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PubMed1981

A comparative study of the deacetylation of paracetamol by urodele and anuran amphibian organ cultures.

1. p-Aminophenol is the major metabolite produced by urodele amphibian tissues in vitro. The deacetylation enzyme system involved is located in the liver microsomal fraction of Amphiuma means. 2. Paracetamol was deacetylated to p-aminophenol by organ cultures of liver, kidney, pancreas and stomach epithelium from adult A. means, by liver, stomach epithelium, bladder and lung cultures from neotenic larval Ambystoma tigrinum, and by adult Triturus cristatus carnifex in vivo. 3. Liver cultures from all seven urodele amphibian species metabolized paracetamol and produced p-aminophenol, but no evidence was found of paracetamol metabolism by liver cultures from any of five anuran amphibian species. 4. The significance of p-aminophenol production from paracetamol and of this difference within the Amphibia are discussed.

Acetaminophen↗
PubMed1984

Retinal carbonic anhydrase: a comparative study.

Activity levels of carbonic anhydrase (E.C. 4.2.1.1) were measured in the retina and pigment epithelium of thirteen vertebrate species. The animals cover five taxonomic classes and among them illustrate four different retinal vascular supply patterns. The species can also be grouped according to their temperature regulatory mechanisms; i.e., homeothermic or poikilothermic. Significant differences are observed when the enzyme activities are examined by taxonomic class-birds and reptiles appear to have very high levels of enzyme activity; mammals and fish, moderate levels; and amphibia, low levels. When the enzyme activities are regrouped according to either vascular structure or temperature regulation, no significant differences are observed. From this, it is concluded that the level of carbonic anhydrase required by retinal tissue is not directly related to either of these factors. Carbonic anhydrase activity in kidney was compared with that in retina/pigment epithelium. Retina/pigment epithelium values are as great or greater than those in kidney but show a wider range. Only mammalian and avian kidney CA activity levels are high. We suggest that carbonic anhydrase levels in retina/pigment epithelium may be responsive to factors which influence vitreo-retinal ion and pH gradients.

Animals↗
PubMed1991

Immunologic conservation of the fiber cell beaded filament.

Lenses were obtained from the eyes of four different classes of Chordates, including Mammalia (rat, mouse, cow, human), Aves (chicken), Amphibia (tiger salamander), and Osteichthyes (steelhead), as well as from one Mollusca (squid). Buffer soluble, urea soluble and urea insoluble fractions were prepared from each, and probed by western blot analysis for the presence of the lens fiber cell 115 and 49 kD beaded filament proteins. Application of both polyclonal and monoclonal antibodies revealed that an immunologic homologue to the bovine fiber cell 115 kD protein is present in all examples of Chordates tested, and that this homologue possessed properties very similar to those of its bovine counterpart. Both monoclonal and polyclonal antibodies revealed an immunologically cross-reactive homologue in squid as well, but suggested that the squid protein had a native molecular weight of closer to 70-80 kD. A monoclonal antibody to the bovine 49 kD beaded filament protein was successful at identifying an immunologic homologue to this protein in mouse, chicken, and tiger salamander. Ultrastructural analysis of rat, human, and fish lenses showed that a beaded filament was present in these lenses, which was indistinguishable from that seen in the bovine lens. In the squid a filamentous, beaded structure was observed, but it differed from that seen in the bovine lens. We conclude from the data presented that the beaded filament, and its constituent proteins, are well-conserved. This data should facilitate the identification of lens cytoskeletal proteins and structure in a wide range of animal models, and establish that probes for these proteins may be of broad applicability.

Animals↗
PubMed1981

Topographic association of fibronectin with elastic fibers in the arterial wall. An immunohistochemical study.

Rabbit antibodies to human fibronectin which recognize tissue fibronectin and lack species-specificity have been employed to localize this molecule in the arterial wall of different animal species by indirect immunofluorescence. Fibronectin has been found to be consistently associated with both the inner and external aspects of the internal elastic membrane of large size arteries in mammals. Only scanty staining for fibronectin has been detected in collagen rich areas of the vessel wall, i.e. adventitia. This topographic association of fibronectin and internal elastic membrane is maintained in large size arteries (aorta, truncus arteriosus) of all species studied, including reptiles, amphibia and fish. The present findings suggest that fibronectin may mediate the contraction of vessel wall structures (i.e. elastic membranes) which lack an intrinsic contractile activity.

