CRISPRi screens reveal a DNA methylation-mediated 3D genome dependent causal mechanism in prostate cancer

Prostate cancer (PCa) risk-associated SNPs are enriched in noncoding cis-regulatory elements (rCREs), yet their modi operandi and clinical impact remain elusive. Here, we perform CRISPRi screens of 260 rCREs in PCa cell lines. We find that rCREs harboring high risk SNPs are more essential for cell proliferation and H3K27ac occupancy is a strong indicator of essentiality. We also show that cell-line-specific essential rCREs are enriched in the 8q24.21 region, with the rs11986220-containing rCRE regulating MYC and PVT1 expression, cell proliferation and tumorigenesis in a cell-line-specific manner, depending on DNA methylation-orchestrated occupancy of a CTCF binding site in between this rCRE and the MYC promoter. We demonstrate that CTCF deposition at this site as measured by DNA methylation level is highly variable in prostate specimens, and observe the MYC eQTL in the 8q24.21 locus in individuals with low CTCF binding. Together our findings highlight a causal mechanism synergistically driven by a risk SNP and DNA methylation-mediated 3D genome architecture, advocating for the integration of genetics and epigenetics in assessing risks conferred by genetic predispositions.

Exome Sequencing Reveals a Phenotype Modifying Variant in ZNF528 in Primary Osteoporosis With a COL1A2 Deletion

We studied a family with severe primary osteoporosis carrying a heterozygous p.Arg8Phefs*14 deletion in COL1A2, leading to haploinsufficiency. Three affected individuals carried the mutation and presented nearly identical spinal fractures but lacked other typical features of either osteogenesis imperfecta or Ehlers-Danlos syndrome. Although mutations leading to haploinsufficiency in COL1A2 are rare, mutations in COL1A1 that lead to less protein typically result in a milder phenotype. We hypothesized that other genetic factors may contribute to the severe phenotype in this family. We performed whole-exome sequencing in five family members and identified in all three affected individuals a rare nonsense variant (c.1282C > T/p.Arg428*, rs150257846) in ZNF528. We studied the effect of the variant using qPCR and Western blot and its subcellular localization with immunofluorescence. Our results indicate production of a truncated ZNF528 protein that locates in the cell nucleus as per the wild-type protein. ChIP and RNA sequencing analyses on ZNF528 and ZNF528-c.1282C > T indicated that ZNF528 binding sites are linked to pathways and genes regulating bone morphology. Compared with the wild type, ZNF528-c.1282C > T showed a global shift in genomic binding profile and pathway enrichment, possibly contributing to the pathophysiology of primary osteoporosis. We identified five putative target genes for ZNF528 and showed that the expression of these genes is altered in patient cells. In conclusion, the variant leads to expression of truncated ZNF528 and a global change of its genomic occupancy, which in turn may lead to altered expression of target genes. ZNF528 is a novel candidate gene for bone disorders and may function as a transcriptional regulator in pathways affecting bone morphology and contribute to the phenotype of primary osteoporosis in this family together with the COL1A2 deletion. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

[Epidemiological characteristics of HIV infected pregnant women and exposed infants in Guangdong province, 2014-2017]

Objective: To analyze the epidemiological characteristics of HIV-infected pregnant women and exposed infant in Guangdong province and identify the factors associated with infant HIV infection through mother-to-child transmission. Methods: National Information System for Prevention of mother-to-child HIV Transmission and Early Infant Diagnosis Information Management Platform were used to collect the individual information about HIV-infected pregnant women and exposed infants who were delivered in Guangdong from January 1, 2014 to December 31 in 2017. The differences in pregnant women's demographic data, history of pregnancy and childbirth, the utilization of mother-to-child transmission prevention services and early infant diagnosis between the infected HIV exposed infants and uninfected HIV exposed infants were compared, and univariate and multivariate logistic regression analyses were conducted to identify the factors associated with mother-to-child HIV transmission. Results: Among 349 HIV infected pregnant women, the proportions of the pregnant women whose HIV infection status were confirmed before pregnancy, during pregnancy and at or after childbirth were 30.4% (106/349), 49.6% (173/349) and 20.0% (70/349) respectively. The proportions of those with sexual partners whose HIV infection status were unknown and those receiving no antiviral treatment were 39.5% (138/349) and 13.2% (46/349) respectively. Among the HIV exposed infants, the mother-to-child transmission rate was 4.2%(15/353), the HIV exposed infants had the first or second early diagnosis tests within 44 (P(25)-P(75): 42-50) days and 96 (P(25)-P(75): 92-106) days after birth, respectively. Univariate logistic regression analysis indicated that the risk for mother-to-child HIV transmission increased in those whose HIV infection status were confirmed at or after childbirth compared with before pregnancy (OR=5.72, 95%CI: 1.52-21.61) and in the group that antiviral treatment was given to either mothers or infants compared with the group that antiviral treatment was given to both mothers and infants (OR=33.56, 95%CI: 9.04-124.55), while there was lower mother-to-child HIV transmission risk in artificial feeding group compared with breast feeding group (OR=0.07, 95%CI: 0.01-0.76). Conclusion: The risk of mother-to-child HIV transmission in Guangdong can be effectively reduced by the measures of early diagnosis, antiviral treatment and artificial feeding as well as the improvement of mother-to-child transmission prevention service.

