Characterization of Toxoplasma gondii isolates in free-range chickens from Chile, South America

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 85 free-range chickens (Gallus domesticus) from Chile was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 47 of 85 (55.3.9%) chickens with titers of 1:5 in six, 1:10 in four, 1:20 in four 1: 40 in three, 1: 80 in nine, 1: 160 in four 1:320 in nine, and 1: 640 or higher in eight. Hearts and brains of 47 chickens with titers of 1:5 or higher were pooled for each chicken and bioassayed in mice. Tissues from 16 seronegative (MAT<1:5) chickens were pooled and fed to one T. gondii-free cat. Feces of the cat were examined for oocysts but none was found based on bioassay of fecal floats in mice. Hearts and brains from seven seronegative (<1:5) were pooled and bioassayed in mice; T. gondii was not isolated. T. gondii was isolated by bioassay in mice from 22 chickens with MAT titers of 1:20 or higher. Genotyping of these 22 isolates using polymorphisms at the loci SAG1, SAG2, SAG3, BTUB and GRA6 revealed three genotypes. Seventeen isolates had type II alleles and four isolates had type III alleles at all loci. One isolate contained the combination of type I and III alleles. This is the first report of genetic characterization of T. gondii isolates from Chile, South America.

Genotyping of Toxoplasma gondii by multilocus PCR-RFLP markers: a high resolution and simple method for identification of parasites

It was generally believed that Toxoplasma gondii had a clonal population structure with three predominant lineages, namely types I, II and III. This was largely based on genotyping of more than 100 T. gondii isolates originating from a variety of human and animal sources in North America and Europe. Recent genotyping studies on T. gondii strains from wild animals or human patients from different geographical regions revealed the high frequency of non-archetypal genotypes, suggesting the overall diversity of the T. gondii population might be much higher than we thought. However, as most genotyping studies had relied on a few biallelic markers, the resolution and discriminative power of identifying parasite isolates were quite low. To date, there is no commonly used set of markers to genotype T. gondii strains and it is not feasible to compare results from different laboratories. Here, we developed nine PCR-restriction fragment length polymorphism markers with each of them capable of distinguishing the three archetypal T. gondii alleles in one restriction-enzyme reaction by agarose gel electrophoresis. Genotyping 46 T. gondii isolates from different sources using these markers showed that they could readily distinguish the archetypal from atypical types and reveal the genetic diversity of the parasites. In addition, mixed strains in samples could be easily detected by these markers. Use of these markers will facilitate the identification of T. gondii isolates in epidemiological and population genetic studies.

Biologic and genetic characteristics of Toxoplasma gondii isolates in free-range chickens from Costa Rica, Central America

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 144 free-range chickens (Gallus domesticus) from Costa Rica was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 60 (40.1%) of 144 chickens with titers of 1:5 in 16, 1:10 in 5, 1:20 in 2, 1:40 in 3, 1:80 in 5, and 1:160 or higher in 29. Tissues of all chickens were bioassayed for T. gondii in mice or cats. Hearts and brains of 52 chickens with titers of 1:5 or higher and 16 chickens with doubtful titers were pooled and bioassayed in mice. Tissues from 76 chickens with MAT titers of 1:10 or less were pooled and fed to three T. gondii-free cats. Fecal floats of cats were bioassayed orally in mice but were negative for T. gondii oocysts. T. gondii was isolated by bioassay in mice from 32 chickens with MAT titers of 1:10 or higher. All infected mice from 4 of the 32 isolates died of toxoplasmosis. Genotyping of these 32 isolates using polymorphisms at the loci SAG1, SAG2, SAG3, BTUB and GRA6 revealed five genotypes. Five isolates had type I alleles and one isolate had type III alleles at all loci. The rest 26 isolates contained the combination of type I and II or I and III alleles and were divided into three genotypes. None was found to have genotype II alleles at all five loci. This is the first report of genetic characterization of T. gondii isolates from Costa Rica, Central America.

Genotyping of Toxoplasma gondii strains from immunocompromised patients reveals high prevalence of type I strains

Toxoplasma gondii is an important food- and waterborne opportunistic pathogen that causes severe disease in immunocompromised patients. T. gondii has an unusual clonal population structure consisting of three widespread lineages known as I, II, and III. To establish the genotypes of strains of T. gondii associated with human toxoplasmosis, we have developed a set of four highly sensitive and polymorphic nested PCR markers. Multiplex nested PCR analysis was used to genotype parasites in cerebral spinal fluid samples from 8 of 10 human immunodeficiency virus-positive patients. Remarkably, a majority of these patients had infections with type I strains or strains containing type I alleles, despite the fact that this lineage is normally uncommon in humans and animals. Multiplex analysis of these four unlinked makers was able to distinguish all three common genotypes and also detected two strains with mixed genotypes. Further analysis based on sequencing of a polymorphic intron revealed that one of these recombinant strains was an exotic lineage distinct from the archetypal clonal lineages. The multiplex nested PCR analysis described here will be useful for analyzing the contribution of parasite genotype to toxoplasmosis.

Genetic diversity, clonality and sexuality in Toxoplasma gondii

The majority of Toxoplasma gondii strains from a variety of human and animal sources have been grouped into three highly clonal but closely related lineages. The low occurrence of nucleotide differences among the three predominant lineages and their unusual dimorphic allelic composition suggest that they have arisen from a recent common ancestry. Less than 1% of the previously studied strains contain unique genotypes and high divergence of DNA sequence, and therefore are considered 'exotic' or 'atypical' strains. The seemingly low genetic diversity in T. gondii may have been underestimated because most parasite strains in previous studies were collected from human patients and domestic animals in North America and Europe. To investigate the genetic diversity of T. gondii, we analysed parasite strains isolated from remote geographical regions by multilocus microsatellite sequencing and phylogenetic analysis. The genetic diversity indices, the molecular analysis of microsatellite genotypes and the constructed phylogram considered together suggest that the global T. gondii population is highly diversified and not characteristic of a clonal organism. The most parsimonious hypothesis is that T. gondii presents a complex population structure with a mix of clonal and sexual propagation as a function of the environmental conditions. The comparison between domestic strains data on one hand and wild strains data on the other hand is in favour of more frequent sexual recombinations in wild environment even though Toxoplasma subpopulation in human and domestic animals is largely clonal.

