The role of cysteine residues in the homeodomain protein Mat alpha 2 in mating-type control of Saccharomyces cerevisiae

The Mat alpha 2 homeodomain protein plays a pivotal role in the control of cell type in Saccharomyces cerevisiae. The homeodomain in the C-terminal region of Mat alpha 2 functions as a DNA-binding domain and the N-terminal region, containing two cysteine residues at positions 33 and 34, is thought to be involved in formation of Mat alpha 2 homodimers via disulfide bonds. mat alpha 2 mutants, isolated in a previous study, in which haploid-specific genes cannot be repressed by the Matal-Mat alpha 2 heterodimer but a-specific genes can be repressed by the Mat alpha 2 homodimer, were found to produce mutant Mat alpha 2 with a substitution of tyrosine or phenylalanine for Cys33. To clarify the role of Cys33 and Cys34 in the Mat alpha 2 protein, we generated several mat alpha 2 mutants by site-directed mutagenesis which had serine residues in place of these Cys residues. Transforming MATa cells with plasmids carrying these mat alpha 2 (MAT alpha 1+) mutations rendered transformants unable to mate. Northern blot analysis revealed that transcription of the a-specific gene STE2 and the haploid-specific locus RME1 in these transformants is repressed to the same level as in wild-type MATa/MAT alpha cells. We concluded that neither Cys33 nor Cys34 is required for repression of a-specific genes by the Mat alpha 2 homodimer or of haploid-specific genes by the Matal-Mat alpha 2 heterodimer, and therefore suggest that Mat alpha 2 homodimer formation in vivo is not mediated by disulfide linkage.

Comparative study of intraocular lens implantation through 3.0 mm temporal clear corneal and superior scleral tunnel self-sealing incisions

PURPOSE

To compare the clinical outcome of phacoemulsification and foldable silicone intraocular lens (IOL) implantation through a 3.0 mm temporal clear corneal incision and 3.0 mm superior scleral tunnel incision.

SETTING

Department of Ophthalmology, Yodogawa Christian Hospital, Osaka, Japan.

METHODS

Eighty cataractous eyes of 78 patients with pre-existing against-the-rule (ATR) astigmatism were recruited for this prospective, randomized study. The patients were assigned to one of the two groups. Data on uncorrected and corrected visual acuities, keratometry, flare intensity measurement, and central cornea endothelial cell count were evaluated preoperatively and at 2 days, 1 week, and 1 and 3 months postoperatively.

RESULTS

Although the pre-existing keratometric cylinder decreased in the temporal clear corneal incision group and increased in the superior scleral tunnel incision group, the amount of cylinder shift was not significantly different. Mean scalar shift of keratometric cylinder in the corneal incision group was 1.19 diopters (D) at 2 days postoperatively, 0.86 D at 1 week, and 0.56 D at 3 months and in the scleral incision group, 1.09 D at 2 days, 0.76 D at 1 week, and 0.65 D at 3 months. Eighty percent of the eyes in each group achieved an uncorrected visual acuity of 20/40 or better from the second day postoperatively. No statistically significant difference in visual rehabilitation or other parameters was noted between the groups throughout the study. Complications including corneal endothelial cell loss and wound incompetence requiring suturing were observed in the temporal clear corneal incision group.

CONCLUSIONS

Both incisions offered satisfactory clinical results, but the superior scleral tunnel incision resulted in fewer complications. Minimal corneal keratometric change induced by a 3.0 mm incision was not related to uncorrected visual rehabilitation.

Fatal GVHD demonstrating an involvement of respiratory muscle following donor leukocyte transfusion (DLT)

A 41-year-old female patient with AML, who relapsed after an allogeneic BMT from her HLA-identical sister, was treated by a donor leukocyte transfusion (DLT). Thereafter, bone marrow aplasia accompanied by the disappearance of leukemic blasts following the GVHD was observed. The patient died of chronic GVHD with respiratory muscle involvement 19 months after the DLT. Although the DLT was considered helpful in suppressing the proliferation of the leukemic cells, it might also have caused the severe GVHD observed in this case. Efforts to separate the lymphocyte clones responsible for GVL from those for the GVHD thus appear to be necessary for the further development of the therapeutic approach, so-called DLT.

