The peritrophic matrix (PM) forms a layer composed of chitin and glycoproteins that lines the insect intestinal lumen. This physical barrier plays a role analogous to that of mucous secretions of the vertebrate digestive tract and is thought to protect the midgut epithelium from abrasive food particles and microbes. Almost nothing is known about PM functions in Drosophila , and its function as an immune barrier has never been addressed by a genetic approach. Here we show that the Drosocrystallin (Dcy) protein, a putative component of the eye lens of Drosophila , contributes to adult PM formation. A loss-of-function mutation in the dcy gene results in a reduction of PM width and an increase of its permeability. Upon bacterial ingestion a higher level of expression of antibacterial peptides was observed in dcy mutants, pointing to an influence of this matrix on bacteria sensing by the Imd immune pathway. Moreover, dcy -deficient flies show an increased susceptibility to oral infections with the entomopathogenic bacteria Pseudomonas entomophila and Serratia marcescens . Dcy mutant flies also succumb faster than wild type upon ingestion of a P. entomophila toxic extract. We show that this lethality is due in part to an increased deleterious action of Monalysin, a pore-forming toxin produced by P. entomophila . Collectively, our analysis of the dcy immune phenotype indicates that the PM plays an important role in Drosophila host defense against enteric pathogens, preventing the damaging action of pore-forming toxins on intestinal cells.

Drosophila adults have been utilized as a genetically tractable model organism to decipher the molecular mechanisms of humoral innate immune responses. In an effort to promote the utility of Drosophila larvae as an additional model system, in this study, we describe a novel aspect of an induction mechanism for innate immunity in these larvae. By using a fine tungsten needle created for manipulating semi-conductor devices, larvae were subjected to septic injury. However, although Toll pathway mutants were susceptible to infection with Gram-positive bacteria as had been shown for Drosophila adults, microbe clearance was not affected in the mutants. In addition, Drosophila larvae were found to be sensitive to mechanical stimuli with respect to the activation of a sterile humoral response. In particular, pinching with forceps to a degree that might cause minor damage to larval tissues could induce the expression of the antifungal peptide gene Drosomycin; notably, this induction was partially independent of the Toll and immune deficiency pathways. We therefore propose that Drosophila larvae might serve as a useful model to analyze the infectious and non-infectious inflammation that underlies various inflammatory diseases such as ischemia, atherosclerosis and cancer.

Natural pigments, or natural colorants, are frequently utilized in the food industry due to their diverse functional and nutritional attributes. Beyond their color properties, these pigments possess several biological activities, including antioxidant, anti-inflammatory, anticancer, antibacterial, and neuroprotective effects, as well as benefits for eye health. This review aims to provide a timely overview of the potential of natural pigments in the pharmaceutical, medical, and food industries. Special emphasis is placed on emerging technologies for natural pigment extraction (thermal technologies, non-thermal technologies, and supercritical fluid extraction), their pharmacological effects, and their potential application in intelligent food packaging and as food colorants. Natural pigments show several pharmaceutical prospects. For example, delphinidin (30 µM) significantly inhibited the growth of three cancer cell lines (B16-F10, EO771, and RM1) by at least 90% after 48 h. Furthermore, as an antioxidant agent, fucoxanthin at the highest concentration (50 μg/mL) significantly increased the ratio of glutathione to glutathione disulfide (p < 0.05). In the food industry, natural pigments have been used to improve the nutritional value of food without significantly altering the sensory experience. Moreover, the use of natural pH-sensitive pigments as food freshness indicators in intelligent food packaging is a cutting-edge technological advancement. This innovation could provide useful information to consumers, increase shelf life, and assist in evaluating the quality of packaged food by observing color variations over time. However, the use of natural pigments presents certain challenges, particularly regarding their stability and higher production costs compared to synthetic pigments. This situation underscores the need for further investigation into alternative pigment sources and improved stabilization methods. The instability of these natural pigments emphasizes their tendency to degrade and change color when exposed to various external conditions, including light, oxygen, temperature fluctuations, pH levels, and interactions with other substances in the food matrix.

The commensal microbes of the skin have a significant impact on dermal physiology and pathophysiology. Racial and geographical differences in the skin microbiome are suggested and may play a role in the sensitivity to dermatological disorders, including infectious diseases. However, little is known about the skin microbiome profiles of people living in Central Africa, where severe tropical infectious diseases impose a burden on the inhabitants. This study provided the skin profiles of healthy Cameroonians in different body sites and compared them to healthy Japanese participants. The skin microbiome of Cameroonians was distinguishable from that of Japanese in all skin sites examined in this study. For example, Micrococcus was predominantly found in skin samples of Cameroonians but mostly absent in Japanese skin samples. Instead, the relative abundance of Cutibacterium species was significantly higher in healthy Japanese. Principal coordinate analysis of beta diversity showed that the skin microbiome of Cameroonians formed different clusters from Japanese, suggesting a substantial difference in the microbiome profiles between participants of both countries. In addition, the alpha diversity in skin microbes was higher in Cameroonians than Japanese participants. These data may offer insights into the determinant factors responsible for the distinctness of the skin microbiome of people living in Central Africa and Asia.

In this study, fruit fly of the genus Drosophila is utilized as a suitable model animal to investigate the molecular mechanisms of innate immunity. To combat orally transmitted pathogenic Gram-negative bacteria, the Drosophila gut is armed with the peritrophic matrix, which is a physical barrier composed of chitin and glycoproteins: the Duox system that produces reactive oxygen species (ROS), which in turn sterilize infected microbes, and the IMD pathway that regulates the expression of antimicrobial peptides (AMPs), which in turn control ROS-resistant pathogens. However, little is known about the defense mechanisms against Gram-positive bacteria in the fly gut. Here, we show that the peritrophic matrix protects Drosophila against Gram-positive bacteria S. aureus. We also define the few roles of ROS in response to the infection and show that the IMD pathway is required for the clearance of ingested microbes, possibly independently from AMP expression. These findings provide a new aspect of the gut defense system of Drosophila, and helps to elucidate the processes of gut-microbe symbiosis and pathogenesis.

Ubiquitylation and SUMOylation of the adaptor protein dMyd88 are required for Toll-dependent immune responses in Drosophila .