Non-invasive diagnosis of non-alcoholic fatty liver disease: Current status and future perspective

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease throughout the world. Hepatocellular carcinoma (HCC) and liver cirrhosis can result from nonalcoholic steatohepatitis (NASH), the severe stage of NAFLD progression. By some estimates, NAFLD affects almost one-third of the world's population, which is completely new and serious public health issue. Unfortunately, NAFLD is diagnosed by exclusion, and the gold standard for identifying NAFLD/NASH and reliably measuring liver fibrosis remains liver biopsy, which is an invasive, costly, time-consuming procedure and involves variable inter-observer diagnosis. With the progress of omics and imaging techniques, numerous non-invasive serological assays have been generated and developed. On the basis of these developments, non-invasive biomarkers and imaging techniques have been combined to increase diagnostic accuracy. This review provides information for the diagnosis and assessment of NAFLD/NASH in clinical practice going forward and may assist the clinician in making an early and accurate diagnosis and in proposing a cost-effective patient surveillance. We discuss newly identified and validated non-invasive diagnostic methods from biopsy-confirmed NAFLD patient studies and their implementation in clinical practice, encompassing NAFLD/NASH diagnosis and differentiation, fibrosis assessment, and disease progression monitoring. A series of tests, including 20-carboxy arachidonic acid (20-COOH AA) and 13,14-dihydro-15-keto prostaglandin D2 (dhk PGD2), were found to be potentially the most accurate non-invasive tests for diagnosing NAFLD. Additionally, the Three-dimensional magnetic resonance imaging (3D-MRE), combination of the FM-fibro index and Liver stiffness measurement (FM-fibro LSM index) and the machine learning algorithm (MLA) tests are more accurate than other tests in assessing liver fibrosis. However, it is essential to use bigger cohort studies to corroborate a number of non-invasive diagnostic tests with extremely elevated diagnostic values.

Further understanding of chronic hepatitis B in the indeterminate phase or in the grey zone

The prevention and treatment of chronic hepatitis B virus (HBV) infection are still facing great challenges. Even though the Chinese Medical Association (CMA) guidelines for the prevention and treatment of chronic hepatitis B (CHB) (version 2022) have expanded the antiviral treatment indications, there is still a certain proportion of HBV infections that do not meet the antiviral treatment indications, known as the indeterminate phase or the gray zone (GZ). However, the current interpretation and judgment criteria for the indeterminate phase or GZ of HBV infection are not uniform, and their connections and differences are not very clear. Different studies focus on different subjects. Regardless of the identification of the indeterminate phase or GZ, the purpose is to timely and accurately determine the progression of CHB and whether timely treatment is needed. Based on the understanding that the GZ corresponds to the "classification of antiviral treatment indication" and that the indeterminate phase corresponds to the "natural history staging", this article elaborates on the further understanding of CHB in the indeterminate phase or in the GZ. This paper argues that the GZ refers to cases that do not receive treatment for not meeting the antiviral treatment indications, while the indeterminate phase refers to cases that are difficult to be clearly attributed to a natural history stage for not meeting the natural history staging criteria. Thus, the GZ should include the indeterminate phase, and they are not parallel concepts. According to the CMA guidelines (version 2022), patients in the indeterminate phase of GZ are recommended for antiviral treatment; according to the European Association for the Study of the Liver (EASL) guidelines (2017), antiviral therapy is recommended for patients in the immune control phase and the indeterminate phase of GZ.

Liver histopathological lesions is severe in patients with normal alanine transaminase and low to moderate hepatitis B virus DNA replication

BACKGROUND

Chronic hepatitis B virus (HBV) infection remains a major global public health problem. Chronic hepatitis B (CHB) patients can be divided into treatment indication and non-treatment indication individuals according to alanine transaminase (ALT), HBV DNA, serum hepatitis B e antigen status, disease status [liver cirrhosis, hepatocellular carcinoma (HCC), or liver failure], liver necroinflammation or fibrosis, patients' age, and family history of HCC or cirrhosis. For example, normal ALT patients in 'immune-tolerant' phase with HBV DNA higher than 107 or 2 × 107 IU/mL, and those in 'inactive-carrier' phase with HBV DNA lower than 2 × 103 IU/mL do not require antiviral therapy. However, is it reasonable to set the defined values of HBV DNA as the fundamental basis to estimate the disease state and to determine whether to start treatment? In fact, we should pay more attention to those who do not match the treatment indications (gray-zone patients both in the indeterminate phase and in the 'inactive-carrier' phase).

AIM

To analyze the correlation of HBV DNA level and liver histopathological severity, and to explore the significance of HBV DNA for CHB with normal ALT.

METHODS

From January 2017 to December 2021, a retrospective cross-sectional set of 1299 patients with chronic HBV infection (HBV DNA > 30 IU/mL) who underwent liver biopsy from four hospitals, including 634 with ALT less than 40 U/L. None of the patients had received anti-HBV treatment. The degrees of liver necroinflammatory activity and liver fibrosis were evaluated according to the Metavir system. On the basis of the HBV DNA level, patients were divided into two groups: Low/moderate replication group, HBV DNA ≤ 107 IU/mL [7.00 Log IU/mL, the European Association for the Study of the Liver (EASL) guidelines] or ≤ 2 × 107 IU/mL [7.30 Log IU/mL, the Chinese Medical Association (CMA) guidelines]; high replication group, HBV DNA > 107 IU/mL or > 2 × 107 IU/mL. Relevant factors (demographic characteristics, laboratory parameters and noninvasive models) for liver histopathological severity were analyzed by univariate analysis, logistics analysis and propensity score-matched analysis.

RESULTS

At entry, there were 21.45%, 24.29%, and 30.28% of the patients had liver histopathological severities with ≥ A2, ≥ F2, and ≥ A2 or/and ≥ F2, respectively. HBV DNA level (negative correlation) and noninvasive model liver fibrosis 5 value (positive correlation) were independent risk factors for liver histopathological severities (liver necroinflammation, liver fibrosis, and treatment indication). The AUROCs of the prediction probabilities (PRE_) of the models mentioned above (< A2 vs ≥ A2, < F2 vs ≥ F2, < A2 and < F2 vs ≥ A2 or/and ≥ F2) were 0.814 (95%CI: 0.770-0.859), 0.824 (95%CI: 0.785-0.863), and 0.799 (95%CI: 0.760-0.838), respectively. HBV DNA level (negative correlation) was still an independent risk factor when diagnostic models were excluded, the P values (< A2 vs ≥ A2, < F2 vs ≥ F2, < A2 and < F2 vs ≥ A2 or/and ≥ F2) were 0.011, 0.000, and 0.000, respectively. For the propensity score-matched pairs, whether based on EASL guidelines or CMA guidelines, the group with significant liver histology damage (≥ A2 or/and ≥ F2) showed much lower HBV DNA level than the group with non- significant liver histology damage (< A2 and < F2). Patients in the moderate replication group (with indeterminate phase) had the most serious liver disease pathologically and hematologically, followed by patients in the low replication group (with 'inactive-carrier' phase) and then the high replication group (with 'immune-tolerant' phase).

CONCLUSION

HBV DNA level is a negative risk factor for liver disease progression. The phase definition of CHB may be revised by whether the level of HBV DNA exceeds the detection low limit value. Patients who are in the indeterminate phase or 'inactive carriers' should receive antiviral therapy.

