46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism

Familial recurrence risks are poorly understood in cases of de novo mutations. In the event of parental germ line mosaicism, recurrence risks can be higher than generally appreciated, with implications for genetic counseling and clinical practice. In the course of treating a female with pubertal delay and hypergonadotropic hypogonadism, we identified a new missense mutation in the SRY gene, leading to somatic feminization of this karyotypically normal XY individual. We tested a younger sister despite a normal onset of puberty, who also possessed an XY karyotype and the same SRY mutation. Imaging studies in the sister revealed an ovarian tumor, which was removed. DNA from the father's blood possessed the wild type SRY sequence, and paternity testing was consistent with the given family structure. A brother was 46, XY with a wild type SRY sequence strongly suggesting paternal Y-chromosome germline mosaicism for the mutation. In disorders of sexual development (DSDs), early diagnosis is critical for optimal psychological development of the affected patients. In this case, preventive karyotypic screening allowed early diagnosis of a gonadal tumor in the sibling prior to the age of normal puberty. Our results suggest that cytological or molecular diagnosis should be applied for siblings of an affected DSD individual.

Polymorphisms of MAMLD1 gene in hypospadias

PURPOSE

Mastermind-like domain containing 1 (MAMLD1) is a causative gene for the fetal development of male external genitalia. Almost 10% of patients with both severe and non-severe hypospadias exhibit mutations of MAMLD1. The aim of this work was to determine whether polymorphisms of MAMLD1 are a genetic risk factor for hypospadias.

MATERIAL AND METHODS

This study included 150 hypospadias with a range of severities and 150 controls. Direct sequencing of the MAMLD1 coding exons and their flanking splice sites was performed. In silico secondary and tertiary structure prediction and accessibility of changed amino acids were evaluated using JPred, Netsurf and PHYRE software. Functional studies of the transactivation of haplotypes on Hes3 promoter were performed in vitro using cDNAs of missense variants of MAMLD1.

RESULTS

The p.P286S polymorphism was identified in 17/150 patients and 12/150 controls (11.3% vs. 8.0%, p = 0.32). The p.N589S polymorphism was identified in 22/150 patients and 12/150 controls (14.6% vs. 8.0%, p = 0.068). The double polymorphism (S-S haplotype) was present in 16/150 patients and 6/150 controls (10.6% vs. 4.0%, p = 0.044, OR = 2.87, CI from 1.09 to 7.55). The association of polymorphisms consistently revealed a modification in the structure prediction or amino acid accessibility in all three in silico models. The P286S, N589S and P286S + N589S proteins did not exhibit reduced transactivating activity on Hes3 promoter.

CONCLUSION

Polymorphisms of MAMLD1 gene are frequent in patients with hypospadias. Although no change in transactivation was noted on Hes3 promoter, the in silico studies and the significantly increased incidence of the S-S haplotype in hypospadiac patients raise the hypothesis of a particular susceptibility conferred by these variants.

Hes1 functions downstream of growth factors to maintain oligodendrocyte lineage cells in the early progenitor stage

Expansion of the progenitor pool of oligodendrocytes (OLs) is a critical process for obtaining appropriate amounts of mature myelin-forming OLs in the developing and regenerating central nervous system. In vitro, fibroblast growth factor-2 (FGF2), together with platelet-derived growth factor (PDGF), is required to expand oligodendrocyte progenitor cells (OLPs) in an unlimited manner, maintaining them in the early progenitor stage. However, the intracellular mechanisms that prevent OLP maturation remain elusive. In order to investigate these mechanisms, we established a mouse OLP primary culture, which enabled us to undertake biochemical analyses. We found that the suppressive effects on maturation of early OLP to the late O4(+) progenitor by PDGF+FGF2 treatment was abrogated by Mek inhibitor, while transfecting cells with a constitutively active Mek1 construct prevented OLP maturation, suggesting that the Mek-Erk pathway is implicated in the effects of the growth factor treatment. The activation of Mek-Erk pathway promoted proliferation of OLP suggesting that cell cycle progression has suppressive effects to the maturation of OLP. Furthermore, molecular screening using DNA microarrays revealed that Hes1, a negative regulator of bHLH transcription factors, is one of the downstream molecules induced by PDGF+FGF2 treatment. We confirmed that forced activation of Mek-Erk pathway is sufficient to induce Hes1 expression and that Hes1, in turn, exerts suppressive effects on the maturation of OL lineage by itself. Our observations thus indicate that Mek-Erk pathway plays pivotal role in preventing early OLP maturation to late OLPs and the effect is mediated by cell cycle progression as well as Hes1 induction.

Parthenogenetic chimaerism/mosaicism with a Silver-Russell syndrome-like phenotype

Introduction

We report a 34-year-old Japanese female with a Silver-Russell syndrome (SRS)-like phenotype and a mosaic Turner syndrome karyotype (45,X/46,XX).

