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  • 1
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    Ancestry of motor innervation to pectoral fin and forelimb (2010)
    Nature Publishing Group
    Details
    Publication Date: 2022-05-25
    Description: © Macmillan Publishers Limited, 2010. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 Unported License. The definitive version was published in Nature Communications 1 (2010): 49, doi:10.1038/ncomms1045.
    Description: Motor innervation to the tetrapod forelimb and fish pectoral fin is assumed to share a conserved spinal cord origin, despite major structural and functional innovations of the appendage during the vertebrate water-to-land transition. In this paper, we present anatomical and embryological evidence showing that pectoral motoneurons also originate in the hindbrain among ray-finned fish. New and previous data for lobe-finned fish, a group that includes tetrapods, and more basal cartilaginous fish showed pectoral innervation that was consistent with a hindbrain-spinal origin of motoneurons. Together, these findings support a hindbrain–spinal phenotype as the ancestral vertebrate condition that originated as a postural adaptation for pectoral control of head orientation. A phylogenetic analysis indicated that Hox gene modules were shared in fish and tetrapod pectoral systems. We propose that evolutionary shifts in Hox gene expression along the body axis provided a transcriptional mechanism allowing eventual decoupling of pectoral motoneurons from the hindbrain much like their target appendage gained independence from the head.
    Description: Th is work was supported by the National Institutes of Health and National Science Foundation.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: video/quicktime
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  • 2
    Electronic Resource
    Electronic Resource
    Forebrain peptides modulate sexually polymorphic vocal circuitry (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 403 (2000), S. 769-772 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The peptide arginine-vasopressin (mammals) and its evolutionary precursor arginine-vasotocin (non-mammals) modulate reproductive physiology and numerous related social behaviours, as do oxytocin (mammals) and its homologues mesotocin and isotocin (fish). The distributions in the brain ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35001581
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  • 3
    Electronic Resource
    Electronic Resource
    Shifts in frequency tuning of electroreceptors in androgen-treated mormyrid fish (1984)
    Springer
    Journal of comparative physiology 155 (1984), S. 713-724 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several species of mormyrid electric fish have a sex difference in the pulse waveform of their electric organ discharge (EOD). Field studies in Gabon, West Africa have shown for one such species,Brienomyrus brachyistius (triphasic), that the sexually mature male EOD differs in shape and is nearly twice the duration of the EODs of females and juveniles. Fourier analysis reveals that differences in EOD duration correlate with those in the EOD power spectrum which has a peak at 0.3 kHz in males and 1.3 kHz in females and juveniles. We find a corresponding sex difference in the frequency tuning of at least one class of electroreceptors known as Knollenorgans. The average ‘best’ or ‘characteristic’ frequency of Knollenorgans is lower in males compared to females and juveniles. This correlates with a lower peak in the power spectrum of the male's pulse. When females are treated with gonadal androgens, their EODs increase 2–3 fold in duration, and the power spectra of their pulses are correspondingly lowered to match that of mature males. The average best frequency of Knollenorgans decreases by nearly 1 kHz which matches the downward shift of their EOD's power spectrum. For a second species ofBrienomyrus (sp. 2) which is commercially imported from Nigeria, we have not detected a sex difference in the power spectrum or duration of the EOD. The power spectrum peaks at about 4.2 kHz in males, females, and juveniles. Androgens, however, do cause a coincident downward shift in the average peak of the EOD power spectrum (from 4.2 to 1.3 kHz) and the average best frequency of Knollenorgans (from 2.3 to 1.4 kHz). Specimens ofBrienomyrus (sp. 2) that have been electrically silenced by surgical means are tuned, on the average, only 0.2 kHz higher than control animals. Silenced animals that have been treated with androgens are tuned, on the average, 0.2 kHz below controls. The results suggest that electroreceptor tuning is only partially modifiable during androgen treatment if the electroreceptors arenot being stimulated by an external electrical stimulus, i.e. the animal's own EOD. Since androgen treatment has a dramatic effect on receptor tuningonly in intact fish, it seems likely that retuning isnot due to a direct action of androgens on receptors, but rather due to the action of the principal electrical stimulus upon the receptors, i.e. the EOD. The implications of such results for the development of species and sex differences in electro-receptor tuning is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611588
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  • 4
    Electronic Resource
    Electronic Resource
    Hormonal control of sex differences in the electric organ discharge (EOD) of mormyrid fishes (1985)
    Springer
