Biosynthesis of the allelopathic alkaloid gramine in barley by a cryptic oxidative rearrangement

The defensive alkaloid gramine not only protects barley and other grasses from insects but also negatively affects their palatability to ruminants. The key gene for gramine formation has remained elusive, hampering breeding initiatives. In this work, we report that a gene encoding cytochrome P450 monooxygenase CYP76M57, which we name AMI synthase (AMIS), enables the production of gramine in Nicotiana benthamiana, Arabidopsis thaliana, and Saccharomyces cerevisiae. We reconstituted gramine production in the gramine-free barley (Hordeum vulgare) variety Golden Promise and eliminated it from cultivar Tafeno by Cas-mediated gene editing. In vitro experiments unraveled that an unexpected cryptic oxidative rearrangement underlies this noncanonical conversion of an amino acid to a chain-shortened biogenic amine. The discovery of the genetic basis of gramine formation now permits tailor-made optimization of gramine-linked traits in barley by plant breeding.

Post-Cyclization Skeletal Rearrangements in Plant Triterpenoid Biosynthesis by a Pair of Branchpoint Isomerases

Triterpenoids possess potent biological activities, but their polycyclic skeletons are challenging to synthesize. The skeletal diversity of triterpenoids in plants is generated by oxidosqualene cyclases based on epoxide-triggered cationic rearrangement cascades. Normally, triterpenoid skeletons then remain unaltered during subsequent tailoring steps. In contrast, the highly modified triterpenoids found in Sapindales plants imply the existence of post-cyclization skeletal rearrangement enzymes that have not yet been found. We report here a biosynthetic pathway in Sapindales plants for the modification of already cyclized tirucallane triterpenoids, controlling the pathway bifurcation between different plant triterpenoid classes. Using a combination of bioinformatics, heterologous expression in plants and chemical analyses, we identified a cytochrome P450 monooxygenase and two isomerases which harness the epoxidation-rearrangement biosynthetic logic of triterpene cyclizations for modifying the tirucallane scaffold. The two isomerases share the same epoxide substrate made by the cytochrome P450 monooxygenase CYP88A154, but generate two different rearrangement products, one containing a cyclopropane ring. Our findings reveal a process for skeletal rearrangements of triterpenoids in nature that expands their scaffold diversity after the initial cyclization. In addition, the enzymes described here are crucial for the biotechnological production of limonoid, quassinoid, apoprotolimonoid, and glabretane triterpenoids.

In vivo characterization of key iridoid biosynthesis pathway genes in catnip (Nepeta cataria)

Using virus-induced gene silencing, we demonstrated that the enzymes GES, ISY, and MLPL are responsible for nepetalactone biosynthesis in Nepeta cataria. Nepetalactone is the main iridoid that is found in the Nepeta genus and is well-known for its psychoactive effect on house cats. Moreover, there is a burgeoning interest into the effect of nepetalactone on insects. Although the enzymes for nepetalactone biosynthesis have been biochemically assayed in vitro, validation of the role that these enzymes have in planta has not been demonstrated. Virus-induced gene silencing (VIGS) is a silencing method that relies on transient transformation and is an approach that has been particularly successful when applied to a variety of non-model plants. Here, we use a recently designed visual-marker dependent VIGS system to demonstrate that the nepetalactone biosynthetic enzymes GES, ISY, and MLPL impact nepetalactone biosynthesis in Nepeta cataria.

Identification of early quassinoid biosynthesis in the invasive tree of heaven (Ailanthus altissima) confirms evolutionary origin from protolimonoids

The tree of heaven, Ailanthus altissima (MILL.) SWINGLE, is a globally invasive plant known to secrete allelopathic metabolites called quassinoids. Quassinoids are highly modified triterpenoids. So far, nothing has been known about the biochemical basis of quassinoid biosynthesis. Here, based on transcriptome and metabolome data of Ailanthus altissima, we present the first three steps of quassinoid biosynthesis, which are catalysed by an oxidosqualene cyclase and two cytochrome P450 monooxygenases, resulting in the formation of the protolimonoid melianol. Strikingly, these steps are identical to the first steps of the biosynthesis of limonoids, structurally different triterpenoids from sister plant families within the same order Sapindales. Our results are therefore not only important to fully understand the biosynthesis of complex triterpenoids in plants, but also confirm the long-standing hypothesis that quassinoids and limonoids share an evolutionary origin. In addition, our transcriptome data for Ailanthus altissima will be beneficial to other researchers investigating the physiology and ecology of this invasive tree.

