a potential chromosomal rearrangement in the egg or sperm source. Our proposed criteria can be employed by clinicians in the in vitro fertilization setting in combination with a patient's reproductive history to identify PGT-A patients who are likely carriers of balanced chromosomal rearrangements. (Fertil Steril Rep Ò 2021;2:72-9. Ó2020 by American Society for Reproductive Medicine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.