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11.
Adriana Bochicchio Paolo Vernieri Serenella Puliga Francesca Balducci Cuncetta Vazzana 《Physiologia plantarum》1994,91(4):615-622
The effect of exogenous ABA on acquisition of desiccation tolerance has been well documented for the embryos of several species. including maize ( Zea mays L.). It has also been suggested that endogenous ABA plays a role in regulating the same phenomena. To test this hypothesis, endogenous ABA was quantified by radioimmunoassay. Our results show that: (1) during embryogenesis in maize, endogenous ABA increase-concomitantly with the acquisition of desiccation tolerance: (2) ABA deficient embryos of the vp 5 mutant are desiccation intolerant, but tolerance can he induced by exogenous ABA: and (3) desiccation tolerance is acquired if desiccation sensitive embryos undergo a slow drying treatment, during which ABA increases. However, when embryos were preincubated in fluridone to prevent ABA accumulation during slow drying, desiccation tolerance was induced in spite of the low level of endogenous ABA in the embryo. Our results cast doubts on an exclusive role of ABA in the acquisition of desiccation tolerance in maize embryo. 相似文献
12.
Summary Embryogenic cultures were initiated from immature pecan zygotic embryos. Explants were induced for one week on Woody Plant Medium with either -naphthaleneacetic acid or 2,4-dichlorophenoxyacetic acid at 2, 6 or 12 mg/l, then subcultured monthly to fresh basal medium. Observations were made on callus production, embryo formation, and embryo morphology. Somatic embryo morphology and overall callus proliferation were affected by auxin type. Callus proliferation was less extensive and more somatic embryos resembling zygotic embryos were obtained from cultures initiated with -naphthaleneacetic acid than with 2,4-dichlorophenoxyacetic acid. Repetitive somatic embryogenesis was obtained in all auxin treatments. Conversion into plantlets was affected by somatic embryo morphology in that embryos with poorly developed apices exhibited lower percentages of conversion than those with well developed single or multiple apices. Consequently, although more embryos were obtained with 2,4-dichlorophenoxyacetic acid, naphthaleneacetic acid was the superior auxin for production of somatic embryos more likely to convert into plants.Abbreviations BAP
6-benzylaminopurine
- IAA
indole-3-acetic acid
- IBA
indole-3-butyric acid
- NAA
-naphthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- WPM
Woody Plant Medium (Lloyd & McCown 1980) 相似文献
13.
Cllia Ferreira Adriana N. Capella Roberta Sitnik Walter R. Terra 《Archives of insect biochemistry and physiology》1994,26(4):299-313
In the midgut of Spodoptera frugiperda larvae, subcellular fractionation data suggest that aminopeptidase and part of amylase, carboxypeptidase A, dipeptidase, and trypsin are bound to the microvillar membranes; that major amounts of soluble dipeptidase, cellobiase, and maltase are trapped in the cell glycocalyx; and finally that soluble carboxypeptidase, amylase, and trypsin occur in intracellular vesicles. Most luminal acetylglucosaminidase is soluble and restricted to the ectoperitrophic contents. Aminopeptidase occurs in minor amounts bound to membranes both in the ectoperitrophic contents and incorporated in the peritrophic membrane. Amylase, carboxypeptidase A, and trypsin are found in minor amounts in the ectoperitrophic contents (both soluble and membrane-bound) and in major amounts in the peritrophic membrane with contents. Part of the activities recovered in the last mentioned contents corresponds to enzyme molecules incorporated in the peritrophic membrane. The results suggest that initial digestion is carried out in major amounts by enzymes in the endoperitrophic space and, in minor amounts, by enzymes immobilized in the peritrophic membrane. Intermediate and final digestion occur at the ectoperitrophic space or at the surface of midgut cells. The results also lend support to the hypothesis that amylase and trypsin are derived from membrane-bound forms, are released in soluble form by a microapocrine mechanism, and are partly incorporated into the peritrophic membrane. © 1994 Wiley-Liss, Inc. 相似文献
14.
