Analyze Diet

Topic:Molecular biology

Molecular biology in horses involves the study of molecular processes and genetic mechanisms that underpin equine physiology and health. This field encompasses the analysis of DNA, RNA, proteins, and other biomolecules to understand gene expression, genetic variation, and cellular functions in horses. Techniques such as genomic sequencing, gene expression profiling, and molecular diagnostics are employed to explore topics like hereditary diseases, performance traits, and immune responses in equines. This page assembles peer-reviewed research studies and scholarly articles that investigate the molecular biology of horses, focusing on genetic research, molecular techniques, and their applications in equine science.
Identification of putative homology between horse microsatellite flanking sequences and cross-species ESTs, mRNAs and genomic sequences.
Animal genetics    January 21, 2004   Volume 35, Issue 1 28-33 doi: 10.1111/j.1365-2052.2003.01077.x
Farber CR, Medrano JF.In this study the flanking sequences of 1534 horse microsatellites were used in a BLAST search to identify putative human-horse homologies. BLAST searches revealed 129 flanking sequences with significant blastn matches [alignment scores (S) > or = 60 and sum probability values (E) < or = 3.0E-6], also, 25 of these produced significant blastx matches. To provide a reference point in the human genome the flanking sequences with matches were subjected to a BLAT search of the University of California Santa Cruz (UCSC) human genome assembly (July 2003 freeze). Eighty-three of the flanking seq...
Expression of bone morphogenetic protein-6 and -2 and a bone morphogenetic protein antagonist in horses with naturally acquired osteochondrosis.
American journal of veterinary research    January 15, 2004   Volume 65, Issue 1 110-115 doi: 10.2460/ajvr.2004.65.110
Semevolos SA, Nixon AJ, Strassheim ML.To determine the mRNA expression of bone morphogenetic protein (BMP)-6 and -2 and a BMP antagonist (Noggin) in horses with osteochondrosis. Methods: Samples of articular cartilage from affected stifle or shoulder joints of 10 immature horses with naturally acquired osteochondrosis and corresponding joints of 9 clinically normal horses of similar age; additionally, samples of distal femoral growth plate cartilage and distal femoral articular cartilage were obtained from a normal equine fetus. Methods: Cartilage specimens were snap-frozen in liquid nitrogen, and total RNA was isolated. Adjacent ...
Nucleotide sequence of equine erythropoietin and characterization of region-specific antibodies.
American journal of veterinary research    January 15, 2004   Volume 65, Issue 1 15-19 doi: 10.2460/ajvr.2004.65.15
Sato F, Yamashita S, Kugo T, Hasegawa T, Mitsui I, Kijima-Suda I.To determine the full-length complementary DNA (cDNA) sequence of equine erythropoietin (EPO) and to develop region-specific antibodies to differentiate equine EPO (eEPO) and human EPO (hEPO). Methods: RNA and lysate extracted from renal tissues of an adult Thoroughbred. Methods: Full-length cDNA was determined by use of a reverse transcriptase-polymerase chain reaction assay and a rapid amplification of cDNA ends method. The deduced amino acid sequence was compared with sequences of EPO reported for other species. Furthermore, 4 synthetic peptides were designed in 2 distinctive parts of the e...
Human chorionic gonadotropin-dependent regulation of 17beta-hydroxysteroid dehydrogenase type 4 in preovulatory follicles and its potential role in follicular luteinization.
Endocrinology    January 15, 2004   Volume 145, Issue 4 1906-1915 doi: 10.1210/en.2003-1715
Brown KA, Boerboom D, Bouchard N, Doré M, Lussier JG, Sirois J.17Beta-hydroxysteroid dehydrogenase type 4 (17betaHSD4) has a unique multidomain structure, with one domain involved in 17beta-estradiol inactivation. The objective of the study was to investigate the regulation of 17betaHSD4 during human chorionic gonadotropin (hCG)-induced ovulation/luteinization. The equine 17betaHSD4 cDNA was cloned and was shown to encode a 735-amino acid protein that is highly conserved (81-87% identity) compared with other mammalian orthologs. RT-PCR/Southern blot analyses were performed to study the regulation of 17betaHSD4 transcripts in equine preovulatory follicles ...
Molecular cloning of a Babesia caballi gene encoding the 134-kilodalton protein and evaluation of its diagnostic potential in an enzyme-linked immunosorbent assay.
