Molecular characterization of an adenylate cyclase gene of the cyanobacterium Spirulina platensis

A cyaA gene, encoding an adenylate cyclase, was isolated from a filamentous cyanobacterium, Spirulina platensis, by functional complementation of a cya mutant of Escherichia coli, defective in adenylate cyclase activity. The predicted gene product of cyaA contains a signal peptide-like domain, a putative sensor domain similar to the gene product of vsrA of Pseudomonas solanacearum, a putative membrane-spanning domain and an adenylate cyclase-like catalytic domain. Two other positive clones that complemented the E. coli mutant were isolated from the same cyanobacterium, suggesting that several cya genes are functioning in S. platensis.

No evidence of a direct venodilatory effect of furosemide in healthy human subjects

The present study was undertaken to examine whether furosemide, a loop diuretic, has a direct venodilatory effect in healthy male subjects. Furosemide, or amrinone, an inotropic agent with a vasodilatory action, was infused into a dorsal hand vein that had been preconstricted by phenylephrine. The diameter of the vein was measured by a linear variable differential transformer. Venodilation was observed during the infusion of amrinone, but such a response was not detected with furosemide. These findings do not support the hypothesis that furosemide has a direct venodilatory effect in healthy human subjects.

[Familial cancer and oncogenic factors]

The recent remarkable progress in molecular biology has revealed that various kinds of genetic alteration occur in cancers. Recently, many genes that cause hereditary cancer have been identified. For example, hMSH2 and hMLH1, which are known as DNA mismatch repair genes have been found to cause HNPCC (hereditary non-poliposis colorectal cancer). Mutation of RET oncogene has been recognized in the families of MEN (multiple endocrine neoplasia) type II. Mutations of the tumor suppressor genes are the most common changes in the genes of familial cancer. BRCA1 and BRCA2 are tumor suppressor genes that have recently been identified as familial breast and ovarian cancer, familial breast cancer genes. This paper reviewed the hereditary cancer families in which genetic alterations have been revealed and the recent progress in mapping and cloning of familial breast cancer candidate genes which have not been identified.

Screening for bacteria producing sucrose phosphorylase and characterization of the enzymes

Two microbial strains, No. 165 and No. 168, were isolated from soil as sucrose phosphorylase producers and identified as Leuconostoc mesenteroides subsp. mesenteroides and subsp. dextranicum, respectively. The sucrose phosphorylases were purified, characterized, and compared with the enzymes of L. mesenteroides AKU1102 and ATCC12291. As for the catalytic properties, these enzymes were close to each other, while as for the enzyme molecules, the No. 165 enzyme (Mr: 58,000) was slightly different from the other (Mr: 54,000), though their N-terminal amino acid sequences were almost the same.

Cloning and expression in Escherichia coli of sucrose phosphorylase gene from Leuconostoc mesenteroides No. 165

The sucrose phosphorylase gene of an isolate, Leuconostoc mesenteroides No. 165, was amplified by PCR, cloned on pUC118, and expressed in E. coli. The nucleotide sequence of the gene showed 96.3% similarity to that of L. mesenteroides ATCC12291 and 67% to that of Streptococcus mutans, but low similarity to the Agrobacterium vitis gene. The cloned gene, which fusing with lacZalpha, was expressed inducibly with IPTG in E. coli to produce an active enzyme in large quantities that accounted for about 50% of the total cell protein.

A Y-box protein is a suppressor factor that decreases thyrotropin receptor gene expression

