Biomedical subjects

W Keys

Publications and source records attributed to W Keys.

6 recordsLinked to original sources

PubMed1998

Cross-species amplification of soybean (Glycine max) simple sequence repeats (SSRs) within the genus and other legume genera: implications for the transferability of SSRs in plants.

We investigated the transferability of 31 soybean (Glycine max) simple sequence repeat (SSR) loci to wild congeners and to other legume genera. Up to 65% of the soybean primer pairs amplified SSRs within Glycine, but frequently, the SSRs were short and interrupted compared with those of soybeans. Nevertheless, 85% of the loci were polymorphic within G. clandestina. Cross-species amplification outside of the genus was much lower (3%-13%), with polymorphism restricted to one primer pair, AG81. AG81 amplified loci in Glycine, Kennedia, and Vigna (Phaseoleae), Vicia (Vicieae), Trifolium (Trifolieae), and Lupinus (Genisteae) within the Papilionoideae, and in Albizia within the Mimosoideae. The primer conservation at AG81 may be explained by its apparent proximity to the seryl-tRNA synthetase gene. Interspecific differences in allele size at AG81 loci reflected repeat length variation within the SSR region and indels in the flanking region. Alleles of identical size with different underlying sequences (size homoplasy) were observed. Our findings and the emerging patterns in other plant studies suggest that in contrast to animals, successful cross-species amplification of SSRs in plants is largely restricted to congeners or closely related genera. Because mutations in both the SSR region and the flanking region contribute to variation in allele size among species, knowledge of DNA sequence is essential before SSR loci can be meaningfully used to address applied and evolutionary questions.

Base Sequence↗

PubMed1986

Saccade-related and visual activities in the pulvinar nuclei of the behaving rhesus monkey.

We studied three subdivisions of the pulvinar: a retinotopically organized inferior area (PI), a retinotopically mapped region of the lateral pulvinar (PL), and a separate, visually responsive component of the lateral pulvinar (Pdm). Single neurons were recorded in these regions from awake, trained rhesus monkeys, and we correlated the discharge patterns of the cells with eye movements. About 60% of the neurons discharged after saccadic eye movements in an illuminated environment and had either excitatory, inhibitory, or biphasic (inhibitory-excitatory) response patterns. These responses were most often transient in nature. Neurons with excitatory activity had a mean onset latency of 72 ms after the termination of the eye movement. Latencies for cells with inhibitory responses averaged 58 ms. In sharp contrast, the cells with biphasic response patterns became active before the termination of the eye movement. A unique set of these neurons termed saccade cells, were active with visually guided eye movements in the light, with the same eye movements made to a briefly pulsed target in the dark, and for similar eye movements made spontaneously in total darkness. The activity was present with the appropriate saccade, independent of the beginning eye position. Biphasic response patterns were typical of these saccade cells. Saccade cells were most common in Pdm and PI. About half of the saccade cells also had some visual response that was independent of eye movement. A second group of cells was active with saccadic eye movements in the light but not in the dark. Some of these cells had clear visual responses that could account for their activity following eye movements; others had no clear visual receptive field.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1985

Pulvinar nuclei of the behaving rhesus monkey: visual responses and their modulation.

