Molecular cloning and characterization of the germline-restricted chromosome sequence in the zebra finch

The zebra finch (Taeniopygia guttata) germline-restricted chromosome (GRC) is the largest chromosome and has a unique system of transmission in germ cells. In the male, the GRC exists as a single heterochromatic chromosome in the germline and is eliminated from nuclei in late spermatogenesis. In the female, the GRC is bivalent and euchromatic and experiences recombination. These characteristics suggest a female-specific or female-beneficial function of the GRC. To shed light on the function of GRC, we cloned a portion of the GRC using random amplified polymorphic DNA–polymerase chain reaction and analyzed it using molecular genetic and cytogenetic methods. The GRC clone hybridized strongly to testis but not blood DNA in genomic Southern blots. In fluorescent in situ hybridization analysis on meiotic chromosomes from synaptonemal complex spreads, the probe showed hybridization across a large area of the GRC, suggesting that it contains repetitive sequences. We isolated a sequence homologous to the GRC from zebra finch chromosome 3 and a region of chicken chromosome 1 that is homologous to zebra finch chromosome 3; the phylogenetic analysis of these three sequences suggested that the GRC sequence and the zebra finch chromosome 3 sequence are most closely related. Thus, the GRC sequences likely originated from autosomal DNA and have evolved after the galliform–passeriform split. The present study provides a foundation for further study of the intriguing GRC

Animal serum-free culture conditions for isolation and expansion of multipotent mesenchymal stromal cells from human BM

Background Multipotent mesenchymal stromal cells ( MSC) have become important tools in regenerative and transplantation medicine. Rapidly increasing numbers of patients are receiving in vitro-expanded MSC. Culture conditions typically include FSC because human serum does not fully support growth of human MSC in vitro (MSCFCS). Concerns regarding BSE, other infectious complications and host immune reactions have fueled investigation of alternative culture supplements. Methods As PDGF has long been identified as a growth factor for MSC, we tested media supplementation with platelet lysate for support of MSC proliferation. Results We found that primary cultures of BM-derived MSC can be established with animal serum-free media containing fresh frozen plasma and platelets (MSCFFPP). Moreover, MSCFFPP showed vigorous proliferation that was superior to classical culture conditions containing FCS. MSCFFPP morphology was equivalent to MSC FCS, and MSCFFPP expressed CD73, CD90, CD105, CD106, CD146 and HLA-ABC while being negative for CD34, CD45 and surface HLA-DR, as expected. In addition to being phenotypically identical, MSCFFPP could efficiently differentiate into adipocytes and osteoblasts. In terms of immune regulatory properties, MSCFFPP were indistinguishable from MSC FCS. Proliferation of PBMC induced by IL-2 in combination with OKT-3 or by PHA was inhibited in the presence of MSCFFPP. Discussion Taken together, FCS can be replaced safely by FFPP in cultures of MSC for clinical purposes

External high-Quality-factor Resonator tunes up nuclear magnetic resonance

The development of powerful sensors for the detection of weak electromagnetic fields is crucial for many spectroscopic applications, in particular for nuclear magnetic resonance (NMR). Here, we present a comprehensive theoretical model for boosting the NMR signal-to-noise ratio, validated by liquid-state 1H, 129Xe and 6Li NMR experiments at low frequencies, using an external resonator with a high quality-factor combined with a low-quality-factor input coil. In addition to an enhanced signal-to-noise ratio, this approach exhibits striking features such as a high degree of flexibility with respect to input coil parameters and a square-root dependence on the sample volume, and signifies an important step towards compact NMR spectroscopy at low frequencies with small and large coils