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PubMed2001

Cutting edge: Gln22 of mouse MD-2 is essential for species-specific lipopolysaccharide mimetic action of taxol.

MD-2 associates with the extracellular domain of Toll-like receptor 4 (TLR4) and greatly enhances LPS signaling via TLR4. Taxol, which mimics the action of LPS on murine macrophages, induces signals via mouse TLR4-MD-2, but not via human TLR4-MD-2. Here we investigated the molecular basis for this species-specific action of Taxol. Expression of mouse MD-2 conferred both LPS and Taxol responsiveness on human embryonic kidney 293 cells expressing mouse TLR4, whereas expression of human MD-2 conferred LPS responsiveness alone, suggesting that MD-2 is responsible for the species-specificity as to Taxol responsiveness. Furthermore, mouse MD-2 mutants, in which Gln(22) was changed to other amino acids, showed dramatically reduced ability to confer Taxol responsiveness, although their ability to confer LPS responsiveness was not affected. These results indicated that Gln(22) of mouse MD-2 is essential for Taxol signaling but not for LPS signaling.

Amino Acid Sequence↗
PubMed2004

Identification of residues in an orthopoxvirus interleukin-18 binding protein involved in ligand binding and species specificity.

Interleukin-18 (IL-18) is a critical cytokine in inflammation and adaptive immune responses. The IL-18 binding proteins (IL-18BP) are a family of proteins that bind to, and inhibit the activity of, IL-18. Using point mutagenesis, we analyzed the ectromelia virus IL-18BP to identify residues involved in binding. Because p13 can bind both human and murine IL-18, and because it is highly homologous to the variola virus IL-18BP, we set out to identify residues that may be involved in species specificity. Several of the mutations resulted in complete abrogation of binding affinity. Three (F49A, E77A, and E69A) significantly affected binding with both species of IL-18, but not to the same extent. Mutant H70A showed reduced affinity for human IL-18 while binding to murine IL-18 was not affected. This study demonstrated that interaction of IL-18 with p13 was similar to other IL-18BPs, however, novel species-specific interactions were identified.

Amino Acid Sequence↗
PubMed2005

Differing roles of inhibition in hierarchical processing of species-specific calls in auditory brainstem nuclei.

Here we report on response properties and the roles of inhibition in three brain stem nuclei of Mexican-free tailed bats: the inferior colliculus (IC), the dorsal nucleus of the lateral lemniscus (DNLL) and the intermediate nucleus of the lateral lemniscus (INLL). In each nucleus, we documented the response properties evoked by both tonal and species-specific signals and evaluated the same features when inhibition was blocked. There are three main findings. First, DNLL cells have little or no surround inhibition and are unselective for communication calls, in that they responded to approximately 97% of the calls that were presented. Second, most INLL neurons are characterized by wide tuning curves and are unselective for species-specific calls. The third finding is that the IC population is strikingly different from the neuronal populations in the INLL and DNLL. Where DNLL and INLL neurons are unselective and respond to most or all of the calls in the suite we presented, most IC cells are selective for calls and, on average, responded to approximately 50% of the calls we presented. Additionally, the selectivity for calls in the majority of IC cells, as well as their tuning and other response properties, are strongly shaped by inhibitory innervation. Thus we show that inhibition plays only limited roles in the DNLL and INLL but dominates in the IC, where the various patterns of inhibition sculpt a wide variety of emergent response properties from the backdrop of more expansive and far less specific excitatory innervation.

Acoustic Stimulation↗
PubMed1994

Species-specific functional interactions of DNA polymerase alpha-primase with simian virus 40 (SV40) T antigen require SV40 origin DNA.

