Molecular Markers Improve Abiotic Stress Tolerance in Crops: A Review

Plants endure many abiotic stresses, such as temperature (heat or frost), drought, and salt. Such factors are primary and frequent stressors that reduce agriculture crop yields. Often alterations in nutrient management and constituents, along with variations in biosynthetic capacity, ultimately reduce or halt plant growth. Genetically, stress is an environmental condition that interferes with complete genetic expression. A vast range of molecular genomic markers is available for the analysis of agricultural crops. These markers are classified into various groups based on how the markers are used: RAPD (Random amplified polymorphic DNA) markers serve to identify and screen hybrids based on salinity and drought stress tolerance, while simple sequence repeat (SSR) markers are excellent for the assessment of stress tolerance. Such markers also play an important role in the QTL (Quantitative trait loci) mapping of stress-related genes. Dehydrins for drought and saltol for salinity stresses are primitive genes which regulate responses to these conditions. Further, a focus on traits using single-gene single nucleotide polymorphisms (SNP) markers supports genetic mapping and the sequencing of stress-related traits in inbred lines. DNA markers facilitate marker-assisted breeding to enhance abiotic stress tolerance using advanced techniques and marker modification.

Error-compensating kinetic method for enzymatic determination of DNAs

We describe the adaptation and evaluation of an error-compensating method for kinetic determinations of deoxyribonucleic acids (DNAs). The DNA is first reacted with ethidium bromide to produce a fluorescent intercalation complex. Subsequent treatment of the complex with DNase catalyzes hydrolysis of the DNA, causing a time-dependent decrease in fluorescence, which is monitored. A model for two-component parallel first-order processes is fit to the decay curve to predict the total change in fluorescence expected if the process were monitored to equilibrium. The predicted change in fluorescence response varies linearly with DNA concentration with an intercept corresponding to 0.13 mg/L DNA. Results by the predictive method are 47-, 58-, and 250-fold less dependent on DNase activity, temperature, and ethidium bromide concentration, respectively, than are results for an initial-rate method utilizing the same data. Moreover, the predictive method yields a significantly wider linear range than the initial-rate method, and is much less affected by blank fluorescence and RNA interference than is an equilibrium method based on the reaction of DNA with ethidium bromide alone.

Silencing of the phytoene desaturase (PDS) gene affects the expression of fruit-ripening genes in tomatoes

BACKGROUND

Past research has shown that virus-induced phytoene desaturase (PDS) gene silencing via agroinjection in the attached and detached fruit of tomato plants results in a pale-yellow fruit phenotype. Although the PDS gene is often used as a marker for gene silencing in tomatoes, little is known about the role of PDS in fruit ripening. In this study, we investigated whether the pepper PDS gene silenced endogenous PDS genes in the fruit of two tomato cultivars, Dotaerang Plus and Legend Summer.

RESULTS

We found that the pepper PDS gene successfully silenced endogenous PDS in tomato fruit at a silencing frequency of 100% for both cultivars. A pale-yellow silenced area was observed over virtually the entire surface of individual fruit due to the transcriptional reduction in phytoene desaturase (PDS), zeta-carotene (ZDS), prolycopene isomerase (CrtlSO), and beta-carotene hydroxylase (CrtR-b2), which are the carotenoid biosynthesis genes responsible for the red coloration in tomatoes. PDS silencing also affected the expression levels of the fruit-ripening genes Tomato AGAMOUS-LIKE1 (TAGL1), RIPENING INHIBITOR (RIN), pectin esterase gene (PE), lipoxygenase (LOX), FRUITFULL1/FRUITFUL2 (FUL1/FUL2), and the ethylene biosynthesis and response genes 1-aminocyclopropane-1-carboxylate oxidase 1 and 3 (ACO1 and ACO3) and ethylene-responsive genes (E4 and E8).

CONCLUSION

These results suggest that PDS is a positive regulator of ripening in tomato fruit, which must be considered when using it as a marker for virus-induced gene silencing (VIGS) experiments in order to avoid fruit-ripening side effects.

Predictors of Non-adherence to Immunosuppressive Therapy in Asian Liver Transplant Recipients

BACKGROUND

Adherence to immunosuppressive medications has been shown to affect post-transplant outcomes. We aimed to determine the level of adherence to immunosuppressive therapy in liver transplant (LT) recipients and to elucidate factors associated with it, as well as patient preferences on the dosing schedule.

METHODS

LT recipients were recruited during transplant clinic follow-up. A validated Morisky 8-item questionnaire was completed by patients to assess their adherence to immunosuppressive therapy. Adherence was determined by the sum of the responses to the questionnaire. Low, medium, and high adherence were defined by a Morisky score of >2, 1 to 2, and 0, respectively. Data on the patient's socio-economic and clinical background, dosing schedule of immunosuppressant medications, and patient preferences were included in the questionnaire.

RESULTS

A total of 107 LT recipients were approached and 75 completed the questionnaire. The majority of patients (48/74, 64.9%) preferred a once-daily medication regimen. The proportion of high adherence was 24/75 (32.0%), medium adherence was 51/75 (42.7%), and low adherence was 19/75 (25.3%). Multivariate analysis showed younger age and post-transplant duration >5 years as independent predictors for low adherence. Among low-adherence patients, 16/19 (84.2%) patients were on a twice-daily regimen, and, of these, 14/16 (87.5%) preferred their medications to be reduced to once daily.

CONCLUSIONS

A significant proportion (68%) of LT recipients had low to moderate adherence to medications, with younger age and longer post-transplant duration of >5 years as independent predictors. Early identification of at-risk patients is essential to allow implementation of measures to improve adherence. Simplifying medication regimens to once daily is a potential way to improve adherence.

Characterization of the role of sodium nitroprusside (SNP) involved in long vase life of different carnation cultivars

BACKGROUND

Sodium nitroprusside (SNP) has been previously shown to extend the vase life of various cut flowers; however, its positive effect on extending vase life of carnations has not been well documented. Moreover, the role of SNP in the mechanisms underlying determination of vase life of cut carnations has also not been well addressed.

