Multi-locus phylogeographic and population genetic analysis of Anolis carolinensis: historical demography of a genomic model species

The green anole (Anolis carolinensis) has been widely used as an animal model in physiology and neurobiology but has recently emerged as an important genomic model. The recent sequencing of its genome has shed new light on the evolution of vertebrate genomes and on the process that govern species diversification. Surprisingly, the patterns of genetic diversity within natural populations of this widespread and abundant North American lizard remain relatively unknown. In the present study, we use 10 novel nuclear DNA sequence loci (N?=?62 to 152) and one mitochondrial locus (N?=?226) to delimit green anole populations and infer their historical demography. We uncovered four evolutionarily distinct and geographically restricted lineages of green anoles using phylogenetics, bayesian clustering, and genetic distance methods. Molecular dating indicates that these lineages last shared a common ancestor ～2 million years ago. Summary statistics and analysis of the frequency distributions of DNA polymorphisms strongly suggest range-wide expansions in population size. Using Bayesian Skyline Plots, we inferred the timing of population size expansions, which differ across lineages, and found evidence for a relatively recent and rapid westward expansion of green anoles across the Gulf Coastal Plain during the mid-Pleistocene. One surprising result is that the distribution of genetic diversity is not consistent with a latitudinal shift caused by climatic oscillations as is observed for many co-distributed taxa. This suggests that the most recent Pleistocene glacial cycles had a limited impact on the geographic distribution of the green anole at the northern limits of its range.     

Risk factors contributing to symptomatic plate removal in maxillofacial trauma patients

This study analyzed the fate of plates used to correct maxillofacial injuries and defined risk factors that eventually resulted in plate removal. The outpatient clinic files of 108 patients treated with rigid internal fixation after maxillofacial trauma were reviewed. Study variables included age, sex, trauma circumstances, diagnosis, type of fracture, approach to the facial skeleton, presence of teeth in the line of fracture, plate material, site of plates, and reasons for plate removal. Of 204 plates used for fixation, 44 plates (22 percent) were removed. When all factors were considered together, only fracture diagnosis (mandibular body and angle) and plate location (mandibular body and angle) were statistically significant. Only when each factor was considered separately, the approach to the facial skeleton (intraoral) and the type of fracture (comminuted and compound fractures) were statistically associated with plate removal. Selection of favorable plate location, the extraoral approach, and vigilant infection control may reduce plate removal in patients with maxillofacial injuries. Special attention should be given to compound and comminuted fractures of the mandibular body and angle.     

Rapid, stimulation-induced reduction of C12-resorufin in motor nerve terminals: linkage to mitochondrial metabolism

The Alamar blue (resazurin) assay of cell viability monitors the irreversible reduction of non-fluorescent resazurin to fluorescent resorufin. This study focused on the reversible reduction of C₁₂-resorufin to non-fluorescent C₁₂-dihydroresorufin in motor nerve terminals innervating lizard intercostal muscles. Resting C₁₂-resorufin fluorescence decreased when the activity of the mitochondrial electron transport chain (ETC) was accelerated with carbonyl cyanide m -chloro phenyl hydrazone, and increased when ETC activity was inhibited with cyanide. Trains of action potentials (50 Hz for 20–50 s), which reversibly decreased NADH fluorescence and partially depolarized the mitochondrial membrane potential, produced a reversible decrease in C₁₂-resorufin fluorescence which had a similar time course. The stimulation-induced decrease in C₁₂-resorufin fluorescence was blocked by inhibitors of ETC complexes I, III, and IV and by carbonyl cyanide m -chloro phenyl hydrazone, but not by inhibiting mitochondrial ATP synthesis with oligomycin. Mitochondrial depolarization and the decreases in C₁₂-resorufin and NADH fluorescence depended on Ca²⁺ influx into the terminal, but not on vesicular transmitter release. These results suggest that the reversible reduction of C₁₂-resorufin in stimulated motor nerve terminals is linked, directly or indirectly, to the reversible oxidation of NADH and to Ca²⁺ influx into mitochondria, and provides an assay for rapid changes in motor terminal metabolism.     

Spatial patterns of sterile Mediterranean fruit fly dispersal

The success of the sterile insect technique (SIT) for the control of the Mediterranean fruit fly or medfly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), depends largely on the ability of sterile flies to spread in the target area and compete with the wild males for wild females. Our objectives in the present study were three‐fold: (1) to evaluate the dispersal ability of sterile male medflies and compare their spatial dispersion patterns with that of wild males, (2) to evaluate how different release methods affect subsequent spatial dispersal, and (3) to determine whether manipulating the pre‐release diet of sterile males affects their dispersal. To achieve these objectives, we conducted three experiments in the field where we quantified and analyzed the spatial and temporal dispersal patterns of sterile medflies and the dispersion of resident wild males. Overall, ca. 5% of the released sterile flies were recaptured 100 m from the release point, and ca. 2% were recaptured 200 m from the release point. The released flies rarely survived longer than 5–7 days. We repeatedly found that the spatial dispersion patterns of sterile males significantly correlated with those of wild males. Release methods strongly affected subsequent fly dispersal in the field as significantly more flies were recaptured following a scattered release vs. a central one. Finally, we show that enriching sterile fly pre‐release diet with protein did not affect subsequent dispersal in the field. We conclude that sterile males are able to match the dispersion patterns of wild males, an outcome that is highly important for SIT success. Large releases from central points distant from each other may leave many areas uncovered. Accordingly, scattered releases, repeated twice a week, will provide better coverage of all available aggregations sites. The spatial performance of protein‐fed males suggests that pre‐release diet amendments may be used without detriment as a sexual stimulant in SIT programs.     

High-throughput assessment of microRNA activity and function using microRNA sensor and decoy libraries

We introduce two large-scale resources for functional analysis of microRNA (miRNA): a decoy library for inhibiting miRNA function and a sensor library for monitoring microRNA activity. To take advantage of the sensor library, we developed a high-throughput assay called Sensor-seq to simultaneously quantify the activity of hundreds of miRNAs. Using this approach, we show that only the most abundant miRNAs in a cell mediate target suppression. Over 60% of detected miRNAs had no discernible activity, which indicated that the functional 'miRNome' of a cell is considerably smaller than currently inferred from profiling studies. Moreover, some highly expressed miRNAs exhibited relatively weak activity, which in some cases correlated with a high target-to-miRNA ratio or increased nuclear localization of the miRNA. Finally, we show that the miRNA decoy library can be used for pooled loss-of-function studies. These tools are valuable resources for studying miRNA biology and for miRNA-based therapeutics.     

False-positive coliform reaction mediated by Aeromonas in the Colilert defined substrate technology system

The Colilert defined substrate technology system allows specific, one-step detection of both coliforms and Escherichia coli while claiming to suppress the influence of non-coliform heterotrophs. The Colilert assay was examined in order to determine whether organisms from the genus Aeromonas could interfere and cause production of a false-positive coliform result as aquatic Aeromonas are known to constitute a fraction of the heterotrophic population found in drinking water. Results obtained clearly demonstrate that Aeromonas sp. can elicit a positive coliform type reaction at very low densities. Cell suspensions as low as 1 × 10¹ cells 10 ml⁻¹ were observed to yield a positive reaction using Colilert reagent 4 weeks short of shelf-life expiry. Use of aged Colilert for monitoring water quality could lead to over-estimation of coliforms as Aeromonas have been identified in many treated drinking water supplies.