MGF360-12L of ASFV-SY18 is an immune-evasion protein that inhibits host type I IFN, NF-κB, and JAK/STAT pathways

African swine fever virus (ASFV) causes feverous and hemorrhagic disease of domestic pigs and European wild boars with high mortality, yet no commercial vaccine is currently available. Several ASFV strains with natural deletion or gene-targeted knockout of multiple MGF360 and MGF505 genes are attenuated in vitro and in vivo, and can offer full protection against homologous challenge. However, the mechanisms underlying the protection are not fully understood. This study aims to investigate the effects of MGF360-12L of ASFV-SY18 on the cGAS-STING signaling pathway and explore the potential mechanisms. We identified that ASFV-SY18 MGF360-12L could inhibit cGAS-STING, TBK1, or IRF3-5D-stimulated IFN-β expression and ISRE activation. Specifically, MGF360-12L inhibits both the activation of PRD(III-I) in a dose-dependent manner, and suppresses the exogenous expression of TBK1 and IRF3-5D. MGF360-12L could block NF-κB activation induced by overexpression of cGAS-STING, TBK1, IKKβ. Downstream of the IFN-β signaling, MGF360-12L blocks the ISRE promoter activation by reducing total protein level of IRF9. Moreover, MGF360-12L protein can inhibit IFN-β-mediated antiviral effects. In conclusion, our findings suggest that MGF360-12L is a multifunctional immune-evasion protein that inhibits both the expression and effect of IFN-β, which could partially explain the attenuation of relevant gene-deleted ASFV strains, and shed light on the development of efficient ASFV live attenuated vaccines in the future.

[Comparison of clinicopathological features for indications of different types of antiviral therapy in chronic hepatitis B]

Objective: To compare and analyze the clinicopathological features and significance for indications of different types of antiviral therapy in chronic hepatitis B (CHB). Methods: Clinical data of 861 CHB cases who received liver biopsy, had hepatitis B virus (HBV) DNA-positive (> 30 IU/ml) and met the indications for antiviral therapy from January 2014 to December 2019 were included. Liver pathological changes and their correlation with clinical characteristics were compared and analyzed. According to different data, t-test, analysis of variance, nonparametric test, χ² test, Ridit and logistic regression analysis were used for statistical analysis. Results: Most of the cases (72.24%) had remarkable pathological damage. The degree of liver fibrosis was higher in the normal than the abnormal group (P<0.001). 17.54% cases had hepatic steatosis. The vast majority of cases (97.33%) had positive hepatitis B surface antigen (HBsAg), while only 50.87% had positive hepatitis B core antigen (HBcAg). The positive correlation factors affecting the severity of liver histopathology were alkaline phosphatase level, while the negative correlation factors were positive HBcAg staining, albumin and platelet level. The degree of liver inflammation and fibrosis had statistically significant differences with different HBcAg staining levels (χ²=44.142 and 102.386, respectively; P<0.001), and the severity was more apparent in the negative group. Conclusion: There exist differences in clinicopathological features for indications of different types of antiviral therapy in patients with CHB. Liver function test range is inconsistent with degrees of hepatic histological severity. The positive and intensity of liver tissue HBcAg staining, and albumin and alanine aminotransferase levels have negative correlation with disease severity.

[Clinicopathological analysis in patients with chronic hepatitis B virus infection in immune tolerant phase]

Objective: To analyze the liver pathology, clinical characteristics and influence factors in patients with chronic hepatitis B virus (HBV) infection in immune tolerant phase (IT). Methods: The clinical data of 273 patients in IT phase who underwent liver biopsy from January 2015 to December 2019 were included in this study. The correlation between liver pathological changes and clinical features was analyzed. Results: There were 43 cases (15.75%) with liver histologic activity ≥ G2, 30 cases (10.99%) with liver fibrosis ≥ S2, and 55 cases (20.15%) with liver pathology ≥ G2 and/or ≥ S2. A total of 17.95% patients had liver steatosis. The majority (98.17%) of tissue samples were positive for HBsAg staining, while only 79.49% were positive for HBcAg. The characteristics of liver pathology were comparable in men from women patients. The differences of G and S were not statistically significant according to different HBsAg positivity, while those were statistically significant according to different HBcAg positivity. By univariate and multivariate analysis, the independent risk factors of pathological severity were HBcAg intensity, HBeAg level, and age. However, the differences of liver histologic activity and fibrosis were not statistically significant between those younger than 30 years old group from those older than 30 years old, neither between those younger or older than 40. Although the diagnostic value of liver inflammation and fibrosis 5 (LIF-5) was better than that of aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis 4 score (FIB-4), three diagnostic models for predicting the pathological severity were not strong enough (all area under the curves<0.8). Only the specificity of LIF-5 for predicting≥ G2, ≥ G2 and/or ≥ S2 was over 80%. Conclusions: Approximately 20% patients with chronic HBV infection in IT phase have progressive liver inflammation or fibrosis. The intensity of liver HBcAg and HBeAg level are negatively correlated with the severity of disease. The diagnostic models or most clinical indicators have low predictive effect for chronic HBV infections in IT phase.

[Clinical feature changes of a COVID-19 patient from mild to critical condition and cardiopulmonary pathological results]

Objective: To analyse the clinical history, laboratory tests and pathological data of a patient who suffered from novel coronavirus pneumonia(COVID-19) and provide reference for the clinical treatment of similar cases. Methods: Data of clinical manifestation, laboratory examination, bronchoscopy, echocardiography and cardiopulmonary pathological results were retrospectively reviewed in a case of COVID-19 with rapid exacerbation from mild to critical condition. Results: This patient hospitalized at day 9 post 2019 novel coronavirus(2019-nCoV) infection, experienced progressive deterioration from mild to severe at day 12, severe to critical at day 18 and underwent extracorporeal membrane oxygenation(ECMO) and continuous renal replacement therapy(CRRT) as well as heart lung transplantation during day 28-45 post infection, and died at the second day post heart and lung transplantation. The patient had suffered from hypertension for 8 years. At the early stage of the disease, his symptoms were mild and the inflammatory indices increased and the lymphocyte count decreased continuously. The patient's condition exacerbated rapidly with multi-organ infections, and eventually developed pulmonary hemorrhage and consolidation, pulmonary hypertension, right heart failure, malignant ventricular arrhythmias, liver dysfunction, etc. His clinical manifestations could not be improved despite viral RNAs test results became negative. The patient underwent lung and heart transplantation and finally died of multi organ failure at the second day post lung and heart transplantation. Pathological examination indicated massive mucus, dark red secretions and blood clots in bronchus. The pathological changes were mainly diffused pulmonary hemorrhagic injuries and necrosis, fibrosis, small vessel disease with cardiac edema and lymphocyte infiltration. Conclusions: The clinical course of severe COVID-19 can exacerbate rapidly from mild to critical with lung, liver and heart injuries.

