Microalgae harvesting using flocculation and dissolved air flotation: Selecting the right vessel for lab-scale experiments.

Flocculation combined with dissolved air flotation (DAF) is a promising technology for harvesting microalgae; therefore, optimisation of flocculant-DAF operating conditions are frequently explored in laboratory experiments. DAF systems have jars of differing volumes, height to diameter ratios, shapes and materials used to manufacture the jars; thus, the harvesting efficiency (η) may differ between these jars. The aim was to systematically compare η between different types of benchtop DAF jars. Evaluation of 30 different types of DAF jars revealed that η was not influenced by the volume of the jars, but was impacted by the height to diameter ratio, with optimal η at a ratio ranging between 1.6 and 2.05. There was no difference in η between cylindrical and cuboid jars, but jars made of hydrophobic (polypropylene) plastic resulted in a lower η. Overall, these results are useful to guide the design of lab-scale DAF microalgae harvesting experiments.

Disruption of the ATE1 and SLC12A1 Genes by Balanced Translocation in a Boy with Non-Syndromic Hearing Loss.

We report on a boy with non-syndromic hearing loss and an apparently balanced translocation t(10;15)(q26.13;q21.1). The same translocation was found in the normally hearing brother, father and paternal grandfather; however, this does not exclude its involvement in disease pathogenesis, for example, by unmasking a second mutation. Breakpoint analysis via FISH with BAC clones and long-range PCR products revealed a disruption of the arginyltransferase 1 (ATE1) gene on translocation chromosome 10 and the solute carrier family 12, member 1 gene (SLC12A1) on translocation chromosome 15. SNP array analysis revealed neither loss nor gain of chromosomal regions in the affected child, and a targeted gene enrichment panel consisting of 130 known deafness genes was negative for pathogenic mutations. The expression patterns in zebrafish and humans did not provide evidence for ear-specific functions of the ATE1 and SLC12A1 genes. Sanger sequencing of the 2 genes in the boy and 180 GJB2 mutation-negative hearing-impaired individuals did not detect homozygous or compound heterozygous pathogenic mutations. Our study demonstrates the many difficulties in unraveling the molecular causes of a heterogeneous phenotype. We cannot directly implicate disruption of ATE1 and/or SLC12A1 to the abnormal hearing phenotype; however, mutations in these genes may have a role in polygenic or multifactorial forms of hearing impairment. On the other hand, it is conceivable that our patient carries a disease-causing mutation in a so far unidentified deafness gene. Evidently, disruption of ATE1 and/or SLC12A1 gene function alone does not have adverse effects.

Prenatal diagnosis of a recombinant chromosome 7 resulting in trisomy 7q11.22 --> qter.

Prenatal diagnosis of trisomy 7 is complex due to only a few reported cases. We report here on a stillborn boy with very large duplication of 7q11.22 --> qter, encompassing almost the entire long arm of chromosome 7. Ultrasound, fetal and parental chromosome banding, fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (CGH) analyses were performed. Sonographic findings included growth retardation, micrognathia, ventricular septal defect (VSD), aortic coarctation, bradyarrhythmia, pericardial effusion, bilateral hydronephrosis, infravesical obstruction, and cerebellar hypoplasia. Chromosome analysis after cordocentesis at 23 weeks of gestation revealed an abnormal male karyotype with 46 chromosomes and a derivative chromosome 7 with a very large duplication of the long arm, 46,XY,der(7)(qter --> q11.2::p22 --> qter). The mother was found to carry an apparently balanced pericentric inversion, 46,XX,inv(7)(p22q11.2). Thus, the recombinant chromosome 7 [rec(7)dup(7q)inv(7)(p22.3q11.22)mat] of the fetus must have arisen through meiotic crossing-over between the inverted chromosome and the normal chromosome 7 in the maternal germline. FISH and array CGH results confirmed the recombinant chromosome 7 in the fetus and indicated a loss of 1.9 Mb at chromosome 7pter --> p22.3 (pter to 1,948,072 bp), and a gain of 87.04 Mb at chromosome 7q11.22 --> qter (71,760,154 bp to qter). The rare syndrome of almost complete trisomy 7q may be suspected in cases of growth retardation, cerebellar hypoplasia, micrognathia, aortic coarctation and VSD and hydronephrosis. Invasive prenatal diagnosis must be offered to the parents.

Haploinsufficiency of 16.4 Mb from chromosome 22pter-q11.21 in a girl with unilateral conductive hearing loss.

We present the postnatal diagnosis of a de novo der(18)t(18;22)(p11.32;q11.21)pat, resulting in an unbalanced 45,XX,der (18)t(18;22) karyotype in a girl with conductive hearing loss on the left and ptosis of the right upper eye-lid. Unilateral ptosis was also observed in the patient's 2 years and 8 months younger sister, who grows noticeably faster and appears to be a much quicker learner. After speech therapy the patient was eventually placed in normal school. The haploinsufficient 16.4-Mb region on chromosome 22pter-->q11.21 contains 10 genes as well as many predicted genes, pseudogenes, and retrotransposed sequences with unknown functions. This observation may prove useful for prenatal diagnosis and genetic counselling of chromosome 22q11.1 gains and losses.

Epimutation at human chromosome 14q32.2 in a boy with a upd(14)mat-like clinical phenotype.

