Gene targeting: things go better with Cre

New technologies are changing the way in which gene targeting experiments are being designed. It is now becoming possible to analyze gene function in defined tissues at specific times during the life of a mouse.

The Snf1 protein kinase and its activating subunit, Snf4, interact with distinct domains of the Sip1/Sip2/Gal83 component in the kinase complex

The Snf1 protein kinase plays a central role in the response to glucose starvation in the yeast Saccharomyces cerevisiae. Previously, we showed that two-hybrid interaction between Snf1 and its activating subunit, Snf4, is inhibited by high levels of glucose. These findings, together with biochemical evidence that Snf1 and Snf4 remain associated in cells grown in glucose, suggested that another protein (or proteins) anchors Snf1 and Snf4 into a complex. Here, we examine the possibility that a family of proteins, comprising Sip1, Sip2, and Gal83, serves this purpose. We first show that the fraction of cellular Snf4 protein that is complexed with Snf1 is reduced in a sip1delta sip2delta gal83delta triple mutant. We then present evidence that Sip1, Sip2, and Gal83 each interact independently with both Snf1 and Snf4 via distinct domains. A conserved internal region binds to the Snf1 regulatory domain, and the conserved C-terminal ASC domain binds to Snf4. Interactions were mapped by using the two-hybrid system and were confirmed by in vitro binding studies. These findings indicate that the Sip1/Sip2/Gal83 family anchors Snf1 and Snf4 into a complex. Finally, the interaction of the yeast Sip2 protein with a plant Snf1 homolog suggests that this function is conserved in plants.

[Hemorheological disorders in patients with sudden deafness]

Fourteen hemorheological and related parameters of blood samples derived from 59 patients with sudden deafness were observed and were compared with those of blood samples got from 512 healthy persons. The ratio viscosity of whole blood (6.50 +/- 1.07), reduced viscosity of whole blood (12.37 +/- 1.80), and plasma viscosity (1.84 +/- 0.14) in male patients were significantly higher than those (6.05 +/- 0.63, 11.06 +/- 1.04, and 1.70 +/- 0.07, respectively) in male controls. The reduced viscosity of whole blood (16.62 +/- 3.87) and plasma viscosity (1.92 +/- 0.13) in female patients were also significantly higher than those (14.40 +/- 2.27 and 1.72 +/- 0.06, respectively) in female controls. The findings above suggest that there is an intimate relationship between the microcirculationary disorder resulting from hemorheological changes and the onset of sudden deafness. The parameters related to plasma viscosity revealed that there were higher concentrations of plasma fibrinogen and triglyceride in male patients than those in male controls, while the concentrations of plasma cholesterol and triglyceride were higher in female patients than in female controls. These results indicate that the factors which induce the change of plasma viscosity in male patients could not be the same as those in female patients. Thus, in the process of treating sudden deafness, besides the use of common devices such as reducing blood viscosity and improving microcirculation, some other special steps based on the hemorheological parameters derived from different sexes or individuals, should also be considered.

Glucose regulates protein interactions within the yeast SNF1 protein kinase complex

The SNF1 protein kinase is broadly conserved in eukaryotes and has been implicated in responses to environmental and nutritional stress. In yeast, the SNF1 kinase has a central role in the response to glucose starvation. SNF1 is associated with its activating subunit, SNF4, and other proteins in complexes. Using the two-hybrid system, we show that interaction between SNF1 and SNF4 is strongly regulated by the glucose signal. Moreover, this interaction is appropriately affected by mutations in regulators, including protein phosphatase 1. We show that SNF4 binds to the SNF1 regulatory domain in low glucose, whereas in high glucose the regulatory domain binds to the kinase domain of SNF1 itself. Genetic analysis further suggests that the SNF1 regulatory domain autoinhibits the kinase activity and that in low glucose SNF4 antagonizes this inhibition. Finally, these interactions have been conserved from yeast to plants, indicating that homologs of the SNF1 kinase complex respond to regulatory signals by analogous mechanisms.