RESULTS

SNP increased vase life of Tico Viola carnations along with their relative fresh weight (RFW). Among the treatments, the flowers treated with 10 mg L^-1 SNP had the longest vase life and maximum relative fresh weight (RFW). This was achieved through significant suppression of ethylene production via downregulation of ethylene biosynthesis and petal senescence-related genes, and through an increase in the scavenging mechanism of reactive oxygen species (ROS) by antioxidant activity during flower vase life. In addition, the positive efficacy of SNP could also be confirmed using 1-aminocyclopropane-1-carboxylic acid (ACC) and different cultivars, resulting in similar trends for both experiments.

CONCLUSION

Taken together, these results suggest that SNP plays a crucial role in multiple modes of action that are associated with the longevity of cut carnation flowers.

Overexpression of snapdragon Delila (Del) gene in tobacco enhances anthocyanin accumulation and abiotic stress tolerance

BACKGROUND

Rosea1 (Ros1) and Delila (Del) co-expression controls anthocyanin accumulation in snapdragon flowers, while their overexpression in tomato strongly induces anthocyanin accumulation. However, little data exist on how Del expression alone influences anthocyanin accumulation.

RESULTS

In tobacco (Nicotiana tabacum 'Xanthi'), Del expression enhanced leaf and flower anthocyanin production through regulating NtCHS, NtCHI, NtF3H, NtDFR, and NtANS transcript levels. Transgenic lines displayed different anthocyanin colors (e.g., pale red: T0-P, red: T0-R, and strong red: T0-S), resulting from varying levels of biosynthetic gene transcripts. Under salt stress, the T2 generation had higher total polyphenol content, radical (DPPH, ABTS) scavenging activities, antioxidant-related gene expression, as well as overall greater salt and drought tolerance than wild type (WT).

CONCLUSION

We propose that Del overexpression elevates transcript levels of anthocyanin biosynthetic and antioxidant-related genes, leading to enhanced anthocyanin production and antioxidant activity. The resultant increase of anthocyanin and antioxidant activity improves abiotic stress tolerance.

Elimination of chrysanthemum stunt viroid and chrysanthemum chlorotic mottle viroid from infected chrysanthemum by cryopreservation

Chrysanthemum morifolium 'Borami' and 'Secret Pink' showing symptoms of stunt disease caused by chrysanthemum stunt viroid (CSVd) and 'Yellow Cap' showing chlorotic mottle disease caused by chrysanthemum chlorotic mottle viroid (CChMVd) were confirmed to be infected by the respective viroids by using reverse transcription polymerase chain reaction (RT-PCR). Real-time PCR results showed that the viroid concentrations in the infected cultivars varied between the different regions of origin (Chilgok, Gumi, and Gyeongsan). We applied a cryopreservation protocol for elimination of CSVd from naturally infected 'Borami' collected from Gumi, showing the lowest concentration of CSVd, by varying several factors such as plant vitrification solutions (PVS2 and PVS3), duration of exposure to liquid nitrogen, shoot-tip size, and low-temperature treatment. The solution (PVS2) and low-temperature treatment were found to be critical factors determining the efficacy of viroid elimination. We optimized the protocol by combining of all resulted optimal factors and tested the applicability of the protocol in 'Borami' collected from Chilgok and Gyeongsan and in 'Secret Pink' from Chilgok, Gumi, and Gyeongsan, which displayed different viroid concentrations. We found that the elimination rates varied depending on the cultivar and region of origin. Similar results were observed when the protocol was applied to eliminate CChMVd from the 'Yellow Cap' collected from the same regions. Finally, we found that nested PCR is more reliable for viroid detection than RT-PCR. Overall, cryopreservation can be used to eliminate viroids from infected chrysanthemums; however, the efficacy depends on genotype and initial viroid concentration.

Factors influencing in vitro shoot regeneration from leaf segments of Chrysanthemum

The objective of this research was to develop an efficient protocol for shoot regeneration from leaf segments of the Chrysanthemum cv. Vivid Scarlet by examining the effects of plant growth regulators, dark incubation period, gelling agents, and silver nitrate. The highest number of shoots per explant (12.3) was regenerated from leaf explants cultured on Murashige and Skoog (MS) medium supplemented with a combination of 1 mgL(-1) of 6-benzyladenine (BA) and 2 mgL(-1) of α-naphthaleneacetic acid (NAA) under light conditions without any initial dark period. Gelrite was the most effective gelling agent for shoot regeneration among those tested, whereas the presence of silver nitrate distinctly inhibited shoot regeneration. Superior plant growth and rooting was observed on a hormone-free MS medium solidified with Gelrite. Flow cytometry analysis revealed no ploidy variation between the regenerated plants and the mother plant grown under greenhouse conditions. The established protocol was applicable to shoot regeneration for four out of six cultivars tested. This research will facilitate the genetic transformation and micropropagation of Chrysanthemum cultivars.

First Report of Pyricularia grisea Causing Gray Leaf Spot on Lily in Korea

Lily is an economically important ornamental crop in Korea. In August 2008, severe leaf spot symptoms were observed on an oriental Lily 'Action' in a plant nursery in Daegu, Korea. Disease incidence was 20 to 30%. Initial symptoms were olive green-to-brown lesions on the leaf that developed into tan, elliptical, necrotic lesions. On severely infected leaves, lesions coalesced and killed the entire leaf blade. Infected leaves were surface disinfested with 70% ethanol for 30 s and 2% chlorox for 15 min before plating 1 cm² sections onto potato dextrose agar. Hyphae appeared 5 days after inoculation and pure culture. Conidia were hyaline, transversely septate with one to three septa; most had two. Conidia were obpyriform and measured 29 to 46 μm long and 7 to 17 μm wide. Mycelia morphology and conidia production were consistent with that described previously for Pyricularia grisea (1). Koch's postulates were fulfilled by spraying five, healthy, vegetative-stage plants with 2 × 10⁵ conidia per ml of sterile distilled water plus 0.05% Tween 20. As a control, five similar plants were sprayed with sterile water plus 0.05% Tween 20 only. Plants were placed inside plastic bags to maintain high relative humidity and incubated in a growth chamber at 25°C under fluorescent light for 14 h and at 20°C in darkness for 10 h. After 3 days, the plastic bags were removed and plants were maintained under the same conditions. Initial symptoms were observed 7 days after inoculation. Ten days after inoculation, disease symptoms on inoculated plants were similar to those previously described in the nursery. Control plants did not show any symptoms. Fungi isolated from these lesions had the same morphological characteristics as the ones isolated previously from plants in the nursery. To our knowledge, this is the first report of gray leaf spot on lily caused by P. grisea in Korea. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971.

