MJD基因CAG不稳定性扩增与临床研究

为了解Ｍａｃｈａｄｏ－ Ｊｏｓｅｐｈ 病（ＭＪＤ）基因突变及临床的神经电生理特点, 对１６ 个诊断为遗传性小脑性共济失调（ＳＣＡ）家系的４５ 例病人及３０ 例家系的“正常”人作ＭＪＤ 基因突变分析,检出ＭＪＤ 基因的病人行肢体运动及感觉神经传导速度（ＭＣＶ 及ＳＣＶ）、脑干诱发电位（ＢＡＥＰ）,视觉诱发电位（ＶＥＰ）的检查。结果检出１０ 个家系２５ 例病人及１ 例症状前１８ 岁女孩有ＭＪＤ基因突变,ＣＡＧ 三核苷酸重复７３～７９ 次,异常等位基因片段长３８０～４０２ｂｐ,均为杂合子; 正常人ＣＡＧ 三核苷酸重复１８～４０ 次,等位片段长２００～２７０ｂｐ,电生理发现ＭＪＤ 的ＳＣＶ 减慢比ＭＣＶ 明显,而下肢的ＭＣＶ、ＳＣＶ 又较上肢明显,ＢＡＥＰ、ＶＥＰ均有不同程度的潜伏期延长或波的异常;ＭＪＤ 的父亲遗传早于母亲,进展也较块,临床以小脑性共济失调为突出症状,其次为构音障碍、突眼等,肌肉萎缩仅见于晚期病人;ＭＲＩ示小脑萎缩较明显,脑干萎缩并不严重,未见明显的颈髓萎缩。     

MJD基因CAG不稳定性扩增与临床研究

为了解Machado-Joseph病(MJD)基因突变及临床的神经电生理特点, 对16个诊断为遗传性小脑性共济失调(SCA)家系的45例病人及30例家系的“正常”人作MJD基因突变分析,检出MJD基因的病人行肢体运动及感觉神经传导速度(MCV及SCV)、脑干诱发电位(BAEP),视觉诱发电位(VEP)的检查。结果检出10个家系25例病人及1例症状前18岁女孩有MJD基因突变,CAG三核苷酸重复73～79次,异常等位基因片段长380～402bp,均为杂合子; 正常人CAG三核苷酸重复18～40次,等位片段长200～270bp,电生理发现MJD的SCV减慢比MCV明显,而下肢的MCV、SCV又较上肢明显,BAEP、VEP均有不同程度的潜伏期延长或波的异常;MJD的父亲遗传早于母亲,进展也较块,临床以小脑性共济失调为突出症状,其次为构音障碍、突眼等,肌肉萎缩仅见于晚期病人;MRI示小脑萎缩较明显,脑干萎缩并不严重,未见明显的颈髓萎缩。 Abstract:　To investigate the gene mutation of clinical and neuroelectrophysiological characteristics in Machado-Joseph disease(MJD). The gene mutation was detected in 45 patients diagnosed as spinocerebellar ataxia(SCA) and 30 “healthy relatives”. Brain stem evoked potentials(BAEP), visual evoked potentials(VEP) and motor conduction velocity (MCV) and sensory conduction velocity (SCV) were performed on MJD. Gene mutations were detected in 25 patients and a 18-year-old girl among 16 families. Trinucleotide repeats of CAG were 73～79. The fragments of abnormal alleles were 380～402bp, and all patients were heterozygous. The copy numbers of normal alleles were 18～40, fragments from 202～270bp. SCV reduction was much obvious compared to MCV, MCV and SCV in lower limb ?ere much more slow than that in upper's. BAEP, VEP were also delayed in latency. The anticipation in parental sex bias were much more obvioius than that in matental's. Cerebellar ataxia was most severe, the next were dysarthria and bulging eyes. Amytrophy was seen only in bed ridden patients. Cerebellar atrophy was more severe than brain stem, cord atrophy was n't observed in all MJD.     

Mathematical Talent is Linked to Autism

A total of 378 mathematics undergraduates (selected for being strong at “systemizing”) and 414 students in other (control) disciplines at Cambridge University were surveyed with two questions: (1) Do you have a diagnosed autism spectrum condition? (2) How many relatives in your immediate family have a diagnosed autism spectrum condition? Results showed seven cases of autism in the math group (or 1.85%) vs one case of autism in the control group (or 0.24%), a ninefold difference that is significant. Controlling for sex and general population sampling, this represents a three- to sevenfold increase for autism spectrum conditions among the mathematicians. There were 7 of 1,405 (or 0.5%) cases of autism in the immediate families of the math group vs 2 of 1,669 (or 0.1%) cases in the immediate families of the control group, which again is a significant difference. These results confirm a link between autism and systemizing, and they suggest this link is genetic given the association between autism and first-degree relatives of mathematicians.     

