The third form electric organ discharge of electric eels

The electric eel is a unique species that has evolved three electric organs. Since the 1950s, electric eels have generally been assumed to use these three organs to generate two forms of electric organ discharge (EOD): high-voltage EOD for predation and defense and low-voltage EOD for electrolocation and communication. However, why electric eels evolved three electric organs to generate two forms of EOD and how these three organs work together to generate these two forms of EOD have not been clear until now. Here, we present the third form of independent EOD of electric eels: middle-voltage EOD. We suggest that every form of EOD is generated by one electric organ independently and reveal the typical discharge order of the three electric organs. We also discuss hybrid EODs, which are combinations of these three independent EODs. This new finding indicates that the electric eel discharge behavior and physiology and the evolutionary purpose of the three electric organs are more complex than previously assumed. The purpose of the middle-voltage EOD still requires clarification.

Highly selective and high-performance osmotic power generators in subnanochannel membranes enabled by metal-organic frameworks

The electric organs of electric eels are able to convert ionic gradients into high-efficiency electricity because their electrocytes contain numerous “subnanoscale” protein ion channels that can achieve highly selective and ultrafast ion transport. Despite increasing awareness of blue energy production through nanochannel membranes, achieving high-performance energy output remains considerably unexplored. Here, we report on a heterogeneous subnanochannel membrane, consisting of a continuous UiO-66-NH2 metal-organic framework (MOF) and a highly ordered alumina nanochannel membrane. In the positively charged membrane, the angstrom-scale windows function as ionic filters for screening anions with different hydrated sizes. Driven by osmosis, the subnanochannel membrane can produce an exceptionally high Br−/NO3− selectivity of ~1240, hence yielding an unprecedented power of up to 26.8 W/m2 under a 100-fold KBr gradient. Achieving ultrahigh selective and ultrafast osmotic transport in ion channel–mimetic MOF-based membranes opens previously unexplored avenues toward advanced separation technologies and energy-harvesting devices.

DIALEKTIKA KESENIAN JARANAN THEK DI PONOROGO DENGAN AGAMA ISLAM

Agama Islam senantiasa berinteraksi dengan kebudayaan lokal. Di antara kesenian yang berinteraksi dan berdialektika dengan ajaran agama Islam adalah kesenian Jaranan Thek di Ponorogo. Keunikan dari kesenian Jaranan Thek ini adalah para pemain dan pawang yang memainkan Jaranan Thek menggunakan unsur magis dan kadang tidak sadar (trance), padahal mereka secara formal menganut agama Islam. Oleh karena itu, penelitian ini sangat penting dalam mengkaji fenomena Jaranan Thek yang hingga kini tetap eksis dan bagaimana para pelaku kesenian ini mendealektikakannya dengan ajaran agama Islam. Penelitian kualitatif (dengan observasi, wawancara mendalam, dan dokumentasi) ini menganalisis sejarah kesenian Jaranan Thek, strategi pelestarian, dan dialektikanya dengan Islam. Jaranan Thek di Ponorogo terkait dengan Kerajaan Kediri dan Kerajaan Bantarangin (Ponorogo). Demi pelestarian Jaranan Thek, maka komunitas kesenian ini berinovasi, yakni menyisipkan kisah Kelono Sewandono (dari Kerajaan Bantarangin) dengan Dewi Songgolangit (dari Kerajaan Kediri); menambahkan variasi lagu (shalawatan, tembang Jawa, Campursari, maupun lagu populer di masyarakat); menggunakan alat musik modern (misalnya, drum dan organ elektrik) sambil mempertahankan gamelan; menggabungkan Jaranan Thek dengan kesenian lain (misalnya, tari tayuban dan jathilan); dan menyelaraskannya dengan ajaran Islam (misalnya, doa, ayat, maupun lafadh bernuansa Islam). Dialektika Jaranan Thek dengan Islam terwujud secara mencolok dalam bentuk sinkretisme setelah unsur-unsur keislaman dimasukkan dalam pementasan Jaranan Thek. [Islam always interacts with the local culture. Among of the arts that interact and dialectic with Islamic teachings is the art of Jaranan Thek in Ponorogo. The uniqueness of this Jaranan Thek art is that the players and handlers who play Jaranan Thek use magical elements and are sometimes unconscious (trance), even though they formally adhere to Islam. Therefore, this research is very important in examining the phenomenon of Jaranan Thek, which still exists today and how the actors of this art treat it with Islamic teachings. This qualitative research (with observations, in-depth interviews, and documentation) analyzes the history of Jaranan Thek, its conservation strategy, and its dialectic with Islam. The Jaranan Thek's art in Ponorogo related to the Kingdom of Kediri and the Kingdom of Bantarangin (Ponorogo) because Jaranan Thek's art was from Jaranan art in Kediri. There are many innovations to preserve Jaranan Thek, such as inserting the story of Kelono Sewandono (from Bantarangin Kingdom) with Dewi Songgolangit (from Kediri Kingdom); performing various songs (with shalawatan, Javanese song, Campursari, and popular songs); using modern musical instruments (drums and electric organs) besides gamelan (traditional music instruments); combining Jaranan Thek with other arts (tayuban and jathilan), and synchronizing Jaranan Thek with Islam (Islamic prayers, verses, and sayings). The dialectic of Jaranan Thek with Islam appears prominently in its syncretism with Islamic elements in its performance.]

Descripción y comparación de la línea lateral de tres especies de rayas eléctricas del género Narcine (Torpediniformes: Narcinidae)

Description and comparison of the lateral line of three species of electric rays of the genus Narcine (Torpediniformes: Narcinidae). This study describes the composition and structural arrangement of the lateral line system of three electric ray species (Narcine bancroftii, N. entemedor and N. vermiculatus). All three species showed the supraorbital (SO), infraorbital (IO), hyomandibular (HYO) and posterior lateral line (PLL) canals, less branched compared to other batoids. Narcine entemedor differs from its congeners by the extensive branching of the SO and IO canals, which converge in the inter-orbital region; in N. vermiculatus these canals present a similar condition, but are less branched. In contrast, N. bancroftii has divergent canals (directed outwards from the inter-orbital region). HYO canals are located on the periphery of the electric organs in these species; in N. bancroftii the branches extend towards the posterior region, whereas in the other species are reduced (N. entemedor) or almost absent (N. vermiculatus). The PLL is curved and projected towards the urostyle, it also shows a large number of ramifications, except in N. vermiculatus. Information about the LL canal system arrangement and pore number in Narcine can be useful for the taxonomic distinction of its species, as it has been corroborated in other Torpediniformes. Rev. Biol. Trop. 66(2): 586-592. Epub 2018 June 01.

The diet of the coffin ray, Hypnos monopterygius (Shaw, 1795), and predation mode inferred from jaw, dentition and electric organ morphology

The diet of the coffin ray, Hypnos monopterygius (Family Hypnidae), an electric ray endemic to Australia, was described on the basis of stomach contents analysis. Benthos-associated teleost fishes and cephalopod molluscs, predominantly Octopus, dominated the diet. The large, paired electric organs of this species scaled close to isometrically in relation to body mass for electric-organ area and electric-organ mass. The number of electrocyte columns that comprise each electric organ (mean=435 columns) was independent of body mass. Jaws were long and slender, and supported small tricuspidate teeth only on the central 55% of their length. Diet, electric-organ size and jaw morphology in Hypnos and the torpedoes (Family Torpedinidae) are similar, but in marked contrast to members of the numbfishes (Family Narcinidae). The differences are interpreted in relation to the use of electric-organ discharge while foraging in the former families.