Minor impact of probiotic bacteria and egg white on Tenebrio molitor growth, microbial composition, and pathogen infection

The industrial rearing of the yellow mealworm (Tenebrio molitor) for feed and food purposes on agricultural by-products may expose larvae and adults to entomopathogens used as biocontrol agents in crop production. Bacterial spores/toxins or fungal conidia from species such as Bacillus thuringiensis or Metarhizium brunneum could affect the survival and growth of insects. Therefore, the aim of this study was to investigate the potential benefits of a wheat bran diet supplemented with probiotic bacteria and dried egg white on larval development and survival and its effects on the gut microbiome composition. Two probiotic bacterial species, Pediococcus pentosaceus KVL B19-01 and Lactiplantibacillus plantarum WJB, were added to wheat bran feed with and without dried egg white, as an additional protein source, directly from neonate larval hatching until reaching a body mass of 20 mg. Subsequently, larvae from the various diets were exposed for 72 h to B. thuringiensis, M. brunneum, or their combination. Larval survival and growth were recorded for 14 days, and the bacterial microbiota composition was analyzed using 16S rDNA sequencing prior to pathogen exposure and on days 3 and 11 after inoculation with the pathogens. The results showed increased survival for T. molitor larvae reared on feed supplemented with P. pentosaceus in the case of co-infection. Larval growth was also impacted in the co-infection treatment. No significant impact of egg white or of P. pentosaceus on larval growth was recorded, while the addition of Lb. plantarum resulted in a minor increase in individual mass gain compared with infected larvae without the latter probiotic. On day 14, B. thuringiensis was no longer detected and the overall bacterial community composition of the larvae was similar in all treatments. On the other hand, the relative operational taxonomic unit (OTU) abundance was dependent on day, diet, and probiotic. Interestingly, P. pentosaceus was present throughout the experiments, while Lb. plantarum was not found at a detectable level, although its transient presence slightly improved larval performance. Overall, this study confirms the potential benefits of some probiotics during the development of T. molitor while underlining the complexity of the relationship between the host and its microbiome.

Effect of CO2 Concentrations on Entomopathogen Fitness and Insect-Pathogen Interactions

Numerous insect species and their associated microbial pathogens are exposed to elevated CO2 concentrations in both artificial and natural environments. However, the impacts of elevated CO2 on the fitness of these pathogens and the susceptibility of insects to pathogen infections are not well understood. The yellow mealworm, Tenebrio molitor, is commonly produced for food and feed purposes in mass-rearing systems, which increases risk of pathogen infections. Additionally, entomopathogens are used to control T. molitor, which is also a pest of stored grains. It is therefore important to understand how elevated CO2 may affect both the pathogen directly and impact on host-pathogen interactions. We demonstrate that elevated CO2 concentrations reduced the viability and persistence of the spores of the bacterial pathogen Bacillus thuringiensis. In contrast, conidia of the fungal pathogen Metarhizium brunneum germinated faster under elevated CO2. Pre-exposure of the two pathogens to elevated CO2 prior to host infection did not affect the survival probability of T. molitor larvae. However, larvae reared at elevated CO2 concentrations were less susceptible to both pathogens compared to larvae reared at ambient CO2 concentrations. Our findings indicate that whilst elevated CO2 concentrations may be beneficial in reducing host susceptibility in mass-rearing systems, they may potentially reduce the efficacy of the tested entomopathogens when used as biological control agents of T. molitor larvae. We conclude that CO2 concentrations should be carefully selected and monitored as an additional environmental factor in laboratory experiments investigating insect-pathogen interactions.

Effect of the rearing diet on gene expression of antimicrobial peptides in Hermetia illucens (Diptera: Stratiomyidae)

Insect proteins have been proposed for human and animal food production. Safeguarding the health status of insects in mass rearing allows to obtain high-quality products and to avoid severe economic losses due to entomopathogens. Therefore, new strategies for preserving insect health must be implemented. Modulation of the insect immune system through the diet is one such strategy. We evaluated gene expression of two antimicrobial peptides (one defensin and one cecropin) in Hermetia illucens (L.) (Diptera: Stratiomyidae) reared on different diets. Analyses were performed on prepupae and 10-day-old larvae reared on cereal- and municipal organic waste-based diets and on only prepupae reared on a cereal-based diet supplemented with sunflower, corn, or soybean oil. The inclusion of sunflower oil at different points in the cereal-based diet was also evaluated. Moreover, diet-driven differences in the inhibitory activity of the hemolymph were tested against Escherichia coli DH5α and Micrococcus yunnanensis HI55 using diffusion assays in solid media. Results showed that a municipal organic waste-based diet produced a significant overexpression of antimicrobial peptides only in prepupae. Inclusion of vegetable oils caused an upregulation of at least one peptide, except for the corn oil. Higher expression of both genes was observed when sunflower oil was added 5 days before pupation. All hemolymph samples showed an inhibitory activity against bacteria colonies. Our results suggest that municipal organic waste-based diet and vegetable oil-added diet may successfully impact the immune system of H. illucens. Such alternatives may also exist for other species of economic interest.

