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At least 1,063 records · Page 59Linked to original sources
PubMed1998

Evidence of an overlap between the two half-sites of UAS1-B/CYC1--a new model for Cyp1p (Hap1p) DNA binding.

Cyp1p (Hap1p) is a yeast transcriptional regulator belonging to the zinc-cluster family. CGGNNNTANCGG was identified by PCR selection as the DNA sequence allowing its optimal binding. Nevertheless, this sequence is not a consensus sequence, the simultaneous presence of the two CGGs and the TA generally not being found in the known natural Cyp1p targets. In fact, our previous studies showed that the mechanism of Cyp1p DNA binding was target dependent. Data concerning the binding of Cyp1p to the UAS1-B/CYC1 are presented here. This target, containing the CGGGGTTTACGG sequence, was found to present the particular ability of stabilizing the binding of only one molecule of some monomeric Cyp1p fragments. This property was used to investigate the actual contribution of the TT and CGG sequences in the binding of Cyp1p. Our results indicate that each CGG belongs to a different half-site and, in contrast to a previous hypothesis, that the T nucleotide located four bases downstream from the left CGG is essential for the binding of one monomer to each half-site. The two half-sites of the UAS1-B/CYC1 thus overlap.

Carbon-Oxygen Lyases↗
PubMed2001

Molecular bases of odor discrimination: Reconstitution of olfactory receptors that recognize overlapping sets of odorants.

The vertebrate olfactory system discriminates a wide variety of odorants by relaying coded information from olfactory sensory neurons in the olfactory epithelium to olfactory cortical areas of the brain. Recent studies have shown that the first step in odor discrimination is mediated by approximately 1000 distinct olfactory receptors, which comprise the largest family of G-protein-coupled receptors. In the present study, we used Ca(2+) imaging and single-cell reverse transcription-PCR techniques to identify mouse olfactory neurons responding to an odorant and subsequently to clone a receptor gene from the responsive cell. The functionally cloned receptors were expressed in heterologous systems, demonstrating that structurally related olfactory receptors recognized overlapping sets of odorants with distinct affinities and specificities. Our results provide direct evidence for the existence of a receptor code in which the identities of different odorants are specified by distinct combinations of odorant receptors that possess unique molecular receptive ranges. We further demonstrate that the receptor code for an odorant changes with odorant concentration. Finally, we show that odorant receptors in human embryonic kidney 293 cells couple to stimulatory G-proteins such as Galphaolf, resulting in odorant-dependent increases in cAMP. Odor discrimination is thus determined by differences in the receptive ranges of the odorant receptors that together encode specific odorant molecules.

Animals↗
PubMedDate not supplied

Soybean chromosome painting: a strategy for somatic cytogenetics.

Cytological identification of soybean mitotic metaphase chromosomes (2n = 40) has been severely limited by their small size and uniform karyomorphology. We have developed fluorescent in situ hybridization (FISH), PCR-primed in situ labelling (PCR-PRINS) procedures, and molecular probes for routine cytological identification and for the physical mapping of soybean somatic chromosomes. Chromosome preparation has been achieved by modifications of previous protocols and through the preparation of root-tip protoplasts prior to chromosome spreading. Initially our probe selection focused on highly repeated DNAs that provide very intense localized hybridization signals. Repetitive gene probes that have proven valuable include the rDNA loci (5S and 45S) which are chromosome specific. We have also developed satellite DNA probes for two different sequence families: the SB92 and the STR120 satellites. Both of these are tandemly arranged at multiple chromosomal loci. By using different cloned examples of each family, we have been able to selectively label unique subsets of soybean chromosomes. Double hybridization with biotin and digoxigenin labeled probes has allowed us to determine the chromosomal overlap between different probes. In addition, we have joined portions of the metaphase chromosome painting patterns with the genetic map by single-copy FISH and PCR-PRINS detection of the RFLP loci G8.15, G17.3, and A199a and A199b. Total genomic DNA in situ hybridization (GISH) patterns were also used to characterize the soybean chromosomes.

