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71.
T. Abiko  H. Sekino 《Amino acids》1993,4(1-2):35-43
Summary A 16-residue peptide was isolated from filtrate of uremic patients with carbohydrate intolerance by ultrafiltration with an Amicon Centriflo DM-5 membrane, followed by gel-filtration on Sephadex G-50 and Sephadex G-25, droplet countercurrent chromatography and high performance liquid chromatography. The hexadecapeptide thus obtained was identical as the entire amino acid sequence of-endorphin by amino acid analysis, application of the Edman degradation analysis and measurement of physical constants and analytical data of the synthetic hexadecapeptide. This result seems to suggest that an accumulation of-endorphin in uremic patients might cause carbohydrate intolerance.  相似文献   
72.
Sekino M  Hara M 《Genetics》2007,175(2):945-958
This study presents linkage maps for the Pacific abalone (Haliotis discus hannai) based on 180 microsatellite DNA markers. Linkage mapping was performed using three F1 outbred families, and a composite linkage map for each sex was generated by incorporating map information from the multiple families. A total of 160 markers are placed on the consolidated female map and 167 markers on the male map. The numbers of linkage groups in the composite female and male maps are 19 and 18, respectively; however, by aligning the two maps, 18 linkage groups are formed, which are consistent with the haploid chromosome number of H. discus hannai. The female map spans 888.1 cM (Kosambi) with an average spacing of 6.3 cM; the male map spans 702.4 cM with an average spacing of 4.7 cM. However, we encountered several linkage groups that show a high level of heterogeneity in recombination rate between families even within the same sex, which reduces the precision of the consolidated maps. Nevertheless, we suggest that the composite maps are of significant potential use as a scaffold to further extend the coverage of the H. discus hannai genome with additional markers.  相似文献   
73.
The influence of the size distribution of phytoplankton on changes in the planktonic food web structures with eutrophication was examined using natural planktonic communities in two world-famous lakes: Lake Baikal and Lake Biwa. The size distribution of phytoplankton and the ratio of heterotrophic to autotrophic biomass (H/A ratio), indicating the balance between primary production and its consumption, were investigated in the lakes of different trophic status. The results revealed that microphytoplankton (>20μm) in mesotrophic Lake Biwa, and picophytoplankton (<2μm) or nanophytoplankton (2–20μm) in oligotrophic Lake Baikal, comprised the highest proportion of the total phytoplankton biomass. The H/A ratio was lower in Lake Biwa (<1) than in Lake Baikal (>1). The low H/A ratio in Lake Biwa appeared to be the consequence of the lack of consumption of the more abundant microphytoplankton, which were inferior competitors in nutrient uptake under oligotrophic conditions but less vulnerable to grazing. As a result, unconsumed microphytoplankton accumulated in the water column, decreasing the H/A ratio in Lake Biwa. Our results showed that food web structure and energy flow in planktonic communities were greatly influenced by the size distribution of phytoplankton, in conjunction with bottom-up (nutrient uptake) and top-down (grazing) effects at the trophic level of primary producers.  相似文献   
74.
In this review we consider the multiple functions of developmentally regulated brain protein (drebrin), an actin-binding protein, in the formation of cellular polarity in different cell types. Drebrin has a well-established role in the morphogenesis, patterning and maintenance of dendritic spines in neurons. We have recently shown that drebrin also stabilizes Connexin-43 containing gap junctions at the plasma membrane. The latest literature and our own data suggest that drebrin may be broadly involved in shaping cell processes and in the formation of stabilized plasma membrane domains, an effect that is likely to be of crucial significance for formation of cell polarity in both neuronal and non-neuronal types. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
75.