The decanucleotides in a tandem repeat, -162 to -140 bp, are suppressor elements that decrease TSH receptor (TSHR) gene expression by different mechanisms. A factor(s) interacting with the 3'-decanucleotide compete for proteins that bind the cAMP response element, -139 to -132 bp, a constitutive enhancer necessary for efficient TSHR expression. The 5'-decanucleotide is in a CT-rich, S1 nuclease-sensitive region of the promoter; its suppressor activity has been related to its ability to bind a nonthyroid-specific protein to its coding strand. In this report we clone a complementary DNA encoding a single strand DNA-binding protein that forms a specific protein-DNA complex with the coding strand of the 5'- but not the 3'-decanucleotide and not with the 5'-decanucleotide noncoding or double strand. We show, by cotransfection with TSHR promoter-chloramphenicol acetyltransferase chimeras, that the protein is a suppressor that regulates the function of the 5'- but not the 3'-decanucleotide. The protein is a Y-box protein that was previously cloned as an enhancer factor from the rat liver; it is, however, 95% identical to human YB-1, which suppresses major histocompatibility class II gene expression, and to human nuclease-sensitive element protein-1, a Y-box protein identified by its ability to bind single strand, CT-rich, nuclease-sensitive elements of genes that, like the TSHR, have GC-rich promoters. Unexpectedly, the Y-box protein binds two other sites in the minimal TSHR promoter in a single strand-specific fashion and acts a suppressor at each of these sites. One is associated with the insulin response element of the minimal TSHR promoter and is not in an overtly CT-rich region. The other is located 3' to the cAMP response element in a region termed the S-box, -120 to -113 bp, because of its homology to the S-box of the major histocompatibility class II promoter; this site is in a CT-rich area and, as in the class II promoter, is linked to cAMP-induced gene suppression. A conserved CCTC sequence in each site is important for the binding and suppressor function of the Y-box protein.

Malignant neoplasms in the Japanese community of Hisayama: mortality and changing pattern during a 30-year observation period based on a consecutive autopsy series

To obtain a relatively true mortality from malignant neoplasms, we studied the frequency of cancers in the different sites and the changing patterns of the frequency and sites over time among residents of the community of Hisayama, where an autopsy-based population survey (autopsy rate, 80%) has been conducted since 191. During the 30-year period from 1962 to 1991, we found 438 malignant neoplasms in 407 cases among 1,250 consecutive autopsies. Stomach cancer was not frequent in type of cancer, with 123 cases (9.8%), followed by lung cancer in 62 (5.0%), colorectal cancer in 42 (3.4%), liver cancer in 37 (3.0%), and pancreatic cancer in 30 (2.4%). We compared the mortality from cancers for both autopsy and nonautopsy cases (the proportional mortality) among three 10-year periods. The proportional mortality from all cancers, as well as for lung, colorectal, and liver cancers, showed an increase in recent years, while stomach and pancreatic cancer showed a decrease. These figures were nearly similar to the mortality statistics for the Japanese population as a whole except for the observed decreasing trend in mortality from pancreatic cancer.

Environmental magnetic fields change complementary DNA synthesis in cell-free systems

A number of studies have shown that exposures to environmental magnetic fields (MFs) increase cellular transcription and enhance DNA synthesis. However, little is known about the basic mechanisms underlying specific biological responses to MFs. We looked directly at the effect of MFs by using a cell-free rabbit globin cDNA synthesis system. cDNA synthesis reaction mixtures were placed in each of four exposure conditions and were tested simultaneously. Condition one was the control, with no exposure during either single-strand or double-strand synthesis (M-M-). The second condition was MF exposure only during single-strand synthesis (M+M-). The third condition was exposure only during double-strand synthesis (M-M+). The fourth condition was exposure during both single-strand and double-strand synthesis (M+M+). Results showed that cDNA synthesis was affected by 5-100 microT, 60 Hz MFs. Double-strand cDNA synthesis increased with MF exposure only during double-strand synthesis reactions (M-M+), and the greatest increase of double-strand cDNA synthesis was detected when MF exposure was at 10 microT, only during double-strand synthesis. Double-strand cDNA synthesis decreased when only single-strand synthesis reactions were exposed (M+M-; 100 microT). An increase of cDNA synthesis caused increased synthesis of rabbit globin cDNA and large-sized molecules. These results suggest that exposure to MF induced structural changes of synthesized cDNA, therefore altering the amount of cDNA. Our results show that environmental MFs can significantly alter cDNA synthesis in a cell-free system.

Flow cytometric analysis of the DNA content in colorectal adenomas with focal cancers

BACKGROUND & AIMS

Variable results have been reported on the nuclear DNA content of colorectal polyps. The significance of DNA aneuploidy in the malignant transformation of colorectal polyps was evaluated.