Characterisation of acidic heteroglycans from Tremella fuciformis Berk with cytokine stimulating activity

Four kinds of acidic heteroglycan, T3a-T3d, were isolated from the body of the fungus Tremella fuciformis Berk. The molecular weights of T3a-T3d were 550, 420, 55, and 48 kDa, respectively. Glycosidic linkage analysis showed that they had a mannan backbone consisting of 3-linked Man p, and side chains containing glucosyl, mannosyl, fucosyl, xylosyl, and glucuronic acid residues attached through O-2, O-4, or O-6 of about half of the backbone mannosyl residues. A partial acidic hydrolysate of T3a could be divided into a low-branching region (T3a-1, 2, 3, 4) mainly branched at the 2-position of 3-linked Man p in the mannan backbone, and a high-branching region (T3a-5A) branched at the 2,4- or 2,4,6-positions of 3-linked Man p in the backbone. The low-branching region, which is predominant in the backbone, was substituted with non-reducing terminal Glc pA, Fuc p and short side chains consisting of (1-->6)-linked Glc p and (1-->2)-linked Man p linked through C-2 of the mannan backbone. The high-branching region, which is a minor component of the backbone, was linked with long side chains of (1-->6)-linked Glc p and (1-->4)-linked Glc pA in their branching points. T3a-T3d were able to induce human monocytes to produce interleukin-1, interleukin-6, and tumor necrosis factor in vitro. The different fragments of the acidic hydrolysate of T3a (T3a-1, 2, 3, 4, 5A) also induced monocytes to secret interleukin-6 with high potency, indicating that the activity may be caused by a common structure, (1-->3)-mannan in the four heteroglycans and their fragments. The change of molecular weight had no obvious influence on the activity of the heteroglycans.

Supplementation with L-2-oxothiazolidine-4-carboxylic acid, a cysteine precursor, does not protect against lipid peroxidation in puromycin aminonucleoside-induced nephropathy

Lipid peroxidation in the kidney has been shown to precede proteinuria in puromycin aminonucleoside (PAN)-induced nephropathy. The aim of this study was to determine if L-2-oxothiazolidine-4-carboxylic acid (procysteine) would protect rats against PAN-induced nephrotoxicity. Male Sprague-Dawley rats were treated with procysteine (16 mg/100 g body weight i.p.) 24 h and 30 min prior to receiving a single injection of PAN (15 mg/100 g body weight i.v.) followed by procysteine in the drinking water (4 g/l). Control rats received procysteine alone (intraperitoneally and in drinking water) or PAN alone and then plain water. Proteinuria was not significantly different between PAN/ procysteine and PAN groups, reaching a maximum at day 14 and persisting at day 28. Lipid peroxidation was more severe in PAN/procysteine rats reaching a maximum at day 3 (253 +/- 30 ng/mg protein) compared to day 5 in PAN rats (196 +/- 20 ng/mg protein). Procysteine alone did not modulate proteinuria over 28 days or lipid peroxidation over 7 days. GSH levels over 7 days were not elevated by procysteine and were virtually zero in PAN and PAN/procysteine rats. Focal glomerulosclerosis (FGS) was worse at day 28 in PAN/procysteine rats than in PAN rats (39 +/- 8.2 vs. 23 +/- 4.5%; p < 0.05). This study shows that procysteine as a potential source of reducing equivalents does not protect against renal lipid peroxidation and FGS in this model. On the contrary, PAN/procysteine rats developed significantly more FGS through yet unknown mechanisms.

