Alterations in biogenic amines levels associated with age-related muscular tissue impairment in Drosophila melanogaster.

While holding on youth may be a universal wish, aging is a natural process associated with physical and physiological impairment in living organisms. Drosophila provides useful insights into aging-related events. Hence, this study was conducted to investigate the age-related changes in muscle function and architecture in relation to the biogenic amine titers. To achieve this aim, visceral and skeletal muscles performance was tested in newly-eclosed, sexually mature and old adult flies using climbing and gut motility assays. In addition, age-related ultrastructural alterations of muscular tissue were observed using transmission electron microscopy (TEM). The titer of selected biogenic amines was measured using high-performance liquid chromatography (HPLC). The results demonstrated that old flies were dramatically slower in upward movement than either newly-eclosed or sexually mature flies. Similarly, gut contraction rate was significantly lower in old flies than the sexually mature, although it was markedly higher than that in the newly-eclosed flies. In TEM examination, there were several ultrastructural changes in the midgut epithelium, legs and thorax muscles of old flies. Regarding biogenic amine titers, the old flies had significantly lower concentrations of octopamine, dopamine and serotonin than the sexually mature. We concluded that aging has adverse effects on muscular system function and ultrastructure, synchronized with biogenic amine titers changes. Our results highlighted the need for more researches on therapeutics that may balance the levels of age-related alterations in biogenic amines.

Drosophila melanogaster as a low-cost and valuable model for studying type 2 diabetes.

Drosophila melanogaster has been used as the most successful invertebrate model for studying metabolic diseases such as type 2 diabetes (T2D). We induced T2D by feeding Drosophila larvae on a high-sugar diet (HSD). The glucose and trehalose, glycogen, lipid, triglyceride, and protein levels were determined in HSD-fed larvae. Moreover, larval food intake, water content, size, and weight in addition to the development until pupation were observed. Levels of Drosophila insulin-like peptides (DILPs 2, 3, and 5), as well as adipokinetic hormone (AKH), were also determined in HSD-fed larvae by quantitative real-time polymerase chain reaction. The results demonstrated that HSD could induce elevated levels of glucose, trehalose, glycogen, and proteins in larvae. The larvae consumed less food intake and were smaller, lighter, and less developed on HSD than those on the control diet. Moreover, the water content of larvae fed HSD was similar to that fed the control diet. HSD induced higher expression of DILP3 and AKH, confirming hyperglycemia with insulin resistance. In sum, Drosophila offers an appropriate model for quick and inexpensive in vivo experimentation on human metabolic diseases.

Reduced fitness of the mosquito Culex pipiens (Diptera: Culicidae) after feeding on a blood meal with hepatitis C virus.

Hepatitis C virus (HCV) is a blood-borne virus. Given that mosquitoes can take blood meals from HCV patients, we aimed to test whether HCV in the blood meal can induce alterations in the biology of Culex pipiens. To address this aim, Cx. pipiens females were fed HCV-negative blood from healthy individuals or HCV-positive fresh blood samples harvested from viremic HCV patients. Replication of HCV in mosquitoes was confirmed by negative strand-specific RT-PCR and sequencing of RNA extracted from the mosquito bodies 7 days post-feeding. In addition, several parameters that determine the fitness of the mosquitoes were measured. Virus acquisition was associated with alterations in the architecture of the gut microvilli and the immune response, indicated by an increase in phenol oxidase activity. Interestingly, the mosquitoes that were fed the HCV-positive blood meal showed shorter median longevity (8 days) and laid fewer eggs than the control mosquitoes. Furthermore, the offspring of females fed the HCV-positive blood meal demonstrated a lower emergence rate than the controls. In sum, the results indicate that feeding on HCV by Cx. pipiens decreases fitness, which may, in turn, affect its potential as a vector.