Batch-mode degradation of high-strength phenolic pollutants by Pseudomonas aeruginosa strain STV1713 immobilized on single and hybrid matrices

Controlled environments are pivotal in all bioconversion processes, influencing the efficacy of biocatalysts. In this study, we designed a batch bioreactor system with a packed immobilization column and a decontamination chamber to enhance phenol and 2,4-dichlorophenol degradation using the hyper-tolerant bacterium Pseudomonas aeruginosa STV1713. When free cells were employed to degrade phenol and 2,4-DCP at a concentration of 1000 mg/L, the cells completely removed the pollutants within 28 h and 66 h, respectively. Simultaneous reductions in chemical oxygen demand and biological oxygen demand were observed (phenol: 30.21 mg/L/h and 16.92 mg/L/h, respectively; 2,4-dichlorophenol: 12.85 mg/L/h and 7.21 mg/L/h, respectively). After assessing the degradation capabilities, the bacterium was immobilized on various matrices (sodium alginate, alginate-chitosan-alginate and polyvinyl alcohol-alginate) to enhance pollutant removal. Hybrid immobilized cells exhibited greater tolerance and degradation capabilities than those immobilized in a single matrix. Among them, polyvinyl alcohol-alginate immobilized cells displayed the highest degradation capacities (up to 2000 mg/L for phenol and 2500 mg/L for 2,4-dichlorophenol). Morphological analysis of the immobilized cells revealed enhanced cell preservation in hybrid matrices. Furthermore, the elucidation of the metabolic pathway through the catechol dioxygenase enzyme assay indicated higher activity of the catechol 1,2-dioxygenase enzyme, suggesting that the bacterium employed an ortho-degradation mechanism for pollutant removal. Additionally, enzyme zymography confirmed the presence of catechol 1,2-dioxygenase, with the molecular weight of the enzyme determined as 245 kDa.

Revealing the degradation mechanisms of the hyper-tolerant bacterium Pseudomonas aeruginosa STV1713 under high phenol and 2,4-DCP-induced stress conditions through RNA-seq analysis

The ability of bacteria to efficiently remove phenolic pollutants depends on their genetic makeup and environmental conditions. This study examined a novel strain, Pseudomonas aeruginosa STV1713, for degrading higher concentrations of phenol and 2,4-dichlorophenol. After optimization, a combination of degradation parameters, such as pH (7.0), temperature (32.5 °C), and ammonium nitrate concentration (0.7 g/L), was found to reduce degradation time while promoting cell growth. Under these optimal conditions, the bacterium effectively degraded up to 2000 mg/L of phenol and 1400 mg/L of 2,4-dichlorophenol, while maximum tolerance was observed till 2100 mg/L and 1500 mg/L, respectively. Metabolic profiling identified crucial metabolites in the ortho-degradation pathway during pollutant removal. Additionally, transcriptome analysis revealed that P. aeruginosa STV1713 utilizes different branches of the beta ketoadipate pathway for phenol and 2,4-DCP removal. Moreover, under high pollutant stress, the bacterium survived through differential gene expression in ribosome biogenesis, chemotaxis, membrane transport, and other pathways.

Wastewater microbial diversity versus molecular analysis at a glance: a mini-review

Microorganisms play a vital role in biological wastewater treatment by converting organic and toxic materials into harmless substances. Understanding microbial communities' structure, taxonomy, phylogeny, and metabolic activities is essential to improve these processes. Molecular microbial ecology employs molecular techniques to study community profiles and phylogenetic information since culture-dependent approaches have limitations in providing a comprehensive understanding of microbial diversity in a system. Genomic advancements such as DNA hybridization, microarray analysis, sequencing, and reverse sample genome probing have enabled the detailed characterization of microbial communities in wastewater treatment facilities. This mini-review summarizes the current state of knowledge on the diversity of microorganisms in wastewater treatment plants, emphasizing critical microbial processes such as nitrogen and phosphorus removal.

FISH Versus IHC as the Primary Test for HER-2 Analysis: Cost Analysis, Aneusomy Significance and Gene Heterogeneity in a Consecutive Series

