[Study on the effect and mechanism of hepatitis B virus X protein transactivates gene 4 in HepG2 cell apoptosis]

Objective: To investigate the effect and mechanism of XTP4 gene in apoptotic hepatoblastoma HepG2 cell line. Methods: HepG2 cells were transiently transfected with small interfering RNA of XTP4 genes, plasmid pcDNA3.1/myc-His(-) A-XTP4, and hepatitis B virus X protein transactivated x gene 4 (HBX protein trans-activate gene4, XTP4) and their respective negative controls. After 48h, the overexpression and interference expression condition of XTP4 in HepG2 cells were detected by Western blot. HepG2 cells apoptosis was detected by flow cytometry. The expression levels of apoptosis-related proteins P53, Bcl-2, Bax and Caspase-3 in HepG2 cells were detected by Western blot, and Bcl-2/Bax ratio was calculated. The chemiluminescence assay was used to detect activity of caspase-3 in HepG2 cells. The measured data were presented as (x ± s), and independent sample t-test was used for comparison between the two groups. Results: HepG2 cells had successfully achieved the overexpression and interference expression of XTP4 protein. Compared with the control group, the overexpression of XTP4 in HepG2 cells had significantly decreased the number of apoptotic cells (P < 0.05), and increased Bcl-2/Bax (P < 0.05) ratio, but decreased the expression of P53 protein (P < 0.05). The protein expression of Caspase-3 and activity of caspase-3 was decreased (P < 0.05). However, interference with XTP4 expression in HepG2 cells had significantly increased the number of apoptotic cells (P < 0.05) and decreased Bcl-2/Bax (P < 0.05) ratio, but increased the expression of P53 protein (P < 0.05). The protein expression of Caspase-3 and activity of caspase-3 was increased (P<0.05). Conclusion: In HepG2 apoptosis XTP4 has inhibitory effect, and its effect on inhibiting HepG2 apoptosis may be achieved by regulating the Bcl-2/Bax ratio, and the P53 protein may be involved.

[Comparison of therapeutic effects between sitagliptin and voglibose both combined with sensor-augmented insulin pump in newly diagnosed type 2 diabetes]

OBJECTIVE

To compare the therapeutic effects between sitagliptin and voglibose both with sensor-augmented insulin pump (SAP) in newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

Fifty-six newly diagnosed hospitalized T2DM patients in Department of Endocrinology of the First Affiliated Hospital of Dalian Medical University, with hemoglobin A1c (HbA1c) value of 9%-11%, were randomized into the sitagliptin (S) group (n=28) and the voglibose (V) group (n=28) by block randomisation. Participants in S group received sitagliptin 100 mg per day, and V group received voglibose 0.2 mg for 3 times per day. All patients were treated with SAP for 9 days. Real-time continuous glucose monitoring (RT-CGM) was used. Glucose variability parameters were observed. The research has been approved by the ethics committee of the First Affiliated Hospital of Dalian Medical University(KY2014-08).

RESULTS

No significant differences were observed in baseline characteristics between the two groups (all P>0.05). In V group and S group, fasting blood glucose (FPG) [(6.4±1.1) vs (11.4±3.0) mmol/L, P=0.008; (5.5±0.8) vs (11.0±2.1) mmol/L, P<0.001], mean blood glucose(MBG) [(7.5±0.8) vs (12.0±1.1) mmol/L, P=0.045; (6.7±0.7) vs (12.5±1.3) mmol/L, P=0.002], standard deviation of blood glucose (SDBG) (P=0.023, 0.036) decreased and homeostasis model assessment (HOMA)-β (P=0.002, 0.001) increased significantly after 9 days therapy. The mean of daily differences (MODD)(P=0.027), coefficient of variation-FPG (CV-FPG) (P=0.033) and HOMA-IR (P=0.039) in S group significantly decreased, while postprandial glycemic excursion (PPGE)(P=0.003, 0.026, 0.011, 3 meals respectively)and the low glycemic index(LBGI)(P=0.025) in V group decreased, the peak postprandial level of glucose(Δt)was longer compared with before (P=0.028, 0.026, 0.030, 3 meals respectively). After therapy, PPGE in V group significantly became lower than those in S group (P=0.041, 0.032, 0.036, 3 meals respectively), while FPG and MBG in S group were significantly lower than those in V group (P=0.041, 0.039).

