Computational characterization of Iron metabolism in the Tsetse disease vector, Glossina morsitans: IRE stem-loops

Iron regulatory protein from the hard tick Haemaphysalis longicornis: characterization, function and assessment as a protective antigen

BACKGROUND

Ticks are blood-feeding ectoparasites with different host specificities and are capable of pathogen transmission. Iron regulatory proteins (IRPs) play crucial roles in iron homeostasis in vertebrates. However, their functions in ticks remain poorly understood. The aim of the present study was to investigate the characteristics, functions, molecular mechanisms, and the vaccine efficacy of IRP in the hard tick Haemaphysalis longicornis.

RESULTS

The full-length complementary DNA of IRP from Haemaphysalis longicornis (HlIRP) was 2973 bp, including a 2772 bp open reading frame. It is expressed throughout three developmental stages (larvae, nymphs, and adult females) and in various tissues (salivary glands, ovaries, midgut, and Malpighian tubules). Recombinant Haemaphysalis longicornis IRP (rHlIRP) was obtained via a prokaryotic expression system and exhibited aconitase, iron chelation, radical-scavenging, and hemolytic activities in vitro. RNA interference-mediated IRP knockdown reduced tick engorgement weight, ovary weight, egg mass weight, egg hatching rate, and ovary vitellin content, as well as prolonging the egg incubation period. Proteomics revealed that IRP may affect tick reproduction and development through proteasome pathway-associated, ribosomal, reproduction-related, and iron metabolism-related proteins. A trial on rabbits against adult Haemaphysalis longicornis infestation demonstrated that rHlIRP vaccine could significantly decrease engorged weight (by 10%), egg mass weight (by 16%) and eggs hatching rate (by 22%) of ticks. The overall immunization efficacy using rHlIRP against adult females was 41%.

CONCLUSION

IRP could limit reproduction and development in Haemaphysalis longicornis, and HlIRP was confirmed as a candidate vaccine antigen to impair tick iron metabolism and protect the host against tick infestation. © 2024 Society of Chemical Industry.

Ironing out the Details: Exploring the Role of Iron and Heme in Blood-Sucking Arthropods

Heme and iron are essential molecules for many physiological processes and yet have the ability to cause oxidative damage such as lipid peroxidation, protein degradation, and ultimately cell death if not controlled. Blood-sucking arthropods have evolved diverse methods to protect themselves against iron/heme-related damage, as the act of bloodfeeding itself is high risk, high reward process. Protective mechanisms in medically important arthropods include the midgut peritrophic matrix in mosquitoes, heme aggregation into the crystalline structure hemozoin in kissing bugs and hemosomes in ticks. Once heme and iron pass these protective mechanisms they are presumed to enter the midgut epithelial cells via membrane-bound transporters, though relatively few iron or heme transporters have been identified in bloodsucking arthropods. Upon iron entry into midgut epithelial cells, ferritin serves as the universal storage protein and transport for dietary iron in many organisms including arthropods. In addition to its role as a nutrient, heme is also an important signaling molecule in the midgut epithelial cells for many physiological processes including vitellogenesis. This review article will summarize recent advancements in heme/iron uptake, detoxification and exportation in bloodfeeding arthropods. While initial strides have been made at ironing out the role of dietary iron and heme in arthropods, much still remains to be discovered as these molecules may serve as novel targets for the control of many arthropod pests.

Comparative analysis of two ferritin subunits from blunt snout bream (Megalobrama amblycephala): Characterization, expression, iron depriving and bacteriostatic activity

Iron is an essential microelement for almost all living organisms, while an excess of iron is toxic, thus maintenance of iron homeostasis is vital. As iron storage protein, ferritin plays an important role in iron metabolism. In the present study, we cloned and characterized the ferritin H subunit from Megalobrama amblycephala, termed as MamFerH. An iron-responsive element (IRE) was predicted in the 5' untranslated region (UTR) of MamFerH, while its bulge structural was different from that of the reported ferritin M subunit (MamFerM). The MamFerH and MamFerM genes exhibited similar expression patterns during early development with specifically high expression post hatching, whereas their tissue expression patterns were different. Specifically, MamFerM was highly expressed in the spleen, liver and kidney, while MamFerH was predominantly expressed in the blood and brain, indicating their different functions. In addition, the expression of the two genes was induced upon Aeromonas hydrophila infection at both transcriptional and translational levels, and MamFerH was more efficient. Immunohistochemistry and immunofluorescence analysis confirmed their significant changes at protein level and distribution in the liver post infection, indicating their participation in host immune response. Furthermore, bacteriostatic experiment revealed that recombinant MamFerH displayed more significant inhibitory effect on the growth of A. hydrophila.