NEST DESERTION IN A REINTRODUCED POPULATION OF MIGRATORY WHOOPING CRANES

Reintroduction of an eastern migratory population of whooping cranes (Grus americana) into eastern North America began in 2001. Reproduction first occurred in 2005. Through 2008, eggs were produced in 22 first nests and 2 renests. All first nests failed–50% confirmed due to desertion by the parents and the remaining nest failures also consistent with the pattern of parental desertion. Nest failures were not related to stage of incubation, and they were often synchronous. Temperatures in winter and early spring affected timing of nest failure. An environmental factor such as harassment of incubating cranes by black flies (Simulium spp.) may be responsible for widespread nest desertion

TEN-YEAR STATUS OF THE EASTERN MIGRATORY WHOOPING CRANE REINTRODUCTION

From 2001 to 2010, 132 costume-reared juvenile whooping cranes (Grus americana) were led by ultralight aircraft from Necedah National Wildlife Refuge (NWR) in central Wisconsin to the Gulf Coast of Florida on their first autumn migration (ultralight-led or UL), and 46 juveniles were released directly on Necedah NWR during autumn of the hatch year (direct autumn release or DAR). Return rate in spring was 90.5% for UL and 69.2% for DAR, the lower value of the latter attributable to 1 cohort with migration problems. Overall population survival 1 year and from 1 to 3 years post-release was 81% and 84%, respectively. Survival 1 year post-release was significantly different between UL (85.1%) and DAR (65.7%) cranes. Since summer 2008, DAR migration and wintering have improved, winter distribution of the population has changed, the migration route of the population has shifted westward, and number of yearlings summering in locations used during spring wandering has increased. Human avoidance problems resulted in 2 birds being removed from the population. As in earlier years, homing to the natal area and prolific pair formation continued (29 of 31 adult pairs have formed in the core reintroduction area), predation continued to be the primary cause of mortality, and parental desertion of nests, especially during the initial (primary) nesting period, continued. During 2005-2010, all 43 of these early nests failed; of 15 late nests or renests, chicks hatched from 8 nests, and 3 chicks fledged. As of 31 March 2011, the population contained a maximum 105 individuals (54 males and 51 females) including 20 adult pairs

Plastid origin: who, when and why?

The origin of plastids is best explained by endosymbiotic theory, which dates back to the early 1900s. Three lines of evidence based on protein import machineries and molecular phylogenies of eukaryote (host) and cyanobacterial (endosymbiont) genes point to a single origin of primary plastids, a unique and important event that successfully transferred two photosystems and oxygenic photosynthesis from prokaryotes to eukaryotes. The nature of the cyanobacterial lineage from which plastids originated has been a topic of investigation. Recent studies have focused on the branching position of the plastid lineage in the phylogeny based on cyanobacterial core genes, that is, genes shared by all cyanobacteria and plastids. These studies have delivered conflicting results, however. In addition, the core genes represent only a very small portion of cyanobacterial genomes and may not be a good proxy for the rest of the ancestral plastid genome. Information in plant nuclear genomes, where most genes that entered the eukaryotic lineage through acquisition from the plastid ancestor reside, suggests that heterocyst-forming cyanobacteria in Stanier’s sections IV and V are most similar to the plastid ancestor in terms of gene complement and sequence conservation, which is in agreement with models suggesting an important role of nitrogen fixation in symbioses involving cyanobacteria. Plastid origin is an ancient event that involved a prokaryotic symbiont and a eukaryotic host, organisms with different histories and genome evolutionary processes. The different modes of genome evolution in prokaryotes and eukaryotes bear upon our interpretations of plastid phylogeny