Objective: To utilize a test algorithm for HER-2 that has the lowest cost per reportable test and establishes the most accurate results for trastuzumab therapy decisions.By restricting hybridization area, we have reduced the probe quantity required without altering sensitivity and specificity. Our FISH reagent cost per test is $32.20. The cost per reportable test is $62.30 for FISH and $56.86 for IHC (Ventana). FISH cost/result is slightly costlier than IHC cost/result. However, reflex to FISH (20-25%) after 2+ IHC analyses is a more expensive test algorithm than primary FISH analysis with reflex to IHC (5.6%). The total cost of the FISH first algorithm/100 cases is $6548 and for IHC first algorithm is $6932. In a recent study of patients being considered for trastuzumab treatment, primary FISH analysis was the most cost-effective diagnostic approach.Studies have shown greater accuracy and precision of FISH vis a vis IHC in predicting response to trastuzumab: Our institution has selected FISH as the primary method for assessing HER-2 status, rather than IHC.HER-2 gene amplification is observed in 15-30% of breast cancers. FISH positivity predicts the response to trastuzumab. Increased gene copies may be due to repeated duplication of HER-2 amplicon or inherent chromosomal instability due to mitotic mis-segregation of cancer cells. Aneusomy is frequently found in cancers and may complicate the interpretation of HER-2 testing results. Tumors with aneusomy of 17 without amplification have a high and uncertain response rate to trastuzumab. There is no clear consensus on how to report tumor heterogeneity in cases due to 17 aneusomy.We report here the MGH experience in 90 consecutive cases using FISH as the primary test for assessing HER-2 status. Using CAP/ASCO guidelines for reporting HER-2 FISH, we determined 15.6% cases amplified, 5.6% equivocal and 78.9% normal. Chromosome 17 and Her2 aneusomy was observed in 27.8% of cases. Our percent aneusomy may be higher than some have reported due to preselection of cases in our reference lab setting. Most of the Her-2 amplified cases had HER-2/CEN-17 ratio >10.In one case the HER 2 amplicon extended widely to chromosome 17 centromeric region. FISH studies using Topoisomerase II alpha probes showed probable deletion of this gene putatively located within the HER-2 amplicon. Even though HER gene copy number was > 20 HER-2/Chromosome17 according to ASCO/CAP was normal (< 1.8). In instances of reported co-amplification of topoisomerase II alpha gene, its status may influence the treatment decision.The incidence of chromosome 17 aneusomy has varied from as low as 4% to as high as >30% in studies of invasive breast cancer influencing the reporting of amplification. There are no existing guidelines on how to report such tumor heterogeneity. We hope this analysis will be useful to other centers evaluating the use of primary FISH algorithm for HER-2 testing.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6037.

Somatostatin receptors in primary human breast cancer: quantitative analysis of mRNA for subtypes 1–5 and correlation with receptor protein expression and tumor pathology

Somatostatin receptors (SSTRs) have been identified in most hormone-producing tumors as well as in breast cancer. In the present study, we determined SSTR1-5 expression in primary ductal NOS breast tumors through semi-quantitative RT-PCR and immunocytochemistry. The results from the analysis of 98 samples were correlated with several key histological markers and receptor expression. All five SSTR subtypes are variably expressed at the mRNA level in breast tumors with 91% of samples showing SSTR1, 98% SSTR2, 96% SSTR3, 76% SSTR4, and 54% SSTR5. SSTR1-5 are localized to both tumor cells and the surrounding peritumoral regions as detected by immunocytochemistry. Levels of SSTR mRNA, when corrected for beta-actin levels, were highest for SSTR3 followed by SSTR1, SSTR2, SSTR5, and SSTR4. Furthermore, there was good correlation between mRNA and protein expression with 84% for SSTR1, 79% for SSTR2, 89% for SSTR3, 68% for SSTR4, 68% for SSTR5, and 78% for all five receptors. SSTR1, 2 and 4 were correlated with ER levels whereas SSTR2 showed an additional correlation with PR levels. These correlations were independent of patient age and histological grade. Moreover, using immunocytochemistry, blood vessels exhibited receptor-specific localization for SSTR2 and SSTR5. Our results indicate significant correlations between mRNA and protein expression along with receptor-specific correlations with histological markers as well as ER and PR levels. Differential distribution of SSTR subtypes in tumors and receptor-specific expression in vascular structures may be considered as a novel diagnosis for breast tumors with receptor subtype agonists.

Somatostatin receptors in primary human breast cancer: quantitative analysis of mRNA for subtypes 1--5 and correlation with receptor protein expression and tumor pathology