Genetic diversity among Korean bermudagrass (Cynodon spp.) ecotypes characterized by morphological, cytological and molecular approaches

The genus Cynodon comprises ten species. The objective of this study was to evaluate the genetic diversity of Korean bermudagrasses at the morphological, cytological and molecular levels. Morphological parameters, the nuclear DNA content and ploidy levels were observed in 43 bermudagrass ecotypes. AFLP markers were evaluated to define the genetic diversity, and chromosome counts were made to confirm the inferred cytotypes. Nuclear DNA contents were in the ranges 1.42-1.56, 1.94-2.19, 2.54, and 2.77-2.85 pg/2C for the triploid, tetraploid, pentaploid, and hexaploid accessions, respectively. The inferred cytotypes were triploid (2n = 3x = 27), tetraploid (2n = 4x = 36), pentaploid (2n = 5x = 45), and hexaploid (2n = 6x = 54), but the majority of the collections were tetraploid (81%). Mitotic chromosome counts verified the corresponding ploidy levels. The fast growing fine-textured ecotypes had lower ploidy levels, while the pentaploids and hexaploids were coarse types. The genetic similarity ranged from 0.42 to 0.94 with an average of 0.64. UPGMA cluster analysis and principle coordinate analysis separated the ecotypes into 6 distinct groups. The genetic similarity suggests natural hybridization between the different cytotypes, which could be useful resources for future breeding and genetic studies.

Comparison between high and low molecular weight hyaluronates in knee osteoarthritis patients: open-label, randomized, multicentre clinical trial

Efficacy and safety of high and low molecular weight hyaluronates in knee osteoarthritis patients were compared in a randomized, open-label trial. Patients in the high molecular weight hyaluronate group were treated once weekly for 3 weeks and in the low molecular weight group once weekly for 5 weeks. We evaluated weight-bearing pain, degree of flexion, swelling and knee tenderness; frequency and amount of rescue medication; patient and investigator global assessment of pain, and safety over 12 weeks after final injection of study medication. Significant improvements in pain and WOMAC-Likert scores were observed in both groups, but not between groups. Knee joint pain improvement was noted in both groups by patients and investigators during follow-up. Close correlation was observed between patient- and investigator-reported data. There was no significant difference in side-effects between the groups. In conclusion, the efficacy and safety of high and low molecular weight hyaluronate are similar.

Validity and reliability of the SF-36: the Malaysian context

Results of construct validity and reliability of the SF-36 are described, based on data from a multi-centre study on asthmatics and a population based survey. Questionnaire refinement was carried out between the two studies. Quality of data was good, with all items having less than 0.5% missing values. Floor and/or ceiling effects were observed for REE, REP, PF and SF. For scaling assumptions, correlations between each items and its hypothesized scale were all above 0.50, except for one item in PF. and for both items in SF. Item discriminant validity was an issue for items in VT, SF and MH scales. Cronbach's as for all scales exceeded the recommended 0.70 level, except for SF. Only one latent dimension was identified in principal component analysis, and only 52-53% of variance accounted for. As expected, PF shows high correlations with the physical component while MH was highly correlated with the mental component. Contrasting findings in the loadings of other scales were observed in the asthma data. Age, disease severity and presence of self-reported handicap/disability significantly affect PF, while MH demonstrates no obvious pattern with declining age. In essence, the Malay version of SF-36 could be used in Malaysia, with its generally acceptable internal consistency and validity. The caveat is in the call for additional domains of importance to Malaysians that is not covered by the instrument, and in the caution to be employed when using and construing the instrument.

Atypical presentations of emphysematous cystitis

Emphysematous cystitis is an uncommon infection of the bladder with the formation of carbon dioxide either within the bladder or within its wall. It is commonly seen in women and those with poorly controlled diabetes mellitus, in association with some form of urinary stasis and obstruction. The clinical features are very varied and the outcome is often unpredictable. Radiography may reveal a radiolucent line around the bladder wall or gas within the bladder. Occasionally, computed tomography scans are required to help in the diagnosis due to their atypical presentation with acute abdominal pain. Herein, we report three patients with such a condition who were treated with favourable outcomes. Of the three patients, two had to undergo exploratory laparotomy due to their initial presentations with acute abdomens.

Transurethral resection of prostate (TURP) through the decades--a comparison of results over the last thirty years in a single institution in Asia

INTRODUCTION

This study was conducted to evaluate the results and complications of transurethral resection of prostate (TURP) over the last 30 years in our institution.

MATERIALS AND METHODS

This retrospective study encompasses 3 different eras: 168 patients in the late 70s, 175 patients in the late 80s and 283 patients in the late 90s. All the patients had at least 18 months of follow-up.

RESULTS

The mean age from the 1970s, the 1980s and 1999 were 68.8 years, 69.2 years and 69.4 years respectively. The proportion of patients operated on for acute retention fell from 78.6% (132) in the 1970s, to 54% (96) in the 1980s, and 43% (122) in 1999. The mean resection time was 44.8 minutes in 1989 and 41.8 minutes in 1999. The mean weight of prostate resected was 22.1 g in the 1970s, 24.2 g in 1989 and 22.2 g in 1999. 44% (74) required blood transfusion in the 1970s, with 11% (19) in 1989 and 4% (11) in 1999. There were 2 deaths (acute myocardial infarction and pneumonia) in the 1970s, 1 (pneumonia) in 1989 and no mortality in 1999. There were 4 patients with TURP syndrome in the 1970s, 3 in 1989 and 1 in 1999. The incidence of postoperative urinary tract infection (UTI) was 25% (42) in the 1970s, 16% (29) in 1989 and 6% (17) in 1999.

