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K Lindsey

Publications and source records attributed to K Lindsey.

24 records · Page 2Linked to original sources
PubMed1993

Differential gene expression in nematode-induced feeding structures of transgenic plants harbouring promoter-gusA fusion constructs.

Sedentary plant-parasitic nematodes are able to induce specialized feeding structures in the root system of their host plants by triggering a series of dramatic cellular responses. These changes presumably are accompanied by a reprogramming of gene expression. To monitor such changes, a variety of promoter-gusA fusion constructs were introduced into Arabidopsis and tobacco. Transgenic plants were analysed histochemically for GUS activity in the nematode feeding structures after infection with either Heterodera schachtii or Meloidogyne incognita. Promoters of the Cauliflower Mosaic Virus 35S gene, the bacterial nopaline synthase, rooting loci (rol) and T-cyt genes and the plant-derived phenylalanine ammonia-lyase I gene, which are highly active in non-infected roots, were all downregulated in the feeding structures as indicated by the strong decrease of GUS activity inside these structures. Less stringent downregulation was observed with chimeric gusA fusion constructs harbouring truncated rolB and rolC promoter sequences. Similar observations were made with transgenic Arabidopsis lines that carried randomly integrated promoterless gusA constructs to identify regulatory sequences in the plant genome. Most of the lines that were selected for expression in the root vascular cylinder demonstrated local downregulation in feeding structures after infection with H. schachtii. The reverse pattern of GUS activity, a blue feeding structure amidst unstained root cells, was also found in several lines. However, GUS activity that was entirely specific for the feeding structures was not observed. Our data show that the expression of a large number of genes is influenced during the development of the nematode feeding structures.

Animals↗
PubMed1992

Gene rescue in plants by direct gene transfer of total genomic DNA into protoplasts.

To study the possibility of gene rescue in plants by direct gene transfer we chose the Arabidopsis mutant GH50 as a source of donor DNA. GH50 is tolerant of chlorsulfuron, a herbicide of the sulfonylurea class. Tobacco protoplasts were cotransfected with genomic DNA and the plasmid pHP23 which confers kanamycin resistance. A high frequency of cointegration of the plasmid and the genomic DNA was expected, which would allow the tagging of the plant selectable trait with the plasmid DNA. After transfection by electroporation the protoplasts were cultivated on regeneration medium supplemented with either chlorsulfuron or kanamycin as a selective agent. Selection on kanamycin yielded resistant calluses at an absolute transformation frequency (ATF) of 0.8 x 10(-3). Selection on chlorsulfuron yielded resistant calluses at an ATF of 4.7 x 10(-6). When a selection on chlorsulfuron was subsequently applied to the kanamycin resistant calluses, 8% of them showed resistance to this herbicide. Southern analysis carried out on the herbicide resistant transformants detected the presence of the herbicide resistance gene of Arabidopsis into the genome of the transformed tobacco. Segregation analysis showed the presence of the resistance gene and the marker gene in the progeny of the five analysed transformants. 3 transformants showed evidence of genetic linkage between the two genes. In addition we show that using the same technique a kanamycin resistance gene from a transgenic tobacco could be transferred into sugar beet protoplasts at a frequency of 0.17% of the transformants.

Blotting, Southern↗
PubMed1991

Somatosensory evoked potentials are unchanged by reflex sympathetic dystrophy and by stellate ganglion block.

Median nerve somatosensory evoked potentials (SEPs) were monitored in patients with chronic pain before and after stellate ganglion blockade. A change caused by the syndrome or by the block would suggest that SEPs might be useful in the diagnosis and treatment of chronic pain. We observed 20 subjects. Group I (n = 10) had chronic pain not involving the upper extremity. Group II (n = 8) had reflex sympathetic dystrophy of the arm. All patients underwent unilateral stellate ganglion block using an anterior paratracheal approach. The SEPs were recorded by median nerve stimulation on the blocked (affected) side and unblocked (unaffected) side before and 30 min after the block. Recording sites were ipsilateral brachial plexus, the cervical spinal cord, and the contralateral sensory cortex. There were no between-group differences before or after the block. Paired analysis within each group showed that the SEPs were not different from baseline (unaffected side before block) at any time throughout the study. We conclude that since SEPs are not changed by the reflex sympathetic dystrophy or stellate ganglion block, they would not be useful in the evaluation of pain or in determining the effectiveness of sympathetic block. Both the pain and the block appear to involve alteration of conducting pathways separate from those monitored by median nerve SEPs.

