Animal personality traits such as boldness, activity and aggressiveness have been described for many animal species. However, why some individuals are consistently bolder or more active than others, for example, is currently obscure. Given that life-history tradeoffs are common and known to promote inter-individual differences in behavior, we suggest that consistent individual differences in animal personality traits can be favored when those traits contribute to consistent individual differences in productivity (growth and/or fecundity). A survey of empirical studies indicates that boldness, activity and/or aggressiveness are positively related to food intake rates, productivity and other life-history traits in a wide range of taxa. Our conceptual framework sets the stage for a closer look at relationships between personality traits and life-history traits in animals.

https://www.cell.com/trends/ecology-evolution/pdf/S0169-5347(08)00159-6.pdf

Are animal personality traits linked to life-history productivity?

The lack of myostatin promotes growth of skeletal muscle, and blockade of its activity has been proposed as a treatment for various muscle-wasting disorders. Here, we have examined two independent mouse lines that harbor mutations in the myostatin gene, constitutive null (Mstn−/−) and compact (Berlin High Line, BEHc/c). We report that, despite a larger muscle mass relative to age-matched wild types, there was no increase in maximum tetanic force generation, but that when expressed as a function of muscle size (specific force), muscles of myostatin-deficient mice were weaker than wild-type muscles. In addition, Mstn−/− muscle contracted and relaxed faster during a single twitch and had a marked increase in the number of type IIb fibers relative to wild-type controls. This change was also accompanied by a significant increase in type IIB fibers containing tubular aggregates. Moreover, the ratio of mitochondrial DNA to nuclear DNA and mitochondria number were decreased in myostatin-deficient muscle, suggesting a mitochondrial depletion. Overall, our results suggest that lack of myostatin compromises force production in association with loss of oxidative characteristics of skeletal muscle.

https://www.pnas.org/content/pnas/104/6/1835.full.pdf

Lack of myostatin results in excessive muscle growth but impaired force generation

Associations between milk protein polymorphisms and milk production traits

Myostatin, a member of the TGF-β family, has been identified as a powerful inhibitor of muscle growth. Absence or blockade of myostatin induces massive skeletal muscle hypertrophy that is widely attributed to proliferation of the population of muscle fiber-associated satellite cells that have been identified as the principle source of new muscle tissue during growth and regeneration. Postnatal blockade of myostatin has been proposed as a basis for therapeutic strategies to combat muscle loss in genetic and acquired myopathies. But this approach, according to the accepted mechanism, would raise the threat of premature exhaustion of the pool of satellite cells and eventual failure of muscle regeneration. Here, we show that hypertrophy in the absence of myostatin involves little or no input from satellite cells. Hypertrophic fibers contain no more myonuclei or satellite cells and myostatin had no significant effect on satellite cell proliferation in vitro, while expression of myostatin receptors dropped to the limits of detectability in postnatal satellite cells. Moreover, hypertrophy of dystrophic muscle arising from myostatin blockade was achieved without any apparent enhancement of contribution of myonuclei from satellite cells. These findings contradict the accepted model of myostatin-based control of size of postnatal muscle and reorient fundamental investigations away from the mechanisms that control satellite cell proliferation and toward those that increase myonuclear domain, by modulating synthesis and turnover of structural muscle fiber proteins. It predicts too that any benefits of myostatin blockade in chronic myopathies are unlikely to impose any extra stress on the satellite cells.

https://www.pnas.org/content/pnas/106/18/7479.full.pdf

Muscle hypertrophy driven by myostatin blockade does not require stem/precursor-cell activity

Effects of genetic selection for milk yield on energy balance, levels of hormones, and metabolites in lactating cattle, and possible links to reduced fertility ☆

Lines of mice selected for many generations for high or low growth in several laboratories around the world have been collected, and from these, inbred lines are being developed by recurrent full-sib mating in Edinburgh. There are seven high selected lines and four low lines (each low line is from the same base population as one of the high lines), and the histories of each are summarized. Mean body weight of males at 70 days of age in the Edinburgh laboratory in the heaviest inbred line (77 g) is 4.8-fold higher than in the lightest line (16 g), and 1.9-fold higher than in the least extreme high line (41 g). Litter size, food intake, and fat content also differ substantially. These inbred extreme selected lines are a uniquely valuable resource for QTL or gene mapping, candidate gene identification, and elucidation of epistatic effects.

