Cloning and functional analysis of a cDNA encoding Ginkgo biloba farnesyl diphosphate synthase

Farnesyl diphosphate synthase (FPS; EC2.5.1.1/EC2. 5.1.10) catalyzes the synthesis of farnesyl diphosphate, and provides precursor for biosynthesis of sesquiterpene and isoprenoids containing more than 15 isoprene units in Ginkgo biloba. Here we report the cloning, characterization and functional analysis of a new cDNA encoding FPS from G. biloba. The full-length cDNA (designated GbFPS) had 1731 bp with an open reading frame of 1170 bp encoding a polypeptide of 390 amino acids. The deduced GbFPS was similar to other known FPSs and contained all the conserved regions of trans-prenyl chain-elongating enzymes. Structural modeling showed that GbFPS had the typical structure of FPS, the most prominent feature of which is the arrangement of 13 core helices around a large central cavity. Southern blot analysis revealed a small FPS gene family in G. biloba. Expression analysis indicated that GbFPS expression was high in roots and leaves, and low in stems. Functional complementation of GbFPS in an FPS-deficient strain confirmed that GbFPS mediates farnesyl diphosphate biosynthesis.     

Mitochondrial DNA heteroplasmy in calves cloned by using adult somatic cell

Adult somatic cell cloned calves were produced by somatic cell nuclear transfer prepared by fusion of cultured ear fibroblast from a Holstein cow into enucleated oocytes of Luxi Yellow cow. In order to determinate the source of mitochondrial DNA of cloned calves, we designed the breed-specific PCR primers by aligning the known D-loop sequences of Bos taurus and analyzed the displacement loop sequences of five live cloned calves by breed-specific primers PCR. The results demonstrated that mtDNA originated from Holstein breed and that from Luxi breed co-exist in all five live calves.     

Patch establishment and development of a clonal plant,Polygonum cuspidatum,on Mount Fuji

Microsatellite analysis was used to investigate the patch establishment and development of Polygonum cuspidatum Sieb. et Zucc, a clonal herbaceous plant that dominates the primary succession on the southeast slope of Mount Fuji. Genotypes of P. cuspidatum in 155 patches at the study site differed from each other. This indicates that P. cuspidatum patches are initially established by seed dispersed on the bare scoria field, and not by clonal rhizome extension. Genetic differentiation was estimated using the FST values between subpopulations at the study site. There was almost no genetic differentiation between subpopulations, indicating the presence of massive gene flow. The pollen fathers of seeds and maternal genets of current-year seedlings were inferred from the microsatellite allele composition by a simple exclusion method. The wide, random distribution of pollen fathers suggests that pollen dispersal occurs over a broad area. Maternal analysis showed a tendency for seed dispersal to be biased to the area nearby and down slope from the mother plants. Patch establishment under massive gene flow may result from such pollen and seed dispersal. To understand the process of patch development, aerial photographs taken from 1962 to 1999 were compared, and then genets in each of 36 patches were identified from the microsatellite genotypes of P. cuspidatum shoots. The comparison of aerial photographs showed that most of the patches enlarged each year and that some neighbouring patches combined during growth. Genet analysis demonstrated a high correlation between patch area and the area of the largest genet within it, and that new genets were recruited at the patch periphery. These findings indicate that both vegetative and sexual reproduction, i.e. rhizome extension and the establishment of new seedlings, contribute to the development of P. cuspidatum patches.     

Genetic structure and reproduction dynamics of Salix reinii during primary succession on Mount Fuji,as revealed by nuclear and chloroplast microsatellite analysis

The early stage of volcanic desert succession is underway on the southeastern slope of Mount Fuji. We used markers of nuclear microsatellites (simple sequence repeats; SSR) and chloroplast microsatellites (cpSSR) to investigate the population genetic structure and reproduction dynamics of Salix reinii, one of the dominant pioneer shrubs in this area. The number of S. reinii genets in a patch and the area of the largest genet within the patch increased with patch area, suggesting that both clonal growth and seedling recruitment are involved in the reproduction dynamics of S. reinii. Five polymorphic cpSSR markers were developed for S. reinii by sequencing the noncoding regions between universal sequences in the chloroplast genome. Nineteen different cpSSR haplotypes were identified, indicating that S. reinii pioneer genets were created by the long-distance dispersal of seeds originating from different mother genets around the study site, where all vegetation was destroyed during the last eruption. Furthermore, the clustered distributions of different haplotypes within each patch or plot suggested that newly colonized genets tended to be generated from seeds dispersed near the initially established mother genets. These results revealed that the establishment of the S. reinii population on the southeastern slope of Mount Fuji involved two sequential modes of seed dispersal: long-distance dispersal followed by short-distance dispersal.     

