Chordotonal organs in hemipteran insects: unique peripheral structures but conserved central organization revealed by comparative neuroanatomy

Hemipteran insects use sophisticated vibrational communications by striking body appendages on the substrate or by oscillating the abdominal tymbal. There has been, however, little investigation of sensory channels for processing vibrational signals. Using sensory nerve stainings and low invasive confocal analyses, we demonstrate the comprehensive neuronal mapping of putative vibration-responsive chordotonal organs (COs) in stink bugs (Pentatomidae and Cydinidae) and cicadas (Cicadidae). The femoral CO (FCO) in stink bugs consists of ventral and dorsal scoloparia, homologous to distal and proximal scoloparia in locusts, which are implicated in joint movement detection and vibration detection, respectively. The ligament of the dorsal scoloparium is distally attached to the accessory extensor muscle, whereas that of the ventral scoloparium is attached to a specialized tendon. Their afferents project to the dorso-lateral neuropil and the central region of the medial ventral association center (mVAC) in the ipsilateral neuromere, where presumed dorsal scoloparium afferents and subgenual organ afferents are largely intermingled. In contrast, FCOs in cicadas have decreased dorsal scoloparium neurons and lack projections to the mVAC. The tymbal CO of stink bugs contains four sensory neurons that are distally attached to fat body cells via a ligament. Their axons project intersegmentally to the dorsal region of mVACs in all neuromeres. Together with comparisons of COs in different insect groups, the results suggest that hemipteran COs have undergone structural modification for achieving faster signaling of resonating peripheral tissues. The conserved projection patterns of COs suggest functional importance of the FCO and subgenual organ for vibrational communications

Photoelectron Current Density Emitted from GEOTAIL Spacecraft in Low-density Plasma Estimated from Measurements of Spacecraft Potential and Ambient Plasma

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Egg-Cracking Vibration as a Cue for Stink Bug Siblings to Synchronize Hatching

カメムシの卵が一斉に孵化する巧妙なメカニズムを発見 --ある卵が割れた振動を合図にきょうだいの卵が孵化する--. 京都大学プレスリリース. 2018-12-28.Egg clutches of many animals hatch synchronously due to parental control [1, 2] or environmental stimulation [3, 4]. In contrast, in some animals, embryos actively synchronize their hatching timing with their siblings to facilitate adaptive behavior in sibling groups, such as mass migration [5, 6]. These embryos require synchronization cues that are detectable from eggs and indicative of when the siblings hatch, such as pre-hatching vocalizations in birds and crocodiles [7, 8]. Previous studies, using methods including artificial presentation of non-specific mechanical stimuli, demonstrated that vibrations or other mechanical forces caused by sibling movements are cues used by some turtles and insects [9, 10, 11, 12, 13]. However, there is no evidence about which movements of tiny embryos or hatchlings, among multiple possibilities, can generate mechanical cues actually detectable through eggs. Here, we show that embryos of the brown marmorated stink bug, Halyomorpha halys, synchronize hatching by responding to single pulsed vibrations generated when siblings crack open their eggshells. An egg-cracking vibration seems to be transmitted to distant eggs within a clutch while still maintaining its function as a cue, thus leading to the highly synchronized hatching pattern previously reported [14]. In this species, it is possible that embryos attempt to hatch with short lags after earlier-hatched siblings to avoid egg cannibalism by them [14]. The present study illustrates the diversity of social-information use by animal embryos for success in the sibling group

White-skinned sweet potato (Ipomoea batatas L.) acutely suppresses postprandial blood glucose elevation by improving insulin sensitivity in normal rats

Long-term administration of Ipomoea batatas L. (white-skinned sweet potato, WSSP) has been reported to help manage type 2 diabetes mellitus (T2DM) in humans and animals; however, the mechanisms of blood glucose regulation by WSSP remain unclear. Therefore, we aimed to investigate the acute effects of WSSP on blood glucose homeostasis under normal conditions and the underlying mechanisms. Three fractions of WSSP (≤10, 10–50, and >50 kDa) were obtained via ultracentrifugation. Rats were subjected to an oral glucose tolerance test (OGTT) after a single administration of WSSP. The insulin tolerance test (ITT) and pyruvate tolerance test (PTT) were performed to evaluate insulin sensitivity and gluconeogenesis, respectively. Single WSSP administration markedly reduced blood glucose levels as revealed by the OGTT. Serum insulin levels were not increased by WSSP treatment. Blood glucose levels during ITT were significantly reduced due to WSSP treatment. WSSP treatment activated the phosphorylation of Akt, thereby activating insulin signaling in the skeletal muscles and liver. The ≤10 kDa fraction considerably reduced blood glucose levels per the OGTT and ITT. In contrast, gluconeogenesis in PTT and the expression of key enzymes in hepatocytes were suppressed by the >50 kDa fraction. This study demonstrated that WSSP acutely reduced postprandial blood glucose levels by improving insulin sensitivity in skeletal muscles in normal rats, which was attributed to constituents with a molecular weight of ≤10 kDa. Moreover, WSSP treatment suppressed gluconeogenesis in the liver, for which constituents of >50 kDa were responsible. Thus, WSSP can acutely regulate blood glucose homeostasis via multiple mechanisms. Since postprandial hyperglycemia leads to the onset of T2DM, WSSP, as a functional food, may possess potential active compounds that prevent T2DM