Cuticle darkening correlates with increased body copper content in Drosophila melanogaster

Abstract

Insect epidermal cells secrete a cuticle that serves as an exoskeleton providing mechanical rigidity to each individual, but also insulation, camouflage or communication within their environment. Cuticle deposition and hardening (sclerotization) and pigment synthesis are parallel processes requiring tyrosinase activity, which depends on an unidentified copperdependent enzyme component in Drosophila melanogaster. We determined the metallomes of fly strains selected for lighter or darker cuticles in a laboratory evolution experiment, asking whether any specific element changed in abundance in concert with pigment deposition. The results showed a correlation between total iron content and strength of pigmentation, which was further corroborated by ferritin iron quantification. To ask if the observed increase in iron body content along with increased pigment deposition could be generalizable, we crossed yellow and ebony alleles causing light and dark pigmentation, respectively, into similar genetic backgrounds and measured their metallomes. Iron remained unaffected in the various mutants providing no support for a causative link between pigmentation and iron content. In contrast, the combined analysis of both experiments suggested instead a correlation between pigment deposition and total copper body content, possibly due to increased demand for epidermal tyrosinase activity. Keywords Color Á Elemental analysis Á Genetic background Á Melanin Á Zinc

Mosquito metallomics reveal copper and iron as critical factors for Plasmodium infection

“…Interestingly, TEP1, LRIM1 and other immune genes were indeed expressed at higher level in the resistant bs strain, whereas melanization genes, such as PPO1, showed reduced expression [ 59 ]. The latter finding is consistent with a general tendency for degree of melanization reactions correlating with iron and copper concentrations [ 87 ], as observed here in the comparison between ws and bs phenotypes (discussed in the following paragraph). Of interest in respect to melanization is a recent discovery of a conserved transporter gene, which turns pupae of Tephritidae flies white when mutated [ 88 ].…”

“…However, it reduced copper by 43% in bs mosquitoes. The interaction between copper and iron metabolism in insects remains under investigation [ 32 – 36 , 87 ]. Since bs mosquitoes showed a lower concentration of iron and copper, the increase in susceptibility after the BPS treatment, which further lowered the concentration of these metals, may be due to a detrimental deficiency of metal ions as prosthetic groups in proteins responsible for eliminating the parasite.…”

“…Data were analyzed with one-way ANOVA followed by Tukey's test. Statistical differences between groups are indicated by different letters, and asterisks denote p values as follows: � p = 0.0370, �� p = 0.0055, ns = p>0.05. https://doi.org/10.1371/journal.pntd.0009509.g005 PLOS NEGLECTED TROPICAL DISEASES 36,87]. Since bs mosquitoes showed a lower concentration of iron and copper, the increase in susceptibility after the BPS treatment, which further lowered the concentration of these metals, may be due to a detrimental deficiency of metal ions as prosthetic groups in proteins responsible for eliminating the parasite.…”

The genomic basis of copper tolerance inDrosophilais shaped by a complex interplay of regulatory and environmental factors

“…2C). A correlation between cuticle darkening and increased body copper content has also been reported in D. melanogaster [75].…”

“…Jon65Aiv is known to be a serine protease with a likely role in digestion [74]. Serine proteases have also been shown to be down-regulated in clusters after exposure to another metal, manganese [75] and during aging [76], although the reason for this perturbation remains unresolved. As copper inhibits larval midgut acidification [14], a phenotype also seen in aging [13], it would be tempting to investigate the relationship between acidity and serine proteases directly.…”