다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Genetics and analysis of quantitative traits

Heritability allows a comparison of the relative importance of genes and environment to the variation of traits within and across populations. The concept of heritability and its definition as an estimable, dimensionless population parameter was introduced by Sewall Wright and Ronald Fisher nearly a century ago. Despite continuous misunderstandings and controversies over its use and application, heritability remains key to the response to selection in evolutionary biology and agriculture, and to the prediction of disease risk in medicine. Recent reports of substantial heritability for gene expression and new estimation methods using marker data highlight the relevance of heritability in the genomics era.

Heritability in the genomics era — concepts and misconceptions

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

/pdf/the-human-obesity-gene-map-the-2005-update-3zvtci1u6f.pdf

The human obesity gene map: the 2005 update.

This paper presents the eleventh update of the human obesity gene map, which incorporates published results up to the end of October 2004. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTLs) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2004, 173 human obesity cases due to single-gene mutations in 10 different genes have been reported, and 49 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 166 genes which, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 221. The number of human obesity QTLs derived from genome scans continues to grow, and we have now 204 QTLs for obesity-related phenotypes from 50 genome-wide scans. A total of 38 genomic regions harbor QTLs replicated among two to four studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably with 358 findings of positive associations with 113 candidate genes. Among them, 18 genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, >600 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful publications and genomic and other relevant sites can be found at http://obesitygene.pbrc.edu.

https://onlinelibrary.wiley.com/doi/pdf/10.1038/oby.2005.50

The human obesity gene map: the 2004 update.

Egg size is a widely-studied trait and yet the causes and consequences of variation in this trait remain poorly understood. Egg size varies greatly within many avian species, with the largest egg in a population generally being at least 50% bigger, and sometimes twice as large, as the smallest. Generally, approximately 70% of the variation in egg mass is due to variation between rather than within clutches, although there are some cases of extreme intra-clutch egg-size variation. Despite the large amount of variation in egg size between females, this trait is highly consistent within individuals between breeding attempts; the repeatability of egg size is generally above 0.6 and tends to be higher than that of clutch size or laying date. Heritability estimates also tend to be much higher for egg size (> 0.5) than for clutch size or laying date (< 0.5). As expected, given the high repeatability and heritability of egg size, supplemental food had no statistically significant effect on this trait in 18 out of 28 (64%) studies. Where dietary supplements do increase egg size, the effect is never more than 13% of the control values and is generally much less. Similarly, ambient temperature during egg formation generally explains less than 15% of the variation in egg size. In short, egg size appears to be a characteristic of individual females, and yet the traits of a female that determine egg size are not clear. Although egg size often increases with female age (17 out of 37 studies), the change in egg size is generally less than 10%. Female mass and size rarely explain more than 20% of the variation in egg size within species. A female's egg size is not consistently related to other aspects of reproductive performance such as clutch size, laying date, or the pair's ability to rear young. Physiological characteristics of the female (e.g. endogenous protein stores, oviduct mass, rate of protein uptake by ovarian follicles) show more promise as potential determinants of egg size. With regards to the consequences of egg-size variation for offspring fitness, egg size is often correlated with offspring mass and size within the first week after hatching, but the evidence for more long-lasting effects on chick growth and survival is equivocal. In other oviparous vertebrates, the magnitude of egg-size variation within populations is often as great or greater than that observed within avian populations. Although there are much fewer estimates of the repeatability of egg size in other taxa, the available evidence suggests that egg size may be more flexible within individuals. Furthermore, in non-avian species (particularly fish and turtles), it is more common for female mass or size to explain a substantial proportion of the variation in egg size. Further research into the physiological basis of egg-size variation is needed to shed light on both the proximate and ultimate causes of intraspecific variation in this trait in birds.

/pdf/avian-egg-size-variation-within-species-and-inflexibility-8qzh45viyq.pdf

Avian egg size: variation within species and inflexibility within individuals

Many physiological and life-history traits scale with body mass, and this mass dependence must often be taken into account when comparing group means or when analyzing correlations between traits. Residual analysis (Bennett 1987), multiple regression (Hayes and Shonkwiler 1996), and analysis of covariance (ANCOVA, Atchley et al. 1976; Packard and Boardman 1987) have been proposed as robust techniques to reduce or eliminate mass dependence, since the use of ratios (i.e., the trait value divided by body mass) is problematic (Packard and Boardman 1987). The first of these three methods all involve regression, so problems may arise when the physiological trait of interest is the mass of an organ or tissue and the covariate is body mass. In a regression between organ mass and body mass, both variables include the mass of the organ. This tends to create a positive relationship between the two variables, even when no correlation between organ mass and the rest of body mass (i.e., body mass minus organ mass) exists. Sokal and Rohlf (1995) referred to the correlation between a part (e.g., organ mass) and the whole (e.g., body mass) as “part-whole correlation.” A number of authors have addressed the issue of partwhole correlation within the context of scaling (e.g., Prothero 1986; LaBarbera 1989) and the analysis of ratios (e.g., Atchley et al. 1976; Jackson and Somers 1991 and references therein). Descriptions of the effects of part-whole correlation in ANCOVA, multiple regression, and residual analysis, however, have been only anecdotal. For instance, Tracy and Sugar (1989) and Burness et al. (1998) described examples where removal of partwhole correlation changed the results of ANCOVA and residual analysis, respectively. A more in-depth study of the effects of part-whole correlation on regression-type analyses (e.g., multiple regression, residual analysis, and ANCOVA) is lacking, and as a result, this potential problem is often ignored. For instance,

https://www.jstor.org/stable/10.1086/316661

Controlling for Body Mass Effects: Is Part‐Whole Correlation Important?

