Masticophis bilineatus

Number of Pages: 4Integrative BiologyGeological Science

Masticophis taeniatus

Number of Pages: 6Integrative BiologyGeological Science

The Status of Three Uncommon Salamanders (Amphibia: Caudata) in Iowa

The smallmouth salamander [Ambystoma texanum (Matthes)], blue-spotted salamander (Ambystoma laterale Hallowell), and central newt [Notophthalmus viridescens louisianensis (Wolterstorff)] were studied in Iowa from fall 1982 through summer 1984. All three species have declined in abundance in Iowa. A. texanum is more abundant and widespread than was previously suspected, but is declining due to habitat destruction. Apparently, only two populations of A. laterale remain in Iowa. N. v. louisianensis has also declined due to habitat destruction, with only three populations known. All three species require ponds in or adjacent to forest. A. ta was found primarily in riparian forest. The other two species inhabited both riparian and upland forest. N. v. louisianensis was associated with permanent ponds containing aquatic vegetation

Comparative Ecology of Two Species of Semiaquatic Snakes in Southeastern North America

The banded water snake (Nerodia fasciata fasciata) and the Eastern cottonmouth (Agkistrodon piscivorus piscivorus) were the focal species in a long-term mark and recapture study in the upper coastal plain of South Carolina, USA. Recapture rates were low for both species. Female N. fasciata were significantly larger than males. Male A. piscivorus were larger than females but not significantly. Age structure and sex ratios were determined for these populations. Recapture latency was greater for A. piscivorus than for N. fasciata. There was little dietary niche overlap between these two species. Nerodia fasciata ingested significantly more fish headfirst and more amphibians tail first. Growth rates were also calculated for both species. Litter size, offspring size, relative clutch mass and parturition dates were determined for N. fasciata

Ecological Parameters of Coluber constrictor etheridgei, with Comparisons to Other Coluber constrictor Subspecies

In 1998, we conducted a radio-telemetry study of Coluber constrictor etheridgei (Tan Racer) in the Angelina National Forest in eastern Texas. Individuals were located once daily from 12 June to 14 August. We determined home-range size, movement distances, movement frequency, and habitat use for this short-term study. We also determined food habits of this population by examination of fecal samples. We compared these parameters to other Racer taxa in Utah (C. c. mormon [Western Yellow-bellied Racer]), Kansas (C. c. fl aviventris [Eastern Yellow-bellied Racer]), and South Carolina (C.c. priapus [Southern Black Racer]). Compared to these populations, Texas Racers exhibited larger home ranges and greater movement frequency and distances during the summer than Utah or Kansas populations, but approximately equal to those of the South Carolina population. Available data on food habits suggests that all populations are consumers of invertebrate and vertebrate prey. We hypothesize that the basic diet of C. constrictor is composed of invertebrates captured by active foraging in areas of abundant herbaceous vegetation, that differences in home-range size and movement distances result from variations in patchiness of suitable foraging habitat across populations, and that the proportion of vertebrate prey in the diet of Coluber populations increases as home-range size and movement distances increase due to increasing patchiness of foraging habitat, resulting in increasing encounters with vertebrate prey

Approaching Mechanization of Plant Micropropagation

Investigations of materials and methods for growing plant tissue in a continual-flow, liquid nutrient medium as an alternative to semisolid agar medium have been made. Enhanced growth of plant tissue on microporouspolypropylene membranes floating on a liquid nutrient has been demonstrated. Moreover, in vitro plantlets on the microporous membrane are free from entanglement with the support matrix and readily available to mechanizedhandling. Trained growth of plantlets through polypropylene netting shows potential for mechanization by mass handling (separation, singulation, and transfer) of plant tissue cultures

Mercury Accumulation in Tree Rings: Observed Trends in Quantity and Isotopic Composition in Shenandoah National Park, Virginia

