Midgut Regions Research Articles

Genome-wide identification of lipases in silkworm (Bombyx mori) and their spatio-temporal expression in larval midgut.

Lipases play crucial roles in food digestion by degrading dietary lipids into free fatty acids and glycerols. The domesticated silkworm (Bombyx mori) has been widely used as an important Lepidopteran model for decades. However, little is known about the lipase gene family in the silkworm, especially their hydrolytic activities as digestive enzymes. In this study, a total of 38 lipase genes were identified in the silkworm genome. Phylogenetic analysis indicated that they were divided into three major groups. Twelve lipases were confirmed to be expressed in the midgut at both transcriptional and translational levels. They were grouped into the same gene cluster, suggesting that they could have similar physiological functions. Quantitative real-time PCR (qRT-PCR) analyses indicated that lipases were mainly expressed in anterior and middle midgut regions, and their expression levels varied greatly along the length of midgut. A majority of lipases were down-regulated in the midgut when larvae stopped feeding. However, a unique lipase gene (Bmlip10583) showed low expression level during feeding stage, but it was significantly up-regulated during the larvae-pupae transition. These results demonstrated that expression of silkworm lipases was spatially and temporally regulated in the midgut during larval development. Taken together, our results provide a fundamental research of the lipase gene family in the silkworm.

Comparative transcriptome analysis reveals regional specialization of gene expression in larval silkworm (Bombyx mori) midgut.

Insect midgut plays a central role in food digestion and nutrition absorption. Larval silkworm midgut could be divided into 3 distinct regions based on their morphological colors. However, it remains rudimentary of regional gene expression and physiological function in larval silkworm midgut. Through transcriptome sequencing of 3 midgut compartments, a comprehensive analysis of gene expression atlas along the anterior-posterior axis was conducted. Posterior midgut was found transcriptionally divergent from anterior and middle midgut. Differentially expressed gene analysis revealed the regional specialization of digestive enzyme production, transmembrane transport, chitin metabolism, and hormone regulation in different midgut regions. In addition, gene subsets of pan-midgut and region-specific transcription factors (TFs) along the length of midgut were also identified. The results suggested that homeobox TFs might play an essential role in transcriptional variations across the midgut. Altogether, our study provided the first fundamental resource to investigate physiological function and regulation mechanism in larval midgut compartmentalization.

Genes from Carboxypeptidase A, glutathione S-transferase, and cytochrome b families were found involved in lead transport in insect Musca domestica

Lead (Pb) is a typical toxic contamination source all over the world. In this research, larvae of the housefly (Musca domestica) were fed a Pb-contaminated diet at different Pb doses of 0, 20 and 5000 mg/kg. RNA sequencing was used to identify genes that were differentially expressed in relation to lead transport or detoxification. RNA interference (RNAi) was carried on 12 candidate genes. The results showed that three luminal pH regions of mid-gut were at pH values of 6.33, 3.10, and 7.80. With increasing Pb concentration, the pH of the middle mid-gut decreased by one unit. The expression levels of carboxypeptidase A (CPA1), glutathione S-transferase (GST), and cytochrome b (Cyt b) were linked to Pb treatments, particularly high Pb concentration of 5000 mg/kg. RNAi-mediated down expression of CPA1, GST2, and CYTb-c1 resulted in low Pb accumulation in the larvae of 5000 mg/kg Pb group. These proteins played key roles in Pb transport and detoxification in M. domestica larvae.

Spatiotemporal organization of enteroendocrine peptide expression in Drosophila

The digestion of food and absorption of nutrients occurs in the gut. The nutritional value of food and its nutrients is detected by enteroendocrine cells, and peptide hormones produced by the enteroendocrine cells are thought to be involved in metabolic homeostasis, but the specific mechanisms are still elusive. The enteroendocrine cells are scattered over the entire gastrointestinal tract and can be classified according to the hormones they produce. We followed the changes in combinatorial expression of regulatory peptides in the enteroendocrine cells during metamorphosis from the larva to the adult fruit fly, and re-confirmed the diverse composition of enteroendocrine cell populations. Drosophila enteroendocrine cells appear to differentially regulate peptide expression spatially and temporally depending on midgut region and developmental stage. In the late pupa, Notch activity is known to determine which peptides are expressed in mature enteroendocrine cells of the posterior midgut, and we found that the loss of Notch activity in the anterior midgut results in classes of enteroendocrine cells distinct from the posterior midgut. These results suggest that enteroendocrine cells that populate the fly midgut can differentiate into distinct subtypes that express different combinations of peptides, which likely leads to functional variety depending on specific needs.

