5-Hydroxymethylfurfural mediated developmental toxicity in Drosophila melanogaster

5-hydroxymethylfurfural is a common byproduct in food. However, its effect on growth and development remains incompletely understood. This study investigated the developmental toxicity of 5-HMF to Drosophila larvae. The growth and development of Drosophila melanogaster fed with 5-50 mM 5-HMF was monitored, and its possible mechanism was explored. It was found that 5-HMF prolonged the developmental cycle of Drosophila melanogaster (25 mM and 50 mM). After 5-HMF intake, the level of reactive oxygen species in the third instar larvae increased by 1.23-1.40 fold, which increased the level of malondialdehyde and caused changes in antioxidant enzymes. Moreover, the nuclear factor erythroid-2 related factor 2 antioxidant signaling pathway and the expression of heat shock protein genes were affected. At the same time, 5-HMF disrupted the glucose and lipid metabolism in the third instar larvae, influencing the expression level of key genes in the insulin signal pathway. Furthermore, 5-HMF led to intestinal oxidative stress, and up-regulated the expression of the pro-apoptotic gene, consequently impacting intestinal health. In short, 5-HMF causes oxidative stress, disturbs glucose and lipid metabolism and induces intestinal damage, damaging related signaling pathways, and ultimately affecting the development of Drosophila melanogaster.

Exploration-exploitation trade-off is regulated by metabolic state and taste value in Drosophila

Similar to other animals, the fly, Drosophila melanogaster, changes its foraging strategy from exploration to exploitation upon encountering a nutrient-rich food source. However, the impact of metabolic state or taste/nutrient value on exploration vs. exploitation decisions in flies is poorly understood. Here, we developed a one-source foraging assay that uses automated video tracking coupled with high-resolution measurements of food ingestion to investigate the behavioral variables flies use when foraging for food with different taste/caloric values and when in different metabolic states. We found that flies alter their foraging and ingestive behaviors based on their hunger state and the concentration of the sucrose solution. Interestingly, sugar-blind flies did not transition from exploration to exploitation upon finding a high-concentration sucrose solution, suggesting that taste sensory input, as opposed to post-ingestive nutrient feedback, plays a crucial role in determining the foraging decisions of flies. Using a Generalized Linear Model (GLM), we showed that hunger state and sugar volume ingested, but not the nutrient or taste value of the food, influence flies' radial distance to the food source, a strong indicator of exploitation. Our behavioral paradigm and theoretical framework offer a promising avenue for investigating the neural mechanisms underlying state and value-based foraging decisions in flies, setting the stage for systematically identifying the neuronal circuits that drive these behaviors.

Multigenerational Effect of Heat Stress on the Drosophila melanogaster Sperm Proteome

The effect of the parental environment on offspring through non-DNA sequence-based mechanisms, such as DNA methylation, chromatin modifications, noncoding RNAs, and proteins, could only be established after the conception of "epigenetics". These effects are now broadly referred to as multigenerational epigenetic effects. Despite accumulating evidence of male gamete-mediated multigenerational epigenetic inheritance, little is known about the factors that underlie heat stress-induced multigenerational epigenetic inheritance via the male germline in Drosophila. In this study, we address this gap by utilizing an established heat stress paradigm in Drosophila and investigating its multigenerational effect on the sperm proteome. Our findings indicate that multigenerational heat stress during the early embryonic stage significantly influences proteins in the sperm associated with translation, chromatin organization, microtubule-based processes, and the generation of metabolites and energy. Assessment of life-history traits revealed that reproductive fitness and stress tolerance remained unaffected by multigenerational heat stress. Our study offers initial insights into the chromatin-based epigenetic mechanisms as a plausible means of transmitting heat stress memory through the male germline in Drosophila. Furthermore, it sheds light on the repercussions of early embryonic heat stress on male reproductive potential. The data sets from this study are available at the ProteomeXchange Consortium under the identifier PXD037488.

