It has been proposed mammary human gland retains a stem cellular population which gives go up to epithelial precursor skin cells

To evaluate dietary bergapten impact on fecundity, cowpea bruchids reared on artificial seeds containing 250 ppm bergapten were produced as above. Newly emerged adults from these seeds, four female and two male, were placed in a separate bottle and eggs laid were recorded and removed daily till all insects died. Three replicates were performed. Insects obtained from artificial seeds without bergapten served as the control. A significant number of contigs had no hits in the BLAST search, and 112 matched genes with unknown function. Those that share homology with genes of known function in the database were categorized according to biological process and molecular function. Bergapten-regulated genes include those involved in sugar, protein and lipid metabolisms, nutrient transport, development, defense, detoxification, signaling and various cellular functions. Such a broad impact suggests that the insect digestive system actively reallocates genomic resources to mitigate negative effect of dietary bergapten. KEGG metabolic pathway analyses indicated that the most abundant categories for bergapten effect were associated with metabolism of carbohydrates and fatty acids. A number of detoxification genes were up-regulated by bergapten but down-regulated by scN. Increasing production of P450s and GSTs, the phase I and II metabolic enzymes, respectively, has been recognized as one of the important counter defense mechanisms that insects use for plant allelochemicals. Catalases play a pivotal role in detoxification and cellular defense against oxidative stress. Laccase 2, a phenoloxidase gene was also induced in bergapten-fed bruchids. Presumably oxidative crosslinking may help decrease bergapten penetration of insect midgut. Furthermore, among bergapten-induced genes were several that are associated with disease resistance. The drosomycin-like genes are of central importance in the insect immune system against bacterial infection. Notably, they are also repressed by scN. On the contrary, many genes involved in protein, lipid and carbohydrate digestion were suppressed under bergapten treatment, opposite to their responses to scN. The antagonistic effect of scN and bergapten on the vast majority of coregulated genes is intriguing. Possibly, scN is able to prevent bergapten-induced adaptive transcriptional adjustment, and even to synergize bergapten’s anti-insect activity. To investigate the potential interaction between bergapten and scN in the insect midgut, a combination of both chemicals were incorporated into the artificial seeds to test their effect on development of the insect. Bergapten at 250 ppm exhibited a mild but significant effect on the development of the bruchids. scN at 1,000 ppm showed no significant effect by itself, yet further delayed RU 24969 hemisuccinate bruchid development by 2 days in the combination treatment when compared to the bergapten treatment. qRT-PCR of 11 selected genes validated the microarray results associated with bergapten treatment. Although scN alone, at the concentration we chose, did not cause any apparent change in insect development, it was sufficient to alter transcript abundance of the selected genes, the profile of which is in agreement with cDNA microarray results. These bergapten- and scN- coregulated genes include those potentially involved in carbohydrate and protein degradation, disease resistance, and stress tolerance. Antagonistic regulation has been observed for many of these genes, that is, genes induced by scN but repressed by bergapten, or vice versa, had much lowered induction or suppression in the combinatory treatment compared to individual chemical treatments. Since insect adaptation to dietary challenges is at least in part mediated by transcriptional regulation, attenuation of bergapten-induced transcriptional adjustment by scN among genes of broad functionality could be responsible for their synergistic anti-insect activity. Out of 80 coregulated genes with BLAST hits, the only two that showed the same transcript regulation by scN and bergapten did not result in further induction or suppression. Deploying secondary metabolites is a common defense mechanism used by many plant species to fight against insect herbivory. Here, we tested dietary bergapten for its effect on a coleopteran storage pest and found that it negatively impacted development, reproduction and survival of cowpea bruchids. Despite the notable plant protective role, many herbivorous insects have evolved various resistance strategies to evade plant defense, and the front line of battle is the digestive canal. Consistently, our microarray analyses demonstrated that the midgut gene expression program in cowpea bruchids changes in response to dietary challenges, whether the challenge was derived from scN or bergapten.

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