3D-printed autoclavable plant holders to facilitate large-scale protein production in plants

The Australian tobacco plant Nicotiana benthamiana is becoming increasingly popular as a platform for protein production and metabolic engineering. In this system, gene expression is achieved transiently by infiltrating N. benthamiana plants with suspensions of Agrobacterium tumefaciens carrying vectors with the target genes. To infiltrate larger numbers of plants, vacuum infiltration is the most efficient approach known, which is already used on industrial scale. Current laboratory-scale solutions for vacuum infiltration, however, either require expensive custom-tailored equipment or produce large amounts of biologically contaminated waste. To overcome these problems and lower the burden to establish vacuum infiltration in new laboratories, we present here 3D-printed plant holders for vacuum infiltration. We demonstrate that our plant holders are simple to use and enable a throughput of around 40 plants per hour. In addition, our 3D-printed plant holders are made from autoclavable material, which tolerate at least 12 autoclave cycles, helping to limit the production of contaminated waste and thus contributing to increased sustainability in research. In conclusion, our plant holders provide a simple, robust, safe and transparent platform for laboratory-scale vacuum infiltration that can be readily adopted by new laboratories interested in protein and metabolite production in Nicotiana benthamiana. Practical application Transient expression in Nicotiana benthamiana provides a popular and rapid system for producing proteins in a plant host. To infiltrate larger numbers of plants (typically >20), vacuum infiltration is the method of choice. However, no system has been described so far which is robust to use and can be used without expensive and complex equipment. Our autoclavable 3D-printed plant holders presented here will greatly reduce the efforts required to adopt the vacuum infiltration technique in new laboratories. They are easy to use and can be autoclaved at least 12 times, which contributes to waste reduction and sustainability in research laboratories. We anticipate that the 3D printing design provided here will drastically lower the bar for new groups to employ vacuum infiltration for producing proteins and metabolites in Nicotiana benthamiana.

Rapid Combinatorial Coexpression of Biosynthetic Genes by Transient Expression in the Plant Host Nicotiana benthamiana

Metabolic engineering of heterologous hosts requires coexpression of multiple genes, often more than ten for a single pathway. Traditional approaches to create genetic constructs for this purpose are highly inflexible and suffer from very low throughput. In this book chapter, we describe a powerful method to overcome this bottleneck, namely, combinatorial co-expression in the Australian tobacco plant Nicotiana benthamiana. This system is based on Agrobacterium tumefaciens-mediated transient gene expression, often called agroinfiltration. Herein, instead of creating complex multigenic constructs, coexpression is achieved by simply mixing different plasmid-bearing Agrobacterium strains without the need for different selection markers. We present a practical guide for coexpressing multiple biosynthetic genes followed by GC-MS analysis, using production of the plant triterpene β-amyrin as an example. Our chapter provides a guideline to harness the potential of this versatile expression system in the natural product community for studying and engineering metabolic pathways.

Collaborations in gynecologic oncology education and research in low- and middle- income countries: Current status, barriers and opportunities

Eighty-five percent of the incidents and deaths from cervical cancer occur in low and middle income countries. In many of these countries, this is the most common cancer in women. The survivals of the women with gynecologic cancers are hampered by the paucity of prevention, screening, treatment facilities and gynecologic oncology providers. Increasing efforts dedicated to improving education and research in these countries have been provided by international organizations. We describe here the existing educational and research programs that are offered by major international organizations, the barriers and opportunities provided by these collaborations and hope to improve the outcomes of cervical cancer through these efforts.