[Treatment of age-related subfoveal choroidal neovascularization by low-dose external radiation: a preliminary study]

We applied low dose external beam radiation (6 MV) to 17 eyes of 17 patients (Mean age 70.9 years, range 58 approximately 85) who had subfoveal choroidal neovascularization associated with age-related macular degeneration. None of the cases were suitable for photocoagulation according to the Macular Photocoagulation Study protocol, and no feeding vessels underlying choroidal neovascular membrane could be detected. Corrected visual acuity ranged from 0.02 to 0.6 before treatment. The patients were divided into two groups. One group of 11 eyes was treated with 10 Gy and the other group of 6 eyes with 21 Gy. Mean follow up period was 347 +/- 89 (mean +/- standard deviation) days in the 10 Gy group and 312 +/- 100 days in the 21 Gy group. We evaluated the outcome as "effective' if no progression in neovascular membrane was found by ophthalmoscopic and angiographic examination. Only 3 eyes (21%) of patients in the 10 Gy group and 2 eyes (33%) in 21 Gy group showed any effect. Although the rate of progression in choroidal neovascular membrane was significantly smaller in the 10 and 21 Gy group than in the controls, the corrected visual acuity in the treated group was not improved over that of the controls. No serious complications were seen. Only one case showed a stabilized neovascular membrane in the control group of 7 patients. Although the present results seem to be worse than those in previous reports, the efficacy of this treatment still needs to be evaluated because no beneficial strategies in the treatment of subfoveal neovascularization have been established.

In vitro effects of a recombinant toxin, mSCF-PE40, targeting c-kit receptors ectopically expressed in small cell lung cancers

Most small cell lung cancers (SCLCs) ectopically express high levels of the c-kit receptor. We have examined if the receptor can serve as a target for a chimeric toxin, mSCF-PE40 composed of murine stem cell factor (SCF) genetically fused to the N terminus of a modified form of Pseudomonas exotoxin (PE) lacking its cell recognition domain. Selective cytotoxicity was found for human c-kit receptor-negative cells. This agent thus warrants further evaluation for therapy of human CSLCs.

The P-OLE1 gene of Pichia angusta encodes a delta 9-fatty acid desaturase and complements the ole1 mutation of Saccharomyces cerevisiae

Three PCR-amplified DNA fragments hybridizing with the OLE1 gene encoding delta 9-fatty acid desaturase of Saccharomyces cerevisiae were obtained using, respectively, genomic DNAs of one strain each of Kluyveromyces thermotolerans, Pichia angusta and Yarrowia lipolytica as templates. A gene designated P-OLE1 was cloned from the above fragment of P. angusta and sequenced. An open reading frame of P-OLE1 encodes a 49.6-kDa protein consisting of 451 amino acid residues, which shows high identity (62%) and similarity (89%) to that deduced from the OLE1 nucleotide sequence. Expression of P-OLE1 driven by the S. cerevisiae GAP promoter or its own promoter complemented the ole1 mutation of S.cerevisiae. Transcription of P-OLE1 in the native host was suggested to be partially repressed by oleic acid in the medium, as was that of OLE1 in S. cerevisiae and a similar gene in Y. lipolytica, but that of a similar gene in K. thermotolerans was not.

Effect of electric pulses and antiproliferative drugs on cultured bovine retinal pigment epithelial cells

PURPOSE

The effect of antiproliferative agents with high voltage electric pulses (EP) on the proliferation of retinal pigment epithelial (RPE) cells was investigated.

METHODS

Bovine RPE cells were cultured and exposed briefly to an antiproliferative agent: 0.005 to 500 microM of bleomycin (BLM), 0.005 to 500 microM of mitomycin C (MMC) or 0.05 to 5000 microM of 5-fluorouracil (5-FU) with or without high voltage electric pulses (EP: 2,000V/cm, 98 microseconds, 8 pulses). Streptomycin (SM) was used as a negative control. Cell proliferation with or without antiproliferative agents was assessed on day 3. DNA fragmentation was assessed by flow cytometric analysis.

