Invertebrate Survival Journal

Pathological changes in the main immune organs of silkworm infected with Staphylococcus aureus

Y Pan, P Lü, M Tang, K Chen — Wed, 31 May 2023 00:00:00 +0000

Silkworm Bombyx mori (B. mori), a lepidopteran model organism, has become an important model for molecular biology. It also offers an excellent model to study the innate immunity because of its similarity to human beings. Staphylococcus aureus (S. aureus) is a typical gram-positive pathogenic microorganism that causes serious pneumonia, meningitis, endocarditis and septicemia. In this study, silkworm was used as animal model to study the innate immune responses against the pathogenic bacterial infections. We investigated the median lethal dose (LD₅₀) of S. aureus infection in the silkworm, and the pathological changes in their hemolymph and midgut after infection. The LD₅₀ of S. aureus infecting the silkworms was 4.39 × 10⁴ colony-forming units per milliliter (CFU/mL) after 72 h. The peritrophic membrane of the silkworm showed severe damage after 36 h. Insect hemocytes can participate in various innate immune responses, such as encapsulation and nodule formation. Our results imply plasmacytes of hemocytes can adhere to and spread over S. aureus in the hemolymph and may play an important role in the resistance of the silkworms to S. aureus infection.

Induction of antioxidant and detoxifying systems of Chilo suppressalis Walker after exposure to entomopathogenic fungi

M Shahriari, A Zibaee, MF Dinan, A Armand, M Tabari, H Hoda — Thu, 02 Feb 2023 00:00:00 +0000

The current study aimed to determine antioxidant and detoxifying responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) to Beauveria bassiana (Strains BBRR1, BBAL1, BBLN1, BBLN2), Metarhizium anisopliae and Hirsutella subulata. The interactions of insect humoral immune responses with the entered conidia of entomopathogenic fungi in addition to nodule formation and melanization caused the production of several reactive oxygenate species (ROS), such as hydrogen peroxidase (H2O2), hydroperoxides (ROOH), superoxide radicals (O2−), and hydroxyl radical (OH−). The highest activity of catalase was recorded by BBRR1 and BBAL1, treatment after 48 to 96 h while the larvae treated by BBRR1 showed the highest peroxidase activity. Both ascorbate peroxidase and glucose-6-phosphate dehydrogenase showed the highest activity in the larvae treated by BBRR1 after 48-96 h. The highest concentration of Malondialdehyde reported in the larvae treated by BBRR1, BBAL1 and BBLN1, after 48 hours. The highest activity of general esterases was recorded in the larvae treated by BBRR1 after 48-96 hours. Similar results were recorded in the activity of glutathione-S-transferase but the enzyme had also the highest activity in the larvae treated by BBAL1 and BBLN2 after 48 hours. The larvae treated by BBRR1 and BBLN1 showed the highest activity of acid phosphatase after 72 and 96 hours while the highest activity of alkaline phosphatase was obtained in the larvae only treated by BBRR1 after 48-96 hours. The results clearly revealed that BBRR1 significantly and severely induced antioxidant and detoxifying systems of C. suppressalis larvae implying on virulence and immune induction of BBRR1 against the larvae.

First morpho-functional characterization of Anemonia viridis amoebocytes: a light microscopy study

J Fabrello, M Ciscato, D Asnicar, MG Marin, V Matozzo — Thu, 19 Jan 2023 00:00:00 +0000

For the first time, we studied the morpho-functional characteristics of amoebocytes of the sea anemone Anemonia viridis. A histochemical approach was adopted and two subpopulations of amoebocytes from mesoglea were observed: granulocytes and hyalinocytes. Granulocytes showed a high number of cytoplasmatic granules, while hyalinocytes had no or few granules. Amoebocytes showed both round and spreading shapes and were divided in basophil, neutrophil or acidophil cells. Amoebocytes actively phagocytized yeast cells and produced superoxide anion. The presence of hydrolytic enzymes in amoebocytes was also investigated. Positive cells to acid phosphatase, acid esterase and non-specific esterase were found, with granulocytes and hyalinocytes that did not show different responses in term of positivity. Although preliminary, the results of this study can help to understand the features and immune role of A. viridis amoebocytes and the development of defense strategies in multicellular organisms. Moreover, this study lay the foundations for future more in-depth studies, including those at the ultrastructural level.

XXIII scientific meeting of the Italian Association of Developmental and Comparative Immunology (IADCI), February 13-15, 2023, DaDoM - Darwin Dohrn Museum, Villa Comunale, Naples, Italy

MR Coscia, D Melillo, A Ametrano, R Marino, D Malagoli, MG Parisi — Mon, 08 May 2023 00:00:00 +0000