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PubMed1976

The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. I. Sexual dimorphism in the distribution of antennal sense organs in five species.

Sexual dimorphism in the distribution of antennal sense organs is common among adults of the genus Periplaneta. In three out of the four strains of Periplaneta americana examined, adult males had more contact chemoreceptros than females. In the fourth strain of P. americana and in P. australasiae, P. brunnea, P. fuliginosa, and P. japonica, no statistically supportable sexual dimorphism of contact chemoreceptors was found. However, in all strains and species of Periplaneta examined, sexual dimorphism was found in the total number and/or density of olfactory sensilla. Male adults had nearly twice as many olfactory sensilla as female adults. These observations are consistent with the behavioral observation that males within the genus Periplaneta rely on the reception of an airborne pheromone for the initiation of courtship behavior. In P. americana, where sexual dimorphism was found in the contact chemoreceptors, contact stimuli release the full wing raising display and presentation in males during courtship.

Animals↗
PubMed2006

Specializations in the lumbosacral vertebral canal and spinal cord of birds: evidence of a function as a sense organ which is involved in the control of walking.

Birds are bipedal animals with a center of gravity rostral to the insertion of the hindlimbs. This imposes special demands on keeping balance when moving on the ground. Recently, specializations in the lumbosacral region have been suggested to function as a sense organ of equilibrium which is involved in the control of walking. Morphological, electrophysiological, behavioral and embryological evidence for such a function is reviewed. Birds have two nearly independent kinds of locomotion and it is suggested that two different sense organs play an important role in their respective control: the vestibular organ during flight and the lumbosacral system during walking.

Animals↗
PubMed1993

asense is a Drosophila neural precursor gene and is capable of initiating sense organ formation.

Neural precursor cells in Drosophila arise from the ectoderm in the embryo and from imaginal disc epithelia in the larva. In both cases, this process requires daughterless and the proneural genes achaete, scute and lethal-of-scute of the achaete-scute complex. These genes encode basic helix-loop-helix proteins, which are nuclear transcription factors, as does the asense gene of the achaete-scute complex. Our studies suggest that asense is a neural precursor gene, rather than a proneural gene. Unlike the proneural achaete-scute gene products, the asense RNA and protein are found in the neural precursor during its formation, but not in the proneural cluster of cells that gives rise to the neural precursor cell. Also, asense expression persists longer during neural precursor development than the proneural gene products; it is still expressed after the first division of the neural precursor. Moreover, asense is likely to be downstream of the proneural genes, because (1) asense expression is affected in proneural and neurogenic mutant backgrounds, (2) ectopic expression of asense protein with an intact DNA-binding domain bypasses the requirement for achaete and scute in the formation of imaginal sense organs. We further note that asense ectopic expression is capable of initiating the sense organ fate in cells that do not normally require the action of asense. Our studies therefore serve as a cautionary note for the inference of normal gene function based on the gain-of-function phenotype after ectopic expression.

Amino Acid Sequence↗
PubMed1991

[Long ascending fibers in the dorsal column of a teleost fish: a disynaptic pathway connecting sense organs to cerebellum].

In spite of the generally accepted opinion that long ascending proprioceptive and tactile fibers do not occur in the spinal dorsal columns of teleost fish, it was demonstrated with degeneration and axonal transport tracing methods that such dorsal column fibers exist in the teleost fish Gnathonemus petersii. These fibers are in fact common spinal afferent fibers originating in spinal ganglion cells. They connect the peripheral sense organs with the lateral funicular nuclei (Fl2) in which the dorsal column fibers terminate, directly through the dorsal columns. In contrast to the dorsal column nuclei of higher vertebrates, the Fl2 nuclei do not project to the diencephalic thalamus but to the caudal lobe and the second lobe (C2) of the corpus cerebelli. Thus, sense organs and cerebellum are connected by a disynaptic pathway. Since the caudal lobe projects directly to the electrosensory lobe, that is, to the target of electrosensory afferents, the presence of a disynaptic pathway in G. petersii suggests the existence of a proprioceptive control of the electrosensory input.

Afferent Pathways↗
PubMed2004

Ultrastructure of the abdominal sense organ of the scallop Mizuchopecten yessoensis (Jay).