IFN-gamma is associated with risk of Schistosoma japonicum infection in China

Before the start of the schistosomiasis transmission season, 129 villagers resident on a Schistosoma japonicum-endemic island in Poyang Lake, Jiangxi Province, 64 of whom were stool-positive for S. japonicum eggs by the Kato method and 65 negative, were treated with praziquantel. Forty-five days later the 93 subjects who presented for follow-up were all stool-negative. Blood samples were collected from all 93 individuals. S. japonicum soluble worm antigen (SWAP) and soluble egg antigen (SEA) stimulated IL-4, IL-5 and IFN-gamma production in whole-blood cultures were measured by ELISA. All the subjects were interviewed nine times during the subsequent transmission season to estimate the intensity of their contact with potentially infective snail habitats, and the subjects were all re-screened for S. japonicum by the Kato method at the end of the transmission season. Fourteen subjects were found to be infected at that time. There was some indication that the risk of infection might be associated with gender (with females being at higher risk) and with the intensity of water contact, and there was evidence that levels of SEA-induced IFN-gamma production were associated with reduced risk of infection.

[Clonning and identification of the gene encoding specific IgE antibody-related antigen of Schistosoma japonicum]

OBJECTIVE

To obtain the gene encoding specific IgE-related antigen of Schistosoma japonicum from the cDNA library of adult Schistosoma japonicum.

METHODS

The pooled sera from 15 individuals with high levels of specific IgE antibody against SWAP were absorbed with Protein-G and used for screening of IgE-related antigen from the adult worm cDNA library of Schistosoma japonicum. The inserted cDNA was amplified by PCR and sequenced. According to the first reading frame of the sequence, a pair of new probes, in which EcoR I and Not I sites were incorporated respectively, were designed and used to amplify the target gene. Then, the gene was cloned into vector pGEM-T and subcloned into expression vector pGEX-6p-1. The fusion protein was expressed, analysed by SDS-PAGE and identified by Western blotting with the specific IgE antibody, respectively.

RESULTS

The inserted cDNA fragment from the positive clone was about 1,200 bp, with the ORF of 507 bp which encoded 169 amino acids. The deduced molecular weight of the recombinant protein was 19.3 kDa. The homology between the target gene (Sj43B) and other known DNA sequences was less than 40%. The fusion protein expressed by the recombinant vector pGEX-6p-1/Sj43B could be recognized by schistosome specific IgE antibody.

CONCLUSION

Sj43B may encode the specific IgE-related antigen of Schistosoma japonicum. The successful construction of recombinant plasmid pGEX-6p-1/Sj43B lay the groundwork for further studies on immunological characteristics and protection immunity of the recombinant protein.

[Analysis of the mitochondria-related protein of Schistosoma japonicum and its antigen epitopes]

OBJECTIVE

To sequence the cloned gene Sj338 and to identify the encoded protein and its antigen epitopes.

METHODS

The Sj338 gene fragment obtained from adult S. japonicum cDNA library amplified by PCR method was subcloned into pGEM-T vector for sequencing. The sequence of nucleotides and the characteristics of the encoded protein were analyzed by DNASIS Program and Goldkey DNA and Protein Analytical Program, and then the homology of the amino acid sequence was searched on the BLAST net.

RESULTS

The cloned rSj338 gene was demonstrated to be 487 bp containing one 459 bp ORF, encoding a protein consisted of 153 amino acids with a molecular weight of 17.6 kDa. The amino acid sequence of the recombinant protein rSj338 shared 46% identity with that of the corresponding part of human mitochondrial import receptor and 44% identity with that of the Rattus sp. mitochondrial precursor receptor. The possible antigen epitopes were predicted within the peptide fragments of 26-32 aa, 37-46 aa and 147-151 aa.

CONCLUSION

The protein encoded by rSj338 gene fragment might be the mitochondria-related protein of Schistosoma japonicum.

[Studies on human cytokine responses before and after praziquantel chemotherapy in an endemic area of schistosomiasis japonica]

OBJECTIVE

To observe the cellular immune responses in a population of an endemic area of schistosomiasis japonica and the influence of praziquantel treatment.

METHODS

Blood was taken from 129 residents (64 cases were egg-positive, 65 cases were egg-negitive) of an endemic area of Poyang Lake before and 45 days after praziquantel treatment. Cytokines induced by the schistosome soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP) in the peripheral blood cells including IL-5, IL-10 and IFN-gamma were measured.

RESULTS

Among 129 cases, the cytokine levels were found much higher in egg negative individuals than in egg-positive individuals. The cytokine levels induced by both antigens were increased significantly after praziqantel treatment especially IL-5 and IFN-gamma.

CONCLUSION

The cellular immune responses in the population in schistosomiasis japonica endemic area exhibited a general trend of down-regulation and were elevated significantly after praziquantel treatment.

[Gene cloning and characterization of mitochondria-related protein of Schistosoma japonicum]

OBJECTIVE

To subclone and characterize a cDNA clone coding for Schistosoma japonicum (S.j.) mitochondria-related protein.

METHODS

The open reading frame of the fragment(Sj338/24) obtained from an adult worm cDNA library of S.j. was analysed, at the upstream and downstream of the open reading frame(ORF) the primers A and B were designed, respectively, and the cDNA fragment was used as PCR template. The Sj338 gene fragment obtained was amplified by PCR method and then subcloned into pGEM-T vector for sequencing. The gene sequence was analyzed and the target fragment was restrictedly digested and subcloned into expression vector pGEX-6P-1. The expressed recombinant protein was purified and characterized.

RESULTS

The cloned Sj338 gene was demonstrated to be 487 bp long containing one 459 bp ORF, encoding a protein with a molecular weight of 17 kDa. The nucleotide sequence of the cloned gene Sj338 had higher homology with those genes coding for mitochondrial outer membrane protein of Homo sapiens and Rattus norvegicus. The recombinant construct of pGEX-6P-1/Sj338 could be expressed efficiently and the antigenicity of its product rSj338 has been demonstrated by Western blotting.

CONCLUSION

Sj338 may be the gene coding for S.j. mitochondria-related protein and the recombinant protein may be used as a new vaccine candidate.

Differential expression of the lactose transporter gene affects growth of Staphylococcus aureus in milk

In this study, differential display polymerase chain reaction (PCR) was used to search for unique or enhanced expression of genes in prevalent bovine mastitis-causing Staphylococcus aureus strains. Comparison of a pair of prevalent and rare strains revealed the differential expression of several genes. The lactose-specific permease, enzyme II (EII), was highly expressed in the prevalent strain. This gene was selected for further study due to its potential influence on bacterial growth, because lactose is the primary carbohydrate in milk. Growth analysis illustrated that prevalent strains reach significantly higher growth densities sooner than rare strains. Quantitative competitive reverse transcription PCR (QC RT-PCR) revealed increased EII mRNA expression in prevalent strains as compared to rare strains. Mutation of the EII gene resulted in abrogated growth and decreased EII mRNA expression in media containing lactose. These data suggest that increased EII expression may facilitate the pathogenesis of S. aureus mastitis by enhancing growth. This study is the first to implicate EII as a potential virulence factor in mastitis, and therefore may be useful in the development of novel therapeutic strategies against S. aureus mastitis.

