Signal perception and transduction in plants

Plants are sessile organisms and are not able to move away from adverse environmental conditions and must response to an array of environmental and developmental cues. They heavily rely on high sensitivity detection and adaptation mechanisms to environmental perturbations. Signal transduction, the means whereby cells construct response to a signal, is a recently defined focus of research in plant biology. Over the past decade our understanding of plant signaling pathways has increased greatly, in part due to the use of molecular genetics and biochemical tools in model plants for example Arabidopsis thaliana and Medicago truncatula. This has assisted us in the identification of components of many signal transduction pathways in diverse physiological systems for example hormonal, developmental and environmental signal transduction pathways and cross-talk between them.During the last 15 years the number of known plant hormones has grown from five to at least ten. Furthermore, many of the proteins involved in plant hormone signaling pathways have been identified, including receptors for many of the major hormones. In addition, recent studies confirm that hormone signaling is integrated at several levels during plant growth and development.In this review paper we have covered recent work in signaling pathway in plants especially how plants sense biotic and abiotic stresses and the potential mechanisms by which different chemical molecules and their downstream signaling components modulates stress tolerance

The Role of Radiology (X-Ray versus Computed Tomography) in Medicolegal Cases Presented at a Tertiary Care Hospital in Pakistan

Objectives:  A prospective observational study was aimed to assess the role of plain radiographs and computed tomography in detecting head injuries presented at the medicolegal office at the Forensics and Radiology Departments, Gambat Medical Hospital, Sindh. Material and Methods:  All cases referred from the Medicolegal Office (MLO) with head injury were included. All victims underwent X-ray head and computed tomography skull was done with 1 or 1.5 cm thick axial sections without administration of intravenous contrast. The radiological reports of X-ray head and CT scans were documented and comparatively evaluated. Results:  Mean age was 38.63 ± 3.91 years. In 51 (45.13%) cases, X-ray was able to detect skull fracture, while CT scan detected 64(56.64%) skull fractures. There were 54 (84.3%) true positives, 3 (2.6%) false positives, 10(8.8%) false negatives, and 40 (40.7%) true negatives. The accuracy of X-ray to detect skull fracture was 88.50%. Conclusion:  X-ray had a sensitivity and specificity of 84.38% and 93.88%, respectively. It is a reliable tool to detect skull fractures in victims of assault in comparison with CT scans. X-ray is also associated with low dose radiation exposure as compared with CT scan which delivers 70 times more exposure than the former

Comparison of Outcome of Bipolar Electrocautery versus Harmonic Scalpel in the Management of Third and Fourth Degree Hemorrhoids

Objective: To compare the outcome of bipolar electrocautery versus harmonic scalpel in the management of third degree hemorrhoids. Methodology: This is a comparative study performed at Different Private Clinics of Karachi from the duration of January 2020 to June 2020. Patients with symptomatic grade III hemorrhoids and grade IV hemorrhoids were randomly divided into two groups. . Either group had 64 patients. One group underwent hemorrhoidectomy using bipolar electrocautery (Group A), other group underwent hemorrhoidectomy using harmonic scalpel hemorrhoidectomy (Group B). Results: The total number of patients was 128 with 64 in either group. The mean operating time in group A was 22 ± 4.7 minutes, while that in group B was 35 ± 2.2 minutes. The mean duration of hospital stay among group A was 1.7 ± 0.5 days while among group B patients was 2.1 ± 1.2 days. Mean VAS score for pain at first post-operative day in group A patients was 7 ± 0.6 days while mean VAS score for pain among group B patients was 8.5 ± .2 days. Conclusion: Our study concludes that harmonic scalpel hemorrhoidectomy offers better post-operative patient satisfaction score as compared to bipolar diathermy. No significant difference in hospital stay was found. The number of patients with post-operative urinary retention were more in harmonic scalpel group while in diathermy group, more patients had post-operative hemorrhage

Plasmalemma from the roots of cucumber: Isolation by two-phase partitioning and characterization

