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PubMed2002

Parathyroid hormone-related protein in lower vertebrates.

The genes for parathyroid hormone-related protein (PTHrP) have been cloned in two teleost fishes, cDNA of sea bream (Sparus aurata) and genomic DNA of puffer fish (Fugu rubripes). The gene sequences show that there is significant conservation of amino acid identity, with specific domains most highly conserved. The N-terminus, responsible for bone matrix lysis in mammals and chickens, is present in the fish genes with 52% sequence identity to higher vertebrate PTHrP peptides; the nuclear transporter region shares 73% identity, and the RNA-binding sequence is 65% identical. However, the peptides are shorter then mammalian PTHrP, lacking the C-terminus responsible for inhibition of osteoclast lytic activity, but they have an additional inserted sequence between amino acids 38 and 54 that is not present in higher vertebrate PTHrPs. The N-terminus 1-38 Fugu PTHrP proved to be hypercalcaemic in larval Sparus, suggesting that it may be a physiological regulator of calcium homeostasis in fish. Using homologous nucleotide probes for in situ hybridisation and reverse-transcription polymerase chain reaction (RT-PCR) of extracted RNA, PTHrP gene expression has been widely found in both developing and adult fish. Antiserum to the fish insert sequence demonstrated transcription of PTHrP in all stages of Sparus development, and also detected the same epitope in tissues of developing frog (Rana temporaria), indicating that this has been retained during evolution of the amphibia.

Amino Acid Sequence↗
PubMed2002

A male-specific (cysteine-rich) protein of Oesophagostomum dentatum (Strongylida) with structural characteristics of a serine protease inhibitor containing two trypsin inhibitor-like domains.

A cDNA was isolated from an adult male Oesophagostomum dentatum gene library by screening with a male-specific, partial expressed sequence tag (EST) probe identified previously using a differential display technique. The full-length cDNA of 642 bp included 5' and 3' untranslated regions of 44 and 121 nucleotides, respectively, and encoded a predicted protein with a putative 18 amino acid signal sequence and a mature polypeptide of 14.7 kDa comprising approximately 15% cysteine residues. The amino acid sequence showed similarity with a number of proteins from Caenorhabditis elegans, parasitic nematodes, insects and amphibia, all of which contain a trypsin inhibitor-like cysteine-rich domain. A 3-dimensional structure model constructed for the O. dentatum protein (designated OdmCRP) inferred that it is composed of 2 domains, each with 5 disulfide bonds, which are indicative of the Ascaris family of serine protease inhibitors. These findings indicate that OdmCRP, with 2 structural domains relating to functionally active sites, is a new member of this inhibitor family.

Amino Acid Sequence↗
PubMed1989

Molecular cloning of cDNA for proteasomes (multicatalytic proteinase complexes) from rat liver: primary structure of the largest component (C2).

Proteasomes (multicatalytic proteinase complexes) from rat liver are composed of at least 13 nonidentical components [Tanaka, K., Yoshimura, T., Ichihara, A., Ikai, A., Nishigai, M., Morimoto, M., Sato, M., Tanaka, N., Katsube, Y., Kameyama, K., & Takagi, T. (1988) J. Mol. Biol. 203, 985-996]. The nucleotide sequence of one major component (C2) of the proteasomes has been determined from a recombinant cDNA clone isolated by screening a rat liver cDNA library with a mixture of synthetic deoxyribonucleotides as a probe. The sequence was composed of 1174 nucleotides including a coding region for the entire protein and noncoding regions of both the 5'- and 3'-sides. The polypeptide deduced from the open reading frame consisted of 263 amino acid residues, and its molecular weight was calculated to be 29,516. The partial amino acid sequences of several fragments (approximately 45% of the total residues), which were obtained by cleavage of C2 with lysyl endopeptidase and cyanogen bromide, were determined by automated Edman degradation and found to be in complete accordance with those deduced from the cDNA sequence. The amino acid composition of C2, determined by chemical analysis, was also consistent with that deduced from the cDNA sequence, indicating that the cloned cDNA actually encoded component C2. Computer analysis revealed little structural similarity of C2 to other proteins reported so far. Northern blot hybridization analyses showed that the mRNA encoding this novel protein C2 was expressed in all the rat tissues examined and in a variety of eukaryotic organisms such as amphibia, birds, and mammals with slight species-specific differences in size.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2000

The distribution of monogenean parasites on aquatic vertebrates inhabiting Chinese inland waters.

