Trace element changes during hibernation of Drosophila melanogaster by WDXRF analyses at chilling temperature

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Abstract

Fruit flies (Drosophila melanogaster) were exposed to low temperature (4 °C, 3d), after controlled acclimation (15 °C, 1d) and passed to artificial hibernation. The concentrations of elements in almost 1000 mature flies were measured by Wavelength-Dispersive X-ray Fluorescence (WDXRF) spectrometry. Concentration changes of Zn, K, S, Ca (33.5%, 11.2%, 10.3% and 7.5%, respectively) and especially Cr and Mn (99.90 and 99.60) were observed. Concentrations of Cr, Zn, S and Ca increased significantly, but concentrations of Mn and K decreased in with comparison to the control group.

Introduction

Elements have three important functions (osmotic, structural, and biochemical) in occurring of metabolic activities in all living organisms. For example, they participate in the formation of several enzymes by binding to specific proteins as prosthetic group (cofactor) and moreover also in the formation of NADP and ATP, which have important roles in energy metabolism and redox reactions [1].

Chromium (Cr) can affect carbohydrate and lipid metabolism through its association with insulin in mammals. It plays also a role in nucleic acid metabolism and protein synthesis [2]. Manganese (Mn) activates numerous enzymes. It is a catalyst in the synthesis of fatty acids and cholesterol, and plays a part in protein, carbohydrate and fat production and can help nourish the nerves and brain. Zinc (Zn) plays a role in many metabolic functions including the normal absorbtion and function of vitamins. It helps to bind enzymes to substrates and may modify the molecular shape of enzymes by simultaneously combining with amino acids at different places on the protein, thus affecting secondary, tertiary and quaternary protein structure. In addition to its function in enzymes, Zn participates in the metabolism of nucleic acids and the synthesis of proteins. Similarly, sulfur (S) is needed for protein synthesis, while Iron (Fe) is an integral part of many respiratory chain proteins. Phosphorus (P) is needed for nucleic acid synthesis, and the production of important cofactors such as ATP and NADP. Potassium is needed for electrolyte balance and activation of many enzymes. Calcium (Ca) is essential for neuronal communication, intracellular transport of signals and has a occurring of osmotic balance in tissues and cells.

The advent of commercially available wavelength dispersive spectrometers for X-ray fluorescence (WDXRF) measurements has provided an economical and powerful tool for environmental, clinical, chemical, geological and industrial analysis. XRF is a non-destructive, fast, multi-element technique for analyzing the surface layer and determining major, as well minor or trace elements in thin and thick samples of all sizes and forms. Although X-ray spectrometry measurement is simple for a quantitative study, accurate quantitative measurements often depend on matrix correction procedures which require a large number of standards. One of the major problems posed by geological materials is the sample preparation. Since the beginning of the application of WDXRF technique as an analytical tool, a great deal of research has been done in mineralogical and biological materials by different workers [3], [4], [5], [6].

Karabulut et al. [7] had reported, by using EDXRF technique, that there may be association between the determination of species and Ni concentrations levels. Woodruff and Nikitin [8] showed that in somatic cells, P element movement affects the lifespan in Drosophila melanogaster.

Hibernation is described that condition, especially of mammals and insects, of passing the winter in a torpid state in which the body temperature drops nearly to freezing and metabolism drops close to zero. Moreover, it has been reported that several enzyme activities change before [9] and these events are controlled by hormones [10].

When the above findings occur come together, it is thought that there may be a powerful association between hibernation and elements. We hypothesized that WDXRF technique can be useful to determine the association in flies.

We report here the presence of an association between hibernation of D. melanogaster and some elements (especially Cr, and Mn).

Section snippets

Apparatus

The following instrumental contents were used: Wavelength-dispersive spectrometer (Rigaku ZSX-100e with Rhodium target X-ray controlled by a Software ZSX computer).

Results and discussion

Fig. 1a and b show the spectra obtained within 1 h. The average concentrations found for different elements in the samples are listed in Table 2.

The purpose of the research was to investigate the changes of trace elements in hibernation of D. melanogaster. We measured by WDXRF concentrations of P, S, K, Ca, Cr, Mn, Fe and Zn in flies exposed to chilling temperatures and in control group flies (Fig. 2, Fig. 3, Fig. 4). From these results, we showed that changing of Cr and Mn were the highest, and

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