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131.
The cucumber cotyledon expansion test was used as a model system to study a possible relationship between cytokinin and polyamines.
When kinetin was applied to excised cotyledons incubated in the dark it caused a marked increase in the activity of arginine
decarboxylase. As a result of ADC action, putrescine content also rose markedly, whereas the level of spermidine and spermine
decreased. However, inhibition of putrescine biosynthesis with D-arginine did not affect cytokinin promotion growth. Applied
alone, putrescine had no significant effect on growth. These results indicate that the large increase in putrescine content
that derives from cytokinin treatment cotyledons is not essential for cytokinin-induced expansion of cotyledons. Addition
of K+ and Ca2+ ions to the cotyledons incubated with cytokinin caused a marked reduction in the putrescine level and ADC activity.
The higher level of putrescine (35 %) and spermine (62 %) bound to chromatin and the large increase (174 %) in spermidine
content bound to ribosomes which derive from cytokinintreated cotyledons in relation to literature data can indicate that
these polyamines may play an important role in gene expression during cytokinin-stimulated expansion of cucumber cotyledons.
The inhibition of cytokinin effect, viz. enlargement of the cotyledons by inhibitors of spermidine biosynthesis, additionally suggessted a possible involvement of
polyamines in cytokinin action. 相似文献
132.
Implication of tissue transglutaminase and desmoplakin in cell adhesion mechanism in human epidermis
Esposito C Lombardi ML Ruocco V Cozzolino A Mariniello L Porta R 《Molecular and cellular biochemistry》2000,206(1-2):57-65
The distribution patterns of both tissue and keratinocyte transglutaminases (TGase), as well as that of desmoplakin (DP), have been immunohistochemically investigated in human skin cultured in the absence or presence of cystamine and enalapril, two acantholytic agents. In the control samples, tissue TGase is predominantly expressed in lower layers of the epidermis and is located intercellularly. Conversely, in tissues cultured with cystamine or enalapril, a diffuse cytoplasmatic staining was observed. Similarly, DP, detected on the cell membrane in the control, shifts into the cytosol of the keratinocytes following treatment. The distribution pattern of the keratinocyte enzyme in the acantholytic epidermis was identical to that observed in the normal one. Since cystamine and enalapril are TGase inhibitors and DP was shown to act as a TGase substrate in vitro, we suggest that DP and tissue enzyme may participate in cell adhesion at the intraepidermal level. 相似文献
133.
Anatomical study of zygotic and somatic embryos of Tilia cordata 总被引:1,自引:0,他引:1
A comparative anatomical study was carried out on zygotic and somatic embryos of Tilia cordata Mill. to evaluate the effect of growth conditions on their development. Zygotic embryos (heart-shaped, torpedo, cotyledonary),
collected during two autumn periods, were examined to investigate the effect of growing season on embryo development. In comparison,
the influence of growth conditions on the development of somatic embryos in vitro was also studied. Treatment with abscisic acid (ABA) and polyethylene glycol-4000 induced the development of somatic cotyledonary
embryos similar to zygotic embryos with respect to morphology and anatomy, as illustrated by the differentiation of the apical
meristems and of the procambium. The pattern of accumulation of starch and protein was also similar in these embryos. Somatic
cotyledonary embryos that developed spontaneously without ABA showed defective accumulation of storage material and a general
failure to form the shoot apical meristem, leading to very low germination rates. Vacuolar phenolic deposits were observed
along the procambium of both zygotic and somatic embryos regardless of the maturation stage. Tracheid formation was observed
only in somatic embryos formed without ABA in the medium and in precociously germinated somatic embryos. Phenolic vacuolar
inclusions were frequently observed in epidermal cells of these embryos.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
134.
135.
Ana Maria Fernandez-Pujals Mark James Adams Pippa Thomson Andrew G. McKechanie Douglas H. R. Blackwood Blair H. Smith Anna F. Dominiczak Andrew D. Morris Keith Matthews Archie Campbell Pamela Linksted Chris S. Haley Ian J. Deary David J. Porteous Donald J. MacIntyre Andrew M. McIntosh 《PloS one》2015,10(11)
The heritability of Major Depressive Disorder (MDD) has been estimated at 37% based largely on twin studies that rely on contested assumptions. More recently, the heritability of MDD has been estimated on large populations from registries such as the Swedish, Finnish, and Chinese cohorts. Family-based designs utilise a number of different relationships and provide an alternative means of estimating heritability. Generation Scotland: Scottish Family Health Study (GS:SFHS) is a large (n = 20,198), family-based population study designed to identify the genetic determinants of common diseases, including Major Depressive Disorder. Two thousand seven hundred and six individuals were SCID diagnosed with MDD, 13.5% of the cohort, from which we inferred a population prevalence of 12.2% (95% credible interval: 11.4% to 13.1%). Increased risk of MDD was associated with being female, unemployed due to a disability, current smokers, former drinkers, and living in areas of greater social deprivation. The heritability of MDD in GS:SFHS was between 28% and 44%, estimated from a pedigree model. The genetic correlation of MDD between sexes, age of onset, and illness course were examined and showed strong genetic correlations. The genetic correlation between males and females with MDD was 0.75 (0.43 to 0.99); between earlier (≤ age 40) and later (> age 40) onset was 0.85 (0.66 to 0.98); and between single and recurrent episodic illness course was 0.87 (0.72 to 0.98). We found that the heritability of recurrent MDD illness course was significantly greater than the heritability of single MDD illness course. The study confirms a moderate genetic contribution to depression, with a small contribution of the common family environment (variance proportion = 0.07, CI: 0.01 to 0.15), and supports the relationship of MDD with previously identified risk factors. This study did not find robust support for genetic differences in MDD due to sex, age of onset, or illness course. However, we found an intriguing difference in heritability between recurrent and single MDD illness course. These findings establish GS:SFHS as a valuable cohort for the genetic investigation of MDD. 相似文献
136.
