Autophagy is a natural process that aims to eliminate malfunctioning cell parts, organelles or molecules under physiological conditions. It is also induced in response to infection, starvation or oxidative stress to provide energy in case of an energy deficit. The aim of this 2-dimensional study was to test if, and if so, how, this process depends on the concentration of cadmium in food (with Cd concentrations from 0 to 352 μg of Cd per g of food (dry weight)—D1 dimension) and the history of selection pressure (160 vs 20 generations of exposure to Cd—D2 dimension). For the study, the 5th instar larvae of a unique strain of the moth Spodoptera exigua that was selected for cadmium tolerance for 160 generations (44 μg of Cd per g of food (dry weight)), as well as 20-generation (11, 22 and 44 μg of Cd per g of food (dry weight)) and control strains, were used. Autophagy intensity was measured by means of flow cytometry and compared with life history parameters: survivability and duration of the 3rd larval stage. The highest values of autophagy markers were found in the groups exposed to the highest Cd concentration and corresponded (with a significant correlation coefficient) to an increased development duration or decreased survivorship in the respective groups. In conclusion, autophagy is probably initiated only if any other defense mechanisms, e.g., antioxidative mechanisms, are not efficient. Moreover, in individuals from pre-exposed populations, the intensity of autophagy is lower.

The neuroendocrine system of insects, including the presence of the main neuroactive compounds, and their role in ontogenesis are probably best understood of all the arthropods. Development, metamorphosis, the maturation of the gonads, vitellogenesis and egg production are regulated by hormones (juvenile hormones, ecdysteroids) and neuropeptides. However, knowledge about their presence and functions in spiders is fragmentary. In this paper, we present a summary of the current data about the juvenile hormones, ecdysteroids and neuropeptides in selected groups of arthropods, with particular emphasis on spiders. This is the first article that takes into account the occurrence, action and role of hormones and neuropeptides in spiders. In addition, the suggestions for possible ways to study these compounds in Araneomorphae spiders are unique and cannot be found in the arachnological literature.

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Background Knowledge about vitellogenesis in spiders is rudimentary. Therefore, the aim of study was to check the vitellogenin (Vg) presence in various tissues of the female spider Parasteatoda tepidariorum , determine when and where vitellogenesis starts and takes place, and the putative role of selected hormones in the vitellogenesis. Results Here we show two genes encoding Vg (Pt Vg 4 and Pt Vg 6) in the genome of the spider P. tepidariorum . One gene Pt Vg 4 and three subunits of Vg (250 kDa, 47 kDa and 30 kDa) are expressed in the midgut glands, ovaries and hemolymph . Heterosynthesis of the Vg in the midgut glands and autosynthesis in the ovaries were observed. Vitellogenesis begins in the last nymphal stage in the midgut glands (heterosynthesis). However, after sexual maturity is reached, Vg is also synthesized in the ovaries (autosynthesis). Changes in the Pt Vg 4 expression level and in the Vg concentration after treatment with 20-hydroxyecdysone, a juvenile hormone analog (fenoxycarb) and an antijuvenoid compound (precocene I) were observed. Therefore, we propose a hypothetical model for the hormonal regulation of vitellogenesis in P. tepidariorum . Conclusions Our results are the first comprehensive study on spider vitellogenesis. In our opinion, this work will open discussion on the evolutionary context of possible similarities in the hormonal control of vitellogenesis between P. tepidariorum and other arthropods as well as their consequences.

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