No description available.

Zea mays plants kept at ambient (ca 375ppm) and elevated CO₂ (ca 650 to 700ppm) were used to examine the possibility of a symplasmic loading, unloading and transport pathway in dark-adapted and illuminated (200μmolm⁻²sec⁻¹ ) sink and source leaves. 5,6-carboxyfluorescein diacetate was introduced into the mesophyll cells and symplasmic transfer observed 3h after application. In sink and source leaves exposed to ambient CO₂ and illuminated at 200 molm-2sec-1, the fluorescence front was observed approximately 3cm from the point of application, while in dark-adapted plants, the fluorescence front was observed approximately 1cm from the point of application. Under elevated CO₂ conditions the fluorescence front in illuminated plants appeared to transport faster moving approximately 5cm from the point of application, and in dark-adapted plants, only 3cm from the point of application. Based on the increase in 5,6-CF accumulation under elevated CO₂ conditions, the present study suggests that there was an increase in capacity for assimilate loading and transport under elevated CO₂ conditions. In source leaves, 5,6-CFDA was taken up into the mesophyll cells, loaded symplasmically and transported basipetally. In sink leaves 5,6- CFDA was taken up from basal mesophyll and after symplasmic loading, was transported acropetally where it was offloaded into the younger immature sink region. Transport in the sieve tubes was confirmed by using aniline blue, which was applied 3h after 5,6-CF transport. Aniline blue coupled with 5,6-CF transport studies showed that the sieve tubes of both cross and longitudinal veins are involved in symplasmic unloading, loading and transport processes in sink and source leaves. Apoplasmic uptake of 5,6-CFDA by cut leaves showed that after apoplasmic transport via the transpiration stream, 5,6-CFDA was offioaded to the xylem parenchyma where it was metabolically cleaved , releasing fluorescent 5,6-CF into the xylem parenchyma. Transverse sections cut after 3h of uptake were observed after 120 and 180 min suggesting that a retrieval of solutes occurs from the xylem to the xylem parenchyma, bundle sheath, phloem parenchyma and to the th in-walled sieve tubes. It was not possible to determine if the thick-walled sieve tubes were involved or if they took up 5,6-CF. Given the available data on loading and offioading of assimilates in sink and source leaves respectively, this study demonstrated that a slow symplasmic pathway exists from the mesophyll to the phloem, and that offloading from the phloem in sink leaves can occur via a symplasmic route.

Master of Science / Department of Biology / Brett K. Sandercock / Translocations are a useful management tool for restoring wildlife species to their native ranges, but require post-release monitoring to determine project success. We report results of a 4-year effort to reestablish a breeding population of Evermann's Rock Ptarmigan (Lagopus mutus evermanni) on Agattu Island in the Aleutian Archipelago, Alaska. This endemic subspecies of ptarmigan was extirpated from most of the Near Islands by introductions of arctic fox by fur traders, and natural recolonizations did not occur after fox eradication. All females surviving the 2-week post-release period attempted to nest but initiated clutches later in the season and laid fewer eggs than resident females. Nest success was similar for resident and translocated females. Brood survival was greater for translocated than resident females and differed significantly; however, brood survival varied among years and was reduced by adverse weather conditions in 2006. Seasonal survival of radio-marked birds during the breeding season was 100% for translocated and resident ptarmigan. Over-winter mortality resulted in a low return rate in 2006. Returning birds in 2006 showed strong site fidelity and nest locations in two consecutive years were closely spaced. We examined nest site selection and determined brood movements and home range size of recently translocated and resident females. Nest sites of translocated females averaged 4.2 km from their respective release location and were not different from nest locations of resident females with regard to topographical features. Female nest site selection was influenced by percent composition of rock and forb coverage but was unaffected by slope, aspect, or general habitat. Broods of both resident and translocated females made movements to higher elevations after hatching. While size of brood home range was similar for resident and translocated females, distances traveled between the nest site and the arithmetic center of the brood home range were greater for translocated females. Overall, we conclude that translocations are an effective technique for reestablishing island populations of Rock Ptarmigan. Our study provides successful methods which may benefit future projects to reestablish endemic populations of ptarmigan and landbirds elsewhere in the Aleutian Islands.