[Expression and identification of recombinant 22.6 kDa fusion protein of Schistosoma japonicum]

AIM

To obtain a large amount of purified 22.6 kDa antigen of Schistosoma japonicum (Sj22.6) in large quantity.

METHODS

The sequence of the gene fragment encoding Sj22.6 was reformed by PCR and subcloned into plasmid vector pGEX-1 lambda T that coded for the 26 kDa GST antigen of Schistosoma japonicum (Sj26 GST). The recombinant plasmid was transformed into E. coli TG2 and then the positive recombinant clone was expressed by induction with IPTG.

RESULTS

The recombinant Sj22.6/Sj26 GST fusion protein was expressed in 5.1% of total bacterial protein and was easy to be purified with glutathione sepharose 4B. Moreover, the purified recombinant Sj22.6 antigen could be cut off easily from the fusion protein with thrombin and had high immunogenicity.

CONCLUSION

The purified recombinant Sj22.6 protein and Sj22.6/Sj26 GST fusion protein had the same immunological activity as the native Sj22.6 kDa protein.

Recent expansion of Toxoplasma through enhanced oral transmission

The global predominance of three clonal Toxoplasma gondii lineages suggests that they are endowed with an exceptional trait responsible for their current parasitism of nearly all warm-blooded vertebrates. Genetic polymorphism analyses indicate that these clonal lineages emerged within the last 10,000 years after a single genetic cross. Comparison with ancient strains (approximately 1 million years) suggests that the success of the clonal lineages resulted from the concurrent acquisition of direct oral infectivity. This key adaptation circumvented sexual recombination, simultaneously promoting transmission through successive hosts, hence leading to clonal expansion. Thus, changes in complex life cycles can occur rapidly and can profoundly influence pathogenicity.

[Screening and characterization of Schistosoma japonicum reinfection-related cDNA clones]

AIM

To obtain cDNA clones coding for S. japonicum (Sj) reinfection-related specific immunologic molecules for vaccination or diagnosis.

METHODS

An adult S. japonicum cDNA library, of which the cloning efficiency is 3.13 x 10(6), with directional inserts in the vector lambda gt11, was screened with pooled serum from 43 reinfected human cases in a schistosomiasis-endemic area with high level of Sj specific-lgG4 antibodies. Primers located several bases away from the insert position on the lambda gt11 arm were used to amplify the insert fragments by standard PCR. SILVER SEQUENCE (PCR-silver) DNA sequencing system was then used to sequence selected positive clones with relatively large inserts and homology comparison with GenBank database was also carried out.

RESULTS AND CONCLUSION

Eleven phage plaques were defined as positive out of the 8.6 x 10(4) phage plaques immunoscreened by human specific lgG4 antibody. GenBank database retrieval showed that 4 new Sj gene clones including Sj reinfection-related specific protein-encoding gene and Sj mitochondrial protein-coding gene have been obtained.

[Researches on immunogenicity identification of recombinant Sj22.6(rSj22.6) kDa antigen gene of schistosoma japonicum]

AIM

To identify the immunogenicity and the potentiality of rSj22.6 as a candidate vaccine antigen for schistosomiasis japonica.

METHODS

rSj22.6 was tested by Western blot with specific antibodies to identify its immunogenicity. The rSj22.6 protein was isolated and purified by SDS-PAGE and injected twice into rabbits to raise antirSj22.6 serum that was tested by Western blot to recognize the native protein of adult S. japonicum and SEA. C57 mice were immunized with rSj22.6 and challenged with S. japonicum cercariae to identify the protective immunity raised by rSj22.6.

RESULTS

rSj22.6 could be recognized by specific antibodies and could stimulate the rabbits to produce high level of anti-rSj22.6 antibodies. Anti-rSj22.6 serum could recognize an adult native protein with the same molecular weight as rSj22.6. The preliminary immune-challenge test resulted in significant reduction in adult worm burden.

CONCLUSION

rSj22.6 possesses immunogenicity in stimulating rabbits to produce high level of specific antibody and has protective role as a candidate vaccine antigen against S. japonicum infection.

Studies on the development of DNA vaccine against Cysticercus cellulosae infection and its efficacy

DNA vaccine against Cysticercus cellulosae infection was developed and its efficacy was tested. A pair of primers specific to antigen B gene of C. cellulosae was designed which amplified the gene successfully with RT-PCR. The gene was ligated to PV93 vector, and the recombinant of antigen B gene and PV93 was transformed to JM83 cells. The transformed JM83 cells were cultured in a large scale and the plasmid purified. Based on the recombinant plasmid. a DNA vaccine was developed and used to vaccinate two groups of experimental pigs. In each group, there was a routine vaccine, an enhanced vaccine and a control group. Groups 1 and 2 were challenged at 4 months and at 14 days post vaccination respectively with eggs of Taenia solium. The antibody response was also tested with ELISA. The results suggested that all animals vaccinated AgB gene DNA vaccine, no matter by routine or enhanced vaccine, their antibodies reached maximum peak 23 days post vaccination and decreased gradually. When the animals were challenged 4 months after vaccination, they had strong immunity and the parasites decrease rates were 91.2% and 93.1% respectively. When pigs vaccinated with AgB gene DNA vaccine were challenged 14 days post vaccination with 18,000 eggs/pig. The animals showed strong immunity and the parasite decrease rates were 99.5% and 84.9% respectively. However at that time, the antibodies did not reach the peak. While in the control group, the number of C. cellulosae was as many as 2,500. It was concluded that the pigs vaccinated with DNA vaccine had strong immunity against infection of eggs of T. solium.

