[The diploid of genetically engineered yeast for expression of hybrid HBsAg gene SA-28]

By mating a yeast haploid expressing hybrid HBsAg gene SA-28, Y19/YFD158, with another hapolid Y95, the diploid Y95xY19/YFD158 was constructed. The experiments showed that the cell density of the diploid in fermentation was three time higher than that of the haploid, the stability of expression vector in the diploid was much higher than in the haploid, the xpression level of hybrid HBsAg gene of the diploid was more than three time higher than that of the haploid and the average cope number in diploid cell was a little lower than that in the haploid.

[Monitoring glucoamylase fermentation with infrared spectroscopy]

The glucoamylase fermentation was investigated with Fourier transform infrared spectroscopy. During the cultivation, the variation of carbon and nitrogen source can be reflected from the infrared spectra. In most cases, the complex media are used to cultivate cells or bacteria. It is difficult to construct calibration samples with synthetic mixtures which can represent the composition of real broth. The infrared spectral data of the real broth and off-line chemical analysis results were used to establish the calibration model. The model is successfully used to predict the concentrations of total sugar, reduced sugar, and nitrogen in real broth. The correlation coefficients between the infrared analysis results and chemical analysis are 0.999, 0.990 and 0.974 for total sugar, reduced sugar and nitrogen, respectively. The bacteria, culture and operating condition are relatively stable during the practical productive processes. The method can be used to monitor the industrial processes.

The physical association and phosphorylation of Cdc25C protein phosphatase by Prk

prk encodes a protein serine/threonine kinase involved in regulating M phase functions during the cell cycle. We have expressed His6-Prk and His6-Cdc25C proteins using the baculoviral vector expression system. Purified recombinant His6-Prk, but not a kinase-defective mutant His6-PrkK52R, is capable of strongly phosphorylating His6-Cdc25C in vitro. Co-immunoprecipitation and affinity column chromatography experiments demonstrate that GST-Prk and native Cdc25C interact. When co-infected with His6-Prk and His6-Cdc25C recombinant baculoviruses, sf-9 cells produce His6-Cdc25C antigen with an additional slower mobility band on denaturing polyacrylamide gels compared with cells infected with His6-Cdc25C baculovirus alone. In addition, His6-Cdc25C immunoprecipitated from sf-9 cells co-infected with His6-Prk and His6-Cdc25C baculoviruses, but not with His6-PrkK52R and His6-Cdc25C baculoviruses, contains a greatly enhanced kinase activity that phosphorylates His6-Cdc25C in vitro. Moreover, phosphopeptide mapping shows that His6-Prk phosphorylates His6-Cdc25C at two sites in vitro and that the major phosphorylation site co-migrates with the one that is phosphorylated in vivo in asynchonized cells. Further studies reveal that His6-Prk phosphorylates Cdc25C on serine216, a residue also phosphorylated by Chk1 and Chk2. Together, these observations strongly suggest that Prk's role in mitosis is at least partly mediated through direct regulation of Cdc25C.

[Screening of beta zero-thalassemia in cord blood from 2,423 newborns in Xilin county of Guangxi]

OBJECTIVE

To investigate the incidence of beta zero-thalassemia in newborns in Xilin county of Guangxi and identify the common type of the gene mutation.

METHODS

Cord blood samples from successive 2,423 newborns were screened for beta zero-thalassemia by PAGE, and the gene mutation was assayed by PCR and dot blot hybridization.

RESULTS

Seven cases (0.29%) of beta zero-thalassemia were revealed in the 2,423 newborns. The gene mutation types were as follows: three cases of CD17/CD17, two of CD17/CD41-42, one of CD41-42/CD41-42 and one of CD17/IVS-I-1.

CONCLUSION

These data might be of help to prenatal diagnosis of beta zero-thalassemia in Guixi district.

[The genotype-based haplotype relative risk and transmission disequilibrium test analyses of familial febrile convulsions]

OBJECTIVE

To confirm the linkage of familial febrile convulsions to the short arm of chromosome 6(6p) or the long arm of chromosome 8(8q).