[Effects of sleeve gastrectomy base on "membrane anatomy" concept on postoperative nausea and vomiting in patients with obesity or metabolic diseases]

Objective: To explore the effects of the application of membrane anatomy concept in sleeve gastrectomy on postoperative nausea and vomiting (PONV) in patients with obesity or metabolic diseases. Methods: A retrospective cohort study was conducted. Clinical data of 88 patients with obesity or metabolic diseases who underwent laparoscopic sleeve gastrectomy in The First Affiliated Hospital of Jinan University from September 2018 to June 2019 were retrospectively analyzed. Forty patients underwent sleeve gastrectomy with membrane anatomy concept as membrane anatomy group, and the other 48 patients underwent traditional sleeve gastrectomy as traditional operation group. There were no significant differences in baseline data between the two groups (all P>0.05). The PONV score of and the times of antiemetic drugs used during 0-6 h and 6-24 h after operation were compared between the two groups. Higher PONV represents more serious nause and vomiting, the score ≥5 is defined as clinical significant PONV. Results: All patients of the two groups successfully completed the operation, and there was no conversion to open, reoperation, and operation-related death. The intraoperative blood loss in the membrane anatomy group was significantly less than that in the traditional surgery group [median: 5.0 (5.0, 5.8) ml vs. 10.0 (5.0, 10.0) ml, Z=-3.265, P=0.001]. There were no significant differences between the two groups in terms of operative time, postoperative hospital stay, gastroesophageal reflux, pain score and postoperative complications (all P>0.05). There was no postoperative bleeding or gastric leakage in either groups. There were no significant differences in PONV score, incidence of clinically significant PONV and use of antiemetics 0-6 h after operation between two groups (all P>0.05). From 6 to 24 hours after operation, compared with traditional surgery group, the membrane anatomy group had lower PONV score (4.6±0.9 vs. 5.1±0.7, t=-2.192, P=0.007), lower incidence of clinically significant PONV [55.0% (22/40) vs. 83.3% (40/48), χ(2)=8.414, P=0.004] and less use of antiemetics [3 times: 10.0% (4/40) vs. 27.1% (13/48), Z=-2.880, P=0.004]. Postoperative follow-up ranged from 1 to 6 months (median 3), 32 cases in membranous anatomy group and 38 cases in the traditional operation group were followed up. One case in the traditional operation group received symptomatic treatment in the local hospital due to functional intestinal obstruction 1 month after surgery and was discharged after recovery. The remaining patients had no postoperative complications and were not readmitted to hospital. Conclusion: Sleeve gastrectomy based on membrane anatomy in the treatment of patients with obesity or metabolic syndrome can make surgical procedure more precise and meticulous, reduce the intraoperative bleeding and the incidence of PONV.

Linear growth model analysis of factors affecting boar semen characteristics in Southern China

This study investigated the factors affecting the semen traits of boars in Southern China. A total of 172,408 ejaculates of boars from 9 AI centers were collected from January 2013 to May 2016. A linear growth model was used to analyze the effects of leve1 1 (boar breed, age, season, and boar age at herd entry) and level 2 (housing type) factors on semen quality. The intraclass correlation coefficients of semen volume, total sperm number, functional sperm number, sperm concentration, motility, and abnormal sperm were 0.62, 0.62, 0.61, 0.60, 0.54, and 0.70, respectively. Boars reared in ordinary houses had lower total and functional sperm numbers than those reared in air filtration houses ( < 0.05). The functional sperm number of Duroc boars was lower than that of Landrace and Yorkshire boars ( < 0.05). The total and functional sperm numbers were lowest from May to September and peaked at the age of 34.1 and 37.7 mo, respectively. Furthermore, boars aged 8 and 9 mo at herd entry had greater functional sperm numbers than those aged 5, 6, 7, and 12 mo at herd entry ( < 0.05), whereas no significant difference was observed between boars aged 8 mo and boars aged 9 mo at herd entry ( > 0.05). In conclusion, the linear growth model is suitable for longitudinal data analysis. To improve boar breeding, sunstroke prevention in the early spring should be given greater attention. Importantly, 8 mo appears to be the most suitable age for boar introduction, especially for Duroc boars.

Antiferromagnetic Order in Epitaxial FeSe Films on SrTiO_{3}

Single monolayer FeSe film grown on a Nb-doped SrTiO_{3}(001) substrate shows the highest superconducting transition temperature (T_{C}∼100  K) among the iron-based superconductors (iron pnictides), while the T_{C} value of bulk FeSe is only ∼8  K. Although bulk FeSe does not show antiferromagnetic order, calculations suggest that the parent FeSe/SrTiO_{3} films are antiferromagnetic. Experimentally, because of a lack of a direct probe, the magnetic state of FeSe/SrTiO_{3} films remains mysterious. Here, we report direct evidence of antiferromagnetic order in the parent FeSe/SrTiO_{3} films by the magnetic exchange bias effect measurements. The magnetic blocking temperature is ∼140  K for a single monolayer film. The antiferromagnetic order disappears after electron doping.

Unidirectional Spin-Wave-Propagation-Induced Seebeck Voltage in a PEDOT:PSS/YIG Bilayer

We clarify the physical origin of the dc voltage generation in a bilayer of a conducting polymer film and a micrometer-thick magnetic insulator Y_{3}Fe_{5}O_{12} (YIG) film under ferromagnetic resonance and/or spin wave excitation conditions. The previous attributed mechanism, the inverse spin Hall effect in the polymer [Nat. Mater. 12, 622 (2013)NMAACR1476-112210.1038/nmat3634], is excluded by two control experiments. We find an in-plane temperature gradient in YIG which has the same angular dependence with the generated voltage. Both vanish when the YIG thickness is reduced to a few nanometers. Thus, we argue that the dc voltage is governed by the Seebeck effect in the polymer, where the temperature gradient is created by the nonreciprocal magnetostatic surface spin wave propagation in YIG.

Effects of feeding regimen on weight gain, semen characteristics, libido, and lameness in 170- to 250-kilogram Duroc boars

A 2-period field trial was conducted to determine the effects of feeding regimen on weight gain, semen characteristics, libido, and lameness in 170- to 200-kg (period 1) and 200- to 250-kg (period 2) boars. Sixty-one Duroc boars were allotted to 1 of 3 dietary treatments and 15 g/d fish oil was also provided for each experimental boar, to maintain the n-6:n-3 intake ratio at approximately 6.1:1. The energy intakes of the 3 treatment groups were controlled by basing the feed intake on a corn-soybean meal-based diet (3.11 Mcal/kg of ME) to create: 1) low energy intake group (L, = 20, 7.3 Mcal/d of ME), 2) medium energy intake group (M, = 20, 7.7 Mcal/d of ME), and 3) high energy intake group (H, = 21, 8.3 Mcal/d of ME) in period 1. Feed intake was then increased to 7.6, 8.2, and 8.6 Mcal/d of ME for the 3 groups, respectively, in period 2. During the 28-wk experimental period, boar weight gain, testis volume, semen characteristics, libido, toe measurements, claw lesions, and lameness were examined, and the number of boars culled in each group was recorded to calculate the culling rate. Although there were no differences in testis volume, sperm concentration, and motility, the percentage of abnormal sperm, the percentage of claw lesions, and claw lesion scores differed among treatments ( > 0.05), and ADG was significantly increased with the increase of energy intake between the 2 periods ( < 0.05). The M and H boars had significantly greater total sperm number and functional sperm number than the L boars ( < 0.05), while no significant difference was observed between the M and H groups ( > 0.05). Nonetheless, the H boars took more time to mount the collection dummy and produce an ejaculate and, in particular, showed a greater percentage of lameness than the L and M boars ( < 0.05). Therefore, the medium energy intake regimen (energy intakes of 7.7 and 8.2 Mcal/d of ME with ADG of 454.5 and 375.3 g/d in 2 periods, respectively) improved the total sperm number and functional sperm number, and meanwhile decreased the occurrence of lameness in 170- to 250-kg Duroc boars.