Serum melatonin levels and insomnia in patients with Machado-Joseph Disease

We previously reported a patient with Machado-Joseph Disease (MJD) who had severe insomnia and a low serum melatonin (MLT) level, and whose insomnia was alleviated by oral MLT replacement therapy. The aims of this study were to examine whether patients with MJD are likely to have insomnia, and whether there is a relationship between the degree of insomnia and the serum MLT level among patients with MJD. This study included 8 patients with MJD. A 58-year-old-patient with cervical spondylosis was also included in this study to check the condition of the test room for sleeping. All patients filled out the Japanese version of Pittsburgh Sleep Quality Index (PSQI-J) questionnaire. We obtained blood samples at 12:00 and 24:00 hours to measure the MLT level. We checked the sleep condition of the patient once an hour and recorded the grade in sleep-logs: the grades of sleep condition were asleep, sleepy, or awake. Statistical analyses were performed to search for correlations between the PSQI score and the serum MLT level or actual sleep time using Spearman’s rank correlation coefficient. Seven of the 8 MJD patients had a total PSQI score of above 5.5 (cut-off level). The daytime MLT level (at 12:00 hours) was below 2.8 pg/mL in all 8 patients, whereas the mean night-time MLT level (at 24:00 hours) of the MJD patients (23.6 ± 17.5 pg/mL) was lower than that of the control patient (43.0 pg/mL) and also lower than the reported cut-off level among healthy people aged 30–50 years (55.5 pg/mL). There was a negative correlation between the total PSQI score and the serum MLT level among the MJD patients (P < 0.05). Our results show that a low serum MLT level may contribute to insomnia in patients with MJD.

     

Correlation between CAG Repeat Length and Clinical Features in Machado-Joseph Disease

Machado-Joseph disease (MJD) is associated with the expansion of a CAG trinucleotide repeat in a novel gene on 14q32.1. We confirmed the presence of this expansion in 156 MJD patients from 33 families of different geographic origins: 15 Portuguese Azorean, 2 Brazilian, and 16 North American of Portuguese Azorean descent. Normal chromosomes contain between 12 and 37 CAG repeats in the MJD gene, whereas MJD gene carriers have alleles within the expanded range of 62–84 CAG units. The distribution of expanded alleles and the gap between normal and expanded allele sizes is either inconsistent with a premutation hypothesis or most (if not all) of the alleles we studied descend from a common ancestor. There is a strong correlation between the expanded repeat size and the age at onset of the disease as well as the clinical presentation. There is mild instability of the CAG tract length with transmission of the expanded alleles; both increase and decrease in size between parents and progeny occur, with larger variations in male than in female transmissions. Together, these effects can partly explain the variability of age at onset and of phenotypic features in MJD; however, other modifying factors must exist.     

白菜紫色性状RAPD连锁标记的筛选与染色体定位研究

以紫菜薹自交系95T2-5、大白菜自交系94S17-1及其F1、F2、BC1植株为材料,进行RAPD分析,从640个随机引物中筛选出2个引物S79和S123,分别能扩增出与紫色性状连锁的条带S79-934和S123-750。连锁分析发现,标记S79-934和S123-750与紫色基因间的遗传距离分别为13.73cM和18.65cM,并且位于紫色基因的两边。回收S79-934特异带,克隆转化并测序,比较分析表明其与大白菜1号染色体上已知克隆KBrH077A05的全序列(113253bp)有99%的相似性,初步推断控制紫色性状的主基因位于大白菜1号染色体上。     

