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Railroadworms luciferases emit the widest range of bioluminescence colors among beetles, ranging from green to red, being model enzymes to investigate the structure and bioluminescence colors relationships. Only three active railroadworms luciferases from the larval stage have been cloned and investigated: the Phrixothrix hirtus head lanterns red-emitting luciferase (PhRE); the Phrixothrix vivianii lateral lanterns green emitting luciferases (PvGR) and the Phengodes sp. dorsal lanterns yellow-green emitting luciferase (Ph). No active luciferase emitting in the yellow–orange region, however, has been cloned yet. Here we report the cloning and characterization of the orange emitting luciferase from the adult males of a rare Brazilian Cerrado railroadworm, Euryopa clarindae, and the transcriptional identification of two isozymes from the Amazon forest Mastinomorphus sp. railroadworm. The luciferase of E. clarindae has 548 residues, emits orange bioluminescence (600 nm), and displays intermediate kinetic values [KM(luciferin) = 50 µM, KM(ATP) ~ 170 µM] between those reported for green-emitting lateral lanterns and red emitting head lanterns luciferases. It displays 74–78% identity with the lateral lanterns luciferases of other railroadworms and 70% with the head lantern PhRE luciferase, and 96% with the larval Mastinomorphus sp. Mast-1, suggesting that this larva could be from the Euryopa genus. The phylogenetic analysis and kinetic/functional properties, place this orange-emitting enzyme as an intermediate form between the green-emitting lateral lanterns and red-emitting head lanterns luciferases. Major structural differences that could be associated with bioluminescence color determination are a relatively larger cavity size, and substitutions in the loops 223–235 and 311–316, especially N/C/T311, and their interactions which may help to close the bottom of LBS. [ABSTRACT FROM AUTHOR]

Among the richest ecosystems in bioluminescent Coleoptera in Brazil, the Cerrado (savannas) is the most threatened one by agricultural expansion. The Emas (PNE) and Chapada dos Guimarães (PNCG) National parks are 2 of the last main remnants of the original Cerrado ecosystems in Central-west Brazil. During the past 3 decades, we have conducted several expeditions to collect, observe and study bioluminescent beetles occurring in the PNE and surrounding farms. More recently we also started to investigate the PNCG. We recorded a total of 51 bioluminescent species, including fireflies (n = 29), click beetles (n = 11), phengodids (n = 10), and staphylinids (n = 1). The PNE region was the richest one, especially for phengodids (n = 9). Among the habitats that compose the Cerrado physiognomy, the Cerrado and cerradão hosted most of the bioluminescent species, followed by forest, open fields and marshes. Most fireflies inhabiting the Cerrado ecosystem emit yellow-green light, whereas most click beetles emit predominantly green light, and among phengodid species, orange and red-light emission was found in 3 species. The spectacular click beetle Pyrearinus termitilluminans Costa-lodging luminous termite mounds were found in PNE and also reported for the first time at PNCG. In the farms around the PNE, however, a declining number of bioluminescent species was recorded in cerradão areas after the replacement of the surrounding cattle pastures by sugarcane plantations, especially adult phengodid males that were no longer attracted to light traps. Habitat reduction, use of agricultural pesticides and artificial night lighting are thought to be the major causes of such impact on bioluminescent beetle diversity. [ABSTRACT FROM AUTHOR]