Enhancer Dysfunction in 3D Genome and Disease

Spatiotemporal patterns of gene expression depend on enhancer elements and other factors during individual development and disease progression. The rapid progress of high-throughput techniques has led to well-defined enhancer chromatin properties. Various genome-wide methods have revealed a large number of enhancers and the discovery of three-dimensional (3D) genome architecture showing the distant interacting mechanisms of enhancers that loop to target gene promoters. Whole genome sequencing projects directed at cancer have led to the discovery of substantial enhancer dysfunction in misregulating gene expression and in tumor initiation and progression. Results from genome-wide association studies (GWAS) combined with functional genomics analyses have elucidated the functional impacts of many cancer risk-associated variants that are enriched within the enhancer regions of chromatin. Risk variants dysregulate the expression of enhancer variant-associated genes via 3D genomic interactions. Moreover, these enhancer variants often alter the chromatin binding affinity for cancer-relevant transcription factors, which in turn leads to aberrant expression of the genes associated with cancer susceptibility. In this review, we investigate the extent to which these genetic regulatory circuits affect cancer predisposition and how the recent development of genome-editing methods have enabled the determination of the impacts of genomic variation and alteration on cancer phenotype, which will eventually lead to better management plans and treatment responses to human cancer in the clinic.

[Current status of reproductive health and its occupational influencing factors among female medical staff in a provincial maternal and child health hospital]

Objective: To investigate the current status of reproductive health among the female medical staff in a provincial maternal and child health hospital and analyze the occupational influencing factors for reproductive health, particularly the effects of high-intensity work, work shift, chemical poisons, and physical and biological factors on reproductive health, and to provide a scientific basis for developing related intervention measures and promoting the reproductive health of professional females. Methods: A reproductive health questionnaire was designed in terms of age, type of work, professional title, education level, working hours, working strength, and the reproductive health of female staff to analyze the current status of reproductive health, working strength, and occupational hazardous factors. The female medical staff in the provincial maternal and child health hospital completed the questionnaire on the internal network of the hospital voluntarily. Results: Of all respondents, 19.46% had a history of miscarriage, 5.90% visited the hospital due to infertility, 21.31% had irregular menstruation within the last 3 months, and 30.57% had reproductive system disease; 72.28% of the investigated medical staff often worked at night, 47.25% often worked overtime (more than 3 days a week) , and 22.27% worked over 8 hours daily. The respondents who often worked overtime had a significantly higher prevalence of reproductive system disease than those who did not often work overtime (χ(2)= 58.65, P<0.01) . The respondents who often worked at night had a significantly higher rate of miscarriage than those who did not work at night (χ(2)=41.57, P<0.01) . In all respondents, 87.08% were often exposed to chemical injuries such as disinfectants, and 78.15% had contact with noise, radiation, and other physical injuries; the medical staff exposed to chemical and physical injuries had a significantly higher proportion of individuals with a history of miscarriage than the unexposed staff (χ(2)=10.04, P<0.01; χ(2)=13.30, P<0.01) . Conclusion: Much attention should be paid to the reproductive health of female medical staff in the provincial maternal and child health hospital, who have high working strength. The occupational hazard factors can be avoided by reasonably arranging the work schedule and creating a supportive environment to improve the reproductive health of female medical staff.

[Mental health problems among female staff in a provincial maternal and child health hospital: an investigation of 647 individuals]

Objective: To investigate the current status of depression and anxiety among female staff in a maternal and child health hospital, and to provide a basis for developing related prevention and intervention measures and promoting the mental health of female staff. Methods: The female staff from a provincial maternal and child health hospital completed a psycho-health questionnaire survey on Internet from June to October, 2016. The questionnaires used in the survey consisted of Patient Health Questionnaire (PHQ-9) , Generalized Anxiety Disorder Scale (GAD-7) , and Symptom Checklist-90 (SCL-90) . The distribution features of mental health problems such as depression and anxiety were analyzed according to the results: of the questionnaire survey. Results Of all female staff surveyed, 42.04% showed depression symptoms, 28.90% showed anxiety symptoms, and 26.12% showed comorbid symptoms of depression and anxiety. Moderate or severe depression (anxiety) was mainly distributed among the female staff with comorbid symptoms (90.63% and 97.01%, respectively) . There were significant differences in the distribution of moderate or severe anxiety symptoms between the medical staff and nursing staff (χ(2)= 5.81, P=0.05) and between those with intermediate and junior professional titles (χ(2)=7.99, P=0.018) . As for SCL-90 results, the total score, total average score, and scores on factors of somatization, compulsion, interpersonal sensitivity, depression, and anxiety in the female staff with comorbid symptoms, moderate or severe depression, and moderate or severe anxiety were significantly higher than the national norm (P<0.01) , while the scores on paranoid and psychotic factors were significantly lower than the national norm (P<0.01) . The numbers of cases of positive factors were significantly higher in the female staff with comorbid symptoms than in the female staff with a single symptom and asymptomatic female staff (both P<0.01) , and positive cases were mainly distributed in depression, interpersonal sensitivity, compulsion, anxiety, and somatic factors. Conclusion: The prevalence of depression and anxiety is high among female staff in the maternal and child health hospital, mainly characterized by comorbid symptoms of moderate or severe depression and anxiety. Comorbidity is accompanied by mental health problems such as interpersonal sensitivity, obsessive compulsion, and physical discomfort. Corresponding measures are needed for the prevention and intervention of mental health problems among female staff in the maternal and child health hospital.

