Biomedical subjects

F D Guerrero

Publications and source records attributed to F D Guerrero.

23 records · Page 2Linked to original sources

PubMed1993

Tissue-specific expression of a plant turgor-responsive gene with amino acid sequence homology to transport-facilitating proteins.

We report the isolation of a turgor-responsive gene of pea, trg-31, whose transcription induced within 30 min after the loss of leaf turgor. Structure of the coding region and 1.4 kb of 5' untranslated region was determined by DNA sequencing. A 3 kb promoter fragment from trg-31 was fused to a beta-glucuronidase (GUS) reporter gene in pBI101, tobacco leaf disks and mature plants analyzed for turgor-responsive induction of GUS mRNA. Significant amino acid sequence homology exists between trg-31 and putative transport proteins of bovine, Phaseolus, soybean and Escherichia coli membranes.

Amino Acid Sequence↗

PubMed1990

Turgor-responsive gene transcription and RNA levels increase rapidly when pea shoots are wilted. Sequence and expression of three inducible genes.

Reduction of turgor in pea shoots caused the accumulation of several poly(A) RNAs. cDNA clones derived from three different poly(A) RNAs which accumulate in wilted pea shoots were isolated, sequenced and expression of the corresponding genes examined. Clone 7a encoded a 289 amino acid protein. The C-terminal 180 amino acids of this protein were homologous to soybean nodulin-26. RNA hybridizing to cDNA 7a was abundant in roots, and induced in shoots by dehydration, heat shock and to a small extent by ABA. Hydropathic plots indicate that the protein encoded by cDNA 7a contains six potential membrane spanning domains similar to proteins which form ion channels. Clone 15a encoded a 363 amino acid protein with high homology to cysteine proteases. RNA hybridizing to cDNA 15a was more abundant in roots than shoots of control plants. Dehydration of pea shoots induced cDNA 15a mRNA levels whereas heat shock or ABA treatment did not. Clone 26g encoded a 508 amino acid protein with 30% residue identity to several aldehyde dehydrogenases. RNA hybridizing to cDNA 26g was induced by dehydration of shoots but not roots and heat shock and ABA did not modulate RNA levels. Levels of the three poly(A) RNAs increased 4-6-fold by 4 h after wilting and this increase was not altered by pretreatment of shoots with cycloheximide. When wilted shoots were rehydrated, RNA hybridizing to cDNA 26g declined to pre-stress levels within 2 h. Run-on transcription experiments using nuclei from pea shoots showed that transcription of the genes which encode the three poly(A) RNAs was induced within 30 min following reduction of shoot turgor. One of the genes showed a further increase in transcription by 4 h after dehydration whereas transcription of the other 2 genes declined. These results indicate that plant cells respond to changes in cell turgor by rapidly increasing transcription of several genes. Furthermore, the expression of the turgor-responsive genes varies with respect to the time course of induction and reversibility of the wilting-induced changes.

Amino Acid Sequence↗

PubMed1990

Promoter sequences from a maize pollen-specific gene direct tissue-specific transcription in tobacco.

A set of 5' promoter deletions from Zmg13, a genomic clone of a pollen-specific gene of maize, has been transcriptionally fused to a beta-glucuronidase (GUS) reporter gene in the binary vector pBI101. Tobacco leaf disks were transformed and mature plants analyzed for GUS activity directed by the Zmg13 promoter constructs. Transgenic plants containing the 375 bp Zmg13 sequence from -314 to +61 relative to the transcription start site transcribed GUS RNA and expressed active GUS enzyme in mature pollen but not in leaves. Plants transformed with a 35S CaMV promoter-GUS transcriptional fusion expressed GUS RNA in leaves but not in pollen. Neither GUS RNA or active enzyme could be detected in pollen or leaves from plants containing a 124 bp Zmg13-GUS transcriptional fusion missing the putative Zmg13 TATA box. No GUS RNA or enzyme expression was not detected in non-transformed tobacco. RNA and GUS histochemical analysis of the T1 generation confirmed that the temporal expression pattern of Zmg13-GUS transcription in tobacco followed that of the native gene in maize and that the Zmg13 promoter sequences from the maize gene are able correctly to direct genetically stable, tissue-specific gene expression in transgenic tobacco plants.

Base Sequence↗

PubMed1988

Reduction of turgor induces rapid changes in leaf translatable RNA.

The turgor of pea (Pisum sativum) leaves was reduced by exposing excised pea shoots to a stream of 23 degrees C air for 20 min. Poly(A)(+) RNA was isolated from control and wilted shoots, translated in vitro and radiolabeled translation products separated by electrophoresis on two-dimensional (isoelectric focusing-sodium dodecyl sulfate) polyacrylamide gels. This analysis showed that the levels of several poly(A)(+) RNAs increased in wilted plants. Most of the poly(A)(+) RNAs induced in wilted plants did not accumulate in response to heat shock or exogenously applied ABA even though endogenous ABA levels were found to increase in shoots 30 min after wilting and by 4 h had increased 50-fold (1 versus 0.02 microgram per gram fresh weight). A lambdagt10 cDNA library was constructed using poly(A)(+) RNA from wilted shoots which had been incubated for 4 hours. Differential screening of the library identified four clones corresponding to poly(A)(+) RNAs which are induced in wilted shoots.

Journal Article↗

PubMedDate not supplied

Toxicological and molecular characterization of pyrethroid-resistant horn flies, Haematobia irritans: identification of kdr and super-kdr point mutations.

Two pyrethroid-resistant strains of horn flies were found to be 17- and 688-fold more resistant to permethrin and 17- and 11,300-fold more resistant to cyhalothrin than a susceptible control strain. Synergism experiments with piperonyl butoxide showed that both target site insensitivity and metabolic resistance mechanisms were present in the Super Resistant strain. Using the reverse transcriptase-polymerase chain reaction (RT-PCR), a 0.9 kb fragment of the putative sodium channel gene from susceptible and resistant flies was cloned and sequenced. Two sequence variants were detected, presumably arising from alternative splicing of transcripts. The amino acid sequences deduced from the resistant and susceptible fly gene fragments were identical except for three amino acid substitutions, two of which have been associated with resistance in house flies. A leucine to phenylalanine substitution associated with knockdown resistance (kdr) was found in both resistant strains. A methionine to threonine substitution associated with super-kdr was found in the Super Resistant strain. Translation of poly(A)+ RNA followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) detected translation products whose concentrations increased in association with pyrethroid resistance. Random-amplified polymorphic DNA (RAPD)-PCR of genomic DNA with over 260 DNA oligomers yielded one resistance-associated marker, designated HF-77, which was not detected in any susceptible flies but was present in 16% of the resistant individuals.

Amino Acid Sequence↗