Correlation between phenotypic expression of de novo marker chromosomes and genomic organization using replicational banding

It has been suggested that actively expressed genes are primarily located in early replicating bands. This hypothesis is supported by cytogenetic and pregnancy outcome data from four consecutive cases of prenatally detected de novo marker chromosomes. Two fetuses with major anomalies had large early replicating bands, while the marker in a third phenotypically normal fetus was late replicating. In the fourth case, a ring marker chromosome had only a small early replicating region. Pregnancy termination was elected. While no structural malformations were apparent, potential intellectual function in this case remains unresolved. An understanding of the relationship between genomic organization and chromosome banding is critical in counseling for prenatally detected de novo marker chromosomes. Replicational banding is particularly helpful in recognizing genes that may be actively expressed and result in developmental abnormality.     

An improved method of direct chromosome preparation from chorionic villus and high resolution banding technique

The trophoblast was dissociated from the underlying mesenchymal layer either with acetic acid after short-term prefixation or with mechanical power after fixation twice. The colcemid treatment time was shorted to 16 min and trypsin solution of low pH (6.2) was used for banding. By these steps, the quality of chromosome banding was greatly improved and complete standard chromosome diagnoses were made in 24 of 24 cases. With the modified technique, high resolution banding chromosomes were consistently obtained after short-term incubation.     

Outcome of cases of de novo structural rearrangements diagnosed at amniocentesis

The frequency of de novo rearrangements at amniocentesis was determined in 76952 prenatal diagnoses from centres in the United States. Rates for balanced rearrangements are slightly greater than rates previously reported in the newborn, possibly because banding studies were not used in the latter. Rates for unbalanced rearrangements are considerably higher in the amniocentesis data not only because banding was used but also because a substantial loss of abnormal conceptions is to be expected between amniocentesis and birth. The higher frequency of cases with supernumerary markers at amniocentesis is unexplained. A review of 66 apparently balanced de novo rearrangements found at amniocentesis revealed evidence of abnormality in five; in four of these the abnormality was noted in the abortus. The number of cases observed is still too small to rule out a risk of abnormality no greater than the usual rate of abnormalities at birth. Abnormalities were detected in 6 of 10 cases with unbalanced de novo rearrangements. In 33 cases of non-familial supernumerary chromosomes 6 (18.2 per cent) showed abnormality. Non-satellited markers appeared to have a higher rate of abnormality than satellited markers but the difference is not statistically significant. Further studies and improved follow-up of de NOVO cases diagnosed at amniocentesis are required.     

Prenatal diagnosis of a de novo unbalanced translocation (4p + ) following in vitro fertilization

We report herein a de novo unbalanced chromosome translocation in a fetus resulting from in vitro fertilization technology. Prenatal diagnostic analysis of an amniotic fluid revealed a 46,XX,4p+ karyotype. The origin of the extra material on the short arm of chromosome 4 could not be identified by a variety of banding techniques. However, examination of fetal parts did reveal some dysmorphic features.     

Distal partial trisomy 1q: report of two cases and a review of the literature

We report on two cases with partial trisomy 1q syndrome. One case was a mid-trimester fetus with multiple malformations that was prenatally diagnosed with a de novo distal partial trisomy 1q. Prenatal ultrasound at 24th gestational week demonstrated the presence of cleft lip and palate, increased biparietal diameter and decreased abdominal circumference. Cytogenetic analysis (GTG banding) and subsequent fluorescence in situ hybridization (FISH) using whole chromosome paint 1 and multicolor banding (MCB) demonstrated an aberrant karyotype 46,XY,dup(1)(q31q43∼44). The second case was a newborn male infant with multiple congenital malformations. He had a derivative chromosome 18 as a result of a maternal insertion involving chromosomes 1 and 18. Further analyses including MCB showed his karyotype as 46,XY,ins(18;1)(q22;q23q31.1∼32). The present cases and a review of the literature suggest that partial trisomy of the long arm of chromosome 1 is a distinct clinical entity. Copyright © 2007 John Wiley & Sons, Ltd.     