Green Synthesis of Selenium Nanoparticles Mediated by Nilgirianthus ciliates Leaf Extracts for Antimicrobial Activity on Foodborne Pathogenic Microbes and PesticidalActivity Against Aedes aegypti with Molecular Docking.

The present study deals with the synthesis of selenium nanoparticles (SeNPs) using Nilgirianthus ciliatus leaf extracts, characterized by UV-Vis spectrophotometer, XRD, FTIR, FE-SEM, HR-TEM, DLS, and zeta potential analysis. The antimicrobial activity against Staphylococcus aureus (MTCC96), Escherichia coli (MTCC443), and Salmonella typhi (MTCC98) showed the remarkable inhibitory effect at 25µl/mL concentration level. Furthermore, the characterized SeNPs showed a great insecticidal activity against Aedes aegypti in the early larval stages with the medianLethal Concentration (LC50)of 0.92mg/L. Histopathological observations of the SeNPs treated midgut and caeca regions of Ae. aegypti 4th instar larvae showed damaged epithelial layer andfragmented peritrophic membrane. In order to provide a mechanistic approach for further studies, molecular docking studies using Auto Dock Vina were performed with compounds of N. ciliatus within the active site of AeSCP2. Overall, the N. ciliates leaf-mediated biogenic SeNPs was promisingly evidenced to have potential larvicidal and food pathogenic bactericidal activity in an eco-friendly approach.

Transcriptomic and proteomic analysis of the underlying mechanisms of digestion of triacylglycerols and phosphatides and absorption and fate of fatty acids along the midgut of Musca domestica

Most dietary lipids are triacylglycerols (TAGs) and phosphatides that are digested by TAG lipases and phospholipases (PLIPs), respectively, originating fatty acids (FA). The genome of Musca domestica has genes coding for phospholipases A1 (1PLIP), A2 (2PLIP), B (BPLIP), and acid lipases (ALIP), as for proteins involved in activation, binding, and metabolism of FA, which expression in the larval midgut was evaluated by RNA-seq. Some of the codified proteins were identified in midgut microvillar-enriched membrane by proteomics. 1PLIPs are the most expressed PLIPs, mainly in anterior midgut whereas 2PLIPs, and BPLIP in middle and posterior midgut, and ALIPs between middle and posterior regions. Absorption of FAs is putatively accomplished by proteins involved in FA activation (acyl-CoA synthetases) found in microvillar-enriched membrane preparations. Furthermore, FA uptake could be enhanced by proteins that bind FAs (FA-binding proteins) and its activated form (acyl-CoA binding proteins) mainly expressed in posterior midgut. Activated FAs could have different fates: synthesis of diacylglycerol (DAG) and TAG through monoacylglycerol and glycerol-3-phosphate pathways; synthesis of phosphatides; energy source by β-oxidation. Most genes coding for enzymes of those routes is expressed mainly at the end of posterior midgut. Data suggest that phosphatides are digested in anterior midgut by Md1PLIPs, releasing lysophosphatides that emulsify fats to be digested by MdALIPs in the middle and posterior midgut. Most resulting FAs is absorbed in the posterior midgut, where they follow the synthesis of DAG, TAG, and phosphatides or are oxidized along the midgut, mainly in highly metabolic middle and posterior midgut regions.

Effects of Blood Sources and Artificial Blood Feeding Membranes on the Biological Parameters and Hepatitis C Virus Infectivity of Culex pipiens (Diptera: Culicidae)

