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PubMed2001

Biochemical characterization and tissue distribution of human SULT2B1.

The human hydroxysteroid sulfotransferase (SULT) family is comprised of two subfamilies, SULT2A1 and SULT2B1. We characterized the substrate specificity, in vitro biochemical properties, and tissue distribution patterns of human SULT2B1a and SULT2B1b. In contrast to the wide substrate specificity of SULT2A1, SULT2B1a and SULT2B1b specifically catalyzed the sulfonation of 3beta-hydroxysteroids with high catalytic efficiency. Both SULT2B1 enzymes also sulfonated dihydrotestosterone. In vitro studies revealed that the biochemical properties of SULT2B1a and SULT2B1b were not significantly different from each other. However, tissue expression analysis suggested that they are differentially regulated. In contrast to the limited tissue distribution of SULT2A1, SULT2B1 was detected in a variety of hormone-responsive tissues including placenta, ovary, uterus, and prostate. The catalytic activity toward dehydroepiandrosterone and dihydrotestosterone, biologically important androgens, coupled with expression in prostate suggests that SULT2B1 may play a novel regulatory role that protects against the mitogenic effects of androgens.

Amino Acid Sequence↗
PubMed2002

Molecular basis of bird respiration: primary hemoglobin structure component from Tufted duck (Aythya fuligula, Anseriformes)--role of alpha99Arg in formation of a complex salt bridge network.

The primary structure of the major hemoglobin component, HbA (alpha(A)- and beta-chain), from Tufted duck (Aythya fuligula) is presented. The separation of the globin subunits was achieved by ion exchange chromatography on CM-cellulose in 8 M urea. The amino acid sequence was determined by automatic Edman degradation of native chains as well as tryptic and hydrolytic peptides in a gas-phase sequencer. The automated homology model was generated by the protein structure modeling package WHAT IF using the crystal structure coordinates of Bar-headed goose hemoglobin. The 3D structure prediction enables alpha99Arg and beta101Glu to emerge as a new intersubunit contact site not found in the hemoglobin structure of any other species. alpha99Arg forms a complex salt bridge network involving alpha99Arg-beta101Glu-beta104Arg-beta108Asp. Also the substitution at alpha34 --> Ile, alpha38 --> Gln and beta55 --> Leu serves to stabilize the oxy-structure, leading to higher oxygen affinity.

Amino Acids↗
PubMed1999

Blood PCB, p,p'-DDE, and mirex levels in Great Lakes fish and waterfowl consumers in two Ontario communities.

PCB, p,p'-DDE, and mirex levels were examined in blood plasma samples of 232 anglers from Cornwall and Mississauga, Ontario, in a pilot study to establish the feasibility and suitability of using a cohort of Ontario fish license holders for large-scale health studies. Great Lakes fish, waterfowl, and ocean fish consumption were examined as predictors of contaminant levels using regression analysis, with adjustment for age, gender, and community. Levels of Great Lakes fish and waterfowl consumption and contaminant levels were generally low in comparison with those observed in other Great Lakes studies. However, even within these low levels, Great Lakes fish consumption was associated with increased blood plasma PCB levels in men and mirex levels in both men and women. Waterfowl consumption was associated with higher plasma PCB (men and women), DDE (men only), and mirex levels (men and Cornwall women), and requires further exploration. We conclude that other study designs are required (to identify high consumers) for carrying out studies of health effects associated with high levels of Great Lakes fish and waterfowl consumption.

Adult↗
PubMed1996

Characterization of melatonin receptors in the brain of four avian species: duck, goose, pigeon, and turkey.

Melatonin receptor sites were characterized in the brains of four avian species (duck, goose, pigeon, and turkey) by an in vitro binding technique, using 2-[125I]iodomelatonin as a labeled ligand. The specific binding of 2-[125I]iodomelatonin to avian brain membranes was found to be stable, saturable, reversible, and of high affinity. Scatchard analysis revealed that 2-[125I]iodomelatonin binds to a single class of sites in brain membrane preparations of these species with high affinity (affinity constants Kd between 153 and 289 pM) and low capacity (total number of binding sites B(max) between 5.07 and 10.15 fmol/mg protein). Competition studies showed the following relative order of potency of indolic compounds to inhibit the specific 2-[125I]iodomelatonin binding: melatonin >> N-acetyltryptamine > N-acetyl-5-hydroxytryptamine > 5-hydroxytryptamine >>> 5-methoxytryptamine. We conclude that the 2-[125I]iodomelatonin-binding sites in brains of duck, goose, pigeon, and turkey have similar binding and pharmacological characteristics, and may represent ML-1 melatonin receptor sites.