Karen B. Strier Francisco D. C. Mendes José Rímoli Adriana O. Rímoli 《International journal of primatology》1993,14(4):513-526
We monitored one group of muriquis, or woolly spider monkeys (Brachyteles arachnoides), over a 9-year period at Fazenda Montes Claros, Minas Gerais, Brazil. The group grew from 22 to 42 individuals due to the births of 21 surviving infants. Eight immigrations involving immature females were offset by emigrations and disappearances. The home range of the group expanded as the group size increased. The group traveled as a cohesive unit during the first 6 years of the study, but recently it has begun to show greater tendencies to fission temporarily into smaller subgroups. Six adult males from the other muriqui group at this site have simultaneously increased their associations with the main study group. These observations indicate that the group is in a state of transition which may lead, ultimately, either to its division into two smaller units or to a more fluid social structure. 相似文献
15.
While investigating dinoflagellate cyst assemblages in surface sediments of the Gulfs of Naples and Salerno (Mediterranean Sea), we found a new calcareous resting cyst. This cyst has a round to oval body surrounded by a thick mineral layer, which gives it the shape of a Napoleon hat, with a flat, oval face bearing the archeopyle and a convex keel on the opposite side. The cyst shape is variable in both natural samples and clonal cultures. The organic membrane underlying the calcareous covering is resistant to acetolysis, thus demonstrating the presence of sporopolleninlike material. The cyst germinated into a motile stage having the same morphological features and thecal plate pattern as Peridinium tyrrhenicum Balech. We believe the validity of the genus Pentapharsodinium Indelicato & Loeblich should be accepted. Based on the comparative examination of the species we collected and of a similar species, Pentapharsodinium trachodium Indelicato & Loeblich, we propose Pentapharsodinium tyrrhenicum as a new combination for Peridinium tyrrhenicum. The genus Pentapharsodinium also includes P. dalei Indelicato & Loeblich (= Peridinium faeroense Dale), which produces spiny, organic-walled cysts. The presence of species forming calcareous cysts and species producing noncalcareous cysts in the same genus raises questions about maintaining the family Calciodinellaceae. This family should only include calcareous cyst-forming peridinioids, in order to maintain a unified system of classification of fossil and recent dinoflagellates. 相似文献
16.
Adriana García 《Hydrobiologia》1993,267(1-3):143-154
Only recently have extant Lamprothamnium species been reported from the American continent. L. succinctum (A. Br. in Asch.) R. D. W. was found in Lago Titicaca, Bolivia and L. haesseliae Dont. en Laguna Luro and Laguna La Salada, Argentina.Fossil gyrogonites of L. succinctum and L. haesseliae, however, are here reported to be widely distributed in Quaternary sediments of Argentina, associated with other charophytes, ostracods and foraminiferans. Localities include Laguna del Siasgo, Laguna Salada Grande, Laguna Mar Chiquita, Laguna La Amarga and Salina del Bebedero.
Lamprothamnium is a genus that prefers shallow, alkaline, hyposaline to mesosaline environments. Analysis of the characteristics of Laguna La Salada contributes information on the factors that influence the distribution of the genus.The morphology characteristics of the gyrogonites and oospores of L. haesseliae and the gyrogonites of L. succinctum are described. The use of Lamprothamnium as a biomarker and its application in the reconstruction of Quaternary saline environments are also discussed. 相似文献
17.
Rafael Radi Stephen Sims Adriana Cassina Julio F. Turrens 《Free radical biology & medicine》1993,15(6)
A recent report (Radi et al., J. Biol. Chem. 266:22028–22034, 1991) showed that rat heart mitochondria contain catalase. The protective role of mitochondrial catalase was tested by exposing heart or kidney mitochondria and mitoplasts to two oxidants (H2O2) or tert-butyl hydroperoxide, t-BOOH), estimating lipid peroxidation (as thiobarbituric acid-reactive substances, TBARS) and overall oxidative stress (as chemiluminescence). Additional controls included heart and kidney preparations from aminotriazole-treated (catalase-depleted) rats. Both oxidants increased TBARS in catalase-free preparations to similar extents over their respective controls (between 200 to 350%). In catalase-containing preparations, H2O2 lipid peroxidation increased by only 40 to 96% over controls. Similar qualitative results were obtained when measuring chemiluminescence. The catalytic role of cytochrome c in mitochondrial lipid peroxidation was investigated by exposing either control or cytochrome-c-depleted kidney mitoplasts (catalase free) to either H2O2 or t-BOOH. Hydrogen-peroxide-dependent mitochondrial lipid peroxidation varied with cytochrome c concentrations, remaining close to controls when cytochrome c concentration decreased by 66%, even though there was no catalase present. Tert-butyl hydroperoxide-dependent lipid peroxidation was less affected by cytochrome c remaining 2.3-fold above controls under the same conditions, suggesting that organic peroxides are more likely to remain in the less polar membrane environment being decomposed by heme or nonheme iron imbedded in the inner mitochondrial membrane. Chemiluminescence was less affected by cytochrome c depletion. Comparing control and cytochrome-c-deficient mitochondria, chemiluminescence was 1.7-fold and 2.8-fold higher when control preparations were challenged with t-BOOH or H2O2, respectively. 相似文献
18.
