Mineralized bodies in the fat body of rhinocricus padbergi (Diplopoda)

The fat body is a loosely packed tissue distributed throughout the body cavities of millipedes. The mainfunction of this tissue is the storage of lipids, glycogen, proteins and uric acid and also serves as a site forthe permanent storage for excretion products. In this work, we examined the ultrastructure of the mineralizedbodies found in the fat body of the millipede Rhinocricus padbergi. The mineralized bodies were sphericalbodies that varied in structural organization within a single cell: some consisted of several concentric layers ofamorphous material while others were surrounded by a layer of electron-dense material intimately associatedwith the surrounding membrane. The histochemical and ultrastructural results suggested that these mineralizedbodies are involved in the accumulation of calcium and uric acid. The large number of these structures foundin the fat body of millipedes may be a consequence of these animals´ diet since they overturn soil rich in largeamounts and/or variety of minerals. As in other organisms, uric acid probably accumulates as the metabolicproduct of the degradation of nucleic acids derived from autophagy of the rough endoplasmic reticulum duean earlier massive protein synthesis, but may also be extracted from the hemolymph.

Effects of deltamethrin pyrethroid on the respiratory metabolism of the neotropical spirostreptid millipedes Gymnostreptus olivaceus and Plusioporus setiger

The effects of deltamethrin on the respiratory metabolism of Gymnostreptus olivaceus and Plusioporus setiger were investigated. Acetone solutions corresponding to half the LD50 values, i.e., 20 mg.g-1 for G. olivaceus and 4.40 mg.g-1 for P. setiger, were used. Metabolism was determined with a Warburg respirometer at 25ºC. Respirometric measurements were performed 1, 3 and 6 hours after administration of the pyrethroid to the same groups of millipedes. After 24 hours, daily respirometric measurements lasting 1 hour each were made on different millipede groups for a period of 10 days. Significant differences were detected only between the groups treated with the pyrethroid and the two control groups. In G. olivaceus, respiratory rates increased by about 1.65-fold compared to normal immediately after administration of the pyrethroid, followed by a gradual decrease up to 72 hours and a return to normal levels thereafter. In P. setiger the increase was about 1.1-fold compared to normal, with a decrease up to 96 hours and a return to normal thereafter. Although increased oxygen consumption was observed, a detoxification process occurred in both species, so that the possible metabolism of the pyrethroid may justify the low toxicity of deltamethrin for G. olivaceus and P. setiger

External morphology of the antennae of Rhinocricus padbergi Verhoeff, 1938 (Diploda, Spirobolida)

The antennae of millipedes (Diplopoda) have an important role in detecting various types of enviromental stimuli. The structural organization of the antennae is closely related to the degree of sensorial perception. The antennae generally consist of eight segments, the most distal (apical) of which characteristically contains four cone-shaped sensilla. In this paper, we describe the external morphology of the antennae of the diplod Rhinocricus padbergi. Antennae from anesthetized mael and female millipedes were fixed in Karnovsky solution and processed for scanning electron microscopy. Intraspecific variation was observed in the number of apical cones (13-18) in segment VIII. This number of cones differed from that usually found (4) in other millipedes species. Segments I, II and III lacked sensilla while the remaining segments had different types of sensilla, including trichoidea, chaetica and basiconica. The presence of the latter types of sensilla suggests that R. padbergiantennae have chemoreceptor, mechanoreceptor and thermal/ hygrosensitive functions, respectively.