Chromosome Mapping↗
PubMed2001

Adamantinoma-like Ewing's sarcoma and Ewing's-like adamantinoma. The t(11; 22), t(21; 22) status.

Adamantinoma of the long bones and Ewing's sarcoma are two malignant tumours between which, at first sight, there seems to be no morphological and clinical relationship. Both tumours, however, are known to express cytokeratins. Adamantinoma is a tumour of true epithelial nature, predominantly expressing cytokeratins 14 and 19. Ewing's sarcoma, believed to be from neuroectodermal origin, like other mesenchymal tumours, can aberrantly express cytokeratin 8 and 18. In the literature there are some reports of tumours showing clinical and/or morphological overlap between adamantinoma and Ewing's sarcoma, suggesting a possible relationship. These studies are mostly based on the epithelioid configuration of these lesions and their cytokeratin expression on immunohistochemistry. This raises the question of whether there is occasionally a morphological similarity between adamantinoma and Ewing's sarcoma, or whether there is a common genetic background. The Ewing's sarcoma/primitive peripheral neuroectodermal tumour (PNET) family is characterized in 90-95% of cases by a t(11; 22) and in 5-10% of cases by t(21; 22). In the few reports in the literature on cytogenetic investigations on adamantinoma, these translocations were never found using classical karyotyping. This study investigated the putative presence of t(11; 22) and t(21; 22) in 14 cases of adamantinoma by RT-PCR. These translocations were not found in any of these cases. The results support the view that these tumours are genetically and clinically distinct, but may eventually show overlapping morphological and immunohistochemical features.

Ameloblastoma↗
PubMed1992

PCR amplification of large genomic fragments from human and simian immunodeficiency virus infected cell lines.

Polymerase chain reaction (PCR) has been used to amplify the large fragments from viral genomic DNA of SIV from wild caught, asymptomatic Erythrocebus monkeys from Western Africa (Senegal) and also from HIV-2 infected cell lines. By using consensus primer sequences from highly conserved stretches of gag, pol and env genes, two halves of the viral genome of HIV-2 and SIV (isolated from west African Erythrocebus monkeys) have amplified by PCR. One half spans 5200 bp from within the U3 region of the 5' long terminal repeat (LTR) into pol gene and an overlapping fragment spans 3700 bp from the pol gene into U5 region of 3' LTR. Also fragments ranging from 1-2.3 kb from gag pol and env genes have been successfully amplified. Our data demonstrate that primers used to amplify large segments from viral DNA yield better results if they are derived from a consensus sequence of a highly conserved stretch of the viral genome.

Animals↗
PubMed1994

Cloning, genomic organization and transcription of the Entamoeba histolytica alpha-tubulin-encoding gene.

We have isolated and characterized an Entamoeba histolytica alpha-tubulin (alpha Tub)-encoding gene (Eh alpha tub). A 700-bp DNA fragment was amplified by PCR using primers derived from consensus alpha- and beta-Tub amino acid (aa) sequences from different organisms and E. histolytica DNA as the template. These PCR fragments were used to screen both genomic DNA and cDNA libraries in order to isolate an Eh alpha tub structural gene. Two overlapping clones containing the complete alpha tub ORF (1392 bp) were isolated from the genome and cDNA libraries. The deduced aa sequence of Eh alpha Tub has 55.5, 50 and 52% identity to Plasmodium falciparum alpha Tub 2, Saccharomyces cerevisiae alpha Tub 2 and human alpha Tub, respectively. Interestingly, the predicted Eh alpha Tub protein lacks a poly-acidic motif at its C terminus which is involved in Tub polymerization and microtubule-associated protein binding in other organisms. This fact may indicate a difference in tubule assembly in this organism and could provide a potential key for the development of therapeutic agents. According to Southern blot experiments and the sequences of several clones, at least two non-adjacent copies of alpha tub are present in the E. histolytica genome. A 1.5-kb transcript corresponding to the alpha tub mRNA was detected in mRNA from asynchronous E. histolytica trophozoites.

