[Intensity of respiration and oxidative phosphorylation in the ontogeny of tailless amphibia (Anura, Amphibia)].
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Amphibians↗
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[Phylogenetic studies on some Japanese amphibia by mean of immunoelectrophoresis. I. Relationships of some frogs and newt to toad (author's transl)].
The phylogenetic relationship among toad, frogs and newt from Japan was investigated by means of immunoelectrophoresis. Homologous, heterologous and non-identity reactions between rabbit anti-Bufo bufo antiserum and antigen from each of 13 species and 2 subspecies of Japanese amphibia were examined. The number and positions of arcs appeared in these reactions were compared. The relationship observed in the comparison well coincided with the classification of the upper taxa of amphibia; viz 1) Hyla arborea is more intimately related to B. bufa, 2) members of Ranidae and Rhacophoridae have equal intimacy for B. bufo, and 3) Cynops pyrrhogaster is most distantly related to B. bufo. By contrasting arc obtained in non-identity reaction and those obtained in homologous reaction, it was found that toad, B. bufo carried 22 antigens, and among these antigens, one was observed through all amphibians tested, 12 were carried solely by toad, and some of the remainders were common to antigens carried by various frogs. Newts carried only one antigen common to toad. Based on these results, the phylogeny of Japanese amphibia was discussed.
Amphibians↗
The occurrence of mercury in amphibia.
Studies have been made of the distribution of mercury and its occurrence as methylmercury in the organs of amphibia collected from different sites mainly in Slovenia, Yugoslavia, including the area around the mercury mine at Idrija. Liver accumulates the highest amounts of mercury, up to 2 ppm in apparent background areas, with values up to 0.5 ppm in muscle, where virtually all mercury is present in the methyl form. Results are reported for some other trace elements in liver. Amphibia may provide useful monitors of the occurrence and spread of mercury contamination.
Amphibians↗
[Embryonic induction and development of the ultimobranchial body in the embryogenesis of amphibia].
At early embryonal and larval stages of development 7 species of amphibia have been studied. The ultimobranchial anlage and processes resulted in formation of the secretory follicle are investigated. Dynamics on changes of amount of the gland cells and the first appearance of capillaries are analyzed. In Anura and Urodela the anlage of the ultimobranchial gland develops from the epithelial lining of the pharynx behind the last branchial pocket rudiment. The gland is asymmetric and can be laid either in the right or in the left side of the body. Death of calcitonin-secreting cells is compensated at the expense of repeated anlage of follicles from the pharyngeal epithelium. The newly formed follicles can either incorporate into the existing gland, or form independent follicles. For amphibia formation of the capillary network around the gland after beginning of the follicular secretion is specific. Owing to these data, it is possible to conclude that the stimulus for the gland to become overgrown with capillaries is the beginning of calcitonin secretion.
Animals↗
Comparative morphometric study of the vestibular system of the vertebrata: reptilia, aves, amphibia, and pisces.
Morphometric measurements were made from serial sections of the vestibular system in four classes of vertebrates: Reptilia, Aves, Amphibia, and Pisces. Representative species of reptile studied were the lizard (Gekko gecko), the common garter snake (Thamnophis sp.), and the common turtle (Chelonia sp.). The budgie (Melopsittacus undulatas), the common pigeon (Columba domestica), the yellow-bellied sapsucker (Sphyrapicus varius), and the horned owl (Bubo virginianus) were chosen as representative of the bird. For the amphibian, the leopard frog (Rana pipiens), and the mud puppy (Necturus maculatus) were chosen for study. As representative of the fish, the goldfish (Carassius auratus), the tilapia (Tilapia mossambica), the guppy (Lebistes sp.), and the sea horse (Hippocampus sp.) were used in these measurements. The morphometric data obtained were then used in estimates of the time constants in the Steinhausen equation which describes the biophysics of fluid flow in the semicircular canals. In general, the time constants (theta/II in the Steinhausen equation) of these representatives of Reptilia, Aves, and Amphibia were of magnitude similar to those reported in mammals, despite the dissimilarities in the diameters of the ducts, the duct radii of curvature, the dimensions of the cristae ampullares and the utricle, and volumes of endolymph within the vestibular system. However, the short-time constants in Pisces were larger (therefore providing a slower response) than those in other vertebrates, and were similar to that of the turtle and the mud puppy.