The effect of nucleotide binding on the structure of the F(1)-ATPase beta subunit from thermophilic bacillus PS-3 (TF(1)beta) was investigated by monitoring the NMR signals of the 12 tyrosine residues. The 3,5-proton resonances of 12 tyrosine residues could be observed for the specifically deuterated beta subunit. The assignment of 3,5-proton resonances of all of the tyrosine residues was accomplished using 14 mutant proteins, in each of which one or two tyrosine residues were replaced by phenylalanine. Binding of Mg. ATP induced an upfield shift of Tyr(341) resonance, suggesting that their aromatic rings are stacked to each other. Besides Tyr(341), the signal shift observed on Mg.ATP binding was restricted to the resonances of Tyr(148), Tyr(199), Tyr(238), and Tyr(307), suggesting that Mg.ATP induces a conformational change in the hinge region. This can be correlated to the change from the open to closed conformations as implicated in the crystal structure. Mg.ADP induced a similar but distinctly different conformational change. Therefore, the intrinsic conformational change in the beta subunit induced by the nucleotide binding is proposed to be one of the essential driving forces for the F(1) rotation. Reconstitution experiments showed that Tyr(277), one of the four conserved tyrosines, is essential to the formation of the alpha(3)beta(3)gamma complex.  相似文献   
76.
The mechanism for utilization of dissolved inorganic carbon(DIC) was investigated in the marine unicellular calcareousalga Emiliania huxleyi, grown with constant aeration. The apparentK0.5 (DIC), the concentration of DIC which attains one-halfof the maximum velocity of apparent photosynthesis, for photosyntheticevolution of O2, measured under saturating light, was 5.5 mM(55 µM for CO2) at pH 8.0 and 25°C. The value of K0.5was not affected by inhibitors of carbonic anhydrase (CA), andan electrometric assay of CA showed that the enzyme was notinvolved in photosynthesis in this alga. The rate of photosyntheticfixation of 14C-DIC into acid-stable products was about 20 timeshigher than that into CaCO3, irrespective of the external concentrationof DIC. In short-term experiments, 14C-DIC was usually incorporatedinto the internal pool of DIC (IIC) to concentrations up to13 to 16 times higher than that of the external DIC. CO2 addedexternally was utilized mainly for fixation of CO2 and accumulationof IIC. By contrast, HCO-3 was utilized mainly for productionof CaCO3 and accumulation of IIC. Incorporation of 14C intoIIC was partially suppressed by DCMU or in darkness but itstransfer to CaCO3 was unaffected. These results suggest thataccumulation of IIC in this alga, even under ordinary circumstances,is only partially responsible for increasing the efficiencyof utilization of DIC by photosynthetic fixation but may bemost useful for the production of CaCO3. (Hydroxyethylidene) bisphosphonic acid, an inhibitor of thegrowth of CaCO3 crystals, completely suppressed production ofCaCO3. The accumulation of IIC was also partially suppressed,but photosynthetic fixation of CO2 was enhanced. In a pulse-chaseexperiment with 14CDIC, 14C incorporated into IIC and CaCO3in darkness was transferred to acid-stable products of photosynthesisin the light. These results suggest that 14C-DIC in IIC andpre-formed CaCO3 may be useful sources of carbon for fixationof CO2. (Received July 2, 1993; Accepted January 10, 1994)  相似文献   
77.
Genetic variations within and between nine hatchery stocks and seven natural populations of abalone including Ezo-abalone (Haliotis discus hannai) and Kuro-abalone (H. d. discus) were assayed with nine microsatellite markers. Marked reductions of genetic variability in the hatchery stocks were recognized in the allelic diversity and mean heterozygosity compared with the natural populations. Thirteen of 16 significant HWE deviations in hatchery stocks revealed heterozygotes excess, while all natural populations did not show such a tendency. Highly significant F ST values were observed for all cases between the hatchery stocks, and between the hatchery stocks and natural populations. Genetic distance (D A) between each hatchery stock and the geographically proximal population (mean ± SD, 0.108 ± 0.035) were similar to those estimated for between the natural Ezo-abalone and Kuro-abalone (0.101 ± 0.021). The self-assignment test, which allocated individuals to their own stock with a high success rate, provided evidence of solid genetic differences among the nine hatchery stocks. These results suggests that the allelic composition and diversity in the natural populations was not necessarily reflected in the hatchery stocks owing to population bottleneck and genetic drift through seedling process, and thus the seedling and stocking practice of these hatchery stocks should take much notice of the results to conserve the genetic diversity of natural populations.  相似文献   
78.