Routine cytogenetic prenatal diagnosis using dynamic banding (RBG-GBG): A highly reproducible method for amniocytes,fetal cord blood,and chorionic villus investigations

Dynamic banding (RBG-GBG) using pulse 5-bromodeoxyuridine (5-BrdU) incorporation during part of the last S-phase before harvesting has been used in prenatal investigations. This method has already been routinely applied in 1344 cytogenetic investigations. GBG and RBG bandings produced almost identical patterns to classical G- and R-banding methods except for heterochromatic portions and some euchromatic segments. Nevertheless, these discordances may be somewhat helpful for cytogenetic diagnosis (i.e., X numerical abnormalities). The results showed particularly good contrast and staining; 5-BrdU incorporation did not prevent additional staining. Likewise, previous RBG or GBG disclosure allowed further chromosomal identification with C-banding or nucleolar organizer staining. Simplicity and reproducibility were very helpful in cases with a low mitotic index. 5-BrdU had no significant effect on in-vitro damage because only 0.31 per cent of cells were affected; so, we believe that dynamic banding should be used more extensively in cytogenetic investigations. Moreover, the staining and contrast qualities were very suitable for automatic methods of analysis now in use: i.e., metaphase finding and computer-assisted karyogram creation.     

Prenatal diagnosis of a familial complex chromosomal rearrangement involving chromosomes 5, 10, 16 and 18

We report one case of a familial complex chromosomal rearrangement (CCR) involving four different chromosomes 5, 10, 16 and 18. The CCR was detected prenatally at 20 weeks' gestation because of advanced maternal age and history of recurrent miscarriages. Cytogenetic analysis of cultured amniotic fluid cells with GTG banding showed a 46,XX,t(5;16;10;18)(q13;q22;q11.2;q21) karyotype. Parental cytogenetic study revealed that the mother has the same CCR. RBG banding, high-resolution banding and fluorescence in situ hybridization (FISH) were used to characterize further and confirm the conventional banding data. No physical abnormalities were shown in the targeted fetal ultrasonography examination. The parents decided to continue the pregnancy. The child is now 2 years old and has neither congenital anomalies nor evidence of delayed psychomotor development. The fetal targeted ultrasound and FISH analysis helped us reassure fetal status. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal foetal diagnosis of partial trisomy 3q and monosomy 13p due to a maternal balanced rearrangement

The authors describe a case of a male foetus whose ultrasound at 20 weeks' gestation revealed cystic hygroma, cleft lip and ventricular septal defect. Amniotic fluid cytogenetics using GTG banding showed a 46,XY,der(13)t(3;13)(q12;p11.1) rearrangement, and fluorescence in situ hybridization (FISH) delineated the relevant breakpoints. Familial studies identified a maternal balanced translocation involving chromosomes 3 and 13. The post-mortem examination confirmed the prenatal ultrasound findings. Copyright © 2005 John Wiley & Sons, Ltd.     

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures is described. The technique is based upon several key steps including: (1) reduced colcemid concentration, (2) reduced exposure to trypsin-EDTA, and (3) maintaining cells in single suspension by adjusting cell concentration appropriately. Chromosomes with banding resolution up ot 800 bands per haploid set can be routinely produced. The described methodology is particularly useful in defining and establishing the clinical significance of subtle structural aberrations.     

Prenatal investigation of a 45,X/46,X,r(?) karyotype in amniocytes using fluorescence in situ hybridization with an X-centromeric probe

The karyotype of cultured amniotic fluid cells obtained on the indication of advanced maternal age was shown to be a mosaic 45,X/46,X,r(?). The small size and banding pattern made it difficult to determine whether the ring was derived from and X or a Y chromosome, or even from an autosome. By using an X-centromeric probe and fluorescence in situ hybridization (FISH), we demonstrated the ring to have an X centromere. Thus, a more complete genetic counselling was possible. This confirms the usefulness of FISH in identifying and characterizing this and other chromosome rearrangements in prenatal diagnosis.     