Effect of allyl-isothiocyanate on survival and antimicrobial peptide expression following oral bacterial infections in Drosophila melanogaster

Since infections with antibiotic-resistant bacteria cause increasing problems worldwide, the identification of alternative therapies is of great importance. Plant-derived bioactives, including allyl-isothiocyanate (AITC), have received attention for their antimicrobial properties. The present study therefore investigates the impact of AITC on survival and antimicrobial peptide (AMP) levels in Drosophila melanogaster challenged with the fly pathogenic bacteria Pectobacterium carotovorum subsp. carotovorum and Leuconostoc pseudomesenteroides. AITC, a sulfur-containing compound derived from glucosinolates, exhibits antimicrobial properties and has been suggested to modulate AMP expression. By using D. melanogaster, we demonstrate that AITC treatment resulted in a concentration-dependent decrease of survival rates among female flies, particularly in the presence of the Gram-negative bacterium Pectobacterium carotovorum subsp. carotovorum, whereas AITC did not affect survival in male flies. Despite the ability of isothiocyanates to induce AMP expression in cell culture, we did not detect significant changes in AMP mRNA levels in infected flies exposed to AITC. Our findings suggest sex-specific differences in response to AITC treatment and bacterial infections, underlining the complexity of host-pathogen interactions and potential limitations of AITC as a preventive or therapeutic compound at least in D. melanogaster models of bacterial infections.

Accelerated protein retention expansion microscopy using microwave radiation

Protein retention expansion microscopy (ExM) retains genetically encoded fluorescent proteins or antibody-conjugated fluorescent probes in fixed tissue and isotropically expands the tissue through a swellable polymer network to allow nanoscale (<70 nm) resolution on diffraction-limited confocal microscopes. Despite numerous advantages ExM brings to biological studies, the full protocol is time-consuming and can take multiple days to complete. Here, we adapted the ExM protocol to the vibratome-sectioned brain tissue of Xenopus laevis tadpoles and implemented a microwave-assisted protocol to reduce the workflow from days to hours. In addition to the significantly accelerated processing time, our microwave-assisted ExM (M/WExM) protocol maintains the superior resolution and signal-to-noise ratio of the original ExM protocol. Furthermore, the M/WExM protocol yields higher magnitude of expansion, suggesting that in addition to accelerating the process through increased diffusion rate of reagents, microwave radiation may also facilitate the expansion process. To demonstrate the applicability of this method to other specimens and protocols, we adapted the microwave-accelerated protocol to whole mount adult brain tissue of Drosophila melanogaster fruit flies, and successfully reduced the total processing time of a widely-used Drosophila IHC-ExM protocol from 6 days to 2 days. Our results demonstrate that with appropriate adjustment of the microwave parameters (wattage, pulse duration, interval, and number of cycles), this protocol can be readily adapted to different model organisms and tissue types to greatly increase the efficiency of ExM experiments.

Corrigendum: What can the common fruit fly teach us about stroke?: lessons learned from the hypoxic tolerant Drosophila melanogaster

[This corrects the article DOI: 10.3389/fncel.2024.1347980.].

Impact of tRNA-induced proline-to-serine mistranslation on the transcriptome of Drosophila melanogaster

Mistranslation is the misincorporation of an amino acid into a polypeptide. Mistranslation has diverse effects on multicellular eukaryotes and is implicated in several human diseases. In Drosophila melanogaster, a serine transfer RNA (tRNA) that misincorporates serine at proline codons (P→S) affects male and female flies differently. The mechanisms behind this discrepancy are currently unknown. Here, we compare the transcriptional response of male and female flies to P→S mistranslation to identify genes and cellular processes that underlie sex-specific differences. Both males and females downregulate genes associated with various metabolic processes in response to P→S mistranslation. Males downregulate genes associated with extracellular matrix organization and response to negative stimuli such as wounding, whereas females downregulate aerobic respiration and ATP synthesis genes. Both sexes upregulate genes associated with gametogenesis, but females also upregulate cell cycle and DNA repair genes. These observed differences in the transcriptional response of male and female flies to P→S mistranslation have important implications for the sex-specific impact of mistranslation on disease and tRNA therapeutics.