Exchange-Dominated Pure Spin Current Transport in Alq3 Molecules

We address the controversy over the spin transport mechanism in Alq3 utilizing spin pumping in the Y3Fe5O12/Alq3/Pd system. An unusual angular dependence of the inverse spin Hall effect is found. It, however, disappears when the microwave magnetic field is fully in the sample plane, excluding the presence of the Hanle effect. Together with the quantitative temperature-dependent measurements, these results provide compelling evidence that the pure spin current transport in Alq3 is dominated by the exchange-mediated mechanism.

Resistant mutants induced by adefovir dipivoxil in hepatitis B virus isolates

AIM: To investigate the loci of adefovir dipivoxil (ADV)-induced resistance in hepatitis B virus (HBV) isolates and optimize the management of ADV-treated patients.

METHODS: Between June 2008 and August 2010, a cross-sectional control study was conducted comprising 79 patients with chronic HBV infection-related liver disease who had been administered ADV monotherapy. Patients underwent liver imaging. Serum DNA extracts were analyzed for HBV DNA levels, genotypes, and serology markers, and deep sequencing of the HBV P gene was performed.

RESULTS: ADV-resistant patients were found either with a single mutated locus, or with coexisting mutated loci. The most prevalent mutations were rtA181T, rtV214A, and rtN236T. Twenty-six patients had more than two mutated loci. The mutants were distributed among the patients without any significant affinity for gender, age, end-stage of liver disease, complications of non-alcoholic fatty liver disease, or HBV DNA levels. Patients with the rtA181T mutant were primarily infected with genotype C and e-antigen negative HBV, while patients with the rtN236T mutant were primarily infected by genotype B HBV (χ² = 6.004, 7.159; P = 0.023, 0.007). The duration of treatment with ADV was shorter in the single mutant group compared with the multi-mutant group (t = 2.426, P = 0.018).

CONCLUSION: Drug-resistant HBV mutants are complex and diverse. Patients should receive the standard and first-line antiviral treatment, strictly comply with medication dosage, and avoid short-term withdrawal.

Horizontal gene transfer does not occur between sFat-1 transgenic pigs and nontransgenic pigs

We previously generated and characterized synthesized fatty acid desaturase-1 (sFat-1) transgenic pigs that had increased concentrations of ω-3 unsaturated fatty acid in their meat. The objective was to assess whether the inserted foreign gene in sFat-1 transgenic pigs was able to transfer and integrate into the genome of nontransgenic pigs by suckling or mating. Tests for suckling-mediated horizontal gene transfer (HGT) included sFat-1 transgenic sows nursing nontransgenic piglets and sFat-1 transgenic piglets suckling nontransgenic sows. Tests for mating-mediated HGT were performed by male sFat-1 transgenic pigs mated with nontransgenic females and female sFat-1 transgenic pigs mated with nontransgenic males. Polymerase chain reaction was used to detect the sFat-1 gene fragment in various tissues sampled from nontransgenic pigs. The foreign target gene sFat-1 was not detected in the genomic DNA of various tissues and organs sampled from nontransgenic pigs. Therefore, we concluded that HGT from transgenic pigs to wild type pigs via suckling or mating was unlikely.

Acute hepatitis C infection with unclear route of transmission

A 43-year old man acquired acute hepatitis C virus (HCV) infection with unclear route of transmission. There were no known sexual or other risk factors for HCV acquisition. Phylogenetic analysis confirmed that the case was infected with identical genotype 1b strain. After symptomatic treatment for three weeks, the HCV was spontaneously cleared and liver function recovered.

MyoD control of SKIP expression during pig skeletal muscle development

Skeletal muscle and kidney enriched inositol phosphatase (SKIP) was identified as a 5'-inositol phosphatase that hydrolyzes PI(3,4,5)P3 to PI(3,4)P2 that negatively regulates insulin-induced phosphatidylinositol 3-kinase signaling in skeletal muscle. In this study, we obtained a 1575-bp mRNA sequence of porcine SKIP that included the full coding region encoding a protein of 450 amino acids. With the use of comparative mapping, we mapped this gene to SSC12 q1.3, where many QTLs affect Backfat thickness at 10th rib, carcass yield, the number of muscle fibers, and ham weight traits. As a candidate gene for growth and carcass traits, a novel single nucleotide polymorphism in exon 12 (G>A) was detected by PCR-RFLP. The results showed that the GG genotype had higher skin percentage (SP), carcass length to first spondyle (CL1), carcass length to first rib (CL2), but lower intramuscular fat (IMF) as compared with genotype AG (P<0.05), and allele G seemed to be associated with an increase in the growth trait. Porcine SKIP was expressed abundantly in skeletal muscle tissue and was transcriptionally upregulated during skeletal muscle differentiation. Analysis of the porcine SKIP promoter sequence demonstrated that MyoD was involved in regulating SKIP mRNA expression in myotubes, partly via the cis-acting elements in SKIP promoter. In summary, we suggested that SKIP might play a role in the regulation of skeletal muscle development in pigs.

Evidence for a new allele at the SERCA1 locus affecting pork meat quality in part through the imbalance of Ca2+ homeostasis

Sarcoendoplasmic reticulum Ca2+-ATPase 1 (SERCA1) as a Ca2+ release channel plays a key role in the relaxation of skeletal muscle through pumping cytosolic Ca2+ into the SR (sarcoplasmic reticulum). In this study, a novel single nucleotide polymorphism (SNP) in exon 8 (C > T) was detected by tetra-primer ARMS-PCR and the tissue expression pattern of SERCA1 was analyzed in eleven tissues. A model of primary skeletal muscle cells in vitro exposed to dexamethasone (DEX, a synthetic corticosteroid) was also employed to determine whether stress hormones cause an increase in intracellular Ca2+ concentration that is associated with alteration in SERCA1 and in turn subsequently affect meat quality. The results showed that the CC genotype has lower content intramuscular fat and higher water than pig carrying the genotype CT and CC. In addition, the additive effects were both significantly (P < 0.05) and allele T seemed to be associate with increase in intramuscular fat, while decrease in water content. Accompanied with previous studies, the high abundance of porcine SERCA1 was found in skeletal muscle tissue. DEX markedly down-regulated the expression of SERCA1, leading to Ca2+ overload. Furthermore, the imbalance of Ca2+ homeostasis up-regulated the transcription level of Calpain1. Taken together, we demonstrated a novel mechanism that the changes in expression of SERCA1 potential disturb the normal Ca2+ channel as well as the balance of Ca2+ homeostasis and which in turn finally activated Ca2+-dependent proteases such as Calpain1 which could affect meat quality.

