A study on the gustatory effects of tetrodotoxin in rat (author's transl)]

Effects of tetrodotoxin (TTX) on neural responses of the chorda tympani to four basic taste stimuli were investigated electrophysiologically in rats. When the TTX (10 mg/ml) was applied directly to the tongue surface for 3 minutes, magnitude of the integrated responses of the chorda tympani was diminished to about 60% of that of the control response. This diminution of response was recovered within 30 minutes by degrees and the effect of the TTX was antagonized by guanylate. This result gives a suggestion that guanidyl group in the TTX may play an important role for the inhibitory actions to the responses of the chorda tympani. On the other hand, when the TTX (0.25 mg/100 g b. wt.) was applied intravenously, magnitude of the responses of the chorda tympani to four basic taste stimuli decreased gradually to 20 approximately 30% of that of the control responses within 60 minutes and did not recover more than 10 hours. This is assumed due to the blocking of the sodium pump of nerve fibers in the chorda tympani by the TTX.     

A Prunus mume extract stimulated the proliferation and differentiation of osteoblastic MC3T3-E1 cells

Osteoporosis is a serious disease caused by decreased bone mass. There is constant matrix remodeling in bones, by which bone formation is performed by osteoblastic cells, whereas bone resorption is accomplished by osteoclast cells. We investigated the effect of a Japanese apricot (Prunus mume SIBE. et ZUCC.) extract on the proliferation and osteoblastic differentiation in pre-osteoblastic MC3T3-E1 cells. An alkaline phosphatase (ALP) activity assay, cell proliferation assay, alizarin red staining and expression analysis of osteoblastic genes were carried out to assess the proliferation and osteoblastic differentiation. The water-soluble fraction of Prunus mume (PWF) increased the ALP activity, cell proliferation and mineralization. The gene expression of osteopontin and bone morphogenetic protein-2, which are markers in the early period of osteoblastic differentiation, were significantly enhanced by the PWF treatment. PWF therefore stimulated the proliferation and osteoblastic differentiation of cells and may have potential to prevent osteoporosis.     

Enhanced production of 2,3-butanediol by engineered <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Production of 2,3-butanediol by Bacillus subtilis takes place in late-log or stationary phase, depending on the expression of bdhA gene encoding acetoin reductase, which converts acetoin to 2,3-butanediol. The present work focuses on the development of a strain of B. subtilis for enhanced production of 2,3-butanediol in early log phase of growth cycle. For this, the bdhA gene was expressed under the control of P _alsSD promoter of AlsSD operon for acetoin fermentation which served the substrate for 2,3-butanediol production. Addition of acetic acid in the medium induced the production of 2,3-butanediol by 2-fold. Two-step aerobic–anaerobic fermentation further enhanced 2,3-butanediol production by 4-fold in comparison to the control parental strain. Thus, addition of acetic acid and low dissolved oxygen in the medium are involved in activation of bdhA gene expression from P _alsSD promoter in early log phase. Under the conditions tested in this work, the maximum production of 2,3-butanediol, 2.1 g/l from 10 g/l glucose, was obtained at 24 h. Furthermore, under the optimized microaerophilic condition, the production of 2,3-butanediol improved up to 6.1 g/l and overall productivity increased by 6.7-fold to 0.4 g/l h in the engineered strain compared to that in the parental control.     

Cernunnos/XLF: a new player in DNA double-strand break repair

Non-homologous end-joining (NHEJ) is the predominant repair pathway for DNA double-strand breaks (DSBs) in vertebrates and also plays a crucial role in V(D)J recombination of immunoglobulin genes. Cernunnos/XLF is a newly identified core factor for NHEJ, and its defect causes a genetic disease characterized by neural disorders, immunodeficiency and increased radiosensitivity. Cernunnos/XLF has at least two distinct functions in NHEJ. Cernunnos/XLF interacts with and stimulates the XRCC4/DNA ligase IV complex, which acts at the final ligation step in NHEJ. In living cells, Cernunnos/XLF quickly responds to DSB induction and accumulates at damaged sites in a Ku-dependent but XRCC4-independent manner. These observations indicate that Cernunnos/XLF plays a unique role in bridging damage sensing and DSB rejoining steps of NHEJ. Recent crystallographic analyses of the homodimeric Cernunnos/XLF protein provide structural insights into the Cernunnos/XLF functions. These studies offer important clues toward understanding the molecular mechanism for NHEJ-defective diseases.     

Molecular Structure of Xanthocidin

In order to establish industrial production of 5′-inosinic acid (5′-IMP), a permeability mutant, KY13171, of Brevibacterium ammoniagenes, which accumulated 7 to 8 grams of 5′-IMP per liter and 4 to 6 grams of hypoxanthine (Hx) per liter (calculated as 5′-IMP), was improved by a genetical procedure. Further improved mutants were selected stepwise through repeating mutational work. The finally selected mutant. KY13369, accumulated 20 to 27 grams of 5′-IMP per liter, but not Hx.

Increased productivity of 5′-IMP and decreased productivity of Hx were not caused by the changes in 5′-IMP degrading activity, because these activities were not significantly different among the mutants. These results appear to indicate that the increased accumulation of 5′-IMP may be caused by the improvement in membrane permeability for 5′-IMP. However, the changes in phospholipid and fatty acid compositions were not enough to explain the increased permeability.     

The role of 5'-methylthioadenosine on rat calvaria cell differentiation.

The role of 5'-methylthioadenosine (MTA), formed during the process of polyamine biosynthesis, on differentiation of osteoprogenitor cells was assessed by its effects on alkaline phosphatase (ALP) activity, bone nodule formation and osteopontin contents of cultured rat calvaria (RC) cells. These three markers were stimulated by exogenous MTA and were depressed by 5'-difluoromethylthioadenosine (DFMTA), a synthetic inhibitor of MTA phosphorylase, which cleaves MTA to adenine and 5-methylthioribose-1-phosphate. 5-Methylthioribose and 2-keto-4-methylthiobutyrate, metabolites of 5-methylthioribose-1-phosphate, had no effects on ALP activity and bone nodule formation in the presence or absence of DFMTA. On the other hand, adenine enhanced ALP activity, bone nodule formation and osteopontin contents in mineralized nodules and also partially reversed DFMTA-induced inhibition of these three markers. MTA, its metabolites and DFMTA did not affect the growth of RC cells under these culture conditions. These results suggest that adenine formed from MTA is important in the differentiation of RC cells.     

The Eiken Latex test for detection of a cryptococcal antigen in cryptococcosis

A latex agglutination test for cryptococcal antigen, the Eiken Latex test (Eiken, Tokyo, Japan), was compared with a monoclonal antibody-based agglutination assay, Pastorex^® Cryptococcus (Diagnostics Pasteur, Marneur-la-Coquette, France). In a murine model of disseminated cryptococcosis, the kinetics of the antigen titers by the Eiken Latex were similar to those by the Pastorex^® Cryptococcus, but sensitivity was much higher. In HIV-negative patients with pulmonary cryptococcosis, a cryptococcal antigen was detected in 6 of 10 patients by the Eiken Latex test and in only 3 of those patients by the Pastorex^® Cryptococcus. The results indicate that the Eiken Latex is more sensitive for the detection of the cryptococcal antigen, even in non-disseminated cryptococcosis. The sensitivity and specificity of the Eiken Latex were examined using 195 sera from 25 patients with pulmonary cryptococcosis and 170 patients with non-cryptococcosis. The cutoff value of 1:8 showed a sensitivity of 76% (19/25) and a specificity of 98.9% (168/170).