Energy metabolism in anaerobic eukaryotes and Earth's late oxygenation

Eukaryotes arose about 1.6 billion years ago, at a time when oxygen levels were still very low on Earth, both in the atmosphere and in the ocean. According to newer geochemical data, oxygen rose to approximately its present atmospheric levels very late in evolution, perhaps as late as the origin of land plants (only about 450 million years ago). It is therefore natural that many lineages of eukaryotes harbor, and use, enzymes for oxygen-independent energy metabolism. This paper provides a concise overview of anaerobic energy metabolism in eukaryotes with a focus on anaerobic energy metabolism in mitochondria. We also address the widespread assumption that oxygen improves the overall energetic state of a cell. While it is true that ATP yield from glucose or amino acids is increased in the presence of oxygen, it is also true that the synthesis of biomass costs thirteen times more energy per cell in the presence of oxygen than in anoxic conditions. This is because in the reaction of cellular biomass with O2, the equilibrium lies very far on the side of CO2. The absence of oxygen offers energetic benefits of the same magnitude as the presence of oxygen. Anaerobic and low oxygen environments are ancient. During evolution, some eukaryotes have specialized to life in permanently oxic environments (life on land), other eukaryotes have remained specialized to low oxygen habitats. We suggest that the Km of mitochondrial cytochrome c oxidase of 0.1–10 μM for O2, which corresponds to about 0.04%–4% (avg. 0.4%) of present atmospheric O2 levels, reflects environmental O2 concentrations that existed at the time that the eukaryotes arose

Serpentinization: Connecting geochemistry, ancient metabolism and industrial hydrogenation

Rock–water–carbon interactions germane to serpentinization in hydrothermal vents have occurred for over 4 billion years, ever since there was liquid water on Earth. Serpentinization converts iron(II) containing minerals and water to magnetite (Fe3O4) plus H2. The hydrogen can generate native metals such as awaruite (Ni3Fe), a common serpentinization product. Awaruite catalyzes the synthesis of methane from H2 and CO2 under hydrothermal conditions. Native iron and nickel catalyze the synthesis of formate, methanol, acetate, and pyruvate—intermediates of the acetyl-CoA pathway, the most ancient pathway of CO2 fixation. Carbon monoxide dehydrogenase (CODH) is central to the pathway and employs Ni0 in its catalytic mechanism. CODH has been conserved during 4 billion years of evolution as a relic of the natural CO2-reducing catalyst at the onset of biochemistry. The carbide-containing active site of nitrogenase—the only enzyme on Earth that reduces N2—is probably also a relic, a biological reconstruction of the naturally occurring inorganic catalyst that generated primordial organic nitrogen. Serpentinization generates Fe3O4 and H2, the catalyst and reductant for industrial CO2 hydrogenation and for N2 reduction via the Haber–Bosch process. In both industrial processes, an Fe3O4 catalyst is matured via H2-dependent reduction to generate Fe5C2 and Fe2N respectively. Whether serpentinization entails similar catalyst maturation is not known. We suggest that at the onset of life, essential reactions leading to reduced carbon and reduced nitrogen occurred with catalysts that were synthesized during the serpentinization process, connecting the chemistry of life and Earth to industrial chemistry in unexpected ways

Lipids Are the Preferred Substrate of the Protist Naegleria gruberi, Relative of a Human Brain Pathogen

Naegleria gruberi is a free-living non-pathogenic amoeboflagellate and relative of Naegleria fowleri, a deadly pathogen causing primary amoebic meningoencephalitis (PAM). A genomic analysis of N. gruberi exists, but physiological evidence for its core energy metabolism or in vivo growth substrates is lacking. Here, we show that N. gruberi trophozoites need oxygen for normal functioning and growth and that they shun both glucose and amino acids as growth substrates. Trophozoite growth depends mainly upon lipid oxidation via a mitochondrial branched respiratory chain, both ends of which require oxygen as final electron acceptor. Growing N. gruberi trophozoites thus have a strictly aerobic energy metabolism with a marked substrate preference for the oxidation of fatty acids. Analyses of N. fowleri genome data and comparison with those of N. gruberi indicate that N. fowleri has the same type of metabolism. Specialization to oxygen-dependent lipid breakdown represents an additional metabolic strategy in protists. Bexkens et al. show that N. gruberi amoebae live preferably on lipids, for which they need oxygen, a lifestyle largely unknown among protists. This challenges existing views about its energy metabolism, with implications for treatment of its pathogenic relative, N. fowleri, the brain-eating agent of primary amoebic me

