No abstract

In an effort to improve the quality of in vitro produced porcine embryos, we investigated the effect of brain-derived neurotropic factor (BDNF), a neurotropin family member, on in vitro maturation (IVM) of porcine oocytes. The expression of BDNF and truncated isoforms of its receptor, tyrosine kinase B (TrkB), and p75 common neurotropin receptor was detected in both follicular cells and metaphase-I stage oocytes by RT-PCR. However, mRNA of full-length TrkB was not found in oocytes although it was detected in follicular cells. The expression pattern of BDNF and TrkB was confirmed by immunohistochemistry. Supplementation with BDNF (30 ng/ml) during IVM significantly (P!0.05) increased the first polar body extrusion and glutathione levels in oocytes, whereas the effect of BDNF on nuclear maturation was diminished when gonadotropin and epidermal growth factor (EGF) were added to the culture media. However, treatment with BDNF (30 ng/ml) along with EGF (10 ng/ml) in the presence of gonadotropin significantly (P!0.05) increased the developmental competence of oocytes to the blastocyst stage after both in vitro fertilization (IVF; 29.1% when compared with control, 15.6%) and somatic cell nuclear transfer (SCNT; 13.6% when compared with control, 3%). This appeared to reflect a stimulatory interaction between BDNF and EGF to enhance the cytoplasmic maturation of oocytes to support successful preimplantation development. In conclusion, BDNF enhanced nuclear and cytoplasmic maturation of oocytes by autocrine and/or paracrine signals. Also, when used together with EGF, BDNF increased the developmental potency of embryos after IVF and SCNT, demonstrating an improved in vitro production protocol for porcine oocytes.

No abstract

A transition metal-containing Zintl phase, Sr2MnSb2, was prepared from a stoichiometric combination reaction of the elements in Sn flux, and its structure was determined by single-crystal X-ray diffraction methods. The compound crystallizes in the orthorhombic space group Pnma with a = 15.936(3) A, b = 14.498(3) A, c = 8.2646(17) A, and Z = 12. The structure of Sr2MnSb2 is composed of corrugated layers of corner- and edge-shared MnSb4 tetrahedra. The basic building unit of the layer is a [Mn3Sb6]12- cluster composed of three edge-shared MnSb4 tetrahedra. These trinuclear clusters share four Sb vertexes to form a layer with cavities. Sr2+ cations are located at the inter- and intralayer space. Magnetic susceptibility measurements indicate an effective magnetic moment of 4.85 mu(B), a value smaller than what would be expected from Mn2+ ions.

No abstract

No abstract

No abstract

No abstract