Inbred lines of mice derived from long-term growth selected lines: unique resources for mapping growth genes

Heterosis in Friesian x Sahiwal crosses

Pleiotrope irkungen von β‐Lactoglobulin‐ und Casein‐Genotypen auf Milchfett‐ und Milchproteinmengen des bayerischen Fleckviehs und Braunviehs1

Overdominance as cause for heterosis in poultry

Summary

The follicle stimulating hormone receptor (FSHR) is a unique member of the glycoprotein hormone receptor family. Its expression is highly gonad- and cell-specific, demonstrating its importance for oogenesis and spermatogenesis. Based on published porcine FSHR gene sequence, a pair of primers was designed to amplify a 674-bp fragment of exon 10. The genetic polymorphism was detected by PCR-single strand conformation polymorphism (PCR-SSCP) analysis and a C/T substitution was revealed by direct sequencing of PCR products of putative SSCP homozygotes. This C-to-T transition led to an isoleucine 377-to-threonine substitution in the porcine FSHR protein. Bi-directional PCR amplification of specific allele (Bi-PASA) assay was developed to genotype this C/T substitution on 75 pure Chinese Erhualian (347 litter records) and 113 pure German Landrace sows (501 litter records). The general linear model (GLM) procedure of SAS analysis revealed significant associations of the marker with total piglets born in these two breeds, but showing different allele effects. In Chinese Erhualian pigs, the homozygous T/T genotype was associated with 2.12 and 1.46 piglets more in total born than the homozygous C/C and heterozygous C/T genotype (p = 0.0137). In contrast, German Landrace pigs of homozygote T/T produced 1.92 and 2.14 piglets less in total born than pigs of homozygote C/C and heterozygote C/T (p = 0.0499). This result indicates that genes could interact differently due to the genetic background in livestock species.


Zusammenfassung

Unterschiedliche Alleleffekte einer Mutation im Follikel stimulierenden Hormon Rezeptor (FSHR)-Gen auf die Wurfgrose bei Schweinen der chinesischen Erhualian Rasse und der Deutschen Landrasse

Der FSH-Rezeptor stellt ein Mitglied der Glykoprotein Rezeptor Familie dar. Die Expression dieses Gens ist sehr gonaden- und zellspezifisch, was die Bedeutung dieses Rezeptors sowohl fur die Oogenese als auch fur die Spermatogenese zeigt. Basierend auf der publizierten porcinen FSHR-Gensequenz wurden Primer zur Amplifizierung eines 674 bp Fragmentes aus dem Exon 10 abgeleitet. Der genetische Polymorphismus wurde durch PCR-SSCP Analyse dargestellt. Durch direkte Sequenzierung der PCR-Produkte von Tieren, die aufgrund der SSCP-Analyse als homozygot identifiziert wurden, konnte eine C/T Substitution entdeckt werden. Diese C/T Transition fuhrt zu einem Isoleucin-Threonin Austausch an der Position 377 des porcinen FSHR-Proteins. An 75 reinrassigen Sauen der chinesischen Erhualian-Rasse mit insgesamt 347 Wurfen, sowie 113 reinrassigen Sauen der Deutschen Landrasse mit insgesamt 501 Wurfen wurde ein Bi-PASA Nachweis zur Genotypisierung dieser C/T Substitution entwickelt. Die GLM Prozedur der SAS Analyse zeigte in beiden Rassen signifikante Assoziationen dieses Markers mit der absoluten Anzahl der geborenen Ferkel, wobei aber unterschiedliche Alleleffekte beobachtet werden konnten. In der Rasse des chinesischen Erhualian-Schweins war der T/T Genotyp mit 2,12 und 1,46 mehr geborenen Ferkeln bezogen auf die Gesamtzahl der geborenen Ferkel assoziiert als bei den homozygoten C/C bzw. den heterozygoten C/T Genotypen (p = 0,0137). Im Gegensatz hierzu hatten die homozygoten T/T Sauen der Deutschen Landrasse 1,92 und 2,14 Ferkel weniger in Bezug auf die Gesamtzahl der geborenen Ferkel als diejenigen mit homozygotem C/C bzw. heterozygotem C/T Genotyp (p = 0,0499). Dieses Ergebnis deutet an, dass Gene in Abhangigkeit vom genetischen Hintergrund der betreffenden Haustierart unterschiedlich wirken konnen.

A missense mutation in the follicle stimulating hormone receptor (FSHR) gene shows different allele effects on litter size in Chinese Erhualian and German Landrace pigs

F. Pirchner

Papers

Inbred lines of mice derived from long-term growth selected lines: unique resources for mapping growth genes

Heterosis in Friesian x Sahiwal crosses

Pleiotrope irkungen von β‐Lactoglobulin‐ und Casein‐Genotypen auf Milchfett‐ und Milchproteinmengen des bayerischen Fleckviehs und Braunviehs1

Overdominance as cause for heterosis in poultry

A missense mutation in the follicle stimulating hormone receptor (FSHR) gene shows different allele effects on litter size in Chinese Erhualian and German Landrace pigs