CONCLUSIONS

Sitagliptin or voglibose combined with SAP can improve glucose control and protect islet function for patients with newly diagnosed T2DM. Sitagliptin has advantages in controlling MBG and FPG compared with voglibose. Voglibose has more striking advantages in reducing the postprandial blood glucose fluctuation.

Clinical image and pathology of hypertrophic cranial pachymeningitis

The objective of this study was to examine the clinical findings, magnetic resonance imaging (MRI), pathological features, and treatment experiments of patients with hypertrophic cranial pachymeningitis (HCP). The clinical findings, MRI, and pathological appearances of 9 patients with HCP were analyzed retrospectively. The thickened dura mater was markedly enhanced after contrast media injection. The lesion near the brain hemisphere presented long regions of T1- and T2-weighted abnormal signal intensities. The abnormal signal intensities of the brain tissue were decreased significantly. Pathological examination demonstrated chronic inflammation changes, with cerebral dura mater fibrous tissue showing obvious hyperplasia, and the periphery of the blood vessel showing a great quantity of infiltrating phlegmonosis cells. HCP mainly presents headache and paralysis of multiple cranial nerves. The distinctive signs on brain MRIs involve strengthening the signal in the cerebral dura.

All-fiber bandwidth-tunable band-rejection filter based on a composite grating induced by CO2 laser pulses

We propose an all-fiber band-rejection filter with a tunable bandwidth, which is realized by putting a normal long-period fiber grating in series with a rotary long-period fiber grating written in a twisted single-mode fiber by CO(2) laser pulses. Bandwidth tuning is achieved by applying torsion to the composite grating. Our experimental filter shows a bandwidth tuning of approximately 16.3 nm at a rejection level of approximately 15 dB and a polarization-dependent loss lower than approximately 0.9 dB.

The QTL analysis on maternal and endosperm genome and their environmental interactions for characters of cooking quality in rice (Oryza sativa L.)

Investigations to identify quantitative trait loci (QTLs) governing cooking quality traits including amylose content, gel consistency and gelatinization temperature (expressed by the alkali spread value) were conducted using a set of 241 RIL populations derived from an elite hybrid cross of "Zhenshan 97"x"Minghui 63" and their reciprocal backcrosses BC1F1 and BC2F1 populations in two environments. QTLs and QTLxenvironment interactions were analyzed by using the genetic model with endosperm and maternal effects and environmental interaction effects on quantitative traits of seed in cereal crops. The results suggested that a total of seven QTLs were associated with cooking quality of rice, which were subsequently mapped to chromosomes 1, 4 and 6. Six of these QTLs were also found to have environmental interaction effects.

Correlation analysis of mineral element contents and quality traits in milled rice (Oryza stavia L.)

The relationships among potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) contents in milled rice (Oryza stavia L.) of 274 genotypes and the relationships between these mineral element contents and other rice quality traits including 3 cooking quality traits, 17 amino acid contents, and protein content were investigated. The results showed that there were significant correlations among most of mineral element contents. Mg, Fe, and Mn contents were significantly correlated with most of the other mineral element contents, while Cu content had significantly negative associations with the K and Mg contents of rice. The relationships between mineral element contents and cooking quality traits showed that gel consistency (GC) was significantly correlated with K, Cu, and Mn contents of rice. Amylose content (AC) was significantly associated with K, Na, Mg, Cu, and Mn contents. The alkali spreading value (ASV) had closely positive relationships with Ca, Mg, and Mn contents. In addition, 8 mineral element contents had obvious correlations with different amino acid contents. Mg, Ca, and Zn contents were significantly correlated with most of the 17 amino acid contents, but Na content did not correlate with amino acid contents except aspartic acid of rice. Furthermore, significant associations were found between protein content and Na, Mg, Zn, Cu, or Mn content. Six principal components were extracted to explain 84.50% of the total variances and contained the information provided by the original 29 variables according to the principal component analysis.