CONCLUSIONS

As expertise and experience in TURP progress, the complication rates fall, as evidenced by the lower rates of transfusion, TURP syndrome and postoperative UTI in the later series.

Randomised clinical trial of suture compared with adhesive strip for skin closure after HRT implant

To determine which method of skin closure was associated with less bleeding, 250 women were randomly allocated to have either a suture closure (3-0 Dexon II) or an adhesive strip closure (Steri-Strip) following subcutaneous insertion of hormone (HRT) implants. Data were collected via a tested questionnaire and analysed. Significantly, more women in the adhesive strip group recorded postprocedure bleeding (RR = 2.26; 95% CI 1.42-3.60) and considered the bleeding excessive (RR = 4.17; 95% CI 1.18-14.76) and unacceptable (RR = 12.52; 95% CI 1.63-96.19). Pain scores and symptoms of local infection were similar in both groups. Routine use of adhesive strips for implant skin incision closure is not recommended.

Karyotype analysis of Lilium longiflorum and Lilium rubellum by chromosome banding and fluorescence in situ hybridisation

Detailed karyotypes of Lilium longiflorum and L. rubellum were constructed on the basis of chromosome arm lengths, C-banding, AgNO3 staining, and PI-DAPI banding, together with fluorescence in situ hybridisation (FISH) with the 5S and 45S rDNA sequences as probes. The C-banding patterns that were obtained with the standard BSG technique revealed only few minor bands on heterologous positions of the L. longiflorum and L. rubellum chromosomes. FISH of the 5S and 45S rDNA probes on L. longiflorum metaphase complements showed overlapping signals at proximal positions of the short arms of chromosomes 4 and 7, a single 5S rDNA signal on the secondary constriction of chromosome 3, and one 45S rDNA signal adjacent to the 5S rDNA signal on the subdistal part of the long arm of chromosome 3. In L. rubellum, we observed co-localisation of the 5S and 45S rDNA sequences on the short arm of chromosomes 2 and 4 and on the long arms of chromosomes 2 and 3, and two adjacent bands on chromosome 12. Silver staining (Ag-NOR) of the nucleoli and NORs in L. longiflorum and L. rubellum yielded a highly variable number of signals in interphase nuclei and only a few faint silver deposits on the NORs of mitotic metaphase chromosomes. In preparations stained with PI and DAPI, we observed both red- and blue-fluorescing bands at different positions on the L. longiflorum and L. rubellum chromosomes. The red-fluorescing or so-called reverse PI-DAPI bands always coincided with rDNA sites, whereas the blue-fluorescing DAPI bands corresponded to C-bands. Based on these techniques, we could identify most of chromosomes of the L. longiflorum and L. rubellum karyotypes.

Cloning and characterization of a novel pregnancy-induced growth inhibitor in mammary gland

Growth factors and growth inhibitors play crucial roles in the growth regulation and differentiation of mammary epithelial cells. Studies have shown that during pregnancy, with the onset of terminal differentiation, there is a dramatic decrease in the proliferation of the mammary epithelial cells. Here we report the cloning and characterization of a novel pregnancy-induced cDNA, OKL38, from a human ovarian cDNA library. This cDNA encodes for a protein of approximately 34.5 kDa. Tissue distribution studies through Northern analyses revealed the ubiquitous nature of OKL38 transcripts in most tissues, with the highest levels observed in the ovary, kidney, and liver. The onset and advancement of pregnancy also gave rise to a concomitant increase in OKL38 gene expression. In situ hybridization revealed that OKL38 mRNA was further detected in mammary secretory epithelial cells. However, low levels of OKL38 transcripts were observed in the various human breast cancer cell lines studied and were barely detectable in all dimethylbenz(A)anthracene-induced mammary tumors examined. Transfection studies with OKL38 cDNA with MCF-7 cells resulted in growth inhibition in vitro and reduction in tumor formation in vivo. These observations led to speculation that OKL38 may play a vital role in the growth regulation and differentiation of breast epithelial cells during pregnancy and its implications in tumorigenesis.

Induction of UO-44 gene expression by tamoxifen in the rat uterus and ovary

A complementary DNA, uterine-ovarian-specific gene 44 (UO-44), has been isolated from tamoxifen-induced rat uterine complementary DNA library using differential display techniques. UO-44 transcripts are found to be abundant in the uterus and ovary. UO-44 gene expression in the uterus is strictly regulated by estrogens, tamoxifen, and GH, whereas the pure antiestrogen ICI 182780 is inhibitory. Treatment of ovariectomized rats and hypophysectomized rats with tamoxifen and GH, respectively, resulted in up-regulation of UO-44 expression in a dose-dependent manner. In situ hybridization revealed that UO-44 gene expression was restricted to the luminal and glandular epithelial cells of the uterus and to granulosa cells of medium-size ovarian follicles. Transfection studies showed that UO-44 was a membrane-associated protein. Because estrogens, tamoxifen, and GH are stimulators of uterine luminal epithelial cell growth in vivo, UO-44 protein may serve as a mediator of the effect of these compounds in inducing epithelial proliferation and differentiation in these tissues.

