Cytotaxonomy of Dipetalogaster maxima Uhler, 1894 (Hemiptera, Reduviidae, Triatominae)

The Triatomini tribe consists of ten genera and is regarded as one of the most important tribes from epidemiological point of view. The genus Dipetalogaster Usinger, 1939 is composed only by the species Dipetalogaster maxima Uhler, 1894. This triatomine is exclusive of the Mexico and is a potential vector for Chagas disease. Besides the epidemiological importance, the insects of the Triatominae subfamily are important biological models for cytogenetic studies. Therefore, in order to contribute to the knowledge on the reproductive biology and assist in citotaxonomy of D. maxima, this study aimed to describe spermatogenesis, as well as confirm the karyotype and heterochromatic patterns of this Mexican triatomine species. The seminiferous tubules were torn, fixed to a cover slip and underwent the cytogenetic technique of Lacto-acetic orcein and C-banding. Through the cytogenetics analysis of testicular material D. maxima it was possible to confirm the karyotype (2n = 22), describe the stages of spermatogenesis and characterize the heterochromatic pattern (restricted to sex chromosome Y) of the species. D. maxima showed the same arrangement of heterochromatin described for Triatoma lecticularia (Stål, 1859) (a species that occur in United States of American and Mexico and is phylogenetically related with D. maxima), highlighting the importance of this analysis as an optimization tool to explore phylogenetic correlations.

The Importance of Classical and Molecular Cytogenetics in the Diagnosis of Microdeletions Microduplications Syndromes

Microdeletions and microduplications syndromes are a well defined group of disorders characterized by loss/ addition of less than 5 Mb of genetic material undetectable by simple karyotype and a particular phenotype. Our study presents the results of investigations of classical and molecular cytogenetic (FISH, Fluorescence in situ Hibridization) in 70 children showing different phenotypic manifestations, such as multiple congenital anomalies, dysmorphic appearance, mental retardation, obesity. After performing classical cytogenetic technique of the 70 cases, in four girls there were diagnosed two visible structural chromosomal abnormalities: DiGeorge syndrome, Distal 18q Deletion syndrome, 15q Duplication syndrome, izocromosome Xq and one boy with 11q24-qter deletion and 38 numerical aberrations were identified: 33 cases of trisomy 21, two cases of monosomy X, two cases of poly Y syndrome and one double aneuploidy, trisomy 21 and poly Y. Using FISH (Fluorescence in situ Hibridization) technique in all the 32 cases, another 5 cases were diagnosed with Prader-Willi syndrome, one with the following: Angelman syndrome, Williams syndrome and 15q Duplication Syndrome, two DiGeorge syndrome, one Jacobsen syndrome, 11q 23-qter deletion and one double aneuploidy. In our study, the efficacy of the classical cytogenetic technique in confirmation of the cases suspected by chromosome abnormality was 61.4% and the FISH technique, was 37,5%.In our study, using both methods of diagnosis, we obtained confirmation of the genetic etiology in only 72.85% of the cases.

Multiplex ligation dependent probe amplification - A useful, fast and cost-effective method for identification of small supernumerary marker chromosome in children with developmental delay and congenital heart defect

Small supernumerary marker chromosome (sSMC) is a rare chromosomal abnormality and is detected in about 0.3% in cases with multiple congenital anomalies (MCA) and/or developmental delay. Different techniques for investigation of cases with MCA and/or developmental delay are available ranging from karyotyping to molecular cytogenetic technique and ultimately multiplex ligation dependent probe amplification (MLPA). Here we present a patient with multiple congenital anomalies for which classical cytogenetic technique was used as a first step in diagnosis and the results being confirmed by MLPA. The karyotype disclosed a sSMC considered to be a fragment of chromosome 22. The MLPA analysis using SALSA MLPA probemix P064-C2 Microdeletion Syndromes-1B confirmed the karyotype results, and according to the manufacturer’s recommendation we performed another confirmation analysis with MLPA probemix P311-B1 Congenital Heart Disease and MLPA probemix P250-B2 DiGeorge. We also suspected an Emanuel syndrome and performed another MLPA analysis with SALSA MLPA probemix P036-E3 Subtelomeres Mix 1 and probemix P070-B3 Subtelomeres Mix 2B for investigation of subtelomeric region that revealed a duplication of 11q25 region and the confirmation was performed using SALSA MLPA probemix P286-B2 Human Telomere-11. In conclusion, we consider that MLPA is a valuable method for identification of sSMC in children with developmental delay and congenital anomalies. Genetic diagnosis using different molecular techniques, such as MLPA, for increasing accuracy in identification of chromosomal structural aberrations has an important role in clinical diagnosis and in genetic counselling and our case explain the importance of using a specific laboratory technique for each stage of diagnosis.