Bugs in Bugs: The Role of Probiotics and Prebiotics in Maintenance of Health in Mass-Reared Insects

Simple Summary

The importance of insect farming is increasing in the livestock market by evolving into a form of intensive production that is often characterized by a high density of individuals kept in closed environments. These conditions can cause a higher risk of occurrence of insect diseases and the lowering of reproductive and growth performances. The role of microbiota composition in insect behaviour and health maintenance could be further studied for selecting microorganisms that act as probiotics for the main mass reared insect species. These probiotics could enhance host performances and reduce the incidence of risks related to insect diseases.

Abstract

Interactions between insects and their microbiota affect insect behaviour and evolution. When specific microorganisms are provided as a dietary supplement, insect reproduction, food conversion and growth are enhanced and health is improved in cases of nutritional deficiency or pathogen infection. The purpose of this review is to provide an overview of insect–microbiota interactions, to review the role of probiotics, their general use in insects reared for food and feed, and their interactions with the host microbiota. We review how bacterial strains have been selected for insect species reared for food and feed and discuss methods used to isolate and measure the effectiveness of a probiotic. We outline future perspectives on probiotic applications in mass-reared insects.

Facial templates: a new perspective in three dimensions

PURPOSE

This paper describes the use of adult facial template in gender-specific facial analysis.

SUBJECTS AND METHODS

Eighty adults, mean age 24.5, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. The differences in facial morphology were measured using shell deviation colour maps. The facial template was used to compare differences between males vs. females groups and two subjects with facial disproportions.

RESULTS

The difference between the male and female facial templates was 1.28 +/- 1.02 mm. The areas of greatest deviation were at the nasal, zygomatic area and lower jaw line. The results of the surface deviation maps between the templates and subjects with facial disproportion showed that the results could be applied for orthodontic diagnosis.

CONCLUSIONS

The construction of the adult facial templates provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of skeletal disproportion.

Radiographic evaluation of teeth subjected to high temperatures: experimental study to aid identification processes

The radiographic evaluation of dental remains represents a significant aspect in the forensic identification process, particularly after an exposure to fire. The aim of this "in vitro" study was to evaluate the radiographic features of unrestored, endodontically treated and restored teeth after exposure to an experimental range of high temperatures. Ninety human teeth were divided into two groups: (1) unrestored teeth, as a control group and (2) teeth endodontically treated (condensation technique) and restored with amalgam or composite fillings. Before testing the high temperatures, periapical radiographs of all teeth were performed. The tests of exposure to heat were carried out in an oven for six different temperatures (200, 400, 600, 800, 1000 and 1100 degrees C (392, 752, 1112, 1472, 1832, 2012 degrees F)). After each exposure, periapical radiographs of all the teeth were taken. The radiographic appearance of all the teeth before and after the thermal stresses were evaluated and the differences were recorded. The results of the radiographic examination showed that a number of significant radiographic details were conserved: the composite fillings were in place maintaining the shape till 600 degrees C (1112 degrees F), the amalgam fillings were in place maintaining the shape till 1000 degrees C (1832 degrees F) and the endodontic treatments were recognisable till 1100 degrees C (2012 degrees F).

Expression of late myogenic differentiation markers in sarcoplasmic masses of patients with myotonic dystrophy

Sarcoplasmic masses contain disorganized myofibrillar material and are a striking feature of myotonic dystrophy. However their significance is still unclear. Using immunocytochemistry we studied the expression of cytoskeletal proteins (desmin and vimentin), dystrophin, markers of myogenic differentiation (foetal myosin, neural cell adhesion molecule, bcl-2, insulin-like growth factor-I, fibroblast growth factor, retinoblastoma protein and myoD1), cell cycle regulators (Cdk2, p16, p27 and p57) and muscle proteases (ubiquitin, micro and m calpain and cathepsin D) in muscle biopsies from four patients with myotonic dystrophy. Sarcoplasmic masses were strongly positive for desmin, neural cell adhesion molecule, bcl-2, insulin-like growth factor I, retinoblastoma protein and p57, weakly positive for dystrophin and p16 and negative for vimentin, fibroblast growth factor, myoD1, Cdk2 and p27. Immunoreactivity for foetal myosin was detected only in a few fibres (< 1%). Our data suggest that the late myogenic differentiation programme is activated in sarcoplasmic masses although these areas do not reach complete maturation.

Expression of protein kinase C isoforms and interleukin-1beta in myofibrillar myopathy

BACKGROUND

The term myofibrillar myopathy refers to a rare and clinically heterogeneous group of muscle disorders. The pathogenesis of this myopathy is not well understood. The morphologic hallmark is myofibrillar destruction with abnormal expression of numerous proteins, most consistently of desmin.

METHODS

The authors investigated eight patients with myofibrillar myopathy belonging to four families. They studied the role of different protein kinase C isoforms and of interleukin-1beta, a cytokine that might activate protein kinase C and, in addition, mediate myofibrillar proteolysis.