Physical and functional interactions of simian virus 40 (SV40) and polyomavirus large-T antigens with DNA polymerase alpha-primase were analyzed to elucidate the molecular basis for the species specificity of polymerase alpha-primase in viral DNA replication. SV40 T antigen associated more efficiently with polymerase alpha-primase in crude human extracts than in mouse extracts, while polyomavirus T antigen interacted preferentially with polymerase alpha-primase in mouse extracts. The apparent species specificity of complex formation was not observed when purified polymerase alpha-primases were substituted for the crude extracts. Several functional interactions between T antigen and purified polymerase alpha-primase, including stimulation of primer synthesis and primer elongation on M13 DNA in the presence or absence of the single-stranded DNA binding protein RP-A, also proved to be independent of the species from which polymerase alpha-primase had been purified. However, the human DNA polymerase alpha-primase was specifically required for primosome assembly and primer synthesis on SV40 origin DNA in the presence of T antigen and RP-A.

Animals↗
PubMed1979

Species specificity of the immediate hypersensitivity to schistosomal proteolytic enzyme.

An acidic proteolytic enzyme which digests host haemoglobin can be isolated and purified from schistosomes. This small glycoprotein is an allergen which sensitizes the host, as shown by immediate hypersensitivity reactions. These are specific for either Schistosoma haematobium or S. mansoni and can be demonstrated by mast cell degranulation in mice or by intradermal skin tests in monkeys. Although high levels of total IgE may be found in acute and chronic schistosomiasis, there was no evident relationship between the worm burden in monkeys and immediate hypersensitivity reactions to either purified enzyme or crude schistosomal extracts. It is suggested that an in vivo correlation between worm burden and manifestations of the allergic response may be perturbed by high titres of non-specific IgE or other homocytotropic antibodies, thus accounting for false negative skin test reactions. Alternatively, a return to low or subnormal IgE levels may allow the restoration of the allergic response, giving rise to false positive reactions. Purified schistosomal antigens offer certain advantages over crude skin test preparations in terms of uniformity of antigen content, dosage and specificity. In addition, the enzyme may represent a species-specific tool for new immunochemical analyses of schistosomiasis.

Animals↗
PubMed1996

The alpha chain of the IL-2 receptor determines the species specificity of high-affinity IL-2 binding.

Interleukin 2 (IL-2) mediated signalling results from ligand binding and subsequent heterodimerization of IL-2r beta and gamma c. The high-affinity IL-2 receptor (IL-2r) is a heterotrimer comprised of the IL-2r alpha, IL-2r beta and gamma c subunits. Whereas human IL-2 effectively binds to either human or murine lymphocytes, murine IL-2 binds with markedly higher affinity to murine receptor complexes than to human complexes. Using cell lines stably expressing heterotrimeric IL-2r that vary in the species origin of individual subunits, we have demonstrated that IL-2r alpha is primarily responsible for the species specificity of IL-2 binding. Studies of ligand binding to the low affinity receptor demonstrated that IL-2r alpha displays a similar species preference to the heterotrimeric complex. Moreover, differences in ligand binding are reflected in differences in proliferation. A cell line expressing human IL-2r alpha and IL-2r beta along with murine gamma c vigorously proliferated only in response to human IL-2 at low doses, while both human and murine IL-2 stimulated proliferation of a cell line containing murine IL-2r alpha (as well as human IL-2r beta and murine gamma c). Therefore, IL-2r alpha is the chain primarily responsible for the species specificity of ligand binding.

Affinity Labels↗
PubMed2006

CRM1, an RNA transporter, is a major species-specific restriction factor of human T cell leukemia virus type 1 (HTLV-1) in rat cells.