METHODS

The authors finished genotyping of Pst I locus on the coding region of heat shock protein (HSP) 70, 5'untranslated region of HSP70-1, 3' untranslated region of HSP70-2, D8S84 and D8S85. The data were processed by the genotype-based haplotype relative risk(GHRR) and transmission disequilibrium test(TDT) methods in PPAP.

RESULTS

Some signs of association and disequilibrium between D8S85 and FC were shown by GHRR and TDT.

CONCLUSION

A suspect linkage of familial febrile convulsions to the long arm of chromosome 8 has been proposed.

[Protection of PNH red blood cells from lysis by transferring GPI-anchored protein vesicles of normal human RBCs in vitro]

OBJECTIVE

To observe the transfer of GPI-anchored protein CD59 from vesicles of normal RBCs to paroxysmal nocturnal hemoglobinuria(PNH) RBCs can correct the susceptibility to complement attack in vitro.

METHODS

Vesicles released from normal RBCs under ATP depletion or storage, are rich in CD59. PNH CD59- RBCs were separated by elution from immunoaffinity column bound with monoclonal antibody CD59, and then incubated with normal RBCs vesicles. The content of CD59 in vesicles and RBCs was detected by Western blot and flowcytometric analysis respectively and hemolysis of PNH CD59- RBCs was detected by cobra venom factor hemolysis test.

RESULTS

The fluorescence intensity of PNH CD59- RBCs were increased from (1.68 +/- 0.57)% to (58.42 +/- 8.25)% and the hemolysis was significantly decreased from (27.13 +/- 9.69)% to (19.49 +/- 7.61)% after incubation with vesicles prepared from normal donors (P < 0.05), while normal RBCs had no obvious change before and after the same treatment. (P > 0.05).

CONCLUSIONS

It seems that CD59 protein molecules could be transfered from normal RBCs vesicles to PNH CD59- RBCs and retaining the complement regulatory function. CD59- RBCs could be rendered less liable to hemolyze during complement attack.

[Demonstration for periodicity of leptospirosis in Yichang City of Hubei Province during 1960-1997]

OBJECTIVE

To study the periodicity of leptospirosis incidence.

METHODS

Data of leptospirosis epidemics in Yichang City collected during the past 38 years from 1960 to 1997 were analyzed with periodic graphics method.

RESULTS

Cause-specific incidence rate of leptospirosis was 15.43 per 100,000 in average, with an epidemic interval of 10 years, with statistical significance in periodic vibration (J = 4.179, P < 0.05).

CONCLUSION

The results mentioned above provided scientific basis for the effective control and prevention of the disease.

[Expression of chimeric single-chain antibody with specificity for HBsAg in E. coli]

The Vk gene of MAb with specificity for HBsAg and human Ck gene have been combined to form chimeric light chain (Vk-Ck) by recombinant PCR, which has combined with VH to construct chimeric single-chain antibody(ScFv-Ck) by a linker encoding a flexible peptide[(Gly3 Ser)3]. The ScFv-Ck has been expressed in the heat-induced expression system and secreted expression system of E. coli respectively. Analysis by Western-blot and indirect ELISA shows that the ScFv-Ck product in two systems both have HBsAg-binding ability, and ScFv-Ck has been secreted from E. coli in the direction of secretion peptide.

Cloning, expression and biochemical characterization of a basic-acidic hybrid phospholipase A2-II from Agkistrodon halys pallas