Clinical and diagnostic laboratory immunology    January 13, 2004   Volume 11, Issue 1 211-215 doi: 10.1128/cdli.11.1.211-215.2004
Tamaki Y, Hirata H, Takabatake N, Bork S, Yokoyama N, Xuan X, Fujisaki K, Igarashi I.A Babesia caballi gene encoding the 134-kDa (BC134) protein was immunoscreened with B. caballi-infected horse serum. An enzyme-linked immunosorbent assay (ELISA) using recombinant BC134 protein could effectively differentiate B. caballi-infected horse sera from Babesia equi-infected or noninfected control horse sera. These results suggest that the recombinant BC134 protein is a potential diagnostic antigen in the detection of B. caballi infection.
A 1.4-Mb interval RH map of horse chromosome 17 provides detailed comparison with human and mouse homologues.
Genomics    January 7, 2004   Volume 83, Issue 2 203-215 doi: 10.1016/j.ygeno.2003.07.002
Lee EJ, Raudsepp T, Kata SR, Adelson D, Womack JE, Skow LC, Chowdhary BP.Comparative genomics has served as a backbone for the rapid development of gene maps in domesticated animals. The integration of this approach with radiation hybrid (RH) analysis provides one of the most direct ways to obtain physically ordered comparative maps across evolutionarily diverged species. We herein report the development of a detailed RH and comparative map for horse chromosome 17 (ECA17). With markers distributed at an average interval of every 1.4 Mb, the map is currently the most informative among the equine chromosomes. It comprises 75 markers (56 genes and 19 microsatellites),...
IL-4, IL-5 and IFN-gamma mRNA expression in pulmonary lymphocytes in equine heaves.
Veterinary immunology and immunopathology    January 1, 2004   Volume 97, Issue 1-2 87-96 doi: 10.1016/j.vetimm.2003.08.013
Cordeau ME, Joubert P, Dewachi O, Hamid Q, Lavoie JP.Heaves is a common condition of horses of cold climate that is characterized by small airway inflammation and obstruction following exposure of susceptible horses to moldy hay and straw. It has been shown that helper T lymphocytes (Th) orchestrate the inflammatory response in asthma and in various animal models of allergic lung diseases by the release of Th2-type cytokines. Results of previous studies indicate that a predominant expression of Th2-type response by airway cells may also be present in heaves. To evaluate the temporal mRNA expression of Th1 (IFN-gamma) and Th2 (IL-4, IL-5) type cy...
Late domain-dependent inhibition of equine infectious anemia virus budding.
Journal of virology    December 25, 2003   Volume 78, Issue 2 724-732 doi: 10.1128/jvi.78.2.724-732.2004
Shehu-Xhilaga M, Ablan S, Demirov DG, Chen C, Montelaro RC, Freed EO.The Gag proteins of a number of different retroviruses contain late or L domains that promote the release of virions from the plasma membrane. Three types of L domains have been identified to date: Pro-Thr-Ala-Pro (PTAP), Pro-Pro-X-Tyr, and Tyr-Pro-Asp-Leu. It has previously been demonstrated that overexpression of the N-terminal, E2-like domain of the endosomal sorting factor TSG101 (TSG-5') inhibits human immunodeficiency virus type 1 (HIV-1) release but does not affect the release of the PPPY-containing retrovirus murine leukemia virus (MLV), whereas overexpression of the C-terminal portion...
Novel classical MHC class I alleles identified in horses by sequencing clones of reverse transcription-PCR products.
European journal of immunogenetics : official journal of the British Society for Histocompatibility and Immunogenetics    December 17, 2003   Volume 30, Issue 6 387-396 doi: 10.1111/j.1365-2370.2003.00420.x
Chung C, Leib SR, Fraser DG, Ellis SA, McGuire TC.Improved typing of horse classical MHC class I is required to more accurately define these molecules and to extend the number identified further than current serological assays. Defining classical MHC class I alleleic polymorphism is important in evaluating cytotoxic T lymphocyte (CTL) responses in horses. In this study, horse classical MHC class I genes were analyzed based on reverse transcription (RT)-PCR amplification of sequences encoding the polymorphic peptide binding region and the more conserved alpha 3, transmembrane and cytoplasmic regions followed by cloning and sequencing. Primer s...
Parathyroid hormone (PTH) secretion, PTH mRNA and calcium-sensing receptor mRNA expression in equine parathyroid cells, and effects of interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha on equine parathyroid cell function.