The general distribution of monogenean parasites of aquatic vertebrates inhabiting Chinese inland waters is summarised. Five hundred and seventy-two out of a total of 581 species of monogeneans were discovered on fish, while only nine species were found on Amphibia and Reptilia. Most dactylogyrids and diplozoids parasitise cyprinids, while ancyrocephalids occur on silurids and cyprinids, and gyrodactylids are found mainly on cyprinids and cobitids. Analyses of host-specificity and host-diversity suggests that the family Ancyrocephalidae should be divided into several families parallel with the Dactylogyridae. Of 12 subfamilies of the Cyprinidae, only the Gobiobotinae was found to be free of infection with monogeneans, and the genus Dactylogyrus has more species than any other monogenean genus associated with every cyprinid subfamily.

Amphibians↗
PubMed2000

Cytological and molecular analysis in the rare discoglossid species, Alytes muletensis (Sanchiz & Adrover 1977) and its bearing on archaeobatrachian phylogeny.

Cytogenetic and molecular data on Alytes muletensis (Amphibia: Discoglossidae) are compared with other representatives of archaeobatrachian frogs: Bombina variegata pachypus, Pelobates cultripes, Pelodytes punctatus, Xenopus laevis, and Discoglossus. A. muletensis has the karyotype typical for the genus Alytes, 38 elements with either one or two arms, some of which can be considered as 'microchromosomes'. The NORs are located on the telomeres of the tenth chromosome pair which agrees with the state in A. obstetricians but differs from A. cisternasii reflecting phylogenetic affinities. C-banding and staining with DAPI and chromomycin A3 revealed important blocks of telomeric CMA-positive heterochromatin on the smaller chromosomes of Alytes, similar to the state found in Discoglossus. Phylogenetic analysis of 750 bp of fragments of the mitochondrial 16S and 12S rRNA genes corroborated that Discoglossus and Alytes are sister taxa which together probably form the sister group of the Bombinatorinae. Centromeric heterochromatin in Alytes may be responsible for the retention of a plesiomorphic asymmetric karyotype which independently has evolved into a symmetric karyotype through centric fusions in Bombina and Discoglossus. The HindIII satellite DNA family was present in all archaeobatrachians studied but absent in hyloid and ranoid neobatrachians.

Amphibians↗
PubMed2000

Apoptosis and the cell cycle in Xenopus: PMA and MPMA exposure of splenocytes.

Spontaneous and induced cancers are rare in non-isogeneic or inbred amphibians. Neoplastic cells become immortalized through loss of a normal capacity to die by apoptosis. Mature lymphocytes of mammals require activation and entry into the cell cycle in order to become susceptible to apoptosis. Whether Xenopus lymphocytes differ from mammalian lymphocytes in this regard is examined. In vitro exposure of PMA, or its analogue, MPMA, to adult splenocytes of Xenopus laevis was used to affect apoptosis. Flow cytometric analysis of FITC-Annexin V/propidium iodide (PI) fluorescence (apoptosis) and BrdU uptake (DNA synthesis) were assayed concurrently in the same lymphocyte population over time. Significant increases in apoptotic levels were induced throughout a 72 hour period in PMA-treated cells only. Lymphocytes were also separated by size for analysis. Several subpopulations of lymphocytes were identified, the most interesting of which was small and apoptotic within 4 hours, after PMA exposure. PMA-induced DNA synthesis did not become elevated until after 24 hours. "Direct" apoptosis, i.e. without cell cycle entry, was found only in these small, mature lymphocytes. Since small lymphocytes make up the vast majority of those being analyzed, "direct" apoptosis may be a determining mechanism in the resistance to neoplasia observed in Amphibia. Cells that die more readily are less likely to transform into neoplastic cells.