Culex pipiens (L.) has a wide distribution worldwide and is the main vector of many diseases. Mass rearing of all target vector mosquito species is frequently required for public health research and vector control. Vector mosquito species are anautogenous, they need vertebrate blood for egg production. Therefore, female blood feeding is essential for colonisation. Various artificial feeding methods have been developed over the years but they lack consistency. Thus, we have developed an artificial feeding technique for rearing and infection experiments as an attempt to establish a practical guide for vector research. Culex mosquitoes were fed directly and artificially; four blood sources (human, cattle, rat and pigeon) and three different membranes (chick, sausage casing and Parafilm-M®) were assessed based on feeding rate, fecundity, oviposition, egg hatchability and infectivity. The chick membrane was considerably more efficient than sausage casing and Parafilm-M. Using the chick membrane with different blood sources, feeding rates (FR) were 89.60 %, 86.20 %, 61.60 %, 50.40 % for human, cattle, rat and pigeon blood, respectively. There was statistically no significant difference in FR between cattle and human blood. Hepatitis C virus infection was carried out successfully using the artificial feeding technique with chick membrane. RT-PCR readings proved that Culex pipiens can harbour this virus for five days through the midgut region. Cattle blood with chick membrane in mosquito rearing is a good substitute for human blood and live feeding for its availability and cost effectiveness. Overall, this method could be recommended in mosquito experimental infection, vectorial capacity and pathogen interactions studies.

In vivo nanoscale analysis of the dynamic synergistic interaction of Bacillus thuringiensis Cry11Aa and Cyt1Aa toxins in Aedes aegypti.

The insecticidal Cry11Aa and Cyt1Aa proteins are produced by Bacillus thuringiensis as crystal inclusions. They work synergistically inducing high toxicity against mosquito larvae. It was proposed that these crystal inclusions are rapidly solubilized and activated in the gut lumen, followed by pore formation in midgut cells killing the larvae. In addition, Cyt1Aa functions as a Cry11Aa binding receptor, inducing Cry11Aa oligomerization and membrane insertion. Here, we used fluorescent labeled crystals, protoxins or activated toxins for in vivo localization at nano-scale resolution. We show that after larvae were fed solubilized proteins, these proteins were not accumulated inside the gut and larvae were not killed. In contrast, if larvae were fed soluble non-toxic mutant proteins, these proteins were found inside the gut bound to gut-microvilli. Only feeding with crystal inclusions resulted in high larval mortality, suggesting that they have a role for an optimal intoxication process. At the macroscopic level, Cry11Aa completely degraded the gastric caeca structure and, in the presence of Cyt1Aa, this effect was observed at lower toxin-concentrations and at shorter periods. The labeled Cry11Aa crystal protein, after midgut processing, binds to the gastric caeca and posterior midgut regions, and also to anterior and medium regions where it is internalized in ordered "net like" structures, leading finally to cell break down. During synergism both Cry11Aa and Cyt1Aa toxins showed a dynamic layered array at the surface of apical microvilli, where Cry11Aa is localized in the lower layer closer to the cell cytoplasm, and Cyt1Aa is layered over Cry11Aa. This array depends on the pore formation activity of Cry11Aa, since the non-toxic mutant Cry11Aa-E97A, which is unable to oligomerize, inverted this array. Internalization of Cry11Aa was also observed during synergism. These data indicate that the mechanism of action of Cry11Aa is more complex than previously anticipated, and may involve additional steps besides pore-formation activity.

Green synthesis of selenium nanoparticles mediated from Ceropegia bulbosa Roxb extract and its cytotoxicity, antimicrobial, mosquitocidal and photocatalytic activities

The present study is to design an eco-friendly mode to rapidly synthesize selenium nanoparticles (SeNPs) through Ceropegia bulbosa tuber’s aqueous extracts and confirming SeNPs synthesis by UV–Vis spectroscopy, FT-IR, XRD, FE-SEM-EDS mapping, HR-TEM, DLS and zeta potential analysis. In addition, to assess the anti-cancer efficacy of the SeNPs against the cultured MDA-MB-231, as studies have shown SeNPs biosynthesis downregulates the cancer cells when compared to normal HBL100 cell lines. The study observed the IC50 value of SeNPs against MDA-MB-231 cells was 34 µg/mL for 48 h. Furthermore, the SeNPs promotes growth inhibitory effects of certain clinical pathogens such as Bacillus subtilis and Escherichia coli. Apart, from this the SeNPs has shown larvicidal activity after 24 h exposure in Aedes albopitus mosquito’s larvae with a maximum of 250 g/mL mortality concentration. This is confirmed by the histopathology results taken at the 4th larval stage. The histopathological studies revealed intense deterioration in the hindgut, epithelial cells, mid gut and cortex region of the larvae. Finally, tried to investigate the photocatalytic activity of SeNPs against the toxic dye, methylene blue using halogen lamp and obtained 96% degradation results. Withal computational study SeNPs was shown to exhibit consistent stability towards breast cancer protein BRCA2. Overall, our findings suggest SeNPs as a potent disruptive agent for MDA-MB-231 cells, few pathogens, mosquito larvae and boosts the photocatalytic dye degradation.