METHODS

We analyzed by flow cytometry the nuclear DNA content of freshly frozen samples of 50 colorectal adenomas with or without focal cancers, analyzing separately the adenomatous and cancerous regions of the polyps.

RESULTS

In the adenomatous regions of the 50 polyps, the DNA was diploid in 43 and aneuploid in 7; the adenomas with DNA aneuploidy in the adenomatous regions were more frequently accompanied by focal cancers than were the DNA-diploid adenomas (P < 0.01). In 60% of the polyps with DNA aneuploidy in the cancerous regions, the DNA was also aneuploid in the adenomatous region and had similar DNA indices; this result suggests that the DNA aneuploidy had already occurred during the adenomatous stage, which lends support to the concept of the adenoma-carcinoma sequence. DNA aneuploidy in the adenomatous region was significantly correlated with the size of colorectal polyps (P < 0.05).

CONCLUSIONS

DNA aneuploidy may be an important indicator for the early diagnosis of malignant transformation of colorectal polyps.

Molecular cloning of the cyanobacterial adenylate cyclase gene from the filamentous cyanobacterium Anabaena cylindrica

Molecular cloning of the structural gene for adenylate cyclase (cya) of the cyanobacterium Anabaena cylindrica was carried out by complementation of an Escherichia coli strain defective in the cya gene. The cya-defective strain produced significant amounts of cyclic AMP when it was transformed with the cya gene isolated from A. cylindrica. This gene encodes a polypeptide consisting of 502 amino acid residues (molecular weight, 55,300). The deduced primary protein structure showed that the carboxyl-terminal region of the adenylate cyclase of A. cylindrica shows strong structural similarity to the conserved regions of the adenylate cyclases of various eukaryotes. No similarity was found between the amino acid sequences of the cya gene of A. cylindrica and that of E. coli. A hydropathy plot suggests that this protein has two hydrophobic regions, a transmembrane span and a signal peptide. An antiserum specific to this adenylate cyclase was prepared by immunizing a rabbit with a glutathione S-transferase-adenylate cyclase fusion protein expressed in E. coli. This antiserum recognized a 55-kDa protein in Anabaena cell lysates. Subcellular fractionation analysis showed that A. cylindrica adenylate cyclase localized in the thylakoid membrane.

Single strand DNA-binding proteins and thyroid transcription factor-1 conjointly regulate thyrotropin receptor gene expression

An element, -186 to -176 base pairs (bp), in the minimal TSH receptor (TSHR) promoter binds thyroid transcription factor-1 (TTF-1) and is important for both constitutive expression and TSH/cAMP-induced negative autoregulation of the TSHR in thyroid cells. An element on the noncoding strand of the TSHR, contiguous with the 5'-end of the TTF-1 element, has single strand binding activity. It is distinct from the TTF-1 site, as evidenced by competition experiments using gel shift assays; but the association of the two elements is not random. Thus, the single strand binding protein (SSBP) element also exists contiguous to the 5'-end of an upstream TTF-1 site, -881 to -866 bp; mutation of two conserved nucleotides in each SSBP element results in the loss of SSBP binding and cross-competition. Transfection experiments indicate that full, constitutive TSHR gene expression in FRTL-5 thyroid cells requires the binding of both SSBPs and TTF-1, since mutation of either element halves thyroid-specific promoter activity, whereas mutation of both decreases promoter activity to values near those of a control vector. Transfection experiments with rat liver cells support their independent activities and show that the SSBP site contributes to TSHR gene expression in non-thyroid tissue. The SSBPs function conjointly with TTF-1 in thyroid-specific, TSH/cAMP-induced negative autoregulation of the TSHR. Thus, TSH or forskolin-treated FRTL-5 cells coordinately decrease TSHR RNA levels and TSHR DNA binding to both the SSBPs and TTF-1; also the maximal TSH/cAMP-induced decrease in gene expression requires both elements. The TSH-induced effect in each case is inhibited by cycloheximide; the TSH-induced decrease in SSBP/DNA complex formation requires the presence of insulin or calf serum, exactly as does TSH-induced down-regulation of TSHR RNA levels. In sum, full, constitutive expression of the TSHR in thyroid cells requires TTF-1 and the SSBPs to bind separate, contiguous elements on the TSHR promoter. TSH/cAMP decreases the binding of each factor to its respective site, thereby decreasing TSHR gene expression. The role of the SSBP and TTF-1 sites in constitutive TSHR expression and in TSH/cAMP-induced negative regulation of the TSHR is, therefore, additive and independent.