Amphibians↗
Ultrastructure of the kidney of a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona). I. Renal corpuscle, neck segment, proximal tubule and intermediate segment.
The ultrastructure of the renal corpuscle, the neck segment, the proximal tubule and the intermediate segment of the kidney of a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona) was examined by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and freeze-fracture technique. The glomerular filter apparatus consists of the podocyte epithelium, a distinct basement membrane, a subendothelial space and the capillary endothelium. Emanating from the podocyte cell body, several long primary processes encircle neighboring capillaries. The short slender foot processes originating from the primary processes interdigitate with those from other primary processes, thereby forming the meandering filtration slit. Thick bundles of microfilaments are found in the primary processes, but absent in the foot processes. The basement membrane consists of a lamina rara externa and a rather thin lamina densa (50 nm thickness). The wide subendothelial space contains abundant microfibrils, a few collagen fibrils and many thin processes of mesangial cells. The endothelium is flat and fenestrated (compared to mammals displaying relatively few fenestrations); some of the fenestrations are bridged by a diaphragm. The glomerular mesangium is made up of the mesangial cells and a prominent mesangial matrix containing microfibrils and collagen fibrils. The cells of the neck and intermediate segments display numerous cilia with their microtubules arranged in the typical 9 + 2 pattern. The basal bodies of the cilia are attached to thick filaments with a clear crossbanding pattern of 65 nm periodicity. The proximal tubule is composed of cells typical for this segment (PT cells) and light cells lacking a brush border (bald-headed cells). The PT cells measure 10-25 micron in height and 15-30 micron in width and do not interdigitate at their lateral borders with each other. Their basolateral cell membrane is amplified by many folds projecting into lateral intercellular spaces and into basal recesses. The brush border is scarce and composed of loosely arranged short microvilli.
Amphibians↗
Ultrastructure of the kidney of a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona). II. Distal tubule, connecting tubule, collecting duct and Wolffian duct.
The ultrastructure of the distal nephron, the collecting duct and the Wolffian duct was studied in a South American caecilian, Typhlonectes compressicaudus (Amphibia, Gymnophiona) by transmission and scanning electron microscopy (TEM, SEM). The distal tubule (DT) is made up of one type of cell that has a well-developed membrane labyrinth established both by interdigitating processes and by interlocking ramifications. The processes contain large mitochondria, the ramifications do not. The tight junction is shallow and elongated by a meandering course. The connecting tubule (CNT) is composed of CNT cells proper and intercalated cells, both of which are cuboidal in shape. The CNT cells are characterized by many lateral interlocking folds. The intercalated cells have a dark cytoplasm densely filled with mitochondria. Their apical cell membrane is typically amplified by microplicae beneath which a layer of globular particles (studs) is found. The collecting duct (CD) is composed of principal cells and intercalated cells, again both cuboidal in shape. The CD epithelium is characterized by dilated intercellular spaces, which are often filled with lateral microfolds projecting from adjacent principal cells. The apical membrane is covered by a prominent glycocalyx. The intercalated cells in the CD are similar to those in the CNT. The Wolffian duct (WD) has a tall pseudostratified epithelium established by WD cells proper, intercalated cells and basal cells. The WD cells contain irregular-shaped dense granules located beneath the apical cell membrane. The intercalated cells of the WD have a dark cytoplasm with many mitochondria; their nuclei display a dense chromatin pattern.
Amphibians↗
Histological and histochemical observations on the neurosecretory cells in the diencephalon of Chthonerpeton indistinctum and Ichthyophis paucisulcus (Gymnophiona, Amphibia).