Animals↗
PubMed1998

Characteristics of the proopiomelanocortin system in the outdoor-bred domestic gander. I. ACTH and beta-endorphin levels in the brain, pituitary, and plasma.

Immunoreactive (ir-) adrenocorticotropic hormone (ACTH) and beta-endorphin (beta E) levels were determined in seven brain regions, in the three pituitary lobes, and in the plasma of the domestic gander by specific radioimmunoassays. In the brain regions studied the relative concentrations of ir-ACTH and ir-beta E were the highest in the mediobasal hypothalamus and in the paraventricular nucleus. There were lower levels of these peptides in the supraoptic nucleus, in the septum, and in the dorsal thalamus. Very low ir-ACTH and -beta E contents were found in the archistriatum and in the lobus parolfactorius. In the pars distalis of the pituitary gland the cephalic lobe contained about 10 times more ir-ACTH (3596 pmol/lobe) and 4 times more ir-beta E (867 pmol/ lobe) than the caudal lobe (383 pmol/lobe and 189 pmol/lobe, respectively). Sephadex G-50 chromatography of pooled cephalic and caudal lobe extracts resulted in two distinct ir-beta E peaks, with elution volumes corresponding to the mammalian beta-lipotropin and beta E, and three ir-ACTH peaks, the second one coeluting with mammalian ACTH. In the neural lobe the ir-ACTH/-beta E concentrations were similar to those in the hypothalamus. Resting plasma ir-ACTH (12.8 +/- 1.47 pmol/ml) but not ir-beta E (31.4 +/- 1.22 pmol/ml) levels were significantly increased following castration (to 41.4 +/- 1.11 pmol/ml). Serial blood sampling indicated pulsatile ir-beta E secretion (mean, coefficients of variation, and minimum-maximum range: 17.5, 62.78, and 2.9-49.7, respectively, for gander 1 and 23.3, 62.85, and 5.00-61.5, respectively, for gander 2).

Adrenocorticotropic Hormone↗
PubMed2000

Seasonal relationships between plasma and fecal testosterone in response to GnRH in domestic ganders.

In two groups (eight individuals each) of socially acquainted, outdoor-kept, domestic ganders (male Hungarian white: Anser domesticus), basal and GnRH-stimulated plasma testosterone (T) concentrations were compared with fecal testosterone metabolites (TM) in and between three seasons, spring peak of reproductive activity, summer photorefractoriness, and fall sexual reactivation. Plasma was sampled 90 min following the challenge and T was analyzed by radioimmunoassay following the GnRH challenge. Fecal TM were measured by enzyme immunoassay using two group-specific antibodies against 17beta-OH-androgens or a novel antibody against 17-oxo groups, which was found to react with major testosterone metabolites without prior hydrolytic deconjugation. Baseline plasma T and systemic levels were high in spring and fall but low in summer. Plasma T increases in response to GnRH were followed by significantly elevated fecal TM levels 2 to 6 h following the challenge in spring and fall. In fall, at high plasma T levels, fecal TM levels were disproportionally lower than in spring. Variability of TM levels was two to five times higher in feces than in plasma, which explains why correlations between individual plasma T and fecal TM levels generally remained nonsignificant. This points to a low-level short-term relationship between the excreted TM and the plasma T levels. However, the reliability of the method was demonstrated by standard inter- and intraassay variabilities and by a high correspondence between results obtained by the two assays. It is suggested that, with appropriate sample size, fecal TM reflects plasma T increase. However, fecal TM was more variable than the plasma T, and fecal TM responses to GnRH did not always parallel the plasma T response. In addition, seasonal changes in androgen excretion regimes must be taken into account.

Animals↗
PubMed2001

A comprehensive characterization of a group IB intron and its encoded maturase reveals that protein-assisted splicing requires an almost intact intron RNA.

The group I intron (AnCOB) of the mitochondrial apocytochrome b gene from Aspergillus nidulans encodes a bi-functional maturase protein that is also a DNA endonuclease. Although the AnCOB intron self-splices, the encoded maturase protein greatly facilitates splicing, in part, by stabilizing RNA tertiary structure. To determine their role in self-splicing and in protein-assisted splicing, several peripheral RNA sub-domains in the 313 nucleotide intron were deleted (P2, P9, P9.1) or truncated (P5ab, P6a). The sequence in two helices (P2 and P9) was also inverted. Except for P9, the deleted regions are not highly conserved among group I introns and are often dispensable for catalytic activity. Nevertheless, despite the very tight binding of AnCOB RNA to the maturase and the high activity of the bimolecular complex (the rate of 5' splice-site cleavage was >20 min(-1) with guanosine as the cofactor), the intron was surprisingly sensitive to these modifications. Several mutations inactivated splicing completely and virtually all impaired splicing to varying degrees. Mutants containing comparatively small deletions in various regions of the intron significantly decreased binding affinity (generally >10(4)-fold), indicating that none of the domains that remained constitutes the primary recognition site of the maturase. The data argue that tight binding requires tertiary interactions that can be maintained by only a relatively intact intron RNA, and that the binding mechanism of the maturase differs from those of two other well-characterized group I intron splicing factors, CYT-18 and Cpb2. A model is proposed in which the protein promotes widespread cooperative folding of an RNA lacking extensive initial tertiary structure.