Adolescent↗
PubMed1991

Functional tagging of regulatory elements in the plant genome.

In comparison with animals, relatively few plant genes have been identified that have been shown to be under organ-, tissue- or cell-type-specific regulation. In this paper, we describe how the beta-glucuronidase (GUS) reporter gene (gusA or uidA), fused to a weak promoter (a truncated (-90 bp) CaMV35S promoter), can be used to identify tissue-specific markers in transgenic tobacco plants. The rationale was that the expression of gusA would be determined primarily by position effect. Quantitative analysis revealed that, of 184 -90-gus transgenic plants, 73% exhibited gusA gene activation in leaf tissue, and the level of GUS enzyme activity varied over a 300-fold range within the population. In comparison, transformation with a promoterless gusA gene resulted in GUS expression in 78% of all plants analyzed (in leaf and/or root) and expression levels were three-fold or more lower. Qualitative GUS analysis of single locus -90-gus transformants revealed differential expression in diverse tissues. The spatial pattern of GUS activity was unique to individual transformants, was a reflection of differential gusA gene transcription, and was stably transmissible to progeny. Evidence for preferential expression in roots not only of the -90-gus, but also the promoterless gusA gene is presented. The value of the -90 bp promoter-gusA sequence, which is termed an 'interposon', as a tool both to identify native enhancer sequences in situ and to investigate position effects in plants, is discussed.

Enhancer Elements, Genetic↗
PubMed1988

The chronic hepatic or renal toxicity of di(2-ethylhexyl) phthalate, acetaminophen, sodium barbital, and phenobarbital in male B6C3F1 mice: autoradiographic, immunohistochemical, and biochemical evidence for levels of DNA synthesis not associated with carcinogenesis or tumor promotion.

Male B6C3F1 mice, 6 weeks of age, were fed diets or water containing di(2-ethylhexyl) phthalate (DEHP) at 12,000 or 6000 ppm, acetaminophen (ACT) at 10,000 or 5000 ppm, sodium barbital (BBS) at 1000 ppm, or phenobarbital (PB) at 500 ppm for 40 weeks. Groups of six mice were terminated at 2, 8, 24, and 40 weeks for evaluation of liver and kidney weights, histopathology, and thymidine kinase (TK) activity in liver and kidney and levels of DNA synthesis, measured by tritiated thymidine [( 3H]T) autoradiography or bromodeoxyuridine (BrdU) immunohistochemistry. Liver weights, as percentage of body weight, were significantly elevated at most time intervals for mice exposed to all chemicals at each dose. The hepatocyte labeling indices (LI) with [3H]T autoradiography or BrdU immunocytochemistry were significantly elevated in mice fed DEHP at 12,000 ppm at 24 and 40 weeks or BBS and ACT at 2 weeks. LI were not elevated in mice fed PB. Hepatic TK activity was significantly elevated in mice fed DEHP, BBS, or ACT at Weeks 2 and 8. Histopathologic hepatic lesions were associated with these elevations, while hepatic lesions were not associated with changes in TK activity in PB-treated mice. In contrast, only DEHP and BBS induced toxic renal lesions. Persistent or transient elevation of the renal LI and TK activity accompanied renal toxicity. Thus, the hepatic toxin DEHP induced chronic renal hyperplasia without evidence of renal carcinogenicity or tumor promotion in previous studies at the doses used. ACT, a hepatotoxin, produced transient chronic hepatic hyperplasia without evidence of carcinogenicity in B6C3F1 mice in earlier studies at the same doses used. Thus, persistent or transient hepatic or renal hyperplasia was associated with carcinogenic or tumor promoting activity of these chemicals in some cases but not in others.

Acetaminophen↗