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

NH4+-stimulated and -inhibited components of K+ transport in rice (Oryza sativa L.)

The disruption of K+ transport and accumulation is symptomatic of NH4+ toxicity in plants. In this study, the influence of K+ supply (0.02–40 mM) and nitrogen source (10 mM NH4+ or NO3–) on root plasma membrane K+ fluxes and cytosolic K+ pools, plant growth, and whole-plant K+ distribution in the NH4+-tolerant plant species rice (Oryza sativa L.) was examined. Using the radiotracer 42K+, tissue mineral analysis, and growth data, it is shown that rice is affected by NH4+ toxicity under high-affinity K+ transport conditions. Substantial recovery of growth was seen as [K+]ext was increased from 0.02 mM to 0.1 mM, and, at 1.5 mM, growth was superior on NH4+. Growth recovery at these concentrations was accompanied by greater influx of K+ into root cells, translocation of K+ to the shoot, and tissue K+. Elevating the K+ supply also resulted in a significant reduction of NH4+ influx, as measured by 13N radiotracing. In the low-affinity K+ transport range, NH4+ stimulated K+ influx relative to NO3– controls. It is concluded that rice, despite its well-known tolerance to NH4+, nevertheless displays considerable growth suppression and disruption of K+ homeostasis under this N regime at low [K+]ext, but displays efficient recovery from NH4+ inhibition, and indeed a stimulation of K+ acquisition, when [K+]ext is increased in the presence of NH4+

Non-reciprocal interactions between K+ and Na+ ions in barley (Hordeum vulgare L.)

The interaction of sodium and potassium ions in the context of the primary entry of Na+ into plant cells, and the subsequent development of sodium toxicity, has been the subject of much recent attention. In the present study, the technique of compartmental analysis with the radiotracers 42K+ and 24Na+ was applied in intact seedlings of barley (Hordeum vulgare L.) to test the hypothesis that elevated levels of K+ in the growth medium will reduce both rapid, futile Na+ cycling at the plasma membrane, and Na+ build-up in the cytosol of root cells, under saline conditions (100 mM NaCl). We reject this hypothesis, showing that, over a wide (400-fold) range of K+ supply, K+ neither reduces the primary fluxes of Na+ at the root plasma membrane nor suppresses Na+ accumulation in the cytosol. By contrast, 100 mM NaCl suppressed the cytosolic K+ pool by 47–73%, and also substantially decreased low-affinity K+ transport across the plasma membrane. We confirm that the cytosolic [K+]:[Na+] ratio is a poor predictor of growth performance under saline conditions, while a good correlation is seen between growth and the tissue ratios of the two ions. The data provide insight into the mechanisms that mediate the toxic influx of sodium across the root plasma membrane under salinity stress, demonstrating that, in the glycophyte barley, K+ and Na+ are unlikely to share a common low-affinity pathway for entry into the plant cell

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

THE INVESTIGATION OF OIL DEGRADING CAPACITY OF BACTERIAL STRAINS ISOLATED FROM DIFFERENT ENVIRONMENTS IN TURKEY

The analyses were carried out with the aim of determining the oil-degradation capacity of bacterial strains isolated from different locations in Turkey. A total of 103 wild bacterial strains isolated from different marine environments and from the soil surrounding petroleum refineries in the city of Batman, Turkey, were screened with respect to their MIC (Minimum Inhibition Concentration) in Batman crude oil. Five bacterial isolates and their mixed consortiums were selected and investigated to detect their degradation capabilities with respect to different parameters including hemolytic activities, pH values, the emulsification index and the oil layers' thickness during the 30 days of incubation. The growth profiles of the isolates in the media with and without crude oil were also studied. In order to better understand the oil degradation capacity of the isolates, their performance was compared with the standard oil degrading bacterial strains, Alcanivorax borkumensis and Vibrio cyclitrophicus. The degradation activities of all of the five strains (Escherichia coli MDK04, Bacillus subtilis BR02, Vibrio fluvialis MD03, Staphylococcus haemolyticus GA01, and Pseudomonas aeruginosa BR03) and their consortiums were better than the reference strains. The experimental results indicated that the isolates from this study were efficient in using crude oil as the sole source of carbon and energy. We suggest that natural bacteria isolates from oil-polluted areas are likely to be as suitable candidates as standard oil-degrading bacterial strains for the purpose of cleaning up oil spills. This study significantly contributed to our knowledge about the possibility of the use of natural bacterial isolates in situ bioremediation of crude oil spills

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