Recent studies have shown that mercury (Hg) concentrations in tree rings have the potential to archive historical Hg exposure from local, regional, and global sources. The southeastern United States has received elevated Hg deposition, yet no studies have evaluated tree ring Hg in this region. Here, we quantify Hg accumulation and isotopic composition in tree rings collected in Shenandoah National Park, Virginia. Cores were collected from three individuals of three tree species—white oak (Quercus alba), northern red oak (Quercus rubra), and pitch pine (Pinus rigida)—within the northern, central, and southern areas of the Park (n = 27 cores). The cores were analyzed for Hg content in 10‐year increments, with some cores dating back to the early 1800s. Overall, tree ring Hg concentrations (ranging from below detection to 4.4 ng/g) were similar to other studies and varied between species, with pitch pine having higher concentrations than the deciduous species. The most notable feature of the tree ring Hg time series was a peak that occurred during the 1930s through 1950s, coinciding with the use of Hg at a local industrial facility. Atmospheric modeling indicates that potential emissions from the plant likely had a stronger impact on the southern region of the Park, consistent with the latitudinal gradient in tree ring Hg concentrations. Mass‐dependent and mass‐independent fractionation of Hg isotopes suggests contributions from both regional anthropogenic and local industrial sources during this period. This study demonstrates the potential usefulness of tree ring dendrochemistry for identifying historical sources of atmospheric Hg exposure.Key PointsTree ring mercury levels in Shenandoah National Park, Virginia, were similar to those measured in other North American forestsTree ring mercury peaked during the 1930s to 1950s, coinciding with mercury use at an industrial facility near the southern end of the ParkMercury isotopes suggest a local source at this time, demonstrating the potential of dendrochemistry to identify historical sourcesPlain Language SummaryFor many years scientists have used tree rings to reconstruct past climate. Increasingly, tree rings are being used to document the historical exposure of trees to pollutants. In this study, we cored trees in Shenandoah National Park, Virginia, dated the tree rings, and then measured the amount of mercury stored within decadal core increments. We were surprised to find that mercury levels peaked in the 1930s to 1950s, even though global mercury emissions continued to rise throughout the past century, mostly as a by‐product of energy production. Our findings suggest that the trees were exposed to a local pollutant source during this earlier time period, perhaps from a nearby industrial plant that used mercury in the production of rayon. By examining the chemistry of wood within tree rings, we can get a clearer picture of when and where human activities have affected air pollution over recent centuries.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153685/1/jgrg21576_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153685/2/jgrg21576.pd

Transgenic mice expressing LHX3 transcription factor isoforms in the pituitary: Effects on the gonadotrope axis and sex-specific reproductive disease

The LHX3 transcription factor plays critical roles in pituitary and nervous system development. Mutations in the human LHX3 gene cause severe hormone deficiency diseases. The gene produces two mRNAs which can be translated to three protein isoforms. The LHX3a protein contains a central region with LIM domains and a homeodomain, and a carboxyl terminus with the major transactivation domain. LHX3b is identical to LHX3a except that it has a different amino terminus. M2-LHX3 lacks the amino terminus and LIM domains of LHX3a/b. In vitro experiments have demonstrated these three proteins have different biochemical and gene regulatory properties. Here, to investigate the effects of overexpression of LHX3 in vivo, the alpha glycoprotein subunit ( ΑGSU ) promoter was used to produce LHX3a, LHX3b, and M2-LHX3 in the pituitary glands of transgenic mice. Alpha GSU-beta galactosidase animals were generated as controls. Male ΑGSU-LHX3a and ΑGSU-LHX3b mice are infertile and die at a young age as a result of complications associated with obstructive uropathy including uremia. These animals have a reduced number of pituitary gonadotrope cells, low circulating gonadotropins, and possible sex hormone imbalance. Female ΑGSU-LHX3a and ΑGSU-LHX3b transgenic mice are viable but have reduced fertility. By contrast, ΑGSU-M2-LHX3 mice and control mice expressing beta galactosidase are reproductively unaffected. These overexpression studies provide insights into the properties of LHX3 during pituitary development and highlight the importance of this factor in reproductive physiology. J. Cell. Physiol. 212: 105–117, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56051/1/21010_ftp.pd

Status of the NRC Decommissioning Program

On July 21, 1997, the U.S. Nuclear Regulatory Commission (NRC) published the final rule on Radiological Criteria for License Termination (the License Termination Rule or LTR) as Subpart E to 10 CFR Part 20. NRC regulations require that materials licensees submit Decommissioning Plans to support the decommissioning of its facility if it is required by license condition, or if the procedures and activities necessary to carry out the decommissioning have not been approved by NRC and these procedures could increase the potential health and safety impacts to the workers or the public. NRC regulations also require that reactor licensees submit Post-shutdown Decommissioning Activities Reports and License Termination Plans to support the decommissioning of nuclear power facilities. This paper provides an update on the status of the NRC's decommissioning program that was presented during WM'02. It discusses the staff's current efforts to streamline the decommissioning process, current issues being faced in the decommissioning program, such as partial site release and restricted release of sites, as well as the status of the decommissioning of complex sites and those listed in the Site Decommissioning Management Plan. The paper discusses the status of permanently shut-down commercial power reactors and the transfer of complex decommissioning sites and sites listed on the SDMP to Agreement States. Finally the paper provides an update of the status of various tools and guidance the NRC is developing to assist licensees during decommissioning, including an effort to consolidate and risk-inform decommissioning guidance