A cDNA encoding a basic-acidic hybrid phospholipase A2-II from Agkistrodon halys Pallas with an N-terminus highly homologous to that of BPLA2 and a C-terminus sequence almost the same as that of APLA2 was inserted into a bacterial expression vector and effectively expressed in Escherichia coli RR1. The protein was produced as insoluble inclusion bodies. After partial purification by washing, the inclusion bodies with Triton X-100, denaturing and refolding, the renatured recombinant protein was purified by FPLC column superose 12. The purified recombinant enzyme with an isoelectric point of pH 6.8 could cross-react with antiserum prepared against acidic phospholipase A2. The enzymatic activity of the expressed basic-acidic hybrid phospholipase A2-II is close to that of denatured-refolded native basic phospholipase A2, and has the same inhibiting effect on platelet aggregation as denatured-refolded acidic phospholipase A2, but lacks the hemolytic activity of denatured-refolded basic phospholipase A2. To study the structural relationships among basic phospholipase A2, acidic phospholipase A2 and basic-acidic hybrid phospholipase A2-II, molecular modeling of basic-acidic hybrid phospholipase A2-II was done. The roles of various amino acid residues in the enzymatic activity and pharmacological activities of phospholipase A2 are discussed.

Downstream technique study of human tumor necrosis factor alpha and its mutant

The study of downstream techniques for recombinant human necrosis factor alpha (rhTNF alpha) and its mutant (Lys2)-rhTNF alpha led to the results of approximately 50 g wet recombinant E. coli per liter with high expression level (> 50%) harvested from autocontrolled fed-batch culture in 15 L fermentor (B. Braun). The rhTNF alpha and (Lys2)-rhTNF alpha expressed are totally soluble. Followed by the process of ultrasonication, ammonium sulfate precipitation, ion-exchange chromatography (DEAE-sepharose FF, CM-sepharose FF), and molecular sieve (Sephacryl S-200), a yield of approximately 1 g pure recombinant protein from 1 L broth is obtained. The purity is up to 98%. The specific activity of rhTNF alpha and (Lys2)-rhTNF alpha are approximately 1.5 x 10(8) IU/mg and approximately 6 x 10(8) IU/mg, respectively.

Cloning, expression, and purification of Bacillus stearothermophilus DNA primase and crystallization of the zinc-binding domain

The dnaG gene encoding DNA primase has been isolated from chromosomal DNA of Bacillus stearothermophilus and its entire nucleotide sequence determined. The deduced amino acid sequence comprised 597 amino acid residues and the molecular mass was calculated to be 67068 Da. B. stearothermophilus primase was overexpressed in Escherichia coli and purified to homogeneity. The N-terminal 12 kDa zinc-binding domain has been crystallized. The crystals are of the monoclinic space group P21 with cell dimensions a=36 A, b=59 A, c=46 A, beta=91.8 degrees and diffract to 1.7 A resolution.

cDNA cloning and expression of acutin

Acutin, a thrombin-like enzyme was purified from Agkistrodon acutus venom in three steps by DEAE-Sepharose CL-6B, Superose 12 column on FPLC and Mono-Q column chromatographies. Its first 15 N-terminal amino acid residues sequence <VIGGVECDINEHRFL> was then determined and the acutin cDNA was isolated from venom gland total RNA using RT-PCR. Determination of its nucleotide sequence allowed elucidation of the amino acid sequence of mature peptide for the first time. The mature acutin has 233 amino acids and its amino acid sequence exhibits significant homology with those of thrombin-like enzymes from crotaline snakes venoms. Based on the homology, the catalytic residues and disulfide bridges of acutin were deduced to be as follows: catalytic residues, His41, Asp84 and Ser179; and disulfide bridges, Cys7-Cys139, Cys26-Cys42, Cys74-Cys231, Cys118-Cys185, Cys150-Cys164, Cys175-Cys200. The recombinant acutin has been expressed in E. coli and purified by affinity column. The renatured recombinant acutin is reported for the first time to have the activity of clotting fibrinogen and arginine-esterase.

Multi-level repeated measures growth modelling using extended spline functions

This paper explores the fitting of multi-level models to growth data over a wide age range using a new class of extended spline models. These extend conventional splines based on a '+' function representation by allowing variable order functions and by including fractional polynomial terms. The work focuses on modelling human growth in height and head circumference with example data sets. The procedures can be used with covariates and for comparing population parameters.

