Silkworm larval midgut: a striking example of tissue remodeling.

openBombyx mori is a pivotal model organism among Lepidoptera, a group of insects that is important for both commercial and agronomic purposes. The study of midgut development during larval period and metamorphosis is helpful to obtain a background useful for many applications concerning these contexts. In these insects, metamorphosis involves a series of highly ordered mechanisms and passes through a well-defined sequence of events to eliminate tissues and organs that are functional only in larval stages (Meléndez and Neufeld, 2008). In Lepidoptera, midgut tissue undergoes extensive remodelling (Vilaplana et al., 2007) during the development and these modifications lead to cell death of the larval epithelium and to its replacement with a new pupal epithelium, which becomes the adult midgut epithelium. For this reason midgut remodelling has been chosen as preferential model to study cell death mechanisms and regeneration processes, and their regulation. In particular, although features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two cell death processes and the nature of their relationship are still cryptic. In order to analyze the remodelling processes in B. mori midgut tissues during larvaladult transformation, we performed a morpho-functional analysis at different developmental stages. In addition, we accomplished a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut, with the aim to analyze autophagy and apoptosis in cells that dye under physiological conditions. We found that stem cells proliferate actively since the wandering stage, leading to the formation of a new pupal midgut which is progressively remodelled until adult ecdysis. Larval midgut cells undergo progressive degradation, forming a compact mass called yellow body, that progressively degenerates inside the lumen of the new pupal midgut and finally disappears. Through histochemical analysis we showed marked changes in metabolic activity in both larval and pupal epithelium at different stages of the midgut renewal process. We demonstrated that larval midgut degradation is a gradual process due to the concerted action of autophagic and apoptotic mechanisms, which occur at different times and have different functions. In particular, autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages. Our data showed also that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells.openAnalisi, Protezione e Gestione delle BiodiversitàFranzetti, EleonoraFranzetti, Eleonor

Similar effectiveness of dapagliflozin and GLP-1 receptor agonists concerning combined endpoints in routine clinical practice: A multicentre retrospective study

Aims According to cardiovascular outcome trials, some sodium-glucose contransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) are recommended for secondary cardiovascular prevention in type 2 diabetes (T2D). In this real-world study, we compared the simultaneous reductions in HbA1c, body weight and systolic blood pressure after initiation of dapagliflozin or GLP-1RA as second or a more advanced line of therapy. Materials and methods DARWIN-T2D was a retrospective multi-centre study conducted at diabetes specialist clinics in Italy that compared T2D patients who initiated dapagliflozin or GLP-1RA (exenatide once weekly or liraglutide). Data were collected at baseline and at the first follow-up visit after 3 to 12 months. The primary endpoint was the proportion of patients achieving a simultaneous reduction in HbA1c, body weight and systolic blood pressure. To reduce confounding, we used multivariable adjustment (MVA) or propensity score matching (PSM). Results Totals of 473 patients initiating dapagliflozin and 336 patients initiating GLP-1RA were included. The two groups differed in age, diabetes duration, HbA1c, weight and concomitant medications. The median follow-up was 6 months in both groups. Using MVA or PSM, the primary endpoint was observed in 30% to 32% of patients, with no difference between groups. Simultaneous reduction of HbA1c, BP and SBP by specific threshold, as well as achievement of final goals, did not differ between groups. GLP-1RA reduced HbA1c by 0.3% more than the reduction achieved with dapagliflozin. Conclusion In routine specialist care, initiation of dapagliflozin can be as effective as initiation of a GLP-1RA for attainment of combined risk factor goals

Weight gain: A possible side effect of all antiretrovirals

Weight gain and body mass index (BMI) increase are central issues in patients living with HIV who need to minimize the risk of metabolic disease. Information collected through the SCOLTA cohort revealed significant 1-year BMI increase in patients treated with dolutegravir (P = .004), raltegravir (P = .0004), elvitegravir (P = .004), darunavir (P = .0006), and rilpivirine (P = .029). BMI gain correlated with low baseline BMI (P = .002) and older age (P = .0007) in Centers for Disease Control and Prevention stages A/B, with lower BMI (P = .005) and CD4+ T-cell count (P = .007) at enrollment in stage C

