Investigating the Potential Mechanism of Pydiflumetofen Resistance in Sclerotinia sclerotiorum

The necrotrophic pathogen Sclerotinia sclerotiorum is one of the most damaging and economically important plant pathogens. Pydiflumetofen, which was developed by Syngenta Crop Protection, has already been registered in China for the management of Sclerotinia stem rot, which was caused by S. sclerotiorum in oilseed rape. In an attempt to preempt and forestall the development of resistance to this useful fungicide, the current study was initiated to investigate the potential mechanism of resistance in laboratory mutants. Five pydiflumetofen-resistant S. sclerotiorum mutants were successfully generated by repeated exposure to the fungicide under laboratory conditions. Although the mutants had greatly reduced sensitivity to pydiflumetofen, they were also found to have significantly (P < 0.05) reduced fitness, exhibiting reduced mycelial growth and sclerotia formation on potato dextrose agar medium. However, three of the four mutants had significantly (P < 0.05) increased pathogenicity on detached soybean leaves compared with their respective parental isolates, indicating a moderate to high level of fungicide resistance risk according to the criteria of the Fungicide Resistance Action Committee. Sequence analysis of four succinate dehydrogenase (Sdh) target genes identified several nucleotide changes in the sequences of the pydiflumetofen-resistant mutants, most of which were synonymous and caused no changes to the predicted amino acid sequences. However, all of the pydiflumetofen-resistant mutants had two amino acid point mutations (A11V and V162A) in their predicted SsSdhB sequence. No similar changes were found in the SsSdhA, SsSdhC, and SsSdhD genes of any of the mutants tested. In addition, there was a positive cross-resistance between pydiflumetofen and boscalid, and no cross-resistance between pydiflumetofen and other commonly used fungicides, including tebuconazole, fludioxonil, cyprodinil, dimethachlone, prochloraz, pyraclostrobin, fluazinam, procymidone, and carbendazim. These results indicate that pydiflumetofen has great potential as an alternative fungicide for the control of S. sclerotiorum, especially where resistance to other fungicides has already emerged. Mixing or alternate application with fludioxonil, prochloraz, and fluazinam could be used to limit the risk of resistance to pydiflumetofen.

Exploring the Biological and Molecular Characteristics of Resistance to Fludioxonil in Sclerotinia sclerotiorum From Soybean in China

Sclerotinia sclerotiorum is one of the most damaging and economically important necrotrophic plant pathogens, infecting more than 400 plant species globally. Although the phenylpyrrole fungicide fludioxonil has high activity against S. sclerotiorum, reports indicate that there is also substantial potential for the development of fungicide resistance. However, the current study investigating five fludioxonil-resistant laboratory mutants found a significant fitness cost associated with fludioxonil resistance resulting in significantly (P < 0.05) reduced mycelial growth and sclerotia formation on potato dextrose agar as well as significantly (P < 0.05) lower pathogenicity on detached tomato leaves, with one mutant, LK-1R, completely losing the capacity to cause infection. In addition, all of the fludioxonil-resistant mutants had significantly (P < 0.05) increased sensitivity to osmotic stress (0.5 M of potassium chloride and 1.0 M of glucose), which is consistent with the proposed fludioxonil target sites within the high osmolarity glycerol stress response mitogen-activated protein kinase (HOG1-MAPK) signaling transduction pathway. Sequence analysis of six genes from this two-component pathway, including SsHk, SsYpd, SsSk1, SsSk2, SsPbs, and SsHog, revealed several mutations that may be associated with fludioxonil resistance. For example, six separate point mutations were found in SsHk that led to changes in the predicted amino acid sequence, including A136G, F249V, G353A, E560K, M610K, and K727R. Similarly, SsPbs had three mutations (D34G, S46L, and L337E), SsSk1 and SsYpd had two (S53G and A795V for SsSk1, and E67G and Y141H for SsYpd), and SsHog and SsSk2 had one each (V220A and S763P, respectively). To our knowledge, these constitute the first reports of amino acid changes in proteins of the HOG1-MAPK pathway being associated with fludioxonil resistance in S. sclerotiorum. This study also showed a positive cross-resistance between fludioxonil and dimethachlone and procymidone, but none with tebuconazole or carbendazim, indicating that the inclusion of tebuconazole within an integrated pest management program could reduce the risk of fludioxonil resistance developing in field populations of S. sclerotiorum and ensure the sustainable production of soybeans in China into the future.