The sensory epithelium of the abdominal sense organ (ASO) of the scallop Mizuchopecten yessoensis is composed of three cell types, sensory cells, mucous cells, and multiciliated cells. Sensory cells bear a single long (up to 250 microm) cilium surrounded by an inner ring of nine modified microvilli and an outer ring of ordinary microvilli paired with modified microvilli. Sensory cells make up about 90% of the total number of cells in the sensory epithelium. Mucous cells, which are much wider than sensory cells, bear only ordinary microvilli on their apical surface. Rare multiciliated cells with short (4-6 microm) cilia are scattered in the periphery of the sensory epithelium sheet. All hairs, cilium, and microvilli of each sensory cell are interconnected by a fibrous network. Nine modified microvilli of a single cell are interconnected by prominent laterally running fibrous links. Membrane-associated electron-dense material of modified microvilli is connected to the ciliary membrane-associated electron-dense material by fine string-like links. These links mechanically bridge the space between the cilium and modified microvilli, as do mechanical links, described for the stereocilia and kinocilium of vertebrate vestibular and cochlear hair cells. The proximal portion of a sensory cilium is about 100 microm long and has a typical 9 x 2+2 axoneme arrangement. The distal portion of a cilium is approximately 2 times thinner than the proximal one and is filled with homogeneous electron-dense material. Along the distal portion, diffuse material associated with the external surface of the membrane is found. The rigidity of distal portion of a cilium is much less than that of the proximal one.

Abdomen↗
PubMed2003

Diversification of brain and sense organ morphology in Antarctic dragonfishes (Perciformes: Notothenioidei: Bathydraconidae).

In the subzero shelf waters of Antarctica, fishes of the perciform suborder Notothenioidei dominate the fish fauna and constitute an adaptive radiation and a species flock. The 16 species of dragonfishes of the family Bathydraconidae live from surface waters to nearly 3,000 m and have the greatest overall depth range among notothenioid families. We examined the anatomy and histology of the brain, retina, and cephalic lateral line system of nine bathydraconid species representing 8 of the 11 known genera. We evaluate these data against a cladogram identifying three clades in the family. We provide a detailed drawing of the brain and cranial nerves of Gymnodraco acuticeps and Akarotaxis nudiceps. Bathydraconid brain morphology falls into two categories. Brains of most species are similar to those of generalized perciforms and some basal notothenioids (Class I). However, brains of deep-living bathydraconids (members of the tribe Bathydraconini minus Prionodraco) have a reduced telencephalon and tectum that renders the neural axis visible - the stalked brain morphology (Class II). All bathydraconids have duplex (rod and cone) retinae but there is considerable interspecific variation in the ratio of cones:rods and in the number of cells in the internal nuclear layer. Retinal histology reflects habitat depth but is not tightly coupled to phylogeny. Although the deep-living species of Bathydraconini have rod-dominated retinae, the retinae of some sister species are photopic. An expanded cephalic lateral line system is also characteristic of all members of the Bathydraconini as exemplified by Akarotaxis. This morphology includes large lateral line pores, wide membranous canals, hypertrophied canal neuromasts, and large anterodorsal lateral line nerves, eminentia granulares, and crista cerebellares. The saccular otoliths are also enlarged in members of this tribe. Neural diversification among bathydraconids on the Antarctic shelf has not involved the evolution of sensory specialists. Brain and sense organ morphologies do not approach the specialized condition seen in primary deep-sea fishes or even that of some secondary deep-sea fishes including sympatric non-notothenioids such as liparids (snailfishes) and muraenolepidids (eel cods). The brains and sense organs of bathydraconids, including the deep-living species, reflect their heritage as perciform shorefishes.

Anatomy, Comparative↗
PubMed1999

Irregular chiasm-C-roughest, a member of the immunoglobulin superfamily, affects sense organ spacing on the Drosophila antenna by influencing the positioning of founder cells on the disc ectoderm.

We describe a role for Irregular chiasmC-roughest (IrreC-rst), an immunoglobulin (Ig) superfamily member, in patterning sense organs on the Drosophila antenna. IrreC-rst protein is initially expressed homogeneously on apical profiles of ectodermal cells in regions of the antennal disc. During specification of founder cells (FCs), the intracellular protein distribution changes and becomes concentrated in regions where specific intercellular contacts presumably occur. Loss of function mutations as well as misexpression of irreC-rst results in an altered arrangement of FCs within the disc compared to wildtype. Sense organ development occurs normally, although spacing is affected. Unlike its role in interommatidial spacing, irreC-rst does not affect apoptosis during antennal development. We propose that IrreC-rst affects the spatial relationship between sensory and ectodermal cells during FC delamination.