[Noninvasive recording of pre-P wave related to sinus node electrical activity using P wave-triggered signal-averaging technique]

To determine whether the sinus node electrogram (SNE) could be detected noninvasively, a specially modified P wave-triggered signal-averaged electrocardiogram was recorded through the standard V1, V2 and V3 precordial leads in 39 patients. The data between 500 ms before and 300 ms after the trigger point were processed using a digital bandpass filter of 0.5 Hz (12 dB/oct)-20 Hz (18 dB/oct). Pre-P signals were observed just before the P wave resembling SNE recorded directly. Pre-P potential duration closely correlated with direct SACT (r = 0.856, P < 0.0005). Thus, it is believed that signals obtained by this new method would be related to sinus electrical activity and that it could be useful for noninvasive estimation of SACT.

Characterization of an up-stream thyroid transcription factor-1-binding site in the thyrotropin receptor promoter

A thyroid transcription factor-1 (TTF-1)-binding element in the rat TSH receptor (TSHR) promoter, between -189 and -175 basepairs (bp), is important for both thyroid-specific expression and thyroid-specific TSH/cAMP autoregulation of the TSHR. The identification of an up-stream TTF-1-binding site and its relationship to the function of the down-stream TTF-1 element are the subjects of this report. Sequence analysis identifies a potential TTF-1 site at -878 bp; deoxyribonuclease-I footprinting shows that the -881 to -866 bp region is protected by recombinant TTF-1 protein and by nuclear extracts from FRTL-5 thyroid cells that contain TTF-1, but not by extracts from nonfunctioning FRT thyroid or Buffalo rat liver (BRL) cells, which have no TTF-1, or by Pax-8. FRTL-5, but not FRT or BRL cell nuclear extracts, form a specific protein-DNA complex with this region in gel mobility shift analyses; its formation is prevented by TTF-1-binding elements from the thyroglobulin promoter. The upstream TTF-1 site acts as an enhancer when coupled to a heterologous simian virus-40 promoter-chloramphenicol acetyltransferase (CAT) chimera and transfected into FRTL-5 thyroid cells. There is a greater increase, 3-vs. 2-fold (P < 0.05), when TSHR promoter-CAT chimeras, which contain the up-stream TTF-1 element, pTRCAT5'-907 or pTRCAT5'-886, as opposed to those in which it is deleted, pTRCAT5'-907 delta USTTF-1, are transfected into FRTL-5 cells or cotransfected with a TTF-1 expression vector into BRL cells, which have no endogenous TTF-1. The TTF-1-dependent activity of pTRCAT5'-907 delta USTTF-1 is the same as that of the minimal promoter, -220 to -39 bp, containing only the down-stream TTF-1 site in both cells. Transfection of chimeric TSHR-CAT plasmids with the down- and/or up-stream TTF-1 site deleted reveals that the down-stream TTF-1 element functions in the absence of the up-stream element, but function of the up-stream site requires the down-stream TTF-1 element. Like the down-stream TSHR TTF-1-binding site, the up-stream TTF-1 site is different from TTF-1 sites in the thyroglobulin and thyroid peroxidase promoter, in that it does not interact with Pax-8.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytology and immunohistochemistry of anaplastic meningiomas in squash preparations. A report of two cases