137.
Li L Stillemark-Billton P Beck C Boström P Andersson L Rutberg M Ericsson J Magnusson B Marchesan D Ljungberg A Borén J Olofsson SO 《Journal of lipid research》2006,47(1):67-77
Epigallocatechin gallate (EGCG) increases the formation of cytosolic lipid droplets by a mechanism that is independent of the rate of triglyceride biosynthesis and involves an enhanced fusion between lipid droplets, a process that is crucial for their growth in size. EGCG treatment reduced the secretion of both triglycerides and apolipoprotein B-100 (apoB-100) VLDLs but not of transferrin, albumin, or total proteins, indicating that EGCG diverts triglycerides from VLDL assembly to storage in the cytosol. This is further supported by the observed increase in both intracellular degradation of apoB-100 and ubiquitination of the protein (indicative of increased proteasomal degradation) in EGCG-treated cells. EGCG did not interfere with the microsomal triglyceride transfer protein, and the effect of EGCG on the secretion of VLDLs was found to be independent of the LDL receptor. Thus, our results indicate that EGCG promotes the accumulation of triglycerides in cytosolic lipid droplets, thereby diverting lipids from the assembly of VLDL to storage in the cytosol. Our results also indicate that the accumulation of lipids in the cytosol is not always associated with increased secretion of VLDL. 相似文献
138.
Valentine SP Le Nedelec MJ Menzies AR Scandlyn MJ Goodin MG Rosengren RJ 《Life sciences》2006,78(20):2391-2398
Curcumin, the yellow pigment found in turmeric, exhibits potent chemopreventative properties in both in vivo and in vitro cancer models. We hypothesized that this effect may occur via curcumin-mediated changes in enzymes involved in both carcinogen bioactivation and estrogen metabolism. Female Swiss Webster mice were treated with either curcumin (200 mg/kg or 400 mg/kg, p.o.) or vehicle control for 1 or 2 weeks. The results demonstrated that curcumin had no effect on the catalytic activities of ovarian aromatase, hepatic catechol-O-methyltransferase or hepatic UDP-glucuronosyltransferase. However, both doses of curcumin caused a 25% decrease in CYP1A catalytic activity, but not polypeptide levels, following 2 weeks of treatment. Additionally, following 2 weeks of curcumin at 400 mg/kg, there was a 20% decrease in the catalytic activity and a 28% decrease in polypeptide levels of CYP3A. While 2 weeks of curcumin treatment (400 mg/kg) caused a 20% increase in glutathione S-transferase activity, there was no parallel increase in hepatic stores of the co-factor glutathione. In conclusion small changes in CYP1A, CYP3A and GST following long term treatment (2 weeks) suggest that the combination of all three metabolic pathways may play a small role in curcumin's chemopreventative action. 相似文献
139.
Balandina A Kamashev D Rouviere-Yaniv J 《The Journal of biological chemistry》2002,277(31):27622-27628
HU, a major component of the bacterial nucleoid, shares properties with histones, high mobility group proteins (HMGs), and other eukaryotic proteins. HU, which participates in many major pathways of the bacterial cell, binds without sequence specificity to duplex DNA but recognizes with high affinity DNA repair intermediates. Here we demonstrate that HU binds to double-stranded DNA, double-stranded RNA, and linear DNA-RNA duplexes with a similar low affinity. In contrast to this nonspecific binding to total cellular RNA and to supercoiled DNA, HU specifically recognizes defined structures common to both DNA and RNA. In particular HU binds specifically to nicked or gapped DNA-RNA hybrids and to composite RNA molecules such as DsrA, a small non-coding RNA. HU, which modulates DNA architecture, may play additional key functions in the bacterial machinery via its RNA binding capacity. The simple, straightforward structure of its binding domain with two highly flexible beta-ribbon arms and an alpha-helical platform is an alternative model for the elaborate binding domains of the eukaryotic proteins that display dual DNA- and RNA-specific binding capacities. 相似文献
140.
Nielsen KJ Watson M Adams DJ Hammarström AK Gage PW Hill JM Craik DJ Thomas L Adams D Alewood PF Lewis RJ 《The Journal of biological chemistry》2002,277(30):27247-27255
Mu-conotoxins are peptide inhibitors of voltage-sensitive sodium channels (VSSCs). Synthetic forms of mu-conotoxins PIIIA and PIIIA-(2-22) were found to inhibit tetrodotoxin (TTX)-sensitive VSSC current but had little effect on TTX-resistant VSSC current in sensory ganglion neurons. In rat brain neurons, these peptides preferentially inhibited the persistent over the transient VSSC current. Radioligand binding assays revealed that PIIIA, PIIIA-(2-22), and mu-conotoxins GIIIB discriminated among TTX-sensitive VSSCs in rat brain, that these and GIIIC discriminated among the corresponding VSSCs in human brain, and GIIIA had low affinity for neuronal VSSCs. (1)H NMR studies found that PIIIA adopts two conformations in solution due to cis/trans isomerization at hydroxyproline 8. The major trans conformation results in a three-dimensional structure that is significantly different from the previously identified conformation of mu-conotoxins GIIIA and GIIIB that selectively target TTX-sensitive muscle VSSCs. Comparison of the structures and activity of PIIIA to muscle-selective mu-conotoxins provides an insight into the structural requirements for inhibition of different TTX-sensitive sodium channels by mu-conotoxins. 相似文献