Metabolic Enzyme Alterations and Astrocyte Dysfunction in a Murine Model of Alexander Disease With Severe Reactive Gliosis

Alexander disease (AxD) is a rare and fatal neurodegenerative disorder caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP). In this report, a mouse model of AxD (GFAP^Tg;Gfap^+/R236H) was analyzed that contains a heterozygous R236H point mutation in murine Gfap as well as a transgene with a GFAP promoter to overexpress human GFAP. Using label-free quantitative proteomic comparisons of brain tissue from GFAP^Tg;Gfap^+/R236H versus wild-type mice confirmed upregulation of the glutathione metabolism pathway and indicated proteins were elevated in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, which had not been reported previously in AxD. Relative protein-level differences were confirmed by a targeted proteomics assay, including proteins related to astrocytes and oligodendrocytes. Of particular interest was the decreased level of the oligodendrocyte protein, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (Ugt8), since Ugt8-deficient mice exhibit a phenotype similar to GFAP^Tg;Gfap^+/R236H mice (e.g., tremors, ataxia, hind-limb paralysis). In addition, decreased levels of myelin-associated proteins were found in the GFAP^Tg;Gfap^+/R236H mice, consistent with the role of Ugt8 in myelin synthesis. Fabp7 upregulation in GFAP^Tg;Gfap^+/R236H mice was also selected for further investigation due to its uncharacterized association to AxD, critical function in astrocyte proliferation, and functional ability to inhibit the anti-inflammatory PPAR signaling pathway in models of amyotrophic lateral sclerosis (ALS). Within Gfap⁺ astrocytes, Fabp7 was markedly increased in the hippocampus, a brain region subjected to extensive pathology and chronic reactive gliosis in GFAP^Tg;Gfap^+/R236H mice. Last, to determine whether the findings in GFAP^Tg;Gfap^+/R236H mice are present in the human condition, AxD patient and control samples were analyzed by Western blot, which indicated that Type I AxD patients have a significant fourfold upregulation of FABP7. However, immunohistochemistry analysis showed that UGT8 accumulates in AxD patient subpial brain regions where abundant amounts of Rosenthal fibers are located, which was not observed in the GFAP^Tg;Gfap^+/R236H mice.     

MV-mimicking micelles loaded with PEG-serine-ACP nanoparticles to achieve biomimetic intra/extra fibrillar mineralization of collagen in vitro

Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering.     

The effects of superoxide dismutase-rich melon pulp concentrate on inflammation,antioxidant status and growth performance of challenged post-weaning piglets

Piglets can often suffer impaired antioxidant status and poor immune response during post-weaning, especially when chronic inflammation takes place, leading to lower growth rates than expected. Oral administration of dietary antioxidant compounds during this period could be a feasible way to balance oxidation processes and increase health and growth performance. The aim of the trial was to study the effects of an antioxidant feed supplement (melon pulp concentrate) that contains high concentration of the antioxidant superoxide dismutase (SOD) on inflammation, antioxidant status and growth performance of lipopolysaccharide (LPS) challenged weaned piglets. In total, 48 weaned piglets were individually allocated to four experimental groups in a 2×2 factorial design for 29 days. Two different dietary treatments were adopted: (a) control (CTR), fed a basal diet, (b) treatment (MPC), fed the basal diet plus 30 g/ton of melon pulp concentrate. On days 19, 21, 23 and 25 half of the animals within CTR and MPC groups were subjected to a challenge with intramuscular injections of an increasing dosage of LPS from Escherichia coli (serotype 0.55:B5) (+) or were injected with an equal amount of PBS solution (−). Blood samples were collected at the beginning of the trial and under the challenge period for interleukin 1β, interleukin 6, tumour necrosis factor α, haptoglobin, plasma SOD activity, total antioxidant capacity, reactive oxygen species, red blood cells and plasma resistance to haemolysis, and 8-oxo-7, 8-dihydro-2’-deoxyguanosine. Growth performance was evaluated weekly. A positive effect of melon pulp concentrate was evidenced on total antioxidant capacity, half-haemolysis time of red blood cells, average daily gain (ADG) and feed intake, while LPS challenge increased pro-inflammatory cytokines and haptoglobin serum concentrations, with a reduced feed intake and gain : feed (G : F). The obtained results show that oral SOD supplementation with melon pulp concentrate ameliorates the total antioxidant capacity and the half-haemolysis time in red blood cell of post-weaning piglets, with positive results on growing performance.     

Infrared spectroscopy of proteins

This review discusses the application of infrared spectroscopy to the study of proteins. The focus is on the mid-infrared spectral region and the study of protein reactions by reaction-induced infrared difference spectroscopy.     