N-Cadherin Gene Maps to Human Chromosome 18 and Is Not Linked to the E-Cadherin Gene

cDNA clones encoding the human N-cadherin cell adhesion molecule have been isolated from an embryonic muscle library by screening with an oligonucleotide probe complementary to the chick brain sequence and chick brain cDNA probe lambda N2. Comparison of the predicted protein sequences revealed greater than 91% homology between chick brain, mouse brain, and human muscle N-cadherin cDNAs over the 748 amino acids of the mature, processed protein. A single polyadenylation site in the chick clone was also present and duplicated in the human muscle sequence. Immediately 3' of the recognition site in chick a poly(A) tail ensued; however, in human an additional 800 bp of 3' untranslated sequence followed. Northern analysis identified a number of major N-cadherin mRNAs. These were of 5.2, 4.3, and 4.0 kb in C6 glioma, 4.3 and 4.0 kb in human foetal muscle cultures, and 4.3 kb in human embryonic brain and mouse brain with minor bands of 5.2 kb in human muscle and embryonic brain. Southern analysis of a panel of somatic cell hybrids allowed the human N-cadherin gene to be mapped to chromosome 18. This is distinct from the E-cadherin locus on chromosome 16. Therefore, it is likely that the cadherins have evolved from a common precursor gene that has undergone duplication and migration to other chromosomal locations.     

Screening of RAPD Markers Linked to the Photoperiod-Sensitivity Gene in Rice Chromosome 6 Using Bulked Segregant Analysis

Bulked segregant analysis was used to determine randomly amplifiedpolymorphic DNA (RAPD) markers in a specific interval in themiddle of chromosome 6 of rice for tagging the photoperiod sensitivitygene.Two pools of F₂ individuals (japonica cv. Nipponbare and indicacv. Kasalath) were constructed according to the genotypes ofthree restriction fragment length polymorphism (RFLP) markerslocated at both ends and the middle of the targeted interval.Then another pair of pools were constructed based on the "graphicalgenotype," which was made with our high density linkage map.RAPD analysis was performed using these DNA pools as templates,and polymorphic fragments were detected and mapped. Using 80primers, either singlyor pairwise, we tested 2,404 primer pairsand established 14 markers tightly linked to the photoperiodsensitivitygene. The obtained RAPD markers were converted intosequence-tagged sites bycloning and sequencing of the polymorphicfragments and they can be used directlyfor construction of physicalmaps. This bulked segregant method can be applied for any speciesand any region of interest in which detailed linkage maps orphysical maps are needed.     

Targeted Resequencing of the Pericentromere of Chromosome 2 Linked to Constitutional Delay of Growth and Puberty

Constitutional delay of growth and puberty (CDGP) is the most common cause of pubertal delay. CDGP is defined as the proportion of the normal population who experience pubertal onset at least 2 SD later than the population mean, representing 2.3% of all adolescents. While adolescents with CDGP spontaneously enter puberty, they are at risk for short stature, decreased bone mineral density, and psychosocial problems. Genetic factors contribute heavily to the timing of puberty, but the vast majority of CDGP cases remain biologically unexplained, and there is no definitive test to distinguish CDGP from pathological absence of puberty during adolescence. Recently, we published a study identifying significant linkage between a locus at the pericentromeric region of chromosome 2 (chr 2) and CDGP in Finnish families. To investigate this region for causal variation, we sequenced chr 2 between the genomic coordinates of 79–124 Mb (genome build GRCh37) in the proband and affected parent of the 13 families contributing most to this linkage signal. One gene, DNAH6, harbored 6 protein-altering low-frequency variants (< 6% in the Finnish population) in 10 of the CDGP probands. We sequenced an additional 135 unrelated Finnish CDGP subjects and utilized the unique Sequencing Initiative Suomi (SISu) population reference exome set to show that while 5 of these variants were present in the CDGP set, they were also present in the Finnish population at similar frequencies. Additional variants in the targeted region could not be prioritized for follow-up, possibly due to gaps in sequencing coverage or lack of functional knowledge of non-genic genomic regions. Thus, despite having a well-characterized sample collection from a genetically homogeneous population with a large population-based reference sequence dataset, we were unable to pinpoint variation in the linked region predisposing delayed puberty. This study highlights the difficulties of detecting genetic variants under linkage regions for complex traits and suggests that advancements in annotation of gene function and regulatory regions of the genome will be critical for solving the genetic background of complex phenotypes like CDGP.     

Chromosome studies in 14 patients with disseminated sclerosis

Summary Short term lymphocyte cultures were performed in 14 patients with disseminated sclerosis. The karyotype of all patients was normal, but the frequency of structural chromosome aberrations was increased as compared to 10 healthy controls of same age. There were chromatid type aberrations including gaps and breaks of one or both chromatids and chromosome type aberrations such as acentric fragments dicentis, rings and other abnormal chromosomes. These results confirm the findings of Khondkarian et al. (1967).

