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161.
Modelling and forecasting the fortnightly cladoceran abundance in the Saronikos Gulf (Aegean Sea) 总被引:1,自引:0,他引:1
In the present study, we evaluated the ability of dynamic regressionon the basis of its efficiency to model and forecast the fortnightlyabundance of dadocerans during 19891993 in a coastalregion of the eastern Saronikos Gulf (Aegean Sea). The followingdynamic regression model explained 79% of the variability ofthe transformed cladoceran abundance during the fitting period(January 1989-December 1992): In (cladocerans)t = 0.4314 In(chlorophyll ) 5.9013 In (salinity) + 8.7760 In (temperature)+ 0.2371 In (cladocerans)t20. The model always predictedthe start and the end of the cladoceran season, and forecastedthe cumulative cladoceran abundance during January-December1993 with an absolute percentage error of 14.5%. The positiveeffect of sea temperature and chlorophyll , and the negativeeffect of salinity, on cladoceran abundance are all consistentwith previous studies. The positive relationship between cladoceranabundance at times and t20 approximates the seasonalcycle of their abundance. 相似文献
162.
Estimating Photosynthesis and Concurrent Export Rates in
C3 and C4 Species at Ambient and Elevated
CO2 总被引:2,自引:0,他引:2 下载免费PDF全文
The ability of 21 C3 and C4 monocot and dicot species to rapidly export newly fixed C in the light at both ambient and enriched CO2 levels was compared. Photosynthesis and concurrent export rates were estimated during isotopic equilibrium of the transport sugars using a steady-state 14CO2-labeling procedure. At ambient CO2 photosynthesis and export rates for C3 species were 5 to 15 and 1 to 10 μmol C m−2 s−1, respectively, and 20 to 30 and 15 to 22 μmol C m−2 s−1, respectively, for C4 species. A linear regression plot of export on photosynthesis rate of all species had a correlation coefficient of 0.87. When concurrent export was expressed as a percentage of photosynthesis, several C3 dicots that produced transport sugars other than Suc had high efflux rates relative to photosynthesis, comparable to those of C4 species. At high CO2 photosynthetic and export rates were only slightly altered in C4 species, and photosynthesis increased but export rates did not in all C3 species. The C3 species that had high efflux rates relative to photosynthesis at ambient CO2 exported at rates comparable to those of C4 species on both an absolute basis and as a percentage of photosynthesis. At ambient CO2 there were strong linear relationships between photosynthesis, sugar synthesis, and concurrent export. However, at high CO2 the relationships between photosynthesis and export rate and between sugar synthesis and export rate were not as strong because sugars and starch were accumulated. 相似文献
163.
P. Vain B. Worland M. C. Clarke G. Richard M. Beavis H. Liu A. Kohli M. Leech J. Snape P. Christou H. Atkinson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(2):266-271
We have used a genotype-independent transformation system involving particle gun bombardment of immature embryos to genetically
engineer rice as part of a programme to develop resistance to nematodes. Efficient tissue culture, regeneration, DNA delivery
and selection methodologies have been established for elite African varieties (‘ITA212’, ‘IDSA6’, ‘LAC23’, ‘WAB56-104’). Twenty-five
transformed clones containing genes coding for an engineered cysteine proteinase inhibitor (oryzacystatin-IΔD86, OC-IΔD86), hygromycin resistance (aphIV) and β-glucuronidase (gusA) were recovered from the four varieties. Transformed plants were regenerated from all clones and analysed by PCR, Southern
and western blot. Detectable levels of OC-IΔD86 (up to 0.2% total soluble protein) in plant roots were measured in 12 out of 25 transformed rice lines. This level of
expression resulted in a significant 55% reduction in egg production by Meloidogyne incognita.
Received: 4 August 1997 / Accepted: 22 August 1997 相似文献
164.
Expression and Immunolocalisation of the Snowdrop Lectin,GNA in Transgenic Rice Plants 总被引:4,自引:0,他引:4
Sudhakar Duraialagaraja Fu Xiangdong Stoger Eva Williams Sarah Spence Jacqui Brown David P. Bharathi Muthusamy Gatehouse John A. Christou Paul 《Transgenic research》1998,7(5):371-378
Transgenic rice (Oryza sativa L.) plants generated through particle bombardment expressed high levels of an insecticidal protein (the snowdrop lectin, GNA) directed against sap-sucking insects. Engineered plants expressed GNA either constitutively or in a tissue specific manner, depending on the nature of the promoter used to drive expression of the gene. We used specific antibodies raised against GNA to localize its expression in phloem tissue in plants engineered with the rice sucrose synthase promoter driving GNA expression. We report here molecular, biochemical and immunological analyses for fifteen independently-derived transformants out of more than 200 plants we generated. 相似文献
165.
