Individual differences in peripheral blood immunological and hormonal measures in adult male rhesus macaques (Macaca mulatta): Evidence for temporal and situational consistency

A growing body of research has indicated that consistent individual differences exist in physiological systems with which the immune system interacts. Few data have been reported that demonstrate stable individual differences in immunological measures, however. In the present study, enumerative measures of immune system activity were examined in 36 adult male rhesus macaques over a 13 month period under baseline conditions as well as under conditions of pharmacological and physical challenge. Blood samples were assayed for plasma concentrations of ACTH and cortisol, as well as neutrophil, total lymphocyte, CD4+ and CD8+ lymphocyte numbers, and the CD4/CD8 ratio. Analyses revealed that individual differences in the CD4/CD8 ratio and, to a lesser extent, plasma ACTH and cortisol concentrations, and neutrophil and CD4+ lymphocyte numbers were consistent across situations and times, despite changes in mean values during the various blood sampling sessions. The results suggest that the CD4/CD8 ratio might be considered trait-like and a useful immunological measure of biobehavioral organization. Am. J. Primatol. 44:29–41, 1998. © 1998 Wiley-Liss, Inc.     

郭岩山不同海拔丝栗栲细根功能性状及其与土壤因子的关系

为揭示丝栗栲(Castanopsis fargesii)细根功能性状对环境变化的适应机制,对郭岩山500、700、900 m海拔处丝栗栲细根功能性状及其与土壤因子的关系进行研究。结果表明,丝栗栲细根生物量与细根根长密度、表面积密度、组织密度及体积密度呈正相关,细根根长密度、体积密度、表面积密度和比根长4个性状间均呈极显著正相关关系,且均与细根组织密度呈显著负相关。根际土含水量、C和N含量与细根比根长、根长密度、体积密度、表面积密度均存在显著正相关关系,而土壤容重与细根组织密度呈正相关。海拔700 m的细根生物量、根长密度、表面积密度及体积密度显著大于海拔500和900 m的。500和900 m海拔的根长密度、表面积密度与土壤深度呈负相关,而500 m海拔细根的组织密度与土壤深度呈正相关。因此,郭岩山丝栗栲通过改变细根功能性状来适应海拔和土壤的变化。     

梭梭和骆驼刺对干旱的适应策略差异

该研究目的在于揭示干旱荒漠中2个优势种梭梭(Haloxylon ammodendron)和骆驼刺(Alhagi sparsifolia)是否在适应干旱的策略上存在差异。在新疆艾比湖自然保护区内自然形成的干旱胁迫梯度上,首先测量梭梭和骆驼刺的3类功能性状(叶、光合和水力性状);其后分析性状随干旱梯度的变化,性状在两个物种之间的差别,两物种应对干旱胁迫时所采用策略的差异性。结果显示:梭梭和骆驼刺的功能性状在干旱梯度上的变化存在不同。除干物质含量外,其余10个功能性状在梭梭和骆驼刺间均存在显著差异,但在干旱梯度与物种的共同作用下,梭梭与骆驼刺之间性状差异呈现缩小趋势。Pearson相关分析表明,骆驼刺显著相关的性状仅有10对,而梭梭有15对。主成分分析可将梭梭11个功能性状分为与植物抗旱能力有关的2个典型性状组合类别,即干旱胁迫-碳获取组和抗干旱胁迫组。但对骆驼刺,很难划分出与抗旱有关的性状组合。该研究结果表明,相较梭梭,骆驼刺具有更强的耐旱能力,属于保守型物种,性状之间联系不显著,但梭梭的性状之间联系紧密,它利用各种性状之间的权衡和补偿关系尽可能地减小干旱胁迫。该研究揭示了干旱荒漠中不同生...     

Heritability of a Quantitative and Qualitative Protease Inhibitor Polymorphism in Nicotiana attenuata

Abstract: Many plant species contain chemical defenses that protect them against herbivores. Despite the benefit of these chemical defenses, not all individuals contain high levels of these compounds. In the native tobacco Nicotiana attenuata we found that plants from three natural populations differed considerably in their ability to produce trypsin protease inhibitors (PIs), which are defensive proteins that reduce herbivore damage to plants. Plants from a Utah (U) population produced high levels, whereas plants from Arizona (A) contained no detectable PI levels. Californian (C) plants had intermediate levels. The PI-producing U and C plants thus differ quantitatively from each other, whereas they both differ qualitatively from PI-deficient A plants. Here we analyze how PI production is inherited in N. attenuata with the ultimate goal of better understanding how the quantitative and qualitative differences between the three populations have evolved. Using a series of classical crossing designs, we determined that the ability to produce PIs is inherited as a dominant Mendelian trait. PI-deficient plants contain two non-functional recessive alleles, whereas heterozygous plants or homozygous dominant plants both are able to produce PIs. Similarly, the level of constitutive PIs may be determined by its genotype, either by an interaction between a functional and a non-functional allele in heterozygotes, or by a factor on the PI allele itself in homozygous C plants. Based on these data and on previous studies with A and U plants we postulate that the PI-deficient A plants may have originated from a mutant that lost its ability to produce PIs. The fitness loss due to reduced herbivore resistance may be offset by the fitness gain associated with increased competitive ability, a trade-off which may maintain this mutation in the Arizona population.     