Prevalence of hepatic steatosis in patients with type 2 diabetes and response to glucose-lowering treatments. A multicenter retrospective study in Italian specialist care

Type 2 diabetes (T2D) is a risk factor for metabolic dysfunction-associated fatty liver disease (MAFLD), which is becoming the commonest cause of chronic liver disease worldwide. We estimated MAFLD prevalence among patients with T2D using the hepatic steatosis index (HSI) and validated it against liver ultrasound. We also examined whether glucose-lowering medications (GLM) beneficially affected HSI

A Molecular View of Autophagy in Lepidoptera

Metamorphosis represents a critical phase in the development of holometabolous insects, during which the larval body is completely reorganized: in fact, most of the larval organs undergo remodeling or completely degenerate before the final structure of the adult insect is rebuilt. In the past, increasing evidence emerged concerning the intervention of autophagy and apoptosis in the cell death processes that occur in larval organs of Lepidoptera during metamorphosis, but a molecular characterization of these pathways was undertaken only in recent years. In addition to developmentally programmed autophagy, there is growing interest in starvation-induced autophagy. Therefore we are now entering a new era of research on autophagy that foreshadows clarification of the role and regulatory mechanisms underlying this self-digesting process in Lepidoptera. Given that some of the most important lepidopteran species of high economic importance, such as the silkworm, Bombyx mori, belong to this insect order, we expect that this information on autophagy will be fully exploited not only in basic research but also for practical applications

In vitro effects of microbiologically characterized Milan particulate matter

AbstractMilan is one of the biggest cities in Italy characterized by a heavy automotive traffic. Air pollution is a deal of concern owing to the high concentration of particulate matter (PM10 and PM2.5) registered all over the year. Existing epidemiological data suggest an impact of PM on human health; however, experimental data on the biological effects of PM are still poorly investigated. In vitro results obtained after exposure to PM10 and PM2.5 sampled in Milan during winter and summer are reported here. PMs were characterized for their chemical and microbiological composition and tested to evaluate their potential toxicity in the human pulmonary cell line A549 and in the monocytes cell line THP-1. The chemical and microbiological analysis showed an evident seasonality in PM properties. Interestingly summer PMs contains mainly gram negative bacterial population while winter PMs gram positive, spore forming and possibly pathogenic, bacteria. PMs triggered different biological responses which are possibly related to the sampling season. Summer PMs elicited a higher pro-inflammatory potential that correlates to the high content of gram negative bacteria as detected by the microbiological characterization. On the other hand the winter PMs are able to induce cell cycle arrest, disrupting the normal microtubule organization in mitotic cells. The results obtained underline that the chemical properties of the PM are only in part responsible for the biological responses, since the biological components are of primary importance triggering endpoints such as inflammation

The midgut of the silkmoth Bombyx mori is able to recycle molecules derived from degeneration of the larval midgut epithelium

The midgut represents the middle part of the alimentary canal and is responsible for nutrient digestion and absorption in insect larva. Despite the growing interest in this organ for different purposes, such as studies on morphogenesis and differentiation, stem cell biology, cell death processes and transport mechanisms, basic information on midgut development is still lacking for a large proportion of insect species. Undoubtedly, this lack of data could hinder the full exploitation of practical applications that involve midgut as their primary target. This may represent in particular a significant problem for Lepidoptera, an insect order that includes some of the most important species of high economic importance. With the aim of overcoming this fragmentation of knowledge, we performed a detailed morphofunctional analysis of the midgut of the silkworm, Bombyx mori, a representative model among Lepidoptera, during its development from the larval up to the adult stage, focusing attention on stem cells. Our data demonstrate stem cell proliferation and differentiation, not only in the larval midgut but also in the pupal and adult midgut epithelium. Moreover, we present evidence for a complex trophic relationship between the dying larval epithelium and the new adult one, which is established during metamorphosis. This study, besides representing the first morphological and functional characterization of the changes that occur in the midgut of a lepidopteron during the transition from the larva to the moth, provides a detailed analysis of the midgut of the adult insect, a stage that has been neglected up to now