Somatostatin receptors (SSTRs) have been identified in most hormone-producing tumors as well as in breast cancer. In the present study, we determined SSTR1-5 expression in primary ductal NOS breast tumors through semi-quantitative RT-PCR and immunocytochemistry. The results from the analysis of 98 samples were correlated with several key histological markers and receptor expression. All five SSTR subtypes are variably expressed at the mRNA level in breast tumors with 91% of samples showing SSTR1, 98% SSTR2, 96% SSTR3, 76% SSTR4, and 54% SSTR5. SSTR1-5 are localized to both tumor cells and the surrounding peritumoral regions as detected by immunocytochemistry. Levels of SSTR mRNA, when corrected for beta-actin levels, were highest for SSTR3 followed by SSTR1, SSTR2, SSTR5, and SSTR4. Furthermore, there was good correlation between mRNA and protein expression with 84% for SSTR1, 79% for SSTR2, 89% for SSTR3, 68% for SSTR4, 68% for SSTR5, and 78% for all five receptors. SSTR1, 2 and 4 were correlated with ER levels whereas SSTR2 showed an additional correlation with PR levels. These correlations were independent of patient age and histological grade. Moreover, using immunocytochemistry, blood vessels exhibited receptor-specific localization for SSTR2 and SSTR5. Our results indicate significant correlations between mRNA and protein expression along with receptor-specific correlations with histological markers as well as ER and PR levels. Differential distribution of SSTR subtypes in tumors and receptor-specific expression in vascular structures may be considered as a novel diagnosis for breast tumors with receptor subtype agonists.

Subtypes of the somatostatin receptor assemble as functional homo- and heterodimers

The existence of receptor dimers has been proposed for several G protein-coupled receptors. However, the question of whether G protein-coupled receptor dimers are necessary for activating or modulating normal receptor function is unclear. We address this question with somatostatin receptors (SSTRs) of which there are five distinct subtypes. By using transfected mutant and wild type receptors, as well as endogenous receptors, we provide pharmacological, biochemical, and physical evidence, based on fluorescence resonance energy transfer analysis, that activation by ligand induces SSTR dimerization, both homo- and heterodimerization with other members of the SSTR family, and that dimerization alters the functional properties of the receptor such as ligand binding affinity and agonist-induced receptor internalization and up-regulation. Double label confocal fluorescence microscopy showed that when SSTR1 and SSTR5 subtypes were coexpressed in Chinese hamster ovary-K1 cells and treated with agonist they underwent internalization and were colocalized in cytoplasmic vesicles. SSTR5 formed heterodimers with SSTR1 but not with SSTR4 suggesting that heterodimerization is a specific process that is restricted to some but not all receptor subtype combinations. Direct protein interaction between different members of the SSTR subfamily defines a new level of molecular cross-talk between subtypes of the SSTR and possibly related receptor families.

Processing of rat preprocortistatin in mouse AtT-20 cells

Preprocortistatin (PPCST) has been recently identified as a novel somatostatin (SST)-related gene expressed only in brain. PPCST shares 11 of 14 residues with SST-14 at its C-terminal segment, where it features Lys-Lys and Lys-Arg basic sites for cleavage to putative cortistatin (CST)-14 and CST-29 peptides, respectively. Although synthetic replicates of the two putative CST peptides interact with SST receptors, they also display novel effects suggesting independent biological functions. Nothing is currently known about the naturally occurring mature cleavage products of PPCST posttranslational processing. Here we have cloned rat PPCST cDNA, stably expressed it in AtT-20 pituitary cells, and characterized the cellular and releasable products of PPCST processing by HPLC and radioimmunoassay using a SST-14 antibody that recognizes synthetic CST-14 and CST-29. Transfected cells released 120 +/- 21 pg of total CST-LI per plate basally, with an increase to 204 +/- 33 pg per plate with forskolin stimulation (p < 0.05). HPLC chromatograms of cell extracts revealed three peaks corresponding to CST-14, CST-29, and unprocessed PPCST (ratio, 41:55:4.5). CST was released preferentially as CST-14 (63-70%) compared with CST-29 (30-37%) under basal and forskolin-stimulated conditions. These studies demonstrate efficient processing of PPCST to both CST-14 and CST-29 through putative cleavage at both C-terminal dibasic sites of PPCST. Although the two peptides are synthesized approximately equally, CST-14 is released preferentially via the regulated secretory pathway.

Agonist-dependent up-regulation of human somatostatin receptor type 1 requires molecular signals in the cytoplasmic C-tail