Microbiota-derived acetylcholine can promote gut motility in Drosophila melanogaster

The gut microbiota is crucial for intestinal health, including gastrointestinal (GI) motility. How commensal bacterial species influence GI motility has not been fully elucidated. A major factor of GI motility is the gut contraction promoting the propulsive movement of orally ingested materials. Here, we developed a method to monitor and quantify gut contractions in living Drosophila melanogaster larvae. We found that the culture medium of an isolated strain Lactiplantibacillus plantarum Lsi promoted gut contraction in vivo, which was not observed in Leuconostoc sp. Leui nor Acetobacter persici Ai culture medium. To identify bacteria-derived metabolites, we performed metabolome analysis of the culture media by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Of the 66 metabolites detected, we found that some metabolites changed in a species-specific manner. Among them, acetylcholine was specifically produced by L. plantarum. Feeding exogenous acetylcholine increased the frequency of gut contractions, which was blocked by D-tubocurarine, an inhibitor of nicotinic acetylcholine receptors. In this study, we propose a mechanism by which the gut microbiota influences Drosophila gut motility. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Genetic Variation in Male Aggression Is Influenced by Genotype of Prior Social Partners in Drosophila melanogaster

AbstractSocial behaviors can be influenced by the genotypes of interacting individuals through indirect genetic effects (IGEs) and can also display developmental plasticity. We investigated how developmental IGEs, which describe the effects of a prior social partner's genotype on later behavior, can influence aggression in male Drosophila melanogaster. We predicted that developmental IGEs cannot be estimated by simply extending the effects of contextual IGEs over time and instead have their own unique effects on behavior. On day 1 of the experiment, we measured aggressive behavior in 15 genotypic pairings (n = 600 males). On day 2, each of the males was paired with a new opponent, and aggressive behavior was again measured. We found contextual IGEs on day 1 of the experiment and developmental IGEs on day 2 of the experiment: the influence of the day 1 partner's genotype on the focal individual's day 2 behavior depended on the genotypic identity of both the day 1 partner and the focal male. Importantly, the developmental IGEs in our system produced fundamentally different dynamics than the contextual IGEs, as the presence of IGEs was altered over time. These findings represent some of the first empirical evidence demonstrating developmental IGEs, a first step toward incorporating developmental IGEs into our understanding of behavioral evolution.

NUCB1 is required for proper insulin signaling to control longevity in Drosophila

AIM

We examined the novel role of NUCB1(Nucleobindin-1) associated with longevity in Drosophila melanogaster.

METHODS

We measured the lifespan, metabolic phenotypes, and mRNA levels of Drosophila insulin-like peptides (Dilps), the protein level of phosphorylated AKT, and the localization of FOXO and its target gene expressions in the NUCB1 knockdown condition.

RESULTS

NUCB1 knockdown flies show an extended lifespan and metabolic phenotypes such as increased circulating glucose level and starvation resistance. The mRNA expression levels of Dilps and the protein level of phosphorylated AKT, a downstream component of insulin signaling, were decreased in NUCB1 knockdown flies compared with the control flies. Also, the nuclear localization of FOXO and its target gene expressions, such as d4E-BP and InR, were elevated.

CONCLUSIONS

The results show that NUCB1 knockdown flies exhibits an extended lifespan. These findings suggest that NUCB1 modulates longevity through insulin signaling in Drosophila. Geriatr Gerontol Int 2024; 24: 486-492.

Exposure to Bisphenol F and Bisphenol S during development induces autism-like endophenotypes in adult Drosophila melanogaster

