Research Advance on Molecular Mechanism of Abiotic and Biotic Stress Resistance in Sweet Potato

Sweet potato（Ipomoea batatas） is not only an important food crop, but also an important economic crop and energy crop. In recent years, as the develop- ment of molecular biology techniques, more and more abiotic and biotic stress-related genes were discovered in sweet potato. These genes can be divided into two categories： the regulatory genes and the functional genes, according to their different roles in stress pathways. This paper reviews the abiotic and biotic stress-related genes cloning, functional analysis and exogenous genes application in sweet potato, and makes expectation for stress resistance research of sweet potato in the future.

Streptozotocin-induced expression of Ngn3 and Pax4 in neonatal rat pancreatic α-cells

AIM： To investigate the mechanism behind β-cell regeneration in neonatal rat pancreas treated with strep- tozotocin （STZ）. METHODS： Neonatal Sprague Dawley rats were intra- peritoneally injected with 70 mg/kg STZ. Body weight, pancreas weight and blood glucose were recorded every two days after the treatment. To identify the expression and location of transcription factors in the rat pancreas, double immunofluorescent staining was performed using antibodies to specific cell markers and transcription factors. RESULTS： Expression of Neurogenin 3 （Ngn3）, a marker for endocrine precursor cells, was observed by immunofluorescence in a few β-cells and many a-cells. The expression reached a peak 12 d after treatment. Pax4, a transcription factor that lies downstream of Ngn3 and plays an important role in β-cell differentiation, was also expressed in the α-cells of STZ-treated rats. We did not observe significant changes in Nkx6.1, which is essential for β-cell maturation in the treated rats. CONCLUSION： α-cells dedifferentiated into endocrine precursor cells and acquired the ability to dedifferentiate in the neonatal rat pancreas after STZ treatment.

Diarylheptanoid-myricanone isolated from ethanolic extract of Myrica cerifera shows anticancer effects on HeLa and PC3 cell lines:signalling pathway and drug-DNA interaction

OBJECTIVE： To test if myricanone （02H2405）, a cyclic diarylheptanoid, has anticancer effects on two different cancer cell lines HeLa and PC3. The present study was conducted with a note on the drug-DNA interaction and apoptotic signalling pathway. METHODS： Several studies like cytotoxicity, nuclear damage, annexin-V-fluorescein isothiocyanate （FITC）/propidium iodide （PI）-Iabelled apoptotic assay and cell cycle arrest, immunoblot and reverse transcriptase-polymerase chain reaction （RT-PCR） were used following standard protocols. Circular dichroism （CD） spectroscopy was also done to evaluate whether myricanone effectively interacted with DNA to bring about conformational changes that could strongly inhibit the cancer cell proliferation. RESULTS： Myricanone showed a greater cytotoxic effect on PC3 cells than on HeLa cells. Myricanone promoted G0/G arrest in HeLa cells and S phase arrest in PC3 cells. Nuclear condensation and annexin V-FITC/PI studies revealed that myricanone promoted apoptotic cell death. CD spectroscopic data indicated that myricanone had an interaction with calf thymus DNA that changed DNA structural conformation. RT-PCR and immunoblot studies revealed that myricanone activated the apoptotic signalling cascades through down-regulation of transcription factors like nuclear factor-KB （NF-KB） （p65）, and signal transducers and activators of transcription 3 （STAT3）; cell cycle regulators like cyclin D1, and survivin and other signal proteins like Bcl-2 and up-regulation of Bax, caspase-9 and caspase-3. CONCLUSION： Myricanone induced apoptosis in both types of cancer cells by triggering caspase activation, and suppression of cell proliferation by down-regulation of NF-KB and STAT3 signalling cascades, which makes it a suitable candidate for possible use in the formulation of therapeutic alent for combatin cancer.

