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  • Nicotine accelerates diabetes-induced retinal changes. 24911405

    To investigate the effects of nicotine on retinal alterations in early-stage diabetes in an established rodent model.Sprague-Dawley rats were examined using a combination of confocal scanning laser ophthalmoscopy and spectral domain optical coherence tomography to determine changes in retinal structure in response to nicotine exposure, diabetes and the combined effects of nicotine and diabetes. Diabetes was induced by a single injection of 65 mg/kg streptozotocin and nicotine injections were administered subcutaneously daily. Retinal thickness in the superior, inferior, nasal and temporal quadrants were determined based on the spectral domain optical coherence tomography (SD-OCT) volume scans (20° × 20°) centered on the optic disc. Segmentation of discrete retinal layers was performed on a subset of SD-OCT cross-sections to further examine changes in each treatment group. Survival of neurons within the ganglion cell layer (GCL) was assessed by confocal morphometric imaging.The control group did not experience any significant change throughout the study. The nicotine treatment group experienced an average decrease in total retinal thickness (TRT) of 9.4 µm with the majority of the loss localized within the outer nuclear layer (ONL) as determined by segmentation analysis (p less than  0.05). The diabetic group exhibited a trend toward decreased TRT while segmentation analysis of the diabetic retinopathy (DR) group revealed significant thinning within the ONL (p less than  0.05). The combination of nicotine and diabetes revealed a significant increase of 8.9 µm in the TRT (p less than  0.05) accompanied by a decrease in the number of GCL neurons.We demonstrated significant temporal changes in retinal morphology in response to nicotine exposure, diabetes and with the combined effects of nicotine and diabetes. These findings may have implications in determining treatment strategies for diabetic patients using products containing nicotine, such as cigarettes, smokeless tobacco, electronic cigarettes or smoking cessation products.
    Document Type:
    Reference
    Product Catalog Number:
    MAB377
    Product Catalog Name:
    Anti-NeuN Antibody, clone A60
  • Tandem orthogonal proteolysis-activity-based protein profiling (TOP-ABPP)--a general method for mapping sites of probe modification in proteomes. 17545978

    Activity-based protein profiling (ABPP) utilizes active site-directed chemical probes to monitor the functional state of enzymes directly in native biological systems. Identification of the specific sites of probe labeling on enzymes remains a major challenge in ABPP experiments. In this protocol, we describe an advanced ABPP platform that utilizes a tandem orthogonal proteolysis (TOP) strategy coupled with mass spectrometric analysis to simultaneously identify probe-labeled proteins together with their exact sites of probe modification. Elucidation of probe modification sites reveals fundamental insights into the molecular basis of specific probe-protein interactions. The TOP-ABPP method can be applied to any type of proteomic sample, including those derived from in vitro or in vivo labeling experiments, and is compatible with a variety of chemical probe structures. Completion of the entire protocol, including chemical synthesis of key reagents, requires approximately 8-10 days.
    Document Type:
    Reference
    Product Catalog Number:
    04-1037
  • Cancer-associated TERT promoter mutations abrogate telomerase silencing. 26194807

    Mutations in the human telomerase reverse transcriptase (TERT) promoter are the most frequent non-coding mutations in cancer, but their molecular mechanism in tumorigenesis has not been established. We used genome editing of human pluripotent stem cells with physiological telomerase expression to elucidate the mechanism by which these mutations contribute to human disease. Surprisingly, telomerase-expressing embryonic stem cells engineered to carry any of the three most frequent TERT promoter mutations showed only a modest increase in TERT transcription with no impact on telomerase activity. However, upon differentiation into somatic cells, which normally silence telomerase, cells with TERT promoter mutations failed to silence TERT expression, resulting in increased telomerase activity and aberrantly long telomeres. Thus, TERT promoter mutations are sufficient to overcome the proliferative barrier imposed by telomere shortening without additional tumor-selected mutations. These data establish that TERT promoter mutations can promote immortalization and tumorigenesis of incipient cancer cells.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • The Saccharomyces cerevisiae TRT2 tRNAThr gene upstream of STE6 is a barrier to repression in MATalpha cells and exerts a potential tRNA position effect in MATa cells. 15459290

