Adenosine 3′,5′-Cyclic Monophosphate-Deficient Mutants of Vibrio cholerae

Two adenosine 3',5'-cyclic monophosphate (AMP)-deficient mutants of Vibrio cholerae (biotype El Tor) were successfully isolated by nitrosoguanidine treatment followed by pencillin screening for pleiotropic sugar-negative clones. Exogenous cyclic AMP is required for the fermentation of sucrose, trehalose, fructose, maltose, and mannose but not of glucose, as well as for the formation of normal flagella and specific somatic antigens. A striking characteristic of the mutants is their growth behavior at higher temperatures. They cannot grow on TCBS selective plates at 37 C or higher unless they are provided with a supply of exogenous cyclic AMP, although they are capable of producing colonies on the same medium, even without cyclic AMP, at temperatures lower than 30 C. Since the mutants are converted to spheroplasts, spindle forms, and spiral filaments in cyclic AMP-free media at 37 C, and this phenomenon is stopped by the addition of cyclic AMP or a combination of 20% sucrose and 0.2% magnesium chloride, it is assumed that cyclic AMP is essential for the synthesis of the cell wall of V. cholerae at higher temperatures.     

Effects of menstrual cycle and physical training on heat loss responses during dynamic exercise at moderate intensity in a temperate environment

We evaluated the effects of the menstrual cycle and physical training on heat loss (sweating and cutaneous vasodilation) responses during moderate exercise in a temperate environment. Ten untrained (group U) and seven endurance-trained (group T) women (maximal O2 uptake of 36.7+/-1.1 vs. 49.4+/-1.7 ml.kg-1.min-1, respectively; P<0.05) performed a cycling exercise at 50% maximal O2 uptake for 30 min during both the midfollicular and midluteal menstrual phase in a temperate environment (ambient temperature of 25 degrees C, relative humidity of 45%). In group U, plasma levels of estrone, estradiol, and progesterone at rest and esophageal temperature (Tes) during exercise were significantly higher during the midluteal than during the midfollicular phase (P<0.05). Sweating rate and cutaneous blood flow (measured via laser-Doppler flowmetry) on the chest, back, forearm, and thigh were lower during the midluteal than during the midfollicular phase during exercise. Tes threshold for heat loss responses was significantly higher and sensitivity of the heat loss responses was significantly lower in the midluteal than in the midfollicular phase, regardless of body site. These effects of the menstrual cycle in group U were not observed in group T. The sweating rate and cutaneous blood flow were significantly higher in group T than in group U, regardless of menstrual phase or body site. Tes threshold for heat loss responses was significantly lower and sensitivity of heat loss responses was significantly greater in group T than in group U in the midluteal phase; however, sensitivity of the sweating response was significantly greater in the midfollicular phase. These results suggest that heat loss responses in group U were inhibited in the midluteal phase compared with in the midfollicular phase. Menstrual cycle had no remarkable effects in group T. Physical training improved heat loss responses, which was more marked in the midluteal than in the midfollicular phase.     

Identification of a novel aquaporin, AQP12, expressed in pancreatic acinar cells

Members of the aquaporin (AQP) water channel family are widely distributed in various tissues and contribute to the water permeability of epithelial and endothelial cells. Currently 11 members of the AQP family (AQP0-10) have been reported in mammals. Here we report the identification of AQP12, which we found by performing a BLAST program search. Northern blot analysis revealed that AQP12 was specifically expressed in the pancreas. Further analysis by in situ hybridization and RT-PCR studies showed that AQP12 was selectively localized in the acinar cells of the pancreas. To analyze the cellular localization and function of AQP12, we expressed AQP12 in Xenopus oocytes and cultured mammalian cells. Immunocytochemistry revealed that AQP12 was not targeted to the plasma membrane. The selective localization of AQP12 in pancreatic acinar cells and possibly in the intracellular organelles suggests a role of AQP12 in digestive enzyme secretion such as maturation and exocytosis of secretory granules.     

Akt is a neutral amplifier for Th cell differentiation

Both CD28 and its relative, inducible costimulator (ICOS), have a binding motif for phosphatidylinositol 3-kinase (PI3K) in their cytoplasmic tail, and the binding of PI3K leads to activation of a serine/threonine kinase, Akt. The role of Akt in cytokine production and helper T (Th) cell differentiation remains obscure. In this study, we found that enforced expression of the constitutively active form (E40K) of Akt rendered CD4(+) T cells activated. Wild-type of Akt and E40K promoted Th1 cell differentiation in C57BL/6-derived and Th1-polarized BALB/c-derived CD4(+) T cells, while both promoted Th2 cell differentiation in BALB/c-derived and Th2-polarized C57BL/6 CD4(+) T cells. E40K also facilitated Th1 differentiation in CD4(+) T cells from IL-4-deficient mice with the BALB/c background. E40K up-regulated expression of NF-AT and c-Myb, which may be related to the augmentation of cytokine production by E40K. These findings indicate that the mechanism by which Akt augments cytokine production via CD28 and ICOS is Th cell type-specific and reflects the intracellular status affected by the cytokine milieu. We conclude that Akt is a neutral amplifier of T cell activation and Th differentiation.     