Animals↗
PubMed2000

Tyrosinase gene expression in the Kupffer cells of Rana esculenta L.

The liver of Amphibia and Reptilia shows a dark-brown pigmentation due to the presence of particular melanin-containing cells that are different from melanocytes and derive from cells of macrophage lineage (Kupffer Cells), which have been shown to have an autonomous capacity to synthesize melanins. To date, as far as we know, there are no reports in the literature about the genetic system of tyrosinase as regards these melanin-synthesizing cells; we carried out the present study to analyze how the tyrosinase gene may function. We showed that the Kupffer cells of Rana esculenta L. do indeed have a transcriptionally active tyrosinase gene. Evidence of this was obtained by reverse transcription polymerase chain reaction analysis carried out on both the liver tissue and the Kupffer cells in culture. Moreover, analysis of the cells in culture enabled us to observe that, by increasing the culture time from 0 to 72 hr, an appreciable increase occurred in the amplification products of the tyrosinase gene, as well as in the level of dopa oxidase activity and in the quantity of melanin in the cells. The results of the present study demonstrate that frog Kupffer cells possess an active tyrosinase gene and that the increase of the tyrosinase mRNA accumulation closely correlates with phenotypic differentiation, in terms of increased dopa oxidase activity and melanosome content. This provides further strong support of the hypothesis that amphibian Kupffer cells possess an endogenous ability to synthesize melanin and suggests the involvement of the transcriptional level of control in the modulation of their melanogenic activity.

Animals↗
PubMed1999

A new secreted protein that binds to Wnt proteins and inhibits their activities.

The Wnt proteins constitute a large family of extracellular signalling molecules that are found throughout the animal kingdom and are important for a wide variety of normal and pathological developmental processes. Here we describe Wnt-inhibitory factor-1 (WIF-1), a secreted protein that binds to Wnt proteins and inhibits their activities. WIF-1 is present in fish, amphibia and mammals, and is expressed during Xenopus and zebrafish development in a complex pattern that includes paraxial presomitic mesoderm, notochord, branchial arches and neural crest derivatives. We use Xenopus embryos to show that WIF-1 overexpression affects somitogenesis (the generation of trunk mesoderm segments), in agreement with its normal expression in paraxial mesoderm. In vitro, WIF-1 binds to Drosophila Wingless and Xenopus Wnt8 produced by Drosophila S2 cells. Together with earlier results obtained with the secreted Frizzled-related proteins, our results indicate that Wnt proteins interact with structurally diverse extracellular inhibitors, presumably to fine-tune the spatial and temporal patterns of Wnt activity.

Adaptor Proteins, Signal Transducing↗
PubMed1980

Brillouin scattering, density and elastic properties of the lens and cornea of the eye.

Brillouin spectra of biological systems may ultimately be related to their intrinsic molecular properties. In some instances the optical properties may be associated with the elastic ones and ultimately with the force constants of the molecules involved. In the present work we have used a triple-pass Fabry-Perot interferometer to measure Brillouin light scattering spectra for refractive tissues of the eye, including cornea, capsule and lens. Combined with corresponding measurements of density, estimates of the real and imaginary parts M' and M'' of the longitudinal bulk modulus have been made for the first time. Measurements have extended over four classes of vertebrate: Mammalia, Aves, Pisces and Amphibia; only small differences have been found between the various samples of cornea, whereas marked differences occur between the different lenses. Hence this account concentrates largely on the latter. The implications of this work lie not so much at the ophthalmological level as at the macromolecular and offer, in conjunction with other scattering techniques, opportunities for probing the lens and its proteins topographically as a function of growth.

Acoustic Stimulation↗
PubMed1983

First observation of a muscle spindle in fish.