Identification of chromosomes in Thinopyrum intermedium and wheat Th. intermedium amphiploids based on multiplex oligonucleotide probes

Synthesized oligonucleotides (oligos) can be used as effective probes similar to plasmid clones for chromosome identification in fluorescence in situ hybridization (FISH) analysis, making oligo FISH a simpler and more efficient molecular cytogenetic technique for studying plants. In this study, multiplex oligonucleotide probes, including pSc119.2-1, pAs1-4, (GAA)10, (AAC)6, and pTa71, were combined and used in FISH to identify chromosomes in common wheat, Thinopyrum intermedium, and a wheat – Th. intermedium amphiploid TE256-1. In comparison with general FISH probes, signals generated by the multiplex probes were more abundant, colorful, and characteristic. Combining the results of genomic in situ hybridization (GISH) with FISH, Th. intermedium chromosomes and alien chromosomes in TE256-1 could be classified and identified more precisely, especially the J- and Js-genome chromosomes. Moreover, based on the FISH results using multiplex probes, more structural variations in wheat chromosomes of TE256-1 were detected. The results indicated that multiplex oligo probes would have a wide range of application prospects in the creation and identification of wheat – Th. intermedium germplasms.

A Preliminary Study of the Suitability of Archival Bone Marrow and Peripheral Blood Smears for Diagnosis of CML Using FISH

Background.FISH is a molecular cytogenetic technique enabling rapid detection of genetic abnormalities. Facilities that can run fresh/wet samples for molecular diagnosis and monitoring of neoplastic disorders are not readily available in Ghana and other neighbouring countries. This study aims to demonstrate that interphase FISH can successfully be applied to archival methanol-fixed bone marrow and peripheral blood smear slides transported to a more equipped facility for molecular diagnosis of CML.Methods.Interphase FISH was performed on 22 archival methanol-fixed marrow (BM) and 3 peripheral blood (PB) smear slides obtained at diagnosis. The BM smears included 20 CML and 2 CMML cases diagnosed by morphology; the 3 PB smears were from 3 of the CML patients at the time of diagnosis. Six cases had knownBCR-ABLfusion results at diagnosis by RQ-PCR. Full blood count reports at diagnosis were also retrieved.Result.19 (95%) of the CML marrow smears demonstrated theBCR-ABLtranslocation. There was a significant correlation between theBCR-ABLtranscript detected at diagnosis by RQ-PCR and that retrospectively detected by FISH from the aged BM smears at diagnosis (r=0.870;P=0.035).Conclusion.Archival methanol-fixed marrow and peripheral blood smears can be used to detect theBCR-ABLtranscript for CML diagnosis.

Application of Multiplex RT-PCR for Identification of Leukemia Associated Gene Abnormalities.

The best prognostic predictor for acute leukemia is known to be the finding of genetic abnormalities of leukemic cells. Methods for detecting the genetic abnormalities include chromosomal studies for karyotyping, FISH(Fluorescence in situ hybridization) and RT-PCR. However, each methods have limitations i.e. low sensitivity in karyotyping, uncertainty of molecular probe to be used in FISH or RT PCR methods. Multiplex RT-PCR (MRT-PCR) allows simultaneous detection of 28 fusion genes, more than 80 breakpoints and splice variants associated with leukemia. Therefore, this method can be used for detection of molecular abnormality in fresh unknown leukemic cases, as well as for molecular remission in follow-up cases. The aim was to demonstrate whether MRT-PCR system might be successfully used to screen a large number of patients with acute leukemia and compare the result with that of chromosome studies. Frozen bone marrow cells from 78 patients, who were diagnosed with acute leukemia at Ajou university hospital between September 1994 and February 2004, were used for MRT-PCR. In all samples with a known conventional cytogenetic results, we performed MRT-PCR and to compared with conventional cytogenetic study regarding the concordance rate and analyzed discordant cases regarding their types. 78 samples(40 male and 38 female patients) were analyzed, and there were 59 AML patients and 19 ALL patients. We successfully obtained the mRNA from all frozen samples. In 21 cases with gene abnormalities by chromosome studies most of them (15/21) showed the same abnormalities with MRT-PCR. In 57 patients with normal karyotype by cytogenetic technique, we identified 18 translocations of clinical significance by MRT-PCR method. In 18 discordant cases, there were 4 cases with t(15;17), 4 cases with t(8;21), 3 cases with t(9;22), 2 cases with t(11;19) and 4 others [t(9;11),t(9;9),t(3;11),inv(16)]. Conventional cytogenetics detected 10 cases of good prognostic gene abnormalities [t(15;17),t(8;21),inv(16)], but MRT-PCR method detected 10 additional cases of good prognostic gene abnormalities which might change the treatment paln. The twenty good prognostic cases with MRT-PCR showed better overall survival than others. (median f/u = 10.6 month, p=0.0443) There were 69% concordance rate between cytogenetic technique and MRT-PCR. Furthermore clinically significant translocations were detected by MRT-PCR in 18 of 57 normal karyotype patients, indicating improved sensitivity and prognostic value with MRT-PCR. Further investigations are needed to ascertain the usefulness of MRT-PCR for the screening tool of leukemic gene abnormalities.