Cytodiagnosis is a useful adjunct to frozen section diagnosis of brain tumors during surgery and has been applied in many pathology laboratories. Although anaplastic (malignant) meningiomas are not extremely rare tumors, their cytologic features have not been well described. Cytologic details of anaplastic meningioma, papillary meningioma with a fibroblastic component and anaplastic angiomatous meningioma are presented. Papillary meningioma showed atypical cell clusters having a close relation to mature endothelial cells and that corresponded to papillary proliferation. Other cell clusters of this tumor showed an ordinary fibroblastic pattern with coarse cytoplasmic filaments and necrotic changes in the cytoplasm. Anaplastic angiomatous meningioma exhibited loose cell clusters. Some of them had coarse cytoplasmic filaments, and others were similar to epithelial cells in origin. Specific features commonly found in anaplastic meningioma were hyperchromatic and pleomorphic nuclei and cytoplasmic filaments more obscure than those of the benign counterpart. Immunocytochemically the tumor cells in the papillary area of papillary meningioma had a positive reaction to antiserum of vimentin, cytokeratin and S-100 protein. The tumor cells of anaplastic plastic angiomatous meningioma showed intracytoplasmic positivity to antivimentin and anti-epithelial membrane antigen serum.

Lesser sac herniation through the greater omentum and gastro-pancreatic ligament: report of a case

We report herein the case of a woman who developed a lesser sac hernia which was especially unusual in that the small bowel prolapsed through a defect in the greater omentum and was thereafter strangulated by a hole in the gastro-pancreatic ligament. The gastro-pancreatic ligament has never before been documented as causing an internal hernia. In our patient, a plain abdominal X-ray demonstrated as soft-tissue mass displacing the stomach to the left while abdominal computed tomography and ultrasonography showed a sac-like encapsulation of the small bowel loops between the liver and stomach. Careful evaluation of these radiographic findings allowed for the preoperative diagnosis of a lesser sac hernia to be made.

[The estimates of the future trend of tuberculosis incidence and the control programs for its elimination]

In most European and other industrialized countries, it is estimated that tuberculosis would be eliminated around 2030, and in the U.S. and Western European countries, new tuberculosis strategies were developed to eliminate tuberculosis. The Ministry of Health and Welfare (MOHW) in Japan too, has also introduced some new tuberculosis control plans and goals. In Japan, it is estimated that the elimination of tuberculosis would be achieved around 2060, and MOHW has set the final goal for the elimination of tuberculosis by the year 2030. MOHW has also set two interim goals by the year 2000, i.e., (1) to achieve the tuberculosis incidence of below 20 per 100,000 population, (2) to achieve the tuberculosis incidence in children to the level of elimination, that is below 0.1 per 100,000. Wishing the success of these plans, the author tried to examine the possibility of achieving the goals by 2000. The decline of tuberculosis incidence rate in Japan has been gradually slower since 1977. However, the declining trend has become almost constant since around 1983, although it is still very slowly decreasing. Therefore, assuming that the future incidence rates will continue at the same decreasing speed as that of average annual decline rate during the last 10-year period from 1983 to 1992, the incidence rate in Japan in 2000 would be estimated to become 30.9 per 100,000 (95% C.I.; 29.8-31.7), and the incidence rate in children would be 0.87 per 100,000 (95% C.I.; 0.71-1.05). Examining the possibility of acceleration of the declining speed of tuberculosis incidence, it was discussed that there could be a possibility of removing such cases as the preventable cases, non-tuberculosis and inactive tuberculosis cases from newly registered cases in advance.(ABSTRACT TRUNCATED AT 250 WORDS)

The thyrotropin receptor

This chapter has outlined the complex process required for thyroid growth and function. Both events are regulated by TSHR via a multiplicity of signals, with the aid of and requirement for a multiplicity of hormones that regulate the TSHR via receptor cross-talk: insulin, IGF-I, adrenergic receptors, and purinergic receptors. Cross-talk appears to regulate G-protein interactions or activities induced by TSH as well as TSHR gene expression. The TSHR structure and its mechanism of signal transduction is being rapidly unraveled in several laboratories, since the recent cloning of the receptor. In addition, the epitopes for autoantibodies against the receptor that can subvert the normal regulated synthesis and secretion of thyroid hormones, causing hyper- or hypofunction, have been defined. Studies of regulation of the TSHR minimal promotor have uncovered a better understanding of the mechanisms by which TSH regulates both growth and function of the thyroid cell. A key novel component of this phenomenon involves TSH AMP positive and negative regulation of the TSHR. Negative transcriptional regulation is a common feature of MHC class I genes in the thyroid. Subversion of negative regulation or too little negative regulation is suggested to result in autoimmune disease. Methimazole and iodide at autoregulatory levels may be important in reversing this process and returning thyroid function to normal. Their action appears to involve factors that react with the IREs on both the TSHR and the TG promoter. Too much negative regulation, as in the case of ras transformation, results in abnormal growth without function. TTF-1 is implicated as a critical autoregulatory component in both positive and negative regulation of the TSHR and appears to be the link between TSH, the TSHR, TSHR-mediated signals, TG and TPO biosynthesis, and thyroid hormone formation. Differentially regulated expression of the TSHR and TG by cAMP and insulin depend on differences in the specificity of the TTF-1 site, that is, the lack of Pax-8 interactions with the TSHR, and the IRE sites. Single-strand binding proteins will become important in determining how TSHR transcription is controlled mechanistically.

