Publications by authors named "LL Pech"
Plasmatocytes from the moth Pseudoplusia includens induce apoptosis of granular cells.
J Insect Physiol
December 2000
Article Synopsis
- The immune system of the moth Pseudoplusia includens uses a method called encapsulation to combat internal parasites and large foreign objects, involving two key types of hemocytes: granular cells and plasmatocytes.
- Research shows that after attaching to the capsule's surface, granular cells die quickly, forming a protective layer around the capsule due to processes triggered by plasmatocytes.
- The study reveals that plasmatocytes release factors that specifically induce apoptosis (cell death) in granular cells, particularly influenced by whether the plasmatocytes and granular cells are in an adhesive or non-adhesive state, highlighting a crucial aspect of capsule formation.
Article Synopsis
- Insect blood cells, specifically plasmatocytes, are crucial for fighting off infections from parasites and other pathogens.
- Researchers identified a peptide called plasmatocyte-spreading peptide (PSP1) from the moth Pseudoplusia includens, which promotes the spreading of plasmatocytes on foreign surfaces.
- In laboratory tests, PSP1 triggered plasmatocyte spreading at specific concentrations and injection into larvae temporarily depleted hemocytes, indicating that only a specific subset of plasmatocytes responds to this peptide while other factors may be involved in adhesion.
Article Synopsis
- Haemocytes, which are immune cells in invertebrates, are crucial for defending against pathogens through a process called encapsulation.
- The study examined how different subpopulations of these cells interact during the encapsulation process in the insect Pseudoplusia includens, revealing that it involves a three-step formation with granular cells and plasmatocytes working together.
- Granular cells are essential for plasmatocytes to encapsulate foreign targets, and their involvement relies on a specific cell adhesion mechanism that can be disrupted by certain recognition sequences.
Article Synopsis
- MdPDV is a virus associated with the parasitic wasp Microplitis demolitor, which targets the larvae of the pest Pseudoplusia includens.
- Infection with MdPDV leads to the apoptosis (programmed cell death) of granular cells, crucial for the caterpillar's immune response, while plasmatocytes show altered adhesion without undergoing apoptosis.
- The mechanism suggests that MdPDV benefits from inducing cell death in immune cells, thereby increasing its chances of survival and the survival of M. demolitor eggs in the host.
Immunological basis for compatibility in parasitoid-host relationships.
Annu Rev Entomol
January 1995
Article Synopsis
- The insect immune system defends against parasitoids through a process called encapsulation, where specialized immune cells (hemocytes) form a protective barrier around the invader.
- Parasitoids have evolved various tactics to avoid or counteract this immune response, including developing in secluded areas that hemocytes cannot reach and injecting factors to disrupt the immune system.
- Polydnaviruses, associated with some parasitoid species, specifically weaken the host's immune response by killing hemocytes or altering their adhesion properties, significantly influencing host compatibility and evolution.
Separation and behavior in vitro of hemocytes from the moth, Pseudoplusia includens.
Cell Tissue Res
July 1994
Article Synopsis
- Hemocytes from Pseudoplusia includens larvae were isolated using centrifugation on Percoll cushions, achieving high purity levels for different cell types.
- Medium enriched with chicken serum improved the survival and spreading of plasmatocytes, while cell-free plasma and preconditioned medium provided even better stability and spreading properties.
- Oenocytoids were unique in exhibiting phenoloxidase activity, while plasmatocytes and granular cells demonstrated endocytosis of fluorescent beads, with plasmatocytes also capable of encapsulating larger foreign objects.
Purification and characterization of calmodulin (lysine 115) N-methyltransferase from Paramecium tetraurelia.
Biochim Biophys Acta
March 1994
Article Synopsis
- Calmodulin N-methyltransferase was successfully purified from the cytosol of Paramecium tetraurelia using a multi-step chromatography process, achieving a 6800-fold increase in purity with a yield of 15%.
- The enzyme predominantly produces mono-, di-, and trimethyllysine residues at lysine 115 of calmodulin, has a Km of 1 microM for the methyl donor S-adenosyl methionine, and requires DTT for activity, which distinguishes it from the crude enzyme fractions.
- Ca2+, Mg2+, Mn2+, and Ni2+ enhance its activity, but it is inhibited by its product S-adenosyl homocysteine and specific calmodulin antagonists
Article Synopsis
- Researchers examined cryo-fixed yeast Paramecia and sea urchin embryos using a low-temperature scanning electron microscope (LTSEM) to optimize the imaging of frozen samples.
- The study found that using low-voltage backscattered electron signals on uncoated samples allowed for sufficient resolution to view membrane structures, but higher resolution was achieved with platinum cryo-coated samples.
- The approach minimizes chemical fixation artifacts and enables the observation of additional cytoplasmic structures, making partially dehydrated samples a promising method for cell biology research.