Effective Management of Citrus Melanose Based on Combination of Ecofriendly Chemicals

Citrus melanose, caused by the ascomycete fungus Diaporthe citri, is one of the most important diseases in China that affects not only the production but also the quality of citrus. In China, mancozeb is recommended to control melanose disease at the dose of 1.34 g/liter. However, it is widely applied in practice at the dose of 2.66 g/liter or even 4 g/liter, because reduced efficacy of the recommended dose was observed in regions severely damaged by melanose. In this study, some ecofriendly chemicals for melanose management were evaluated. First, the sensitivity to fungicides was screened in the laboratory based on the inhibition of mycelial growth and conidial germination of D. citri. Results showed that both quinone outside inhibitor (QoI) fungicides kresoxim-methyl and trifloxystrobin inhibited conidial germination of D. citri up to 100% at 0.1 μg/ml. The in vivo control efficacy on detached fruit indicated that treatments with elastic nanocopolymer film at 2 g/liter, mancozeb at 1 g/liter, and kresoxim-methyl at 0.1 g/liter significantly inhibited the infection process compared with the control treatment of mineral oil alone. In field trials, the efficacy of kresoxim-methyl at 0.1 g/liter and elastic nanocopolymer film at 2 g/liter mixed with mancozeb at 1 g/liter was equal to that of mancozeb at 2.66 g/liter. The use of mancozeb could be reduced greatly, and the newly developed fungicide combinations are more environmentally friendly due to the low toxicity of both QoI fungicides and elastic nanocopolymer film. The newly developed method with ecofriendly chemicals should play an important role in the management of citrus melanose in the future.

Genetic pathogenesis of acephalic spermatozoa syndrome: past, present, and future

Acephalic spermatozoa syndrome (ASS) is one of the most severe spermatogenic failures of all infertility in men. The cognition of ASS has experienced a tortuous process. Over the past years, with the in-depth understanding of spermatogenesis and the emergence of new genetic research technologies, the unraveling of the genetic causes of spermatogenic failure has become highly active. From these advances, we established a genetic background and made significant progress in the discovery of the genetic causes of ASS. It is important to identify pathogenic genes and mutations in ASS to determine the biological reasons for the occurrence of the disease as well as provide genetic diagnosis and treatment strategies for patients with this syndrome. In this review, we enumerate various technological developments, which have made a positive contribution to the discovery of candidate genes for ASS from the past to the present. Simultaneously, we summarize the known genetic etiology of this phenotype and the clinical outcomes of treatments in the present. Furthermore, we propose perspectives for further study and application of genetic diagnosis and assisted reproductive treatment in the future.

[Outcomes of assisted reproductive technology for patients with different types of teratozoospermia]

OBJECTIVE

To discuss the outcomes of ICSI in infertile patients with globozoospermia (GS), acephalic spermatozoa syndrome (ASS) or teratozoospermia with miniacrosome and irregular-headed sperm defect (TMRHS).

METHODS

This retrospective study included 3 cases of GS, 3 cases of ASS and 2 cases of TMRHS undergoing ICSI. We analyzed the rates of fertilization, cleavage, blastocyst formation, implantation, clinical pregnancy and live birth in the three groups of patients.

RESULTS

The patients of the GS and ASS groups all achieved clinical pregnancies and healthy births, but those of the TMRHS group showed a lower fertilization rate than the other two groups and achieved no clinical pregnancy.

CONCLUSIONS

ICSI could achieve successful clinical pregnancy in infertile patients with globozoospermia or acephalic spermatozoa syndrome, but no satisfactory clinical outcome in those with miniacrosome and irregular-headed sperm defect, though it has to be further proved by more studies with larger-sized samples.

Novel DPY19L2 variants in globozoospermic patients and the overcoming this male infertility

Globozoospermia has been reported to be a rare but severe causation of male infertility, which results from the failure of acrosome biogenesis and sperm head shaping. Variants of dpy-19-like 2 (DPY19L2) are highly related to globozoospermia, but related investigations have been mainly performed in patients from Western countries. Here, we performed a screening of DPY19L2 variants in a cohort of Chinese globozoospermic patients and found that five of nine patients carried DPY19L2 deletions and the other four patients contained novel DPY19L2 point mutations, as revealed by whole-exome sequencing. Patient 3 (P3) contained a heterozygous variant (c.2126+5G>A), P6 contained a homozygous nonsense mutation (c.1720C>T, p.Arg574^*), P8 contained compound heterozygous variants (c.1182-1184delATC, p.Leu394_Ser395delinsPhe; c.368A>T, p.His123Arg), and P9 contained a heterozygous variant (c.1182-1184delATCTT, frameshift). We also reported intracytoplasmic sperm injection (ICSI) outcomes in the related patients, finding that ICSI followed by assisted oocyte activation (AOA) with calcium ionophore achieved high rates of live births. In summary, the infertility of these patients results from DPY19L2 dysfunction and can be treated by ICSI together with AOA.

