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At least 811 records · Page 45Linked to original sources
PubMed2002

Substrate specificity of the Plasmodium falciparum glycosylphosphatidylinositol biosynthetic pathway and inhibition by species-specific suicide substrates.

The substrate specificities of the early glycosylphosphatidylinositol biosynthetic enzymes of Plasmodium were determined using substrate analogues of D-GlcN(alpha)1-6-D-myo-inositol-1-HPO(4)-sn-1,2-dipalmitoylglycerol (GlcN-PI). Similarities between the Plasmodium and mammalian (HeLa) enzymes were observed. These are as follows: (i) The presence and orientation of the 2'-acetamido/amino and 3'-OH groups are essential for substrate recognition for the de-N-acetylase, inositol acyltransferase, and first mannosyltransferase enzymes. (ii) The 6'-OH group of the GlcN is dispensable for the de-N-acetylase, inositol acyltransferase, all four of the mannosyltransferases, and the ethanolamine phosphate transferase. (iii) The 4'-OH group of GlcNAc is not required for recognition, but substitution interferes with binding to the de-N-acetylase. The 4'-OH group of GlcN is essential for the inositol acyltransferase and first mannosyltransferase. (iv) The carbonyl group of the natural 2-O-hexadecanyl ester of GlcN-(acyl)PI is essential for substrate recognition by the first mannosyltransferase. However, several differences were also discovered: (i) Plasmodium-specific inhibition of the inositol acyltransferase was detected with GlcN-[L]-PI, while GlcN-(2-O-alkyl)PI weakly inhibited the first mannosyltransferase in a competitive manner. (ii) The Plasmodium de-N-acetylase can act on analogues containing N-benzoyl, GalNAc, or betaGlcNAc whereas the human enzyme cannot. Using the parasite specificity of the later two analogues with the known nonspecific de-N-acetylase suicide inhibitor [Smith, T. K., et al. (2001) EMBO J. 20, 3322-3332], GalNCONH(2)-PI and GlcNCONH(2)-beta-PI were designed and found to be potent (IC(50) approximately 0.2 microM), Plasmodium-specific suicide substrate inhibitors. These inhibitors could be potential lead compounds for the development of antimalaria drugs.

Acyltransferases↗
PubMed1979

Immunosuppression by surface-active material: lack of species specificity.

Surface-active material isolated from the lungs of both dogs and rats was tested for its ability to suppress the in vitro proliferative responses of dog, mouse, or human lymphocytes to a variety of immunologic stimuli. Both dog and rat surface-active material exerted a dose-dependent suppressive effect on the proliferative responses of each species of lymphocyte, regardless of the nature of the immune stimulus (mitogen, antigen, or alloantigen). The data indicated that surface-active material acts by directly inhibiting the responding lymphocyte and not by activating suppessor cells. The immunosuppression could not be attributed to lymphocyte cytotoxicity. Although the mechanism of this immunosuppressive action of surface-active material remains undefined, the present data clearly indicate that such activity is not species specific.

Animals↗
PubMed1987

The species-specific nature of the ototoxicity of dihydrostreptomycin in the patas monkey.

The remarkable susceptibility of the inner ear of the patas monkey (Erythrocebus patas) to the ototoxic action of dihydrostreptomycin (DHSM) (and streptomycin (SM)) is well established in this paper and affords a rare example of a species-specific reaction to a restricted class of compounds within the aminoglycoside group of antibiotics. In a series of experiments, behavioral and morphological observations together provided the following profile of DHSM ototoxicity in the patas monkey: Sudden onset of hearing loss beginning after 7-9 weeks of treatment; Substantial, though often partial, hearing impairment beginning at the high frequencies and progressing with or without continued treatment to the low frequencies; In the inner ear, a corresponding and selective loss of nerve fibers and of outer hair cells, relative to inner hair cells, beginning in the base of the cochlea and proceeding toward the apex; Continued and progressive loss of hearing for several months after cessation of drug treatment; and Non-auditory effects in some animals on the kidney and vestibular system. Results from control experiments confirmed this special relationship between the patas monkey and DHSM: Other nonhuman primates (macaques and vervet monkeys) were essentially unaffected by DHSM; The patas showed no equivalent sensitivity to other aminoglycosides such as kanamycin or to other forms of ototraumatic insult such as intense noise.

Animals↗
PubMedDate not supplied

Reactivity of monoclonal antibodies to species-specific antigens of Entamoeba histolytica.