Midgut microbiota and host immunocompetence underlie Bacillus thuringiensis killing mechanism

Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced nodulation response, which was associated with a significant enhancement of host larvae mortality triggered by B. thuringiensis and a Cry toxin. This was determined by an uncontrolled proliferation of midgut bacteria, after entering the body cavity through toxin-induced epithelial lesions. Consequently, the hemolymphatic microbiota dramatically changed upon treatment with Cry1Ca toxin, showing a remarkable predominance of Serratia and Clostridium species, which switched from asymptomatic gut symbionts to hemocoelic pathogens. These experimental results demonstrate the important contribution of host enteric flora in B. thuringiensis-killing activity and provide a sound foundation for developing new insect control strategies aimed at enhancing the impact of biocontrol agents by reducing the immunocompetence of the host

Characterization of the microbial community in ripened Pecorino Toscano cheese affected by pink discoloration

Pink discoloration defect can cause economic losses for cheese producers due to the impossibility to sell the defected cheese, but few knowledge is currently available on the causes of this defect. To gain more insight on the causes that lead to the formation of pink discoloration in Pecorino Toscano cheese with the Protected Designation of Origin (PDO) status, the bacterial community in defected and not defected cheese was characterized by high-throughput sequencing of bacterial 16S rRNA gene. The bacterial community in the defected cheese significantly differed compared to the control. The relative abundance of the genera Acidipropionibacterium, Enterococcus, Escherichia/Shigella, Lactobacillus, Lentilactobacillus and Propionibacterium was higher in the cheese with pink discoloration defect. The concentration of short chain fatty acids and of lactic acid in cheese was measured and a shift towards the production of propionate in the cheese with pink discoloration defect was observed. Furthermore, the possible involvement of microbially produced vitamin B12 in the formation of pink discoloration was not supported by the data, since a tendency to a lower concentration of vitamin B12 was measured in the defected cheese compared to the control

A Virulence Factor Encoded by a Polydnavirus Confers Tolerance to Transgenic Tobacco Plants against Lepidopteran Larvae, by Impairing Nutrient Absorption

<div><p>The biological control of insect pests is based on the use of natural enemies. However, the growing information on the molecular mechanisms underpinning the interactions between insects and their natural antagonists can be exploited to develop “bio-inspired” pest control strategies, mimicking suppression mechanisms shaped by long co-evolutionary processes. Here we focus on a virulence factor encoded by the polydnavirus associated with the braconid wasp <i>Toxoneuron nigriceps</i> (<i>Tn</i>BV), an endophagous parasitoid of noctuid moth larvae. This virulence factor (<i>Tn</i>BVANK1) is a member of the viral ankyrin (ANK) protein family, and appears to be involved both in immunosuppression and endocrine alterations of the host. Transgenic tobacco plants expressing <i>Tn</i>BVANK1 showed insecticide activity and caused developmental delay in <i>Spodoptera littoralis</i> larvae feeding on them. This effect was more evident in a transgenic line showing a higher number of transcripts of the viral gene. However, this effect was not associated with evidence of translocation into the haemocoel of the entire protein, where the receptors of <i>Tn</i>BVANK1 are putatively located. Indeed, immunolocalization experiments evidenced the accumulation of this viral protein in the midgut, where it formed a thick layer coating the brush border of epithelial cells. <i>In vitro</i> transport experiments demonstrated that the presence of recombinant <i>Tn</i>BVANK1 exerted a dose-dependent negative impact on amino acid transport. These results open new perspectives for insect control and stimulate additional research efforts to pursue the development of novel bioinsecticides, encoded by parasitoid-derived genes. However, future work will have to carefully evaluate any effect that these molecules may have on beneficial insects and on non-target organisms.</p></div