Association mapping reveals candidate loci for resistance and anaemic response to an emerging temperature‐driven parasitic disease in a wild salmonid fish

Even though parasitic infections are often costly or deadly for the host, we know very little which genes influence parasite susceptibility and disease severity. Proliferative kidney disease is an emerging and, at elevated water temperatures, potentially deadly disease of salmonid fishes that is caused by the myxozoan parasite Tetracapsuloides bryosalmonae. By screening >7.6 K SNPs in 255 wild brown trout (Salmo trutta) and combining association mapping and Random Forest approaches, we identified several candidate genes for both the parasite resistance (inverse of relative parasite load; RPL) and the severe anaemic response to the parasite. The strongest RPL‐associated SNP mapped to a noncoding region of the congeneric Atlantic salmon (S. salar) chromosome 10, whereas the second strongest RPL‐associated SNP mapped to an intronic region of PRICKLE2 gene, which is a part of the planar cell polarity signalling pathway involved in kidney development. The top SNP associated with anaemia mapped to the intron of the putative PRKAG2 gene. The human ortholog of this gene has been associated with haematocrit and other blood‐related traits, making it a prime candidate influencing parasite‐triggered anaemia in brown trout. Our findings demonstrate the power of association mapping to pinpoint genomic regions and potential causative genes underlying climate change‐driven parasitic disease resistance and severity. Furthermore, this work illustrates the first steps towards dissecting genotype–phenotype links in a wild fish population using closely related genome information.     

Normal response of Fanconi's anemia cells to high concentrations of O2 as determined by alkaline elution

In this investigation, normal and Fanconi's anemia fibroblasts were exposed to high concentrations of oxygen and the effects of this treatment on DNA were analyzed by alkaline elution. No DNA single-strand breaks were detected in either cell type with up to 20 h incubation in high (50–95%) concentrations of O₂. No evidence of DNA damage by O₂ could be detected with an endonuclease preparation from Micrococcus luteus. Cells which have been treated with various DNA-damaging agents in the presence of the polymerase inhibitor cytosine arabinoside have been shown to accumulate DNA single-strand breaks during DNA excision repair. When cells were treated with the polymerase inhibitor in 50 or 95% O₂, a low level of DNA single-strand breaks accumulated in both cell types. However, no significant differences in the frequency of DNA single-strand breaks were detected between normal and Fanconi's anemia cells after exposure to high O₂.     

Biochemical genetics of a new glucosephosphate isomerase allele (Gpi-1 c) from wild mice

We have found a new allele at the structural locus for glucosephosphate isomerase (called Gpi-1 ^c ) in a population of wild mice. The Gpi-1 ^c allele codes for an enzyme of greater cathodal electrophoretic mobility than either the Gpi-1 ^a or Gpi-1 ^b alleles found in the wild and in the SM/J and C57BL/6J inbred strains. Mice homozygous for Gpi-1 ^c have erythrocyte enzyme activity reduced to 33% of normal levels, altered pH profile, lowered heat stability, and normal K _m 's when compared with SM/J and C57BL/6J mice. The activity of the enzyme in brain, liver, and kidney is not so markedly lowered, although the electrophoretic mobility, pH profile, and heat stability are altered in these tissues. Deficiencies of erythrocyte glucosephosphate isomerase in man, to this level, can cause severe hemolytic anemia. Homozygotes for Gpi-1 ^c show only mild hematological symptoms. The frequency of Gpi-1 ^c in wild populations of mice is discussed and the occurrence of a further rare allele Gpi-1 ^d is reported.This work was supported by M.R.C. grants to Professor R. J. Berry and Dr. H. Kacser, whom we should also like to thank for much help and useful discussion.     