In many groups of vertebrates, the muscle spindle is a specialized sensory organ for the detection of muscle stretching. The structure of the spindle varies among vertebrate classes. Moreover, Barker has asserted that Amphibia are the most primitive vertebrates to possess muscle spindles. Extensive studies, made mainly on the locomotor myotome, seem to show that the muscle receptors of fish are less specialized than those of more advanced animals, and that muscle spindles are absent. However, little attention has been paid to the jaw-closing muscle. We report here our finding of a very simple muscle spindle with a single intrafusal fibre in the well-developed jaw-closing muscle, adductor mandibulae, in a primitive teleostean, Oncorhynchus masou (Brevoort).

Animals↗
PubMed1989

Identification of a widespread nuclear actin binding protein.

The many different cellular functions so far shown to involve actin and to be regulated by specific actin binding proteins are located primarily, if not exclusively, in the cytoplasm. Actin is also found in the nucleus of various cells, but because of the problems of cell fractionation the significance of nuclear actin has remained unclear. The large amphibian oocyte nucleus (germinal vesicle), however, can be isolated manually with little cytoplasmic contamination. This nucleus contains high concentrations (4-6 mg ml-1) of mostly soluble, although polymerization-competent beta- and gamma-actin, which exists in a nucleocytoplasmic exchange pool. The findings that drastic effects on transcription and chromosome morphology are caused by the injection of actin antibodies or actin binding proteins into germinal vesicles, and that a factor required for accurate transcription by RNA polymerase II is actin, suggest that nuclear actin is involved in specific nuclear functions. We have recently identified two main components in Xenopus laevis oocytes with actin binding activities; one of these activities is Ca2+-dependent, is located predominantly, if not exclusively, in the cytoplasm and is attributable to gelsolin. Here we report that the second component, having a Ca2+-independent activity, is a heterodimeric acting binding protein; this protein is markedly enriched in the nuclei of oocytes and somatic cells of amphibia, but also occurs in nuclei of other vertebrate cells.

Actins↗
PubMed2004

DNA demethylation is necessary for the epigenetic reprogramming of somatic cell nuclei.

Nuclear transplantation experiments in amphibia and mammals have shown that oocyte and egg cytoplasm can extensively reprogram somatic cell nuclei with new patterns of gene expression and new pathways of cell differentiation; however, very little is known about the molecular mechanism of nuclear reprogramming. Here we have used nuclear and DNA transfer from mammalian somatic cells to analyse the mechanism of activation of the stem cell marker gene oct4 by Xenopus oocytes. We find that the removal of nuclear protein accelerates the rate of reprogramming, but even more important is the demethylation of somatic cell DNA. DNA demethylation seems to precede gene reprogramming, and is absolutely necessary for oct4 transcription. Reprogramming by oocytes occurs in the absence of DNA replication and RNA/protein synthesis. It is also selective, operating only on the promoter, but not enhancers, of oct4; both a putative Sp1/Sp3 and a GGGAGGG binding site are required for demethylation and transcription. We conclude that the demethylation of promoter DNA may be a necessary step in the epigenetic reprogramming of somatic cell nuclei.

Animals↗
PubMed1970

Measurement of uridine diphosphate glucuronic acid concentrations and synthesis in animal tissues.

1. A method for the isolation from animal tissues of UDP-glucuronic acid by one-dimensional paper chromatography is described and its concentrations in some tissues of several species of vertebrates are reported; the incorporation of [(32)P]-phosphate into UDP-glucuronic acid in vivo was also investigated. 2. The concentration of UDP-glucuronic acid was higher in the liver of rats, rabbits and guinea pigs than in the same tissue of some species of birds, amphibia and fishes; also, the concentration of UDP-glucuronic acid in rat liver, kidney and small intestine was several times lower than that of the same tissues of guinea pigs. 3. The rate of [(32)P]-phosphate incorporation into UDP-glucuronic acid was very high in rat liver and kidney and almost reached equilibrium with the radioactivity of UDP-glucose 30min after the administration of the [(32)P]phosphate.

Animals↗
PubMed2002

The molecular mechanism for the spectral shifts between vertebrate ultraviolet- and violet-sensitive cone visual pigments.