[Analysis of risk factors associated with weaning from mechanical ventilation in critical patients with major abdominal surgery]

OBJECTIVE

To analyze the risk factors involved in the weaning from mechanical ventilation in critical patients who underwent major abdominal surgery.

METHODS

This retrospective study was conducted at Department of Critical Care Medicine in Peking University People's Hospital. The subjects included all critical ill patients who underwent major abdominal surgery from January 2011 to December 2013. Clinical and laboratory parameters in perioperative period were investigated for the risk factors involved in the weaning from mechanical ventilation.

RESULTS

In this study, 381 patients were included, of whom, 274 were successfully weaned. We found old age, lower left ventricular ejection fraction (LVEF) before surgery, with the complication of myocardial injury after noncardiac surgery (MINS) and lower serum albumin level after surgery were the independent risk factors of weaning from mechanical ventilation. And the days of intensive care unit and 28-day mortality of patients who successfully weaned were better than patients who failed to wean.

CONCLUSION

Old age, lower LVEF before surgery, with the complication of MINS and lower serum albumin level after surgery were independent risk factors of weaning in critical patients who underwent major abdominal surgery.

First Report of Dimethachlon Resistance in Field Isolates of Sclerotinia sclerotiorum on Oilseed Rape in Shaanxi Province of Northwestern China

Sclerotinia sclerotiorum (Lib.) de Bary is a necrotrophic fungal pathogen causing diseases in a wide range of plants, including oilseed rape (3). Substantial economic losses caused by S. sclerotiorum have been reported in the United States, Canada, Brazil, South Africa, Hungary, India, Nepal, and Japan (1). Application of fungicides is the principal tool for controlling S. sclerotiorum because of lack of high level of host resistance. Dicarboximide fungicides such as dimethachlon have been widely used to control S. sclerotiorum in recent years in China and field isolates with reduced sensitivity to dimethachlon have been reported in Jiangsu Province of eastern China (2). In order to understand the current status of dimethachlon resistance in S. sclerotiorum isolates of northwestern China, 196 and 344 isolates of S. sclerotiorum collected from oilseed rape fields in 10 counties throughout Shaanxi Province in 2011 and 2012, respectively, were assayed for sensitivity to dimethachlon using 5 μg ml^-1 dimethachlon as a discriminatory dose. Mycelial plugs (6 mm in diameter) cut from the margin of a 48-h-old colony were placed in the center of petri dishes containing potato dextrose agar (PDA) amended with 5 μg ml^-1 dimethachlon; PDA without fungicide served as the control. Cultures were incubated at 26°C and colony growth was measured after 72 h of incubation. Isolates that showed growth on PDA amended with fungicide were tentatively considered resistant to dimethachlon, whereas the completely inhibited isolates were considered sensitive. Results showed that 1.02% or 2 isolates of the 196 isolates collected in 2011 and 3.78% or 13 isolates of the 344 isolates collected in 2012 were resistant to dimethachlon. For all the isolates considered resistant and 42 randomly selected sensitive isolates, 50% effective concentrations (EC₅₀) were determined on PDA amended with a series of dimethachlon concentrations. The average EC₅₀ value of dimethachlon for sensitive isolates was 0.29 ± 0.02 μg ml^-1 Resistance ratios (EC₅₀ of resistant isolate / average EC₅₀ of sensitive isolates) for the two resistant isolates detected in 2011 were 10.28 and 23.83, respectively, whereas resistance ratios for the 13 resistant isolates detected in 2012 ranged from 24.90 to 101.97. The average EC₅₀ value of dimethachlon for the 13 resistant isolates detected in 2012 was 19.05 μg ml^-1, and EC₅₀ values for the two resistant isolates detected in 2011 were 2.98 and 6.91 μg ml^-1, respectively. These results indicated that both resistance frequency and resistance level increased from 2011 to 2012. Bioassay results of three resistant isolates indicated that there was positive cross-resistance between dimethachlon and other dicarboximide fungicides such as iprodione and procymidone. To our knowledge, this is the first report of dimethachlon resistance in S. sclerotiorum in Shaanxi Province of northwestern China. The molecular mechanism of dimethachlon resistance in field isolates of S. sclerotiorum remains to be studied. Although resistance frequency is low at present, dimethachlon resistance should be kept in mind and fungicide resistance management tactics such as use of biological control agents, fungicide tank-mixing, or alternating dimethachlon with other fungicides having different modes of action is recommended in controlling S. sclerotiorum. References: (1) M. D. Bolton et al. Mol Plant Pathol. 7:1, 2006. (2) H. X. Ma et al. Plant Dis. 93:36, 2009. (3) L. H. Prudy. Phytopathology 69:875, 1979.