[Short-term effect of sodium zirconium cyclosilicate on potassium lowering in chronic kidney disease patients with hyperkalemia]

Objective: To investigate the efficacy of sodium zirconium cyclosilicate on emergency correction of hyperkalemia in chronic kidney disease patients. Methods: Patients with chronic kidney disease who were admitted to the Department of Nephrology of the First Affiliated Hospital of Zhengzhou University from May to June 2020 were selected. Those who had hyperkalemia and took sodium zirconium cyclosilicate powder were finally included. The patient's clinical data and laboratory results were collected. Results: A total of 24 results were included from 21 patients. The age of patients was (48.9±13.5) years old. Fourteen patients were male, and 7 patients were female. After 2 hours of administration, the venous potassium level decreased from (5.85±0.52) mmol/L to (5.15±0.43) mmol/L (P<0.001, n=21), with an average decline of (0.71±0.43) mmol/L. Meanwhile, the arterial potassium level decreased from (5.50±0.40) mmol/L to (4.88±0.33) mmol/L (P<0.001, n=10), with an average decline of (0.62±0.29) mmol/L. Based on the initial venous potassium level, the patients were further divided into three groups. The average potassium decrease in<5.5 mmol/L group (4 patients), 5.5-<6.0 mmol/L group (11 patients) and ≥6.0 mmol/L group (6 patients) was (0.46±0.26) mmol/L, (0.62±0.38) mmol/L and (1.04±0.45) mmol/L, respectively. There was statistically significant difference of potassium reduction among the three groups (P=0.045). Moreover, the extent of potassium reduction was positively correlated with baseline venous potassium level (r=0.603, P=0.004, n=21). The study did not reveal any treatment-related adverse event. Conclusion: Sodium zirconium cyclosilicate powder can rapidly and effectively reduce the serum potassium level in chronic kidney disease patients with hyperkalemia.

[Prediction of clinical outcomes of patients with surplus cleavage-stage embryos for blastocyst culture after D3 embryo transfer]

Objective: To find the best strategy of embryo transfer, so as to provide theoretical basis for improving the clinical outcomes of in vitro fertilization-Embryo transfer (IVF-ET), we investigate the blastocyst culture of surplus cleavage-stage embryos after D3 embryo transfer and the prediction of clinical outcomes with or without blastocyst formation. Methods: A retrospective study was conducted on 3 568 patients who underwent IVF-ET in the Reproductive Medicine Center of the First Affiliated Hospital of Zhengzhou University from January 2016 to May 2018, whotransplanted two embryos in D3 with blastocyst culture of surplus cleavage-stage embryos, according to their age, they were divided into three groups: <35 years old group, 35-38 years old group, and>38 years old group.And according to the presence or absence of blastocyst formation, they were also divided into two subgroups: blastocyst formation group and non-blastocyst formation group. The embryo development and clinical outcomes in each group were compared. Results: (1) Comparisons of the embryo development in the three age groups with the first cycle. The total fertilization rate, cleavage rate and high quality embryo rate of the blastocyst formation group in the three groups were higher than those in the non-blastocyst formation group, P<0.05; In<35 years old group, the embryo utilization rate (75.0% vs 70.6%), pregnancy rate (74.9% vs 70.3%), planting rate (53.6% vs 48.6%), delivery rate (66.7% vs 61.1%) and live birth rate (66.5% vs 61.0%) of the blastocyst formation group were higher than those in the non-blastocyst formation group, P<0.05. (2) Comparisons of embryo development in the three age groups with multiple cycles (≥2 cycles). In<35 years old group, the total fertilization rate (75.0% vs 70.6%),delivery rate (62.7% vs 43.8%) and live birth rate (62.7% vs 43.8%) of the blastocyst formation group were significantly higher than those in the non-blastocyst formation group, P<0.05; In>38 years old group, the pregnancy rate (56.3% vs 25.8%), implantation rate (34.4% vs 14.5%), delivery rate (43.8% vs 11.3%), live birth rate (43.8% vs 11.3%) of the blastocyst formation group were higher than those in the non-blastocyst formation group, P<0.05. Conclusions: The results of blastocyst culture in different groups can predict the outcomes of embryo transfer in D3. For patients<35 years old with the first cycle, the clinical outcomes of the blastocyst formation group after D3 embryo transfer is better than that of the non-blastocyst formation group. For Patients with multiple cycles (≥2 cycles),the clinical outcomes of the embryo formation group is superior to that of the non-blastocyst formation group<35 years old or>38 years old.

[Identification and analysis of the proteins interacted with Prestin in cochlear outer hair cells of guinea pig]

Objective: To explore the regulation and mechanism of Prestin protein by identifying the proteins interacted with Prestin in cochlear outer hair cell(OHC) and analyzing their biological function. Methods: Co-immunoprecipitation combined mass spectrometry technology was used to isolate and identify the proteins interacted with Prestin protein of OHC, bioinformatics was used to construct Prestin protein interaction network. The proteins interacted with Prestin in OHC of guinea pig were determined by matching primary interaction mass spectrometry with protein interaction network, and annotated their functions. Results: The results of co-immunoprecipitation combined with mass spectrometry showed that 116 kinds of credible proteins could interact with Prestin. By constructing Prestin protein interaction network, matching the results of mass spectrometry and analyzing of sub-cellular localization, eight kinds of proteins were confirmed that they interacted with Prestin directly, namely EEF2, HSP90AB1, FN1, FLNA, EEF1A1, HSP90B1, ATP5A1, and ERH, respectively, which were mainly involved in the synthesis and transportation, transmembrane folding and localization, structural stability and signal transduction of Prestin protein. Conclusion: EEF2, HSP90AB1, FN1, FLNA, EEF1A1, HSP90B1, ATP5A1 and ERH provide molecular basis for sensory amplification function of OHCs by participating in biotransformation, transmembrane folding and localization, signal transduction and other biological processes of Prestin protein.