Histopathology of Chironomus riparius (Diptera, Chironomidae) exposed to metal oxide nanoparticles

As the production of metal-based nanomaterials increases, it is inevitable that nano-scale products and byproducts will enter the aquatic environment. In terms of global production, the most abundant nano-oxides are TiO2, CeO2 and Fe3O4 nanoparticles. Chironomus riparius is commonly used for ecotoxicological assessment and defining its histopathological biomarkers that showcase the toxic effect of tested nanoparticles should lead to a better understanding of the consequences of nanomaterial accumulation in aquatic ecosystems. In this study, a histological description of the digestive and excretory systems as well as the fat body structure of C. riparius larvae is provided. In addition, potential histological biomarkers of nano-oxide toxicity were determined based on the obtained histopathological alterations in organs. Vacuolization was observed in epithelial cells of midgut region I that were treated with nano-Fe3O4 as well as in Malpighian tubules treated with nano-Fe3O4 and nano-CeO2. Larvae exposed to nano-TiO2 showed alterations in the fat body and midgut region II tissue architecture. Additionally, shortening of the intestinal brush border was determined in groups exposed to nano-Fe3O4. These results reveal the high sensitivity of these organs, which can be used as biomarkers in histopathological assessment and therefore lead to further improvement of existing methodology in ecotoxicological studies.

P.417 The emotional disturbances in young patients with type 1 diabetes using various methods of insulin therapy by four-dimensional symptom questionnaire

The southern green stink bug, Nezara viridula is a polyphagous pest of commercially important crops during both nymph and adult stages. This insect has recently transitioned from a secondary agricultural pest to one of primary concern. Novel management solutions are needed due to the limited effectiveness of current control strategies. We performed biochemical and transcriptomic analyses to characterize digestive enzymes in the salivary glands and along midgut tissues of N. viridula nymphs and adults fed on sweet corn. The digestive profiles were more distinct between midgut regions (M1 to M3) than between life stages. Aminopeptidase and chymotrypsin activities declined from the M1 (anterior) toward the M3 midgut region. Cysteine protease activity was higher in the M2 and M3 regions than in M1. Differences in sensitivity to chymotrypsin inhibitors between midgut regions suggest that distinct genes or isoforms are expressed in different regions of the gut. In nymphs, DNA and RNA degradation was higher in M1 than in M3. Adult nuclease activity was low across all midgut regions, but high in salivary glands. The differences in protease activities are reflected by transcriptomic data and functional enrichment of GO terms. Together, our results show that different regions of the digestive tract of N. viridula have specific and distinct digestive properties, and increase our understanding of the physiology of this organism.

Re-opening of the symbiont sorting organ with aging in Riptortus pedestris

Abstract Because environments are full of diverse microorganisms including parasites and pathogens, how to select and maintain a beneficial microbial partner is a critical issue for host organisms. The bean bug Riptortus pedestris (Heteroptera: Alydidae) acquires a specific gut symbiont, Burkholderia insecticola, from environmental soil in the second instar stage and houses it in a crypt-bearing midgut region called M4. To sort the Burkholderia symbiont from a wide variety of soil microbes, R. pedestris develops a specialized organ named “constricted region (CR)”. The CR, located in front of the crypt-bearing symbiotic region, is immediately closed after colonization of M4 by the Burkholderia symbiont to block any contamination of microbes ingested with food. By using a food coloring and a red fluorescent protein (RFP)-expressing Burkholderia symbiont, we here revealed that the closed CR is re-opened at a later developmental stage of R. pedestris. Although the CR was re-opened at the late phase of the fifth instar, oral administration of food coloring and green fluorescent protein (GFP)-expressing symbiont demonstrated that ingested food and bacteria were stopped at the M4B despite the opened CR. Observations using confocal microscopy revealed reverse flow of gut content from M4 to M3 through the opened CR, the flow pressure of which seemed to prevent any contamination of the symbiotic M4 region. The morphological change of the CR with aging may cause a risk of contamination, but another mechanism, the reverse flow, plausibly maintains the specificity of gut symbiont in R. pedestris.