Induction of apoptosis in mammary gland by a pure anti-estrogen ICI 182780

The antiestrogen, ICI 182780 (ICI) proves to be clinically useful for the treatment of estrogen receptor positive breast tumours. We report the assessment of the in vivo and in vitro effects of ICI on apoptosis of breast epithelial cells. In vivo, administration of rats with ICI for 3 weeks resulted in a reduction in the size of the lobular structures with the rate of mammary epithelial apoptosis equivalent to 10, 35 and 45% on treatment with 1, 1.5 and 2 mg ICI per kg body weight, respectively. Concomitantly, these treatment led to a 2.0-, 2.2- and 2.5-fold increase in Bax. Similar elevations were also observed in Bad levels which increased 1.7-, 2.6- and 2.7-fold respectively in the ICI treatment as compared to controls. This also resulted in a dose dependent decrease in Bcl-2 and Bcl-xL protein expressions. Growth inhibition and induction of apoptosis were also observed in the MCF-7 cells following in vitro treatment with ICI. This is closely associated with [1] the down-regulation of Bcl-2 and Bcl-xL proteins and [2] upregulation of Bax and Bad, whose gene products are known to be involved the regulation of apoptosis in mammalian cells. Stable over-expression of Bcl-2 resulted in protection of MCF-7 cells from apoptosis and growth inhibitory effects of ICI. Conversely, reduction of Bcl-2 by antisense transfection make MCF-7 cells more sensitive to ICI-induced growth inhibition and apoptosis. These findings suggest that modulation of Bax, Bcl-xL, Bcl-2 and Bad proteins by ICI may be, in part, responsible for the anti-proliferative and apoptotic effect of ICI seen clinically and in animal models.

STR data for the AmpFℓSTR Profiler loci from the three main ethnic population groups (Malay, Chinese and Indian) in Malaysia

Allele frequencies for the nine STRs genetic loci included in the AmpFlSTR Profiler kit were obtained from samples of unrelated individuals comprising 139-156 Malays, 149-153 Chinese and 132-135 Indians, residing in Malaysia.

Escherichia coli alpha-hemolysin (HlyA) is heterogeneously acylated in vivo with 14-, 15-, and 17-carbon fatty acids

alpha-Hemolysin (HlyA) is a secreted protein virulence factor observed in certain uropathogenic strains of Escherichia coli. The active, mature form of HlyA is produced by posttranslational modification of the protoxin that is mediated by acyl carrier protein and an acyltransferase, HlyC. We have now shown using mass spectrometry that these modifications, when observed in protein isolated in vivo, consist of acylation at the epsilon-amino groups of two internal lysine residues, at positions 564 and 690, with saturated 14- (68%), 15- (26%), and 17- (6%) carbon amide-linked side chains. Thus, HlyA activated in vivo consists of a heterogeneous family of up to nine different covalent structures, and the substrate specificity of the HlyC acyltransferase appears to differ from that of the closely related CyaC acyltransferase expressed by Bordetella pertussis.

Introgression of Lilium rubellum Baker chromosomes into L. longiflorum Thunb.: a genome painting study of the F1 hybrid, BC1 and BC2 progenies

Interspecific hybrids between Lilium longiflorum (L, 2n = 2x = 24) and Lilium rubellum (R, 2n = 2x = 24) were produced with the aim of transferring desirable horticultural traits from L. rubellum to L. longiflorum. All F1 hybrids (LR, 2n = 2x = 24) and BC1 individuals (LLR, 2n = 3x = 36) were phenotypically uniform for plant height, flowering time, leaf shape and flower colour. The BC1 plants were, in spite of their triploid nature, fertile and could be used as a female parent in backcrossings with autotetraploid L. longiflorum (LLLL, 2n = 4x = 48). Twelve BC2 individuals were obtained and three of them were selected for further chromosome analysis. As L. longiflorum and L. rubellum chromosomes were indistinguishable in the hybrids, genomic in-situ hybridization (GISH) was applied to establish the parentage of the chromosomes of the F1 hybrids and the BC1 and BC2 progenies. GISH confirmed the LLRR constitution of the doubled amphimonoploid (allodiploid), and the LLR constitution of all BC1 plants. The three selected BC2 plants were, as expected, aneuploid, containing three complete sets of L. longiflorum chromosomes and six, seven or eight L. rubellum chromosomes, respectively. However, L/R translocation or recombinant chromosomes could not be demonstrated in the mitotic metaphase complements of the F1, BC1 and BC2 plants. In spite of the high frequencies of homoeologous recombination in the F1 hybrids (LR) pollen was found to be sterile in all cases. At metaphase I of the pollen mother cells of the BC1 plants, genome painting did not reveal any cases of homoeologous pairing and recombination between L and R chromosomes. This lack of exchange between homoeologous chromosome segments indicates complete preferential pairing of the L and R chromosomes in the F1 (amphidiploid) and BC1 plants. It seems that the preferential pairing in the F1 and BC1 hybrids hinder the introgression of the chromosome segments or species-specific genes into the recipient for breeding purposes.

Thermographic study of palmar and facial skin temperature of hyperhidrosis patients before and after thoracic sympathectomy

PURPOSE

The purpose of this study was to investigate the roles of the second thoracic sympathetic segment in the sympathetic innervation of the hands and face, and to compare skin temperature changes in the palms, fingers, face, and neck of palmar hyperhidrosis (PH) patients before and after endoscopic thoracic sympathectomy.

METHODS

Twenty-two patients, 14 women and eight men, with severe PH were treated with endoscopic ablation of the T2 segment. The skin temperatures of the hands, neck, and face were assessed by infrared thermography both before and after operation.

RESULTS

All obtained satisfactory relief of PH. Before sympathectomy, thermography revealed that the palmar skin temperature (PST) was significantly lower than the facial temperature by 1.3 degrees C (paired t-test, p < 0.005). After sympathectomy, thermography showed significant elevations in temperature mainly of the thenars, palms, digits, and nose, but not of the forehead, mandible, or neck (ANOVA, p < 0.05 with Bonferroni t-test). The variations in PST among PH patients were much greater preoperatively than postoperatively. More prominent postoperative PST elevation was found in PH patients with lower preoperative PST (r = 0.898, p < 0.001).

CONCLUSIONS

These findings demonstrate that the T2 segment is the key source of sympathetic innervation to the hand and that the T2 segment contributes only trivial sympathetic innervation to the face. The results of the present thermography studies offer descriptive information about the autonomic innervation of the upper thoracic sympathetic trunk.

Specific lipopolysaccharide found in cystic fibrosis airway Pseudomonas aeruginosa

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.

