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In bacteria, the hyper-phosphorylated nucleotide, guanosine 3′,5′-bis(pyrophosphate) (ppGpp), functions as a secondary messenger under stringent conditions. ppGpp levels are controlled by two distinct enzymes, namely RelA and SpoT, in Escherichia coli. RelA–SpoT homologs (RSHs) are also conserved in plants where they function in the plastids. The model plant Arabidopsis thaliana contains four RSHs: RSH1, RSH2, RSH3 and Ca2+-dependent RSH (CRSH). Genetic characterizations of RSH1, RSH2 and RSH3 were undertaken, which showed that the ppGpp-dependent plastidial stringent response significantly influences plant growth and stress acclimation. However, the physiological significance of CRSH-dependent ppGpp synthesis remains unclear, as no crsh -null mutant has been available. Here, to investigate the function of CRSH, a crsh -knockout mutant of Arabidopsis was constructed using a site-specific gene-editing technique, and its phenotype was characterized. A transient increase in ppGpp was observed for 30 min in the wild type (WT) after the light-to-dark transition, but this increase was not observed in the crsh mutant. Similar analyses were performed with the rsh2-rsh3 double and rsh1-rsh2-rsh3 triple mutants and showed that the transient increments of ppGpp in the mutants were higher than those in the WT. The increase in ppGpp in the WT and rsh2 rsh3 accompanied decrements in the mRNA levels of some plastidial genes transcribed by the plastid-encoded plastid RNA polymerase. These results indicate that the transient increase in ppGpp at night is due to CRSH-dependent ppGpp synthesis and that the ppGpp level is maintained by the hydrolytic activities of RSH1, RSH2 and RSH3 to accustom plastidial gene expression to darkness. [ABSTRACT FROM AUTHOR]

Lacquer tree sap, a raw material of traditional paints in East Asia, is hardened through laccase-catalyzed oxidation and the following polymerization of phenolic compound urushiol. In the sap’s water-insoluble fraction, we found two plantacyanins and a ferritin 2 domain-containing protein (TvFe2D, a homolog ofArabidopsisAT1G47980 and AT3G62730). The recombinant TvFe2D protein suppressed the accumulation of laccase-catalyzed oxidation products of a model substrate syringaldazine without decreasing oxygen consumption, the second substrate of laccase. The suppression was also observed when another substrate guaiacol or another oxidizing enzyme peroxidase was used. The functional domain of the suppression was the C-terminal half, downstream of the ferritin 2 domain. The results suggest that this protein may be involved in regulating the sap polymerization/hardening. We also discuss the possibility that homologous proteins of TvFe2D in other plants might be involved in the laccase- or peroxidase-mediated polymerization of phenolic compounds, such as lignin and flavonoids. Sap exuded from the wound site of lacquer tree. The ferritin 2 domain protein in it is a novel candidate regulating urushiol polymerization/hardening. [ABSTRACT FROM PUBLISHER]

Large-scale phenotyping of multicellular organisms is one of the current challenges in biology. We present a comprehensive and scalable pipeline that allows for the efficient phenotyping of root growth traits on a large scale. This includes a high-resolution, low-cost acquisition setup as well as the automated image processing software BRAT. We assess the performance of this pipeline in Arabidopsis thaliana under multiple growth conditions and show its utility by performing genome-wide association studies on 16 root growth traits quantified by BRAT each day during a 5-d time-course experiment. The most significantly associated genome region for root growth rate is a locus encoding a calcium sensing receptor. We find that loss of function and overexpression of this gene can significantly alter root growth in a growth condition dependent manner and that the minor natural allele of the Calcium Sensor Receptor locus is highly significantly enriched in populations in coastal areas, demonstrating the power of our approach to identify regulators of root growth that might have adaptive relevance. [ABSTRACT FROM AUTHOR]

In this study, we produced selective images of photosystems in plant chloroplasts in situ. We used a spectroimaging microscope, equipped with a near-infrared (NIR) laser that provided light at wavelengths mainly between 800 and 830 nm, to analyze chlorophyll autofluorescence spectra and images from chloroplasts in leaves of Zea mays at room temperature. Femtosecond laser excitation of chloroplasts in mesophyll cells revealed a spectral shape that was attributable to PSII and its antenna in the centers of grana spots. We found that a continuous wave emitted by the NIR laser at a wavelength as long as 820 nm induced chlorophyll autofluorescence with a high contribution from PSI through a one-photon absorption mechanism. A spectral shape attributable to PSI and its antenna was thus obtained using continuous wave laser excitation of chloroplasts in bundle sheath cells. These highly pure spectra of photosystems were utilized for spectral decomposition at every intrachloroplast space to show distributions of PSI and PSII and their associated antenna. A new methodology using an NIR laser to detect the PSI/PSII ratio in single chloroplasts in leaves at room temperature is described. [ABSTRACT FROM PUBLISHER]

Myosin XI, a class of myosins expressed in plants is believed to be responsible for cytoplasmic streaming and the translocation of organelles and vesicles. To gain further insight into the translocation of organelles and vesicles by myosin XI, an isoform of Arabidopsis myosin XI, MYA2, was chosen and its role in peroxisome targeting was examined. Using the yeast two-hybrid screening method, two small GTPases, AtRabD1 and AtRabC2a, were identified as factors that interact with the C-terminal tail region of MYA2. Both recombinant AtRabs tagged with His bound to the recombinant C-terminal tail region of MYA2 tagged with GST in a GTP-dependent manner. Furthermore, AtRabC2a was localized on peroxisomes, when its CFP-tagged form was expressed transiently in protoplasts prepared from Arabidopsis leaf tissue. It is suggested that MYA2 targets the peroxisome through an interaction with AtRabC2a. [ABSTRACT FROM PUBLISHER]