Methods/Results

Molecular studies including methylation analysis of 17 differentially methylated regions (DMRs) on the autosomes and the XIST-DMR on the X chromosome and genome-wide microsatellite analysis for 96 autosomal loci and 30 X chromosomal loci revealed that the 46,XX cell lineage was accompanied by maternal uniparental isodisomy for all chromosomes (upid(AC)mat), whereas the 45,X cell lineage was associated with biparentally derived autosomes and a maternally derived X chromosome. The frequency of the 46,XX upid(AC)mat cells was calculated as 84% in leukocytes, 56% in salivary cells, and 18% in buccal epithelial cells.

Discussion

The results imply that a parthenogenetic activation took place around the time of fertilisation of a sperm missing a sex chromosome, resulting in the generation of the upid(AC)mat 46,XX cell lineage by endoreplication of one blastomere containing a female pronucleus and the 45,X cell lineage by union of male and female pronuclei. It is likely that the extent of overall (epi)genetic aberrations exceeded the threshold level for the development of SRS phenotype, but not for the occurrence of other imprinting disorders or recessive Mendelian disorders.

HENLE'S REACTION OF THE CHROMAFFIN CELLS IN THE ADRENALS, AND THE MICROSCOPIC TEST FOR ADRENALIN

We have established the fact that the chrome reaction as well as the silver and osmium reactions are merely reductions by adrenalin. In our opinion the naming of the cells giving a positive reaction should not be based upon the reaction i.e., chromaffin cells), but on the presence of adrenalin itself. Biedl's terms, adrenal cell, adrenal organ, adrenal body, adrenal system, and also Bonnamour's term, adrenalin-producing cells, are appropriate in this respect. We propose the names adrenalin cell, adrenalin tissue, adrenalin system, thereby indicating the presence of adrenalin.

Prostaglandin E1 analog increases spinal cord blood flow at the point of compression during and after experimental spinal cord injury

STUDY DESIGN

An in vivo study using a spinal cord compression model in rats.

OBJECTIVES

To evaluate the effect of prostaglandin E1 (PGE1) on the change in thoracic spinal cord blood flow and on hind-limb motor function.

BACKGROUND

Until now, effect of PGE1 on spinal cord blood flow at the point of compression has not been tested.

METHODS

Our newly developed blood flow measurement system was a combination of a noncontact-type Laser Doppler system and a spinal cord compression device. The rat thoracic spinal cord was exposed and spinal cord blood flow at the point of compression was measured before, during and after compression. The functioning of the animals' hind-limbs was evaluated by the BBB Scale and by measuring the frequency of voluntary standing.

RESULTS

During the compression period, spinal cord blood flow was significantly higher in the PGE1-treated rats than in the control rats, which did not receive PGE1. After decompression, the spinal cord blood flow rapidly recovered to about 60% of the precompression level in the control rats. When the animals were treated with PGE1, blood flow after decompression reached about 90% of the precompression level.Twenty-gram compression for 40 mins induced motor deficiencies in the rat hind-limbs. The application of PGE1 significantly improved motor function of the rat hind-limbs after spinal cord injury.

CONCLUSIONS

The application of PGE1 increased spinal cord blood flow during and after spinal cord compression, and improved motor function after the spinal cord injury.

CHD7 mutations in patients initially diagnosed with Kallmann syndrome--the clinical overlap with CHARGE syndrome

Kallmann syndrome (KS) is the combination of hypogonadotropic hypogonadism and anosmia or hyposmia, two features that are also frequently present in CHARGE syndrome. CHARGE syndrome is caused by mutations in the CHD7 gene. We performed analysis of CHD7 in 36 patients with KS and 20 patients with normosmic idiopathic hypogonadotropic hypogonadism (nIHH) in whom mutations in KAL1, FGFR1, PROK2 and PROKR2 genes were excluded. Three of 56 KS/nIHH patients had de novo mutations in CHD7. In retrospect, these three CHD7-positive patients showed additional features that are seen in CHARGE syndrome. CHD7 mutations can be present in KS patients who have additional features that are part of the CHARGE syndrome phenotype. We did not find mutations in patients with isolated KS. These findings imply that patients diagnosed with hypogonadotropic hypogonadism and anosmia should be screened for clinical features consistent with CHARGE syndrome. If such features are present, particularly deafness, dysmorphic ears and/or hypoplasia or aplasia of the semicircular canals, CHD7 sequencing is recommended.