Variations of D (-)-beta-hydroxybutyrate dehydrogenase activity of rat liver mitochondria during post-natal development

1. D(-)-beta-hydroxybutyrate dehydrogenase specific activity of rat liver mitochondria changes during ontogenesis: at birth, the activity is low, then increases to a maximum at 12 days, decreases until 50 days to keep constant thereafter. At the same time, mitochondrial protein amount increases regularly while succinatecytochrome c reductase specific activity slightly increases after birth to keep constant afterwards. 2. The observed changes in activity of D(-)-beta-hydroxybutyrate dehydrogenase are not related to possible interactions between the enzyme and phospholids since addition of lecithin to mitochondria does not change the activity. 3. Electrophoresis of mitochondrial proteins isolated from rats at different development stages demonstrates the presence of a protein band characterized by the same electrophoretic mobility as beta-hydroxybutyrate dehydrogenase and by significative changes of its proportion during maturation: the relative amount of this protein increases from the new-born to the 10-12 days old rat, to decrease afterwards. 4. These findings may signify that the increased activity of the enzyme with a maximum at 10-12 days followed by a decrease is related to the rate of the enzymes biosynthesis.     

CHARACTER DISCRIMINATORY POWER,CHARACTER-SET CONGRUENCE,AND THE CLASSIFICATION OF INDIVIDUALS FROM HYBRID ZONES: AN EXAMPLE USING STONE CRABS (MENIPPE)

Many investigators categorize individuals from hybrid zones to facilitate comparisons among genotypic classes (e.g., parental, F₁, backcross) for comparative studies in which components of fitness or geographic variation are being analyzed. Frequently, multiple character sets representing genetically independent traits are used to classify these individuals and various methodologies are employed to combine the classifications obtained from the different character sets. We adapted the principles of total evidence and taxonomic congruence (two formalized approaches used by systematists in formulating phylogenetic hypotheses) to address the problem of discriminating hybridizing species and classifying individuals from hybrid zones. As our model, we used two morphological (coloration and morphometric) and two molecular (allozyme and mitochondrial DNA restriction-fragment-length polymorphism) character sets that differentiate two stone crab species (Menippe adina and M. mercenaria). Using principal-components analysis, we determined that combining character sets and eliminating characters or character sets that did not have large eigenvector coefficients for the principal component that best separated the two species yielded the highest level of discrimination between species and allowed us to classify a broad range of morpho-genotypes as hybrids. For the stone crabs, three diagnostic allozyme loci and five diagnostic coloration characters best separated the species. The two character sets were not completely congruent, but they agreed in their classification of 50% of the individuals from the hybrid zone and rarely strongly disagreed in their classifications. Classification discrepancies between the two character sets probably represent variation between traits in interspecific gene flow rather than intraspecific, ecologically mediated variation. Our results support the assertions of previous investigators who espoused the benefits associated with using multiple character sets to classify individuals from hybrid zones and demonstrate that, if character sets are reasonably congruent and numerically balanced, combining diagnostic characters from multiple character sets (a total-evidence approach) can enhance discriminatory power between species and facilitate the assignment of hybrid-zone individuals to genotypic classes. On the contrary, classifying hybrid-zone individuals using character sets separately (a taxonomic-congruence approach) provides the opportunity to compare levels of introgression between species and to assess reasons for discordance among the data sets.     

Effect of hyperoxidized guanine on DNA primer-template structures: Spiroiminodihydantoin leads to strand slippage

Oxidation of guanine in DNA can lead to mutagenic lesions such as 7-hydro-8-oxoguanine (oG). Upon further oxidation, a more mutagenic lesion, spirominodihydantoin (Sp), can occur. In this study, nuclear magnetic resonance (NMR) investigations were performed to determine the structural features of DNA primer-template models with 5′-GG, 5′-G(oG), 5′-G(Sp) and 5′-T(Sp) templates, that mimic the situation in which the downstream G of the template has been oxidized to oG or hyperoxidized to Sp. Our results show that misalignment occurs only in the 5′-G(Sp) and 5′-T(Sp) templates, providing structural insights into the observed differences in mutagenicity of Sp and oG during DNA replication.     

Effects of exotic plant invasion on soil nitrogen availability

外来植物入侵对土壤氮循环和氮有效性的影响是入侵成功或进一步加剧的重要原因。通过对比相同研究地点入侵区域和无入侵区域的土壤原位氮状态差异, 探讨了外来植物入侵对土壤氮有效性的影响程度和生理生态学机制。基于107篇相关研究文献数据的整合, 发现植物入侵区域相对于无入侵区域土壤总氮、铵态氮、硝态氮、无机氮、微生物生物量氮含量显著增加, 增幅分别为(50 ± 14)%、(60 ± 24)%、(470 ± 115)%、(69 ± 25)%、(54 ± 20)%。土壤硝态氮含量增幅较大反映硝化作用增强, 这可能增加入侵植物硝态氮利用以及喜硝植物的共存。温带地区植物入侵后土壤的硝态氮含量增幅显著高于亚热带地区。固氮植物入侵后土壤的总氮和无机氮含量增幅均显著高于非固氮植物入侵。木本和常绿植物入侵后土壤的总氮含量增幅分别高于草本和落叶植物入侵; 而土壤铵态氮含量的增幅没有显著差异且与固氮入侵植物占比无明显关系; 然而硝态氮含量的增幅普遍较高且与固氮入侵植物占比显著正相关。外来入侵植物固氮功能以及凋落物质量和数量是影响土壤氮矿化和硝化过程的关键因素。该研究为理解外来植物入侵成功和加剧的机制以及入侵植物功能性状与土壤氮动态之间的关系提供了新的见解。