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  • 1
    Electronic Resource
    Electronic Resource
    The influence of whole lake aeration on the limnology of a hypereutrophic lake in central Florida (1987)
    Springer
    Hydrobiologia 148 (1987), S. 3-24 
    Details
    ISSN: 1573-5117
    Keywords: lake restoration ; artificial destratification ; limnology ; subtropical lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the influence of a multiple inversion aeration system upon the limnology of a small sinkhole lake, we monitored physical-chemical and biological parameters for 15 months prior to starting aeration and for 24 months thereafter. Aeration eliminated thermal stratification and dissolved oxygen concentrations of bottom waters increased significantly. Secchi disk transparency increased during aeration while turbidity, pH, alkalinity, total nitrogen, hydrogen sulfide and iron concentrations decreased significantly. Primary production and mean chlorophyll a did not change significantly during aeration but total phytoplankton cell volume decreased 2-fold. This decrease was caused by a marked reduction in blue-green algae which appears to be attributable to rapid mixing of the lake and to decreases in the pH. Cell volumes of green algae remained constant but numbers of taxa increased 70%. Densities of crustacean zooplankton were reduced markedly by aeration while densities of rotifers increased significantly during the first year but then returned to preaeration levels during the second year. Large-bodied cladocerans were replaced by small-bodied forms during aeration, and copepod populations became dominated by nauplii (97%). Densities of benthic macroinvertebrates declined 2-fold during aeration due to to a marked reduction (10-fold) in the Chaoborus population which correlated strongly with decreases in crustacean zooplankton abundance. The total number of taxa collected on individual sample dates increased throughout the two year aeration period (from 12 to 25) and chironomids became the predominant group (70%). The multiple inversion aeration system successfully eliminated many of the undesirable features of eutrophication (e.g., oxygen depletion, blue-green algal blooms, low benthic diversity), but it did not change the trophic state. Aeration of hypereutrophic lakes for multiple years may be necessary to maintain desired conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018162
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  • 2
    Electronic Resource
    Electronic Resource
    Transfection of heteroduplexes containing uracil · guanine or thymine · guanine mispairs into plant cells (1992)
    Springer
    Plant molecular biology 20 (1992), S. 123-131 
    Details
    ISSN: 1573-5028
    Keywords: DNA methylation ; 5-methylcytosine ; uracil excision ; DNA mismatch repair ; geminivirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have compared the fate of U · G mispairs or analogous T · G mispairs in DNA heteroduplexes transfected into tobacco protoplasts. The heteroduplex DNA consisted of tomato golden mosaic virus DNA sequences in theEscherichia coli vectors pUC118 or pUC119. After transfection, the mismatched U residues were lost with an efficiency of greater than 95%, probably as a result of the uracil-DNA glycosylase pathway for excision of U residues in any sequence context. In contrast to the preferential removal of the mispaired U residues, biased removal of T residues from analogous heteroduplexes was not seen in the transfected plant cells. Also, we investigated the effect of extensively methylating one strand of the heteroduplex DNA used for transfection. Surprisingly, such methylation resulted in highly biased loss of the mismatched base from the 5-methylcytosine-rich strand of T · G-containing heteroduplexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029155
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  • 3
    Electronic Resource
    Electronic Resource
    Independent encapsidation of tomato golden mosaic virus A component DNA in transgenic plants (1987)
    Springer
    Plant molecular biology 8 (1987), S. 477-484 
    Details
    ISSN: 1573-5028
    Keywords: geminivirus ; Ti-plasmid ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tomato golden mosaic virus (TGMV), a member of the geminivirus group, has a genome consisting of two DNA molecules designated the A and B components. Both are required for infectivity in healthy plants, although the former has been shown to replicate independently in transgenic plants containing tandem direct repeats of the A genome component. In the studies presented here, petunia plants transgenic for either both components (A×B hybrids) or the A component alone were examined for the presence of virus particles and encapsidated, single stranded viral DNA. The results of DNase protection experiments and direct observation of extracts from transgenic plants by electron microscopy indicate that single stranded TGMV DNA is in both cases packaged into paired particles identical to those obtained from virus-infected plants. DNase-treated virions isolated from A×B hybrid petunia are infectious when inoculated onto healthy Nicotiana benthamiana. Likewise, virions obtained from transgenic A petunia are infectious for plants transgenic for the B component. Our observations of TGMV replication in transgenic plants indicate that TGMV A DNA encodes all viral functions necessary for the replication and encapsidation of viral DNA. The possible role of the B component in TGMV replication is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017993
