Monte L. Thies

Diffusible iodine-based contrast-enhanced computed tomography (diceCT) : an emerging tool for rapid, high-resolution, 3-D imaging of metazoan soft tissues.

Morphologists have historically had to rely on destructive procedures to visualize the three‐dimensional (3‐D) anatomy of animals. More recently, however, non‐destructive techniques have come to the forefront. These include X‐ray computed tomography (CT), which has been used most commonly to examine the mineralized, hard‐tissue anatomy of living and fossil metazoans. One relatively new and potentially transformative aspect of current CT‐based research is the use of chemical agents to render visible, and differentiate between, soft‐tissue structures in X‐ray images. Specifically, iodine has emerged as one of the most widely used of these contrast agents among animal morphologists due to its ease of handling, cost effectiveness, and differential affinities for major types of soft tissues. The rapid adoption of iodine‐based contrast agents has resulted in a proliferation of distinct specimen preparations and scanning parameter choices, as well as an increasing variety of imaging hardware and software preferences. Here we provide a critical review of the recent contributions to iodine‐based, contrast‐enhanced CT research to enable researchers just beginning to employ contrast enhancement to make sense of this complex new landscape of methodologies. We provide a detailed summary of recent case studies, assess factors that govern success at each step of the specimen storage, preparation, and imaging processes, and make recommendations for standardizing both techniques and reporting practices. Finally, we discuss potential cutting‐edge applications of diffusible iodine‐based contrast‐enhanced computed tomography (diceCT) and the issues that must still be overcome to facilitate the broader adoption of diceCT going forward.

Cross-placental transfer of organochlorine pesticides in mexican free-tailed bats from Oklahoma and New Mexico

A total of 41 pregnant Mexican free-tailed bats (Tadarida brasiliensis) were collected from Carlsbad Caverns, New Mexico, and Vickery Cave, Oklahoma, in May and June 1990 and May 1991 for organochlorine pesticide analyses. Residues of p,p′-DDE were detected by gas chromatography in 40 embryos at levels highly correlated with brain concentrations (r=0.496) but were not correlated mothers body tissues (r=0.060). Embryonic levels also did not correlate with either embryonic fat content (r=0.018) or maternal fat content (r=0.300), suggesting that placental membranes offer only marginal protection for developing embryos against exposure to lipophilic organochlorine pesticides.

Organochlorine pesticide accumulation and genotoxicity in Mexican free-tailed bats from Oklahoma and New Mexico

The summer population of Mexican free-tailed bats (Tadarida brasiliensis) at Carlsbad Caverns, New Mexico, declined from an estimated 8.7 million in 1936 to 200,000 in 1974; thereafter, it increased to approximately 700,000 in 1991. This decline has been attributed primarily to organochlorine (OC) pesticide contamination and habitat disturbance. Similar declines have been observed in other populations of this species. This study examined the potential genotoxic effects of OC pesticide contamination on two populations of T. brasiliensis. Pesticide accumulation, frequencies of chromosomal aberrancy, and nuclear DNA content variation in spleen and testicular tissues were examined in specimens collected from Carlsbad Caverns and Vickery Cave, a maternity colony in northwestern Oklahoma, during the summers of 1990 and 1991. Pesticide residues in brain and carcass tissues were identified and quantified by electron capture gas chromatography. Genotoxicity was examined with the standard bone marrow chromosomal aberration assay and flow cytometry. Statistical relationships among pesticide content, observed chromosomal aberrancy, and nuclear DNA content variation were examined. Both populations demonstrated significant levels of DDE contamination; however, the Carlsbad Caverns population showed consistently higher pesticide loads. Males also demonstrated higher levels than females. No statistical differences in chromosomal aberrancy or nuclear DNA content variation were observed among sexes, sites, or collected periods. Positive correlations were detected between brain and carcass DDE concentrations for all bats examined. A significant negative relationship was found between brain DDE concentration and coefficients of variation in spleen DNA content only for males.

Mitochondrial DNA and karyotypic data confirm the presence of Mus indutus and Mus minutoides (Mammalia, Rodentia, Muridae, Nannomys) in Botswana

Abstract We use a combination of cytochrome b sequence data and karyological evidence to confirm the presence of Mus indutus and Mus minutoides in Botswana. Our data include sampling from five localities from across the country, including one site in northwestern Botswana where both species were captured in syntopy. Additionally, we find evidence for two mitochondrial lineages of M. minutoides in northwestern Botswana that differ by 5% in sequence variation. Also, we report that M. minutoides in Botswana have the 2n=34 karyotype with the presence of a (X.1) sex-autosome translocation.