High-performance liquid chromatographic assay for common sunscreening agents in cosmetic products, bovine serum albumin solution and human plasma

This paper reports the development of a reversed-phase high-performance liquid chromatographic assay for quantifying five of the most common sunscreen agents, namely 2-ethylhexyl-p-dimethyl aminobenzoate (Escalol 507), 2-ethylhexyl-p-methoxycinnamate (Parsol MCX); 4-tert.-butyl-4'-methoxydibenzoylmethane (Parsol 1789), 2-hydroxy-4-methoxybenzophenone-3 (oxybenzone) and 2-ethylhexyl-salicylate (octylsalicylate). The assay permits analysis of the sunscreen agents in formulations and in biological fluids, including bovine serum albumin (BSA) solution, a common additive to in vitro skin diffusion cell receptor fluids, as well as human plasma. Separation was achieved using an ODS C154 column with a methanol-water (88:12) mobile phase. The analytes were detected by ultraviolet light absorption at a wavelength of 315 nm. The assay was linear with minimum detectable limits, calculated as greater than 3-times the baseline noise level: for oxybenzone and Escalol 507, 0.05 microgram/ml; for Parsol 1789 and Parsol MCX, 0.1 microgram/ml; for octylsalicylate, 1 microgram/ml. Recoveries from both plasma and 2% BSA were within the range 89-107%. The inter- and intra-day coefficients of variation for the five agents were not more than 4% at the upper end of the linear range and not more than 10% at the lower end. Preliminary stability studies of the sunscreen agents in a commercial product and in two diffusion cell receptor fluids were also conducted.

The limiting mobility of DNA sequencing fragments for both cross-linked and noncross-linked polymers in capillary electrophoresis: DNA sequencing at 1200 V cm-1

The mobility of DNA sequencing fragments was measured in Long-Ranger gels at an electric field ranging from 200 to 1200 V cm-1 and in noncross-linked polyacrylamide at electric fields ranging from 100 to 300 V cm-1. In both cases, N*, the fragment length that denotes the onset of biased reptation with orientation, is inversely proportional to electric field. The inverse dependence of N* is inconsistent with the original biased reptation model but is consistent with modern models of DNA migration. While separation speed increases dramatically with electric field, the number of bases determined in a separation decreases in proportion to field strength. We present a DNA sequencing run at an electric field of 1200 V cm-1. Roughly 200 bases of sequence are determined in 3.5 min.

Non-stochastic utilization of Ig V region genes in unselected human peripheral B cells

Limited evidence based on a few subjects suggests that human peripheral blood B cells may express a non-stochastic assortment of V region genes. To determine if non-stochastic utilization was a generally applicable rule, the identities of rearranged V region gene segments were determined in unselected peripheral blood B cells from 12 subjects (five male, seven female), ranging in age from 35 to 72 years. The analysis was limited to V region genes belonging to the VH3 gene family. More than 4500 independent VH3-containing rearrangements were analysed. The frequency of occurrence of eight individual VH3 gene segments contained in rearrangements was assessed using gene specific oligonucleotide probes. Usage of elements was not uniform. Three elements, which have been known to encode autoantibodies as well as to be frequently rearranged during fetal development, were represented among rearrangements more frequently than were other members of the VH3 family, and in aggregate, accounted for the majority of rearrangements. These three predominant loci are clustered in an 80 kb region suggesting an influence of chromosomal location on efficiency of rearrangement. The results document a clear, statistically significant, preference for the occurrence of specific V region genes among rearrangements. The modest amount of variation observed between subjects was not associated with either age or gender. Duplications which increased gene dose may have contributed to increased gene usage. These data indicate that, in caucasians, the immunoglobulin rearrangements in adult human B cells are dominated by a few heavy chain V region genes to the exclusion of other putatively equally functional genes. Thus, the conventional notion that the adult repertoire is normalized with respect to family complexity is not confirmed by analysis of individual VH genes.

Use of non-cross-linked polyacrylamide for four-color DNA sequencing by capillary electrophoresis separation of fragments up to 640 bases in length in two hours

Four-color DNA cycle sequencing was performed on an M13mp18 template using dye-labeled primers. Sequencing fragments were separated by capillary electrophoresis at 60 degrees C and at an electric field of 150 V/cm. The sieving medium was 5%T, non-cross-linked polyacrylamide in 7 M urea. The use of high temperature for the separation reduces formation of secondary structures in the sequencing fragments, generating a sequence that is free of compressions without the use of strongly denaturing gels. The use of high temperatures also increases the separation rate compared with room-temperature operation. Fragments up to 640 bases are separated in less than 2 h.