On the use of the transmission disequilibrium test to detect pseudo‐autosomal variants affecting traits with sex‐limited expression

We herein describe the realization of a genome‐wide association study for scrotal hernia and cryptorchidism in Norwegian and Belgian commercial pig populations. We have used the transmission disequilibrium test to avoid spurious associations due to population stratification. By doing so, we obtained genome‐wide significant signals for both diseases with SNPs located in the pseudo‐autosomal region in the vicinity of the pseudo‐autosomal boundary. By further analyzing these signals, we demonstrate that the observed transmission disequilibria are artifactual. We determine that transmission bias at pseudo‐autosomal markers will occur (i) when analyzing traits with sex‐limited expression and (ii) when the allelic frequencies at the marker locus differ between X and Y chromosomes. We show that the bias is due to the fact that (i) sires will preferentially transmit the allele enriched on the Y (respectively X) chromosome to affected sons (respectively daughters) and (ii) dams will appear to preferentially transmit the allele enriched on the Y (respectively X) to affected sons (respectively daughters), as offspring inheriting the other allele are more likely to be non‐informative. We define the conditions to mitigate these issues, namely by (i) extracting information from maternal meiosis only and (ii) ignoring trios for which sire and dam have the same heterozygous genotype. We show that by applying these rules to scrotal hernia and cryptorchidism, the pseudo‐autosomal signals disappear, confirming their spurious nature.     

Mapping of quantitative trait loci affecting eggshell quality on chromosome 9 in an F2 intercross between two chicken lines divergently selected for eggshell strength

Broken and cracked eggshells are major causes of significant economic losses to the egg production industry. The quantitative trait loci (QTL) on chromosome 9 influencing the quality of eggshells were identified by analysing an intercross between two parent lines developed from the same founder population by a two-way selection for eggshell strength with non-destructive deformation conducted over 14 generations. Chromosome-wide highly significant ( P  <   0.01) QTL associated with egg weight (EW), short length of egg (SLE), long length of egg (LLE) and eggshell weight were mapped to the distal region of chromosome 9. Among the QTL affecting EW, SLE and LLE, ovocalyxin-32 was identified as a potential candidate gene influencing eggshell traits. Marker-assisted selection based on these QTL could be used to develop strategies for reducing the breakage and cracking of eggs in commercial layer houses.     

Quantitative trait loci with effects on feed efficiency traits in Hereford × composite double backcross populations

Two half-sib families of backcross progeny were produced by mating F₁ Line 1 Hereford (L1) × composite gene combination (CGC) bulls with L1 and CGC cows. Feed intake and periodic weights were measured for 218 backcross progeny. These progenies were genotyped using 232 microsatellite markers that spanned the 29 BTA. Progeny from L1 and CGC females was analysed separately using composite interval mapping to find quantitative trait loci (QTL) affecting daily dry matter intake (DMI), average daily gain (ADG), feed conversion (FCR) and residual feed intake (RFI). Results from both backcrosses were pooled to find additional QTL. In the backcross to L1, QTL were detected for RFI and DMI on BTA11, FCR on BTA16, and ADG on BTA9. In the backcross to CGC, QTL were detected for RFI on BTA10, FCR on BTA12 and 16 and ADG on BTA15 and 17. After pooling, QTL were detected for RFI on BTA 2, 6, 7, 10, 11, 13 and 16; for FCR on BTA 9, 12, 16, 17 and 21; for ADG on BTA 9, 14, 15, 17; and for DMI on BTA 2, 5, 6, 9, 10, 11, 20 and 23.     

Proline Metabolism and Transport in Maize Seedlings at Low Water Potential

The growing zone of maize seedling primary roots accumulatesproline at low water potential. Endosperm removal and excisionof root tips rapidly decreased the proline pool and greatlyreduced proline accumulation in root tips at low water potential.Proline accumulation was not restored by exogenous amino acids.Labelling root tips with [¹⁴C]glutamate and [¹⁴C]proline showedthat the rate of proline utilization (oxidation and proteinsynthesis) exceeded the rate of biosynthesis by five-fold athigh and low water potentials. This explains the reduction inthe proline pool following root and endosperm excision and theinability to accumulate proline at low water potential. Theendosperm is therefore the source of the proline that accumulatesin the root tips of intact seedlings. Proline constituted 10% of the amino acids released from the endosperm. [¹⁴C]Prolinewas transported from the scutellum to other parts of the seedlingand reached the highest concentration in the root tip. Less[¹⁴C]proline was transported at low water potential but becauseof the lower rate of protein synthesis and oxidation, more accumulatedas proline in the root tip. Despite the low biosynthesis capacityof the roots, the extent of proline accumulation in relationto water potential is precisely controlled by transport andutilization rate.     

Rapid Identification of Major-Effect Genes Using the Collaborative Cross

The Collaborative Cross (CC) was designed to facilitate rapid gene mapping and consists of hundreds of recombinant inbred lines descended from eight diverse inbred founder strains. A decade in production, it can now be applied to mapping projects. Here, we provide a proof of principle for rapid identification of major-effect genes using the CC. To do so, we chose coat color traits since the location and identity of many relevant genes are known. We ascertained in 110 CC lines six different coat phenotypes: albino, agouti, black, cinnamon, and chocolate coat colors and the white-belly trait. We developed a pipeline employing modifications of existing mapping tools suitable for analyzing the complex genetic architecture of the CC. Together with analysis of the founders’ genome sequences, mapping was successfully achieved with sufficient resolution to identify the causative genes for five traits. Anticipating the application of the CC to complex traits, we also developed strategies to detect interacting genes, testing joint effects of three loci. Our results illustrate the power of the CC and provide confidence that this resource can be applied to complex traits for detection of both qualitative and quantitative trait loci.