Plastic biodegradation: Do Galleria mellonella Larvae Bioassimilate Polyethylene? A Spectral Histology Approach Using Isotopic Labeling and Infrared Microspectroscopy.

Environmental pollution by the nearly nonbiodegradable polyethylene (PE) plastics is of major concern; thus, organisms capable of biodegrading PE are required. The larvae of the Greater Wax Moth, Galleria mellonella (Gm), were identified as a potential candidate to digest PE. In this study, we tested whether PE was metabolized by Gm larvae and could be found in their tissues. We examined the implication of the larval gut microbiota by using conventional and axenic reared insects. First, our study showed that neither beeswax nor LDPE alone favor the growth of young larvae. We then used Fourier transform infrared microspectroscopy (µFTIR) to detect deuterium in larvae fed with isotopically labeled food. Deuterated molecules were found in tissues of larvae fed with deuterium labeled oil for 24 and 72 h, proving that µFTIR can detect metabolization of 1 to 2 mg of deuterated food. Then, Gm larvae were fed with deuterated PE (821 kDa). No bioassimilation was detected in the tissues of larvae that had ingested 1 to 5 mg of deuterated PE in 72 h or in 19 days, but micrometer sized PE particles were found in the larval digestive tract cavities. We evidenced weak biodegradation of 641 kDa PE films in contact for 24 h with the dissected gut of conventional larvae and in the PED4 particles from excreted larval frass. Our study confirms that Gm larvae can biodegrade HDPE but cannot necessarily metabolize it.

Congenital cystic adenomatoid malformations of the lung: an epithelial transcriptomic approach.

BACKGROUND: The pathophysiology of congenital cystic adenomatoid malformations (CCAM) of the lung remains poorly understood. AIM: This study aimed to identify more precisely the molecular mechanisms limited to a compartment of lung tissue, through a transcriptomic analysis of the epithelium of macrocystic forms. METHODS: Tissue fragments displaying CCAM were obtained during planned surgical resections. Epithelial mRNA was obtained from cystic and normal areas after laser capture microdissection (LCM). Transcriptomic analyses were performed and the results were confirmed by RT-PCR and immunohistochemistry in independent samples. RESULTS: After controlling for RNA quality, we analysed the transcriptomes of six cystic areas and five control areas. In total, 393 transcripts were differentially expressed in the epithelium, between CCAM and control areas. The most highly redundant genes involved in biological functions and signalling pathways differentially expressed between CCAM and control epithelium included TGFB2, TGFBR1, and MAP 2 K1. These genes were considered particularly relevant as they have been implicated in branching morphogenesis. RT-qPCR analysis confirmed in independent samples that TGFBR1 was more strongly expressed in CCAM than in control tissues (p < 0.03). Immunohistochemistry analysis showed TGFBR1 (p = 0.0007) and TGFB2 (p < 0.02) levels to be significantly higher in the epithelium of CCAM than in that of control tissues. CONCLUSIONS: This compartmentalised transcriptomic analysis of the epithelium of macrocystic lung malformations identified a dysregulation of TGFB signalling at the mRNA and protein levels, suggesting a possible role of this pathway in CCAM pathogenesis. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01732185.

Different miRNA contents between mammary epithelial cells and milk fat globules: a random or a targeted process?

MicroRNAs (miRNAs) are small noncoding RNAs present in milk-derived extracellular vesicles and milk fat globules (MFG). Nucleic acid content between the lactating mammary tissue (MT) and MFG are quite similar but discrepancies exist in their miRNA content. Our objective was to identify the origin of these discrepancies, and to evaluate the existence of a possible mechanism sorting miRNAs that will or will not be exported from the mammary epithelial cells (MECs) in bovine MFG. miR-125b-5p, miR-126-3p, miR-141-3p, and miR-204-5p, chosen on the basis of their abundance in the MT, were quantified using RT-qPCR in lactating cow MT, MFG, and laser capture-microdissected MECs. Two miRNAs (miR-125b-5p and miR-141-3p) were detected in the MT as well as in MFG and MECs. miR-204-5p was detected only in the MT, suggesting that it is very likely expressed in a cell type other than MECs. miR-126-3p was detected both in the MT and in MECs but not in MFG, suggesting a targeting mechanism for miRNAs in MECs. These results highlights differences in miRNA content between MECs and MFG may be due to a possibly not random mechanism for loading MFG with miRNA cargos that could involve a variable distribution in MECs or a sorting mechanism.

Laser capture microdissection to study Bacillus cereus iron homeostasis gene expression during Galleria mellonella in vivo gut colonization.

Bacillus cereus is a Gram-positive opportunistic pathogen closely related to the entomopathogen, Bacillus thuringiensis, both of which are involved in intestinal infections. Iron is an essential micronutrient for full growth and virulence of pathogens during infection. However, little is known about iron homeostasis during gut infection. Therefore, we aimed to assess the expression of B. cereus genes related to bacterial iron homeostasis, virulence and oxidative stress. The hypothesis is that the expression of such genes would vary between early and later stage colonization in correlation to gut cell damage. To perform the study, a germ-free Galleria mellonella model was set up in order to adapt the use of Laser-capture microdissection (LCM), to select precise areas in the gut lumen from frozen whole larval cryo-sections. Analyses were performed from alive larvae and the expression of targeted genes was assessed byspecific pre-amplification of mRNA followed by quantitative PCR. Firstly, the results reinforce the reliability of LCM, despite a low amount of bacterial RNA recovered. Secondly, bacterial genes involved in iron homeostasis are expressed in the lumen at both 3 and 16 hours post force-feeding. Thirdly, iron gene expression is slightly modulated during gut infection, and lastly, the mRNA of G. mellonella encoding for ferritin and transferrin iron storage and transport are recovered too. Therefore, iron homeostasis should play a role in B. cereus gut colonization. Furthermore, we demonstrate for the first time the value of using LCM for specific in situ gene expression analysis of extracellular bacteria in a whole animal.

The quest for epigenetic regulation underlying unisexual flower development in Cucumis melo.

BACKGROUND: Melon (Cucumis melo) is an important vegetable crop from the Cucurbitaceae family and a reference model specie for sex determination, fruit ripening and vascular fluxes studies. Nevertheless, the nature and role of its epigenome in gene expression regulation and more specifically in sex determination remains largely unknown. RESULTS: We have investigated genome wide H3K27me3 and H3K9ac histone modifications and gene expression dynamics, in five melon organs. H3K9ac and H3K27me3 were mainly distributed along gene-rich regions and constrained to gene bodies. H3K9ac was preferentially located at the TSS, whereas H3K27me3 distributed uniformly from TSS to TES. As observed in other species, H3K9ac and H3K27me3 correlated with high and low gene expression levels, respectively. Comparative analyses of unisexual flowers pointed out sex-specific epigenetic states of TFs involved in ethylene response and flower development. Chip-qPCR analysis of laser dissected carpel and stamina primordia, revealed sex-specific histone modification of MADS-box genes. Using sex transition mutants, we demonstrated that the female promoting gene, CmACS11, represses the expression of the male promoting gene CmWIP1 via deposition of H3K27me3. CONCLUSIONS: Our findings reveal the organ-specific landscapes of H3K9ac and H3K27me3 in melon. Our results also provide evidence that the sex determination genes recruit histone modifiers to orchestrate unisexual flower development in monoecious species.