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991.
992.
A simple model for the simultaneous passive membrane transport and bioconversion of a drug, which may be a weak electrolyte or a neutral molecule, is mathematically described. It includes an aqueous diffusion layer and an operational aqueous pore pathway. The applicability of the model is shown for the in situ rat intestinal transport of prostaglandin F2a. 相似文献
993.
Takuya Chiba Junjie Yao Yoshikazu Higami Isao Shimokawa Masanori Hosokawa Keiichi Higuchi 《Mammalian genome》2007,18(2):105-112
Senescence-accelerated mouse (SAM) strains constitute a model of accelerated senescence coupled with a short lifespan and
the early development of various age-related disorders. To identify differential gene expression in testes between senescence-accelerated
SAMP1 and control SAMR1 mice, we performed suppression subtractive hybridization. We observed that the expression of three
genes related to cell proliferation (myosin regulatory light chain B, aldolase 1A isoform, and cytochrome c oxidase subunit
VIc) were upregulated and four genes implicated in spermatogenesis were downregulated in SAMP1 mice. Asb-8, a member of ankyrin
repeat-containing proteins, was abundantly expressed in the testes and downregulated in SAMP1. The other three downregulated
genes (germ cell-specific gene 1, T-complex polypeptide 1b, and activator of cAMP responsive element modulator in testis)
have been reported to regulate late-stage spermatogenesis. These gene expression profiles might explain the findings of early
testicular maturation and rapid decline in the ability to produce spermatozoa with advancing age in SAMP1 mice. 相似文献
994.
Yuya Kumagai Kayoko KawakamiMisugi Uraji Tadashi Hatanaka 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(1):301-307
The study aimed to define the key factors involved in the modulation of actinomycete mannanases. We focused on the roles of carbohydrate-binding modules (CBMs) and bivalent ions. To investigate the effects of these factors, two actinomycete mannanase genes were cloned from Streptomyces thermoluteus (StManII) and Streptomyces lividans (SlMan). CBMs fused to mannanase catalytic domains do not affect the thermal stability of the proteins. CBM2 of StManII increased the catalytic efficiency toward soluble-mannan and insoluble-mannan by 25%–36%, and CBM10 of SlMan increased the catalytic efficiency toward soluble-mannan by 40%–50%. Thermal stability of wild-type and mutant enzymes was enhanced by calcium and manganese. Thermal stability of SlMandC was also slightly enhanced by magnesium. These results indicated that bivalent ion-binding site responsible for thermal stability was in the catalytic domains. Thermal stability of mannanase differed in the kinds of bivalent ions. Isothermal titration calorimetry revealed that the catalytic domain of StManII bound bivalent ions with a Ka of 5.39 ± 0.45 × 103–7.56 ± 1.47 × 103 M− 1, and the catalytic domain of SlMan bound bivalent ions with a Ka of 1.06 ± 0.34 × 103–3.86 ± 0.94 × 103 M− 1. The stoichiometry of these bindings was consistent with one bivalent ion-binding site per molecule of enzyme. Circular dichroism spectrum revealed that the presence of bivalent ions induced changes in the secondary structures of the enzymes. The binding of certain bivalent ion responsible for thermal stability was accompanied by a different conformational change by each bivalent ion. Actinomycete mannanases belong to GHF5 which contained various hemicellulases; therefore, the information obtained from mannanases applies to the other enzymes. 相似文献
995.
Kouichi Kuroda Ken Matsui Shinsuke Higuchi Atsushi Kotaka Hiroshi Sahara Yoji Hata Mitsuyoshi Ueda 《Applied microbiology and biotechnology》2009,82(4):713-719
Vector engineering and gene disruption in host cells were attempted for the enhancement of α-agglutinin-based display of proteins
on the cell surface in yeast. To evaluate the display efficiency by flow cytometric analysis, DsRed-monomer fused with FLAG-tag
was displayed and immunostained as a model protein. The use of leu2-d in the expression vector resulted in the enhanced efficiency and ratio of the accessible display of proteins. Moreover, the
amount of displayed proteins in SED1-disrupted cells increased particularly during the stationary growth phase. The combination of these improvements resulted
in the quantitatively enhanced accessible display of DsRed-monomer on the yeast cell surface. The improved yeast display system
would be useful in a wider range of its applications in biotechnology. 相似文献
996.
997.
998.
Classic theories suggest that central serotonergic neurons are involved in the behavioral inhibition that is associated with
the prediction of negative rewards or punishment. Failed behavioral inhibition can cause impulsive behaviors. However, the
behavioral inhibition that results from predicting punishment is not sufficient to explain some forms of impulsive behavior.
In this article, we propose that the forebrain serotonergic system is involved in “waiting to avoid punishment” for future
punishments and “waiting to obtain reward” for future rewards. Recently, we have found that serotonergic neurons increase
their tonic firing rate when rats await food and water rewards and conditioned reinforcer tones. The rate of tonic firing
during the delay period was significantly higher when rats were waiting for rewards than for tones, and rats were unable to
wait as long for tones as for rewards. These results suggest that increased serotonergic neuronal firing facilitates waiting
behavior when there is the prospect of a forthcoming reward and that serotonergic activation contributes to the patience that
allows rats to wait longer. We propose a working hypothesis to explain how the serotonergic system regulates patience while
waiting for future rewards. 相似文献
999.
1000.
Ekino S Arakawa H Sonoda K Noguchi K Inui S Yokoyama H Kodama Y 《Cell and tissue research》2012,348(3):537-550
The bursa of Fabricius of the chicken is known as a primary lymphoid organ for B-cell development. Morphologically, the origin of IgG-containing cells in the bursa has not been clear until now, because abundant maternal IgG (MIgG) is transported to the chick embryo and distributed to the bursal tissue around hatching. Thus, it has been difficult to find out whether these cells themselves biosynthesize IgG or if they acquire MIgG via attachment to their surface. Our present study employing in situ hybridization clarified that IgG-containing cells in the medulla of bursal follicles did not biosynthesize IgG. To study the role of MIgG in the development of those IgG-containing cells, MIgG-free chicks were established from surgically bursectomized hen (SBx-hen). We found that, on the one hand, deprivation of MIgG from chicks completely inhibited the development of IgG-containing cells in the medulla after hatching. On the other hand, administration of MIgG to MIgG-free chicks recovered the emergence of those cells. In addition, we observed that those cells did not bear a B-cell marker and possessed dendrites with aggregated IgG. These results demonstrate that IgG-containing cells in the medulla are reticular cells that capture aggregated MIgG. Moreover, we show that the isolation of the bursa from environmental stimuli by bursal duct ligation (BDL) suppressed the development of IgG-containing cells after hatching. Thus, it is implied that environmental stimulations play a key role in MIgG aggregations and dendritic distributions of aggregated MIgG in the medulla after hatching. 相似文献