Immunometabolic regulation during the presence of microorganisms and parasitoids in insects

Multicellular organisms live in environments containing diverse nutrients and a wide variety of microbial communities. On the one hand, the immune response of organisms can protect from the intrusion of exogenous microorganisms. On the other hand, the dynamic coordination of anabolism and catabolism of organisms is a necessary factor for growth and reproduction. Since the production of an immune response is an energy-intensive process, the activation of immune cells is accompanied by metabolic transformations that enable the rapid production of ATP and new biomolecules. In insects, the coordination of immunity and metabolism is the basis for insects to cope with environmental challenges and ensure normal growth, development and reproduction. During the activation of insect immune tissues by pathogenic microorganisms, not only the utilization of organic resources can be enhanced, but also the activated immune cells can usurp the nutrients of non-immune tissues by generating signals. At the same time, insects also have symbiotic bacteria in their body, which can affect insect physiology through immune-metabolic regulation. This paper reviews the research progress of insect immune-metabolism regulation from the perspective of insect tissues, such as fat body, gut and hemocytes. The effects of microorganisms (pathogenic bacteria/non-pathogenic bacteria) and parasitoids on immune-metabolism were elaborated here, which provide guidance to uncover immunometabolism mechanisms in insects and mammals. This work also provides insights to utilize immune-metabolism for the formulation of pest control strategies

Bmserpin2 Is Involved in BmNPV Infection by Suppressing Melanization in Bombyx mori

Melanization, an important defense response, plays a vital role in arthropod immunity. It is mediated by serine proteases (SPs) that convert the inactive prophenoloxidase (PPO) to active phenoloxidase (PO) and is tightly regulated by serine protease inhibitors (serpins) which belong to a well distributed superfamily in invertebrates, participating in immune mechanisms and other important physiological processes. Here, we investigated the Bmserpin2 gene which was identified from a transcriptome database in response to Bombyx mori nucleopolyhedrovirus (BmNPV) infection. Quantitative real-time polymerase chain reaction (qRT-PCR) results showed that Bmserpin2 was expressed in all tissues, with maximum expression in fat body. Upon BmNPV infection, the expression of Bmserpin2 was up-regulated in P50 (susceptible strain) and BC9 (resistant strain) in haemocytes, fat body and the midgut. However, up-regulation was delayed in BC9 (48 or 72 h), in contrast to P50 (24 h), after BmNPV infection. Meanwhile, Bmserpin2 could delay or inhibit melanization in silkworm haemolymph. Significant increased PO activity can be observed in Bmserpin2-depleted haemolymph under NPV infection. Furthermore, the viral genomic DNA copy number was decreased in Bmserpin2-depleted haemolymph. We conclude that Bmserpin2 is an inducible gene which might be involved in the regulation of PPO activation and suppressed melanization, and have a potential role in the innate immune system of B. mori

The RNA-seq approach to discriminate gene expression profiles in response to Beauveria bassiana and Micrococcus luteus microbial pathogens on Actias selene (Lepidoptera: Saturniidae)

Liang, Dan, Wang, Pei, Wu, Lingling, Jiang, Xiaoli, Wei, Guoqing, Zhu, Aojian, Wang, Lei, Zhang, Heyu, Toufeeq, Shahzad, Qian, Cen, Liu, Chaoliang (2019): The RNA-seq approach to discriminate gene expression profiles in response to Beauveria bassiana and Micrococcus luteus microbial pathogens on Actias selene (Lepidoptera: Saturniidae). Zootaxa 4591 (1): 1-71, DOI: 10.11646/zootaxa.4591.1.

Prospects of Poikelocercus pictus (Orthoptera: Acrididae) as an alternative protein source for Rhode Island Red chicken

Objectives: Insects have great potential as an alternative nutrient source in animal feed, fisheries, and poultry industries for sustainable development. Poikelocercus pictus (PP) is an edible grasshopper that has a high percentage of crude protein; thus, we evaluated it as an alternative protein source for Rhode Island Red (RIR) chicken. Methods: We fed RIR chicken on a commercial diet (control) and PP diets: T1 (PP meal throughout the trial, T2 (PP diet for the last 30 days of the trial), T3 (PP diet for the last 15 days of the trial). We maintained eight RIR chickens in four groups each with six replications. Results: Feed analysis indicated significantly higher crude protein levels (P < 0.05) in the PP diet than in the commercial diet. The feeding trial showed that PP diet feeding for 15 days did not record a significant difference with control for feed intake, food conversion ratio (FCR), and growth. RIR chicken demonstrated significantly higher feed intake and gained higher weight when fed on the PP diet as compared to the control (P < 0.05). Maximum FCR was observed when chickens were fed the PP diet for 45 days (3.21 ± 0.03). Conclusion: Our study indicated that the grasshopper species, Poikelocercus pictus, might serve as a protein source in poultry feed. Our results suggest that PP diets could replace or be used as a partial substitute for conventional plant-based protein sources in poultry feed

FIGURE 9 in The RNA-seq approach to discriminate gene expression profiles in response to Beauveria bassiana and Micrococcus luteus microbial pathogens on Actias selene (Lepidoptera: Saturniidae)

FIGURE 9. Larva and adult of Actias selene

FIGURE 7 in The RNA-seq approach to discriminate gene expression profiles in response to Beauveria bassiana and Micrococcus luteus microbial pathogens on Actias selene (Lepidoptera: Saturniidae)

FIGURE 7. RT-qPCR analysis of 11 immune-related DEGs in ML vs. PBS group. The y-axis shows relative expression levels (Blue colour represents the PBS control group and yellow colour represents the M. luteus treatment group, * p <0.05, **p <0.01)

DNA Methylation Is Correlated with Gene Expression during Diapause Termination of Early Embryonic Development in the Silkworm (Bombyx mori)

DNA modification is a naturally occurring DNA modification in prokaryotic and eukaryotic organisms and is involved in several biological processes. Although genome-wide methylation has been studied in many insects, the understanding of global and genomic DNA methylation during insect early embryonic development, is lacking especially for insect diapause. In this study, we analyzed the relationship between DNA methylomes and transcriptomes in diapause-destined eggs compared to diapause-terminated eggs in the silkworm, Bombyx mori (B. mori). The results revealed that methylation was sparse in this species, as previously reported. Moreover, methylation levels in diapause-terminated eggs (HCl-treated) were 0.05% higher than in non-treated eggs, mainly due to the contribution of CG methylation sites. Methylation tends to occur in the coding sequences and promoter regions, especially at transcription initiation sites and short interspersed elements. Additionally, 364 methylome- and transcriptome-associated genes were identified, which showed significant differences in methylation and expression levels in diapause-destined eggs when compared with diapause-terminated eggs, and 74% of methylome and transcriptome associated genes showed both hypermethylation and elevated expression. Most importantly, Kyoto Encyclopaedia of Genes and Genomes (KEGG) analyses showed that methylation may be positively associated with Bombyx mori embryonic development, by regulating cell differentiation, metabolism, apoptosis pathways and phosphorylation. Through analyzing the G2/M phase-specific E3 ubiquitin-protein ligase (G2E3), we speculate that methylation may affect embryo diapause by regulating the cell cycle in Bombyx mori. These findings will help unravel potential linkages between DNA methylation and gene expression during early insect embryonic development and insect diapause