Cancer stem cell metabolism

Cancer is now viewed as a stem cell disease. There is still no consensus on the metabolic characteristics of cancer stem cells, with several studies indicating that they are mainly glycolytic and others pointing instead to mitochondrial metabolism as their principal source of energy. Cancer stem cells also seem to adapt their metabolism to microenvironmental changes by conveniently shifting energy production from one pathway to another, or by acquiring intermediate metabolic phenotypes. Determining the role of cancer stem cell metabolism in carcinogenesis has become a major focus in cancer research, and substantial efforts are conducted towards discovering clinical targets

THE ROLE OF RETRIEVAL AND TRANSLOCATION IN A REINTRODUCED POPULATION OF MIGRATORY WHOOPING CRANES

Beginning in 2001, a reintroduction project was initiated using captive-reared whooping cranes (Grus americana) to establish a migratory flock in eastern North America. From May 2003 to August 2008, 23 of these birds were retrieved and translocated in 15 separate events. These individuals consisted of 14 cranes that had been led to Florida by ultralight aircraft on their first autumn migration (UL) and 9 cranes that had been directly released in autumn in Wisconsin (DAR). Of 104 (86 UL and 18 DAR) reintroduced individuals that eventually departed from their release location, 22% were later retrieved 1-3 times. Lake Michigan posed an effective barrier to northward migrating yearlings, and 8 retrieval events were of birds in Lower Michigan or in other locations that were a direct result of the bird having been in Michigan during their yearling spring and summer. Three events involved DAR birds (n = 8) that were in inappropriate locations during their first autumn migration, and in another event 4 UL birds were translocated within Wisconsin because of inadequate human avoidance behavior. Nine yearlings (6 UL and 3 DAR) in Lower Michigan were not retrieved (retrievals were attempted for only 3 of the birds). The summer location of released birds influenced the location of return in future years. Concentration of this population in the core reintroduction area, where probability of pair formation and association with conspecifics was greatest, became a high project priority. Retrieval and translocation of yearlings to Wisconsin became a critical management tool in the reintroduction. With 1 exception, all translocated birds have successfully returned to the core reintroduction area by 2008, and several have paired and some nested

SURVIVAL, REPRODUCTION, AND MOVEMENTS OF MIGRATORY WHOOPING CRANES DURING THE FIRST SEVEN YEARS OF REINTRODUCTION

An effort to reintroduce a migratory population of whooping cranes (Grus americana) into eastern North America began in 2001. During 2001-2007, 125 juveniles were costume/isolation-reared and released: 106 were led by ultralight aircraft from Necedah National Wildlife Refuge (NWR), central Wisconsin, to Chassahowitzka NWR, central Gulf Coast of Florida, on their first autumn migration (ultralight-led or UL). The remaining 19 individuals were released directly on Necedah NWR during autumn of the hatch year (direct autumn release or DAR). Of 86 UL and 13 DAR cranes that completed their first spring migration, 72 (84%) and 5 (38%), respectively, returned unassisted as yearlings to central Wisconsin. Yearlings typically returned to Necedah NWR and then wandered to other spring locations, mainly in southern and eastern Wisconsin, but also to locations as far as 1,370 km distant. Most yearlings returned to central Wisconsin by early summer, especially males, and females associated with males. Lake Michigan posed an effective barrier to 16 yearlings that migrated too far eastward during spring migration. Some of these birds and others were retrieved and translocated. For UL cranes, 48% of returning bird-winters occurred in a primary wintering area within 88 km of the original release site and an additional 12% at a smaller area of concentration 82-103 km northward. Other UL and DAR cranes wintered at sites primarily in Florida, South Carolina, Tennessee, Alabama, or Indiana. Excluding 17 UL juveniles that died in a single weather-related event at the winter release site in 2007, 40 individuals (37% of those in the population) died during the first 7 years of the reintroduction. The primary cause was predation (minimally 50%). During 2005-2008, all 22 first nests with eggs failed. Of 2 renests during the same period, 2 chicks hatched from 1 nest and 1 chick fledged in 2006. Consistent nest failures were mainly synchronous and usually occurred on warm days. As of September 2008, the population contained a maximum 68 individuals (39 males and 29 females) including 12 adult pairs