Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis

Abstract. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v . 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.     

Human placental multipotent mesenchymal stromal cells modulate placenta angiogenesis through Slit2-Robo signaling

abstract

The objective of this study was to investigate whether human placental multipotent mesenchymal stromal cell (hPMSC)-derived Slit2 and endothelial cell Roundabout (Robo) receptors are involved in placental angiogenesis. The hPMSC-conditioned medium and human umbilical vein endothelial cells were studied for Slit2 and Robo receptor expression by immunoassay and RT-PCR. The effect of the conditioned medium of hPMSCs with or without Slit2 depletion on endothelial cells was investigated by in vitro angiogenesis using growth factor-reduced Matrigel. hPMSCs express Slit2 and both Robo1 and Robo4 are present in human umbilical vein endothelial cells. Human umbilical vein endothelial cells do not express Robo2 and Robo3. The hPMSC-conditioned medium and Slit2 recombinant protein significantly inhibit the endothelial cell migration, but not by the hPMSC-conditioned medium with Slit2 depletion. The hPMSC-conditioned medium and Slit2 significantly enhance endothelial tube formation with increased cumulated tube length, polygonal network number and vessel branching point number compared to endothelial cells alone. The tube formation is inhibited by the depletion of Slit2 from the conditioned medium, or following the expression of Robo1, Robo4, and both receptor knockdown using small interfering RNA. Furthermore, co-immunoprecipitation reveals Slit2 binds to Robo1 and Robo4. Robo1 interacts and forms a heterodimeric complex with Robo4. These results suggest the implication of both Robo receptors with Slit2 signaling, which is involved in endothelial cell angiogenesis. Slit2 in the conditioned medium of hPMSCs has functional effect on endothelial cells and may play a role in placental angiogenesis.     

Cell degeneration during early development of hymenopteran olfactory sensilla

The imaginal pore plates of Hymenoptera apocrita so far examined embody five or six envelope cells respectively. In early developmental stages, however, supernumerary envelope cells have been found. The results are discussed in the context of cell death as a developmental phenomenon.     

Sensory projections of identified coxal hair sensilla of the scorpionHeterometrus fulvipes (Scorpionidae)

The topography of long hair sensilla on the coxae of walking legs and pedipalps of the scorpionHeterometrus fulvipes is described. Identified long hair sensilla are cobalt filled, and central projections of sensory fibres are reported for the first time in the suboesophageal ganglion of this scorpion. The afferent fibres arising from each long hair sensilla segregate into ventral, dorsomedial and dorsal tracts upon their entry into the suboesophageal ganglion. These transverse tracts bifurcate towards the middle of the leg neuromere and form three ipsilateral, plurisegrnental, longitudinal sensory pathways. Filling a pair of bilaterally distributed long hair sensilla shows bilaterally arranged longitudinal afferent tracts interconnected by distinct transverse commissures. Similar patterns of sensory projections are observed when filling homologous hairs on other legs and pedipalps. Numerous fine collaterals arise from the longitudinal sensory trancts that subdivide and end in small blebs presumed to be presynaptic endings. The dorsal and dorsomedial longitudinal tracts and their respective commissures are in close association with the dendritic arborisations of pedipalpal and leg motor neurons, suggesting direct contact between them. The probable functions of these multisegmental hair afferent pathways are discussed.     

Anatomy of the antennal dorsal organ in female of Neodryinus typhlocybae (Hymenoptera: Dryinidae): A peculiar sensory structure possibly involved in perception of host vibration

