Lipase-catalyzed transamidation of non-activated amides in organic solvent

A novel biocatalytic reaction of transamidation of non-activated amides with amines is reported. Among 45 different lipolytic and proteolytic enzymes tested, only the lipase from Candida antarcticawas able to catalyze this reaction. The reaction proceeded with up to ca. 80% conversion in anhydrous methyl tert-butyl ether and worked with both N-substituted and unsubstituted amides. The biocatalytic transamidation is an equilibrium process and, therefore, higher conversions to the desired amide were achieved by using increased concentrations of the amine nucleophile.     

Climate Driven Life Histories: The Case of the Mediterranean Storm Petrel

Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time.     

Biosynthesis of various types of collagen by human hepatoma cells in vitro

A cloned human hepatoma cell line (HH2-1) produced and formed collagen fibers in vitro. The relative rate of collagen synthesis by the cells was increased with an enhancement of the cell density. An analysis of the components of the collagen using sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the cells synthesized interstitial collagen, types I and III, and other collagenous proteins. Thus, human hepatoma cells may play an important role in the formation of stromal collagen in the tumor.     

Pr-SNTX,a short-chain three-finger toxin from Papuan pigmy mulga snake,is an antagonist of muscle-type nicotinic acetylcholine receptor (α2βδε)

Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α₂βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity.     

Distribution of spermine in bacilli and lactic acid bacteria

Obligate moderately thermophilic bacilli and obligate moderately thermoacidophilic bacilli contained spermine as the major polyamine in addition to putrescine and spermidine. The identity of spermine was confirmed by thin-layer chromatography and high-performance liquid chromatography before and after treatment with putrescine oxidase. Using these methods, thermospermine and spermine can be separated; thermospermine was not present in these organisms. On the other hand, various facultative thermophiles and mesophilic strains of the genus Bacillus, including alkalophiles and halophiles, lack spermine and other tetraamines. No spermine was detected in several strains of mesophilic or facultative slightly thermophilic lactic acid bacteria, Lactobacillus and Streptococcus.     

Evidence of intracellular and trans-acting differentiation-inducing activity in human promyelocytic leukemia HL-60 cells: its possible involvement in process of cell differentiation from a commitment step to a phenotype-expression step

We previously reported that human promyelocytic leukemia HL-60 cells, when treated with various inducers in magnesium-deficient medium, became committed to differentiate but did not express the differentiation-related phenotypes (Okazaki et al., J. Cell. Physiol., 131:50-57, 1987). In the present study we demonstrated the existence of an intracellular differentiation-inducing activity (int-DIA) in differentiation-committed phenotype-nonexpressing HL-60 cells by using cybrid formation between untreated HL-60 cells and cytoplasts from HL-60 cells treated in magnesium-deficient medium with 100 nM 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3). Cell extracts from similarly treated HL-60 cells also showed int-DIA, which when added (10 mg total protein/ml) to culture of untreated HL-60 cells, could increase the percentages of nitroblue tetrazolium (NBT)- and nonspecific esterase (NSE)-positive cells from 1% to 53%, and from 0 to 32%, respectively. They also induced differentiation of human monoblastic leukemia U-937 cells and of human myeloblastic leukemia KG-1 cells but not of erythroleukemia K-562 cells. These results suggested that the int-DIA had a common effect on differentiation induction in several human myeloid cell lines and may be involved in inducing cells to proceed from a commitment to a phenotype-expression step during human myeloid cell differentiation.     

Establishment of the human hepatocellular carcinoma cell line and its characteristics

c-Hc-4 has been established and maintained for more than seven years. The hepatocellular carcinoma originated in 45-year old man with liver cirrhosis. The cell grew in vitro forming a sheet of monolayered cells and firmly attaching to the inner surface of cultured flasks. Morphologically they showed epithelial-like pattern. The doubling time was about 20 hours. Their modal chromosome number was 58. Serial heterologous transplantation in nude mice was successful. The histological finding was almost the same patterns as those in the primary tumor. The cultured cells produced alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA).     

Lipoxygenase activities of human platelets and their subcellular fractions: Comparison between lipoxygenase-deficient platelets and normal platelets

Lipoxygenase activities were estimated in washed platelets (intact platelets) and their subcellular fractions obtained from 7 patients with deficient platelet lipoxygenase activities and 9 normal subjects. From sonicated platelet preparations, 12,000 g supernatant (F-I), cytosol (F-II) and microsomal fractions (F-III) were prepared by differential centrifugation. When 12-hydroxyeicosatetraenoic acid (12-HETE) produced by the incubation of arachidonic acid with intact platelets or each of their subcellular fractions from normal subjects was measured by reversed-phase high-performance liquid chromatography analysis, the lipoxygenase activities of F-I, F-II and F-III were 87%, 31% and 17%, respectively, of the enzyme activity of intact platelets. One of the patients showed no detectable lipoxygenase activity in any preparation, while the other patients showed reduced enzyme activities in all preparations. The addition of CaCl2 significantly increased 12-HETE synthesis solely by F-I from these patients. In most of these patients, contrary to normal subjects, it appeared that the lipoxygenase activity was not fully expressed in intact platelets, since the F-I produced more 12-HETE than the intact platelets.