Journal of molecular endocrinology    December 11, 2003   Volume 31, Issue 3 609-620 doi: 10.1677/jme.0.0310609
Toribio RE, Kohn CW, Capen CC, Rosol TJ.Parathyroid hormone (PTH) is secreted by the chief cells of the parathyroid gland in response to changes in ionized calcium (Ca(2+)) concentrations. In this study, we measured PTH secretion, and PTH mRNA and calcium-sensing receptor (CaR) mRNA expression by equine parathyroid chief cells in vitro. We also evaluated the effects of interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha on PTH secretion, and PTH and CaR mRNA expression. The relationship between PTH and Ca(2+) was inversely related. PTH secretion decreased from 100% (day 0) to 13% (day 30). PTH mRNA expression decline...
Intra- and intermolecular disulfide bonds of the GP2b glycoprotein of equine arteritis virus: relevance for virus assembly and infectivity.
Journal of virology    December 4, 2003   Volume 77, Issue 24 12996-13004 doi: 10.1128/jvi.77.24.12996-13004.2003
Wieringa R, De Vries AA, Post SM, Rottier PJ.Equine arteritis virus (EAV) is an enveloped, positive-strand RNA virus belonging to the family Arteriviridae of the order NIDOVIRALES: EAV virions contain six different envelope proteins. The glycoprotein GP(5) (previously named G(L)) and the unglycosylated membrane protein M are the major envelope proteins, while the glycoproteins GP(2b) (previously named G(S)), GP(3), and GP(4) are minor structural proteins. The unglycosylated small hydrophobic envelope protein E is present in virus particles in intermediate molar amounts compared to the other transmembrane proteins. The GP(5) and M protein...
The amino acid sequence of protein AA from a burro (Equus asinus). Sletten K, Johnson KH, Westermark P.The primary structure of amyloid fibril protein AA of a burro has been determined by Edman degradation. The 80 amino acid residue long protein shows strong resemblance to that of other mammalian AA-proteins and differs from equine protein AA at 5 positions: Burro/horse positions 20 (Q/N), 44 (R,Q, K/K,Q), 59 (G,L/G,A), 61 (Q/E) and 65 (N/R).
Recent advances in molecular epidemiology and detection of Taylorella equigenitalis associated with contagious equine metritis (CEM).
Veterinary microbiology    November 26, 2003   Volume 97, Issue 1-2 111-122 doi: 10.1016/j.vetmic.2003.08.001
Matsuda M, Moore JE.In the present review article, recent molecular advances relating to studies with Taylorella equigenitalis, as well as the recently described second species of the genus Taylorella, namely Taylorella asinigenitalis, have been described. Molecular genotyping of T. equigenitalis strains by pulsed-field gel electrophoresis (PFGE) after digestion with the suitable restriction enzyme(s) enabled the effective discrimination of strains, thus allowing the examination of the scientific mechanism(s) for its occurrence and transmission of contagious equine metritis (CEM). Alternatively, polymerase chain ...
Molecular modeling of manganese regulation of calmodulin-sensitive adenylyl cyclase from mammalian sperm.
Biochemical and biophysical research communications    November 25, 2003   Volume 312, Issue 1 91-96 doi: 10.1016/j.bbrc.2003.09.215
Toscano WA, Toscano JS, Toscano DG, Gross MK.The soluble calmodulin-sensitive isoform of adenylyl cyclase isolated from equine sperm is unique because it requires Mn(2+) rather than Mg(2+) for activity. To gain insight into the molecular action of metals on sperm adenylyl cyclase, the kinetics of Mn(2+) and ATP effect was examined. A biphasic response to increases in ATP concentration was observed when metal was held constant. When [Mn(2+)] exceeded [ATP], however, greatly enhanced enzyme activity was observed. The kinetic profiles were consistent with allosteric activation of adenylyl cyclase by Mn(2+). Linear transformation of the data...
Post-entry restriction of retroviral infections.
AIDS reviews    November 6, 2003   Volume 5, Issue 3 156-164 
Towers GJ, Goff SP.Pathogenic retroviruses have driven the evolution of several dominant-acting mechanisms able to block infection and protect the host. These are exemplified by the mouse gene Fv1, which encodes a Gag-like protein able to protect against murine leukemia virus (MLV) infection. The block is saturable, occurs after reverse transcription and is directed against the viral capsid gene. Several other mammalian species are also able to block MLV infection with the same capsid specificity. A human gene with this activity has been named Ref1. Recently, primates have been shown to restrict a variety of ret...
Novel purification method for mammalian seminal plasma phospholipid-binding proteins reveals the presence of a novel member of this family of protein in stallion seminal fluid.