Neodryinus typhlocybae (Hymenoptera: Dryinidae) is a natural enemy of the planthopper Metcalfa pruinosa, which was introduced from North America into Europe and has become established in various regions as a pest species. Vibrational signals play a crucial role in the communication of M. pruinosa, which appears to be exploited by N. typhlocybae. Scanning and transmission electron microscopy have shown that the antennae of N. typhlocybae females have peculiar and complex sensory structures: deep longitudinal grooves that house long sensilla trichodea, termed here “Antennal Dorsal Organs.” Such structures were not present on male antennae. These sensilla extend for the length of the grooves, without contact with the groove cuticle. Their hair shaft is empty and aporous, and inserted into a specialized socket, underneath which there is a cuticular ampulla‐like chamber. Each sensillum is associated with two sensory neurons: one terminates at the proximal end of the dendritic sheath; the other continues into the sensillum sinus and is enclosed in the dendritic sheath. This second sensory neuron then enters the ampulla‐like chamber through the circular opening, and then terminates with a conspicuous tubular body at the shaft base. The possible involvement of this peculiar structure in the context of host recognition mechanism is discussed. J. Morphol. 277:128–137, 2016. © 2015 Wiley Periodicals, Inc.     

Morphological and electrophysiological characteristics of the epipharyngeal sensilla of the silkworm, Bombyx mori

One pair of gustatory sensilla was found on the epipharynx ofBombyx mori larvae, and some morphological and electrophysiological characteristics of the epipharyngeal sensilla were investigated. They are sensilla coeloconica composed of a small papilla with a pore at the tip and a swelling of cuticle encircling the papilla. Three bipolar neurons innervate each sensillum. One neuron is an inositol receptor which responds to inositol only. Another cell responds with action potentials of relatively large amplitude to some feeding deterrent substances, such as strychnine nitrate. The thresholds of these cells for inositol and strychnine nitrate are approximately 10⁻⁴ M and 10⁻⁷ M, respectively. At least two kinds of spikes can be observed when these sensilla are stimulated with some salts and acids. Dose-response relationships and time courses of responses to inositol and strychnine nitrate were also examined in this study.     

Different sensitivities of the sugar receptor of the lateral styloconic sensillum in fourth- and sixth-instar larvae of the spruce budworm Choristoneura fumiferana

Female fourth- and sixth-instar larvae, Choristoneura fumiferana, were tested individually for the response of the sugar cell on the lateral styloconic sensillum to 25 mM/l concentrations of 12 carbohydrates. The spruce budworm showed an age-related change in responsiveness of the sugar cell. The order of stimulating effectiveness for fourth-instars was melibiose > sucrose > raffinose.These storage di- and trisaccharides are present in the host plant at the beginning of budbreak. Sixth-instars responded to sucrose > fructose> m-inositol. These findings are in accordance with those of a previous behavioural study on feeding preferences of sixth-instars. The response for both melibiose and raffinose does not change from fourth- to sixth-instars; however, it does for sucrose, fructose and m- inositol.     

Cleaved Slit directs embryonic muscles

The formation of functional musculoskeletal system relies on proper connectivity between muscles and their corresponding tendon cells. In Drosophila, larval muscles are born during early embryonic stages, and elongate toward tendons that are embedded within the ectoderm in later. The Slit/Robo signaling pathway had been implicated in the process of muscle elongation toward tendons. Here we discuss our recent findings regarding the critical contribution of Slit cleavage for immobilization and stabilization of the Slit signal on the tendon cells. Slit cleavage produces 2 polypeptides, the N-terminal Slit-N, which is extremely stable, undergoes oligomerization, and associates with the tendon cell surfaces, and the C-terminal Slit-C, which rapidly degrades. Slit cleavage leads to immobilization of Slit signaling on tendons, leading to a short-range repulsion, which eventually arrest further muscle elongation. Robo2, which is co-expressed with Slit by the tendon cells facilitates Slit cleavage. This activity does not require the cytoplasmic signaling domain of Robo2. We suggest that Robo2-dependent Slit cleavage, and the formation of Slit-N oligomers on the tendon cell surfaces direct muscle elongation, and provide a stop signal for the approaching muscle, through binding to Robo and Robo3 receptors expressed by the muscles.     

Tibial campaniform sensilla of Glossina morsitans

On the basis of behavioural tests and light microscopy, a pair of dome shaped sensilla occuring on the outer and inner surfaces of Glossina morsitans morsitans tibiae were considered to be sex pheromone receptors. Recent observations using electrophysiological tests and ultrastructural methods have revealed that those receptors have no olfactory function; they are ampaniform sensilla sensitive to mechanical stimulation.