In the diencephalon of two species of Gymnophiona (Amphibia) two neurosecretory nuclei were examined with histological (Alcian Blue, Aldehyde Fuchsin, Brookes Trichrome stain) and enzyme histochemical techniques (acid phosphatase, alpha-naphthyl acetate esterase, acetylcholinesterase (AChE)). In the preoptic nucleus two categories of secretory neurons were distinguished: large and medium sized neurons. The perikarya of both cell types contain very little neurosecretory material. The Alcian Blue method stained the medium sized neurons faintly but selectively. The tractus praeopticohypophyseus is marked by the presence of Herring bodies, which, however, are relatively scarce. The neurohypophysis, in contrast, contains large amounts of neurosecretory material. Both cell types of the preoptic nucleus are characterized by their very strong AChE and alpha-naphthylacetate esterase activity. The AChE also marks the tractus praeoptico-hypophyseus. In the large neurons acid phosphatase is present around the nucleus; in the medium sized neurons this enzyme is concentrated close to the origin of the axon. In the dorso-caudal hypothalamus a small group of neurons is stained with Alcian-Blue. These neurons, which also contain AChE, are located immediately under the ependyma which seems to be specialized in this region.
Acetylcholinesterase↗
Chromosome banding in Amphibia. XII. Restriction endonuclease banding.
Fixed metaphase chromosomes of several species of Amphibia were treated with various restriction endonucleases and subsequently stained with Giemsa. Metaphases of man and chicken were examined in parallel under the same experimental conditions for comparison. The restriction enzymes always induce subsets of the C-banding patterns present in the amphibian karyotypes. The heterochromatic regions can be either resistant or sensitive to the restriction enzyme. The modified C-banding patterns revealed by different restriction endonucleases in the karyotype of the same species can be either extremely dissimilar or almost completely congruent. Correspondingly, the action of the same restriction enzyme on the karyotypes of different species may vary greatly. There is only rarely a correlation between the type of C-banding patterns produced by different restriction endonucleases and their specific base pair recognition sequences. In contrast to mammalian and avian chromosomes, restriction enzymes induce no multiple G-banding patterns in amphibian chromosomes. This is attributed to the difference in organization of the DNA in the genomes of poikilothermic vertebrates. The possible mechanisms of restriction endonuclease banding and the various uses of this technique for amphibian chromosomes are discussed.
Amphibians↗
Methylation of ribosomal cistrons in diploid and tetraploid Odontophrynus americanus (Amphibia, Anura).
Odontophyrynus americanus (Amphibia, Anura) genomic DNA from diploid and tetraploid specimens was treated with restriction enzymes sensitive to cytosine and adenine methylation (5 meC and 6 meA). In both diploids and tetraploids a high proportion of the total DNA was not cleaved by 5 meC-sensitive enzymes as observed on agarose gels stained with ethidium bromide. The DNAs were transferred to nitrocellulose filters and hybridized with cloned fragments containing sequences of Xenopus laevis 28S and 18S ribosomal DNA (rDNA). A high level of methylation of the ribosomal repeat units was revealed by 5 meC-sensitive enzymes in blood, liver, kidney and testis tissues. Adenine was methylated to a lesser degree and similarly in the rDNA from both germinative and somatic tissues. Comparison of the results obtained with DNA of diploids and tetraploids showed that methylation of ribosomal genes was increased in tetraploid genomes of adult frogs, but exact quantitative determinations could not be performed by this methodology. Cloning of the 28S region of the rDNA repeat unit was performed in the lambda gtWES lambda C vector. Restriction patterns obtained with methylation-sensitive enzymes using diploid and tetraploid derived clones confirmed the high level of methylation of the corresponding region of the ribosomal repeat unit in genomic DNAs. The implications of these results in the regulation of expression of the ribosomal genes in diploids and tetraploids are discussed.
Adenine↗
The organization of ribosomal genes in diploid and tetraploid species of the genus Odontophrynus (Amphibia, Anura).