Molecular reproduction and development    October 28, 2003   Volume 66, Issue 4 349-357 doi: 10.1002/mrd.10369
Ménard M, Nauc V, Lazure C, Vaillancourt D, Manjunath P.A family of bull seminal plasma (BSP) phospholipid-binding proteins (BSP proteins), potentiate heparin- and HDL-induced capacitation. The homologous proteins have been purified from stallion and boar seminal plasma, and detected in low concentrations in other mammalian seminal plasma. In this study, we developed a new isolation method for mammalian seminal plasma choline phospholipid-binding proteins wherein they are present in low concentrations. The method is based on the interaction of this family of proteins with egg yolk low-density lipoprotein fraction (LDF). In order to demonstrate the ...
Characterization of the horse (Equus caballus) IGHA gene.
Immunogenetics    October 15, 2003   Volume 55, Issue 8 552-560 doi: 10.1007/s00251-003-0617-2
Wagner B, Greiser-Wilke I, Antczak DF.Nucleotide sequences of the immunoglobulin constant heavy chain genes of the horse have been described for IGHM, IGHG and IGHE genes, but not for IGHA. Here, we provide the nucleotide sequence of the genomic IGHA gene of the horse ( Equus caballus), including its secretion region and the transmembrane exon. The equine IGHA gene shows the typical structure of a mammalian IGHA gene, with only three exons, separated by two introns of similar size. The hinge exon is located at the 5' end of the CH2 exon and encodes a hinge region of 11 amino acids, which contains five proline residues. The coding ...
Expression of key prostaglandin synthases in equine endometrium during late diestrus and early pregnancy.
Biology of reproduction    October 15, 2003   Volume 70, Issue 2 391-399 doi: 10.1095/biolreprod.103.020800
Boerboom D, Brown KA, Vaillancourt D, Poitras P, Goff AK, Watanabe K, Doré M, Sirois J.Luteolysis in domestic species is mediated by the release of luteolytic pulses of prostaglandin (PG) F(2alpha) by the uterus at the end of diestrus, which must be suppressed by the conceptus to permit maternal recognition of pregnancy. In many species, including the horse, both the conceptus and the endometrium also synthesize PGE(2), which may antagonize PGF(2alpha) by playing a luteotropic and/or antiluteolytic role. While the release of PGE(2) and PGF(2alpha) by the equine endometrium in late diestrus and early pregnancy has been previously studied, the underlying prostaglandin synthase gen...
Inhibition of in vitro maturation of equine oocytes by interleukin 1 beta via specific IL-1 receptors.
Reproduction (Cambridge, England)    October 4, 2003   Volume 126, Issue 4 509-515 doi: 10.1530/rep.0.1260509
Martoriati A, Caillaud M, Goudet G, Gérard N.Interleukin 1 beta (IL-1 beta) inhibits the LH-induced resumption of meiosis of equine oocytes in vitro. The present study was performed to clarify this inhibitory effect of IL-1 beta by testing increasing concentrations of IL-1 beta, and by measuring the effect of addition of IL-1 receptor antagonist (IL-1RA) to the culture medium. The effect of IL-1 beta on epidermal growth factor (EGF)-induced resumption of meiosis was also studied. Cumulus-oocyte complexes (COCs) were collected from subordinate follicles on ovaries obtained from an abattoir. In five distinct experiments, COCs were cultured...
beta-Adrenergic stimulated lipolysis in pony adipocytes is exclusively via a beta2-subtype and is not affected by lactation.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology    September 27, 2003   Volume 136, Issue 2 311-320 doi: 10.1016/s1095-6433(03)00157-0
Carrington EF, Desautels M, Naylor JM.Catecholamines are important lipolytic agents in horses and ponies but the nature of the adrenergic receptor subtype distribution in their adipocytes is uncertain. A first objective was to identify the beta-adrenergic receptor subtype(s) present in adipocytes from horses and ponies. A second objective was to evaluate if the lipolytic responsiveness of isolated adipocytes to beta-adrenergic agonists is altered during lactation, a condition known to affect markedly maternal fat metabolism. Isoproterenol and salbutamol elicited strong lipolytic responses in adipocytes isolated from horse and pony...
Novel plasmid-borne gene qacJ mediates resistance to quaternary ammonium compounds in equine Staphylococcus aureus, Staphylococcus simulans, and Staphylococcus intermedius.
