PRODUCTIVE BEHAVIOR OF Dactylopius coccus Costa ON TWO CONFINED Opuntia ficus-indica (L.) Mill CULTIVARS

Recently, the commercial breeding of Dactylopius coccus in confined environments has been developed not to depend on seasonal production and ensure the supply chain. Previous studies have shown the technical viability of their breeding of i Opuntia in a repository also called "Nopaloteca". However, considering the genetic diversity of Opuntia in each region, it is necessary to evaluate alternative cultivars to maximize the efficiency of that production system. The evaluated cultivars were Esmeralda and Villanueva (Opuntia ficus-indica (L.) Mill.). Four height levels (m) within the “Nopaloteca” (N1: 0.5; N2: 1.0; N3: 1.5 and N4: 2.0) and two harvest indices (pre and post oviposition) were evaluated regarding their effects on the carminic acid concentration (CAC, %) and fresh weight (FW, g) of D. Coccus. The results showed no significant difference in the CAC of the D. coccus colonies in both cultivars (18 %); however, the highest FW was reached in the cv. Esmeralda with 6.3 g per cladode (p ≤ 0.05). The highest CAC was found in the N4 treatment (2.0 m) with 18.6 % (p ≤ 0.05); while the highest average FW values (p ≤ 0.05) were in the intermediate levels of the N2 (1.0 m) and N3 (1.5 m) treatments, with 6.4 and 6.1 g per cladode, each. The post oviposition phase harvest of D. coccus resulted in a higher CAC concentration (20.4 %); meanwhile, in the pre-oviposition phase, 15.6 % was harvested (p ≤ 0.05). Due to the productivity and quality obtained, the Esmeralda cultivar could be used as an alternative host for the intensive breeding of D. coccus in confinement, in north-central Mexico.

FAD-dependent C-glycoside–metabolizing enzymes in microorganisms: Screening, characterization, and crystal structure analysis

C-glycosides have a unique structure, in which an anomeric carbon of a sugar is directly bonded to the carbon of an aglycone skeleton. One of the natural C-glycosides, carminic acid, is utilized by the food, cosmetic, and pharmaceutical industries, for a total of more than 200 tons/y worldwide. However, a metabolic pathway of carminic acid has never been identified. In this study, we isolated the previously unknown carminic acid-catabolizing microorganism and discovered a flavoenzyme “C-glycoside 3-oxidase” named CarA that catalyzes oxidation of the sugar moiety of carminic acid. A Basic Local Alignment Search Tool (BLAST) search demonstrated that CarA homologs were distributed in soil microorganisms but not intestinal ones. In addition to CarA, two CarA homologs were cloned and heterologously expressed, and their biochemical properties were determined. Furthermore, a crystal structure of one homolog was determined. Together with the biochemical analysis, the crystal structure and a mutagenesis analysis of CarA revealed the mechanisms underlying their substrate specificity and catalytic reaction. Our study suggests that CarA and its homologs play a crucial role in the metabolism of C-glycosides in nature.

Colors and dyes of archaeological textiles from Tarapacá in the Atacama Desert (South Central Andes)

This work concerns the study of colors and dyes identified on archaeological textiles from the Atacama Desert. The different garments and ornaments come from the excavation of two important pre-Columbian cemeteries of the Tarapacá region: Tarapacá-40 attributed to the Formative period (1100 BC–660 AD) and Pica-8 to the Late Intermediate period (900–1450 AD). For the first time, a multi-analytical approach with non-invasive techniques using FORS and SERS was applied on samples of less than 2 cm of length for physicochemical characterization of the raw materials and the dyes employed in the textile production of northern Chile. The fibers are from animal origin. Blue, green, and yellow are identified as indigo, but we cannot discard a mixture with other dyes to vary hue and shade; while carminic acid and alizarin—to a lesser extent—are found on red, orange, and brown samples. This research provides new elements for the discussion about the textile technology developed in this desertic region, its changes, and continuities along the history. Our results are compared to recent findings on neighboring regions from South-Central Andes, to improve the current knowledge and discuss the existence of dyeing textile cultural traditions.

Disposable Electrochemical Sensor for Food Colorants Detection by Reduced Graphene Oxide and Methionine Film Modified Screen Printed Carbon Electrode

A facile synthesis of reduced graphene oxide (rGO) and methionine film modified screen printed carbon electrode (rGO-methionine/SPCE) was proposed as a disposable sensor for determination of food colorants including amaranth, tartrazine, sunset yellow, and carminic acid. The fabrication process can be achieved in only 2 steps including drop-casting of rGO and electropolymerization of poly(L-methionine) film on SPCE. Surface morphology of modified electrode was studied by scanning electron microscopy (SEM). This work showed a successfully developed novel disposable sensor for detection of all 4 dyes as food colorants. The electrochemical behavior of all 4 food colorants were investigated on modified electrodes. The rGO-methionine/SPCE significantly enhanced catalytic activity of all 4 dyes. The pH value and accumulation time were optimized to obtain optimal condition of each colorant. Differential pulse voltammetry (DPV) was used for determination, and two linear detection ranges were observed for each dye. Linear detection ranges were found from 1 to 10 and 10 to 100 µM for amaranth, 1 to 10 and 10 to 85 µM for tartrazine, 1 to 10 and 10 to 50 µM for sunset yellow, and 1 to 20 and 20 to 60 µM for carminic acid. The limit of detection (LOD) was calculated at 57, 41, 48, and 36 nM for amaranth, tartrazine, sunset yellow, and carminic acid, respectively. In addition, the modified sensor also demonstrated high tolerance to interference substances, good repeatability, and high performance for real sample analysis.

Bacteria associated with the intestinal tract of three predators of Dactylopius opuntiae (Hemiptera: Dactylopiidae)

Insects depend on gut bacteria for many metabolic functions including detoxification. Dactylopius (Hemiptera: Dactylopiidae) species (e.g. D. opuntiae and D. coccus) produce carminic acid possibly acting as part of their immune response to predation; thus predators of Dactylopius species may require intestinal symbionts to metabolize carminic acid acquired from their prey. The average content of carminic acid in D. opuntiae and D. coccus is 3–5% and 19–25% respectively; the predators Leucopina bellula and Hyperaspis trifurcata are specialists on D. opuntiae while Laetilia coccidivora feeds on both D. opuntiae and D. coccus. We determined the diversity of bacteria associated with the gut of these predators to test the hypothesis that it would vary significantly depending on the level of prey specialism. Bacteria were isolated from the intestine of Le. bellula, L. coccidivora and H. trifurcata larvae and also adults of H. trifurcata. Bacteria were identified morphologically and by partial sequencing of the 16S rRNA gene. The greatest bacterial diversity was found in L. coccidivora and H. trifurcata adults, followed by H. trifurcata larvae. The lowest diversity was found in Le. bellula. Sequencing revealed the presence of Bacillus cereus, Enterococcus gallinarum and E. casseliflavus in L. coccidivora larvae; Enterobacter sp. in larvae of H. trifurcata; Lactococcus lactis in adults of H. trifurcate; and Staphylococcus sp. in larvae and adults of H. trifurcate. Bacillus pumilus was only found in Le. bellula. The possible role of these bacteria in the ability of predators to feed on D. opuntiae and D. coccus is discussed.