A Model of the Intracellular Response of an Olfactory Neuron in Caenorhabditis elegans to Odor Stimulation

We developed a mathematical model of a hypothetical neuronal signal transduction pathway to better understand olfactory perception in Caenorhabditis elegans. This worm has only three pairs of olfactory receptor neurons. Intracellular Ca(2+) decreases in one pair of olfactory neurons in C. elegans, the AWC neurons, following application of an attractive odor and there is a transient increase in intracellular Ca(2+) following removal of odor. The magnitude of this increase is positively correlated with the duration of odor stimulation. Additionally, this Ca(2+) transient is induced by a cGMP second messenger system. We identified likely candidates for the signal transduction molecules functioning in this system based on available gene expression and physiological data from AWCs. Our model incorporated a G-protein-coupled odor receptor, a G-protein, a guanylate cyclase as the G-protein effector, and a single phosphodiesterase. Additionally, a cyclic-nucleotide-gated ion channel and a voltage-gated ion channel that mediated calcium influx were incorporated into the model. We posited that, upon odor stimulation, guanylate cyclase was suppressed by the G-protein and that, upon cessation of the stimulus, the G-protein-induced suppression ceased and cGMP synthesis was restored. A key element of our model was a Ca(2+)-dependent negative feedback loop that ensured that the calcium increases were transient. Two guanylate cyclase-activating proteins acted on the effector guanylate cyclase to negatively regulate cGMP signaling and the resulting calcium influx. Our model was able to closely replicate in silico three important features of the calcium dynamics of AWCs. Specifically, in our simulations, [Ca(2+)] increased rapidly and reached its peak within 10 s after the odor stimulus was removed, peak [Ca(2+)] increased with longer odor exposure, and [Ca(2+)] decreased during a second stimulus that closely followed an initial stimulus. However, application of random background signal ('noise') showed that certain components of the pathway were particularly sensitive to this noise.     

Memory immune responses against pandemic (H1N1) 2009 influenza virus induced by a whole particle vaccine in cynomolgus monkeys carrying Mafa-A1*052:02

We made an H1N1 vaccine candidate from a virus library consisting of 144 (?=?16 HA×9 NA) non-pathogenic influenza A viruses and examined its protective effects against a pandemic (2009) H1N1 strain using immunologically na?ve cynomolgus macaques to exclude preexisting immunity and to employ a preclinical study since preexisting immunity in humans previously vaccinated or infected with influenza virus might make comparison of vaccine efficacy difficult. Furthermore, macaques carrying a major histocompatibility complex class I molecule, Mafa-A1*052:02, were used to analyze peptide-specific CD8(+) T cell responses. Sera of macaques immunized with an inactivated whole particle formulation without addition of an adjuvant showed higher neutralization titers against the vaccine strain A/Hokkaido/2/1981 (H1N1) than did sera of macaques immunized with a split formulation. Neutralization activities against the pandemic strain A/Narita/1/2009 (H1N1) in sera of macaques immunized twice with the split vaccine reached levels similar to those in sera of macaques immunized once with the whole particle vaccine. After inoculation with the pandemic virus, the virus was detected in nasal samples of unvaccinated macaques for 6 days after infection and for 2.67 days and 5.33 days on average in macaques vaccinated with the whole particle vaccine and the split vaccine, respectively. After the challenge infection, recall neutralizing antibody responses against the pandemic virus and CD8(+) T cell responses specific for nucleoprotein peptide NP262-270 bound to Mafa-A1*052:02 in macaques vaccinated with the whole particle vaccine were observed more promptly or more vigorously than those in macaques vaccinated with the split vaccine. These findings demonstrated that the vaccine derived from our virus library was effective for pandemic virus infection in macaques and that the whole particle vaccine conferred more effective memory and broader cross-reactive immune responses to macaques against pandemic influenza virus infection than did the split vaccine.     

Investigation of the electronic and dynamic properties of sodium and caesium exchanged zeolite by MO and MD simulations

For the pyrochemical reprocessing of spent metallic fuels in molten salt baths it is of importance to investigate the electronic and dynamic properties of the negative elements like Cs in aluminosilicates framework. The molecular orbital simulation has been performed on three types of clusters and 4A-zeolite frameworks with exchangeable alkali-ions containing as significant fission products in order to estimate the geometry optimization, the vibrational frequency factors and the electric densities, etc. These quantum chemical results enable us to conclude that the most stable structure is consistent with the X-ray results. Moreover, the obtained infrared spectrum was reproduced by the experimental results. Furthermore, the molecular dynamics simulation for Na-A and Cs-A zeolites has been carried out at 673 K in order to investigate the dynamics of Na⁺ and Cs⁺ions in Na-A and Cs-A zeolite frameworks. These results revealed that Na I ion in β-cage was more stable than the other Na ions in Na-A zeolite and Cs I ion in α-cage was maintained stability in Cs-A zeolite in consideration of the self-diffusion coefficients.     