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Zusammenfassung Bei 14 Patienten mit multipler Sklerose wurden kurzfristige Lymphocytenkulturen durchgeführt. Alle Patienten hatten ein normales Karyogramm, Strukturanomalien waren jedoch häufiger als bei den 10 gesunden Kontrollpersonen gleichen Alters. Sie bestanden aus Gaps und Brüchen eines oder beider Chromatiden, azentrischen Fragmenten, dizentrischen Chromosomen, Ringen und anderen anormalen Chromosomen. Diese Ergebnisse bestätigen die Befunde von Khondkarian et al. (1967).

     

Understanding of Aquifer Microbiology is Tightly Linked to Sampling Approaches

Primary samples of groundwater or core are collected and analyzed to characterize the microbiology of aquifers and to predict biogeochemical transformations. Alternative sampling devices have been developed that are incubated for some length of time in the aquifer to accrue biomass for analysis. Considering data generated from different types of aquifer samples, it appears that the type of sample collected and analyzed may strongly influence the resulting view of aquifer microbiology. Borehole artifacts need to be rigorously considered when incubated substrata are used. The indigenous attached populations in deeper, fractured rock aquifers remain understudied and await new sampling approaches.     

Limited Effect of Chronic Valproic Acid Treatment in a Mouse Model of Machado-Joseph Disease

Machado-Joseph disease (MJD) is an inherited neurodegenerative disease, caused by a CAG repeat expansion within the coding region of ATXN3 gene, and which currently lacks effective treatment. In this work we tested the therapeutic efficacy of chronic treatment with valproic acid (VPA) (200mg/kg), a compound with known neuroprotection activity, and previously shown to be effective in cell, fly and nematode models of MJD. We show that chronic VPA treatment in the CMVMJD135 mouse model had limited effects in the motor deficits of these mice, seen mostly at late stages in the motor swimming, beam walk, rotarod and spontaneous locomotor activity tests, and did not modify the ATXN3 inclusion load and astrogliosis in affected brain regions. However, VPA chronic treatment was able to increase GRP78 protein levels at 30 weeks of age, one of its known neuroprotective effects, confirming target engagement. In spite of limited results, the use of another dosage of VPA or of VPA in a combined therapy with molecules targeting other pathways, cannot be excluded as potential strategies for MJD therapeutics.     

Familial Chordoma, a Tumor of Notochordal Remnants, Is Linked to Chromosome 7q33

Chordoma is a rare tumor originating from notochordal remnants that is usually diagnosed during midlife. We performed a genomewide analysis for linkage in a family with 10 individuals affected by chordoma. The maximum two-point LOD score based on only the affected individuals was 2.21, at recombination fraction 0, at marker D7S2195 on chromosome 7q. Combined analysis of additional members of this family (11 affected individuals) and of two unrelated families (one with 2 affected individuals and the other with 3 affected individuals), with 20 markers on 7q, showed a maximum two-point LOD score of 4.05 at marker D7S500. Multipoint analysis based on only the affected individuals gave a maximum LOD score of 4.78, with an approximate 2-LOD support interval from marker D7S512 to marker D7S684. Haplotype analysis of the three families showed a minimal disease-gene region from D7S512 to D7S684, a distance of 11.1 cM and approximately 7.1 Mb. No loss of heterozygosity was found at markers D7S1804, D7S1824, and D7S2195 in four tumor samples from affected family members. These results map a locus for familial chordoma to 7q33. Further analysis of this region, to identify this gene, is ongoing.     

国产十四种苋属植物的染色体数目

报道了国产14种苋属植物的染色体数目。部分种的染色体数目为2n=34,即反枝苋Amaranthus retroflexus,刺苋A．spinosus,红苋A．cruentus,腋花苋A．roxburghianus,合被苋A．polygonoides,皱果苋A． viridis,凹头苋A．lividus,苋A．tricolor。其他种的染色体数目为2n=32,即尾穗苋A．caudatus,绿穗苋A． hybridus,千穗谷A．hypochendriacus,繁穗苋A．paniculatus,北美苋A．blitoides,白苋A．albus。其中腋花 苋的染色体数目为首次报道。该属染色体基数为x=16,17。两种染色体基数在苋属2个组(sect．Ama- ranthus和sect．Blitopsis)中均存在。由于苋属植物染色体大多为小型染色体,因此对苋属植物目前尚不 能进行详尽的核型分析。