Homoeologous recombination in 2n-gametes producing interspecific hybrids of Lilium (Liliaceae) studied by genomic in situ hybridization (GISH)

Interspecific hybridization of Lilium longiflorum (L) with Asiatic (A) lily hybrids results in so-called LA-hybrids. Some of these hybrids produce 2n-pollen, which were used to perform crosses on Asiatic and Oriental (O) hybrids, resulting in ALA- and OLA-hybrids. Recombination between homoeologous chromosomes (introgression) and the mechanism of 2n-pollen formation in these hybrids were studied using genomic in situ hybridization (GISH). A clear differentiation between the chromosomes of L. longiflorum, Asiatic, and Oriental hybrids was observed in four ALA- and one OLA-hybrid using GISH. Two ALA-hybrids showed 3 and 5 recombinant chromosomes with a total of 5 and 10 crossover sites per hybrid, respectively. These occurred at random positions on the chromosomes. The number and the location of the rDNA-sites were determined using in situ hybridization and provided a tool, the FISH-marker, for identifying the NOR-bearing chromosomes in the lily hybrids. Evidence for the occurrence of the FDR-mechanism (first division restitution) of 2n-pollen formation in the LA-hybrids was obtained on the basis of absence of homologous chromosomes of L. longiflorum in the ALA- and OLA-hybrids.Key words: Lilium longiflorum, introgression, FDR, interspecific hybridization, FISH.

The outcome of trial off catheter after acute retention of urine

The aim of this study was to analyse the outcome of trial off catheter for patients who were admitted to the Department of Urology, Singapore General Hospital (SGH) for acute retention of urine (ARU) due to benign prostatic hypertrophy (BPH). From 1 June to 15 October 1997, 150 patients were admitted for ARU. Seventy-one patients were excluded from our study due to our exclusion criteria such as chronic retention, patients with bladder stones and cancer of the prostate. Our results showed that 58% (n = 46) had a successful trial off catheter. The risk factors for failure were: high residual urine (more than 800 ml) and high prostatic specific antigen (PSA) value (10.9 versus 21.5). All patients with normal PSA value (< 4 ng/l) had successful trial off catheters. There was no difference between trial off catheter 24 hours versus 48 hours after admission.

Lipid A acylation and bacterial resistance against vertebrate antimicrobial peptides

The Salmonellae PhoP-PhoQ virulence regulators induce resistance to host cationic antimicrobial peptides (CAMP) after infection of vertebrate tissues, and Mg2+ or Ca2+ limitation. The PhoP-PhoQ activated gene, pagP, was identified as important to inducible CAMP resistance and increased acylation of lipid A, the major component of the outer leaflet of the outer membrane. pagP mutants demonstrated increased outer membrane permeability in response to CAMP, supporting the hypothesis that increased lipid A acylation is a CAMP resistance mechanism. Similarly, in response to Mg2+ limited growth, other enteric Gram-negative bacteria demonstrated increased lipid A acylation. Compounds that inhibit the ability to increase lipid A acylation may have utility as new antimicrobial agents.

PmrA-PmrB-regulated genes necessary for 4-aminoarabinose lipid A modification and polymyxin resistance

Antimicrobial peptides are distributed throughout the animal kingdom and are a key component of innate immunity. Salmonella typhimurium regulates mechanisms of resistance to cationic antimicrobial peptides through the two-component systems PhoP-PhoQ and PmrA-PmrB. Polymyxin resistance is encoded by the PmrA-PmrB regulon, whose products modify the lipopolysaccharide (LPS) core and lipid A regions with ethanolamine and add aminoarabinose to the 4' phosphate of lipid A. Two PmrA-PmrB-regulated S. typhimurium loci (pmrE and pmrF) have been identified that are necessary for resistance to polymyxin and for the addition of aminoarabinose to lipid A. One locus, pmrE, contains a single gene previously identified as pagA (or ugd) that is predicted to encode a UDP-glucose dehydrogenase. The second locus, pmrF, is the second gene of a putative operon predicted to encode seven proteins, some with similarity to glycosyltransferases and other complex carbohydrate biosynthetic enzymes. Genes immediately flanking this putative operon are also regulated by PmrA-PmrB and/or have been associated with S. typhimurium polymyxin resistance. This work represents the first identification of non-regulatory genes necessary for modification of lipid A and subsequent antimicrobial peptide resistance, and provides support for the hypothesis that lipid A aminoarabinose modification promotes resistance to cationic antimicrobial peptides.

Stability enhancement for peptide analysis by electrospray using the triple quadrupole mass spectrometer

Electrospray ionization sources, used with triple quadrupole mass spectrometers from PE/Sciex (API III+), Micromass (Quattro II), and Finnigan (TSQ 7000), were modified with a 35-gauge stainless steel needle. The dimensions of the needle were 63 microm i.d. by 145 microm o.d. with variable length, depending on the specific instrument. This modification led to enhanced signal stability, improved signal/noise ratios, and lowered sample consumption for a wide range of peptides. Stable baselines were observed with flow rates in the range of 50 nL/min to 5 microL/min. An alternative design, based on a metal wire housed within a fused silica capillary, led to the most stable signals of all during infusion, but caused excessive peak broadening with capillary chromatography. The Finnigan interface was further modified with an external postcolumn addition tee, used in conjunction with capillary liquid chromatography columns of 30 and 50 microm internal diameter. The best results with the modified Finnigan interface were acquired using the 50-microm column at a flow rate of 150 to 200 nL/min.

Regulation of lipid A modifications by Salmonella typhimurium virulence genes phoP-phoQ

Bacterial pathogenesis requires proteins that sense host microenvironments and respond by regulating virulence gene transcription. For Salmonellae, one such regulatory system is PhoP-PhoQ, which regulates genes required for intracellular survival and resistance to cationic peptides. Analysis by mass spectrometry revealed that Salmonella typhimurium PhoP-PhoQ regulated structural modifications of lipid A, the host signaling portion of lipopolysaccharide (LPS), by the addition of aminoarabinose and 2-hydroxymyristate. Structurally modified lipid A altered LPS-mediated expression of the adhesion molecule E-selectin by endothelial cells and tumor necrosis factor-alpha expression by adherent monocytes. Thus, altered responses to environmentally induced lipid A structural modifications may represent a mechanism for bacteria to gain advantage within host tissues.