Molecular characterization and SNPs analysis of the porcine Deleted in AZoospermia Like (pDAZL) gene

The Deleted in AZoospermia Like (DAZL) gene is expressed in prenatal and postnatal germ cells. In this study, we cloned and characterized the porcine Deleted in AZoospermia Like (pDAZL) gene. We found the full-length coding sequence of the pDAZL encoded a protein of 295 amino acids with a RNA recognition motif (amino acids 41-111) and a DAZ repeat (amino acids 167-120). The deduced protein sequence of pDAZL is 92.5% and 91.5% similar to those of human and bovine, respectively. PCR-MspI-RFLP and PCR-TaqI-RFLP were established to detect an A/G mutation in intron 7 and a C/A mutation in intron 9, respectively. Associations of two SNPs with litter size traits were assessed in Large White (n=275) and DIV (n=128) pig populations, and the statistical analysis demonstrated that CC produced 0.716 more (P<0.05) piglets born alive than CD genotypes in Large White pigs at TaqI locus (C/A mutation in intron 9), and the dominance effect was 0.304 pig per litter (P<0.05). This result suggests that the pDAZL gene might be a good candidate gene of litter size trait and provides some marker information for marker-assisted selection (MAS).

Molecular analysis of dispersal in giant pandas

Although dispersal in the giant panda (Ailuropoda melanoleuca) is a demographic mechanism which can potentially counteract the negative effect of habitat fragmentation, little is known about dispersal in this species because of difficulties in observing individuals. Using data from faecal microsatellite genotyping, we compared the spatial distribution of giant pandas in two populations and the proximity of relatives in one key population to infer their dispersal pattern. We conclude that giant pandas exhibit female-biased dispersal because: (i) vAIc (variance of assignment index) for females was significantly larger than for males, suggesting that females comprise both 'local' and 'foreign' genotypes; (ii) the average spatial distance of related female dyads was significantly larger than that of males; (iii) larger r (relatedness), F(ST) (genetic variance among populations) and mAIc (mean of assignment index) values were found in males using the software FSTAT, although the differences were not significant; (iv) males set up territories neighbouring to their birth place; (v) significant population structure using microsatellites with a concomitant lack of mitochondrial structure was found in a previous study, possibly indicating more extensive female dispersal; and (vi) female-biased dispersal was strongly supported by evidence from concomitant ecological studies. Considering previous ecological data and life-history characteristics of the giant panda, female-biased dispersal is most likely to be due to competition for birth dens among females, inbreeding avoidance and enhancing inclusive fitness among related males.

Identification of a differential gene HUMMLC2B between F1 hybrids Landrace x Yorkshire and their female parents Yorkshire

In order to investigate heterosis on a molecular basis, suppression subtractive hybridization was used to analyze the differences in gene expression between porcine F1 hybrids Landrace x Yorkshire and their female parents Yorkshire. From two specific subtractive cDNA libraries, the clones screened out by reverse Northern high-density blots screening were chosen to clone full-length cDNA by RACE. An expression-upregulated gene for Yorkshire skeletal muscle, designated as HUMMLC2B, was identified. Porcine HUMMLC2B contains an open reading frame (ORF) encoding 169 amino acids residues with 59 and 115 nucleotides in the 5' and 3' untranslated regions (UTRs), respectively. In the porcine genome, it contains seven exons separated by six introns. High allelic variations and four SINEs were detected in it. Comparison of derived amino acid sequence of HUMMLC2B with database sequences revealed highly conserved 12 amino acid residues in a putative calcium-binding region. RT-PCR analysis showed a tissue-specific pattern of expression in skeletal muscle and a similar level of expression during skeletal muscle development. The possible role of HUMMLC2B and its relation to porcine heterosis are discussed.

Polymorphism, linkage mapping and expression pattern of the porcine skeletal muscle glycogen synthase (GYS1) gene

The glycogen synthase gene (GYS1), which encodes the rate-limiting enzyme for glycogen synthesis of skeletal muscle, is a promising candidate gene for traits related to skeletal muscle in pigs. In this study, a G/A single nucleotide polymorphism in GYS1 intron 7 detected as a FokI PCR-restriction fragment length polymorphism (PCR-RFLP) showed allele frequency differences among five Chinese indigenous pig breeds and three western commercial pig breeds. Linkage analysis assigned the gene GYS1 to marker interval SW1302-SW1473 on SSC6 in a three-generation Meishan X Large White reference family. The results of association analysis and interval mapping suggested that the FokI PCR-RFLP polymorphism might be linked with the quantitative trait loci affecting carcass traits detected on SSC6 in the F2 intercross pedigree. The reverse transcriptase-polymerase chain reaction revealed that the porcine GYS1 gene was expressed in spleen, lung, liver, kidney, small intestine, skeletal muscle, heart and stomach, with the highest expression in skeletal muscle.

cDNA cloning, genomic structure and polymorphism of the porcine FHL3 gene

LIM domain proteins are important regulators of the growth, determination and differentiation of cells. Four-and-a-half LIM-only protein 3 (FHL3) is a type of LIM-only protein that contains four tandemly repeated LIM motifs with an N-terminal single zinc finger (half LIM motif). In this study, we have determined the complete coding sequence of pig FHL3 which encodes a 280 amino acid protein. The coding region of the pig FHL3 gene is organized in five exons and spans an approximately 2.1-kb genomic region. Comparative sequencing of six pig breeds revealed three single nucleotide polymorphisms (SNPs) within exon 2 of which an A-->G substitution at position 313 changes a codon for arginine into a codon for glycine. The substitution was situated within a PstI recognition site and developed as a PCR-RFLP marker for further use in population variation investigations and association analysis. The A/G polymorphism was segregating only in Landrace pigs. Association studies of the FHL3 polymorphism with carcass traits provided preliminary evidence that the PstI PCR-restriction fragment length polymorphism (RFLP) genotype may be associated with variation in several carcass traits of interest for pig breeding. Further investigations in more Landrace pigs are needed to confirm this.

Molecular phylogenetics relationship between six Chinese native pig breeds and three Swedish pig breeds from mitochondrial DNA

Mitochondrial DNA genetic polymorphisms were used to evaluate the relationship between 6 Chinese indigenous pig breeds and 3 Swedish domestic pig breeds. A total of 440 bp of the control region and 798 bp of cytochrome b (cyt b) gene of mtDNA were determined from 140 pigs of 9 different breeds. The results of phylogenetics analysis showed that 6 Chinese native pig breeds originated from the Asian wild boar. The pairwise nucleotide sequences divergence suggested that they might occur about 413,000-875,000 years before present (YBP) between Chinese native pig breeds and European wild boar, and approximately 7,500-15,600 YBP between Chinese native pig breeds and Asian wild boar. Three Swedish pig breeds are present both European clade and Asian clade, which is due to the documented introgression of Chinese pig breeds into European domestic pig breeds 2 thousand years ago or during early 18th century.

[An investigation of the bio-tribological performance of diamond-like carbon/ultrahigh molecular weight polyethylene couple]

OBJECTIVE

To evaluate the friction property of diamond-like carbon (DLC) film/Ti6Al4V gradient material sliding against UHMWPE couple.

METHOD

Tests of this couple were made under dry sliding and lubrication of Hank's solution and 0.9% NaCl solution respectively, and they were compared with the friction property of Ti6Al4V sliding against UHMWPE couple. The tests were performed on an SRV friction and wear tester by means of surface-contact and coefficients of friction were recorded real-time.

RESULT

DLC film could reduce the friction coefficient evidently. The coefficients of friction reduced 24%, 5.0%, 10% than these of Ti6Al4V under dry sliding and lubrication of Hank's solution and 0.9% NaCl solution respectively. Mechanism of friction was also studied by observing scanning electrical microscopy (SEM) morphology of frictional surfaces.

