Regeneration of transgenic Cryptomeria japonica D. Don after Agrobacterium tumefaciens-mediated transformation of embryogenic tissue

A genetic transformation procedure for Cryptomeria japonica was developed after co-cultivation of embryogenic tissues with the disarmed Agrobacterium tumefaciens strain C58/pMP90, which harbours the visual reporter gene sgfp and two selectable marker genes, hpt and nptII. We were able to generate eight and three independent transgenic lines per gram of embryogenic tissue after selection on hygromycin and kanamycin medium, respectively. Transgenic plants were regenerated through somatic embryogenesis in 4 lines out of these 11 lines. Green fluorescent protein fluorescence was observed under fluorescent microscopy. Integration of the genes into the genome was confirmed by polymerase chain reaction analysis of embryogenic tissues and Southern blot analysis of regenerated plantlets.     

Saccharomyces cerevisiae Bor1p is a boron exporter and a key determinant of boron tolerance

Boron is toxic to living organisms when present in excess. Saccharomyces cerevisiae Bor1p is a plasma membrane protein that decreases the intracellular concentration of boron and confers boron tolerance in yeasts. We investigated the detailed characteristics of boron transport by Bor1p and its roles in boron tolerance. Boron transport assays showed that the bor1 deletion mutant (bor1Delta) accumulates higher intracellular concentrations of boron and has a lower rate of boron export. The bor1Delta showed greater susceptibility to high concentrations of boron than the wild-type strain, and the growth rates of both strains were negatively correlated with the intracellular concentrations of boron. With normal to toxic levels of external boron, green fluorescent protein (GFP)-tagged Bor1p localized to the plasma membrane irrespective of the concentration of boron in the medium. Taken together, these results establish Bor1p as a plasma membrane boron exporter and a key determinant of boron tolerance.     

An Analytic Solution of the Cable Equation Predicts Frequency Preference of a Passive Shunt-End Cylindrical Cable in Response to Extracellular Oscillating Electric Fields

Under physiological and artificial conditions, the dendrites of neurons can be exposed to electric fields. Recent experimental studies suggested that the membrane resistivity of the distal apical dendrites of cortical and hippocampal pyramidal neurons may be significantly lower than that of the proximal dendrites and the soma. To understand the behavior of dendrites in time-varying extracellular electric fields, we analytically solved cable equations for finite cylindrical cables with and without a leak conductance attached to one end by employing the Green's function method. The solution for a cable with a leak at one end for direct-current step electric fields shows a reversal in polarization at the leaky end, as has been previously shown by employing the separation of variables method and Fourier series expansion. The solution for a cable with a leak at one end for alternating-current electric fields reveals that the leaky end shows frequency preference in the response amplitude. Our results predict that a passive dendrite with low resistivity at the distal end would show frequency preference in response to sinusoidal extracellular local field potentials. The Green's function obtained in our study can be used to calculate response for any extracellular electric field.     

Efficient expression of recombinant soluble human FcγRI in mammalian cells and its characterization

The extracellular domain of human FcγRI which interacts with a human IgG was expressed as recombinant soluble human FcγRI (rshFcγRI) by Chinese hamster ovary (CHO) cell. Stable CHO cell clones with efficient expression of rshFcγRI were established based on a dihydrofolate reductase (DHFR)/methotrexate (MTX) gene-amplification system. The CHO clones efficiently produced rshFcγRI under high-density continuous culture in a bioreactor. After 53 days of culture, the number of cells had reached approximately 4 × 10? cells/mL in the bioreactor and the average production of rshFcγRI had reached 7.4 mg L-medium?1 day?1. Secreted rshFcγRI was purified to a homogeneous state using cation exchange and affinity chromatographies. The binding affinities of rshFcγRI to human IgG subclasses were determined using surface plasmon resonance analysis. The binding affinities of rshFcγRI to human IgG1/κ and IgG3/κ were high (1.59 × 10?1? and 2.81 × 10?1? M, respectively), whereas that of rshFcγRI to human IgG4/κ was lower binding affinity (1.41 × 10?? M). Binding to IgG2/κ was not detectable. Examination of circular dichroism spectra indicated that rshFcγRI was rich in β-structures and loop or turn structures, but there were few α-helices. These results may be valuable for further studies of the structure and function of human FcγRI.     

