Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure

Earthworms Use Odor Cues to Locate and Feed on Microorganisms in Soil

Earthworms are key components of temperate soil ecosystems but key aspects of their ecology remain unexamined. Here we elucidate the role of olfactory cues in earthworm attraction to food sources and document specific chemical cues that attract Eisenia fetida to the soil fungi Geotrichum candidum. Fungi and other microorganisms are major sources of volatile emissions in soil ecosystems as well as primary food sources for earthworms, suggesting the likelihood that earthworms might profitably use olfactory cues to guide foraging behavior. Moreover, previous studies have documented earthworm movement toward microbial food sources. But, the specific olfactory cues responsible for earthworm attraction have not previously been identified. Using olfactometer assays combined with chemical analyses (GC-MS), we documented the attraction of E. fetida individuals to filtrate derived from G. candidum colonies and to two individual compounds tested in isolation: ethyl pentanoate and ethyl hexanoate. Attraction at a distance was observed when barriers prevented the worms from reaching the target stimuli, confirming the role of volatile cues. These findings enhance our understanding of the mechanisms underlying key trophic interactions in soil ecosystems and have potential implications for the extraction and collection of earthworms in vermiculture and other applied activities

Differential Effects of Serotonin Enhance Activity of an Electrically Coupled Neural Network

Networks of electrically coupled neurons play an important role in coordinating activity among widely distributed neurons in the CNS. Such networks are sensitive to neuromodulation; but how modulation of individual cells affects activity of the entire network is not well understood. In the CNS of the medicinal leech, the S interneuron (S-cell) forms a network of electrically coupled neurons where each S-cell is linked to its two neighboring S-cells by electrical synapses. An action potential initiated in one cell is carried the length of the animal along this S-cell chain. The S-cell network is of interest because it is crucial for sensitization and dishabituation of the whole-body shortening reflex, although it is not necessary for reflexive shortening itself. Mechanosensory stimuli that produce shortening will directly elicit a train of action potentials by the S-cell network. This activity reflects the sum of action potential initiations in several S interneurons within the chain. The activity was enhanced by serotonin (5HT) in terms of both the total number of action potentials initiated and the average frequency of these initiations. Increases in evoked activity were accompanied by differential changes in the rates of action potential initiation in individual S-cells. 5HT only weakly enhanced initiations in S-cells that made a large contribution to the network-level response, while initiations in other, less active, S-cells were strongly enhanced by 5HT. This neurotransmitter also modulated the pattern of how activity was distributed throughout the network. 5HT-induced changes in activity patterns of the S-cell network may represent an important component of learning-related neuroplasticity in the leech shortening reflex