Oncogenic regulatory circuits driven by 19q13 rs11672691 underlies prostate cancer aggressiveness

The 19q13 allele rs11672691 has been reproducibly found in association with aggressive form of prostate cancer, yet the underlying mechanism remains totally unknown. We have recently uncovered a mechanism by which rs11672691 influenced a novel oncogenic regulatory circuit, including HOXA2, PCAT19 and CEACAM21, thereby contributing to prostate cancer aggressiveness.

Biology and Clinical Implications of the 19q13 Aggressive Prostate Cancer Susceptibility Locus

Genome-wide association studies (GWAS) have identified rs11672691 at 19q13 associated with aggressive prostate cancer (PCa). Here, we independently confirmed the finding in a cohort of 2,738 PCa patients and discovered the biological mechanism underlying this association. We found an association of the aggressive PCa-associated allele G of rs11672691 with elevated transcript levels of two biologically plausible candidate genes, PCAT19 and CEACAM21, implicated in PCa cell growth and tumor progression. Mechanistically, rs11672691 resides in an enhancer element and alters the binding site of HOXA2, a novel oncogenic transcription factor with prognostic potential in PCa. Remarkably, CRISPR/Cas9-mediated single-nucleotide editing showed the direct effect of rs11672691 on PCAT19 and CEACAM21 expression and PCa cellular aggressive phenotype. Clinical data demonstrated synergistic effects of rs11672691 genotype and PCAT19/CEACAM21 gene expression on PCa prognosis. These results provide a plausible mechanism for rs11672691 associated with aggressive PCa and thus lay the ground work for translating this finding to the clinic.

High-throughput screening of prostate cancer risk loci by single nucleotide polymorphisms sequencing

Functional characterization of disease-causing variants at risk loci has been a significant challenge. Here we report a high-throughput single-nucleotide polymorphisms sequencing (SNPs-seq) technology to simultaneously screen hundreds to thousands of SNPs for their allele-dependent protein-binding differences. This technology takes advantage of higher retention rate of protein-bound DNA oligos in protein purification column to quantitatively sequence these SNP-containing oligos. We apply this technology to test prostate cancer-risk loci and observe differential allelic protein binding in a significant number of selected SNPs. We also test a unique application of self-transcribing active regulatory region sequencing (STARR-seq) in characterizing allele-dependent transcriptional regulation and provide detailed functional analysis at two risk loci (RGS17 and ASCL2). Together, we introduce a powerful high-throughput pipeline for large-scale screening of functional SNPs at disease risk loci.

Functional characterization of disease-causing variants at risk loci in cancer is challenging. Here, in prostate cancer the authors report a pipeline for high-throughput single-nucleotide polymorphisms sequencing (SNPs-seq) for large scale screening of functional SNPs at disease risk loci.

Mutation L437P in the 2B domain of keratin 1 causes diffuse palmoplantar keratoderma in a Chinese pedigree

Diffuse palmoplantar keratoderma (DPPK) is an autosomal dominant genodermatosis characterized by uniform hyperkeratosis of the palm and sole epidermis. This disorder can be caused by mutations in the genes keratin 1, keratin 9, keratin 16, desmoglein 1 and plakoglobin. Here we present a DPPK Chinese pedigree and identify the aetiology as a novel missense mutation, L437P, located in a highly conserved helix motif in domain 2B of KRT1. Functional analysis shows that overexpression of the L437P mutant in cultured cells leads to abnormal intermediate filament networks and filament aggregation. This gain-of-function mutation highlights the role of domain 2B in mediating filament assembly.

Interleukin-6 is essential for Staphylococcal exotoxin B-induced T regulatory cell insufficiency in nasal polyps

BACKGROUND

The pathogenesis of nasal polyps is still unclear. There is increasing evidence indicating that Staphylococcal aureus (S. aureus) is associated with the formation of nasal polyps, but the mechanism has not been well documented to date.

METHODS

We stimulated cultured nasal polyps and turbinate tissues with Staphylococcal exotoxin B (SEB), detected the expression of pro-inflammatory cytokines (IL-2, IL-6, and IL-8) and T cell cytokines (IFN-gamma, IL-4, IL-5, IL-10, and IL-17) in the supernatants, and evaluated mRNA expression (T-bet, GATA-3, Foxp3, and RORgammat) and frequencies of CD4+CD25+ T regulatory cells (Tregs) in nasal tissues. We also evaluated the effects of blocking IL-6 with monoclonal antibodies to T cell profiles in cultured nasal tissues stimulated by SEB.

RESULTS

Levels of IL-6, IFN-gamma and IL-4 increased significantly in SEB-stimulated nasal polyps. Meanwhile, mRNA expressions of T-bet and GATA-3 were significantly up-regulated, while Foxp3 was inhibited and the frequencies of CD4+CD25+ Tregs were decreased after SEB stimulation. After blocking IL-6, the levels of IL-10 and Foxp3 mRNA, as well as the frequencies of CD4+CD25+ Tregs, were significantly increased, while IFN-gamma and IL-4 production and the mRNA expression of T-bet and GATA-3 were significantly inhibited.