Rat ortholog of human CRM1 has been found to be responsible for the poor activity of viral Rex protein, which is essential for RNA export of human T cell leukemia virus type 1 (HTLV-1). Here, we examined the species-specific barrier of HTLV-1 by establishing rat cell lines, including both adherent and CD4(+) T cells, which express human CRM1 at physiological levels. We demonstrated that expression of human CRM1 in rat cells is not harmful to cell growth and is sufficient to restore the synthesis of the viral structural proteins, Gag and Env, at levels similar to those in human cells. Gag precursor proteins were efficiently processed to the mature forms in rat cells and released into the culture medium as sedimentable viral particles. An HTLV-1 pseudovirus infection system suggested that the released virus particles are fully infectious. Our newly developed reporter cell system revealed that Env proteins produced in rat cells are fully fusogenic, which is the basis for cell-cell HTLV-1 infection. Moreover, we show that the early steps in infection, from post-entry uncoating to integration into the host chromosomes, occur efficiently in rat cells. These results, in conjunction with reports describing efficient entry of HTLV-1 into rat cells, may indicate that HTLV-1 is unique in that its major species-specific barrier is determined by CRM1 at a viral RNA export step. These observations will enable us to construct a transgenic rat model expressing human CRM1 that is sensitive to HTLV-1 infection.

Adenocarcinoma↗
PubMed1991

Analysis of the molecular mechanisms for the species-specific transcription of Drosophila and human tRNA gene transcription components.

The transcription of eucaryotic tRNA genes requires two factors IIIB and IIIC, in addition to RNA polymerase III, to reconstitute this process in vitro. We have examined the functional exchangeability of these components from Drosophila and human systems. The reconstitution of heterologous IIIB and IIIC components demonstrated that neither factor will functionally substitute for the homologous components to activate tRNA gene transcription. The addition of the heterologous Drosophila factors to HeLa transcription assays causes an inhibition of RNA synthesis that is dependent upon the order of addition of these proteins to the DNA template. Thus, it appears that tRNA gene transcription in these systems is species-specific. We have further analyzed the reason for the apparent incompatibilities of these components by the use of stable complex formation assays. We find that human HeLa IIIB and Drosophila IIIC are unable to form stably associated complexes with a tRNA gene template, whereas the Drosophila IIIB and HeLa IIIC do form stable but nonproductive complexes. These results demonstrate that specific IIIC-IIIB interactions are critical in the formation of productive transcription complexes and are responsible for the observed species specificity of Drosophila and human tRNA gene transcription.

Animals↗
PubMed1975

Cell surface species-specific high affinity receptors for discoidin: developmental regulation in Dictyostelium discoideum.

Vegetative (noncohesive) D. discoideum cells and cells at several stages during the development of cohesiveness were fixed with glutaraldehyde, and their agglutinability by purified carbohydrate-binding proteins (lectins) from slime molds and plants was determined. The two purified lectins from D. discoideum, called discoidin I and II, were poor agglutinins of fixed vegetative D. discoideum cells and potent agglutinins of fixed cohesive D. discoideum cells. The increased agglutinability of D. discoideum cells by discoidin I or discoidin II with differentiation paralleled discoidin appearance in cell extracts and development of cohesiveness. The lectin of another slime mold, Polysphondylium pallidum (pallidin) and the lectin of Ricinus communis (RCA-I) were also more potent agglutinins of fixed differentiated D. discoideum cells than of fixed vegetative D. discoideum cells. However, wheat germ agglutinin was much more potent with fixed vegetative cells. The association constant (Ka) of discoidin I and discoidin II for fixed differentiated D. discoideum cells was in the range of 10(9) M-1, more than twenty-fold higher than the Ka of these lectins for fixed vegetative cells. The Ka of discoidin I and discoidin II for fixed differentiated P. pallidum cells was an order of magnitude lower than for fixed differentiated D. discoideum cells. The Ka of pallidin for fixed differentiated P. pallidum cells was about 4 X 10(9) M-1 and was an order of magnitude lower for fixed differentiated D. discoideum cells. Since previous studies showed that the lectin of each of these slime mold species is detectable on the surface of cohesive cells, the observation of species-specific receptors on the surface of cohesive cells suggests a basis for species-specific cohesion.

Binding Sites↗
PubMed2004

Characterization of the species-specificity of peroxisome proliferators in rat and human hepatocytes.

