Polypterus Senegalus Research Articles

Immunohistochemical Distribution of Urotensins I and II in the Central Nervous System of the Senegal Bichir, Polypterus senegalus

Abstract The distribution of the urotensin I (UI)- and II (UII)-like immunoreactants in the central nervous system of the primitive bony fish Polypterus senegalus was studied by means of immunohistochemistry. Noticeably, UI-positive perikarya were present chiefly in the brain stem and the entire spinal cord with the exception of the caudalmost spinal cord segments, and their axons terminated on the wall of the adjacent blood vessels. In the cranial portion, the positive cells were found in the nucleus preopticus, the caudal diencephalon and the medulla oblongata. In contrast, the UII-immunoreactive fibers were distributed in the terminal part of the spinal cord, anterior to the 15th-to-the last vertebra; and a few UII-immunopositive perikarya occurred only in the caudalmost 5 to 6 segments. The most caudal region of the spinal cord showed a simplified or reduced neurohemal structure, where only UII-immunoreactive fibers were found. Accordingly, this area may represent the caudal neurosecretory system of t...

Lipids and Myelin Proteins in the Brains of Coelacanth (Latimeria chalumnae), lungfish (Lepidosiren paradoxaandProtopterus aetiopicus), bichir (Polypterus senegalus), and sturgeon (Acipenser ruthenus) (Osteichthyes): Phylogenetic Implications

The chemical components of nerve membranes of primitive bony fishes (coelacanth (Latimeria chalumnae), lungfish (Lepidosiren paradoxa and Protopterus aetiopicus), bichir (Polypterus senegalus), and sturgeon (Acipenser ruthenus)) were analyzed to investigate their phylogenetic relations. Representative myelin components such as cerebroside and myelin proteins and enzyme exhibited characteristic profiles in the different species. Coelacanth was characterized by an abundance of hydroxy components of cerebroside fatty acids and by the occurrence of a 28 000 molecular weight band (possibly P0-like protein) and proteolipid protein (PLP). Lungfish possessed glycosylated PLP, but lacked PLP; bichir and sturgeon showed the same protein compositions, PLP and P0-like protein being major components. The activity of 2′,3′-cyclic nucleotide 3′-phosphohydrolase (CNP), a myelin marker enzyme, was detected in coelacanth myelin, but was almost negligible in the others. The ganglioside compositions were simple in coelacanth and lungfish compared with those in bichir and sturgeon, which were abundant in polysialo components. These findings suggest that coelacanth nerve membranes are the most developed in these species; thus, coelacanth may be more advanced phylogenetically than the others. Bichir and sturgeon were suggested to occupy unique phylogenetic positions, showing similar chemical compositions of nerve membranes which were distinct from those of coelacanth and lungfish.

A Study of the Alimentary Canal of the Brachyopterygian FishPolypterus senegaluswith Electron Microscopy and Immunohistochemistry

The gastro-intestinal tract of Polypterus senegalus was investigated by means of electron microscopy and immunohistochemistry. Cilia-bearing cells can be observed over the whole length of the intestine. All enterocytes along the intestinal tract are characterized by apical pinocytotic vesicles. However, a typical intestinal region, which in other fish is characterized by large supranuclear vacuoles, is lacking. By means of electron microscopy, four types of endocrine cells and three types of nerve cell processes can be identified. By means of immunohistochemistry, endocrine cells with immunoreactivity for bombesin-, enkephalin-, G/CCK-, 5-HT-, somatostatin- and substance P-antisera can be found. Nerve cell processes show immunoreactivity for bombesin-, enkephalin-, 5-HT-, substance P- and VIP-antisera. The number of immunoreactive endocrine cells, nerve cells and nerve cell processes is different for each part of the gut.