Down-regulation of specific antigen-driven cytokine production in a population with endemic Schistosoma japonicum infection

Schistosome antigen-driven cytokine responses and antischistosome antibody levels of residents of a Schistosoma japonicum endemic island in Poyang Lake, Jiangxi Province were studied before and 45 days after treatment with praziquantel. IL-4, IL-5, IL-10 and INF-gamma were all detected in the supernatants of whole-blood cultures after stimulation with schistosome soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP). The percentages of subjects producing detectable amounts of each cytokine assayed were higher in the group who were negative by stool examination at the start of the study than in those who were initially stool positive. After praziquantel treatment the percentages of subjects producing both type I and type II cytokines increased. This suggests that the production of both types of cytokine was down-regulated in the presence of live, egg-laying S. japonicum adult worms but that this was reversible by treatment. In contrast, the antibody studies showed higher levels of SWAP and SEA-specific antibodies (IgE, total IgG, IgG4, IgM) in subjects who were originally stool-positive than in those who were stool-negative. After treatment specific IgE responses were elevated, but total IgG and IgG4 anti-SEA and IgM anti-SWAP antibody levels all fell significantly.

[Researches on the nucleotide sequencing of the recombinant Sj 22.6 kDa antigen gene of Schistosoma japonicum]

AIM

To sequence the cloned gene in pGSj24 and to identify the encoded protein.

METHODS

The cloned gene in pGSj24 was digested from the recombinant plasmid by EcoRI, ligated into the M13mp19 vector and sequenced by automatic sequencer. The sequence was analyzed by Goldkey DNA and Protein Analytical Program and DNASIS Program.

RESULTS

The pGSj24 cloned gene was demonstrated to be 840 bp containing one opened reading frame (ORF) with an initiation codon ATG at position 23 nt and a termination codon TAA at position 596 nt, encoding a protein with a molecular weight of 22.6 kDa. At the upstream and downstream of the ORF there were termination codons, so the encoded protein was unable to be larger. However, there was a termination codon TAA at position 11 nt, suggesting why the 22.6 kDa protein expressed separately. The nucleotide sequence of the pGSj24 cloned gene shared 95% identity with that of the corresponding part of S. japonicum 22.6 kDa antigen gene, and 99.7% identity in the encoding part. The deduced amino acid sequence analysis showed a sequence motif known as EF-Hand calcium binding domain, several endoplasmic reticulum targeting sequences and microbodies C-terminal targeting signals. The possible antigen determinants were predicted within the amino acid fragments of 29-32aa, 63-68aa and 87-101aa.

CONCLUSIONS

The cloned gene in pGSj24 is the gene that encodes Sj22.6 kDa antigen.

High-resolution typing of Toxoplasma gondii using microsatellite loci

High-resolution typing of Toxoplasma gondii is essential to understand the effect of genetic differences among strains on the variation in disease manifestation and transmission patterns. Current typing methods discern 3 lineages with minimal within-lineage variation. Described here are 6 new variable loci. These loci, including a minisatellite and 5 microsatellites, were more polymorphic than allozymes, restriction fragment length polymorphisms, and sequence variation in introns. Most importantly, these loci revealed, for the first time, substantial within-lineage variation that was over 6-fold higher than that detected by other markers. Genotyping at these loci facilitates classification of isolates beyond the lineage level.

Cancer preventive effect of Morinda citrifolia (Noni)

Morinda citrifolia (Noni) has been extensively used in folk medicine by Polynesians for over 2,000 years. It has been reported to have broad therapeutic effects, including anticancer activity, in both clinical practice and laboratory animal models. The mechanism for these effects remains unknown. The hypothesis that Morinda citrifolia possesses a cancer preventive effect at the initiation stage of carcinogenesis was studied. Our preliminary data indicated that 10% Tahitian Noni Liquid Dietary Supplement or Tahitian Noni Juice (TNJ), made from Morinda citrifolia fruit by Morinda Inc, in drinking water for one week was able to prevent DMBA-DNA adduct formation. The levels of DMBA-DNA adducts were reduced by 30% in the heart, 41% in the lung, 42% in the liver, and 80% in the kidney of female SD rats. Even more dramatic results were obtained in male C57 BL-6 mice: 10% TNJ was able to reduce DMBA-DNA adduct formation by 60% in the heart, 50% in the lung, 70% in the liver, and 90% in the kidney. In order to explore the mechanism of this preventive effect, the antioxidant activity of TNJ was examined in vitro by lipid hydroperoxide (LPO) and tetrazolium nitroblue (TNB) assays. In the LPO assay, LPO oxidizes leucomethylene blue to methylene blue in the presence of hemoglobin. The resultant blue color was quantified at 660 nm spectrophotometrically. In the TNB assay, superoxide anion radicals (SAR) reduce TNB into formazan blue that was also measured by absorption at 602 nm. TNJ showed a dose-dependent inhibition of both LPO and SAR in our system. The antioxidant activity of TNJ was compared to the effects of vitamin C, grape seed powder (GSP), and pycnogenol (PYC) at the daily dose per serving level recommended by U.S.RDAs or manufacturers. The results suggest that prevention of carcinogen-DNA adduct formation and the antioxidant activity of TNJ may contribute to the cancer preventive effect of Morinda citrifolia.

Arsenate and arsenite removal by zerovalent iron: effects of phosphate, silicate, carbonate, borate, sulfate, chromate, molybdate, and nitrate, relative to chloride

Batch tests were performed to evaluate the effects of inorganic anion competition on the kinetics of arsenate (As(V)) and arsenite (As(III)) removal by zerovalent iron (Peerless Fe0) in aqueous solution. The oxyanions underwent either sorption-dominated reactions (phosphate, silicate, carbonate, borate, and sulfate) or reduction-dominated reactions (chromate, molybdate, and nitrate) with Peerless Fe0 in the presence of As(V) or As(III), relative to chloride. Pseudo-first-order rate equations were found to describe satisfactorily both As(V) and As(III) removal kinetics in the presence of each competing anion. Of the oxyanions tested for Peerless Fe0 in the pH range from 7 to 9, phosphate caused the greatest decrease in As removal rate (7.0 x 10(-3) to 18.5 x 10(-3) h(-1)) relative to chloride (34.9 x 10(-3) to 36.2 x 10(-3) h(-1)). Silicate, chromate, and molybdate also caused strong inhibition of As removal, followed by carbonate and nitrate, whereas borate and sulfate only caused slight inhibition to As(III) removal. Present results show that Peerless Fe0 may be an excellent permeable reactive barrier medium for a suite of mixed inorganic contaminants. The anion competing effects should be considered when designing permeable reactive barriers composed of zerovalent iron for field applications to remediate As(V) and As(III).

[Chemical constituents from Salix oritrepha Schneid]

OBJECTIVE

To study chemical constituents of the above ground part of Salix oritrepha.

METHOD

Using chromatography to isolate compounds and their structure were identified by physical, chemical and spectral techniques.

