Books by Stephen Mackessy
REPORTS www.BioTechniques.com REPORTS Reports Vol. 65 | 2018 No. 6 339 DNA barcoding provides a r... more REPORTS www.BioTechniques.com REPORTS Reports Vol. 65 | 2018 No. 6 339 DNA barcoding provides a rapid and effi cient means to determine taxonomic status of specimens using one or a few common genetic markers. This technique involves amplifying and sequencing relatively short regions of DNA (e.g., cytochrome b in animals) from a large number of organisms that display a high level of variation between species, but not within species. These reference genetic markers are used to identify species, to characterize new species, and ultimately to develop a large-scale system of classifi cation that is broadly applicable across a wide variety of taxa [1, 2]. Although DNA barcoding lacks the depth of information acquired from sequencing many genetic regions, it compensates for this with broad applicability and high throughput potential across highly divergent species. Ultimately, the success of DNA barcoding relies on the depth and breadth of a genetic library of reference sequences. Mitochondrial regions cytochrome C oxidase I (COI) and cytochrome b (cyt b) DNA barcoding is a simple technique used to develop a large-scale system of classifi cation that is broadly applicable across a wide variety of taxa. DNA-based analysis of snake venoms can provide a system of clas-sifi cation independent of currently accepted taxonomic relationships by generating DNA barcodes spe-cifi c to each venom sample. DNA purifi cation from dried snake ven-oms has previously required large amounts of starting material, has resulted in low yields and inconsistent amplification, and was possible with front-fanged snakes only. Here, we present a modi-fi ed DNA extraction protocol applied to venoms of both front-and rear-fanged snakes that requires signifi cantly less starting material (1 mg) and yields suffi cient amounts of DNA for successful PCR amplifi cation of regions commonly used for DNA barcoding. Crotalus simus tzabcan METHOD SUMMARY Modifications to a commercial DNA extraction kit (cultured cells protocol) allow purification of DNA from snake venoms for DNA-barcoding efforts. The outlined protocol uses ~100x less venom than previously possible and is applicable to both front-and rear-fanged venomous snakes. .
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Toxins, 2018
The use of-omics technologies allows for the characterization of snake venom composition at a fas... more The use of-omics technologies allows for the characterization of snake venom composition at a fast rate and at high levels of detail. In the present study, we investigated the protein content of Red-headed Krait (Bungarus flaviceps) venom. This analysis revealed a high diversity of snake venom protein families, as evidenced by high-throughput mass spectrometric analysis. We found all six venom protein families previously reported in a transcriptome study of the venom gland of B. flaviceps, including phospholipases A 2 (PLA 2 s), Kunitz-type serine proteinase inhibitors (KSPIs), three-finger toxins (3FTxs), cysteine-rich secretory proteins (CRISPs), snaclecs, and natriuretic peptides. A combined approach of automated database searches and de novo sequencing of tandem mass spectra, followed by sequence similarity searches, revealed the presence of 12 additional toxin families. De novo sequencing alone was able to identify 58 additional peptides, and this approach contributed significantly to the comprehensive description of the venom. Abundant protein families comprise 3FTxs (22.3%), KSPIs (19%), acetylcholinesterases (12.6%), PLA 2 s (11.9%), venom endothelial growth factors (VEGFs, 8.4%), nucleotidases (4.3%), and C-type lectin-like proteins (snaclecs, 3.3%); an additional 11 toxin families are present at significantly lower concentrations, including complement depleting factors, a family not previously detected in Bungarus venoms. The utility of a multifaceted approach toward unraveling the proteome of snake venoms, employed here, allowed detection of even minor venom components. This more in-depth knowledge of the composition of B. flaviceps venom facilitates a better understanding of snake venom molecular evolution, in turn contributing to more effective treatment of krait bites. Key Contribution: We describe the deep proteomic mining of Bungarus flaviceps venom that allowed us to identify the presence of 18 protein families, including several low abundance toxins. Utilization of this approach facilitates the understanding of the evolution of venom complexity and the differential expression of dominant venom toxins by allowing detection/identification of even trace venom components.
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Papers by Stephen Mackessy
Journal of Proteome Research, 2019
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BMC Biology, Jun 6, 2023
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Genome Biology and Evolution, Jul 22, 2022
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Toxicon, Nov 1, 1996
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Genome Research, Mar 21, 2019
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Journal of Proteome Research, Aug 2, 2006
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Toxicon, Aug 1, 2012
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Toxicon, Jul 1, 2011
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Analytical science advances, Feb 1, 2023
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Biological Reviews
ABSTRACTConvergence is the phenomenon whereby similar phenotypes evolve independently in differen... more ABSTRACTConvergence is the phenomenon whereby similar phenotypes evolve independently in different lineages. One example is resistance to toxins in animals. Toxins have evolved many times throughout the tree of life. They disrupt molecular and physiological pathways in target species, thereby incapacitating prey or deterring a predator. In response, molecular resistance has evolved in many species exposed to toxins to counteract their harmful effects. Here, we review current knowledge on the convergence of toxin resistance using examples from a wide range of toxin families. We explore the evolutionary processes and molecular adaptations driving toxin resistance. However, resistance adaptations may carry a fitness cost if they disrupt the normal physiology of the resistant animal. Therefore, there is a trade‐off between maintaining a functional molecular target and reducing toxin susceptibility. There are relatively few solutions that satisfy this trade‐off. As a result, we see a sma...
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Handbook of Venoms and Toxins of Reptiles, 2021
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Toxicon, 2020
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Wilderness & Environmental Medicine, 2020
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Toxicon, 2018
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Molecular Biology and Evolution, 2020
Meiotic recombination in vertebrates is concentrated in hotspots throughout the genome. The locat... more Meiotic recombination in vertebrates is concentrated in hotspots throughout the genome. The location and stability of hotspots have been linked to the presence or absence of PRDM9, leading to two primary models for hotspot evolution derived from mammals and birds. Species with PRDM9-directed recombination have rapid turnover of hotspots concentrated in intergenic regions (i.e., mammals), whereas hotspots in species lacking PRDM9 are concentrated in functional regions and have greater stability over time (i.e., birds). Snakes possess PRDM9, yet virtually nothing is known about snake recombination. Here, we examine the recombination landscape and test hypotheses about the roles of PRDM9 in rattlesnakes. We find substantial variation in recombination rate within and among snake chromosomes, and positive correlations between recombination rate and gene density, GC content, and genetic diversity. Like mammals, snakes appear to have a functional and active PRDM9, but rather than being dir...
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Toxicon, 2019
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Proceedings of the Royal Society B: Biological Sciences, 2018
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Books by Stephen Mackessy
Papers by Stephen Mackessy