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Biomedical subjects

M J Dickinson

Publications and source records attributed to M J Dickinson.

12 recordsLinked to original sources
PubMed2005

Anxiety and depression may have an evolutionary role as negative reinforcers, encouraging socialisation.

Anxiety and depression are both very common mental states and both are quite unpleasant. Their high prevalence and preservation make it likely they have considerable evolutionary significance and in some way improve the chances of an individual's survival. The following article proposes that much of the anxiety and depression we experience is primarily acting as a negative reinforcer, encouraging socialisation. These feelings are experienced most intensely when we are isolated and have evolved to discourage this highly maladaptive behaviour, there being major advantages for being with other people. Particular problems are considered, including aspects of autism and alcohol and tranquilliser abuse. How the presence of other people may alter the expression of anxiety and depression is considered, in addition to implications for psychiatry.

Adaptation, Psychological↗
PubMed2001

Cloning of the CYP51 gene from the eyespot pathogen Tapesia yallundae indicates that resistance to the DMI fungicide prochloraz is not related to sequence changes in the gene encoding the target site enzyme.

Resistance to sterol 14 alpha-demethylase inhibitor (DMI) fungicides has been correlated with mutations in the CYP51 gene encoding the target enzyme eburicol 14 alpha-demethylase. CYP51 was isolated from the eyespot pathogen Tapesia yallundae revealing a predicted 526-amino acid product exhibiting homology to other fungal CYP51s. CYP51 was sequenced from four field isolates sensitive or resistant to the DMI fungicide prochloraz and partially sequenced from two further isolates and eight progeny from a cross between prochloraz-sensitive and -resistant parents. Two alleles of the gene were detected termed CYP51-1 and CYP51-2. No correlation was found between sequence change and fungicide sensitivity. Therefore prochloraz resistance involved a mechanism other than mutation in the target site gene.

Amino Acid Sequence↗
PubMed1993

Nucleotide sequence relationships of double-stranded RNAs in flax rust, Melampsora lini.

Flax rust, Melampsora lini strain SP6, contains 11 double-stranded (ds) RNA molecules with a total length of about 25 kbp. The dsRNAs are inherited in three genetic units: the L unit comprising a single 5.2 kbp dsRNA and contained within a 40-nm virus-like particle, and the A and B units each consisting of five dsRNAs (A1-A5, and B1-B5) ranging in size from 1.2 to 2.7 kbp. This paper reports the isolation of a cDNA library representing 10 of the 11 dsRNAs. By nucleic-acid hybridization techniques it has been shown that all ten sequences are unique showing no detectable cross-hybridization with any other dsRNA present in the rust. A near full-length sequence of 1932 bp of the B3 dsRNA is reported and contains several open reading frames, the largest of which comprises most of the molecule.

Amino Acid Sequence↗
PubMed1984

Integration of a temperate phage infecting Spiroplasma citri.

A physical map of the genome of a temperate Type 3 spiroplasma-virus, ai, has been constructed. Host DNA has been digested with restriction enzymes, and recombinant DNA clones of ai fragments in coliphage M13 vectors have been used as probes to detect viral DNA sequences integrated into spiroplasmas. All strains of Spiroplasma citri examined contained a deleted form of ai integrated as a cryptic prophage which was unable to confer resistance to ai superinfection. Stable ai lysogens also contained a complete ai genome. We propose that the infecting viral DNA circularizes and integrates adjacent to the cryptic prophage in a site-specific recombination event at unique points in both the virus and host genomes.

Bacteriophages↗
PubMed1975

Expression of the beta-thalassemia gene in the first trimester fetus.

To determine whether beta-thalassemia can be detected in the fetus, blood was obtained from abortuses of normal mothers and of mothers with beta-thalassemia trait. The red cells were incubated with radioactive leucine and the globin chains were analyzed by radiochromatography. Two independent methods were utilized to correct the results for contamination by maternal radioactive beta-chain, and the corrected beta/gamma ratios were compared to a previously established range of normal fetal beta/gamma synthetic ratios obtained by similar measurements in pure fetal cells. In the erythroid cells of three fetuses from mothers with beta-thalassemia trait, the beta/gamma synthetic ratio was normal in two. The third had a beta/gamma ratio of 0.04 at 10 1/2 weeks, a 50% reduction, consistent with fetal beta-thalassemia trait. Two other fetuses, derived from parents both of whom had beta-thalassemia trait, were also studied. One had a beta/gamma ratio of 0.029 at 8 weeks, a 65% reduction, also consistent with beta-thalassemia trait. The cells of the other had a ratio of essentially zero at 11 weeks, highly suggestive of homozygous beta-thalassemia. Although further experience will be needed to distinguish the homozygous and heterozygous states reliably, it now appears that the beta-thalassemia gene is expressed in the first trimester. Therefore these data suggest that the antenatal diagnosis of beta-thalassemia is becoming an attainable goal.

Female↗
PubMedDate not supplied

Close linkage between the Cf-2/Cf-5 and Mi resistance loci in tomato.

Analysis of restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers in tomato plants segregating for resistance to the fungus Cladosporium fulvum was used to localize the resistance genes Cf-2 and Cf-5 to the same region of chromosome 6. This region, between GP79 and Aps-1, is the same as that reported for the Mi gene, which confers resistance to root-knot nematodes (meloidogyne spp.). Recombination values based on F2 populations from crosses between near-isogenic lines of L. esculentum 'Moneymaker' carrying Cf-2 or Cf-5 and Lycopersicon pennellii, indicate that this region occupies 4-5 centiMorgans (cM). However, in F2 populations from crosses between the L. esculentum stock LA1190 carrying yv and these lines, this value is 1-2 cM. The Cf-2 gene, introduced into L. esculentum from L. pimpinellifolium, is on an introgressed segment that extends from a point distal to GP79 to a point between TG232 and H2D1. The origin of Cf-5 was found to be L. esculentum var. cerasiforme rather than L. pimpinellifolium as previously reported. No RFLP markers and only one RAPD marker showed a polymorphism between Moneymaker and the near-isogenic line carrying Cf-5.

Base Sequence↗