Bioconjugation of Vegetable Oils with UV Absorbers: New Approach in Skin Photoprotection

We reported the tunable synthesis of new vegetable oil-UV filter bioconjugates using sea buckthorn oil (SBO) and p-methoxycinnamic acid (p-MCA) as an alternative to the common UV filter, ethylhexyl-p-methoxycinnamate (octinoxate). The synthetic strategy is based on the sustainable ring-opening reaction of epoxidized SBO with p-MCA in heterogenous catalysis in eco-friendly solvents. The amount of UV-absorptive moieties grafted on the triglyceride backbone is controlled by different epoxidation degrees as determined by NMR spectroscopy. The performance of the new UV-absorber bioconjugates was assessed by in vitro sun protection factor (SPF) measurements after inclusion in SBO-ethylcellulose (EC) oleogels and comparison with the SPF value of the SBO-EC-octinoxate oleogel with equivalent p-MCA acid moieties (10% wt/wt). The concentration obtained for the SBO-EC oleogel formulated with the bioconjugate with the lowest degree of functionalization, namely 55%, represents 45% of the SPF determined for the SBO-EC-octinoxate oleogel, regardless of the concentration of measured solutions. The new concept of vegetable oil-UV-absorber bioconjugates has potential UV-B photoprotective properties when included in oleogel formulations and deserves further investigation of their properties and stability including association with UV-A absorbers, respectively.

Superior Valorisation of Juglans regia L. Leaves of Different Maturity through the Isolation of Bioactive Compounds

Extracts rich in bioactive compounds from natural sources have received great interest due to their great impact on human health. The aim of this research is focused on the obtaining and characterization of several extracts from Juglans regia L. leaves in four different maturity phases: young green leaves (YGL), green leaves (GL), mature green leaves (MGL), and yellow leaves (YL), using different solvents: ethanol (e), water (w), or water:ethanol (1:1 (v/v)-m) by employing several methods: magnetic stirring (MS), ultrasound-assisted (UA), as well as maceration (M). The obtained extracts were quantitatively evaluated through spectrophotometric methods: Total Polyphenol Content (TPC-Folin-Ciocalteu assay) and Total Antioxidant Capacity (TEAC assay). Phytochemical screening by means of Fourier-Transform Ion-Cyclotron-Resonance High-Resolution Mass Spectrometry (FT-ICR-MS) indicated the presence of 40 compounds belonging to different phytochemical classes: phenolic acids, flavonoids, flavones, flavanones, flavonones, flavanols, vitamins, tereponoid, steroid, anthocyanidin, and other compounds. Based on TPC and TEAC assays, the water-ethanol mixture was found to be the proper extraction solvent, with the best results being obtained for YL plant material: 146.29 mg GAE/g DM (TPC) and 11.67 mM TE/g DM (TEAC). This type of extract may be used in various domains, such as the cosmetics industry, the biomedical field, and/or the design of functional foods, relying on their phytochemical composition.

Effects of Extraction Process Factors on the Composition and Antioxidant Activity of Blackthorn (Prunus spinosa L.) Fruit Extracts

This study aimed at establishing the optimal conditions for the classic extraction of phenolic compounds from Prunus spinosa L. fruits. The effects of different parameters, i.e., ethanol concentration in the extraction solvent (mixture of ethanol and water), operation temperature, and extraction time, on process responses were evaluated. Total phenolic content (TPC), total anthocyanin content (TAC), antioxidant capacity (AC), and contents of protocatechuic acid (PA), caffeic acid (CA), vanillic acid (VA), rutin hydrate (RH), and quercetin (Q) of fruit extracts were selected as process responses. A synergistic effect of obtaining high values of TPC, TAC, AC, PA, and VA was achieved for the extraction in 50% ethanol at 60 °C for 30 min. At a higher level of process temperature, the extraction of protocatechuic acid and vanillic acid was enhanced, but the flavonoids, i.e., rutin hydrate and quercetin, were degraded. A lower temperature should be used to obtain a higher amount of flavonoids. TPC, TAC, AC, and phenolic acid contents (PA, CA, and VA) in the extract samples obtained at an ethanol concentration of 50-100%, a temperature of 30-60 °C, and an extraction time of 30 min were strongly directly correlated.