The Question of a Vomer in Brachiopterygian Fish

Abstract The term vomer was coined over four centuries ago to denote one of the 23 bones normally comprising an adult human skull. As time went on more and more craniates were designated vomerate. To date, however, the issue as to whether brachiopterygian fish are or are not vomerate has remained unresolved. Those who consider these fish to be vomerate have suggested at least three different palatal bones as the homologue of the human vomer. Examination of embryological material of Polypterus senegalus shows that this brachiopterygian actually develops a vomer which eventually becomes united indistinguishably with the anterior part of the parasphenoid. The vomer is suggested to have arisen through the fusion of dental plates belonging to a supplementary set of buccopharyngeal denticulate bones. The other subethmoidal bones of the brachiopterygian palate seem likely to be derivatives of the tooth plates which originally were applied to the first two pairs of infrapharyngeals. When these endoskeletal elements were put to use for encapsulation of the organs of smell early in craniate phylogeny, some of the tooth plates that covered their inner surfaces fused to provide anterior palatal bones. Identified at one time or another as vomers, these bones are here termed glochinals and dacnils.

Two Intracranial Ligaments Supporting the Brain of the Brachiopterygian Fish Polypterus senegalus

AbstractTwo hitherto unknown ligaments that assist in holding the brain in position occur in the brachiopterygian fish Polypterus senegalus. These rounded fibrous cords, placed one behind the other, are called ligamentum intracraniale transversum and ligamentum intracraniale obliquum. The former spans the orbitotemporal division of the cranial cavity and passes through the velum transversum. The latter, which is paired, extends from the roof to the sidewall of the endocranium and runs in the rhombomesencephalic sulcus in company with the trochlear nerve. It is argued that these intracranial ligments, like the spinal denticulate ligaments, are derivatives of a pair of fibrous bands which in early craniate phylogeny extended throughout the length of the neuraxial meninx and enhanced its tensile strength. It is also argued that at least the transverse intracranial ligament was already in existence some 350 million years ago.

Scales in young Polypterus senegalus are elasmoid: new phylogenetic implications.

A component of the basal plate which has a plywood-like organization similar to that of the elasmoid scales of teleosts is described in the scales of Polypterus senegalus for the first time. The origin and development of this structure is studied in young (50-117 mm, standard length) and adult (225 and 240 mm) specimens using light and electron microscopy. In 50 mm fish, the scales are imbricated and composed mainly of a succession of orthogonal collagen layers forming a plywood-like structure, the isopedin. The outer surface of the scale is ornamented locally by irregular patches of collagenous material. The layers are not mineralized, whereas the superficial patches are well calcified. The isopedin thickens until it has 12-15 layers and then stops growing (88 mm fish). It mineralizes irregularly from its upper part, and two vascular regions, surrounded by woven-fibered osseous material, form on the outer and deeper surfaces of the isopedin. These regions thicken while the vascular canals close by centripetal deposition of parallel-fibered osseous tissue. The outer region is the superficial part of the mature scale (called here osteodentin), which is covered by the ganoine deposited by the epidermal cells. The deeper part constitutes the definitive basal plate, composed of parallel-fibered osseous tissue. The results show 1) that the young ganoid scales of Polypterus senegalus have a structure similar to that of typical elasmoid scales; and 2) that the isopedin structure does not change during ontogeny and so represents a permanent record of the first ontogenetic stages. The phylogenetic implication of these results is that the elasmoid scales of teleosts arose by a process of paedomorphosis.

Histochemical properties of sulfated glycoconjugates in developing enameloid matrix of the fish Polypterus senegalus

I investigated the ultrastructural localization and histochemical properties of sulfated glycoconjugates in developing enameloid matrix of the fish Polypterus senegalus, by use of the high iron diamine thiocarbohydrazide silver proteinate (HID-TCH-SP) staining and enzymatic digestion methods. HID-TCH-SP stain deposits were localized in the dental basal lamina and in the whole thickness of developing enameloid matrix, particularly closely associated with enameloid collagen fibrils. Most HID-TCH-SP stain deposits in the enameloid were susceptible to testicular hyaluronidase but some stain deposits survived. HID-TCH-SP stain deposits in the basal lamina resisted the enzymatic digestion, and were regularly localized to the internal and external sites of lamina densa at an early stage of development, subsequently tending to be randomly arranged with the increase in thickness of enameloid matrix layer. Furthermore, enzymatic digestion with heparitinase preferentially removed HID-TCH-SP stain deposits in the region of the basal lamina. Thus, it was confirmed that most HID-TCH-SP stain deposits in developing enameloid matrix are chondroitin 4-sulfate and/or 6-sulfate and that the stain deposits in the basal lamina represent heparan sulfate. The chondroitin sulfates tended to disappear with the advancement of enameloid mineralization.