RESULT

Four compounds were isolated and elucidated as beta-sitosterol, beta-sitosteryl-3-O-glucoside, friedelin, luteolin-7-O-glucoside.

CONCLUSION

All of them were isolated from S. oritrepha for the first time. Friedelin from the plants of genus Salix for the first time.

The steroid receptor antagonists RU40555 and RU486 activate glucocorticoid receptor translocation and are not excreted by the steroid hormones transporter in L929 cells

RU40555 is a recently available glucocorticoid receptor (GR) antagonist that differs from RU486 by a methyl radical. We have used the mouse fibroblast cell line L929 to study the in vitro effects of RU40555 on GR translocation and function and on the membrane steroid hormones transporter. The results showed that: 1) RU40555 competed for the binding of labelled dexamethasone (Dex) with a K(i) of 2.4 nM; 2) both RU40555 and RU486 were equally potent inhibitors of Dex-induced GR-mediated gene transcription; 3) maximum GR translocation induced by micromolar concentrations of Dex and the GR antagonists was approximately 30-55% loss in the cytoplasmic GR and approximately 40-90% increase in the nuclear GR (assessed by GR immunostaining in cytoplasm and nucleus and western blots of immunoprecipitated GR protein in cytosolic and nuclear fractions) and was similar for the two antagonists; 4) at nanomolar concentrations, RU40555 and RU486 induced more GR translocation than Dex (assessed by [(3)H]Dex binding and western blot of immunoreactive GR in the same cytosolic homogenates); 5) blocking the steroids membrane transporter with verapamil (100 microM) in the presence of Dex (10 nM) increased GR translocation to levels similar to those induced by RU40555 (10 nM) and RU486 (10 nM) alone; 6) verapamil did not affect GR translocation in the presence of RU40555 or RU486. These data demonstrate similar quantitative effects on GR translocation by RU486 and the new GR antagonist, RU40555. Moreover, RU40555, like RU486, is an effective GR antagonist. Finally, there is no evidence that the intracellular concentrations of RU40555 or RU486 are regulated by the steroids membrane transporter in L929 cells.

Evolutionary dynamics of the T-cell receptor VB gene family as inferred from the human and mouse genomic sequences

The diversity of T-cell receptors is generated primarily by the variable-region gene families, each of which is composed of a large number of member genes. The entire genomic sequence of the variable region (VB) of the T- cell receptor beta chain from humans and mice has become available. To understand the evolutionary dynamics of the VB gene family, we conducted a phylogenetic analysis of all VB genes from humans and mice, as well as a detailed analysis of internal DNA duplications in the human genomic VB region. The phylogenetic tree obtained shows that human and mouse VB genes intermingle extensively rather than forming two separate clusters and that many gene duplications occurred both before and after the divergence between primates and rodents. Analyzing the genomic maps of transposable elements (e.g., LINEs and SINEs) and relic VB genes in the VB gene region, we present evidence that a 20-kb VB region duplicated tandemly four times in the human lineage during the last 32 Myr, and 6 out of the 15 VB genes in this region have become nonfunctional during this period. Our results show that the VB gene family is subject to evolution by a birth-and-death process rather than to concerted evolution.

[Research on the near-infrared (NIR) photon migration in multi-layered structures of biological tissues]

The phenomena of photon migration in multi-layered structures of biological tissue is very important in the field of non-invasive near-infrared optical diagnosis. In this paper, a two-layered structure consisting of the fat and the muscle of poke was used as the sample. Near-infrared light source and detector were located on the surface of the fat and a part of the photons reflected by the two-layered structure of the tissue were detected. The relationship between the optical current and the distance from source to detector and the relationship between the optical current and the thickness of the fat layer were given. In order to analyze the experiment results, Monte-Carlo simulation was used to calculate the photons migration traces in the uniform tissues and the Fresnel's law is used to determine the refraction and reflection components of a photon package at the boundary between the fat and the muscle. The results showed that the simulation data coincident well with the experimental results. The conclusion is that the experiment and the simulation method provided in this study may be useful to analyze the photon migration in a mult-layered tissue and to optimize the design of the transducer.

Arsenate and arsenite removal by zerovalent iron: kinetics, redox transformation, and implications for in situ groundwater remediation

Batch tests were performed utilizing four zerovalent iron (Fe0) filings (Fisher, Peerless, Master Builders, and Aldrich) to remove As(V) and As(III) from water. One gram of metal was reacted headspace-free at 23 degrees C for up to 5 days in the dark with 41.5 mL of 2 mg L(-1) As(V), or As(III) or As(V) + As(III) (1:1) in 0.01 M NaCl. Arsenic removal on a mass basis followed the order: Fisher > Peerless Master Builders > Aldrich; whereas, on a surface area basis the order became: Fisher > Aldrich > Peerless Master Builders. Arsenic concentration decreased exponentially with time, and was below 0.01 mg L(-1) in 4 days with the exception of Aldrich Fe0. More As(III) was sorbed than As(V) by Peerless Fe0 in the initial As concentration range between 2 and 100 mg L(-1). No As(III) was detected by X-ray photoelectron spectroscopy (XPS) on Peerless Fe0 at 5 days when As(V) was the initial arsenic species in the solution. As(III) was detected by XPS at 30 and 60 days present on Peerless Fe0, when As(V) was the initial arsenic species in the solution. Likewise, As(V) was found on Peerless Fe0 when As(II) was added to the solution. A steady distribution of As(V) (73-76%) and As(III) (22-25%) was achieved at 30 and 60 days on the Peerless Fe0 when either As(V) or As(III) was the initial added species. The presence of both reducing species (Fe0 and Fe2+) and an oxidizing species (MnO2) in Peerless Fe0 is probably responsible for the coexistence of both As(V) and As(III) on Fe0 surfaces. The desorption of As(V) and As(III) by phosphate extraction decreased as the residence time of interaction between the sorbents and arsenic increased from 1 to 60 days. The results suggest that both As(V) and As(III) formed stronger surface complexes or migrated further inside the interior of the sorbent with increasing time.