First Report of the β-tubulin E198A Allele for Fungicide Resistance in Monilinia fructicola from South Carolina

Resistance to methyl benzimidazole carbamates (MBCs) in Monilinia fructicola, the causal agent of brown rot of stone fruits, is known to be present in South Carolina peach orchards, but the molecular mechanism of resistance has not been investigated. Nine isolates were collected from peach in five counties in South Carolina and examined in petri dish assays on potato dextrose agar (PDA) for resistance to the MBC fungicide thiophanate-methyl (Topsin-M 70WP; Ceraxagri, King of Prussia, PA) at the discriminatory dose of 50 μg/ml. Isolates that grew on the fungicide-amended medium were considered highly resistant (HR). The β-tubulin gene from four sensitive (S) and five HR M. fructicola isolates was PCR-amplified with primer pair TubA and TubR1 as described previously (1). Sequence analysis revealed several silent mutations in introns and exons in S and HR isolates and the presence of the previously described E198A allele in HR but not S isolates (1). Nucleotide sequences of the β-tubulin gene from three S (BS, S2, MfEgpc1) and two HR isolates (MfPdt6 and BR2) were submitted to GenBank under accession numbers HM051379, HM051380, HM051381, HM051382, and HM051383, respectively. To our knowledge, this is the first report of the E198A in M. fructicola isolates from South Carolina and the East Coast. This allele is responsible for high levels of MBC resistance in M. fructicola (1). A previously reported PCR-based method using primers HRF+HRR designed to detect the E198A mutation in M. fructicola HR isolates (1) was improved by adding primer TR739 (5'-TCA CGA CGA ACA ACA TCA AGA-3') to the PCR cocktail. This additional internal primer amplified a 222-bp fragment from all S and HR isolates and therefore provided a useful, additional control. The confirmation of the E198A allele in M. fructicola isolates provides another useful tool to detect MBC resistance in commercial peach orchards in South Carolina. Reference: (1) Z. H. Ma et al. Appl. Environ. Microbiol. 69:7145, 2003.

[Mutation of KLHL-10 in idiopathic infertile males with azoospermia, oligospermia or asthenospermia]

OBJECTIVE

To investigate the relationship of the mutation of the spermatogenesis-associated gene KLHL-10 with azoospermia, oligospermia and asthenospermia.

METHODS

Genomic DNA was extracted from the peripheral blood samples of 325 patients with idiopathic azoospermia (n = 11), oligozoospermia (n = 196) or asthenospermia (n = 118) and 100 fertile male controls. KLHL-10 mutations were detected for all the DNA specimens by PCR, DHPLC and sequencing techniques.

RESULTS

A novel heterozygous mutation (C88 --> A) was identified in exon 1 from 1 oligospermia patient and 3 fertile male controls and another one (C424 --> A) confirmed in exon 2 from 4 fertile controls, 3 oligospermia patients and 1 asthenospermia man. Both of the mutations were synonymous, but neither missense mutation nor microdeletion of the KLHL-10 gene was found.

CONCLUSION

The KLHL-10 gene is not a major contributor to azoospermia, oligospermia or asthenospermia in Chinese population. The value of this gene in the diagnosis of male infertility remains to be further investigated.

[Construction of fusion recombinant plasmid coding for RGD peptide and urokinase B chain, its expression in Escherichia coli and preliminary characterization of its biological activity]

A synthetic RGD (Arg-Gly-Asp) peptide-coding sequence was fused with urokinase B-chain cDNA and then cloned into the prokaryotic expression vector pBV220. The fused gene was expressed in E. coli DH5 alpha under the control of PRPL promoter by 42 degrees C induction. The expression level of the fusion protein was over 9.2% of the total bacterial proteins as a or of inactive inclusion body. The purified fusion protein was obtained with similar antigenicity as urokinase shown by Western blotting. Its in vitro fibrinolysis and anti-platelet aggregation activity was also evaluated by bioassay.