Human Bub1: a putative spindle checkpoint kinase closely linked to cell proliferation

Eukaryotic cells have evolved a mechanism that delays the onset of anaphase until chromosomes are properly positioned on the spindle. To understand the molecular basis of such surveillance mechanism in human cells, we have cloned a full-length cDNA encoding a putative mitotic checkpoint kinase termed hBub1. Sequence comparison reveals that hBub1 is a structurally conserved protein, sharing 23% amino acid residue identity with BUB1 of budding yeast. In addition, the NH2-terminal portion (161 amino acids) of hBub1 shows a significant homology to yeast MAD3, a protein also known to be involved in the mitotic checkpoint response pathway. Northern blot analyses show that the hBub1 mRNA level is abundantly expressed in tissues or cells with a high mitotic index. When Dami cells undergo terminal differentiation after treatment with phorbol ester, hBub1 expression in this cell line is down-regulated rapidly. The hBub1 protein level is low in G1 and remains relatively constant in S, G2, and M phases. Immunofluorescence analysis shows that hBub1 protein colocalizes with a centromere-kinetochore antigen CREST in interphase, mitotic prophase, and nocodazole-treated cells. Antibody electroporation experiments show that hBub1 is an important component of the spindle checkpoint pathway. Furthermore, fluorescence in situ hybridization analysis maps the hBub1 gene to chromosome 2q12-13. Our studies suggest that hBub1 expression is restricted to proliferating cells and appears to be involved in regulating cell cycle progression. The molecular cloning of hBub1 cDNA will facilitate the study of its role in spindle checkpoint control as well as its potential role in certain genetic disorders.

Expression of membrane-bound transferrin-like protein p97 on the cell surface of chondrocytes

A concanavalin-A-binding protein of 76 kDa was purified from the plasma membrane fraction of rabbit chondrocyte cultures. Amino acid sequencing of the N-terminal region and of tryptic peptides of the protein, in addition to sequencing of its cDNA revealed that this protein is highly similar to the tumour-associated antigen p97. Hence, it was concluded that this protein is the rabbit form of p97. Western blotting, Northern blotting and reverse-transcription PCR analyses indicated that rabbit p97 is expressed at high levels in cartilage and chondrocytes, but is barely detectable in the bone, liver, kidney, small intestine, eye, pancreas, heart, testis, skeletal muscle, spleen and fibroblasts. Immunocytochemical and immunohistochemical analyses demonstrated that p97 is expressed in the plasma membrane of chondrocytes. p97 transcript was detected in all zones of the cartilage but the level was relatively low in the hypertrophic zone. These findings suggest that p97 is involved in maintaining the cell surface characteristics of chondrocytes.

Guinea pig 5-HT transporter: cloning, expression, distribution, and function in intestinal sensory reception

Studies of the guinea pig small intestine have suggested that serotonin (5-HT) may be a mucosal transmitter that stimulates sensory nerves and initiates peristaltic and secretory reflexes. We tested the hypothesis that guinea pig villus epithelial cells are able to inactivate 5-HT because they express the same 5-HT transporter as serotonergic neurons. A full-length cDNA, encoding a 630-amino acid protein (89.2% and 90% identical, respectively, to the rat and human 5-HT transporters) was cloned from the guinea pig intestinal mucosa. Evidence demonstrating that this cDNA encodes the guinea pig 5-HT transporter included 1) hybridization with a single species of mRNA ( approximately 3.7 kb) in Northern blots of the guinea pig brain stem and mucosa and 2) uptake of [3H]5-HT by transfected HeLa cells via a saturable, high-affinity (Michaelis constant 618 nM, maximum velocity 2.4 x 10(-17) mol . cell-1 . min-1), Na+-dependent mechanism that was inhibited by chlorimipramine > imipramine > fluoxetine > desipramine > zimelidine. Expression of the 5-HT transporter in guinea pig raphe and enteric neurons and the epithelium of the entire crypt-villus axis was demonstrated by in situ hybridization and immunocytochemistry. Inhibition of mucosal 5-HT uptake potentiates responses of submucosal neurons to mucosal stimulation. The epithelial reuptake of 5-HT thus appears to be responsible for terminating mucosal actions of 5-HT.