Recently, three reports described deletions and epimutations affecting the imprinted region at chromosome 14q32.2 in individuals with a phenotype typical for maternal uniparental disomy of chromosome 14 [upd(14)mat]. In this study, we describe another patient with upd(14)mat-like phenotype including low birth weight, neonatal feeding problems, muscular hypotonia, motor and developmental delay, small hands and feet, and truncal obesity. Conventional cytogenetic analyses, fluorescence in situ hybridization subtelomere screening, multiplex ligation-dependent probe amplification analysis of common microdeletion and microduplication syndromes, and methylation analysis of SNRPN all gave normal results. Methylation analysis at 14q32.2 revealed a gross hypomethylation of the differentially methylated regions (intergenic DMR and MEG3-DMR). Further molecular studies excluded full or segmental upd(14)mat as well as a microdeletion within this region. Evidently, the upd(14)mat-like clinical phenotype is caused by an epimutation at 14q32.2. The clinical and molecular features of this novel case are discussed with respect to the recently published cases.

Boy with seizures (West syndrome) and distal 7q duplication syndrome due to an unbalanced 7q;9p translocation.

We report a 15 month old boy with prominent metopic suture, epicanthal folds, strabismus, low-set ears, microretrognathia, large anterior fontanel, bilateral simian creases, muscular hypotonia, and severe psychomotor retardation. He also had West syndrome. An electroencephalogram showed hypsarrythmia, and cranial MR indicated a myelinisation delay. Standard karyotyping showed additional material on one chromosome 9p. Using FISH, a terminal 7q duplication spanning 26 Mb in size and a terminal 9p deletion sized (at least) 9.1 Mb were identified. The father had a karyotype of t(7;9)(q33;p23) and the mother's karyotype was normal. The boy presented typical facial features of the distal 7q duplication syndrome but no genital anomalies attributable to his distal 9p deletion. We assume that the severe epilepsy is likely due to the trisomy 7q.

pp32/PHAPI determines the apoptosis response of non-small-cell lung cancer.

During malignant transformation, cancer cells have to evade cell-intrinsic tumor suppressor mechanisms including apoptosis, thus acquiring a phenotype that is relatively resistant to clinically applied anticancer therapies. Molecular characterization of apoptotic signal transduction defects may help to identify prognostic markers and to develop novel therapeutic strategies. To this end we have undertaken functional analyses of drug-induced apoptosis in human non-small cell-lung cancer (NSCLC) cells. We found that primary drug resistance correlated with defects in apoptosome-dependent caspase activation in vitro. While cytochrome c-induced apoptosome formation was maintained, the subsequent activation of caspase-9 and -3 was abolished in resistant NSCLC. The addition of recombinant pp32/putative human HLA class II-associated protein (pp32/PHAPI), described as a putative tumor suppressor in prostate cancer, successfully restored defective cytochrome c-induced caspase activation in vitro. Conditional expression of pp32/PHAPI sensitized NSCLC cells to apoptosis in vitro and in a murine tumor model in vivo. Immunohistochemical analyses of tumor samples from NSCLC patients revealed that the expression of pp32/PHAPI correlated with an improved outcome following chemotherapy. These results identify pp32/PHAPI as regulator of the apoptosis response of cancer cells in vitro and in vivo, and as a predictor of survival following chemotherapy for advanced NSCLC.

Two independent chromosomal rearrangements, a very small (550 kb) duplication of the 7q subtelomeric region and an atypical 17q11.2 (NF1) microdeletion, in a girl with neurofibromatosis.

Most patients with neurofibromatosis (NF1) are endowed with heterozygous mutations in the NF1 gene. Approximately 5% show an interstitial deletion of chromosome 17q11.2 (including NF1) and in most cases also a more severe phenotype. Here we report on a 7-year-old girl with classical NF1 signs, and in addition mild overgrowth (97th percentile), relatively low OFC (10th-25th percentile), facial dysmorphy, hoarse voice, and developmental delay. FISH analysis revealed a 17q11.2 microdeletion as well as an unbalanced 7p;13q translocation leading to trisomy of the 7q36.3 subtelomeric region. The patient's mother and grandmother who were phenotypically normal carried the same unbalanced translocation. The 17q11.2 microdeletion had arisen de novo. Array comparative genomic hybridization (CGH) demonstrated gain of a 550-kb segment from 7qter and loss of 2.5 Mb from 17q11.2 (an atypical NF1 microdeletion). We conclude that the patient's phenotype is caused by the atypical NF1 deletion, whereas 7q36.3 trisomy represents a subtelomeric copy number variation without phenotypic consequences. To our knowledge this is the first report that a duplication of the subtelomeric region of chromosome 7q containing functional genes (FAM62B, WDR60, and VIPR2) can be tolerated without phenotypic consequences. The 17q11.2 microdeletion (containing nine more genes than the common NF1 microdeletions) and the 7qter duplication were not accompanied by unexpected clinical features. Most likely the 7qter trisomy and the 17q11.2 microdeletion coincide by chance in our patient.

Autologous transplantation of in vivo purged PBSC in CML: comparison of FISH, cytogenetics, and PCR detection of Philadelphia chromosome in leukapheresis products.

To determine the effectiveness of different methods for the detection of tumor cell contamination of collected peripheral stem cells, we performed a study on 39 chronic myelogenous leukemia (CML) patients who were consecutively treated at our department. Analyses of tumor cell contamination by fluorescence in situ hybridization (FISH), conventional cytogenetics, and polymerase chain reaction (PCR) showed marked differences in the percentage of evaluable results: Quantitative analysis of tumor cell contamination was feasible in 60 of 105 (57%) samples evaluated with the use of conventional cytogenetic analysis and in 105 of 107 (98%) samples analyzed by FISH. PCR was evaluable in all 85 samples tested (100%). Both methods were shown to be adequate overall in determining the number of BCR-ABL positive cells, although cytogenetics tended to produce slightly higher percentages. Based on these results, we conclude that FISH performed on leukapheresis products is a rapid and reliable method for assessing the quality of these products and should be used for routine evaluation of tumor cell contamination of CML stem cell products.