Synthesis and characterization of turmeric oil loaded non-ionic surfactant vesicles (niosomes) and its enhanced larvicidal activity against mosquito vectors

The fabrication of smart materials and its potential versatility instigated to develop Niosomes for sustained delivery of drugs. In this pursuit, in this research work, we have synthesized Niosomes using the transmembrane pH gradient method from turmeric oil and evaluated against mosquito vectors. The characteristics of niosomes were extensively explored by Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), Zeta Potential and others. FTIR analysis affirmed the formation of Niosomes from turmeric oils. Subsequently, the synthesized niosomes were observed in SEM to decipher the size and shape. DLS and Zeta Potential studies indicated that synthesized niosomes average particle size was around 491.09 nm with good stability. Functionally, the synthesized Niosomes were evaluated against third instar larvae of Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi . The outcome of the study demonstrated that niosomes exhibit effective mortality against the larvae in a dose-dependent method with significant Lethal Concentration (LC) values. Further, histopathological analysis of treated larvae implies that niosomes cause extensive damage in the midgut region and the collapse of internal membrane bodies. Overall, the comprehensive study of the synthesized niosomes from turmeric oil will be competent for the vector management program.

Green synthesis of silver nanoparticle using Leonotis nepetifolia and their toxicity against vector mosquitoes of Aedes aegypti and Culex quinquefasciatus and agricultural pests of Spodoptera litura and Helicoverpa armigera.

Pest insects causing damage to cultivable crops and food products by feeding, fecundity, and parasitizing livestock, also being a nuisance to human health. In consideration with human health, the World Health Organization reports that more than 50% of the world's population is presently at risk from mosquito-borne diseases. Mosquitoes are primary vectors for major dreadful diseases such as yellow fever, malaria, and dengue fever, which infect millions of human beings all over the world and kill millions of peoples every year. The present research work was carried out to evaluate the antifeedant, larvicidal, pupicidal, larval, and pupal duration activity of Leonotis nepetifolia-mediated silver nanoparticles (AgNPs) against Spodoptera litura, Helicoverpa armigera, Aedes aegypti, and Culex quinquefasciatus. Biosynthesized AgNPs were characterized through various techniques such as UV-Vis spectrometer, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. The AgNPs showed potential antifeedant activity of 78.77% and 82.16% against the larvae of S. litura and H. armigera, respectively. The maximum larval mortality rate (78.49% and 72.70%) and maximum pupal mortality rate (84.66% and 77.44%) were observed against S. litura and H. armigera. Mosquito larvae were tested with biosynthesized AgNPs, and recorded LC50 values were 47.44ppm and 35.48ppm on A. aegypti and C. quinquefasciatus, respectively. The histological examinations showed that the acceleration of the nanomaterial caused severe tissue damage in the epithelial and goblet cells in the larval midgut region of S. litura, H. armigera, A. aegypti, and C. quinquefasciatus. Biosynthesis of silver nanoparticles using L. nepetifolia is an ideal eco-friendly approach for the management of insect pests. Graphical abstract.

Characterization of the segmental transport mechanisms of DL-methionine hydroxy analogue along the intestinal tract of rainbow trout with an additional comparison to DL-methionine

The aim of this study was to identify the unknown transport mechanism of the extensively used monocarboxylate methionine feed supplement DL-methionine hydroxy analogue (DL-MHA) in rainbow trout intestine. Transport across the pyloric caeca (PC), midgut (MG), and hindgut (HG) regions were kinetically studied in Na+- and H+-dependent manners. Gene expression of monocarboxylate (MCTs) and sodium monocarboxylate transporters (SMCTs) were assessed. Results demonstrated that DL-MHA transport from 0.2‐20 mM was Na+-dependent and obeyed Michaelis-Menten kinetics with low affinity in PC & MG in apical/basal pH of 7.7/7.7. Changes in apical/basal pH (6.0/6.0, 6.0/7.7, and 7.7/8.7) had insignificant effects on kinetics. In contrast, HG flux kinetics were only obtained in pH 7.7/8.7 or in the presence of lactate with medium affinity. Additionally, DL-MHA transport from 0‐150 μM demonstrated the presence of a Na+-dependent high-affinity transporter in PC & MG. Conclusively, two distinct carrier-mediated DL-MHA transport mechanisms along the trout gut were found: 1) in PC & MG: apical transport was regulated by Na+-requiring systems that possibly contained low- and high-affinity transporters, and basolateral transport was primarily achieved through a H+-independent transporter; 2) in HG: uptake was apically mediated by a Na+-dependent transporter with medium affinity, and basolateral exit was largely controlled by an H+-dependent transporter. Finally, two major methionine feed supplements, DL-MHA and DL-methionine (DL-Met) were compared to understand the differences in their bioefficacy. Flux rates of DL-MHA were only about 42.2–66.0% in PC and MG compared to DL-Met, suggesting intestinal transport of DL-MHA was lower than DL-Met.