Key roles for E2F1 in signaling p53-dependent apoptosis and in cell division within developing tumors

Apoptosis induced by the p53 tumor suppressor can attenuate cancer growth in preclinical animal models. Inactivation of the pRb proteins in mouse brain epithelium by the T121 oncogene induces aberrant proliferation and p53-dependent apoptosis. p53 inactivation causes aggressive tumor growth due to an 85% reduction in apoptosis. Here, we show that E2F1 signals p53-dependent apoptosis since E2F1 deficiency causes an 80% apoptosis reduction. E2F1 acts upstream of p53 since transcriptional activation of p53 target genes is also impaired. Yet, E2F1 deficiency does not accelerate tumor growth. Unlike normal cells, tumor cell proliferation is impaired without E2F1, counterbalancing the effect of apoptosis reduction. These studies may explain the apparent paradox that E2F1 can act as both an oncogene and a tumor suppressor in experimental systems.

Diversity of cDNAs encoding phospholipase A2 from Agkistrodon halys pallas venom, and its expression in E. coli

As a step toward understanding the structure and function of phospholipase A2(PLA2), we isolated several novel cDNAs encoding Agkistrodon halys Pallas PLA2 isoenzymes including B-PLA2, Asn49-PLA2, A-PLA2, A'-PLA2 and BA1-PLA2 by polymerase chain reaction with oligonucleotide primers corresponding to the N- and C-terminus of these enzymes. The amino acid sequences of A-PLA2 deduced from cDNA are consistent with that isolated from venom except for four residues. Asn49-PLA2 and B-PLA2 are highly similar (> 95%), but the critical residue Asp49 in the active centre of B-PLA2 is replaced by Asn49 in Asn49-PLA2. The N-terminal residues (1-24) of BA1-PLA2 shows high similarity to that of B-PLA2 which has strong ability to hemolyze erythrocytes, while its C-terminal residues (72-125) are the same as that of A-PLA2 which can inhibit platelet aggregation. The successful cloning of these isoenzymes not only provide excellent native material to study the structure-function relationship of PLA2s, but also to disclose the genesis of structural diversity of PLA2s, namely DNA modification and gene rearrangement. The cloned cDNA for A-PLA2 has been expressed in E. coli. By Q-Sepharose column chromatography, denaturation-renaturation and FPLC, we obtained the active recombinant protein with the initiator Met. This is the first report of the production of an active recombinant PLA2 with the initiator Met.

Purification, cDNA cloning and molecular characteristic of a fibrinolytic enzyme from the venom of Agkistrodon acutus

A nonglycoprotein-like fibrinolytic enzyme ((FIB-I) was purified from the crude venom of Agkistrodon acutus by CM-Sepharose CL-6B and DEAE-Sepharose CL-6B ion exchange chromatography and then by FPLC through Superose 12 gel filtration. Its molecular weight is about 23 kDa and isoelectric point is near 6.0. It not only has fibrinolytic and caseinolytic activity, but also can hydrolyze BAEE. The local hemorrhagic activity was found in mice after the subcutaneous injection of this enzyme. EDTA can inhibit its fibrinolytic activity completely, but PMSF and arrowhead proteinase inhibitor have no such obvious inhibitory effect, thus implying that FIB-I is a metalloproteinase. The N-terminal ten amino acid residues 'STEFQRYMEI' of FIB-I was elucidated. A full-length cDNA gene of this enzyme was cloned by using RT-PCR from the total RNA extracted from the snake venom gland and FIB-I was expressed in E. coli. Having analyzed the sequence, we found that it had a typical zinc-chelating characteristic as 'HEXXHXXGXXHD.'