Initial studies of a new approach to the design and use of enzyme-based reactor/sensor systems: amperometric system for glucose

This paper describes the development and evaluation of a new approach to the design and use of enzyme-based reactor/sensor systems (so-called "enzyme electrodes"). In the new approach, the reactor/sensor design is such that the measured response corresponds to reaction of all substrate in a fixed volume of solution. The result is that equilibrium-based measurements can be made, which in turn should result in advantages such as extended linear ranges and reduced dependencies on experimental variables such as enzyme activity, temperature, activators, inhibitors, etc. The concept was implemented with a glucose oxidase/electron-mediator reactor system immobilized on a glassy-carbon electrode operated in an amperometric mode. The reactor/sensor system was used in a thin-layer (14 microns) cell such that the mean diffusion time of substrate (glucose) across the cell was very short (< 1 s) and the rate-limiting process was the chemical reaction at the reactor surface. In this way, it was possible to quantify the electrical charge corresponding to reaction of all the substrate in a fixed volume of solution perpendicular to the plane of the reactor system. Because the determined charge is dependent only on the total amount of substrate in the fixed volume, results exhibit linear range up to at least 2-fold the Michaelis constant and reduced dependency on pH relative to results obtained with steady-state responses from the same experimental system. A mathematical treatment is presented which yields equations that are consistent with time-dependent responses for current and charge and which provide a rational basis for several data-processing options evaluated.

Error-compensating kinetic method for enzymatic determination of DNAs

We describe the adaptation and evaluation of an error-compensating method for kinetic determinations of deoxyribonucleic acids (DNAs). The DNA is first reacted with ethidium bromide to produce a fluorescent intercalation complex. Subsequent treatment of the complex with DNase catalyzes hydrolysis of the DNA, causing a time-dependent decrease in fluorescence, which is monitored. A model for two-component parallel first-order processes is fit to the decay curve to predict the total change in fluorescence expected if the process were monitored to equilibrium. The predicted change in fluorescence response varies linearly with DNA concentration with an intercept corresponding to 0.13 mg/L DNA. Results by the predictive method are 47-, 58-, and 250-fold less dependent on DNase activity, temperature, and ethidium bromide concentration, respectively, than are results for an initial-rate method utilizing the same data. Moreover, the predictive method yields a significantly wider linear range than the initial-rate method, and is much less affected by blank fluorescence and RNA interference than is an equilibrium method based on the reaction of DNA with ethidium bromide alone.

Enzyme immunoassay (Chlamydiazyme) for the detection of chlamydial antigen in endocervical specimens

Endocervical swabs taken from 86 women were tested by the Chlamydiazyme enzyme immunoassay test to detect chlamydial antigens. Compared to cell culture, Chlamydiazyme was 100% sensitive and 90% specific. This test is suitable as alternative diagnostic method to cell culture and has the potential for automation.

Endocervical chlamydial infection in women with gonorrhoea

Eighty six women attending Middle Road Hospital with endocervical gonococcal infection were evaluated. Chlamydia trachomatis was isolated in 27% of them. Women co-infected with C. trachomatis were similar to those with gonococcal infection alone in terms of demography, type of sexual contact, previous sexually transmitted disease, genitourinary symptoms, and clinical signs.

Comparative double-blinded study between mupirocin and tetracycline ointments for treating skin infections

A double-blinded study was conducted to compare the effects of mupirocin and tetracycline ointments in the treatment of skin infections. 111 patients were available for clinical assessment, of which 53 were treated with mupirocin and 58 treated with tetracycline. Clinically, both groups were improved, and there was no significant difference. Bacteriological assessment however revealed a better response to mupirocin. Staphylococcus aureus and Streptococcus pyogenes were the most common organisms isolated. 99% of Staphylococci were sensitive to mupirocin compared with 61% to tetracycline and 29% to penicillin G. 57% of Group A beta haemolytic Streptococci were resistant to tetracycline compared to 14% to mupirocin. Gram-negative organisms were mostly resistant to both preparations. No side effects were observed in both treatment groups. This study suggests that mupirocin is a safe and effective topical preparation for treating most of our common skin infections.

Chlamydial infection in female prostitutes in Singapore

Three studies conducted in 1982, 1985 and 1988 investigated chlamydial infections in female prostitutes. In 1982, 115 prostitutes with culture-positive gonorrhoea were studied; 8% were coinfected with Chlamydia trachomatis. In 1985, 86 female prostitutes and in 1988, 100 female prostitutes attending for routine tests were examined. Chlamydia trachomatis was isolated in 12% and 9% of the cases, respectively. Gonorrhoea was detected in 10% and 11% of the cases. In the 1988 study, one (9%) of the 11 women with gonorrhoea had concomitant chlamydial infection. Syphilis was diagnosed in 3% of the female prostitutes investigated in 1988. Our findings indicate that concomitant chlamydial infection occurs in about 8-9% of female prostitutes with gonorrhoea and that 9-12% of the female prostitutes screened harboured Chlamydia trachomatis in their endocervices. A chlamydial control programme in prostitutes is desirable.

Epidemiology of acute epididymo-orchitis in Singapore

A prospective study on 55 patients with acute epididymo-orchitis was studied. Their ages ranged from 15 to 65 years. Thirty-three (60%) were within the 20-29 year age group and 9 were above 35 years of age. 69% cited prostitutes as the source of sexual contact. Twenty-six patients did not receive and 29 patients received antibiotic therapy before recruitment. In the former untreated group, 6 patients (23%) had gonococcal urethritis, 3 patients (11%) had chlamydial urethritis and 2 patients (8%) had combined gonococcal and chlamydial urethritis. No pathogens were isolated from the urethra from the remaining 15 (58%) patients, 8 of whom had nonspecific urethritis. In the latter treated group, 4 patients (14%) had gonococcal urethritis and no organisms were isolated from the remaining 25 (86%) of whom 6 had non-specific urethritis. None of the 55 patients had urinary tract infections. Forty-three patients (78%) had unilateral involvement of both the testis and epididymis, and 4 patients (7%) had bilateral epididymo-orchitis. Semen analysis was performed on 13 patients of whom 8 showed pyospermia.