RESULTS

Treatment with BLM, MMC or 5-FU inhibited cell proliferation in a dose-dependent manner, with and without EP (p < 0.05). EP enhanced the inhibitory effect of BLM as much as 3,000 times (ID50: BLM without EP; 163.7 microM, BLM with EP; 0.0574 microM, MMC without EP; 132.4 microM, MMC with EP; 26.2 microM, 5-FU without EP; 616.4 microM, 5-FU with EP; 873.8 microM). EP treatment showed an inhibitory effect of BLM on cell proliferation more prominently than BLM alone. The cell numbers of 0.5 microM BLM treatment without EP were 87.4 +/- 11.7% (mean +/- SD), whereas the cell numbers of 0.5 microM BLM with EP were 21.1 +/- 2.16% (p < 0.005). BLM treatment with EP increased the apoptosis like DNA fragmentation in the flow cytometric DNA histogram, showing dominant accumulation in the A0 region, which is the population of DNA fragmentation. (The cell population of the A0 region: control, 3.4%; EP alone, 18.9%; BLM treatment without EP, 32.0%; with EP, 93.8%.)

CONCLUSIONS

EP treatment enhances the inhibitory effect of BLM on RPE cell proliferation. The combination of electric pulse and BLM treatment can localize the drug effect and reduce the necessary dose of the antiproliferative agent in comparison to BLM treatment alone.

Autotrophic carbon dioxide fixation in Acidianus brierleyi

The autotrophic CO2 fixation pathway in Acidianus brierleyi, a facultatively anaerobic thermoacidophilic archaebacterium, was investigated by measuring enzymatic activities from autotrophic, mixotrophic, and heterotrophic cultures. Contrary to the published report that the reductive tricarboxylic acid cycle operates in A. brierleyi, the enzymatic activity of ATP:citrate lyase, the key enzyme of the cycle, was not detected. Instead, activities of acetyl-CoA carboxylase and propionyl-CoA carboxylase, key enzymes of the 3-hydroxypropionate cycle, were detected only when A. brierleyi was growing autotrophically. We conclude that a modified 3-hydroxypropionate pathway operates in A. brierleyi.

Regulation of phosphatase synthesis in Saccharomyces cerevisiae--a review

Transcription of the genes encoding acid and alkaline phosphatases and the inorganic phosphate (Pi) transporter of Saccharomyces cerevisiae are coordinately repressed and derepressed depending on the Pi concentration in the culture medium. This phosphatase system is particularly suited for the study of regulatory mechanisms, because the acid phosphatase activity of each colony on a plate is easily detected by specific staining methods and there is a 500-fold difference between the repressed and derepressed levels of acid phosphatase activity. With these advantages, considerable amounts of genetic and molecular evidence have been accumulated in the past two decades. This article summarizes our current knowledge on this subject.

Isolation and structure of prorocentrolide B, a fast-acting toxin from Prorocentrum maculosum

A new toxin, prorocentrolide B (1), has been isolated following bioassay-guided fractionation of a BuOH extract of the tropical dinoflagellate, Prorocentrum maculosum Faust. This compound produces a rapid toxic response in the mouse bioassay, a type of activity not accounted for by other diarrhetic shellfish poisoning toxins produced by P. maculosum. The structure 1 was established by NMR and MS and is similar to prorocentrolide (2), a toxin from a strain of Prorocentrum lima. NMR data and the modeling program ConGen have been used to establish the relative stereochemistry of some individual ether ring systems and the hexahydroisoquinoline ring.

[Bronchiolitis obliterans organizing pneumonia (BOOP) after allogeneic bone marrow transplantation]

We report a patient who underwent allogeneic bone marrow transplantation for ALL. The patient presented low grade fever, cough and dyspnea at day 3 after after bone marrow transplantation. Imaging studies showed bilateral patchy infiltrates on chest X-ray and chest CT. Though treated by antibiotics, chest auscultation recognized marked bilateral inspiratory crackles. Transbronchial lung biopsy performed on day 34 showed bronchiolitis obliterans and an organizing interstitial pneumonia. The patient was treated with methylprednisolone and follow up computed tomography findings improved.