Amphibians↗
PubMed1983

A modified differential stain for cartilage and bone in whole mount preparations of mammalian fetuses and small vertebrates.

Fixation in formol-acetic-alcohol as a prelude to the staining of whole mount vertebrate skeletons with alcian blue and alizarin red S has greatly facilitated the enzyme clearing step of the method outlined by Dingerkus and Uhler. The modified method has been tested on fetal and neonatal mice, and on a variety of vertebrates including bony fish, reptiles, amphibia and birds, and shown to be rapid, reproducible and permanent. The method is not so rapid as that reported by Kimmel and Trammell but is superior at least in certain circumstances. In the present study, optimal results were obtained by fixing in formol-acetic-alcohol for 40 minutes, staining cartilage with alcian blue 8GX, then clearing with trypsin. The time taken to complete the latter step was reduced significantly by incubation at 37 C. The next step was to stain bone using alizarin red S in a weak solution of potassium hydroxide, followed by clearing in a potassium hydroxide-glycerol series.

Amphibians↗
PubMed1993

Immunocytochemical detection of bromodeoxyuridine in tissues of the toad Bufo arenarum Hensel.

We present a modified protocol for the immunocytochemical identification of 5-bromo-2'-deoxyuridine (BrdU) as an indicator of cell replication in different tissues of the toad, Bufo arenarum Hensel. Animals were sacrificed 60 min after BrdU (5 mg/100 g body weight) was injected into the dorsal lymph sac. The tissues were fixed in Carnoy's fluid and stained by the immunoperoxidase method using an anti-BrdU monoclonal antibody. This protocol can be used safely for the study of cell replication in toads and other Anura amphibia.

Animals↗
PubMed1995

A new species of Chloromyxum (Myxozoa: Chloromyxidae) from the gall bladder of Eurycea spp. (Caudata: Plethodontidae) in North America.

A previously undescribed species of Chloromyxum (Myxozoa: Chloromyxidae) was found in plasmodia adhering to the epithelium of the gall bladders in salamanders of the genus Eurycea (Caudata: Plethodontidae) from Arkansas and Texas (USA) in November, December, and January, 1987 to 1994. Bivalved spores of Chloromyxum salamandrae sp. n. from Eurycea multiplicata griseogaster (type host) were subspherical, with a mean size +/- SD of 8.3 +/- 0.3 x 7.7 +/- 0.4 (7.8 to 8.8 x 7.0 to 8.2) microns (n = 20), and had a shape index (length/width) of 1.07 +/- 0.03 (1.02 to 1.14). The valves measured 0.8 to 1.0 micron thick and had 10 to 12 external striations each. Each of the four polar capsules were piriform, with a mean size +/- SD of 4.0 +/- 0.1 x 2.6 +/- 0.1 (3.8 to 4.2 x 2.4 to 2.8) microns (n = 20), and there appeared to be about four coils of each polar filament. The sporoplasm was irregular in shape and appeared to be binucleate. Adherent plasmodia observed in winter months were small, with a mean size +/- SD of 31.5 +/- 6.3 x 24.9 +/- 2.6 (20 to 40 x 20 to 30) microns (n = 20), and contained zero to eight disporoblastic spores each. The myxozoan occurred in nine of 14 E. multiplicata griseogaster, three of eight E. multiplicata multiplicata, and two of 12 E. neotenes. This represents the first report of a Chloromyxum sp. from Amphibia in the Western hemisphere.

Animals↗
PubMed1976

[Incorporation of H3-thymidine into the oocytes of a sterlet in the early meiotic prophase].

DNA synthesis in meiotic oocytes of the sterlet (A. ruthenus) has been studied during early prophase stages using H3-thymidine. The pattern of H3-thymidine incorporation is similar to that in oocytes of Amphibia and Osteichthyes. In the oogonia as well as in the leptotene and zygotene oocytes, the label is predominantly localized over chromosomes. An intensive incorporation of H3-thymidine into the material of the heterochromatic "cap" has been observed during pachytene. Thus, the main synthesis of extra DNA in the sterlet oocytes occurs during pachytene. No DNA in synthesized by the diplotene oocytes.

Animals↗
PubMed1999

Head-organizing activities of endodermal tissues in vertebrates.