Epidemiological studies have suggested that cigarette smoking is related to increased breast cancer risk. Nicotine is most likely related to the risk in cigarette smoking. However, the mechanisms by which nicotine promotes cancer development are not fully understood. It has recently been suggested that development of breast cancer are originated from cancer stem cells, which are a minor population of breast cancer. In the present study, we investigated the effects of nicotine on the population of cancer stem cells in MCF-7 human breast cancer cells, using flow cytometry with a cancer stem cell marker aldehyde dehydrogenase (ALDH). We found that nicotine increased ALDH-positive cell population in a dose-dependent manner. We further demonstrated that a PKC-Notch pathway is involved in the effect of nicotine. In addition, the effect of nicotine was blocked by treatment with the α7 subunit-selective antagonist of nicotinic acetylcholine receptors (nAChR) α-Bungarotoxin. These data suggest that nicotine increases the stem cell population via α7-nAChR and the PKC-Notch dependent pathway in MCF-7 cells. These findings reveal a relationship between nicotine and the cancer stem cells in human breast cancer.  相似文献   
79.
Two deacetyl-thymosin alpha(1) analogues containing Phe (4Br) or D-Phe (4Br) residue-[D-Phe(4Br)(21)]deacetyl-thymosin alpha(1) and [Phe(4Br)(21)]deacetyl-thymosin alpha(1), respectively-were synthesized by the manual solid-phase method and their immunological effects on the low E-rosette-forming lymphocytes of uraemic patients were examined. One of the synthetic analogues, [Phe(4Br)(21)deacetyl-thymosin alpha(1), demonstrated a restorative effect on the low E-rosette-forming lymphocytes of uraemic patients, which was stronger than that of deacetyl-thymosin alpha(1), but the other analogue, [D-Phe(4Br)(21)]deacetyl-thymosin alpha(1), showed no restorative effect under the same conditions.  相似文献   
80.
The utilization of inorganic carbon and role of the coccolithswere investigated in intact cells and protoplasts of a marineunicellular calcareous alga, Emiliania huxleyi. Protoplastswith high photosynthetic activity were obtained by artificialdecalcification with 50 mM MES-NaOH (pH5.5). (1) The kineticsof the photosynthetic evolution of O2 at various concentrationsof externally added NaHCO3 were the same for intact cells andprotoplasts, indicating that the kinetic properties with respectto dissolved inorganic carbon (DIC) were not affected by thepresence or absence of the coccoliths on the cell surface. Double-reciprocalplots and plots of the concentration of substrate divided byvelocity (s/v) against the concentration of substrate (s) werebiphasic in the case of both intact cells and protoplasts. TheCO2-utilization reaction was, therefore, considered to involvetwo processes with different values of Km and Vmax. From thekinetic analyses, Km and Vmax [µmoles O2 (ml PCV)–1h–1] were deduced to be 92 µM and 76.3 for a "low-Km"reaction and 4.1 mM and 252 for a "high-Km" reaction, respectively.(2) In short-term (40-min) experiments, time courses of thetotal uptake of 14C-DIC and the incorporation of 14C into acid-stableproducts of photosynthesis and the internal pool of DIC, determinedas acid-labile compounds, under CO2-limiting conditions (80µM) were very similar for intact cells and protoplasts.However, incorporation of 14C into CaCO3 apparently occurredmore slowly in protoplasts than in intact cells. (3) In longterm (24-h) experiments, patterns of incorporation of 14C werealmost same for intact cells and protoplasts, with the exceptionthat the amount of 14C incorporated into CaCO3 was much smallerin the former than the latter. The production of Ca14CO3 increasedduring the course of 10 h after a 4-h lag. However, after 10h the level of Ca14CCO3 started to decrease. The decrease wasaccompanied by an increase in 14C in the products of photosynthesis,suggesting that CaCO3 was reutilized for the photosyntheticfixation of CO2 and, therefore, that the coccoliths functionas sites of storage of DIC. However, the internal level of DICremained at the same level even after the supply of externalDIC has been almost completely depleted. (Received July 25, 1995; Accepted December 11, 1995)  相似文献   
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