Identification of a novel insulin-responsive element in the rat thyrotropin receptor promoter

By transfecting TSH receptor (TSHR)-chloramphenicol acetyltransferase (CAT) chimeras into FRTL-5 thyroid cells in the presence or absence of insulin, we identify an insulin-responsive element (IRE) between -220 and -190 bp of the TSHR 5'-flanking region. The region between -220 and -192 bp is footprinted by nuclear extracts from FRTL-5 cells and, coupled to a heterologous SV40-CAT chimera, an oligonucleotide containing the protected region induces insulin responsiveness in FRTL-5 cells. FRTL-5 cell nuclear extracts form two groups of protein-DNA complexes, A and B, in gel shift assays using an oligonucleotide having the protected sequence; mutation data indicate only the A complexes are increased by exposure of FRTL-5 cells to insulin; TSH can also increase A complex formation, but the TSH action is insulin-dependent. The nuclear factor(s) in FRTL-5 cells that interact with the TSHR IRE are distinct from thyroid transcription factor-2 (TTF-2), the insulin regulatory factor of the thyroglobulin promoter, as evidenced by the absence of competition in gel shift assays; there is no apparent sequence similarity of this region with other known IREs. The IRE is immediately upstream of a thyroid transcription factor-1 (TTF-1) binding site, -189 to -175 bp; mutation of the TTF-1 site causing a loss of TTF-1 activity also causes a loss of insulin responsiveness when the TSHR-CAT chimera at -220 bp is transfected into FRTL-5 cells and an altered IRE footprint by nuclear extracts. The TSHR appears, therefore, to contain a novel IRE whose activity depends at least in part on TTF-1, a thyroid-specific, homeodomain-containing transcription factor important both for thyroid-specific TSHR gene expression and TSH/cAMP autoregulation of the TSHR.

Three cases of extrapulmonary small cell carcinoma occurring in the prostate, stomach, and pancreas

Small cell carcinomas are fairly common neoplasms in the lung, but tumors featuring similar histological profiles may occur in extrapulmonary organs. Three cases of small cell carcinomas occurring in the prostate (case 1), stomach (case 2), and pancreas (case 3) are presented. Production of hormones was demonstrated immunohistochemically in all cases. In case 2 alpha-fetoprotein (AFP) was elevated in the serum and observed immunohistochemically in tumor cells. Production of AFP is a distinctive feature, which has not been reported in the pulmonary and extrapulmonary cases of small cell carcinoma. Amplification and/or expression of myc gene family have been suggested to be related to the prognosis of pulmonary small cell carcinoma. Amplification of myc genes was not detected in any of our cases, but c-myc protein was demonstrated immunohistochemically in tumor cells of case 1.

Comparison of the binding of beta-cyclodextrin and alpha- and gamma-cyclodextrins with pullulanase from Klebsiella pneumoniae as studied by equilibrium and kinetic fluorometry