CONCLUSION

Friction-reduction mechanism of DLC film/Ti6Al4V could be resulted from amorphous structure of DLC film which was smooth and hard.

DNA binding of TEA/ATTS domain factors is regulated by protein kinase C phosphorylation in human choriocarcinoma cells

Transcription enhancer factor 1 (TEF-1) controls the expression of a diverse set of genes. Previous studies implicated protein kinase C (PKC)-mediated signal transduction in modulating TEF function. We demonstrate that in human choriocarcinoma BeWo cells, the PKC activator 12-O-tetradecanoyl phorbol 13-acetate and PKC inhibitor bisindolylmaleimide reciprocally down- and up-regulate, respectively, TEF-mediated GGAATG core enhancer activity. In vitro TEF-1 phosphorylation with several PKC isozymes and phosphoamino acid analysis confirmed that TEF-1 is a potential PKC substrate. TEF-1.DNA complexes formed by BeWo nuclear extracts are supershifted by phosphoserine- and phosphothreonine- but not phosphotyrosine-specific antibodies, indicating that TEF-1 is phosphorylated in vivo at serine and threonine residues. The TEF-1 phosphorylation domain was localized to the third alpha-helix of the DNA binding domain and adjacent hinge region by phosphopeptide analysis. TEF-1 phosphorylation significantly reduced its DNA binding activity both in vitro and in vivo, providing a possible mechanism for the inhibitory action of PKC. Finally, BeWo cells contained abundant levels of gamma and delta PKC isoforms, and their overexpression resulted in even greater inhibition of GGAATG core enhancer activity after 12-O-tetradecanoyl phorbol 13-acetate treatment. These data strongly suggest that PKC-mediated phosphorylation is a key factor controlling TEF function.

[Polymorphism of porcine hormone sensitive lipase gene and sequencing the partial DNA fragments]

Hormone sensitive lipase (HSL) is a key enzyme in fat metabolism. The polymorphism of the pig HSL gene is studied in this paper. The SSCP (Single Strand Conformational Polymorphism) is found in the HSL gene Exon 8. It shows three genotypes (MM, MN, NN). Fat-type pig breeds of Meishan and Tongcheng pigs have more allele M, with frequencies of 0.690 M and 0.740 M, respectively; however, lean-type pig breeds of Landrace and the Large White pigs have more allele N, with frequencies of 0.847 N and 0.845 N, respectively. PCR fragments representing HSL genotypes MM and NN are sequenced. Two A-->G transitions are detected, and it resulted in corresponding changes of amino acid (Asn-->Asp and Glu-->Gly) in the HSL protein, respectively. The HSL gene can be considered as a candidate gene for fatness in pigs.

Induction of the BRCA2 promoter by nuclear factor-kappa B

BRCA2 is a tumor suppressor gene that has been implicated in response to DNA damage, cell cycle control, and transcription. BRCA2 has been found to be overexpressed in many breast tumors, suggesting that altered expression of the BRCA2 gene may contribute to breast tumorigenesis. To determine how BRCA2 is overexpressed in tumors, we investigated the transcriptional regulation of the BRCA2 promoter. Deletion mapping of the BRCA2 promoter identified three regions associated with 3-fold activation or repression and one upstream stimulatory factor binding site associated with 20-fold activation. Gel shift and cotransfection studies verified the role of USF in regulation of BRCA2 transcription. Analysis of the -144 to -59 region associated with 3-fold activation identified a putative NFkappaB binding site. Cotransfection of the p65 and p50 subunits of NFkappaB up-regulated the BRCA2 promoter 16-fold in a luciferase reporter assay, whereas mutations in the binding site ablated the effect. Gel shift and supershift assays with anti-p65 and -p50 antibodies demonstrated that NFkappaB binds specifically to the NFkappaB site. In addition, ectopic expression of NFkappaB resulted in increased levels of endogeneous BRCA2 expression. Thus, NFkappaB and USF regulate BRCA2 expression through the BRCA2 promoter.

Cooperative binding of TEF-1 to repeated GGAATG-related consensus elements with restricted spatial separation and orientation

The human transcriptional enhancer factor (TEF) family includes TEF-1, TEF-3, TEF-4, and TEF-5. The TEFs share a highly conserved 68-amino acid TEA/ATTS DNA-binding domain, which binds to SV40 GT-IIC (GGAATG), SphI (AGTATG), SphII (AGCATG), and muscle-specific M-CAT (GGTATG) enhansons. We determined the optimal DNA-binding consensus sequence for TEF-1. Using a purified GST-TEF-1 fusion protein and a random pool of synthetic oligonucleotides, 31 independent clones were obtained after six rounds of binding site selection. DNA sequences analysis revealed that 16 clones contained direct repeats with a 3-bp spacer (DR3), and 15 clones contained a single binding site. The predominate consensus half-site was GGAATG (67%), and the other elements were of the form G(A)GA(T/C)ATG. The TEF-1 bound to the DR3 as a dimer in a cooperative manner. Cooperative binding was dependent on the spacing and orientation of the half-sites and was inhibited by deoxycholate treatment, providing evidence that protein-protein interactions were involved. The data suggest that TEF dimerization is important for its ability to modulate gene transcription.

Novel human TEF-1 isoforms exhibit altered DNA binding and functional properties

The transcriptional enhancer factor-1 (TEF-1) is a member of the TEA/ATTS domain family. TEF-1 binds to GT-IIC (GGAATG), SphI (AGTATG), SphII (AGCATG), and M-CAT (GGTATG) response elements and is involved in the transactivation of a variety of genes, including the SV40 large T antigen, mammalian muscle-specific genes, and human chorionic somatomammotropin genes. Also, TEF-1 acts as a transcriptional repressor in placental cells, possibly through interaction with the TATA binding protein (TBP), preventing TBP binding to the TATA box. Here we describe the cloning, tissue-specific expression pattern, and functional characterization of two novel TEF-1 isoforms, TEF-1beta and TEF-1gamma. These isoforms most likely arise from alternative splicing of mRNA transcribed from a single gene and involve substitutions and/or insertions in a region immediately following the DNA binding domain. TEF-1beta appears to be widely distributed like the prototypic TEF-1, designated TEF-1alpha, whereas TEF-1gamma exhibits a narrower tissue-specific expression pattern that includes pancreas, kidney, and skeletal and heart muscle. The relatively limited sequence alterations among these isoforms cause significant changes in their DNA binding and transcriptional activities. TEF-1beta and TEF-1gamma bind to GT-IIC sequences with higher affinity and repress hCS promoter more efficiently than TEF-1alpha. These results suggest that each TEF-1 isoform may play unique regulatory roles in various tissues.

