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Biomedical subjects

L J Rogers

Publications and source records attributed to L J Rogers.

At least 19 recordsLinked to original sources
PubMed1991

Relationship of the flavodoxin isoforms from Porphyra umbilicalis.

The macroalga Porphyra umbilicalis contained two flavodoxins in approximately 5:1 ratio and differing in Mr by ca 1000. The N-terminal sequences of the isoforms were identical and there was strong immunochemical identity. Peptide mapping gave similar fragments which differed in Mr by constant amount for the two isoforms. The flavodoxins may therefore differ only at the C-terminus, possibly as a consequence of in vivo processing since inclusion of protease inhibitors during extraction had no effect on the ratio of the isoforms.

Amino Acid Sequence↗
PubMed1979

Influence of pesticides on the growth of cyanobacteria.

Two unicellular and two filamentous cyanobacteria (blue-green algae) were exposed under conditions optimal for photoautotrophic growth to eleven pesticides. Low concentrations (0.01 to 5 ppm) of diuron, atrazine, and paraquat inhibited growth. With MCPA, MCPP, 2,4-D, milstem and ethrel, marked inhibitory effects were achieved only at concentrations above 100 ppm. Growth was inhibited by glyphosate, DDT, and thiram at intermediate concentrations. In some cases, the effective concentration of the pesticide varied considerably with the organism tested.

Cyanobacteria↗
PubMed1979

Lateralisation of function in the chicken fore-brain.

There is lateralisation of function in the chicken fore-brain. This was revealed by examining the behavioural modifications produced by administration of cycloheximide into the left or right hemisphere on Day 2 of post-hatched life. Visual discrimination learning of a task requiring a search for food was found to be performed either entirely or, at least, to a greater extent by the left hemisphere. Visual habituation learning was not found to be lateralised. The left hemisphere is more involved in auditory habituation than is the right; administration of cycloheximide to the left hemisphere slowed auditory habituation, as did bilateral administration, but treatment of the right hemisphere was ineffective. There are indications that the right hemisphere plays a more important role in response to novelty. A side-preference for response to stimuli seen by the left eye was demonstrated. These results are discussed with reference to head orientation during development in the egg.

Acoustic Stimulation↗
PubMed1979

Menstruation.

Societal attitudes to menstruation are largely negative, and so serve to reinforce the inferior social status of women. These attitudes have extended into medical practice and research on menstruation. As a result, much research on 'premenstrual syndrome' has been biased both in methodology and interpretation. Correlations between hormone levels, mood changes and other behavioural measures, which cycle together, are often incorrectly assumed to indicate causal relationships. These problems are discussed along with the report of a pilot study which used a new, and more comprehensive method of studying menstruation. This study has demonstrated numerous correlations between hormone levels, mood and psycho-physical performance. A relationship was found between task performance and early education about menstruation. Studied of the kind reported here provide a basis on which to formulate new questions about causal influences, which can only be established by entirely different methods of study.

Attitude to Health↗
PubMed1978

Isoelectric focusing of ferredoxins, flavordoxins and a rubredoxin.

Isoelectric points of ferredoxins, flavodoxins and a rubredoxin from a range of sources were measured by electrofocusing over the pH range between 2.5 and 5.0 on thin layers of polyacrylamide gel. The pH gradient along the gel was measured directly by a surface electrode. The isoelectric points of the plant-type ferredoxins were between approx. 3.15 and 3.35, and those of the flavodoxins close to 3.5. Ferredoxin, rubredoxin and flavodoxin from Clostridium pasteurianum had isolectric points of the of 2.75, 2.9, and 3.1, respectively. The values for the isoelectric points ferredoxins are significantly lower than previous results in the literature suggest.

Bacteria↗
PubMed1978

The amino acid sequence of ferredoxin from the red alga Porphyra umbilicalis.

The amino acid sequence of the ferrodoxin of Porphyra umbilicalis was determined by the dansyl-phenyl isothiocyanate method, on peptides obtained by tryptic, chymotryptic and thermolytic digestion of the protein or its CNBr-cleavage fragments. The molecule consists of 98 residues, has an unblocked N-terminus and shows considerable similarity with other plant-type ferredoxins. It is the first reported sequence of a red-algal ferredoxin.

Amino Acid Sequence↗
PubMed1978

Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.

Amino Acid Sequence↗
PubMed1978

Stigma, sex and society: a new look at gender differentiation and sexual variation.

This paper takes a critical look at the hormonal basis of sexual behavior and concludes that it plays no part in determination of sexual activity or sexual preference in any of its forms including homosexuality and transsexualism. The empirical evidence of psychosexual functioning does not support Money's schema which suggest that sexual variation (homosexuality), transsexualism, and transvestism are incongruities of gender identity. At alternative approach which places gender differentiation and sexual variation in a social context is presented.

Adult↗