Transportome-wide engineering of Saccharomyces cerevisiae

Synthetic biology enables the production of small molecules by recombinant microbes for pharma, food, and materials applications. The secretion of products reduces the cost of separation and purification, but it is challenging to engineer due to the limited understanding of the transporter proteins' functions. Here we describe a method for genome-wide transporter disruption that, in combination with a metabolite biosensor, enables the identification of transporters impacting the production of a given target metabolite in yeast Saccharomyces cerevisiae. We applied the method to study the transport of xenobiotic compounds, cis,cis-muconic acid (CCM), protocatechuic acid (PCA), and betaxanthins. We found 22 transporters that influenced the production of CCM or PCA. The transporter of the 12-spanner drug:H(+) antiporter (DHA1) family Tpo2p was further confirmed to import CCM and PCA in Xenopus expression assays. We also identified three transporter proteins (Qdr1p, Qdr2p, and Apl1p) involved in betaxanthins transport. In summary, the described method enables high-throughput transporter identification for small molecules in cell factories.

Metabolic Engineering of Saccharomyces cerevisiae for Rosmarinic Acid Production

Rosmarinic acid is a hydroxycinnamic acid ester commonly found in the Boraginaceae and Lamiaceae plant families. It exhibits various biological activities, including antioxidant, anti-inflammatory, antibacterial, antiallergic, and antiviral properties. Rosmarinic acid is used as a food and cosmetic ingredient, and several pharmaceutical applications have been suggested as well. Rosmarinic acid is currently produced by extraction from plants or chemical synthesis; however, due to limited availability of the plant sources and the complexity of the chemical synthesis method, there is an increasing interest in producing this compound by microbial fermentation. In this study, we aimed to produce rosmarinic acid by engineered baker's yeast Saccharomyces cerevisiae. Multiple biosynthetic pathway variants, carrying only plant genes or a combination of plant and Escherichia coli genes, were implemented using a full factorial design of experiment. Through analysis of variances, the effect of each enzyme variant (factors), together with possible interactions between these factors, was assessed. The best pathway variant produced 2.95 ± 0.08 mg/L rosmarinic acid in mineral medium with glucose as the sole carbon source. Increasing the copy number of rosmarinic acid biosynthetic genes increased the titer to 5.93 ± 0.06 mg/L. The study shows the feasibility of producing rosmarinic acid by yeast fermentation.

A single-host fermentation process for the production of flavor lactones from non-hydroxylated fatty acids

Lactone flavors with fruity, milky, coconut, and other aromas are widely used in the food and fragrance industries. Lactones are produced by chemical synthesis or by biotransformation of plant-sourced hydroxy fatty acids. We established a novel method to produce flavor lactones from abundant non-hydroxylated fatty acids using yeast cell factories. Oleaginous yeast Yarrowia lipolytica was engineered to perform hydroxylation of fatty acids and chain-shortening via β-oxidation to preferentially twelve or ten carbons. The strains could produce γ-dodecalactone from oleic acid and δ-decalactone from linoleic acid. Through metabolic engineering, the titer was improved 4-fold, and the final strain produced 282 mg/L γ-dodecalactone in a fed-batch bioreactor. The study paves the way for the production of lactones by fermentation of abundant fatty feedstocks.

Engineering of high yield production of L-serine in Escherichia coli

L-serine is a widely used amino acid that has been proposed as a potential building block biochemical. The high theoretical yield from glucose makes a fermentation based production attractive. In order to achieve this goal, serine degradation to pyruvate and glycine in E. coli MG1655 was prevented by deletion of three L-serine deaminases sdaA, sdaB, and tdcG, as well as serine hydroxyl methyl transferase (SHMT) encoded by glyA. Upon overexpression of the serine production pathway, consisting of a feedback resistant version of serA along with serB and serC, this quadruple deletion strain showed a very high serine production yield (0.45 g/g glucose) during small-scale batch fermentation in minimal medium. Serine, however, was found to be highly toxic even at low concentrations to this strain, which lead to slow growth and production during fed batch fermentation, resulting in a serine production of 8.3 g/L. The production strain was therefore evolved by random mutagenesis to achieve increased tolerance towards serine. Additionally, overexpression of eamA, a cysteine/homoserine transporter was demonstrated to increase serine tolerance from 1.6 g/L to 25 g/L. During fed batch fermentation, the resulting strain lead to the serine production titer of 11.7 g/L with yield of 0.43 g/g glucose, which is the highest yield reported so far for any organism.