    A growing body of evidence suggests that genes transcribed by RNA polymerase III exhibit multiple functions within a chromosome. While the predominant function of these genes is the synthesis of RNA molecules, certain RNA polymerase III genes also function as genomic landmarks. Transfer RNA genes are known to exhibit extra-transcriptional activities such as directing Ty element integration, pausing of replication forks, overriding nucleosome positioning sequences, repressing neighboring genes (tRNA position effect), and acting as a barrier to the spread of repressive chromatin. This study was designed to identify other tRNA loci that may act as barriers to chromatin-mediated repression, and focused on TRT2, a tRNA(Thr) adjacent to the STE6 alpha2 operator. We show that TRT2 acts as a barrier to repression, protecting the upstream CBT1 gene from the influence of the STE6 alpha2 operator in MATalpha cells. Interestingly, deletion of TRT2 results in an increase in CBT1 mRNA levels in MATa cells, indicating a potential tRNA position effect. The transcription of TRT2 itself is unaffected by the presence of the alpha2 operator, suggesting a hierarchy that favors assembly of the RNA polymerase III complex versus assembly of adjacent alpha2 operator-mediated repressed chromatin structures. This proposed hierarchy could explain how tRNA genes function as barriers to the propagation of repressive chromatin.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • Cervicothalamic tract termination: a reexamination and comparison with the distribution of monoclonal antibody Cat-301 immunoreactivity in the cat. 9833685

    The distribution of cervicothalamic tract (CTT) terminations, labeled with anterogradely transported tracers (WGA-HRP or biotinylated dextran amine) injected into the lateral cervical nucleus of cats, was compared with the distribution of immunoreactivity for a cell-surface antigen detected with the monoclonal antibody Cat-301. The most abundant CTT termination is present in the ventrobasal complex (VB), mainly in its lateral part (VPL) and only sparsely in its medial part (VPM). In the VPL, the CTT preferentially terminates in a Cat-301-sparse peripheral rim of the nucleus and in between its lateral and medial subdivisions (VPLI and VPLm). CTT terminations are sparse in the central Cat-301-dense parts of the VPL. In the ventral periphery of VB (VBvp), situated in between the VPL/VPM and the external medullary lamina, thin CTT fibers with spaced varicosities is seen among the large fibers of passage. The VBvp is essentially devoid of Cat-301 immunoreactivity. Scattered clusters of CTT termination are also seen caudal and dorsal to the VB in the medial division of the posterior complex (POm), which is virtually devoid of Cat-301 immunoreactivity. In the caudal thalamus, dense and focused CTT termination is present in the medial extension of the magnocellular medial geniculate nucleus (MGmc) but absent from its main lateral part. The termination in the MGmc is centered upon clusters of cells displaying dense Cat-301 immunoreactivity. The present study demonstrates previously unrecognized or unconfirmed CTT terminations in the VPM and in the VBvp, and confirm previously described projections to the VPL, POm and MGmc. The preferential termination of the CTT in the Cat-301-sparse peripheral region of the VPL demonstrates that the CTT is related to a chemically defined VPL compartment. In the light of previous data, this observation suggests that the CTT is related to one or more thalamocortical channels that are partly or completely separate from that (those) activated through the dorsal column-medial lemniscal pathway. The organization of the thalamocortical channel(s) activated through the CTT remains to be elucidated. In contrast to the termination in the VPL, CTT termination in the medial MGmc is focused to clusters of Cat-301 immunolabeled cells. The significance of this difference between CTT recipient cells in the VPL and in the MGmc is unclear.
    Document Type:
    Reference
    Product Catalog Number:
    MAB5284
    Product Catalog Name:
    Anti-Chondroitin Sulfate Proteoglycan Antibody, Brain (core protein), clone Cat-301
  • Polypyrimidine tract binding protein blocks the 5' splice site-dependent assembly of U2AF and the prespliceosomal E complex. 16109373