Identification, Functional Characterization, and Seasonal Expression Patterns of Five Sesquiterpene Synthases in Liquidambar formosana

Terpenoids are a large group of important secondary metabolites that are involved in a variety of physiological mechanisms, and many are used commercially in the cosmetics and pharmaceutical industries. During the past decade, the topic of seasonal variation in terpenoid biosynthesis has garnered increasing attention. Formosan sweet gum ( Liquidambar formosana Hance) is a deciduous tree species. The expression of terpene synthase and accumulation of terpenoids in leaves may vary in different seasons. Here, four sesquiterpene synthases (i.e., LfTPS01, LfTPS02, LfTPS03, and LfTPS04) and a bifunctional mono/sesquiterpene synthase ( LfTPS05) were identified from Formosan sweet gum. The gene expression of LfTPS01, LfTPS02, and LfTPS03 showed seasonal diversification, and, in addition, expression of LfTPS04 and LfTPS05 was induced by methyl jasmonate treatment. The major products LfTPS01, LfTPS02, LfTPS04, and LfTPS05 are hedycaryol, α-selinene, trans-β-caryophyllene, α-copaene/δ-cadinene, and nerolidol/linalool, respectively. The data indicated that the sesquiterpenoid content in the essential oil of Formosan sweet gum leaves shows seasonal differences that were correlated to the sesquiterpene synthase gene expression.

Detection and correlation of pre-operative, frozen section, and final pathology in high-risk endometrial cancer

PURPOSE

To evaluate sensitivity and specificity of pre-operative and frozen section pathologic evaluation (FSA) in predicting high-risk (HR) histology endometrial cancer.

MATERIALS AND METHODS

A retrospective analysis was performed on all patients diagnosed with endometrial cancer at a single institution. Medical records were abstracted for baseline characteristics, surgical reports for staging, and final histology was confirmed by a gynecologic pathologist.

RESULTS

868 patients were identified. Of these, 118 had Grade 3 endometrioid, 36 clear cell carcinoma (CCC), 47 carcinosarcoma (CS), and 84 uterine papillary serous carcinoma (UPSC) histology. Endometrial biopsy (EMB) had an overall sensitivity of 90%, 77% for low grade, 78% for HR, with a specificity of 0%. For dilation and curettage (D&C), overall sensitivity was 85%, 69% for low grade, and 77% for HR. Specificity was 33%. Sensitivities for combined pre-operative testing for G3 endometrioid, CCC, CS, and UPSC were: 56%, 28%, 72%, and 60%, respectively. For frozen section analysis (FSA), overall sensitivity was 77%, and 67% for low and high grade. For G3 endometrioid, CCC, CS, and UPSC, sensitivities were 57%, 20%, 74%, 32%, respectively. Specificity was 95%. FSA identified an additional six patients (8%) with UPSC, CCC or CS that were pre-operatively low risk, providing an 8% improvement in sensitivity but decreased specificity.

CONCLUSIONS

Pre-operative EMB and D&C are overall very sensitive for detecting endometrial cancer; however, sensitivity decreases with HR histology. Pre-op testing will miss 28% of HR diagnoses and FSA provides an opportunity to identify some patients with UPSC, CCC, and CS. If pre-operative results suggest HR cancer, the surgeon should proceed with comprehensive surgical staging without an FSA.

A simple improved-throughput xylem protoplast system for studying wood formation

Isolated protoplasts serve as a transient expression system that is highly representative of stable transgenics in terms of transcriptome responses. They can also be used as a cellular system to study gene transactivation and nucleocytoplasmic protein trafficking. They are particularly useful for systems studies in which stable transgenics and mutants are unavailable. We present a protocol for the isolation and transfection of protoplasts from wood-forming tissue, the stem-differentiating xylem (SDX), in the model woody plant Populus trichocarpa. The method involves tissue preparation, digestion of SDX cell walls, protoplast isolation and DNA transfection. Our approach is markedly faster and provides better yields than previous protocols; small (milligrams)- to large (20 g)-scale SDX preparations can be achieved in ~60 s, with isolation of protoplasts and their subsequent transfection taking ~50 min. Up to ten different samples can be processed simultaneously in this time scale. Our protocol gives a high yield (~2.5 × 10(7) protoplasts per g of SDX) of protoplasts sharing 96% transcriptome identity with intact SDX.

Association of genetic variation in FTO with risk of obesity and type 2 diabetes with data from 96,551 East and South Asians

AIMS/HYPOTHESIS

FTO harbours the strongest known obesity-susceptibility locus in Europeans. While there is growing evidence for a role for FTO in obesity risk in Asians, its association with type 2 diabetes, independently of BMI, remains inconsistent. To test whether there is an association of the FTO locus with obesity and type 2 diabetes, we conducted a meta-analysis of 32 populations including 96,551 East and South Asians.