Aging of human mature erythrocytes is like a process of apoptosis in enucleated cell

Apoptosis of nucleated cells is well known, but how about the unnucleated cells is still not elucidated. In the present paper, the morphological and biochemical features of the aged erythrocytes were observed and compared with the characteristic events of apoptosis. Membrane of aged erythrocytes tends to shrink, protrude, from vesicle and lose lipid asymmetry. Aged erythrocytes were removed by phagocytosis. Both of the events are very similar to the apoptotic nucleated cells. The authors suggested that aging of erythrocytes is also a process of apoptosis.

Rapid, transient changes at the env locus of plasma human immunodeficiency virus type 1 populations during the emergence of protease inhibitor resistance

Plasma human immunodeficiency virus type 1 (HIV-1) populations were genetically analyzed at their most variable locus, the envelope gene, during the rapid emergence of resistance to protease inhibitor monotherapy. Plasma virus populations remained genetically constant prior to drug treatment and during the 1 to 2 weeks following initiation of therapy, while viremia fell 10- to 100-fold. Concomitant with rapid plasma viremia rebounds associated with the emergence of drug-resistant virus, marked alterations were then detected at the env locus. Plasma population changes lasted only a few weeks before the reappearance of the pretreatment envelope variants. The emergence of resistance to single protease inhibitors was therefore associated with major but transient changes at a nonselected locus. Selection for resistance to single protease inhibitors thus appears to be more complex than the continued replication of a large, random, and therefore genetically representative sampling of the pretreatment plasma population. The possibility that drug-privileged anatomical sites containing distinct envelope variants and/or a small effective HIV-1 population size account for these results is discussed.

[The effect of antioxidant sodium ferulate on human lymphocytes apoptosis induced by H2O2]

OBJECTIVE

Sodium ferulate is a potent antioxidant purified from ferula assafoetida L. The effect of sodium ferulate on apoptosis of human lymphocytes induced by H2O2 in vitro was studied.

METHODS

Apoptosis was detected by light and electron microscopic, DNA electrophoresis and Flow cytometric cell cycle analysis. mitochondrial function was detected by MTT method. BCL-2 and Bax expression was detected by confocal laser scanning microscope.

RESULTS

The morphological and biochemical changes characteristic of apoptosis were partially restored after treatment with sodium ferulate, Immunofluorescence assay showed a decrease in BCL-2 and an increase in Bax oncogene proteins in lymphocytes treated with H2O2 and an improvement of cell apoptosis was found after sodium ferulate treatment.

CONCLUSION

Oxidative stress can induce apoptosis in lymphocytes, and this induction can be partly prevented by sodium ferulate.

Multi-level models for longitudinal growth norms

Multi-level models for estimating conditional and unconditional longitudinal growth norms are presented. The procedure involves transforming the original growth measurements to Normality and modelling these with a two-level random coefficient model. Growth norms for any desired time interval and function can be derived. Height and weight data are used for illustration.

Human Prk is a conserved protein serine/threonine kinase involved in regulating M phase functions

Human prk encodes a novel protein serine/threonine kinase capable of strongly phosphorylating casein but not histone H1 in vitro. prk expression is tightly regulated at various levels during different stages of the cell cycle in lung fibroblasts. The Prk kinase activity is relatively low during mitosis, G1, and G1/S, and peaks during late S and G2 stages of the cell cycle. Recombinant human Prk expressed through the baculoviral vector system is capable of phosphorylating Cdc25C, a positive regulator for the G2/M transition. Human prk shares significant sequence homology with Saccharomyces cerevisiae CDC5 and Drosophila melanogaster polo, both of which are essential for mitosis and meiosis. Full-length prk transcripts greatly potentiate progesterone-induced meiotic maturation of Xenopus laevis oocytes. On the other hand, antisense prk transcripts significantly delay and reduce the rate of oocyte maturation. When expressed in a CDC5 mutant strain of S. cerevisiae, human Prk, but not a deletional mutant protein, fully rescues the temperature-sensitive phenotype of the budding yeast. Taken together, prk may represent a new protein kinase, playing an important role in regulating the onset and/or progression of mitosis in mammalian cells.