Im Rahmen dieser Arbeit wurde die Konservierung elektrophysiologischer Charakteristika von Proteintranslokasen aus verschiedenen Organismen untersucht. Die Sec61/Sec61p Komplexe aus rauen Mikrosomen von Canis familiaris und Saccharomyces cerevisiae bilden ionenpermeable Poren mit einer hohen Leitfähigkeit in planaren Lipidmembranen. In Säugerzellen werden diese durch einen Calcium-Calmodulin (Ca2+-CaM)-vermittelten negativen Feedback-Mechanismus reguliert. Im Rahmen dieser Arbeit konnte die Spezifität der zugrundeliegenden Interaktion von Ca2+-CaM mit der α-Untereinheit des Sec61 Komplexes belegt werden. Es wurde gezeigt, dass der Calmodulin Antagonist Ophiobolin A in der Lage ist, die Inhibition der Ionenpermeation durch Sec61 aufzuheben. Des Weiteren wurde anhand elektrophysiologischer Messungen nachgewiesen, dass dieser Ca2+-CaM-vermittelte Regulationsmechanismus in der Hefe S. cerevisiae nicht vorhanden ist. Dies wird auf eine kritische Variation in der Primärstruktur des Hefe-Proteins zurückgeführt, welche die Bindung von Calmodulin an den N-Terminus von Sec61p verhindert. Der bakterielle SecYEG Komplex aus E. coli konnte erfolgreich in Proteoliposomen rekonstituiert werden. Die Funktionalität des Translokons wurde in in vitro proOmpA Importexperimenten nachgewiesen. Mittels dieser Proteoliposomen sollten SecYEG Poren in den planaren Bilayer integriert werden. Sowohl für den inaktiven als auch für den durch die Anwesenheit von Substraten oder Bindepartnern aktivierten Komplex konnten keine ionenpermeablen Poren in der Membran nachgewiesen werden. Dies lässt darauf schließen, dass im Gegensatz zu den homologen Komplexen in Eukaryoten, der bakterielle Sec Komplex intrinsisch die Permeabilitätsbarriere für Ionen aufrechterhält. Die vorliegenden Ergebnisse legen nahe, dass weder die Ausbildung ionenpermeabler Poren, noch deren Regulation zwischen den Sec Komplexen von Bakterien, Hefen und Säugern vollständig konserviert ist. In einem zweiten Teilprojekt wurden auf der Suche nach der zentralen Proteinimportpore in der äußeren Mitochondrienmembran von Trypanosoma brucei zwei mögliche Kandidaten, TbSam50 und ATOM, anhand elektrophysiologischer Untersuchungen verglichen. Beide waren in der Lage in planaren Bilayern ionenpermeable Poren auszubilden. Die elektrophysiologischen Grundcharakteristika dieser Poren, wie der hohe Leitwert und die Selektivität für Kationen sowie die beobachtete Interaktion mit mitochondrialen Präsequenzen, stimmen gut mit einer potentiellen Funktion als Proteinimportpore überein. Eine detaillierte Untersuchung der Einzelkanaleigenschaften zeigte, dass TbSam50 beträcht-liche Ähnlichkeiten zu homologen Proteinen in Hefen und menschlichen Zellen aufweist. Somit bestätigen die hier präsentierten Ergebnisse die Identifikation von TbSam50 als Kern der trypanosomalen Assemblierungsmaschinerie für β-barrel Proteine in der äußeren Mitochondrienmembran. Besonderheiten in der Beeinflussung der Kanaleigenschaften durch mitochondriale Präpeptide, insbesondere die erhöhte Verweildauer des Kanals im geschlossenen Zustand, weisen darauf hin, dass TbSam50 keine duale Funktion als β-barrel Insertase und Proteintranslokase besitzt. Hingegen lieferte die elektrophysiologische Charakterisierung von ATOM Hinweise, welche die Identifikation dieses Proteins als porenbildende Untereinheit des mitochondrialen Proteinimportapparates in T. brucei bestätigen. Darüber hinaus zeigten Vergleiche der elektrophysiologischen Charakteristika, insbesondere des Schaltverhaltens und der Anzahl porenbildender Untereinheiten pro aktiver Einheit im artifiziellen Bilayer, dass ATOM stärkere Ähnlichkeiten zu Proteintranslokasen bakterieller Abstammung aufweist, als zu Tom40, der generellen Importpore der Eukaryoten. Dies unterstützt das auf Sequenzvergleichen basierende Model, dass ATOM ein evolutives Relikt repräsentiert, anhand dessen die Entwicklung der mitochondrialen Proteinimportmaschinerie aus einer bakteriellen, Omp85-artigen Protein-exportpore abgeleitet werden kann.

