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At least 37 records · Page 2Linked to original sources
PubMed1989

CO(2) and O(2) Exchanges in the CAM Plant Ananas comosus (L.) Merr: Determination of Total and Malate-Decorboxylation-Dependent CO(2)-Assimilation Rates; Study of Light O(2)-Uptake.

Photosynthesis and light O(2)-uptake of the aerial portion of the CAM plant Ananas comosus (L.) merr. were studied by CO(2) and O(2) gas exchange measurements. The amount of CO(2) which was fixed during a complete day-night cycle was equal to the amount of total net O(2) evolved. This finding justifies the assumption that in each time interval of the light period, the difference between the rates of net O(2)-evolution and of net light atmospheric CO(2)-uptake give the rates of malate-decarboxylation-dependent CO(2) assimilation. Based upon this hypothesis, the following photosynthetic characteristics were observed: (a) From the onset of the light to midphase IV of CAM, the photosynthetic quotient (net O(2) evolved/net CO(2) fixed) was higher than 1. This indicates that malate-decarboxylation supplied CO(2) for the photosynthetic carbon reduction cycle during this period. (b) In phase III and early phase IV, the rate of CO(2) assimilation deduced from net O(2)-evolution was 3 times higher than the maximum rate of atmospheric CO(2)-fixation during phase IV. A conceivable explanation for this stimulation of photosynthesis is that the intracellular CO(2)-concentration was high because of malate decarboxylation. (c) During the final hours of the light period, the photosynthetic quotient decreased below 1. This may be the result of CO(2)-fixation by phosphoenolpyruvate-carboxylase activity and malate accumulation. Based upon this hypothesis, the gas exchange data indicates that at least 50% of the CO(2) fixed during the last hour of the light period was stored as malate. Light O(2)-uptake determined with (18)O(2) showed two remarkable characteristics: from the onset of the light until midphase IV the rate of O(2)-uptake increased progressively; during the following part of the light period, the rate of O(2)-uptake was 3.5 times higher than the maximum rate of CO(2)-uptake. When malate decarboxylation was reduced or suppressed after a night in a CO(2)-free atmosphere or in continuous illumination, the rate of O(2)-uptake was higher than in the control. This supports the hypothesis that the low rate of O(2)-uptake in the first part of the light period is due to the inhibition of photorespiration by increased intracellular CO(2) concentration because of malate decarboxylation. In view of the law of gas diffusion and the kinetic properties of the ribulose-1,5-bisphosphate carboxylase/oxygenase, O(2) and CO(2) gas exchange suggest that at the end of the light period the intracellular CO(2) concentration was very low. We propose that the high ratio of O(2)-uptake/CO(2)-fixation is principally caused by the stimulation of photorespiration during this period.

Journal Article↗
PubMed2001

16S ribosomal DNA characterization of nitrogen-fixing bacteria isolated from banana (Musa spp.) and pineapple (Ananas comosus (L.) Merril).

Nitrogen-fixing bacteria isolated from banana (Musa spp.) and pineapple (Ananas comosus (L.) Merril) were characterized by amplified 16S ribosomal DNA restriction analysis and 16S rRNA sequence analysis. Herbaspirillum seropedicae, Herbaspirillum rubrisubalbicans, Burkholderia brasilensis, and Burkholderia tropicalis were identified. Eight other types were placed in close proximity to these genera and other alpha and beta Proteobacteria.

Alphaproteobacteria↗
PubMed1993

Large-scale production and purification of an Erwinia ananas ice nucleation protein and evaluation of its ice nucleation activity.

The ice nucleation-active protein of Erwinia ananas IN-10 (inaA protein) was over-expressed as inclusion bodies in Escherichia coli in a yield of 15.3 mg of inaA protein from 60 mg of bacterial cells on a dry-matter basis. The inaA protein was purified from the inclusion bodies by solubilization with detergents to obtain a protein preparation free from sugar and lipid. This preparation had a distinct ice nucleation activity, indicating that the inaA protein per se is able to act as a nucleus.

Amino Acid Sequence↗
PubMed2002

Response of the ice-nucleating bacterium Pantoea ananas KUIN-3 during cold acclimation.