[Chinese multicenter randomized trial of customized chemotherapy based on BRCA1 (breast cancer susceptibility gene 1)-RAP80 (receptor-associated protein 80) mRNA expression in advanced non-small cell lung cancer (NSCLC) patients]

Objective: BRCA1 (breast cancer susceptibility gene 1) and RAP80 (receptor-associated protein 80) play key roles in predicting chemosensitivity of platinum and taxanes. A randomized trial was carried out to compare non-selected cisplatin-based chemotherapy with therapy customized according to BRCA1 and RAP80 expression. Methods: Advanced stage NSCLC patients whose tumor specimen was sufficient for molecular analysis were randomized (1∶3) to the control or experimental arm. Patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin (Arm 1), those with intermediate/high RAP80 expression and low/intermediate BRCA1expression received docetaxel/cisplatin (Arm 2), and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone (Arm 3). The primary end point was progression-free survival (PFS). Results: 226 patients were screened and 124 were randomized in this trial. ORR in the four subgroups was 22.6%, 48.4%, 30.3% and 19.2%, respectively (P=0.08); PFS was 4.74, 5.59, 3.78 and 2.73 months, respectively (P=0.55); and OS was 10.82, 14.44, 10.86 and 10.86 months, respectively (P=0.84). The common adverse effects included neutropenia, nausea, anemia and fatigue. Conclusions: No statistically significant difference of ORR, PFS or OS is observed in the experimental arms compared with the control arm. Patients with low RAP80 mRNA levels have a trend of better survival and higher response rate to gemcitabine/cisplatin chemotherapy.

[Evaluation and analysis of the tibial coronal alignment after total knee replacement with the extramedullary tibial cutting guided by the tibial tubercle and anterior tibial tendon in Chinese patients]

OBJECTIVE

To evaluate the efficiency of the tibial coronal alignment after total knee arthroplasty with the extramedullary cutting system guided by the tibial tubercle and anterior tibial tendon, and to discuss the potential risk factors for the postoperative malalignment.

METHODS

A retrospective study of 212 primary unilateral TKA surgeries (in 188 patients) in our hospital between June to December in 2014 had been analysed. All the cases were performed by one surgical group. An extramedullary tibial cutting guide system had been used, with a landmark of one third inner-medial tibial tubercle as a proximal anatomy reference, and anterior tibial tendon as a distal marker. The mechanical axis of lower extremity in full-length X-ray was measured before surgery, and the tibial prosthetic coronal alignment was checked two weeks postoperation, evaluating the accuracy of this extramedullary cutting system guided by our method.

RESULTS

Since good alignment was defined as an angle within 3 degrees of the perpendicular to the mechanical axis, the tibial component positions were acceptable in 191 knees (90.1%), five knees were in valgus postoperative, and sixteen knees were in varus. There were seventeen(8.7%) in 179 knees with a preoperative varus presented malalignment after surgery, and four in 12 preoperative valgus kneess howed malalignment also, no statistical difference was found by Chi-square test(χ(2)=2.778,P=0.096), which cannot define the relationship between the varus or valgus deformity preoperation and the malalignmentposition in tibial prosthesis after surgery. Twenty-two knees suffered a severe preoperative deformity as a varus or valgus angle larger than 20 degrees with absolute value of mechanical axis before surgery and tibial prosthetic coronal alignment were 21.95 °(20.00°,26.90°)and 1.85°(0.10°, 7.10°), showed a significant difference (Z=2.11,P=0.035) compared with the data [10.65°(0.50°,19.80°)in preoperative mechanical axis and 1.10°(0.00°,4.60°)in the tibial prosthetic coronal alignment]of 190 knees who presented a mild deformity before surgery(less than 20 degrees), the result indicated the severe preoperative deformity might be a potential mal-alignment risk factor within this cutting system in TKA surgery.

CONCLUSION

The tibial coronal alignment after total knee arthroplasty could achieve good results with extramedullary cutting guide, by using one third inner-medial tibial tubercle and anterior tibial tendon as a proximal and distal anatomy marker. Postoperative varus might occur in this system, and tibial prosthetic malalignment appeared more often in the patients who suffered a severe deformity before surgery.