Apoproteins↗
PubMed2001

The crystal structure of bar-headed goose hemoglobin in deoxy form: the allosteric mechanism of a hemoglobin species with high oxygen affinity.

The crystal structure of a high oxygen affinity species of hemoglobin, bar-headed goose hemoglobin in deoxy form, has been determined to a resolution of 2.8 A. The R and R(free) factor of the model are 0.197 and 0.243, respectively. The structure reported here is a special deoxy state of hemoglobin and indicates the differences in allosteric mechanisms between the goose and human hemoglobins. The quaternary structure of the goose deoxy hemoglobin shows obvious differences from that of human deoxy hemoglobin. The rotation angle of one alphabeta dimer relative to its partner in a tetramer molecule from the goose oxy to deoxy hemoglobin is only 4.6 degrees, and the translation is only 0.3 A, which are much smaller than those in human hemoglobin. In the alpha(1)beta(2) switch region of the goose deoxy hemoglobin, the imidazole ring of His beta(2)97 does not span the side-chain of Thr alpha(1)41 relative to the oxy hemoglobin as in human hemoglobin. And the tertiary structure changes of heme pocket and FG corner are also smaller than that in human hemoglobin. A unique mutation among avian and mammalian Hbs of alpha119 from proline to alanine at the alpha(1)beta(1 )interface in bar-headed goose hemoglobin brings a gap between Ala alpha119 and Leu beta55, the minimum distance between the two residues is 4.66 A. At the entrance to the central cavity around the molecular dyad, some residues of two beta chains form a positively charged groove where the inositol pentaphosphate binds to the hemoglobin. The His beta146 is at the inositol pentaphosphate binding site and the salt-bridge between His beta146 and Asp beta94 does not exist in the deoxy hemoglobin, which brings the weak chloride-independent Bohr effect to bar-headed goose hemoglobin.

Adaptation, Physiological↗
PubMed1995

Murray valley encephalitis virus envelope protein antigenic variants with altered hemagglutination properties and reduced neuroinvasiveness in mice.

Neutralization escape variants of Murray Valley encephalitis virus were selected using a type-specific, neutralizing, and passively protective anti-envelope protein (E) monoclonal antibody (4B6C-2) which defines epitope E-1c. Nucleotide sequence analysis revealed single nucleotide changes in the E genes of 15 variants resulting in nonconservative amino acid substitutions in all cases. One variant had a three-nucleotide deletion in the E gene which resulted in loss of serine at residue 277. Changes were clustered into two separate regions of the E polypeptide (residues 126-128 and 274-277), indicating that E-1c is a discontinuous epitope. One variant (BHv1), altered at residue 277 (Ser-->Ile), failed to hemagglutinate across the pH range 5.5-7.5, in contrast to parental virus and the other escape variants which hemagglutinated at an optimal pH of 6.6. BHv1 was also of reduced neuroinvasiveness in 21-day-old mice following intraperitoneal inoculation compared to the other viruses. Parental virus and the neutralization escape variants grew equally well in both vertebrate and invertebrate cell cultures, indicating that the reduced neuroinvasiveness of BHv1 was not due to a major abnormality of replication.

Amino Acid Sequence↗
PubMed1995

Analysis of the complete nucleotide sequences of goose and muscovy duck parvoviruses indicates common ancestral origin with adeno-associated virus 2.

The complete nucleotide sequences of two parvoviruses isolated from goose and muscovy duck were determined. The two virus genomes share 81.9% nucleotide sequence identity, indicating that they are closely related. The coding regions are bracketed by inverted terminal repeats containing palindromes. This is similar to the genome organization of human parvoviruses, adeno-associated virus 2, and B19. Amino acid sequence comparison shows that the closest relative of the goose and muscovy duck parvoviruses is adeno-associated virus 2. This is surprising, because the goose and muscovy duck parvoviruses do not require any helper virus for productive replication, suggesting that adeno-associated virus 2 has been derived from a helper-independent ancestor.

Amino Acid Sequence↗
PubMed1996

Different hemagglutinin cleavage site variants of H7N7 in an influenza outbreak in chickens in Leipzig, Germany.

