The insulin signaling pathway in Drosophila melanogaster: A nexus revealing an "Achilles' heel" in DDT resistance

PEPCK and glucose metabolism homeostasis in arthropods

The fat body is responsible for a variety of functions related to energy metabolism in arthropods, by controlling the processes of de novo glucose production (gluconeogenesis) and glycogen metabolism. The rate-limiting factor of gluconeogenesis is the enzyme phosphoenolpyruvate carboxykinase (PEPCK), generally considered to be the first committed step in this pathway. Although the study of PEPCK and gluconeogenesis has been for decades restricted to mammalian models, especially focusing on muscle and liver tissue, current research has demonstrated particularities about the regulation of this enzyme in arthropods, and described new functions. This review will focus on arthropod PEPCK, discuss different aspects to PEPCK regulation and function, its general role in the regulation of gluconeogenesis and other pathways. The text also presents our views on potentially important new directions for research involving this enzyme in a variety of metabolic adaptations (e.g. diapause), discussing enzyme isoforms, roles during arthropod embryogenesis, as well as involvement in vector-pathogen interactions, contributing to a better understanding of insect vectors of diseases and their control.

Exposure of chlorothalonil and acetamiprid reduce the survival and cause multiple internal disturbances in Apis mellifera larvae reared in vitro

Background: Chlorothalonil and acetamiprid are chemical pesticides commonly used in agricultural production and have been shown to have negative effects on bee's fitness. Despite many studies have revealed that honey bee (Apis mellifera L.) larvae are posting a high risk on exposure to pesticides, but the toxicology information of chlorothalonil and acetamiprid on bee larvae remain limited. Results: The no observed adverse effect concentration (NOAEC) of chlorothalonil and acetamiprid for honey bee larvae were 4 μg/mL and 2 μg/mL, respectively. Except for CarE, the enzymic activities of GST and P450 were not influenced by chlorothalonil at NOAEC, while chronic exposure to acetamiprid slightly increased the activities of the three tested enzymes at NOAEC. Further, the exposed larvae showed significantly higher expression of genes involved in a series of different toxicologically relevant process following, including caste development (Tor (GB44905), InR-2 (GB55425), Hr4 (GB47037), Ac3 (GB11637) and ILP-2 (GB10174)), immune system response (abaecin (GB18323), defensin-1 (GB19392), toll-X4 (GB50418)), and oxidative stress response (P450, GSH, GST, CarE). Conclusion: Our results suggest that the exposure to chlorothalonil and acetamiprid, even at concentrations below the NOAEC, showed potentially effects on bee larvae's fitness, and more important synergistic and behavioral effects that can affect larvae fitness should be explored in the further.

FOXO acts as a positive regulator of CncC and deltamethrin tolerance in the red flour beetle, Tribolium castaneum

BACKGROUND

Both forkhead box O (FOXO) and nuclear factor erythroid-derived 2-like-2 (Nrf2) are key transcription factors related to stress responses. Whereas limited studies in mammals and Caenorhabditis elegans have revealed the interaction between FoxO/DAF-16 and Nrf2/SKN-1, the role of FOXO in metabolic detoxification and regulation of the Nrf2-Keap1 signaling pathway are poorly understood in insects.

RESULTS

Using Tribolium castaneum as a model organism, we found that RNA interference-mediated knockdown of FOXO enhanced deltamethrin-induced lethality by affecting the messenger RNA (mRNA) levels of CYP6BQ cluster genes. We further demonstrated that injection of dsFOXO into the beetle larvae decreased expression of CncC and KEAP1 at both the mRNA and protein level. Notably, dual-luciferase and electrophoretic mobility shift assays both confirmed direct regulation of CncC by FOXO, whereas Keap1 was directly regulated by CncC.

CONCLUSION

FOXO can directly regulate the expression of CncC and indirectly regulate the expression of Keap1 through CncC. The data provide insights into the regulatory mechanisms of the Nrf2-Keap1 signaling pathway in insects.

Hawthorn extract inhibited the PI3k/Akt pathway to prolong the lifespan of Drosophila melanogaster

HE is a natural extract with strong antioxidant capacity. Drosophila melanogaster was used to explore HE could delay aging in this study. We detected that 3 mg/ml HE could increase stress tolerance (heat, cold, starvation, oxidative stress), reduce intestinal dysfunction, and prolong the lifespan of D. melanogaster. Network pharmacology analysis showed HE could act through the PI3K-Akt pathway. Meanwhile, HE intervention inhibited the gene expression of InR, PI3K, and Akt-1, and further increased the gene expression of Atg1, Atg5, Atg8a, and Atg8b. Furthermore, HE inhibited the unnatural propagation of ISCs and increased the number of lysosomes. Supplement with HE may be an effective intervention for aging D. melanogaster. PRACTICAL APPLICATIONS: In recent years, diseases that come with aging have seriously affected people's healthy life. Hawthorn is a kind of nutrient-rich substance that is rich in flavonoids and thus has many potential biological and pharmacological functions. Our results showed that HE has good antioxidant properties and can maintain intestinal homeostasis, which provides a good theoretical basis for the development and research using HE as an effective natural antioxidant for the elderly.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.