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Biomedical subjects

J Malek

Publications and source records attributed to J Malek.

9 recordsLinked to original sources
PubMed2004

Identifying genes for neuron survival and axon outgrowth in Hirudo medicinalis.

We have studied the molecular basis of nervous system repair in invertebrate (Hirudo medicinalis) nerve cells. Unlike in mammals, neurons in invertebrates survive injury and regrow processes to restore the connections that they held before the damage occurred. To identify genes whose expression is regulated after injury, we have used subtractive probes, constructed from regenerating and non-regenerating ganglia from the leech Hirudo medicinalis, to screen cDNA libraries made from whole leech CNS or from identified microdissected neurons. We have identified genes of known or predicted function as well as novel genes. Known genes up-regulated within hours of injury and that are widely expressed in invertebrate and mammalian cells include thioredoxin and tubulin. Other known genes, e.g. Cysteine Rich Intestinal Protein (CRIP), have previously been identified in mammalian cells though not in regenerating adult neurons. Two regulated genes identified, myohemerythrin and the novel protein ReN3 are exclusively expressed in invertebrates. Thus our approach has enabled us to identify genes, present in a neuron of known function, that are up- and down-regulated within hours of axotomy, and that may underpin the intrinsic ability of invertebrate neurons to survive damage and initiate regrowth programmes.

Animals↗
PubMed2003

Radiation hybrid map, physical map, and low-pass genomic sequence of the canine prcd region on CFA9 and comparative mapping with the syntenic region on human chromosome 17.

Progressive rod-cone degeneration (prcd) is a canine retinal disease that maps to the centromeric end of CFA9 in a region of synteny with the distal part of HSA17q. As such, prcd has been postulated as the only animal model of RP17, a human retinitis pigmentosa locus that maps to 17q22. In an effort to establish more detailed regions of synteny between dog CFA9 and the HSA17q-ter region, we created a robust gene-enriched CFA9-RH08(3000) map with 34 gene-based markers and 12 microsatellites, with the highest resolution and number of markers for the centromeric end of CFA9. Furthermore, we built an approximately 1.5-Mb physical map containing both GRB2 and GALK1, genes so far identified by meiotic linkage analysis as being closest to the prcd locus, and generated about 1.2 Mb low-pass (3.2x) canine sequence. Canine to human comparative sequence analysis identified 49 transcripts that had been previously mapped to the HSA17q25 region. The generated low-pass canine sequence was annotated with a working draft of human sequence from HSA17q25, and we used this scaffold to order and orient the canine sequence against human. This order and orientation are preliminary, as high-throughput genomic sequencing of HSA17q-ter has not been fully completed.

Animals↗
PubMed2001

Effect of agroclavine on NK activity in vivo under normal and stress conditions in rats.

Agroclavine is a natural, clavine type of ergot alkaloid with D1 dopamine and a-adrenoceptor agonistic properties. We showed previously that in vitro agroclavine enhances natural killer (NK) cell activity, increases interleukin-2 and interferon-gamma production and prolongs the survival time of tumor-bearing mice. The aim of this study was 1) to test the effect of agroclavine on NK activity in vivo, and 2) to assess the potential toxicity of high doses of agroclavine on cardiac and liver functions using creatine kinase MB (CKMB) and alanine aminotransferase (ALT) as biochemical markers in normal and stressed animals. The effect of stress was studied because we examined promising anticancer properties of agroclavine and malignant diseases are supposed to be a potent stressful event for patients. In our experiments 3-month-old male rats of the Wistar-Kyoto strain were used. Agroclavine was injected intraperitoneally (0.5 mg/kg or 0.05 mg/kg) 30 min before stress (four hours' restraint and immersion in 23 degrees C water). The animals were killed 30 min after stress, blood was collected and the spleen was removed. Non-stressed animals treated with agroclavine were killed 5 h after the drug administration. The results confirmed our previous in vitro results and showed that also in vivo agroclavine increases NK cell activity under non-stress conditions. Agroclavine only slightly increased CKMB and had no influence on ALT in non-stressed animals. These promising results are limited by the fact that agroclavine (0.5 mg/kg) diminished NK cell activity and significantly increased ALT and CKMB under stress conditions.

Alanine Transaminase↗
PubMed2000

Human BAC ends quality assessment and sequence analyses.

End sequences from bacterial artificial chromosomes (BACs) provide highly specific sequence markers in large-scale sequencing projects. To date, we have generated >300,000 end sequences from >186,000 human BAC clones with an average read length of >460 bp for a total of 141 Mb covering approximately 4.7% of the genome. Over 60% of the clones have BAC end sequences (BESs) from both ends representing more than fivefold coverage of the human genome by the paired-end clones. Our quality assessments and sequence analyses indicate that BESs from human BAC libraries developed at The California Institute of Technology (CalTech) and Roswell Park Cancer Institute have similar properties. The analyses have highlighted differences in insert size for different segments of the CalTech library. Problems with the fidelity of tracking of sequence data back to physical clones have been observed in some subsets of the overall BES dataset. The annotation results of BESs for the contents of available genomic sequences, sequence tagged sites, expressed sequence tags, protein encoding regions, and repeats indicate that this resource will be valuable in many areas of genome research.

Chromosome Mapping↗
PubMed1996

Transcriptional regulation of the proton-translocating ATPase (atpIBEFHAGDC) operon of Escherichia coli: control by cell growth rate.

The F0F1 proton-translocating ATPase complex of Escherichia coli, encoded by the atpIBEFHAGDC operon, catalyzes the synthesis of ATP from ADP and Pi during aerobic and anaerobic growth when respiratory substrates are present. It can also catalyze the reverse reaction to hydrolyze ATP during nonrespiratory conditions (i.e., during fermentation of simple sugars) in order to maintain a electrochemical proton gradient across the cytoplasmic membrane. To examine how the atp genes are expressed under different conditions of cell culture, atpI-lacZ operon fusions were constructed and analyzed in single copy on the bacterial chromosome or on low-copy-number plasmids. Expression varied over a relatively narrow range (about threefold) regardless of the complexity of the cell growth medium, the availability of different electron acceptors or carbon compounds, or the pH of the culture medium. In contrast to prior proposals, atp operon expression was shown to occur from a single promoter located immediately before atpI rather than from within it. The results of continuous-culture experiments suggest that the cell growth rate rather than the type of carbon compound used for growth is the major variable in controlling atp gene expression. Together, these studies establish that synthesis of the F0F1 ATPase is not greatly varied by modulating atp operon transcription.

Bacterial Outer Membrane Proteins↗