We have previously reported that the human somatostatin receptor type 1 (hSSTR1) stably expressed in Chinese hamster ovary-K1 cells does not internalize but instead up-regulates at the membrane during continued agonist treatment (1 microM somatostatin (SST)-14 x 22 h). Here we have investigated the molecular basis of hSSTR1 up-regulation. hSSTR1 was up-regulated by SST in a time-, temperature-, and dose-dependent manner to saturable levels, in intact cells but not in membrane preparations. Although hSSTR1 was acutely desensitized to adenylyl cyclase coupling after 1 h SST-14 treatment, continued agonist exposure (22 h) restored functional effector coupling. Up-regulation was unaffected by cycloheximide but blocked by okadaic acid. Confocal fluorescence immunocytochemistry of intact and permeabilized cells showed progressive, time-dependent increase in surface hSSTR1 labeling, associated with depletion of intracellular SSTR1 immunofluorescent vesicles. To investigate the structural domains of hSSTR1 responsible for up-regulation, we constructed C-tail deletion (Delta) mutants and chimeric hSSTR1-hSSTR5 receptors. Human SSTR5 was chosen because it internalizes readily, displays potent C-tail internalization signals, and does not up-regulate. Like wild type hSSTR1, Delta C-tail hSSTR1 did not internalize and additionally lost the ability to up-regulate. Swapping the C-tail of hSSTR1 with that of hSSTR5 induced internalization (27%) but not up-regulation. Substitution of hSSTR5 C-tail with that of hSSTR1 converted the chimeric receptor to one resembling wild type hSSTR1 (poor internalization, 71% up-regulation). These results show that ligand-induced up-regulation of hSSTR1 occurs by a temperature-dependent active process of receptor recruitment from a pre-existing cytoplasmic pool to the plasma membrane. It does not require new protein synthesis or signal transduction, is sensitive to dephosphorylation events, and critically dependent on molecular signals in the receptor C-tail.

Differential regulation of somatostatin receptor types 1-5 in rat aorta after angioplasty

Treatment of restenosis after angioplasty with octapeptide somatostatin (SST) analogs has met with variable success. These analogs bind with high affinity to only two SST receptor (SSTR) subtypes (2 and 5), display moderate affinity for SSTR3, and low affinity for SSTR1 and 4. To optimize the vasculoprotective effect of SST, we have investigated the pattern of expression of all five SSTRs in rat thoracic aorta in the resting state and at 15 min, 3, 7, and 14 days after balloon endothelial denudation. SSTR1-5 were analyzed as mRNA by semiquantitative reverse transcriptase-polymerase chain reaction and as protein by immunocytochemistry. All five SSTRs were expressed in rat aorta both as mRNA and protein and displayed a time-dependent, subtype-selective response to endothelial denudation. mRNA for SSTR1 and 2 increased acutely (SSTR1 > SSTR2) on days 3 and 7, coincident with smooth muscle cell (SMC) proliferation, and declined to basal levels by day 14. SSTR3 and 4 displayed a different pattern with a delayed, more gradual increase in mRNA beginning at days 3-7 and continued to increase thereafter. SSTR5 mRNA was constitutively expressed at a low level and showed no change during the 2 wk postinjury period. By immunohistochemistry, SSTR1-5 antigens were localized predominantly in SMC that were present in the media or had migrated into the intima; antigen expression correlated with receptor mRNA expression. Notably, only SSTR1,3,4 were expressed in the intima: SSTR1 and 4 during the proliferative burst and SSTR3 and 4 after proliferation, when SMC migration into the intima continues. These results demonstrate dynamic changes in SSTR1-5 expression after vascular trauma localized to areas of vascular SMC migration and replication. In view of their early and prominent induction, SSTR1 may be the optimal subtype to target for inhibition of myointimal proliferation, and SSTR3 and 4 for migration and remodeling.

Subtype-selective expression of the five somatostatin receptors (hSSTR1-5) in human pancreatic islet cells: a quantitative double-label immunohistochemical analysis

We have developed a panel of rabbit polyclonal antipeptide antibodies against the five human somatostatin receptor subtypes (hSSTR1-5) and used them to analyze the pattern of expression of hSSTR1-5 in normal human islet cells by quantitative double-label confocal fluorescence immunocytochemistry. All five hSSTR subtypes were variably expressed in islets. The number of SSTR immunopositive cells showed a rank order of SSTR1 > SSTR5 > SSTR2 > SSTR3 > SSTR4. SSTR1 was strongly colocalized with insulin in all beta-cells. SSTR5 was also an abundant isotype, being colocalized in 87% of beta-cells. SSTR2 was found in 46% of beta-cells, whereas SSTR3 and SSTR4 were relatively poorly expressed. SSTR2 was strongly colocalized with glucagon in 89% of alpha-cells, whereas SSTR5 and SSTR1 colocalized with glucagon in 35 and 26% of alpha-cells, respectively. SSTR3 was detected in occasional alpha-cells, and SSTR4 was absent. SSTR5 was preferentially expressed in 75% of SST-positive cells and was the principal delta-cell SSTR subtype, whereas SSTR1-3 were colocalized in only a few delta-cells, and SSTR4 was absent. These studies reveal predominant expression of SSTR1, SSTR2, and SSTR5 in human islets. Beta-cells, alpha-cells, and delta-cells each express multiple SSTR isoforms, beta-cells being rich in SSTR1 and SSTR5, alpha-cells in SSTR2, and delta-cells in SSTR5. Although there is no absolute specificity of any SSTR for an islet cell type, SSTR1 is beta-cell selective, and SSTR2 is alpha-cell selective. SSTR5 is well expressed in beta-cells and delta-cells and moderately well expressed in alpha-cells, and thereby it lacks the islet cell selectivity displayed by SSTR1 and SSTR2. Subtype-selective SSTR expression in islet cells could be the basis for preferential insulin suppression by SSTR1-specific ligands and of glucagon inhibition by SSTR2-selective compounds.