Bisphenol F (BPF) and Bisphenol S (BPS) are being widely used by the industry with the claim of "safer substances", even with the scarcity of toxicological studies. Given the etiological gap of autism spectrum disorder (ASD), the environment may be a causal factor, so we investigated whether exposure to BPF and BPS during the developmental period can induce ASD-like modeling in adult flies. Drosophila melanogaster flies were exposed during development (embryonic and larval period) to concentrations of 0.25, 0.5, and 1 mM of BPF and BPS, separately inserted into the food. When they transformed into pupae were transferred to a standard diet, ensuring that the flies (adult stage) did not have contact with bisphenols. Thus, after hatching, consolidated behavioral tests were carried out for studies with ASD-type models in flies. It was observed that 1 mM BPF and BPS caused hyperactivity (evidenced by open-field test, negative geotaxis, increased aggressiveness and reproduction of repetitive behaviors). The flies belonging to the 1 mM groups of BPF and BPS also showed reduced cognitive capacity, elucidated by the learning behavior through aversive stimulus. Within the population dynamics that flies exposed to 1 mM BPF and 0.5 and 1 mM BPS showed a change in social interaction, remaining more distant from each other. Exposure to 1 mM BPF, 0.5 and 1 mM BPS increased brain size and reduced Shank immunoreactivity of adult flies. These findings complement each other and show that exposure to BPF and BPS during the development period can elucidate a model with endophenotypes similar to ASD in adult flies. Furthermore, when analyzing comparatively, BPS demonstrated a greater potential for damage when compared to BPF. Therefore, in general these data sets contradict the idea that these substances can be used freely.

Eye proteome of Drosophila melanogaster

Drosophila melanogaster is a popular model organism to elucidate the molecular mechanisms that underlie the structure and function of the eye as well as the causes of retinopathies, aging, light-induced damage, or dietary deficiencies. Large-scale screens have isolated genes whose mutation causes morphological and functional ocular defects, which led to the discovery of key components of the phototransduction cascade. However, the proteome of the Drosophila eye is poorly characterized. Here, we used GeLC-MS/MS to quantify 3516 proteins, including the absolute (molar) quantities of 43 proteins in the eye of adult male Drosophila reared on standard laboratory food. This work provides a generic and expandable resource for further genetic, pharmacological, and dietary studies.

Fractionation and antioxidation activities of polysaccharides from Zanthoxylum bungeanum Maxim

Zanthoxylum bungeanum has a lengthy history of widespread use as a food ingredient in China. However, the composition of Zanthoxylum bungeanum polysaccharide remains ambiguous, and the antioxidant effect has received limited attention. This study aimed to extract water-soluble polysaccharide from the dried pericarp of Zanthoxylum bungeanum, referred to as WZBP, which was fractionated into a neutral component (WZBP-N) and three pectic components (WZBP-A-I, WZBP-A-II, WZBP-A-III). The findings indicated that WZBP-A-III is a pectic polysaccharide "smooth region" without many side chains. All components of WZBP exhibited a notable capacity for scavenging free radicals, with WZBP-A-III demonstrating the most potent antioxidation activity, and WZBP-A-III also observed to effectively extend the lifespan of Drosophila melanogaster and enhanced the activity of antioxidant enzymes. These results provide valuable insight and direction for future research on Zanthoxylum bungeanum polysaccharide as an antioxidant agent.

Artemisia argyi extract exerts antioxidant properties and extends the lifespan of Drosophila melanogaster

BACKGROUND

Chinese mugwort (Artemisia argyi) possesses extensive pharmacological activities associated with anti-tumour, antioxidative and anti-inflammatory effects. The present study aimed to investigate the antioxidant and anti-ageing effects of A. argyi extract (AAE) on the fruit fly (Drosophila melanogaster) ageing model by detecting antioxidant enzyme activities and the mRNA level of antioxidant genes.

RESULTS

AAE could significantly lengthen the mean lifespan, 50% survival days, and maximum lifespan of D. melanogaster, especially when the amount of AAE added reached 6.68 mg mL-1, the mean lifespan of both female and male flies increased by 23.74% and 22.30%, respectively, indicating the effective life extension effect of AAE. At the same time, AAE could improve the climbing ability and tolerance to hydrogen peroxide in D. melanogaster. In addition, the addition of AAE effectively increased the activities of copper-zinc-containing superoxide dismutase, manganese-containing superoxide dismutase and catalase in D. melanogaster and reduced the contents of malondialdehyde. Moreover, when reared with diets containing AAE, the expression of antioxidant-related genes SOD1, SOD2 and CAT was up-regulated in D. melanogaster and down-regulated for MTH genes.

