Xenopus: An ideal system for chemical genetics

Chemical genetics, or chemical biology, has become an increasingly powerful method for studying biological processes. The main objective of chemical genetics is the identification and use of small molecules that act directly on proteins, allowing rapid and reversible control of activity. These compounds are extremely powerful tools for researchers, particularly in biological systems that are not amenable to genetic methods. In addition, identification of small molecule interactions is an important step in the drug discovery process. Increasingly, the African frog Xenopus is being used for chemical genetic approaches. Here, we highlight the advantages of Xenopus as a first-line in vivo model for chemical screening as well as for testing reverse engineering approaches. genesis 50:207–218, 2012. © 2012 Wiley Periodicals, Inc

Spasmogenic, Spasmolytic and Chemical Screening of Cigarettes

The aqueous and ethanolic extracts derived from cigarettes (Morven Gold) were screened for chemicals, spasmogenic and spasmolytic activities. Aqueous extract showed strong relaxant activity that is, 92% against KCl induced contractions while ethanolic extract was found to be moderately spasmolytic (70%). Ethanolic extract was also found to have a strong spasmogenic activity, while aqueous extract depress the spasmogenic activity of pilocarpine induced contractions. Thus, the ethanoilc extract was found to be more efficient for spasmogenic activity while aqueous extract was noted to be more efficient for spasmolytic activity. The chemicals found in sufficient quantity in both the extracts were saponin and glycosides. It was also noted that tannins were present only in ethanolic extract in excess quantity. The research indicated clearly that cigarette is a good spasmolytic agent while the ethanolic extract has spasmogenic activity. Further studies are necessary to elucidate its exact mechanism of action.Keywords:Sapsmogenic, spasmolytic, chemical screening, cigaretteAfrican Journal of Biotechnology Vol. 12(39), pp. 5799-580

The Value of Chemical Screening Profiles on Blood

Chemical screening profiles on blood specimens are designed to yield information that may lead to new and additional clinical diagnoses, to revision of clinically established diagnoses, to confirmed impressions of the physician and to following the course of diseases during a patient\u27s hospitalization. Screening profiles on blood are designed to indicate disease of the liver, kidney, heart, striated muscle and other organs; they may be helpful in the diagnosis of anemia, diabetes mellitus, gout, congestive heart failure, osteomalacia, and hyperlipidemia, hyperparathyroidism and other diseases. When these screening profiles were first introduced, there was widespread skepticism among physicians as to their value and their yield and some skepticism remains as to the usefulness of a broad spectrum of laboratory tests

In Vivo Chemical Screening for Modulators of Hematopoiesis and Hematological Diseases

In vivo chemical screening is a broadly applicable approach not only for dissecting genetic pathways governing hematopoiesis and hematological diseases, but also for finding critical components in those pathways that may be pharmacologically modulated. Both high-throughput chemical screening and facile detection of blood-cell-related phenotypes are feasible in embryonic/larval zebrafish. Two recent studies utilizing phenotypic chemical screens in zebrafish have identified several compounds that promote hematopoietic stem cell formation and reverse the hematopoietic phenotypes of a leukemia oncogene, respectively. These studies illustrate efficient drug discovery processes in zebrafish and reveal novel biological roles of prostaglandin E2 in hematopoietic and leukemia stem cells. Furthermore, the compounds discovered in zebrafish screens have become promising therapeutic candidates against leukemia and included in a clinical trial for enhancing hematopoietic stem cells during hematopoietic cell transplantation