First Report of Powdery Mildew Caused by Erysiphe betae on Swiss Chard in China

Swiss chard (Beta vulgaris L. subsp. cicla) is a widely planted vegetable in China. From May to June 2013, an outbreak of powdery mildew on Swiss chard cultivar Fangzheng was observed in the commercial fields in Zhoukou city of Henan Province, located in central China. More than 80% of the plants exhibited symptoms of the disease. At the beginning of infection, circular, white, dust-like colonies of powdery mildew occurred mainly on adaxial surfaces of leaves. As the disease progressed, white mycelia covered the foliar parts of plant. No cleistothecia were found on or in collected samples. Upon microscopic evaluation, conidiophores were unbranched with the length of 63 to 126 and width of 7 to 10 μm (n = 50), produced conidia singly, and composed of a cylindrical foot cell followed by one to three short cells. Conidia were colorless, hyaline, ovoid, measured 29 to 40 × 12 to 18 μm (n = 100), lacked fibrosin bodies, and produced germ tubes on the ends of the conidia. The fungus was identified as Erysiphe betae according to the morphological features (1). To verify the identity, the internal transcribed spacer (ITS) region was amplified with the universal primers ITS1 and ITS4 (2) and sequenced. The ITS sequence obtained was assigned as Accession No. KF268348 in GenBank, which showed 100% homogeneity with two ITS sequences of E. betae isolates from UK (DQ164432 and DQ164436). Koch's postulates were conducted by inoculating 15 healthy 5-week-old plants (cv. Fangzheng) with detached infected leaves, which grew in a growth chamber under 22/16°C (day/night), 50% relative humidity, 120 μmol/m²/s light and a 16-h photoperiod. Fifteen non-inoculated plants grew in another growth chamber with the same conditions as control. Symptoms consistent with the infected field plants were observed on the inoculated plants, while no symptoms were found on the control plants. Microscopic observation revealed that the pathogen growing on the inoculated plants was consistent with the morphology of the original fungus. To our knowledge, this is the first report of E. betae infection on Swiss chard in China (3). References: (1) S. Francis. Mol. Plant Pathol. 3:119, 2002. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990. (3) R. Y. Zheng et al. Page 63 in: Flora Fungorum Sinicorum, Vol. 1, Erysiphales. Science Press, Beijing, 1987.

Loop-tail phenotype in heterozygous mice and neural tube defects in homozygous mice result from a nonsense mutation in the Vangl2 gene

N-ethyl-N-nitrosourea (ENU) is a powerful point mutagen that can generate random mutations. It has been used to generate mouse mutations to produce phenotypic models of human disease. Neural tube defects (NTD) are common birth defects in which the brain and/or spinal cord can be exposed; however, the mechanisms of these defects are poorly understood. Craniorachischisis is one type of NTD that bears a close resemblance to the phenotype of the loop-tail (Lp) mouse. Here we describe a C57BL/6J Lp mouse generated by ENU-induced mutagenesis. The mutation was mapped to the Vangl2 gene on chromosome 1, near markers D1Mit113 and D1Mit149. Sequence analysis of Vangl2 heterozygotes (Vangl2(m1Yzcm)/+) revealed a C/T transition mutation that resulted in substitution of a glutamine codon for a stop (nonsense) codon at position 449. The Vangl2 protein is involved in epithelium planar cell polarity. The predicted truncated protein would lack the PDZ-domain binding motif involved in protein-protein interaction; therefore, Vangl2(m1Yzcm) may be a loss-of-function mutant. Morphological and histological examination of homozygous mouse embryos revealed a neural tube closure defect that leads to craniorachischisis. This Vangl2(m1Yzcm) mouse represents a valuable model for the study of NTDs in humans.

The effects of the Chinese medicine ZiBu PiYin recipe on the hippocampus in a rat model of diabetes-associated cognitive decline: a proteomic analysis

AIMS/HYPOTHESIS

Increasing evidence suggests that diabetes is associated with an enhanced risk of cognitive decline. The precise mechanisms underlying diabetes-associated cognitive decline (DACD) remain unclear. Here we investigated the molecular changes associated with DACD using a comparative proteomics study of hippocampus in a rat model of type 2 diabetes. In addition, we tested the effects of the Chinese medicine ZiBu PiYin recipe (ZBPYR) on DACD.

METHODS

The hippocampus was dissected from control, diabetic and diabetic rats treated with ZBPYR (DM/ZBPYR). Soluble proteins were separated using fluorescence-based difference gel electrophoresis. Protein spots were visualised with fluorescent dyes and spot density was compared between each pair of groups. Proteins of interest were identified using mass spectrometry. Proteins of specific interest were also tested by western blot and real-time PCR analysis.

RESULTS

We found 13 spots that were altered between control and diabetes groups, and 12 spots that were changed between diabetes and DM/ZBPYR groups. The identities of nine proteins were determined by mass spectrometry. The identified proteins were largely involved in energy metabolism, cytoskeleton regulation and oxidative stress. The protein alterations observed in the diabetes group were ameliorated to varying degrees following ZBPYR treatment.