RESULTS

Immunohistochemical analysis showed the expression of alpha, eta, and zeta isoforms of protein kinase C and of interleukin-1beta in abnormal muscle fibers. Immunoblots confirmed the immunohistochemical data and revealed the absence of protein kinase C delta and epsilon in muscle fibers from patients and controls.

CONCLUSIONS

These data suggest that protein kinase C and interleukin-1beta may play a role in the pathogenesis of myofibrillar myopathy.

Transcription factors c-Jun/activator protein-1 and nuclear factor-kappa B in oxidative stress response in mitochondrial diseases

Mitochondrial dysfunction leads to oxygen free radical (ROS) generation with consequent oxidative stress and cellular damage. Recently, activation of the cellular antioxidant system and apoptosis were demonstrated in skeletal muscle fibres from patients with mitochondrial diseases, but the underlying mechanisms remain unknown. Hydrogen peroxide, a by-product of ROS generation, is a chemical inducer of gene expression able to activate apoptosis and to promote the antioxidant response through the activation of nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1) transcription factor. Using immunohistochemistry and confocal microscopy, we evaluated the expression of NF-kappaB and AP-1 in muscle biopsies from patients with mitochondrial disease. In addition, we examined the expression of factors involved in their activation, such as NF-kappaB inducing kinase (NIK) and phosphorylated Jun-N-terminal kinase (p-JNK). Most fibres with respiratory chain dysfunction displayed nuclear staining for activated c-Jun/AP-1, but not for NF-kappaB. The same fibres reacted for p-JNK. Only some ragged red fibres immunoreacted for NIK. These data suggest that AP-1 is involved in the oxidative stress response in muscle fibres from patients with mitochondrial disease.

Observations on dental prostheses and restorations subjected to high temperatures: experimental studies to aid identification processes

In large scale disasters associated with fire the damage caused by heat can make medico-legal identification of human remains difficult. Teeth, restorations and prostheses, all of which are resistant to even quite high temperatures can be used as aids in the identification process. In this project the behaviour and morphology of teeth and dental prostheses exposed to a range of high temperatures was studied. Healthy teeth, dental restorations and prostheses were placed in a furnace and heated at a rate of 30 degrees C/min and the effects of the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined by stereomicroscopy and scanning electron microscopy (SEM). Our observations show that some prostheses and restorative materials resist higher temperatures than theoretically predictable and that even when a restoration is lost because of detachment or change of state its ante-mortem presence can be confirmed and detected by both stereomicroscopic examination and SEM of the residual cavity. We further conclude that a reasonably reliable estimation of the temperature of exposure can be made from an analysis of the teeth and restorative materials.

Chk2 activation dependence on Nbs1 after DNA damage

The checkpoint kinase Chk2 has a key role in delaying cell cycle progression in response to DNA damage. Upon activation by low-dose ionizing radiation (IR), which occurs in an ataxia telangiectasia mutated (ATM)-dependent manner, Chk2 can phosphorylate the mitosis-inducing phosphatase Cdc25C on an inhibitory site, blocking entry into mitosis, and p53 on a regulatory site, causing G(1) arrest. Here we show that the ATM-dependent activation of Chk2 by gamma- radiation requires Nbs1, the gene product involved in the Nijmegen breakage syndrome (NBS), a disorder that shares with AT a variety of phenotypic defects including chromosome fragility, radiosensitivity, and radioresistant DNA synthesis. Thus, whereas in normal cells Chk2 undergoes a time-dependent increased phosphorylation and induction of catalytic activity against Cdc25C, in NBS cells null for Nbs1 protein, Chk2 phosphorylation and activation are both defective. Importantly, these defects in NBS cells can be complemented by reintroduction of wild-type Nbs1, but neither by a carboxy-terminal deletion mutant of Nbs1 at amino acid 590, unable to form a complex with and to transport Mre11 and Rad50 in the nucleus, nor by an Nbs1 mutated at Ser343 (S343A), the ATM phosphorylation site. Chk2 nuclear expression is unaffected in NBS cells, hence excluding a mislocalization as the cause of failed Chk2 activation in Nbs1-null cells. Interestingly, the impaired Chk2 function in NBS cells correlates with the inability, unlike normal cells, to stop entry into mitosis immediately after irradiation, a checkpoint abnormality that can be corrected by introduction of the wild-type but not the S343A mutant form of Nbs1. Altogether, these findings underscore the crucial role of a functional Nbs1 complex in Chk2 activation and suggest that checkpoint defects in NBS cells may result from the inability to activate Chk2.

Cell-specific differences in the regulation of IL-6 expression by PMA

We have studied the regulation of IL-6 expression in human blood monocytes and lymphocytes. LPS and IFN-gamma induced IL-6 gene expression with a similar qualitative profile in both cell types. Treatment of monocytes and lymphocytes with PMA resulted, instead, in different effects: monocytes accumulated IL-6 and its message, while lymphocytes were inhibited either in the absence or the presence of LPS and IFN-gamma. These results suggest that the signal transduction pathways triggered by LPS and IFN-gamma are similar in both cell types, while PMA may activate a tissue-specific pathway which leads to opposite responses.