Disease relevance of Zygote

• Microinjection of the DG42 antiserum or the Bradyrhizobium NodZ enzyme in fertilized eggs of zebrafish led to severe defects in trunk and tail development [1].
• The in vitro fertilization and embryo transfer (IVF/ET) procedure provides extra material--oocytes, zygotes, and embryos--to investigate the contribution of chromosomal abnormality to implantation failure [2].
• Spontaneous abortion risk was increased among women reporting previous spontaneous abortions and ART attempts, and among women who used clomiphene or zygote intrafallopian transfer [3].
• MAIN OUTCOME MEASURE(S): Number of gonadotropin ampules; estradiol level on the day of ovulation induction; follicles, oocytes, and cryopreserved zygotes; fertilization, implantation, and pregnancy rates; and number of ovarian hyperstimulation syndromes (OHSS) [4].
• Effect of glucose starvation on the expression of transferred tsx genes in Escherichia coli K12 zygotes [5].

High impact information on Zygote

• In loss-of-function mutants, the zygote does not elongate properly, and the cells of the basal lineage are eventually incorporated into the embryo instead of differentiating the extra-embryonic suspensor [6].
• In C. elegans, the PAR-1 kinase is localized to the posterior of the zygote and is required for anterior-posterior axis formation [7].
• Unexpectedly, removal of the Sxl gene in the zygote mitigates both the migration and mitotic defects of nos- germ cells [8].
• PAR-1 protein is localized to the posterior periphery of the zygote and is distributed in a polar fashion preceding the asymmetric divisions of the germline lineage [9].
• We now have introduced the wild-type MBP gene into the germ line of shiverer mice by microinjection into fertilized eggs [10].

Chemical compound and disease context of Zygote

• Zinc amelioration of cadmium toxicity on preimplantation mouse zygotes in vitro [11].
• In this study, fertilized eggs of sea urchin have been observed morphologically during exposure to heavy metal salts or carbon tetrachloride, with the purpose of testing possible differences in toxicity of various classes of poisons [12].
• Citotoxicity (inhibition of cell division in fertilized eggs of Loxechinus albus) and general toxicity (using embryos of Artemia salina) of plants belonging to the genera Senecio, Deschampsia, Alstroemeria, Anarthrophyllum, Chloraea and Geranium were investigated [13].

Biological context of Zygote

• Only X linkage of the H-Y gene creates a compelling evolutionary need to change the female sex chromosome constitution from XX to XO, and to abandon the dosage compensation by an X inactivation mechanism, so that the nonproductive XH-YX zygote can be eliminated as an embryonic lethal [14].
• In the absence of Taz1, telomere clustering at the spindle pole bodies is disrupted, meiotic recombination is reduced, and both spore viability and the ability of zygotes to re-enter mitosis are impaired to a level that would be expected if chromosome segregation were occurring randomly [15].
• From these results, we conclude that centrosome reproduction in sea urchin zygotes is not controlled by the accumulation of cyclin proteins or the synthesis of centrosome-specific proteins at each cell cycle [16].
• We have used two different experimental approaches to demonstrate topological separation of parental genomes in preimplantation mouse embryos: mouse eggs fertilized with 5-bromodeoxyuridine (BrdU)-labeled sperm followed by detection of BrdU in early diploid embryos, and differential heterochromatin staining in mouse interspecific hybrid embryos [17].
• Fus2 may interact with structures involved in the alignment of the nuclei during cell fusion, because fus2 mutants have strong defects in karyogamy and fail to orient microtubules between parental nuclei in zygotes [18].

Anatomical context of Zygote

• In mutant zygotes with abnormal spindle orientations and in wild-type zygotes treated with the microtubule inhibitors nocodazole, colcemid, vinblastine, and griseofulvin, both P-granule segregation to the posterior pole and the concomitant pseudocleavage occur apparently normally, but the normally concurrent migration of the pronuclei is inhibited [19].
• In zygotes formed by mating two ugo1 cells, mitochondria do not fuse and mix their matrix contents [20].
• Centrosomes repeatedly reproduce in sea urchin zygotes arrested in S phase, whether cyclin-dependent kinase 1-cyclin B (Cdk1-B) activity remains at prefertilization levels or rises to mitotic values [21].
• In adult mice, Sebox RNA was found in maturing oocytes and in fertilized eggs; however, the abundance of Sebox RNA is decreased in the two-cell embryo, and little or none was detected in the four-cell embryo [22].
• RNA phenotyping shows transcripts for the GH receptor and GH-binding protein in mouse preimplantation embryos of all stages from fertilized eggs (day 1) to blastocysts (day 4) [23].

Associations of Zygote with chemical compounds

• Measurement of tract length of poly(A) in two cell zygotes by adenosine/AMP ratios of radioactive RNA shows that the poly(A) tract of the zygote is solely accounted for radioactive RNA, indicating extensive turnover of the poly(A) [24].
• The neurons were labeled by injecting rhodamine-labeled tubulin into the fertilized egg and explanting the neurons from the neural tube [25].
• In these experiments lidocaine inhibited both the initial rates and the extent of wall loss and zygote formation [26].
• Eggs fertilized in the presence of the transglutaminase inhibitors, putrescine and cadaverine, had disorganized and expanded FEs with inhibition of the characteristic I-T transition [27].
• High frequency of mosaic mutants produced by N-ethyl-N-nitrosourea exposure of mouse zygotes [28].

Gene context of Zygote

• This result suggests that a mechanism other than cytoplasmic flow or mlc-4/nmy-2 activity can generate some a-p asymmetries in the C. elegans zygote [29].
• When the GS17 gene is injected into fertilized eggs, transcription from the injected DNA mimics the expression pattern of the endogenous gene, i.e., both the switch-on and switch-off of transcription are correctly regulated [30].
• The ATML1 gene was first expressed in the apical cell after the first asymmetric division of the zygote and continued to be expressed in all proembryo cells until the eight-cell stage [31].
• Transcripts of the XIST gene were detected as early as the 1-cell zygote and, with increasing efficiency, through to the 8-cell stage of preimplantation development [32].
• Although these LEC2-induced RNAs accumulate primarily during the maturation phase, we show that a subset, including AGL15 and IAA30, accumulate in seeds containing zygotes [33].

Analytical, diagnostic and therapeutic context of Zygote

• Immunofluorescence staining with an antibody against 5-methylcytosine shows that the cellular machinery of the fertilized egg cannot demethylate the second maternal genome in parthenogenetic, gynogenetic and triploid digynic embryos or remethylate the additional (already demethylated) paternal genome in androgenetic and triploid diandric embryos [34].
• RT-PCR analysis showed that epithin mRNAs were detectable during the cleavage stages from a 1-cell zygote to the blastocyst [35].
• To determine the source of carbon for sugar phosphates and pyruvate, 14C-labeled intermediary metabolites were injected into fertilized eggs and their metabolism examined by thin-layer chromatography [36].
• Unfertilized and fertilized eggs of the sea urchins Strongylocentrotus purpuratus and Lytechinus pictus, injected with the fluorescent probe calcium green dextran (Molecular Probes, Inc.) and monitored with single cell fluorimetry, rarely responded to 10 mM caffeine, but with 20 mM caffeine they produced a transient rise in intracellular calcium [37].
• To investigate causes for these changes in cell-cycle control, we observed division synchrony in animal-cap blastomeres dissociated from embryos whose nucleocytoplasmic ratio (N/C) had been altered by constriction of zygotes or by delaying nucleation into zygote halves and compared their mitotic indices in the presence and absence of nocodazole [38].

References