CONCLUSIONS/INTERPRETATION

The protein changes identified in hippocampus from a rat model of type 2 diabetes suggest that specific cellular alterations contribute to DACD. The Chinese medicine ZBPYR was found to affect multiple targets and partially repaired the original cellular balance. This study may provide important insights into the molecular events underlying DACD and allow the identification of novel therapeutic targets.

Blue Light Emission from Porous Silicon

Through a post treatment of light emitting porous silicon in boilingwater, a large blue shift of its photoluminescence (PL) spectrum hasbeen observed and a stable blue-green light emission at the peak wavelength down to 500 nm is achieved. The effect of boiling water treatment is suggested to be a kind of oxidation, which could reduce thesize of the Si column, fill up some micropores and strengthen the Siskeleton. The photoluminescence microscopic observation shows that the surface of blue light emitting porous silicon is composed of manysmall uniformly light-emitting domains at the size of several tens of μm. Fourier transform infrared reflection (FTIR) measurements show that the formation of Si-H bonds is not responsible for the visible luminescence in the very thin Si wires.

Molecular identification and characterization of the platelet ADP receptor targeted by thienopyridine antithrombotic drugs

ADP plays a critical role in modulating thrombosis and hemostasis. ADP initiates platelet aggregation by simultaneous activation of two G protein-coupled receptors, P2Y1 and P2Y12. Activation of P2Y1 activates phospholipase C and triggers shape change, while P2Y12 couples to Gi to reduce adenylyl cyclase activity. P2Y12 has been shown to be the target of the thienopyridine drugs, ticlopidine and clopidogrel. Recently, we cloned a human orphan receptor, SP1999, highly expressed in brain and platelets, which responded to ADP and had a pharmacological profile similar to that of P2Y12. To determine whether SP1999 is P2Y12, we generated SP1999-null mice. These mice appear normal, but they exhibit highly prolonged bleeding times, and their platelets aggregate poorly in responses to ADP and display a reduced sensitivity to thrombin and collagen. These platelets retain normal shape change and calcium flux in response to ADP but fail to inhibit adenylyl cyclase. In addition, oral clopidogrel does not inhibit aggregation responses to ADP in these mice. These results demonstrate that SP1999 is indeed the elusive receptor, P2Y12. Identification of the target receptor of the thienopyridine drugs affords us a better understanding of platelet function and provides tools that may lead to the discovery of more effective antithrombotic therapies.

ADP is the cognate ligand for the orphan G protein-coupled receptor SP1999

P2Y receptors are a class of G protein-coupled receptors activated primarily by ATP, UTP, and UDP. Five mammalian P2Y receptors have been cloned so far including P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11. P2Y1, P2Y2, and P2Y6 couple to the activation of phospholipase C, whereas P2Y4 and P2Y11 couple to the activation of both phospholipase C and the adenylyl cyclase pathways. Additional ADP receptors linked to Galpha(i) have been described but have not yet been cloned. SP1999 is an orphan G protein-coupled receptor, which is highly expressed in brain, spinal cord, and blood platelets. In the present study, we demonstrate that SP1999 is a Galpha(i)-coupled receptor that is potently activated by ADP. In an effort to identify ligands for SP1999, fractionated rat spinal cord extracts were assayed for Ca(2+) mobilization activity against Chinese hamster ovary cells transiently transfected with SP1999 and chimeric Galpha subunits (Galpha(q/i)). A substance that selectively activated SP1999-transfected cells was identified and purified through a series of chromatographic steps. Mass spectral analysis of the purified material definitively identified it as ADP. ADP was subsequently shown to inhibit forskolin-stimulated adenylyl cyclase activity through selective activation of SP1999 with an EC(50) of 60 nM. Other nucleotides were able to activate SP1999 with a rank order of potency 2-MeS-ATP = 2-MeS-ADP > ADP = adenosine 5'-O-2-(thio)diphosphate > 2-Cl-ATP > adenosine 5'-O-(thiotriphosphate). Thus, SP1999 is a novel, Galpha(i)-linked receptor for ADP.

[Telomerase activity and expression of its RNA component in laryngeal cancer]

OBJECTIVE

Expression of telomerase activity and telomerase RNA component have been reported in various human cancers. In the article, we ascertained whether telomerase activity and hTR changes are characteristic of laryngeal cancer.

METHOD

Telomerase activity were examined by telomeric repeat amplification protocol (Trap) and hTR examined by in situ hybridization, in tissue samples from 50 laryngeal cancer, 12 laryngeal polyps, 14 precancerous, 9 normal laryngeal tissue.

RESULT

1. All tissue expressed various levels of hTR. Positive rate of hTR increased with the clinical stage, but no significant correlation was observed, as well as lymph node metastasis. 2. The telomerase activity were detected in samples 39 of the 50 laryngeal cancer(78%). However, in 12 cases of begin lesions only 8.3% (1/12). Telomerase activity was found to have a relationship with the grade of tumor differentiation. Poorly differentiated laryngeal cancer expressed high level telomerase activity.