Twenty monoclonal antibodies were produced against trophozoites of Entamoeba histolytica strains HK-9 and HM-1: IMSS. When reactivity to various enteric protozoa was examined by an indirect fluorescence antibody test, 15 of the monoclonal antibodies were strongly reactive with E. histolytica trophozoites. Species-specific antigens recognized by these monoclonal antibodies were located on the plasma membrane, nucleus, cytoplasm, and cytoskeletal structures of the trophozoites. Two of the remaining five monoclonals reacted strongly with trophozoites of the E. histolytica-like Laredo strain. The determinant antigen was located in the cytoplasm. The three remaining monoclonal antibodies were found to recognize cross-reactive antigens between E. histolytica and E. histolytica-like Laredo, E. hartmanni, E. coli, Dientamoeba fragilis, Giardia lamblia, and Trichomonas hominis. These three antibodies were also reactive with T. vaginalis and mammalian cells such as HeLa cells. Thus, the combined use of monoclonal antibodies seems capable of distinguishing E. histolytica and/or E. histolytica-like Laredo from other enteric protozoa.

Animals↗
PubMed2000

Species specificity of barnacle settlement-inducing proteins.

We previously isolated a larval settlement-inducing protein complex (SIPC) from adult extracts of the barnacle, Balanus amphitrite using a nitrocellulose membrane settlement assay. In the present study, we found that the extracts of other adult barnacles, Megabalanus rosa and Balanus eburneus, also induced the settlement of B. amphitrite cyprids although the inductive activity was slightly lower than that of conspecific extracts. Furthermore, we examined reactivity to anti-SIPC antibody in adult extracts from six species of Japanese barnacles other than B. amphitrite, brine shrimp and eight marine sessile organisms besides barnacles. The results showed that all barnacles examined contained SIPC-like proteins with slightly different molecular weight, while the other animals did not react to the antibody by immunoblot analysis. These findings suggest that species specificity in settlement-inducing proteins of barnacles is not so strict, but these proteins are characteristic to barnacle species.

Animals↗
PubMed2002

Species-specific receptor recognition by a minor-group human rhinovirus (HRV): HRV serotype 1A distinguishes between the murine and the human low-density lipoprotein receptor.

Human rhinoviruses (HRV) of the minor receptor group use several members of the low-density lipoprotein receptor superfamily for cell entry. These proteins are evolutionarily highly conserved throughout species and are almost ubiquitously expressed. Their common building blocks, cysteine-rich ligand binding repeats about 40 amino acids in length, exhibit considerable sequence similarity. Various numbers of these repeats are present in the different receptors. We here demonstrate that HRV type 1A (HRV1A) replicates in mouse cells without adaptation. Furthermore, although closely related to HRV2, it fails to bind to the human low-density lipoprotein receptor but recognizes the murine protein, whereas HRV2 binds equally well to both homologues. This difference went unnoticed due to the presence of other receptors, such as the low-density lipoprotein receptor-related protein, which allow species-independent attachment. The species specificity of HRV1A reported here will aid in defining amino acid residues establishing the contact between the viral surface and the receptor.

Animals↗
PubMed1994

Species specificity and organ, cellular and subcellular localization of the 100 kDa Ras GTPase activating protein.

A p100-GAP isoform, generated by an alternative splicing mechanism that eliminates the 180 hydrophobic amino acids at the amino terminus of p120-GAP, has been described in human placenta, in addition to the known p120GAP and neurofibromin. This p100-GAP possesses full Ras-GTPase stimulating activity. p120-GAP is ubiquitously localized in the cytosol while the localization of p100-GAP is unknown. Here we have explored the precise localization of p100-GAP and show that p100-GAP is present only in extracts of primate placenta. It is abundant in both human and Maccaca Rhesus placentae, where it is present in far larger amounts than p120-GAP. The p100-GAP is species-specific since it was not detected in the placenta of pig, sheep, mouse or rat. p100-GAP was also found to be organ-specific, since it was not detectable in organs other than the placenta. In this connection, we substantiated our previous finding that p100-GAP is mainly localized in the trophoblasts. Both subcellular trophoblast fractionation and immunofluorescence analyses showed that this protein was distributed between the cytosol, plasma membrane and a fraction bound to the nucleus, but not inside it. This highly restrictive specificity of p100-GAP localization in relation to species, organ and cell type, confirms the extreme singularity of this protein, and strongly suggests a particular specific function in the trophoblast.

Amino Acid Sequence↗
PubMed1995

Vaccinia virus encodes a soluble type I interferon receptor of novel structure and broad species specificity.

