An orthologue of the vacuolar Na+/H+ antiporter gene, AmNHX2, was isolated from a desert plant, Ammopiptanthus mongolicus, by RACE-PCR. It has a total length of 1,986 bp, with an open reading frame of 1,632 bp, encoding a predicted polypeptide
of 543 amino acids. Sequence similarity and exon constituent analysis clearly suggested that AmNHX2 encoded an AtNHX2 (an antiporter from Arabidopsis) like vacuolar Na+/H+ antiporter. AmNHX2 could be strongly induced by both drought and salt stress. Heterologous expression in the yeast mutant nhx1 indicated that AmNHX2 was the orthologue of ScNHX1, and the complementation effect was almost the same as AtNHX1. Over-expressing AmNHX2 resulted in enhanced tolerances to both drought and salt stresses in transgenic Arabidopsis plants. The transgenic plants
accumulated lower Na+ content in their leaves, showing healthier root system after salt stress, and retained more water during the drought stress.
Our work suggested that AmNHX2 was a salt tolerance determinant in A. mongolicus, but might not be a contributor to the difference in salt sensitivity between A. thaliana and A. mongolicus. 相似文献
Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr−1) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels.
DNA/RNA methylation plays an important role in lung cancer initiation and progression. Liquid biopsy makes use of cells, nucleotides and proteins released from tumor cells into body fluids to help with cancer diagnosis and prognosis. Methylation of circulating tumor DNA (ctDNA) has gained increasing attention as biomarkers for lung cancer. Here we briefly introduce the biological basis and detection method of ctDNA methylation, and review various applications of methylated DNA in body fluids in lung cancer screening, diagnosis, prognosis, monitoring and treatment prediction. We also discuss the emerging role of RNA methylation as biomarkers for cancer. 相似文献
Breeding for disease resistance is the most effective strategy to control diseases, particularly with broad‐spectrum disease resistance in many crops. However, knowledge on genes and mechanism of broad‐spectrum resistance and trade‐off between defence and growth in crops is limited. Here, we show that the rice copine genes OsBON1 and OsBON3 are critical suppressors of immunity. Both OsBON1 and OsBON3 changed their protein subcellular localization upon pathogen challenge. Knockdown of OsBON1 and dominant negative mutant of OsBON3 each enhanced resistance to rice bacterial and fungal pathogens with either hemibiotrophic or necrotrophic lifestyles. The defence activation in OsBON1 knockdown mutants was associated with reduced growth, both of which were largely suppressed under high temperature. In contrast, overexpression of OsBON1 or OsBON3 decreased disease resistance and promoted plant growth. However, neither OsBON1 nor OsBON3 could rescue the dwarf phenotype of the Arabidopsis BON1 knockout mutant, suggesting a divergence of the rice and Arabidopsis copine genes. Our study therefore shows that the rice copine genes play a negative role in regulating disease resistance and their expression level and protein location likely have a large impact on the balance between immunity and agronomic traits. 相似文献
Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation. 相似文献
Bestrophins (VMD2, VMD2L1, VMD2L2, and VMD2L3) are a new family of anion channels. The mechanisms of their regulation are not yet well understood. Recently, we found that a domain (amino acids 356-364) in the C terminus of mouse VMD2L3 (mBest3) inhibited channel activity when it was expressed in HEK293 cells (Qu, Z., Cui, Y., and Hartzell, H. C. (2006) FEBS Lett. 580, 2141-2214). Here we show that this auto-inhibitory (AI) domain in mBest3 and human (h)Best3 is composed of seven critical residues, (356)IPSFLGS(362). Replacement of any residue (except Pro(357)) in the domain with alanine activated Cl(-) currents. Substitution of Pro(357) with other amino acids, especially phenylalanine, did activate currents. Membrane biotinylation demonstrated that nonfunctional mBest3 protein was trafficked to the plasma membrane, implying that the AI domain inhibited channel gating but not trafficking. mBest3-F359A and hBest3-G361A mutations induced outwardly rectifying currents, suggesting that the AI domain is associated with the channel pore or gating mechanism. Supporting this suggestion, the mBest3 AI domain was demonstrated to be located within a membrane-associated region. When the wild-type mBest3 C terminus (amino acids 292-669) was expressed in HEK293 cells, the protein was located mainly in the particulate fraction, but it became soluble when a sequence containing the AI domain was deleted (Delta353-404). There is an AI domain ((357)QPSFQGS(363)) in mouse VMD2L1 (mBest2) as well, but its inhibitory effect is competed by a downstream facilitatory sequence (amino acids 405-454). These results suggest that an auto-inhibitory mechanism in C termini may be universal among bestrophins investigated in the study. 相似文献
A 1431-bp upstream fragment of Athsp70b was cloned via PCR amplification and expressed in onion epidermis by particle bombardment. Furthermore, the progressive deletions of the Athsp70b upstream fragment linked to the β-glucuronidase (GUS) coding region were performed. Then, a stable GUS expression was analyzed in tobacco BY2 cells and Arabidopsis. Our present results showed that about a 500-bp region upstream ATG of Athsp70b is suitable to confer heat inducibility to the GUS reporter gene in plants and around 116 bp contain nonperfect heat-sensitive element. This promoter responds to heat, salicylic acid, and benzyladenine. GUS staining was mainly observed in the vascular tissues and root tips, implying that Athsp70b is related to water transportation. 相似文献