scholarly journals Effects of the Fungal Bioherbicide, Alternaria cassia on Peroxidase, Pectinolytic and Proteolytic Activities in Sicklepod Seedlings

2021 ◽  
Vol 7 (12) ◽  
pp. 1032
Author(s):  
Robert E. Hoagland ◽  
Clyde Douglas Boyette
Keyword(s):  
Plant Defense ◽  
Weed Control ◽  
Proteolytic Activity ◽  
Time Course ◽  
Plant Pathogens ◽  
Fold Increase ◽  
Biological Weed Control ◽  
Aminopeptidase Activity ◽  
Control Tissue ◽  
Pectinase Activity

Certain plant pathogens have demonstrated potential for use as bioherbicides for weed control, and numerous studies have been published on this subject for several decades. One of the early examples of an important fungal bioherbicide is Alternaria cassiae, isolated from the weed sicklepod (Senna obtusifolia). To gain further insight into biochemical interactions of this fungus and its host weed, we examined the effects of this bioherbicide on various enzymes associated with plant defense. Young sicklepod seedlings were challenged with A. cassiae spore inoculum and enzyme activities associated with plant defense (peroxidase, proteolytic, and pectinolytic) were assayed periodically over a 96-h time course on plants grown in continuous darkness or continuous light. Peroxidase activity increased with time in untreated control seedlings in both light and dark, but the effect was greater in the light. In A. cassiae-treated plants, peroxidase was elevated above that in control tissue at all sample times resulting in a 1.5 -fold increase above control in light-grown tissue and a 2- to 3-fold increase in dark-grown tissue over 48–96 h. Differences in leucine aminopeptidase activity in control versus A. cassiae-treated tissues were not significant until 48–96 h, when activity was inhibited in fungus-treated tissues by about 32% in light-grown tissue and 27% in dark-grown tissue after 96 h. Proteolytic activity on benzoyl-arginine-p-nitroanilide was not significantly different in treated versus control tissue in either light or dark over the time course. Pectinase activity increased in treated tissues at all time points as early as 16 h after spore application in light- or dark-grown plants. The greatest increases were 1.5-fold above control levels in light-grown plants (40–64 h) and 2-fold in plants grown in darkness (72–96 h). Data suggests that peroxidase may be involved as defense mechanism of sicklepod when challenged by A. cassia and that this mechanism is operative in young seedlings under both light and dark growth conditions. Differential proteolytic activity responses on these two substrates suggests the presence of two different enzymes. Increased pectinase activity during pathogenesis suggests that A. cassiae-sicklepod interaction results in an infectivity mechanism to degrade pectic polymers important to sicklepod cell wall integrity. These studies provide important information on some biochemical interactions that may be useful for improvements to biological weed control programs utilizing plant pathogens. Such information may also be useful in genetic selection and manipulation of pathogens for weed control.

THE SUCCESS OF THE LUCERNE MESSAGE IN MARLBOROUGH

1981 ◽  
pp. 179-183
Author(s):  
A.J. Cresswell
Keyword(s):  
North America ◽  
Weed Control ◽  
Seed Yield ◽  
Insect Pest ◽  
Fold Increase ◽  
Plant Spacing ◽  
Insect Pest Control ◽  
One Year ◽  
Seed Yields ◽  
New Cultivars

This paper, as well as being a testimonial to the benefit the writer has received from the Grassland Association, shows how the knowledge of scientists has been used to increase lucerne seed yields by methods of growing resistant cultivars especially for seed production as opposed to growing for hay, silage or grazing. It shows how new cultivars can be multiplied quickly by growing two crops in one year, one in each hemisphere, by using low seeding rates, wide plant spacing and very good weed control. Increased flowering of the crop has been achieved by the use of boron and the choice of time of closing; better pollination has been achieved by the use of more efficient bees - two varieties of which have been imported from North America. Weed and insect pest control and the use of a desiccant at harvest are contributing to a four-fold increase in seed yield, which should double again soon,

scholarly journals The transcription factor OpWRKY2 positively regulates the biosynthesis of the anticancer drug camptothecin in Ophiorrhiza pumila