CONCLUSIONS

SEB is able to modulate pro-inflammatory factors, T-helper type 1/Th2 profiles and suppress Treg activity in cultured nasal polyps, which were rescued by blocking IL-6 activity. Therefore, IL-6 is essential for SEB-induced Treg insufficiency in nasal polyps.

Foxp3+ T regulatory cells (Tregs) are increased in nasal polyps (NP) after treatment with intranasal steroid

The pathogenesis of chronic rhinosinusitis (CRS) with nasal polyps(NP) is still poorly understood. To evaluate the role of Foxp3+ T regulatory cells (Tregs) in the pathogenesis and management of NP, we investigated the location and expression of Foxp3 in NP before and after treatment with intranasal steroid. NP specimens were obtained from 14 patients with NP before and after intranasal administration of mometasone (50 microg/day for 4 weeks). Foxp3 was detected by double immunofluorescence stain, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), flow cytometry and western blot. The concentration of interleukin(IL)-10 in supernatants of homogenized tissue was measured by enzyme-linked immunosorbent assay (ELISA). We found that Foxp3 and IL-10 were downregulated in NP compared to the control mucosa (P<0.05). Foxp3 and IL-10 expression were increased significantly after intranasal steroid treatment (P<0.05). And Foxp3 was tightly correlated with IL-10 in NP (P<0.05) after treatment. These data suggest that Foxp3 is downregulated in NP and intranasal steroid attenuates the chronic inflammatory response by enhancing the expression and function of Foxp3 in NP.

Characterization of reflection intermittency in a composite granular chain

The physical factors controlling the power-law behavior of impact energy in a composite granular chain remain elusive. Based on event-driven simulations and the on-off intermittency of wave reflections, we obtain the probability distribution functions of the waiting time tau and the energy leakage DeltaE . They exhibit lognormal distributions, which together with the relationship between DeltaE and tau allow one to explain directly the power-law behavior of the confined energy. This work may be extended to higher dimensions and help us understand the complex dynamics in granular materials.

Crossover in the power-law behavior of confined energy in a composite granular chain

We present a numerical study of the impact energy decay in a composite granular chain containing two heavy and one light sections. We observe a marked crossover in the power-law behavior of the impact-energy decay. The average reflection frequency first increases with a decreasing acceleration, and arrives at its maximum at "crossing" time then decays almost exponentially. The analysis demonstrates that this phenomenon is related to the structural transition from compression to dilation state in both heavy-particle sections. The further calculations suggest the dependence relation of the power-law exponent (gammacb) in compression state on the mass ratio (m2/m1) and the Hertz law exponent (n) of the composite granular chain gammacb approximately (m2/m1)1/(n+1).

An improved mechanical technique for assisted hatching

BACKGROUND

Varied clinical outcomes of assisted hatching (AH) have been reported. We attempt to investigate whether the size of the zona opening created by AH is adequate for blastocyst hatching, and, if not, set up a new method to improve it.

METHODS

A new AH technique, long zona dissection (LZD), was established, and experiments were performed to compare the effects of different sizes of zona opening on complete hatching of blastocysts in mouse and human embryos in vitro.

RESULTS

The LZD technique can create a long zona slit on early embryos, even blastocysts, with the slit size beyond two-thirds of zona diameter. Compared with three-dimensional partial zona dissection, LZD can significantly enhance the hatching speed and the rate of complete hatching of mouse blastocysts (93.9%). All (100%) human blastocysts completely hatched following LZD; however, when the slit size after AH was about two-fifths of zona diameter, more of the larger inner cell masses (ICM) became trapped by the zona opening during hatching than the smaller ICM (53.3 versus 12.5%, P = 0.01).

CONCLUSIONS

Zona opening of moderate size following AH is inadequate for the completion of blastocyst hatching in vitro; in some cases, however, it can be significantly improved by LZD.

Anesthetic management for separation of craniopagus twins

We report the anesthetic management of a case of separation of craniopagus twins with unbalanced cross circulation and one twin with renal dysfunction. After intravenous induction, anesthesia was maintained with isoflurane inhalation and propofol infusion. Twin A survived but Twin B died after the surgery. The anesthetic problems during the operation are discussed.

Confirmation and refinement of a genetic locus for disseminated superficial actinic porokeratosis (DSAP1) at 12q23.2-24.1

BACKGROUND

Our previous study has identified two loci for disseminated superficial actinic porokeratosis (DSAP), but the genes responsible are still unknown.

OBJECTIVES

To narrow down the candidate regions and to assess candidate genes.

METHODS

A genome-wide scan and linkage analysis were carried out in a newly collected five-generation Chinese family with DSAP. In addition, six candidate genes were screened for possible DSAP-associated mutations.

RESULTS

DSAP in this family was associated with chromosome 12q. Fine mapping and haplotype construction refined the DSAP1 locus to a 4.4-cM interval. No disease-associated mutation was detected in CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 or KIAA0789 genes.

CONCLUSIONS

The DSAP1 locus was localized to a 4.4-cM interval at chromosome 12q23.2-24.1. CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 and KIAA0789 genes were not associated with DSAP1.