Amino Acid Sequence↗
PubMedDate not supplied

Incidence of BCL-2 gene rearrangements in Argentinean non-Hodgkin lymphoma patients: increased frequency of breakpoints outside of MBR and MCR.

The t(14;18)(q32;q21) is the most frequent cytogenetic abnormality observed in follicular lymphoma (FL), but also occurs in diffuse large B-cell lymphoma (DLBCL). We have evaluated the frequency of this translocation in 106 Argentinean non-Hodgkin lymphoma (NHL) patients: 83 with diagnosis of FL and 23 with DLBCL. Nested (N) and long-distance PCR (LD-PCR) approaches were used. By N-PCR, a total of 42 (51%) FL cases showed BCL-2 rearrangement: 28 (34%) for major breakpoint region (MBR) and 14 (17%) for minor cluster region (mcr). By LD-PCR, additional 23 (28%) new positive cases were found: 10 (12%) for MBR and 13 (16%) for mcr. These data make a total of 65 (78%) positive cases for BCL-2 gene rearrangements. In DLBCL cases, N-PCR detected two (9%) cases with the MBR breakpoint and one (4%) with mcr. Seven (30%) new positive cases by LD-PCR were found: four (17%) for MBR and three (13%) for mcr, showing a total of 10 (43%) positive cases. Thus, both FL and DLBCL had high frequencies of breakpoints located between MBR and mcr clusters. Our N-PCR results in FL (51%; 95% CI, 40-62%) showed statistical differences with respect to the pooled data from USA (P < 0.0001) and overlapped with the frequencies from Asia and Europe. In DLBCL, no significant differences with respect to the literature were found. This data support the idea that FL may be a heterogeneous malignancy with distinct molecular pathogenesis and suggest that the geographic differences may be related with the distribution of breakpoints that are widely spread throughout the sequence stretch between MBR and mcr.

Adult↗
PubMed2006

Hepatitis E virus infection in work horses in Egypt.

Hepatitis E virus (HEV) is an important cause of hepatitis among young Egyptian adults with high seroprevalence rates seen in both rural areas of the Nile Delta and in suburban Cairo. Because natural antibodies to HEV have been detected in animals and zoonotic transmission is postulated, we surveyed work horses in Cairo for evidence of HEV exposure and viremia. Sera from 200 Cairo work horses were tested by ELISA for the presence of IgG anti-HEV antibody revealed a seropositivity of 13%. Among 100 samples processed for detection of viral genome by means of nested polymerase chain reaction (N-PCR), 4% were positive and indicative of viremia. Viremic animals were less than 1 year old. Relative to PCR-negative horses, PCR-positive animals demonstrated significant elevation of AST (p=0.03). Phylogenetic analysis of a 253-bp fragment, in the ORF-1,2,3 overlap region of the HEV genome from the viremic animals showed that three of these viral strains to be identical, and closely related (97-100% nucleotide identity) to two human isolates from Egypt, and distant (78-96%) from 16 other HEV isolates from human and animals and shared 99.6% NI with the fourth strain. The consensus sequence of the four strains was origin obtained elsewhere. These data indicated that horses acquire HEV infection and suggest that cross-species transmission may occur. Whether horses play a role in the transmission of HEV needs further investigation.

Adult↗
PubMed2002

Mutation analysis of the human CYP3A4 gene 5' regulatory region: population screening using non-radioactive SSCP.

