Records ofApristurus herklotsi (Lamniformes,Scyliorhinidae) and discussion of its taxonomic relationships

Additional specimens of the rareApristurus herklotsi are reported, and the characteristic features of this species are discussed.A. herklotsi is concluded to be a distinct species, having a very long snout, a narrow distance between the nostrils, a long caudal fin, a short abdomen, numerous teeth on both jaws, and a low number of monospondylous vertebrae.A. herklotsi appears to be mature at about 44 cm in total length.     

Wiring diagrams of MAPK regulation by MEKK1, 2, and 3.

Mitogen-activated protein kinase (MAPK) pathways are activated by a plethora of stimuli. The literature is filled with papers describing the activation of different MAPKs by almost any stimulus or insult imaginable to cells. In this review, we use signal transduction wiring diagrams to illustrate putative upstream regulators for the MAPK kinase kinases, MEKK1, 2, and 3. Targeted gene disruption of MEKK1, 2, or 3 defined phenotypes for each MEKK associated with loss of specific MAPK regulation. Genetic analysis of MEKK function clearly defines specific components of the wiring diagram that require MEKK1, 2, or 3 for physiological responses. We propose that signal transduction network wiring diagrams are valuable tools for hypothesis building and filtering physiologically relevant phenotypic responses from less connected protein relations in the regulation of MAPK pathways.     

Refined genetic analysis of the region II che mutants in Salmonella typhimurium

Summary From a detailed complementation analysis of the region II che mutants of Salmonella typhimurium, we have located five che genes, cheA, cheW, cheR, cheB, and cheY. We have shown that corrections are required in the previous assignment of the mutations in four strains: both SL2514 and SL2515 which have been reported to be cheY mutants are cheR mutants, SL2539 is not a cheA but a cheW mutant, and ST171 which has been reported to be a cheZ mutant is a double mutant with defects in both cheA and cheB. Since ST171 is the only cheZ mutant so far isolated, the idea that the cheZ gene might play an essential role in chemotaxis in S. typhimurium as in Escherichia coli has lost its experimental basis. Furthermore, a number of deletion mutants in region II resulting from the excision of Tn10 have been isolated and analysed. From these experiments, we propose that the gene order in region II is flaK-flaE-motA-motB-cheA-cheW-cheR-cheB-cheY-flaM-flaC, which is identical with that in E. coli.     

Inhibitory ca2+-control of movement of beads coated withphysarum myosin along actin-cables inChara internodal cells

Summary The actin-activated ATPase activityPhysarum myosin was shown to be inhibited of M levels of Ca²⁺. To determine if Ca²⁺ regulates ATP-dependent movement ofPhysarum myosin on actin, latex beads coated withPhysarum myosin were introduced intoChara cells by intracellular perfusion. In perfusion solution containing EGTA, the beads moved along the parallel arrays ofChara actin filaments at a rate of 1.0–1.8 m/sec; however, in perfusion solution containing Ca²⁺, the rate reduced to 0.0–0.7 m/sec. The movement of beads coated with scallop myosin, whose actin-activated ATPase activity is activated by Ca²⁺, was observed only in the perfusion solution containing Ca²⁺, indicating that myosin is responsible for the inhibitory effect of Ca²⁺ onPhysarum myosin movement. The involvement of this myosin-linked regulation in the inhibitory effect of Ca²⁺ on the cytoplasmic streaming observed inChara internodal cell andPhysarum plasmodium was discussed.Abbreviations ATP adenosine 5-triphosphate - DTT dithiothreitol - EDTA ethylenediaminetetraacetic acid - EGTA ethyleneglycolbis(-aminoethylether) N,N,N,N-tetraacetic acid - PIPES piperazine-N,N-bis(2-ethanesulfonic acid)     

DNA methylation profiles provide a viable index for porcine pluripotent stem cells

Porcine induced pluripotent stem cells (iPSCs) provide useful information for translational research. The quality of iPSCs can be assessed by their ability to differentiate into various cell types after chimera formation. However, analysis of chimera formation in pigs is a labor‐intensive and costly process, necessitating a simple evaluation method for porcine iPSCs. Our previous study identified mouse embryonic stem cell (ESC)‐specific hypomethylated loci (EShypo‐T‐DMRs), and, in this study, 36 genes selected from these were used to evaluate porcine iPSC lines. Based on the methylation profiles of the 36 genes, the iPSC line, Porco Rosso‐4, was found closest to mouse pluripotent stem cells among 5 porcine iPSCs. Moreover, Porco Rosso‐4 more efficiently contributed to the inner cell mass (ICM) of blastocysts than the iPSC line showing the lowest reprogramming of the 36 genes (Porco Rosso‐622‐14), indicating that the DNA methylation profile correlates with efficiency of ICM contribution. Furthermore, factors known to enhance iPSC quality (serum‐free medium with PD0325901 and CHIR99021) improved the methylation status at the 36 genes. Thus, the DNA methylation profile of these 36 genes is a viable index for evaluation of porcine iPSCs. genesis 51:763–776. © 2013 Wiley Periodicals, Inc.     

Coevolution and Hierarchical Interactions of Tomato mosaic virus and the Resistance Gene Tm-1

During antagonistic coevolution between viruses and their hosts, viruses have a major advantage by evolving more rapidly. Nevertheless, viruses and their hosts coexist and have coevolved, although the processes remain largely unknown. We previously identified Tm-1 that confers resistance to Tomato mosaic virus (ToMV), and revealed that it encodes a protein that binds ToMV replication proteins and inhibits RNA replication. Tm-1 was introgressed from a wild tomato species Solanum habrochaites into the cultivated tomato species Solanum lycopersicum. In this study, we analyzed Tm-1 alleles in S. habrochaites. Although most part of this gene was under purifying selection, a cluster of nonsynonymous substitutions in a small region important for inhibitory activity was identified, suggesting that the region is under positive selection. We then examined the resistance of S. habrochaites plants to ToMV. Approximately 60% of 149 individuals from 24 accessions were resistant to ToMV, while the others accumulated detectable levels of coat protein after inoculation. Unexpectedly, many S. habrochaites plants were observed in which even multiplication of the Tm-1-resistance-breaking ToMV mutant LT1 was inhibited. An amino acid change in the positively selected region of the Tm-1 protein was responsible for the inhibition of LT1 multiplication. This amino acid change allowed Tm-1 to bind LT1 replication proteins without losing the ability to bind replication proteins of wild-type ToMV. The antiviral spectra and biochemical properties suggest that Tm-1 has evolved by changing the strengths of its inhibitory activity rather than diversifying the recognition spectra. In the LT1-resistant S. habrochaites plants inoculated with LT1, mutant viruses emerged whose multiplication was not inhibited by the Tm-1 allele that confers resistance to LT1. However, the resistance-breaking mutants were less competitive than the parental strains in the absence of Tm-1. Based on these results, we discuss possible coevolutionary processes of ToMV and Tm-1.