[cDNA cloning and sequencing of human urokinase receptor]

Human urokinase receptor (uPAR), a 55 kD glycoprotein linked to the cell membrane by a glycosylphosphatidylinositol anchor, plays a central role in cell migration and tissue remodeling. The human uPAR cDNA was cloned from a highly metastatic human lung giant cell line PG by RT-PCR and then subcloned into pGEM-T vector and sequenced. The data indicate that there are three bases substitution (705, 746, 755) which subsequently leads to two amino acid mutation (249, 252) compared to that of previously reported. The cDNA sequence of uPAR was registered in GenBank with accession number AF257789.

Development and use of a polymerase chain reaction-based diagnostic test for the causal mutation of progressive retinal atrophy in Cardigan Welsh Corgis

OBJECTIVE

To develop an allele-specific polymerase chain reaction (ASPCR)-based diagnostic test for the mutation in the cyclic guanosine monophosphate phosphodiesterase alpha subunit gene (PDE6A) that causes the rcd3 form of progressive retinal atrophy (PRA) in Cardigan Welsh Corgis.

ANIMALS

1 affected homozygote, 1 unaffected carrier, 1 genotypically normal dog, and 500 unknown-PRA status Cardigan Welsh Corgis.

PROCEDURE

Control blood samples were collected from Cardigan Welsh Corgis of known PRA status (ie, affected homozygote, unaffected carrier, and a genotypically normal dog) for test development. Test blood samples were collected from 500 Cardigan Welsh Corgis of unknown PRA status. Genomic DNA was used as a template in ASPCR. One pair of primers was designed to specifically amplify only the mutant allele, and another set to amplify only the wildtype allele. The PCR conditions were adjusted to ensure each reaction was 100% specific.

RESULTS

The PCR conditions were identified so that each ASPCR only amplified the allele it was designed to amplify. Of the 500 Cardigan Welsh Corgis tested using the newly developed ASPCR, 457 were homozygous for the normal allele (genotypically normal), 43 were heterozygous (phenotypically normal carriers), and none were homozygous for the mutant allele.

CONCLUSION AND CLINICAL RELEVANCE

A rapid, ASPCR diagnostic test able to detect the PDE6A gene mutation responsible for the rcd3 form of PRA in Cardigan Welsh Corgis was developed. The test provides a useful service for Cardigan Welsh Corgi breeders and will enable them to prevent the birth of homozygote mutant dogs.

Identification of the immediate-early transcripts of Kaposi's sarcoma-associated herpesvirus

In the immediate-early phase of reactivation or primary infection, herpesviruses express a small number of genes without requiring prior viral protein synthesis. Immediate-early genes usually encode regulatory proteins critical for the viral life cycle. Kaposi's sarcoma-associated herpesvirus (KSHV) gene transcription in the immediate-early stage of viral reactivation was examined by using a chemical induction combined with a gene expression screening method. RNA transcripts from at least four KSHV genomic loci accumulate when latently infected B-lymphoma cells are induced for reactivation in the presence of an inhibitor of protein synthesis (cycloheximide) and thus represent immediate-early class transcripts. Among them, a 3.6-kb mRNA encodes three putative open reading frames (ORFs), namely, ORF50, K8, and K8.2. ORF50 is a homologue of Rta, a transcription activator encoded by Epstein-Barr virus (EBV). The K8 gene codes for a 237-amino-acid protein with a basic-leucine zipper domain near its C terminus and an acidic domain near its N terminus and which closely resembles the ZEBRA protein of EBV and Jun/Fos family proteins. Other immediate-early mRNAs of KSHV include a 1. 7-kb mRNA encoding ORF45, a 2.0-kb mRNA encoding ORF K4.2, and a 4. 5-kb mRNA. Functional roles of products of these KSHV immediate-early transcripts remain to be studied.

Modulation of ACh release from airway cholinergic nerves in horses with recurrent airway obstruction