The short-wave-sensitive (SWS) visual pigments of vertebrate cone photoreceptors are divided into two classes on the basis of molecular identity, SWS1 and SWS2. Only the SWS1 class are present in mammals. The SWS1 pigments can be further subdivided into violet-sensitive (VS), with lambda(max) (the peak of maximal absorbance) values generally between 400 and 430 nm, and ultraviolet-sensitive (UVS), with a lambda(max)<380 nm. Phylogenetic evidence indicates that the ancestral pigment was UVS and that VS pigments have evolved separately from UVS pigments in the different vertebrate lineages. In this study, we have examined the mechanism of evolution of VS pigments in the mammalian lineage leading to present day ungulates (cow and pig). Amino acid sequence comparisons of the UVS pigments of teleost fish, amphibia, reptiles and rodents show that site 86 is invariably occupied by Phe but is replaced in bovine and porcine VS pigments by Tyr. Using site-directed mutagenesis of goldfish UVS opsin, we have shown that a Phe-86-->Tyr substitution is sufficient by itself to shift the lambda(max) of the goldfish pigment from a wild-type value of 360 nm to around 420 nm, and the reverse substitution of Tyr-86-Phe into bovine VS opsin produces a similar shift in the opposite direction. The substitution of this single amino acid is sufficient to account therefore for the evolution of bovine and porcine VS pigments. The replacement of Phe with polar Tyr at site 86 is consistent with the stabilization of Schiff-base protonation in VS pigments and the absence of protonation in UVS pigments.

Animals↗
PubMed1992

Evolutionary conservation of the dystrophin central rod domain.

Dystrophin cDNA fragments encoding the C-terminal repeats of the central rod region have been expressed as fusion proteins. The polyclonal antisera raised to the purified fusion proteins have been characterized and neither antiserum cross-reacted with dystrophin-related protein. Antisera detected dystrophin with molecular mass close to that of the human in all terrestrial vertebrates and amphibia studied. Experiments with antisera to the N-terminal region of the dystrophin rod confirmed that epitopes to the rod region were conserved during this evolutionary period and the length of this domain remained unaltered.

Animals↗
PubMed2000

Maternal control of sex ratio in Rana rugosa: evidence from DNA sexing.

Parental control of primary sex ratio has been reported in a mammal (red deer), some birds, and a snake. However, it remains uncertain whether other vertebrates including Amphibia can control sex ratio. In this paper, we examined the possibility in a wild population of the Japanese frog Rana rugosa which has female heterogamety. Sex ratios of their eggs were determined using DNA markers. The eggs were sampled in the field from May to August in 1998. Each egg was then sexed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using a sex-specific DNA marker. The result showed a male bias early in the season which changed to a female bias later, suggesting that females of R. rugosa can control the primary sex ratio.

Animals↗
PubMed1997

Evidence that "pinin", reportedly a differentiation-specific desmosomal protein, is actually a widespread nuclear protein.

A protein recently described as a desmosome-specific molecule involved in anchoring intermediate-sized filaments (IFs) to the desmosomal plaque, and hence named "pinin" [43], has been known in our laboratory for several years as a strictly nuclear protein occurring in a wide range of cell types, including many that are totally devoid of desmosomes. Using a series of specific antibodies we have localized the protein in the nucleoplasm of cultured cells, blood cells and solid tissues of diverse vertebrate species, from oocytes to erythrocytes of amphibia and from liver to connective tissue and fibroblasts in mammals. Desmosomes have consistently been negative, and the nuclear specificity of the immunolocalization reactions has also been directly demonstrated by double-label immunofluorescence microscopy. From our results we conclude that this nuclear protein, characterized by a domain exceptionally rich in serine residues and hence termed DRS-protein, occurs in at least two genetically different forms in a diffusible state as well as in special ribonucleoprotein-particles, "speckles" [6], and is a widespread if not ubiquitous nuclear protein. Consequently it must serve nuclear functions rather than "pinning" IFs to plasma membranes and does not provide a new reliable marker for desmosomes and epithelial or myocardial differentiation.

Amino Acid Sequence↗