METHODS

All studies published on the association between FTO-rs9939609 (or proxy [r (2) > 0.98]) and BMI, obesity or type 2 diabetes in East or South Asians were invited. Each study group analysed their data according to a standardised analysis plan. Association with type 2 diabetes was also adjusted for BMI. Random-effects meta-analyses were performed to pool all effect sizes.

RESULTS

The FTO-rs9939609 minor allele increased risk of obesity by 1.25-fold/allele (p = 9.0 × 10(-19)), overweight by 1.13-fold/allele (p = 1.0 × 10(-11)) and type 2 diabetes by 1.15-fold/allele (p = 5.5 × 10(-8)). The association with type 2 diabetes was attenuated after adjustment for BMI (OR 1.10-fold/allele, p = 6.6 × 10(-5)). The FTO-rs9939609 minor allele increased BMI by 0.26 kg/m(2) per allele (p = 2.8 × 10(-17)), WHR by 0.003/allele (p = 1.2 × 10(-6)), and body fat percentage by 0.31%/allele (p = 0.0005). Associations were similar using dominant models. While the minor allele is less common in East Asians (12-20%) than South Asians (30-33%), the effect of FTO variation on obesity-related traits and type 2 diabetes was similar in the two populations.

CONCLUSIONS/INTERPRETATION

FTO is associated with increased risk of obesity and type 2 diabetes, with effect sizes similar in East and South Asians and similar to those observed in Europeans. Furthermore, FTO is also associated with type 2 diabetes independently of BMI.

Photoluminescence properties of InAs nanowires grown on GaAs and Si substrates

We report the first photoluminescence (PL) characterization of InAs nanowires (NWs). The InAs NWs were grown on GaAs(111) B and Si(111) substrates using the Au-assisted molecular beam epitaxy (MBE) growth technique or metal-organic chemical vapor deposition (MOCVD). We compared the PL response of four samples grown under different conditions using MBE or MOCVD. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) patterns were utilized to determine the crystal structure and growth directions of the NWs to relate PL features to NW structural parameters. We observed mainly three PL peaks which were below, near and above InAs bandgaps, respectively. Temperature and excitation intensity dependence PL measurements were also performed to help elucidate the origins of the PL peaks of NWs. Of particular interest was a band-edge emission peak that was blue-shifted due to quantization effects of the InAs NWs, as confirmed by our calculation.

A case-controlled study of total laparoscopic radical hysterectomy with pelvic lymphadenectomy versus radical abdominal hysterectomy in a fellowship training program

To determine whether total laparoscopic radical hysterectomy (TLRH) is a feasible alternative to an abdominal radical hysterectomy (ARH) in a gynecologic oncology fellowship training program. We prospectively collected cases of all of the patients with cervical cancer treated with TLRH and pelvic lymphadenectomy by our division from 2000 to 2006. All of the patients from the TLRH group were matched 1:1 with the patients who had ARH during the same period based on stage, age, histological subtype, and nodal status. Thirty patients were treated with TLRH with a mean age of 48.3 years (range, 29–78 years). The mean pelvic lymph node count was 31 (range, 10–61) in the TLRH group versus 21.8 (range, 8–42) (P < 0.01) in the ARH group. Mean estimated blood loss was 200 cc (range, 100–600 cc) in the TLRH with no transfusions compared to 520 cc in the ARH group (P < 0.01), in which five patients required transfusions. Mean operating time was 318.5 min (range, 200–464 min) compared to 242.5 min in the ARH group (P < 0.01), and mean hospital stay was 3.8 days (range, 2–11 days) compared to 5.6 days in the ARH group (P < 0.01). All TLRH cases were completed laparoscopically. All patients in the TLRH group are disease free at the time of this report. In conclusion, it is feasible to incorporate TLRH training into the surgical curriculum of gynecologic oncology fellows without increasing perioperative morbidity. Standardization of TLRH technique and consistent guidance by experienced faculty is imperative.