Vaccinia virus (VV) and other orthopoxviruses express a soluble type I interferon (IFN) receptor that for VV strain Western Reserve is encoded by gene B18R. The 60-65 kDa glycoprotein is related to the interleukin-1 receptors and is a member of the immunoglobulin superfamily, unlike other type I IFN receptors, which belong to the class II cytokine receptor family. The receptor has high affinity (KD, 174 pM) for human IFN alpha and, unlike other type I IFN receptors, has broad species specificity, binding to human, rabbit, bovine, rat, and mouse type I IFNs. This may have aided VV replication in multiple host species during evolution. A VV B18R deletion mutant is attenuated in a murine intranasal model. This type I IFN receptor represents the fourth VV protein that interferes with IFN and the fourth soluble cytokine receptor expressed by poxviruses.

Animals↗
PubMed1994

Variations in the distribution of sugar residues in the zona pellucida as possible species-specific determinants of mammalian oocytes.

The lectin-binding patterns of mammalian zonae pellucidae were investigated to determine whether differences reflected their characteristic carbohydrate distribution patterns. Ovaries isolated from rodents (mouse, rat and hamster), rabbits, cats, dogs and pigs were fixed with glutaraldehyde and embedded in paraffin wax. Sections 5 microns, were deparaffinized, rehydrated and labelled with ten different biotinylated lectins as probes and avidin-biotin-peroxidase complex as visualant. The zonae pellucidae of all animals studied exhibited species-specific variations in lectin-binding patterns, whereas the lectin binding of their granulosa cells and follicular fluids were identical. Phylogenetically close species, such as the rodents and rabbits demonstrated high similarity in zona pellucida saccharides, expressed in binding of succinylated wheatgerm agglutinin and peanut agglutinin. Lectins such as Dolichos biflorus agglutinin, which binds only to mouse, Griffonia simplicifolia (GS-I), which binds to mouse and rat but not hamster and rabbit and soybean agglutinin, which binds only to rodents, reflect characteristic differences between phylogenetically related mammals.

Animals↗
PubMed1990

Genetic variation at the omp2 porin locus of the brucellae: species-specific markers.

The omp2 locus of Brucella abortus is composed of two closely related genes (omp2a and omp2b) that encode, and potentially both express, homologous porin proteins. Genetic variation at this locus is revealed in the form of restriction-fragment-length polymorphisms which can be used to distinguish the type strains of all six Brucella species. Five of the six species contain single copies of omp2a and omp2b, whereas Brucella ovis appears to have two copies of the omp2a gene. The implications of these results with regard to the physiological functions of the omp2a and the omp2b gene products, phylogeny of the genus, and species-specific adaptation are discussed.

Bacterial Outer Membrane Proteins↗
PubMed2000

Molecular mechanisms of the initiation of oocyte maturation: general and species-specific aspects.

Stimulated by maturation-inducing hormone secreted from follicle cells surrounding the oocytes, fully-grown oocytes mature and become fertilisable. During maturation, immature oocytes resume meiosis arrested at the first prophase and proceed to the first or second metaphase at which they are naturally inseminated. Paying special attention to general and species-specific aspects, we summarise the mechanisms regulating the initial phase of oocyte maturation, from the reception of hormonal signals on the oocyte surface to activation of the maturation-promoting factor in the cytoplasm, in amphibians, fishes, mammals and marine invertebrates.

Amphibians↗
PubMed2004

Acidocalcisomes of trypanosomatids have species-specific elemental composition.

The elemental composition and stoichiometric profile of elements present in acidocalcisomes of different genera of the Trypanosomatidae family (insect, plant, and mammalian parasites) submitted to parallel cultivation conditions were studied. X-ray microanalysis using transmission electron microscopy in conjunction with a morphometric approach was used to investigate the elemental content, number, distribution, and volumetric density of acidocalcisomes of different species. Microanalytical data showed that the different parasites possess the same elemental composition (oxygen, sodium, magnesium, phosphorus, calcium, iron, and zinc) in their acidocalcisomes. However, the relative concentrations of the elements varied among species, but not within acidocalcisomes of individual species. Iron was detected in acidocalcisomes of all species analyzed, characterizing this element as a constituent of these organelles. Taken together, the results strongly indicate a species-specific composition of acidocalcisomes in trypanosomatid parasites.

Animals↗
PubMed1995

A species-specific interaction of rad51 and rad52 proteins in eukaryotes.

The structures and properties of the Rad51 and Rad52 proteins in eukaryotes are described. Both proteins form a complex and are responsible for recombination and repair reactions. The N-terminal region of the Rad51 protein interacts with the C-terminal region of the Rad52 protein. Species-specific interaction is probably essential for the functioning of these genes.

Animals↗
PubMed1996

A carbohydrate antigen of Clonorchis sinensis recognized by a species-specific monoclonal antibody.

