In vitro culture and differentiation of osteoblasts from human umbilical cord blood

It is well accepted that human umbilical cord blood (UCB) is a source of mesenchymal stem cells (MSCs) which are able to differentiate into different cell phenotypes such as osteoblasts, chondrocytes, adipocytes, myocytes, cardiomyocytes and neurons. The aim of this study was to isolate MSCs from human UCB to determine their osteogenic potential by using different kinds of osteogenic medium. Eventually, only those MSCs cultured in osteogenic media enriched with vitamin D₂ and FGF9, were positive for osteocalcin by RT-PCR. All these cells were positive for alizarin red, alkaline phosphatase and Von Kossa. The results obtained from RT-PCR have confirmed that osteogenesis is complete by expression of the osteocalcin marker. In conclusion, vitamin D₂, at least in vitro, may replace vitamin D₃ as an osteogenic stimulator factor for MSC differentiation.     

DNA architecture: from G to Z

G-quadruplexes and Z-DNA are two important non-B forms of DNA architecture. Results on novel structural elements, folding and unfolding kinetics, and interactions with small molecules and proteins have been reported recently for these forms. These results will enhance our understanding of the biology of these structures and provide a platform for drug design.     

Some New Records of Ferns from Vietnam and Laos (3)Pteris (Pteridaceae)

Genus Pteris from Vietnam and Laos is revised in this paper. Seven species newly reported from Vietnam and Laos are P.argyraea, P.sichuanensis, P.maclurei, P.pseudopellucida, P.setuloso costulata, P.morii, and P.wangiana.     

Before it had a name: Diagnostic characteristics,geographic distribution,and the conservation of <Emphasis Type="Italic">Cupressus tonkinensis</Emphasis> (Cupressaceae)

In northern Việt Nam the felling of Cupressus for wood and incense has resulted in the decimation of wild cypress populations. Ever since specimens of Cupressus from Việt Nam were first sent to Paris in 1905, they have been inappropriately referred to a variety of names including Cupressus funebris, Cu. torulosa, and synonyms of Callitropsis lusitanica. This taxonomic disarray was somewhat ameliorated in 1994 when a new species—Cu. tonkinensis—was proposed. Unfortunately, the morphological differences between Cu. tonkinensis and similar species were not clearly articulated. As a result, Cu. tonkinensis has generally been ignored or treated as a synonym of Cu. torulosa. These two species can be distinguished by the presence of dimorphic leaves in Cu. tonkinensis and their absence in Cu. torulosa as well as several continuous morphological characteristics including the frequency of resin glands (greater in Cu. tonkinensis) on ultimate segments, and the size of the ovulate cone (smaller in Cu. tonkinensis). The natural habitat occupied by Cu. tonkinensis in a principal coordinates plot of nine monthly climate variables and 40 soil variables is remote from other species. Cupressus tonkinensis habitat is statistically distinct from Cu. chengiana, Cu. gigantea, and Cu. torulosa, but statistically indistinguishable from the habitats of Cu. funebris.     

Lysimachia vietnamensis and L. verbascifolia spp. nov. (Primulaceae) from Vietnam

Two new species of Lysimachia (Primulaceae), L. vietnamensis L. K. Phan & C. M. Hu and L. verbascifolia C. M. Hu & K. L. Phan from Vietnam are described and illustrated.     

Stacking of G-quadruplexes: NMR structure of a G-rich oligonucleotide with potential anti-HIV and anticancer activity

G-rich oligonucleotides T30695 (or T30923), with the sequence of (GGGT)(4), and T40214, with the sequence of (GGGC)(4), have been reported to exhibit anti-HIV and anticancer activity. Here we report on the structure of a dimeric G-quadruplex adopted by a derivative of these sequences in K(+) solution. It comprises two identical propeller-type parallel-stranded G-quadruplex subunits each containing three G-tetrad layers that are stacked via the 5'-5' interface. We demonstrated control over the stacking of the two monomeric subunits by sequence modifications. Our analysis of possible structures at the stacking interface provides a general principle for stacking of G-quadruplexes, which could have implications for the assembly and recognition of higher-order G-quadruplex structures.