The organization of the repeat unit of the ribosomal genes was determined in populations of Odontophrynus americanus 2n, 4n, O. occidentalis 2n and O. barrioi 2n (Amphibia, Anura) from South America. HindIII, EcoRI and BamHI restriction patterns of rDNA from single individuals were probed with two rDNA clones from Xenopus laevis. Variations in length and sequence were found among different species, populations and specimens. A general pattern could be established from the most frequent type of repeat observed in each case, so that diploid populations could be distinguished from tetraploid ones. The molecular evolution of variant repeats is discussed. It is suggested that the reduced size of the non-transcribed spacers in the tetraploids from São Paulo could play a role in the control of rDNA transcription. Distinct restriction maps were tentatively correlated to the varying localization of active rDNA clusters on metaphase chromosomes of corresponding populations.
Animals↗
Chromosome banding in Amphibia. XVII. First demonstration of multiple sex chromosomes in amphibians: Eleutherodactylus maussi (Anura, leptodactylidae).
A cytogenetic study performed on a population of the South American leptodactylid frog Eleutherodactylus maussi revealed multiple sex chromosomes of the X1X1X2X2 female/X1X2Y male (= XXAA female/XXAY male) type. The diploid chromosome number is 2n = 36 in all females and 2n = 35 in most males. The multiple sex chromosomes originated by a centric fusion between the original Y chromosome and a large autosome. In male meiosis the X1X2Y (= XXAY) multiple sex chromosomes form a classical trivalent configuration. E. maussi is the first species discovered in the class Amphibia that is distinguished by a system of multiple sex chromosomes. Only one single male was found in the population with 2n = 36 chromosomes and lacking the Y-autosomal fusion. This karyotype (XYAA male) is interpreted as the ancestral condition, preceding the occurrence of the Y-autosome fusion.
Animals↗
Two dispersed highly repeated DNA families of Triturus vulgaris meridionalis (Amphibia, Urodela) are widely conserved among Salamandridae.
Two BamHI families of repeated sequences were characterized from the genome of the Italian smooth newt, Triturus vulgaris meridionalis (Amphibia, Urodela). The first family, which is divided into subfamilies, consists of tandemly arranged arrays whose basic repeat is around 398 bp long; these arrays are dispersed throughout the entire chromosome sets of the various species of Triturus tested. Moreover the family is widely conserved among Salamandridae, being detected by genomic DNA blotting of Notophthalmus viridescens, Taricha granulosa, Salamandrina terdigitata and Euproctus platycephalus. The second BamHI family is represented by a cloned sequence of 419 bp, which is dispersed in the chromosome set of several species of Triturus. The sequence is also conserved in S. terdigitata and in E. platycephalus but is not detectable in N. viridescens or T. granulosa. The cloned sequence is most probably only part of a longer unit interspersed within the Triturus genome.
Animals↗
Immunocytochemical localization of a galanin-like peptidergic system in the brain of two urodele and two anuran species (Amphibia).
Galanin-like immunoreactivity was localized in the brain of Urodela (Ambystoma, Pleurodeles) and Anura (Bufo, Xenopus) by immunocytochemistry with anti-porcine galanin antiserum. In the four species, immunoreactive perikarya were observed in the telencephalon (striatum, amygdala), diencephalon preoptic area mainly along the anterodorsal wall of the preoptic recessus, suprachiasmatic nucleus, lateral hypothalamus, ventral and dorsal infundibular nuclei, paraventricular organ, and rhombencephalon (nucleus of the solitary tract). Galaninergic fibres extended in similar regions and in the medial septum, ventral telencephalon, ventral hypothalamus, median eminence, and various mesencephalic and rhombencephalic regions. Contacts with the cerebrospinal fluid cavity occurred along the preoptic recessus (Ambystoma) and the ventral infundibular wall (all species). Fibres were scarce in the neurohypophysis. The distal and intermediate lobes of the pituitary were virtually devoid of immunoreactivity. The galaninergic system appeared more developed in adult amphibia than in young animals, suggesting the stimulating influence of sex steroids on the expression of galanin as previously described in Anguilla. The extensive distribution of the galanin-like immunoreactive neurons in amphibian brains suggests that this peptide may act as a neuromodulatur and/or neurotransmitter.
Ambystoma↗
The structural organization of the kidney of Typhlonectes compressicaudus (Amphibia, Gymnophiona).