A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1

BACKGROUND

Disseminated superficial actinic porokeratosis (DSAP) is a chronic cutaneous disorder characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. It develops in teenagers in sun-exposed areas of skin and usually follows an autosomal dominant inheritance pattern. The first locus for DSAP was localized to chromosome 12q23.2-24.1, but no gene responsible for porokeratosis has been identified to date.

OBJECTIVES

To determine whether DSAP is a genetically heterogeneous disorder and to identify the disease gene locus in a three-generation Chinese family with DSAP.

METHODS

Genetic linkage analysis was carried out in this family using 15 microsatellite markers between D12S1671 and D12S369 on chromosome 12q, followed by a genome-wide scan with 382 microsatellite markers from the autosomes.

RESULTS

Genetic linkage analysis with chromosome 12q markers suggested that the locus in this family is not linked to chromosome 12q. A genome-wide scan and fine mapping finally localized the locus for DSAP in this family to a 6.4-cM region between markers D15S1023 and D15S1030 at chromosome 15q25.1-26.1. This DSAP locus was named DSAP2.

CONCLUSIONS

The previous results and this study have shown that DSAP is a genetically heterogeneous disorder; a novel locus for DSAP, termed DSAP2, was mapped to a 6.4-cM region between markers D15S1023 and D15S1030.

[Molecular clonging of the human dimethyglycine dehydrogenase-like gene (DMGDHL1) from the sarcosinemia critical region at 9q34]

Through the analysis of EST database, we obtained one human EST (GenBank: H28856) which showed significant similarity with the partial coding sequence of rat dimethylglycine dehydrogenase gene. This EST was mapped to 9q34 due to 95.6% identity with one genomic sequence (GenBank: AC002295). A pair of primers (HRP-1/HRP-2) designed on the sequence of the EST were coupled with the primers (lambda gt10-5/lambda gt10-3) on the vector flanking cloning site respectively to amplify the 5' and 3' cDNA beyond the EST. New primers designed based on novel cDNA sequence overlapped with the sequence within EST H28856 were used for amplification with lambda gt10-5 and lambda gt10-3 by the similar way as above untill a complete ORF was obtained. Finally, a 1,970 bp sequence (termed as dimethylglycine dehydrogenase like gene isoform I, DMGDHL1a) containing a 1,428 bp complete coding sequence from the live cDNA library and 1,475 bp sequence (isoform II, termed as DMGDHL1b) containing a 1,296 bp complete coding sequence from the fetas live cDNA library were obtained. Fourteen exons were identified in isoform I and the first nine exons of isoform II which shared with isoform I could be determined too. The last 105 bp cDNA sequence of isoform II could not be found in the public database, indicating a very large intron (> 123 kb) existed between exon 9 and exon 10 of isoform II. DMGDHL1 showed highly homology on both cDNA and amino acid level with rat dimethylglycine dehydrogenase (60% identity in 135 bp and 35% identity in 436 residues respectively). It was reported that human sarcosinemia gene was mapped at 9q34. Therefore it could be a good candidate gene for the sarcosinemia.

Identification of a locus for disseminated superficial actinic porokeratosis at chromosome 12q23.2-24.1

Disseminated superficial actinic porokeratosis is an autosomal dominant cutaneous disorder characterized by many uniformly small, minimal, annular, anhidrotic, and keratotic lesions. The genetic basis for this disease is unknown. Using a genomewide search in a large Chinese family, we identified a locus at chromosome 12q23.2-24. 1 responsible for disseminated superficial actinic porokeratosis. The fine mapping study indicates that the disseminated superficial actinic porokeratosis gene is located within a 9.6 cM region between markers D12S1727 and D12S1605, with a maximum two-point LOD score of 20.53 (theta = 0.00) at D12S78. This is the first locus identified for a genetic disease where the major phenotype is porokeratosis. The study provides a map location for isolation of a gene causing disseminated superficial actinic porokeratosis.

[Molecular cloning of one splicing form of human M6b cDNA]

X-linked, early onset Pelizaeus-Merzbacher disease (PMD) and part of X-linked spastic paraplegia are caused by mutation of proteolipid protein. M6b (U45955) partially cloned by Olinsky was considered as a member of PLP gene family. One novel fragment about 300 bp partially overlapped but differed in 5'part with U45955 was obtained by nested PCR. Assembly of the novel sequence with U45955 make a 1.642kb cDNA sequence with an open reading frame encoding 265 amino acids, which was verified by sequence of PCR products from brain cDNA library. The cDNA (termed M6ba) and its deduced peptide sequence showed significant similarity to murine M6b gene and protein (91.2% and 93.4% respectively). Northern blot, PCR amplification in cDNA library and EST analysis indicated that human M6b gene has at least three splicing forms. M6ba also showed significant similarity to PLP gene, they encode strongly hydrophobic protein and all their hydrophobic region are highly conserved. Gene structure analysis showed that the coding region of M6ba was composed of seven exons.

