The importance of arginine mutation for the evolutionary structure and function of phenylalanine hydroxylase gene

Phenylalanine hydroxylase (PAH) gene mutations were investigated in 23 (46 alleles) unrelated phenylketonuria (PKU) patients in Cukurova region. First, all exons of PAH gene were screened by denaturing high performance liquid chromatography (DHPLC), and then, the suspicious samples were analyzed by direct sequencing technique. Consequently, the following results were obtained: IVS10-11g-->a splicing mutation in 27/46 (58.7%), R261Q mutation in 7/46 (15.2%) and E178G, R243X, R243Q, P281L, Y386C, R408W mutations, each found in the frequency of 2/46 (4.3%). In many countries, Arginine mutations have the highest frequency among PAH gene mutations in PKU patients. Although, CpG dinucleotids are effective in mutations resulting in arginine changes, this finding originated from the studies on the causes of mutations rather than the studies on the importance of arginine amino acid. In our analyses, we have detected that a majority of mutations causing a change in arginine and other amino acids concentrated in exon 7 comprising the catalytic domain (residues 143-410) of PAH gene. Several studies has emphasized the role of arginine amino acid; with the following outcomes; arginine repetition is significant for RNA binding proteins, and for histon proteins in eukaryotic gene expression, and also arginine repetition occurring in the structure of signal recognition particle's (SRPs) as a consequence of post-translational processes is very important in terms of gene expression. Therefore, the role of arginine amino acid in PAH gene is rather remarkable in that it shows the role of amino acids in the protein/RNA interaction that has started in the evolutionary process and is still preserved and maintained in the motif formation of active domain structure due to its strong binding properties. Thus, such properties imply that both arginine amino acid and exon 7 is of great significance with regards to the structure and function of the PheOH enzyme.     

甘草粗提物对鲫的免疫调节作用

本研究对中药甘草(Glycyrrhiza uralensis Fiseh)进行了粗提,将粗提物按0.5%和2%的质量分数制成药饵投喂鲫鱼(Carassius auratus)后,于第14天、28天、35天、42天5、6天采样检测其免疫指标。结果显示,低剂量组试验鱼血清溶菌酶活性逐渐升高,高剂量组在35d达到最大值(205.5±28.8)U/mL,之后略有下降。低剂量组和高剂量组试验鱼血清杀菌活性均有所波动,波动范围分别为62.0%—73.1%和75.0%—83.3%,就各期而言,对照组、低剂量组和高剂量组试验鱼的血清杀菌活性依次升高。另外,在淋巴细胞计数方面,高剂量组仅在第42天采样时显著高于对照组(p<0.05),在其他采样期,试验组与对照组均无统计学差异。此外,低剂量组试验鱼血液中白细胞吞噬活性有所增强(p<0.05),第42天达到最大值(66.5±9.4)%,高剂量组先升后降,在第35天达到峰值(74.7±5.6)%。最后,低剂量组试验鱼脾脏重量指数在第56天显著高于对照组(p<0.05),结果分别为(1.08±0.09)×10-3和(0.71±0.09)×10-3,高剂量组在第28天与对照组差异极显著(p<0.01),结果分别为(1.12±0.13)×10-3和(0.63±0.08)×10-3。实验表明,该甘草粗提物对鲫免疫功能有良好的调节作用,具有广阔的应用前景。     

RNA modifications by oxidation: A novel disease mechanism?

The past decade has provided exciting insights into a novel class of central (small) RNA molecules intimately involved in gene regulation. Only a small percentage of our DNA is translated into proteins by mRNA, yet 80% or more of the DNA is transcribed into RNA, and this RNA has been found to encompass various classes of novel regulatory RNAs, including, e.g., microRNAs. It is well known that DNA is constantly oxidized and repaired by complex genome maintenance mechanisms. Analogously, RNA also undergoes significant oxidation, and there are now convincing data suggesting that oxidation, and the consequent loss of integrity of RNA, is a mechanism for disease development. Oxidized RNA is found in a large variety of diseases, and interest has been especially devoted to degenerative brain diseases such as Alzheimer disease, in which up to 50-70% of specific mRNA molecules are reported oxidized, whereas other RNA molecules show virtually no oxidation. The iron-storage disease hemochromatosis exhibits the most prominent general increase in RNA oxidation ever observed. Oxidation of RNA primarily leads to strand breaks and to oxidative base modifications. Oxidized mRNA is recognized by the ribosomes, but the oxidation results in ribosomal stalling and dysfunction, followed by decreased levels of functional protein as well as the production of truncated proteins that do not undergo proper folding and may result in protein aggregation within the cell. Ribosomal dysfunction may also signal apoptosis by p53-independent pathways. There are very few reports on interventions that reduce RNA oxidation, one interesting observation being a reduction in RNA oxidation by ingestion of raw olive oil. High urinary excretion of 8-oxo-guanosine, a biomarker for RNA oxidation, is highly predictive of death in newly diagnosed type 2 diabetics; this demonstrates the clinical relevance of RNA oxidation. Taken collectively the available data suggest that RNA oxidation is a contributing factor in several diseases such as diabetes, hemochromatosis, heart failure, and β-cell destruction. The mechanism involves free iron and hydrogen peroxide from mitochondrial dysfunction that together lead to RNA oxidation that in turn gives rise to truncated proteins that may cause aggregation. Thus RNA oxidation may well be an important novel contributing mechanism for several diseases.     