Quality Assurance and Cost Reduction in Histopathology Laboratories Using Tissue Microarrays

In the context of cost increases of both labor and consumables, cheaper and faster histopathology methods are needed. We implemented in our research laboratory the use of tissue microarrays (TMA) for the parallel processing and analysis of tissue samples. In this study, we used seven pre-processed, paraffinated biomimetic sectionable support matrices serving as "recipient" paraffin blocks to embed a total of 196 tissue cores from formalin-fixed paraffin-embedded tissue samples (serving as "donor" paraffin blocks) from seven different rabbit organs. These tissue samples were obtained using four different processing protocols: two 6 h protocols with xylene as the transition solvent, and two using butanol instead (one 10 h in duration and the other 72 h long). While the samples from protocols 1 and 2 (with xylene) quite regularly generated peeling of some of the cores from the slides (most likely because of substandard paraffin infiltration), butanol processing performed flawlessly for both processing protocols. Our proposed technique of using TMAs in the research laboratory brings with it a significant reduction in time and consumable costs (up to 77 and 64%, respectively), but also new challenges for all the upstream processes.

Lipoprofiling Assessed by NMR Spectroscopy in Patients with Acute Coronary Syndromes: Is There a Need for Fasting Prior to Sampling?

Most patients presenting in an emergency unit with acute coronary syndromes (ACS) (which include non-ST-elevation myocardial infarction (NSTEMI), ST-elevation MI (STEMI), and unstable angina) usually meet at least two cardiovascular risk factors, such as dyslipidemia, arterial hypertension, diabetes mellitus type 2, obesity, history of or current smoking, etc. Most ACS patients suffer from a type of dyslipidemia, and in addition to this there are ACS patients rushed into the emergency units for which the feeding status is unknown. Thus, we set out to evaluate the effect of fasting on 16 blood metabolite concentrations and 114 lipoprotein parameters on one control group and a group of statin-treated ACS patients hospitalized in a cardiovascular emergency unit, using Nuclear Magnetic Resonance (NMR) spectroscopy. The results indicated trends (in terms of number of cases, but not necessarily in terms of the magnitude of the effect) for as many as four metabolites and 48 lipoproteins. The effect was defined as a trend for results showing over 70% of the cases from either one or both groups that experienced parameter changes in the same direction (i.e., either increased or decreased). In terms of magnitude, the effect is rather low, leading to the overall conclusion that in cardiovascular (CV) emergency units, the blood samples analyzed in any feeding status would provide close results and very valuable information regarding prognosis and for fast decisions on patient’s proper management.

Electrospun-Fibrous-Architecture-Mediated Non-Viral Gene Therapy Drug Delivery in Regenerative Medicine

Gene-based therapy represents the latest advancement in medical biotechnology. The principle behind this innovative approach is to introduce genetic material into specific cells and tissues to stimulate or inhibit key signaling pathways. Although enormous progress has been achieved in the field of gene-based therapy, challenges connected to some physiological impediments (e.g., low stability or the inability to pass the cell membrane and to transport to the desired intracellular compartments) still obstruct the exploitation of its full potential in clinical practices. The integration of gene delivery technologies with electrospun fibrous architectures represents a potent strategy that may tackle the problems of stability and local gene delivery, being capable to promote a controlled and proficient release and expression of therapeutic genes in the targeted cells, improving the therapeutic outcomes. This review aims to outline the impact of electrospun-fibrous-architecture-mediated gene therapy drug delivery, and it emphatically discusses the latest advancements in their formulation and the therapeutic outcomes of these systems in different fields of regenerative medicine, along with the main challenges faced towards the translation of promising academic results into tangible products with clinical application.