Polymorphism in the 5' flanking region of the human somatostatin receptor subtype 5

The human somatostatin receptor subtype 5 (hSSTR5) gene has previously been cloned and localized to chromosome 16 p13.3. This region is evolutionarily conserved in all vertebrate genomes from the puffer fish (Fugu rubripes) to human, and also contains loci for genes associated with two common multisystemic disorders, adult polycystic kidney disease (PKD1) and tuberous sclerosis (TSC2). Analysis of the 5' flanking region of the hSSTR5 gene has revealed consensus sequences for a number of transcription factors as well as Alu-like repeat elements. In the present study, genomic DNA from 53 unrelated individuals was analysed by PCR and Southern blots probed with radiolabeled fragments generated from different segments of the hSSTR5 gene. We have identified two restriction fragment length polymorphisms (RFLP) with high heterozygosity values at the 5' flanking region of the hSSTR5 gene. These RFLP markers will be useful for determining the allelic loss of genetic material from this region. The observed polymorphism in the promoter region may affect the function of the hSSTR5 gene.

Expression of somatostatin receptor subtypes in human brain tumors

Expression of mRNA for the 5 somatostatin receptors (sst1-5) was characterized by Northern blot and RT-PCR analysis in 20 meningioma and 9 glioma samples. sst1 mRNA was detectable by Northern blots of poly-A+ RNA in meningiomas but not gliomas. In contrast, sst2 mRNA was readily detected by Northern blots of total RNA as a major 2.3 kb transcript and 2 minor 4.3 kb and 8 kb transcripts in all meningiomas and 6 out of 9 gliomas. Quantitation of the 2.3 kb sst2 mRNA showed that 15 out of 20 tumors expressed 1.3- to 33-fold higher levels than control normal human brain. Mean sst2 mRNA for the 20 meningioma samples was 978% that of normal brain. Three gliomas showed 7- to 14-fold higher sst2 mRNA than normal brain whereas the remaining samples displayed very low or undetectable levels. Immunocytochemistry of meningioma and glioma samples, with a sst2-specific antibody revealed immunoreactivity in tumor cells and peritumoral tissue, with prominent expression in blood vessels. mRNA for sst3,4,5 could not be detected by Northern blots in any of the tumors. RT-PCR analysis of meningiomas and gliomas revealed the following percent of tumors positive for a given sst mRNA: sst1 (86%), sst2 (100%), sst3 (60%), sst4 (58%), and sst5 (67%); 85% of tumors expressed 3 of the 5 subtypes. No correlation was found between the pattern of expression of sst mRNA and tumor type, location, and histology for either the meningiomas or gliomas. Our results show that meningiomas and gliomas are all positive for at least one sst subtype, the majority expressing multiple subtypes. sst2 is the most abundant isoform with a rich expression in both tumor and peritumoral tissue especially blood vessels.

Molecular genetics of inherited eye disorders

In the past 10 y, there have been considerable advances in the mapping, isolation, and characterization of many genes for important ocular conditions: retinitis pigmentosa, Norrie disease, Waardenburg syndrome, choroideremia, aniridia, retinoblastoma, and others. The candidate gene approach has now supplemented classical linkage studies and positional cloning in the investigation of ocular disorders. Developmentally expressed genes and animal models have provided insights as to the etiology of other disorders. With this knowledge at hand, genetic counselling for heritable eye diseases has been greatly improved.

Isolation and identification of a novel tandemly repeated DNA sequence in the centromeric region of human chromosome 8

EcoRI subclones, designated as 50E1 and 50E4, were independently obtained from a cosmid clone previously mapped to the centromeric region of human chromosome 8. Southern blot hybridization analyses suggested that both subclones contain repetitive DNA sequences different from the chromosome 8 specific alphoid DNA. DNA sequence analysis of the 704 bp insert of 50E1 and the 1,962 bp insert of 50E4 revealed that both inserts contained tandemly repeated units of approximately 220 bp. Fluorescence in situ hybridization studies confirmed these two subclones to be specifically located on the centromeric region of chromosome 8. A 220 bp consensus sequence, derived from nine monomeric repeats, showed no significant homology to alphoid consensus sequences or to other currently known human centromeric DNA sequence. Furthermore, no significant homology was found with any other DNA sequence deposited in the EMBL or GenBank databases, indicating that this chromosome 8 specific repetitive DNA sequence is novel. From slot blot experiments it was estimated that 0.013% of the human genome comprises 1,750 of these monomeric repeats, residing on the centromeric region of chromosome 8 in tandem array(s).