Immunohistochemical characterization of cancer antigen in uterine cancers

The pattern of cancer antigen (CA-125) expression by immunohistochemistry (IHC) was investigated in malignant and nonneoplastic endometrium in endometrial carcinoma. Ninety cases of primary uterine carcinomas (65 endometrioid [EM] carcinoma, 15 serous papillary [SP] carcinoma, 6 carcinosarcomas [malignant mixed müllerian tumors], and 4 clear cell carcinoma [CC]) and adjacent atrophic and/or hyperplastic endometrium were analyzed by IHC for CA-125 expression. The percentage and intensity of luminal, apical, basal, and diffuse cytoplasmic immunostaining of epithelial cells were categorized on a scale of 0-4. The immunoreaction score (IRS score) was calculated and correlated with the grade and stage of carcinoma according to the histologic type. CA-125 expression (3-4/4) was localized in apical borders of grade 1 and grade 2 EM carcinoma and was weak or negative (0-1/4) in grade 3 EM. Mucinous differentiation in EM was associated with intense luminal and apical staining. Squamous areas and stroma showed no staining at all. SP carcinoma and endometrial intraepithelial carcinoma showed much higher mean IRS score than EM. In malignant mixed müllerian tumors (MMMT), the epithelial component stained as above according to the type of epithelial cell differentiation of the neoplastic cells. Benign proliferative glands showed moderate apical luminal, basal, and cytoplasmic staining. Intense diffuse staining was observed in atypical complex hyperplasia. Different patterns of CA-125 immunostaining were observed in normal, hyperplastic, and neoplastic endometrium. IRS score correlated with the grade but not with the stage of EM carcinoma. The intense different staining pattern of endometrium with atypical complex hyperplasia suggests that CA-125 may be a useful diagnostic aid.

Effective palliative radiation therapy in advanced and recurrent ovarian carcinoma

PURPOSE

To retrospectively review our experience using radiation therapy as a palliative treatment in ovarian carcinoma.

METHODS AND MATERIALS

Eighty patients who received radiation therapy for ovarian carcinoma between 1983 and 1998 were reviewed. The indications for radiation therapy, radiation therapy techniques, details, tolerance, and response were recorded. A complete response required complete resolution of the patient's symptoms, radiographic findings, palpable mass, or CA-125 level. A partial response required at least 50% resolution of these parameters. The actuarial survival rates from initial diagnosis and from the completion of radiation therapy were calculated.

RESULTS

The median age of the patients was 67 years (range 26 to 90 years). A median of one laparotomy was performed before irradiation. Zero to 20 cycles of a platinum-based chemotherapy regimen were delivered before irradiation (median = 6 cycles). The reasons for palliative treatment were: pain (n = 22), mass (n = 23), obstruction of ureter, rectum, esophagus, or stomach (n = 12), a positive second-look laparotomy (n = 9), ascites (n = 8), vaginal bleeding (n = 6), rectal bleeding (n = 1), lymphedema (n = 3), skin involvement (n = 1), or brain metastases with symptoms (n = 11). Some patients received treatment for more than one indication. Treatment was directed to the abdomen or pelvis in 64 patients, to the brain in 11, and to other sites in 5. The overall response rate was 73%. Twenty-eight percent of the patients experienced a complete response of their symptoms, palpable mass, and/or CA-125 level. Forty-five percent had a partial response. Only 11% suffered progressive disease during therapy that required discontinuation of the treatment. Sixteen percent had stable disease. The duration of the responses and stable disease lasted until death except in 10 patients who experienced recurrence of their symptoms between 1 and 21 months (median = 9 months). The 1-, 2-, 3-, and 5-year actuarial survival rates from diagnosis were 89%, 73%, 42%, and 33%, respectively. The survival rates calculated from the completion of radiotherapy were 39%, 27%, 13%, and 10%, respectively. Five percent of patients experienced Grade 3 diarrhea, vomiting, myelosuppression, or fatigue. Fourteen percent of patients experienced Grade 1 or 2 diarrhea, 19% experienced Grade 1 or 2 nausea and vomiting, and 11% had Grade 1 or 2 myelosuppression.

CONCLUSIONS

In this series of radiation therapy for advanced ovarian carcinoma, the response, survival, and tolerance rates compare favorably to those reported for current second- and third-line chemotherapy regimens. Cooperative groups should consider evaluating prospectively the use of radiation therapy before nonplatinum and/or nonpaclitaxel chemotherapy in these patients.