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaolong Hao ◽  
Chenhong Xie ◽  
Qingyan Ruan ◽  
Xichen Zhang ◽  
Chao Wu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Anticancer Activity ◽  
Time Course ◽  
Indole Alkaloid ◽  
Fold Increase ◽  
Wrky Transcription Factor ◽  
Mobility Shift ◽  
Pathway Gene ◽  
Low Concentrations ◽  
Encoding Gene

AbstractThe limited bioavailability of plant-derived natural products with anticancer activity poses major challenges to the pharmaceutical industry. An example of this is camptothecin, a monoterpene indole alkaloid with potent anticancer activity that is extracted at very low concentrations from woody plants. Recently, camptothecin biosynthesis has been shown to become biotechnologically amenable in hairy-root systems of the natural producer Ophiorrhiza pumila. Here, time-course expression and metabolite analyses were performed to identify novel transcriptional regulators of camptothecin biosynthesis in O. pumila. It is shown here that camptothecin production increased over cultivation time and that the expression pattern of the WRKY transcription factor encoding gene OpWRKY2 is closely correlated with camptothecin accumulation. Overexpression of OpWRKY2 led to a more than three-fold increase in camptothecin levels. Accordingly, silencing of OpWRKY2 correlated with decreased camptothecin levels in the plant. Further detailed molecular characterization by electrophoretic mobility shift, yeast one-hybrid and dual-luciferase assays showed that OpWRKY2 directly binds and activates the central camptothecin pathway gene OpTDC. Taken together, the results of this study demonstrate that OpWRKY2 acts as a direct positive regulator of camptothecin biosynthesis. As such, a feasible strategy for the over-accumulation of camptothecin in a biotechnologically amenable system is presented.

scholarly journals Amplification of the thapsigargin-evoked increase in the cytosolic free Ca2+ concentration by acetylcholine in acutely isolated mouse submandibular acinar cells

1996 ◽  
Vol 317 (3) ◽  
pp. 779-783 ◽  
Author(s):  
Peter. M. SMITH ◽  
Helen. E. REED
Keyword(s):  
Plasma Membrane ◽  
Time Course ◽  
Acinar Cells ◽  
Fold Increase ◽  
Extrusion Process ◽  
Significant Alteration ◽  
Atpase Inhibitor ◽  
Fura 2

The intracellular Ca2+ concentration was measured in single, acutely isolated, mouse submandibular acinar cells loaded with fura-2 AM. All experiments were performed in the absence of extracellular Ca2+ in order to eliminate Ca2+ influx. The microsomal ATPase inhibitor, thapsigargin, was used to release Ca2+ from intracellular stores and simultaneously prevent re-uptake into the stores. Sequential application of thapsigargin (2 μM) and the Ca2+ ionophore ionomycin (500 nM) indicated that thapsigargin was able to mobilize practically all intracellular Ca2+. Furthermore, in comparison with results obtained following inhibition of the plasma membrane Ca2+-ATPase by La3+ (2 mM), it may be shown that slowly unloading the intracellular Ca2+ stores using thapsigargin does not normally cause a massive, cytotoxic, increase in the cytosolic Ca2+ concentration, because Ca2+ is rapidly extruded from the cell across the plasma membrane. Application of a submaximal dose of acetylcholine (500 nM) during the rising phase of the response to thapsigargin caused a 3–4-fold increase in the amplitude of the rise in the cytosolic Ca2+ concentration without any significant alteration of the time course of the response. As thapsigargin alone is capable of mobilizing all releasable Ca2+, this increase in amplitude is most likely the result of inhibition of the Ca2+ extrusion process by acetylcholine.

Abstract 1770: Proteasome Switching is Associated with Adverse Cardiac Remodeling in a Transgenic Mouse Model of Sustained Inflammatory Signaling

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Wei Wang ◽  
Gabor Szalai ◽  
Natarajan Sivasubramanian ◽  
Douglas L Mann
Keyword(s):  
Proteolytic Activity ◽  
Cardiac Remodeling ◽  
Fold Increase ◽  
Left Ventricular ◽  
26S Proteasome ◽  
Myocardial Inflammation ◽  
Fluorescent Substrate ◽  
Lv Remodeling ◽  
Apoptotic Proteins