To evaluate the functional status of neuronal alpha2-adrenoceptors (ARs) and beta2-ARs on ACh release in horses with recurrent airway obstruction (RAO), we examined the effects of the physiological agonists epinephrine (Epi) and norepinephrine (NE) and the beta2-agonists RR- and RR/SS-formoterol on ACh release from airway cholinergic nerves of horses with RAO. Because SS-formoterol, a distomer of the beta2-agonist, increases ACh release from airways of control horses only after the autoinhibitory muscarinic receptors are blocked by atropine, we also tested the hypothesis that if there is an M2-receptor dysfunction in equine RAO, SS-formoterol should increase ACh release even in the absence of atropine. ACh release was evoked by electrical field stimulation and measured by HPLC. Epi and NE caused less inhibition of ACh release in horses with RAO than in control horses. At the catecholamine concentration achieved during exercise (10(-7) M), the inhibition induced by Epi and NE was 10.8 +/- 13.2 and 3.4 +/- 6.8%, respectively, in equine RAO versus 41.0 +/- 6.4 and 27.1 +/- 5.6%, respectively, in control horses. RR- and RR/SS-formoterol (10(-8) to 10(-5) M) increased ACh release to a similar magnitude as that in control horses. These results indicate that neuronal beta2-ARs are functioning; however, the alpha2-ARs are dysfunctional in the airways of horses with RAO in response to circulating catecholamines. SS-formoterol (10(-8) to 10(-5) M) facilitated ACh release in horses with RAO even in the absence of atropine. Addition of atropine did not cause significantly more augmentation of ACh release over the effect of SS-formoterol alone. The magnitude of augmentation in horses with RAO in the absence of atropine was similar to that in control horses in the presence of atropine. The latter observations could be explained by neuronal muscarinic-autoreceptor dysfunction in equine RAO.

Mediators of anaphylaxis but not activated neutrophils augment cholinergic responses of equine small airways

Neutrophilic inflammation in small airways (SA) and bronchospasm mediated via muscarinic receptors are features of chronic obstructive pulmonary disease in horses (COPD). Histamine, serotonin, and leukotrienes (LTs) are reported to be involved in the exacerbation of COPD, and currently, histamine has been shown to increase tension response to electrical field simulation (EFS) in equine SA. We tested the effects of these mediators and the effects of activated neutrophils on the cholinergic responses in SA. Histamine, serotonin, and LTD4 had a synergistic effect on EFS responses and only an additive effect on the tension response to exogenous ACh or methacholine. Atropine and TTX entirely eliminated the EFS-induced tension response in the presence of all three inflammatory mediators, indicating that augmentation of the EFS response applies only to the endogenous cholinergic response. Neutrophils isolated from control and COPD-affected horses were activated by zymosan, producing 18.1 +/- 2.3 and 25.0 +/- 2.3 nmol superoxide. 10(6) cells-1. 30 min-1, respectively. However, in contrast to the profound effect of mediators, incubation of SA for over 1 h in a suspension of up to 30 x 10(6) zymosan-treated neutrophils/ml did not significantly affect EFS responses of SA isolated from either control or COPD-affected horses. We conclude that in equine SA 1) the endogenous cholinergic responses are subject to strong facilitation by inflammatory mediators; 2) activated neutrophils do not affect cholinergic responses in SA; and 3) in acute bouts of equine COPD, histamine, LTD4, and serotonin (mediators primarily associated with type I allergic reaction) rather than mediators derived from neutrophils most likely contribute to increased cholinergic airway tone.

Role of cAMP and neuronal K+ channels on alpha 2-AR-induced inhibition of ACh release in equine trachea

To investigate the effects of changes in intracellular cAMP on alpha 2-adrenoceptor (AR)-induced inhibition of airway acetylcholine (ACh) release, we examined the effects of the alpha 2-AR agonist clonidine on electrical field stimulation-evoked ACh release from equine tracheal parasympathetic nerves before and after treatment with 8-bromo-cAMP or forskolin. We also tested whether charybdotoxin (ChTX)- or iberiotoxin (IBTX)-sensitive Ca(2+)-activated K+ channels mediate alpha 2-AR-induced inhibition by examining the effect of clonidine in the absence and presence of ChTX or IBTX on ACh release. The amount of released ACh was measured by HPLC coupled with electrochemical detection. Clonidine (10(-7) to 10(-5) M) dose dependently inhibited ACh release before and after treatment with 8-bromo-cAMP (10(-3) M) or forskolin (3 x 10(-5) M). ChTX and IBTX, both at the concentration of 5 x 10(-7) M, significantly increased ACh release; however, they did not alter the magnitude of clonidine-induced inhibition. These results indicated that in equine tracheal parasympathetic nerves, alpha 2-AR-induced inhibition of ACh release is via an intracellular cAMP-independent pathway. Activation of both ChTX- and IBTX-sensitive Ca(2+)-activated K+ channels inhibits the electrical field stimulation-evoked ACh release, but these channels are not involved in the alpha 2-AR-induced inhibition of ACh release.