Determination of chlormequat in pig serum and sow milk by LC–MS/MS

Chlormequat is a plant growth regulator widely used on cereals, and there is general concern that it may impair human fertility. A LC-MS/MS method for the analysis of chlormequat in milk and serum was developed and validated in connection with an investigation on the effect of chlormequat on pig reproduction. Validation of the method was based on recovery tests at three spiking levels, determined as double determinations and repeated at least four times. Samples were extracted with methanol-water-acetic acid, centrifuged, filtrated and determined by LC-MS/MS. The mean recoveries were in the range 80-110%, and the LOD was 0.2 ng/g for serum and 0.3 ng/g for milk. The values for repeatability and reproducibility were within 2/3 of the limits given by the Horwitz equation. Samples of pig serum (59) and sow milk (27) were analyzed using the method. Chlormequat was determined in four milk samples in the range of 0.4 ng/g to 1.2 ng/g and in all serum samples in the range of 0.2 ng/g-4.0 ng/g.

Survey of pesticide residues in table grapes: Determination of processing factors, intake and risk assessment

The differences in residue pattern between Italy and South Africa, the main exporters of table grapes to the Danish market, were investigated. The results showed no major differences with respect to the number of samples with residues, with residues being found in 54-78% of the samples. Exceedances of the European Union maximum residue limit (MRL) were found in five samples from Italy. A number of samples were rinsed to study the possible reduction of residues. For copper, iprodione, procymidone and dithiocarbamates a significant effect of rinsing was found (20-49% reduction of residues). However, no significant effect was found for organophosphorus pesticides and pyrethroids, whereas the number of samples with residues of benzilates, phenylamids and triazoles was insufficient to demonstrate any significant effects. An intake calculation showed that the average intake from Italian grapes was 3.9 microg day(-1) for pesticides and 21 microg day(-1) for copper. Correspondingly, the intakes from South African grapes were 2.6 and 5.7 microg day(-1), respectively. When the total exposure of pesticides from grapes were related to acceptable daily intake, expressed as the sum of Hazard Quotients, the exposure were approximately 0.5% for Italian samples and 1% for South African samples.

Processing factors and variability of pyrimethanil, fenhexamid and tolylfluanid in strawberries

An HPLC-MS/MS method for the analysis of three pesticides in strawberries was developed and validated. Recoveries were measured at three spiking levels and ranged from 85 to 99% (mean recoveries). The effects of processing of strawberries ranging from rinsing to jam production were investigated for the three fungicides tolylfluanid, fenhexamid and pyrimethanil, which were applied under field conditions. Kresoxim-methyl was also applied in the field, but was not found in any of the samples investigated. The effect of parameters such as preharvest interval, dose, harvest time and observed pesticide concentration after harvest (initial concentration, mg kg(-1)), were examined with respect to possible reduction of the pesticides. The results from rinsing showed that all three pesticides were reduced on average by 37% for tolylfluanid, by 34% for fenhexamid and by 19% for pyrimethanil. For tolylfluanid and fenhexamid, the initial concentration significantly affected the reduction. For fenhexamid, dose could also have a minor influence on reduction. For pyrimethanil, none of the parameters significantly influenced the reduction. For jam production, cooking significantly reduced tolylfluanid by an average of 91%. For fenhexamid and pyrimethanil, a smaller reduction was seen, 25% and 33%, respectively. The reduction of tolylfluanid and pyrimethanil was affected by the preharvest interval, while fenhexamid was affected by the initial concentration. The unit-to-unit variability of fungicide contents was also investigated and the variability factors for the three fungicides were from 1.9 to 2.8.