Diana Villegas-Coronado Jesús Adriana Soto-Guzman Juan Manuel Martínez-Soto Nayelli Guadalupe Teran-Saavedra Ana Maria Guzman-Partida Luz Vazquez-Moreno Ana Gloria Villalba-Villalba Amir Maldonado Irlanda Lagarda-Diaz 《化学与生物多样性》2023,20(7):e202300051
Acute monocytic leukemia is a type of myeloid leukemia that develops in monocytes. The current clinical therapies for leukemia are unsatisfactory due to their side effects and nonspecificity toward target cells. Some lectins display antitumor activity and may specifically recognize cancer cells by binding to carbohydrate structures on their surface. Therefore, this study evaluated the response of the human monocytic leukemia cell lines THP-1 to the Olneya tesota PF2 lectin. The induction of apoptosis and reactive oxygen species production in PF2-treated cells was evaluated by flow cytometry, and the lectin-THP-1 cell interaction and mitochondrial membrane potential were evaluated by confocal fluorescence microscopy. PF2 genotoxicity was evaluated by DNA fragmentation analysis via gel electrophoresis. The results showed that PF2 binds to THP-1 cells, triggers apoptosis and DNA degradation, changes the mitochondrial membrane potential, and increases reactive oxygen species levels in PF2-treated THP-1 cells. These results suggest the potential use of PF2 for developing alternative anticancer treatments with enhanced specificity. 相似文献
19.
Juan José Pierella Karlusich Eric Pelletier Lucie Zinger Fabien Lombard Adriana Zingone Sébastien Colin Josep M. Gasol Richard G. Dorrell Nicolas Henry Eleonora Scalco Silvia G. Acinas Patrick Wincker Colomban de Vargas Chris Bowler 《Molecular ecology resources》2023,23(1):16-40
Phytoplankton account for >45% of global primary production, and have an enormous impact on aquatic food webs and on the entire Earth System. Their members are found among prokaryotes (cyanobacteria) and multiple eukaryotic lineages containing chloroplasts. Genetic surveys of phytoplankton communities generally consist of PCR amplification of bacterial (16S), nuclear (18S) and/or chloroplastic (16S) rRNA marker genes from DNA extracted from environmental samples. However, our appreciation of phytoplankton abundance or biomass is limited by PCR-amplification biases, rRNA gene copy number variations across taxa, and the fact that rRNA genes do not provide insights into metabolic traits such as photosynthesis. Here, we targeted the photosynthetic gene psbO from metagenomes to circumvent these limitations: the method is PCR-free, and the gene is universally and exclusively present in photosynthetic prokaryotes and eukaryotes, mainly in one copy per genome. We applied and validated this new strategy with the size-fractionated marine samples collected by Tara Oceans, and showed improved correlations with flow cytometry and microscopy than when based on rRNA genes. Furthermore, we revealed unexpected features of the ecology of these ecosystems, such as the high abundance of picocyanobacterial aggregates and symbionts in the ocean, and the decrease in relative abundance of phototrophs towards the larger size classes of marine dinoflagellates. To facilitate the incorporation of psbO in molecular-based surveys, we compiled a curated database of >18,000 unique sequences. Overall, psbO appears to be a promising new gene marker for molecular-based evaluations of entire phytoplankton communities. 相似文献
20.