CONCLUSION

The study indicates that AAE effectively enhances the antioxidant capacity of D. melanogaster and has potential applications as an antioxidant and anti-ageing agent in the nutraceutical industry. © 2024 Society of Chemical Industry.

ASXL3-related disorder: Molecular phenotyping and comprehensive review providing insights into disease mechanism

ASXL3-related disorder, sometimes referred to as Bainbridge-Ropers syndrome, was first identified as a distinct neurodevelopmental disorder by Bainbridge et al. in 2013. Since then, there have been a number of case series and single case reports published worldwide. A comprehensive review of the literature was carried out. Abstracts were screened, relevant literature was analysed, and descriptions of common phenotypic features were quantified. ASXL3 variants were collated and categorised. Common phenotypic features comprised global developmental delay or intellectual disability (97%), feeding problems (76%), hypotonia (88%) and characteristic facial features (93%). The majority of genetic variants were de novo truncating variants in exon 11 or 12 of the ASXL3 gene. Several gaps in our knowledge of this disorder were identified, namely, underlying pathophysiology and disease mechanism, disease contribution of missense variants, relevance of variant location, prevalence and penetrance data. Clinical information is currently limited by patient numbers and lack of longitudinal data, which this review aims to address.

α-Synuclein pathology in Drosophila melanogaster is exacerbated by haploinsufficiency of Rop: connecting STXBP1 encephalopathy with α-synucleinopathies

Syntaxin-binding protein 1 (STXBP1) is a presynaptic protein that plays important roles in synaptic vesicle docking and fusion. STXBP1 haploinsufficiency causes STXBP1 encephalopathy (STXBP1-E), which encompasses neurological disturbances including epilepsy, neurodevelopmental disorders, and movement disorders. Most patients with STXBP1-E present with regression and movement disorders in adulthood, highlighting the importance of a deeper understanding of the neurodegenerative aspects of STXBP1-E. An in vitro study proposed an interesting new role of STXBP1 as a molecular chaperone for α-Synuclein (αSyn), a key molecule in the pathogenesis of neurodegenerative disorders. However, no studies have shown αSyn pathology in model organisms or patients with STXBP1-E. In this study, we used Drosophila models to examine the effects of STXBP1 haploinsufficiency on αSyn-induced neurotoxicity in vivo. We demonstrated that haploinsufficiency of Ras opposite (Rop), the Drosophila ortholog of STXBP1, exacerbates compound eye degeneration, locomotor dysfunction, and dopaminergic neurodegeneration in αSyn-expressing flies. This phenotypic aggravation was associated with a significant increase in detergent-insoluble αSyn levels in the head. Furthermore, we tested whether trehalose, which has neuroprotective effects in various models of neurodegenerative disorders, mitigates αSyn-induced neurotoxicity exacerbated by Rop haploinsufficiency. In flies expressing αSyn and carrying a heterozygous Rop null variant, trehalose supplementation effectively alleviates neuronal phenotypes, accompanied by a decrease in detergent-insoluble αSyn in the head. In conclusion, this study revealed that Rop haploinsufficiency exacerbates αSyn-induced neurotoxicity by altering the αSyn aggregation propensity. This study not only contributes to understanding the mechanisms of neurodegeneration in STXBP1-E patients, but also provides new insights into the pathogenesis of α-synucleinopathies.

Novel Genome-Engineered H Alleles Differentially Affect Lateral Inhibition and Cell Dichotomy Processes during Bristle Organ Development

Hairless (H) encodes the major antagonist in the Notch signaling pathway, which governs cellular differentiation of various tissues in Drosophila. By binding to the Notch signal transducer Suppressor of Hairless (Su(H)), H assembles repressor complexes onto Notch target genes. Using genome engineering, three new H alleles, HFA, HLLAA and HWA were generated and a phenotypic series was established by several parameters, reflecting the residual H-Su(H) binding capacity. Occasionally, homozygous HWA flies develop to adulthood. They were compared with the likewise semi-viable HNN allele affecting H-Su(H) nuclear entry. The H homozygotes were short-lived, sterile and flightless, yet showed largely normal expression of several mitochondrial genes. Typical for H mutants, both HWA and HNN homozygous alleles displayed strong defects in wing venation and mechano-sensory bristle development. Strikingly, however, HWA displayed only a loss of bristles, whereas bristle organs of HNN flies showed a complete shaft-to-socket transformation. Apparently, the impact of HWA is restricted to lateral inhibition, whereas that of HNN also affects the respective cell type specification. Notably, reduction in Su(H) gene dosage only suppressed the HNN bristle phenotype, but amplified that of HWA. We interpret these differences as to the role of H regarding Su(H) stability and availability.

