Pluripotent embryonic stem cells (ESCs) were first isolated nearly three decades ago from mice, yet efficient ESC isolation has been limited to rodents and primates to date. We report a novel and ...robust technique for isolating ESCs from mammalian pre-implantation embryos by altering the epigenotype of embryonic explants and using pressed zona pellucida-free blastocysts. We first examined this technique for murine ESC derivation. Compared with controls, murine ESCs were efficiently derived when explants were exposed to 1μM 5-azacytidine, an epigenetic modifier that causes DNA demethylation (56.1% vs 31.6%; P < 0.01). Mouse ESCs stained positively for alkaline phosphatase, expressed markers of pluripotency including Oct4, Rex1 and SSEA1 and formed teratomas when injected into Severe Combined Immuno-Deficient (SCID) mice. The approach was subsequently used for bovine ESC derivation. In bovine a higher concentration of 5-azacytidine (5 μM) was required to elicit a response. This technique resulted in up to 18 times more efficient isolation of pluripotent cells than traditional methods (71.4% vs 4.0%; P < 0.001). These putative bovine ESCs expressed OCT4, REX1 mRNA and SSEA-1 and SSEA-4 proteins; and were able to form embryoid bodies in vitro and teratomas when injected in Severe Combined Immuno Deficient (SCID) mice. This is the first report on derivation of ESCs with both in vitro and in vivo differentiation potential in a livestock species.
Here we report the first use of intra-cytoplasmic sperm injection (ICSI) in a marsupial, the tammar wallaby (Macropus eugenii), to achieve in vitro fertilization and cleavage. A single epididymal ...spermatozoon was injected into the cytoplasm of each mature oocyte collected from Graafian follicles or from the oviduct within hours of ovulation. The day after sperm injection, oocytes were assessed for the presence of pronuclei and polar body extrusion and in vitro development was monitored for up to 4 days. After ICSI, three of four (75%) follicular and four of eight (50%) tubal oocytes underwent cleavage. The cleavage pattern was similar to that previously reported for in vivo fertilized oocytes placed in culture, where development also halted at the 4- to 8-cell stage. One-third of injected oocytes completed the second cleavage division, but only a single embryo reached the 8-cell stage. The success of ICSI in the tammar wallaby provided an opportunity to examine the influence of the mucoid coat that is deposited around oocytes passing through the oviduct after fertilization. The presence of a mucoid coat in tubal oocytes did not prevent fertilization by ICSI and the oocytes cleaved in vitro to a similar stage as follicular oocytes lacking a mucoid coat. Cell-zona and cell-cell adhesion occurred in embryos from follicular oocytes, suggesting that the mucoid coat is not essential for these processes. However, blastomeres were more closely apposed in embryos from tubal oocytes and cell-cell adhesion was more pronounced, indicating that the mucoid coat may be involved in maintaining the integrity of the conceptus during cleavage.
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•Methyl anthranilate (MA), an ortho sunscreen, is a non-ideal chemical filter.•Two structural isomers, para- and meta-MA, have very different photochemistry.•para-MA shows a ...long-lived excited state, also not an ideal sunscreen.•meta-MA decays much more rapidly, has non-unity luminescence.•Theory suggests prefulvenic conical intersections drive faster dynamics.•These conical intersections present new avenues for novel sunscreen design.
Towards the development of a bottom-up rationale for sunscreen design, the effects of substituent position on the ultrafast photodynamics of the sunscreen precursor methyl anthranilate (MA, an ortho compound) were evaluated by studying para- and meta-MA in vacuum. Time-resolved ion yield (TR-IY) measurements reveal a long-lived S1 excited state (≫1.2 ns) for para-MA, proposed to be the result of a weakly fluorescent, bound excited state. In the case of meta-MA, TR-IY transients reveal a much faster (∼2 ns) excited state relaxation, possibly due to multiple low-lying S1/S0 conical intersections of prefulvenic character. While meta-MA may not be an ideal sunscreen ingredient due to a low ultraviolet absorbance, its comparatively efficient relaxation mechanism may constitute an alternative to common sunscreen relaxation pathways. Thus, our results should prompt further studies of prefulvenic relaxation pathways in potential sunscreen agents.
To determine the success of intracytoplasmic sperm injection for severe male infertility.
A retrospective survey.
A tertiary infertility service.
One hundred fourteen couples had 119 intracytoplasmic ...sperm injection treatments because of previous failure of standard IVF, poor results with subzonal insemination, sperm concentration < 2 × 106/mL, other sperm defects, or male genital tract obstruction.
Fertilization, implantation, and pregnancy rates.
Of 1,185 oocytes treated by intracytoplasmic sperm injection, normal fertilization and cleavage occurred in 717 of 1,073 that survived (67% normal fertilization rate). Abnormal fertilization occurred in 113 oocytes (11% abnormal fertilization rate) and 112 oocytes did not survive the procedure (survival rate of 90%). In 117 couples, 251 embryos were transferred fresh, 409 embryos were cryopreserved, and 224 were transferred after thawing. The implantation rate was 7.4% (fetal heart per embryo transferred). To date 36 clinical pregnancies have been achieved (12% per fresh transfer, 20% per frozen transfer, and 30% overall), 24 are ongoing or delivered (6% per fresh transfer, 14% per frozen transfer, and 20% per intracytoplasmic sperm injection). The fertilization rates were the same (65%) with various sperm defects but higher with genital tract obstructions (75%).
Intracytoplasmic sperm injection has improved the prognosis of severe male infertility.
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