Peroxisome proliferation is a well-defined pleiotropic effect that is mediated by the ligand inducible transcription factor peroxisome proliferator-activated receptor (PPAR) alpha. Because marked peroxisome proliferation occurs in rodents but not in humans, we aimed to elucidate the molecular and cellular determinants of this species-specificity in hepatocytes. Analysis of peroxisomal marker enzyme activities confirmed that peroxisome proliferators induced acyl-CoA oxidase (ACOX) and to a lesser extent catalase in rat hepatocytes, but not in human hepatoma HepG2 cells. Transient transfection assays revealed that ciprofibrate and Wy 14,643 induced rat but not human PPARalpha-mediated reporter gene activity in rat FAO and primary hepatocytes on rat but not on human PPARalpha response elements (PPREs). In contrast, in human HepG2 and primary human hepatocytes, peroxisome proliferators did not induce either human or rat PPARalpha activity regardless of rat or human PPRE sequences. In addition, no induction of ACOX gene expression was observed in human hepatocytes independent of the expression level of human PPARalpha. Remarkably, no distinct peroxisome proliferation related responses were observed in human hepatocytes when rat PPARalpha was transfected, although human hepatocytes were responsive to PPARalpha-mediated induction of carnitine palmitoyl transferase-1A and 3-hydroxy-3-methylglutaryl-CoA synthase. These results confirmed that PPARalpha and PPREs are important determinants for the species-specificity of peroxisome proliferation. Nevertheless, our results showed that human hepatocytes limit the extent of peroxisome proliferation regardless of PPARalpha expression.

Acyl-CoA Oxidase↗
PubMed1992

Species specific protein--DNA interactions may determine the chromatin units of genes in S.cerevisiae and in S.pombe.

Yeast genes, such as URA3, are chromatin units characterized by positioned nucleosomes and flanking nuclease sensitive regions (NSRs). To investigate the structural determinants at the chromatin level in vivo, the URA3 gene was dissected into three parts (U5', Umid and U3'), and the chromatin structures of the individual parts were analysed after insertion into minichromosomes and after chromatin assembly in vivo in Saccharomyces cerevisiae. While nucleosome positions were altered on Umid, the 5'-end and the 3'-end of URA3 maintained their native structures (a positioned nucleosome and a NSR each) independent of the site or orientation of insertion. This suggests that the chromatin unit of the native URA3 gene is dominated by strong protein boundaries at the 5'- and 3'-ends. In an alternative approach, we investigated whether nucleosome positions or NSRs were maintained when the whole URA3 gene was placed on a shuttle vector and assembled into chromatin by Schizosaccharomyces pombe providing different proteins, but the same nucleosomal spacing. In a complementary exchange experiment, the ade6 gene of S.pombe was shuttled to S.cerevisiae. In spite of a general conservation of histone proteins and nucleosome core structures, neither nucleosome positions nor NSRs were maintained in the heterologous background. The results demonstrate that chromatin structures are species specific and that the structural boundaries of yeast genes may be dominated by strong species specific protein-DNA interactions.

Chromatin↗
PubMed1975

Selective depletion of chromosomes in a stable mouse-Chinese hamster hybrid cell line using antisera directed against species-specific cell surface antigens.

A chromosomally-stable mouse-Chinese hamster hybrid cell line was subjected to five rounds of selection with cytotoxic antisera raised in rabbits against either the parental mouse 3T3 cells or the parental Chinese hamster Wg-1 cells. Routine karyological analysis of clones isolated at each stage of serum selection revealed that treatment with either serum resulted in a limited loss of chromosomes (compared to the untreated hybrid cell cultured in parallel) and that the pattern of chromosome loss could not be correlated with the particular antiserum used for selection. However, more detailed analysis with the SSC-formamide C-banding technique, which identifies chromosomes containing a mouse centromere region, demonstrated that while large-scale chromosome loss was not achieved as a result of antiserum selection, the limited loss of chromosomes did, in fact, reflect a specific depletion of chromosomes in response to treatment with cytotoxic antiserum. Specific chromosomal elimination was shown to occur as early asthe first round of antiserum treatment. Antigenic analysis of the serum-selected clones revealed a quantitative decrease in the expression of the species-specific surface antigens selected against, but no qualitative loss of antigens was detected. The results suggest that treatment with cytotoxic antiserum may select for clones that have lost specific chromosomes bearing genes regulating the expression of species-specific surface antigens, rather than for those demonstrating large-scale depletion of chromosomes bearing the corresponding structural genes.

