Margaret A. Marchaterre

Publications (5)16.29 Total impact

• Article: Glucocorticoid and androgen signaling pathways diverge between advertisement calling and non-calling fish.

  Rachel M Genova, Margaret A Marchaterre, Rosemary Knapp, Daniel Fergus, Andrew H Bass
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  ABSTRACT: Behavioral and neuroendocrine mechanisms of social vocalization in teleost fish are influenced by the glucocorticoid cortisol and the androgen 11-ketotestosterone (11kT). The relative abundance of both 11kT, which binds to androgen receptors (ARα, ARβ), and cortisol, which binds to glucocorticoid receptors (GR-1, GR-2), is regulated by 11β-hydroxylase (11βH) that converts 11-deoxycortisol to cortisol and testosterone to 11β-OH-testosterone, and 11β-hydroxysteroid dehydrogenase (11βHSD) that converts cortisol to the inactive metabolite cortisone and 11β-OH-testosterone to 11kT. In midshipman fish, we tested the hypothesis that plasma steroid levels, mRNA abundance for 11βH and 11βHSD in the vocal muscle and testis (known site of 11kT synthesis), and mRNA abundances for ARs and GRs in vocal muscle, would differ between males that did or did not recently produce 'hum' advertisement calls. Quantitative real-time PCR demonstrated that non-calling male vocal muscle had significantly higher mRNA levels for all receptors except ARα, and a strong trend for higher 11βHSD; 11βH was similar to that in calling males. Calling males had higher plasma and testis 11kT, but lower plasma cortisol, levels. Testis enzyme levels did not differ between male groups, although calling males showed a positive linear correlation between plasma 11kT and testis 11βHSD mRNA levels, consistent with testis being the main source of plasma 11kT. We propose that higher vocal muscle 11βHSD levels in non-calling males reflect increased local conversion of elevated cortisol to cortisone, providing protection from cortisol-related toxicity, while increased receptor expression in non-calling males functions as a preparatory mechanism for meeting the physiological demands of future vocalization.
  Hormones and Behavior 08/2012; 62(4):426-32. · 3.87 Impact Factor
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  Available from: lifedesks.org

  Article: Ultrastructural features and hormone‐dependent sex differences of mormyrid electric organs

  Andrew H. Bass, Jean-Pierre Denizot, Margaret A. Marchaterre
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  ABSTRACT: The electric organ of mormyrid fishes is composed of action potentialgenerating cells called electrocytes that together produce a species-typical electric organ discharge (EOD). The electrocytes of mormyrids are discshaped cells with distinct anterior and posterior faces, and a series of evaginations of one face that form a stalklike structure that is the site of innervation by spinal electromotoneurons (Bass: J. Comp. Neurol. 244:313–330, '86a). Here, we describe the major ultrastructural features of mormyrid electrocytes, which include surface invaginations along each face, myonuclei, myofilaments, and neuromuscularlike junctions formed by the axons of spinal electromotoneurons. The degree of surface invaginations along the anterior face is the most dramatic interspecific variable and is usually greater for species with the longer duration EODs. Among species with sexually dimorphic EODs, natural males, or females trated with gonadal steroid hormones, have longer-duration EODs and thicker electrocytes with more surface invaginations along the anterior face. The results are discussed in relation to the action potential-generating properties of the electrocyte's membranes.
  The Journal of Comparative Neurology 10/2004; 254(4):511 - 528. · 3.81 Impact Factor
• Article: Structure, Localization, and Molecular Phylogeny of a GnRH cDNA from a Paracanthopterygian Fish, the Plainfin Midshipman (Porichthys notatus)

  Matthew S. Grober, Tami R. Myers, Margaret A. Marchaterre, Andrew H. Bass, Dean A. Myers
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  ABSTRACT: Multiple forms of gonadotropin releasing hormone (GnRH) are found within several species of teleost fishes. Within the infradivision Euteleostei, the superorder Paracanthopterygii represents one of the last major groups to be examined with respect to the GnRH mRNA sequence. The plainfin midshipman, Porichthys notatus , is a common member of this superorder which is intermediate between the ancestral euteleost taxa and the more derived Acanthopterygians (percomorphs). The goals of this study were to: (1) determine the cDNA sequence of prepro-GnRH in the plainfin midshipman, (2) address the anatomical localization of midshipman prepro-GnRH gene expression, and (3) perform a cladistic analysis using all currently known cDNA sequences of prepro-GnRH. We report 460 base pair of cDNA sequence containing the entire protein coding region, and 5′- and 3′-untranslated regions. The deduced amino acid sequence indicates that this cDNA encodes a GnRH decapeptide identical in sequence to that originally isolated in salmon (Trp7, leu8- GnRH). Northern analysis demonstrated transcripts in brain, ovary, and testis (600-700 nucleotides). PCR showed that the ovarian prepro-GnRH was identical to that found in brain. In situ hybridization labeled neurons in the ganglion of the terminal nerve and the preoptic area, forebrain areas previously observed to contain GnRH-like immunoreactivity. Last, a phylogenetic analysis of 18 prepro-GnRH sequences grouped the Paracanthopterygii with the Acanthopterygii. However, this recent clade was distinct from two separate and more ancestral lineages, the Paracanthopterygii (salmonids) and Ostariophysi (represented by catfish).
  General and Comparative Endocrinology 08/1995; · 3.27 Impact Factor
• Article: Androgen effects on vocal muscle structure in a teleost fish with inter‐ and intra‐sexual dimorphism

  Richard K. Brantley, Margaret A. Marchaterre, Andrew H. Bass
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  ABSTRACT: 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.
  Journal of Morphology 05/1993; 216(3):305 - 318. · 1.54 Impact Factor
• Article: Sound‐generating (sonic) motor system in a teleost fish (Porichthys notatus): Sexual polymorphism in the ultrastructure of myofibrils

  Andrew H. Bass, Margaret A. Marchaterre
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  ABSTRACT: One mechanism used by teleost fishes to produce acoustic communication signals involves the contraction of sonic “drum” muscles that appose the lateral walls of the swimbladder. In one marine species, the midshipman (Porichthys notatus), there is a sex difference in the overall size of the swimbladder as well as in the ultrastructural properties of its myofibrils. Additionally, there are two classes of sexually mature males referred to as Type I and Type II. The peripheral sonic motor system of Type I males differs from that of Type II males and females (which resemble each other) in a number of ways: 1) the mass of their swimbladder and associated sonic muscles is 50% greater, (2) their muscle fibers are several times larger and have a characteristically large volume of sarcoplasm that surrounds the myofibrils and is densely filled with mitochondria, (3) the length of z-lines of their myofibrils is about 20-fold greater, and (4) their sarcoplasmic reticulum is more highly branched. The ultrastructure of the myofibrils of Type II males and females resembles that found in the sonic muscle of males and females in other related species. The larger mass and specializations of the sonic muscle in Type I males are considered to be adaptations related to their known role in sound production and the unique long duration “humming” sounds that they generate during the breeding season. The similarity in the sonic motor system between females and Type II males is considered to be related to the utilization of an “alternative mating strategy” by Type II males. To our knowledge, this is the first documentation of a sex difference or, for that matter, a sexual polymorphism in the ultrastructural features of a vertebrate myofibril.
  The Journal of Comparative Neurology 08/1989; 286(2):141 - 153. · 3.81 Impact Factor