A plausible explanation for many MHC-linked diseases is lacking. Sequencing of the MHC class I region (coding units or full contigs) in several human and nonhuman primate haplotypes allowed an analysis of single nucleotide variations (SNV) across this entire segment. This diversity was not evenly distributed. It was rather concentrated within two gene-rich clusters. These were each centered, but importantly not limited to, the antigen-presenting HLA-A and HLA-B/-C loci. Rapid evolution of MHC-I alleles, as evidenced by an unusually high number of haplotype-specific (hs) and hypervariable (hv) (which could not be traced to a single species or haplotype) SNVs within the classical MHC-I, seems to have not only hitchhiked alleles within nearby genes, hut also hitchhiked deleterious mutations in these same unrelated loci. The over-representation of a fraction of these hvSNV (hv1SNV) along with hsSNV as compared to those that appear to have been maintained throughout primate evolution (trans-species diversity; tsSNV; included within hv2SNV) tends to establish that the majority of the MHC polymorphism is de novo (species specific). This is most likely reminiscent of the fact that these hsSNV and hv1SNV have been selected in adaptation to the constantly evolving microbial antigenic repertoire. [ABSTRACT FROM AUTHOR]

Most plastid promoters recognized by bacteria-like plastid RNA polymerase (PEP) are similar to E. coli σ70-type promoters comprising “–35” and “–10” elements. Among them, psbA promoter is unique in bearing additional elements between the conserved –35 and –10 elements. The psbA promoter activity is differentially maintained in the mature chloroplasts where the activity of most PEP promoters declines. Previously, we identified two types of PEP activities in wheat seedlings [Satoh et al. (1999) Plant J. 18: 407]; PEP present in the mature chloroplasts of the leaf tip (tip-type PEP) can initiate transcription from the –35-destructed psbA promoter, but the –35 element is essential for transcription by PEP present in immature chloroplasts of the leaf base (base-type PEP). To reveal which type of PEP functions in various types of plastids in tobacco, we analyzed the tobacco psbA promoter by means of a transplastomic approach. The promoter core context (–42 to +9) was sufficient for developmental regulation of the psbA promoter activity. The –35 promoter element was important for transcription initiation at the psbA promoter in all types of plastids, including chloroplasts in mature leaves, leucoplasts in roots, etioplasts in etiolated cotyledons. The conclusion is that the PEP bearing a promoter preference, similar to the wheat base-type PEP, functions dominantly in tobacco chloroplasts. [ABSTRACT FROM PUBLISHER]

A fusion between the plastid psbA promoter and the green fluorescent protein gene (gfp) was introduced into the tobacco chloroplast genome by stable plastid transformation. GFP was synthesized actively and exclusively in the chloroplasts. Tubular projections filled with GFP but containing no chlorophyll were visualized for the first time in chloroplasts of these transplastomic plants. Occasionally, the tubules connect chloroplasts with each other, suggesting the possibility of the exchange of endogenous proteins. However, the fusion of protoplasts between the transplastomic and wild-type plants showed that such chloroplast connections might be rare in mesophyll protoplasts. [ABSTRACT FROM AUTHOR]

Analyzes the susceptibility locus of psoriasis vulgaris in the telomere of human leukocyte antigen-C gene using refined microsatellite markers. Prevalence; Mode of inheritance; Genes involved in the development of epidermolysis bullosa simplex.

Calcium signaling plays a crucial role in the regulation of plant physiological processes. There is increasing evidence that plant endosymbiotic organelles, chloroplast and mitochondrion, are engaged in intracellular calcium signaling network. This review summarizes the current knowledge on calcium signaling in organelles and their roles in stress responses.Recent studies have demonstrated that chloroplasts and mitochondria evoke specific Ca2+ signals in response to biotic and abiotic stresses in a stress-dependent manner. The identification of Ca2+ transporters and Ca2+ signaling molecules in chloroplasts and mitochondria implies that they play roles in controlling not only intra-organellar functions, but also extra-organellar processes such as plant immunity and stress responses. It appears that organellar Ca2+ signaling might be more important to plant cell functions than previously thought. This review briefly summarizes what is known about the molecular basis of Ca2+ signaling in plant mitochondria and chloroplasts. [ABSTRACT FROM PUBLISHER]

The frequency and HLA-Aallelic associations of a HERVK9 DNA structural polymorphism located in close proximity to the highly polymorphic HLA-A gene within the major histocompatibility complex (MHC) genomic region were determined in Japanese, African Americans, and Australian Caucasians to better understand its human population evolutionary history. The HERVK9 insertion or deletion was detected as a 3′ LTR or a solo LTR, respectively, by separate PCR assays. The average insertion frequency of the l-IERVK9.HG was significantly different (P < 1.083e-6) between the Japanese (0.59) and the African Americans (0.34) or Australian Caucasians (0.37). LD analysis predicted a highly significant (P < 1 .0e-5) linkage between the HLA-A and HERVK9 alleles, probably as a result of hitchhiking (linkage). Evolutionary time estimates of the solo, 5′ and 3′ LTR nucleotide sequence divergences suggest that the HERVK9 was inserted 17.3 MYA with the first structural deletion occurring 15.1 MYA. The LTR/HLA-A-haplotypes appear to have been formed mostly during the past 3.9 MY The HERVK9 insertion and deletion, detected by a simple and economical PCR method, is an informative genetic and evolutionary marker for the study of H LA-A haplotype variations, human migration, the origins of contemporary populations, and the possibility of disease associations. [ABSTRACT FROM AUTHOR]