A study of the mechanism of chemical reactivity of nitrogen tetroxide with titanium alloys Quarterly report, 1 Oct. - 31 Dec. 1967

Corrosion test of titanium alloys with nitrogen tetroxid

Regulator of Gene Silencing Calmodulins: Components of RNA granules and autophagy during plant stress

The central focus of this work is to understand how rgsCaM homologs regulate mRNP bodies under cellular stress. While rgsCaM is best known as an endogenous suppressor of gene silencing in tobacco, our findings for a homologous protein in Arabidopsis, CML38, suggest that a broader function in the regulation of mRNP bodies may be common to this family of calmodulin-like proteins. CML38 is induced by hypoxia stress, contributes to plant survival under hypoxia, and localizes to stress-induced mRNP bodies called stress granules (SGs), as well as to processing bodies (PBs). Members of this protein family target viral and endogenous proteins for degradation through the autophagy pathway. We propose that rgsCaM and its relatives may localize to stress-induced mRNP bodies and target them for autophagic degradation (granulophagy). In our investigations for rgsCaM, we used hypoxia stress as a means to induce stress granule formation and found that rgsCaM localizes to hypoxia-induced cytosolic granules which are both independent of and bound to SGs and PBs. We further show that rgsCaM colocalizes with the autophagosome cargo-binding protein ATG8e, and interacts with ATG8e in planta by BiFC assay. Mutations disrupting the N-terminus of rgsCaM, or ones affecting the ability of ATG8 to bind cargo adaptors caused a loss in BiFC interaction. This suggests that the N-terminus contains a site for binding to the cargo binding protein ATG8e, and which might mediate the targeting of rgsCaM and bound cargo to autophagosomes as part of the granulophagy process. For future studies, a FRET-based approach for probing rgsCaM interactions in vivo is demonstrated.In a second trust, we report the development of a novel, fluorescence-based, quantitative oxygen biosensor to facilitate the non-invasive assessment of the oxygen status of cells of living cells by fluorescent imaging

Red-cockaded Woodpecker Colony Status and Trends On the Angelina, Davy Crockett and Sabine National Forests

Abundant hardwood midstory, colony isolation, and habitat fragmentation are believed to be the causes for severe population declines of red-cockaded woodpeckers on three national forests in eastern Texas

Red-Cockaded Woodpeckers and Silvicultural Practice: is Uneven-Aged? Silviculture Preferable to Even-Aged

The endangered red-cockaded woodpecker (Picoides borealis) has become a high-profile management issue in the southeastern United States. Suitable habitat consists of mature to old pine, or mixed pine-hardwood forest, with minimal hardwood midstory vegetation. Loss of habitat, detrimental silvicultural practices, and changes in the fire regime have resulted in small fragmented populations, most of which have been declining precipitously in recent decades (Costa and Escano 1989, Conner and Rudolph 1989). The current population of l0-12 thousand birds occurs across much of the original range from Virginia and Florida west to Oklahoma and Texas (James 1995). However, populations are restricted to isolated tracts of suitable habitat, primarily on public lands. Consequently, the debate over the future of this once abundant species, characteristic of fire climax pine forests, has focused primarily on management strategies for the species by the U.S. Forest Service (USFS), the agency responsible for the majority of the public forest lands in the region

The Red-cockaded Woodpecker: Interactions With Fire, Snags, Fungi, Rat Snakes, and Pileated Woodpeckers

Red-cockaded woodpecker (Picoides borealis) adaptation to fire-maintained southern pine ecosystems has involved several important interactions: (I) the reduction of hardwood frequency in the pine ecosystem because of frequent tires, (2) the softening of pine heartwood by red heart fungus (Phellinus pini) that hastens cavity excavation by the species, (3) the woodpecker\u27s use of the pine\u27s resin system to create abarrier against rat snakes (Elaphe sp.), and (4) the woodpecker as a keystone cavity excavator for secondary-cavity users. Historically, frequent, low-intensity ground tires in southern pine uplands reduced the availability of dead trees (snags) that are typically used by other woodpecker species for cavity excavation. Behavioral adaptation has permitted red-cockaded woodpeckers to use living pines for their cavity trees and thus exploit the frequently burned pine uplands. Further, it is proposed that recent observations of pileated woodpecker (Dryocopus pileatus) destruction of red-cockaded woodpecker cavities may be related to the exclusion of fire, which has increased the number of snags and pileated woodpeckers. Red-cockaded woodpeckers mostly depend on recl heart fungus to soften the heartwood of their cavity trees, allowing cavity excavation to proceed more quickly. Red-cockaded woodpeckers use the cavity tree\u27s resin system to create a barrier that serves as a deterrent against rat snake predation by excavating small wounds, termed resin wells, above and below cavity entrances. It is suggested that red-cockaded woodpeckers are a keystone species in fire-maintained southern pine ecosystems because, historically, they were the only species that regularly could excavate cavities in living pines within these ecosystems. Many of the more than 30 vertebrate and invertebrate species known to use red-cockaded woodpecker cavities are highly dependent on this woodpecker in fire-maintained upland pine forests