Human CYP3A4 is the major cytochrome P450 isoenzyme in adult human liver and is known to metabolise many xenobiotic and endogenous compounds. There is substantial inter-individual variation in the hepatic levels of CYP3A4. Although, polymorphic mutations have been reported in the 5' regulatory region of the CYP3A4 gene, those that have been investigated so far do not appear to have any effect on gene expression. To determine whether other mutations exist in this region of the gene, we have performed a new population screen on a panel of 101 human DNA samples. A 1140 bp section of the 5' proximal regulatory region of the CYP3A4 gene, containing numerous regulatory motifs, was amplified from genomic DNA as three overlapping segments. The 300 bp distal enhancer region at -7.9kb containing additional regulatory motifs was also amplified. Mutation analysis of the resulting PCR products was carried out using non-radioactive single strand conformation polymorphism (SSCP) and confirmatory sequencing of both DNA strands in those samples showing extra SSCP bands. In addition to detection of the previously reported CYP3A4*1B allele in nine subjects, three novel alleles were found: CYP3A4*1E (having a T-->A transversion at -369 in one subject), CYP3A4*1F (having a C-->G tranversion at -747 in 17 subjects) and CYP3A4*15B containing a nine-nucleotide insertion between -845 and -844 linked to an A-->G transition at -392 and a G-->A transition in exon 6 (position 485 in the cDNA) in one subject. All the novel alleles were heterozygous. No mutations were found in the upstream distal enhancer region. Our results clearly indicate that this rapid and simple SSCP approach can reveal mutant alleles in drug metabolising enzyme genes. Detection and determination of the frequency of novel alleles in CYP3A4 will assist investigation of the relationship between genotype, xenobiotic metabolism and toxicity in the CYP3A family of isoenzymes.

5' Untranslated Regions↗
PubMed2002

Multiplexed gene expression analysis using the invader RNA assay with MALDI-TOF mass spectrometry detection.

A mass spectrometric approach for measuring gene expression levels has been developed. This technique utilizes a signal amplification system and analysis by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Signal amplification from the targeted RNA employs a recently developed invasive cleavage assay that does not require prior PCR amplification. The assay uses a set of target-specific probes (oligonucleotides), which hybridize to the RNA being measured to create an overlap structure with a single-stranded flap. This flap is enzymatically cleaved and accumulates linearly in a target-specific manner. The products of the reaction, short DNA oligomers, are well suited for quantitative detection by MALDI-TOF mass spectrometry. Multiplexing is achieved by designing the assays so that reaction products for different mRNA targets have discrete masses that can be resolved in a single mass spectrum. Simultaneous analysis of human cytokine in vitro transcripts IL-1beta, TNF-alpha, and IL-6, with GAPDH as a reference standard, was used as a model system to demonstrate this novel method of gene expression analysis.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Upstream stimulatory factor (USF) and neurogenic differentiation/beta-cell E box transactivator 2 (NeuroD/BETA2) contribute to islet-specific glucose-6-phosphatase catalytic-subunit-related protein (IGRP) gene expression.

Islet-specific glucose-6-phosphatase (G6Pase) catalytic-subunit-related protein (IGRP) is a homologue of the catalytic subunit of G6Pase, the enzyme that catalyses the final step of the gluconeogenic pathway. The analysis of IGRP-chloramphenicol acetyltransferase (CAT) fusion-gene expression through transient transfection of islet-derived beta TC-3 cells revealed that multiple promoter regions, located between -306 and -97, are required for maximal IGRP-CAT fusion-gene expression. These regions correlated with trans -acting factor-binding sites in the IGRP promoter that were identified in beta TC-3 cells in situ using the ligation-mediated PCR (LMPCR) footprinting technique. However, the LMPCR data also revealed additional trans -acting factor-binding sites located between -97 and +1 that overlap two E-box motifs, even though this region by itself conferred minimal fusion-gene expression. The data presented here show that these E-box motifs are important for IGRP promoter activity, but that their action is only manifest in the presence of distal promoter elements. Thus mutation of either E-box motif in the context of the -306 to +3 IGRP promoter region reduces fusion-gene expression. These two E-box motifs have distinct sequences and preferentially bind NeuroD/BETA2 (neurogenic differentiation/beta-cell E box transactivator 2) and upstream stimulatory factor (USF) in vitro, consistent with the binding of both factors to the IGRP promoter in situ, as determined using the chromatin-immunoprecipitation (ChIP) assay. Based on experiments using mutated IGRP promoter constructs, we propose a model to explain how the ubiquitously expressed USF could contribute to islet-specific IGRP gene expression.

