Restoration and Monitoring of the River Otter Population in Iowa

Northern river otters (Lontra canadensis) were widespread in North America at the time of European settlement. However, river otters were extirpated from most of Iowa in the early 1900s due to habitat degradation and unregulated harvest. In 1985, the Iowa Department of Natural Resources began an effort to restore the river otter population throughout the state, including a pilot study of survival to determine if establishment was feasible. Annual survival was estimated to be 86% during the pilot study. River otters dispersed an average of about 11 km from the point of release and exhibited habitat use typical for the species. Based on the successful pilot study, 261 river otters were released in the state of Iowa from 1986-2001. More recently we examined the age structure and reproductive effort of 81 river otters (43 females and 38 males) collected in Iowa from 1999-2001 to document the characteristics of the reestablished population. We found that 41% of the otters sampled were juveniles, 38% were yearlings and 21% were adults. Fifty-five percent of all female otters were pregnant, and 80% of adult females were pregnant. We observed a mean of 2.9 corpora lutea/female and calculated that female’s ≥ 1 year old could potentially produce an average 5.7 female offspring during an average life span. Based on the widespread distribution, healthy reproductive characteristics, and high survival rates it is feasible that a limited harvest of river otter could be implemented in Iowa

External N inputs and internal N cycling traced by isotope ratios of nitrate, dissolved reduced nitrogen, and particulate nitrogen in the eastern Mediterranean Sea

The eastern Mediterranean Sea is an unusually nutrient-poor oceanbasin where the 15N/14N isotope ratios in many compartments of reactivenitrogen are lower than in comparable oceanic settings. To elucidatepossible reasons, we determined stable isotope ratios in nitrate,suspended particulate nitrogen (PN), and total dissolved reducednitrogen for stations across the eastern Mediterranean Sea occupiedin January and February 2007; sinking PN was collected at one ofthe stations in the period from February to September 2007. The δ15Nlevels of all reactive N compartments in waters of the basin arevery low (grand average 2.6‰) compared to other oceanic environments.Deep water nitrate below 500 m water depth (δ15N = 2.2 \pm 0.3‰)was more depleted in 15N than nitrate generally found in deep waternitrate pools of other oceans (δ15N ranges from 4.7 to 5.4‰), whereas15N was enriched in suspended particulate N (δ15N = 7.3 \pm 0.8‰)and reduced dissolved N (δ15N = 5.7 \pm 3.8‰) compared to nitrateand sinking particulate N intercepted in sediment traps (δ15N = 0.9\pm 0.8‰). We infer that extensive mineralization is the causeof the isotopic makeup of reactive N in deep water, in concert withthe lack of water column denitrification. Nitrogen and oxygen isotoperatios in nitrate of the mixed layer suggest an external source ofnitrate depleted in 15N, probably anthropogenic NOx rather than fixednitrogen. To explain the observed isotope anomaly in the mixed layer,either the ammonium formed by the breakdown of organic matter mustbe predominantly nitrified, or atmospheric NOx characteristicallyenriched in 18O was present

Development of a BAC library for yellow-poplar (Liriodendron tulipifera) and the identification of genes associated with flower development and lignin biosynthesis

Liriodendron tulipifera L., a member of the Magnoliaceae, occupies an important phylogenetic position as a basal angiosperm that has retained numerous putatively ancestral morphological characters, and thus has often been used in studies of the evolution of flowering plants and of specific gene families. However, genomic resources for these early branching angiosperm lineages are very limited. In this study, we describe the construction of a large-insert bacterial artificial chromosome (BAC) library from L. tulipifera. Flow cytometry estimates that this nuclear genome is approximately 1,802 Mbp per haploid genome (±16 SD). The BAC library contains 73,728 clones, a 4.8-fold genome coverage, with an average insert size of 117 kb, a chloroplast DNA content of 0.2%, and little to no bacterial sequences nor empty vector content clones. As a test of the utility of this BAC library, we screened the library with six single/low-copy genic probes. We obtained at least two positive clones for each gene and confirmed the clones by DNA sequencing. A total of 182 paired end sequences were obtained from 96 of the BAC clones. Using BLAST searches, we found that 25% of the BAC end sequences were similar to DNA sequences in GenBank. Of these, 68% shared sequence with transposable elements and 25% with genes from other taxa. This result closely reflected the content of random sequences obtained from a small insert genomic library for L. tulipifera, indicating that the BAC library construction process was not biased. The first genomic DNA sequences for Liriodendron genes are also reported. All the Liriodendron genomic sequences described in this paper have been deposited in the GenBank data library. The end sequences from shotgun genomic clones and BAC clones are under accession DU169330-DU169684. Partial sequences of Gigantea, Frigida, LEAFY, cinnamyl alcohol dehydrogenase, 4-coumarate:CoA ligase, and phenylalanine ammonia-lyase genes are under accession DQ223429-DQ223434

Development of a BAC library for yellow-poplar (Liriodendron tulipifera) and the identification of genes associated with flower development and lignin biosynthesis

Liriodendron tulipifera L., a member of the Magnoliaceae, occupies an important phylogenetic position as a basal angiosperm that has retained numerous putatively ancestral morphological characters, and thus has often been used in studies of the evolution of flowering plants and of specific gene families. However, genomic resources for these early branching angiosperm lineages are very limited. In this study, we describe the construction of a large-insert bacterial artificial chromosome (BAC) library from L. tulipifera. Flow cytometry estimates that this nuclear genome is approximately 1,802 Mbp per haploid genome (±16 SD). The BAC library contains 73,728 clones, a 4.8-fold genome coverage, with an average insert size of 117 kb, a chloroplast DNA content of 0.2%, and little to no bacterial sequences nor empty vector content clones. As a test of the utility of this BAC library, we screened the library with six single/low-copy genic probes. We obtained at least two positive clones for each gene and confirmed the clones by DNA sequencing. A total of 182 paired end sequences were obtained from 96 of the BAC clones. Using BLAST searches, we found that 25% of the BAC end sequences were similar to DNA sequences in GenBank. Of these, 68% shared sequence with transposable elements and 25% with genes from other taxa. This result closely reflected the content of random sequences obtained from a small insert genomic library for L. tulipifera, indicating that the BAC library construction process was not biased. The first genomic DNA sequences for Liriodendron genes are also reported. All the Liriodendron genomic sequences described in this paper have been deposited in the GenBank data library. The end sequences from shotgun genomic clones and BAC clones are under accession DU169330-DU169684. Partial sequences of Gigantea, Frigida, LEAFY, cinnamyl alcohol dehydrogenase, 4-coumarate:CoA ligase, and phenylalanine ammonia-lyase genes are under accession DQ223429-DQ223434