Soft-Tissue Movement at the Foot During the Stance Phase of Walking

Background: Soft-tissue movement has challenged the use of noninvasive skin-based markers that are assumed to be rigidly attached to the underlying bony landmarks. We assessed soft-tissue movement in multiple foot segments by calculating the relative changes in the intermarker distances of the hindfoot, midfoot, and forefoot segments during the early, middle, and late stances of walking compared with the intermarker distances measured while participants remained still during standing. Methods: Seven healthy young adults with no previous lower-limb injury were tested while walking barefoot at a comfortable pace. Skin-based markers were placed on three foot regions (hindfoot-calcaneus, midfoot-navicular, and forefoot–first to fifth metatarsals). A motion system sampled at 120 Hz was used to capture the foot markers during the stance phase of walking. Results: Soft-tissue movement was found in the forefoot region characterized by shortened distances, specifically during early (breaking) stance and late (propulsion) stance. In the hindfoot region, soft-tissue movement was characterized by shortened and elongated distances during the early and late stance periods, respectively. All of the foot regions showed the least intermarker distance changes during midstance. Conclusions: The dynamics of soft-tissue movement in multiple foot segments were characterized by the greatest changes in the intermarker distances in the forefoot and hindfoot during the early and late stance phases and the least changes in the foot segments during midstance. The results provide a feasible and accessible measurement for assessing soft-tissue movement in the foot when skin-based motion markers are used. (J Am Podiatr Med Assoc 101(1): 25–34, 2011)

A high-resolution, intraspecific linkage map of pepper (Capsicum annuum L.) and selection of reduced recombinant inbred line subsets for fast mapping

A high-resolution, intraspecific linkage map of pepper ( Capsicum annuum L.) was constructed from a population of 297 recombinant inbred lines. The parents were the large-fruited inbred cultivar ‘Yolo Wonder’ and the hot pepper line ‘Criollo de Morelos 334’, which is heavily used as a source of resistance to a number of diseases. A set of 587 markers (507 amplified fragment length polymorphisms, 40 simple sequence repeats, 19 restriction fragment length polymorphisms, 17 sequence-specific amplified polymorphisms, and 4 sequence tagged sites) were used to generate the map; of these, 489 were assembled into 49 linkage groups (LGs), including 14 LGs with 10 to 60 markers per LG and 35 with 2 to 9 markers per LG. The framework map covered 1857 cM with an average intermarker distance of 5.71 cM. Twenty-three LGs, composed of 69% of the markers and covering 1553 cM, were assigned to 1 of the 12 haploid pepper chromosomes, leaving 26 LGs (304 cM) unassigned. The chromosome framework map built with 250 markers led to a high level of mapping confidence and an average intermarker distance of 6.54 cM. By applying MapPop software, it was possible to select smaller subsets of 141 or 93 most informative individuals with a view to reducing the time and cost of further mapping and phenotyping. To define the smallest number of individuals sufficient for assigning any new marker to a chromosome, subsets from 12 to 45 individuals and a set of 13 markers distributed over all 12 chromosomes were screened. In most cases, the markers were correctly assigned to their expected chromosome, but the accuracy of the map position decreased as the number of individuals was reduced.

Microsatellite marker panels for use in high-throughput genotyping of mouse crosses

Iakoubova, Olga A., Christine L. Olsson, Katherine M. Dains, Jim Choi, Ivetta Kalcheva, L. Gordon Bentley, Madalyne Cunanan, David Hillman, Judi Louie, Migdad Machrus, and David B. West. Microsatellite marker panels for use in high-throughput genotyping of mouse crosses. Physiol Genomics 3: 145–148, 2000.—Several microsatellite genotyping panel sets have been developed that are polymorphic between C57BL/6J and CAST/Ei mice, or C57BL/6J and DBA/2J. One set of markers for each strain pair has an intermarker distance of ∼20 cM, and a second set has an intermarker distance of 5 cM. The 20-cM set contains 105 markers for C57BL/6J × DBA/2J and 108 for C57BL/6J × CAST/Ei, divided into 13 panels. Each 5-cM set includes 350 markers arranged into 45 panels. A panel contains a number of primer pairs whose fluorescently labeled PCR products can be pooled together and separated on one lane of a polyacrylamide gel. The sets are arranged by the size of the PCR product and by the type of fluorescent dye; 5-cM sets are also arranged by chromosomal region. The 20-cM sets are most useful for full-genome scans, the 5-cM sets are useful for full-genome and/or for region-specific chromosome screens. Both sets were proven as useful tools for speed congenic development, quantitative trait loci (QTL) analysis and physical mapping. These panel sets provide a throughput of 1,536–2,304 mouse genotypes daily per one gel-based system. Whole genome scans of one animal require 13 or 48 gel lanes, with 20 cM or 5 cM density, respectively.

Long-tract mitotic gene conversion in yeast: evidence for a triparental contribution during spontaneous recombination.

In Saccharomyces cerevisiae, spontaneous mitotic gene conversion at one site is statistically correlated with recombination at other loci. In general, coincident conversion frequencies are highest for tightly linked markers and decline as a function of intermarker distance. Paradoxically, a significant fraction of mitotic gene convertants exhibits concomitant nonreciprocal segregation for multiple and widely spaced markers. We have undertaken a detailed genetic analysis of this class of mitotic recombinants. Our results indicate that mitotic gene conversion in yeast is frequently associated with nonreciprocal segregation of markers centromere-distal to the selected site of conversion. In addition, distal markers are often found to be mosaic within the product colonies. These observations, and others described here, suggest that a percentage of gene conversion in vegetative yeast cells is coupled to a chromosome break and repair mechanism. This hypothesis was further tested using a strain trisomic for chromosome VII which was specially marked to detect homolog-dependent repair events. An association between mitotic gene conversion events and the production of broken chromosomes which are repaired by a homologous-pairing-copy mechanism was supported.

Estimation of regional pleural surface expansile forces in intact dogs

Distances between percutaneously inserted apical and basal lung markers determined by biplane X-ray, computer-based videometry (J. Appl. Physiol. 34: 544, 1973) were calibrated against dependent percutaneously recorded pleural liquid pressures (J. Appl. Physiol. 31: 277, 1971) in five 10-12 kg mongrel dogs under morphine-pentobarbital anesthesia studied without thoracotomy. At the same apical pleural-liquid pressure values, the apical intermarker distances were uniformly greater when in the head-up rather than head-down position. This finding suggests that the expansile forces acting on the apical regions of the lung, in the head-up position, are greater (-30 +/- 2 cmH2O) than would be predicted from “pleural liquid” pressures (-15 +/- 1 cmH2O) measured at this nondependent site in the thorax, and much greater than the “pleural surface” pressures measured by the generally accepted balloon and counter-pressure techniques. In contrast, in the head-down body position, expansile forces acting on the nondependent basal regions of the lung estimated by the intermarker distance technique were variable to either side of the pressures measured by open-ended liquid-filled catheters, and thus were not significantly different. Mean values measured by the catheters and predicted by the markers were -14 +/- 1 and -10 +/- 3 cmH2O, respectively.