Environmental investigations have been conducted at 23 military firing ranges in the United States and Canada. The specific training facilities most frequently evaluated were hand grenade, antitank rocket, and artillery ranges. Energetic compounds (explosives and propellants) were determined and linked to the type of munition used and the major mechanisms of deposition.

Little is known about the response of terrestrial plants to 2,4,6‐trinitrotoluene (TNT). To assess its effects, yellow nutsedge (Cyperus esculentus L.) was grown in hydroponic cultures containing TNT concentrations of 0, 5, 10, and 20 mg/L. The deleterious effects of TNT were rapid and occurred at solution concentrations of 5 mg/L and higher. Root growth was most affected, followed by leaves and rhizomes. Root weights were reduced about 95% when grown in the presence of TNT. Plant yields were 54 to 74% lower than the control. The TNT and its metabolites, 4‐amino‐2,6‐dinitrotoluene (4‐ADNT), and 2‐amino‐4,6‐dinitrotoluene (2‐ADNT) were found throughout the plants. Solutions were continually monitored to ensure that no metabolites were present in solution. Since TNT was the only compound taken up, the metabolites must have formed within the plant. Levels of 4‐ADNT exceeded those of 2‐ADNT and TNT itself ranging up to 2200 mg/kg in roots of plants grown in 20 mg/L of TNT. The greatest quantities of all three compounds were found in the rhizomes. Increasing solution TNT levels increased the concentrations and quantities of all three compounds in the plants.

Molecular genetic maps were constructed for two full-sib populations, TTC1 and TTC2, derived from two Leymus triticoides x Leymus cinereus hybrids and one common Leymus triticoides tester. Informative DNA markers were detected using 21 EcoRI-MseI and 17 PstI-MseI AFLP primer combinations, 36 anchored SSR or STS primer pairs, and 9 anchored RFLP probes. The 164-sib TTC1 map includes 1069 AFLP markers and 38 anchor loci in 14 linkage groups spanning 2001 cM. The 170-sib TTC2 map contains 1002 AFLP markers and 36 anchor loci in 14 linkage groups spanning 2066 cM. Some 488 homologous AFLP loci and 24 anchor markers detected in both populations showed similar map order. Thus, 1583 AFLP markers and 50 anchor loci were mapped into 14 linkage groups, which evidently correspond to the 14 chromosomes of allotetraploid Leymus (2n = 4x = 28). Synteny of two or more anchor markers from each of the seven homoeologous wheat and barley chromosomes was detected for 12 of the 14 Leymus linkage groups. Moreover, two distinct sets of genome-specific STS markers were identified in these allotetraploid Leymus species. These Leymus genetic maps and populations will provide a useful system to evaluate the inheritance of functionally important traits of two divergent perennial grass species.

2001. Merits of native and introduced Triticeae grasses on semi-arid rangelands. Can. J. Plant Sci. 81: 45-52. Experiments were conducted on four semiarid range sites to compare stand establishment , productivity, and persistence of several introduced perennial Triticeae grasses with that of their native counterparts. On Intermountain sites with severe water limitations (< 300 mm), native grasses were more difficult to establish, less productive, and less persistent than the introduced grasses. Stands of native grasses declined most rapidly under defoliation. At locations where moisture conditions were more favorable, particularly where more summer precipitation occurred, native Triticeae grasses established and persisted relatively well compared with the introduced entries. Although difficult to establish, stands of the rhizoma-tous native, western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve] increased during the seasons after establishment. Choice of plant materials to be used in range seeding programs should be based on objective criteria. To do otherwise will perpetuate degradation of soil resources, especially on sites that are dominated by weedy annual species such as cheatgrass (Bromus tecto-rum) and medusahead rye (Taeniatherum asperum). It is proposed that adapted introduced grasses be equally considered along with native grasses as a component of seed mixtures on environmentally harsh sites that have been burned, infested with competitive weedy species, or otherwise degraded.. 2001. Attributs des Triticées indigènes et introduites dans les par-cours de pâturage semi-arides. Can. J. Plant Sci. 81: 45-52. Nous avons réalisé à quatre emplacements de parcours semi-arides des expériences visant à comparer l'installation, la productivité et la longévité de plusieurs Triticées vivaces d'introduction avec les propriétés d'espèces indigènes apparentées. Dans les vallée des montagne, exposées à de graves carences en précipitations (moins de 300 mm), les espèces indigènes étaient plus difficiles à installer et aussi moins productives et moins persistantes. En outre, leurs peuplements se dégarnissaient particulièrement vite sous l'effet du broutage. En revanche, dans les situations mieux arrosées, en particulier durant les mois d'été, leur installation et leur longévité se comparaient assez favorablement à celles des espèces d'introduction. Malgré des difficultés d'installation, les peuplements d'agropyre de l'Ouest [Pascopyrum metis (Rydb.) A. Löve], espèce indigène rhizomateuse gagnaient en densité dans les années suivantes. Le choix du matériel végétal à utiliser dans les programmes de ressemis en parcours devrait donc être fondé sur des critères objectifs, faute de quoi la dégradation du sol risque de se perpétuer, surtout aux emplacements dominés par des espèces annuelles envahissantes comme le brome des toits (Bromus tectorum et Taeniatherum asperum) (élyme tête-de-méduse). Les Triticées d'introduction adaptées aux conditions de parcours devraient donc être considérées tout autant que les espèces indigène...

Bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve = Agropyron spicatum Pursh: Poaceae) is a cross‐pollinating perennial grass native to western North America. Two bluebunch wheatgrass cultivars, Goldar and Whitmar, are currently available for large‐scale rangeland seeding. However, cultivars may lack the genetic diversity and adaptation necessary for dynamic non‐local environments. The objective of this study was to quantify and compare genomic DNA variation within and between Goldar, Whitmar, and Generation 2 of P‐7, a multiple‐origin polycross (MOPX2) of 25 naturally diverse bluebunch wheatgrass collections. We assayed 1043 polymorphic amplified fragment length polymorphism (AFLP) products and 88 monomorphic AFLP products from three sample populations of 22 plants. The number of polymorphic loci (and unique alleles) within sample populations of P‐7, Goldar, and Whitmar was 898 (99), 813 (49), and 746 (59), respectively. Conversely, the number of fixed AFLP loci within sample populations of P‐7, Goldar, and Whitmar was 233, 318, and 385, respectively. The overall nucleotide‐sequence diversity [π ± SE (×1000)] estimated for P‐7, Goldar, and Whitmar was 100.2 ± 7.1, 80.1 ± 6.6, and 79.4 ± 6.7, respectively. By all measures, genetic variation within P‐7 is significantly higher than genetic variation within cultivars. However, the estimated number of inter‐population nucleotide differences per site [dX ± SE (×1000)] between Goldar and Whitmar, e.g., 36.6 ± 1.6, is only slightly higher than π within these cultivars, therefore the net nucleotide‐sequence divergence [dA ± SE (× 1000)] between these cultivars is relatively small, e.g. 2.5 ± 0.3. These results indicate that selectively neutral genetic diversity has not been dramatically reduced or inadvertently lost via genetic drift that may have occurred since the divergence of Goldar and Whitmar. No AFLP markers completely distinguish Goldar and Whitmar, therefore discrete morphological differences between these cultivars (e.g., the presence and absence of awns) most likely result from natural or artificial selection.

Random amplified polymorphic DNA (RAPD) markers were used to provide estimates of the comparative genetic variation within and among four native populations of Schizachyrium scoparium. Genotypes were collected from high‐ and low‐fertility sites in both New Jersey (forest biome) and in Oklahoma (grassland biome), USA, and propagated in the greenhouse. Four oligonucleotide primers, 10 bp in length, produced a total of 60 RAPD markers, with the minimum marker difference between any two individuals being 14 markers. Euclidean metric distances were calculated among all individuals, and the analysis of molecular variance (AMOVA) technique was used to apportion the total genetic variation among individuals within populations, populations within fertility levels, populations within biomes, fertility levels, and biomes. Even though most genetic variation resided within populations, statistically significant differences were detected between populations within each biome. Furthermore, genetic distances between high and low fertility levels within biomes were equal to or greater than biome distances. Therefore, in this wide‐ranging and highly variable species, RAPD analysis suggests that local site differences in fertility and ecological history can promote genetic differentiation equal to or greater than geographical differentiation.

No abstract

Transposable elements (TEs) are constitutive components of both eukaryotic and prokaryotic genomes. The role of TEs in the evolution of genes and genomes has been widely assessed over the past years in a variety of model and non-model organisms. Drosophila is undoubtedly among the most powerful model organisms used for the purpose of studying the role of transposons and their effects on the stability and evolution of genes and genomes. Besides their most intuitive role as insertional mutagens, TEs can modify the transcriptional pattern of host genes by juxtaposing new cis-regulatory sequences. A key element of TE biology is that they carry transcriptional control elements that fine-tune the transcription of their own genes, but that can also perturb the transcriptional activity of neighboring host genes. From this perspective, the transposition-mediated modulation of gene expression is an important issue for the short-term adaptation of physiological functions to the environmental changes, and for long-term evolutionary changes. Here, we review the current literature concerning the regulatory and structural elements operating in cis provided by TEs in Drosophila. Furthermore, we highlight that, besides their influence on both TEs and host genes expression, they can affect the chromatin structure and epigenetic status as well as both the chromosome's structure and stability. It emerges that Drosophila is a good model organism to study the effect of TE-linked regulatory sequences, and it could help future studies on TE-host interactions in any complex eukaryotic genome.