Endocervical chlamydial infection in women attending a sexually transmitted disease clinic in Singapore

Two hundred women attending the sexually transmitted disease (STD) clinic at Middle Road Hospital were investigated. Chlamydia trachomatis was isolated from 32% of women who were contacts of men with nongonococcal urethritis, 15% of contacts of gonococcal urethritis, 27% of contacts of unspecified STD, and 13% of women without any history of STD in their sex partners. Overall, Chlamydia trachomatis was isolated from 17% of 200 women, Neisseria gonorrhoeae from 13% of 199 women, Candida albicans from 34% and Trichomonas vaginalis from 6% of 197 women. Three per cent of the patients had positive VDRL results. A history of bilateral lower abdominal pain and the presence of cervicitis were significantly associated with chlamydial infection. Forty one per cent of the 34 chlamydia-positive women were asymptomatic. The results of this study show that C. trachomatis infection is more common than infection with N. gonorrhoeae in women who attend STD clinics. The need for routine screening and treatment on the basis of epidemiological and clinical markers of infection has to be carefully examined.

Endocervical chlamydial infection in female contacts of patients with nongonococcal urethritis

Eighty-five female contacts of patients with nongonococcal urethritis attending Middle Road Hospital were examined. Chlamydia trachomatis was isolated from the cervix in 39% of them. Forty-five per cent of the chlamydia-positive patients were asymptomatic and 79% of them showed signs of a cervicitis. None of the patients developed complications. Neisseria gonorrhoeae was not isolated from any of the patients. Clinical markers other than cervicitis are not useful for detecting chlamydial infections in female contacts of NGU. Until such time when cheaper, more convenient and accurate methods of laboratory diagnosis of C. trachomatis are put to routine use, it would seem prudent to treat all female contacts of NGU patients after exclusion of other sexually transmitted diseases.

Dedifferentiated chondrosarcoma metastasizing to the pancreas in pregnancy

Acute abdomen in pregnancy can present difficulties in both diagnosis and treatment. In this patient the presentation of an acute abdomen was due to some intraperitoneal hemorrhage complicating a pancreatic metastasis from a primary dedifferentiated chondrosarcoma arising from the right iliac bone. Neither the primary nor the secondary growths had been suspected previously.

Bacampicillin to treat non-gonococcal urethritis in men: pilot study

Of 84 men with non-gonococcal urethritis (NGU), 24 yielded Chlamydia trachomatis by either cell culture or MicroTrak immunofluorescence test. All 84 were treated with bacampicillin 800 mg twice a day for seven days. Five (one chlamydia positive) defaulted from follow up 10 to 14 days after the start of treatment. Of the 23 chlamydia positive patients who attended follow up, 22 became chlamydia negative; 14 of the 23 patients also became asymptomatic and had normal urethral smears. Of the 56 chlamydia negative patients who attended follow up, 21 were cleared of their urethritis. Two patients reported side effects; one drowsiness and one mild diffuse alopecia. Bacampicillin may therefore be a safe and effective alternative to tetracycline or erythromycin in treating chlamydial urethritis in men.

An immunofluorescence study of lichen planus among Asians in Singapore

Forty-five Asian patients (Indians 35, Chinese 8, Malay 2) with histologically proven lichen planus were studied by immunofluorescence. The most characteristic feature, seen in 93% of the cases, was shaggy deposition of fibrinogen along the basement membrane. Immunoglobulin deposition along the basement membrane was notably, absent. Colloid bodies were observed in 87% of the cases. Fibrinogen was the most common immunoreactant, and its presence in colloid bodies was always associated with fibrinogen deposition along the basement membrane zone. Colloid bodies also contained a variety of other immunoreactants. However, staining for IgM was noted to be the most intense. The combination of shaggy deposition of fibrinogen along the basement membrane, in the absence of immunoglobulins, and the presence of colloid bodies around the basement membrane zone, is highly characteristic of lichen planus. The pattern of immunofluorescence among Asians with lichen planus, conforms to that observed in other races. There did not appear to be any difference in the immunofluorescence staining with pattern in the three racial groups studied.

Lichen planus: a study of 72 cases in Singapore

Seventy-two patients attending this hospital with a diagnosis of lichen planus were examined. There was a striking predominance of Indians (69%) and a surprisingly low incidence of Chinese (24%) and Malays (4%) in the study population, compared to the racial composition of the general clinic population. The age distribution curve of the study population was bimodal with peaks at age groups 21-30 (22%) and 41-60 (33%) years. The most common morphologic variant was lichen planus vulgaris (common type) which we observed in 46 (64%) patients, followed by lichen planus hypertrophicus in 8 (11%) and lichen planus atrophicus in 2 (3%). Lichen planus confined to the skin was observed in 49 (68%) patients. Mucous membrane involvement was seen in 21 (29%)-17 (24%) had oral mucosa membrane involvement and 4 (6%) genital mucous membrane involvement. In 16 (22%) cases, mucous membranes were exclusively involved--12 (17%) had oral mucous membrane involvement and 4 (6%) genital mucous membrane involvement. Nail changes were only observed in 2 (3%) patients. Eight (11%) patients had associated diabetes mellitus. Overall, lichen planus appeared to pursue a protracted course with only 4 (6%) patients clearing completely after a disease duration of 5-12 months.

An unusual case of varicella involving the penis

An unusual case of varicella involving the penis is presented. Herpetiform ulceration of the penis in a person who has had promiscuous sexual contact is not necessarily herpes progenitalis, since varicella may also involve the penis.