The structural organization of the kidney of Typhlonectes compressicaudus (Amphibia, Gymnophiona) was studied by light microscopic (LM) examination of serial paraffin and semithin Epon sections. The kidney is slender and quite long and has a mesonephric segmental construction; the excretory duct (Wolffian duct), running along the lateral side of the kidney, segmentally receives the terminal trunks of the collecting duct system. The nephron has the following parts: renal corpuscle, neck segment, proximal tubule, intermediate segment, distal tubule and connecting tubule. The distal tubule is located in a ventromedial (central) zone of the kidney; all other tubular segments lie in a dorsolateral (peripheral) zone. The renal corpuscles are found at the border between these two zones. The renal corpuscle is very large; its urinary pole faces the peripheral zone. A small proportion of neck segments receive either a nephrostomal duct or a blind branch. The proximal tubule is a thick, highly convoluted tubule. The intermediate segment is ciliated and makes a few coils. The distal tubule is composed of three portions: a highly convoluted part in the central zone, subsequently an attachment site with the renal corpuscle and a short postattachment-part. The connecting tubule and the collecting duct have a heterogeneous epithelium consisting of light and dark cells. The collecting duct is distinguished by dilated intercellular spaces. The Wolffian duct has a pseudostratified epithelium. The present study correlates the course and segmentation of the renal tubule of Typhlonectes. The tubule has three major convolutions. The first occurs in the proximal tubule in the peripheral zone; the second is established by the distal tubule and occurs in the central zone; the third is formed by the connecting tubule and is found in the peripheral zone.
Amphibians↗
Comparative metabolism of histamine in two Amphibia anura.
The metabolism of histamine has been compared in Rana ridibunda and Discoglossus pictus, both Amphibia anura. An intralymphatic injection of 14C-histamine (5 microCi) was administered to the animals and the total radioactivity excreted in the urine was measured 24, 48, and 72 hours later. The metabolites excreted in the urine at 24 hours were analyzed by thin-layer chromatography and subsequent autoradiography. In both species approximately 60--70% of the injected dose was found in the urine by 72 hours. In Rana ridibunda two histamine metabolites were found: imidazoleacetic and methylimidazoleacetic acid. The present results suggest that the catabolism of histamine differs in the two species.
Amphibians↗
A comparative study of the innervation of the choroid plexus in amphibia.
The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.
Acetylcholine↗
3,5,3'-Triiodothyronine receptors and thyroxine 5'-monodeiodinating activity in thyroid hormone-insensitive amphibia.
Adult anuran Amphibia and neotenous urodeles, such as Necturus maculosus, rarely respond to thyroid hormone (TH). In this study, the possibility was examined that this lack of response is due either to an inability to convert thyroxine (T4) to 3,5,3'-triiodothyronine (T3) or to the absence of nuclear TH receptors. Following injection of [125I]T4, significant amounts of [125I]T3, analyzed by chromatography, were detected in the serum and liver of Necturus and Rana catesbeiana frog indicating that both possesses a T4 5'-monodeiodinating system. Nuclear binding of T3 was studied in suspensions of purified hepatic nuclei and intact red blood cells (RBC). Analysis of binding data revealed that frog liver nuclei contained two sets of saturable T3 binding sets with affinities comparable to those of the two sets of sites previously demonstrated in tadpole liver nuclei (Galton and Schaafsma, 1983). However, the number of sites per nuclei was small compared to tadpole; expressed as pmol/mg DNA, the maximum binding capacity of the high affinity set of sites (MBC1) was 2.2 +/- 0.31 versus 12.9 +/- 1.80 and MBC2 was 24.9 +/- 4.5 versus 42.2 +/- 54. Receptor number in RBC nuclei was also smaller in frog than tadpole: 90 +/- 26 versus 882 +/- 56 sites/nucleus (Kd less than 10(-11) M in both groups). No comparable high affinity binding sites were detected in Necturus liver, but some sites were found in Necturus RBC. These cells contained 2111 +/- 120 sites/nucleus, more than twice the number found in tadpole.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