Mutations of the Fanconi Anemia Group A Gene (FAA) in Italian Patients

Fanconi anemia (FA) is an autosomal recessive disease characterized by progressive pancytopenia, congenital malformations, and predisposition to acute myeloid leukemia. At least five complementation groups (FA-A-FA-E) have been identified. The relative prevalence of FA-A has been estimated at an average of approximately 65% but may widely vary according to ethnic background. In Italy, 11 of 12 patients analyzed by cell-fusion studies were assigned to group FA-A, suggesting an unusually high relative prevalence of this FA subtype in patients of Italian ancestry. We have screened the 43 exons of the FAA gene and their flanking intronic sequences in 38 Italian FA patients, using RNA-SSCP. Ten different mutations were detected: three nonsense and one missense substitutions, four putative splice mutations, an insertion, and a duplication. Most of the mutations are expected to cause a premature termination of the FAA protein at various sites throughout the molecule. Four protein variants were also found, three of which were polymorphisms. The missense mutation D1359Y, not found in chromosomes from healthy unrelated individuals, was responsible for a local alteration of hydrophobicity in the FAA protein, and it was likely to be pathogenic. Thus, the mutations so far encountered in the FAA gene are essentially all different. Since screening based on the analysis of single exons by genomic DNA amplification apparently detects only a minority of the mutations, methods designed to detect alterations in the genomic structure of the gene or in the FAA polypeptide may be helpful in the identification of FAA mutations.     

环孢霉素A治疗儿童再生障碍性贫血的临床疗效研究

目的:探讨环孢霉素A治疗儿童再生障碍性贫血患者的临床疗效。方法:选择在我院就诊或住院治疗的50例儿童再生障碍性贫血患者,随机分为实验组和对照组,每组25例。对照组患者给予司坦唑醇治疗,实验组患者在对照组基础上给予环孢素治疗。治疗结束后,检测并比较两组患者的血清雌二醇、睾酮水平、网织红细胞计数以及临床疗效。结果:与治疗前相比,两组患者治疗后的血清雌二醇水平均显著下降(P0.05),血清睾酮水平以及网织红细胞计数水平均明显升高(P0.05);与对照组相比,实验组患者的血清雌二醇水平较低(P0.05),血清睾酮水平以及网织红细胞计数水平较高(P0.05)。此外,实验组的临床治疗总有效率较对照组明显升高(P0.05)。结论:环孢霉素A可提高儿童AA患者的疗效,可能与其降低血清雌二醇水平,升高血清睾酮水平以及网织红细胞计数水平有关。     

急性心肌梗死后发生医院获得性贫血的影响因素及预后

目的:研究急性心肌梗死(acute myocardial infarction,AMI)后发生医院获得性贫血(hospital acquired anemia,HAA)的影响因素及预后情况。方法:以1131例入院时血红蛋白质量浓度正常的AMI患者为回顾性研究对象,医院获得性贫血(HAA)定义为:AMI患者入院时无贫血,而在住院期间最低血红蛋白质量浓度达到贫血的诊断标准。根据最低血红蛋白值将HAA划分为轻度HAA组(110 g/LHb正常值下限)、中度HAA组(90 g/L≤Hb≤110 g/L)、重度HAA组(Hb90 g/L),并将其与无HAA组进行对比,采用卡方检验比较各组间的预后差异及相关因素。所有患者在出院后1、2、3年进行随访,四组患者的远期病死率、心衰再住院率采用用卡方检验及Kaplan-Meier法。结果:在符合入选标准的HAA患者中,轻度HAA 440例(77.6%),中度HAA 105例(18.5%),重度HAA 22例(3.8%)。AMI患者发生HAA的相关因素包括年龄、女性、心力衰竭、PCI治疗、Cr、超敏C反应蛋白、左室射血分数(EF)、β-受体阻滞剂、低分子肝素、螺内酯(p0.001)。随着HAA程度的加重,病死率明显升高,而其与心衰的发生无明显相关性。结论:年龄、女性、心力衰竭、PCI治疗、Cr、超敏C反应蛋白、左室射血分数(EF)、β-受体阻滞剂、低分子肝素、螺内酯可能是AMI后发生HAA的影响因素,随着HAA程度的加重,患者病死率明显升高,但HAA的发生与严重程度与出院后心衰的发生无明显相关性。     