The dynamic gene expression from different genetic systems for protein and lysine contents of indica rice

The dynamic expression of genes for protein and lysine contents of rice grain under different environments was carried out with time-dependent measures by using the developmental genetic models for quantitative traits of triploid endosperm in cereal crops. The results showed that the genetic effects, especially genotype x environment (GE) interaction effects from the genes expression of different genetic systems including triploid endosperm, cytoplasm and diploid maternal plant were important for the performance of both nutrient quality traits at all developmental times/stages of rice grain. The conditional genetic variance analysis found that the activation of quantitative genes especially from endosperm and maternal plant genetic systems for protein and lysine contents was gradually carried through the developmental process of rice grain. The net genetic effects showed that the new expression of quantitative genes for protein and lysine contents was more active at late filling stage (15-21 days after flowering) and maturity stage (22-28 days) of rice grain. Also the sequential expression of cytoplasmic genes cannot be ignorable for the development of nutrient quality traits. The phenomena that some genes could continuously express for several developmental stages or the genes expression could be interrupted among developmental stages of rice grain was detected especially for net endosperm additive main effects or maternal additive main effects. The differences of genetic relationships from different genetic systems were found for protein and lysine contents among developmental times of rice grain.

Genetic and genotype x environment interaction effects for the content of seven essential amino acids in indica rice

It is necessary for rice breeders to understand the genetic basis of nutrient quality traits of rice. Essential amino acids are most important in determining the nutrient quality of rice grain and can affect the health of people who depend on rice as a staple food. In view of the paucity of genetic information available on essential amino acids in indica rice, we estimated the genetic main effects and genotype x environment (G x E) interaction effects on the content of essential amino acids. Nine cytoplasmic male sterile lines as females and five restorer lines as males were introduced in a North Carolina II design across environments. Estimates of the content of the essential amino acids valine, methionine, leucine and phenylalanine showed that they were mainly controlled by genetic main effects, while the contents of threonine, cysteine and isoleucine were mainly affected by G x E effects. In the case of genetic main effects, both cytoplasmic and maternal genetic effects were predominant for all essential amino acids, indicating that selection for improving essential amino acid content based on maternal performance would be more effective than that based on seeds. The total narrow-sense heritabilities were high and ranged from 0.72 to 0.83. Since general heritabilities for these essential amino acids (except for cysteine) were found to be much larger than G x E interaction heritability, the improvement of content of most essential amino acids under selection would be expected under various environments. Rice varieties such as Zhenan 3, Yinchao 1, T49, 26715, 102 and 1391 should be selected as optimal parents for increasing the content of most essential amino acids, while the total genetic effects from Zhexie 2, Xieqingzao, Gangchao 1, V20, Zuo 5 and Zhenshan 97 were mainly negative and these parents could decrease the contents of most essential amino acids.

The Cytological Mechanism of Low Fertility in the Naked Seed Rice

The low fertility of naked seed rice (NSR) was investigated by the following observations: somatic chromosome constitute, behavior of pollen mother cells (PMCs), the germination of mature pollen grains, the development of male and female gametes and the structure of the anther opening. The results indicated that somatic chromosomal number was 2n = 24, behavior of PMCs were normal and most of pollen grains could regularly develop further to mature male gametophytes in NSR. And dehiscence chamber and thickened endothecium cell (TEC) in numerous anthers of the NSR were developed abnormally after dicaryotic phase, result in few anthers complete opening and most partly opening or failure to opening, therefore much fewer of pollen grains attach on the stigma as compared with normal variety. Furthermore most of embryo sacs possessed abnormal structure and were sterile. All of above illustrated that the failure of the anther opening and the abortion of female gametophyte were main factors controlling the low seed-setting rate of the NSR.

