Structure and expression of Rhodnius prolixus GH18 chitinases and chitinase-like proteins: Characterization of the physiological role of RpCht7, a gene from subgroup VIII, in vector fitness and reproduction

Abstract

Chitinases are enzymes responsible for the hydrolysis of glycosidic linkages within chitin chains. In insects, chitinases are typically members of the multigenic glycoside hydrolase family 18 (GH18). They participate in the relocation of chitin during development and molt, and in digestion in detritivores and predatory insects, and they control the peritrophic membrane thickness. Chitin metabolism is a promising target for developing vector control strategies, and knowledge of the roles of chitinases may reveal new targets and illuminate unique aspects of their physiology and interaction with microorganisms. Rhodnius prolixus is an important vector of Chagas disease, which is caused by the parasite Trypanosoma cruzi. In this study, we performed annotation and structural characterization of nine chitinase and chitinase-like protein genes in the R. prolixus genome. The roles of their corresponding transcripts were studied in more depth; their physiological roles were studied through RNAi silencing. Phylogenetic analysis of coding sequences showed that these genes belong to different subfamilies of GH18 chitinases already described in other insects. The expression patterns of these genes in different tissues and developmental stages were initially characterized using RT-PCR. RNAi screening showed silencing of the gene family members with very different efficiencies. Based on the knockdown results and the general lack of information about subgroup VIII of GH18, the RpCht7 gene was chosen for phenotype analysis. RpCht7 knockdown doubled the mortality in starving fifth-instar nymphs compared to dsGFP-injected controls. However, it did not alter blood intake, diuresis, digestion, molting rate, molting defects, sexual ratio, percentage of hatching, or average hatching time. Nevertheless, female oviposition was reduced by 53% in RpCht7-silenced insects, and differences in oviposition occurred within 14–20 days after a saturating blood meal. These results suggest that RpCht7 may be involved in the reproductive physiology and vector fitness of R. prolixus.

Digestive α-L-fucosidase activity in Rhodnius prolixus after blood feeding: effect of secretagogue and nutritional stimuli

“…The use of this strategy in works characterizing the production of R. prolixus midgut enzymes after blood feeding is of special interest. This system was used successfully to describe the production pattern of glycosidases ( Ribeiro and Pereira, 1984 ; Gama et al, 2022 ) and proteases ( Henriques et al, 2021 ), but because these works fed the insect only with whole blood, no reference to hemolysis was made. In a particular work, R. prolixus was fed with whole defibrinated blood, its plasma and cell fractions were diluted with PBS, and a secretatogue pattern of stimulation was demonstrated by their dilutions, with no reference to hemolysis ( Garcia and Garcia, 1977 ).…”

Function analysis and characterisation of a novel chitinase, MdCht9, in Musca domestica

“…Individual chitinases are expressed differently at different developmental stages and in different tissues (Arakane & Muthukrishnan, 2010; Merzendorfer, 2013). According to a recent study, eight chitinase genes in the deutonymph of Tetranychus urticae and nine chitinase genes from Rhodnius prolixus showed personalised expression patterns during various stages of development (Li et al, 2021; Gama et al, 2022).…”