[Inhibitory effect of vitamin E succinate on the proliferation of cultured bovine choroidal endothelial cells]

We report the effect of vitamin E succinate (VE succinate) on the proliferation of cultured bovine choroidal endothelial cells (BCECs). BCECs were incubated with a medium containing vitamin E (VE) or one of the VE derivatives gamma-tocopherol, VE phosphate, VE succinate, VE nicotinate, VE acetate, or trolox, at a concentration of 10 microM. The proliferation of BCECs was assessed by 3H-thymidine uptake and cell counting. Especially in VE and VE succinate, the proliferation assay was performed on BCECs at two different stages, that is, the proliferating stage and the quiescent stage. The effect of protein kinase C (PKC) stimulator phorbol ester (PMA) on the VE succinate-induced inhibition of BCEC proliferation was also examined. VE succinate was found to significantly inhibit BCEC proliferation at a concentration of 10 microM or greater both by 3H-thymidine uptake assay and by cell counting. This inhibitory effect was not noted in other VE derivatives. The inhibitory effect was the most prominent in the proliferating BCECs and co culture of PMA. VE succinate inhibits the proliferation of cultured BCECs and PKC is involved in this action at least in part.

A putative membrane protein, Pho88p, involved in inorganic phosphate transport in Saccharomyces cerevisiae

Transcription of a regulatory gene, PHO81, in the phosphatase regulon of Saccharomyces cerevisiae is repressed by inorganic phosphate (Pi) in the medium via that same regulatory system. The activity of Pho81p, the product of PHO81, is also inhibited by a high concentration of Pi in the medium. Increased dosage of PHO86, a gene encoding a putative membrane protein associated with a Pi transporter complex, activates the Pi-inhibited Pho81p produced under the control of the GAL1 promoter. A new gene, PHO88/ YBR106w, has now been identified as a multicopy suppressor of the rAPase- phenotype of the cells caused by the Pi inhibition of Pho81p. The pho86 disruptant expressed rAPase activity in high-Pi medium, while the pho88 disruptant did not. The delta pho86 delta pho88 double disruption resulted in enhanced synthesis of rAPase under the high-Pi condition and conferred arsenate resistance on the cells than those in single disruptants of these genes. Its hydropathy profile and the results of an analysis of its cellular localization suggested that Pho88p is a membrane protein similar to Pho86p. Both disruption and high dosage of PHO88 or PHO86 resulted in reduced Pi uptake. These findings suggest that Pho88p is also involved in Pi transport and modulates Pho81p function together with Pho86p.

Indocyanine green angiographic findings in Vogt-Koyanagi-Harada disease

PURPOSE

To report the indocyanine green angiographic findings associated with Vogt-Koyanagi-Harada disease and compare them with fluorescein angiographic findings and monochromatic scanning laser images.

METHODS

In a prospective study, indocyanine green angiography, by scanning laser ophthalmoscopy or infrared fundus photography, was performed in ten consecutive patients (20 eyes) with Vogt-Koyanagi-Harada disease during the acute stage before and recovery stage after corticosteroid treatment. Findings were compared with fluorescein angiographic features and monochromatic scanning laser imaging.

RESULTS

During the acute stage of the disease, indocyanine green angiography disclosed a dark background in the early phase and multiple, non-uniform hypofluorescent lesions in the midphases. Lesions were more numerous and extensive than areas either of serous retinal detachment on monochromatic scanning laser imaging or of punctate hyperfluorescence on fluorescein angiography. During the recovery stage, the abnormal dark background on indocyanine green angiography at initial examination resolved, with choroidal vessels visible in all cases, but nonuniform hypofluorescent lesions persisted in most eyes. Fluorescein angiography disclosed hypofluorescent patchy areas, and confocal infrared laser imaging showed some bright reflective lesions in three patients with especially severe clinical symptoms. On final examination after an average of 17.7 months, both angiographies still disclosed abnormal findings in these three patients.

CONCLUSIONS

Indocyanine green angiographic findings suggest that choroidal inflammation may cause a transient choroidal circulatory disturbance during the acute stage of Vogt-Koyanagi-Harada disease. In more severe cases, this dysfunction may secondarily damage the retinal pigment epithelium.