Plasmalemma was isolated from the roots of 2‐week‐old cucumber plants (Cucumis sativus L. cv. Rhensk druv) by utilizing an aqueous polymer two‐phase system with 6.5%:6.5% (w/w) Dextran T500 and polyethylene glycol (PEG) 3350 at pH 7.8. The plasmalemma fraction comprised ca 6% of the membrane proteins contained in the microsomal fraction. The specific activity of the plasma membrane marker enzyme (K+, Mg2+‐ATPase) was 14‐ to 17‐times higher in the upper (PEG‐rich) than in the lower (Dextran‐rich) phase, and the reverse was true for marker enzymes (cytochrome c oxidase, EC 1.9.3.1, and antimycin A‐resistant NADPH cytochrome c reductase) of intracellular membranes. The ATPase was highly stimulated by the addition of detergent (Triton X‐100), so that the isolated plasmalemma vesicles appear tightly sealed and in a right‐side‐out orientation. Further characterization of the ATPase activities showed a pH optimum at 6.0 in the presence of Mg2+. This optimum was shifted to pH 5.8 after addition of K+. K+ stimulated the ATPase activity below pH 6 and inhibited above pH 6. The ATPase activity was specific for ATP and sensitive to N,N‐dicyclohexylcarbodiimide and sodium vanadate, with K+ enhancing the vanadate inhibition. The enzyme was insensitive to sodium molybdate, NO−3, azide and oligomycin. No Ca2+‐ATPase was detected, and even as little as 0.05 mM Ca2+ inhibited the Mg2+‐ATPase activity.Publisher's Versio

Inositol phospholipids activate plasma membrane ATPase in plants

Phosphatidylinositol-4-monophosphate and phosphatidylinositol-4,5-bisphosphate increased the activity of the vanadate-sensitive ATPase associated with plasma membranes isolated from both sunflower hypocotyls and carrot suspension culture cells. The response was not due to the metabolism of the polyphosphoinositides since diacylglycerol, inositol-1,4-bisphosphate, inositol-1,4,5-trisphosphate, glycerophosphoinositol monophosphate and glycerophosphoinositol bisphosphate had no effect. These data suggest that activation of the inositol phospholipid kinases could be a critical step in signal transduction in plants

Expression of small GTPases in the roots and nodules of Medicago truncatula cv. Jemalong

Memon AR, Schwager CK, Niehaus K. Expression of small GTPases in the roots and nodules of Medicago truncatula cv. Jemalong. ACTA BOTANICA CROATICA. 2019;78(1):1-8.In this study we used Medicago truncatula, to identify and analyze the expression of small GTP-binding proteins (Arf1,Arl1,Sar1,Rabs, Rop/Rac) and their interacting partners in the infection process in the roots and nodules. A real-time polymerase chain reaction analysis was carried out and our results showed that Arf1(AtArfB1c-like), MtSar1, AtRabA1e-like, AtRabC1-like, MsRab11-like and AtRop7-like genes were highly expressed in the nodules of rhizobium inoculated plants compared to the non-inoculated ones. On the contrary, AtRabA3 like, AtRab5c and MsRac1-like genes were highly expressed in non-infected nitrogen supplied roots of M. truncatula. Other Rab genes (AtRabA4a, AIRabA4c and AtRabG3a-like genes) were nearly equally expressed in both treatments. Interestingly, RbohB (a respiratory burst NADPH oxidase homologue) was more highly expressed in rhizobium infected than in non-infected roots and nodules. Our data show a differential expression pattern of small GTP-binding proteins in roots and nodules of the plants. This study demonstrates an important role of small GTP-binding proteins in symbiosome biogenesis and root nodule development in legumes

Quantitative ICP-OES Determination of Trace and Essential Elements in the Plant Species of Genus Ferula