Fine structural peculiarities of the pectoral fin dermoskeleton of two brachiopterygii, Polypterus senegalus and Calamoichthys calabaricus (Pisces, Osteichthyes).

The features of the dermal skeleton of the pectoral fins of two Brachiopterygii, Polypterus senegalus and Calamoichthys calabaricus, have been studied by light and electron microscopy. The components studied are the ganoine-covered lepidotrichia segments and the distally located actinotrichia, the features of which are similar to those in teleosts. An irregular patch of ganoine susceptible to erosion by vascular canals lies on top of the cellular bone of the upper surface of the segment. It is separated from the stratified epidermis by an organic intermediate layer in place of the dermoepidermal interface. This layer is interpreted as "anti-slip pad" or elastic glue anchoring the epidermis on the hypermineralized ganoine. Such components are also observed in ganoid scales, although embryological data fail to support that lepidotrichial segments are modified scales. The lack of dentin in lepidotrichia emphasizes the tendency during evolution toward the reduction of some dermoskeletal components and exemplifies ganoine deposition directly on top of the bone as in holostei scales. The participation of neural crest cells in development of the dermal skeleton is discussed by way of the repartition of the odontods within the pectoral fin.

The Morphology of the Organum Olfactus of a 32 mm Embryo of the Brachiopterygian Fish Polypterus senegalus

AbstractAnatomically the brachiopterygian organum olfactus is unique among craniates. As revealed by the present study of Polypterus senegalus, it consists of an incurrent and an excurrent tube, a body and six lobes. Luminally these divisions are extensively covered with cilia, the actions of which cause water to flow through the organ. The proximal extremities of the two tubes communicate directly with one another, allowing water to bypass the body and the lobes. The body is subdivided by means of seven infolds into a central part and two peripheral parts. Of these, the central part directs water to the lobes; the peripheral parts drain the lobes and lead water to the excurrent tube. Each lobe has an axial portion and two rows of alternating lobuli. Interlobularly infolds of the axial portion subdivide the lobar lumen in such a way that movement of water is possible. Olfactory neurosensory cells occur in the rear of the incurrent tube, as well as in the lobes. Probably the degree of stimulation of the tubal receptors determines whether the water taken in is to bypass the lobes.

Fish communities in the eastern, seasonal-floodplain of the Sudd, Southern Sudan

Annual flooding of the permanent Sudd swamps innundates large areas of Oryza longistaminata grasslands. Fish migration into a southeast section of the seasonal floodplain was led by Clarias gariepinus, Polypterus senegalus and several small species which were intent on spawning. Channa obscura and juveniles of Oreochromis niloticus were prominent among later entrants. From a total of 23 species caught in seasonal habitats, 7 contributed over 97% of total estimated numerical and biomass densities. The latter ranged from 435–580 kg ha−1. In the 1982–83 flood-season entry to the floodplain was essentially restricted to species tolerant of oxygen-deficient waters and thereby able to penetrate the papyrus and Typha swamps of the permanent wetland. Migrants became stranded in temporary pools and subject to heavy cropping by birds.