Synthesis and odor description of both enantiomers of methyl 4,5-didehydrojasmonate, a component of jasmin absolute

Synthesis of both enantiomers of methyl 4,5-didehydrojasmonate (1, Delta(4,5)-MJA; >99.8% ee), a constituent of jasmin absolute, established the absolute configuration of the natural product, and their odor quality was evaluated. The fragrance of the natural (3S,7R)-enantiomer (a fresh natural, sweet floral fruity odor, reminiscent of Jasmin and Ylang Ylang flower, more intensive and tenacious) was superior to that of the unnatural (3R,7S)-enantiomer (a floral green odor with slight metallic green aspect, less intensive than the natural form) and the racemate (green-floral note, having weak and less volume than methyl jasmonate). Odor difference between natural and unnatural enantiomers of methyl jasmonate (2) is also reported.     

Relationship between the bloom of Noctiluca scintillans and environmental factors in the coastal waters of Sagami Bay, Japan

In order to study the mechanism of the bloom formation of Noctilucascintillans, the relationship between the variation in the abundanceof N. scintillans and environmental factors was examined inthe coastal waters of Sagami Bay, Japan. Hydrographic (temperature,salinity, water stability), biological (chlorophyll a concentration,zooplankton biomass) and meteorological (rainfall, wind velocity,wind direction) factors were investigated from 1997 to 2004.For all years, the abundance of N. scintillans started to increasefrom March and reached a maximum in spring between April andMay. The abundance in 1997 and 2000 was relatively high comparedto the other years while the abundance in 1998 and 2004 wasrelatively low. A stepwise multiple linear regression analysisshowed that the wind direction and rainfall were significantlycorrelated with the variation in the abundance of N. scintillans.Our results suggest that bloom formation can be separated intoa three-step process: (i) initial increase in the abundanceof N. scintillans attributed to an increase in optimum hydrographicand biological factors, (ii) N. scintillans is then accumulatedby convergence of seawater by the factors of low rainfall andwind and (iii) swarmer-effects suggested enhanced bloom formation.Accumulation is considered to be a key trigger in this processof the formation of large-scale blooms. This paper was presented at Plankton Symposium III, held atFiguera da Foz, Portugal between 17 and 20 March 2005, underthe auspices of the University of Coimbra and the Universityof Aveiro, and coordinated by Mário Jorge Pereira andUlisses M. Azeiteiro.     

The medaka rs-3 locus required for scale development encodes ectodysplasin-A receptor

The bodies of most teleost fish species are covered with specialized subepithelial structures known as scales. The scale is an epithelial appendage that differentiates from the dermal mesenchyme. Mammals, on the other hand, have no scales, but instead their bodies are covered with hair. Although their appearances are quite different, scales and hair can be considered structurally similar in that both of them are epithelial appendages distributed over the body surface in an orderly pattern. This analogy suggests that they may have the same evolutionary origin. But, to date, no molecular evidence has been presented that links scales and hair. A mutation at the rs-3 locus of medaka (Oryzias latipes) leads to almost complete loss of scales. We demonstrated that the rs-3 locus encodes ectodysplasin-A receptor (EDAR), which is required for the initiation of hair development in mammals. We identified a novel transposon inserted in the first intron of EDAR, which causes aberrant splicing. This work shows that EDAR is required for scale development in fish and suggests that it is an evolutionarily conserved molecule that is required for the development of epithelial appendages in vertebrates.     

Rapid detection of blaIMP-6 by amplification refractory mutation system

Klebsiella pneumoniae resistant to almost all ß-lactams except imipenem designated as ISMRK (imipenem-susceptible meropenem-resistant Klebsiella) is emerging in Japan. All ISMRK carries bla_IMP-6 which differs from bla_IMP-1 by only a single nucleotide at position 640. We devised a rapid detection system of bla_IMP-6 by using ARMS PCR.     

Phosphorylation of α-synuclein protein at Ser-129 reduces neuronal dysfunction by lowering its membrane binding property in Caenorhabditis elegans

α-Synuclein is causative for autosomal dominant familial Parkinson disease and dementia with Lewy bodies, and the phosphorylation of α-synuclein at residue Ser-129 is a key posttranslational modification detected in Parkinson disease/dementia with Lewy bodies lesions. However, the role of Ser-129 phosphorylation on the pathogenesis of Parkinson disease/dementia with Lewy bodies remains unclear. Here we investigated the neurotoxicity of Ser-129-substituted α-synuclein in the transgenic Caenorhabditis elegans (Tg worm) model of synucleinopathy. Tg worms pan-neuronally overexpressing nonphosphorylatable (S129A) α-synuclein showed severe defects including motor dysfunction, growth retardation, and synaptic abnormalities. In contrast, Tg worms expressing phosphorylation mimic (S129D) α-synuclein exhibited nearly normal phenotypes. Biochemical fractionation revealed that the level of membrane-bound α-synuclein was significantly increased in S129A-α-synuclein Tg worms, whereas S129D- as well as A30P-α-synuclein displayed lower membrane binding properties. Furthermore, A30P/S129A double mutant α-synuclein did not cause neuronal dysfunction and displayed low membrane binding property. In human neuroblastoma SH-SY5Y cells, localization of S129A-α-synuclein to membranes was significantly increased. Finally, gene expression profiling of S129A-Tg worms revealed a dramatic up-regulation of Daf-16/FOXO pathway genes, which likely act against the dysfunction caused by S129A-α-synuclein. These results imply a role of Ser-129 phosphorylation of α-synuclein in the attenuation of α-synuclein-induced neuronal dysfunction and downstream stress response by lowering the membrane binding property.