Animals↗
PubMed2002

Activation of a p44 pseudogene in Anaplasma phagocytophila by bacterial RNA splicing: a novel mechanism for post-transcriptional regulation of a multigene family encoding immunodominant major outer membrane proteins.

Immunodominant 44 kDa major outer membrane proteins of Anaplasma phagocytophila (human granulocytic ehrlichiosis agent) are encoded by the p44 multigene family. One of the paralogues, p44-18 is predominantly expressed by A. phagocytophila in mammalian hosts, but is downregulated in the arthropod vector. The expression of p44-18 was upregulated in A. phagocytophila cultivated in HL-60 cells at 37 degrees C compared with 24 degrees C. However, the molecular mechanism of such gene expression was unclear, as p44-18 has a pseudogene-like structure, i.e. it lacks an AUG start codon and is out of frame with an upstream overlapping paralogue, p44-1. In the present study, we found that an amplicon detected by reverse transciption-polymerase chain reaction (RT-PCR) [808 basepair (bp)] for the p44-1/p44-18 gene locus was smaller than that detected by PCR with the genomic DNA (1652 bp) in the A. phagocytophila-infected HL-60 cells cultured at 37 degrees C. A circularized RNA molecule corresponding to the 844 bp region missing from the locus in the RT-PCR product was detected by inverse RT-PCR, indicating that this is an intron (designated p44-1 intervening sequence, p44-1 IVS). The splicing event of p44-1 IVS was also observed when the p44-1 IVS-carrying plasmid was introduced into Escherichia coli, suggesting that the splicing is sequence-dependent. Structural analysis and in vitro splicing experiments of p44-1 IVS suggested that this is likely to represent a new class of introns in eubacteria. The primer extension analysis showed the presence of a putative sigma(32)-type promoter in region upstream from p44-1. Collectively, the novel RNA splicing and the temperature-dependent transcription may account for the dominant p44-18 expression in mammals.

Amino Acid Sequence↗
PubMed1998

Localization and interactions of vasoactive peptide receptors in renomedullary interstitial cells of the kidney.

Vasoactive peptides regulate renal medullary microcirculation and tubular function, but the localization of their receptors and mechanisms of actions are currently unknown. Using electron microscopic autoradiography, we have mapped the receptors for angiotensin II (Ang II [AT1 and AT2]), endothelin (ET(A) and ET(B)), and bradykinin (B2) in the rat renal medulla. Although these peptide receptors show distinct vascular and tubular distributions, they overlap strikingly in renomedullary interstitial cells (RMICs) of the inner stripe and the papilla. Using reverse transcription-polymerase chain reaction (RT-PCR) and Southern analysis, mRNAs for AT1A, ET(A), and B2 receptors were detected in cultured adult RMICs. Ang II increases intracellular inositol 1,4,5-triphosphate (IP3) and [Ca2+]i and stimulates [3H]thymidine incorporation and extracellular matrix (ECM) synthesis via AT1A receptors. Endothelin and bradykinin also stimulate cell proliferation and ECM synthesis in RMICs through ET(A) and B2 receptors, respectively, but the actions of endothelin are modulated by concurrent nitric oxide production. By contrast, AT2 receptor mRNA was detected only in embryonic RMICs, in which Ang II inhibits cell proliferation through this receptor. These results suggest that multiple vasoactive peptides may interact with RMICs to exert endocrine and/or paracrine influences on renal medullary microcirculation and tubular function.

Animals↗
PubMed1997

Envelope sequence variability and serologic characterization of HIV type 1 group O isolates from equatorial guinea.