Expression of syndecan-1 changes during the differentiation of visceral and parietal endoderm from murine F9 teratocarcinoma cells

F9 teratocarcinoma stem cells treated with retinoic acid differentiate in suspension into embryoid bodies with an outer layer of visceral endoderm surrounding a core of largely undifferentiated cells. The visceral endoderm-containing embryoid bodies, when plated onto an extracellular matrix coating, give rise to parietal endoderm outgrowth. These in vitro cell cultures mimic both geometrically and biochemically the differentiation of visceral and parietal endoderm in the early mouse embryo and, thus, were used as a model system for the study of molecular and cellular mechanisms underlying the differentiation of the extraembryonic endoderm lineages. We have investigated the expression of syndecan-1, an integral membrane proteoglycan that binds to multiple components of the extracellular matrix and basic FGF, during visceral endoderm differentiation and parietal endoderm outgrowth. Syndecan-1 immunostaining is detected on all cell surfaces in the undifferentiated embryoid bodies and in the differentiating embryoid bodies prior to the formation of the visceral endoderm. Following the differentiation of visceral endoderm, syndecan-1 localizes predominantly to the basal surface of this epithelial layer, while syndecan-1 staining in the core of differentiated embryoid bodies is faint. Quantitation of cell associated syndecan-1 indicates that syndecan-1 is down-regulated during embryoid body differentiation. However, northern analysis shows that the amounts of steady-state syndecan-1 mRNA are the same in undifferentiated versus differentiated embryoid bodies, suggesting post-transcriptional regulation of syndecan-1 expression in the differentiating embryoid body. Analysis of syndecan-1 distribution in the outgrowth culture by immunofluorescence demonstrates that syndecan-1 is absent from the cell surface of parietal endoderm. However, a substantial amount of syndecan-1 is detected inside parietal endoderm cells. While all three cell types release syndecan-1 ectodomain into the culture medium, the parietal endoderm outgrowth releases more syndecan-1 ectodomain than the differentiated embryoid body. These data suggest that the post-transcriptional control and post-translational shedding of syndecan-1 from the cell surface are developmentally regulated during the differentiation of visceral to parietal endoderm and the migration of parietal endoderm.

Loss of allosteric behaviour in recombinant hemoglobin alpha 2 beta 2(92)(F8) His-->Ala: restoration upon addition of strong effectors

In the stereochemical model proposed by Perutz [1], the Fe-His(F8) bond plays a significant role in the allosteric transition in hemoglobin and the resulting cooperativity in ligand binding. When this bond is ruptured, there is a loss in the transmission of the information concerning ligand binding; examples are Hb(NO)4 in the presence of inositol hexakisphosphate (IHP), or nickel substituted Hb hybrids which, despite being liganded, exhibit deoxy-like properties. To study the effects of the loss of the iron proximal histidine bond, we have engineered the alpha 2 beta 2(F8)H92A recombinant Hb. The replacement of the highly conserved proximal histidine F8 residue by an alanine results in a low affinity for the heme group and a loss of the allosteric properties; kinetics of CO recombination after photodissociation show only the rapid bimolecular phase, characteristic of the high affinity R-state. However, a significant amount of deoxy (T-state) kinetics are observed after addition of external effectors such as IHP. The iron-histidine bond is apparently crucial for the heme-heme interaction, but the allosteric equilibrium may still be influenced by external constraints.

Stability of hydrocortisone oral suspensions prepared from tablets and powder

OBJECTIVE

To assess the stability, dosage uniformity, and clinical acceptability of hydrocortisone oral suspensions prepared from tablets and powder.

DESIGN

Hydrocortisone 2.5 mg/mL oral suspensions were stored in the dark for 91 days at 5, 25, and 40 degrees C. Dosage uniformity was assessed by repeated sampling of the formulation prepared from tablets at 5 and 25 degrees C. The formulation was clinically evaluated in 2 pediatric patients.

SETTING

A university pharmacy school and affiliated urban teaching hospital.

