• Graphical touch screen interface for simplified programming
• NO adapters necessary for different tube sizes!
• NO cap moves over open tubes to eliminate cross-contamination
• 96 tubes can be decapped or recapped in under 10 seconds
• DeCapper is compatible with Micronic tubes and other major brands

Hamilton - Gel Caddy™
Store gels easily!

The Gel Caddy™ is designed to protect delicate gels and eliminate breakage. The Gel Caddy allows for imaging, spot cutting, shipping and storage for long periods of time.

Minimal buffer is required to seal the gel, reducing the risk of breakage during shipping or even routine manipulation. The Gel Caddy is significantly larger than the gel to allow for sealing and resealing. Use of the Impulse Heat Sealer minimizes the risk of a faulty seal and improves the gel's lifespan.

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Orochem - Oligonet Customized Oligonucleotides

Whether you need a single oligo or thousands, a plain pair of standard primers for PCR or high purified ExtreMERS® for gene synthesis, in plates or in tubes, Oligonet can fulfill your specific oligo requirements.

Several modifications are available, including:

SCAT - Safety Caps and Safety Waste Caps for Solvent Handling

SCAT Safety Caps and Safety Waste Caps keep your lab environment healthier and your solvents cleaner. By sealing solvent vapours in the bottle, SCAT caps reduce organic vapours in lab air and prevent differential evaporation of mixed solvents.

• Airtight seal between container and caps
• Valves and filters equalize pressure in containers, but trap solvent vapours
• Simple automatic operation. Safety features will not be disabled or forgotten
• No power needed. Unlike forced ventilation, SCAT caps protect when the power goes out
• Passive “Pop-up” indicators on waste containers help to prevent spills

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Chromatographic Specialties Inc. - Orochem, Hamilton and SCAT products are distributed by our sister company, Chromatographic Specialties Inc. Please note that these products can be ordered on the same request as your regular ^MJSBioLynx Inc. product orders.

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New Literature

Matreya - 2009-2010 Catalogue

Matreya offers a broad range of lipids for biochemical microbiology and food research. Their products include sphingosines, ceramides, gangliosides, phosphatidyl inositol phosphates and many more.
Click here for the on-line PDF.

Enzo Life Sciences - CELLestial™ Fluorescent Probes and Labeling Products Catalogue

The CELLestial™ brand of products represents a comprehensive family of dyes, labels, probes and markers for identifying pathways, functions and other cellular events.
Click here for the on-line PDF.

AthenaES - 2009-2010 Catalogue

AthenaES offers an extensive line of products that concentrate on the expression of difficult-to-produce proteins that have the potential to provide ground-breaking benefits. Their products include kits and reagents for protein expression and cell culture.
Click here for the on-line PDF (print version is not available).

Contact our Technical Support Team to request printed copies.

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Promotions

Abgent - Free Chocolate with the Purchase of Antibodies

From April 1st to June 30th, 2009
Accumulate purchases of 5 Abgent antibodies* and receive a $50 gift card for Laura Secord Chocolates.

Abgent antibodies are widely used in the fields of :

Gentel Biotechnologies - Receive a Free SIMplex™ 16 Multi-Array System when you purchase an APiX™ Cancer Biomarker Array Kit.

Measure the relative abundance of 46 human cancer-related proteins
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• Very Convenient: No medium changes required, compatible with serum and antibiotics

Assay Designs - 50% OFF an ImmunoSet Buffer Pack with the Purchase of Any ImmunoSet

The Assay Designs ImmunoSet Buffer Pack provides an all-purpose buffer that is easily modified to coat, block, and wash plates in addition to diluting standards and samples. TMB substrate and acid stop solution for colour development and reaction termination are also supplied.

This offer is valid until April 30th, 2009
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Active Motif - Order ChIP-IT™ Express HT and Receive a FREE MAG-96 Magnetic Stand

ChIP-IT™ Express HT allows you to perform chromatin IP in a fast, reproducible high-throughput format. It combines the efficiency of the groundbreaking magnetic bead-based ChIP-IT™ Express Kit with a 96-well plate format, enabling the rapid and efficient processing of a large number of ChIP reactions.