CONCLUSION

Telomerase activity were an early event of laryngeal cancer. It suggests that detection of telomerase activity could be a good diagnostic marker for distinguish cancer from normal cell.

Characterization of Ha-ras, N-ras, Ki-Ras4A, and Ki-Ras4B as in vitro substrates for farnesyl protein transferase and geranylgeranyl protein transferase type I

Ras proteins are small GTP-binding proteins which are critical for cell signaling and proliferation. Four Ras isoforms exist: Ha-Ras, N-Ras, Ki-Ras4A, and Ki-Ras4B. The carboxyl termini of all four isoforms are post-translationally modified by farnesyl protein transferase (FPT). Prenylation is required for oncogenic Ras to transform cells. Recently, it was reported that Ki-Ras4B is also an in vitro substrate for the related enzyme geranylgeranyl protein transferase-1 (GGPT-1) (James, G. L., Goldstein, J. L., and Brown, M. S. (1995) J. Biol. Chem. 270, 6221-6226). In the current studies, we compared the four isoforms of Ras as substrates for FPT and GGPT-1. The affinity of FPT for Ki-Ras4B (Km = 30 nM) is 10-20-fold higher than that for the other Ras isoforms. Consistent with this, when the different Ras isoforms are tested at equimolar concentrations, it requires 10-20-fold higher levels of CAAX-competitive compounds to inhibit Ki-Ras4B farnesylation. Additionally, we found that, as reported for Ki-Ras4B, N-Ras and Ki-Ras4A are also in vitro substrates for GGPT-1. Of the Ras isoforms, N-Ras is the highest affinity substrate for GGPT-1 and is similar in affinity to a standard GGPT-1 substrate terminating in leucine. However, the catalytic efficiencies of these geranylgeranylation reactions are between 15- and 140-fold lower than the corresponding farnesylation reactions, largely reflecting differences in affinity. Carboxyl-terminal peptides account for many of the properties of the Ras proteins. One interesting exception is that, unlike the full-length N-Ras protein, a carboxyl-terminal N-Ras peptide is not a GGPT-1 substrate, raising the possibility that upstream sequences in this protein may play a role in its recognition by GGPT-1. Studies with various carboxyl-terminal peptides from Ki-Ras4B suggest that both the carboxyl-terminal methionine and the upstream polylysine region are important determinants for geranylgeranylation. Furthermore, it was found that full-length Ki-Ras4B, but not other Ras isoforms, can be geranylgeranylated in vitro by FPT. These findings suggest that the different distribution of Ras isoforms and the ability of cells to alternatively process these proteins may explain in part the resistance of some cell lines to FPT inhibitors.

[Epidemiological analysis on the rising of brucellosis prevalence in the area already under controlled]

An epidemiological analysis was made on the outbreak of brucellosis in Sui-de County, Shaanxi Province in 1995-1996. Result showed that it was one of the most serious brucellosis outbreaks since 1986 when national brucellosis under controlled critiria had been met in the province, and the number of cases was continuously spreading and growing. The incidence was up to 84.8 per 10(5) and the prevalence rate reached 17.5 percent. Patients had typical symptoms with bad conditions. Most all the cases were those who had vocations such as shepherds, etc. Patients' antibody titers were very high with the highest one approached 1:25,600. Two strains of B. melitensis, type III were isolated from the blood of patients.

Influence of metal ions on substrate binding and catalytic activity of mammalian protein geranylgeranyltransferase type-I

Protein geranylgeranyltransferase type-I (GGTase-I) transfers a geranylgeranyl group from the prenyl donor geranylgeranyl diphosphate (GGPP) to the cysteine residue of substrate proteins containing a C-terminal CaaX-motif (a sequence motif of proteins consisting of an invariant Cys residue fourth from the C-terminus). The GGTase-I heterodimer contains one atom of zinc, and this metal is required for enzyme activity. In this regard, GGTase-I is similar to the related enzyme protein farnesyltransferase (FTase); the latter enzyme also requires Mg2+ for activity. The current studies were undertaken in an attempt to explore further the role of bivalent metal ions in the activity of GGTase-I. Surprisingly, we found that GGTase-I and FTase have different metal requirements. Specifically, in marked contrast to FTase, GGTase-I does not require Mg2+ for activity. Direct binding assays, including a novel fluorescence-based technique, were employed to obtain quantitative information on the interaction of substrates with GGTase-I. Using these assays, we demonstrate that the Zn2+ in GGTase-I is required for peptide, but not for isoprenoid, substrate binding. Moreover, binding of GGPP protects GGTase-I from inactivation by zinc-chelating reagents; this protective effect is not seen with binding of peptide substrates. Metal substitution studies show that the Zn2+ in GGTase-I can be replaced by Cd2+, and that the Cd form of GGTase-I has altered specificity with regard to utilization of both peptide and isoprenoid substrates. The significance of these findings in relation to proposed mechanisms for the GGTase-I reaction is discussed.