The change in fluorescence spectra of crystalline pullulanase from Klebsiella pneumoniae caused by the addition of alpha-, beta-, and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin was investigated at 25 degrees C and pH 5.6. The fluorescence intensity at around 325 nm (excitation at 280 nm) was increased by the addition of all the cyclodextrins studied. The dissociation constant, Kd, of the enzyme-cyclodextrin complex was evaluated by fluorometric titration for each cyclodextrin, and was consistent with the inhibitor constant, Ki, obtained previously [Iwamoto et al. (1993) J. Biochem. 113, 93-96]. The Kd values of beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin were approximately two orders of magnitude smaller than those of alpha- and gamma-cyclodextrins. Fluorescence titration of a cyclodextrin in the presence of another cyclodextrin revealed competition among alpha-, beta-, and gamma-cyclodextrins for binding with the enzyme, which indicates that the binding region of beta-cyclodextrin overlaps those of alpha- and gamma-cyclodextrins. On the other hand, with excitation at 295 nm, a fluorescence spectral change similar to that excited at 280 nm was observed for alpha- and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin, whereas beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin did not show any such change. These results suggest that the binding site or the binding mode of beta-cyclodextrin is slightly different from those of alpha- and gamma-cyclodextrins.(ABSTRACT TRUNCATED AT 250 WORDS)

delta 9 Acyl-lipid desaturases of cyanobacteria. Molecular cloning and substrate specificities in terms of fatty acids, sn-positions, and polar head groups

In cyanobacteria, the biosynthesis of unsaturated fatty acids is initiated by delta 9 acyl-lipid desaturase which introduces the first double bond at the delta 9 position of a saturated fatty acid that has been esterified to a glycerolipid. We have cloned genes, designated desC, for delta 9 acyl-lipid desaturases from two cyanobacteria, namely Anabaena variabilis and Synechocystis sp. PCC 6803. These desaturases, when expressed in Escherichia coli, desaturated stearic acid to yield oleic acid at the C-1 positions of phosphatidylethanolamine and phosphatidylglycerol, but did not desaturate palmitic acid, palmitoleic acid, and cis-vaccenic acid. These results indicate that the delta 9 acyl-lipid desaturases are specific to stearic acid esterified at the C-1 position of a glycerolipid and are nonspecific with respect to the polar head group of the glycerolipid. The deduced amino acid sequences of the delta 9 acyl-lipid desaturases are similar in part to those of stearoyl-CoA desaturases of the rat, the mouse, and Saccharomyces cerevisiae, but not to those of acyl-(acyl-carrier-protein) desaturases of higher plants.

Cloning of omega 3 desaturase from cyanobacteria and its use in altering the degree of membrane-lipid unsaturation

Cyanobacteria respond to a decrease in temperature by desaturating fatty acids of membrane lipids to compensate for the decrease in membrane fluidity. Among various desaturation reactions in cyanobacteria, the desaturation of the omega 3 position of fatty acids is the most sensitive to the change in temperature. In the present study, we isolated a gene, designated desB, for the omega 3 desaturase from the cyanobacterium, Synechocystis sp. PCC 6803. The desB gene encodes a protein a 359 amino-acid residues with molecular mass of 41.9 kDa. The desB gene is transcribed as a monocistronic operon that produced a single transcript of 1.4 kb. The level of the desB transcript in cells grown at 22 degrees C was 10 times higher than that in cells grown at 34 degrees C. In order to manipulate the fatty-acid unsaturation of membrane lipids, the desB gene in Synechocystis sp. PCC 6803 was mutated by insertion of a kanamycin-resistance gene cartridge. The resultant mutant was unable to desaturate fatty acids at the omega 3 position. The desA gene, which encodes the delta 12 desaturase of Synechocystis sp. PCC 6803, and the desB gene were introduced into Synechococcus sp. PCC 7942. Whilst the parent cyanobacterium can only desaturate membrane lipids at the delta 9 position of fatty acids, the resultant transformant was able to desaturate fatty acids of membrane lipids at the delta 9, delta 12 and omega 3 positions. These results confirm the function of the desB gene and demonstrate that it is possible to genetically manipulate the fatty-acid unsaturation of membrane lipids in cyanobacteria.

Giant symptomatic myelolipoma of the adrenal gland

A case of giant symptomatic myelolipoma is described in which clinical differentiation was difficult. It was considered to be an extremely rare case of giant myelolipoma arising in the adrenal gland. Histologically the present case contained more lipomatous elements than others reported to data. This is a case of giant adrenal myelolipoma with a few foci of myeloid elements and it is suggested that this case has a true neoplastic nature rather than a hyperplastic or metaplastic one.