Methods of developing core collections based on the predicted genotypic value of rice ( Oryza sativa L.)

The selection of an appropriate sampling strategy and a clustering method is important in the construction of core collections based on predicted genotypic values in order to retain the greatest degree of genetic diversity of the initial collection. In this study, methods of developing rice core collections were evaluated based on the predicted genotypic values for 992 rice varieties with 13 quantitative traits. The genotypic values of the traits were predicted by the adjusted unbiased prediction (AUP) method. Based on the predicted genotypic values, Mahalanobis distances were calculated and employed to measure the genetic similarities among the rice varieties. Six hierarchical clustering methods, including the single linkage, median linkage, centroid, unweighted pair-group average, weighted pair-group average and flexible-beta methods, were combined with random, preferred and deviation sampling to develop 18 core collections of rice germplasm. The results show that the deviation sampling strategy in combination with the unweighted pair-group average method of hierarchical clustering retains the greatest degree of genetic diversities of the initial collection. The core collections sampled using predicted genotypic values had more genetic diversity than those based on phenotypic values.

Developmental behavior of gene expression for brown rice thickness under different environments

The dynamic changes of genetic effects, including main effects, and genotype x environment (GE) interaction effects on brown rice thickness (BRT) across environments were investigated by using the developmental genetic models. Seven cytoplasmic male sterile lines of indica rice (Oryza sativa L.) as females and five restoring lines as males were used in a factorial design to produce grains of F(1)s and F(2)s in two environments (years) for developmental genetic analysis. The results indicate that genetic effects, especially GE interaction effects of triploid endosperm genes, cytoplasm genes, and diploid maternal plant genes were important to the performance of BRT at various filling stages of rice. The BRT was genetically controlled by the net genetic effects of genes expressed at the early and late filling stages (1-7 days and 15-21 days after flowering, respectively). The differences in net genetic effects under different environments for endosperm, cytoplasm, and maternal plant genes were found, and the net GE interaction effects were more important to BRT at the early filling and mature stages of rice. Some net genetic effects, especially for net cytoplasm effects spasmodically expressed, were detected among filling stages. Higher additive and cytoplasm main effects, along with their interaction effects, were found, which would be useful for selection for BRT in breeding programs. The predicated genetic effects at different filling stages show that the parents of V20 and Xieqingzao were better than others for improving BRT of progenies.

Studies on anthracenes. 1. Human telomerase inhibition and lipid peroxidation of 9-acyloxy 1,5-dichloroanthracene derivatives

The synthetically useful approaches to 9-acyloxy 1,5-dichloroanthracene derivatives are reported. The system selectively reduces the carbonyl group flanked by the peri substituents of the anthracenediones to give the corresponding 1,5-dichloro-9(10H)-anthracenone. Simple regioselective acylation of anthracenone is applied with appropriate acyl chlorides in CH2Cl2 with catalytic amount of pyridine to give the novel 9-acyloxy 1,5-dichloroanthracene derivatives. Considerable interest has developed in the mechanism of how anthracenone achieves this desirable selectivity. In an attempt to understand the mechanism of this reaction, solid-state structures of anthracene derivatives have been obtained. In addition, the inhibition of lipid peroxidation in model membranes was determined as was their ability to inhibit the telomere-addition function of the human telomerase enzyme together with their inhibition of the Taq polymerase enzyme. In contrast to (+)-alpha-tocopherol, 3b, 3c, 3d, 3g, and 3i do not enhance lipid peroxidation in model membranes. Implications for 9-acyloxy 1,5-dichloroanthracene analogues as potential anticancer agents are discussed.

[Developmental genetic analysis of brown rice thickness of indica rice (Oryza sativa L.)]