Animals↗
PubMed1980

Ciliated receptors in the cruciform muscle sense organ of Scrobicularia plana (Da Costa) (Mollusca Lamellibranchia Tellinacea).

The ultrastructure of the cruciform muscle sense organ has been studied in Scrobicularia plana. Subepithelial neurons give rise to two different types of ciliated dendrite which pass through a thick basement membrane to insert between epithelial cells lining the sensory pit. Type I, comprising most dendrites have an elongated surface bearing up to 4 rows of 20 cilia, the basal bodies of which are linked in each row. These dendrites, it is suggested, receive unidirectional stimuli. Type II dendrites bear only one cilium surrounded by 9 peculiar microvilli embedded in a conspicuous glycocalyx. The efficient stimulus for this receptor is not known. The two different types possess cilia with (9 X 2) + 2 microtubuli, striated rootlets but no basal foot, surrounded by microvilli.

Animals↗
PubMed2004

EGF receptor signaling triggers recruitment of Drosophila sense organ precursors by stimulating proneural gene autoregulation.

In Drosophila, commitment of a cell to a sense organ precursor (SOP) fate requires bHLH proneural transcription factor upregulation, a process that depends in most cases on the interplay of proneural gene autoregulation and inhibitory Notch signaling. A subset of SOPs are selected by a recruitment pathway involving EGFR signaling to ectodermal cells expressing the proneural gene atonal. We show that EGFR signaling drives recruitment by directly facilitating atonal autoregulation. Pointed, the transcription factor that mediates EGFR signaling, and Atonal protein itself bind cooperatively to adjacent conserved binding sites in an atonal enhancer. Recruitment is therefore contingent on the combined presence of Atonal protein (providing competence) and EGFR signaling (triggering recruitment). Thus, autoregulation is the nodal control point targeted by signaling. This exemplifies a simple and general mechanism for regulating the transition from competence to cell fate commitment whereby a cell signal directly targets the autoregulation of a selector gene.

Animals↗
PubMed1997

Development of gravity-sensing organs in altered gravity.

Experiments are described in which the development of the gravity-sensing organs was studied in newt larvae reared in microgravity on the IML-2 mission and in Aplysia embryos and larvae reared on a centrifuge at 1 to 5 g. In Aplysia embryos, the statolith (single dense mass on which gravity and linear acceleration act) was reduced in size in a graded fashion at increasing g. In early post-metamorphic Aplysia or even in isolated statocysts from such animals, the number of statoconia produced is reduced at high g. Newt larvae launched before any of the otoconia were formed and reared for 15 days in microgravity had nearly adult labyrinths at the end of the IML-2 mission. The otoliths of the saccule and utricle were the same size in flight and ground-reared larvae. However, the system of aragonitic otoconia produced in the endolymphatic sac in amphibians was much larger and developed earlier in the flight-reared larvae. At later developmental stages, the aragonitic otoconia enter and fill the saccule. One flight-reared larva was maintained for nine months post-flight and the size of the saccular otolith, as well as the volume of otoconia within the endolymphatic sac, were considerably larger than in age-matched, ground-reared newts. This suggests that rearing in microgravity initiates a process that continues for several months after introduction to 1-g, which greatly increases the volume of otoconia. The flight-reared animal had abnormal posture, pointing its head upward, whereas normal ground-reared newts always keep their head horizontal. This suggests that rearing for even a short period in microgravity can have lasting functional consequences in an animal subsequently reared in 1-g conditions on Earth.

Animals↗
PubMed2002

Novel bridge of axon-like processes of epithelial cells in the aboral sense organ of ctenophores.

