Related Experiment Video
Updated: Jun 18, 2026
08:30
Detection of Phospholipase C Activity in the Brain Homogenate from the Honeybee
Published on: September 14, 2018
Genes encoding phospholipases A2 mediate insect nodulation reactions to bacterial challenge
Sony Shrestha1, Yoonseong Park, David Stanley
1Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
Journal of Insect Physiology
|November 26, 2009
Summary
Insect immune responses involve secretory phospholipases A(2) (sPLA(2)). Four sPLA(2) genes mediate nodulation reactions to bacterial infections in Tribolium castaneum, crucial for cellular defense.
Area of Science:
- Insect immunity
- Molecular biology
- Biochemistry
Background:
- Nodulation is a primary insect cellular defense against bacterial infection.
- Eicosanoids mediate nodulation, and their synthesis relies on phospholipase A(2) (PLA(2)) activity.
- Arachidonic acid (AA) is a key substrate for PLA(2) in eicosanoid biosynthesis.
Purpose of the Study:
- To investigate the role of secretory phospholipases A(2) (sPLA(2)) in insect nodulation responses.
- To identify specific sPLA(2) genes involved in the cellular immune defense of Tribolium castaneum.
Main Methods:
- Stimulating nodulation in Tribolium castaneum larvae with Escherichia coli.
- Using pharmaceutical inhibitors of eicosanoid biosynthesis and supplementing with arachidonic acid (AA).
- Cloning and expressing sPLA(2) genes, using RNA interference (RNAi) to reduce gene expression, and employing antibody-based detection.
Main Results:
- Bacterial infection induced nodulation and sPLA(2) activity in a dose- and time-dependent manner.
- Inhibition of eicosanoid synthesis impaired nodulation, which was rescued by AA.
- Knockdown of four out of five sPLA(2) genes significantly reduced nodulation responses, confirming their mediating role.
- sPLA(2) enzymes were found in hemocytes and localized to plasma membranes post-infection.
Conclusions:
- Expression of four specific sPLA(2) genes is essential for mediating insect nodulation responses to bacterial infection.
- sPLA(2) enzymes are central to insect cellular immunity, playing a critical role in the production of defense mediators like eicosanoids.
Related Concept Videos
01:11IP3/DAG Signaling Pathway
Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
01:28Regulation of Bacterial Virulence
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:58Cell Specific Gene Expression
Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
01:15Amplifying Signals via Second Messengers
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...