The ice-nucleating bacterium Pantoea ananas KUIN-3 accumulated glucose in cells following a shift in temperature (10 degrees C) from the optimum growth temperature (30 degrees C). This accumulation might be caused by the activation of glucose-6-phosphatase. Although this strain after culturing at 30 degrees C was harmed by freezing, the cryotolerance of this strain was reached about 80% after cold acclimation at 10 degrees C.

Acclimatization↗
PubMed2003

Enzymatic browning and biochemical alterations in black spots of pineapple [Ananas comosus (L.) Merr.].

Penicillium funiculosum Thom. was consistently isolated from pineapple-infected fruitlet (black spots). Polyphenol oxidase, peroxidase, and laccase activities were determined in extracts from contiguous and infected fruitlets. Healthy fruitlets showed a rather high level of polyphenol oxidase (optimum pH 7.0), and this activity was tremendously increased (X 10) in contiguous infected fruitlets. Furthermore, infected fruitlets also exhibited laccase activity (optimum pH 4.0), while peroxidase was rather constant in both fruitlets. Browning reactions were attributed to qualitative and quantitative modifications of the enzymatic equipment (polyphenol oxidase and laccase) (p < 0.0001). In infected fruiltets, sucrose and L-malic acid were present at significantly lower amounts than in healthy ones, likely owing to fungal metabolism (p < 0.0001), whereas cell wall material was three times higher, which could be viewed as a defense mechanism to limit expansion of the mycelium.

Ananas↗
PubMed2006

Silencing of the ACC synthase gene ACACS2 causes delayed flowering in pineapple [Ananas comosus (L.) Merr.].

Flowering is a crucial developmental stage in the plant life cycle. A number of different factors, from environmental to chemical, can trigger flowering. In pineapple, and other bromeliads, it has been proposed that flowering is triggered by a small burst of ethylene production in the meristem in response to environmental cues. A 1-amino-cyclopropane-1-carboxylate synthase (ACC synthase) gene has been cloned from pineapple (ACACS2), which is induced in the meristem under the same environmental conditions that induce flowering. Two transgenic pineapple lines have been produced containing co-suppression constructs designed to down-regulate the expression of the ACACS2 gene. Northern analysis revealed that the ACACS2 gene was silenced in a number of transgenic plants in both lines. Southern hybridization revealed clear differences in the methylation status of silenced versus non-silenced plants by the inability of a methylation-sensitive enzyme to digest within the ACACS2 DNA extracted from silenced plants, indicating that methylation is the cause of the observed co-suppression of the ACACS2 gene. Flowering characteristics of the transgenic plants were studied under field conditions in South East Queensland, Australia. Flowering dynamics studies revealed significant differences in flowering behaviour, with transgenic plants exhibiting silencing showing a marked delay in flowering when compared with non-silenced transgenic plants and control non-transformed plants. It is argued that the ACACS2 gene is one of the key contributors towards triggering 'natural flowering' in mature pineapples under commercial field conditions.

Ananas↗
PubMed2005

Odor-active constituents in fresh pineapple (Ananas comosus [L.] Merr.) by quantitative and sensory evaluation.

By application of aroma extract dilution analysis (AEDA) to an aroma distillate prepared from fresh pineapple using solvent-assisted flavor evaporation (SAFE), 29 odor-active compounds were detected in the flavor dilution (FD) factor range of 2 to 4,096. Quantitative measurements performed by stable isotope dilution assays (SIDA) and a calculation of odor activity values (OAVs) of 12 selected odorants revealed the following compounds as key odorants in fresh pineapple flavor: 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDF; sweet, pineapple-like, caramel-like), ethyl 2-methylpropanoate (fruity), ethyl 2-methylbutanoate (fruity) followed by methyl 2-methylbutanoate (fruity, apple-like) and 1-(E,Z)-3,5-undecatriene (fresh, pineapple-like). A mixture of these 12 odorants in concentrations equal to those in the fresh pineapple resulted in an odor profile similar to that of the fresh juice. Furthermore, the results of omission tests using the model mixture showed that HDF and ethyl 2-methylbutanoate are character impact odorants in fresh pineapple.

Ananas↗
PubMed2005

Tissue distribution, synthesis stage, and ethylene induction of pineapple (Ananas comosus) chitinases.