Macrophage-targeted mannose-decorated PLGA-vegetable oil hybrid nanoparticles loaded with anti-inflammatory agents

This work pledge to extend the therapeutic windows of hybrid nanoparticulate systems by engineering mannose-decorated hybrid nanoparticles based on poly lactic-co-glycolic acid (PLGA) and vegetable oil for efficient delivery of two lipophilic anti-inflammatory therapeutics (Celecoxib-CL and Indomethacin-IMC) to macrophages. The mannose surface modification of nanoparticles is achieved via O-palmitoyl-mannose spacer during the emulsification and nanoparticles assembly process. The impact of targeting motif on the hydrodynamic features (R_H, PdI), stability (ζ-potential), drug encapsulation efficiency (DEE) is thoroughly investigated. Besides, the in vitro biocompatibility (MTT, LDH) and susceptibility of mannose-decorated formulations to macrophage as well their immunomodulatory activity (ELISA) are also evaluated. The monomodal distributed mannose-decorated nanoparticles are in the range of nanometric size (R_H < 115 nm) with PdI < 0.20 and good encapsulation efficiency (DEE = 46.15% for CL and 76.20% for IMC). The quantitative investigation of macrophage uptake shows a 2-fold increase in fluorescence (RFU) of cells treated with mannose-decorated formulations as compared to non-decorated ones (p < 0.001) suggesting an enhanced cell uptake respectively improved macrophage targeting while the results of ELISA experiments suggest the potential immunomodulatory properties of the designed mannose-decorated hybrid formulations.

A Real-Life Reproducibility Assessment for NMR Metabolomics

Nuclear magnetic resonance (NMR) metabolomics is currently popular enough to attract both specialized and non-specialized NMR groups involving both analytical trained personnel and newcomers, including undergraduate students. Recent interlaboratory studies performed by established NMR metabolomics groups demonstrated high reproducibility of the state-of-the-art NMR equipment and SOPs. There is, however, no assessment of NMR reproducibility when mixing both analytical experts and newcomers. An interlaboratory assessment of NMR quantitation reproducibility was performed using two NMR instruments belonging to different laboratories and involving several operators with different backgrounds and metabolomics expertise for the purpose of assessing the limiting factors for data reproducibility in a multipurpose NMR environment. The variability induced by the operator, automatic pipettes, NMR tubes and NMR instruments was evaluated in order to assess the limiting factors for quantitation reproducibility. The results estimated the expected reproducibility data in a real-life multipurpose NMR laboratory to a maximum 4% variability, demonstrating that the current NMR equipment and SOPs may compensate some of the operator-induced variability.

Microwave-Assisted Sol-Gel Preparation of the Nanostructured Magnetic System for Solid-Phase Synthesis

This work describes a new synthesis method for core–shell magnetite nanoparticles with a secondary silica shell, functionalized with a linker system (Fe₃O₄-PABA-SiO₂-linker) using a microwave-assisted heating technique. The functionalized solid nanomaterial was used for the nanophase synthesis of peptides (Fmoc route) as a solid support. The co-precipitation method was selected to obtain magnetite nanoparticles and sol–gel technique for silica coating using a microwave-assisted (MW) procedure. The magnetic properties of the nanoparticle core offer the advantage of a quick and easy alternative for the magnetic separation of the product from the reaction mixture, facilitating all the intermediary washing and separation operations. The intermediate and final materials were analyzed by advanced characterization methods. The effectiveness of the nanophase peptide synthesis using this nanostructured material as solid support was demonstrated for a short peptide sequence.