The retinofugal pathways in the primitive African bony fish Polypterus senegalus (Cuvier, 1829)

Retinal projections were studied using Fink-Heimer and radioautographic methods in Polypterus senegalus, a species which is representative of a small group of African fresh-water bony fish often considered to be very primitive. The large optic nerve showed partial decussation at the chiasm. Two major contralateral tracts were observed: the axillary and marginal optic tracts, with the latter being subdivided posteriorly into the tractus opticus medialis and tractus opticus lateralis. The retina projected onto the: (1) hypothalamus (area optica postoptica); (2) thalamus (nucleus opticus dorsolateralis thalimi, nucleus dorsomedialis thalami, corpus geniculatum laterale, area optica dorsolateralis thalami, area optica ventrolateralis thalami); (3) pretectum (nuclei commissurae posterioris, pretectalis ventralis, pretectalis dorsalis); and (4) optic tectum (stratum marginale, stratum opticum, stratum griseum et fibrosum superficiale, stratum griseum et album centrale, stratum griseum et fibrosum periventriculare). Ipsilateral retinal projections were demonstrated to the same 4 levels and more precisely to the nucleus opticus dorsolateralis thalami, area optica dorsolaterale thalami, nucleus commissurae posterioris, stratum marginale and stratum griseum et album centrale. The existence of a retinal projection to the mesencephalic tegmentum is discussed. Comparing the primary optic system of Polypterus with that of other jawed vertebrates, and particularly with that of other bony fish, indicated that this species possesses a combination of characteristics which are both actinopterygian and sarcopterygian. The phylogenetic significance of this mozaic anatomical arrangement is discussed.

Evolution of the feeding mechanism in primitive actionopterygian fishes: A functional anatomical analysis of Polypterus, Lepisosteus, and Amia

The comparative functional anatomy of feeding in Polypterus senegalus, Lepisosteus oculatus, and Amia calva, three primitive actinopterygian fishes, was studied by high-speed cinematography (200 frames per second) synchronized with electromyographic recordings of cranial muscle activity. Several characters of the feeding mechanism have been identified as primitive for actinopterygian fishes: (1) Mandibular depression is mediated by the sternohyoideus muscle via the hyoid apparatus and mandibulohyoid ligament. (2) The obliquus inferioris and sternohyoideus muscles exhibit synchronous activity at the onset of the expansive phase of jaw movement. (3) Activity in the adductor operculi occurs in a double burst pattern-an initial burst at the onset of the expansive phase, followed by a burst after the jaws have closed. (4) A median septum divides the sternohyoideus muscle into right and left halves which are asymmetrically active during chewing and manipulation of prey. (5) Peak hyoid depression occurs only after peak gape has been reached and the hyoid apparatus remains depressed after the jaws have closed. (6) The neurocranium is elevated by the epaxial muscles during the expansive phase. (7) The adductor mandibulae complex is divided into three major sections-an anterior (suborbital) division, a medial division, and a posterolateral division. In Polypterus, the initial strike lasts from 60 to 125 msec, and no temporal overlap in muscle activity occurs between muscles active at the onset of the expansive phase (sternohyoideus, obliquus superioris, epaxial muscles) and the jaw adductors of the compressive phase. In Lepisosteus, the strike is extremely rapid, often occuring in as little as 20 msec. All cranial muscles become active within 10 msec of each other, and there is extensive overlap in muscle activity periods. Two biomechanically independent mechanisms mediate mandibular depression in Amia, and this duality in mouth-opening couplings is a shared feature of the halecostome fishes. Mandibular depression by hyoid retraction, and intermandibular musculature, consisting of an intermandibularis posterior and interhyoideus, are hypothesized to be primitive for the Teleostomi.

Architecture du télencéphale, diencéphale et mésencéphale des Polyptériformes (Osteichthyens, Brachiopterygiens)

Abstract Architectural pattern of the telencephalon, diecenphalon and mesencephalon of Polypterine fishes (Osteichthyes, Brachiopterygii). The architectural pattern of the telencephalon, diencephalon and mesencephalon was studied in the Polypterine fishes. Brains of Calamoichthys calabaricus and Polypterus senegalus were examined using Golgi-Cox impregnations and Bodian gold-silver staining. The structure of these neural areas resembles the organization in the Actinopterygii and Dipnoi. Nevertheless, relevant peculiarities are evident in the brachiopterygian brain organization, viz. a double olfactory nerve, the torus lateralis of the mesencephalon and a particular shape of the pretectum. Detailed information has been given on the visual system of Calamoichthys and Polypterus both for a better understanding of the problem of the phylogenesis of this neural system and as a basis for further experimental research in this field.