We describe by light and electron microscopy a novel structure in the aboral sense organ (apical organ) of cydippid (Pleurobrachia) and lobate (Mnemiopsis) ctenophores. An elevated bundle of long, thin, microtubule-filled processes arises from the apical ends of two groups of epithelial cells located on opposite sides of the apical organ along the tentacular plane of the body. This bundle of axon-like processes arches over the epithelial floor like a bridge, with branches at both ends running toward opposing pairs of ciliary balancers that are motile pacemakers for the rows of locomotory ciliary comb plates. The bridge in Pleurobrachia is approximately 40 microm long and 3-4 microm wide and consists of approximately 60 closely packed processes, 0.2-0.8 microm thick, containing vesicles and numerous microtubules running parallel to their long axes. There are approximately 30 epithelial cells in each of the two groups giving rise to the bridge and each cell forms a single process, so roughly half of the processes in the bridge must originate from cells on one side and diverge into branches to a pair of balancers on the opposite side of the apical organ. The 150-200 cilia in each balancer arise from morphologically complex cellular projections with asymmetric lateral extensions directed towards a fork of the bridge. Presynaptic triad structures and vesicles are found in this region but clear examples of synaptic contacts between bridge processes and balancer cells have not yet been traced. Cydippid larvae of Mnemiopsis have a conspicuous bridge along the tentacular plane of the apical organ. Beroid ctenophores that lack tentacles at all stages do not have a bridge. We discuss the possibility that the bridge is an electrical conduction pathway to balancers that coordinates tentacle-evoked swimming responses of ctenophores, such as global ciliary excitation.

Animals↗
PubMed2003

Sense-organ-like parietal pits found in Psammophiini (Serpentes, Colubridae).

In several psammophine snake species, small sense-organ-like pits have been discovered occurring on the top of the head. These pits show a heretofore non-described structure. In numbers of one to four per head, they are present in Dromophis lineatus, Malpolon monspessulanus, several Psammophis species and Rhamphiophis rubropunctatus, but not in all individuals which is unrelated to sex. The reason for their sporadic occurrence remains obscure. Their equally obscure function is discussed in relation to the presumed functions of already known upper-head 'pits' in snakes. A histological study is in preparation.

Animals↗
PubMed2004

Brain and sense organ anatomy and histology in hemoglobinless Antarctic icefishes (Perciformes: Notothenioidei: Channichthyidae).

The Channichthyidae, one of five Antarctic notothenioid families, includes 16 species and 11 genera. Most live at depths of 200-800 m and are a major component of fish biomass in many shelf areas. Channichthyids are unique among adult fishes in possessing pale white blood containing a few vestigal erythrocytes and no hemoglobin. Here we describe the brains of seven species and special sense organs of eight species of channichthyids. We emphasize Chionodraco hamatus and C. myersi, compare these species to other channichthyids, and relate our findings to what is known about brains and sense organs of red-blooded notothenioids living sympatrically on the Antarctic shelf. Brains of channichthyids generally resemble those of their bathydraconid sister group. Among channichthyids the telencephalon is slightly regressed, resulting in a stalked appearance, but the tectum, corpus cerebellum, and mechanoreceptive areas are well developed. Interspecific variation is present but slight. The most interesting features of channichthyid brains are not in the nervous tissue but in support structures: the vasculature and the subependymal expansions show considerable elaboration. Channichthyids have large accessory nasal sacs and olfactory lamellae are more numerous than in other notothenioids. The eyes are relatively large and laterally oriented with similar duplex (cone and rod) retinae in all eight species. Twin cones are the qualitatively dominant photoreceptor in histological sections and, unlike bathydraconids, there are no species with rod-dominated retinae. Eyes possess the most extensive system of hyaloid arteries known in teleosts. Unlike the radial pattern seen in red-blooded notothenioids and most other teleosts, channichthyid hyaloid arteries arise from four or five main branches and form a closely spaced anastomosing series of parallel channels. Cephalic lateral line canals are membranous and some exhibit extensions (canaliculi), but canals are more ossified than those of deeper-living bathydraconids. We conclude that, with respect to the anatomy and histology of the neural structures, the brain and sensory systems show little that is remarkable compared to other fishes, and exhibit little diversification within the family. Thus, the unusual habitat and a potentially deleterious mutation resulting in a hemoglobinless phenotype are reflected primarily in expansion of the vasculature in the brain and eye partially compensating for the absence of respiratory pigments. Neural morphology gives the impression that channichthyids are a homogeneous and little diversified group.

Adaptation, Physiological↗
PubMed1993

Ampullary sense organs, peripheral, central and behavioral electroreception in chimeras (Hydrolagus, Holocephali, Chondrichthyes).