Antimicrobial agents and chemotherapy    September 25, 2003   Volume 47, Issue 10 3046-3052 doi: 10.1128/AAC.47.10.3046-3052.2003
Bjorland J, Steinum T, Sunde M, Waage S, Heir E.We identified a novel plasmid-borne gene (designated qacJ) encoding resistance to quaternary ammonium compounds (QACs) in three staphylococcal species associated with chronic infections in four horses. qacJ was located on a 2,650-bp plasmid (designated pNVH01), a new member of the pC194 family of rolling-circle replication plasmids. The 107-amino-acid protein, QacJ, showed similarities to known proteins of the small multidrug resistance family: Smr/QacC (72.5%), QacG (82.6%), and QacH (73.4%). The benzalkonium chloride MIC for a qacJ-containing recombinant was higher than those for otherwise i...
Cyclooctadepsipeptides–an anthelmintically active class of compounds exhibiting a novel mode of action.
International journal of antimicrobial agents    September 19, 2003   Volume 22, Issue 3 318-331 doi: 10.1016/s0924-8579(03)00219-x
Harder A, Schmitt-Wrede HP, Krücken J, Marinovski P, Wunderlich F, Willson J, Amliwala K, Holden-Dye L, Walker R.There are three major classes of anthelmintics for veterinary use: the benzimidazoles/prebenzimidazoles, the tetrahydropyrimidines/imidazothiazoles, and the macrocyclic lactones. In nematodes, there are five targets for the existing anthelmintics: the nicotinergic acetylcholine receptor which is the target of tetrahydropyrimidines/imidazothiazoles and indirectly that of the acetylcholineesterase inhibitors; the GABA receptor which is the target of piperazine, the glutamate-gated chloride channel as the target of the macrocyclic lactones, and beta-tubulin as the target of prebenzimidazoles/benz...
Molecular phylogenetics and diagnosis of soil and clinical isolates of Halicephalobus gingivalis (Nematoda: Cephalobina: Panagrolaimoidea), an opportunistic pathogen of horses.
International journal for parasitology    September 18, 2003   Volume 33, Issue 10 1115-1125 doi: 10.1016/s0020-7519(03)00134-6
Nadler SA, Carreno RA, Adams BJ, Kinde H, Baldwin JG, Mundo-Ocampo M.Phylogenetic relationships among six isolates of Halicephalobus gingivalis (Stefanski, 1954), a species with pathogenic potential in horses and humans, were evaluated using DNA sequences from the nuclear large-subunit ribosomal RNA (LSU rDNA) gene. Sequences from nematodes obtained from in vitro cultures (soil or clinical sources), or isolated from infected horse tissues, were compared. Gene sequences from a fatal equine clinical case from southern California and a free-living isolate recovered from southern California soil showed no fixed differences. Sequences from isolates representing two ...
Cloning, expression and biological activity of equine interleukin (IL)-5.
Veterinary immunology and immunopathology    September 13, 2003   Volume 95, Issue 1-2 63-72 doi: 10.1016/s0165-2427(03)00100-4
Cunningham FM, Vandergrifft E, Bailey SR, Sepulveda MF, Goode NT, Horohov DW.The cytokine, interleukin (IL)-5 stimulates eosinophil differentiation, activation and survival and can prime these cells, increasing the response to other mediators. In view of its many effects on eosinophils, IL-5 has been implicated in the pathogenesis of allergic disease in man. Here we report the cloning of equine IL-5 and expression of the recombinant protein by transfection of Chinese hamster ovary (CHO) cells. The cloned cDNA sequence consisted of 405 nucleotides and encoded a protein of 135 amino acids. There is >85% identity with feline, bovine, ovine, canine, and human IL-5 sequence...
Characterization of RNA elements that regulate gag-pol ribosomal frameshifting in equine infectious anemia virus.
Journal of virology    September 13, 2003   Volume 77, Issue 19 10280-10287 doi: 10.1128/jvi.77.19.10280-10287.2003
Chen C, Montelaro RC.Synthesis of Gag-Pol polyproteins of retroviruses requires ribosomes to shift translational reading frame once or twice in a -1 direction to read through the stop codon in the gag reading frame. It is generally believed that a slippery sequence and a downstream RNA structure are required for the programmed -1 ribosomal frameshifting. However, the mechanism regulating the Gag-Pol frameshifting remains poorly understood. In this report, we have defined specific mRNA elements required for sufficient ribosomal frameshifting in equine anemia infectious virus (EIAV) by using full-length provirus rep...