David C. Spink Carrie L. Hayes Nina R. Young Maro Christou Thomas R. Sutter Colin R. Jefcoate John F. Gierthy 《The Journal of steroid biochemistry and molecular biology》1994,51(5-6):251-258
Rates of microsomal 17β-estradiol (E2) hydroxylation at the C-2, -4, -6, and -15 positions are each induced greater than 10-fold by treating MCF-7 breast cancer cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The TCDD-induced activities at the C-2, -6 and -15 positions have been attributed to cytochrome P450 1A1 (CYP1A1); however, the low Km 4-hydroxylase induced by TCDD appears to be a distinct enzyme. We report here that antibodies to cytochrome P450-EF (mouse CYP1B1) selectivity inhibited the C-4 hydroxylation of E2 catalyzed by microsomes from TCDD-treated MCF-7 cells. Western blots probed with anti-CYP1B antibodies showed the induction of a 52 kDa microsomal protein in response to treatment with TCDD in MCF-7 cells. Western blots of microsomes from HepG2 cells did not show the TCDD-induced 52 kDa protein, and microsomes from TCDD-treated HepG2 cells did not catalyze a low Km hydroxylation of E2 at C-4. Cellular metabolism experiments also showed induction of both the C-2 and -4 hydroxylation pathways in TCDD-treated MCF-7 cells as evidenced by elevated 2- and 4-methoxyestradiol (MeOE2) formation. In contrast, TCDD-treated HepG2 cells showed 2-MeOE2 formation predominantly over 4-MeOE2. Northern blots of RNA isolated from untreated and TCDD-treated cells, when probed with the human CYP1B1 cDNA, showed induction of a 5.2 kb RNA in MCF-7 cells but not in HepG2 cells in response to treatment with TCDD. These results provide additional evidence for the induction by TCDD of a novel E2 4-hydroxylase in MCF-7 cells but not in HepG2 cells and indicate possible endocrine regulatory roles for the newly discovered group of enzymes of the CYP1B subfamily. 相似文献
166.
Evangelos P. Zafeiris George C. Babis Christos P. Zafeiris Efstathios Chronopoulos 《Journal of musculoskeletal & neuronal interactions》2021,21(4):509
Objectives:The aim of this study was to analyze the association of knee OA with bone mineral density (BMD) and vitamin D serum levels in postmenopausal women.Methods:A cross-sectional study including 240 postmenopausal women with knee OA was conducted. Demographic data were recorded along with balance and functionality scores. Knee OA severity was assessed by the radiological Kellgren & Lawrence scale. BMD and T-scores were calculated in hips and lumbar spine. Serum levels of vitamin D were also measured.Results:High BMI (p<0.005), high number of children (p=0.022) and family history of hip fracture (p=0.011) are significantly associated with knee OA severity. Lumbar spine OP is negatively associated with knee OA (p<0.005). A significant difference was detected between vitamin D deficiency and severe knee OA, adjusted for BMD [OR (95%CI); 3.1 (1.6-6.1), p=0.001]. BMD does not affect the relationship of vitamin D levels in relation to OA and vitamin D levels do not affect the relationship of BMD with OA.Conclusions:Low BMD has a protective role against knee OA while vitamin D deficiency contributes significantly to knee OA severity. However, the association between OA and OP is not affected by vitamin D deficiency and the association of OA and vitamin D serum levels is not affected by BMD. 相似文献
167.
Kontargiris E Kolettas E Vadalouca A Trougakos IP Gonos ES Kalfakakou V 《Cell research》2004,14(5):415-422
Local anesthetics inhibit cell proliferation and induce apoptosis in various cell types. Ropivacaine, a unique, novel tertiary amine-type anesthetic, was shown to inhibit the proliferation of several cell types including keratinocytes. We found that Ropivacaine could inhibit the proliferation and induce apoptosis in an immortalized human keratinocyte line,HaCaT, in a dose- and time-dependent manner and with the deprivation of serum. The dose-dependent induction of apoptosis by ropivacaine was demonstrated by DNA fragmentation analysis and the proteolytic cleavage of a caspase-3 substrate—poly (ADP-ribose) polymerase (PARP). In addition, ropivacaine downregulated the expression of clusterin/ apoliporotein J, a protein with anti-apoptotic properties, in a dose-dependent manner, which well correlated with the induction of apoptosis of HaCaT cells. To investigate the role of clusterin/apoliporotein J in ropivacaine-induced apoptosis,HaCaT cells overexpressing clusterin/apoliporotein J were generated and compared to cells expressing the well established anti-apoptotic Bcl-2 protein. Ectopic overexpression of the secreted form of clusterin/apoliporotein J or Bcl-2decreased the sensitivity of HaCaT cells to toxic effects of ropivacaine as demonstrated by DNA fragmentation, the proteolytic cleavage of PARP and by a reduction in procaspase-3 expression. Furthermore, the downregulation of endogenous clusterin/apolipoprotein J levels by ropivacaine suggested that this might be one mechanism by which ropivacaine induced cell death in HaCaT cells. In conclusion, the ability of ropivacaine to induce antiproliferative responses and to suppress the expression of the anti-apoptotic protein clusterin/apolipoprotein J, combined with previously reported anti-inflammatory activity and analgesic property of the drug, suggests that ropivacaine may have potential utility in the local treatment of tumors. 相似文献
168.