The gut microbiome promotes locomotion of Drosophila larvae via octopamine signaling

The gut microbiome is a key partner of animals, influencing various aspects of their physiology and behaviors. Among the diverse behaviors regulated by the gut microbiome, locomotion is vital for survival and reproduction, although the underlying mechanisms remain unclear. Here, we reveal that the gut microbiome modulates the locomotor behavior of Drosophila larvae via a specific neuronal type in the brain. The crawling speed of germ-free (GF) larvae was significantly reduced compared to the conventionally reared larvae, while feeding and excretion behaviors were unaffected. Recolonization with Acetobacter and Lactobacillus can fully and partially rescue the locomotor defects in GF larvae, respectively, probably due to the highest abundance of Acetobacter as a symbiotic bacterium in the larval gut, followed by Lactobacillus. Moreover, the gut microbiome promoted larval locomotion, not by nutrition, but rather by enhancing the brain levels of tyrosine decarboxylase 2 (Tdc2), which is an enzyme that synthesizes octopamine (OA). Overexpression of Tdc2 rescued locomotion ability in GF larvae. These findings together demonstrate that the gut microbiome specifically modulates larval locomotor behavior through the OA signaling pathway, revealing a new mechanism underlying larval locomotion regulated by the gut microbiome.

Tastant-receptor interactions: insights from the fruit fly

Across species, taste provides important chemical information about potential food sources and the surrounding environment. As details about the chemicals and receptors responsible for gustation are discovered, a complex view of the taste system is emerging with significant contributions from research using the fruit fly, Drosophila melanogaster, as a model organism. In this brief review, we summarize recent advances in Drosophila gustation and their relevance to taste research more broadly. Our goal is to highlight the molecular mechanisms underlying the first step of gustatory circuits: ligand-receptor interactions in primary taste cells. After an introduction to the Drosophila taste system and how it encodes the canonical taste modalities sweet, bitter, and salty, we describe recent insights into the complex nature of carboxylic acid and amino acid detection in the context of sour and umami taste, respectively. Our analysis extends to non-canonical taste modalities including metals, fatty acids, and bacterial components, and highlights unexpected receptors and signaling pathways that have recently been identified in Drosophila taste cells. Comparing the intricate molecular and cellular underpinnings of how ligands are detected in vivo in fruit flies reveals both specific and promiscuous receptor selectivity for taste encoding. Throughout this review, we compare and contextualize these Drosophila findings with mammalian research to not only emphasize the conservation of these chemosensory systems, but to demonstrate the power of this model organism in elucidating the neurobiology of taste and feeding.

Regulation of phase separation and antiviral activity of Cactin by glycolytic enzyme PGK via phosphorylation in Drosophila

Liquid-liquid phase separation (LLPS) plays a crucial role in various biological processes in eukaryotic organisms, including immune responses in mammals. However, the specific function of LLPS in immune responses in Drosophila melanogaster remains poorly understood. Cactin, a highly conserved protein in eukaryotes, is involved in a non-canonical signaling pathway associated with Nuclear factor-κB (NF-κB)-related pathways in Drosophila. In this study, we investigated the role of Cactin in LLPS and its implications for immune response modulation. We discovered that Cactin undergoes LLPS, forming droplet-like particles, primarily mediated by its intrinsically disordered region (IDR). Utilizing immunoprecipitation and mass spectrometry analysis, we identified two phosphorylation sites at serine residues 99 and 104 within the IDR1 domain of Cactin. Co-immunoprecipitation and mass spectrometry further revealed phosphoglycerate kinase (PGK) as a Cactin-interacting protein responsible for regulating its phosphorylation. Phosphorylation of Cactin by PGK induced a transition from stable aggregates to dynamic liquid droplets, enhancing its ability to interact with other components in the cellular environment. Overexpression of PGK inhibited Drosophila C virus (DCV) replication, while PGK knockdown increased replication. DCV infection also increased Cactin phosphorylation. We also found that phosphorylation enhances the antiviral ability of Cactin by promoting liquid-phase droplet formation. These findings demonstrate the role of Cactin-phase separation in regulating DCV replication and highlight the modulation of its antiviral function through phosphorylation, providing insights into the interplay between LLPS and antiviral defense mechanisms.