PARTICIPANTS

A brother (4 y old) and sister (1 y old) with congenital adrenal hyperplasia maintained on a commercially available hydrocortisone cypionate suspension.

MAIN OUTCOME MEASURES

Samples removed at 5 time points were analyzed for hydrocortisone to assess decomposition over 90 days. Dosage uniformity was evaluated by intra- and interday variability. Palatability was examined in the 2 children and urinary cortisol concentrations were measured in the boy before and 5 days after commencing the formulation prepared from tablets.

RESULTS

Decomposition of hydrocortisone was not significant except in the formulation that was prepared from tablets and stored at 40 degrees C. Dosage uniformity gave coefficients of variation less than 4.5%. The formulation was well-tolerated and resulted in satisfactory urinary cortisol concentrations in the boy.

CONCLUSIONS

The hydrocortisone oral suspensions supply a uniform dose and are chemically stable when stored in the dark at 5 and 25 degrees C for at least 30 days. They provide flexible and convenient dosage forms for pediatric patients.

STD1 (MSN3) interacts directly with the TATA-binding protein and modulates transcription of the SUC2 gene of Saccharomyces cerevisiae

STD1 (MSN3) was isolated independently as a multicopy suppressor of mutations in the TATA-binding protein and in SNF4, suggesting that STD1 might couple the SNF1 kinase signaling pathway to the transcriptional machinery. We report here a direct physical interaction between STD1 and the TATA-binding protein (TBP), observed in vivo by the two-hybrid system and in vitro by binding studies. STD1 bound both native TBP in yeast cell-free extracts and purified recombinant TBP. This interaction was altered when TBP delta 57 was used, suggesting a role for the non-conserved N-terminal domain of TBP in mediating protein-protein interactions. We also show that perturbation of STD1-TBP stoichiometry alters SUC2 expression in vivo and that this effect is dependent on the N-terminal domain of TBP. The activation of SUC2 expression by increased copy number of STD1 occurs at the level of mRNA accumulation and it requires the same TATA element and uses the same transcription start site as does activation of SUC2 by glucose limitation. Taken together, these results suggest that STD1 modulates SUC2 transcription through direct interactions with TBP.

Function and differential regulation of the alpha 6 integrin isoforms during parietal endoderm differentiation

F9 embryonal carcinoma cells treated with retinoic acid differentiate in monolayer into parietal endoderm (PE) or in suspension into embryoid bodies with an outer layer of visceral endoderm (VE) surrounding a core of largely undifferentiated cells. Previous reports have shown that cell-extracellular matrix interactions mediated by the beta 1 integrins play a critical role in the differentiation and migration of PE. In the present study we investigated the pattern of expression and function of the integrin alpha 6 beta 1 during the differentiation of F9 cells into VE and PE. F9 cells express integrin subunits alpha 3, alpha 5, alpha 6, and beta 1. Cell adhesion and migration assays demonstrate that alpha 6 beta 1 is the major laminin receptor in undifferentiated F9 cells as well as F9-derived PE cells. However, the amount of alpha 6 protein decreases significantly upon F9 cell differentiation into either VE or PE, as revealed by immunofluorescent staining and immunoprecipitation analysis. In contrast, the amount of steady-state alpha 6 message stays constant before and after F9 cell differentiation, suggesting that the down-regulation of alpha 6 beta 1 occurs post-transcriptionally. In view of previous reports of two alpha 6 isoforms generated by alternative RNA processing, we carried out reverse transcription-PCR analysis and show that, while alpha 6B is the major mRNA isoform before and after F9 cell differentiation, alpha 6A mRNA is weakly expressed in undifferentiated F9 cells and is substantially increased following F9 differentiation into PE. Immunoprecipitations using the isoform-specific antibodies show an increase in alpha 6A and a dramatic decrease in alpha 6B protein following PE differentiation. Pulse-chase experiments indicate that, whereas the stability of alpha 6B protein is unaltered, synthesis of alpha 6B protein is decreased at least threefold following PE differentiation. Further experiments demonstrate that alpha 6A localizes to focal contacts in PE cells. The switch from alpha 6B to alpha 6A and the localization of alpha 6A at focal contacts correlate with the acquisition of PE cell motility, which suggests distinct functions for the two alpha 6 isoforms.