Nahm WK Philpot BD Adams MM Badiavas EV Zhou LH Butmarc J Bear MF Falanga V 《Journal of cellular physiology》2004,200(2):309-317
Increasing data suggest that glutamate might act as a cell-signaling molecule in non-neuronal tissues such as the skin. Here we demonstrate the presence of functional N-methyl-D-aspartate (NMDA)-type glutamate receptors in human keratinocytes. NMDA receptor expression strongly reflects the degree of cell-to-cell contact. Wounding polarizes the expression of NMDA receptors in keratinocytes involved in re-epithelialization, and the process of re-epithelialization is inhibited by NMDA receptor activation. We also demonstrate that squamous cell carcinomas lack NMDA receptors. Our data suggest that Ca2+ entry through NMDA receptors influences the cycle of keratinocyte proliferation, differentiation, and migration during epithelialization. Moreover, NMDA receptor activation might play a role in contact-mediated inhibition of growth, a process that is absent during neoplastic pathology. This receptor may serve as a pharmacological target for modulating keratinocyte behavior and treating cutaneous disorders. 相似文献
169.
Keramidas EG Rodopoulou SG Tsoutsos D Miller G Ioannovich J 《Plastic and reconstructive surgery》2004,114(5):1131-4; discussion 1135-6
A randomized, double-blind study was performed in 50 patients to compare the transthecal and traditional subcutaneous infiltration techniques of digital block anesthesia regarding the onset of time to achieve anesthesia and pain during the infiltration. All the patients had sustained injury involving two or four fingers of the hand. Each patient served as his or her own control, having one finger infiltrated with the transthecal technique and the other with the subcutaneous infiltration technique. Time to loss of pinprick sensation and pain (at the time of the infiltration and 24 hours postoperatively) were assessed using a visual analogue scale and verbal response score. A total of 104 blocks (52 transthecal and 52 subcutaneous infiltration) were performed. All of these blocks were successful. Mean time to achieve anesthesia with the transthecal block was 165 seconds, compared with 100 seconds for the subcutaneous infiltration block. The mean analogue pain score was higher for transthecal blocks than for subcutaneous infiltration blocks (3.2 +/- 0.19 versus 1.6 +/- 0.14). Twenty-four hours postoperatively, 24 patients who had the transthecal block experienced pain at the injection site of the digit. However, none of the patients who received the subcutaneous infiltration block complained of pain at the digit. The technique of anesthesia preferred by patients for their finger was the subcutaneous infiltration block, because it causes less pain. Our results confirm the efficacy of the transthecal block for achieving anesthesia of the finger; however, because it is a more painful procedure, it is not recommended. 相似文献
170.
Hatziantoniou S Giamarellos-Bourboulis EJ Skiathitis S Demetzos C Donta I Papaioannou GT Dionyssiou-Asteriou A Karayannacos PE Giamarellou H 《Prostaglandins, leukotrienes, and essential fatty acids》2004,70(5):465-468
Polyunsaturated fatty acids (PUFAs) have been shown to possess a considerable anti-tumor and anti-bacterial effect in vitro. In an attempt to achieve serum concentrations of these acids similar to those applied in vitro, a solution of ethyl ester of arachidonic acid (AA) was administered intravenously at 25 mg/kg within 10 min in six male rabbits. Blood samples were collected before and 60 min after infusion from catheters inserted in the hepatic veins and in the carotid artery. Analysis of serum fatty acids was performed by gas chromatography mass spectrometry. Elevated concentrations of elongated fatty acids were detected in the hepatic veins after infusion. Mean concentrations of arachidonate in the hepatic veins and the carotid arteries after infusion of AA were 2.77 and 3.73 microM, respectively. It is concluded that the intravenous administration of a solution of AA might result in increased hepatic biosynthesis of serum saturated and unsaturated fatty acids of elongated carbon chains. The increasing interest for the application of PUFAs in therapeutics renders further study mandatory to clarify the significance of these findings. 相似文献