Assignment of EPR Transitions in a Manganese-Containing Lipoxygenase and Prediction of Local Structure

A new variant of lipoxygenases, one containing manganese instead of iron, is characterized by electron paramagnetic resonance (EPR) at two frequencies. In the manganous state (S(e) = 5/2), maganese lipoxygenase (MnLO) yields very broad X-band (9.2 GHz) EPR signals, extending over about 800 mT. In contrast, at W-band (94 GHz), the signal is much simplified, consisting of nested transitions centered near the free electron g-value. Computer simulation has been employed to derive estimates of the zero-field splittings for MnLO, with data from these two EPR frequencies. The general features of both X- and W-band spectra are fit, first, by simulations with S(e) = 5/2, but no nuclear hyperfine splitting. The simulations are then refined by inclusion of the hyperfine splitting. On the basis of the simulations, the ranges of zero-field splitting parameters are D = +0.07 to +0.10 cm(-1), and E/D = 0.13 to 0.23. Comparison of the value of D for MnLO with that of other manganese-containing proteins suggests that MnLO has three N-ligands to the metal center and O-ligands in the remainder of 6 coordination positions. The coordination environment of MnLO is similar to that in iron lipoxygenases.

Staphylococcus aureus agr genotypes with enterotoxin production capabilities can resist neutrophil bactericidal activity

Staphylococcus aureus pathogenicity is mainly due to the production of a number of secreted and cell surface-associated proteins under the regulation of the agr gene. A region of the agr gene was used to subgroup S. aureus strains according to restriction fragment length polymorphisms. Additionally, strains were subtyped according to the coagulase gene in order to strengthen discriminatory power. Virulence capabilities of agr genotype subgroups were evaluated using an in vitro neutrophil bactericidal assay, which showed that prevalent genotypes were significantly better at evading this primary host defense. Multiplex PCR was then used to detect enterotoxin genes among the genotype subgroups in order to determine possible virulence candidates that enable strains to combat neutrophil killing. The prevalent genotype strains were found to possess higher production capabilities for enterotoxin A than did low-prevalence strains. The significance of enterotoxin A production capabilities in affecting pathogenicity of S. aureus strains was evaluated and found to have a profound effect on neutrophil killing abilities. The use of a large epidemiological database as a tool for subgrouping strains with varying degrees of pathogenicity has allowed the identification of relevant and previously undefined virulence factors that affect a pathogen's capability to overcome host immune defenses.

Relations of tumor suppressor gene p16 and RB to early diagnosis of lung cancer

OBJECTIVES

To study the incidence and mechanism of the tumor suppressor gene p16 and RB inactivation in lung cancer, and to investigate their relations to biological characteristics, clinical pathological diagnosis and gene classification.

METHODS

Immunohistochemistry, double in situ hybridization, PCR, PCR-SSCP, and sequencing were used to study the changes in the p16 and RB genes in 106 patients with lung cancer. The specimen of normal lung tissue from the patients with lung cancer and specimens of the 23 patients with benign lung diseases were studied in contrast to those of the same patients.

RESULTS

The total expression rate of the p16 and RB genes in the lung cancer tissues of the 106 patients was lower than that in normal lung tissues and tissues of benign lung diseases and was specially related to histological type, metastasis, and clinical stage of lung cancer. In stage I and II lung cancer, the obvious inactivation rate of the tumor suppressor gene p16 or RB was 32.6% or 28.3%. The p16 inactivation appeared largely in non-small cell lung cancer (50.1%), and the RB inactivation largely in small cell lung cancer (88.2%). Homozygous deletion, methylation, and mutation were three mechanisms for the p16 gene inactivation. The deletion rate of the p16 exon 1 and/or exon 2 was 25.8% in the patients with non-small cell lung cancer. Fifteen patients (16.9%) showed methylation at the SmaI sites of CpG island of the p16 gene. PCR-SSCP and sequencing revealed p16 gene mutation in 9 of the 106 patients with lung cancer.

CONCLUSIONS

The p16 and RB genes may play an important role in genesis and progression of lung cancer. The inactivation of the p16 or RB gene may be an early sign of lung canceration, that is important for the early diagnosis. A new gene classification model for lung cancer diagnosis would be set up based on the research of the p16 and RB genes.

[Correlation between methylation on SmaI locus of the CDKN2/p16 gene CpG island and lung cancer]

OBJECTIVE

To study the relationship between the status of methylation of the CDKN2/p16 gene 5'-CpG island and lung cancer.

METHODS

Genomic DNA was digested with methylation-sensitive enzyme SmaI and Southern blotting was applied to analyze the status of methylation of the CDKN2/p16 in 89 cases of lung cancer and 10 cases of normal lung tissue.

RESULTS

Of the 89 cases of lung cancer studied, the CDKN2/p16 gene was shown to be methylated in 15 cases (16.9%). It occurred in 12 of 42 p16 protein negative cases (28.6%), and in 3 of 47 p16 protein positive cases. The CDKN2/p16 gene was not shown to be methylated in 10 cases of normal lung tissue.

CONCLUSION

Methylation of the CDKN2/p16 gene 5'-CpG island may be an important mechanism for gene inactivation in lung cancer progression.

Analyzing high-density oligonucleotide gene expression array data

We have developed methods and identified problems associated with the analysis of data generated by high-density, oligonuceotide gene expression arrays. Our methods are aimed at accounting for many of the sources of variation that make it difficult, at times, to realize consistent results. We present here descriptions of some of these methods and how they impact the analysis of oligonucleotide gene expression array data. We will discuss the process of recognizing the "spots" (or features) on the Affymetrix GeneChip(R) probe arrays, correcting for background and intensity gradients in the resulting images, scaling/normalizing an array to allow array-to-array comparisons, monitoring probe performance with respect to hybridization efficiency, and assessing whether a gene is present or differentially expressed. Examples from the analyses of gene expression validation data are presented to contrast the different methods applied to these types of data.

[Surgical treatment of primary intracerebral neoplasms only presenting with epilepsy]

OBJECTIVE

To analyse the histopathology and the factors influencing the outcome of surgical treatment of primary intracerebral neoplasms only presenting with epilepsy.

METHODS

55 patients with primary intracerebral tumors presenting with epilepsy without other neurologic signs were retrospectively reviewed.

RESULTS

54(98.2%) cases were histologically diagnosed as gliomas among which 42(76.4%) were low-grade and 12(21.8%) high-grade. The incidence of complications for tumor removals was 32.7%. Of the 41 patients who had postoperative follow-up more than 6 months after operation, 20(48.8%) were seizure-free, 3 were rare, 4 were improved, and 14 (34.1%) had no appreciable reduction in seizure frequency. The position of the tumors was significantly correlated with the incidence of postoperative complications and the postoperative seizure control (P < 0.05). The incidence of postoperative complications for frontal and parietal tumors was higher than that for temporal tumors, while the temporal tumors had better postoperative seizure control than the frontal and the parietal ones.

CONCLUSIONS

Most of the primary intracerebral tumors only presenting with epilepsy were low-grade gliomas. The position of tumors was an important factor influencing the extent of surgical removal and the postoperative seizure control.