Analysis of developmental genetic effects for brown rice thickness (BRT) trait in indica rice (Oryza sativa L.) at four different filling stages was conducted and a developmental genetic model and corresponding statistical approaches for quantitative traits of triploid endosperm in cereal crops was used. The results indicated that the diploid maternal plant, triploid endosperm and cytoplasmic genetic effects were important for BRT trait at all filling stages of rice and those effects were the major effect at initial medium, filling period and mature period respectively. The additive and dominance effects were the major effect alternatively at four filling stages of rice. Significant endosperm and maternal dominance effects for BRT suggest that the utilization of heterosis for BRT is viable. The results of conditional genetic variance components shown that the expression of new quantitative genes in endosperm, cytoplasm and maternal plant for BRT was found at most filling stages of rice. The gene expression was most active at the early filling stages, especially at the second stage (8-14 days after flowering). Near to mature period (22-28 days after flowering), however, the expression of genes decreased sharply and even closed. The phenomena that the genes expressed spasmodically, i.e. the net genetic effects equaled to zero in some filling stages were detected for some genetic effects. Dominance and cytoplasmic correlation coefficients were significant at 0.05 or 0.01 probability level in some filling stages meanwhile there were the most strong relationship between mature period and other periods for BRT.

[Translation initiation function of the regulation element in the operon of cholera toxin A]

To demonstrate that there existed translation coupling between cholera toxin A subunit gene and B subunit gene, and give the answer why the expression level of B gene is five times more than that of A gene, alpha report system for the investigation of translation coupling was constructed by using lacZ gene as reporter. Frame-shift mutation was introduced near the C terminal of ctxA gene, and the ribosome would read through its normal stop codon. The report plasmid was constructed and it was found that the expression level of lacZ gene decreased five times after the frame-shift mutation. The translation of cholera toxin B subunit gene was translational coupled with A subunit gene, and was responsible for the differential expression level of the two genes.

[A new model of translational control of gene expression in polycistron++ of AB5 entrerotoxin]

The expression level of the B subunit gene of cholera toxin (ctx) and E. coli heat labile toxin (ltx) is five to seven times more than that of A subunit gene. In these studies, a 80 basepair translation regulation element was found located in the structure gene of A gene of both toxin operon which consists of three translation initiation region. Site-directed mutation of the initiation codon of TIR3 resulted in the 9 time decrease of the expression of the downstream cistron which was translational coupled with A gene. The results indicated that translation from the internal of A gene and translation coupling are responsible for the differential expression level of the A and B gene of AB5 enterotoxin.

[Preliminary study on cytochrome C oxidase 1 gene of Oncomelania hupensis from Miao River area in Hubei province]

OBJECTIVE

To study the mitochondrial cytochrome C oxidase 1(CO1) gene of Oncomelania snails from Miao River area in Hubei Province.

METHODS

Oncomelania snails were collected from Miao River area, including upstream and downstream. Genomic DNA was extracted from the tissue of the snail. PCR was used to amplify a fragment of the CO1 gene. Sequences of the CO1 fragment were determined directly from the purified PCR products by an automated sequencer. Sequences for each individual were assembled and edited using ESEE 3.0 s. A distance matrix was computed using program DNADISt of PHYLIP(3.57). Unrooted maximum likelihood trees were calculated from program FITCH.

RESULTS

The amplified CO1 gene of the snail was a fragment of 638 bp in length. Sequence analysis showed that the accumulated variable sites were significant different between upstream and downstream populations, being 29 and 46, respectively. From the number of variable sites in the gene, snails in this area were roughly separated into two groups. Each of them was a mixture of both upstream and downstream snails. Same haplotypes were confirmed to be present among the collected sites along the river. From the distance matrix of sequence divergence, the population upstream vs downstream differed by 0.0221 +/- 0.0105.

CONCLUSION

There were more variation in downstream population than that in upstream. Gene flow was identified in these populations. The phylogenetic trees suggest the existence of two groups, but all of them belong to 0. h. hupensis.

