Determination of the in vivo distribution of nuclear matrix attachment regions using a polymerase chain reaction-based assay in Arabidopsis thaliana

Lettuce-based production of an oral vaccine against porcine edema disease for the seed lot system

Plant-made oral vaccines can be a cost-effective method to control infectious diseases of humans and farm animals. Pig edema is a bacterial disease caused by enterohemorrhagic Escherichia coli producing the toxin Shiga toxin 2e (Stx2e). In our previous report, we chose the non-toxic B subunit of Stx2e (Stx2eB) as a vaccine antigen, and Stx2eB was expressed in lettuce (Lactuca sativa L., cv. Green wave). We found that a double repeated Stx2eB (2×Stx2eB) accumulates to higher levels than a single Stx2eB. In this study, we analyzed progeny plants introduced with 2×Stx2eB in which the gene was expressed under the control of conventional cauliflower mosaic virus 35S RNA (CaMV 35S) promoter, and found that the lettuce underwent transgene silencing and bore few seeds. We resolved these problems by using a transgene cassette which harbored a transcriptional promoter derived from the lettuce ubiquitin gene and a longer version of HSPT. The lettuce harboring this expression construct will be valuable in establishing the seed lot system on the basis that thousands of seeds can be obtained from one plant body and the resulting progeny plants accumulate 2×Stx2eB at high levels without the transgene silencing.

Development of an R4 dual-site (R4DS) gateway cloning system enabling the efficient simultaneous cloning of two desired sets of promoters and open reading frames in a binary vector for plant research

Vast numbers of proteins work cooperatively to exert their functions in various cells. In order to understand the functions and molecular mechanisms of these proteins in plants, analyses of transgenic plants that concomitantly express two protein-coding genes are often required. We developed a novel Gateway cloning technology-compatible binary vector system, the R4 dual-site (R4DS) Gateway cloning system, which enables the easy and efficient cloning of two desired sets of promoters and open reading frames (ORFs) into a binary vector using promoter and ORF entry clones. In this system, C-terminal fusions with 17 kinds of tags including visible reporters and epitope tags are available for each ORF, and selection by four kinds of resistance markers is possible. We verified that the R4DS Gateway cloning system functioned well in Arabidopsis thaliana by observing the expression and localization patterns of fluorescent proteins fused with organelle-targeting signals and driven by stomatal-lineage specific promoters. We also confirmed that the two cloning sites in the R4DS Gateway cloning system were equivalent and independently regulated. The results obtained indicate that the R4DS Gateway cloning system facilitates detailed comparisons of the expression patterns of two promoters as well as co-localization and interaction analyses of two proteins in specific cells in plants.

A dual-site gateway cloning system for simultaneous cloning of two genes for plant transformation

Analyses of the subcellular localization of proteins and protein-protein interaction networks are essential to uncover the molecular basis of diverse biological processes in plants. To this end, we have created a Gateway cloning-compatible vector system, named dual-site (DS) Gateway cloning system to allow simple cloning of two expression cassettes in a binary vector and to express them simultaneously in plant cells. In the DS Gateway cloning system, (i) a moderate constitutive nopaline synthase promoter (Pnos), which is much suitable for localization analysis, is used to guide each expression cassette, (ii) four series of vectors with different plant resistance markers are established, (iii) N-terminal fusion with 6 fluorescent proteins and 7 epitope tags is available, (iv) both N- and C-terminal fusions with split enhanced yellow fluorescent protein (EYFP) are possible for efficient detection of protein-protein interactions using a bimolecular fluorescence complementation (BiFC) assay. The usefulness of the DS Gateway cloning system has been demonstrated by the analysis of the expression and the subcellular localization patterns of two Golgi proteins in stable expression system using A. thaliana, and by the analyses of interactions between subunits of coat protein complex II (COPII) both in transient and stable expression systems using Japanese leek and A. thaliana, respectively. The DS Gateway cloning system provides a multipurpose, efficient expression tool in gene function analyses and especially suitable for investigating interactions and subcellular localization of two proteins in living plant cells.

T-type Ca²⁺ channels regulate the exit of cardiac myocytes from the cell cycle after birth

T-type Ca(2+) channels (TTCCs) are expressed in the fetal heart and then disappear from ventricular myocytes after birth. The hypothesis examined in this study was the α1G TTCCs' influence in myocyte maturation and their rapid withdrawal from the cell cycle after birth.

METHODS

Cardiac myocytes were isolated from neonatal and adult wild type (WT), α1G-/- and α1G over expressing (α1GDT) mice. Bromodeoxyuridine (BrdU) uptake, myocyte nucleation, cell cycle analysis, and T-type Ca(2+) currents were measured.

RESULTS

All myocytes were mono-nucleated at birth and 35% of WT myocytes expressed functional TTCCs. Very few neonatal myocytes had functional TTCCs in α1G-/- hearts. By the end of the first week after birth no WT or α1G-/- had functional TTCCs. During the first week after birth about 25% of WT myocytes were BrdU+ and became bi-nucleated. Significantly fewer α1G-/- myocytes became bi-nucleated and fewer of these myocytes were BrdU+. Neonatal α1G-/- myocytes were also smaller than WT. Adult WT and α1G-/- hearts were similar in size, but α1G-/- myocytes were smaller and a greater % were mono-nucleated. α1G over expressing hearts were smaller than WT but their myocytes were larger.

CONCLUSIONS

The studies performed show that loss of functional TTCCs is associated with bi-nucleation and myocyte withdrawal from the cell cycle. Loss of α1G TTCCs slowed the transition from mono- to bi-nucleation and resulted in an adult heart with a greater number of small cardiac myocytes. These results suggest that TTCCs are involved in the regulation of myocyte size and the exit of myocytes from the cell cycle during the first week after birth.