IMPORTANCE

Liquid-liquid phase separation (LLPS) plays an integral role in various biological processes in eukaryotic organisms. Although several studies have highlighted its crucial role in modulating immune responses in mammals, its function in immune responses in Drosophila melanogaster remains poorly understood. Our study investigated the role of Cactin in LLPS and its implications for immune response modulation. We identified that phosphoglycerate kinase (PGK), an essential enzyme in the glycolytic pathway, phosphorylates Cactin, facilitating its transition from a relatively stable aggregated state to a more dynamic liquid droplet phase during the phase separation process. This transformation allows Cactin to rapidly interact with other cellular components, enhancing its antiviral properties and ultimately inhibiting virus replication. These findings expand our understanding of the role of LLPS in the antiviral defense mechanism, shedding light on the intricate mechanisms underlying immune responses in D. melanogaster.

Genomes of historical specimens reveal multiple invasions of LTR retrotransposons in Drosophila melanogaster during the 19th century

Transposable element invasions have a profound impact on the evolution of genomes and phenotypes. It is thus an important open question how often such TE invasions occur. To address this question, we utilize the genomes of historical specimens, sampled about 200 y ago. We found that the LTR retrotransposons Blood, Opus, and 412 spread in Drosophila melanogaster in the 19th century. These invasions constitute second waves, as degraded fragments were found for all three TEs. The composition of Opus and 412, but not of Blood, shows a pronounced geographic heterogeneity, likely due to founder effects during the invasions. Finally, we identified species from the Drosophila simulans complex as the likely origin of the TEs. We show that in total, seven TE families invaded D. melanogaster during the last 200y, thereby increasing the genome size by up to 1.2Mbp. We suggest that this high rate of TE invasions was likely triggered by human activity. Based on the analysis of strains and specimens sampled at different times, we provide a detailed timeline of TE invasions, making D. melanogaster the first organism where the invasion history of TEs during the last two centuries could be inferred.

New Approach Methods to Assess the Enteropathogenic Potential of Strains of the Bacillus cereus Group, including Bacillus thuringiensis

Bacillus cereus (Bc) is a wide group of Gram-positive and spore-forming bacteria, known to be the etiological agents of various human infections, primarily food poisoning. The Bc group includes enteropathogenic strains able to germinate in the digestive tract and to produce enterotoxins such as Nhe, Hbl, and CytK. One species of the group, Bacillus thuringiensis (Bt), has the unique feature of producing insecticidal crystals during sporulation, making it an important alternative to chemical pesticides to protect crops from insect pest larvae. Nevertheless, several studies have suggested a link between the ingestion of pesticide strains and human cases of food poisoning, calling their safety into question. Consequently, reliable tools for virulence assessment are worth developing to aid decision making in pesticide regulation. Here, we propose complementary approaches based on two biological models, the human intestinal Caco-2 cell line and the insect Drosophila melanogaster, to assess and rank the enteric virulence potency of Bt strains in comparison with other Bc group members. Using a dataset of 48 Bacillus spp. strains, we showed that some Bc group strains, including Bt, were able to induce cytotoxicity in Caco-2 cells with concomitant release of IL-8 cytokine, a landmark of pro-inflammatory response. In the D. melanogaster model, we were able to sort a panel of 39 strains into four different classes of virulence, ranging from no virulence to strong virulence. Importantly, for the most virulent strains, mortality was associated with a loss of intestinal barrier integrity. Interestingly, although strains can share a common toxinotype, they display different degrees of virulence, suggesting the existence of specific mechanisms of virulence expression in vivo in the intestine.

