scholarly journals Active defense mechanisms of thorny catfish

2020 ◽  
Vol 38 ◽  
pp. 35-48 ◽  
Author(s):  
Haocheng Quan ◽  
Wen Yang ◽  
Zixiang Tang ◽  
Robert O. Ritchie ◽  
Marc A. Meyers
Keyword(s):  
Defense Mechanisms ◽  
Active Defense

scholarly journals Molecular Identification of a Sexual Interloper: The Pear Pathogen, Venturia pirina, has Sex on Apple

2001 ◽  
Vol 91 (7) ◽  
pp. 633-641 ◽  
Author(s):  
Christiane Stehmann ◽  
Shaun Pennycook ◽  
Kim M. Plummer
Keyword(s):  
Defense Mechanisms ◽  
Apple Scab ◽  
Fruit Trees ◽  
First Record ◽  
Morphological Characters ◽  
Active Defense ◽  
Apple Leaves ◽  
Venturia Pirina ◽  
Species Specific ◽  
Polymerase Chain Reaction Primers

Venturia pirina (the pear scab pathogen) and V. inaequalis (the apple scab pathogen) were detected as ascospores discharged from apple leaf litter in New Zealand (spring 1998). Pseudothecia of both species were located on dead apple leaves; however, only those of V. inaequalis were associated with scab lesions. V. pirina was identified by rDNA sequence analyses, because morphological characters could not distinguish this fungus from V. asperata (a rare saprophyte on apple) and other Venturia spp. pathogenic on rosaceous fruit trees. Species-specific polymerase chain reaction primers designed to the 18S end of the internal transcribed spacer 1 region differentiated Venturia fruit tree pathogens reliably. V. pirina field isolates were pathogenic on pear, but only weak saprophytes on apple. In rare instances, when appressoria of V. pirina appeared to penetrate the cuticle of apple leaves, epidermal cells responded with a localized hypersensitive response (HR). To our knowledge, this is the first report of induction of HR-like events by V. pirina on its nonhost, apple, and also the first record of sexual reproduction of V. pirina on apple. It is assumed that V. pirina pseudothecia formed from saprophytic lesions in senescing apple leaves when active defense mechanisms such as HR were no longer induced.

scholarly journals Defense responses of sunflower plants to the fungal pathogen attack

Biljni lekar ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 510-521
Author(s):  
Slobodan Krsmanović ◽  
Kristina Petrović ◽  
Boško Dedić ◽  
Ferenc Bagi ◽  
Vera Stojšin ◽  
...  
Keyword(s):  
Defense Mechanisms ◽  
Fungal Pathogens ◽  
Plant Protection ◽  
Induced Defense ◽  
Research Work ◽  
Defense Responses ◽  
Phytopathogenic Fungi ◽  
Active Defense ◽  
Expression Of Genes ◽  
The Republic

Sunflower plants show pronounced allelopathic traits and represent a suitable base for potential scientific research work. Understanding and exploiting precisely of that potential could greatly reduce the use of chemical products for plant protection that are intensively used in the production technology of this crop. Today, a big effort is made in sunflower breeding in order to produce the resistance to the economically most important pathogens, which are in most cases phytopathogenic fungi and parasitic weeds such as broomrape. Since sunflower is an increasingly popular crop within farmer fields in the Republic of Serbia, an overview of so far known, passive and active defense mechanisms, that are key for the crop resistance creating, is given. The study also describes in detail, the interactions among the most harmful fungal pathogens and sunflower plants, the expression of genes caused by their attack, and the production of metabolites that are crucial for the induced defense formation.

A Balanced View of Plant Defenses Active Defense Mechanisms in Plants R. K. S. Wood

BioScience ◽  
1983 ◽  
Vol 33 (4) ◽  
pp. 281-281
Author(s):  
Merritt R. Nelson
Keyword(s):  
Defense Mechanisms ◽  
Plant Defenses ◽  
Active Defense

scholarly journals Organ-Specificity in a Plant Disease Is Determined Independently of R Gene Signaling

2003 ◽  
Vol 16 (9) ◽  
pp. 752-759 ◽  
Author(s):  
Monika Hermanns ◽  
Alan J. Slusarenko ◽  
Nikolaus L. Schlaich
Keyword(s):  
Defense Mechanisms ◽  
Plant Diseases ◽  
Avirulence Gene ◽  
Organ Specificity ◽  
Dependent Manner ◽  
R Gene ◽  
Hypersensitive Cell Death ◽  
Active Defense ◽  
Hyaloperonospora Parasitica ◽  
Polymerase Chain