The embryonic organizer represents the major regulatory centre for the establishment of the body axes during gastrulation. Here, we discuss the endodermal contributions to the organizer of amphibia, birds and mammals. We differentiate between the definitive, prospective liver endoderm, and the primitive, prospective extraembryonic endoderm, the latter addressed as the hypoblast in birds and the visceral endoderm in mammals. We further discuss the role of the prechordal plate, a mesendodermal tissue underlying the prospective forebrain. Our conclusion points out the similarity of the amphibian and the avian organizer, with a concentration of inductive potentials in time and space. On the other hand, we discuss the unique feature of mammals, that have shifted certain aspects of the head organizer into the anterior visceral endoderm.

Amphibians↗
PubMed1999

Expression of human blood group antigens A and B in stomach cells of C. carpio, C. auratus, R. ridibunda and H. sapiens.

Human blood group ABH antigens are found not only on red blood cell membranes, but in many other cell types as well. Their biological functions still remain unclear. The aim of the present study was to examine the cellular expression of these antigens in the stomach of representatives of different Vertebrates--Pisces and Amphibia and to compare it with their expression found in Man. The immunohistochemical technique applied was based on the biotinstreptavidin-peroxidase complex. Monoclonal antibodies to human A and B antigens were used as primary antibodies in the system. Stomach paraffin sections from Cyprinus carpio, Carassius auratus, Rana ridibunda and Homo sapiens were examined. Blood group antigens were found mainly in tunica mucosa of C. carpio, C. auratus and R. ridibunda. Tunica muscularis and tunica serosa were always immunonegative. The antigens were localized in the apical part of the cytoplasm of epithelial cells in lamina epithelialis. Strong positive reaction was seen in secretory granules of the stomach of C. auratus, while in R. ridibunda the antigens were expressed by single epithelial cells in cardial stomach glands. A and B antigens were not found in human stomach sections most probably due to the negative secretor status of the individuals studied. Our results show that ABH human blood group antigens are evolutionary conserved structures similarly expressed by different Vertebrates. The phylogenetic stability in their cellular expression possibly results from the important biological role they have. Future large scale systematic investigations could elucidate the undefined and disputable physiological functions of human blood group antigens.

ABO Blood-Group System↗
PubMed1999

Pieter Nieuwkoop's contributions to the understanding of meso-endoderm induction and neural induction in chordate development.

Pieter Nieuwkoop, who died September 18, 1996, at age 79 in Utrecht, The Netherlands, is remembered by developmental biologists for his numerous research contributions and integrative hypotheses over the past 50 years, especially in the areas of neural induction, meso-endoderm induction, and germ cell induction in chordates. Most of his experimentation was done on the embryos of amphibia, the preferred vertebrate embryo of the early years of the 20th century. One of his last publications contains a comparison of the experimental advantages and disadvantages of anuran and urodele amphibians (Nieuwkoop, 1996). The significance of his findings and interpretations for developmental biology can be estimated from the fact that researchers of many laboratories worldwide continue to work on the phenomena he first described and to extend the hypotheses he first formulated. The aim of this article is to review Nieuwkoop's main contributions and to cite the recent extensions by others.

Animals↗
PubMed2000

Toxicity of a Neem (Azadirachta indica) insecticide to certain aquatic organisms.

Neem based insecticides are likely to show a large increase in use in the near future. In the present work, the toxicity of a neem insecticide, Neem-Azal-T/S, was tested against the mosquito larvae, as well as against certain non target organisms occurring in a polluted pond and a shallow stream, located in a cultivated area in Giza, Egypt. Samples of water containing the experimental animals were collected from this area, and toxicity tests were conducted in the laboratory by exposing them to a series of concentrations of the botanical insecticide, using the water of the pond and stream at room temperature (28-31 degrees C). The compound was more or less toxic to all the tested species. The LC50S and mortality rates were determined. The order of tolerance of the organisms to different concentrations of the insecticide was: larvae of Bufo regularis (Amphibia) > Aedes caspius. (Insecta) > Gambusia affinis (Poeciliidae) > Cyclops sp. > Daphnia magna (Crustacea). At a concentration of 20 ppm, all the tadpoles died within 9 days, while all other individuals died within 5 to 8 days after exposure to a concentration of 10 ppm of Neem Azal insecticide.

Aedes↗
PubMed2001

The avian organizer.

