The NRAMP gene family encodes integral membrane protein and mediates the transport of Fe, however, its function in transport
of toxic metal ions is not very clear in plants. TcNRAMP3 was isolated from Thlaspi caerulescens, and encoded a metal transporter member of the NRAMP family. TcNRAMP3 was predominantly expressed in roots of T. caerulescens by semi-quantitative RT-PCR. The expression of TcNRAMP3 was induced by iron starvation and by the heavy metals Cd and Ni
in roots. TcNRAMP3 was able to rescue growth of an iron uptake fet3fet4 mutant yeast strain, suggesting a possible role in
iron transport. Expression of TcNRAMP3 in yeast increased Cd sensitivity and Cd content, while it enhanced the Ni resistance
and reduced Ni accumulation, indicating that TcNRAMP3 could accumulate Cd and exclude Ni in yeast. Furthermore, overexpression
of TcNRAMP3 in tobacco resulted in slight Cd sensitivity of root growth and did not influence Ni resistance. These results
suggested that TcNRAMP3 played a role in metal cation homeostasis in plant. 相似文献
A heavy metal responsive gene PvSR3 (GenBank accession number U54703) encoding an acid dehydrin was isolated from a mercuric chloride-treated bean (Phaseolus vulgaris L.) leaf cDNA library by differential screening using cDNAs derived from treated and untreated plants. The PvSR3 cDNA is 981-bp long and has a 606-bp open-reading frame with a 202-residue-deduced amino acid sequence. The PvSR3 sequence
contains two conserved repeats of the characteristic lysine-rich K segment (EKKGIMDKIKEKLPG) preceded by an 8-serine residue
stretch, whereas the Y segment (DEYGNP) conserved motif is absent. The deduced protein has a calculated molecular weight of
23 kDa and an isoelectric point of 5.2. Sequence similarity and comparative analysis showed that PvSR3 shares 70 and 73% similarity
with the dehydrin of poplar and pepper, respectively. Southern hybridizations indicated that PvSR3 was a low copy-number gene. Northern blot analysis revealed that PvSR3 mRNA was weakly detected in seedling leaves. However, the gene expression was strongly stimulated by heavy metals, such as
mercury, cadmium, arsenic, and coppper, whereas virus infection and salt had little effect on it. In contrast, PvSR3 was not responsive to drought or abscisic acid (ABA), and was downregulated by UV radiation. Furthermore, PvSR3 was upregulated by the exogenous signaling molecules, including salicylic acid (SA) and hydrogen peroxide (H2O2). It is suggested that PvSR3 is extremely related to heavy metal stress, and might play an important role in metal detoxification and resistance to the
damage caused by heavy metals. 相似文献
The length of the sgRNA-DNA complementary sequence is a key factor influencing the cleavage activity of Streptococcus pyogenes Cas9 (SpCas9) and its variants. The detailed mechanism remains unknown. Here, based on in vitro cleavage assays and base editing analysis, we demonstrate that reducing the length of this complementary region can confer nickase activity on SpCas9 and eSpCas9(1.1). We also show that these nicks are made on the target DNA strand. These properties encouraged us to develop a dual-functional system that simultaneously carries out double-strand DNA cleavage and C-to-T base conversions at separate targets. This system provides a novel tool for achieving trait stacking in plants.
Mechanisms underlying the attenuation of body weight gain and insulin resistance in response to high fat diet (HFD) by the curry compound curcumin need to be further explored. Although the attenuation of the inflammatory pathway is an accepted mechanism, a recent study suggested that curcumin stimulates Wnt signaling pathway and hence suppresses adipogenic differentiation. This is in contrast with the known repressive effect of curcumin on Wnt signaling in other cell lineages.
Methodology and Principal Findings
We conducted the examination on low fat diet, or HFD fed C57BL/6J mice with or without curcumin intervention for 28 weeks. Curcumin significantly attenuated the effect of HFD on glucose disposal, body weight/fat gain, as well as the development of insulin resistance. No stimulatory effect on Wnt activation was observed in the mature fat tissue. In addition, curcumin did not stimulate Wnt signaling in vitro in primary rat adipocytes. Furthermore, curcumin inhibited lipogenic gene expression in the liver and blocked the effects of HFD on macrophage infiltration and the inflammatory pathway in the adipose tissue.
Conclusions and Significance
We conclude that the beneficial effect of curcumin during HFD consumption is mediated by attenuating lipogenic gene expression in the liver and the inflammatory response in the adipose tissue, in the absence of stimulation of Wnt signaling in mature adipocytes. 相似文献
Brassica juncea L. is a Zn/Cd accumulator. To determine the physiological basis of its metal accumulation phenotype, the functional properties
and role of the metal efflux transporter BjCET2 were investigated using transgenic technology. Heterologous expression of BjCET2 in the double mutant yeast strain Δzrc1Δcot1 enhanced the metal tolerance of the yeast strain and led to decrease in Zn or Cd accumulation. Detection of green fluorescence
from green fluorescent protein (GFP) in the root tip of transgenic tobacco further revealed that BjCET2::GFP is localized
at the plasma membrane. Semi-quantitative RT-PCR analysis showed that BjCET2 was most abundant in the root and was weakly expressed in the stem and leaves. The expression of BjCET2 was up-regulated by heavy metals. However, exposure to low temperature, salt and drought did not affect the expression of
BjCET2. Overexpression of BjCET2 in transgenic B. juncea plants conferred heavy metal tolerance and increased Cd/Zn accumulation in the leaves. BjCET2-deficient B. juncea mediated by antisense RNA resulted in hypersensitivity to heavy metals and decreased Zn/Cd accumulation in the plants. These
results suggest that the heavy metal efflux of BjCET2 plays important roles in the metal tolerance of B. juncea and in Zn/Cd accumulation in B. juncea. 相似文献
To explore the regulation of expansin expression under heavy metal stresses, a novel expansin gene, BjEXPA1, and its upstream region were obtained from Indian mustard (Brassica juncea L.). BjEXPA1 encodes a cell wall protein of the α-subgroup of the expansin family. The expression of BjEXPA1 is regulated by exogenous phytohormones, NaCl, and heavy metals. Sequence analysis of its upstream region revealed the presence
of several putative cis-acting elements, including phytohormone response, abiotic stress response, and tissue-specific elements. GUS activity under
the control of the BjEXPA1 promoter allowed observation of BjEXPA1 spatial and temporal expression patterns. The reporter construct indicated that BjEXPA1 is induced by exogenous gibberellin and auxin, and inhibited by abscisic acid, CdCl2 and PEG6000. Transgenic tobacco seedlings overexpressing BjEXPA1 showed an altered phenotype and enhanced sensitivity to cadmium. Higher H2O2 accumulation and extensive plasma membrane damage were detected in the leaves of transgenic seedlings when exposed to Cd,
compared with wild-type plants. Our findings support the conclusion that overexpression of BjEXPA1 in tobacco renders plants susceptible to Cd stress, probably due to disruption of the growth process and/or the breakdown
of cell walls. 相似文献