共查询到20条相似文献,搜索用时 123 毫秒
1.
2.
Giovanni Morici Alessandra d'Azzo Maria Di Bernardo 《Development, growth & differentiation》2013,55(2):237-246
The sea urchin provides a relatively simple and tractable system for analyzing the early stages of embryo development. Here, we use the sea urchin species, Paracentrotus lividus, to investigate the role of Alix in key stages of embryogenesis, namely the egg fertilization and the first cleavage division. Alix is a multifunctional protein involved in different cellular processes including endocytic membrane trafficking, filamentous (F)‐actin remodeling, and cytokinesis. Alix homologues have been identified in different metazoans; in these organisms, Alix is involved in oogenesis and in determination/differentiation events during embryo development. Herein, we describe the identification of the sea urchin homologue of Alix, PlAlix. The deduced amino acid sequence shows that Alix is highly conserved in sea urchins. Accordingly, we detect the PlAlix protein cross‐reacting with monoclonal Alix antibodies in extracts from P. lividus, at different developmental stages. Focusing on the role of PlAlix during early embryogenesis we found that PlAlix is a maternal protein that is expressed at increasingly higher levels from fertilization to the 2‐cell stage embryo. In sea urchin eggs, PlAlix localizes throughout the cytoplasm with a punctuated pattern and, soon after fertilization, accumulates in larger puncta in the cytosol, and in microvilli‐like protrusions. Together our data show that PlAlix is structurally conserved from sea urchin to mammals and may open new lines of inquiry into the role of Alix during the early stages of embryo development. 相似文献
3.
4.
Shioh Ooka Tomoko Katow Shunsuke Yaguchi Junko Yaguchi Hideki Katow 《Development, growth & differentiation》2010,52(2):195-207
We have cloned and studied Hp‐ECPN, an encephalopsin orthologue of the sea urchin Hemicentrotus pulcherrimus. Hp‐ecpn cDNA was produced and found to contain a 1461‐bp open reading frame that encodes 486 amino acids. Accumulation of Hp‐ecpn mRNA and protein expression occurred at the 14 h postfertilization (hpf) swimming blastula stage and thereafter. The Hp‐ECPN protein was N‐glycosylated, and the amino acid sequence was similar to that of vertebrate encephalopsins. Whole‐mount immunohistochemistry revealed the presence of Hp‐ECPN in cells (ECPN cells) that appeared initially around the tip of the archenteron in 20 hpf early gastrulae. By the 54 hpf pluteus stage, ECPN cells had spread through the aboral ectoderm, and, by the eight‐arm pluteus stage, were restricted to the tips of the larval arms and the posterior end of the body. The number of ECPN cells increased under conditions of continuous light, but decreased under continuous dark. Knockdown of Hp‐ecpn mRNA using morpholino antisense oligonucleotides decreased the number of ECPN cells considerably, and inhibited the vertical swimming of the larvae. This suggested that Hp‐ECPN plays a role in photosensitive larval swimming vertical migration. In adult tissues, the ECPN cells were detected exclusively in tube feet. 相似文献
5.
In permanent blastulae of the sea urchin, which were obtained by culture in SO2?4-free artificial seawater from the time of fertilization, ascorbate and α-ketoglutarate, activators of protocollagen proline hydroxylase, induced the formation of archenteron. By adding either ascorbate or α-ketoglutarate to the SO2?4-free culture at 12 hr of fertilization, spherical embryos with archenteron were obtained by successive 12 hr cultures at 20°C. The embryos thus obtained did not develop to plutei. Archenteron formation induced by these compounds in SO2?4-free-cultured embryos, as well as in the normal embryos, was inhibited by α,α′-dipyridyl, an inhibitor of protocollagen proline hydroxylase. Glutamate, malate, citrate, and fumarate did not stimulate archenteron formation in SO2?4-free cultured embryos. In the SO2?4-free-cultured embryos exposed to [14C]proline, considerable radioactivity was found in hot trichloroacetic acid-extractable proteins but the radioactivity of [14C]hydroxyproline residue, produced by hydroxylation of proline residue of protocollagen, was markedly lower than that in normal embryos. In the presence of ascorbate and α-ketoglutarate, the radioactivity of [14C]hydroxyproline residue became high and was lowered by α,α′-dipyridyl. Archenteron formation induced by ascorbate and α-ketoglutarate in the embryos kept in SO2?4-free artificial seawater probably results from the stimulated protocollagen hydroxylation. 相似文献
6.
Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth,
photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental
design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m−2 day−1; enhanced UV-B, 14.33 KJ m−2 day−1) and two nitrogen levels (0; 20 g N m−2). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic
rate (Pn), photosynthetic pigments and F
v/F
m, (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and F
v/F
m under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced
UV-B or nitrogen supply changed the concentration of nutrient elements of various organs. 相似文献
7.
Quan-fu Wang Yan-hua Hou Jin-lai Miao Guang-you Li 《Acta Physiologiae Plantarum》2009,31(6):1097-1102
The effect of ultraviolet-B (UV-B) radiation on Antarctic phytoplankton has become an attractive ecological issue as a result
of annual springtime ozone depletion. The effects of UV-B radiation on the growth and antioxidant enzymes were investigated
using Antarctic sea ice microalgae Chlamydomonas sp. ICE-L as the material in this study. The results demonstrated that UV-B radiation could notably inhibit the growth, especially
at high UV-B radiation intensity (70 μW cm−2). Malondialdehyde and O2
·− content in ICE-L increased rapidly in early days (1–3 days) exposed to UV-B radiation enhancement, then decreased rapidly.
In the stress of UV-B radiation enhancement, the superoxide dismutase, peroxidase and Catalase activities of 1–4 days in ICE-L
were obviously higher than those in the control, and their activities became higher at high UV-B radiation intensity (70 μW cm−2). These enzymes activity of 7 days would kept stable at low UV-B radiation intensity (35 μW cm−2), but kept high level at high UV-B radiation intensity (70 μW cm−2). However, the ascorbate peroxidase activity in ICE-L kept stable under the stress of UV-B radiation enhancement. The above
experimental results indicated that the antioxidant enzyme system played an important role in the adaptation of Antarctic
ice microalgae under the UV-B radiation change of Antarctic ecosystems. 相似文献
8.
Cloning and characterization of the 14-3-3 protein gene from the halotolerant alga Dunaliella salina
Previous studies have demonstrated that 14-3-3 proteins exist in all the eukaryotic organisms studied; however, studies on
the 14-3-3 proteins have not been involved in the halotolerant, unicellular green alga Dunaliella salina so far. In the present study, a cDNA encoding 14-3-3 protein of D. salina was cloned and sequenced by PCR and rapid amplification of cDNA end (RACE) technique based on homologous sequences of the
14-3-3 proteins found in other organisms. The cloned cDNA of 1485 bp in length had a 29.2 kDa of molecular weight and contained
a 774 bp of open reading frame encoding a polypeptide of 258 amino acids. Like the other 14-3-3 proteins, the deduced amino
acid sequences of the D. salina 14-3-3 protein also contained two putative phosphorylation sites within the N-terminal region (positions 62 and 67). Furthermore,
an EF hand motif characteristic for Ca2+-binding sites was located within the C-terminal part of this polypeptide (positions 208–219). Analysis of bioinformatics
revealed that the 14-3-3 protein of D. salina shared homology with that of other organisms. Real-time quantitative PCR demonstrated that expression of the 14-3-3 protein
gene is cell cycle-dependent. 相似文献
9.
10.
Yantree Devi Sankar-Thomas Katja Saare-Surminski Reinhard Lieberei 《Plant Cell, Tissue and Organ Culture》2008,95(2):163-173
The present study describes a protocol for plant regeneration via somatic embryogenesis in temporary immersion system (TIS)
for Camptotheca acuminata. Somatic embryos were induced by culturing hypocotyl segments from 14-day-old in vitro grown C. acuminata seedlings in TIS. Hypocotyl segments were placed in culture vessels modified with a mechanical device to support the fixation
of explants. Cultures were maintained under a 16 h photoperiod with a light intensity of 60 μmol m−2 s−1 PPF at 25 ± 1°C. After 16 weeks of incubation embryogenic calli were formed above the edge of the mechanical device in the
basal Murashige and Skoog (MS) medium containing 35 g l−1 sucrose and without hormonal supplementation. For plantlet regeneration, somatic embryos at cotyledonary stage were cultured
in three different concentrations of 6-benzylamino-purine (0.5, 1.0 and 1.5 mg l−1 BAP) and in plant growth regulator (PGR) free medium. In general, 0.5 mg l−1 BAP was found to be the most effective concentration for growth and development of Camptotheca embryos in TIS. Conversion of somatic embryos into plantlets was also successfully achieved on sterile substrates moistened
with 0.5 mg l−1 BAP. Plantlets derived from cotyledonary embryos were rooted in vitro with 0.5 mg l−1 indole-3-butyric acid (IBA) before transfer to ex vitro conditions. 相似文献
11.