Interstitial localization of telomeric DNA sequences in the Indian muntjac chromosomes: further evidence for tandem chromosome fusions in the karyotypic evolution of the Asian muntjacs

The Indian muntjac is believed to have the lowest chromosome number in mammals (2n = 6 in females and 2n = 7 in males). It has been suggested that a series of tandem chromosome fusions from an ancestral Chinese muntjac-like species (2n = 46) may have occurred during the karyotypic evolution of the Indian muntjac. In an earlier study, hybridization signals generated by the Chinese muntjac centromeric heterochromatin DNA probe (C5) were found to be distributed interstitially in the chromosomes of the Indian muntjac, providing supportive evidence for the tandem chromosome fusion theory. In this study, the highly conserved human telomeric DNA sequence (TTAGGG)n was localized by fluorescence in situ hybridization (FISH) on the metaphase chromosomes of three Cervidae species: the Indian muntjac, Chinese muntjac, and woodland caribou. As expected, hybridization signals were observed at the termini of almost every chromosome in all three species. In addition, interstitial hybridization signals were detected in chromosomes 1 and 2 of the Indian muntjac. The observed interstitial telomeric signals appeared to correspond to specific interstitial centromeric heterochromatin sites. These interstitial telomeric signals could represent remnant DNA sequences from the ancestral species telomeres, further supporting the tandem chromosome fusion theory. Furthermore, these observations permit the elucidation of the chromosome sites where breakage and fusion most likely occurred during the restructuring of the ancestral Chinese muntjac-like chromosomes to form the present day Indian muntjac karyotype.

Localization of the human CYP17 gene (cytochrome P450(17 alpha)) to 10q24.3 by fluorescence in situ hybridization and simultaneous chromosome banding

The gene for human P450(17 alpha) (CYP17) was previously mapped to chromosome 10 through analysis of somatic cell hybrids. Using a modified procedure of fluorescence in situ hybridization, this gene has now been visualized on simultaneously banded chromosomes and localized to a specific subband of chromosome 10 at q24.3. This precise assignment may facilitate the understanding of the molecular basis of 17 alpha-hydroxylase/17,20-lyase deficiency and the evolution of the CYP superfamily of genes.

Mapping of 50 cosmid clones isolated from a flow-sorted human X chromosome library by fluorescence in situ hybridization

Fifty cosmids have been mapped to metaphase chromosomes by fluorescence in situ hybridization under conditions that suppress signals from repetitive DNA sequences. The cosmid clones were isolated from a flow-sorted human X chromosome library. Thirty-eight of the clones were localized to chromosome X and 12 to autosomes such as chromosomes 3, 7, 8, 14, and 17. Although most of the cosmids mapped to the X chromosome appeared to be scattered along both the short and long arms, 10 cosmids were localized to the centromeric region of the chromosome. Southern blot analysis revealed that only two of these clones hybridized to probe pXBR-1, which detects the DXZ1 locus. In addition, 4 out of 5 cosmids mapped on chromosome 8 also localized on the centromeric region. While localization of X-specific cosmids will facilitate the physical mapping of the human X chromosome, cosmids mapped to the centromeric regions of chromosomes X and 8 should be especially useful for studying the structure and organization of these regions.

New evidence for tandem chromosome fusions in the karyotypic evolution of Asian muntjacs

A clone of highly repetitive DNA, designated C5, was isolated from DNA of female Chinese muntjac cells. The nucleotide sequence of this clone is 80%-85% homologous to that of the satellite IA clone and other highly repetitive DNA clones previously obtained from the Indian muntjac. Using C5 as a probe for in situ hybridizations to chromosome preparations of cells of both the Chinese and Indian muntjacs, we were able to show that these repeated sequences occur in centromeric heterochromatin of the chromosomes of both Chinese and Indian muntjac species. More significantly, non-random clusters of hybridization signals were detected on the arms of chromosomes of the Indian muntjac. These latter hybridization sites are postulated to be regions of interstitial heterochromatin and could be the remnants of centromeric heterochromatin from ancestral Chinese muntjac chromosomes. Our observations provide new supportive evidence for the tandem chromosome fusion theory that has been proposed for the evolution of the Indian muntjac karyotype.

