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1.
Influence of external factors on secondary embryogenesis and germination in somatic embryos from leaves of Quercus suber 总被引:2,自引:0,他引:2
Bárbara Fernández-Guijarro Cristina Celestino Mariano Toribio 《Plant Cell, Tissue and Organ Culture》1995,41(2):99-106
Somatic embryogenesis was obtained in cultures of leaves from young seedlings of Quercus suber L. A two-stage process, in which benzyladenine and naphthaleneacetic acid were added first at high and then at low concentrations, was required to initiate the process. Somatic embryos arose when the explants were subsequently placed on medium lacking plant growth regulators. The embryogenic lines remained productive, by means of secondary embryogenesis, on medium without growth regulators. However, this repetitive induction was influenced by the macronutrient composition of the culture medium. Both low total nitrogen content and high reduced nitrogen concentration decreased the percentage of somatic embryos that showed secondary embryogenesis. Our results suggest that alternate culture on medium that increases embryo proliferation and a low salt medium prohibiting embryo formation will partially synchronize embryo development. Chilling slightly reduced secondary embryogenesis but gave a modest increase in germination. Maturation under light followed by storage at 4 °C for at least 30 days gave the best results in switching embryos from an embryogenic pathway to a germinative one. Under these conditions 15% of embryos showed coordinated root and shoot growth and 35% formed either shoots or mostly roots. These percentages were higher than those of embryos matured in darkness. This result indicates that a specific treatment is required after maturation and before chilling to activate the switch from secondary embryo formation to germination.Abbreviations BA
benzyladenine
- NAA
naphthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- BA
indolebutyric acid
- MS
Murashige & Skoog (1962) medium
- SH
Schenk & Hildebrandt (1972) medium
- G
Gamborg (1966, PRL-4-C) medium (macronutrients in mg l–1: NaH2PO4·H2O, 90; Na2HPO4, 30; KCl, 300; (NH4)2SO4, 200; MgSO4·7H2O, 250; KNO3, 1000, CaCl2·2H2O, 150)
- PGR
plant growth regulator 相似文献
2.
Mohammed O. Abdelaziz Celestino Bonura Aurora Aleo Teresa Fasciana Cinzia Calà Caterina Mammina 《Microbiology and immunology》2013,57(5):391-395
Cephalosporin‐resistant Escherichia coli has been increasingly reported worldwide. In this study, 32 cephalosporin resistant E. coli isolates identified from cancer patients in Cairo, Egypt in 2009–2010 were analyzed. Twenty‐three were of phylogenetic group D, seven A and one each B1 and B2. By rep‐PCR 15 phylogroup D isolates were grouped in four clusters, one with sequence type (ST) 405 and three ST68. Seventeen isolates showed single patterns. blaCTX‐M‐15 and aac(6')‐Ib‐cr were the most common resistance determinants. blaOXA‐48 and blaVIM were also detected. Multidrug resistant E. coli seriously affects healthcare, especially in immunocompromised hosts, such as cancer patients. 相似文献
3.
Role of 17beta-estradiol administration on insulin sensitivity in the rat: implications for the insulin receptor 总被引:6,自引:0,他引:6
González C Alonso A Grueso NA Díaz F Esteban MM Fernández S Patterson AM 《Steroids》2002,67(13-14):993-1005
The role of 17beta-estradiol in the early steps of insulin action is only partially known, although its effect on glucose homeostasis has been reported. In this paper, we attempt to prove the influence of 17beta-estradiol on the insulin receptor of ovariectomized rats treated with different hormonal doses. Our results show that high doses of estradiol impair insulin sensitivity while low doses improve it. We think that these results are the consequence of changes at a molecular level, because high doses of estradiol produced lower expression of the insulin receptor gene, lower content of this receptor in target tissues, and lower phosphorylation of insulin receptor in these tissues. However, low doses of estradiol seem to produce just the opposite. The possible existence of consensus response elements in the insulin receptor gene promoter to estradiol could be controlling the expression of this gene, this control being dose and timing dependent. Moreover, we cannot discard a possible effect of estradiol on the activity of protein tyrosine phosphatases, and therefore, on the activity of the insulin receptor. These new findings improve knowledge about the possible risk for insulin resistance in women taking oral contraceptives or receiving hormonal replacement therapy around the menopause, but could also open the door towards the possible utilization of 17beta-estradiol in some diabetes cases. 相似文献
4.
High-flavonol tomatoes resulting from the heterologous expression of the maize transcription factor genes LC and C1 总被引:20,自引:0,他引:20 下载免费PDF全文
5.
Somatic embryogenesis was induced in expanding leaves from epicormic shoots forced to sprout from segments of branches collected from several hundred-year-old cork oak trees. Following a basic protocol previously defined for leaves taken from seedlings of this species, several factors were studied to improve the response. The induction frequency was significantly higher when the length of exposure to growth regulators was increased from 7 to 30 days. The combined application of NAA and BAP was essential for induction. Although both regulators had a very significant influence, their interaction was not significant, suggesting independent roles. Leaf size had a crucial effect, because beyond a certain threshold, embryogenesis could not be obtained. Embryogenic lines were maintained via repetitive embryogenesis on hormone-free medium for more than 2 years. 相似文献
6.