Peramorphic Traits in the Tokay Gecko Skull

Traditionally, geckos have been conceived to exhibit paedomorphic features relative to other lizards (e.g., large eyes, less extensively ossified skulls, and amphicoelous and notochordal vertebrae). In contrast, peramorphosis has not been considered an important process in shaping their morphology. Here, we studied different sized specimens of Gekko gecko to document ontogenetic changes in cranial anatomy, especially near maturity. Comparison of this species with available descriptions of other geckos resulted in the identification of 14 cranial characteristics that are expressed more strongly with size increase. These characteristics become move evident in later stages of post‐hatching development, especially near maturation, and are, therefore, attributed to peramorphosis (hyperossification). ACCTRAN and DELTRAN character optimizations were applied to these characters using a tree of 11 genera derived from a gekkotan molecular phylogeny. This analysis revealed that G. gecko expresses the majority of these putative peramorphic features near maturity, and that some of these features are also expressed in species closely related to G. gecko. The characters studied have the potential to be applied in future phylogenetic and taxonomic studies of this group of lizards. J. Morphol. 276:915–928, 2015.

The Homology of the Pelvic Elements of Zygaspis quadrifrons (Squamata: Amphisbaenia)

Limb attenuation with element loss has occurred multiple times among the Squamata (lizards, snakes, and amphisbaenians). Although most of the attention has been focused on the appendicular bones, we found that the pelvic rudiments have been studied less thoroughly and recurring disagreement is common among different authors studying the same species. We studied the osteology of the pelvic region of female and male Zygaspis quadrifrons with high‐resolution X‐ray computed tomography data. We report an osteological landmark (acetabulum) not previously detected in this taxon, the presence of which has repercussions that call for a reconsideration of the primary homology hypothesis for the identity of these bones in amphisbaenians and other squamates. Finally, we observed that the acetabulum and limb rudiments in amphisbaenians (i.e., the stylopodium when present) are situated medial to the pelvic girdle, contrasting with the large majority of tetrapods where these structures are laterally oriented. Anat Rec, 297:1407–1413, 2014.

Effectiveness of chemical repellents in deterring red imported fire ants (Solenopsis invicta) from Sherman live traps.

Abstract Livetrapping small mammals is a common tool for surveying diversity and determining size of populations, but studies in the southern United States often are complicated by the red imported fire ant (Solenopsis invicta). We tested effectiveness of four chemical repellents applied around Sherman live traps to deter fire ants from removing bait and mutilating captured mammals (Borax, granules of pyrethrum, Raid Ant and Roach Spray, and carbaryl flea powder). A significant difference among repellents was detected, with carbaryl flea powder and Raid Ant and Roach Spray performing best. Carbaryl flea powder significantly reduced occurrence of fire ants in baited traps, while diversity and rates of capture for small mammals were unaffected.

A comparison of factors affecting the small-scale distribution of mercury from artisanal small-scale gold mining in a Zimbabwean stream system

Artisanal small-scale gold mining (ASGM) operations use mercury liberally in the gold extraction process and account for approximately one quarter of the anthropogenic mercury consumption worldwide. ASGM activities are concentrated in many impoverished and poorly regulated countries such as Zimbabwe, resulting in a number of negative impacts to health and the environment. To examine levels of mercury contamination in one such geographic locality, sediment and tailing samples were collected in a heavily mined watershed in southern Zimbabwe from May-June 2015. Samples were collected from multiple points within the stream system, as well as from around six stamp mills and a single industrial mine in the watershed. GPS point location data were taken for mining operations and sampling sites to examine the spatial patterns of mercury concentration. Data were first analyzed using linear regression and development of a MARS model, followed by application of an ANCOVA model to assess the relationship among mercury concentrations and percent organic material, distance downstream, and distance from potential contamination source. Mercury concentrations within the study area ranged from 6 to 1541 μg/kg dw (mean 142 μg/kg dw). Analyses of mercury concentrations indicated a positive relationship with percent organic material but a negative relationship with distance downstream and distance from potential contamination source. Results from this study help elucidate the relationship between gold production and the spatial scale of mercury contamination in aquatic ecosystems in Africa. These data may lead to a better understanding of the relationship between mercury use and community health, which may aid both the local and global communities in regulating mercury contamination of the environment.

Effect of fire on the herpetofauna of the Koanaka Hills, Ngamiland, Botswana

Ngamiland is one of the most remote regions in Botswana, and its herpetofauna is largely under-surveyed. This study documents the herpetofauna of the Koanaka Hills (KH) in Ngamiland in 2009 following extensive fire destruction and compares it to the pre-fire herpetofauna collected in 2008. We also provide new records for the region for three amphibian and six reptile species, and document vouchers for two taxa that were sighted but not collected in 2008. During 2009, 14 reptile and three amphibian species were collected, bringing the total number of confirmed herpetofaunal taxa near the KH to three amphibian and 19 reptile species. For seven species this is the first published occurrence in quarter degree square 2021 Aa. Analyses measuring changes in the KH herpetofauna following the fire are inconclusive due to differences in collection effort and weather conditions. However, these data suggest that fire impact was minimal.

Extreme Periodontal Disease in a Brazilian Free-Tailed Bat (Molossidae: Tadarida brasiliensis) from Eastern Texas

Abstract A male Brazilian free-tailed bat (Tadarida brasiliensis), collected from a colony in Huntsville, Walker County, Texas, had severe periodontal disease resulting in extensive loss of teeth. Although demonstrating normal activity and a healthy appearance, this individual had only eight teeth: normal complement is 30–32 teeth. The remaining teeth appeared to be sufficient for this individual to adequately process food and maintain an average body weight as reported for this species.