Estimation of the uncertainty in a multiresidue method for the determination of pesticide residues in fruit and vegetables

The estimation of uncertainty of an analytical result has become important in analytical chemistry. It is especially difficult to determine uncertainties for multiresidue methods, e.g. for pesticides in fruit and vegetables, as the varieties of pesticide/commodity combinations are many. In the present study, recommendations from the International Organisation for Standardisation's (ISO) Guide to the Expression of Uncertainty and the EURACHEM/CITAC guide Quantifying Uncertainty in Analytical Measurements were followed to estimate the expanded uncertainties for 153 pesticides in fruit and vegetables. Data from in-house validation were used in the estimation of the uncertainty. No significant difference in the relative standard deviation for reproducibility (RSD(R)) were found between the different concentration levels at concentration levels exceeding 2.5 times the detection limit. Therefore, it was possible to pool the RSD(R) within a single matrix. However, a difference in RSD(R) between matrices was seen, thus the poorest RSD(R) of the investigated matrices was chosen for the uncertainty estimation. The expanded uncertainties ranged from 7 to 78% with an average of 32% and median of 32%. Furthermore, only RSD(R) contributed to the uncertainty estimation.

Method validation for strobilurin fungicides in cereals and fruit

Strobilurins are a new class of fungicides that are active against a broad spectrum of fungi. In the present work a GC method for analysis of strobilurin fungicides was validated. The method was based on, extraction with ethyl acetate/cyclohexane, clean-up by gel permeation chromatography, (GPC) and determination of the content by gas chromatography (GC) with electron capture (EC-), nitrogen/phosphorous (NP-), and mass spectrometric (MS-) detection. Three strobilurins, azoxystrobin, kresoxim-methyl and trifloxystrobin were validated on three matrices, wheat, apple and grapes. The validation was based on recovery tests at three or four spiking levels, determined as double determinations and repeated three times (n = 6). The mean recoveries for the three detectors were in the range of 70-114%, and the LODs were between 0.004 mg/kg and 0.014 mg/kg, for all three strobilurins. The values for repeatability and reproducibility were within the limits for repeatability and reproducibility given by the Horwitz equation. Validation was not accepted for azoxystrobin in grapes on all three detectors and for azoxystrobin in apple for the MS-detector. A comparison of matrix-matched standards versus standards in solvent showed varying differences between the two calibration curves.

Behavioural and emotional problems in children of alcoholic mothers and fathers

The Child Behavior Check List (CBCL) was used to compare a sample of 103 Danish children of alcoholics (CoA) to a Danish population-based sample (N = 780). The CoA had a significantly greater incidence of symptoms on 17 of the 118 CBCL items. Compared to the reference population, daughters of alcoholics were more impaired than sons of alcoholics on most CBCL measures. In families with maternal alcoholism daughters had higher internalising and depression scores than sons, and in families with paternal alcoholism, sons had higher internalising and depression scores than daughters. The CoA also had a significantly greater risk of scoring above the 95th percentile on internalising behaviour, depression symptoms and socially deviant behaviour. On all CBCL dimensions, almost half of the CoA samples functioned as well as the average of the reference population. The results from this study suggest that CoA should be regarded as a risk group but with very heterogeneous consequences in response to parental alcoholism.

Transfer of primed CD4+OX40- T lymphocytes induces increased immunity to experimental Salmonella typhimurium infections in rats

The protective effect of primed CD4 T cells against a lethal dose of Salmonella typhimurium was studied in Lewis rats. Primed CD4 T cells were obtained by inoculating Lewis rats with a non-lethal dose of S. typhimurium. Four weeks after the infection, spleen non-adherent mononuclear cells were isolated. The cells were separated according to their expression of CD4 and the OX40 antigen by FACS. OX40+ and OX40- CD4+ T-cell subpopulations were together with unsorted CD4+ T cells transferred to untreated rats 24 h prior to infection with S. typhimurium. Transfer of either unsorted CD4+ T cells or CD4+ T cells sorted into OX40- or OX40- subpopulations significantly increased animal survival compared to controls. Animals receiving OX40+CD4+ T cells did not differ significantly in survival probability from those receiving unsorted CD+ T cells. However, animals receiving OX40-CD4+ T cells had a significantly better survival compared to animals given unsorted CD4+ T cells. It is concluded that OX40-CD4+ T cells can induce significant protection against S. typhimurium infections in rats. This is most likely due to the fact that the OX40-CD4+ T-cell population contains a significant number of antigen-specific memory T cells that have returned to a resting state.

Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD45RC+ and CD45RC- CD4 T-cell subpopulations

The protective effect of primed CD4 T cells against a lethal dose of Salmonella typhimurium was studied in Lewis rats. Primed CD4 T cells were obtained by inoculating Lewis rats with a non-lethal dose of S. typhimurium. Four weeks after the infection, spleen CD4 T cells were separated by antibody-coated magnetic microspheres using an antibody against the CD4 molecule (W3/25). The cells were separated according to their expression of the CD45RC isoform of the leukocyte common antigen by FACS. CD45RC+ and CD45RC- CD4 T-cell subpopulations were transferred to untreated rats 24 h prior to infection with S. typhimurium. Transfer of CD45RC+ and CD45RC- CD4 T cells induced a significant survival, p = 0.022 and p = 0.023 respectively, following inoculation with S. typhimurium compared to animals with no cells transferred. The infection induced an increase in CD4 T cells expressing the CD45RC isoform compared to untreated controls (p < 0.001). It is concluded that both CD45RC+ and CD45RC- cells can induce a significant protection against S. typhimurium infections in rats. Therefore the CD45RC antigen cannot be used as a phenotypic marker for functionally distinct CD4 T-cell subpopulations. The infection-induced increase in CD45RC+ cells is most likely due to generation of antigen-specific memory T cells.

Pituitary adenylate cyclase-activating polypeptide: occurrence and relaxant effect in female genital tract

The distribution, localization, and smooth muscle effects of pituitary adenylate cyclase-activating polypeptide (PACAP) were studied in the human female genital tract. The concentrations of PACAP-38 and PACAP-27 were measured by radioimmunoassays, and both peptides were found throughout the genital tract. The highest concentrations of PACAP-38 were detected in the ovary, the upper part of vagina, and the perineum. The concentrations of PACAP-27 were generally low, in some regions below the detection limit and in other regions 1 to 5% of the PACAP-38 concentrations. Immunocytochemistry revealed that PACAP was located in delicate varicose nerve fibers that were most abundant in the internal cervical os, where they mainly seemed to innervate blood vessels and smooth muscle cells. PACAP-38 and PACAP-27 (10(-10)-10(-6) M) caused a concentration-dependent relaxation of the spontaneous activity of the nonvascular smooth muscle strips from fallopian tube and myometrium in vitro. Likewise, both peptides (10(-10)-10(-6) M) caused relaxation of nonrepinephrine (10(-6) M)-precontracted intramyometrial arteries. No effect of the PACAP sequences, PACAP-(6-27), PACAP-(16-38), and PACAP-(18-27), on fallopian tube was observed. The findings suggest a smooth muscle regulatory role of PACAP in the human female reproductive tract.

Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD4+CD25high and CD4+CD25low T lymphocytes

The protective effect of primed CD4+ T lymphocytes against a lethal dose of 10(8) viable Salmonella typhimurium was studied in Lewis rats. Primed CD4+ T lymphocytes were obtained by inoculating Lewis rats with a non-lethal dose of 10(6) viable S. typhimurium. Four weeks after the infection, spleen CD4+ T lymphocytes were separated using magnetic microspheres coated with an antibody against the CD4 molecule (W3/25). Subsequent sorting into activated and non-activated subpopulations using the p55 alpha-chain of the interleukin-2 receptor (CD25) as an activation marker was performed by a fluorescence-activated cell sorter. Untreated Lewis rats were injected with 10(4) different primed CD4+ T-cell populations 24 h prior to the lethal dose of 10(8) viable S. typhimurium. Blood samples were drawn from the orbital plexus 1, 2, 3, and 4 weeks after the infection, and analysed for specific IgM and IgG antibodies. Cell sorting revealed that 2/3 of the primed CD4+ T lymphocytes expressed high levels of CD25. Cell transfer revealed that both CD25high and CD25low expression populations could induce immunity against a lethal dose of S. typhimurium, whilst antibody analysis revealed that antibody levels were not correlated with protection against S. typhimurium infections, although it showed that a higher and more persistent level of specific IgG antibodies was produced in animals receiving the CD4+CD25high fraction. It is concluded that 10(4) primed CD4+ T lymphocytes can induce immunity in animals challenged with a lethal dose of S. typhimurium and that antibodies do not seem to be correlated with the immunity induced. The CD4+CD25high fraction was, however, associated with a higher and more persistent level of specific IgG antibodies.