Metabarcoding Analyses of Gut Microbiota of Nile Tilapia (Oreochromis niloticus) from Lake Awassa and Lake Chamo, Ethiopia.

The Nile tilapia (Oreochromis niloticus) gut harbors a diverse microbial community; however, their variation across gut regions, lumen and mucosa is not fully elucidated. In this study, gut microbiota of all samples across gut regions and sample types (luminal content and mucosa) were analyzed and compared from two Ethiopian lakes. Microbiota were characterized using 16S rRNA Illumina MiSeq platform sequencing. A total of 2061 operational taxonomic units (OTUs) were obtained and the results indicated that Nile tilapia from Lake Chamo harbored a much more diversified gut microbiota than Lake Awassa. In addition, the gut microbiota diversity varied significantly across the gut region based on the Chao1, Shannon and Simpson index. The microbiome analyses of all samples in the midgut region showed significantly higher values for alpha diversity (Chao 1, Shannon and Simpson). Beta diversity analysis revealed a clear separation of samples according to sampling areas and gut regions. The most abundant genera were Clostridium_sensu_stricto and Clostridium_XI genera across all samples. Between the two sampling lakes, two phyla, Phylum Fusobacteria and Cyanobacteria, were found to be significantly different. On the other hand, six phyla (Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria and Cyanobacteria) were significantly different across gut regions. In this study, we found that all samples shared a large core microbiota, comprising a relatively large number of OTUs, which was dominated by Proteobacteria, Firmicutes, Cyanobacteria, Fusobacteria and Actinobacteria. This study has established the bases for future large-scale investigations of gut microbiota of fishes in Ethiopian lakes.

The Midgut Ultrastructure of the Sand Fly Vector, Phlebotomus Langeroni (Diptera: Psychodidae)

The midgut ultrastructure of Phlebotomus langeroni, the vector of visceral leismaniasis was studied by the transmission electron microscope. The midgut region warrants a special investigation since it is directly relevant to the development of Leishmania promastigotes. Observations performed on females at time-intervals following a bloodmeal were analyzed and compared. The epithelium of the midgut consisted of a single layer of columner cells surrounded by the basal lamina. Under which there is a musculature consisted of circular and longitudinal fibers. The cells were characterized by large nuclei, densely packed microvilli, and intricate basal labyrinth. The cytoplasm was filled with numerous mitochondria. Morphological changes occurred in the cellular structures during the blood digestion process. The peritrophic matrix was present up to 3 days after the bloodmeal and completely disintegrated at day 4 after bloodmeal. At day 6 after bloodmeal, lipid inclusions were few within the cell cytoplasm and vacuoles were depicted. At day 8, the area of the microvilli was greatly reduced probably due to reduced functional activity along with the end of the digestive cycle. The changes depicted in the midgut of P. langeroni during the process of blood digestion were comparable to those described for other hematophagous dipterans.

Leaf Extract of Dillenia indica as a Source of Selenium Nanoparticles with Larvicidal and Antimicrobial Potential toward Vector Mosquitoes and Pathogenic Microbes

Chikungunya, dengue, Zika, malaria, Japanese encephalitis, filariasis, West Nile, etc. are mosquito transmitted diseases that have killed millions of people worldwide, and millions of people are at risk of these diseases. Control of the mosquitoes, such as Aedes aegypti and Culex quinquefasciatus, is challenging due to their development of resistance to synthetic insecticides. The habitats of the young mosquitoes are also the habitats for foodborne pathogens like Staphylococcus aureus (MTCC96) and Serratia marcescens (MTCC4822). The present study was aimed at synthesizing eco-friendly green nanoparticles using Dillenia indica leaf broth and analyzing its efficacy in controlling the vector mosquitoes A. aegypti and C. quinquefasciatus, as well as the microbial pathogens St. aureus and Se. marcescens. The formation of selenium nanoparticles (SeNps) was confirmed using UV-Vis spectroscopy (absorption peak at 383.00 nm), Fourier transform infrared radiation (FTIR spectrum peaks at 3177, 2114, 1614, 1502, 1340, 1097, 901, 705, and 508 cm−1), X-ray diffraction (diffraction peaks at 23.3 (100), 29.6 (101), 43.5 (012), and 50.05 (201)), and scanning electron microscopy (oval shaped). The size of the nanoparticles and their stability were analyzed using dynamic light scattering (Z-Average value of 248.0 nm) and zeta potential (−13.2 mV). The SeNps disorganized the epithelial layers and have broken the peritrophic membrane. Histopathological changes were also observed in the midgut and caeca regions of the SeNPs treated A. aegypti and C. quinquefasciatus larvae. The SeNps were also active on both the bacterial species showing strong inhibitory zones. The present results will explain the ability of SeNps in controlling the mosquitoes as well as the bacteria and will contribute to the development of multi potent eco-friendly compounds.

