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An YQ, McDowell JM, Huang S, McKinney EC, Chambliss S, Meagher RB. Strong, constitutive expression of the Arabidopsis ACT2/ACT8 actin subclass in vegetative tissues. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1996; 10:107-21. [PMID: 8758981 DOI: 10.1046/j.1365-313x.1996.10010107.x] [Citation(s) in RCA: 216] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Arabidopsis has a complex and ancient actin gene family encoding six divergent subclasses of proteins. One subclass is represented by ACT2 and ACT8, which encode nearly identical proteins. These two genes differ significantly in flanking and intron sequences and in silent nucleotide positions within codons. Gene-specific RNA gel blot hybridization and reverse transcriptase-mediated polymerase chain reaction (RT-PCR) assays showed that ACT2 and/or ACT8mRNAs were coordinately and strongly expressed in leaves, roots, stems, flowers, pollen, and siliques. Together they account for greater than 80% of the actin mRNA in most Arabidopsis organs. The 5' flanking regions, including the promoter, the mRNA leader exon, an intron in the mRNA leader, and the first 19 codons, were coupled to a beta-glucuronidase (GUS) reporter gene and transformed into Arabidopsis. The ACT2/GUS construct was expressed strongly in nearly all the vegetative tissues in seedlings, juvenile plants, and mature plants. These activities persisted in older tissues. Little or no expression was observed in seed coats, hypocotyls, gynoecia, or pollen sacs. In contrast, the expression of the ACT8/GUS construct was weaker. It was observed only in a subset of the organs and tissues expressing ACT2/GUS and was not significantly expressed in the flower. ACT2, ACT8, and ACT8/GUS mRNAs were present at moderate to high levels in pollen, and yet neither ACT2/GUS nor ACT8/GUS enzyme expression could be detected in pollen. This suggested a mechanism of translational control affecting ACT2 and ACT8 expression in some tissues. The conservation of protein sequence and overlapping patterns of expression, in spite of significant DNA sequence divergence, suggests that the function and regulation of these two genes have been conserved during the evolution of the Brassicaceae.
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McDowell JM, An YQ, Huang S, McKinney EC, Meagher RB. The arabidopsis ACT7 actin gene is expressed in rapidly developing tissues and responds to several external stimuli. PLANT PHYSIOLOGY 1996; 111:699-711. [PMID: 8754679 PMCID: PMC157885 DOI: 10.1104/pp.111.3.699] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
ACT7 encodes one of the six distinct and ancient subclasses of actin protein in the complex Arabidopsis actin gene family. We determined the sequence and structure of the Arabidopsis thaliana ACT7 actin gene and investigated its tissue-specific expression and regulation. The ACT7 mRNA levels varied by 128-fold among several different tissues and organs. The highest levels of aCT7 mRNA were found in rapidly expanding vegetative organs, the lowest in pollen. A translational fusion with the 5' end of ACT 7 (1.9 kb) joined to the beta-glucuronidase reporter gene was strongly and preferentially expressed in all young, developing vegetative tissues of transgenic Arabidopsis plants. ACT7 was the only Arabidopsis actin gene strongly expressed in the hypocotyl and seed coat. Although no beta-glucuronidase expression was seen in developing ovules or immature seeds, strong expression was seen in dry seeds and immediately after imbibition in the entire seedling. ACT7 was the only Arabidopsis actin gene to respond strongly to auxin, other hormone treatments, light regime, and wounding, and may be the primary actin gene responding to external stimuli. The ACT7 promoter sequence contains a remarkable number of motifs with sequence similarity to putative phytohormone response elements.
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Abstract
Recent studies suggest that plant disease-resistance responses use multiple signaling pathways acting subsequent to pathogen recognition, and that phosphorylation cascades play a prominent role in the recognition and execution of foreign invaders.
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Huang S, McDowell JM, Weise MJ, Meagher RB. The Arabidopsis profilin gene family. Evidence for an ancient split between constitutive and pollen-specific profilin genes. PLANT PHYSIOLOGY 1996; 111:115-26. [PMID: 8685262 PMCID: PMC157818 DOI: 10.1104/pp.111.1.115] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Profilin is a ubiquitous eukaryotic protein that regulates the actin cytoskeleton and recently has been identified as a potent allergen in pollen. We examined the profilin gene family in the model plant, Arabidopsis thaliana, and found that it contained approximately 8 to 10 members. Four distinct profilin sequences, three cDNAs, PRF1, PRF2, and PRF3, and two genomic clones, PRF1 and PRF4, were isolated and characterized. These genes encoded four distinct profilin isoforms of 131 to 134 amino acids. Northern and reverse-transcriptase polymerase chain reaction analyses demonstrated that Arabidopsis PRF1 was expressed in all major plant organs, whereas PRF4 was specifically expressed in mature pollen. Gene trees constructed from amino acid sequence data revealed the presence of two ancient, distinct profilin gene classes in plants. PRF4 was in a class with previously identified pollen-specific profilins from monocot and dicot species. PRF1, PRF2, PRF3, and a distant dicot sequence formed a separate novel class, suggesting an ancient separation of plant profilins based on regulation and perhaps function. The coevolution of plant actin and profilin classes with similar patterns of expression is discussed. The similarity of plant, fungal, protist, insect, and nematode profilins and their extreme divergence from the vertebrate profilins has striking implications for the evolution of fungal-spore- and plant-pollen-profilins as allergens.