Four sera from Equatorial Guinea (EG) suspected to contain antibody against HIV-1 group O-related viruses were identified on the basis of unusual and differential serologic reactivity in selected commercial assays and Western blot. Degenerate primers, designed from HIV-1 group O published sequences, were used to PCR amplify envelope (env) gene sequences from the suspect EG sera. A complete envelope gene sequence from each serum was determined from the overlapping env gene fragments. Analysis (PHYLIP package of programs) of Env amino acid sequences (translated from nucleotide sequences) indicated that the amino acid sequences obtained from EG sera clustered more closely with HIV Env sequences of group O compared to group M. The amino acid sequences at the octameric tip of the V3 loop were either RIGPLAWY (one isolate), RIGPMAWY (two isolates), or GLGPLAVY (one isolate). The V3 tip tetrameric sequence GPLA is represented only once in the 1995 HIV (Los Alamos) database, but was present in two of our group O-related EG samples. The gp41 immunodominant regions (IDR) protein sequences were identical for sequences from three of the sera, RLLALETLIQNQQLLNLWGCKGR(K)L(I)VCYTSVK(T)W, whereas sequence from the fourth serum contained three changes as noted in parentheses. IDR sequences derived from EG sera were unique compared to those reported for other HIV-1 group O isolate ANT70, VAU, or MVP5180. Antibody in each EG serum directed against the IDR could be detected using synthetic peptides comprising sequences from the ANT70 or MVP5180 IDRs, but were most reactive against the sequences derived from the samples themselves. Little or no serologic reactivity was detected when EG sera were reacted against peptides comprising the IDR of HIV-1 group M (subtype B consensus) or HIV-2 (consensus).

Amino Acid Sequence↗
PubMed2003

The sucrose transporter gene family in rice.

In this paper we report the identification, cloning and expression analysis of four putative sucrose transporter (SUT) genes from rice, designated OsSUT2, 3, 4 and 5. Three of the four genes were identified through extensive searches of the recently published draft sequence of the rice genome. Along with the previously reported OsSUT1 we propose that these five genes comprise the rice SUT gene family. Complementary DNA clones were isolated for the four newly identified genes. The deduced proteins of all five SUT genes were predicted to contain 12 membrane-spanning helices and a domain highly conserved throughout all known plant SUTs, suggesting the four additional OsSUT genes encode functional SUTs. Reverse transcription-PCR analysis was performed in order to investigate the expression pattern of each member of the SUT family in rice. A differing but overlapping expression pattern was observed for each member of the SUT family at different stages through plant development. These results, together with the structural variations apparent from the deduced protein sequences, suggest that the five SUTs possess diverse roles in both sink and source tissues. We also discuss the classification and evolution of the rice SUT gene family, using a comparison of the gene structures and deduced amino acid sequences with other known plant SUT genes.

Amino Acid Sequence↗
PubMed2006

Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

Lamivudine is a major drug approved for treatment of chronic hepatitis B virus (HBV) infection. Emergence of drug-resistant mutants with amino acid substitutions in the YMDD motif is a well-documented problem during long-term lamivudine therapy. Here we report a novel lamivudine-resistant strain of HBV with an intact YMDD motif, which included an amino acid substitution, rtA181T, in the reverse transcriptase (RT) domain of HBV polymerase. The substitution also induced a unique amino acid substitution (W172L) in the overlapping hepatitis B surface (HBs) protein. The YMDD mutant strains were not detected even by using the sensitive peptide nucleic acid-mediated PCR clamping method. The detected nucleotide substitution was accompanied by the emergence of an additional nucleotide substitution that induced amino acid change (S331C) in the spacer domain. The rtA181T mutant strain displayed a threefold decrease in susceptibility to lamivudine in in vitro experiments in comparison with the wild type. In vivo analysis using human hepatocyte-chimeric mice confirmed the resistance of this mutant strain to lamivudine. We developed a method to detect this novel rtA181T mutation and a previously reported rtA181T mutation with the HBs stop codon using restriction fragment length polymorphism PCR and identified one patient with the latter pattern among 40 patients with lamivudine resistance. In conclusion, although the incidence is not high, we have to be careful regarding the emergence of lamivudine-resistant mutant strains with intact YMDD motif.