Composite Materials from Renewable Resources as Sustainable Corrosion Protection Coatings

Epoxidized linseed oil (ELO) and kraft lignin (LnK) were used to obtain new sustainable composites as corrosion protection layers through a double-curing procedure involving UV radiation and thermal curing to ensure homogeneous distribution of the filler. The crosslinked structures were confirmed by Fourier-transform infrared spectrometry (FTIR), by comparative monitorization of the absorption band at 825 cm^-1, attributed to the stretching vibration of epoxy rings. Thermal degradation behavior under N2 gas indicates that the higher LnK content, the better thermal stability of the composites (over 30 °C of Td10% for ELO + 15% LnK), while for the experiment under air-oxidant atmosphere, the lower LnK content (5%) conducted to the more thermo-stable material. Dynamic-mechanic behavior and water affinity of the new materials were also investigated. The increase of the Tg values with the increase of the LnK content (20 °C for the composite with 15% LnK) denote the reinforcement effect of the LnK, while the surface and bulk water affinity were not dramatically affected. All the obtained composites were tested as carbon steel corrosion protection coatings, resulting in significant increase of corrosion inhibition efficiency (IE) of 140-380%, highlighting the great potential of the bio-based ELO-LnK composites as a future perspective for industrial application.

Harnessing a byproduct from wastewater treatment to obtain improved starch/poly(vinyl alcohol) composites

A rational method to harness a triglyceride-based by-product containing chicken fat traces, extracted from the simulated slaughterhouses wastewater was adopted. Methacrylated linseed oil was used as photo-reactive monomer to "catch" the grease molecules, resulting in a polymeric network (PFrec), further embedded in starch/poly(vinyl alcohol) (St/PVA)-based composites, with or without plasticizer (glycerol-Gly), with enhanced properties. Hydrophobic additive improved the thermal stability of St/PVA blends, an 18 ⁰C increase of Td3 % being registered for PFrec-loaded sample. Mechanical tests revealed that association of PFrec with Gly improved the flexibility and also reinforced the systems, although, no plasticizing effect was observed at PFrec addition. Solubility determinations for the St/PVA-based composite films showed that hydrophobic PFrec increased the water resistance with at least 40 %. According to contact angle measurements a good dispersion of PFrec in the St/PVA network was mediated at the interface by hydrophilic Gly molecules.

Novel PEG-Modified Hybrid PLGA-Vegetable Oils Nanostructured Carriers for Improving Performances of Indomethacin Delivery

The purpose of this work was to more exhaustively study the influence of nanocarrier matrix composition and also the polyethylene glycol (PEG)-modified surface on the performances of formulations as lipophilic drug delivery systems. Poly (d,l-lactide-co-glycolide), two vegetable oils (Nigella sativa oil and Echium oil) and indomethacin were employed to prepare novel PEG-coated nanocarriers through emulsion solvent evaporation method. The surface modification was achieved by physical PEG adsorption (in the post-production step). Transmission electron microscopy (TEM) nanographs highlighted the core-shell structure of hybrid formulations while scanning electron microscopy (SEM) images showed no obvious morphological changes after PEG adsorption. Drug loading (DL) and entrapment efficiency (EE) varied from 4.6% to 16.4% and 28.7% to 61.4%, solely depending on the type of polymeric matrix. The oil dispersion within hybrid matrix determined a more amorphous structure, as was emphasized by differential scanning calorimetry (DSC) investigations. The release studies highlighted the oil effect upon the ability of nanocarrier to discharge in a more sustained manner the encapsulated drug. Among the kinetic models employed, the Weibull and Korsmeyer-Peppas models showed the better fit (R² = 0.999 and 0.981) with n < 0.43 indicating a Fickian type release pattern. According to cytotoxic assessment the PEG presence on the surface increased the cellular viability with ~1.5 times as compared to uncoated formulations.

Naringenin improves the sunscreen performance of vegetable nanocarriers

Naringenin enhances the UV protection, photostability and cell viability of lipid based vegetable nanocarriers.