Protein prenylation: molecular mechanisms and functional consequences

Prenylation is a class of lipid modification involving covalent addition of either farnesyl (15-carbon) or geranylgeranyl (20-carbon) isoprenoids to conserved cysteine residues at or near the C-terminus of proteins. Known prenylated proteins include fungal mating factors, nuclear lamins, Ras and Ras-related GTP-binding proteins (G proteins), the subunits of trimeric G proteins, protein kinases, and at least one viral protein. Prenylation promotes membrane interactions of most of these proteins, which is not surprising given the hydrophobicity of the lipids involved. In addition, however, prenylation appears to play a major role in several protein-protein interactions involving these species. The emphasis in this review is on the enzymology of prenyl protein processing and the functional significance of prenylation in cellular events. Several other recent reviews provide more detailed coverage of aspects of prenylation that receive limited attention here owing to length restrictions (1-4).

Substitution of cadmium for zinc in farnesyl:protein transferase alters its substrate specificity

Ras proteins are mutationally activated in a variety of human cancers. Since farnesylation of Ras proteins is required for expression of their oncogenic potential, the enzyme responsible for this reaction, farnesyl:protein transferase (FPT), has become a major target for anticancer drug development. FPT is a zinc metalloenzyme, and the zinc is essential for its catalytic activity. To begin to elucidate the role of zinc in catalysis, we initiated metal substitution studies. Of all metals tested, only cadmium was able to functionally substitute for zinc, reconstituting enzymatic activity with native substrates (H-Ras and farnesyl diphosphate) to about 50% of that of the zinc-containing enzyme. Several important differences were observed between cadmium-substituted FPT (Cd-FPT) and zinc-containing FPT (Zn-FPT). Cd-FPT not only uses H-ras with its native CaaX motif (Ras-CVLS) as a substrate but also can farnesylate H-ras in which the CaaX motif is altered to contain a C-terminal leucine residue (Ras-CVLL). Similarly, Cd-FPT can farnesylate leucine-terminated peptides. Leucine-terminated proteins and peptides are usually substrates for the related enzyme geranylgeranyl:protein transferase type I. Farnesylation of Ras-CVLS and Ras-CVLL by Cd-FPT exhibited similar sensitivity to the FPT inhibitor SCH 44342 and to the peptide inhibitor CAIM. However, unlike Zn-FPT, Cd-FPT is also potently inhibited by the leucine-terminated peptide CAIL. These results indicate that the metal ion content of FPT strongly influences its protein substrate specificity.

Protein prenylation: molecular mechanisms and functional consequences

Prenylation is a class of lipid modification involving covalent addition of either farnesyl (15-carbon) or geranylgeranyl (20-carbon) isoprenoids to conserved cysteine residues at or near the C-terminus of proteins. Known prenylated proteins include fungal mating factors, nuclear lamins, Ras and Ras-related GTP-binding proteins (G proteins), the subunits of trimeric G proteins, protein kinases, and at least one viral protein. Prenylation promotes membrane interactions of most of these proteins, which is not surprising given the hydrophobicity of the lipids involved. In addition, however, prenylation appears to play a major role in several protein-protein interactions involving these species. The emphasis in this review is on the enzymology of prenyl protein processing and the functional significance of prenylation in cellular events. Several other recent reviews provide more detailed coverage of aspects of prenylation that receive limited attention here owing to length restrictions (1-4).

[Relationship between anti-coagulation system changes of coronary heart disease patients and different syndrome-type in TCM]

The level of Antithrombin-III : antibody (ATIII : A), Antithrombin III: antigen (ATIII : Ag), protein C antigen (PC : Ag), Total protein S : antigen (TPS : Ag) and Free protein S : antigen (FPS : Ag) were determined in 46 cases of coronary heart disease (CHD) and 40 cases normal control with the thrombin gelplaque technique and the immunoelectrophoresis assay. The results showed: the level of the PC: Ag and TPS: Ag of Qi stagnation type of CHD were significantly higher than those in normal control group (P < 0.05), the level of the AIII: Ag, ATIII : Ag in blood stasis type of CHD were significantly less than those in control (P < 0.05). These suggested that the level of PC: Ag and TPS: Ag might be used as referential indices of the Qi stagnation type; the level of ATIII: A, ATIII : Ag might be used as those of blood stasis type in CHD.

A fluorescence assay for geranylgeranyl transferase type I

A new fluorescence assay for measuring the activity of geranylgeranyl transferase (type I) is described. It does not require the use of either radiolabeled geranylgeranyl diphosphate or the purified recombinant Ras protein substrate with the carboxy terminal sequence of CVLL. Dansyl GCVLL and unlabeled geranylgeranyl diphosphate are used as substrates. The Km for Dansyl GCVLL and for geranylgeranyl diphosphate is 5 microM and 800 nM, respectively. At equimolar concentrations, enzymatic activity is higher when Dansyl GCVLL is used as a substrate compared to Dansyl GCVII. Dansyl GCVLS, a substrate for farnesyl transferase, is inactive in this assay. CVFL is a competitive inhibitor of geranylgeranyl transferase and exhibits a Ki of 200 nM.