[Effect of diazepam on delayed nausea and vomiting caused by anticancer agents]

We conducted an evaluation of the usefulness of antiemetics (5-Hydroxy-tryptamine 3 receptor antagonism, 5HT3RA) combined with diazepam for delayed nausea and vomiting due to anticancer agents in 17 patients with various malignancies (such as lung Ca, breast Ca, esophagus Ca, gastric Ca, colon Ca, and non Hodgkin's disease) for whom chemotherapy was performed with different regimens in the Dept. of Oncologic Chemotherapy, People's Hospital, Beijing Medical University. Antiemetics (5HT3RA) combined with diazepam were given only to cases that had symptoms of nausea and vomiting induced by anticancer agents in the 1st course and invalidity with antiemetics (5HT3RA) alone in this study. Antiemetic (5HT3RA) agents + Dexamethasone were dosed before chemotherapy and also diazepam 5 mg orally after 24 hours (namely, when nausea was observed). Nausea was reduced and vomiting decreased after the antiemetic treatment with 5HT3RA + Dexamethasone and diazepam. These results indicated that 5HT3RA and diazepam combination therapies were more effective than 5HT3 RA + Dexamethasone alone for delayed nausea and vomiting. Further, the antiemetics had characters that a short adminiter time, few times and a take not over dose. The only side effect related to this antiemetic therapy was light somnolence. Antiemetics combined with diazepam might be a useful therapy against delayed nausea and vomiting induced by anticancer agents.

Effects of enantiomers of beta 2-agonists on ACh release and smooth muscle contraction in the trachea

The beta 2-agonists currently used as bronchodilators are racemic mixtures of R- and S-enantiomers. In the present study, we examined the effects of enantiomers of the beta 2-agonists albuterol and formoterol on acetylcholine (ACh) release from equine trachealis parasympathetic nerves. ACh release was evoked by electrical field stimulation (20 V, 0.5 ms, 0.5 Hz) and measured by high-performance liquid chromatography coupled with electrochemical detection. We also tested the effects of enantiomers of albuterol and formoterol on equine tracheal smooth muscle (TSM) contraction in response to exogenous ACh. R- and RS-albuterol (10(-8) to 10(-5) M) and RR- and RR/SS-formoterol (10(-8) to 10(-5) M) augmented ACh release in a concentration-dependent manner. Beginning at 10(-6) M, SS-formoterol significantly increased ACh release, and at 10(-5) M, release increased by 71.9 +/- 8.7% over baseline. This effect was only observed, however, when the prejunctional muscarinic autoinhibitory effect of ACh was prevented with atropine. Both the RR- and SS-formoterol-induced increases in ACh release were abolished by the beta 2-antagonist ICI-118551 (3 x 10(-7) M). The effect of S-albuterol on ACh release was variable, and the mean increase induced by 10(-5) M was 30.8 +/- 16.1% in the presence of atropine. In the muscle tension study, R- and RS-albuterol and RR- and RR/SS-formoterol (10(-8) to 10(-5) M) but not the S-enantiomers inhibited TSM contraction. Even though R-enantiomers augment ACh release, they potently inhibit TSM contraction. Because racemic beta 2-agonists are bronchodilators on acute administration, the postjunctional spasmolytic effects of R-enantiomers predominate over the spasmogenic effect evoked via increased ACh release. The S-enantiomers, in contrast, do not inhibit TSM contraction and therefore would not contribute to the observed bronchodilation of the racemate. The S-enantiomers do prejunctionally facilitate ACh release when prejunctional muscarinic autoreceptors are dysfunctional, suggesting a potentially deleterious effect.

Mechanism of capsaicin-induced relaxation in equine tracheal smooth muscle

The effects of capsaicin and neuropeptides were examined in equine tracheal smooth muscle (TSM). Neither capsaicin nor substance P (SP) contracted TSM. Capsaicin (100 microM) elicited relaxation in TSM contracted with methacholine. This relaxation was not mimicked by SP or calcitonin gene-related peptide (CGRP). Relaxation was not attenuated by removal of the epithelium or by pretreatment of tissue with meclofenamate or the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine. Previous exposure of TSM to capsaicin did not eliminate the relaxation responses to subsequent capsaicin. Although vasoactive intestinal peptide (VIP) elicited marked relaxation that was attenuated by alpha-chymotrypsin, alpha-chymotrypsin did not affect the capsaicin-induced relaxation. Capsaicin-induced relaxation was abolished by charybdotoxin, a blocker of large-conductance Ca(2+)-activated K+ channels. These results indicate that capsaicin-induced equine TSM relaxation is not mediated either by neuropeptides such as SP or CGRP released from capsaicin-sensitive sensory nerves or by prostanoids, NO, or VIP. Relaxation is due to the effect of capsaicin on large-conductance Ca(2+)-activated K+ channels. The peptidergic nerves play no important role in the regulation of TSM tone in horse airways.

