New species of glass knifefish genus Eigenmannia (Gymnotiformes: Sternopygidae) with comments on the morphology and function of the enlarged cephalic lateral-line canals of Sternopygidae

A new species of Eigenmannia is described from the Rio Paraná (the Grande, Paranapanema and Tietê basins). This new species is distinguished from all congeners by colouration pattern, position of the mouth, relative depth of posterodorsal expansion on infraorbitals 1 + 2, number of teeth, osteological features, number of rows of scales above lateral line (LL) and morphometric data. Comments on the widened cephalic lateral-line canals of Sternopygidae and a dichotomous key to the species of Eigenmannia from the Rio Paraná Basin are provided.     

Dural Mast Cells: Source of Contaminating Histamine in Analyses of Mouse Brain Histamine Levels

Abstract: Histamine levels were determined in mouse brains from WBB6F₁- +/+ (mast cell normal) and WBB6F₁- W/W^v (mast cell-deficient) mice whose brains were dissected immediately after decapitation or after freezing the severed heads in liquid nitrogen for 10 s. In WBB6F₁-+/+ mice, brains obtained from frozen heads contained significantly higher levels of histamine than those obtained from unfrozen heads. The converse was found in brains obtained from the WBB6F₁- W/W^v mice. When CF-1 mice (which also contain brain-associated mast cells) were treated as described above, results very similar to those found with the WBB6F₁- +/+ mice were obtained. Further, the high levels of histamine found in CF-1 mice whose brains had been frozen in situ were accompanied by an extensive degranulation of mast cells in the dura mater of these mice. Because of this degranulation of mast cells, and the fact that increased levels of brain histamine were not found in mast cell-deficient mice, it is concluded that dural mast cells are the likely source of the artifactually higher levels of histamine seen in brains frozen in situ.     

Mechanoresponsive neurones in the suboesophageal ganglion of the locust

Abstract. A preparation is described for intracellular recording from the neur-opile of the sub-oesophageal ganglion (SOG) of the locust, while stimulating the labial and maxillary palps with plant material in such a way as to mimic the palpation behaviour which precedes and continues throughout feeding. Twelve neurones responding to simulated palpation were recorded from and stained in the SOG. Axons of three neurones ascended to the brain, six had descending axons and three had all of their processes confined to the suboesophageal ganglion. The major regions of arborization were in the ventrolateral and mediolateral neuropiles of the maxillary and labial neuromeres. All twelve neurones were solely mechanoresponsive. In addition to responding to palpation of one or more of the four palps, five also responded to stimulation of the labrum, one to touching each antenna, and one to mechanical stimulation of each of the six tarsi. In the context of what is known about the role of mechano-stimulation in the control of feeding, and given their particular patterns of input and arborizations, it is suggested that the neurones may be active during food selection and ingestion.     

Ultrastructure of the galeal sensory complex in adults of the Colorado potato beetle, Leptinotarsa decemlineata

ABSTRACT. The structure of galeal sensilla of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), is described using electron microscopical methods. Previous electro-physiological studies indicate that these sensilla respond to amino acids, sucrose and plant saps. One physiological type is particularly sensitive to L-alanine and gamma amino butyric acid (GABA).
Three morphologically different types of sensilla occur on the galeal tip. The more numerous apical pegs are not distinguishable from one another on the basis of external structure, although they differ physiologically. Five sensory cells are associated with most apical pegs. One apical peg, the α-sensillum, contains only four cells. All apical pegs have one cell with a tubular body. The remaining cells have unbranched dendrites and are associated with a single apical pore.
Apical hairs differ from the apical pegs by having double innervation. Within the hair shaft, a dendritic sheath is lacking and the sensillar sinus extends to the base of the hair. The function of this hair type is not known.
Numerous mechanosensory hairs which surround the other sensilla are singly innervated and contain a tubular body at the level of the outer dendritic segments.     

Effect of relative humidity on the movement of rat vibrissae in a 60-Hz electric field

The snouts of rats were placed in a 60-Hz electric field at an unperturbed field strength of 50 kV/m. A count of the number of vibrissae that moved in the field was made on a series of rats over a number of days where the laboratory humidity varied from 25% to 48%. The number observed to vibrate fell from nine to zero or one at relative humidities between 25% and 39%, respectively.     

Innervation of the cercal sensilla on the ovipositor of the Australian sheep blowfly (Lucilia cuprina)

ABSTRACT. The ovipositor of the female sheep blowfly, Lucilia cuprina (Wied.) (Diptera: Calliphoridae), has a complement of cercal sensilla that includes long, medium and short tactile hairs, two campaniform domes, four olfactory pegs, and ten double-channelled gustatory hairs. This sensory array is suited to assess oviposition site resources, prior to and during the laying of an egg batch.
The tactile hairs and campaniform sensilla are each innervated by a single, tubular body containing dendrite. The olfactory pegs are each innervated by a single, moderately branched dendrite, which gains access to the external environment via pores at the bottom of deep grooves in the peg wall. The gustatory hairs fall into two categories. Four hairs have a single, tubular body containing dendrite at their base, and four unbranched dendrites running up to the hair tip which has a terminal pore. Six of the taste hairs have no tubular body containing dendrite at the base, and three unbranched dendrites running up to a terminal pore.     

Behavioural evidence for hygro- and mechanoreception by ovipositor sensilla of Dacus tryoni (Diptera: Tephritidae)

ABSTRACT. Gravid female Queensland fruit flies Dacus tryoni (Froggatt) readily oviposit when the ovipositor sensilla are stimulated either by a relatively thick (≥2 mm) surface layer, or by moisture under a relatively thin (<0.5 mm) or thick surface layer. A single layer of Parafilm over dry air elicits almost no oviposition; significantly more oviposition occurs when the underside of the Parafilm is coated with a 2 mm thick layer of petroleum jelly; even more oviposition occurs when the Parafilm is floated on liquid paraffin; greatest oviposition is elicited when moist media (agar gel, water or moist air) are presented under the Parafilm. Hollowed-out domes of apple skin elicit significant oviposition only when sealed basally, to give high internal concentrations of water vapour. The previously identified groove sensilla on the tephritid ovipositor are inferred as being a source of mechanical and chemical information used by the fly in such ovipositional decisions. The ovipositor also has two other types of tactile sensilla. The three types of ovipositor sensilla of tephritids are considered to play roles analogous to those of certain labial receptors of flies with piercing mouthparts.     

Python pit organs analyzed as warm receptors

The infrared receptor neurons of Python reticulatuspit organs were all found to have bimodal sensitivity, responding to both infrared and touch stimuli with fairly rapid adaptation. The majority (22 of 29 neurons) had no background discharges at any temperature between 20 and 33°C. The receptive areas were 150–250 µm in diameter and identical for both modalities. There was only one receptive area for each neuron. These facts suggest the possibility that some kinds of temperature sensitive neurons can also function as touch neurons and vice versa, not only in this species, but also in other animals.     

Prox2 and Runx3 vagal sensory neurons regulate esophageal motility

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