Absence of association between mannose-binding lectin gene polymorphisms and HIV-1 infection in a Colombian population 总被引:5,自引:0,他引:5
Mannose-binding lectin (MBL) is a calcium-dependent lectin shown to play an important role in innate immunity to infection by activating the classical complement pathway and phagocytosis. In vitro studies have shown that MBL is able to bind to the gp120 HIV-1 surface antigen, and variants of the gene are associated with increased risk of HIV infection among Scandinavians. We investigated the association of genetic MBL variants and HIV-1 infection in 278 Colombian HIV-infected and control individuals. MBL genotype frequencies were similar for both groups, and no association was detected between MBL alleles B, C, and D and susceptibility to HIV-1 infection ( P=1.0). Since there is a well-documented link between the tested MBL alleles and very low MBL serum concentration, these results do not support the hypothesis that MBL levels are a risk factor for HIV-1 infection in Colombia. 相似文献
7.
Conjugates of avidin with ferrocene and with microperoxidase 8 have been used as electrochemically active molecular building blocks. Assemblies of the conjugates with biotinylated glucose oxidase or lactate oxidase on gold electrodes were tested as enzyme sensors for glucose and lactate. The electrochemical detection is based either on ferrocene-mediated oxidation of the substrate in oxygen-free solution, or on microperoxidase-catalysed reduction of H2O2 which is enzymatically produced from the substrate and molecular oxygen. Glucose and lactate were detectable with both detection principles in concentrations down to 1 or 0.1 mM, respectively. The molecular architecture concept allows quick adaptation of the sensors to other analytes, and it provides a platform for arrays of sensors with different selectivity. 相似文献
8.
Matos MH Lima-Verde IB Luque MC Maia JE Silva JR Celestino JJ Martins FS Báo SN Lucci CM Figueiredo JR 《Zygote (Cambridge, England)》2007,15(2):173-182
The aims of the present study were to investigate the effects of follicle-stimulating hormone (FSH) on survival, activation and growth of caprine primordial follicles using histological and ultrastructural studies. Pieces of caprine ovarian cortex were cultured for 1 or 7 days in minimum essential medium (MEM - control medium) supplemented with different concentrations of FSH (0, 10, 50 or 100 ng/ml). Small fragments from non-cultured ovarian tissue and from those cultured for 1 or 7 days in a specific medium were processed for classical histology and transmission electron microscopy (TEM). Additionally, effects of FSH on oocyte and follicle diameter of cultured follicles were evaluated. The results showed that the lowest percentage of normal follicles was observed after 7 days of culture in control medium. After 1 day of culture, a higher percentage of growing follicles was observed in the medium supplemented with 50 ng/ml of FSH. In the presence of 10 and 50 ng/ml of FSH, an increase in diameter of both oocyte and follicle on day 7 of culture was observed. TEM showed ultrastructural integrity of follicles after 1 day of culture in MEM and after 7 days in MEM plus 50 ng/ml FSH, but did not confirm the integrity of those follicles cultured for 7 days in MEM. In conclusion, this study demonstrated that FSH at concentration of 50 ng/ml not only maintains the morphological integrity of 7 days cultured caprine preantral follicles, but also stimulate the activation of primordial follicles and the growth of activated follicles. 相似文献
9.
Saraiva MV Celestino JJ Araújo VR Chaves RN Almeida AP Lima-Verde IB Duarte AB Silva GM Martins FS Bruno JB Matos MH Campello CC Silva JR Figueiredo JR 《Zygote (Cambridge, England)》2011,19(3):205-214
This study evaluated the expression of FSH receptors (FSHR) in the different stages of goat follicle development and investigated whether the addition of increasing concentrations of FSH throughout the culture period influences the survival, growth and antral formation of in vitro-cultured caprine preantral follicles. The expression of FSHR was analysed before and after culturing follicles using real-time RT-PCR. For the culture, preantral follicles (≥150 μm) were isolated from ovarian fragments and cultured for 18 days in α-MEM+ alone or associated with recombinant FSH (rFSH: 100 or 1000 ng/ml), or in α-MEM+ supplemented with increasing concentrations of FSH throughout culture periods as follows: (a) sequential medium 1: FSH 100 ng/ml (from day 0 to 6), FSH 500 ng/ml (from day 6 to 12) and FSH 1000 ng/ml (from day 12 to 18); and (b) sequential medium 2: FSH 500 ng/ml (from day 0 to 9) and 1000 ng/ml (from day 9 to 18). Follicle development was evaluated on the basis of antral cavity formation, follicular and oocyte growth, and cumulus-oocyte complex health. The expression of FSHR in isolated caprine follicles increased from the preantral to antral phase. Regarding the culture, after 18 days, sequential medium 1 promoted follicular survival, antrum formation and a reduction in oocyte extrusion. Both sequential media promoted a higher rate of meiotic resumption compared with the other treatments. In conclusion, the addition of increased concentrations of FSH (sequential medium) has a significant impact on the in vitro development of caprine preantral follicles. 相似文献
10.
Alvarez-Suarez JM Dekanski D Ristić S Radonjić NV Petronijević ND Giampieri F Astolfi P González-Paramás AM Santos-Buelga C Tulipani S Quiles JL Mezzetti B Battino M 《PloS one》2011,6(10):e25878