We examined the tissue distribution, synthesis stage, and ethylene induction of three types of pineapple chitinase using chitinase activity gel and immunoblot analysis. Type A (acidic class III) exists in all tissues, while type B (weakly basic class I, which has strong antifungal activity) and type C (acidic class I) are localized mainly in the leaf and stem. In a pericarp, type A exists at all stages during fruit development, while type B and type C exist only at the early stage. Synthesis of type A is induced by ethylene, while that of types B and C is not affected by it. These results suggest that the physiological roles of these three types of chitinase in pineapple are different.

Ananas↗
PubMedDate not supplied

Modulation of murine tumor growth and colonization by bromelaine, an extract of the pineapple plant (Ananas comosum L.).

The antitumor and antimetastatic activities of the plant cysteine endoproteinase bromelaine were evaluated in a murine model. Syngeneic sarcoma L-1 cells were incubated with bromelaine (after preceeding time and dosage kinetics) and subcutaneously; (s.c.) or intravenously; (i.v.) inoculated into BALB/c-mice (n = 5 per experimental group) to induce local tumor growth or lung colonization. Compared to non-protease incubated L-1 cells, local tumor growth and experimental lung metastasis decreased significantly (p < 0.05). After bromelaine incubation of the tumor cells. Sarcoma L-1 cells induced local tumor growth after s.c. inoculation and lung colonization after i.v. injection. Intraperitoneal (i.p.) or s.c. administration of bromelaine (optimal dosage and time schedule tested in preceeding kinetic studies) significantly (p < 0.05) reduced local tumor weight, however, lung colonization was non-significantly reduced. Bromelaine incubation of sarcoma L-1 cells significantly reduced their tumorigenic/metastatic capacities. Bromelaine treatment after tumor cell inoculation significantly reduced local tumor growth, experimental lung metastasis, however, to a lesser, non-significant degree.

Ananas↗
PubMed2006

[Studies on phenolic constituents from leaves of pineapple (Ananas comosus)].

OBJECTIVE: To study the phenolic constituents of the leaves of pineapple. METHOD: Chromatographic methods were used to isolate compounds from the leaves of pineapple and spectroscopic methods were used to identify the structures of the isolated compounds. RESULT: 7 compounds, ananasate (1), 1-O-caffeoylglycerol (2), 1-O-p-coumaroylglycerol (3), caffeic acid (4), p-coumaric acid (5), beta-sitosterol (6) and daucosterol (7), were isolated from the leaves of pineapple. CONCLUSION: 1 was a new compound, and others were obtained from this plant for the first time.

Ananas↗
PubMedDate not supplied

Bromelain, the enzyme complex of pineapple (Ananas comosus) and its clinical application. An update.

After a short description of the uses of pineapple as folk medicine by the natives of the tropics, the more important new pharmaceutical applications of bromelain, reported between 1975 and 1978, are presented. Although the exact chemical structure of all active components of bromelain is not fully determined, this substance has shown distinct pharmacological promise. Its properties include: (1) interference with growth of malignant cells; (2) inhibition of platelet aggregation; (3) fibrinolytic activity; (4) anti-inflammatory action; (5) skin debridement properties. These biological functions of bromelain, a non-toxic compound, have therapeutic values in modulating: (a) tumor growth; (b) blood coagulation; (c) inflammatory changes; (d) debridement of third degree burns; (e) enhancement of absorption of drugs. The mechanism of action of bromelain affecting these varied biological effects relates in part to its modulation of the arachidonate cascade.

Anti-Inflammatory Agents↗
PubMed2002

Two selective novel triterpene glycosides from sea cucumber, Telenata Ananas: inhibitors of chemokine receptor-5.

The aqueous methanolic extract of a sea cucumber was found to contain two triterpene glycosides 1 and 2. The structures of 1 and 2 were established based on high-resolution NMR studies. Compounds 1 and 2 exhibited inhibitory activity (K(i)) of 30 and 5microM, respectively, in a chemokine receptor subtype 5 (CCR5) assay. Both compounds did not show any significant inhibition in a CXCR2 assay at 50microM, suggesting their selectivity for the CCR5 receptor.

Animals↗