血清Hepcidin 水平在老年缺铁性贫血和慢性病贫血诊断中的临床应用

目的:探讨血清铁调素(Hepcidin)在老年人群缺铁性贫血(IDA)和慢性病贫血(ACD)中的应用价值。方法:选择老年IDA患者32例,老年ACD患者34例,健康对照组28例。检测对比三组血清Hepcidin、血清铁(SI)、血清铁蛋白(SF)、C-反应蛋白(CRP)、红细胞数(RBC)、血红蛋白(Hb)、红细胞比容(HCT)、红细胞平均体积(MCV)、白细胞数(WBC)水平。结果:ACD组中WBC明显高于IDA组(P0.05)。血清Hepcidin在IDA组、ACD组及对照组之间具有显著性差异(P0.05),IDA组中Hepcidin含量比对照组低,而ACD组中Hepcidin含量比对照组高(P0.05)。IDA组、ACD组中SI明显低于对照组(P0.05),而两组间无显著性差异(P0.05)。ACD组中SF、CRP均明显高于IDA组与对照组(P0.05)。Hepcidin诊断IDA组的ROC曲线下面积(AUC)值大于诊断ACD组,IDA组的诊断指数高于ACD组。结论:血清Hepcidin含量的检测对于鉴别IDA和ACD具有重要的意义。     

Fanconi anemia proteins in telomere maintenance

Mammalian chromosome ends are protected by nucleoprotein structures called telomeres. Telomeres ensure genome stability by preventing chromosome termini from being recognized as DNA damage. Telomere length homeostasis is inevitable for telomere maintenance because critical shortening or over-lengthening of telomeres may lead to DNA damage response or delay in DNA replication, and hence genome instability. Due to their repetitive DNA sequence, unique architecture, bound shelterin proteins, and high propensity to form alternate/secondary DNA structures, telomeres are like common fragile sites and pose an inherent challenge to the progression of DNA replication, repair, and recombination apparatus. It is conceivable that longer the telomeres are, greater is the severity of such challenges. Recent studies have linked excessively long telomeres with increased tumorigenesis. Here we discuss telomere abnormalities in a rare recessive chromosomal instability disorder called Fanconi Anemia and the role of the Fanconi Anemia pathway in telomere biology. Reports suggest that Fanconi Anemia proteins play a role in maintaining long telomeres, including processing telomeric joint molecule intermediates. We speculate that ablation of the Fanconi Anemia pathway would lead to inadequate aberrant structural barrier resolution at excessively long telomeres, thereby causing replicative burden on the cell.     

Sickle red cells as danger signals on proinflammatory gene expression,leukotriene B4 and interleukin-1 beta production in peripheral blood mononuclear cell

This study tested the hypothesis that sickle red blood cell (SS-RBC) induce Toll-like receptors (TLR) and Nod-like receptor family, pyrin domain containing 3 (NLRP3)- inflammasome expression in peripheral blood mononuclear cells (PBMC). TLR and NLRP3 inflammasome could contribute to the maintenance of the inflammatory status in sickle cell anemia (SCA) patients, since SS-RBC act as danger signals activating these pathways. In this study, first, we evaluated TLR (2, 4, 5 and 9), NLRP3, Caspase-1, interleukin (IL)-1β and IL-18 expression in PBMC freshly isolated from SCA patients (SS-PBMC) in comparison with PBMC from healthy individuals (AA-PBMC). In the second moment, we investigated whether SS-RBC could interfere with the expression of these molecules in PBMC from healthy donor, in the absence or presence of hydroxyurea (HU) in vitro. TLRs and NLRP3 inflammasome expression were investigated by qPCR. IL-1β, Leukotriene-B4 (LTB₄) and nitrite production were measured in PBMC (from healthy donor) culture supernatants. TLR2, TLR4, TLR5, NLRP3 and IL-1β were highly expressed in SS-PBMC when compared to AA-PBMC. Additionally, SS-RBC induced TLR9, NLRP3, Caspase-1, IL-1β and IL-18 expression and induced IL-1β, LTB₄ and nitrite production in PBMC cultures. HU did not prevent TLR and NLRP3 inflammasome expression, but increased TLR2 and IL-18 expression and reduced nitrite production. In conclusion, our data suggest that TLR and inflammasome complexes may be key inducers of inflammation in SCA patients, probably through SS-RBC; also, HU does not prevent NLRP3 inflammasome- and TLR-dependent inflammation, indicating the need to develop new therapeutic strategies to SCA patients that act with different mechanisms of those observed for HU.