[Induction of protective immune response in mice and rhesus monkeys by immunization with fusion protein of cholera toxin B subunit and multiples of Plasmodium falciparum]

Recombinant fusion protein of cholera toxin B subunit (CTB) and poly-valent protective epitopes of plasmodium falciparum was given to i.m. to C57BL/6j mice and rhesus monkeys three times. In rhesus monkeys, high level of antibodies for CTB (1:6400) and malaria epitopes (1:3200) amtobpdoes were elicited as well as the specific CTL activity for P. plasmodium. After the mice were challenged with sporozoites of P. yeolli, about 50% of them were protected from the patent infection. A blood-stage challenge with 10(8) of P. cynomolgi parasite were given to rhesus monkeys, which showed that two animals in control group were patent infection for at least 30 days, in contrast, the two animals immunized were recovered respectively at the day of 11 and 15 after challenges. The results suggested that cholera toxin acts as an effective adjuvent in the development of malaria vaccine.

Characteristics of recombinant human butyrylcholinesterase

AIM

To study the biochemical-pharmacological properties of the recombinant human butyrylcholinesterase (rhBChE) and thereby to size up the potential possibility of using it as a detoxifying agent in succinylcholine intoxication.

METHODS

CHO-dhfr cells were transfected with plasmids by electroporation. BChE activity was determined colorimetrically by 5, 5'-dithiobis-(2-nitrobenzoic acid) (DTNB) method. Antigenicity was estimated by enzyme-linked immunosorbent assay and Western blot.

RESULTS

The maximal expression amounted to 25.83 ng.h-1/10(6) cells. The rhBChE was highly similar to the native human BChE (nhBChE) in terms of its catalytic property, substrate affinity, inhibitor sensitivity, reactivation, stability, and immunoreactivity with anti-nhBChE antibodies. Mice challenged with 1.5 lethal dose of succinylcholine preincubated with rhBChE survived without any symptoms of intoxication.

CONCLUSION

The rhBChE and nhBChE exhibit similar biochemical-pharmacological features. It is of potential value in practical use.

Analysis of genetic effects on nutrient quality traits in indica rice

Nine cytoplasmic male-sterile lines and five restorer lines were used in an incomplete diallel cross to analyze seed effects, cytoplasmic effects, and maternal gene effects on nutrient quality traits of indica rice (Oryza sauva L.). The results indicated that nutrient quality traits were controlled by cytoplasmic and maternal effects as well as by seed direct effects. Maternal effects for lysine content (LC), lysine index (LI), and the ratio of lysine content to protein content (RLP) were more important than seed direct effects, while protein content (PC) and protein index (PI) were mainly affected by seed direct effects. Cytoplasmic effects accounted for 2.41-20.80% of the total genetic variation and were significant for all nutrient quality traits. Additive genetic effects were much more important than dominance effects for all of the traits studied, so that selection could be applied for these traits in early generations.

Gene fusion of cholera toxin B subunit and HBV PreS2 epitope and the antigenicity of fusion protein

A unique EcoRI site was introduced at the 3' end of cholera toxin B subunit (CTB) gene by site-directed mutagenesis, polynucleotides encoding 120-145aa epitope of HBV PreS2 were chemically synthesized and fused to the 3' end of cholera toxin B subunit gene. The fused gene was over-expressed (about 30 micrograms ml-1) in E. coli, and more than 95% of the fusion protein was secreted into the medium. The fusion protein expressed was purified by affinity chromatography. The chimera protein obtained bound to ganglioside GM1, and had the antigenicity of both cholera toxin B subunit and HBV PreS2 as confirmed by ELISA. After mice were immunized intramuscularly with the fusion protein, anti-CTB antibody and anti-PreS2 antibody were produced. These results indicated that the fusion protein retained not only the biological function of CTB but also the antigenicity and the immunogenicity of cholera toxin B subunit and HBV PreS2 epitope. This work provided a sound basis for further studies on the construction of engineered peptide vaccine.

