Biology subjects

Smith, A. A.

Publications and source records attributed to Smith, A. A..

3 recordsLinked to original sources

bioRxiv2022

Function and evolution of aquaporin IsAQP1 in the Lyme disease vector Ixodes scapularis

Ticks are important vectors of pathogenic viruses, bacteria, and protozoans to humans, wildlife, and domestic animals. Due to their life cycle, ticks face significant challenges related to water homeostasis. When blood-feeding they must excrete water and ions, but when off-host (for stretches lasting several months) they must conserve water to avoid desiccation. Aquaporins (AQPs), a family of membrane-bound water channels, are key players in osmoregulation in many animals but remain poorly characterized in ticks. Here, we bioinformatically identified AQP-like genes from the deer tick Ixodes scapularis and used phylogenetic approaches to map the evolution of the aquaporin gene family in arthropods. We find that most arachnid AQP-like sequences (including those of I. scapularis) form a monophyletic group clustered within aquaglycerolporins (GLPs) from bacteria to vertebrates. This gene family is absent from insects, revealing divergent evolutionary paths for AQPs in different hematophagous arthropods. We next sequenced the full-length cDNA of I. scapularis aquaporin 1 (IsAQP1) and expressed it heterologously in Xenopus oocytes to functionally characterize its permeability to water and solutes. We additionally examined IsAQP1 expression across different life stages and adult female tissues. We found IsAQP1 to be an efficient water channel with salivary gland-specific expression, implying its function may be closely tied to osmoregulation during blood-feeding. Its functional properties were unique: unlike most GLPs, IsAQP1 has low glycerol permeability, and unlike most AQPs, it is insensitive to mercury. Together, our results suggest IsAQP1 plays an important role in tick water balance during blood feeding and may hold promise as a target for novel vector control efforts. Graphical TOC/Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY eTOCIsAQP1, an aquaporin found in the black legged tick (Ixodes scapularis), is a functional water channel with low permeability to glycerol. In a phylogenetic analysis of 176 sequences from 48 arachnid species, most tick and other arachnid AQP-like genes formed a monophyletic clade nested within aquaglyceroporins (GLPs). IsAQP1 shows salivary-gland specific expression in adult females--with highest expression in unfed females--suggesting a role in water balance during blood feeding.

genetics↗

bioRxiv2021

A Novel Power-Amplified Jumping Behavior in Larval Beetles (Coleoptera: Laemophloeidae)

Larval insects use many methods for locomotion. Here we describe a previously unknown jumping behavior in a group of beetle larvae (Coleoptera: Laemophloeidae). We analyze and describe this behavior in Laemophloeus biguttatus and provide information on similar observations for another laemophloeid species, Placonotus testaceus. Laemophloeus biguttatus larvae prelude jumps by arching their body while gripping the substrate with their legs over a period of 0.22 {+/-} 0.17s. This is followed by a rapid ventral curling of the body after the larvae releases its grip that launches them into the air. Larvae reached takeoff velocities of 0.47 {+/-} 0.15 m s-1 and traveled 11.2 {+/-} 2.8 mm (1.98 {+/-} 0.8 body lengths) horizontally and 7.9 {+/-} 4.3 mm (1.5 {+/-} 0.9 body lengths) vertically during their jumps. Conservative estimates of power output revealed that not all jumps can be explained by direct muscle power alone, suggesting Laemophloeus biguttatus uses a latch-mediated spring actuation mechanism (LaMSA) in which interaction between the larvaes legs and the substrate serves as the latch. MicroCT scans and SEM imaging of larvae did not reveal any notable modifications that would aid in jumping. Although more in-depth experiments could not be performed to test hypotheses on the function of these jumps, we posit that this behavior is used for rapid locomotion which is energetically more efficient than crawling the same distance to disperse from their ephemeral habitat. We also summarize and discuss jumping behaviors among insect larvae for additional context of this behavior in laemophloeid beetles.

animal behavior and cognition↗

bioRxiv2019

A semi-automated technique for adenoma quantification in the ApcMin mouse using FeatureCounter

Colorectal cancer is a major contributor to death and disease worldwide. The ApcMin mouse is a widely used model of intestinal neoplasia, as it carries a mutation also found in human colorectal cancers. However, the method most commonly used to quantify tumour burden in these mice is manual adenoma counting, which is time consuming and poorly suited to standardization across different laboratories. We describe a method to produce suitable photographs of the small intestine, process them with an ImageJ macro, FeatureCounter, which automatically locates image features potentially corresponding to adenomas, and a machine learning pipeline to identify and quantify them. Compared to a manual method, the specificity (or True Negative Rate, TNR) and sensitivity (or True Positive Rate, TPR) of this method in detecting adenomas are similarly high at about 80% and 87%, respectively. Importantly, total adenoma area measures derived from the automatically-called tumours were just as capable of distinguishing high-burden from low-burden mice as those established manually. Overall, our strategy is quicker, helps control experimenter bias and yields a greater wealth of information about each tumour, thus providing a convenient route to getting consistent and reliable results from a study.

cancer biology↗