The enzyme-linked immunosorbent assay (ELISA)-inhibition test using a Clonorchis sinensis species-specific mouse monoclonal antibody (MAb), CsHyb 0605-23, showed increased specificity over the conventional ELISA used for serodiagnosis of clonorchiasis. To characterize the corresponding antigen further, the MAb was tested against polysaccharide, protein and glycolipid fractions obtained from a crude extract of C. sinensis adult worms, using chloroform, methanol and phenol extractions. Only the polysaccharide fraction was recognized by the MAb among those fractions. Mild oxidation of the antigen with sodium periodate showed decreased reactivity against the MAb. We concluded that the antigen and antigenic determinants recognized by the MAb are carbohydrates.

Animals↗
PubMed1995

The species-specific differences in the cAMP regulation of the tissue-type plasminogen activator gene between rat, mouse and human is caused by a one-nucleotide substitution in the cAMP-responsive element of the promoters.

In rat ovarian cells tissue-type plasminogen activator (tPA) is induced by gonadotropins, by a cAMP-dependent pathway and the induction correlates with the time of follicle rupture in vivo. However, in mice, gonadotropins induce the related but distinct protease urokinase-type plasminogen activator (uPA). Comparison of rat, mouse and human tPA genes reveal that there is a species-specific difference in the promoter that could explain the difference in regulation of the tPA gene between these species. At the position where the rat promoter contains a consensus cAMP-responsive element (CRE), the mouse and human counterparts contains a CRE variant with a one-nucleotide substitution. Transient transfection experiments of rat glial and granulosa cells demonstrated that reporter constructs driven by rat but not mouse or human tPA promoters were efficiently induced by the cAMP-inducing agents forskolin or follicle-stimulating hormone. Following the conversion of the mouse and human CRE-like sequences to rat consensus CRE these promoters became cAMP responsive. In contrast the rat promoter, following conversion of the consensus CRE to the corresponding mouse and human CRE-like sequence, lost the ability to efficiently respond to cAMP. Deoxyribonuclease I footprinting analysis and electrophoretic mobility shift assays were used to examine interactions of nuclear factors with the consensus and variant CRE. Compared to rat CRE, the mouse and human CRE-like sequences had a drastically reduced binding affinity for a nuclear factor identified as the cAMP-responsive element binding protein. Thus the inability of the mouse and human tPA promoters to respond efficiently to forskolin and follicle-stimulation hormone seem to be due to the inability of these CRE-like sequences to efficiently bind transcription factor CRE binding protein.

1-Methyl-3-isobutylxanthine↗
PubMed2005

Determination of methionine and selenomethionine in selenium-enriched yeast by species-specific isotope dilution with liquid chromatography-mass spectrometry and inductively coupled plasma mass spectrometry detection.

Selenomethionine (SeMet) and methionine (Met), liberated by acid hydrolysis of selenium-enriched yeast, were quantified by liquid chromatography-mass spectrometry (LC/MS) using standard additions calibrations as well as isotope dilution (ID) based on species-specific (13)C-enriched spikes. LC inductively coupled plasma mass spectrometry (ICPMS) was also employed for the quantification of SeMet, and (74)Se-enriched SeMet was used for ID calibration. The results were evaluated to ascertain the feasibility of using these methods in a campaign to certify selenized yeast. Good agreement was found between the methods, which, when averaged, gave concentrations of 5482.2 +/- 101 and 3256.9 +/- 217.4 microg/g for Met and SeMet, respectively. This corresponds to a 1.68:1 Met-to-SeMet ratio in the yeast. Quantification by ID LC/MS and LC ICPMS yields the most precise sets of results with relative standard deviations in the range 0.5-1.3% (n = 6). A total selenium concentration of 2064.6 +/- 45.4 microg/g was obtained for this yeast material. The extraction efficiency and a mass balance budget were determined. Acid hydrolysis liberated 81.0% of the total selenium present. SeMet comprised 79.0% of the extracted selenium and 63.9% of the total selenium present in the yeast.

Carbon Isotopes↗
PubMed1989

Species-specific responses of muscle lactate dehydrogenase isozymes to increased contractile activity.

Analyses of lactate dehydrogenase (LDH) isozymes were performed in normal and chronically stimulated (10 Hz, 10 h/d) tibialis anterior (TA) muscles of the mouse, rat, guinea pig, and rabbit. The electrophoretic mobilities of the individual LDH isozymes of normal muscles revealed species-specific patterns. Stimulation up to 28 days evoked increases in the percentage of the H-subunit of LDH. The absolute increase was highest in the rabbit, intermediate in the guinea pig and rat, and lowest in the mouse. The extent of the M- to H-subunit exchange, thus, appeared to be inversely correlated with the basal aerobic-oxidative capacities of the investigated muscles. In addition, a relationship between the expression of the H-subunit of LDH and the increase in aerobic-oxidative capacity became evident from these stimulation-induced processes of metabolic adaptation.

Animals↗