Hybrid networks based on epoxidized camelina oil

Lately, renewable resources received great attention in the macromolecular compounds area, regarding the design of the monomers and polymers with different applications. In this study the capacity of several modified vegetable oil-based monomers to build competitive hybrid networks was investigate, taking into account thermal and mechanical behavior of the designed materials. In order to synthesize such competitive nanocomposites, the selected renewable raw material, camelina oil, was employed due to the non-toxicity and biodegradability behavior. General properties of epoxidized camelina oil-based materials were improved by loading of different types of organic-inorganic hybrid compounds – polyhedral oligomeric silsesquioxane (POSS) bearing one (POSS1Ep) or eight (POSS8Ep) epoxy rings on the cages. In order to identify the chemical changes occurring after the thermal curing reactions, FT-IR spectrometry was employed. The new synthesized nanocomposites based on epoxidized camelina oil (ECO) were characterized by dynamic mechanical analyze and thermogravimetric analyze. The morphology of the ECO-based materials was investigate by scanning electron microscopy and supplementary information regarding the presence of the POSS compounds were establish by energy dispersive X-ray analysis and X-ray photoelectron spectroscopy. The smooth materials without any separation phase indicates a well dispersion of the Si–O–Si cages within the organic matrix and the incorporation of this hybrid compounds into the ECO network demonstrates to be a well strategy to improve the thermal and mechanical properties, simultaneously.

Ivy leaves extract based – lipid nanocarriers and their bioefficacy on antioxidant and antitumor activities

Two issues were addressed in the paper: (1) the use of medicinal herbs as functional ingredients entrapped into lipid-based nanocarriers; (2) the efficacy of phytochemical-based nanocarriers with promising antioxidant and antitumor benefits.

Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported.

Novel bio-active lipid nanocarriers for the stabilization and sustained release of sitosterol

In this work, new stable and efficiently bio-active lipid nanocarriers (NLCs) with antioxidant properties have been developed for the transport of active ingredients in food. The novel NLCs loaded with β-sitosterol/β-sitosterol and green tea extract (GTE) and prepared by a combination of natural oils (grape seed oil, fish oil and squalene) and biological lipids with food grade surfactants, were physico-chemically examined by DLS, TEM, electrokinetic potential, DSC and HPLC and found to have main diameters less than 200 nm, a spherical morphology, excellent physical stability, an imperfect crystalline lattice and high entrapment efficiency. The novel loaded-NLCs have demonstrated the potential to develop a high blocking action of chain reactions, trapping up to 92% of the free-oxygen radicals, as compared to the native β-sitosterol (AA%=36.5). Another advantage of this study is associated with the quality of bio-active NLCs based on grape seed oil and squalene to manifest a better sitosterol-sustained release behaviour as compared to their related nanoemulsions. By coupling both in vitro results, i.e. the enhanced antioxidant activity and superior release properties, this study emphasizes the sustainability of novel bio-active nanocarriers to gain specific bio-food features for development of functional foods with a high applicability spectrum.

Catanionic Organogelators Derived from D-Sorbitol and Natural Fatty Acids

Several catanionic organogelators derived from 1,3 :2,4-bis-O-(p-aminobenzylidene)-D-sorbitol (p-NH2-DBS) and hydroxy derivatives of natural fatty acids were synthesized, characterized and their gelation ability was evaluated. SEM observations of the xerogels formed by association of 1,3 :2,4-bis-O-(p-aminobenzylidene)-D-sorbitol and 12-hydroxystearic acid showed important modifications in the morphology and depend upon the nature of solvent as compared with the xerogels formed by each individual organogelator.

In vitro expansion of Ag-specific T cells by HLA-A*0201-transfected K562 cells for immune monitoring

BACKGROUND

Development of a practical and sensitive assay for evaluating immune responses against cancer Ag has been a challenge for immune monitoring of patients. We have established a reproducible method using peptide-pulsed K562-A*0201 cells as APC to expand Ag-specific T cells in vitro. This method may be applied for monitoring T-cell responses in cancer immunotherapy clinical trials.

METHODS

Autologous PBMC from HLA-A*0201+ healthy donors and patients with melanoma were stimulated with peptide-pulsed K562-A*0201 cells under varying conditions. We investigated (1) different culture conditions, including the requirements for serum and cytokines for expansion of CD8+ T lymphocytes; (2) a range of peptide concentrations for Ag loading; (3) phenotypic characterization of responding T cells; and (4) APC:responder ratios and their effects on T-cell expansion. We validated these conditions by ELISPOT and intracellular cytokine staining (ICS) assays using peptides from influenza, Epslein-Barr Virus (EBV) and tyrosinase.

