Metabolic robustness in young roots underpins a predictive model of maize hybrid performance in the field

Heterosis has been extensively exploited for yield gain in maize (Zea mays L.). Here we conducted a comparative metabolomics‐based analysis of young roots from in vitro germinating seedlings and from leaves of field‐grown plants in a panel of inbred lines from the Dent and Flint heterotic patterns as well as selected F₁ hybrids. We found that metabolite levels in hybrids were more robust than in inbred lines. Using state‐of‐the‐art modeling techniques, the most robust metabolites from roots and leaves explained up to 37 and 44% of the variance in the biomass from plants grown in two distinct field trials. In addition, a correlation‐based analysis highlighted the trade‐off between defense‐related metabolites and hybrid performance. Therefore, our findings demonstrated the potential of metabolic profiles from young maize roots grown under tightly controlled conditions to predict hybrid performance in multiple field trials, thus bridging the greenhouse–field gap.     

Interspecific hybridization causes long‐term phylogenetic discordance between nuclear and mitochondrial genomes in freshwater fishes

Classification, phylogeography and the testing of evolutionary hypotheses rely on correct estimation of species phylogeny. Early molecular phylogenies often relied on mtDNA alone, which acts as a single linkage group with one history. Over the last decade, the use of multiple nuclear sequences has often revealed conflict among gene trees. This observation can be attributed to hybridization, lineage sorting, paralogy or selection. Here, we use 54 groups of fishes from 48 studies to estimate the degree of concordance between mitochondrial and nuclear gene trees in two ecological grades of fishes: marine and freshwater. We test the hypothesis that freshwater fish phylogenies should, on average, show more discordance because of their higher propensity for hybridization in the past. In keeping with this idea, concordance between mitochondrial and nuclear gene trees (as measured by proportion of components shared) is on average 50% higher in marine fishes. We discuss why this difference almost certainly results from introgression caused by greater historical hybridization among lineages in freshwater groups, and further emphasize the need to use multiple nuclear genes, and identify conflict among them, in estimation of species phylogeny.     

Lasting effects of early life stress in mice: interaction of maternal environment and infant genes

In the mouse, a powerful paradigm of early life stress, infant maternal separation (IMS), can trigger emotional and cognitive dysfunctions in adulthood similar to those found in humans with a history of childhood adversity. The magnitude of IMS effects differs among diverse inbred strains suggesting an interaction between the genetic background of pups and the maternal care they received. Here, we investigated this interaction with studies on reciprocal F1 hybrid mice of the stress‐susceptible Balb/c and the resilient C57Bl/6 strains that were either raised by Balb/c mothers (low maternal care) or by C57Bl/6 mothers (higher maternal care) with or without IMS exposure. The ultrasonic vocalization response to isolation was recorded from infant F1 pups, and their emotional, executive cognitive and epigenetic phenotypes were assessed in adulthood. These studies showed that, regardless of the maternal care received, the emotional phenotype of F1 hybrids was not significantly affected by IMS exposure. However, F1 pups raised by Balb/c (but not C57Bl/6) mothers during IMS exposure exhibit deficits in working memory and attention‐set‐shifting in adulthood. They also exhibit reduced histone deacetylase 1 levels at promotors of brain‐derived neurotrophic factor and early growth response 2 genes, and abnormally high induction of expression of these genes during cognitive testing. As one of affected genes was previously shown to associate with the Balb/c and the other with the C57Bl/6 genetic background, these findings indicate that both parental alleles interact with the maternal environment to modulate the cognitive and epigenetic phenotypes of F1 mice exposed to the IMS.     

A Hybrid Mg2+/Li+ Battery Based on Interlayer‐Expanded MoS2/Graphene Cathode

The hybrid Mg²⁺/Li⁺ battery (MLIB) is a very promising energy storage technology that combines the advantage of the Li and Mg electrochemistry. However, previous research has shown that the battery performance is limited due to the strong dependence on the Li content in the dual Mg²⁺/Li⁺ electrolyte. This limitation can be circumvented by significantly improving the diffusion kinetics of Mg²⁺ in the electrode, so that both Li⁺ and Mg²⁺ ions can be utilized as charge carriers. Herein, a free‐standing interlayer expanded MoS₂/graphene composite (E‐MG) is demonstrated as a cathode for MLIB. The key advantage of this cathode is to enable the efficient intercalation of both Mg²⁺ and Li⁺. The E‐MG electrode displays a reversible capacity of ≈300 mA h g^?1 at 20 mA g^?1 in an MLIB cell, corresponding to a specific energy density up to ≈316.9 W h kg^?1, which is comparable to that of the state‐of‐the‐art Li‐ion batteries (LIBs) and has no dendrite formation. The composite electrode is stable against cycling with a coulombic efficiency close to 100% at 500 mA g^?1. This new electrode design represents a significant step forward for building a safe and high‐density electrochemical energy storage system.     