Antigens↗
PubMed1981

Autoantibodies to the human thyrotropin receptor are not species specific.

To ascertain the clinical usefulness of nonhuman thyroid-dependent TSH radioligand-receptor assays, we have reexamined the species specificity of the human TSH receptor-binding site and the unique TSH binding-inhibiting activity (TBI) found in sera from patients with Graves' disease. The human TSH receptor had a high affinity for nonprimate TSH (0.7 + 0.1 x 10(10) M(-1). However, porcine TSH receptors were of higher affinity and ovine TSH receptors were of lower affinity than the human binding site. A human TSH preparation had a similar potency against bovine TSH standard (NIH-B8) when assessed in both human and porcine radioligand-receptor assays (10 + 1.4 U/mg), suggesting that human TSH receptors showed no evidence of species preference. Although immunoglobulins from normal sera had enhanced nonspecific binding to human rather than porcine or ovine thyroid, the interaction of Graves'-specific immunoglobulin was most dependent on the affinity of the TSH receptor for TSH rather than the species from which the thyroid was derived. Hence, of 10 individual globulin fractions chosen to span the range of TBI obtained with human TSH receptor system, there was complete agreement between human and porcine TBI indices. In contrast, 5 preparations became TBI negative using ovine thyroid. These negative globulin fractions were the lowest 5 titers examined, suggesting that titer was the important factor rather than receptor species. Neither the human TSH receptor-binding site nor the TBI activity found in sera from patients with Graves' disease demonstrated true species specificity. Hence, porcine thyroid may be substituted for human tissue in clinically applicable TBI assays.

Animals↗
PubMed1985

Monoclonal antibodies against species-specific cephalosporinase of Pseudomonas aeruginosa.

Ten hybridomas which produced monoclonal antibodies against species-specific cephalosporinase of Pseudomonas aeruginosa were constructed by somatic cell fusion of SP-2/0 myeloma cells with spleen cells from hyperimmunized BALB/c mice and intraperitoneally injected into mice. Monoclonal antibodies were partially purified from ascites fluids. All ten antibodies thus prepared were IgG immunoglobulins. In a solid-phase immunoassay the antibodies gave positive reactions which could be prevented by the presence of free cephalosporinase. When the antibodies were precipitated with anti-(mouse IgG), the cephalosporinase activity was co-precipitated. Also, these antibodies were co-eluted with cephalosporinase activity in gel filtration. Nine of the monoclonal antibody preparations elevated the cephalosporinase activity by about 6-40% and only one inhibited it by about 50%. All the monoclonal antibodies were highly specific to P. aeruginosa cephalosporinase and showed no cross-reaction with nine cephalosporinases and four penicillinases of other gram-negative bacteria.

Antibodies, Monoclonal↗
PubMed1995

Species-specific 18S rRNA gene amplification for the detection of P. falciparum and P. vivax malaria parasites.

Based on the sequence diversity of the Plasmodium 18S ribosomal RNA (rRNA), we designed oligonucleotide primers for polymerase chain reaction (PCR) to yield different size fragments for P. falciparum and P. vivax. The primers for the PCR procedure were chosen such that the 5' primer was Plasmodium-conserved while the 3' primers were species-specific. Using primer cocktails and cloned plasmid DNAs containing the 18S rRNA genes or parasite genomic DNA as targets, we show that the PCR procedure yields 1.4-kb and 0.5-kb DNA fragments for P. falciparum and P. vivax, respectively. Limited field testing of this procedure demonstrated the utility of a ribosomal gene based species-specific malaria diagnosis.