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  • 4
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated inoculation of plants with tomato golden mosaic virus DNAs (1988)
    Springer
    Plant molecular biology 10 (1988), S. 225-234 
    Details
    ISSN: 1573-5028
    Keywords: geminivirus ; Agrobacterium ; tomato golden mosaic virus ; agroinoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have adapted the “agroinfection” procedure of Grimsley and co-workers [4,5] to develop a simple, efficient, reproducible infectivity assay for the insect-transmitted, split-genome geminivirus, tomato golden mosaic virus (TGMV). Agrobacterium T-DNA vectors provide efficient delivery of both components of TGMV when used in mixed inoculation of wild-type host plants. A greater increase in infection efficiency can be obtained by Agrobacterium delivery of the TGMV A component to “permissive” transgenic plants. These “permissive” plants contain multiple tandem copies of the B component integrated into the host genome. An inoculum containing as few as 2000 Agrobacterium cells can produce 100% infection under these conditions. Further, our results show that there is a marked effect of the configuration of the TGMV A components within the T-DNA vector on time of symptom development. We have also found that transgenic plants carrying tandem copies of the A component do not complement the B component. Possible mechanisms to explain these results and the potential use of this system to further study the functions of the geminivirus components in infection are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027399
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  • 5
    Electronic Resource
    Electronic Resource
    DNA methylation inhibits propagation of tomato golden mosaic virus DNA in transfected protoplasts (1992)
    Springer
    Plant molecular biology 18 (1992), S. 703-712 
    Details
    ISSN: 1573-5028
    Keywords: DNA methylation ; geminivirus ; protoplasts ; tomato golden mosaic virus ; transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of methylation on plant viral DNA replication have been studied inNicotiana tabacum protoplasts transfected with DNA of the geminivirus tomato golden mosaic virus (TGMV). The transfected cells were also used to determine whether experimentally introduced methylation patterns are maintained in extrachromosomal viral DNA. Replacement of cytosine residues with 5-methylcytosine (m5C) reduced the amount of viral DNA which accumulated in transfected protoplasts. The reduction was observed whether m5C residues were substituted for cytosine residuesin vitro in either the viral strand or the complementary strand of double-stranded circular inoculum DNAs containing tandemly repeated copies of the A component of the TGMV genome. Both limited and extensive cytosine methylation of TGMV DNA sequencesin vitro was not propagated in progeny viral DNA. The absence of detectable maintenance-type methylation of the transfecting TGMV DNA sequences may be related to the lack of methylation observed in double-stranded TGMV DNA isolated from infected plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020012
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  • 6
    Electronic Resource
    Electronic Resource
    Photocontrol of organelle and cell type specific changes in the polypeptide composition of Euglena and sorghum (1988)
    Weinheim : Wiley-Blackwell
    Electrophoresis 9 (1988), S. 764-773 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional (2-D) gel electrophoresis has been used to follow changes in cell type specific and organelle localized polypeptides upon exposure of etiolated sorghum shoots and dark-grown resting Euglena to light. Total protein extracted from isolated bundle sheath strands and mesophyll protoplasts was resolved by 2-D gel electrophoresis. The cell type specific polypeptides were localized on the whole shoot 2-D gel map in order to determine changes in the levels of these polypeptides upon light exposure. An image analyzer was used to analyze fluorographs of 2-D gels of total Euglena protein pulse-labeled with [35S]sulfate in the dark, immediately upon light exposure and 1, 4, 14, 24, 48 and 72 h after light exposure. The subset of polypeptides whose relative rats of synthesis changes more than threefold immediately upon light exposure was i dentified. The different patterns of changes in the rate of synthesis of this subset of polypeptides were followed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150091112
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