Chemical Exchange Saturation Transfer (CEST) is an MRI approach that can indirectly detect exchange broadened protons that
are invisible in traditional NMR spectra. We modified the CEST pulse sequence for use on high-resolution spectrometers and
developed a quantitative approach for measuring exchange rates based upon CEST spectra. This new methodology was applied to
the rapidly exchanging Hδ1 and Hε2 protons of His57 in the catalytic triad of bovine chymotrypsinogen-A (bCT-A). CEST enabled
observation of Hε2 at neutral pH values, and also allowed measurement of solvent exchange rates for His57-Hδ1 and His57-Hε2
across a wide pH range (3–10). Hδ1 exchange was only dependent upon the charge state of the His57 (k
ex,Im+ = 470 s−1, k
ex,Im = 50 s−1), while Hε2 exchange was found to be catalyzed by hydroxide ion and phosphate base (
k\textOH - k_{{{\text{OH}}^{ - } }} = 1.7 × 1010 M−1 s−1,
k\textHPO42 - k_{{{\text{HPO}}_{4}^{2 - } }} = 1.7 × 106 M−1 s−1), reflecting its greater exposure to solute catalysts. Concomitant with the disappearance of the Hε2 signal as the pH was
increased above its pK
a, was the appearance of a novel signal (δ = 12 ppm), which we assigned to Hγ of the nearby Ser195 nucleophile, that is hydrogen bonded to Nε2 of neutral His57. The
chemical shift of Hγ is about 7 ppm downfield from a typical hydroxyl proton, suggesting a highly polarized O–Hγ bond. The
significant alkoxide character of Oγ indicates that Ser195 is preactivated for nucleophilic attack before substrate binding.
CEST should be generally useful for mechanistic investigations of many enzymes with labile protons involved in active site
chemistry. 相似文献
12.
We report the effect of UV-B radiation (0.8 ± 0.1 mW cm−2) and UV-B radiation supplemented with low-intensity PAR (∼80 μmol photons m−2 s−1) on the photosynthesis, photosynthetic pigments, phosphoglycolipids, oxidative damage, enzymatic antioxidants, and UV-absorbing
compounds in Phormidium tenue, a marine cyanobacterium. UV-B radiation resulted in a decline in photosynthesis and photosynthetic pigments leading to lower
biomass. P. tenue synthesized UV-absorbing compounds like mycosporine-like amino acids (MAAs) and scytonemin in response to UV-B radiation.
Quantity of MAAs and scytonemin was higher when UV-B was supplemented with low-level PAR. UV-B treatment also resulted in
quantitative changes in phosphoglycolipids of the membrane. The UV-B treatment resulted in a slight increase in the level
of peroxidation of cell membrane and very little increase in the activity of superoxide dismutase (SOD). Results indicate
that UV-B affected photosynthesis and that the main protective system was the synthesis of MAAs and scytonemin-like compounds
rather than antioxidant enzymes such as SOD. 相似文献
13.
Synthesis of Collagen-Like Proteins in Embryonic Organs of the Sea Urchin, Hemicentrotus pulcherrimus 总被引:1,自引:1,他引:0
Hazime Mizoguchi Akiko Fujiwara Ikuo Yasumasu 《Development, growth & differentiation》1989,31(2):189-196
In sea urchin embryos exposed to 14 C-proline at 20°C for 3 hr at the gastrula, prism or pluteus stage, 14 C-radioactivity was found in hot acid-extractable proteins, in which more than 4% of the radioactivity was detectable in hydroxyproline residues. In these embryos, 14 C-radioactivity in collagen-like proteins was found in the archenteron, spicule and embryo-wall cells. The rate of synthesis of collagen-like proteins was highest in the archenteron in the mid-gastrula stage, in the embryo-wall cells in the prism stage and in the spicule in the pluteus stage. The rate of synthesis decreased in the archenteron and increased in embryo-wall cells in the period between the mid- and late-gastrula stages, when the rate of synthesis in the spicule was quite low. Thereafter, the rate decreased slightly in the embryo-wall cells, was maintained in archenteron and increased markedly in the spicule. The rates of synthesis of collagen-like proteins are high in these embryonic organs at stages at which development and growth respectively, occur in embryos. Therefore, synthesis of collagen-like proteins probably supports morphogenesis in these embryonic organs. 相似文献
14.