Adenine↗
PubMed1998

Molecular characterization of the Lactococcus lactis LlaKR2I restriction-modification system and effect of an IS982 element positioned between the restriction and modification genes.

The nucleotide sequence of the plasmid-encoded LlaKR2I restriction-modification (R-M) system of Lactococcus lactis subsp. lactis biovar diacetylactis KR2 was determined. This R-M system comprises divergently transcribed endonuclease (llaKR2IR) and methyltransferase (llaKR2IM) genes; located in the intergenic region is a copy of the insertion element IS982, whose putative transposase gene is codirectionally transcribed with llaKR2IM. The deduced sequence of the LlaKR2I endonuclease shared homology with the type II endonuclease Sau3AI and with the MutH mismatch repair protein, both of which recognize and cleave the sequence 5' GATC 3'. In addition, M. LlaKR2I displayed homology with the 5-methylcytosine methyltransferase family of proteins, exhibiting greatest identity with M. Sau3AI. Both of these proteins shared notable homology throughout their putative target recognition domains. Furthermore, subclones of the native parental lactococcal plasmid pKR223, which encode M. LlaKR2I, all remained undigested after treatment with Sau3AI despite the presence of multiple 5' GATC 3' sites. The combination of these data suggested that the specificity of the LlaKR2I R-M system was likely to be 5' GATC 3', with the cytosine residue being modified to 5-methylcytosine. The IS982 element located within the LlaKR2I R-M system contained at its extremities two 16-bp perfect inverted repeats flanked by two 7-bp direct repeats. A perfect extended promoter consensus, which represented the likely original promoter of the llaKR2IR gene, was shown to overlap the direct repeat sequence on the other side of IS982. Specific deletion of IS982 and one of these direct repeats via a PCR strategy indicated that the LlaKR2I R-M determinants do not rely on elements within IS982 for expression and that the efficiency of bacteriophage restriction was not impaired.

Amino Acid Sequence↗
PubMed2005

CDKL5/STK9 is mutated in Rett syndrome variant with infantile spasms.

BACKGROUND: Rett syndrome is a severe neurodevelopmental disorder, almost exclusively affecting females and characterised by a wide spectrum of clinical manifestations. Both the classic form and preserved speech variant of Rett syndrome are due to mutations in the MECP2 gene. Several other variants of Rett syndrome have been described. In 1985, Hanefeld described a variant with the early appearance of convulsions. In this variant, the normal perinatal period is soon followed by the appearance of seizures, usually infantile spasms. We have observed two patients with signs of Rett syndrome showing acquired microcephaly and stereotypic midline hand movements. The disease started with generalised convulsions and myoclonic fits at 1.5 months in the first patient and with spasms at 10 days in the other, suggesting a diagnosis of the Hanefeld variant. In these patients, MECP2 point mutations and gross rearrangements were excluded by denaturing high performance liquid chromatography and real time quantitative PCR. The ARX and CDKL5 genes have been associated with West syndrome (infantile spasms, hypsarrhythmia, and mental retardation). METHODS: Based on the clinical overlap between the Hanefeld variant and West syndrome, we analysed ARX and CDKL5 in the two girls. RESULTS: We found frameshift deletions in CDKL5 in both patients; one in exon 5 (c.163_166delGAAA) and the other in exon 18 (c.2635_2636delCT). CDKL5 was then analysed in 19 classic Rett and 15 preserved speech variant patients, all MECP2 negative, but no mutations were found. CONCLUSION: Our results show that CDKL5 is responsible for a rare variant of Rett syndrome characterised by early development of convulsions, usually of the spasm type.

Amino Acid Sequence↗