We have examined the properties of neurons in three subdivisions of the pulvinar of alert, trained rhesus monkeys 1) an inferior, retinotopically mapped area (PI), 2) a lateral, retinotopically organized region (PL), and 3) a dorsomedial visual portion of the lateral pulvinar (Pdm), which has a crude retinotopic organization. We tested the neurons for visual responses to stationary and moving stimuli and for changes in these responses produced by behavioral manipulations. All areas contain cells sensitive to stimulus orientation as well as neurons selective for the direction of stimulus movement; however, the majority of cells in all three regions are either broadly tuned or nonselective for these attributes. Nearly all cells respond to stimulus onset, a significant number also give a response to stimulus termination, and rarely a cell gives only off responses. Nearly all cells increase their discharge rate to visual stimuli. Receptive fields in the two retinotopically mapped regions, PI and PL, have well-defined borders. The sizes of these receptive fields show a positive correlation with the eccentricity of the receptive fields. The receptive fields in the remaining region, Pdm, are frequently very large, but with these large fields excluded, show a similar correlation with eccentricity. All pulvinar cells tested (n = 20) were mapped in retinal coordinates; the receptive fields are positioned in relation to the retina. We found no cells with gaze-gated characteristics (2), nor cells mapped in a spatial coordinate system. The response latencies in PI and PL are shorter and less variable than the latencies in Pdm. Active use of a stimulus can produce an enhancement or attenuation of the visual response. Eye-movement modulation was found in all three subdivisions in about equal frequencies. Attentional modulation was common in Pdm and was rare in PI and PL. The modulation is spatially selective in Pdm and nonselective in PI for a small number of tested cells. These data demonstrate functional differences between Pdm and the other two areas and suggest that Pdm plays a role in selective visual attention, whereas PI and PL probably contribute to other aspects of visual perception.

Animals↗

PubMed1981

Behavioral analyses of visual cortex of the Galago.

For the purpose of examining some of the principles underlying the function of primate visual cortex, the performance of one normal control group and three operated groups of Galagos having bilateral cortical lesions in area 17 (S), the middle temporal area (MT), or areas 18 and 19 (XS) was assessed on tasks measuring visual sensory capacity, search, and learning. Striate lesions produced a reduction in foveal vision and were responsible for deficits only on a complex visual learning task. The lesions of Group MT extended beyond area MT and involved the optic radiations. This resulted in impairments on all visual problems. Animals in Group XS had subtotal lesions of prestriate cortex and were also impaired on each task, but they showed less severe deficits in sensory capacity than animals in Group MT. It is suggested that the Galago's striate cortex plays a major role in the identification and utilization of relevant visual information and that areas 18 and 19 are important in both visual learning and visuospatial analyses. Evidence is provided that area MT is involved in visual search.

Animals↗

PubMed1979

Middle temporal cortical visual area and visuospatial function in Galago senegalensis.

Bushbabies with lesions restricted to the middle temporal (MT) area and animals with larger extrastriate lesions including area MT were compared with normal control animals on test of visuospatial localization and discrimination learning. Ablation of area MT was sufficient to produce impairments in directing behavior appropriately on the basis of visuospatial cues. Extension of the lesion into areas 18 and 19 produced more profound deficits. Retardation in learning a stripe discrimination problem was correlated with the extent of damage to the geniculostriate system. It is hypothesized that area MT is important in achieving and maintaining fixation on a target whereas cortical areas 18 and 19 are necessary for establishing the location of stimulation in visual space.

Animals↗

PubMed1979

Personality correlates in a sample of male nurses in the British Royal Air Force.

This descriptive study provides data relevant to two currently popular views of the male nursing image. Firstly, that male nurses tend to prefer the more technological or administrative aspects of nursing and secondly, that they exhibit to an unusually high degree what are commonly thought of as being amongst the more feminine personality traits. The sample consisted of 91 male RAF nurses working in RAF hospitals, and was of predominantly English nationality. Of the 39 SRNs in the sample 65.8% preferred general nursing to the more technical areas such as intensive care, operating theatre, orthopaedic and renal. The preference for general nursing was even greater, 76.1%, amongst the 30 SENs surveyed. The Eysenck Personality Questionnaire (EPQ) and a Level of Aspiration Test (LOA) were used to obtain measures of the personality traits of the sample. The scores obtained showed that the male RAF nurses were significantly less psychotic than male civilian nurses, male civilians or serviceman of similar age. They were also significantly less extraverted than servicemen as a whole and significantly more stable than the male civilian norm. A comparison of SRNs with SENs revealed only two significant differences. The SRNs were significantly less extraverted and had a significantly higher level of adpiration than the SENs.

Adult↗