Heterologous expression of thermopsin, a heat-stable acid proteinase

We have previously reported the isolation, characterization, and gene sequence of a new thermostable acid protease, thermopsin, from Sulfolobus acidocaldarius, a thermophilic archaebacterium. Thermopsin is similar to aspartic protease pepsin in specificity and pH dependence. However, it optimally catalyzes in the temperature range of 85 to 90 degrees C and it is not structurally related to pepsin. The current report describes the synthesis of recombinant thermopsin in E. coli and in insect cells. Several recombinant thermopsin fusion proteins were expressed as "inclusion bodies" in the cytosol of E. coli. Active thermopsin preparations were obtained by refolding from urea solutions. Recombinant thermopsin was also expressed in insect cells using a baculovirus expression system. The thermostability of recombinant thermopsin is similar to that of the native enzyme.

[The effects of dachengqi decoction, shaogan decoction, emodin and sennoside on the histamine level of intestinal mucosa in intestinally obstructed rats]

The experimental intestinal obstruction model was made by partly ligating the ileum in rat. The histamine levels of obstruction groups (8.14 +/- 2.28 micrograms/g) were obviously lower than those of control groups (P < 0.01). After administration of Dachengqi decoction, Shaogan decoction, emodin and sennoside, the levels of histamine were significantly higher than those of obstruction groups, but there were no significant differences as compared with control groups.

A conserved region in human and Chinese hamster X chromosomes can induce cellular senescence of nickel-transformed Chinese hamster cell lines

Cellular senescence is the genetically programmed cessation of cellular proliferation. We have recently mapped a putative senescence gene(s) on the X chromosome of Chinese hamster embryo (CHE) cells. In the present study, we have utilized microcell-mediated chromosome transfer (microcell fusion) to test whether: (i) the human X chromosome exhibits similar genetic potential to induce senescence and (ii) the deletion or inactivation of the X-linked senescence gene(s) in CHE cells is associated with nickel-induced immortalization. A normal CHE or human X chromosome was first introduced into mouse-cell hybrids, then transferred by microcell fusion into a nickel-transformed, immortal male CHE cell line (Ni-2/TGR) with an X deletion (Xq1). Microcell fusion of the normal CHE X chromosome into tumorigenic Ni-2/TGR cells yielded senescence of all X recipient clones. The normal human X chromosome induced dominant senescence of tumorigenic Ni-2/TGR cells in only 17% of the resulting microcell hybrids (14/81). Karyotypic analyses of 13 non-senescing human X chromosome-derived microcell hybrid clones revealed that none of these clones retained the complete X. A normal CHE X chromosome induced senescence of 75% of hybrids obtained with another immortal and tumorigenic nickel-transformed male CHE cell line (Ni-6/TGR), which exhibited no visible deletion of the X chromosome, while the normal human X chromosome, only induced senescence in 19% of these hybrids. Transfer of the normal CHE or human X chromosome into spontaneously transformed and tumorigenic cell lines, CHO/TGR or V79/TGR, had little or no effect on their growth. These data suggest that both human and CHE cells possess similar X-linked genetic activities that regulate the process of cellular senescence, and that in Chinese hamster cells nickel-induced immortalization but not that of CHO or V79 cells is associated with inactivation of an X-linked senescence gene.

[Isolation of desmosomes: a marker for epithelial tumors]

A simple method is reported for the isolation of desmosomes. The fresh noncornified layers of cow nose epidermis were immersed in 0.1 mol/L citric acid-sodium citrate buffer (pH 2.3, containing 0.5 mmol/L PMSF), and then treated with homogenization and discontinuous sucrose density gradient centrifugation. Desmosomes were located at the 50-56% sucrose interface. Electron microscopy revealed that the characteristic desmosome structure was well preserved, and that a few intermediate filament bundles attached to desmosome plaque were removed by the solubilizing action of the buffer. Approximate 100 mg desmosomes (dry weight) were got from 20g wet noncornified layers of epidermic tissue.

Internally standardized amino acid analysis for determining peptide/carrier protein coupling ratio

A method based on amino acid analysis has been developed for monitoring the covalent conjugation of synthetic peptide haptens to carrier proteins. The marker amino acid, alpha-aminobutyric acid, is included in the sequence during peptide synthesis. Following reaction, the carrier protein-conjugate is freed of excess peptide by two successive rounds of gel filtration chromatography. Amino acid analysis of a hydrolysate of the conjugate allows the calculation of the coupling ratio of the peptide to the carrier protein. Two typical procedures for conjugation, carbodiimide cross-linking and cysteine-thiol reaction with maleimidyl-proteins, have been evaluated.