Population Trends of Red-Cockaded Woodpeckers in Texas

We tracked population trends of Red-cockaded Woodpeckers (Picoides borealis) in eastern Texas from 1983 through 2004. After declining precipitously during the 1980s, woodpecker population trends on federal lands (National Forests and Grasslands in Texas, but excluding the Big Thicket National Preserve) increased between 1990 and 2000, and have been stable to slightly decreasing over the past four years. Litigation against the U.S. Forest Service in the mid 1980s reversed a severe population decline, whereas litigation during the past 8 years hampered recovery efforts for the Red-cockaded Woodpecker. Red-cockaded Woodpecker populations on private and State of Texas lands have steadily declined over he past 15 years, most likely the result of demographic isolation. Limited availability of old pines suitable for cavity excavation, inadequate fire regimes to control hardwood midstory, and demographic dysfunction resulting from woodpecker group isolation remain as significant obstacles to recovery in most populations

Red-Cockaded Woodpeckers vs Rat Snakes: The Effectiveness of the Resin Barrier

Red-cockaded Woodpeckers (Picoides borealis) excavate resin wells in the immediate vicinity of roost and nest cavity entrances. Resin wells are worked regularly, resulting in a copious and persistent resin flow that coats the tree trunk, especially below cavity entrances. Red-cockaded Woodpeckers also scale loose bark from cavity trees and closely adjacent trees. These two behaviors result in smooth, sticky surfaces surrounding cavity entrances. Climbing experiments on cavity, scaled, and control trees using rat snakes (Elaphe obsoleta) demonstrate that these behaviors produce a resinous barrier that is highly effective in preventing predatory snakes from gaining access to active Red-cockaded Woodpecker cavities

Experimental Reintroduction of Red-Cockaded Woodpeckers

The Red-cockaded Woodpecker (Picoides borealis) is an endangered species endemic to the pine forests of the southeastern United States (Jackson 1971). Deforestation and habitat alteration have severely affected Red-cockaded Woodpecker populations; current populations are isolated and most are declining (Jackson 1971, Lennartz et al. 1983, Conner and Rudolph 1989, Costa and Escano 1989). The species has been extirpated from significant areas of suitable or potentially suitable habitat

Red-Cockaded Woodpecker Recovery: An Integrated Strategy

Populations of the red-cockaded woodpecker (Picoides borealis) have experienced massive declines since European colonization of North America. This is due to extensive habitat loss and alteration. Logging of old-growth pine forests and alteration of the fire regime throughout the historic range of the species were the primary causes of population decline. Listing of the red-cockaded woodpecker under the Endangered Species Act of 1973, as amended, and increased emphasis on management of non-game species have resulted in efforts to recover remnant populations of the red-cockaded woodpecker in many parts of its historic range. Due to extensive research and adaptive management initiatives much is now known about the elements required for both short- and long-term management of viable populations of red-cockaded woodpeckers. A short-term strategy is crucial because currently available habitat, in nearly all populations, is poor in 1 or more critical respects. Consequently, almost all populations require immediate attention in the short term, to insure suitable midstory and understory conditions, adequate availability of suitable cavities, and restoration of demographic viability through improvements in number and distribution of breeding groups. Management techniques including artificial cavities, cavity entrance restrictors, translocation of birds, prescribed fire, and mechanical and chemical control of woody vegetation are available to achieve these needs. In the long term, cost-effective management of red-cockaded woodpecker populations requires a timber management program and prescribed fire regime that will produce and maintain the stand structure characteristic of high quality nesting and foraging habitat, so that additional intensive management specific to the woodpeckers is no longer necessary. Timber management that achieves this goal and still allows substantial timber harvest is feasible. The implementation of a red-cockaded woodpecker management strategy, as outlined above, represents appropriate ecosystem management in the fire-maintained pine ecosystems of the southeastern United States and will ultimately benefit a great number of additional species of plants and animals adapted to this ecosystem

Red-Cockaded Woodpecker Nesting Success, Forest Structure, and Southern Flying Squirrels in Texas

For several decades general opinion has suggested that southern flying squirrels (Gluucomys volans) have a negative effect on Red-cockaded Woodpeckers (Picoides borealis) through competition for cavities and egg/nestling predation. Complete removal of hardwood trees from Red-cockaded Woodpecker cavity tree clusters has occurred on some forests because southern flying squirrel abundance was presumed to be associated with the presence and abundance of hardwood vegetation. In some locations, southern flying squirrels have been captured and either moved or killed in the name of Red-cockaded Woodpecker management. We determined southern flying squirrel occupancy of Red-cockaded Woodpecker cavities in loblolly (Pinus taeda)-shortleaf (P. echinata) pine habitat (with and without hardwood midstory vegetation) and longleaf pine (P. pulustris) habitat (nearly devoid of hardwood vegetation) during spring, late summer, and winter during 1990 and 1991. Flying squirrel use of Red-cockaded Woodpecker cavities was variable and was not related to presence or abundance of hardwood vegetation. Woodpecker nest productivity was not correlated with flying squirrel use of woodpecker cavities within clusters. In addition, we observed six instances where Red-cockaded Woodpeckers successfully nested while flying squirrels occupied other cavities in the same tree. Our results suggest that complete removal of hardwoods from woodpecker cluster areas in loblolly and shortleaf pine habitat may not provide benefits to the woodpeckers through reduction of flying squirrel numbers. Reduction of hardwood midstory around cavity trees, however, is still essential because of the woodpecker\u27s apparent innate intolerance of hardwood midstory foliage