Oxygen consumption and respiratory behaviour of three Nile fishes

1. The respiratory behaviour and patterns of oxygen consumption of three Nile species have been investigated. 2. Tilapia nilotica showed a typical pattern of oxygen consumption with an ambient region, adaptive plateau and lethal region (Fig. 2). 3. Specimens of Polypterus senegalus and Clarias lazera (body weights 20–30 and 30–45 g respectively) showed patterns of consumption comparable to that of Tilapia (Fig. 3a and 4a). In larger specimens of the two species the adaptive plateau was either insignificant or completely absent. 4. Specimens of Polypterus and Clarias (20–30 g and 30–45 g respectively) could survive in waters saturated with oxygen (7.4 mg/l) but their tolerance to lower oxygen concentrations was limited. Larger specimens of Polypterus and Clarias failed to survive in oxygen saturated waters. 5. The tolerance of Tilapia nilotica to extremely low oxygen concentration is an adaptation of a tropical and completely aquatic species. Polypterus and Clarias resort to their compensatory mechanisms only when the aquatic respiratory surface fails to satisfy their oxygen requirements.

The in Vitro Respiratory Properties of Blood of the Primitive Fish Polypterus Senegalus

ABSTRACT Respiratory properties of blood of Polypterus senegalus were studied in vitro at 30 °C The following values were found in species which did not suffer from an apparent anaemia: erythrocyte count 0·7–1·15 x 108/mm3, haemoglobin concentration 10–14 g/100 ml, haematocrit 33–43 vol. %, mean erythrocyte volume 300–480/4ms, and mean erythrocyte size 18×10 μm. Subtracting the calculated volume of the nucleus, the ‘true’ mean corpuscular haemoglobin concentration in the erythrocyte cytoplasm was found to be 34 g/100 ml, which corresponds to the haemoglobin concentration in the non-nucleated mammalian erythrocytes. Transport of oxygen : The oxygen affinity of haemoglobin was found to be moderate, P50 being 23·5 mmHg at , 6 mmHg and pH 7·7. The O2 dissociation curve had a typical sigmoid shape. The oxygen capacity of the investigated samples was 13·5–18·5 ml/100ml, showing a binding capacity of approximately 1·34 ml O2 per 1 g Hb at pH > 7·3. A slight Root effect was observed at pH lower than 7·2. The coefficients of the Bohr effect (A log P 50/A pH) and of the temperature shift of the oxygen dissociation curve (Δ log P50/ΔT) were −0·43 and 0·022, respectively. Transport of carbon dioxide: the CO2 combining power in oxygenated blood was 12·5 mM/1 at 30 mmHg and pH 7·3 and the CO2 dissociation curve showed the typical steep initial portion. The buffering capacity of blood was moderate, the coefficient being −15·4. The Haldane effect was also found to be moderate, cap. being–0.10. The dissociation constant of plasma carbonic acid (pK′) was assessed to be 0-03 higher than that of human plasma at corresponding pH and temperature 30 °C. The position of the absorption maxima of Polypterus oxyhaemoglobin and cyanmethaemoglobin solutions was the same as that of human haemoglobin solutions. The results are compared with the respiratory properties of lungfish and human blood.

Juxtaglomerular apparatus in the vertebrates

Renin and juxtaglomerular (JG) cells are present in tetrapod vertebrates and teleosts the macula densa (MD) and extraglomerular mesangium (EGM) are seen only in mammals. Detailed studies of the evolution of juxtaglomerular apparatus (JGA) are presented in this paper. No granules were stained with Bowie's method in the kidneys of Chondrostei: Polypterus senegalus, Calamoichthys calabaricus, Acipenser brevirostris, and Holostein: Amia calva, Lepisosteus osseus. In the kidney of the lungfish, Protopterus aethiopicus, JG cells were found in the arterial wall distant from the glomeruli. Three types of distribution of JG cells were observed in aglomerular teleosts. In the kidney of Opsanus tau, JG cells were distributed in the walls of small arteries. In Lophius litulon, JG cells were distributed in several regions of the kidney. In Phrynelox nox, P. tridens and Histrio histrio, JG cells were concentrated in a limited area of the kidney. The MD site was examined with the light microscope in Gallus gallus v. domesticus and Coturnix coturnix japonica, and with the electron microscope in G. gallus. The avian cells possess some of the characteristics of mammalian MD cells, and can be considered as structurally transitional between typical MD cells in mammals and the ordinary cells of the distal tubule.