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McDowell JM, Huang S, McKinney EC, An YQ, Meagher RB. Structure and evolution of the actin gene family in Arabidopsis thaliana. Genetics 1996; 142:587-602. [PMID: 8852856 PMCID: PMC1206991 DOI: 10.1093/genetics/142.2.587] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Higher plants contain families of actin-encoding genes that are divergent and differentially expressed. Progress in understanding the functions and evolution of plant actins has been hindered by the large size of the actin gene families. In this study, we characterized the structure and evolution of the actin gene family in Arabidopsis thaliana. DNA blot analyses with gene-specific probes suggested that all 10 of the Arabidopsis actin gene family members have been isolated and established that Arabidopsis has a much simpler actin gene family than other plants that have been examined. Phylogenetic analyses suggested that the Arabidopsis gene family contains at least two ancient classes of genes that diverged early in land plant evolution and may have separated vegetative from reproductive actins. Subsequent divergence produced a total of six distinct subclasses of actin, and five showed a distinct pattern of tissue specific expression. The concordance of expression patterns with the phylogenetic structure is discussed. These subclasses appear to be evolving independently, as no evidence of gene conversion was found. The Arabidopsis actin proteins have an unusually large number of nonconservative amino acid substitutions, which mapped to the surface of the actin molecule, and should effect protein-protein interactions.
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An YQ, Huang S, McDowell JM, McKinney EC, Meagher RB. Conserved expression of the Arabidopsis ACT1 and ACT 3 actin subclass in organ primordia and mature pollen. THE PLANT CELL 1996; 8:15-30. [PMID: 8597657 PMCID: PMC161078 DOI: 10.1105/tpc.8.1.15] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We have proposed that ancient and divergent classes of plant actin genes have been preserved throughout vascular plant evolution, because they have distinct patterns of gene regulation. The hypothesis was explored for ACT1 and ACT3, which represent one of the six ancient subclasses in the Arabidopsis actin gene family. Comparison of ACT1 and ACT3 cDNA and genomic sequences revealed highly divergent flaking and intron sequences, whereas they encoded nearly identical proteins. Quantification of their level of divergence suggests that they have not shared a common ancestor for 30 to 60 million years. Gene-specific RNA gel blot hybridization and reverse transcriptase-polymerase chain reaction analyses demonstrated that the distribution of ACT1 and ACT3 mRNAs was very similar: both preferentially accumulated at high levels in mature pollen and at very low levels in the other major organs. The 5' flanking regions of both genes, including the promoter, leader exon and intron, and the first 19 condons, were fused to the beta-glucuronidase (GUS) reporter gene. The expression of these reporter fusions was examined in a large number of transgenic Arabidopsis plants. Histochemical assays demonstrated that both ACT1-GUS and ACT3-GUS constructs were expressed preferentially in pollen, pollen tubes, and in all organ primordia, including those in roots shoots, and the inflorescence. Comparison of the 5' flanking regions of ACT1 and ACT3 revealed a number of short conserved sequences, which may direct their common transcriptional and post-transcriptional regulation. The expression patterns observed were distinct from those of any other other Arabidopsis actin subclass. The conservation of their expression pattern and amino acid sequences suggests that this actin subclass plays a distinct and required role in the plant cytoskeleton.
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McKinney EC, Ali N, Traut A, Feldmann KA, Belostotsky DA, McDowell JM, Meagher RB. Sequence-based identification of T-DNA insertion mutations in Arabidopsis: actin mutants act2-1 and act4-1. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1995; 8:613-22. [PMID: 7496405 DOI: 10.1046/j.1365-313x.1995.8040613.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A method is presented to facilitate the isolation of mutations in plant genes, which requires knowledge of the target gene or protein sequence, and is independent of mutant phenotype. The polymerase chain reaction was used to amplify the junctions between a T-DNA insert and the gene of interest from pools of mutant plant lines. The approach was used to identify mutations in Arabidopsis thaliana actin genes. The Arabidopsis genome encodes 10 actins in six ancient subclasses each with distinct expression patterns. Primers in the T-DNA border and highly degenerate actin primers, designed from conserved amino acid motifs, were used to prime the amplification. The PCR products were transferred to filters and probed for actin at low stringency. Thus, mutations in all 10 actin genes were screened for simultaneously. Mutations in the vegetative constitutive actin gene, ACT2, and the pollen-specific actin gene, ACT4, were identified in a population of 5300 lines containing approximately 1.5 T-DNA insertions per line. The screen was sensitive enough that actin insertion alleles were easily distinguished among pools of 100 plant lines. PCR techniques were used which accelerated the purification of mutant lines, and segregation, physical mapping, and sequencing of the act2-1 and act4-1 mutations. This strategy should be generally useful in screening mutant libraries made with a variety of plant insertion elements for mutations in any known sequence.