In vitro development and mitochondrial fate of macaca-rabbit cloned embryos

Interspecies cloning may be used as an effective method to conserve highly endangered species and to support the development of non-human primate animal models for studying therapeutic cloning and nuclear-cytoplasm interaction. The use of the monkey model for biomedical research can avoid legal, ethical, and experimental limitations encountered in a clinical situation. We describe in this study the in vitro development of macaca-rabbit embryos produced by fusing macaca fibroblasts with enucleated rabbit oocytes and examine the fate of mitochondrial DNA in these embryos. We show that macaca-rabbit cloned embryos can develop to the blastocyst stage when cultured in vitro in HECM(10) +10% FBS and that mitochondrial DNA derived from donor somatic cells was detectable in cloned embryos throughout preimplantation development. These results suggest that (1) macaca fibroblast nuclei can dedifferentiate in enucleated metaphase II rabbit oocytes; (2) HECM(10) +10% FBS can break through the development block and support the development of macaca-rabbit cloned embryos to blastocysts; and (3) donor-cell-derived mitochondrial DNA is not eliminated until blastocyst stage.     

Extending the family of UNCG-like tetraloop motifs: NMR structure of a CACG tetraloop from coxsackievirus B3

Stable RNA tetraloop motifs are found frequently in biologically active RNAs. These motifs carry out a wide variety of functions in RNA folding, in RNA-RNA and RNA-protein interactions. A great deal of knowledge about the structures and functions of tetraloop motifs has accumulated largely due to intensive theoretical, biochemical, and biophysical studies on three most frequently occurring families of tetraloop sequences, namely, the cUNCGg, the cGNRAg, and the gCUUGc sequences. Our knowledge surely is not exhaustive, and efforts are still being made to gain a better understanding. Here we report the NMR structure of a uCACGg tetraloop that occurs naturally within the cloverleaf RNA structure of the 5'-UTR of coxsackievirus B3. This tetraloop is the major determinant for interaction between the cloverleaf RNA and viral 3C protease, which is an essential part of a ribonucleoprotein complex that plays a critical role in the regulation of viral translation and replication. Our structure shows that the CACG tetraloop is closed by a wobble U.G base pair. The structure of the CACG tetraloop is stabilized by extensive base stacking and hydrogen bonding interactions strikingly similar to those previously reported for the cUUCGg tetraloop. Identification of these hallmark structural features strongly supports the existence of an extended YNCG tetraloop family. The U.G base pair closing the stem and the A residue in the loop introduce some small structural and themodynamic distinctions from the canonical cUUCGg tetraloop that may be important for recognition by the viral 3C protease.     

Cholinergic regulation of the corpora allata in adult male loreyi leafworm Mythimna loreyi

The direct effect of acetylcholine on the activation of the corpora allata (CA) was investigated in the adult male loreyi leafworm, Mythimna loreyi. Acetylcholine, in the presence of the choline esterase inhibitor physostigmine (50 microM), elicited a stimulatory effect on juvenile hormone acids (JHAs) release from the CA. Maximum effect was obtained at concentrations of 10 and 50 microM. Repeated administration of 10 microM acetylcholine on the same CA did not elicit similar stimulatory effect. Since JHA release can be significantly activated by carbachol and not by nicotine, this cholinergic effect is likely to belong to the muscarinic type. The effect of acetylcholine was significantly antagonized by gallamine triethiodide (M(2) antagonist) and 4-DAMP (M(3) antagonist), pirenzepine (M(1) antagonist), and tropicamide (M(4) antagonist) were ineffective. It is concluded that in the adult male M. loreyi, the cholinergic regulation of CA is most likely via M(2) and M(3) muscarinic receptors.     

Subcellular targeting and agonist-induced site-specific phosphorylation of endothelial nitric-oxide synthase

The endothelial isoform of nitric-oxide synthase (eNOS) undergoes a complex pattern of covalent modifications, including acylation with the fatty acids myristate and palmitate as well as phosphorylation on multiple sites. eNOS acylation is a key determinant for the reversible subcellular targeting of the enzyme to plasmalemmal caveolae. We transfected a series of hemagglutinin epitope-tagged eNOS mutant cDNAs deficient in palmitoylation (palm(-)) and/or myristoylation (myr(-)) into bovine aortic endothelial cells; after treatment with the eNOS agonists sphingosine 1-phosphate or vascular endothelial growth factor, the recombinant eNOS was immunoprecipitated using an antibody directed against the epitope tag, and patterns of eNOS phosphorylation were analyzed in immunoblots probed with phosphorylation state-specific eNOS antibodies. The wild-type eNOS underwent agonist-induced phosphorylation at serine 1179 (a putative site for phosphorylation by kinase Akt), but phosphorylation of the myr(-) eNOS at this residue was nearly abrogated; the palm(-) eNOS exhibited an intermediate phenotype. The addition of the CD8 transmembrane domain to the amino terminus of eNOS acylation-deficient mutants rescued the wild-type phenotype of robust agonist-induced serine 1179 phosphorylation. Thus, membrane targeting, but not necessarily acylation, is the critical determinant for agonist-promoted eNOS phosphorylation at serine 1179. In striking contrast to serine 1179, phosphorylation of eNOS at serine 116 was enhanced in the myr(-) eNOS mutant and was markedly attenuated in the CD8-eNOS membrane-targeted fusion protein. We conclude that eNOS targeting differentially affects eNOS phosphorylation at distinct sites in the protein and suggest that the inter-relationships of eNOS acylation and phosphorylation may modulate eNOS localization and activity and thereby influence NO signaling pathways in the vessel wall.