A single origin of the photosynthetic organelle in different Paulinella lineages

Background

Hybrid zones represent valuable opportunities to observe evolution in systems that are unusually dynamic and where the potential for the origin of novelty and rapid adaptation co-occur with the potential for dysfunction. Recently initiated hybrid zones are particularly exciting evolutionary experiments because ongoing natural selection on novel genetic combinations can be studied in ecological time. Moreover, when hybrid zones involve native and introduced species, complex genetic patterns present important challenges for conservation policy. To assess variation of admixture dynamics, we scored a large panel of markers in five wild hybrid populations formed when Barred Tiger Salamanders were introduced into the range of California Tiger Salamanders.

Results

At three of 64 markers, introduced alleles have largely displaced native alleles within the hybrid populations. Another marker (GNAT1) showed consistent heterozygote deficits in the wild, and this marker was associated with embryonic mortality in laboratory F2's. Other deviations from equilibrium expectations were idiosyncratic among breeding ponds, consistent with highly stochastic demographic effects.

Conclusion

While most markers retain native and introduced alleles in expected proportions, strong selection appears to be eliminating native alleles at a smaller set of loci. Such rapid fixation of alleles is detectable only in recently formed hybrid zones, though it might be representative of dynamics that frequently occur in nature. These results underscore the variable and mosaic nature of hybrid genomes and illustrate the potency of recombination and selection in promoting variable, and often unpredictable genetic outcomes. Introgression of a few, strongly selected introduced alleles should not necessarily affect the conservation status of California Tiger Salamanders, but suggests that genetically pure populations of this endangered species will be difficult to maintain.     

'Rinrei', a brassinosteroid-deficient dwarf mutant of faba bean (Vicia faba L.)

A dwarf mutant of broad bean ( Vicia faba L.), the variety Rinrei, has been created by γ -ray irradiation. Rinrei is characterized by dark green leaves and by reduced plant length, internode and petiole length, shoot weight, and number of branches. Genetic analysis of hybrids between Rinrei and two wild-type lines indicated that these characteristics are controlled by a single recessive gene. The phenotype of Rinrei was restored to that of the wild type by application of brassinolide, but not by GA₃. Qualitative and quantitative analysis by gas chromatography–mass spectrometry indicated that 24-methylenecholesterol and isofucosterol accumulated in Rinrei to levels more than 30 times higher than in the wild type. In contrast, Rinrei had lower than wild-type levels of campesterol, sitosterol and brassinosteroids. Therefore, Rinrei is a brassinosteroid-deficient mutant defective in sterol C-24 reduction. The gene was tentatively designated as brassinosteroid deficient dwarf 1 , bdd1 , which seems to be a homologue of Arabidopsis dwf1 ( dim , cbb1 ) and pea lkb .     

Purification and inactivation by substrate of an allene oxide synthase (CYP74) from corn (Zea mays L.) seeds

The allene oxide synthase (AOS) was purified from corn (Zea mays) seeds to homogeneity and characterized partially. The corn AOS was a hemoprotein cytochrome P450 with a molecular weight and pI of 53,000 and 6.0, respectively. The corn AOS was found to be irreversibly inactivated by a substrate, 13-hydroperoxyoctadienoic acid. The rate of the enzyme inactivation was higher at low pHs.     

Minocycline attenuates both OGD-induced HMGB1 release and HMGB1-induced cell death in ischemic neuronal injury in PC12 cells

High mobility group box-1 (HMGB1), a non-histone DNA-binding protein, is massively released into the extracellular space from neuronal cells after ischemic insult and exacerbates brain tissue damage in rats. Minocycline is a semisynthetic second-generation tetracycline antibiotic which has recently been shown to be a promising neuroprotective agent. In this study, we found that minocycline inhibited HMGB1 release in oxygen-glucose deprivation (OGD)-treated PC12 cells and triggered the activation of p38mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK1/2). The ERK kinase (MEK)1/2 inhibitor U-0126 and p38MAPK inhibitor SB203580 blocked HMGB1 release in response to OGD. Furthermore, HMGB1 triggered cell death in a dose-dependent fashion. Minocycline significantly rescued HMGB1-induced cell death in a dose-dependent manner. In light of recent observations as well as the good safety profile of minocycline in humans, we propose that minocycline might play a potent neuroprotective role through the inhibition of HMGB1-induced neuronal cell death in cerebral infarction.     