The molecular basis of organ specificity in plant diseases is little characterized. Downy mildew of Arabidopsis caused by the oomycete Hyaloperonospora parasitica (formerly Peronospora parasitica) is characteristically a leaf disease. Resistant host genotypes recognize the pathogen in a gene-for-gene dependent manner and respond with the production of H2O2 and the execution of a genetically programmed hypersensitive cell death (HR). We inoculated the roots of Arabidopsis genotypes Col-0, Ws-0, and Wei-0 with the NOCO and WELA races of the pathogen and compared the responses with those observed in leaves. Combinations of incompatible genotypes of host and pathogen showed the expected responses of an oxidative burst and the HR in leaves, but surprisingly, roots showed no signs of active defense and appeared completely susceptible to all the H. parasitica isolates tested. Reverse transcrip tase-polymerase chain reaction showed that the R gene RPP1, which mediates resistance in leaves of accession Ws-0 to the H. parasitica isolate NOCO, was expressed in leaves as well as in roots. Similarly, NDR1 and EDS1, two components of R gene-mediated signaling pathways, are also expressed in both tissues. To our knowledge, it has not been previously demonstrated that expression of R genes and downstream components of the signaling cascade are not sufficient for the induction of avirulence gene-mediated defense mechanisms in roots.

scholarly journals Study of the contribution of active defense mechanisms to ciprofloxacin tolerance in Escherichia coli growing at different rates

2022 ◽  
Author(s):  
Galina V. Smirnova ◽  
Aleksey V. Tyulenev ◽  
Nadezda G. Muzyka ◽  
Oleg N. Oktyabrsky
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanisms ◽  
Active Defense

scholarly journals Study of the Contribution of Active Defense Mechanisms to Ciprofloxacin Tolerance in Escherichia Coli Growing at Different Rates

2021 ◽  
Author(s):  
Galina Smirnova ◽  
Aleksey V. Tyulenev ◽  
Nadezda G. Muzyka ◽  
Oleg N. Oktyabrsky
Keyword(s):  
Growth Rate ◽  
Membrane Potential ◽  
Growth Rates ◽  
Defense Mechanisms ◽  
Late Phase ◽  
Sos Response ◽  
Initial Growth ◽  
Antioxidant Genes ◽  
E Coli ◽  
Active Defense

Abstract Using rpoS, tolC, ompF, and recA knockouts, we investigated their effect on the physiological response and lethality of ciprofloxacin in E. coli growing at different rates on glucose, succinate or acetate. We have shown that, regardless of the strain, the degree of changes in respiration, membrane potential, NAD/NADH ratio, ATP and glutathione (GSH) strongly depends on the initial growth rate and the degree of its inhibition. The deletion of the regulator of the general stress response RpoS, although it influenced the expression of antioxidant genes, did not significantly affect the tolerance to ciprofloxacin at all growth rates. The mutant lacking TolC, which is a component of many E. coli efflux pumps, showed the same sensitivity to ciprofloxacin as the parent. The absence of porin OmpF slowed down the entry of ciprofloxacin into cells, prolonged growth and shifted the optimal bactericidal concentration towards higher values. Deficiency of RecA, a regulator of the SOS response, dramatically altered the late phase of the SOS response (SOS-dependent cell death), preventing respiratory inhibition and a drop in membrane potential. The recA mutation inverted GSH fluxes across the membrane and abolished ciprofloxacin-induced H2S production. At all growth rates, this mutation reduced logCFU ml-1 by about 3 orders of magnitude. All studied mutants showed an inverse linear relationship between logCFU ml-1 and the specific growth rate, that is, the activity of antibiotic targets. Mutations shifted the plot of this dependence relative to the parental strain according to their significance for ciprofloxacin tolerance.

New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

1981 ◽  
Vol 39 ◽  
pp. 624-625
Author(s):  
J.L. Carson ◽  
A.M. Collier
Keyword(s):  
Respiratory Tract ◽  
Airway Epithelium ◽  
Defense Mechanisms ◽  
Normal Growth ◽  
Fetal Lung ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Ciliated Cells ◽  
Conducting Airway ◽  
Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

Parasite defense mechanisms in bees: behavior, immunity, antimicrobials, and symbionts

2019 ◽  
Vol 4 (1) ◽  
pp. 59-76 ◽  
Author(s):  
Alison E. Fowler ◽  
Rebecca E. Irwin ◽  
Lynn S. Adler
Keyword(s):  
Defense Mechanisms ◽  
Poor Quality ◽  
Future Research ◽  
Immune Priming ◽  
Social Bees ◽  
Bee Health ◽  
Landscape Scales ◽  
And Function ◽  
Solitary Species

Parasites are linked to the decline of some bee populations; thus, understanding defense mechanisms has important implications for bee health. Recent advances have improved our understanding of factors mediating bee health ranging from molecular to landscape scales, but often as disparate literatures. Here, we bring together these fields and summarize our current understanding of bee defense mechanisms including immunity, immunization, and transgenerational immune priming in social and solitary species. Additionally, the characterization of microbial diversity and function in some bee taxa has shed light on the importance of microbes for bee health, but we lack information that links microbial communities to parasite infection in most bee species. Studies are beginning to identify how bee defense mechanisms are affected by stressors such as poor-quality diets and pesticides, but further research on this topic is needed. We discuss how integrating research on host traits, microbial partners, and nutrition, as well as improving our knowledge base on wild and semi-social bees, will help inform future research, conservation efforts, and management.

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