The 26S proteasome possess proteolytic activity and deubiquitinating (DUB) activity of ubiquitin tagged proteins. Whereas the proteolytic activity of the 26S proteasome facilitates protein degradation, proteasome DUB activity spares proteins from degradation by shortening the length of the ubiquitin chains, thereby preventing proteins from being degraded by the 26S proteasome. In yeast, increased DUB activity is beneficial by preventing depletion of ubiquitin pools critical for cell signaling. However, the role of DUB activity in mammalian systems is not known. We have shown that mice with cardiac restricted overexpression of tumor necrosis factor (sTNF mice) develop a heart failure phenotype characterized by progressive left ventricular (LV) remodeling and accumulation of pro-apoptotic proteins, including Smac/Diablo. To determine whether the adverse LV remodeling in sTNF mice was related to alterations in DUB activity we measured the cleavage of ubiquitin-AMC, an in vitro fluorescent substrate for DUBs, in purified preparations of the 26S proteasome obtained from hearts of 4 week old sTNF and littermate (LM) control mice. Compared to LM controls we observed a significant (p < 0.001) 60.8% decrease in activity of the 26S proteasome and a significant (p < 0.01) 24.2% increase in DUB activity in sTNF mouse hearts. There was also a significant (p < 0.01) 11-fold increase myocardial protein levels of USP14, a critical DUB associated with the 26S proteasome in sTNF mouse hearts. The decrease in 26S proteasome activity and increased DUB activity in sTNF mouse hearts was accompanied by an increase in myocardial levels of ubiquitinated SMAC/Diablo. Taken together these results show for the first time that sustained myocardial inflammation leads to switch in the function of the proteasome from a proteolytic function to a protein sparing function. Although this “proteasome switching” may provide a short-term adaptive benefit by preventing depletion of critical ubiquitin pools, it may lead to long-term maladaptive consequences by allowing the progressive accumulation of potentially harmful pro-apoptotic proteins in the cytosol, which may in turn promote programmed cell death and adverse cardiac remodeling.

scholarly journals Overexpression of Plasmodium falciparum M1 Aminopeptidase Promotes an Increase in Intracellular Proteolysis and Modifies the Asexual Erythrocytic Cycle Development

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1452
Author(s):  
Carolina C. Hoff ◽  
Mauro F. Azevedo ◽  
Adriana B. Thurler ◽  
Sarah El Chamy Maluf ◽  
Pollyana M. S. Melo ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Fold Increase ◽  
Cysteine Proteases ◽  
Aminopeptidase Activity ◽  
Lower Sensitivity ◽  
Wild Type ◽  
Erythrocytic Cycle ◽  
Transgenic Parasite

Plasmodium falciparum, the most virulent of the human malaria parasite, is responsible for high mortality rates worldwide. We studied the M1 alanyl-aminopeptidase of this protozoan (PfA-M1), which is involved in the final stages of hemoglobin cleavage, an essential process for parasite survival. Aiming to help in the rational development of drugs against this target, we developed a new strain of P. falciparum overexpressing PfA-M1 without the signal peptide (overPfA-M1). The overPfA-M1 parasites showed a 2.5-fold increase in proteolytic activity toward the fluorogenic substrate alanyl-7-amido-4-methylcoumarin, in relation to the wild-type group. Inhibition studies showed that overPfA-M1 presented a lower sensitivity against the metalloaminopeptidase inhibitor bestatin and to other recombinant PfA-M1 inhibitors, in comparison with the wild-type strain, indicating that PfA-M1 is a target for the in vitro antimalarial activity of these compounds. Moreover, overPfA-M1 parasites present a decreased in vitro growth, showing a reduced number of merozoites per schizont, and also a decrease in the iRBC area occupied by the parasite in trophozoite and schizont forms when compared to the controls. Interestingly, the transgenic parasite displays an increase in the aminopeptidase activity toward Met-, Ala-, Leu- and Arg-7-amido-4-methylcoumarin. We also investigated the potential role of calmodulin and cysteine proteases in PfA-M1 activity. Taken together, our data show that the overexpression of PfA-M1 in the parasite cytosol can be a suitable tool for the screening of antimalarials in specific high-throughput assays and may be used for the identification of intracellular molecular partners that modulate their activity in P. falciparum.

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