Animals↗
PubMed1997

Reactions of polyclonal and neutralizing anti-p54 monoclonal antibodies with an isolated, species-specific 54-kilodalton protein of Chlamydia pneumoniae.

A recently described 54-kDa protein has been detected in six type strains and three patient isolates of Chlamydia pneumoniae by immunoblotting with sera from patients positive for antibodies to C. pneumoniae by the microimmunofluorescence test. This protein was not found in either C. trachomatis E or C. psittaci Z 432 as an antigen, confirming its species specificity. The 54-kDa protein was isolated by continuous-elution electrophoresis and immunoglobulin G monoclonal antibodies (MAbs) against the isolated antigen were produced. MAb 8B11E6 reacted only with the 54-kDa band of C. pneumoniae and not with C. trachomatis E or C. psittaci in a Western immunoblot assay. This antibody was purified and tested for neutralizing activity together with three additional anti-p54-active MAbs (8B11E6, 8B11B4, and 10F1C1). In Buffalo green monkey cells, all of the MAbs significantly reduced the infectivity of C. pneumoniae elementary bodies, whereas no neutralizing activity could be observed with C. trachomatis E or C. psittaci Z 432. These results not only confirm the species specificity of the 54-kDa protein but also indicate that this protein might play an important role in the pathogenesis of C. pneumoniae infection. Furthermore, the results suggest a possible protective role of anti-p54 antibodies in an adaptive immune response.

Animals↗
PubMed2000

Rapid identification of 11 human intestinal Lactobacillus species by multiplex PCR assays using group- and species-specific primers derived from the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA.

Rapid and reliable two-step multiplex polymerase chain reaction (PCR) assays were established to identify human intestinal lactobacilli; a multiplex PCR was used for grouping of lactobacilli with a mixture of group-specific primers followed by four multiplex PCR assays with four sorts of species-specific primer mixtures for identification at the species level. Primers used were designed from nucleotide sequences of the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA gene of members of the genus Lactobacillus which are commonly isolated from human stool specimens: Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus delbrueckii (ssp. bulgaricus and ssp. lactis), Lactobacillus fermentum, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus paracasei (ssp. paracasei and ssp. tolerans), Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus and Lactobacillus salivarius (ssp. salicinius and ssp. salivarius). The established two-step multiplex PCR assays were applied to the identification of 84 Lactobacillus strains isolated from human stool specimens and the PCR results were consistent with the results from the DNA-DNA hybridization assay. These results suggest that the multiplex PCR system established in this study is a simple, rapid and reliable method for the identification of common Lactobacillus isolates from human stool samples.

Bacterial Typing Techniques↗
PubMed1988

Species specificity of iron delivery in hybridomas.

Studies with Human X Human (H X H), Human X Mouse (H X M), and Mouse X Mouse (M X M) hybridomas have enabled us to define specific factors that affect hybridoma growth in a species-specific manner. Three transferrins and three lipophilic iron chelates have been tested for their ability to support hybridoma proliferation and antibody production. The results of these studies demonstrate that H X H hybridomas do not respond to bovine transferrin a+ concentrations up to 100 micrograms/ml and are approximately 100-fold less responsive to mouse transferrin than to human transferrin. H X M and M X M hybridomas respond equally to human or mouse transferrin but are 100-fold less sensitive to bovine transferrin. An antibody to the human transferrin receptor inhibited the growth-promoting activity of human or mouse transferrin on H X H hybridomas but was ineffective on H X M hybridomas. This demonstrated the functionality of the human transferrin receptor in H X H hybridomas and that human, mouse, and bovine transferrin were interacting through the mouse transferrin receptor in H X M hybridomas. H X H and H X M hybridomas respond similarly to three different iron chelates exhibiting 80 to 110% of the growth response to human transferrin. M X M hybridomas fail to respond to the iron chelates at similar concentrations, suggesting that the human genome present in the other hybridoma species confers a unique ability for utilizing iron when delivered in this form.

Animals↗