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Fletcher LD, McDowell JM, Tidwell RR, Meagher RB, Dykstra CC. Structure, expression and phylogenetic analysis of the gene encoding actin I in Pneumocystis carinii. Genetics 1994; 137:743-50. [PMID: 8088520 PMCID: PMC1206034 DOI: 10.1093/genetics/137.3.743] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Actin is a major component of the cytoskeleton and one of the most abundant proteins found in eukaryotic cells. Comparative sequence analysis shows that this essential gene has been highly conserved throughout eukaryotic evolution making it useful for phylogenetic analysis. Complete cDNA clones for the actin-encoding gene were isolated and characterized from Pneumocystis carinii purified from immunosuppressed rat lungs. The nucleotide sequence encodes a protein of 376 amino acids. The predicted actin protein of P. carinii shares a high degree of conservation to other known actins. Only one major actin gene was found in P. carinii. The P. carinii actin sequence was compared with 30 other actin sequences. Gene phylogenies constructed using both neighbor-joining and protein parsimony methods places the P. carinii actin sequence closest to the majority of the fungi. Since the phylogenetic relationship of P. carinii to fungi and protists has been questioned, these data on the actin gene phylogeny support the grouping of P. carinii with the fungi.
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Greenwood MJ, McDowell JM, Trabka E. Conducting Descriptive and Analytical Research with the Immigration and Naturalization Service Public Use Tapes. ACTA ACUST UNITED AC 1991. [DOI: 10.3233/jem-1991-173-402] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Brown RA, Taylor AM, McDowell JM. Inhibition of sulphate incorporation by chondrocytes in intact cartilage by hyaluronate from foetal cartilage. Connect Tissue Res 1990; 24:157-68. [PMID: 2354635 DOI: 10.3109/03008209009152431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A number of regulators are available in cartilage to effect the local control of matrix production by chondrocytes. A cartilage slice assay has been used in this study to investigate the influence of such regulators (extracted from foetal cartilage) on intact cartilage. A net inhibition of sulphation was found, rather than stimulation as reported for extracts rich in the somatomedin-like, cartilage derived factor (CDF). Inhibition was due, to a high molecular weight component identified as hyaluronic acid (based on enzyme sensitivity, chromatographic behaviour and temperature stability). Its inhibition of sulphation in intact cartilage was more profound than that produced by commercially available umbilical cord hyaluronate. We conclude that foetal cartilage hyaluronate is a far more potent inhibitor of sulphation than hyaluronate from other sources, suppressing sulphation even in the presence of a somatomedin-like activator and in intact cartilage, which responds poorly to commercial hyaluronate.
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Simpson KH, Madej TH, McDowell JM, MacDonald R, Lyons G. Comparison of extradural buprenorphine and extradural morphine after caesarean section. Br J Anaesth 1988; 60:627-31. [PMID: 3377946 DOI: 10.1093/bja/60.6.627] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Fifty-seven women received extradural morphine 3 mg, buprenorphine 0.18 mg or buprenorphine 0.09 mg after elective Caesarean section carried out under extradural bupivacaine. Supplementary sublingual buprenorphine was available on demand. Ten-centimetre visual analogue pain scores were completed regularly; emesis, pruritus and urinary retention were recorded for 24 h. Patients who received buprenorphine 0.09 mg had more pain, and required more supplementary analgesia, than those who received morphine 3 mg. Pain scores and analgesic requirements after buprenorphine 0.18 mg were not significantly different from either of the other two groups. Emesis was not significantly different in the three groups. More itching occurred after morphine 3 mg and buprenorphine 0.18 mg than after buprenorphine 0.09 mg; pruritus of the face, legs and perineum was more common after morphine than buprenorphine. Twenty-eight percent of patients without a urinary catheter developed retention of urine. Seventy-five to 84% of patients were satisfied with analgesia during the first day after operation. Analgesia and adverse effects were similar when morphine 3 mg or buprenorphine 0.18 mg was given extradurally after Caesarean section.
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Farrell AM, Gowland G, McDowell JM, Simpson KH, Watkins J. Anaphylactoid reaction to vecuronium followed by systemic reaction to skin testing. Anaesthesia 1988; 43:207-9. [PMID: 2896468 DOI: 10.1111/j.1365-2044.1988.tb05542.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
An unusual case is presented of a systemic anaphylactoid reaction to tubocurarine and subsequently to vecuronium. Intradermal testing with vecuronium following the latter response was negative at recommended test dose levels but at a higher concentration it initiated a hazardous systemic response. The laboratory investigations and possible mechanisms involved in this unusual case are discussed in detail since they may relate to other patients who experience anaphylactoid responses to anaesthetic drugs and who then undergo intradermal testing.
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Rodda JC, McGregor IG, McDowell JM. Remineralisation of artificial enamel lesions with a phosphate-fluoride solution. THE NEW ZEALAND DENTAL JOURNAL 1979; 75:80-6. [PMID: 289000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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