Mutations in the gene encoding gap junction protein beta-3 associated with autosomal dominant hearing impairment

Hearing impairment is the most commonly occurring condition that affects the ability of humans to communicate. More than 50% of the cases of profound early-onset deafness are caused by genetic factors. Over 40 loci for non-syndromic deafness have been genetically mapped, and mutations in several genes have been shown to cause hearing loss. Mutations in the gene encoding connexin 26 (GJB2) cause both autosomal recessive and dominant forms of hearing impairment. To study the possible involvement of other members of the connexin family in hereditary hearing impairment, we cloned the gene (GJB3) encoding human gap junction protein beta-3 using homologous EST searching and nested PCR. GJB3 was mapped to human chromosome 1p33-p35. Mutation analysis revealed that a missense mutation and a nonsense mutation of GJB3 were associated with high-frequency hearing loss in two families. Moreover, expression of Gjb3 was identified in rat inner ear tissue by RT-PCR. These findings suggest that mutations in GJB3 may be responsible for bilateral high-frequency hearing impairment.

[Localization of the gene for 4 hereditary multiple exostoses families]

We investigated 11 families with hereditary multiple exostoses (EXT) by linkage analysis using 8 short-tandem-repeat (CA)n polymorphic markers on chromosomes 8, 11 and 19. The Lod score in four families indicated that the gene responsible for EXT is located in the pericentromeric region of chromosome 11.

Isolation of 24 novel cDNA fragments from microdissected human chromosome band

The strategy of isolating the band-specific expression fragments from a probe pool generated by human chromosome microdissection was reported. A chromosome 14q24.3 band-specific single copy DNA pool was constructed based on this probe pool. Using total DNA of the pool as probe to hybridize the human marrow cDNA library, 68 primary positive clones were selected from 5 x 10(5) cDNA clones. Among these primary clones, 32 secondary clones were obtained after second-round screening and designed as cFD14-1-32. Finally, 24 band-specific expression fragments were identified from these 32 positive clones by DNA hybridization. Those band-specific clones can hybridize to both 14q24.3 DNA and human genomic DNA but can't hybridize to 17q11-12 DNA. Partial sequences of 13 fragments of them were sequenced and identified as novel cDNA sequences, and these sequences were proved to have some homology with known genes in NCBI database. Analysis of expression spectrum of cFD14-1 suggested that the cDNA fragments thus obtained should be used to isolate the genes can not been cloned in 14q24.3 region.

A novel case of unilateral blepharophimosis syndrome and mental retardation associated with de novo trisomy for chromosome 3q

We have evaluated a 3 2/12 year old girl who presented with unilateral blepharophimosis, ptosis of the eyelid, and mental retardation. Additional dysmorphic features include microcephaly, high, narrow forehead, short stubby fingers, and adduction of the right first toe. Cytogenetic analysis showed an unbalanced karyotype consisting of 46,XX,add(7)(q+) that was de novo in origin. Fluorescence in situ hybridisation (FISH) using microdissected library probe pools from chromosomes 1,2,3,7, and 3q26-qter showed that the additional material on 7q was derived from the distal end of the long arm of chromosome 3. Our results indicate that the patient had an unbalanced translocation, 46,XX,der(7)t(3;7)(q26-qter;q+) which resulted in trisomy for distal 3q. All currently reported cases of BPES (blepharophimosis-ptosis-epicanthus inversus syndrome) with associated cytogenetic abnormalities show interstitial deletions or balanced translocations involving 3q22-q23 or 3p25.3. Our patient shares similar features to BPES, except for the unilateral ptosis and absence of epicanthus inversus. It is possible that our patient has a contiguous gene defect including at least one locus for a type of blepharophimosis, further suggesting that multiple loci exist for eyelid development.

[Isolation of the expression fragments with the probe pool of human chromosome 14 q 24.3 generated by microdissection]

The strategy of isolating the band-specific expression fragments from the probe pool of human chromosome generated by microdissection was reported in present paper. A chromosome 14 q 24.3 band-specific single copy DNA library was constructed based on this probe pool. Using this pool DNA as probe to hybridize the human bone marrow cell cDNA library, 68 primary positive clones were selected from 5 x 10(5) cDNA clones. Of them 32 clones were got in second-round screening and designed as cFD 14-1-32. Finally, 24 bandspecific expression fragments were identified from these 32 positive clones by analysing the results of DNA hybridization. Those band-specific clones can hybridize to both 14 q 24.3 DNA and human genomic DNA, but have no hybridization signal with 17 q 11-12 DNA. Partial sequences of 13 fragments of them were sequenced and were identified as novel cDNA sequences as well as have some homology with known genes in NCBI database. Analysis of expression spectrum of cFD 14-1 suggested that the cDNA fragments thus obtained can be used to isolate the genes not yet be cloned in 14 q 24.3 region.

[Identification of the origin of 7q+ marker chromosome in a mental retard patient]

The present chromosome-specific and chromosome-band-specific probe pools constructed by the technique of human chromosome microdissection and PCR were taken as painting probes. Using the forward chromosome painting and chromosome screening method, we had identified a chromosome additional fragment of a 7 q+ marker chromosome in a patient originated from 3 q 26-->3 qter, and ascertained the patient's karyotype was 46, XX, -7, + der (7) t (7;3) (7 pter-->7 q 32::3 q 26-->3 qter). Applying this strategy, we can identify the origin of marker chromosomes fastly and effectively.