Human placental TEF-5 transactivates the human chorionic somatomammotropin gene enhancer

Human chorionic somatomammotropin (hCS) gene expression in the placenta is controlled by an enhancer (CSEn) containing SV40-related GT-IIC and SphI/SphII enhansons. These enhancers are controlled by members of the transcription enhancer factor-1 (TEF-1) family. Recently TEF-5, whose mRNA is abundant in placenta, was shown to bind cooperatively to a unique, tandemly repeated element in CSEn2, suggesting that TEF-5 regulates CSEn activity. However, expression of TEF-5 using a cDNA lacking the 5'-untranslated region and containing a modified translation initiation site was not accompanied by CSEn activation. Using nested, degenerate PCR primers corresponding to conserved TEF domains, several novel TEF-1-related cDNAs have been cloned from a human placental cDNA library. The open reading frame of one 3033-bp clone was identical to TEF-5 and contained 300- and 1423-bp 5'- and 3'-untranslated regions, respectively. The in vitro generated approximately 53-kDa TEF-5 polypeptide binds specifically to GT-IIC and SphI/SphII oligonucleotides. Overexpression of TEF-5 in BeWo cells using the intact 3033-bp cDNA transactivates the hCS and SV40 enhancers and artificial enhancers comprised of tandemly repeated GT-IIC enhansons, but not OCT enhansons. The data demonstrate that TEF-5 is a transactivator that is likely involved in the transactivation of CSEn enhancer function. Further, the data suggest that elements within the untranslated regions, initiation site, or both control TEF-5 expression in ways that influence its transactivation function.

Effects of in vivo adventitial expression of recombinant endothelial nitric oxide synthase gene in cerebral arteries

Nitric oxide (NO), synthesized from L-arginine by NO synthases (NOS), plays an essential role in the regulation of cerebrovascular tone. Adenoviral vectors have been widely used to transfer recombinant genes to different vascular beds. To determine whether the recombinant endothelial NOS (eNOS) gene can be delivered in vivo to the adventitia of cerebral arteries and functionally expressed, a replication-incompetent adenoviral vector encoding eNOS gene (AdCMVNOS) or beta-galactosidase reporter gene (AdCMVLacZ) was injected into canine cerebrospinal fluid (CSF) via the cisterna magna (final viral titer in CSF, 10(9) pfu/ml). Adventitial transgene expression was demonstrated 24 h later by beta-galactosidase histochemistry and quantification, eNOS immunohistochemistry, and Western blot analysis of recombinant eNOS. Electron microscopy immunogold labeling indicated that recombinant eNOS protein was expressed in adventitial fibroblasts. In AdCMVNOS-transduced arteries, basal cGMP production and bradykinin-induced relaxations were significantly augmented when compared with AdCMVLacZ-transduced vessels (P < 0.05). The increased receptor-mediated relaxations and cGMP production were inhibited by eNOS inhibitors. In addition, the increase in cGMP production was reversed in the absence of calcium, suggesting that the increased NO production did not result from inducible NOS expression. The present study demonstrates the successful in vivo transfer and functional expression of recombinant eNOS gene in large cerebral arteries. It also suggests that perivascular eNOS gene delivery via the CSF is a feasible approach that does not require interruption of cerebral blood flow.

Estrogen receptor expression and growth-promoting function in human choriocarcinoma cells

Tamoxifen (1.0 microM) was found to inhibit the expression of a thymidine kinase (TK) promoter-reporter gene, lacking an estrogen response element (ERE), in transiently transfected BeWo cells, suggesting that inhibition of TK promoter activity was linked to secondary estrogen-dependent effects on BeWo cell function. Estradiol (0.05-0.45 microM) stimulated BeWo cell proliferation and increased the percentage of S-phase cells. Tamoxifen (1.35-4.05 microM) inhibited BeWo cell growth and antagonized the stimulatory actions of 0.15 microM estradiol. Reverse transcription-polymerase chain reaction and Western analyses confirmed the presence of estrogen receptor (ER) transcripts and the 67-kD ER in BeWo cells. The BeWo cell ER binds to an ERE consensus sequence and the ER-ERE complex is supershifted by antibodies directed against the ER. We conclude that BeWo cells express a functional ER that is important for the control of BeWo cell proliferation, suggesting a potential role for estrogens in mediating placental trophoblast growth and development.

Human chorionic somatomammotropin enhancer function is mediated by cooperative binding of TEF-1 and CSEF-1 to multiple, low-affinity binding sites

The human chorionic somatomammotropin gene enhancer (CSEn) is composed of multiple enhansons (Enh) that share sequence similarities with those of the simian virus, SV40 enhancer (SVEn). The sequence homology includes two GT-IIC-like (Enh1 and Enh4) and three SphI/II-like enhansons (Enh2, Enh3, and Enh5). We previously showed that transcription enhancer factor 1 (TEF-1) and a 30-kDa placental-specific factor, chorionic somatomammotropin enhancer factor 1 (CSEF-1), bind to Enh4, which plays an essential role in enhancer function. In this study, we demonstrate that TEF-1 and CSEF-1 bind specifically to all the other GT-IIC- and SphI/II-like elements within CSEn with a broad range of binding affinities that vary between 0.005 and 0.15 that of Enh4. Each individual concatenated enhanson was able to stimulate hCS promoter activity in an orientation-independent manner in choriocarcinoma cells (BeWo) with an observed stimulation that was directly proportional to its relative binding affinity for TEF-1 and CSEF-1. These results indicate that CSEn function results from the cooperative interaction of TEF-1 and/or CSEF-1 binding to multiple, low-affinity GT-IIC- and SphI/II-like enhansons within the enhancer.

The human chorionic somatomammotropin enhancers form a composite silencer in pituitary cells in vitro

The human GH (GH) gene family includes the pituitary-specific hGH-1, placental-specific chorionic somatomammotropin (hCS-5, hCS-2, and hCS-1), and hGH-2 genes. These duplicated, nearly identical genes are localized on approximately 50 kb of DNA on chromosome 17q23-q24. An enhancer (CSEn2), located downstream of the hCS-2 gene, participates in mediating placental-specific hCS gene expression. In the preceding paper we demonstrated that CSEn2 activity derives from the cooperative binding of transcription factor-1, TEF-1, and a placental-specific factor CSEF-1 to multiple enhansons, Enh1-Enh5, that are related to the SV40 GT-IIC and SphI/SphII enhansons. Here we demonstrate that two copies of CSEn2 or a single copy of CSEn2 linked to either of the other two enhancers in the hGH/hCS locus, CSEn1 and CSEn5, act cooperatively to enhance hCS promoter activity in choriocarcinoma (BeWo) cells, but silence the promoter in pituitary GC cells. Mutation of Enh4, an essential GT-IIC-like enhanson in the context of the intact enhancer, abolishes silencer activity, and multimerized GT-IIC enhansons mimic the intact CSEn enhancer/silencer activities in BeWo and GC cells, respectively. By antibody-mediated supershift, Western, and far Western analyses, we identified TEF-1 as the GT-IIC-binding factor in pituitary cells. The data suggest that TEF-1 may be involved in pituitary-specific repression of placental GH/CS gene transcription through long-range interactions between the multiple CS enhancers present on the GH/CS gene locus.

An efficient method for generation and subcloning of tandemly repeated DNA sequences with defined length, orientation and spacing

Tandemly repeated DNA sequences generated from single synthetic oligonucleotide monomers are useful for many purposes. With conventional ligation procedures low yields and random orientation of oligomers makes cloning of defined repeated sequences difficult. We solved these problems using 2 bp overhangs to direct orientation and random incorporation of linkers containing restriction sites during ligation. Ligation products are amplified by PCR using the linker oligonucleotides as primers. Restriction digestion of the PCR products generate multimer distributions whose length is controlled by the monomer/linker ratio. The concatenated DNA fragments of defined length, orientation and spacing can be directly used for subcloning or other applications without further treatment.