In cases where refuge acquisition or captive breeding programs are not practical or justifiable, wild caught animals are frequently translocated into areas of suitable habitat. Such management programs seldom are designed to account for the behavioral responses of translocated animals to an unfamiliar habitat, breakup of social units, and/or interactions with existing social units in the new habitat. Ongoing efforts to translocate threatened Utah prairie dogs (Cynomys parvidens) from areas where conflicts with other land uses are occurring to public land sites have met with limited success. This could be due, in part, to behavioral responses associated with disrupting social units and placing animals in an unfamiliar environment. The purpose of this research was to test a series of hypotheses regarding the behavioral responses of Utah prairie dogs to translocation. Focal animal sampling was used to estimate the durations and frequencies of five behavioral variables and five interaction types at four treatments: control, new site, supplemental site, and new population. In Chapter 1, activity budgets were compared among control animals, animals released into a new site versus a supplemental site, and animals already present at a supplemental site. The objective was to evaluate the relative effects of new and supplemental translocations and the effects of translocations on resident animals. In Chapter 2, the frequencies of interactions were compared among these same treatments to evaluate the effects of translocation on the sociality of Utah prairie dogs as reflected by changes in the frequencies of greeting displays, dominance/subordinance displays, and amicable and agonistic interactions. Chapter 3 compares the activity budgets of animals released at a site containing natural burrows (i.e., new population) and animals released into a site containing artificial burrows (i.e., new site) to a control. Habitat measurements for these treatments were also compared to evaluate the importance of habitat characteristics typical of prairie dog colonies to translocated animals. Hotelling's T2 analyses were used to compare behavioral durations between treatments and log-linear analyses were use to compare behavioral frequencies among treatments. Activity budgets were altered by translocation through tradeoffs between the amount of time spent foraging, being vigilant, exploring the unfamiliar habitat, and minimizing conspicuousness. Predicted changes in interactions frequencies as a result of translocations were not observed. Activity budgets of animals released into the site containing natural burrows did not differ from those of control animals . The most important behavioral consideration is the effects of burrow and habitat characteristics in providing centers of activity and effective predator detection and avoidance.

The absorption, translocation and metabolism of 1,3-dichloropropene (a soil fumigant) in bush beans, tomato and carrot was studied under growth chamber and greenhouse conditions using solution culture, vermiculite and sand. Absorption was monitored using gas chromatographic analysis and isotope techniques. Plants were shown to absorb a maximum amount of dichloropropene by 24 to 48 hr from solution culture and vermiculite. The plant absorbed and translocated 1,3-dichlorpropene-14C-U readily to aerial parts of the plant. Bush beans, tomatoes and carrots absorbed and translocated 3-chlorallyl alcohol-14C-U from solution culture and vermiculite. Levels of 3-chloroallyl alcohol reached maximum at 24 to 48 hr after inoculation The gas chromatographic analysis of plant materials showed that 1,3-dichloropropene and 3-chloroallyl alcohol were rapidly metabolized by the plant. The three plants metabolize 1,3-dichloropropene to 3-chloroallyl alcohol, part of which is converted to 3-choroacrylic acid and 3-chloro-1-propanol. The metabolite identities were convirmed by co-chromatography with standard compounds and by mass spectral analysis. The sequence from this point (3-chloroacrylic of 3-chloro-1-propanol) is not known but coupled with the evidence from metabolite studies, it is apparent that a central metabolite (acetate pathway is indicated) has to be an intermediate in dichloropropene metabolism as label is located in glucose, TCA acids, amino acids, lipids and other normal plant products. The dichloropropenes are rapidly absorbed, translocated and metabolized by the plant. No parent dichloropropene was found in the plant after 72 hr incubation period and 3-chloroallyl alcohol was not detected after 96 hr in the plant. The data indicates that the dichloropropenes and 3-chloroallyl alcohols are not potential residue problems and that environmental concern about the ultimate fate of these compounds should be minimal.