[Construction and application of the chromosomal specific probe pool from human chromosome no. 7]

We constructed a chromosomal specific probe pool from human chromosome No. 7 using the techniques of chromosomal microdissection, PCR and chromosomal painting. A patient's pedigree with an abnormal chromosome No. 7 were analysed by the above probe pool.

[Influence of endothelin-1 on ventricular fibrillation threshold in acute myocardial ischemic rats]

The influence of endothelin-1 on ventricular fibrillation threshold was studied in acute myocardial ischemic rats. Endothelin-1 (1.5-3.0 micrograms.kg-1 i.v.) given 5 min before ischemia reduced the ventricular fibrillation threshold in a dose- and time-dependent manner. Its effect lasted at least 60 min. A marked increase of spontaneous ventricular tachycardia and myocardial infarct size was seen and the arterial blood pressure was at a higher level (18.5-20.1/14.4-15.8 kPa) after 3.0 micrograms.kg-1. Diltiazem prevented partially from reduction of ventricular fibrillation threshold, eliminated completely the vasopressor response and limited the extension of myocardial necrosis induced by endothelin-1.

Sequencing for 4 single-copy DNA segments from human chromosome 8q24.1

A successful method for constructing human chromosome 8q24.1 band specific probe pool by microdissection and microcloning is described in this paper. The probe pool was proved to be band-specific by fluorescence in situ hybridization. Through Southern blot analysis, 34 single copy DNA segments were obtained and four of them were sequenced. It is possible to provide useful landmarks for constructing human chromosome 8q24.1 physical map and STSs map.

Lactic Acid efflux as a mechanism of hypoxic acclimation of maize root tips to anoxia

Hypoxic pretreatment (3 kPa oxygen) of maize (Zea mays L.) root tips improved their survival time in a subsequent anoxic incubation from 10 h to more than 3 d, provided that glucose was added to the medium to sustain metabolism. The glycolytic flux (lactate + ethanol) was the same in both pretreated and untreated root tips during the 1st h after transfer to anoxia. It was only after 2 h that it declined sharply in untreated tips, but was sustained in pretreated ones. Right after the transition from normoxia to anoxia of untreated root tips, the only fermentative product detected was lactic acid, which accumulated in a 7:1 proportion after 30 min in tissue and medium, respectively. It took 10 min before ethanol could be detected and 20 min for it to be produced at its maximum rate at the expense of lactate production, which slowed down. In contrast, in hypoxically pretreated root tips, ethanol was produced at a maximum rate right after the transfer to anoxia. Concurrently, low amounts of lactic acid were produced that accumulated in a 1:1 proportion after 30 min in tissue and medium, respectively. This large efflux of lactic acid could account for the higher cytoplasmic pH values always found in pretreated tissues. The presence of cycloheximide during pretreatment abolished this difference, suggesting that the greater efficiency of lactate efflux was linked to protein synthesis. The role of lactate in cytosolic pH regulation and in sensitivity to anoxia is discussed.

Microdissection of human high resolution banded chromosome, polymerase chain reaction and microcloning

A simple technique for microdissection of specific region of human high resolution banded chromosome, followed by polymerase chain reaction (PCR), and microcloning was successfully used to microdissect 4 chromosomal pieces from the distal one third from band 11.2 to the terminal of the short arm of Y chromosome where the testis determining factor is located; 3.6 x 10(4) clones were obtained after 30 cycles of PCR. We analysed 41 clones with insert. The size of insert ranges from 140 to 350 bp (average 250 bp). A Southern blot analysis was done for one of them, and a 2.5 kb Hind III fragment was detected.

[Effects of corticosterone on spontaneous discharges of rat hypothalamic paraventricular neurons in vitro]

Experiments were performed to investigate the effects of corticosterone on electrical activities of paraventricular neurons in rat hypothalamic slices. In unstimulated conditions, most of the neurons had either a slow irregular (48.1%) or fast continuous pattern (42.5%) of discharge. Only a small portion (9.4%) of the cells shows phasic activity. During perfusion of the slices with corticosterone (10(-7), 10(-6) mol/L), 25 out of 104 paraventricular neurons were profoundly inhibited with a short latency, 8 neurons were excited and the remaining cells showed no response. The response, the magnitude of the cells which depended upon the concentration of corticosterone, could be reversed by concomitant application of RU38486 (10(-7), 10(-6) mol/L), a competitive antagonist of glucocorticoid's cytosolic receptor. These results provide further evidence that corticosterone has rapid effects on rat hypothalamic paraventricular neurons, and suggests the existence of membrane receptors for glucocorticoid in paraventricular neurons.