Considerations for designing chemical screening strategies in plant biology

Traditionally, biologists regularly used classical genetic approaches to characterize and dissect plant processes. However, this strategy is often impaired by redundancy, lethality or pleiotropy of gene functions, which prevent the isolation of viable mutants. The chemical genetic approach has been recognized as an alternative experimental strategy, which has the potential to circumvent these problems. It relies on the capacity of small molecules to modify biological processes by specific binding to protein target(s), thereby conditionally modifying protein function(s), which phenotypically resemble mutation(s) of the encoding gene(s). A successful chemical screening campaign comprises three equally important elements: (1) a reliable, robust, and quantitative bioassay, which allows to distinguish between potent and less potent compounds, (2) a rigorous validation process for candidate compounds to establish their selectivity, and (3) an experimental strategy for elucidating a compound's mode of action and molecular target. In this review we will discuss details of this general strategy and additional aspects that deserve consideration in order to take full advantage of the power provided by the chemical approach to plant biology. In addition, we will highlight some success stories of recent chemical screenings in plant systems, which may serve as teaching examples for the implementation of future chemical biology projects

Discovery of Protein-Protein Interaction Inhibitors by Integrating Protein Engineering and Chemical Screening Platforms

Protein-protein interactions (PPIs) govern intracellular life, and identification of PPI inhibitors is challenging. Roadblocks in assay development stemming from weak binding affinities of natural PPIs impede progress in this field. We postulated that enhancing binding affinity of natural PPIs via protein engineering will aid assay development and hit discovery. This proof-of-principle study targets PPI between linear ubiquitin chains and NEMO UBAN domain, which activates NF-κB signaling. Using phage display, we generated ubiquitin variants that bind to the functional UBAN epitope with high affinity, act as competitive inhibitors, and structurally maintain the existing PPI interface. When utilized in assay development, variants enable generation of robust cell-based assays for chemical screening. Top compounds identified using this approach directly bind to UBAN and dampen NF-κB signaling. This study illustrates advantages of integrating protein engineering and chemical screening in hit identification, a development that we anticipate will have wide application in drug discovery

ATR-FTIR chemical screening for adulterants and sugar characterisation in honeys

The search for improvements in honey analysis is an important topic due to the relevance that adulterations and variations of sugar composition have in this food. Attenuated Total Reflectance Fourier Transform InfraRed spectroscopy (ATR-FTIR) is a reliable and fast analytical instrumentation for analysis of liquids, semi-solids and solids, which is currently used in food chemistry for qualitative and quantitative investigations. This work is aimed to build a fast analytical method, using ATR-FTIR and Partial Least Square (PLS) chemometric tool, to quantitative determination of glucose, fructose and sucrose present in honeys. We analyzed 25 honeys from Trentino and Sicily and a significant spectral range from the whole ATR-FTIR spectra were selected. Then a PLS multivariate calibration model was built by using mixtures of glucose, fructose and sucrose at various concentration. Samples for cross-validation were selected, thereby allowing quantitative evaluation of glucose, fructose and sucrose in all samples. Furthermore, a representative number of honeys were mixed with common adulterant syrups to simulate adulteration procedures and to verify the reliability of the ATR-FTIR technique in recognizing them. Preliminary results revealed not only the quantitative reliability of ATR-FTIR spectroscopy in the evaluation of sugars in honeys, but also its ability in recognizing honey adulteration

Plant chemical genetics : from phenotype-based screens to synthetic biology

The treatment of a biological system with small molecules to specifically perturb cellular functions is commonly referred to as chemical biology. Small molecules are used commercially as drugs, herbicides, and fungicides in different systems, but in recent years they are increasingly exploited as tools for basic research. For instance, chemical genetics involves the discovery of small-molecule effectors of various cellular functions through screens of compound libraries. Whereas the drug discovery field has largely been driven by target-based screening approaches followed by drug optimization, chemical genetics in plant systems tends to be fueled by more general phenotype-based screens, opening the possibility to identify a wide range of small molecules that are not necessarily directly linked to the process of interest. Here, we provide an overview of the current progress in chemical genetics in plants, with a focus on the discoveries regarding small molecules identified in screens designed with a basic biology perspective. We reflect on the possibilities that lie ahead and discuss some of the potential pitfalls that might be encountered upon adopting a given chemical genetics approach