We investigated the quantitative matching of plasma yolk precursor supply (the plasma pool) to follicle demand during yolk formation in European starlings (Sturnus vulgaris). Plasma concentrations of the two yolk precursors, vitellogenin (VTG) and very low density lipoprotein (VLDL), were only elevated coincident with rapid yolk development (RYD) and matched variation in total yolky follicle mass. VTG and VLDL were low (<0.4 μg/mL and <4.2 mg/mL, respectively) in nonbreeders and prebreeders with no yolky follicles, and at clutch completion. They increased to 4.02 μg/mL and 19.4 mg/mL in birds with a full follicle hierarchy (F1–F4), and concentrations then remained high and actually increased up to the point where only a single, yolky (F1) follicle remained. However, there was some evidence for mismatching of supply and demand: (a) precursor concentrations increased throughout the laying cycle even though the number of developing follicles decreased. We suggest that this is because of a requiremen...

https://www.jstor.org/stable/10.1086/320427

Follicular Development and Plasma Yolk Precursor Dynamics through the Laying Cycle in the European Starling (Sturnus vulgaris)

Summary 1. The seasonal decline in clutch size observed in many avian populations may be due to (a) a causal effect of the timing of breeding or (b) variation in individual quality (i.e. lower quality individuals lay fewer eggs and lay later in the season). 2. To distinguish between these two hypotheses, we manipulated the timing of breeding of European starlings ( Sturnus vulgaris L.) by removing first clutches to induce the production of replacement clutches. This experiment was performed at two sites over three breeding seasons. 3. To test whether the within-individual trend in clutch size differed from the seasonal decline in clutch size observed in the population, we devised a novel randomization test that overcomes some of the potential limitations of previously used analyses. 4. We observed no within-female decline in clutch size in any year at either site. Therefore, clutch removal did not appear to manipulate female quality (due to the costs of egg production), a potentially confounding factor in such experiments; only the timing of breeding was manipulated. 5. The within-individual seasonal trend in clutch size differed significantly from the population decline in four of six cases (year‐site combinations); there is good reason to believe that the lack of a significant difference in the two other cases was due to low statistical power. Thus, our data support the hypothesis that the season decline in clutch size in this species is due to variation in female quality. 6. The between-year repeatability of clutch size was 0·47 and significantly different from zero, whereas that of relative laying date was much lower (‐0·23) and non-significant. The repeatability data are thus consistent with the quality hypothesis: clutch size is characteristic of individuals regardless of their timing of breeding. 7. Female body mass at the beginning of incubation was not related consistently to clutch size or laying date, and therefore does not appear to be an indicator of female quality in this context.

/pdf/seasonal-decline-in-clutch-size-in-european-starlings-a-hikv0xfj6u.pdf

Seasonal decline in clutch size in European starlings: a novel randomization test to distinguish between the timing and quality hypotheses

Costs of reproduction might be mediated by a physiological (resource allocation) trade-off between immune function and reproductive effort, and several recent studies have shown that an experimental increase in reproductive effort is associated with decreased immune function. Here we test the complementary prediction of this hypothesis: that increased immune function (specific antibody production) depresses reproductive output. Female European starlings (Sturnus vulgaris) were injected with a non-pathogenic antigen (sheep red blood cells) following completion of laying of their first clutch, to stimulate an in vivo humoral immune response (primary antibody production). We induced laying of a second clutch by removing the first clutch, and assessed changes in reproductive performance in individual females pre- and post-treatment. Injection of sheep red blood cells produced a significant antibody response in 96% (n=29) of treated females, with titres comparable to previous studies (range 1 to 7). However, increased antibody production did not decrease primary or secondary female reproductive effort (re-laying interval, egg size, clutch size, chick growth or fledging success), compared with control, saline-injected birds (n=22). These data do not support a simple resource allocation model for the cost of reproduction, based on a reciprocal, negative relationship between resources allocated to immune function and reproduction.

/pdf/enhanced-immune-function-does-not-depress-reproductive-2lpypxb5fv.pdf

Julian K. Christians

Papers

Avian egg size: variation within species and inflexibility within individuals

Controlling for Body Mass Effects: Is Part‐Whole Correlation Important?

Follicular Development and Plasma Yolk Precursor Dynamics through the Laying Cycle in the European Starling (Sturnus vulgaris)

Seasonal decline in clutch size in European starlings: a novel randomization test to distinguish between the timing and quality hypotheses

Enhanced immune function does not depress reproductive output