[A study of epidermal growth factor receptor in human colorectal cancer]

Membrane extracts of surgically resected colorectal cancer and nearby non-cancerous tissues were prepared and the expression of epidermal growth factor receptor (EGF-R) was examined by 125I-EGF binding assay. Scatchard analysis indicated that a single class of EGF-R was present in the cancer as well as the non-cancerous tissues. EGF-R was found over-expressed in cancer (38.07 +/- 4.75 fmol/mg protein) as compared to that in the non-cancerous tissue (29.31 +/- 1.64 fmol/mg protein) (P < 0.05). However, the difference in binding affinities of EGF-R in the cancer and non-cancerous tissues was not statistically significant. The results suggest an important role of an autocrine/paracrine loop of growth regulation in colorectal cancer.

A family of proteins containing a conserved domain that mediates interaction with the yeast SNF1 protein kinase complex

The SNF1 protein kinase is required for the regulatory response to glucose starvation in Saccharomyces cerevisiae. SNF1 is a protein serine/threonine kinase that has been widely conserved in both plants and mammals. Previously, we identified SIP1 and SIP2 as proteins that interact with SNF1 in vivo by the two-hybrid system. We have cloned the SIP2 gene and the encoded protein is homologous to SIP1 and to GAL83, which affects glucose repression of the GAL genes. We show that SIP2 and GAL83, like SIP1, co-immunoprecipitate with SNF1 and are phosphorylated in vitro. An 80 amino acid sequence, designated the ASC domain, is highly conserved at the C-termini of all three proteins. We show that this small domain can mediate protein-protein interaction with the SNF1 kinase complex. Thus, SIP1, SIP2 and GAL83 define a family of homologous proteins that are tightly associated with the SNF1 kinase, probably in alternative forms of the complex. Genetic evidence suggests that the three proteins have distinct, but related, functions in the SNF1 pathway, and deletion of GAL83 dramatically reduces SNF1 activity in immune complex assays. We propose that SIP1, SIP2 and GAL83 act as adaptors that promote the activity of SNF1 towards specific targets.

Time course of lipid peroxidation in puromycin aminonucleoside-induced nephropathy

Reactive oxygen species have been implicated in the pathogenesis of acute puromycin aminonucleoside (PAN)-induced nephropathy, with antioxidants significantly reducing the proteinuria. The temporal relationship between lipid peroxidation in the kidney and proteinuria was examined in this study. Rats were treated with a single IV injection of puromycin aminonucleoside, (PAN, 7.5 mg/kg) and 24 hour urine samples were obtained prior to sacrifice on days 3,5,7,10,17,27,41 (N = 5-10 per group). The kidneys were removed, flushed with ice cold TRIS buffer. Kidney cortices from each animal were used to prepare homogenates. Tissue lipid peroxidation was measured in whole homogenates as well as in lipid extracts from homogenates as thiobarbituric acid reactive substances. Proteinuria was evident at day 5, peaked at day 7 and persisted to day 27. Lipid peroxidation in homogenates was maximal at day 3 and declined rapidly to control levels by day 17. This study supports the role of lipid peroxidation in mediating the proteinuric injury in PAN nephropathy.

Infusion of large quantities of autologous blood monocyte-derived macrophages in two cancer patients did not induce increased concentration of IL-6, TNF-alpha, soluble CD14 and nitrate in blood plasma

In an attempt to increase the number of macrophages available for reinfusion in immunotherapy trials, GM-CSF was injected in vivo to mobilize circulating blood monocytes in 2 cancer patients. Subsequently mononuclear cells were collected by apheresis, cultured in the presence of GM-CSF and activated with IFN-gamma. This procedure resulted in the harvesting of 1.3 to 3.1 x 10(9) (mean 2 x 10(9)) macrophages per apheresis, product which was very well tolerated at autologous reinfusion. These infusions did not induce increased levels of TNF-alpha, IL-6, soluble CD14 nor nitrates in blood plasma (or urine). The lack of TNF-alpha and IL-6 release in blood plasma could explain the good tolerance of these infusions. No in vivo anti-tumoural activity of these high numbers of infused macrophages could be observed.