The hemagglutinin (HA) genes from four avian H7N7 influenza A isolates, from a single outbreak, were shown to possess different cleavage sites that contain varying numbers of basic amino acid residues (KKKKR, KRKKR, KKRKKR, KKKKKKR). All four variants are highly pathogenic in chickens and share an immediate common ancestral HA with A/tern/Potsdam/342-6/79 (H7N7) and A/swan/Potsdam/63-6/81 (H7N7). These viruses are nonpathogenic and contain no extra basic amino acids at the cleavage site of their HA. During evolution a common precursor virus acquired different sequences at the cleavage site of the HA and became highly pathogenic in chickens. In vitro assays revealed that the HA from A/chicken/Leipzig/79 with KKKKR at the cleavage site was only partially cleaved (41%), compared to 93-100% cleavage of the other HAs. Since all four viruses were highly pathogenic in chickens, these findings confirm that the degree of pathogenicity in vivo is not exclusively determined by the degree of HA cleavability.

Amino Acid Sequence↗
PubMed1999

Genetic characterization of the pathogenic influenza A/Goose/Guangdong/1/96 (H5N1) virus: similarity of its hemagglutinin gene to those of H5N1 viruses from the 1997 outbreaks in Hong Kong.

Analysis of the sequences of all eight RNA segments of the influenza A/G oose/Guangdong/1/96 (H5N1) virus, isolated from a sick goose during an outbreak in Guangdong province, China, in 1996, revealed that the hemagglutinin (HA) gene of the virus was genetically similar to those of the H5N1 viruses isolated in Hong Kong in 1997. However, the remaining genes showed greater similarity to other avian influenza viruses. Notably, the neuraminidase gene did no have the 19-amino-acid deletion in the stalk region seen in the H5N1 Hong Kong viruses and the NS gene belonged to allele B, while that of the H5N1 Hong Kong viruses belonged to allele A. These data suggest that the H5N1 viruses isolated from the Hong Kong outbreaks derived their HA genes from a virus similar to the A/Goose/Guangdong/1/96 virus or shared a progenitor with this goose pathogen.

Animals↗
PubMed2001

Genome sequence determinations and analyses of novel circoviruses from goose and pigeon.

The genomes of novel circoviruses from goose and pigeon, which were isolated using degenerate primer and inverse primer PCR methods, were cloned and sequenced. Comparative nucleotide (nt) sequence analyses showed that the goose circovirus (GCV) and pigeon circovirus (PiCV) possessed genomes which were 1821 and 2037 or 2036 nt, respectively, and which had features in common with the genomes of porcine circoviruses types 1 and 2 (PCV1, PCV2) and psittacine beak and feather disease virus (BFDV), such that they can now be assigned to the genus Circovirus of the family Circoviridae. Common features include the possession of (i) a potential stem-loop/nonanucleotide motif with which the initiation of rolling circle replication of the virus DNA is associated; (ii) two major ORFs, located on the virus (V1 ORF) and complementary (C1 ORF) strands, which encode the replication-associated protein (Rep) and capsid protein, respectively; (iii) high levels of amino acid identity (41.2--58.2%) shared with other circovirus Rep proteins; and (iv) direct/inverted repeat sequences within the putative intergenic region. On the basis of nt and amino acid sequence identities, GCV is substantially less closely related to BFDV than PiCV is to BFDV.

Amino Acid Sequence↗
PubMed2002

Generation of velogenic Newcastle disease viruses from a nonpathogenic waterfowl isolate by passaging in chickens.

A benign Newcastle disease virus (NDV) recently became highly virulent during replication in domestic chickens. It is still unclear whether NDVs circulating among wild waterfowl also have the potential to become highly pathogenic (velogenic) in chickens. To demonstrate experimentally the generation of velogenic NDV from a nonpathogenic waterfowl isolate, we passaged an avirulent goose isolate in chickens. After nine consecutive passages by air-sac inoculation, followed by five passages in chick brain, the virus became highly virulent in chickens, producing a 100% mortality rate, and demonstrating typical velogenic properties in pathogenicity tests. Sequence analysis at the fusion protein cleavage site showed that the original isolate contained the typical avirulent type sequence, E-R-Q-E-R/L, which progressed incrementally to a typical virulent type, K-R-Q-K-R/F, during repeated passage in chickens. These results demonstrate that avirulent viruses, maintained in wild waterfowl in nature and bearing the consensus avirulent type sequence, have the potential to become velogenic after transmission to and circulation in chicken populations. The results also suggest that chickens provide a mechanism for the selection of virulent viruses from an avirulent background.

Animals↗