Interaction of Yeast Phosphoglyceromutase with Nucleotides

Moderate cell growth occurred after a long lag phase of about 100 hr when oxygen-sensitive hydrogen bacterium N34 was cultivated chemoautotrophically under 40% O₂. A decrease in cell growth or viable count was not observed during the lag phase. These cells grown under 40 % O₂ were oxygen-resistant because when used as inocula for fresh 40 % O₂-culture, the growth lag period was less than 10 hr. Nine oxygen-sensitive colonies developed from a single oxygen-sensitive cell respectively. When these colonies were inoculated into 40% O₂-culture, they showed an almost equal lag period and growth rate. These results suggest that cell growth in 40% O₂-culture inoculated with oxygen-sensitive strain N34 occurred not by selection of oxygen-resistant variants which might preexist but by adaptation of very oxygen-sensitive cells to high oxygen tension. Oxygen-resistance thus developed was maintained after successive subcultures under 10% O₂ for more than one year.     

Fractionation and Characterization of 9 Subcomponents of Bovine κ-Casein A

κ-casein A was fractionated into 9 subcomponents, all of which were identified as κ-casein from immunological analyses. The microheterogeneity of the subcomponents was explained by stepwise increase of their carbohydrate contents (0~4mol/mol of GalNAc, and 0~8mol/mol of NANA). The micelle-stabilizing ability of κ-casein subcomponents increased with the increase of their carbohydrate contents: the carbohydrate rich subcomponent 7 possessed twice the stabilizing ability of the carbohydrate free subcomponent 1. The sensitivity of synthetic casein micelle composed of κ-casein subcomponents and α_sl-casein to the wheat germ lectin-induced aggregation also increased with the increase of their NANA contents.     

Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.     

The status of acrosomal caps of hamster spermatozoa immediately before fertilization in vivo

Adult female golden hamsters were induced to superovulate. When they were mated several hours prior to ovulation or artificially inseminated about the time of ovulation, nearly 100% of their eggs were subsequently fertilized monospermically. During the progression of fertilization when the eggs were still surrounded by compact cumulus oophorus, the contents of the ampullary region of the oviducts were collected and spermatozoa moving in the ampullary fluid, within the cumulus and on/in the zonae pellucidae of unfertilized eggs, were examined by light and electron microscopy to evaluate the status of their acrosomal caps. Most spermatozoa swimming in the ampullary fluid had apparently intact acrosomal caps, while the vast majority moving within the cumulus had distinctly modified acrosomal caps. Most spermatozoa that had passed through the cumulus and reached the zona surfaces had remnants of their acrosomal caps (“acrosomal ghosts”). When the ghosts were present around the sperm heads on the zona, the heads pivoted about a point roughly corresponding to the places where the ghosts were located. The ghosts seemed to firmly attach to the zona surfaces, then were split open by the sperm heads and left behind as the sperm heads advanced into the zona. A few spermatozoa on the zona surfaces had no acrosomal ghosts (at least not detectable by light microscopy). In this case, the sperm head pivoted about either the inner acrosomal membrane or the equatorial segment of the acrosome. In no instance were spermatozoa with intact acrosomal caps found on zona surfaces. We infer from these observations that most spermatozoa in vivo initiate their acrosome reactions while they are advancing through the cumulus. When they arrive at the zona surfaces, acrosomal ghosts are generally present on the sperm heads. These ghosts appear to hold sperm heads to zona surfaces as well as to restrict the direction of advancement of sperm head through the zona. In a minority of cases, ghostless spermatozoa reach the zona surfaces. As these spermatozoa appear to be able to penetrate the zona successfully, structures other than the acrosomal ghost (ie, the inner acrosomal membrane and the plasma membrane over the equatorial segment of the acrosome) may also attach to zona surfaces before spermatozoa penetrate into the zona.     

Reversible Dissociation of Crystalline Yeast Phosphoglyceric Acid Mutase in Alkali

The structure of crystalline yeast phosphoglyceric acid mutase has been investigated by sedimentation-velocity and equilibrium measurements, optical rotatory dispersion measurements and viscometry. The data indicate that this enzyme is a globular, compact and highly organized protein with a low helix content. The native structure remains unchanged at pH 10.5. Dissociation of the enzyme into subunits has been observed at pH values of 11.5 and above. From optical rotatory dispersion measurements, it is found that the enzyme loses a large part of its organized conformation when it dissociates in alkaline solution. On neutralization, the alkali-treated enzyme regains its activity. The ability to regain the enzyme activity is gradually lowered with the increase of pH value to be incubated and with time of exposure. Inactivation at pH 13.0 is almost irreversible. However, the reversibility of the inactivation at pH 13.0 is appreciably enhanced by the presence of phosphate compounds in the reactivation system. Particulary, it is found that presence of substrates or the coenzyme is effective for considerable improvement of the reversibility. Molecular weight analyses by ultracentrifugation indicate that subunits have approximately equal molecular weights and that the native enzyme is consisted of four polypeptide chains.     

Fishes ofNeoclinus from Okinawa with notes on the traits of their habitats

All the fish specimens ofNeoclinus bryope species complex collected from Okinawa Island including the 2 specimens already reported asN. bryope are referable toN. okazakii. Neoclinus nudus, hitherto known only from Taiwan, is newly recorded from Okinawa Island. These two species are redescribed on the basis of the specimens from Okinawa Island. The specimens from Okinawa are compared with those from Shirahama in the case ofN. okazakii and with specimens from Taiwan as well asN. lacunicola andN. toshimaensis specimens from Shirahama in the case ofN. nudus. The habitats ofN. okazakii andN. nudus are clearly separated in the waters of Heshikiya, Okinawa Island and the habitat of either species is rather particular in that it is exceptionally unoccupied by blenniids which are flourishing in the coastal waters of the Okinawa Islands.