    Journal of comparative physiology 156 (1985), S. 587-604 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Field studies have demonstrated that several species of mormyrid fish from Gabon, West Africa have a sex difference in the pulse-like waveform of their Electric Organ Discharge (EOD). Administration of androgen hormones (testosterone or dihydrotestosterone) to a female or juvenile can induce the EOD typical of a sexually mature male. Data for two such species —Brienomyrus brachyistius (triphasic) andStomatorhinus corneti — are presented, showing that transformation of a female's or juvenile's EOD to a male-like EOD involves a 2–3 fold increase in EOD duration and a downward shift in the peak frequency of the EOD's power spectrum (as determined by Fourier analysis). ForBrienomyrus brachyistius (triphasic), estradiol can also induce changes in the EOD waveform, although not as dramatic as that for androgens. Changes in EOD duration and power spectra are often accompanied by an alteration of the wave-shape or ‘morphology’ of the EOD pulse, i.e., the relative amplitude of its peaks and the presence of inflection points in its negative and positive phases. A third species,Hippopotamyrus batesii (triphasic), not previously known to have an EOD sex difference, also responds to testosterone treatment with an increase in EOD duration. Preliminary field data indicate this species may have a sexual dimorphism in its EOD, suggesting that the response to a steroid hormone may be an indicator of a sex difference in a species' EOD waveform. Such findings are discussed in relation to the affects of steroids on vertebrate neurons and muscle, and the evolution of electric communication systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619109
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  • 5
    Electronic Resource
    Electronic Resource
    Androgen binding in the brain and electric organ of a mormyrid fish (1986)
    Springer
    Journal of comparative physiology 159 (1986), S. 535-544 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mormyrid fish of Africa produce a weak electric pulse called an Electric Organ Discharge (EOD) that functions in electrical guidance and communication. TheEOD waveform describes the appearance of a single pulse which is produced by the electric organ's excitable cells, the electrocytes. For some species, there is a sex difference in the appearance and duration of the EOD waveform, which is under the control of gonadal steroid hormones. We now show, using biochemical techniques, that the steroid-sensitivity of the myogenic electric organ correlates with the presence of comparatively high levels of androgen-binding activity in the cytosol of electrocytes. TheEOD rhythm describes the rate at which the electric organ fires and is under the control of a central electromotor pathway. Sex differences have also been described for the EOD rhythm. Using steroid autoradiographic techniques, we found uptake of tritium-labelled dihydrotestosterone (3H-DHT) by cells within the reticular formation that lie adjacent to the medullary ‘relay nucleus’ which innervates the spinal electromotoneurons that excite the electric organ. However, no DHT-binding was observed in the relay or electromotor nuclei. Steroid-concentrating cells were also found in several other brainstem regions, the hypothalamus, and the thalamus. In particular, a group of DHT-concentrating, motoneuron-like cells were observed in the caudal medulla and were identified as aswimbladder orsonic motor nucleus. The biochemical data suggest that the electric organ has evolved a sensitivity to gonadal steroid hormones that may underlie the development of known sex differences in the EOD waveform. The autoradiographic results suggest that if steroids do affect the development of sex differences in the EOD rhythm, it is at some level removed from known spinal and medullary electromotor nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00604173
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  • 6
    Electronic Resource
    Electronic Resource
    Comparative neuroanatomy: foundations for a comparative neurobiology (1985)
    Springer
    Environmental biology of fishes 13 (1985), S. 77-79 
    Details
    ISSN: 1573-5133
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004858
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  • 7
    Electronic Resource
    Electronic Resource
    From brains to behaviour: hormonal cascades and alternative mating tactics in teleost fishes (1993)
    Springer
    Reviews in fish biology and fisheries 3 (1993), S. 181-186 
    Details
    ISSN: 1573-5184
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Each alternative male reproductive morph in teleosts has a distinct suite of secondary sex characteristics including behavioural, endocrinological, somatic and brain traits. Accepting that the central nervous system (CNS) is the ‘seat’ of behaviour, then male dimorphisms in the CNS (whether e.g. morphological, chemical or biophysical) must determine the production of distinct male reproductive tactics. The available data suggest that the preoptic-pituitary/GnRH-gonadotropin axis provides a proximate mechanism that initiates testicular maturation, subsequent changes in titers of circulating sex steroids, and the expression of secondary sex characteristics. Individuals may be predisposed, developmentally, to express one male morph or the other. Thus, irrespective of the time during an individual male's postembryonic life that a GnRH cascade is initiated, he would express only one male morph. (Developmental predisposition may depend on genetic or epigenetic events.) Alternatively, the temporal relationship of a GnRH cascade to an individual's age or body size may be critical to determining which morph is expressed. Thus, if the GnRH ‘trigger’ were to occur at 1 year of age or 6 cm body size, a sneak-spawn tactic would be followed; at 2 years of age or 12 cm, a parental, nest-guarding tactic is followed. The latter mechanism is akin to that for sequential hermaphrodites, where an individual has the potential to express both reproductive tactics, although for species such as midshipman, only one morph is ever manifested. Irrespective of which developmental mechanism is operative, the result is a mating system with two male reproductive morphs, each of which has a distinct suite of traits subject to sexual and natural selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045231