A putative new membrane protein, Pho86p, in the inorganic phosphate uptake system of Saccharomyces cerevisiae

The PHO84 gene in Saccharomyces cerevisiae encodes the P(i) transporter Pho84p. The other three genes, GTR1, PHO86 and PHO87, are also suggested to be involved in the P(i) uptake system. We cloned and sequenced PHO86 and found that it encodes a 34-kDa protein consisting of 311 amino acid residues with two strongly hydrophobic segments in its N-terminal half. Western blotting analysis of cell extracts revealed that Pho86p, tagged with c-Myc, was fractionated into a water-insoluble fraction. Disruption of PHO86 did not affect cell viability even in combination with the pho84 and/or pho87 disruptions. The triple disruptants showed high levels of constitutive rAPase synthesis and arsenate resistance similar to the pho84 mutant, but showed slower cell growth than the pho84 mutant. PHO86 has two putative binding sites for the transcriptional activator, Pho4p, at nucleotide positions -191 and -497 relative to the ATG start codon, and showed substantial levels of transcription under high-P(i) conditions and more enhanced levels in low-P(i) medium.

Saccharomycodes ludwigii has seven chromosomes

Tetrad distributions for 108 different gene pairs in 1346 asci of 113 diploids heterozygous for various combinations of 24 genes in Saccharomycodes ludwigii were investigated. Tetratype tetrads occurred only rarely and the 24 genes tested were classified into seven linkage groups. Electrophoretic karyotypes of three independent strains of S'codes ludwigii showed seven bands of chromosome-sized DNA having molecular sizes of 0 center dot 8 to 2 center dot 3 Mb with strain-specific polymorphic chromosomal DNAs as determined based on their migration distances.

Two new genes, PHO86 and PHO87, involved in inorganic phosphate uptake in Saccharomyces cerevisiae

The PHO84 gene in Saccharomyces cerevisiae encodes a Pi transporter, mutation of which confers constitutive synthesis of repressible acid phosphatase (rAPase), in medium containing repressible amounts of Pi, and an arsenate-resistant phenotype. We selected an arsenate-resistant mutant showing the constitutive synthesis of rAPase on nutrient plates containing 4.5 mM arsenate. This mutant has double mutations designated as pho86 and pho87. The mutant transcribes PHO84 even in the repressible condition but has a severe defect in Pi uptake. The constitutive rAPase+ phenotype of the pho86 pho87 mutant was partially suppressed by an increased dosage of the PHO84 gene. The PHO87 gene was found to be identical with YCR524, according to the published nucleotide sequence of chromosome III, which encodes a protein of 923 amino-acid residues with a highly charged N-terminal half followed by a C-terminal half consisting of 12 membrane-spanning segments as in Pho84p. These and the other findings suggest that the Pho86p and Pho87p proteins collaborate with Pho84p in Pi uptake.

Staged repair of tetralogy of Fallot and pulmonary atresia without central pulmonary arteries

A 15-year-old boy with tetralogy of Fallot and pulmonary atresia without central pulmonary arteries who was successfully treated using a staged approach is presented. The first stage consisted of the creation of central pulmonary arteries. In the second stage, the continuity between the right ventricle and the pulmonary arteries was established with closure of the ventricular septal defect. Some patients previously considered to be unsuitable candidates for correction may be successfully repaired using this approach.

Structure and distribution of specific cis-elements for transcriptional regulation of PHO84 in Saccharomyces cerevisiae

Transcription of the PHO84 gene encoding a Pi transporter in Saccharomyces cerevisiae is regulated by the Pi concentration in the medium. The promoter region of PHO84 bears five copies of the motif 5'-CACGT(G/T)-3', a candidate for the upstream activation site (UAS) that binds the transcriptional activator protein of the phosphatase regulon, Pho4p. These motifs are found at nucleotides -880 (site A), -587 (B), -436 (C), -414 (D), and -262 (E) relative to the putative ATG codon of PHO84. The Pho4p binds to all five 6-bp motifs with various affinities. Deletion analysis of the PHO84 promoter using a PHO84-lacZ fusion gene and base substitutions in the 6-bp motif revealed that two copies of the 6-bp motif, either C or D, and E, are necessary and sufficient for full regulation of the PHO84 gene. Results of expression studies with a CYC1-lacZ fusion gene with various 36-bp oligonucleotides including the 30-bp sequences around site D or E, or with modified sequences, inserted in the CYC1 promoter region indicated that the 6-bps motif flanked by a thymine nucleotide at its 5' end is much less effective as a UAS site for Pho4p in vivo than other versions. Thus, the consensus sequences for phosphatase regulation are 5'-GCACGTGGG-3' and 5'-GCACGTTTT-3' which differ from the binding sequences for the Cpflp protein required for transcription of the genes in methionine biosynthesis and for centromere function. However, Pho4p binding in vitro was unaffected by modification of the 5' or 3' flanking sites of the 6-bp motif, while modification inside the 6-bp motif affected it severely. The UAS function of the GCACGTTTT motif with respect to the Pi signal depends on its orientation in the promoter sequence.