This offer is available while quantities last
Click here for promotion details

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Technical Report

Retroviruses, Chromatin Structure and Transcriptional Regulation- by Active Motif

Retroviral DNA is integrated in its host genome, which allows the virus to escape from the host’s immune system. Therefore, chromatin structure plays an important role in the transcriptional regulation of retroviral genes.

During retroviral infection of a eukaryotic cell, the integration of viral DNA into the cellular genome is an important step for the viral cycle. This allows the provirus to survive in the host cell and, with limited viral transcription, escape detection by the host immune system. Once integrated, the provirus is organized into chromatin, along with all cellular genes, and is transcribed by the host RNA polymerase II (RNA pol II). Transcription from eukaryotic promoters, including retroviral promoters, is regulated by different cellular mechanisms. Recruitment of transcription factors, chromatin structure, histone modifications and DNA methylation play important roles in this process.

Chromatin, the material into which genomic DNA is packaged in eukaryotes, is a very dynamic structure. The smallest subunit of chromatin is the nucleosome, 147 base pairs of DNA wrapped around an octamer of core histone proteins. Chromatin is subject to a variety of chemical modifications, including the post-translational modification of the histones and the methylation of cytosines in the DNA. Reported histone modifications include acetylation, methylation, phosphorylation, ubiquitylation, glycosylation, ADP-ribosylation, carbonylation and SUMOylation. Many modifications can and do influence others, and many are positively or negatively correlated with specific transcriptional states and the specific organization of repressive or open chromatin. Some modifications serve as signals for the binding of specific proteins, referred to collectively as the “histone code”.

After integration of the viral DNA into the host genome, the provirus can be transcriptionally active or inactive (latent). For example, cells latently infected by Human Immunodefi ciency Virus type1 (HIV-1) serve as “reservoirs” of virus and are a permanent source of virus reactivation. Latency is a viral strategy to avoid the host immune response, allowing survival of the virus. The persistence of these latently HIV-infected cellular reservoirs, despite prolonged treatment with highly effective retroviral therapy, represents the major obstacle to virus eradication. Bovine Leukemia Virus (BLV) and Human T-Lymphotropic Virus type 1 (HTLV-1) infections are characterized by viral latency in the large majority of infected cells and by the absence of virus circulating in the blood. These features are thought to be due to the repression of viral gene expression in vivo.1, 2

In this review, we will focus on the role of some chromatin modifications in the initiation and maintenance of viral latency within the host cells.

DNA methylation
Inhibition of gene expression and a repressive chromatin state are often associated with DNA methylation, an epigenetic modification of DNA that occurs on cytosines within CpG dinucleotides. Addition of the methyl group to cytosines is carried out by the DNA methyltransferase enzymes (DNMT). There are at least two general mechanisms by which DNA methylation inhibits gene expression: first, modification of cytosine bases can inhibit the association of some DNA-binding factors with their cognate DNA recognition sequences;3 and second, proteins that recognize methyl-CpGs can elicit the repressive potential of methylated DNA (reviewed in 4). The second mechanism is predominant and is generally associated with histone deacetylation, rendering the conformation of chromatin inaccessible to the transcriptional machinery. Additionally, there is a significant body of evidence linking DNA methylation with histone methylation, indicating that one might reinforce the other to cooperatively silence gene expression.37-39

Methylation of retroviral promoter and enhancer sequences located in the 5´LTR (Long Terminal Repeat) is a mechanism of epigenetic silencing of provirus transcription, which allows the virus to become latent and avoid detection by the host immune system.5-7 An inverse correlation between gene expression and CpG methylation in the 5´LTR of retroviral genomes has indeed been indeed demonstrated in HTLV-1,7-9 in Moloney Murine Leukemia Virus (Mo-MuLV)6, 10 and in Rous Sarcoma virus.11 The role of HIV-1 promoter methylation in viral latency is quite controversial, however. CpG methylation within the HIV-1 promoter inhibits transcription of in vitro methylated plasmids transfected cells,12-14 and it was suggested as a mechanism to maintain HIV-1 latency in some infected cell lines.15, 16 In contrast to these studies, Pion et al. showed using bisulfite sequencing, that transcriptional repression of HIV-1 is not associated with methylation of the 5´LTR.17

Histone acetylation
One factor influencing the modulation of chromatin structure is the reversible acetylation of conserved lysine residues on histone proteins. The acetylation reaction results in the transfer of the acetyl group from acetyl-coA to the e-amino group of the lysine residue, neutralizing its positive charge. Steadystate levels of histone acetylation result from a balance between the activity of two families of antagonistic enzymes: histone deacetylases (HDACs) and histone acetyltransferases (HATs), which respectively remove or add acetyl groups to histones.