Stimulation of RTH1 nuclease of the yeast Saccharomyces cerevisiae by replication protein A

The RTH1 nuclease is involved in the replication of chromosomal DNA as well as in the repair of DNA damage. Replication protein A (RPA) is also an integral part of the DNA replication and repair processes. We have investigated the roles(s) of RPA in the function of RTH1 nuclease, including its structure specific endonuclease activity. Initial in vitro studies, which employed a "flap" or a "pseudo Y" substrate containing a short 14 bp duplex region, showed the effect of RPA to be minimal or inhibitory. As RPA inhibition is unwarranted for a protein participating in the DNA replication process, we have further investigated the mechanism of such inhibition. Alternate flap and pseudo Y substrates with a long duplex region (50 bp) were prepared using M13mp19 ssDNA and synthetic oligonucleotides. Yeast RPA stimulated the endonuclease activity of RTH1 endonuclease with these substrates in a dose-dependent manner. Kinetic analysis suggested that yRPA exerted a bipartite effect on the nuclease reaction: (i) the "load time" of RTH1 nuclease onto the DNA substrate decreased from approximately 5 to 2 min in the presence of RPA, and (ii) following initiation of the nuclease reaction, the initial rate of the reaction increased 10-fold in the presence of yRPA. Further analysis of the interaction of RPA with various endonuclease substrates indicated that RPA has a weak helix destabilizing effect and could melt small, 14 bp, regions of duplex DNA. RTH1 endonuclease cleaves the DNA strand at the junction of single- and double-stranded DNA; consequently, the observed inhibition with small duplex substrates was likely due to duplex melting. Our studies also demonstrated that RPA stimulated the RNase H activity of RTH1 nuclease significantly. In both instances (RTH1 endonuclease and RNase H), the stimulation may involve a specific interaction of RPA with the RTH1 nuclease rather than a structural positioning of the DNA substrate by RPA.

Purification and characterization of the DNA polymerase alpha associated exonuclease: the RTH1 gene product

We report here the purification and mechanistic characterization of a 5'-3' exonuclease associated with DNA polymerase alpha from the yeast Saccharomyces cerevisiae. Earlier, we identified a 5' --> 3' exonuclease activity that copurified with yeast DNA polymerase alpha-primase in a multiprotein complex [Biswas, E. E., et al. (1993) Biochemistry, 32, 3020-3027]. Peptide sequence analysis of the purified 47 kDa exonuclease was carried out, and the peptide sequence was found to be identical to the S. cerevisiae gene YKL510 encoded polypeptide, which is also known as yeast RAD2 homolog 1 or RTH1 nuclease. The native exonuclease also had strong flap endonuclease activity similar to that observed with RTH1 nuclease and homologous yeast (RAD2) and mammalian enzymes. During our studies, we have discovered certain unique features of the mechanism of action of the native RTH1 nuclease. Studies presented here indicated that the exonuclease had specific pause sites during its 5'-3' exonuclease nucleotide excision. These pause sites were easily detected with long (approximately 50 bp) oligonucleotide substrates during exonucleolytic excision by the formation of a discontinuous ladder of excision product. We have further analyzed the mechanism of generation of the pause sites, as they could occur through a number of different pathways. Alignment of the pause sites with the nucleotide sequence of the oligonucleotide substrate indicated that the pause sites were dependent on the nucleotide sequence. Our analysis revealed that RTH1 nuclease pauses predominantly at G:C rich sequences. With poly(dA):oligo(dT)50 as substrate, the exonucleolytic products formed a continuous ladder with no evidence of pausing. The G:C rich DNA sequences are thermodynamically more stable than the A:T rich sequences, which may be in part responsible for pausing of the RTH1 5' --> 3' exonuclease at these sites.

Origin and modulation of ACh release from rat airway cholinergic nerves

The release of acetylcholine (ACh) from airway parasympathetic nerves was studied in rat trachea. We established stimulus parameters, examined the role of extracellular Ca2+, and investigated the origin of the released ACh by use of vesamicol, an inhibitor of ACh uptake in synaptic vesicles. The role of muscarinic autoreceptors and prostanoids on ACh release was also studied. Tracheal rings were incubated in Krebs-Henseleit solution containing neostigmine and guanethidine with or without atropine. ACh release was measured by high-performance liquid chromatography with electrochemical detection. ACh release was dependent on frequency (0.5-16 Hz), voltage (10-25 V), and pulse duration (0.5-4 ms). At 4 Hz, one-fifth of electrical field stimulation-induced ACh release was extracellular Ca2+ independent and vesamicol resistant, indicating its nonvesicular origin. Three-fifths were Ca2+ dependent and vesamicol sensitive, indicating that it was newly synthesized, and one-fifth was Ca2+ dependent but vesamicol resistant, indicating its origin from prestored vesicles. At 16 Hz, two-fifths were nonvesicular and three-fifths were newly synthesized. Blockade of the muscarinic autoreceptor by atropine potentiated the release of ACh four- to fivefold. Neither of the cyclooxygenase inhibitors indomethacin or meclofenamate nor exogenous prostaglandin E2 affected ACh release, indicating that inhibitory prostanoids do not modulate ACh release.