A pipette method for rapid karyotyping in prenatal diagnosis

The 'pipette method' is introduced as a method of prenatal diagnosis which is in competition with the 'in situ' and the 'trypsinization' technique. It is sufficiently standardized for routine diagnosis and the banding techniques currently used in prenatal diagnosis (G, Q, C-banding and NOR) have been adapted for it. In 180 cases from 27 different centres, the 'pipette method' was employed for chromosomal harvesting in order to save time. An average of 6·6 days was taken to achieve a result. There was a pathological karyotype in 28 cases (16·1 per cent) and this high proportion can be related to cases where ultrasound scan has led to a diagnosis of 'suspected chromosomal abnormality'. This technique is also of use in advanced stages of pregnancy. The early recognition of the fetal karyotype can contribute to the future management of the pregnancy. The 'pipette method' can also be used in chromosomal harvesting of tumour cells and fibroblast cultures.     

Analysis of bacterial community in bulking sludge using culture-dependent and -independent approaches

Combination of 16S rRNA gene clone library and cultivation for assessing of bacterial diversity of the microflora in bulking sludge was evaluated in the study.     

Synchronization of amniotic fluid cells for high resolution cytogenetics

A high resolution technique was applied to amniotic fluid cells by synchronization. After inoculation, the cells were incubated for 30 h in the presence of either thymidine or 5-bromodeoxyuridine (BrdU). After removal of the blocking agent and addition of a low concentration of thymidine, the cells were incubated for another 6 1/2–7 h, then harvested in prometaphase without colcemid. This technique gives a mitotic index of 3·7 per cent after thymidine synchronization and of 3·2 per cent after BrdU synchronization, and more than half of the mitoses were in the earlier phases with the chromosomes showing more than 550 bands per haploid set. GBG, GTG, and RHG prometaphases are presented. Precise high-resolution banding of chromosomes of amniotic fluid cells can increase diagnostic accuracy.     

Prenatal diagnosis of a fetus with pure partial trisomy 1q32-44 due to a familial balanced rearrangement

We diagnosed a pure partial trisomy of the long arm of chromosome 1 in a fetus with multiple malformations detected prenatally. The father was a carrier of a balanced rearrangement involving 46,XY,inv(1)(qter→p36::q32→qter::p36→q32). The fetus had preaxial polydactyly, low-set ears, macrocephaly, a prominent forehead, a broad and flat nasal bridge, a small mouth, an arched palate, micrognathia and unilateral renal agenesis. The couple had previously an infant with the same phenotypic abnormalities. The aberration was initially detected on amniocentesis with GTG banding and was confirmed by fluorescence in situ hybridization (FISH). Our case and other published pure trisomy 1q32-44 cases showed similarities, which allowed the further delineation of the trisomy 1q syndrome. Copyright © 2002 John Wiley & Sons, Ltd.     

Preparation of high resolution chromosomes from amniotic fluid cells

A relatively simple method of obtaining high resolution chromosomes from amniotic fluid cells is described. The elongated chromosomes are achieved by adding ethidium bromide (5μg/ml) to the culture 4 1/2 hours before harvesting and the high resolution banding can be produced by usual banding procedures.     

A culture vessel for amniotic fluid cells allowing faster preparation of chromosome slides

A new culture vessel for amniotic fluid culture is presented (flaskette). It consists of a microscope slide, on top of which a culture chamber is mounted. Amniotic fluid cell cultures using in situ technique in the flaskette were compared to subcultured samples in ordinary (Falcon) tissue culture bottles. Working time was reduced by using this new culture vessel because of a very simple harvest procedure allowing simultaneous harvest of 15 samples. The interval between amniocentesis and harvest was shorter for the in situ technique than for the subcultivation technique. The frequency of aneuploidy in individual metaphases was higher with the subcultivation technique. while there was no difference in the frequency of structural anomalies.     

