Nutrients are assimilated efficiently by Lymantria dispar caterpillars from the mature leaves of trees in the Salicaceae

The efficient aquisition of nutrients from leaves by insect herbivores increases their nutrient assimilation rates and overall fitness. Caterpillars of the gypsy moth (Lymantria dispar L.) have high protein assimilation efficiencies (PAE) from the immature leaves of trees such as red oak (Quercus rubra) and sugar maple (Acer saccharum) (71–81%) but significantly lower PAE from their mature leaves (45–52%). By contrast to this pattern, both PAE and carbohydrate assimilation efficiencies (CAE) remain high for L. dispar larvae on the mature leaves of poplar (Populus alba × Populus tremula) grown in greenhouse conditions. The present study tests two alternative hypotheses: (i) outdoor environmental stresses cause decreased nutrient assimilation efficiencies from mature poplar leaves and (ii) nutrients in the mature leaves of trees in the poplar family (Salicaceae) remain readily available for L. dispar larvae. When poplar trees are grown in ambient outdoor conditions, PAE and CAE remain high (approximately 75% and 78%, respectively) in L. dispar larvae, in contrast to the first hypothesis. When larvae feed on the mature leaves of species in the Salicaceae [aspen (Populus tremuloides), cottonwood (Populus deltoides), willow (Salix nigra) and poplar], PAE and CAE also remain high (68–76% and 72–92%, respectively), consistent with the second hypothesis. Larval growth rates are strongly associated with protein assimilation rates, and more strongly associated with protein assimilation rates than with carbohydrate assimilation rates. It is concluded that tree species in the Salicaceae are relatively high‐quality host plants for L. dispar larvae, in part, because nutrients in their mature leaves remain readily available.     

Altitudinal distribution limits of aquatic macroinvertebrates: an experimental test in a tropical alpine stream

1. Temperature and oxygen are recognised as the main drivers of altitudinal limits of species distributions. However, the two factors are linked, and both decrease with altitude, why their effects are difficult to disentangle. 2. This was experimentally addressed using aquatic macroinvertebrates; larvae of Andesiops (Ephemeroptera), Claudioperla, (Plecoptera), Scirtes (Coleoptera) and Anomalocosmoecus (Trichoptera), and the amphipod Hyalella in an Ecuadorian glacier‐fed stream (4100–4500 m a.s.l.). The following were performed: (i) quantitative benthic sampling at three sites to determine altitudinal patterns in population densities, (ii) transplants of the five taxa upstream of their natural altitudinal limit to test the short‐term (14 days) effect on survival, and (iii) in situ experiments of locomotory activity as a proxy for animal response to relatively small differences in temperature (5 °C vs. 10 °C) and oxygen saturation (55% vs. 62%). 3. The transplant experiment reduced survival to a varying degree among taxa, but Claudioperla survived well at a site where it did not naturally occur. In the in situ experiment, Scirtes and Hyalella decreased their activity at lower oxygen saturation, whereas Andesiops and Anomalocosmoecus did so at a low temperature. The decrease in activity from a high to a low temperature and oxygen for the five taxa was significantly correlated with their mortality in the transplant experiment. 4. Together the present experiments indicate that even relatively small differences in temperature and oxygen may produce effects explaining ecological patterns, and depending on the taxon, either water temperature or oxygen saturation, without clear interacting effects, are important drivers of altitudinal limits.     

一种新型免疫层析技术在临床乳腺癌Her-2蛋白定量检测中的应用

建立一种靶点蛋白质快速定量检测方法。在原有侧向流动免疫层析技术的基础上,通过优化层析材料和纳米微球的均一性、改进检测区的检测方法,经逐点扫描技术,建立标准浓度曲线,以达到对临床靶点蛋白质的定量检测。以乳腺癌组织中的Her2表达为例,通过对已知浓度样品的检测,验证本技术方法的准确度大于96%。另外,以蛋白质免疫印迹作为组织中特定蛋白质检测金标准,分析临床肿瘤组织中Her2蛋白的含量,其准确率也达到95.5%,而免疫组织化学方法检测准确率仅为69.58%。新型免疫层析法检测结果与靶向治疗患者的愈后密切相关(P<0.01)。改进后的新型免疫层析方法能够准确地对临床靶点蛋白质进行定量检测,而且结合侧向流动技术的简单、快速和易用性,这种新型检测方法可以广泛应用于临床组织标本、血液标本和体液标本中靶点蛋白质的临场定量检测,在一定程度上可以替代免疫组化技术。     