MAMLD1 (CXorf6): a new gene for hypospadias

MAMLD1 (mastermind-like domain containing 1), also known as CXorf6 (chromosome X open reading frame 6) has been shown to be a causative gene for hypospadias. This is primarily based on the identification of nonsense mutations (E124X, Q197X, and R653X) which undergo nonsense mediated mRNA decay in patients with penoscrotal hypospadias. Subsequent molecular studies have shown that (1) the mouse homolog is transiently expressed in fetal Sertoli and Leydig cells around the critical period for sex development; (2) CXorf6 protein shares homology to mastermind-like 2 (MAML2) protein that functions as a co-activator in canonical Notch signaling; (3) CXorf6 localizes to the nuclear bodies and transactivates the promoter activity of a non-canonical Notch target gene hairy/enhancer of split 3(Hes3) without demonstrable DNA binding capacity; (4) transient knockdown of CXorf6 results in significantly reduced testosterone production in murine Leydig tumor cells; and (5) CXorf6 can be regulated by steroidogenic factor 1 (SF-1). These findings suggest that the CXorf6 mutations cause hypospadias primarily because of testicular dysfunction and resultant compromised testosterone production around that period, and provide useful information for the molecular network involved in fetal testosterone production.

Egr-1 mRNA induction by medium flow involves mRNA stabilization and is enhanced by the p38 inhibitor SB203580 in osteoblast-like cells

AIM

Mechanical stimuli are important for maintaining organ structure and tissue function. To elucidate signalling pathways activated by mechanical stimuli, the contribution of mRNA stabilization to induction of egr-1 mRNA by medium flow was examined and the mechanisms responsible for stabilization were analysed. An early-response gene that encodes a transcription factor, egr-1, activates transcription of several genes in response to mechanical stimuli, and was therefore selected to resolve how early-induced signals are integrated and connected to subsequent response.

METHODS

Mouse osteoblast-like MC3T3E1 cells were stably transfected with the chloramphenicol acetyltransferase (CAT) gene linked to the egr-1 promoter, and inductions of endogenous egr-1 and transfected CAT mRNA following medium flow were compared using real-time reverse transcriptase PCR. The mechanism of induction was examined using a transcription inhibitor and mitogen-activated protein (MAP) kinase inhibitors. Activation of MAP kinases by medium flow was investigated using western blotting.

RESULTS

Induction of egr-1 mRNA by medium flow was twofold higher than CAT mRNA induction. Induction of egr-1 mRNA was also observed in cells pre-treated with transcription inhibitor. The p38 inhibitor SB203580 enhanced induction of egr-1 mRNA by medium flow. Extracellular signal regulated kinase (ERK), p38 and c-Jun N-terminal kinase (JNK) were activated by medium flow.

CONCLUSION

A considerable part of egr-1 mRNA induction by medium flow may be due to mRNA stabilization. The p38 inhibitor SB203580 enhances induction.

Effects of Milk Casein-derived Peptides on Absolute Oxyhaemoglobin Concentrations in the Prefrontal Area and on Work Efficiency after Mental Stress Loading in Male Students

This study examined the influence of milk casein-derived peptides on cerebral activity after mental stress loading. In a crossover study, 16 male students were given a drink containing peptides (peptide group), or water (control group) before stress loading. The oxyhaemoglobin (HbO2) concentration in the prefrontal area of the brain and work efficiency were measured as indicators of cerebral activity and differences in these parameters were examined according to type A or type B personality. Type A behaviour was defined as: aggression–hostility, hard-driving—time-urgency and speed–power, whereas type B behaviour did not have these characteristics. Peptide intake resulted in a significant increase in both HbO2 concentration and work efficiency, whilst a similar increase was not seen in the control group. When divided into type A or type B personality, the changes in HbO2 concentration for the control group differed significantly in the right prefrontal area. Moreover, in type A subjects the HbO2 concentration in the right prefrontal area following intake was significantly different between the peptide and control groups.

Chromosomal location of Lg-FLO1 in bottom-fermenting yeast and the FLO5 locus of industrial yeast

AIMS

To determine the chromosomal location and entire sequence of Lg-FLO1, the expression of which causes the flocculation of bottom-fermenting yeast.

METHODS AND RESULTS

Two cosmid clones carrying DNA from a bottom-fermenting yeast chromosome VIII right-arm end were selected by colony hybridization. Sequencing revealed that the clones contained DNA derived from a Saccharomyces cerevisiae type chromosome VIII and a Saccharomyces bayanus type chromosome VIII, both from bottom-fermenting yeast.

CONCLUSIONS

Lg-FLO1 is located on the S. cerevisiae type chromosome VIII at the same position as the FLO5 gene of the laboratory yeast S. cerevisiae S288c. The unique chromosome VIII structure of bottom-fermenting yeast is conserved among other related strains. FLO5 and Lg-FLO1 promoter sequences are identical except for the presence of three 42 bp repeats in the latter, which are associated with gene activity. Flocculin genes might have been generated by chromosomal recombination at these repeats.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of the exact chromosomal location and entire sequence of Lg-FLO1. This information will be useful in the brewing industry for the identification of normal bottom-fermenting yeast. Moreover, variations in the FLO5 locus among strains are thought to reflect yeast evolution.