Early genetic amniocentesis—4 years' experience

Four hundred and thirty early amniocenteses (EAC) from 10 to 14 weeks' gestation were compared with 300 routine amniocenteses (RAC) from 15 weeks' gestation (control A) and 733 routine amniocenteses from 16 to 18 weeks' gestation (control B) with regard to success rates, various growth parameters, and cytogenetic results. Using both in situ and trypsiniz-ation techniques, the success rate was 99·8 per cent for EAC versus 100 per cent for RAC. The average turn-around time for establishing a diagnosis was 8·4 days in EAC versus 8·3 days in 15 weeks' specimens (n.s.) and 7·7 days in 16 to 18 weeks' specimens (p ≦ 0·0001) for the last 200 samples. The banding quality of early specimens compared favourably with that of controls (both 500–550 bphs) and was much better than that in long-term cultured chorionic villus sampling (CVS) (350–400 bphs). For level I and level II mosaicism, no statistically significant differences were noted between EAC and control group A. Comparing EAC with control group B, a significant increase in the number of numerical and structural single cell aberrations was observed (p ≦ 0·025 and p ≦ 0·001, respectively), whereas for multiple cell aberrations only the increase in numerical aberrations was statistically significant (p ≦ 0·001) (x²-test). Clinical problems arising from the detection of mosaicism were solved in all cases by investigating parallel cultures. It is concluded that early amniocentesis is a reliable procedure which permits prenatal diagnosis of numerical and structural chromosome aberrations to a high standard.     

Chorionic villus culture for first trimester diagnosis of chromosome defects: Evaluation by two london centres

The maceration technique for the culture of chorionic villi has been applied by St Mary's Hospital and King's College Hospital, to a total of 225 villus aspirates of which 100 were from diagnostic cases. Two hundred and eighteen (96·8 per cent) of these were successfully karyotyped, and chromosome abnormalities were detected in 15 cases. Of the cases with a normal karyotype, 113 were male and 90 were female. Sixty-nine (77 per cent) of the female cultures were demonstrated to be fetal and a further two of these may be verified at delivery. The use of Chang medium was found to accelerate cell growth thereby reducing the interval between sampling and reporting to less than 2 weeks. An unlimited quantity of metaphase spreads was obtained suitable for the application of routine banding techniques, and comparable to those obtained from amniotic fluid culture. Experience with diagnostic cases reinforced our view that culture should always back up direct analysis and this is discussed with particular reference to the occurrence of mosaicism in the trophoblast.     

A familial Xp+ chromosome detected during fetal karyotyping,which is associated with short stature in four generations of a Turkish family

The short-stature homeobox-containing gene (SHOX) on chromosome Xp22.3 was recently identified as an important determinant of the stature phenotype. Deletions of the SHOX gene, some of them due to structural chromosome abnormalities, have been described in patients with idiopathic short stature and Leri-Weill syndrome. Additionally, haploinsufficiency of SHOX is a main cause for short stature seen in patients with Turner syndrome. Here we report an unusual X-chromosome abnormality, which was detected during a fetal karyotyping performed because of a previous child with Down syndrome. GTG banding demonstrated an extra chromosome segment on the terminal part of the short arm of chromosome X in the index case (karyotype: 46,X,Xp+). The same chromosomal abnormality was found in the mother and the maternal grandmother. All carriers of this chromosomal abnormality presented with short stature but no other associated symptoms. Whole chromosome painting of X revealed a homogeneous painting of the abnormal X chromosome indicating that no other chromosome was involved. Additional FISH studies with probe DXS1140 (Kallmann probe at Xp22.3), Quint-Essential X-Specific DNA (DMD probe at Xp21.2), XIST (at Xq13.2), and Tel Xq/Yq were performed, and no abnormality was observed in the intensities or the localizations of the probes signals. However, applying a specific SHOX gene probe (derived from cosmid LLNONO3M34F5) showed a loss of signal on the derivative X chromosome. Our results show that the Xp+ generation led to a deletion of the complete SHOX gene and caused short stature in the presented family. Copyright © 2003 John Wiley & Sons, Ltd.     

Degradation of pyrene by immobilized microorganisms in saline-alkaline soil

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB+MF was increased by 161.7% (P < 0.05), 60.1% (P < 0.05) and 59.6% (P < 0.05) after 30 days, respectively, when compared with free F2, MF and MB+MF. Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline-alkaline soil, as the interspace of the carrier material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAH-degradation ability in saline-alkaline soil.