Optimization of rice alpha-amylase production using temperature-sensitive mutants of Saccharomyces cerevisiae for the PHO regulatory system

A typical example of rational system synthesis for bioproduction by the cultivation of microorganisms harboring a recombinant plasmid was studied. First, two temperature-controllable expression systems for a foreign gene in Saccharomyces cerevisiae were constructed. The promoter of the PHO84 gene, which encodes an inorganic phosphate (Pi) transporter of S. cerevisiae and is controlled by Pi concentration through the PHO regulatory system, was used. And two temperature-sensitive mutants of S. cerevisiae for the PHO regulatory system were used as the host with rice alpha-amylase expression vector. One was temperature-sensitive pho81 mutant, SH3337, and the other was temperature-sensitive pho80 mutant, YKU107. When the strain SH3337 is cultivated at a lower temperature, the rice alpha-amylase gene connected downstream of the PHO84 promoter is expressed, but at a higher temperature, it is not. Conversely, with the strain YKU107, the transcription of the rice alpha-amylase gene is induced at a higher temperature and repressed at a lower one. The optimal cultivation temperature strategies for maximum production of rice alpha-amylase in batch cultures of these two recombinant strains were then determined by the Maximum Principle using the relationships of the specific growth and specific production rates to the cultivation temperature. The optimal strategies were easy to realize and were shown to be effective for maximum product. Finally, under these maximum alpha-amylase production strategies, the alpha-amylase activities and alpha-amylase yields in terms of glucose consumption for these recombinant strains were calculated on the basis of experimental data and compared for various operation times. The study demonstrates how a foreign gene expression system can be synthesized using a temperature-sensitive mutant with a given objective and under given constraints.

[A case of Ebstein's anomaly treated by tricuspid valve replacement]

A 8-year-old girl with Ebstein's anomaly was operated on because of progressive heart failure caused by severe tricuspid regurgitation. At the operation, the tricuspid leaflets were found to be destroyed, and the annulus was very enlarged. The enlarged true tricuspid annulus was constricted using the DeVega method, and the tricuspid valve was replaced on the true annulus using a porcine valve. To avoid injury to the auriculoventricular bundle, the suture line was shifted to the false annulus at the portion close to the course of His' bundle. Postoperative course was uneventful in satisfactory condition. The role of valve replacement in the treatment of Ebstein's anomaly of the tricuspid valve is not only to improve valve formation, but also to secure the function of the right ventricle. It is ideal to replace the tricuspid valve on the true annulus provided that the injury to the His' bundle is safely avoided.

[A diabetic patient with bilateral carotid stenosis who developed neovascular glaucoma following cataract surgery]

A 67-year-old diabetic man suffered from right neovascular glaucoma following the ipsilateral cataract surgery. Three years later, he underwent left cataract surgery and again developed left neovascular glaucoma after the operation. Fluorescein angiogram showed a marked delay in retinal circulation. Moreover, severe stenosis of bilateral carotid origins and reflux of bilateral ophthalmic arteries were ascertained by neurosonographical examination such as duplex cervical echography and transcranial Doppler, as well as an angiogram. Brain imaging demonstrated asymptomatic watershed infarction in the left parieto-occipital cortex. Chronic ocular ischemia caused by carotid stenosis is one of the decisive risk factors for secondary glaucoma after cataract surgery. Preoperative neurosonographical screening tests are required to decrease ocular surgery complications, especially in the aged, and diabetic patients.