Histochemical Techniques in Plant Science: More Than Meets the Eye.

Histochemistry is an essential analytical tool interfacing extensively with plant science. The literature is indeed constellated with examples showing its use to decipher specific physiological and developmental processes, as well as to study plant cell structures. Plant cell structures are translucent unless they are stained. Histochemistry allows the identification and localization, at the cellular level, of biomolecules and organelles in different types of cells and tissues, based on the use of specific staining reactions and imaging. Histochemical techniques are also widely used for the in vivo localization of promoters in specific tissues, as well as to identify specific cell wall components such as lignin and polysaccharides. Histochemistry also enables the study of plant reactions to environmental constraints, e.g. the production of reactive oxygen species (ROS) can be traced by applying histochemical staining techniques. The possibility of detecting ROS and localizing them at the cellular level is vital in establishing the mechanisms involved in the sensitivity and tolerance to different stress conditions in plants. This review comprehensively highlights the additional value of histochemistry as a complementary technique to high-throughput approaches for the study of the plant response to environmental constraints. Moreover, here we have provided an extensive survey of the available plant histochemical staining methods used for the localization of metals, minerals, secondary metabolites, cell wall components, and the detection of ROS production in plant cells. The use of recent technological advances like CRISPR/Cas9-based genome-editing for histological application is also addressed. This review also surveys the available literature data on histochemical techniques used to study the response of plants to abiotic stresses and to identify the effects at the tissue and cell levels.

[Cloning and function analysis of promoter of DcCDPK8 from Dendrobium catenatum].

DcCDPK8 involved in abiotic stress such as low temperature and signal transduction of hormones ABA and MeJA,but the transcriptional regulation is still unclear. In order to study the core promoter region of DcCDPK8 gene in Dendrobium catenatum and explore its transcriptional regulation mechanism,the DcCDPK8 gene promoter sequence was cloned by PCR from D. catenatum. Promoter sequence function was studied by fusion of 5 'terminal deletion and GUS gene. The results showed that the promoter sequence of DcCDPK8 gene has a low-temperature responsive element( LTR) between~(-1) 749 bp and-614 bp,two MeJA responsive elements between~(-1) 749 bp and-230 bp,and one ABA responsive elements between-614 bp and-230 bp. Three 5'-end different deletion fragments were constructed to fuse the eukaryotic expression vectors p BI121 with GUS,which were transformed into tobacco leaves. The GUS activity under cold stress treatment was DcCDPK8-p1>DcCDPK8-p2>DcCDPK8-p3. GUS activity under exogenous ABA induction was DcCDPK8-p1>DcCDPK8-p2>DcCDPK8-p3,and GUS activity under exogenous MeJA induction was DcCDPK8-p1>DcCDPK8-p2>DcCDPK8-p3. It is speculated that the ABA response element( ARE) in the promoter sequences of DcCDPK8 is positive regulatory role in response to exogenous ABA,the MeJA cis-acting element plays a negative role in response to exogenous MeJA.

Allium cepa root tip assay in assessment of toxicity of magnesium oxide nanoparticles and microparticles.

Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide (MgO) particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano- and microparticles (NPs and MPs) at a range of exposure concentrations (12.5, 25, 50, and 100µg/mL). The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index (MI) when compared to control cells and the effect was more significant for NPs than MPs (at p<0.05). Comet analysis revealed that the Deoxyribonucleic acid (DNA) damage in terms of percent tail DNA ranged from 6.8-30.1 over 12.5-100µg/mL concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.

Experimental Study on Yisheng Injection for Reducing Cold Ischemia Injury in Isolated Rat Heart / 重庆医科大学学报

Objective;To investigate whether the traditional Chinese medicine Yisheng Injection can reduce the injury on isolated rat heart induced by cold ischemia. Methods ;18 isolated female closed colony SD rats were divided into two groups at random. In the control group, the isolated rat hearts were preserved in 0.9% sodium chlorine solution at 4℃ , while in the experimental group ,the hearts were preserved in 0.9% sodium chlorine solution containing Yisheng injection at 4℃. The specimens were harvested 2,6,12, 24,48 and 72 hours after preservation. Histochemical changes were observed in two groups. Results ;In the control group, the activities of alkaline phosphatase ( ALP) and NADPH diaphorase (NADPHD) decreased after cold ischemia for 24 hours. Lactic dehydro-genase (LDH) decreased slightly, while ALP and NADPHD decreased evidently, after cold ischemia for 48 hours. Succinic dehydro-genase ( SDH) and cytochrome oxidase ( CCO) decreased slightly, and NADPHD disappeared after cold ischemia for 72 hours respectively. In the experimental group, NADPHD, LDH and CCO decreased slightly after cold ischemia for 24, 48 and 72 hours. ALP decreased slightly after cold ischemia for 48 hours, however, SDH showed no changes, after cold ischemia for 72 hours. Conclusion : Cold ischemia can induce cold ischemia injury in isolated rat hearts, especially the vascular endothelial cells being more sensitive. Yisheng injection can reduce this kind of injury to some degree.