Potentiation of ganodermic acid S on prostaglandin E(1)-induced cyclic AMP elevation in human platelets

Ganodermic acid S (GAS), isolated from the Chinese medicinal fungus Ganoderma lucidum (Fr.) Karst (Polyporaceae), exhibits inhibitory effects on platelet responses to various aggregating agonists. Our study demonstrated that GAS also participated in potentiating the response of human gel-filtered platelets to prostaglandin (PG) E(1). GAS at <20 microM did not show any significant change of basal cyclic AMP level in gel-filtered platelets. However, GAS potentiated the PGE(1)-evoked cyclic AMP level in a bell-shaped, concentration-dependent manner. The agent at 7.5 microM enhanced the level up to 1.8-fold of that evoked by PGE(1) alone. Collagen did not inhibit the PGE(1)-induced cyclic AMP level in platelets pretreated with GAS at 6 to 7.5 microM. In the presence of 7.5 microM GAS, the agent enhanced the inhibition of PGE(1) on platelet response to collagen in: phosphorylation of myosin light chain and pleckstrin; alpha-granule secretion; cell aggregation and protein-tyrosine phosphorylation. In addition, the agent along with PGE(1) almost abolished the dense-granule secretion and thromboxane (TX) B(2) formation. The results suggest that GAS played an additional role in potentiating the PGE(1)-induced cyclic AMP synthesis. GAS and PGE(1) inhibited additively the platelet response to collagen.

[Relationship between tumor suppressor gene p16 and Rb and early diagnosis of lung cancers]

OBJECTIVES

To study the incidences and mechanisms of tumor suppressor gene p16 and Rb inactivation in lung cancers, and to investigate their relation to biological characters, clinical pathological diagnosis and gene classification diagnosis of lung cancers.

METHODS

Immunohistochemistry, double in situ hybridization, PCR, PCR-SSCP and sequencing were applied to study the changes of p16 and Rb genes in 106 lung cancers and 23 lung tissues of benign diseases.

RESULTS

Total expression rates of p16 and Rb proteins and mRNAs in lung cancers were lower than those in normal lung tissues and benign lung diseases, and they were specially related to histological type, metastasis and clinical stage of lung cancers. In stage I and II lung cancers, the obvious inactivation of tumor suppressor gene p16 or Rb was examined (32.6% or 28.3%); p16 inactivation was detected mainly in non-small cell lung cancers, and Rb inactivation mainly in small cell lung cancers. There were three mechanisms of homozygous deletions, methylations and mutations for p16 gene inactivation. The deletion rate of p16 exon1 and/or exon2 was 25.8%, mainly took place in p16 protein negative cases of non-small cell lung cancers. 15 cases (16.9%) took part in methylations on SmaI sites of CpG island of p16 gene. PCR-SSCP and sequencing showed that 9 cases had p16 gene mutations.

CONCLUSIONS

p16 and Rb genes may play important roles in genesis and progression of lung cancers. Inactivation of p16 or Rb gene may be is an early link of lung canceration, that is very important for early diagnosis of lung cancers. A new gene classification model for lung cancer diagnosis would be set up based on the research of p16 and Rb genes.

[CDKN2/p16 gene cloning and its probe preparation and application in lung cancer]

OBJECTIVES

To clone CDKN2/p16(INK4a) gene, prepare its probe, and to study the change of CDKN2/p16(INK4a) gene in lung cancers.

METHODS

Total RNA of normal lung tissue was extracted, CDKN2/p16(INK4a) gene cDNA synthesized, and CDKN2/p16(INK4a) gene recombinant vector, constructed. Southern blot was used to study CDKN2/p16(INK4a) gene in 46 cases of lung cancers, 3 cases of normal lung tissues, 6 cases of lung tissues near cancer, and 3 cases of lymph nodes with lung cancer metastasis.

RESULTS

Cloned CDKN2/p16(INK4a) cDNA was proved by enzyme digestion and sequencing. Southern blot showed 4.3 kb band in normal lung tissues and lung tissues near cancers, and deletion of CDKN2/p16(INK4a) gene in cancer tissues and lymph nodes with lung cancer metastasis, with a deletion rate of 17.4% (8/46).

CONCLUSION

CDKN2/p16(INK4a) gene may play a role to some extent in progression of lung cancers.

Kinetics of manganese lipoxygenase with a catalytic mononuclear redox center

Manganese lipoxygenase was isolated from the take-all fungus, Gaeumannomyces graminis, and the oxygenation mechanism was investigated. A kinetic isotope effect, k(H)/k(D) = 21-24, was observed with [U-(2)H]linoleic acid as a substrate. The relative biosynthesis of (11S)-hydroperoxylinoleate (11S-HPODE) and (13R)-hydroperoxylinoleate (13R-HPODE) was pH-dependent and changed by [U-(2)H]linoleic acid. Stopped-flow kinetic traces of linoleic and alpha-linolenic acids indicated catalytic lag times of approximately 45 ms, which were followed by bursts of enzyme activity for approximately 60 ms and then by steady state (k(cat) approximately 26 and approximately 47 s(-1), respectively). 11S-HPODE was isomerized by manganese lipoxygenase to 13R-HPODE and formed from linoleic acid at the same rates (k(cat) 7-9 s(-1)). Catalysis was accompanied by collisional quenching of the long wavelength fluorescence (640-685 nm) by fatty acid substrates and 13R-HPODE. Electron paramagnetic resonance (EPR) of native manganese lipoxygenase showed weak 6-fold hyperfine splitting superimposed on a broad resonance indicating two populations of Mn(II) bound to protein. The addition of linoleic acid decreased both components, and denaturation of the lipoxygenase liberated approximately 0.8 Mn(2+) atoms/lipoxygenase molecule. These observations are consistent with a mononuclear Mn(II) center in the native state, which is converted during catalysis to an EPR silent Mn(III) state. We propose that manganese lipoxygenase has kinetic and redox properties similar to iron lipoxygenases.