[Fluorescence spectroscopic study of interaction between Fe-protoporphyrin in myoglobin and Cu(II) ions].
Guang pu xue yu guang pu fen xi = Guang pu    September 5, 2003   Volume 23, Issue 3 532-534 
Feng YY, Yang H, Gu XT, Jiang HJ, Lu TH.In this paper, the interaction between Cu(II) ions and Fe-protoporphyrin in horse-heart myoglobin (FePP-Mb) was studied. As a result, some of the Fe(II) ions in FePP-Mb were found to be replaced by Cu(II) ions forming CuPP-Mb, by adding Cu(II) ions into the myoglobin solution. The interaction became stronger when adding more Cu(II) ions into the myoglobin solution. By studying the metal ions' interaction with myoglobin proteins as macromolecules and discussing the interaction mechanism, this work provides a theoretical basis for the further study of hazardous metal ions' interaction with the h...
Enhancement of equine infectious anemia virus virulence by identification and removal of suboptimal nucleotides.
Virology    September 5, 2003   Volume 313, Issue 2 588-603 doi: 10.1016/s0042-6822(03)00351-9
Cook RF, Cook SJ, Berger SL, Leroux C, Ghabrial NN, Gantz M, Bolin PS, Mousel MR, Montelaro RC, Issel CJ.Pathogenicity was reportedly restored to an avirulent molecular clone of equine infectious anemia virus (EIAV) by substitution of 3' sequences from the pathogenic variant strain (EIAV(PV)). However, the incidence of disease in horses/ponies was found to be significantly lower (P = 0.016) with the chimeric clone (EIAV(UK)) than with EIAV(PV). This was attributable to 3' rather than 5' regions of the proviral genome, where EIAV(UK) differs from the consensus EIAV(PV) sequence by having a 68-bp duplication in the 3' LTR and arginine (R(103)) rather than tryptophan (W(103)) at position 103 in the ...
Sequence variants of bovine papillomavirus E5 detected in equine sarcoids.
Virus research    September 3, 2003   Volume 96, Issue 1-2 141-145 doi: 10.1016/s0168-1702(03)00175-8
Chambers G, Ellsmore VA, O'Brien PM, Reid SW, Love S, Campo MS, Nasir L.The equine sarcoid, one of the most common dermatological lesions in equids, is a benign, locally invasive dermal fibroblastic lesion. Previous studies have suggested an association with two bovine papilloma virus (BPV) types, BPV-1 and BPV-2. In the present study, we examined sarcoids from horses from two geographical areas, Switzerland and the UK, for the major transforming gene of BPV, E5. We detected BPV DNA for the E5 open reading frame and viral E5 RNA transcripts in most sarcoids. Sequence analysis of the E5 open reading frame of sarcoid-associated BPV detected several unique DNA sequen...
Horse hooves and bird feathers: Two model systems for studying the structure and development of highly adapted integumentary accessory organs–the role of the dermo-epidermal interface for the micro-architecture of complex epidermal structures.
Journal of experimental zoology. Part B, Molecular and developmental evolution    September 2, 2003   Volume 298, Issue 1 140-151 doi: 10.1002/jez.b.31
Bragulla H, Hirschberg RM.Accessory organs of the integument are locally modified parts of the potentially feather-bearing skin in birds (e.g., the rhamphotheca, claws, or scales), and of the potentially hairy skin in mammals (e.g., the rhinarium, nails, claws, or hooves). These special parts of the integument are characterised by a modified structure of their epidermal, dermal and subcutaneous layers. The developmental processes of these various integumentary structures in birds and mammals show both similarities and differences. For example, the development of the specialised epidermal structures of both feathers and...
A pH-dependent aquomet-to-hemichrome transition in crystalline horse methemoglobin.
Biochemistry    August 27, 2003   Volume 42, Issue 34 10113-10125 doi: 10.1021/bi030059t
Robinson VL, Smith BB, Arnone A.In 1947, Perutz and co-workers reported that crystalline horse methemoglobin undergoes a large lattice transition as the pH is decreased from 7.1 to 5.4. We have determined the pH 7.1 and 5.4 crystal structures of horse methemoglobin at 1.6 and 2.1 A resolution, respectively, and find that this lattice transition involves a 23 A translation of adjacent hemoglobin tetramers as well as changes in alpha heme ligation and the tertiary structure of the alpha subunits. Specifically, when the pH is lowered from 7.1 to 5.4, the Fe(3+) alpha heme groups (but not the beta heme groups) are converted from...