Some of the species belonging to the genus ferula are known to be used as traditional medicine for treating various diseases in South Asia, the Middle East, and in North Africa. In this study, samples from 20 varieties of plants belonging to 20 species of the genus ferula L. (Apiaceae) were collected from various regions of Turkey. After air drying, the samples were solubilized by using the microwave dissolution technique. The concentration levels of the different elements (Al, B, Ba, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Se, Sr, and Zn) were determined by ICP-OES. The accuracy of the proposed method was verified by analyzing certified reference materials SRM 1573a Tomato and INCT-TL-1 Tea Leaves. The results showed a significant variation of elemental content, especially for Al, B, Ba, and Fe amongst the fruit- and flower-bearing plants of the different plant species of the same genus. This clearly indicates that each plant species has a different absorption and accumulation capacity for different metals. Further work on the accumulation of these metals in the leaves and shoots of the plants is in progress

Abscisic acid regulated gene expression in bread wheat (Triticum aestivum L.)

The studies about the elucidation of molecular components of drought response in major crops have become an urgent priority. Since abscisic acid (ABA) is one of the major plant hormones influencing main stress responses including drought, cold, and heat, there has been overwhelming interest in investigation of ABA-associated genes. Therefore, the identification and characterization of ABA-associated genes from bread wheat is significant for gaining better insights about the multiple stress-response mechanisms. Due to the pivotal role of ABA in stress response mechanism, we tried to determine spatiotemporal expressional characteristics of ABA-related genes in wheat. The comparative differential transcript profiling experiments revealed a total of 60 differentially-regulated cDNA fragments, thirty of which were sequenced to obtain more details about their functional identities. Some of the sequenced fragments showed significant similarity with the genes known to be associated with ABA-induced signaling networks; e. g., Germin-Like Proteins, Tonoplast Intrinsic Proteins, MAP kinases and leucine-rich repeat (LRR) receptor-like proteins. To get more details about ABA-associated genes in wheat, the expressional characteristics of the transcripts from the initial screening was further investigated by using quantitative Real Time PCR. For example, the amount of transcripts MAPK4 and TIP1 homologs in leaf tissue of bread wheat is gradually increased and eventually peaked in about 2 hours after ABA treatment, and subsequently declined with the prolonged exposure. On the other hand, induction in the GLP homolog expression was much faster than the aforementioned transcripts; reaching to the apex in roughly an hour after the treatment. This study provided insights about the expressional characteristics of some ABA-associated genes from bread wheat. This is the first study investigating the early response genes under ABA-treatment in hexaploid bread wheat

Characterization of differentially expressed genes to Cu stress in Brassica nigra by Arabidopsis genome arrays

Phytoremediation is an efficient and promising cleanup technology to extract or inactivate heavy metals and several organic and inorganic pollutants from soil and water. In this study, different Brassica nigra L. ecotypes, including Diyarbakr, collected from mining areas were exposed to different concentrations of copper and harvested after 72h of Cu stress for the assessment of phytoremediation capacity. The Diyarbakr ecotype was called as metallophyte because of surviving at 500M Cu. To better understand Cu stress mechanism, ArabidopsisATH1 genome array was used to compare the gene expression in root and shoot tissues of B. nigra under 25M Cu. The response to Cu was much stronger in roots (88 genes showing increased or decreased mRNA levels) than in leaf tissues (24 responding genes). These genes were classified into the metal transport and accumulation-related genes, signal transduction and metabolism-related genes, and transport facilitation genes. Glutathione pathway-related genes (-ECS, PC, etc.) mRNAs were identified as differentially expressed in root and shoot tissues. QRT-PCR validation experiments showed that -ECS and PC expression was upregulated in the shoot and leaf tissues of the 100M Cu-subjected B. nigra-tolerant ecotype. This is the first study showing global expression profiles in response to Cu stress in B. nigra by Arabidopsis genome array. This work presented herein provides a well-illustrated insight into the global gene expression to Cu stress response in plants, and identified genes from microarray data will serve as molecular tools for the phytoremediation applications in the future