成纤维细胞生长因子17研究进展

成纤维细胞生长因子17(FGF17)是成纤维细胞生长因子(FGF)家族的成员之一,并与FGF8、FGF18组成FGF8亚家族。在胚胎时期FGF17扮演重要角色,对多种组织器官起着重要作用。研究发现,FGF17不仅参与了脑部发育和神经形成,而且参与骨骼、动脉的发育和肿瘤等生物过程。现针对FGF17的特点,及其在胚胎发育、神经系统、癌症等方面的作用进行综述。     

Microsatellites for eastern Australian Banksia species

We developed eight primer pairs for Banksia microsatellite markers (five using DNA from Banksia oblongifolia and three from Banksia robur) in order to study the processes of speciation within hybridizing B. oblongifolia, B. robur and Banksia paludosa complex. We genotyped four populations of B. oblongifolia and B. robur, and three of B. paludosa. Numbers of alleles ranged from 1 to 13 across the three species and observed average heterozygosities ranged from 0.000 to 0.833. At least four loci completely discriminated B. robur from B. oblongifolia and three discriminated B. paludosa from B. oblongifolia. Seven of these primers amplified DNA from at least two of three other local species.     

Hybridization and the inheritance of female colour polymorphism in two ischnurid damselflies (Odonata: Coenagrionidae)

Female‐limited polychromatism is frequent in many species of Odonata. Ischnura elegans has three colour morphs: one male‐like coloured (androchrome) and two additional gynochrome brown morphs (infuscans and rufescens‐obsoleta morphs). A total of 19 progenies obtained from once‐mated females were reared in the laboratory in three generations. Results indicate that the colour morphs are controlled by the same genetic system as previously described for I. graellsii, i.e. an autosomal locus with female‐limited expression and with three alleles with a hierarchy of dominance (p^a > pⁱ > p°). Five interspecific crossings between female I. graellsii and male I. elegans, five crossings between hybrid females and male I. elegans and one crossing between female I. graellsii and a hybrid male further confirmed that the genetic system is the same in both species. A survey of morph frequencies in north‐west Spain revealed that I. elegans shows high variability in androchrome frequency (4–91%) between nearby populations, whereas in I. graellsii androchromes never are the majority morph (5–40%). The highest androchrome frequency in I. graellsii was found in populations closest to a locality where both species have hybridized, and that now has the highest androchrome frequency of I. elegans. We hypothesize that I. elegans genes have been incorporated into the genome of I. graellsii resulting in increased androchrome frequency in the latter species. Low androchrome frequency in I. elegans seems also related to the influence of I. graellsii genes. Therefore, we suggest that hybridization between both taxa is contributing to the temporal maintenance of contrasting androchrome frequencies in nearby populations. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 471–481.     

An Approach to Further Enhance the Cellular Productivity of Exogenous Protein Hyper-producing Chinese Hamster Ovary (CHO) Cells

The cell line D29, which was easily and rapidly established by the promoter-activated production and glutamine synthetase hybrid system, secreted recombinant human interleukin-6 (hIL-6) at a productivity rate of 39.5 μg 10⁻⁶ cells day⁻¹, one of the highest reported levels worldwide. The productivity rate was about 130-fold higher than that of the cell line A7, which was established without both promoter activation and gene amplification. Although D29 cells had a high copy number and high mRNA level of the hIL-6 gene as well as a high secretion rate of hIL-6, large amounts of intracellular hIL-6 protein accumulated in D29 cells compared to A7 cells. Northern blotting analysis showed no change in the GRP78/BiP expression level in D29 cells. In contrast, an electrophoresis mobility shift assay revealed strong activation of NF-κB in D29 cells. These results suggest that large amounts of hIL-6 translated from large amounts of hIL-6 mRNA cause excess accumulation of intact hIL-6 in the endoplasmic reticulum (ER), and that subsequent negative feedback signals via the ER overload response inhibit hIL-6 protein secretion. To enhance the hIL-6 productivity rate of D29 cells by releasing the negative feedback signals, the effect of pyrrolidinedithiocarbamate, an inhibitor of NF-κB activation, was examined. Suppression of NF-κB activation in D29 cells produced a 25% augmentation of the hIL-6 productivity rate. Therefore, in highly productive cells like D29 cells, the release of negative feedback signals could increase the total amount of recombinant protein secretion.