Differential accumulation of transcripts encoding protein kinase homologs in greening pea seedlings

Degenerate oligonucleotides, corresponding to conserved regions within the catalytic domain of known protein-serine/threonine kinases, were used as primers for the polymerase chain reaction to amplify cDNA synthesized from poly(A)+ RNA purified from the apical buds of 7-day-old pea seedlings. Five partial cDNAs were obtained and designated PsPK1 through PsPK5 (for Pisum sativum protein kinase) in order of decreasing length. The deduced amino acid sequences show that each member of the PsPK series is different in length, and, although their sequences are quite similar overall, each has a unique sequence. Moreover, each member of the PsPK series has structural features typical of members of the protein-serine/threonine kinase family of protein kinases. All are equally similar to cyclic nucleotide-dependent protein kinase and protein kinase C, suggesting that the pea homologs may be involved in signal transduction. DNA gel blots show that each PsPK cDNA is likely to be encoded by a single gene within the pea genome. RNA blot analyses show that the PsPK transcripts accumulate differentially during greening of etiolated seedlings. PsPK3 and PsPK5 transcripts show a large and rapid decline during deetiolation. In contrast, the level of PsPK4 RNA increases steadily during deetiolation whereas PsPK1 and PsPK2 transcripts show little change during the greening period. Thus light regulates changes in the levels of transcripts encoding putative protein kinases in plants.

A receptor that is highly specific for extracellular ATP in developing chick skeletal muscle in vitro

1. Extracellular adenosine 5'-triphosphate (ATP) activated an early excitatory conductance followed by a late potassium conductance in developing chick skeletal muscle. A series of ATP analogues were tested for their ability to activate these two conductances. All compounds tested were either agonists for both responses or for neither. Furthermore, the potency of agonists was similar for the two responses. 2. The order of potency for agonists was ATP approximately adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S) approximately 2-methylthio-ATP (2-CH3S-ATP) greater than 2'-deoxy-ATP approximately 3'-deoxy-ATP greater than adenosine 5'-tetraphosphate (ATP-OPO3) approximately adenosine 5'-diphosphate (ADP). Many other ATP analogues were not agonists. 3. Activation of the excitatory response did not require divalent cations. Furthermore, the concentration-response relation of the excitatory response was similar when ATP was applied as the free anion of ATP (ATP4-) or complexed with a divalent cation (M.ATP2-). 4. Three antagonists of the ATP response were characterized. 8-Br-ATP was a weak antagonist, while 2',3'-dialdehyde-ATP and DIDS (4,4'-diisocyanatostilbene-2,2'-disulphonic acid) were potent irreversible inhibitors. The two conductances were equally affected by these antagonists. 5. These results suggest that both ATP responses are activated through the same receptor type, or two very similar receptors.

Qualitative analysis of an HIV transmission model

In 1988, a multiple-group model for HIV transmission with preferred mixing was proposed by Jacquez and coworkers. In the present paper, the work done by Jacquez et al. is extended. It is shown that the stability modulus of the Jacobian matrix at the no-disease equilibrium is a threshold for this model. Furthermore, if the no-disease equilibrium is unstable, the number of infected individuals will remain above a certain positive level regardless of initial levels; that is, the disease will persist uniformly. The stability of the endemic equilibrium in the case of restricted mixing is also studied. A series of sufficient conditions for local and global asymptotic stability of the endemic equilibrium are stated.

[Lectin histochemistry in psoriasis, lichen planus and keratosis seborrheica]

Using 14 different biotinyl lectins and avidin horseradish peroxidase, we studied the lectin binding patterns in the epidermis of the lesions in 37 cases of psoriasis, 9 cases of lichen planus and 18 cases of keratosis seborrheica. In comparison with normal human skin, epidermal lectin binding patterns in these diseases showed considerable qualitative and quantitative abnormalities, among which some were characteristic. These findings revealed significant changes in keratinocytic glycoconjugates in these diseases, providing clues to their pathogeneses. The detected changes suggest that the maturation pathway of the keratinocytes in psoriasis differs qualitatively from the normal cases and is not merely a result of rapid transit of the cells.