RESULTS

Conditions for optimal T-cell expansion using K562-A*0201 APC included input of 2 x 10(6) PBMC, a 10 microg/mL peptide concentration to pulse K562-A*0201 cells, a 1:30 APC:responder T-cell ratio and culture in 10% autologous plasma supplemented with IL-2 and IL-15. In these conditions, Ag-specific T cells expanded >100-fold over a 10-day culture period (peak at day 12).

DISCUSSION

This bulk culture method is simple and reliable for expanding human Ag-specific T cells using peptide-pulsed K562-A*0201 cells. This HLA-matched APC line can be adapted to other HLA haplotypes, and has advantages for monitoring clinical trials of immunotherapy with limited availability of autologous APC and PBMC from patients.

DNA helicases, genomic instability, and human genetic disease

DNA helicases are a highly conserved group of enzymes that unwind DNA. They function in all processes in which access to single-stranded DNA is required, including DNA replication, DNA repair and recombination, and transcription of RNA. Defects in helicases functioning in one or more of these processes can result in characteristic human genetic disorders in which genomic instability and predisposition to cancer are common features. So far, different helicase genes have been found mutated in six such disorders. Mutations in XPB and XPD can result in xeroderma pigmentosum, Cockayne syndrome, or trichothiodystrophy. Mutations in the RecQ-like genes BLM, WRN, and RECQL4 can result in Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome, respectively. Because XPB and XPD function in both nucleotide excision repair and transcription initiation, the cellular phenotypes associated with a deficiency of each one of them include failure to repair mutagenic DNA lesions and defects in the recovery of RNA transcription after UV irradiation. The functions of the RecQ-like genes are unknown; however, a growing body of evidence points to a function in restarting DNA replication after the replication fork has become stalled. The genomic instability associated with mutations in the RecQ-like genes includes spontaneous chromosome instability and elevated mutation rates. Mouse models for nearly all of these entities have been developed, and these should help explain the widely different clinical features that are associated with helicase mutations.

[The influence of meteorological factors for frequency of Herpes simplex keratitis]

HYPOTHESIS

The variation of the meteorological factors could be a stress for the organism, which could determine the start of some diseases.

MATERIAL AND METHOD

We studied 252 cases of herpes simplex keratitis which had been hospitalized in Eye Clinic of Cluj between 1983-1991. The selection criteria were: known diagnosis; day of the rise could be exactly established; disease was taken place in Cluj or in region not longer than 30 km on Somes Valley. The meteorological parameters were collected by specialist from the Meteorological Station of the city and from the Cluj's Airport. The results were verified statistical and were guaranted by p = 0.05.

RESULTS

The herpes simplex keratitis are more frequently in days with a temperature higher and an atmospheric pressure lower than the average value of the season.

DISCUSSIONS

We drew a possible pathogenic mechanism to explained the reactivation of the virus under the influence of warm weather.

[Orbital tuberculoma]

We present a case of orbital tumor with skin lesions at the lateral cantus. CT scan confirmed the orbital tumor and we considered it to be malignant. The histological examination of a piece of the tumor showed tuberculous characteristics. Patient received treatment with antituberculous drugs and steroids. The tumor decreased after two months of treatment.

A role for PML and the nuclear body in genomic stability

The PML gene of acute promyelocytic leukemia (APL) encodes a cell-growth and tumor suppressor. PML localizes to discrete nuclear bodies (NBs) that are disrupted in APL cells. The Bloom syndrome gene BLM encodes a RecQ DNA helicase, whose absence from the cell results in genomic instability epitomized by high levels of sister-chromatid exchange (SCE) and cancer predisposition. We show here that BLM co-localizes with PML to the NB. In cells from persons with Bloom syndrome the localization of PML is unperturbed, whereas in APL cells carrying the PML-RARalpha oncoprotein, both PML and BLM are delocalized from the NB into microspeckled nuclear regions. Treatment with retinoic acid (RA) induces the relocalization of both proteins to the NB. In primary PML-/- cells, BLM fails to accumulate in the NB. Strikingly, in PML-/- cells the frequency of SCEs is increased relative to PML+/+ cells. These data demonstrate that BLM is a constituent of the NB and that PML is required for its accumulation in these nuclear domains and for the normal function of BLM. Thus, our findings suggest a role for BLM in APL pathogenesis and implicate the PML NB in the maintenance of genomic stability.