The development of avian embryos is characterized by the large amount of yolk present from the one-cell stage until late phases of organogenesis. In the chick, an axis of bilateral symmetry is established already before egg laying, when the egg rotates in the uterus. There is evidence for an active Wnt-catenin pathway in the vegetal cells in the periphery of the multi-cellular embryo. It overlaps with the posteriorly restricted expression of genes characterizing the vegetal hemisphere in amphibia. The zone of overlap bears several functional characteristics of a Nieuwkoop center, which is first apparent in the posterior marginal zone, but continues into the early primitive streak. Only the anterior part of the late streak is capable of direct neural induction, and only its tip, Hensen's node, can induce an anterior neural identity. This latter activity leaves the node together with the cells representing the anterior mesendoderm. Thus, although the constraints and dynamics of avian development make comparisons with the amphibian situation a complex undertaking, Hensen's node comes as close as possible to an organizer in Spemann and H. Mangold's definition.

Animals↗
PubMed2001

Germ cells, gonads and sex reversal in marsupials.

The formation of the testis or ovary is a critical step in development. Alterations in gonadal development during fetal or postnatal life can lead to intersexuality or infertility. Several model systems have been particularly useful in studying gonadal differentiation, the eutherian mammal and amphibia, fish, and birds. However, marsupials provide a unique opportunity to investigate gonadal development and the interactions of genes and hormones in gonadal differentiation and germ cell development in all mammals. On the one hand the genetic mechanisms appear to be identical to those in eutherian mammals, including the testis-determining SRY gene. On the other hand, marsupials retain in part the plasticity of the amphibian gonad to hormonal manipulation. It is possible to induce female to male and also male to female gonadal sex reversal in marsupials by hormonal manipulation, and oestradiol can induce male germ cells to enter meiosis at the time the oogonia do. In addition, in marsupials the development of the scrotum and mammary glands are independent of testicular androgens and instead are controlled by a gene or genes on the X-chromosome. Thus marsupials provide a number of opportunities for manipulating the sexual differentiation of the gonads that are not possible in eutherian mammals and so provide a unique perspective for understanding the common mechanisms controlling sexual development.

Animals↗
PubMed2002

Ernst Hadorn, a pioneer of developmental genetics.

This article gives a short and personal portrait of Ernst Hadorn (1902-1976), one of the most influential developmental biologists in Europe. Hadorn initially worked with amphibia, but then soon turned to Drosophila where he very successfully studied lethal factors and the development of imaginal disks.

Animals↗
PubMed1975

[Erysipeloid on the islands of the Sea of Okhotsk. I. The sources and vectors of the causative agent of erysipeloid].

The foci of the causative agent of erysipeloid at the islands of the Okhotsk sea were of the polyvector and polyhostal character. There were recorded 92 species of the naturally infected by the erysipeloid causative agent invertebrate inhabitants of the sea, fish, amphibia, reptilia, birds, mammals and ectoparasites of the warm-blooded animals. Gamazoid and ixodes ticks, mosquitoes, horse-flies and flees were found to be naturally infected with erysipelotrix. Ixodes persulcatus were found to be capable of infecting albino mice during blood sucking.

Animals↗
PubMedDate not supplied

[Human parasitizing echinostomatata (Trematoda, Fasciolidae) in mammals in Belorussian forest zone].

Domestic and wild mammals in Byelorussian Polesye have been found to have 3 species of echinostomatates known as human parasites: Echinochasmus perfoliatus (Ratz, 1908), Echinostoma revolutum (Froelich, 1802) and Isthmiophora (= Euraryphium) melis (Schrank, 1788). Human beings may be infected on ingestion of mollusks, fish, and Amphibia (frogs) invaded with larvae of these helminths. Although, cases of human invasion have not been recorded in Byelarus, there is an infection risk group, this should be borne in mind by medical workers.

Animals↗
PubMed1975

[Primary visual centers in Protopterus dolloi Boulenger].

Modifications of the Nauta's method (Fink-Heimer, Ebbesson-Heimer) were used to study the optic centers and pathways of rotoperus dolloi following unilateral enucleation. After ablation, animals were kept at 25degrees C from 6 to 51 days. We saw optimum degenerescences from 10 to 13 days of postoperatory life. Retinofugal fibers are completely crossed. The projections to necleus preopticus and hypothalamus seem to be bi-lateral. The mean primary optic centers are: the thalamic neuropil which is may be homologous with the Bellonci's neuropil in Amphilbia; the pretectal and tectal neuropils; the neuropil of the basal optic root. Results obtained in Protopterus can be compared with our knowledges in Amphibia.

Animals↗