Properties and kinetic mechanism of recombinant mammalian protein geranylgeranyltransferase type I

Protein geranylgeranyltransferase type I (GGTase I) catalyzes the prenylation of a number of proteins that play important roles in cellular signaling. The recent cDNA cloning of this enzyme (Zhang, F. L., Diehl, R. E., Kohl, N. E., Gibbs, J. B., Giros, B., Casey, P. J., and Omer, C. A. (1994) J. Biol. Chem. 269, 3175-3180) has allowed us to develop an expression system for obtaining large quantities of the enzyme. Co-infection of insect cells with recombinant baculoviruses encoding the two subunits of the enzyme results in GGTase I accumulation within the cells to levels of > 20% of cytosolic protein. The recombinant enzyme could be readily purified by ion-exchange chromatography and is shown to possess the activity and specificity of the enzyme obtained from mammalian tissues. Production of the recombinant enzyme allowed us to confirm its identity as a zinc metalloenzyme by direct identification of the metal using atomic absorption spectroscopy. We also identify two substrate analogs that are competitive inhibitors of GGTase I. One is a novel isoprenoid analog, 3-aza-GGPP, which inhibits the enzyme with a Ki of 15 nM. The second inhibitor is the tetrapeptide Cys-Val-Phe-Leu, which exhibits a Ki of 50 nM. The use of these inhibitors, coupled with a steady-state kinetic analysis of the enzyme, reveals that the reaction catalyzed by GGTase I proceeds through a random ordered sequential mechanism.

cDNA cloning and expression of rat and human protein geranylgeranyltransferase type-I

Protein geranylgeranyltransferase type-I (GGTase-I) transfers a geranylgeranyl group to the cysteine residue of candidate proteins containing a carboxyl-terminal CAAX (C, cysteine; A, aliphatic amino acid; X, any amino acid) motif in which the "X" residue is leucine. The enzyme is composed of a 48-kilodalton alpha subunit and a 43-kilodalton beta subunit. Peptides isolated from the alpha subunit of GGTase-I were shown to be identical with the alpha subunit of a related enzyme, protein farnesyltransferase. Overlapping cDNA clones containing the complete coding sequence for the beta subunit of GGTase-I were obtained from rat and human cDNA libraries. The cDNA clones from both species each predicted a protein of 377 amino acids with molecular masses of 42.4 kilodaltons (human) and 42.5 kilodaltons (rat). Amino acid sequence comparison suggests that the protein encoded by the Saccharomyces cerevisiae gene CDC43 is the yeast counterpart of the mammalian GGTase-I beta subunit. Co-expression of the GGTase-I beta subunit cDNA together with the alpha subunit of protein farnesyltransferase in Escherichia coli produced recombinant GGTase-I with electrophoretic and enzymatic properties indistinguishable from native GGTase-I.

[Effects of tetrandrine on hypertensive responses induced by electric stimulation and alpha-adrenoceptor agonists in pithed rats]

Tetrandrine (Tet) 5 mg.kg-1 i.v. inhibited the pressor action of norepinephrine (NE) release induced by electric stimulation (10 V, 0.5-16 Hz) of spinal cord T11-L2. However, Tet 5 mg.kg-1 ia did not obviously attenuate the hypertensive responses to NE 0.51-16.91 micrograms.kg-1 i.v., indicating that Tet did not affect the alpha 1-adrenoceptors-mediated vasoconstriction. Tet 5 mg.kg-1 ia decreased the pressor responses to NE 0.05 and 0.17 micrograms.kg-1 i.v. and markedly reduced the dose-dependent hypertensive responses to B-HT920 i.v., a selective alpha 2-adrenoceptor agonist, proving that Tet reduced alpha 2-adrenoceptors-mediated vasoconstriction.

[Functional classification of pituitary adenomas]

Pituitary adenomas might be classified into different groups according to different variety of hormone produced. 225 surgical specimens were labeled with anti- sera of GH, PRL, ACTH, TSH, FSH, and LH, via immunohistochemical technique (ABC method). Data indicated that 100 out of the 225 (44.5%) were monohormonal adenomas, including 24 GH, 39 PRL, 1 FSH and 9 LH, 77 (34.2%) were multi- hormonal adenomas, including 28 positive for 2 hormones, 30 positive for 3 hormones, 19 positive for 4 or more different hormones, and the remaining 48 (21.3%) were nonfunctional adenomas. In comparison with Kovacs series, factors which might participate in the mechanism of developing monohormonal or multi- hormonal adenomas are discussed.