Acute and chronic effects of polystyrene microplastics on brine shrimp: First evidence highlighting the molecular mechanism through transcriptome analysis

Microplastics contamination is one of the leading environmental catastrophes for the marine ecosystem, but the molecular toxicity mechanism of those microplastics remains elusive. This study aims to determine the acute and chronic toxicity after exposure to polystyrene microplastics in brine shrimp with various concentrations. Our results demonstrated that acute exposure to polystyrene microplastics induced no significant effects on the survival of brine shrimp. Interestingly, the concentration-dependent increase in both bioaccumulation and the generation of reactive oxygen species (ROS) was observed after acute and chronic exposure. Moreover, the histopathology analysis revealed the deformation of epithelial cells in the midgut region after both acute exposures at 100 mg/L and chronic exposure at 1 mg/L to polystyrene microplastics. To elucidate the underlying mechanisms of microplastics-mediated toxicity, the transcriptome analysis was performed after chronic exposure, and the result showed 721 differentially expressed genes (DEGs) associated with 156 known KEGG pathways. 292 DEGs genes were significantly upregulated and 429 genes were significantly downregulated. The transcriptome analysis further revealed the DEGs related pathways. Taken together, this study not only highlighted the negative effects but also provided detailed sequencing data from transcriptome profiling to enhance our understanding of the molecular toxicity of polystyrene microplastics in brine shrimp.

Mutation of amphioxus Pdx and Cdx demonstrates conserved roles for ParaHox genes in gut, anus and tail patterning

BackgroundThe homeobox genes Pdx and Cdx are widespread across the animal kingdom and part of the small ParaHox gene cluster. Gene expression patterns suggest ancient roles for Pdx and Cdx in patterning the through-gut of bilaterian animals although functional data are available for few lineages. To examine evolutionary conservation of Pdx and Cdx gene functions, we focus on amphioxus, small marine animals that occupy a pivotal position in chordate evolution and in which ParaHox gene clustering was first reported.ResultsUsing transcription activator-like effector nucleases (TALENs), we engineer frameshift mutations in the Pdx and Cdx genes of the amphioxus Branchiostoma floridae and establish mutant lines. Homozygous Pdx mutants have a defect in amphioxus endoderm, manifest as loss of a midgut region expressing endogenous GFP. The anus fails to open in homozygous Cdx mutants, which also have defects in posterior body extension and epidermal tail fin development. Treatment with an inverse agonist of retinoic acid (RA) signalling partially rescues the axial and tail fin phenotypes indicating they are caused by increased RA signalling. Gene expression analyses and luciferase assays suggest that posterior RA levels are kept low in wild type animals by a likely direct transcriptional regulation of a Cyp26 gene by Cdx. Transcriptome analysis reveals extensive gene expression changes in mutants, with a disproportionate effect of Pdx and Cdx on gut-enriched genes and a colinear-like effect of Cdx on Hox genes.ConclusionsThese data reveal that amphioxus Pdx and Cdx have roles in specifying middle and posterior cell fates in the endoderm of the gut, roles that likely date to the origin of Bilateria. This conclusion is consistent with these two ParaHox genes playing a role in the origin of the bilaterian through-gut with a distinct anus, morphological innovations that contributed to ecological change in the Cambrian. In addition, we find that amphioxus Cdx promotes body axis extension through a molecular mechanism conserved with vertebrates. The axial extension role for Cdx dates back at least to the origin of Chordata and may have facilitated the evolution of the post-anal tail and active locomotion in chordates.