BACKGROUND The effects of exposure time (20 versus 45 s) to a high concentration of cryoprotectant (7.0 mol/l ethylene glycol with 0.5 mol/l sucrose) and freezing rates (1200-10 300 degrees C/min) during rapid freezing of mouse pronuclear stage embryos on survival and development to blastocysts were investigated. Different freezing rates were achieved by directly plunging the straws (rapid free...

Four new complexes of the type [LCo ((DO)(DOH) pn) Cl] PF , where (DO) (DOH) pn = N , N '- propanediylbis (2, 3-butanedione2-imine3-oxirne)a nd L =morpholine (mrpln) (I), benzylamine (bzlan) (II), piperidine (pprdn)(III) and pyrrolidine (prldn) (IV) have been synthesized and characterized by elemental analyses and spectroscopic methods. Approximate values of the angular-overlap parameter, ?, ...

The predicted existence of cytoplasmic Ca2+ gradients during the photopolarization of the zygotes of the brown algae, Pelvetia and Fucus, has proved to be difficult to establish, and the downstream targets of the putative gradients are not known. We have used quantitative microinjection of the long excitation wavelength Ca2+ indicator, Calcium Crimson, and of antibodies against calmodulin to in...

Zygotes of the brown alga Fucus distichus L. Powell accumulate a sulfated polysaccharide (fucoidin) in the cell wall at the site of rhizoid formation. Previous work indicated that zygotes grown in seawater minus sulfate do not sulfate the preformed fucan (an unsulfated fucoidin) but form rhizoids. Under these conditions, we determined whether sulfation of the fucan is required for its localizat...

Brief exposure to some pesticides, applied during a sensitive window for the neural regulation of ovulation, will block the preovulatory surge of LH and, thus, delay ovulation. Previously, we have shown that a single i.p. injection of 50 mg/kg of thiram, a dithiocarbamate fungicide that decreases norepinephrine synthesis, on proestrus (1300 h) suppresses the LH surge and delays ovulation for 24...

N the medaka (Oryzius Zutipes) , an oviparous cyprinodont fish, the normal I sex-chromosome constitution is XX for female and XY for male (AIDA 1921). A series o€ our previous experiments have convincingly demonstrated that a heterotypic (atypical) sex hormone administered prior to and passing through the stage of gonadal sex differcntiation induces a complete reversal in sex differentiation. I...

Animal genome engineering experimental procedures involve three major steps: isolation of zygotes from pregnant females; microinjection of zygotes, and; transfer of injected zygotes into recipient females, that have been practiced for over three decades. The laboratory set ups intending to performing these procedures require to have sophisticated equipment as well as highly skilled technical pe...

OBJECTIVE To assess ovarian response among carriers of FMR1 premutation who undergo preimplantation genetic diagnosis (PGD). DESIGN Retrospective study. SETTING Academic IVF unit. PATIENT(S) Of 18 carriers of FMR1 premutation referred to PGD, eight had <100 CGG repeats and ten had >or=100 CGG repeats. INTERVENTION(S) Controlled ovarian stimulation (COH) and PGD. MAIN OUTCOME MEASURE(S...

Although global erasure of DNA methylation has been observed in zygotes and primordial germ cells, the responsible enzyme(s) have been elusive. The demonstration that members of the Tet (ten eleven translocation) family of proteins are capable of catalyzing conversion of 5-methylcytosine (5mC) of DNA to 5-hydroxymethylcytosine (5hmC) raises the possibility that Tet proteins may participate in t...

BACKGROUND Chilling injury occurs when the cell membrane undergoes a transition from the liquid state to the gel state. Human oocytes and single-cell zygotes are of similar shape and size but the post-thawing survival rate of oocytes is poorer. We set out to investigate the possible difference in membrane lipid phase transition (LPT) temperature between the two cell types. METHODS The LPT tem...