Identification of the N-Terminal Domain of the Influenza Virus PA Responsible for the Suppression of Host Protein Synthesis

Cellular protein synthesis is suppressed during influenza virus infection, allowing for preferential production of viral proteins. To explore the impact of polymerase subunits on protein synthesis, we coexpressed enhanced green fluorescent protein (eGFP) or luciferase together with each polymerase component or NS1 of A/California/04/2009 (Cal) and found that PA has a significant impact on the expression of eGFP and luciferase. Comparison of the suppressive activity on coexpressed proteins between various strains revealed that avian virus or avian-origin PAs have much stronger activity than human-origin PAs, such as the one from A/WSN/33 (WSN). Protein synthesis data suggested that reduced expression of coexpressed proteins is not due to PA''s reported proteolytic activity. A recombinant WSN containing Cal PA showed enhanced host protein synthesis shutoff and induction of apoptosis. Further characterization of the PA fragment indicated that the N-terminal domain (PANt), which includes the endonuclease active site, is sufficient to suppress cotransfected gene expression. By characterizing various chimeric PANts, we found that multiple regions of PA, mainly the helix α4 and the flexible loop of amino acids 51 to 74, affect the activity. The suppressive effect of PANt cDNA was mainly due to PA-X, which was expressed by ribosomal frameshifting. In both Cal and WSN viruses, PA-X showed a stronger effect than the corresponding PANt, suggesting that the unique C-terminal sequences of PA-X also play a role in suppressing cotransfected gene expression. Our data indicate strain variations in PA gene products, which play a major role in suppression of host protein synthesis.     

Distal Sox binding elements of the alphaB-crystallin gene show lens enhancer activity in transgenic mouse embryos

alphaB-Crystallin, a member of the small heat shock protein (sHSP) family, is expressed in various tissues including lens, heart, and skeletal muscle. Previously we identified the gene of HSPB2, another member of the sHSP family, located 1-kb upstream of the alphaB-crystallin gene in a head-to-head manner. In the present study, we found a highly conserved region of 220 bp approximately 2.4-kb upstream of the alphaB-crystallin gene and examined its role in expression of the alphaB-crystallin gene. Transgenic mice containing 3 kb of the upstream sequence of the alphaB-crystallin gene showed lacZ reporter gene expression in the lens as well as the myotome and heart on embryonic day 12.5. Deletion analysis revealed that the -2656/-2267 region including the conserved region with four putative Sox binding elements (E1-E4) exhibits lens enhancer activity toward the alphaB-crystallin promoter. Gel shift assays showed that the Sox1 and Sox2 proteins preferentially bound to E2 and E4. Moreover, disruption of E2 and E4 abolished the reporter gene expression in the lens. These results indicate that the newly identified enhancer with Sox elements activates the alphaB-crystallin promoter in the lens, although they are separated by the entire HSPB2 gene.     

cDNA cloning and characterization of human and mouse Ca-independent phosphatidylethanolamine N-acyltransferases

The formation of N-acylphosphatidylethanolamine by N-acylation of phosphatidylethanolamine (PE) is the initial step in the biosynthetic pathway of bioactive N-acylethanolamines, including the endocannabinoid anandamide and the anti-inflammatory substance N-palmitoylethanolamine. We recently cloned a rat enzyme capable of catalyzing this reaction, and referred to the enzyme as Ca²⁺-independent N-acyltransferase (iNAT). Here we report cDNA cloning and characterization of human and mouse iNATs. We cloned iNAT-homologous cDNAs from human and mouse testes, and overexpressed them in COS-7 cells. The purified recombinant proteins abstracted an acyl group from both sn-1 and sn-2 positions of phosphatidylcholine, and catalyzed N-acylation of PE as well as phospholipase A₁/A₂-like hydrolysis. The iNAT activity was mainly detected in soluble rather than particulate fractions, and was only slightly increased by Ca²⁺. These results demonstrated that the human and mouse homologues function as iNAT. As for the organ distribution of iNAT, human testis and pancreas and mouse testis exhibited by far the highest expression level, suggesting its physiological importance in the specific organs. Moreover, mutagenesis studies showed crucial roles of His-154 and Cys-241 of rat iNAT in the catalysis and a possible role of the N-terminal domain in membrane association or protein–protein interaction.     

Enteral tube feeding alters the oral indigenous microbiota in elderly adults

Enteral tube feeding is widely used to maintain nutrition for elderly adults with eating difficulties, but its long-term use alters the environment of the oral ecosystem. This study characterized the tongue microbiota of tube-fed elderly adults by analyzing the 16S rRNA gene. The terminal restriction fragment length polymorphism (T-RFLP) profiles of 44 tube-fed subjects were compared with those of 54 subjects fed orally (average age, 86.4 ± 6.9 years). Bar-coded pyrosequencing data were also obtained for a subset of the subjects from each group (15 tube-fed subjects and 16 subjects fed orally). The T-RFLP profiles demonstrated that the microbiota of the tube-fed subjects was distinct from that of the subjects fed orally (permutational multivariate analysis of variance [perMANOVA], P < 0.001). The pyrosequencing data revealed that 22 bacterial genera, including Corynebacterium, Peptostreptococcus, and Fusobacterium, were significantly more predominant in tube-fed subjects, whereas the dominant genera in the subjects fed orally, such as Streptococcus and Veillonella, were present in much lower proportions. Opportunistic pathogens rarely detected in the normal oral microbiota, such as Corynebacterium striatum and Streptococcus agalactiae, were often found in high proportions in tube-fed subjects. The oral indigenous microbiota is disrupted by the use of enteral feeding, allowing health-threatening bacteria to thrive.