Further Studies on Macrogyrodactylus polypteri, a Monogenean on the African Freshwater Fish Polypterus senegalus

Macrogyrodactylus polypteri Malmberg, 1957* is a viviparous monogenean found on the skin and fins of the African freshwater fish Polypterus senegalus Cuvier. It was first reported by Malmberg (1957) from Gambia. Khalil (1964, 19G9) and Amirthalingam (19C5) recorded it on the same host species and Saoud & Mageed (1969) found it on P. bichir in the Sudan. Prudhoe (1957) described a new genus and species, Neogyrodactylus congolensis, on the skin of Clarias lazera from the Congo but Yamaguti (1963) considered this genus to be a synonym of Macrogyrodactylus. A third species, M. clarii Gussev, 1961 was reported on Clarias sp. from south Ethiopia and Ghana. On the basis of one specimen M. latest Paperna, 1969 was reported on Lates nilotica from Ghana. So far the species of the genus are confined to African freshwater fishes.

Respiratory Function of the Swim-Bladders of the Primitive Fish Polypterus Senegalus

ABSTRACT The respiratory function of the swim-bladders of Polypterus senegalus was investigated. Experiments were carried out in tap water with an oxygen tension of about 140 mm. Hg. Both swim-bladders were cannulated through the body-walls of the unrestricted fish. Gas samples were analysed for their oxygen and carbon dioxide content before and after the fish visited the surface. A sharp increase in oxygen and a decrease in carbon dioxide tension was always observed after inhalation. This proves that atmospheric air is actually inspired into the bladders. After inspiration, the amount of oxygen in the bladders decreased rapidly. This shows that oxygen is taken up by the blood, even when the oxygen content of the water is normal. Inspiration of air is preceded by expiration which, on the average, reduces the volume of the bladders to about 40%. The uneven distribution of inhaled air in the right bladder is shown to be due to anatomical configuration.

Respiration of Air by the Primitive Fish Polypterus senegalus

THE primitive aetinopterygian fish Polypterus senegalus Cuvier inhabits shallow and swampy waters throughout tropical Africa, often in conditions of severe oxygen deficiency, and its adaptation to this type of habitat includes the possession of spiracles and a double swim bladder or lung which has long been assumed to act as an accessory respiratory organ. Conflicting views have, however, been expressed regarding the use of spiracles in connexion with the respiration of air. Budgett1 stated that the spiracles are used to take in and expire air from the swim bladders; but Boulenger2 concluded that there was little evidence to show that Polypterus comes to the surface to breathe. More recently, it has been shown that the spiracles are used to inhale air which is passed to the lungs3. Air is inspired both in conditions of low oxygen concentration and during periods of excessive activity.

Observations on the venous system of three species of Polypterus (Pisces)

The venous system of Polypterus exhibits general asymmetry. The features that characterize the venous system of this peculiarly African fish are the possession of many blood sinuses, the segmental drainage of blood, the continuation of the posterior cardinal veins as separated vessels and the occurrence of several anastomozes between the latter.In the absence of any recent comprehensive work on the blood system of this fish, it was thought that investigation of the circulatory system of Polypterus would be valuable. In this paper attention is drawn to Budgettapos;s (1902) original work on a larva of Polypterus senegalus. Contrary to Budgettapos;s findings it is concluded that what he called the “interrenal” vein is in fact the right posterior cardinal vein. It is also found that paired posterior cardinal veins exist in all adults.