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Aptamers are short single-stranded nucleic acid sequences capable of binding to target molecules in a way similar to antibodies. Due to various advantages such as prolonged shelf life, low batch to batch variation, low/no immunogenicity, freedom to incorporate chemical modification for enhanced stability and targeting capacity, aptamers quickly found their potential in diverse applications ranging from therapy, drug delivery, diagnosis, and functional genomics to bio-sensing. Aptamers are generated by a process called SELEX. However, the current overall success rate of SELEX is far from being satisfactory, and still presents a major obstacle for aptamer-based research and application. The need for an efficient selection strategy consisting of defined procedures to deal with a wide variety of targets is significantly important. In this work, by analyzing key aspects of SELEX including initial library design, target preparation, PCR optimization, and single strand DNA separation, we provide a comprehensive analysis of individual steps to facilitate researchers intending to develop personalized protocols to address many of the obstacles in SELEX. In addition, this review provides suggestions and opinions for future aptamer development procedures to address the concerns on key SELEX steps, and post-SELEX modifications., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

The Australian paralysis tick (Ixodes holocyclus) secretes neuropathic toxins into saliva that induce host paralysis. Salivary glands and viscera were dissected from fully engorged female I. holocyclus ticks collected from dogs and cats with paralysis symptoms. cDNA from both tissue samples were sequenced using Illumina HiSeq 100 bp pair end read technologies. Unique and non-redundant holocyclotoxin sequences were designated as HT2-HT19, as none were identical to the previously described HT1. Specific binding to rat synaptosomes was determined for synthetic HTs, and their neurotoxic capacity was determined by neonatal mouse assay. They induced a powerful paralysis in neonatal mice, particularly HT4 which produced rapid and strong respiratory distress in all animals tested. This is the first known genomic database developed for the Australian paralysis tick. The database contributed to the identification and subsequent characterization of the holocyclotoxin family that will inform the development of novel anti-paralysis control methods., (Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.)

The genome of the cattle tick Rhipicephalus microplus, an ectoparasite with global distribution, is estimated to be 7.1Gbp in length and consists of approximately 70% repetitive DNA. We report the draft assembly of a tick genome that utilized a hybrid sequencing and assembly approach to capture the repetitive fractions of the genome. Our hybrid approach produced an assembly consisting of 2.0Gbp represented in 195,170 scaffolds with a N50 of 60,284bp. The Rmi v2.0 assembly is 51.46% repetitive with a large fraction of unclassified repeats, short interspersed elements, long interspersed elements and long terminal repeats. We identified 38,827 putative R. microplus gene loci, of which 24,758 were protein coding genes (≥100 amino acids). OrthoMCL comparative analysis against 11 selected species including insects and vertebrates identified 10,835 and 3,423 protein coding gene loci that are unique to R. microplus or common to both R. microplus and Ixodes scapularis ticks, respectively. We identified 191 microRNA loci, of which 168 have similarity to known miRNAs and 23 represent novel miRNA families. We identified the genomic loci of several highly divergent R. microplus esterases with sequence similarity to acetylcholinesterase. Additionally we report the finding of a novel cytochrome P450 CYP41 homolog that shows similar protein folding structures to known CYP41 proteins known to be involved in acaricide resistance., (Copyright © 2017 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.)