    Polypyrimidine tract binding protein (PTB) represses some alternatively spliced exons by direct occlusion of splice sites. In repressing the splicing of the c-src N1 exon, we find that PTB acts by a different mechanism. PTB does not interfere with U1 snRNP binding to the N1 5' splice site. Instead, PTB prevents formation of the prespliceosomal early (E) complex across the intervening intron by preventing the assembly of the splicing factor U2AF on the 3' splice site of exon 4. When the unregulated 5' splice site of the upstream exon 3 is present, U2AF binding is restored and splicing between exons 3 and 4 proceeds in spite of the N1 exon bound PTB. Thus, rather than directly blocking the N1 splice sites, PTB prevents the 5' splice site-dependent assembly of U2AF into the E complex. This mechanism likely occurs in many other alternative exons.
    Document Type:
    Reference
    Product Catalog Number:
    MABE986
    Product Catalog Name:
    Anti-PTB Antibody, clone BB7
  • The influence of trout cardiac troponin I and PKA phosphorylation on the Ca2+ affinity of the cardiac troponin complex. 21613513

    The trout heart is 10-fold more sensitive to Ca(2+) than the mammalian heart. This difference is due, in part, to cardiac troponin C (cTnC) from trout having a greater Ca(2+) affinity than human cTnC. To determine what other proteins are involved, we cloned cardiac troponin I (cTnI) from the trout heart and determined how it alters the Ca(2+) affinity of a cTn complex containing all mammalian components (mammalian cTn). Ca(2+) activation of the complex was characterized using a human cTnC mutant that contains anilinonapthalenesulfote iodoacetamide attached to Cys53. When the cTn complex containing labeled human cTnC was titrated with Ca(2+), its fluorescence changed, reaching an asymptote upon saturation. Our results reveal that trout cTnI lacks the N-terminal extension found in cTnI from all other vertebrate groups. This protein domain contains two targets (Ser23 and Ser24) for protein kinase A (PKA) and protein kinase C. When these are phosphorylated, the rate of cardiomyocyte relaxation increases. When rat cTnI in the mammalian cTn complex was replaced with trout cTnI, the Ca(2+) affinity was increased ∼1.8-fold. This suggests that trout cTnI contributes to the high Ca(2+) sensitivity of the trout heart. Treatment of the two cTn complexes with PKA decreased the Ca(2+) affinity of both complexes. However, the change for the complex containing rat cTnI was 2.2-fold that of the complex containing trout cTnI. This suggests that the phosphorylation of trout cTnI does not play as significant a role in regulating cTn function in trout.
    Document Type:
    Reference
    Product Catalog Number:
    AP106P
    Product Catalog Name:
    Rabbit Anti-Goat IgG Antibody, HRP conjugate
  • Early feeding of rainbow trout ( Oncorhynchus mykiss) with methionine-deficient diet over a 2 week period: consequences for liver mitochondria in juveniles 31488624

    Methionine is a key factor in modulating the cellular availability of the main biological methyl donor S-adenosylmethionine (SAM), which is required for all biological methylation reactions including DNA and histone methylation. As such, it represents a potential critical factor in nutritional programming. Here, we investigated whether early methionine restriction at first feeding could have long-term programmed metabolic consequences in rainbow trout. For this purpose, trout fry were fed with either a control diet (C) or a methionine-deficient diet (MD) for 2 weeks from the first exogenous feeding. Next, fish were subjected to a 5 month growth trial with a standard diet followed by a 2 week challenge (with the MD or C diet) to test the programming effect of the early methionine restriction. The results showed that, whatever the dietary treatment of fry, the 2 week challenge with the MD diet led to a general mitochondrial defect associated with an increase in endoplasmic reticulum stress, mitophagy and apoptosis, highlighting the existence of complex cross-talk between these different functions. Moreover, for the first time, we also observed that fish fed the MD diet at the first meal later exhibited an increase in several critical factors of mitophagy, hinting that the early nutritional stimulus with methionine deficiency resulted in long-term programming of this cell function. Together, these data extend our understanding of the role of dietary methionine and emphasize the potential for this amino acid in the application of new feeding strategies, such as nutritional programming, to optimize the nutrition and health of farmed fish.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple