Optical properties of a new two-photon absorbing chromophore

A new dye, trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridinium iodide, has been synthesized, and the two-photon-absorption (TPA), TPA-induced frequency upconversion emission, and two-photon-pumped (TPP) frequency upconverted lasing properties of this new dye were experimentally studied. This new dye has a moderate TPA cross section of varsigma(2) = 5.7 x 10(-48) (cm(4) s(-1))/photon at 1064 nm but exhibits high lasing efficiency. The slope efficiency of the TPP cavity laser with this new dye as the laser medium is 1.6%.

[Indomethacin induces apoptosis of K562 cells through activation of caspases and elevation of intracellular free calcium]

OBJECTIVE

To investigate the indomethacin (IN) induced apoptosis of K562 cells: (1) the expression, activation and subcellular localization of caspase-3 and -8; (2) the change of intracellular free calcium concentration ([fCa(2+)]i) and its mechanism; and (3) whether the cell apoptosis is cyclooxygenase (cox) dependent or not.

METHODS

Changes and subcellular localization of caspase-3 and -8 were observed by laser scanning confocal microscopy (LSCM); expression and activation of caspase-3 and -8 proteins by Western blotting; changes of intracellular [fCa(2+)]i by LSCM coupling with a calcium-fluorescence probe and calcium chelator EGTA blocking test; and cox inhibitor effect by MTT assay.

RESULTS

(1) LSCM assay and Western blotting showed that caspase-3 and -8 localized in cytoplasm and nucleus dispersedly and spottedly and were upregulated with the increasing of IN doses. Western blotting also showed the cleavage and activation of caspase-3 and -8 during IN-induced apoptosis. (2) The increase of [fCa(2+)]i in K562 cells was parallel to the increase of IN concentration regardless of the presence or absence of EGTA. But with EGTA treatment, [fCa(2+)]i was much less than that without EGTA treatment. (3) Low dose of IN or other cox inhibitors could not exert cytotoxic effects on K562 cells whereas high dose of IN could.

CONCLUSION

(1) The upregulation and activation of caspase-3 and -8 play a fundamental role in apoptosis induced by IN in K562 cells. Both cytoplasm and nucleus are locations where caspase-3 and -8 localized. (2) The increase of [fCa(2+)]i may be critical in the modulation of apoptosis; the extracellular calcium influx is the main source of the elevation of [fCa(2+)]i in K562 cells and can be blocked by the calcium chelator EGTA;the release of calcium from intracellular calcium store is also an important source of the intracellular calcium which can trigger apoptosis without the extracellular calcium influx. (3) Apoptosis of K562 cells induced by IN is cox-independent.

[Isolation of high-quality genomic DNA from plants]

In order to isolate high-quality genomic DNA from medicinal plant tissues enriching polyphenols and polysaccharides, a simple and rapid method based on CTAB extraction for isolating high-quality intact DNA was established by modifying several existing methods. With this technique, the absorbance ratio (A260/A280) of DNAs obtained from fresh and/or dried roots of Panax ginseng, P. Quinquefolius and P. notoginseng was 1.8 approximately. The restriction fragments of DNAs were directly digested with restriction enzyme (EcoR I/Mse I), linked up by T4 DNA ligase and amplified by nested PCR. Reproducible amplified fragment length polymorphism (AFLP) genomic DNA fingerprinting profiles were established with the isolated DNAs. The results demonstrate that the modified technique may be efficient and reliable in isolating high-quality and high-molecular-weight DNAs from fresh and/or dried medicinal plants containing a high content of polyphenols and polysaccharides. We expect that this method can also be applied to other plants.

Facilitation of acetylcholine release and improvement in cognition by a selective M2 muscarinic antagonist, SCH 72788

Current treatment of Alzheimer's Disease (AD) requires acetylcholinesterase inhibition to increase acetylcholine (ACh) concentrations in the synaptic cleft. Another mechanism by which ACh levels can be increased is blockade of presynaptic M2 muscarinic autoreceptors that regulate ACh release. An antagonist designed for this purpose must be highly selective for M2 receptors to avoid blocking postsynaptic M1 receptors, which mediate the cognitive effects of ACh. Structure-activity studies of substituted methylpiperadines led to the synthesis of 4-[4-[1(S)-[4-[(1,3-benzodioxol-5-yl)sulfonyl]phenyl]ethyl]-3(R)-methyl-1-piperazinyl]-4-methyl-1-(propylsulfonyl)piperidine. This compound, SCH 72788, binds to cloned human M2 receptors expressed in CHO cells with an affinity of 0.5 nM, and its affinity at M1 receptors is 84-fold lower. SCH 72788 is a functional M2 antagonist that competitively inhibits the ability of the agonist oxotremorine-M to inhibit adenylyl cyclase activity. In an in vivo microdialysis paradigm, SCH 72788 increases ACh release from the striatum of conscious rats. The compound is also active in a rodent model of cognition, the young rat passive avoidance response paradigm. The effects of SCH 72788 suggest that M2 receptor antagonists may be useful for treating the cognitive decline observed in AD and other dementias.

Muscarinic agonists and antagonists in the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment and personality changes. The development of drugs for the treatment of the cognitive deficits of AD has focused on agents which counteract loss in cholinergic activity. Although symptoms of AD have been successfully treated with acetylcholinesterase inhibitors (tacrine, donepezil. rivastigmine, galanthamine), limited success has been achieved with direct M1 agonists, probably due to their lack of selectivity versus other muscarinic receptor subtypes. Muscarinic M2 antagonists have been reported to increase synaptic levels of acetylcholine after oral administration to rats (e.g. BIBN-99, SCH-57790), but their selectivity versus other muscarinic receptor subtypes is modest. Exploration of a series of piperidinylpiperidines has yielded the potent and selective M2 antagonist SCH-217443. This antagonist has excellent bioavailability in rats and dogs and shows activity in a rat model of cognition.

Organization of uroplakin subunits: transmembrane topology, pair formation and plaque composition

The apical surfaces of urothelial cells are almost entirely covered with plaques consisting of crystalline, hexagonal arrays of 16 nm uroplakin particles. Although all four uroplakins, when SDS-denatured, can be digested by chymotrypsin, most uroplakin domains in native urothelial plaques are resistant to the enzyme, suggesting a tightly packed structure. The only exception is the C-terminal, cytoplasmic tail of UPIII (UPIII) which is highly susceptible to proteolysis, suggesting a loose configuration. When uroplakins are solubilized with 2% octylglucoside and fractionated with ion exchangers, UPIa and UPII were bound as a complex by a cation exchanger, whereas UPIb and UPIII were bound by an anion exchanger. This result is consistent with the fact that UPIa and UPIb are cross-linked to UPII and UPIII, respectively, and suggests that the four uroplakins form two pairs consisting of UPIa/II and UPIb/III. Immunogold labelling using a new mouse monoclonal antibody, AU1, revealed that UPIII is present in all urothelial plaques, indicating that the two uroplakin pairs are not segregated into two different types of urothelial plaque and that all plaques must have a similar uroplakin composition. Taken together, these results indicate that uroplakins form a tightly packed structure, that the four uroplakins interact specifically forming two pairs, and that both uroplakin pairs are required for normal urothelial plaque formation.

The pattern of gene expression in human CD15+ myeloid progenitor cells

We performed a genome-wide analysis of gene expression in primary human CD15(+) myeloid progenitor cells. By using the serial analysis of gene expression (SAGE) technique, we obtained quantitative information for the expression of 37,519 unique SAGE-tag sequences. Of these unique tags, (i) 25% were detected at high and intermediate levels, whereas 75% were present as single copies, (ii) 53% of the tags matched known expressed sequences, 34% of which were matched to more than one known expressed sequence, and (iii) 47% of the tags had no matches and represent potentially novel genes. The correct genes were confirmed by application of the generation of longer cDNA fragments from SAGE tags for gene identification (GLGI) technique for high-copy tags with multiple matches. A set of genes known to be important in myeloid differentiation were expressed at various levels and used different spliced forms. This study provides a normal baseline for comparison of gene expression in myeloid diseases. The strategy of using SAGE and GLGI techniques in this study has broad applications to the genome-wide identification of expressed genes.

[Analysis on the sex ratios at birth for deliveries in hospitals in China from 1987 to 1992]

OBJECTIVE

To estimate the sex ratios at birth (SRB) for livebirths in hospitals in China.

METHODS

Data were collected by the birth defects monitoring network. The livebirths with gestation of 28 weeks or over delivered in hospitals of 30 provinces, municipalities and autonomous regions all over the country from 1987 to 1992 were analyzed and used for calculating the SRB.

RESULTS

The high male bias in SRB was observed in the data from most areas, and there was an upward trend of SRB, especially in rural areas. The SRB for livebirths in the hospitals of urban areas was normal from 1987 to 1989, and rose to 108.9 in 1992. The SRB for rural areas was high and was 109.9 in 1987, and rose to 111.8 in 1992. The SRB for livebirths given by the mothers under 20 years of age and coming from lower educational background was higher than that for others. The SRB for higher parities was even higher.

CONCLUSION

The SRB in China is high; this is possibly related to sex-preference. Under-reporting of female neonates and "missing females" are not the main causes of the rising SRB.

[A multi-centered clinical study an domestic intravenous Turbutalin sulfate in the treatment of asthma and chronic asthmatic bronchitis]

OBJECTIVE

This multi-centered clinical trial was designed to assess the efficacy and safety of domestic intravenous Turbutalin Sulfate in the treatment of asthma and chronic asthmatic bronchitis.

METHODS

Bricanyl was used as control. A total of 120 patients were included in this randomized controlled study. The two medications, both at a dose of 0.25 mg intravenous drip, were given three times a day for 3-5 days.

RESULTS

The two drugs' clinical excellent rates were 66.7% and 73.3%; overall efficacy rates were 98.3% and 100.0%, respectively. Their pulmonary functional excellent rates were 78.4% and 76.6%; overall effect rates were 88.3% and 90.0%, respectively. Composite curative evaluation showed that the two drug's composite excellent rates were 61.6% both; their overall efficacy rates were 88.3% and 90.0%, respectively. All of these showed no significant difference (P > 0.05). The incidence rates of adverse side effects of the two groups were 13.5% and 15.0%, respectively; most of them were mild and tolerable.

CONCLUSION

Domestic intravenous Terbutalin Sulfate is effective and safe in treating asthma and chronic asthmatic bronchitis.

Regulation of glomerular basement membrane collagen expression by LMX1B contributes to renal disease in nail patella syndrome

Basement membrane (BM) morphogenesis is critical for normal kidney function. Heterotrimeric type IV collagen, composed of different combinations of six alpha-chains (1-6), is a major matrix component of all BMs (ref. 2). Unlike in other BMs, glomerular BM (GBM) contains primarily the alpha 3(IV) and alpha 4(IV) chains, together with the alpha 5(IV) chain. A poorly understood, coordinated temporal and spatial switch in gene expression from ubiquitously expressed alpha 1(IV) and alpha 2(IV) collagen to the alpha 3(IV), alpha 4(IV) and alpha 5(IV) chains occurs during normal embryogenesis of GBM (ref. 4). Structural abnormalities of type IV collagen have been associated with diverse biological processes including defects in molecular filtration in Alport syndrome, cell differentiation in hereditary leiomyomatosis, and autoimmunity in Goodpasture syndrome; however, the transcriptional and developmental regulation of type IV collagen expression is unknown. Nail patella syndrome (NPS) is caused by mutations in LMX1B, encoding a LIM homeodomain transcription factor. Some patients have nephrosis-associated renal disease characterized by typical ultrastructural abnormalities of GBM (refs. 8,9). In Lmx1b(-/-) mice, expression of both alpha(3)IV and alpha(4)IV collagen is strongly diminished in GBM, whereas that of alpha1, alpha2 and alpha5(IV) collagen is unchanged. Moreover, LMX1B binds specifically to a putative enhancer sequence in intron 1 of both mouse and human COL4A4 and upregulates reporter constructs containing this enhancer-like sequence. These data indicate that LMX1B directly regulates the coordinated expression of alpha 3(IV) and alpha 4(IV) collagen required for normal GBM morphogenesis and that its dysregulation in GBM contributes to the renal pathology and nephrosis in NPS.

[Study on diarrhea disease and Escherichia coli strains harboring HPI pathogenicity island of Yersinia enterolitica in Shandong province]

OBJECTIVE

It was found that some E. coli strains previously identified as entero SLTs-producing and invasive E. coli (ESIEC), harboring HPI pathogenicity island of Yersinia enterolitica. This research was designed to reveal prevalence, susceptible group and clinical features it caused.

METHODS

All of the diarrhea patients were from the out-patient units of four hospitals in Shandong province from June to November of 1997. Stool specimen were collected before administration of antibiotics for isolation of enteric bacterial pathogen. Clinical symptoms were recorded at the same time.

RESULTS

A total number of 449 enteric pathogenic bacteria strains were detected among stool samples from 671 patients, with isolation rates of Shigella species and diarrheagenic E. coli 25.48% and 15.05% respectively. When irp-2 and ipaB gene fragments were used as DNA probes, 42 of 176 un-identifiable strains were found irp-2(+) and ipaB(-), which were identified as HPI-harboring E. coli. Typical symptoms of the diarrhea caused by HPI-harboring E. coli were described as mild, including abdominal pain, shiver and vapidity. Temperature of the patients was usually normal. Over 6 times of bowel movements per day was frequently observed, of which most were unformed stools with mucous.

CONCLUSION

HIP-harboring E. coli was an important diarrheagenic pathogen identified from 671 patients with diarrhea. Shigella was found to be the majority strain.

Platelet monoamine oxidase B and plasma beta-phenylethylamine in Parkinson's disease

OBJECTIVE

To evaluate the correlation between changes in platelet monoamine oxidase type B (MAO-B) activity and plasma beta-phenylethylamine (PEA) concentrations in patients with Parkinson's disease and controls.

METHODS

Platelet MAO-B activity and plasma PEA were measured with gas chromatography-mass spectrometry (GC-MS) in patients with Parkinson's disease treated with levodopa (12 men and 12 women) or selegiline (three men and three women), and physically healthy subjects as a control group (10 men and 10 women).

RESULTS

Platelet MAO-B activity was significantly higher in the Parkinson's disease group (mean 542 (SD 318) pmol/10(7) platelets/30 min) than in the control group (mean 349 (SD 307) pmol/10(7) platelets/30 min) (p<0.05). By contrast, the plasma PEA concentrations in patients with Parkinson's disease were significantly lower than in the control group (mean 532 (SD 243) pg/ml; 931 (SD 560) pg/ml) (p<0.01). The plasma PEA concentrations in patients with Parkinson's disease treated with selegiline were prominently higher than in patients with no selegiline treatment (p<0.001). There was a significantly negative correlation between platelet MAO-B activity and plasma PEA concentrations in patients (n=24, r=-0.466, p<0.001).

CONCLUSIONS

The increase in platelet MAO-B activity and decrease in plasma PEA concentrations in patients with Parkinson's disease may be involved in the pathophysiological processes of the disease, and these changes are reversed by treatment with selegiline.

[Analysis on ecophysiological characteristics of leaf photosynthesis of Aneurolepidium chinense in songnen grassland]

A series of physiological characteristics of leaf photosynthesis and environmental factors are measured on Aneurolepidium chinense in Songnen salinized grassland during the growth season. The results showed that the daily change pattern of net photosynthetic rate (Pn) of Aneurolepidium chinense could be expressed as a two-humped curve, the daily change pattern of transpiration rate is one-humped curve. In addition, net photosynthetic rate (Pn), transpiration rate (E) and stomatal resistance (Rs) are affected by various environmental factors. At different growth stage, the influence of environmental factor on them is different, and even the same environmental factor had an different effect on Pn, E and Rs. In the whole growth period, photosynthetic available radiation (PAR) was the most intensive effect on the photosynthesis of Aneurolepidium chinense. Among Pn, E and Rs, E was one of the most obvious ecophysiological factor affected by environmental factors.

Genetic dissection of the olfactory bulbs of mice: QTLs on four chromosomes modulate bulb size

Olfaction is influenced by a complex mix of environmental and genetic factors that modulate the production, migration, and maturation of cells in the olfactory bulbs. In this study we analyzed effects of sex, age, body weight, and brain weight on olfactory bulb size in sexually mature mice. We then used regression corrected values (residuals) to map quantitative trait loci (QTLs) that selectively modulate bulb weight. This biometric analysis has relied on an F2 intercross between C57BL/6J (B6) and DBA/2J (D2) inbred strains and a large sample of 35 BXD recombinant inbred (RI) strains. Bilateral bulb weight in adult mice ranges from 10 to 30 mg. Half of this remarkable variation can be predicted from differences in brain weight, sex, body weight, and age. A 100-mg difference in brain weight is associated with a 4.4-mg difference in bulb weight. Bulbs gain in weight by 0.2 mg/week--a 1% increase that continues until at least 300 days of age. Males tend to have slightly larger bulbs than females. By combining data from both related crosses (F2 and RI) we identified four QTLs with selective effects on bulb size (genomewide p < .05). Bulb4a is located on chromosome 4 (Chr 4) and Bulb6a is located on Chr 6. Alleles inherited from B6 at both of these loci increase bulb weight by 0.5-1.0 mg. Bulb11a is located on proximal Chr 11 and Bulb17a is located on the proximal part of Chr 17. In contrast to the first two QTLs, B6 alleles at these two loci decrease bulb weight by 0.5-1.0 mg. Collectively, the four loci account for 20% of the phenotypic variance in bulb weight.

Development of a fungus-specific PCR assay for detecting low-level fungi in an indoor environment

A fungus-specific PCR assay using only one primer set has been developed for detecting indoor fungi. Four fungal primer sets, NS3/NS4, NS5/NS6, FF1/FR1 and FF2/FR1, were tested with DNA from humans, rats, mice, bacteria, pollens and six commonly found fungal species (Alternaria chamydospora, Aspergillus flavus, Candida famata, Cladosporium fermentans, Penicillium chrycoIgenum and Stachybotrys chartarum). Results indicated that, although all four primer sets could amplify the fungal DNA, only FF2/FR1 demonstrated no cross-amplification with non-fungal DNA. In addition, these amplified fragments were sequenced to ensure that they indeed matched known fungal DNA sequences. Furthermore, besides the tested fungi, eighteen more genera of fungal sequences were examined and found to match the FF2/FR1. Here, the method of bead-beating was identified as the most effective way for spore breakage and fungal DNA release. The PCR amplification efficiency and potential inhibition were examined using different process solutions and preparation procedures. It was found that, when using 20% nutrient media and homogenization-first procedure, a higher amplification efficiency with less inhibition was achieved. Although positive bands were observed at 0.2 fungal spore/reaction using the homogenization-first procedure, the sensitivity of this assay would be two fungal spores/reaction for environmental samples.

Interleukin-12 induces gene expression in interleukin-2 stimulated human T lymphocytes

IL-12 is a critical immunoregulatory cytokine that promotes cell-mediated immune responses by inducing the differentiation of Th1 cells. To better clarify the molecular basis of IL-12 action, we compared the gene expression in human T lymphocytes activated by IL-2 and IL-12. mRNAs from T lymphocytes activated by either IL-2 alone or IL-2 plus IL-12 were transcribed into cDNAs. A differential mRNA display was conducted. As a result, differential display of five cDNA fragments was obtained. Sequence analysis suggests that they had high homology with recorded genes as found by a computer search against GenBank. Two full genes of the five fragments were cloned, which activation-induced C-type lectin and glucose transporter-like protein. Interestingly, these proteins were expressed in the T cells stimulated by IL-2 and IL-12, but not in the T cells stimulated by IL-2 alone. These results suggest that C-type lectin and glucose transporter-like protein may play an important role in the T lymphocyte activation induced by IL-12.

[Dynamic changes of respiration pathway and active oxygen levels in subcultured tobacco callus]

During the growth and senescence of tobacco callus, the total respiration rate showed two peaks on the 11th and 19th day, respectively. The development and operation of alternative pathway increased gradually, reached the maximum between two respiration peaks, and then declined in the following days, but the cytochrome pathway was still as a main electron transport pathway consistently. Analysis on the levels of active oxygen species during the growth and senescence process in tobacco callus suggested that H2O2 and O2.- were involved in some way in the induction of the development and operation of the alternative pathway, but the increase of production rate of OH might suppress both the development and operation of the alternative pathway, which were enhanced by H2O2 and O2.- respectively. These results were further proved by the use of active oxygen scavengers. The possible participation of the alternative pathway enhanced by active oxygen in the initial senescence process was discussed.

[Dynamics of respiration pathway in transgenic salt-tolerant wheat and its receptor under salt stress]

Using transgenic salt-tolerant wheat 89122 and its receptor Longchun 13 as test material, the dynamic changes of respiration pathway of wheat seedlings at different salt concentration were studied. The appearance of salt respiration was later in 89122 than in Longchun 13. The changes of Valt and rho Valt of both varieties had different patterns during salt stress process. Valt was suppressed by high salt levels, but could be induced by low salt levels in Longchun 13. The rho Valt and rho' Vcyt of two varieties were cooperatively regulated with each other to adapt to salt stress, and rho' Vcyt was the main electron transport pathway. The possible physiological roles of cyanide-resistant respiration were also discussed. It was suggested that the operation intensity of cyanide-resistant respiration could serve as a physiological index of plant salt-tolerance.

[Effect of combined treatment of 60Co gamma-ray and EMS on antioxidase activity and ODAP content in Lathyrus sativus]

Lathyrus sativus seeds were treated with 60Co gamma-ray and EMS(ethyl methane sulfonate), and their emergence rate and SOD, POD and CAT activities were determined. The result indicated that the treatment decreased the emergence rate. The activities of SOD and POD were changed in accordance with the increase of irradiation dose and EMS concentration, while that of CAT had no obvious change. After treatment, the ODAP content in Lathyrus sativus decreased. Amutant was developed, with toxin content of 0.1%, compared to 0.2% in control.

Glycoprotein D or J delivered in trans blocks apoptosis in SK-N-SH cells induced by a herpes simplex virus 1 mutant lacking intact genes expressing both glycoproteins

We have made two stocks of a herpes simplex virus 1 mutant lacking intact U(S)5 and U(S)6 open reading frames encoding glycoproteins J (gJ) and D (gD), respectively. The stock designated gD(-/+), made in cells carrying U(S)6 and expressing gD, was capable of productively infecting cells, whereas the stock designated gD(-/-), made in cells lacking viral DNA sequences, was known to attach but not initiate infection. We report the following. (i) Both stocks of virus induced apoptosis in SK-N-SH cells. Thus, annexin V binding to cell surfaces was detected as early as 8 h after infection. (ii) U(S)5 or U(S)6 cloned into the baculovirus under the human cytomegalovirus immediate-early promoter was expressed in SK-N-SH cells and blocked apoptosis in cells infected with either gD(-/+) or gD(-/-) virus, whereas glycoprotein B, infected cell protein 22, or the wild-type baculovirus did not block apoptosis. (iii) In SK-N-SH cells, internalized, partially degraded virus particles were detected at 30 min after exposure to gD(-/-) virus but not at later intervals. (iv) Concurrent infection of cells with baculoviruses did not alter the failure of gD(-/-) virus from expressing its genes or, conversely, the expression of viral genes by gD(-/+) virus. These results underscore the capacity of herpes simplex virus to initiate the apoptotic cascade in the absence of de novo protein synthesis and indicate that both gD and gJ independently, and most likely at different stages in the reproductive cycle, play a key role in blocking the apoptotic cascade leading to cell death.

Expression, purification, and characterization of gp160e, the soluble, trimeric ectodomain of the simian immunodeficiency virus envelope glycoprotein, gp160

The envelope glycoprotein, gp160, of simian immunodeficiency virus (SIV) shares approximately 25% sequence identity with gp160 from the human immunodeficiency virus, type I, indicating a close structural similarity. As a result of binding to cell surface CD4 and co-receptor (e.g. CCR5 and CXCR4), both SIV and human immunodeficiency virus gp160 mediate viral entry by membrane fusion. We report here the characterization of gp160e, the soluble ectodomain of SIV gp160. The ectodomain has been expressed in both insect cells and Chinese hamster ovary (CHO)-Lec3.2.8.1 cells, deficient in enzymes necessary for synthesizing complex oligosaccharides. Both the primary and a secondary proteolytic cleavage sites between the gp120 and gp41 subunits of gp160 were mutated to prevent cleavage and shedding of gp120. The purified, soluble glycoprotein is shown to be trimeric by chemical cross-linking, gel filtration chromatography, and analytical ultracentrifugation. It forms soluble, tight complexes with soluble CD4 and a number of Fab fragments from neutralizing monoclonal antibodies. Soluble complexes were also produced of enzymatically deglycosylated gp160e and of gp160e variants with deletions in the variable segments.

The performance and design of ultrasonic vibration system for flexural mode

The matrix method for analyzing flexural vibration system is outlined. The displacement, stress and velocity gain of ultrasonic flexural vibration systems are investigated by transfer matrix method. A design method is given for flexural transducer and vibration system.

Transgenic plants expressing cationic peptide chimeras exhibit broad-spectrum resistance to phytopathogens

Here we describe a strategy for engineering transgenic plants with broad-spectrum resistance to bacterial and fungal phytopathogens. We expressed a synthetic gene encoding a N terminus-modified, cecropin-melittin cationic peptide chimera (MsrA1), with broad-spectrum antimicrobial activity. The synthetic gene was introduced into two potato (Solanum tuberosum L.) cultivars, Desiree and Russet Burbank, stable incorporation was confirmed by PCR and DNA sequencing, and expression confirmed by reverse transcription (RT)-PCR and recovery of the biologically active peptide. The morphology and yield of transgenic Desiree plants and tubers was unaffected. Highly stringent challenges with bacterial or fungal phytopathogens demonstrated powerful resistance. Tubers retained their resistance to infectious challenge for more than a year, and did not appear to be harmful when fed to mice. Expression of msrA1 in the cultivar Russet Burbank caused a striking lesion-mimic phenotype during leaf and tuber development, indicating its utility may be cultivar specific. Given the ubiquity of antimicrobial cationic peptides as well as their inherent capacity for recombinant and combinatorial variants, this approach may potentially be used to engineer a range of disease-resistant plants.