Athymic experimental animals in pharmaco-immunological research

Immunodeficient animals--the nude mouse and the nude rat--allow studies of drug action and possible side effects without interference from the immune system. Comparative investigations in athymic and euthymic animals allowed us to elucidate the role of T-lymphocytes in the pathogenesis of streptozotocin-induced diabetes mellitus in mice, and the importance of NK-cells as effectors in guanethidine-induced sympathectomy in the rat. It is suggested that immunodeficient animals should be included in toxicological studies of xenobiotics.

Effect of immunosuppressive agents on the guanethidine-induced sympathectomy in athymic and euthymic rats

Guanethidine sulphate causes destruction of peripheral sympathetic neurons and infiltration of mononuclear inflammatory cells in the sympathetic ganglia of both athymic nude (rnu/rnu) and euthymic LEW/Mol rats. The effect of guanethidine is believed to be an autoimmune reaction. To determine the effect of immunosuppressive drugs concurrently with guanethidine treatment both athymic and euthymic rats were treated with guanethidine 40 mg/kg i.p. daily for 14 days, cyclophosphamide 100 mg/kg i.p. on days 1 and 8, methylprednisolone 10 mg/kg and cyclosporin A 10 mg/kg daily from days 1 to 7, and then every other day from days 8 to 14. The number of neurons in the sympathetic ganglia was counted and four subpopulations of mononuclear inflammatory cells were identified by monoclonal antibodies MHC II, CD8 T-cells/NK-cells, CD5 T-cells, CD4 T-cells/macrophages. Our results show that the immunosuppressive drugs used were unable to prevent the guanethidine-induced reduction of sympathetic neurons, although the number, of neurons following guanethidine-methylprednisolone treatment was significantly higher compared with guanethidine alone in both athymic and euthymic rats. The identification of mononuclear cells in the sympathetic ganglia showed that the CD8/NK and CD5 populations were the populations primarily responding to guanethidine treatment. Both CD8/NK and CD5 populations were absent without guanethidine, but increased significantly following guanethidine in both athymic and euthymic animals. None of the immunosuppressive drugs used could prevent the guanethidine-induced rise in the CD8/NK population in neither athymic nor in euthymic rats. The rise in the CD5 population was suppressed following treatment with all immunosuppressive drugs in athymic rats, but only following methylprednisolone in euthymic animals. These results indicate that guanethidine induces proliferation of T-cells in euthymic rats and non-functional CD5 positive pre T-cells in athymic animals. The CD5 population in both athymic and euthymic animals appears relatively more sensitive to immunosuppressive drugs than the NK-cell population also activated by guanethidine. This relatively resistant NK-cell population seems to play an important role in the guanethidine-induced destruction of sympathetic neurons and can explain why the guanethidine-induced immunological reaction could not be fully prevented by the immunosuppressive drugs used. The conclusion is that guanethidine induces destruction of sympathetic neurons by a NK-cell-mediated reaction.