[Investigations on the present status of infections with Chlamydia trachomatis (Ct), Mycoplasma hominis (Mh) and Ureaplasma urealyticum (Uu) in patients with venereal diseases, sexual abusers and healthy people in Da Lian]

From January to June 1992, we conducted the detection of serum antibodies against Ct, Mh and Uu in patients with venereal diseases, sexual abusers and healthy people. The results showed that the positive rates of antibodies against Ct, Mh and Uu in patients were the highest, while in healthy people those of antibodies against Ct and Uu were the lowest. The positive rates between the antibody against Uu and that against Mh have no obvious difference between male and female. All samples have dual infection of Ct and Mh.

Dosage-dependent modulation of glucose repression by MSN3 (STD1) in Saccharomyces cerevisiae

The SNF1 protein kinase of Saccharomyces cerevisiae is required to relieve glucose repression of transcription. To identify components of the SNF1 pathway, we isolated multicopy suppressors of defects caused by loss of SNF4, an activator of the SNF1 kinase. Increased dosage of the MSN3 gene restored invertase expression in snf4 mutants and also relieved glucose repression in the wild type. Deletion of MSN3 caused no substantial phenotype, and we identified a homolog, MTH1, encoding a protein 61% identical to MSN3. Both are also homologous to chicken fimbrin, human plastin, and yeast SAC6 over a 43-residue region. Deletion of MSN3 and MTH1 together impaired derepression of invertase in response to glucose limitation. Finally, MSN3 physically interacts with the SNF1 protein kinase, as assayed by a two-hybrid system and by in vitro binding studies. MSN3 is the same gene as STD1, a multicopy suppressor of defects caused by overexpression of the C terminus of TATA-binding protein (R. W. Ganster, W. Shen, and M. C. Schmidt, Mol. Cell. Biol. 13:3650-3659, 1993). Taken together, these data suggest that MSN3 modulates the regulatory response to glucose and may couple the SNF1 pathway to transcription.

[Application of A-scan ultrasonography in the diagnosis and treatment of myositis of extraocular muscles (with a report of four cases)]

Four cases of myositis of extraocular muscles were diagnosed by A-scan ultrasonography. The diagnostic criteria were thickening, low reflectivity and homogeneous internal structure of affected muscles. Under the monitor of A-scan ultrasonography all cases were treated with high dose prednisone. Three of the four were cured, and one regressed. Meanwhile, the clinical manifestations and differential diagnosis of the disease are discussed briefly.

[Effect of the changes of amino acids on both signal peptide C-terminal and mature protein N-terminal region to the secretion of alpha-amylase in B. subtilis]

By site-directed mutagenesis, G and C have taken the place of T and G at nucleotide sequence 287 and 291 of B. licheniformis alpha-amylase gene to generate pAm-y413B and the N-terminal sequence of mature protein have been changed from 7Leu 8Met to 7Arg8Ile. By the insertion of polylinker into the C-terminal of the signal sequence of alpha-amylase gene of pAmy413, the signal peptide of alpha-amylase produced by pAmy413L is 13 amino acids more than the pAmy413 (which is 29 amino acids long) and also, a new recognition cleavage sequence for signal peptidase I (Ala-Gln-Ala decreases Ser) is created; The secondary structure of the signal peptide has been analyzed by computer programs. The alpha-amylase relative activity of the two mutant strains is 3% and 36% of pAmy413, respectively. The molecular weight of extracellular alpha-amylase is the same as pAmy413. Terminal analysis shows that the N-terminal amino acid of mature protein is Ala, not Ser, and suggests that SPase I prefers to cleavage at the wild type recognition site (Ala-Ala-Ala decreases Ala). Therefore, all of the above results show that the secretion of alpha-amylase in B. subtilis is in accordance with the co-translational transportation model.