Since man first grew crops on calcareous soils he has probably been troubled with what we today call lime-induced chlorosis. This chlorosis has determined whether he grew certain desirable ornamentals or crops or whether he had to substitute others which were less desirable. Lime-induced chlorosis is spread world wide. It has been reported in the vine and fruit growing regions of Europe, in the chernozem soils of Russia, and many other areas where the rainfall is relatively low and the soil is relatively high in calcium carbonate. In the United States it most frequently occurs where the average annual rainfall is less than 30 inches. The conditions causing chlorosis are not stable, for it varies from year to year and even from week to week with changing conditions in climate and soil. An estimated 500,000 acres of crops grown in the western United States on calcareous soils are subject to moderate to severe chlorosis. This physiological malady has challenged the technical ingenuity of outstanding plant and soil scientists. The exact cause or causes have never been isolated; consequently no permanent preventative measures or cures can, as yet, be recommended.

Mussel populations diminished from freshwaters in Europe during the 20th century, both due to human harvest and hydropower constructions. Therefore, substantial efforts have been dedicated towards restoration and reintroduction operations. Nevertheless, few studies have assessed mussel behavior in response to substrate and within stream preferences, which makes reintroduction operations uncertain and short of scientific guidelines. The aim of this study was to evaluate the importance of environmental factors for pearl mussel habitat selection and thus, provide knowledge that may make mussel introduction more successful. I investigated the behavior of freshwater pearl mussels (Margaritifera margaritifera) following introduction in a stream (Gäddbäcken) in Northern Sweden. Here, I used short behavioral trials and stream surveys to assess pearl mussel habitat preference (substrate, stream depth and water velocity) when introduced in novel environments. When comparing juvenile and adult pearl mussel behavior in my laboratory trials, I found that juvenile pearl mussels are more active (faster to do their first move) than adult mussels. In the within stream experiment, I found that there was a high correlation between water velocity and remaining pearl mussels, where mussels were more common in water with a velocity of 0.5 m/s than at lower velocities. Also, there was a positive correlation between water depth and remaining pearl mussels, where pearl mussels increased in abundance at depth over 0.3 m. My results suggesting that within stream conditions (water depth and stream velocity) can to a large part explain the pearl mussel presence at different localities in the stream. In other words, to increase the likelihood of successful introduction of pear mussels, my study indicate that individuals should be introduced to stream velocities of around 0.5 m/s and a water depth of 0.3 - 0.45 m.

DNA end-resection and nuclear actin-based movements orchestrate clustering of double-strandbreaks (DSBs) into homology-directed repair (HDR) domains. Using genomic approaches, we analyze how actin nucleation by ARP2/3 affects damage-dependent and -independent 3D genome reorganization and facilitates pathologic repair. Chromosome conformation capture techniques (Hi-C) reveal multi-scale alterations in genome organization following damage, including changes in chromatin insulation and compartmentalization. Nuclear actin polymerization promotes interactions between DSBs, which in turn facilitates aberrant intra- and inter-chromosomal rearrangements as visualized by high-throughput translocation assays (HTGTS). Notably, BRCA1 deficiency, which decreases end-resection, DSB mobility, and subsequent HDR, nearly abrogates recurrent translocations between AsiSI DSBs. In contrast, loss of functional BRCA1 yields unique translocations genome-wide, reflecting a critical role in preventing spontaneous genome instability and subsequent rearrangements. Our work establishes that the assembly of DSB repair domains is coordinated with multiscale alterations in genome architecture that enable HDR despite increased risk of translocations with pathologic potential.

No description available.