Chromosome aberrations and oncogene alterations in two new breast tumor cell lines

Two new breast tumor cell lines (UISO-BC-1 and UISO-BC-2) have been established from pleural effusions obtained from patients with confirmed diagnosis of breast cancer. Cytogenetic investigation shows several numerical and structural aberrations in both cell lines. Each cell line appears to have distinctive karyotypic aberrations. Although a common marker chromosome was not found in both cell lines, several breakpoints (i.e., 1q11, 3q11, 7p11, 9q11, and 13q11) were commonly involved in the marker chromosomes of both lines. Double minute (dmin) chromosomes were also observed in these two cell lines. Sixteen oncogene probes were used to study the oncogene amplification and overexpression; among these, only neu and c-myc probes detected multiple gene copies. A 10-fold amplification and a 20-fold overexpression of the neu were observed in the UISO-BC-1 line, whereas a threefold and a fivefold amplification of c-myc were found in UISO-BC-1 and UISO-BC-2, respectively. Moderately enhanced expression (sixfold) of c-myc was also observed in the UISO-BS-2 line. No gross rearrangement of these genes or aberrant RNAs was detected in these tumor cell lines.

Prenatal sexing and detection of ZFY gene sequences in sex chromosome disorders by polymerase chain reaction

Specific amplification of a DNA segment of the human ZFY gene by polymerase chain reaction (PCR) was carried out for detection of Y-chromosome specific sequences. When male DNA was used as template for amplification, a single and discrete 530 bp ethidium bromide staining band was observed in agarose gel. Female DNA produced no band. This technique was successfully used in prenatal sexing and for detecting ZFY DNA sequences in five XX males, an XY female, and a female patient with Turner syndrome having mosaicism involving a minute marker chromosome.

Determining the origins and the structural aberrations of small marker chromosomes in two cases of 45,X/46,X, + mar by use of chromosome-specific DNA probes

A 17-year-old girl (S.M.) and a 13-year-old girl (C.L.) both with Ullrich-Turner syndrome (UTS) were found to have 45,X/46,X, + mar mosaicism. The marker chromosomes in both patients were very small in size. In S.M. the marker chromosome was present in 80% of phytohemagglutinin-stimulated lymphocytes, 28% of skin fibroblasts, and 11-20% of gonadal fibroblasts. In C.L., the small marker chromosome was found in 50% of stimulated lymphocytes. S.M. is of normal height, but C.L. is short. Molecular hybridization with a number of Y-specific DNA probes demonstrated their presence in S.M. but absence in C.L. In situ hybridization with Y-specific and X-centromere-specific DNA probes confirmed the Y origin of the marker chromosome in S.M. and the X origin of the minute chromosome in C.L. Biotinylated centromere and telomere probes were also used for in situ hybridization to show the presence of centromeric and telomeric sequences in the Y-marker chromosome, suggesting that the deletion of this marker chromosome is interstitial.

Chromosome localization of two human serine protease genes to region 14q11.2----q12 by in situ hybridization

Two human serine protease genes have been cloned. One corresponds to CTLA1, the human equivalent of the mouse cytotoxic cell protease gene Ctla-1, and the other is novel. Both genes were localized to 14q11.2----q12 by in situ hybridization. This result confirms the assignment of human CTLA1 to 14q11.2----q12 and provides new mapping data for another human serine protease gene located in the same chromosome region.

Mapping of the goat beta-globin gene cluster to a region of chromosome 7 by in situ hybridization

We mapped the beta-globin gene cluster of the goat (Capra hircus) to a specific chromosomal region of the species, using in situ hybridization. The probe we used was a 1.2-kb Eco RI/Bam HI genomic DNA fragment that was 3H labeled to high specific activity by the random primer method. This DNA fragment contains part of the 5' flanking region and the first two exons of the epsilon IV gene of the goal beta-globin gene cluster. Our results show that this gene cluster is on chromosome 7 in the region of bands 33 to 35 based on BrdU G-banded chromosome preparations of this species.

Biochemical and physiochemical characterization of chromatin fractions with different degrees of solubility isolated from chicken erythrocyte nuclei

Chicken erythrocyte chromatin was prepared according to two different methods [Fulmer, A. W., & Bloomfield, V. A. (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 5968-5972; Ausio, J., Borochov, N., Seger, D., & Eisenberg, H. (1984) J. Mol. Biol. 177, 373-398] to give three main common fractions, according to its solubility (S) or insolubility (I) in 0.15 M NaCl buffers or to its further solubility in 0.25 mM ethylenediaminetetraacetic acid (E). From the biochemical point of view, all of them have been found to be undistinguishable. Analytical ultracentrifugation shows that all of these fractions can reversibly undergo the transition from the low to the higher order structure, through a nearly identical way of folding. Thermal denaturation profiles yielded three transitions having the same Tm's for the three fractions. The percentage of DNA melting in the first transition decreased in the order S greater than I greater than E, and the amount in the second transition increased in the same order. Together with the different solubility of these fractions in the presence of divalent ions, these results indicate that in the three fractions of chromatin studied, the amount of linker DNA bound to the nucleosome varied.