Histone acetylation is an important mechanism implicated in the regulation of retroviral promoters. Several studies have reported the regulation of BLV and HTLV-1 transcription by histone acetylation. Many groups have observed the strong effect of HDAC inhibitors on the BLV gene expression in vitro and in vivo.18-21 They have also shown a role for the HATs CBP and p300 in the transcriptional activation of BLV and HTLV-1.22-25 Recruitment of HDAC1, HDAC2 or HDAC3 to the HTLV-1 promoter has been observed and linked to repression of the viral promoter.26, 27 Other retroviruses including HIV-1 (review in 28), the Rous Sarcoma virus29 or MoMuLV30, 31 are also regulated by histone acetylation. For example, it has been demonstrated by chromatin mapping experiments that a nucleosome positioned immediately downstream of the transcription start site is remodeled upon the activation of the HIV-1 promoter in response to HDAC inhibitors.32 Lorincz et al. have demonstrated an inverse correlation between acetylation of histone H3 and proviral methylation density and transcriptional repression of MoMuLV.30

Histone Methylation
The methylation of histones can occur on arginine (R) and lysine (K) residues. Methylation at many residues of all the core histones has been observed (reviewed in 33). Histone lysine methyltransferases (HMTs) contain a catalytic SET domain, utilizing S adenosyl-Lmethionine (SAM) as a cofactor. Some sites of histone methylation are associated with transcriptional activation (e.g.H3 K4), whereas others (e.g. H3 K9, H3 K27) are associated with transcriptional repression and heterochromatin formation. The arginine methyltransferases are responsible for the transfer of methyl groups from SAM to the guanidinium group of arginine. There are several enzymes which methylate histones at arginine residues, PRMT1 and CARM1/ PRMT4 being the most widely studied of these. Generally, methylation of histones on arginine residues is associated with transcriptional activation of genes.

A few things are known about histone methylation within the BLV promoter. Merimi et al. demonstrated a change in lysine methylation leading to BLV activation after a treatment of the infected cells with a combination of trichostatin A (an HDAC inhibitor) and 5-azacytidine (a DNA methylation inhibitor).34 An increase of H3 K4 methylation and a decrease of H3 K9 methylation accompanied a decrease of HDAC1 and mSin3 recruitment after treatment of the cells.34 In the case of HTLV-1, two histone methyltransferases seem to be involved in the transcriptional regulation of the viral promoter.35, 36 ChIP assays demonstrated the recruitment of CARM1 and Suv39H1 in vivo at the promoter region, together with the viral transcriptional activator protein, Tax. This recruitment is associated with strong H3 methylation on different arginine residues and with acetylation of H3 K9 in cells containing a single active integrated copy.

All these studies show the importance of epigenetic modifications in the transcriptional regulation of retroviruses. It is certain that similar future research will aid in treatment of viral diseases.