Purification of overexpressed hexahistidine-tagged BLM N431 as oligomeric complexes

BLM is a DNA helicase encoded by a gene which is mutated in persons with Bloom's syndrome. The protein is a member of the RecQ subfamily of helicases and contains a central domain constituted by the seven motifs conserved in all helicases. In contrast, the N-terminal portion of BLM lacks similarity to any other known proteins or motifs. We have expressed the first 431 amino acids of this domain as a fusion to a hexahistidine tag (BLM N431) in Escherichia coli. A method of purification was developed which involves elution from Ni-NTA resin in imidazole and EDTA, followed by treatment with DTT and gel filtration on Sephacryl-300. The treatment with EDTA and DTT prevents and disrupts aggregation of BLM N431. The purified protein appears to form hexamers and dodecamers, suggesting that the N-terminal domain of BLM is involved in the organization of the quaternary structure of BLM.

Interaction between FKBP12-rapamycin and TOR involves a conserved serine residue

The yeast TOR1 and TOR2 proteins were previously discovered as putative targets of the immunosuppressive drug rapamycin. Although their cellular function is unknown, they are predicted to be at least 215 kDa in size and possess a C-terminal phosphatidylinositol (PI) kinase-related domain. We previously identified a conserved Ser residue, within the PI kinase-related domain of both yeast TOR proteins (Ser1972 in TOR1; Ser1975 in TOR2), as being the site of missense mutations conferring dominant rapamycin resistance. The Ser1972/1975 residue of yeast TOR is conserved in mammalian TOR homologs. One possibility is that this residue is critical for a direct interaction between TOR and the FKBP12-rapamycin complex. There is very recent biochemical evidence for an interaction between mammalian TOR and FKBP12-rapamycin (Brown, E. J., Albers, M. W., Shin, T. B., Ichikawa, K., Keith, C. T., Lane, W. S., and Schreiber, S. L. (1994) Nature 369, 756-758; Sabatini, D. M., Erdjument-Bromage, H., Lui, M., Tempst, P., and Snyder, S. H. (1994) Cell 78, 35-43). Using the yeast two-hybrid system, we now have obtained genetic proof of a physical interaction between FKBP12-rapamycin and TOR and have demonstrated that this interaction requires the conserved Ser residue. We have found that a small fragment of wild-type yeast TOR2 spanning Ser1975 is capable of interacting with human FKBP12 in the presence of rapamycin, whereas an Arg1975 mutant fails to interact. This effect is dependent upon rapamycin and is antagonized by FK506.

Ergosterol levels in two L-methionine-enriched mutants of the methylotrophic yeast Candida boidinii ICCF26

Two L-methionine-enriched mutants, SN-78 and SE-57, were isolated in a sulphur-deficient medium from the methylotrophic yeast Candida boidinii ICCF26. No significant differences were detected between the L-cysteine pools of the mutants and the wild-type. In mutant strain SE-57, S-adenosylmethionine and ergosterol levels were higher than in the wild-type strain, while in the other mutant, SN-78, the levels were lower. The evidence presented would suggest that, in both the mutants and the wild-type used in this study, S-adenosylmethionine was of key importance for the accumulation of L-methionine and ergosterol.

Electrically induced protoplast fusion for ergosterol-producing yeast strain improvement

Electrofusion was employed for hybrid construction in ergosterol-producing yeast strains. Some fusion products proved to be hybrid with respect to ergosterol content and to remain stable over several generations.