Escargot a Snail superfamily member and its multiple roles in Drosophila melanogaster development

The Snail superfamily of transcription factors plays a crucial role in metazoan development; one of the most important vertebrate members of this family is Snai1 which is orthologous to the Drosophila melanogaster esg gene. This review offers a comprehensive examination of the roles of the esg gene in Drosophila development, covering its expression pattern and downstream targets, and draws parallels between the vertebrate Snai1 family proteins on controlling the epithelial-to-mesenchymal transition and esg. This gene regulates stemness, ploidy, and pluripontency. esg is expressed in various tissues during development, including the gut, imaginal discs, and neuroblasts. The functions of the esg include the suppression of differentiation in intestinal stem cells and the preservation of diploidy in imaginal cells. In the nervous system development, esg expression also inhibits neuroblast differentiation, thus regulating the number of neurons and the moment in development of neuronal differentiation. Loss of esg function results in diverse developmental defects, including defects in intestinal stem cell maintenance and differentiation, and alters imaginal disc and nervous system development. Expression levels of esg also play a role in regulating longevity and metabolism in adult stages. This review provides an overview of the current understanding of esg's developmental role, emphasizing cellular and tissue effects that arise from its loss of function. The insights gained may contribute to a better understanding of evolutionary conserved developmental mechanisms and certain metabolic diseases.

Mitochondrial Differentiation during Spermatogenesis: Lessons from Drosophila melanogaster

Numerous diseases can arise as a consequence of mitochondrial malfunction. Hence, there is a significant focus on studying the role of mitochondria in cancer, ageing, neurodegenerative diseases, and the field of developmental biology. Mitochondria could exist as discrete organelles in the cell; however, they have the ability to fuse, resulting in the formation of interconnected reticular structures. The dynamic changes between these forms correlate with mitochondrial function and mitochondrial health, and consequently, there is a significant scientific interest in uncovering the specific molecular constituents that govern these transitions. Moreover, the specialized mitochondria display a wide array of variable morphologies in their cristae formations. These inner mitochondrial structures are closely associated with the specific functions performed by the mitochondria. In multiple cases, the presence of mitochondrial dysfunction has been linked to male sterility, as it has been observed to cause a range of abnormal spermatogenesis and sperm phenotypes in different species. This review aims to elucidate the dynamic alterations and functions of mitochondria in germ cell development during the spermatogenesis of Drosophila melanogaster.

Chitosan oligosaccharide improves intestinal homeostasis to achieve the protection for the epithelial barrier of female Drosophila melanogaster via regulating intestinal microflora

Chitosan oligosaccharide (COS) is a new type of marine functional oligosaccharide with biological activities such as regulating intestinal microflora and improving intestinal immunity. In this study, female Drosophila melanogaster was used as a model organism to evaluate the effect of COS on intestinal injury by H2O2 induction, and its mechanism was explored through the analysis of intestinal homeostasis. The results showed that 0.25% of COS could effectively prolong the lifespan of stressed female D. melanogaster by increasing its antioxidant capacity and maintaining intestinal homeostasis, which included protecting the mechanical barrier, promoting the chemical barrier, and regulating the biological barrier by affecting its autophagy and the antioxidant signaling pathway. Additionally, the protective effect of COS on the intestinal barrier and homeostasis of D. melanogaster under oxidative stress status is directly related to its regulation of the intestinal microflora, which could decrease excessive autophagy and activate the antioxidant system to promote health.

IMPORTANCE

The epithelial barrier plays an important role in the organism's health. Chitosan oligosaccharide (COS), a new potential prebiotic, exhibits excellent antioxidant capacity and anti-inflammatory effects. Our study elucidated the protective mechanisms of COS on the intestinal barrier of Drosophila melanogaster under oxidative stress, which could provide new insights into COS application in various industries, such as food, agriculture, and medicine.