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  • 8
    Electronic Resource
    Electronic Resource
    Primary retinal targets in the Atlantic loggerhead sea turtle, Caretta caretta (1981)
    Springer
    Cell & tissue research 218 (1981), S. 253-264 
    Details
    ISSN: 1432-0878
    Keywords: Sea turtles ; Retinal pathways ; Diencephalon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Autoradiographic analysis distinguished twelve primary retinal targets in the diencephalon and the mesencephalon of the Atlantic loggerhead sea turtle, Caretta caretta. While the majority of fibers terminate contralaterally, sparse labelling is seen over ipsilateral thalamic nuclei. The dorsal optic nucleus is the most expansive retinal target in the dorsal thalamus. Four nuclei ventral and one dorsal, to the dorsal optic nucleus, receive retinal input. Before terminating in the optic tectum, labelled fibers pass through the pretectum terminating in four nuclei. Within the superficial zone of the optic tectum, three terminal zones are recognized. A distinct accessory tegmental tract separates from the main optic tract terminating in the basal optic nucleus. While such a multiplicity of retinal targets occurs among other reptiles, birds and mammals, it is presently impossible to accurately recognize visual homologies among amniotic vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210341
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  • 9
    Electronic Resource
    Electronic Resource
    Organization of the telencephalon in the channel catfish, Ictalurus punctatus (1981)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 169 (1981), S. 71-90 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoarchitectonics of the telencephalon of the channel catfish, Ictalurus punctatus, are described as a basis for experimental analysis of telencephalic afferents and efferents. The olfactory bulb comprises: (1) an outer layer of olfactory nerve fibers, (2) a glomerular layer, (3) an external cell layer, (4) an inner fiber layer, and (5) an internal cell layer. The telencephalic hemispheres comprise the areas ventralis and dorsalis telencephali. The area ventralis consists of: (1) a precommissural, periventricular zone including nucleus 'nother (Vn), the ventral nucleus (Vv), and the dorsal nucleus (Vd); (2) a precommissural, migrated zone of central (Vc) and lateral (VI) nuclei; (3) a supracommissural nucleus (Vs); (4) a caudal commissural zone of postcommissural (Vp) and intermediate (Vi) nuclei; and (5) a preoptic area (PP). The area dorsalis comprises: (1) medial (DM), (2) dorsal (Dd), (3) lateral [DL, containing dorsal (DLd), ventral (DLv), and posterior (DLp) regions], (4) posterior (DP), and (5) central (DC-1, -2, -3) areas. Nucleus taeniae (NT) is transitional between areas dorsalis and ventralis.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051690107
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  • 10
    Electronic Resource
    Electronic Resource
    Androgen effects on vocal muscle structure in a teleost fish with inter- and intra-sexual dimorphism (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 216 (1993), S. 305-318 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The plainfin midshipman fish Porichthys notatus has both interand intra-sexual dimorphism in the sound-producing (vocal or sonic) muscles attached to the swimbladder wall. The “Type I” and “Type II” male morphs differ in that dramatic structural changes related to sexual maturity occur in the mass, the area of mitochondria-filled sarcoplasm, and the myofiber number of the sonic muscles of Type I males, but not in those of Type II males (nor of females). Androgen implantation for 9 weeks markedly increased the relative sonic muscle size in juvenile males, juvenile females, and Type II males, whereas estradiol or cholesterol treatment did not. The principal androgen effect on myofiber structure was an increase in the area of mitochondria-filled sarcoplasm. The ratio of sarcoplasm area to myofibril area (Sr/Mf) increased by 1.4- to 2-fold in myofibers of all androgen-treated groups, with the greatest structural change occurring in juvenile males. When androgen implants were removed from juvenile males, the muscle mass and Sr/Mf ratio reverted toward the unimplanted juvenile phenotype. Total fiber number in sonic muscle increased significantly in juvenile males following androgen implantation but did not detectably change in juvenile females or Type II males. These results suggest: (1) sonic muscle in Porichthys notatus is an androgen target tissue, (2) fiber structure and fiber number are androgen-sensitive features, and (3) there exist sex- and morph-specific patterns of sonic muscle responsiveness to androgen implants. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052160306
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