[Premature ejaculation--results of treatment of men of 2 different cultural backgrounds]

The object of this investigation was to compare Danish and Muslim men treated for premature ejaculation in the Department of Sexology, Rigshospitalet, Copenhagen. The investigation is a retrospective review from the period 1986-1989. The following variables were included in the investigation: Mode of referral, personal data, duration of sexual dysfunction, previous sexological/psychiatric treatment, methods of treatment and results of treatment. The material consists of 60 Danish and 32 Muslim men. The investigation reveals that the Muslim men predominantly receive individual therapy of brief duration. Fewer Muslims were instructed in sensuality training and fewer carry out stop-start-treatment. The Muslim men responded more poorly to treatment than the Danish men. The differences in the therapeutic methods and therapeutic results cannot be explained on the basis of the personal parameters and possible cultural obstacles to treatment are suggested. For example, the therapist must become familiar with taboos and beliefs in the Muslim culture. The referring instance should inform the patients about the therapeutic principles at the Department of Sexology and attempts must be made to motivate possible partners to participate in the treatment.

Anti-asialo GM1 antibodies prevents guanethidine-induced sympathectomy in athymic rats

Guanethidine sulphate induces destruction of peripheral sympathetic neurons and infiltration of mononuclear cells in rat sympathetic ganglia. The effect of guanethidine is believed to be an autoimmune reaction. In order to determine the effect of anti-asialo GM1, an antibody that binds to the glycolipid asialo GM1 expressed on rodent natural killer cells, athymic Lewis rats received guanethidine 40 mg/kg i.p. daily from day 1 to 14 and anti-asialo GM1 i.p. 1 mg/rat on day -2, 0, 2, 6, and 10 in the study period. Saline and anti-asialo GM1 were given alone in the same doses as control. The number of neurons in the sympathetic ganglia were counted and the ganglionic volume determined. The presence of natural killer cells in the ganglia were determined by immunohistochemical methods. Our results shows that anti-asialo GM1 can prevent guanethidine-induced reduction of sympathetic neurons, but not prevent the initiation of an immunological reaction in the ganglia. Natural killer cells could only be identified in ganglia following guanethidine treatment alone. It is concluded that anti-asialo GM1 treatment can prevent the guanethidine-induced sympathectomy by eliminating the natural killer cells from the ganglia.

Identification of the mononuclear cell infiltrate in the superior cervical ganglion of athymic nude and euthymic rats after guanethidine-induced sympathectomy

Guanethidine sulphate 40 mg/kg intraperitoneally for 14 days induced chromatolysis and nerve cell death in the superior cervical ganglia of athymic nude (rnu/rnu) LEW/Mol rats and their euthymic (+/rnu) LEW/Mol heterozygous littermates. Histologically the sympathetic ganglia were dominated by an infiltration of small inflammatory cells. By means of monoclonal antibodies these cells were identified. The number of B-lymphocytes increased following guanethidine in both athymic and euthymic rats. The number of T-lymphocytes increased to a great extent in euthymic rats, but was virtually missing in athymic rats. The number of NK-cells and monocytes/macrophages increased in both athymic and euthymic rats. The conclusion is, that guanethidine exerts a direct effect on sympathetic ganglion cells followed by a thymus-independent immune response.

[Immersion in a bath despite a safety bath chair]

A case of submersion is described. A mother left her child aged 8 1/2 months sitting in a "safety bath chair" in a full bath and found the child lying under the water shortly afterwards. The infant was hypotonic for a brief period but rapidly recovered without sequelae. Use of a "safety bath chair" gives a false sense of security and its use is warned against.

Guanethidine-induced sympathectomy in the nude rat

Guanethidine sulphate 40 mg/kg was administered intraperitoneally daily for 14 days to normal Lewis rats and athymic nude rats of a Lewis background (rnu/rnu). Histological examination of the superior cervical ganglia demonstrated a pronounced chromatolysis of the neurones and a loss of the major part of the nerve cells accompanied by an increased number of small mononuclear inflammatory cells. The extent of chromatolysis and nerve cell death induced by guanethidine did not differ between normal and nude rats, whereas the increase of the number of mononuclear cells was lower in the nude rats than in the normal rats (163 and 268 per cent respectively of the saline treated controls, P less than 0.01). Since guanethidine induced nerve cell death in the T-cell deficient nude rat to the same extent as in normal rats, it is concluded, that the effect is caused by either a thymus-independent immune-response or by a direct toxic effect.