Variation in the mating system of Sitka spruce (Picea sitchensis): evidence for partial assortative mating

Five allozyme polymorphisms were used to analyze the mating system in a Sitka spruce seed orchard in Saanichton, British Columbia. Allelic frequencies differed between the pollen and maternal pools at three of the five loci, with alleles rare in the maternal pool being even rarer in the effective pollen pool. Minor differences in pollen allelic frequencies were observed in the upper vs. lower crown. The multilocus outcrossing rate of the upper crown (t_m = 0.909) exceeded that of the lower crown (t_m = 0.764). Single-locus estimates of the outcrossing rate were significantly heterogeneous, with the lowest estimate of outcrossing, t = 0.773, observed for PGM-2 locus. Analyses of the mating system for the three maternal PGM-2 genotypes revealed heterogeneous pollen allelic frequencies and heterogeneous outcrossing rates, possibly due to assortative mating at this locus.     

The distribution of individual heterozygosity in natural populations

Estimation of the distribution of the level of individual heterozygosity within natural populations is explored with both Monte-Carlo simulation studies and data from natural populations. Simulations indicate that heterozygosities estimated from as few as a dozen randomly chosen loci may, to some degree, reflect (r = 0.35) heterozygosity determined by 100 independent loci. The shape of the expected distribution of heterozygosity is heavily dependent upon levels of heterozygosity at the loci. Complete genetic data for 12 loci from 997 Fundulus heteroclitus are used to describe the distributions of heterozygosity for different localities, for age classes and for sexes. The distributions deviate from normality. Distributions from different localities are not different, but the distributions are heterogeneous among age classes at one of two localities and are heterogeneous between the sexes.     

Genetic Organization and Adaptive Response of Allozymes to Ecological Variables in FUNDULUS HETEROCLITUS

Populations of Fundulus heteroclitus, (Cyprinodontidae) a widespread coastal marine fish, were studied in control and artificially heated environments on the North Shore of Long Island, New York to determine (1) patterns of variation in biochemical phenotypes and (2) the extent to which this variation reflected adaptation to environmental characteristics.—Variation at three of twelve polymorphic isoenzyme loci from the warm water population was beyond the range of variation among control populations, and resembled those determined for populations living at more southern latitudes. Hence, these differences were interpreted as adaptations to warm environments. Significant differences in allele frequencies and zygotic proportions at ten of twelve isoenzyme loci were found associated with differences in environments, sexes, and/or age classes. These data strongly support the view that protein polymorphisms are adaptive.—Several observations suggested that selection acts upon multilocus phenotypes rather than upon those of single loci. Several di-locus phenotypic distributions were demonstrated to be nonrandom, and those that exhibited similar patterns of dependence over years were postulated to be maintained by selection. Highly heterozygous fish exhibited superior viability when cohorts were compared over successive years.—The consequences of the polygynous mating system in this species for maintaining genetic variation and for allowing rapid evolutionary response to a variable environment are discussed.     

An anatomical subject-specific FE-model for hip fracture load prediction

In order to reduce the socio-economic burden induced by osteoporotic hip fractures, finite element models have been evaluated as an additional diagnostic tool for fracture prediction. For a future clinical application, the challenge is to reach the best compromise between model relevance and computing time. Based on this consideration, the current study focused on the development and validation of a subject-specific FE-model using an original parameterised generic model and a specific personalization method. A total of 39 human femurs were tested to failure under a quasi-static compression in stance configuration. The corresponding FE-models were generated and for each specimen the numerical fracture load (F _FEM) was compared with the experimental value (F _EXP), resulting in a significant correlation (F _EXP = 1.006 F _FEM with r ² = 0.87 and SEE = 1220 N, p < 0.05) obtained with a reasonable computing time (30 mn). Further in vivo study should confirm the ability of this FE-model to improve the fracture risk prediction.     

Immunohistochemical localization of irisin in skin,eye, and thyroid and pineal glands of the crested porcupine (Hystrix cristata)

Irisin was first identified in muscle cells. We detected irisin immunoreactivity in various organs of the crested porcupine (Hystrix cristata). In the epidermis, irisin immunoreactivity was localized mainly in stratum basale, stratum spinosum and stratum granulosum layers; immunoreactivity was not observed in the stratum corneum. In the dermis, irisin was found in the external and internal root sheath, cortex and medulla of hair follicles, and in sebaceous glands. Irisin immunoreactivity was found in the neural retina and skeletal muscle fibers associated with the eye. The pineal and thyroid glands also exhibited irisin immunoreactivity.