Molecular cloning, characterization and analysis of the intracellular localization of a water-soluble chlorophyll-binding protein (WSCP) from Virginia pepperweed (Lepidium virginicum), a unique WSCP that preferentially binds chlorophyll b in vitro

Various plants possess non-photosynthetic, hydrophilic chlorophyll (Chl) proteins called water-soluble Chl-binding proteins (WSCPs). WSCPs are categorized into two classes; Class I (photoconvertible type) and Class II (non-photoconvertible type). Among Class II WSCPs, only Lepidium virginicum WSCP (LvWSCP) exhibits a low Chl a/b ratio compared with that found in the leaf. Although the physicochemical properties of LvWSCP have been characterized, its molecular properties have not yet been documented. Here, we report the characteristics of the LvWSCP gene, the biochemical properties of a recombinant LvWSCP, and the intracellular localization of LvWSCP. The cloned LvWSCP gene possesses a 669-bp open reading frame. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis revealed that the precursor of LvWSCP contains both N- and C-terminal extension peptides. RT-PCR analysis revealed that LvWSCP was transcribed in various tissues, with the levels being higher in developing tissues. A recombinant LvWSCP and hexa-histidine fusion protein (LvWSCP-His) could remove Chls from the thylakoid in aqueous solution and showed an absorption spectrum identical to that of native LvWSCP. Although LvWSCP-His could bind both Chl a and Chl b, it bound almost exclusively to Chl b when reconstituted in 40 % methanol. To clarify the intracellular targeting functions of the N- and C-terminal extension peptides, we constructed transgenic Arabidopsis thaliana lines expressing the Venus protein fused with the LvWSCP N- and/or C-terminal peptides, as well as Venus fused at the C-terminus of LvWSCP. The results showed that the N-terminal peptide functioned in ER body targeting, while the C-terminal sequence did not act as a trailer peptide.     

Bacillus stearothermophilus plasmid pSTK1 replicon is functional in Escherichia coli

Summary A kanamycin-resistant plasmid possessing a thermostable replicon derived from Bacillus stearothermophilus cryptic plasmid pSTK1 was constructed. The plasmid could transform not only B. stearothermophilus and Bacillus subtilis, but also Gram-negative Escherichia coli. The behavior of the plasmid in the hosts was examined. The plasmid was stably maintained even at 67°C in B. stearothermophilus without selective pressure. During the plasmid replication, single-stranded DNA (ssDNA) intermediates were found in E. coli, while these were not found in B. subtilis.     

Phase I study of α-galactosylceramide-pulsed antigen presenting cells administration to the nasal submucosa in unresectable or recurrent head and neck cancer

Background Human Vα24 natural killer T (NKT) cells are activated by the specific ligand, α-galactosylceramide (α-GalCer), in a CD1d-dependent manner. Potent anti-tumor activity of activated NKT cells has been previously demonstrated. Methods We conducted a phase I study with α-GalCer-pulsed antigen presenting cells (APCs) administered in the nasal submucosa of patients with head and neck cancer, and evaluated the safety and feasibility of such a treatment. Nine patients with unresectable or recurrent head and neck cancer received two treatments 1 week apart, of 1 × 10⁸ of α-GalCer-pulsed autologous APCs into the nasal submucosa. Results During the clinical study period, no serious adverse events (Common Terminology Criteria for Adverse Events version 3.0 greater than grade 3) were observed. After the first and the second administration of α-GalCer-pulsed APCs, an increased number of NKT cells was observed in four patients and enhanced natural killer activity was detected in the peripheral blood of eight patients. Conclusion The administration of α-GalCer-pulsed APCs into the nasal submucosa was found to be safe and induce anti-tumor activity in some patients.     

Coaggregation of Porphyromonas gingivalis and Prevotella intermedia.

Porphyromonas gingivalis cells coaggregated with Prevotella intermedia cells. The coaggregation was inhibited with L-arginine, L-lysine, Nalpha-p-tosyl-L-lysine chloromethyl ketone, trypsin inhibitor, and leupeptin. Heat- and proteinase K-treated P. gingivalis cells showed no coaggregation with P. intermedia cells, whereas heat and proteinase K treatments of P. intermedia cells did not affect the coaggregation. The vesicles from P. gingivalis culture supernatant aggregated with P. intermedia cells, and this aggregation was also inhibited by addition of L-arginine or L-lysine and by heat treatment of the vesicles. The rgpA rgpB, rgpA kgp, rgpA rgpB kgp, and rgpA kgp hagA mutants of P. gingivalis did not coaggregate with P. intermedia. On the other hand, the fimA mutant lacking the FimA fimbriae showed coaggregation with P. intermedia as well as the wild type parent. These results strongly imply that a heat-labile and proteinous factor on the cell surface of P gingivalis, most likely the gingipain-adhesin complex, is involved in coaggregation of P. gingivalis and P. intermedia.