High REDOX RESPONSIVE TRANSCRIPTION FACTOR1 Levels Result in Accumulation of Reactive Oxygen Species in Arabidopsis thaliana Shoots and Roots

Redox Responsive Transcription Factor1 （RRTF1） in Arabidopsis is rapidly and transiently upregulated by H202, as well as biotic- and abiotic-induced redox signals. RRTF1 is highly conserved in angio- sperms, but its physiological role remains elusive. Here we show that inactivation of RRTF1 restricts and overexpression promotes reactive oxygen species （ROS） accumulation in response to stress. Transgenic lines overexpressing RRTF1 are impaired in root and shoot development, light sensitive, and susceptible to Alternaria brassicae infection. These symptoms are diminished by the beneficial root endophyte Piriformospora indica, which reduces ROS accumulation locally in roots and systemi- cally in shoots, and by antioxidants and ROS inhibitors that scavenge ROS. More than 800 genes were detected in mature leaves and seedlings of transgenic lines overexpressing RRTF1; ∽40% of them have stress-, redox-, ROS-regulated-, ROS-scavenging-, defense-, cell death- and related functions. Bioinformatic analyses and in vitro DNA binding assays demonstrate that RRTF1 binds to GCC-box-like sequences in the promoter of RRTFl-responsive genes. Upregulation of RRTF1 by stress stimuli and H202 requires WRKY18/40/60. RRTF1 is co-regulated with the phylogenet- ically related RAP2.6, which contains a GCC-box-like sequence in its promoter, but transgenic lines overexpressing RAP2.6 do not accumulate higher ROS levels. RRTF1 also stimulates systemic ROS accumulation in distal non-stressed leaves. We conclude that the elevated levels of the highly conserved RRTF1 induce ROS accumulation in response to ROS and ROS-producing abiotic and biotic stress signals.

Role of transcription factor acetylation n the regulation of metabolic homeostasis

Post-translational modifications （PTMs） of transcription factors play a crucial role in regulating metabolic homeostasis. These modifications include phosphory- lation, methylation, acetylation, ubiqulUnation, SUMOy- lation, and O-GIcNAcylation. Recent studies have shed light on the importance of lysine acetylation at nonhis- tone proteins including transcription factors. Acetyla- tion of transcription factors affects subcellular distribution, DNA affinity, stability, transcriptional activity, and current investigations are aiming to further expand our understanding of the role of lysine acetyla- tion of transcription factors. In this review, we summarize recent studies that provide new insights into the role of protein lysine-acetylation in the transcriptional regulation of metabolic homeostasis.

A Systems Biology Approach for Studying Heterotopic Ossification： Proteomic Analysis of Clinical Serum and Tissue Samples

Heterotopic ossification （HO） refers to the abnormal formation of bone in soft tissue. Although some of the underlying processes of HO have been described, there are currently no clinical tests using validated biomarkers for predicting HO formation. As such, the diagnosis is made radiographically after HO has formed. To identify potential and novel biomarkers for HO, we used isobaric tags for relative and absolute quantitation （iTRAQ） and high-throughput antibody arrays to produce a semi-quantitative proteomics survey of serum and tissue from subjects with （HO ＋） and without （HO-） heterotopic ossification. The resulting data were then analyzed using a systems biology approach. We found that serum samples from subjects experiencing traumatic injuries with resulting HO have a different proteomic expression controls. Subsequent quantitative ELISA identified profile compared to those from the matched five blood serum proteins that were differentially regulated between the HO-- and HO- groups. Compared to HO- samples, the amount of insulin-like growth factor I （IGF1） was up-regulated in HO＋ samples, whereas a lower amount of osteopontin （OPN）, myeloperoxidase （MPO）, runt-related transcription factor 2 （RUNX2）,and growth differentiation factor 2 or bone morphogenetic protein 9 （BMP-9） was found in HO ＋ samples （Welch two sample t-test; P 〈 0.05）. These proteins, in combination with potential serum biomarkers previously reported, are key candidates for a serum diagnostic panel that may enable early detection of HO prior to radiographic and clinical manifestations.