Chen XS Li S Liao LJ Ren XD Li F Tang L Zhang JH Mao ZG 《Bioprocess and biosystems engineering》2011,34(5):561-567
The production of ε-poly-l-lysine (ε-PL) by Streptomyces sp. M-Z18 from glycerol was investigated in a 5-L jar-fermenter. Batch fermentations by Streptomyces sp. M-Z18 at various pH values ranging from 3.5 to 4.5 were studied. Based on the analysis of the time course of specific
cell growth rate and specific ε-PL formation rate, a novel two-stage pH control strategy was developed to improve ε-PL production
by shifting the culture pH from 3.5 to 3.8 after 36 h of cultivation. By applying the strategy, the maximal ε-PL concentration
and productivity had a significant improvement and reached 9.13 g L−1 and 4.76 g L−1 day−1, respectively, compared with those in one-stage pH control process where the pH value is controlled at 3.5 (7.83 g L−1 and 3.13 g L−1 day−1). Fed-batch fermentation with two-stage pH control strategy was also applied to produce ε-PL; final ε-PL concentration of
30.11 g L−1 was obtained, being 3.3-fold greater than that of batch fermentation. To our knowledge, it is the first report on production
of ε-PL from glycerol in fermenter scale and achievement of high ε-PL production with two-stage pH control strategy. 相似文献
15.
The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial
suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1–1.6 J cm−2 (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0–2.61 mW cm−2. Irradiated conidia were then incubated for 24 h at 25°C under saturated humidity. The ratio of germination at each dose
over that in the blank control was defined as survival index (I
s). For all isolates, the I
s − D observations fit well with the survival model I
s = 1/[1 + exp(a + bD)] (0.94 ≤ r
2 ≤ 0.99) generated widely spanned lethal doses of 0.154–0.928, 0.240–1.139, and 0.383–1.493 J cm−2 for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm−2 measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity
to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method
was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses. 相似文献
16.
Zornitsa Katerova Sergei Ivanov Sergio Mapelli Vera Alexieva 《Acta Physiologiae Plantarum》2009,31(1):111-117
Pea (Pisum sativum L.) seedlings were exposed to low, moderate, and high regimes of ultraviolet-B (UV-B) (ld-B 4.4, md-B 13.3, and hd-B 26.5 kJ m−2 day−1), or ultraviolet-C (UV-C) (ld-C 0.1, md-C 0.3, and hd-C 0.6 kJ m−2 day−1) radiations. Concentrations of total phenols, free proline, and low-molecular thiol groups were determined in the last formed
(young) and older leaves after irradiation for 7, 10 or 14 consecutive days. Shoot length and weight did not change markedly
after 14 days of ld-B and ld-C, but reduced substantially after moderate and high regimes of both UV-B and UV-C. Proline decreased
upon high doses of irradiation, while in ld-B treated plants, by contrast, an increase was observed. The reduction in total
phenols and thiols was stronger after hd-B than after hd-C irradiations, although an induction was found in ld-B treated plants.
In contrast to ld-B, ld-C regime led mainly to reductions or insignificant changes in proline, phenols, and thiols. Therefore,
the stress-protection mechanisms are different between low UV-B and UV-C irradiation regimes in regard to proline, phenols,
and thiols. 相似文献
17.
Although estrogens have been detected in some echinoderm species, their role is not clearly understood; so we examined the
effects of estrogens administered to sea urchin embryos and larvae. A typical malformation was exogastrulation, induced by
the exposure to ethynylestradiol (EER) in a defined period of 12 h from 12 h after fertilization (HAF). Morphogenesis for
gastrulation was delayed in the treated embryos: protrusion of the archenteron started at 30 HAF when gastrulation had already
finished in normal embryos. Exogastrulation induced by EER was cancelled by the antiestrogen chemical, ICI182,780. Feeding
larvae were less sensitive to estrogens than those in early embryogenesis and, at certain concentrations, developed without
abnormal morphology. The effect of estrogens was examined at the level of gene expression of the major yolk protein (MYP).
MYP expression started during the larval stage and was suppressed by estrone at the six-armed stage, but not by β-estradiol,
and in later stage larvae, the expression was not affected by treatment with either estrogen. Estrogens affect sea urchins
in the early stage of embryogenesis, leading to abnormal morphogenesis and interference with gene expression. 相似文献
18.