The effect of a high mobility group protein (HMG 17) on the structure of acetylated and control core HeLa cell chromatin

The effect of binding a high mobility group protein (HMG 17) on the stability and conformation of acetylated and control HeLa high molecular weight core chromatin (stripped of H1 and non-histone chromosomal proteins) was studied by circular dichroism and thermal-denaturation measurements. Previously it had been shown that conformational differences exist between native whole chromatin derived from butyrate-treated (acetylated) and control HeLa cells and that these conformational differences disappear by removing H1 and non-histone chromosomal proteins ( Reczek , P.R., Weissman , D., Huvos , P.E. and Fasman, G.D. (1982) Biochemistry 21, 993-1002). The circular dichroism spectra and the thermal denaturation profiles of control and acetylated core chromatin were found to be similar. The circular dichroism properties of HMG 17 reconstituted highly acetylated and control core chromatin indicated the same alteration of chromatin structure at low ionic strength (1 mM sodium phosphate/0.25 mM EDTA, pH 7.0). The magnitudes of the decrease in ellipticity were proportional to the amount of HMG 17 bound and were found to be the same for both the acetylated and control core chromatin. Thermal denaturation profiles confirmed this change in structure induced by HMG 17 on control and highly acetylated core chromatin. The thermal denaturation profiles, which were resolved into three component transitions, exhibited a shifting of hyperchromicity from the lower melting transitions to the higher melting transitions, with a concomitant rise in Tm, on HMG 17 binding to both control and acetylated chromatin. The natures of the interactions of HMG 17 at higher ionic strength (50 mM NaCl/0.25 mM EDTA/1 mM sodium phosphate, pH 7.0) with acetylated and control core chromatin were slightly different, as measured by circular dichroism; however, a decrease in ellipticity was observed for both samples upon binding of HMG 17. These observations suggest that acetylation coupled with HMG 17 binding to core chromatin does not loosen chromatin structure. HMG 17 binding to control and acetylated core chromatin produces an overall stabilization and compaction of chromatin structure.

A conformational study of the binding of a high mobility group protein with chromatin

The nature of the binding of a high mobility group protein (HMG 17) to native and H1-H5-depleted chicken erythrocyte chromatin was studied, as a function of ionic strength, using circular dichroism and thermal denaturation techniques. The circular dichroism properties of the HMG 17-reconstituted whole chromatin and H1-H5-depleted chromatin demonstrated that a condensation of chromatin structure occurred upon HMG 17 binding at low ionic strength (1 mM Na phosphate, 0.25 mM EDTA, pH 7.0). Thermal denaturation profiles confirmed this change in the structure of chromatin induced by HMG 17. Thermal denaturation profiles were resolved into three-component transitions. In general, a shift in the temperature of maximum dh/dT for each transition (Tm) was observed for all transitions upon HMG 17 binding. DNA melting in the first transition, originating from linker regions of whole chromatin, was nearly totally depleted and was distributed mainly into the highest melting transition. The same trends were also observed in H1-H5-depleted chromatin. These results indicate that the binding sites of HMG 17 are situated in the linker regions immediately adjacent to the core. The nature of the interaction of HMG 17 at higher ionic strength (50 mM NaCl, 1 mM Na phosphate, 0.25 mM EDTA, pH 7.0) with whole chromatin and H1-H5-depleted chromatin was found to be different but a decrease in [theta] values was found in both chromatins. These observations suggest that HMG 17 does not loosen chromatin structure but produces an overall stabilization and condensation of structure. The implications of these results to the currently accepted models of transcriptionally active chromatin are discussed.

Interaction of rhodium(III) with DNA

The nature of interaction of Rh(III) with DNA was studied using viscometry and ultraviolet, visible and infrared spectroscopy. The rate of interaction was found to be very slow at room temperature taking several days for completion. The time needed to attain equilibrium is dependent on the concentrations of metal ion, higher the concentration shorter the period required for equilibration. Visible spectra of Rh(III) were found to alter considerably in the presence of DNA. An increase in absorbance and a red shift were observed in the ultra violet spectra of DNA in the presence of Rh(III). The specific viscosity of DNA solution was found to decrease asymptotically with time and concentrations of metal ion. The melting temperature of DNA was found to increase at lower metal ion concentrations, whereas at higher values a decrease was obtained. At still higher metal ion concentrations (metal ion/DNA-P greater than 3) a 'nonmeltable state' of DNA was observed. These results seem to indicate that Rh(III) binds both with the phosphate and the bases of the DNA.