Genome‐wide analysis of Italian sheep diversity reveals a strong geographic pattern and cryptic relationships between breeds

Italy counts several sheep breeds, arisen over centuries as a consequence of ancient and recent genetic and demographic events. To finely reconstruct genetic structure and relationships between Italian sheep, 496 subjects from 19 breeds were typed at 50K single nucleotide polymorphism loci. A subset of foreign breeds from the Sheep HapMap dataset was also included in the analyses. Genetic distances (as visualized either in a network or in a multidimensional scaling analysis of identical by state distances) closely reflected geographic proximity between breeds, with a clear north–south gradient, likely because of high levels of past gene flow and admixture all along the peninsula. Sardinian breeds diverged more from other breeds, a probable consequence of the combined effect of ancient sporadic introgression of feral mouflon and long‐lasting genetic isolation from continental sheep populations. The study allowed the detection of previously undocumented episodes of recent introgression (Delle Langhe into the endangered Altamurana breed) as well as signatures of known, or claimed, historical introgression (Merino into Sopravissana and Gentile di Puglia; Bergamasca into Fabrianese, Appenninica and, to a lesser extent, Leccese). Arguments that would question, from a genomic point of view, the current breed classification of Bergamasca and Biellese into two separate breeds are presented. Finally, a role for traditional transhumance practices in shaping the genetic makeup of Alpine sheep breeds is proposed. The study represents the first exhaustive analysis of Italian sheep diversity in an European context, and it bridges the gap in the previous HapMap panel between Western Mediterranean and Swiss breeds.     

FlhF regulates the number and configuration of periplasmic flagella in Borrelia burgdorferi

The Lyme disease bacterium Borrelia burgdorferi has 7–11 periplasmic flagella (PF) that arise from the cell poles and extend toward the midcell as a flat-ribbon, which is distinct from other bacteria. FlhF, a signal recognition particle (SRP)-like GTPase, has been found to regulate the flagellar number and polarity; however, its role in B. burgdorferi remains unknown. B. burgdorferi has an FlhF homolog (BB0270). Structural and biochemical analyses show that BB0270 has a similar structure and enzymatic activity as its counterparts from other bacteria. Genetics and cryo-electron tomography studies reveal that deletion of BB0270 leads to mutant cells that have less PF (4 ± 2 PF per cell tip) and fail to form a flat-ribbon, indicative of a role of BB0270 in the control of PF number and configuration. Mechanistically, we demonstrate that BB0270 localizes at the cell poles and controls the number and position of PF via regulating the flagellar protein stability and the polar localization of the MS-ring protein FliF. Our study not only provides the detailed characterizations of BB0270 and its profound impacts on flagellar assembly, morphology and motility in B. burgdorferi, but also unveils mechanistic insights into how spirochetes control their unique flagellar patterns.     

Effect of fertilizers on Cd accumulation and subcellular distribution of two cosmos species (Cosmos sulphureus and Cosmos bipinnata)

Addition of fertilizer amendments is regarded as an ideal approach to enhancing phytoextraction. However, there is little information available on the influence of common fertilizers on Cd accumulation of two newly reported Cd accumulators, Cosmos sulphureus and Cosmos bipinnata (C. sulphureus and C. bipinnata). The effects of N (CO(NH₂)₂), NP (CO(NH₂)₂ + Ca(H₂PO₄)₂), and NPK (CO(NH₂)₂ + Ca(H₂PO₄)₂ + KCl) fertilizers on Cd accumulation and subcellular distribution of C. sulphureus and C. bipinnata were studied in a 70-d pot experiment. The results showed that Cd uptake of C. sulphureus and C. bipinnata with NPK fertilizer was significantly higher than control, N, and NP fertilizers, especially 3.8- and 4.7-fold higher than control (p < 0.05). Compared with C. bipinnata, C. sulphureus achieved higher biomass and Cd uptake in aboveground parts under fertilizer treatments, especially NPK fertilizer. The Cd subcellular distribution revealed that segregation of Cd to Cd-rich granules (MRG) might play an important role in Cd detoxification in both species. C. sulphureus is more likely than C. bipinnata to separate the Cd in MRG and reduce the partition in the heat-denatured protein fraction, especially with NPK fertilizer. Therefore, C. sulphureus combined with NPK fertilizers could be an effective method to remediate Cd-polluted farmland soils in China.