TEF-1 transrepression in BeWo cells is mediated through interactions with the TATA-binding protein, TBP

Transcription enhancer factor-1 (TEF-1) has been implicated in transactivating a placental enhancer (CSEn) that regulates human chorionic somatomammotropin (hCS) gene activity. We demonstrated that TEF-1 represses hCS promoter activity in choriocarcinoma (BeWo) cells (Jiang, S.W., and Eberhardt, N.L. (1995) J. Biol. Chem. 270, 13609-13915), suggesting that TEF-1 interacts with basal transcription factors. Here we demonstrate that hTEF-1 overexpression inhibits minimal hCS promoters containing TATA and/or initiator elements, Rous sarcoma virus and thymidine kinase promoters in BeWo cells. Cotransfection of TEF-1 antisense oligonucleotides alleviated exogenous TEF-1-mediated repression and increased basal hCS promoter activity, indicating that endogenous TEF-1 exerts repressor activity. GST-TEF-1 fusion peptides fixed to glutathione-Sepharose beads retained in vitro-generated human TATA-binding protein, hTBP. The TEF-1 proline-rich domain was essential for TBP binding, but polypeptides also containing the zinc finger domain bound TBP with higher apparent affinity. TBP supershifted hTEF-GT-IIC DNA complexes, but TEF-1 inhibited in vitro binding of TBP to the TATA motif. Coexpression of TBP and TEF-1 in BeWo cells alleviated TEF-1-mediated transrepression, indicating that the TBP-TEF-1 interaction is functional in vivo. The data indicate that TEF-1 transrepression is mediated by direct interactions with TBP, possibly by inhibiting preinitiation complex formation.

A micro-scale method to isolate DNA-binding proteins suitable for quantitative comparison of expression levels from transfected cells

Images

Involvement of a protein distinct from transcription enhancer factor-1 (TEF-1) in mediating human chorionic somatomammotropin gene enhancer function through the GT-IIC enhanson in choriocarcinoma and COS cells

Previous studies suggested that transcription enhancer factor-1 (TEF-1) was involved in mediating the human chorionic somatomammotropin (hCS) gene enhancer (CSEn) function (Jiang, S.-W., and Eberhardt, N. L. (1994) J. Biol. Chem. 269, 10384-10392). We now show that an unrelated protein (CSEF-1) found in BeWo and COS-1 cells binds to the GT-IIC enhanson in CSEn and is correlated with CSEn activity in these cells. TEF-1 and CSEF-1 were distinguished by differential migration as GT-IIC complexes, thermal stability, molecular mass, and cross-reactivity with chicken TEF-1 antibodies. TEF-1 and CSEF-1 bound to the GT-IIC and Sph-I/Sph-II enhansons with identical binding properties, and in vitro generated TEF-1 competed with CSEF-1 binding to the GT-IIC motif, suggesting that their actions might be mutually exclusive. Up- and down-regulation of TEF-1 levels by expression systems and antisense oligonucleotides demonstrated that TEF-1 inhibited the hCS promoter in a manner independent of the enhancer or a known TEF-1 DNA binding site. The data suggest that TEF-1 may provide a counter-regulatory stimulus to the actions of CSEF-1, which may be involved in mediating enhancer stimulatory activity.

An initiator element is required for maximal human chorionic somatomammotropin gene promoter and enhancer function

Previous studies have indicated that cell-specific expression of the human chorionic somatomammotropin (hCS) gene may be mediated by a placental-specific enhancer (CSEn). In the current studies, we have analyzed the promoter elements that are required for enhancer and promoter function in choriocarcinoma cells (BeWo). Mutation of both hCS GHF1 sites had no effect on promoter or enhancer activity. In contrast, mutation of the Sp1 site diminished basal and CSEn-stimulated transcription by approximately 75% and approximately 56%, respectively, indicating that Sp1 was necessary but not sufficient for maximal basal and enhancer-mediated transcription. Deletion and site-specific mutation of the proximal promoter region indicated that the TATA box and an initiator site (InrE) located between nucleotides -15/+1 of the hCS promoter were required for maximal promoter and enhancer function. Mutations of the InrE were associated with reduced basal and enhancer-stimulated activities and altered transcription initiation sites. A protein of 70-kDa mass, that was preferentially expressed in human choriocarcinoma cells (BeWo and JEG-3), bound specifically to the InrE. The data suggest that an initiator present in high concentrations in placental cells contributes to the control of cell-specific hCS gene expression at the promoter level and is required for maximal enhancer function.

The human chorionic somatomammotropin gene enhancer is composed of multiple DNA elements that are homologous to several SV40 enhansons

Previous studies indicate that a human chorionic somatomammotropin (hCS) gene enhancer (CSEn) associated with the growth hormone (hGH) gene locus is involved in directing cell-specific expression of the hCS genes in placenta. In the current studies, we report a detailed structural analysis of this enhancer. CSEn stimulated transcription of a variety of promoters, including the hCS, human growth hormone, thymidine kinase, and Rous sarcoma virus promoters, in human choriocarcinoma cell lines (BeWo and JEG-3) but not HeLa cells or rat somatolactotrophes (GC). Maximal enhancer activity was confined to a 242-base pair DNA segment. Of several CSEn subfragments, only the En 57/242 subfragment retained activity (33.5% wild-type). The CSEn DNA sequence contained direct and inverted repeat motifs and sequences related to the SV40 enhansons, GT-IIC, GT-I, and SphI/SphII. DNase I footprint analysis revealed that most of these sites were protected by nuclear proteins derived from BeWo, JEG-3, HeLa, and GC cells. Site-specific block mutation of the GT-IIC-related and inverted repeat motifs virtually abolished enhancer activity, and mutation of all but the GT-I-related motif resulted in significant loss (30-60%) of activity. These data demonstrate that the CS enhancer is comprised of multiple elements related to SV40 enhansons that interact cooperatively to generate enhancer function.

[Effects of tumor promoting herb Wikstroemia chamaedaphne extract on V79 cells and WB liver cells: I. Correlation between cellular growth and gap junctional intercellular communication]

A Chinese herb, wikstroemia Chamaedaphen (WC) extract, recently has been shown to be a potential tumor promoting agent on uterine cervical carcinoma induced by HSV-2 or MCA in mice. To determine whether the tumor promoting effects of WC extract were mediated through inhibition of gap junctional intercellular communication (GJIC) with relation to cellular growth, experiments were conducted on Chinese hamster V79 cells and rat WB liver cells by utilization of SLDT method for GJIC detection and cell growth curve examination, 3H-TdR incorporation, mitotic index (MI) and Flow Cytometry (FCM) methods. TPA was used for comparative purpose. WC extract inhibited GJIC and stimulated cell growth in a dose (2-200 micrograms/ml) and time (0-72 hr)-dependent manner in both cell lines. Both WC extract and TPA treatments increased V79 cell growth rate. The average cell doubling-time was decreased from 36.5 hr in control V79 cells to 28.2 hr in WC extract (10 micrograms/ml) and 20.9 hr in TPA (50 ng/ml) treatment by the 3rd day. Stimulating effect of both drugs on DNA synthesis of V79 cells was demonstrated. The results of FCM and MI indicated that the cell number of M-phase cells was increased after drug treatment. It is suggested that (1) tumor promoting effect of WC extract might be mediated through inhibition of GJIC: (2) inhibition of GJIC is closely correlated with increased cell growth rate and entry of cell division cycle.