Gout with aseptic loosening of cementless total hip arthroplasty--a case report

One case of gouty patient with aseptic loosening of cementless total hip arthroplasty was reported. Mechanical and biological factors may both play some roles in this ollsening hip. From both cup and stem, no direct evidence of loosening was found from pathologic aspect. Further study may need to define relationship between gout and loosening of total hip arthroplasty.

Structure in the precore region of hepatitis B core gene affecting its expression in E. coli

Restriction fragments of HBV-DNA, cleaved by endonuclease HhaI, containing HBcAg gene were trimmed by BAL-31 exonuclease to remove different lengths of the precore sequence. They were inserted into plasmid pUR222 at EcoRI site through synthetic linker ligation. Transformants in E. coli BMH7118 showing different levels of HBcAg gene expression were screened and analyzed for their nucleotide sequences in the junction region both by Maxam and Gilbert's chemical degradation method and by M13 chain termination method. Results of sequence analysis of different transformants revealed a partial palindromic (loop and stem) structure, at -7 to -35 nucleotide with regard to ATG of the HBcAg gene as position +1, which has dramatic effect on the level of expression of the inserted gene using the same promoter, SD sequence and identical N-terminus. The amount of HBcAg synthesized differed from 9% in the high expressing plasmid to less than 0.01% of the total cell proteins in the low expressing transformants. The findings were compared to results obtained by other workers in studies of HBcAg expression in procaryotes and their significance in the expression of eucaryotic genes in procaryotic cells were discussed.

The effect of upstream sequences to initiator on the expression of gene coding for hepatitis B core antigen

The nucleotide sequences of cloned adw hepatitis B core antigens (HBcAg) which have different levels of expression have been determined by dideoxy chain-terminating method. The results indicate that the different levels of gene expression is primarily due to the different structures of upstream sequences before the initiator of HBcAg genes. The hepatitis B core gene in the low-expressed clone forms a secondary structure before the initiator. This secondary structure has been removed by Bal-31 exonuclease in the high-expressed clone and half of the structure removed in the mid-expressed clone. It is apparent that the transcription/translation of the hepatitis B core gene is somehow blocked because of the secondary structure. Therefore, the amount of HBcAg synthesized in E. coli is dramatically reduced.

Hemagglutinin of swine influenza virus: a single amino acid change pleiotropically affects viral antigenicity and replication

The complete nucleotide sequence has been obtained of the H1 hemagglutinin (HA) gene of a high-yielding (H) mutant of the A/NJ/11/76(H1N1) strain of swine influenza virus in studies of a viral reassortant (X-53a) bearing this gene. This determination has permitted comparison with human influenza H1N1 prototype viruses A/WSN/33 and A/PR/8/34, with which 80% and 94% amino acid homology was found between HA1 and HA2, respectively. Partial sequences have been determined for other viral reassortants containing either H or L (low-yielding phenotype) genes derived from A/NJ/11/76. Sequence of the HA1 region of an L mutant prototype was virtually completed and differed from that of the H mutant by only four amino acid changes. Sequence analysis of four other viruses was restricted to regions of the HA with which monoclonal antibodies capable of distinguishing L and H mutants are presumed to react. Therefore, changes in these sequences are relevant to changes in viral phenotype. Change at residue 155 from Gly to Glu is associated with change from L to H HA phenotype. This site, structurally equivalent to amino acid 158 on the Wiley et al. HA model [Wiley, D. C., Wilson, I. A. & Skehel, J. J. (1981) Nature (London) 289, 373-378] is near the tip of the HA monomer adjacent to the proposed receptor binding site and therefore credibly could influence both viral antigenicity and replication. Because both L and H variants exist in nature and because revertants may be selected in the laboratory as replication variants in the absence of immunoselection, these studies provide evidence for fortuitous antigenic change in association with change in biological function, which is determined by a single base change.