N-Terminal pyroglutamate formation of Aβ38 and Aβ40 enforces oligomer formation and potency to disrupt hippocampal long-term potentiation

Pyroglutamate (pGlu)-modified amyloid peptides have been identified in sporadic and familial forms of Alzheimer's disease (AD) and the inherited disorders familial British and Danish Dementia (FBD and FDD). In this study, we characterized the aggregation of amyloid-β protein Aβ37, Aβ38, Aβ40, Aβ42 and ADan species in vitro, which were modified by N-terminal pGlu (pGlu-Aβ3-x, pGlu-ADan) or possess the intact N-terminus (Aβ1-x, ADan). The pGlu-modification confers rapid formation of oligomers and short fibrillar aggregates. In accordance with these observations, the pGlu-modified Aβ38, Αβ40 and Αβ42 species inhibit hippocampal long term potentiation of synaptic response, but pGlu-Aβ3-42 showing the highest effect. Among the unmodified Aβ peptides, only Aβ1-42 exhibites such propensity, which was similar to pGlu-Aβ3-38 and pGlu-Aβ3-40. Likewise, the amyloidogenic peptide pGlu-ADan impaired synaptic potentiation more pronounced than N-terminal unmodified ADan. The results were validated using conditioned media from cultivated HEK293 cells, which express APP variants favoring the formation of Aβ1-x, Aβ3-x or N-truncated pGlu-Aβ3-x species. Hence, we show that the ability of different amyloid peptides to impair synaptic function apparently correlates to their potential to form oligomers as a common mechanism. The pGlu-modification is apparently mediating a higher surface hydrophobicity, as shown by 1-anilinonaphtalene-8-sulfonate fluorescence, which enforces potential to interfere with neuronal physiology.     

Implications of body condition on the unsustainable predation rates of endangered mountain caribou

Both top-down and bottom-up processes influence herbivore populations, and identifying dominant limiting factors is essential for applying effective conservation actions. Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou) that have been declining, and unsustainable predation has been identified as the proximate cause. To investigate the role of poor nutrition, we examined the influence of sex, season, age class, and available suitable habitat (i.e., old-growth forest>140 years) per caribou on bone marrow fat content of caribou that died (n = 79). Sex was the only strong predictor of marrow fat. Males that died during and post rut had lower marrow fat than females or males at other times of year. Old-growth abundance per caribou, season, and age class did not predict marrow fat. Caribou killed by predators did not have less marrow fat than those that died in accidents, suggesting that nutritionally stressed caribou were not foraging in less secure habitats or that predators selected nutritionally stressed individuals. Marrow fat in endangered and declining populations of mountain caribou was similar to caribou in other, more viable populations. Our results support previous research suggesting that observed population declines of mountain caribou are due to excessive predation that is not linked to body condition.     

Fine mapping of QTLs for rice grain yield under drought reveals sub-QTLs conferring a response to variable drought severities

Fine-mapping studies on four QTLs, qDTY(2.1), qDTY(2.2), qDTY(9.1) and qDTY(12.1), for grain yield (GY) under drought were conducted using four different backcross-derived populations screened in 16 experiments from 2006 to 2010. Composite and bayesian interval mapping analyses resolved the originally identified qDTY(2.1) region of 42.3 cM into a segment of 1.6 cM, the qDTY(2.2) region of 31.0 cM into a segment of 6.7 cM, the qDTY(9.1) region of 32.1 cM into two segments of 9.4 and 2.4 cM and the qDTY(12.1) region of 10.6 cM into two segments of 3.1 and 0.4 cM. Two of the four QTLs (qDTY(9.1) and qDTY(12.1)) having effects under varying degrees of stress severity showed the presence of more than one region within the original QTL. The study found the presence of a donor allele at RM262 within qDTY(2.1) and RM24334 within qDTY(9.1) showing a negative effect on GY under drought, indicating the necessity of precise fine mapping of QTL regions before using them in marker-assisted selection (MAS). However, the presence of sub-QTLs together in close vicinity to each other provides a unique opportunity to breeders to introgress such regions together as a unit into high-yielding drought-susceptible varieties through MAS.