Jing Li Yang Bo Zhao Eun Soo Seong Myong Jo Kim Won Hee Kang Na Young Kim Chang Yeon Yu Cheng Hao Li 《Plant biotechnology reports》2010,4(4):261-267
We describe culture conditions for a high-efficiency in vitro regeneration system of Papaver
nudicaule through somatic embryogenesis and secondary somatic embryogenesis. The embryogenic callus induction rate was highest when
petiole explants were cultured on Murashige and Skoog (MS) medium containing 1.0 mg l−1 α-naphthaleneacetic acid (NAA) and 0.1 mg l−1 6-benzyladenine (BA) (36.7%). When transferred to plant growth regulator (PGR)-free medium, 430 somatic embryos formed asynchronously
from 90 mg of embryogenic callus in each 100-ml flask. Early-stage somatic embryos were transferred to MS medium containing
1.0 mg l−1 BA and 1.0 mg l−1 NAA to germinate at high frequency (97.6%). One-third-strength MS medium with 1.0% sucrose and 1.0 mg l−1 GA3 had the highest frequency of plantlet conversion from somatic embryos (91.2%). Over 90% of regenerated plantlets were successfully
acclimated in the greenhouse. Secondary somatic embryos were frequently induced directly when the excised hypocotyls of the
primary somatic embryos were cultured on MS medium without PGRs. Sucrose concentration significantly affected the induction
of secondary embryos. The highest induction rate (89.5) and number of secondary somatic embryos per explant (9.3) were obtained
by 1% sucrose. Most secondary embryos (87.2–94.3%) developed into the cotyledonary stage on induction medium. All cotyledonary
secondary embryos were converted into plantlets both in liquid and on semisolid 1/3-strength MS medium with 1.0% sucrose. 相似文献
19.
We have for the first time succeeded in expressing in vitro-synthesized mRNAs in both the sinistral and the dextral Lymnaea stagnalis early embryos by microinjecting the mRNAs into the eggs before the first polar body stage. Translation of exogenous mRNA
in developing embryos was confirmed by expressing various fluorescent proteins; mCherry, DsRed-Express, and enhanced green
fluorescent protein. We have found that the protein expression derived from the introduced exogenous mRNA largely depends
on the elapsed time after the microinjection and not on the developmental stage of injection, and also on the amount of injected
mRNA. Developmental abnormalities were hardly observed. The first notable fluorescent signal was detected within 2–3 h after
the injection while the embryos were still in uncleaved stage. Fluorescence gradually increased until 8–9 h and was stable
up to 24 h. From these results, it is suggested that there is enough translation machinery necessary for early development
and the translation of injected mRNA proceeds immediately and constantly in the early embryos. This is true for both the sinistral
and dextral L. stagnalis embryos. Application of the developed method to other freshwater pond snails, dextral Lymnaea peregra, sinistral Physa acuta, and sinistral Indoplanorbis exustus revealed that their early expression mechanisms to be similar to that of L. stagnalis. Thus, in vitro-synthesized mRNA expression is expected to be important for the understanding of evolutional process and
the molecular mechanism underlining the handedness determination in these freshwater snail embryos. 相似文献
20.
K. Balaraju S. Saravanan P. Agastian S. Ignacimuthu 《Acta Physiologiae Plantarum》2011,33(4):1123-1133
An improved method of direct somatic embryogenesis (SE) was developed in Swertia chirata for the first time using leaves and roots of in vitro-grown young seedlings. In the present study, 2,4-dichlorophenoxyacetic
acid (2,4-D) was assessed individually and in combination with other auxins, as well as with cytokinin for its effectiveness
to induce somatic embryos. Leaf explants with abaxial side in the medium produced maximum number of somatic embryos. This
system omits the callus stage and thus reduces the process of SE in S. chirata by 35–45 days. Embryos at different stages of development were observed. Maturation of heart stage embryos were observed
on Murashige and Skoog (MS) medium containing 1 mg L−1 2,4-D. Upon transfer to the germination medium, they were converted to cotyledonary stage and then plantlets of 33% and 68%
of them were converted to cotyledonary stage and then plantlets on MS medium supplemented with 0.05 and 0.1 mg L-1 GA3 respectively. The 2,4-D alone at 1.0 or 1.5 mg L−1 was found to be better for embryogenic tissue initiation than 2,4-D in combination with indole-3-acetic acid or α-naphthalene
acetic acid. For further embryo development, 2,4-D was combined with cytokinins such as 6-benzylaminopurine (BAP) and kinetin
or plant growth regulator free medium or medium with 50% reduced concentration of the same hormone while subculturing. Mean
germination and percentage of survival were maximum in the medium containing 1.0 mg L−1 2,4-D in combination with 0.1 mg L−1 BAP. Regenerated plantlets were morphologically and genetically identical. This method offers a vast scope for the clonal
propagation of endangered plants. 相似文献