Vaginal Reconstruction With a Rectus Abdominis Musculoperitoneal Flap

In more than 300 clinical cases, the authors have observed and documented the presence of a branch of the deep inferior epigastric artery that penetrates the posterior rectus sheath near the umbilicus. Their cadaveric anatomic and animal injection studies confirm the vascularity of the peritoneum via the deep inferior epigastric artery. They report 2 patients treated with a new technique of vaginal reconstruction using a thin, pliable flap with a peritoneal-lined rectus abdominis muscle based on the deep inferior epigastric vessels.

Genetic epidemiology of type 1 diabetes mellitus in Taiwan

Some environmental and genetic factors play important roles in etiopathogenesis of type 1 or insulin-dependent diabetes mellitus (IDDM). HLA genes, the IDDM1 locus located the human chromosome 6, were found to be associated with insulin-dependent diabetes mellitus. However, the incidence of IDDM varied greatly among various populations. To evaluate the pathogenetic factors contributing to the development of IDDM in Taiwan, HLA typing was performed in a group of IDDM unrelated individuals and IDDM pedigrees along with the normal controls from the northern Taiwan. DNA genotypes of class II HLA were done by polymerase-chain-reaction based oligotyping techniques. We confirmed that class II HLA genes were significantly associated with IDDM in Taiwan. To study detailed molecular structure of class II HLA molecules and disease association, we examined several amino acid residues on DQalpha and DQbeta chains and the molecular mechanisms to explain the heterozygotic effect of the DR3/DR4 and DR3/DR9 in the Chinese population. Linkage analysis in our pedigrees confirmed the association between HLA and IDDM in population association studies. Among the several class II alleles, a closer segregation of HLA-DQB1*0401 to the affected persons might suggest that HLA-DQB1*0401 itself or an allele closely linked to the DQB1 locus was the IDDM-predisposing allele in Taiwanese. For IDDM2 (INS) region, association with IDDM was not found due to that more than 90% of the population carried class I alleles. In our collection of IDDM, we found few cases (2.4%) carried mitochondrial DNA mutation. Our studies in Taiwanese confirm a multigenetic nature for IDDM.

SpinThin, a simple, inexpensive technique for preparation of thin-layer cervical cytology from liquid-based specimens: data on 791 cases

BACKGROUND

Acceptance of liquid-based fixatives for cervical cytology has been limited by the more complex slide-preparation procedures, increased cost, and reports that increased sensitivity has been based largely on comparison with conventional cytology without histologic correlation. Here the authors describe and evaluate a technically simple and relatively inexpensive method (which they call SpinThin) for preparing Cytospin (Shandon Inc., Pittsburgh, PA) cervical cytology slides from samples in liquid fixative using a modified electric toothbrush holder to put the cells in suspension. Results are compared with conventional cytology and histologic biopsy.

METHODS

A total of 791 cervical cytology specimens from 2 patient groups at high risk of uterine cervical neoplasia were entered into this study, and a spatula and cytobrush (174 specimens) or cytobroom (617 specimens) were used to collect conventional smears. The collection device with remaining cellular sample was placed in an alcohol-based fixative solution; the cells were put into suspension by a brief burst of vibration using a modified electric toothbrush holder, then cytocentrifuged on a slide and stained with the Papanicolaou technique.

RESULTS

Specimen adequacy in SpinThin slides was better than that of conventional cytology smears. However, the prevalence of dysplasia, including atypical squamous cells of undetermined significance (ASCUS-D), in conventional smears and SpinThin slides was the same--27% and 25%, respectively--and excluding ASCUS-D, it was 20% in both. The prevalence of neoplasia (low or high grade squamous intraepithelial lesion, or carcinoma) histologically was 31% in the 647 cases biopsied, and agreement with histology was similar for SpinThin and conventional smears.

CONCLUSIONS

Using a simple and relatively inexpensive new technique (Spin-Thin), slides prepared from fluid-based cervical cytology specimens obtained with the cytobrush or cytobroom correlated very well with the corresponding conventional smears within major diagnostic categories, and both correlated well with histology.