Ampullary sense organs are distributed in groups over the head of Hydrolagus colliei with their pores in clusters and innervated by the buccal, hyomandibular and superficial ophthalmic branches of the anterior lateral line nerve. The ampullae contain ciliated sense cells in an alveolate-shaped epithelium, which communicates to the surface through a jelly-filled tube. The sense cells synapse at their bases with the afferent nerve fibers that terminate in the dorsal nucleus of the anterior lateral line lobe of the medulla. The anatomy and ultrastructure support the homology with the ampullae of Lorenzini of elasmobranchs. Single units recorded from the buccal branch of the anterior lateral line nerve are either lateral line or ampullary in character, the former being sensitive only to mechanical stimuli, the latter to both mechanical and to weak electric stimuli. They are also distinguished by the positions of their receptive fields. The electroreceptive units are spontaneously active and are excited by a cathode placed near the opening of their pore and inhibited by an anode. Compound evoked potentials are recorded from beneath the lateral aspect of the tectum in response to weak electric fields in the bath. Each recording locus has a best position and orientation of the electric field. The electric fields are effective if their duration is longer than ca. 2 ms; longer than 10 ms makes no difference until an OFF effect becomes distinct at ca. 50 ms. The reception is tuned to low frequencies but is not sensitive to maintained current (DC). Evoked potentials summating moderate numbers of responses are clear at < 1 microV/cm. Ratfish were conditioned in a ring-shaped tank to reverse the direction of swimming when an electric field was switched ON. The stimulus was a 5 Hz square wave or the onset of a DC of 1-10 microA between a pair of electrodes on the floor of the tank. The fish responded to fields as weak as 0.2 microV/cm. A specialized sense modality for electroreception, similar to that in elasmobranchs and most other groups of nonteleost fishes, except for Myxini and Neopterygii (holosteans), is present in the subclass Holocephali. The notion is supported that this modality and its central as well as peripheral apparatus arose early in the evolution of vertebrates. Only two losses of the whole system need be hypothesized, on this idea, once in the ancestors of the hagfishes and once in the ancestors of the neopterygians, which include the teleosts. Some orders of teleosts then evolved a new system of electroreception independently. The ciliary receptor cells are probably primitive; microvillar sense cells evolved independently.

Animals↗
PubMed1997

Development of the Drosophila olfactory sense organs utilizes cell-cell interactions as well as lineage.

We have examined the mechanisms underlying the development of the olfactory sense organs on the third segment of the antenna of Drosophila. Our studies suggest that a novel developmental strategy is employed. Specification of the founder or precursor cell is not governed by the genes of the achaete-scute complex. Another basic helix-loop-helix encoding gene, atonal, is essential for determination of only a subset of the sensilla types--the sensilla coeloconica. Therefore, we predict the existence of additional proneural genes for the selection of sensilla trichoidea and sensilla basiconica. The choice of a founder cell from the presumed proneural domain is regulated by Notch activity. Soon after delamination of the founder cell, two to three additional neighboring cells also take on a sensory fate and these cells together form a presensillum cluster. The selection of neighbors does not occur when endocytosis is blocked using a temperature sensitive allele of shibire, thus suggesting that cell-cell communication is required for this step. The cells of the cluster divide once before terminal differentiation which is influenced by Notch activity. The final cell number within each sensillum is controlled by programmed cell death.

Animals↗
PubMed1994

Selective lineage specification by mab-19 during Caenorhabditis elegans male peripheral sense organ development.

The action of the gene mab-19 is required for specification of a subset of Caenorhabditis elegans male peripheral sense organ (ray) lineages. Two mab-19 alleles, isolated in screens for ray developmental mutations, resulted in males that lacked the three most posterior rays. Cell lineage alterations of male-specific divisions of the most posterior lateral hypodermal (seam) blast cell, T, resulted in the ray loss phenotype in mab-19 mutant animals. Postembryonic seam lineage defects were limited to male-specific T descendent cell divisions. Embryonic lethality resulted when either mab-19 mutation was placed over a chromosomal deficiency encompassing the mab-19 locus. The earliest detectable defect was aberrant hypodermal cell movements during morphogenesis. From these data, it is inferred that both mab-19 alleles described are hypomorphs, and further reduction of mab-19 function results in embryos that are unable to complete morphogenesis. Thus, mab-19 may play a larger role in developmental regulation of hypodermal cell fate, including sensory ray development in males. Body morphology mutations, passage through the dauer stage, and heat or CdCl2 treatment suppressed mab-19 male phenotypes. A model is presented in which all three types of suppression result in a physiological stress response, which in turn leads to correction of the mab-19 defect.

Alleles↗