Expression of human mitochondrial thymidine kinase in Escherichia coli: correlation between the enzymatic activity of pyrimidine nucleoside analogues and their inhibitory effect on bacterial growth

Mitochondrial thymidine kinase (TK2) phosphorylates pyrimidine nucleosides to monophosphates and is expressed constitutively through the cell cycle in all cells. Because of the overlap of its substrate specificity with that of the cytosolic thymidine kinase (TK1) and deoxycytidine kinase (dCK), it has been difficult to determine the role of TK2 in activating nucleosides used in chemotherapy. In this report, we described the construction of a recombinant Escherichia coli strain which could be used to test if TK2 activity is limiting for the toxicity of nucleosides. Enzymes of bacterial origin which are involved in thymidine and deoxyuridine anabolism and catabolism were eliminated, and the cDNA for human TK2 was introduced. In the crude extract of the engineered E. coli, the level of thymidine kinase was, after induction of TK2 expression, several hundred fold higher than in the control strain. Several pharmacologically interesting nucleoside analogues, including 3'-azidothymidine, 2',3'-didehydro-2',3'-dideoxythymidine, and 2', 3'-dideoxy-beta-L-3'-thiacytidine, were tested for their effects on the growth of this recombinant strain. For a comparison, the phosphorylation of these compounds was determined with purified recombinant TK1, TK2, and dCK. A correlation was observed between the phosphorylation of several of these compounds by TK2 and their effects on bacterial growth. These results demonstrate that activation of growth-inhibiting pyrimidine nucleosides can be catalyzed by TK2, and together with recombinant E. coli strains expressing other cellular nucleoside kinases, this whole-cell bacterial system may serve as a tool to predict the efficacy and side effects of chemotherapeutic nucleosides.

Glial cell line-derived neurotrophic factor in the rat pituitary gland

The presence of glial cell line-derived neurotrophic factor (GDNF) is described within specific regions of the adult rat pituitary gland. Immune staining methods revealed a small number of GDNF-immunopositive cells in the anterior lobe, and in areas of the neural lobe, while no immunoreactive endocrine cells were observed in the intermediate lobe. In the neural lobe, immunofluorescence methods were also used to demonstrate that GDNF and glial fibrillary acidic protein (GFAP) are co-localized in the glial cells (pituicytes) of the neural lobe. GDNF was not co-localized with neurofilament (NF) in nerve fibers of the neural lobe, suggesting that it is not present in axonal fibers. Measurements of GDNF content in separated anterior and neurointermediate lobes were also performed, using an enzyme-linked immunoassay (ELISA). Values for GDNF were slightly higher in the neurointermediate lobe than those obtained for the anterior lobe. The presence of GDNF in areas of the pituitary is discussed in the context of its possible function to support and maintain hypothalamic innervation, as well as a potential autocrine factor within endocrine cells.

[Ganciclovir induces apoptosis of rat C6 glioma cell transduced with HSV-tk gene]

OBJECTIVE

To observe whether apoptosis could be induced by ganciclovir (GCV) in the herpes simplex virus-thymidine kinase gene-ganciclovir system (HSV-tk-GCV system) gene therapy for glioma.

METHODS

Transduced C6/tk glioma cell as treated group, wild C6 cell as control group, were studied with morphology, gel-electrophoresis of DNA fragment analysis, fluoroscopy, and flow cytometric study before or after exposed to GCV, and apoptosis of transduced C6/tk glioma cell was ascertained.

RESULTS

When C6/tk cell was treated with GCV at 5 micrograms/ml for 72 hours, cell apoptosis occurred. Typical apoptotic morphological features included cell shrinkage, condensation, and margination of nuclear chromatin were showed by light and electron microscopy, condensed nuclear chromatin and the fragment of nuclei were demonstrated by fluoroscopy, DNA ladder was showed by DNA fragment analysis, apoptotic peak was identified by flow cytometric study. The apoptotic cells accounted for 23% of the cell population. Apoptosis was not observed in control group treated by GCV.

CONCLUSIONS

The apoptosis of transduced C6/tk glioma was induced by GCV, which fit in with the basis of HSV-tk-GCV gene therapy for glioma.

[Correlation of inactivation of CDKN2/p16 gene by methylation and lung cancers]

OBJECTIVE

To study the relationship between methylation state of CDKN2/p16 gene and lung cancers.

METHODS

Genomic DNA was digested with methylation-sensitive enzymes and Southern blotting was used to analyses the methylation state of CDKN2/p16 gene in 89 cases of lung cancer.

RESULTS

Twenty-one out of 89 lung cancers(23.6%) shown methylation of CDKN2/p16 gene, and 17 of them occurred in 42 P16 negative cases with a rate of 40.5%(17/42).

CONCLUSION

Methylation of CDKN2/p16 gene 5' CpG island is probably an important mechanism of gene inactivation; it may take part in the onset and process of lung cancer.

Phylogenetic relationships of Staphylococcus aureus from bovine mastitis based on coagulase gene polymorphism

Coagulase gene restriction fragment length polymorphism (RFLP) patterns were analyzed to determine the phylogenetic relationship among isolates of Staphylococcus aureus from the Czech Republic (n = 27), France (n = 48), Korea (n = 115) and the United States (n = 278). A total of 468 isolates of S. aureus were subtyped into 41 coagulase genotypes. Cluster analysis placed the 41 types into nine clusters. Eighteen API Staph profiles were determined for 102 S. aureus isolates representing 1 to 4 isolates of each coagulase type. The results of the study suggest that based on coagulase gene RFLP analysis, several genetic variants of S. aureus are prevalent. Comparison of coagulase and API Staph profiles indicated that the two identification system were independent of each other.

Diversity and evolution of T-cell receptor variable region genes in mammals and birds

The receptor of a T lymphocyte (TCR) recognizes nonself antigens in the company of major histocompatibility complex (MHC) molecules presented to it by the antigen-presenting cell. The variable region of TCR is encoded by either a concatenation of variable region (TCR-V), diversity region (TCR-D), and joining region (TCR-J) genes, or a concatenation of TCR-V and TCR-J genes. The TCR-V genes exist as a multigene family in vertebrate species. Here we study the evolutionary relationships of TCR-V genes from humans, sheep, cattle, rabbits, mice, and chicken. These six species can be classified into two groups according to the frequency of gamma(delta) T-cells in their peripheral T-cell populations. The "gamma(delta) low" group of species includes humans and mice, in which gamma(delta)T-cells constitute very limited portion of the T-cell population. The "gamma(delta) high" group includes sheep, cattle, rabbits, and chicken, in which gamma(delta) T-cells comprise up to 60% of the T-cell population. Here, we compiled TCR-V sequences from the six species and conducted a phylogenetic analysis. We identified various TCR-V gene subgroups based on the analysis. We found that humans and mice have representatives from nearly all of the subgroups identified, while other species have lost subgroups to different extent. Therefore, the gamma(delta) low species have a high degree of diversity of TCR-V genes, while gamma(delta) high species all have limited diversity of TCR-V genes. This pattern is similar to that found for immunoglobulin variable region (IGV) genes.