References

1. N. Gillet et al., (2007) Retrovirology 4:18.
2. J. Yasunaga, M. Matsuoka, (2007) Cancer Control 14:133.
3. F. Watt, P. L. Molloy, (1988) Genes Dev 2:1136.
4. T. Latham, N. Gilbert, B. Ramsahoye, (2008) Cell Tissue Res 331:31.
5. R. Pearson et al.,(2008) J Virol 82:12291.
6. K. Harbers, A. Schnieke, H. Stuhlmann, D. Jahner, R. Jaenisch, (1981) PNAS 78:7609.
7. T. Koiwa et al., (2002) J Virol 76:9389.
8. D. Saggioro, M. Panozzo, L. Chieco-Bianchi, (1990) Cancer Res 50:4968.
9. Y. Taniguchi et al., (2005) Retrovirology 2:64.
10. R. C. Hoeben, A. A. Migchielsen, R. C. van der Jagt, H. van Ormondt,
A. J. van der Eb, (1991) J Virol 65:904.
11. J. Hejnar et al., (1999) Virology 255:171.
12. D. P. Bednarik, J. A. Cook, P. M. Pitha, (1990) EMBO J 9:1157.
13. K. A. Gutekunst, F. Kashanchi, J. N. Brady, D. P. Bednarik, (1993) J Acquir Immune Defic Syndr 6:541.
14. K. Schulze-Forster, F. Gotz, H. Wagner, H. Kroger, D. Simon, (1990) Biochem Biophys Res Commun 168:141.
15. M. K. Singh, C. D. Pauza, (1992) Virology 188:451.
16. T. Ishida, A. Hamano, T. Koiwa, T. Watanabe, (2006) Retrovirology 3:69.
17. M. Pion et al., (2003) J Virol 77:4025.
18. C. Merezak et al., (2002) J Virol 76:5034.
19. A. Achachi et al., (2005) PNAS 102:10309.
20. C. Calomme et al., (2004) J Virol 78:13848.
21. T. L. Nguyen et al., (2004) J Biol Chem 279:35025.
22. T. L. Nguyen et al., (2007) J Biol Chem 282:20854.
23. H. Lu et al., (2002) Mol Cell Biol 22:4450.
24. I. Clerc et al., (2008) J Biol Chem 283:23903.
25. N. Sharma, J. K. Nyborg, (2008) PNAS USA 105:7959.
26. R. Villanueva et al., (2006) Oncol Rep 16:581.
27. T. Ego, Y. Ariumi, K. Shimotohno, (2002) Oncogene 21:7241.
28. V. Quivy, S. De Walque, C. Van Lint, (2007) Subcell Biochem 41:371.
29. E. Espinos, A. Le Van Thai, C. Pomies, M. J. Weber, (1999) Mol Cell Biol 19:3474.
30. M. C. Lorincz, D. Schubeler, M. Groudine, (2001) Mol Cell Biol 21:7913.
31. R. Appanah, D. R. Dickerson, P. Goyal, M. Groudine, M. C. Lorincz, (2007) PLoS Genet 3, e27.
32. C. Van Lint, S. Emiliani, M. Ott, E. Verdin, (1996) EMBO J 15:1112.
33. P. K. Lo, S. Sukumar, (2008) Pharmacogenomics 9:1879.
34. M. Merimi et al., (2007) J Virol 81:5929.
35. S. J. Jeong et al., (2006) J Virol 80:10036.
36. Y. Zhang, D. Reinberg, (2001) Genes Dev 15:2343.
37. L. M. Johnson et al., (2007) Curr Biol 17:379.
38. S. Epsztejn-Litman et al, (2008) Nat Struct Mol Biol 15:1176.
39. J. Wang et al, (2009) Nat Genet 41:125.

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Events

NuGEN Webinar - Prognostic Multigene Expression Classification of Cancer Patients: A Route for Success

Join us for this upcoming NuGEN Web Lecture Event!
Date and time: Wednesday, April 1, 2009
11:30 am Eastern Daylight Time / 8:30 am Pacific Daylight Time
Duration: 1 hour

Click here to register.

Description: More accurate assessment of prognosis is of importance to improve the choice of risk-related therapy in cancer patients. It has been shown that gene expression profiling is able to achieve this goal. Here, we outline a strategy for real-time PCR-based gene expression profiling of 60 candidate prognostic markers identified upon meta-analysis of published gene expression studies. Key success factors of our strategy are the testing of many more patients than genes, rigorous RNA quality control, thorough evaluation of qPCR gene expression assays, use of absolute standards for cross-laboratory comparison, and application of the WT-Ovation™ pre-amplification procedure enabling the expression profiling using only 20 ng of total RNA as starting material. Following the outlined strategy, we established a robust and accurate prognostic multigene expression predictor, suitable for routine lab tests and ready to be evaluated in prospective studies.

Featured Presenter:
Jo Vandesompele, PhD
Professor, Functional Genomics and Applied Bioinformatics
Ghent University, Belgium

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Announcement

Abgent - New Resources for Autophagy Research

The Abgent autophagy resource page features reviews, protocols, videos, citations and much more. Be sure to visit the Autophagy Shop where autophagy art can be applied to a variety of items including t-shirts and mugs. Click here to access these great resources.

Example of a word cloud image available
in the Autophagy Shop section.

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