Constitutive activation of the fucAO operon and silencing of the divergently transcribed fucPIK operon by an IS5 element in Escherichia coli mutants selected for growth on L-1,2-propanediol

L-1,2-Propanediol is an irretrievable end product of L-fucose fermentation by Escherichia coli. Selection for increased aerobic growth rate on propanediol results in the escalation of basal synthesis of the NAD+-linked oxidoreductase encoded by fucO, a member of the fuc regulon for the utilization of L-fucose. In general, when fucO becomes constitutively expressed, two other simultaneous changes occur: the fucA gene encoding fuculose-1-phosphate aldolase becomes constitutively expressed and the fucPIK operon encoding fucose permease, fucose isomerase, and fuculose kinase becomes noninducible. In the present study, we show that fucO and fucA form an operon which is divergently transcribed from the adjacent fucPIK operon. In propanediol-positive and fucose-negative mutants the cis-controlling region shared by the operons fucAO and fucPIK is lengthened by 1.2 kilobases. DNA hybridization identified the insertion element to be IS5. This element, always oriented in the same direction with the left end (the BglII end) proximal to fucA, apparently causes constitutive expression of fucAO and noninducibility of fucPIK. The DNA of the fucAO operon and a part of the adjacent fucP was sequenced.

Effect of calcium ion on analgesia of opioid peptides

The analgesic effect produced by subcutaneous injection (SC) of morphine was antagonized by intracerebroventricular (ICV) but not intrathecal (ITH) injection of CaCl2. While ITH CaCl2 was devoid of any effect on the analgesia induced by ITH morphine, it did antagonize the analgesic effect produced by ITH injection of dynorphin A or (D-Pen2,D-Pen5)-enkephalin (DPDPE). In accordance with this, the uptake of 45Ca by synaptosomes prepared from the dorsal column of rat spinal cord was suppressed by dynorphin A or DPDPE, but not by morphine. The results imply that different kinds of opioid ligands might have different mechanisms of action at discrete areas of the CNS. Blockade of neuronal Ca2+ uptake may serve as an important mechanism for morphine analgesia in the brain as well as DPDPE and dynorphin A analgesia in the spinal cord.

Characterization of thin film surfaces over an extended spatial wavelength range

The statistical properties of a thin film surface over an extended spatial wavelength have been studied by using the methods of differential scattering and digital analysis of replica micrographs. It can be concluded that, for a given film thickness, the surface features corresponding to long spatial wavelengths greater than several thousand angstroms are dominated mainly by the substrate surface, while the fine details corresponding to short spatial wavelengths are dominated by the thin film material and deposition process. Effects of ion-beam bombardment during deposition on surface roughness are also discussed.

Identification of an encephalitogenic determinant of myelin proteolipid protein for SJL mice

PLP is the major protein constituent of central nervous system myelin. We have previously shown that SJL/J (H-2s) mice develop an acute form of EAE after immunization with PLP. The purpose of the present study was to identify an encephalitogenic determinant of PLP for SJL mice. We immunized SJL/J mice with a synthetic peptide identical to residues 130-147 QAHSLERVCHCLGKWLGH of murine PLP, a sequence having an amphipathic alpha-helical conformation. Although it did not induce disease, an overlapping peptide containing residues 139-154 HCLGKWLGHPDKFVGI was encephalitogenic. Immunization with this peptide induced severe clinical and histologic EAE in 3 of 20 mice. T cell enriched ILN cells from these mice responded specifically (3H-thymidine incorporation) to this peptide as well as to shorter analogues of this domain containing serine in place of cysteine at residues 138 and 140. Immunization with the serine-substituted PLP peptides 137-151 VSHSLGKWLGHPDKF and 139-151 HSLGKWLGHPDKF induced severe, acute EAE in 4 of 9 and 15 of 15 SJL mice, respectively, and their T cell enriched ILN cells responded not only to the analogues, but also to the native PLP sequence 139-154. These results indicate that residues 139-151 of murine PLP is an encephalitogenic determinant for SJL mice. Furthermore, like the PLP encephalitogenic domain for SWR (H-2q) mice, this determinant is also a T cell epitope with a coding sequence at the end of an exon.

Identification of an encephalitogenic determinant of myelin proteolipid protein for SJL mice

PLP is the major protein constituent of central nervous system myelin. We have previously shown that SJL/J (H-2s) mice develop an acute form of EAE after immunization with PLP. The purpose of the present study was to identify an encephalitogenic determinant of PLP for SJL mice. We immunized SJL/J mice with a synthetic peptide identical to residues 130-147 QAHSLERVCHCLGKWLGH of murine PLP, a sequence having an amphipathic alpha-helical conformation. Although it did not induce disease, an overlapping peptide containing residues 139-154 HCLGKWLGHPDKFVGI was encephalitogenic. Immunization with this peptide induced severe clinical and histologic EAE in 3 of 20 mice. T cell enriched ILN cells from these mice responded specifically (3H-thymidine incorporation) to this peptide as well as to shorter analogues of this domain containing serine in place of cysteine at residues 138 and 140. Immunization with the serine-substituted PLP peptides 137-151 VSHSLGKWLGHPDKF and 139-151 HSLGKWLGHPDKF induced severe, acute EAE in 4 of 9 and 15 of 15 SJL mice, respectively, and their T cell enriched ILN cells responded not only to the analogues, but also to the native PLP sequence 139-154. These results indicate that residues 139-151 of murine PLP is an encephalitogenic determinant for SJL mice. Furthermore, like the PLP encephalitogenic domain for SWR (H-2q) mice, this determinant is also a T cell epitope with a coding sequence at the end of an exon.

Preliminary report on microencapsulated islet transplantation in experimental diabetes mellitus in China

Pancreatic islets were encapsulated with sodium alginate-polylysine after procurement by collagenase digestion and Ficoll density-gradient-dispersion. The encapsulated islets were intact and during the first week of culture produced insulin 63 +/- 42 microU/d vs 69 +/- 42 microU/d by noncapsulated islets. Seven streptozotocin-induced diabetic rats each received 4.0-4.5 x 10(3) microencapsulated islets intraperitoneally. After transplantation, blood glucose dropped from 350 +/- 29 mg/dl to 142 +/- 12 mg/dl. To date, normoglycemia has been maintained for 222 days. Control animals either died or developed cataracts.