This work is concerned with modeling the key interrelated biochemical reactions involved in initiating and inhibiting pacemaking activity in the mammalian sinoatrial node. A detailed model involving ...G-proteins was developed to better represent the activation pathway for adenylate cyclase. Concentration profiles of an activated G-protein complex alpha(T)C were established as a function of the membrane bound calcium calmodulin concentration. A previously developed model used to establish temporal profiles of cAMP was improved using the G-protein effects through the alpha(T)C functionality. Methods were also developed to model inhibition of G-protein by acetylcholine. Analytical solutions were developed to predict acetylcholine concentration profiles as a function of diffusion parameter and duration of acetylcholine pulses. The model was used to demonstrate suppression of cAMP by acetylcholine through G-protein pathways. It provides a basis for a tool to quantify key biochemical species during stimulation and inhibition of sinoatrial node pacemaking. A stability analysis of the model equations has potential application in studying the link between the biochemical species concentrations and abnormal effects in sinoatrial node pacemaking.
To elucidate the molecular mechanisms associated with metamorphic phenomenon relating to
Bombyx mori, an important organism in the sericulture industry, we identified genes that are expressed in the ...different developmental stages, specifically the embryonic (ES) and larval (LS) stages of
B. mori. Of 8230 high-quality ESTs from two full-length enriched cDNA libraries, 3442 of the ES ESTs were coalesced into 1325 clusters, while 4788 were coalesced into 927 clusters. The functional classification of these ESTs based on Gene Ontology showed that the types of genes that are associated with oxidoreductase activity, enzyme inhibition, and larval development were highly observed in LS, whereas the types of genes that are involved in nucleotide binding, enzyme activity, and protein transport activity were highly observed in ES. In addition, when the gene expression profile between ES and LS was examined by counting the EST frequencies in each library, 69 genes were identified as being either up- or down-regulated in the larval stage compared to the embryonic stage (
P
>
0.99) and this was confirmed by semi-quantitative RT-PCR. The results show that genes involved in proteolysis and peptidolysis, and lipid and carbohydrate metabolism were dramatically up-regulated in LS, while those related to protein metabolism, DNA/RNA, and coenzymes were highly down-expressed. In particular, a GO analysis of these genes revealed that genes that are involved in hydrolase activity were observed to be highly expressed in amount as well as diversity in LS, while those involved in nucleic acid binding were highly expressed in ES. These data may contribute to elucidating genetic events that distinguish the developmental stage and to our understanding of the metamorphosis of
B. mori.
We report the isolation of activating transcription factor of chaperone (ATFC), a novel cDNA from
Bombyx mori BM5 cells that encodes a putative transducer of endoplasmic reticulum (ER) stress. The ...236 amino acids of ATFC include both a basic region and a leucine zipper at the C-terminus, in contrast to Hac1p of yeast which features these structures at its N-terminus. ATFC expression was strongly up-regulated by ER stress. ATFC could specifically bind to the unfolded protein response element. BM5 cells transfected with ATFC cDNA displayed enhanced ER chaperone expression in response to ER stress. These results indicate that ATFC encodes a putative transducer of ER stress.
Effect of envenomation of ectoparasitoid
Bracon hebetor was determined on the heart rate and the expression of
shsp,
hsc70 and
hsp90 of the lepidopteran host
Plodia interpunctella. Envenomated host ...larvae were promptly immobilized but heart rate was not changed until 4 days after envenomation. Northern hybridization showed that each
hsp gene was differentially influenced by envenomation: continued high induction of
shsp, gradual strong induction of
hsc70, but no induction of
hsp90. Our results suggest that upregulation of both
shsp and
hsc70 may produce potent factors that have important roles in the mechanism of host–parasitoid relationship.
Individuals of the wild silkworm, Bombyx mandarina, collected in South Korea (Taegu City) and Japan (Tsushima Islands and Fukuoka City) had the chromosome number of 2n = 54, while those collected in ...China (Hangzhou City) had the chromosome number of 2n = 56. Analysis by PCR (polymerase chain reaction) showed that the 66-bp-long retroposon-like insertion known in the arylphorin gene was present in the B. mandarina specimens with 2n = 54, but not in those with 2n = 56. Thus, dimorphism in the chromosome number coincided with the occurrence of the insertion. It is likely that the boundary dividing the two geographic B. mandarina populations lies somewhere in the northern part of the Korean Peninsula.
Gap junctions are clusters of intercellular channels that are associated with embryonic development and neural signaling. Innexins, invertebrate gap junction proteins, have been identified in
...Drosophila and
Caenorhabditis. Here, we report the isolation and characterization of two novel members of the insect innexin family,
Bm inx2 and
Bm inx4, from embryos of the silkworm,
Bombyx mori, during the germ-band formation stage.
Bm inx2 is a single copy gene with one exon, while
Bm inx4 is a single copy gene with four exons and three introns. The predicted proteins show structural similarities with other innexin family members, including four transmembrane (TM) domains, two extracellular loops (ELs), one cytoplasmic loop (CL), and typical conserved amino acids.
Bm inx2 is phylogenetically orthologous to the other insect
inx2 genes, but
Bm inx4 is not orthologous to any known innexin including
Dm inx4. Interestingly, Northern blotting and in situ hybridization showed that
Bm inx2 was variously expressed across all developmental stages and in various tissues, with high expression seen in the nervous system at the time of embryogenesis. In contrast,
Bm inx4 was transiently expressed at the germ-band formation stage of embryogenesis, and was specifically expressed in the ovary and testis during the larval and pupal stages. The isolation and characterization of these novel genes should form the basis for further study of the functional events that occur during development and neuronal communication in
B. mori.
Using a finite-temperature path integral Monte Carlo simulation (PIMC) method and finite-size scaling, we have investigated the interaction-induced shift of the phase-transition temperature for ...Bose-Einstein condensation of homogeneous weakly interacting Bose gases in three dimensions, which is given by a proposed analytical expression T{sub c}=T{sub c}{sup 0}{l_brace}1+c{sub 1}an{sup 1/3}+c{sub 2}{sup '} ln(an{sup 1/3})+c{sub 2}a{sup 2}n{sup 2/3}+O(a{sup 3}n){r_brace}, where T{sub c}{sup 0} is the critical temperature for an ideal gas, a is the s-wave scattering length, and n is the number density. We have used smaller number densities and more time slices than in the previous PIMC simulations Gruter et al., Phys. Rev. Lett. 79, 3549 (1997) in order to understand the difference in the value of the coefficient c{sub 1} between their results and the (apparently) other reliable results in the literature. Our results show that {l_brace}(T{sub c}-T{sub c}{sup 0})/T{sub c}{sup 0}{r_brace}/(an{sup 1/3}) depends strongly on the interaction strength an{sup 1/3} while the previous PIMC results are considerably flatter and smaller than our results. We obtain c{sub 1}=1.32{+-}0.14, in agreement with results from recent Monte Carlo methods of three-dimensional O(2) scalar {phi}{sup 4} field theory and variational perturbation theory.
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