A baculovirus vector derived from immediately early gene promoter of Autographa californica nuclear polyhedrosis virus

A transfer vector was constructed in which the neomycin resistance (neo) gene was under the control of a copy of Autographa californica nuclear polyhedrosis virus (AcMNPV) IE1 gene promoter at the p10 locus. After cotransfection of Spodoptera frugiperda (Sf9) cells with the transfer vector and infectious AcMNPV DNA, the recombinant virus-containing neo gene was selected by serial passage of the mixed progenies from cotransfection. This was done at low MOI in the presence of G418 in growth medium and was followed by limited dilution. RNA dot hybridization showed that the neo gene was transcribed from immediately early phase to very late phase, in infected Sf9 cells. These results demonstrate that a new baculovirus vector system had been constructed in infected cells. Furthermore, a new method for selection of positive recombinant baculovirus had been developed.

Excitatory prejunctional beta 2-adrenoceptor distribution within equine airway cholinergic nerves

We examined the effect of activation of beta 2-adrenoceptor (AR) by isoproterenol (ISO) on acetylcholine (ACh) release evoked by electrical field stimulation (EFS: 20 V, 0.5 Hz, 0.5 msec) from cholinergic nerves in five regions of equine airways. We also tested if the effect of ISO was dependent on epithelium or prostanoids by examining the effect of ISO on ACh release in the presence and absence of epithelium or cyclooxygenase inhibition. Trachealis strips or bronchial rings were preincubated for 60 min with 10(-7) M atropine, 10(-6) M neostigmine, and 10(-5) M guanethidine. The ACh amount was measured by high-performance liquid chromatography with electrochemical detection. Isoproterenol (10(-8)-10(-6) M) augmented ACh release throughout the whole airway in a concentration-dependent manner. Rubbing off the epithelium potentiated EFS-induced ACh release but neither epithelium removal nor cyclooxygenase inhibition affected the magnitude of ISO-induced augmentation of ACh release. These results indicate that in equine airway parasympathetic nerves: (1) excitatory prejunctional beta 2-adrenoceptors are distributed throughout the tracheobronchial tree; (2) the function of this excitatory beta 2-adrenoceptor is independent of endogenous prostanoids and epithelium; and (3) there is an epithelium-derived factor that inhibits ACh release.

Potentiation of acetylcholine release from tracheal parasympathetic nerves by cAMP

We tested the hypothesis that increasing intracellular levels of adenosine 3', 5'-cyclic monophosphate (cAMP) increases acetylcholine (ACh) release from airway parasympathetic nerves. Muscle strips from equine trachea were preincubated for 60 min with 10(-7)M atropine, 10(-6)M neostigmine, and 10(-5) M guanethidine. The ACh release was evoked by electrical field stimulation (EFS, 20 V, 0.5 ms, 0.5 Hz) and measured by high-performance liquid chromatography with electrochemical detection. Agents known to increase cAMP, i.e., forskolin (10(-6) - 10(-4) M), 8-bromoadenosine 3', 5'-cyclic monophosphate (8-BrcAMP; 10(-5)-10(-3) M), and 3-isobutyl-1-methylxanthine (IBMX ; 10(-5)-10(-3)M) was potentiated by IBMX but not mimicked by 1,9 dideoxyforskolin. To determine if the augmentation of Ach release facilitated EFS-induced ACh release in a concentration-dependent manner. Forskolin-induced augmentation of ACh release induced by activation of beta 2-adrenoceptors is mediated via cAMP-dependent pathways, we also examined the additive effects of 8-BrcAMP, forskolin, and IBMX with 10(-6)M isoproterenol (ISO), the concentration that maximally augments ACh release. Neither forskolin nor 8-BrcAMP potentiated the maximal augmentation produced by ISO, but inhibition of phosphodiesterase with IBMX (10(-4) and 10(-3)M) augmented the maximal effect of ISO. These observations indicate that neuronal cAMP is a physiological modulator of ACh release from airway parasympathetic nerves and mediates ISO-induced augmentation of ACh release. Bronchodilators that increase cAMP may therefore paradoxically augment ACh release while relaxing smooth muscle.