Regulation of steroidogenesis of infant and adult rhesus monkey granulosa cells in vitro

The present studies have demonstrated that infant monkey granulosa cells, like the adult ones, have the potential of responding markedly in vitro to human FSH, cyclic-AMP and forskolin, resulting in the increase of progesterone and estrogen production. Exogenous hCG was also capable of increasing FSH-stimulated progesterone biosynthesis in both infant and adult granulosa cells, but did not stimulate the infant granulosa cells to secrete estrogen. Addition of a synthetic estrogen, diethylstilbestrol, to the culture of monkey granulosa cells enhanced the FSH-stimulated progesterone and estrogen production. The steroidogenesis of monkey granulosa cells was also dramatically stimulated by a gonadotropin-releasing hormone agonist. Monkey granulosa cells, unlike the other animal cells, secrete measurable amount of estrogen in the absence of androgen substrate. The findings reported here are significant in regard to understanding of the mechanism of hormonal regulation of primate ovarian function.

Treatment of functional headache with Chinese herbal inhalant--a report of 496 cases

Headaches of the neurofunctional type, blood vascular type, neuro-vascular type, and musculotonic type are commonly encountered clinically. The authors report a nasal inhalant of Chinese herbal drugs which has been effective in the treatment of these varieties of headache.

Purification, characterization, and gene cloning of thermopsin, a thermostable acid protease from Sulfolobus acidocaldarius

A thermostable, acid proteolytic activity has been found to be associated with the cells and in the culture medium of Sulfolobus acidocaldarius, an archaebacterium. This acid protease, which has been named thermopsin, was purified to homogeneity from the culture medium by a five-step procedure including column chromatographies on DEAE-Sepharose CL-6B, phenyl-Sepharose CL-4B, Sephadex G-100, monoQ (fast protein liquid chromatography), and gel filtration (high pressure liquid chromatography). The purified thermopsin produced a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the proteolytic activity was associated with the band. Thermopsin is a single-chain protein as indicated by gel electrophoresis and by a single NH2-terminal sequence. It has maximal proteolytic activity at pH 2 and 90 degrees C. A genomic library of S. acidocaldarius was prepared and screened by an oligonucleotide probe designed from the NH2-terminal sequence of thermopsin. Five positive clones were isolated. From these clones the thermopsin gene was mapped and sequenced. The nucleotide sequence showed that the thermopsin structure is encoded in 1020 bases. In the deduced protein sequence, there are 41 amino acid residues (including the initiation Met) preceding the NH2-terminal position of thermopsin. Most of these residues appear to be characteristic of a leader sequence. However, the presence in this region of a short pro sequence cannot be ruled out. Thermopsin contains a single cysteine at residue 237 that is not essential for activity (Fusek, M., Lin, X.-L., Tang, J. (1990) J. Biol. Chem. 265, 1496-1501. Thermopsin has no apparent sequence similarity to aspartic proteases of the pepsin family nor to pepstatin-insensitive acid protease (Maita, T., Nagata, S., Matsuda, G., Murata, S., Oda, K., Murao, S., and Tsura, D. (1984) J. Biochem. 95, 465-475) and thus may represent a new class of acid proteases. Also absent is the characteristic active site aspartyl sequence of aspartic proteases. There are 11 potential N-glycosylation sites on each thermopsin molecule. The molecular weight estimated from gel filtration (45,000) is larger than that calculated from the sequence (32,651), suggesting that thermopsin is the sequence (32,651), suggesting that thermopsin is glycosylated at at least some of these 11 sites.

[A study of the quality of Fujian native Magnolia officinalis Rehd. et Wils. var. biloba Rehd. et Wils]

This study reports on the connexion of the content of the efficacious constituents, magnolol and honokiol of Magnolia officinalis var. biloba with age, diameter of the trunk and various parts of the tree, thus presenting a basis for its collection, quality control and clinical applications.

Pulmonary corpora amylacea in sheep

Pulmonary corpora amylacea (PCA) were found in 36 per cent of lambs with chronic non-progressive pneumonia. They were spheroidal or ovoid, concentrically lamellar, and commonly found in the alveoli. The components of PCA were complex and variable but staining reactions indicated that most of them contained deoxyribonucleoproteins, glycoproteins and ribonucleoproteins. Electron microscopy showed that they were composed of a fine granular material with an occasional vesicular pattern. There are a number of differences in the morphology and staining reaction of ovine PCA compared with those described in man. Some of these differences may be related to their age. Ovine PCA are closely associated with chronic non-progressive pneumonia and it is postulated that they may result indirectly from bronchiolar stenosis and stagnation of exudate.