[Effects of noradrenaline and acetylcholine on electric activity of paraventricular neurons of rat hypothalamic slices]

The effects of noradrenaline (NA) and acetylcholine (ACh) on 90 paraventricular neurons from 31 hypothalamic slices prepared from rat were observed. After perfusing the brain slices with NA (10(-6) mol/L, 3 min), discharge rate of 14/73 (17%) nonphasic and 7/12 (58.3%) phasic neurons was significantly increased, while that of 10/73 (12%) nonphasic and 2/12 (16.6%) phasic neurons was significantly decreased, even ceased. 50/73 (64%) of the nonphasic and 3/12 (25%) of the phasic neurons were non-responsive. The effects of NA on the nonphasic neurons were completely blocked by alpha receptor blocker phentolamine. The effects of NA on phasic neurons were partly blocked by phentolamine or propranolol (beta receptor blocker). After perfusing hypothalamic slices with ACh (10(-7) mol/L, 3 min), the firing rate of 15/73 (19%) nonphasic and 6/12 (50%) phasic neurons was increased, while that of 9/73 (11%) nonphasic and 2/12 (16.6%) phasic neurons was decreased. 54/73 (69%) nonphasic and 4/12 (33.3%) phasic neurons were non-responsive. The effect of ACh on the neurons could be reversed by atropine. The effect of scopolamine (M blocker) is similar to that of atropine. The experimental results suggest that the excitatory or inhibitory effect of NA or ACh on paraventricular neurons has mediated respectively by alpha, beta or M receptors.

Parental origin and mechanism of formation of X chromosome structural abnormalities: four cases determined with RFLPs

Parental origin and mechanism of formation of X chromosome structural abnormalities were studied in one each case of dup(X)(pter----p11.4::p22.1----qter), del(X)(qter----p11:), i(X)(qter----cen----qter), and inv dup(X) (pter----q22::q22----pter) using various X-linked RFLPs as genetic markers. Segregation and densitometric analyses on polymorphic DNAs revealed that the dup(Xp) and the del(Xp) are both of paternal origin and the i(Xq) and i dic(X) are of maternal origin. The dup(Xp) had arisen by an unequal sister chromatid exchange and the del(Xp) had occurred through an intrachromosomal breakage-reunion mechanism, both in the paternal X chromosome. The i(Xq) had arisen either through centromere fission of a maternal X chromosome, followed by duplication of its long-arm, or through a translocation between two maternal X chromosomes after meiotic crossing-over. The inv dup(X) arose through sister chromatid breakage and reunion in a maternal X chromosome. These results, together with those of previous studies, suggest that the de novo abnormalities due to events involving centromere disruption arise predominantly during oogenesis, while those due to simple breakage-reunion events occur preferentially during spermatogenesis.

H Efflux and Hexose Transport under Imposed Energy Status in Maize Root Tips

The relationship between changes in H(+) flux and sugar transport in maize Zea mays L. DEA root tips have been investigated using two methods for controlling the cellular nucleotide level: (a) incubation in the presence of a glucose analog, the 2-deoxyglucose, which decreased the ATP level to less than 15% of its initial value within 60 minutes without changing the ADP and AMP levels; (b) an hypoxic treatment which also decreased the ATP level but with a concomitant rise in ADP and AMP. In both cases the rate of hexose transport was not modified until ATP had dropped to 70% of its initial value; then it decreased with the cellular ATP level. The residual uptake rate at very low ATP concentrations still represented 50% of the maximum rate with the dGlc treatment but only the diffusion rate in anoxia. H(+) efflux was abolished in anoxia but not by the 2-deoxyglucose treatment, in spite of a lower cellular ATP concentration. Our results are consistent with an inhibition of H(+)-ATPase activity in anoxia by the high levels of cellular ADP and AMP, and provide in vivo evidence that sugar uptake is dependent upon the proton motive force rather than cellular ATP concentration. The absence of stimulation of H(+) extrusion by ferricyanide in either normoxic or hypoxic conditions suggests that a redox system does not appear to contribute to H(+) secretion under the conditions of this investigation.

[Effects of serotonin on the electric activity of paraventricular neurons of in vitro rat hypothalamic slices]

Hypothalamic slices were prepared with a vibratome. The spontaneous discharge of 46 paraventricular neurons was recorded by glass microelectrode from 20 such slices, and effects of serotonin on spontaneous discharge were observed. After perfusing the brain slices with artificial cerebro-spinal fluid containing serotonin (10(-6) mol/L) for 3 min, discharge rate of 16 units is significantly increased with latency 1.21 +/- 1.21 (mean + SD) min, this response is blocked by serotonin antagonist, cyproheptadine. The discharges of 3 units were decreased, but 25 units non-responsive. The experimental results suggest that about 1/3 of paraventricular neurons can be activated by topical application of serotonin via the activation of 5-HT receptors.

[A simple vibratome for brain slice]

A simple vibratome was fabricated using double-function electric shaver and microscopic platform. Spontaneous discharge of neurons in hippocampal and hypothalamic brain slices (in 300-400 microns thick) prepared by the vibratome could kept above 12 hours in artificial cerebro-spinal fluid.

Characterization of the hexose transport system in maize root tips

Sugar-depleted excised maize (Zea mays L.) root tips were used to study the kinetics and the specificity of hexose uptake. It was found that difficulties induced by bulk diffusion and penetration barriers did not exist with root tips. Several lines of evidence indicate the existence of a complex set of uptake systems for hexoses showing an overall biphasic dependence on external sugar concentrations. The results suggest that the high and the low affinity components might be located on the same carrier. One uptake system was specific for fructose, but the high affinity component was repressed by high concentrations of external glucose. A second system was specific for glucose and its analogs (2-deoxy-d-glucose and 3-O-methyl-d-glucose), and a third one, more complex, had a high affinity for glucose and its analogs but could transport fructose when glucose was not present in the external solution. A simple method is proposed to determine the inhibitor constants in competition experiments.