Crystal structure of biotin synthase, an S-adenosylmethionine-dependent radical enzyme

The crystal structure of biotin synthase from Escherichia coli in complex with S-adenosyl-L-methionine and dethiobiotin has been determined to 3.4 angstrom resolution. This structure addresses how "AdoMet radical" or "radical SAM" enzymes use Fe4S4 clusters and S-adenosyl-L-methionine to generate organic radicals. Biotin synthase catalyzes the radical-mediated insertion of sulfur into dethiobiotin to form biotin. The structure places the substrates between the Fe4S4 cluster, essential for radical generation, and the Fe2S2 cluster, postulated to be the source of sulfur, with both clusters in unprecedented coordination environments.     

High-quality binary protein interaction map of the yeast interactome network

Current yeast interactome network maps contain several hundred molecular complexes with limited and somewhat controversial representation of direct binary interactions. We carried out a comparative quality assessment of current yeast interactome data sets, demonstrating that high-throughput yeast two-hybrid (Y2H) screening provides high-quality binary interaction information. Because a large fraction of the yeast binary interactome remains to be mapped, we developed an empirically controlled mapping framework to produce a "second-generation" high-quality, high-throughput Y2H data set covering approximately 20% of all yeast binary interactions. Both Y2H and affinity purification followed by mass spectrometry (AP/MS) data are of equally high quality but of a fundamentally different and complementary nature, resulting in networks with different topological and biological properties. Compared to co-complex interactome models, this binary map is enriched for transient signaling interactions and intercomplex connections with a highly significant clustering between essential proteins. Rather than correlating with essentiality, protein connectivity correlates with genetic pleiotropy.     

Ultraviolet radiation levels during the antarctic spring

The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic "ozone hole" remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.     

A phylogenomic study of birds reveals their evolutionary history

Deep avian evolutionary relationships have been difficult to resolve as a result of a putative explosive radiation. Our study examined approximately 32 kilobases of aligned nuclear DNA sequences from 19 independent loci for 169 species, representing all major extant groups, and recovered a robust phylogeny from a genome-wide signal supported by multiple analytical methods. We documented well-supported, previously unrecognized interordinal relationships (such as a sister relationship between passerines and parrots) and corroborated previously contentious groupings (such as flamingos and grebes). Our conclusions challenge current classifications and alter our understanding of trait evolution; for example, some diurnal birds evolved from nocturnal ancestors. Our results provide a valuable resource for phylogenetic and comparative studies in birds.     

Cross-fostering in coyotes: Evaluation of a potential conservation and research tool for canids

Cross-fostering has been attempted opportunistically with endangered canids as a means of increasing populations. Due to the usefulness of cross-fostering for conservation, an understanding of factors influencing success rates is essential. Using captive coyotes (Canis latrans) as a model, we assessed the willingness of adult pairs to foster young born to other parents. We assessed the efficacy of fostering pups into existing litters (augmentation) and completely switching litters (replacement). We augmented four litters with two pups of similar age when pups were <7 days old. In addition, we replaced four entire litters when pups were <10 days old. We also augmented litters with pups 3-4 and 6-7 weeks of age. Survival, weight gain, and dominance status of pups were monitored for six weeks and compared to four control litters to determine success. All complete litter replacements were successful with survival rates among replaced pups (89.5%) similar to those of control litters (90%). For augmented litters, pup survival was dependent on the age at which fostering occurred. All pups fostered into 4 litters at <1 week of age survived beyond 6 weeks of age, two of three fostering attempts with 3-4-week-old pups succeeded, while neither of two attempts to foster 6-week-old pups succeeded. Surviving fostered pups appeared to be at no disadvantage. Weight gains were similar for pups in all treatments, and there was no evidence of reduced dominance status among fostered pups as compared to natal pups in the same litters. These results illustrate that genetic relatedness is not essential for successful fostering and does not appear to alter dominance patterns; however the age at which pups are fostered may affect the success of fostering attempts.     

Genetic variability and relationships in nine South African cattle breeds using microsatellite markers

Tropical Animal Health and Production - Genetic variability within and between breeds allows adaptation to a changing environment and consequently prepares producers for the future. Eleven...     

Eucalyptus benthamii Maiden et Cambage growth and wood density in integrated crop-livestock systems

Integrating trees in agricultural landscapes is a promising option to sustainably provide goods for society while increasing biodiversity, securing animal welfare, and generating profits for stakeholders. The choice of the species and knowing how timber quality is affected when trees are integrated to crop and/or livestock enterprises can provide additional insights into the usefulness of timber after harvest, and wood density is one of the most important properties in this regard. The present study aimed to evaluate how Eucalyptus benthamii growth and wood density are affected in integrated crop-livestock systems when compared to monoculture forestry 74 months after planting in subtropical environments. The integrated systems were in an alley cropping design where crop and/or grazed pasture were temporally rotated in between tree lines (14?×?2 m trees spacing), and those systems were compared to monoculture forestry (3?×?2 m spacing). Tree trunks (n?=?60) were sampled in five diameter classes of each treatment by cutting disks in six positions of the trunk (0.1 m, 1.30 m, 25%, 50%, 75% and 90% of the total height) (n?=?360). Trees growing in integrated systems increased trunk diameter at breast height by 24.7%, increased wood fiber production per tree by 17.9%, and produced wood 9.0% less dense than in the monoculture forestry system. Monoculture forestry increased tree height, and there was no difference of trunk volume among the production systems. The results suggest that integrated systems can produce timber with lower wood density, but faster individual tree growth than in forestry monocultures. Such a system can promote sustainable intensification of agricultural production, and enhance provision of complementary ecosystem services.

     

Bird community assembly in Bornean industrial tree plantations: Effects of forest age and structure

Plantations of exotic trees for industrial and agricultural purposes are burgeoning in the tropics, and some of them offer the opportunity to study community ecology of animals in a simplified forest setting. We examined bird community assembly in different aged groves of the industrial tree mangium (Acacia mangium) at two plantations in Malaysian Borneo: Sabah Softwoods near Tawau, Sabah, and the Planted Forest Project, near Bintulu, Sarawak. Bird communities were compared among three age-groups of mangium (2-, 5-, and 7-years old) and logged native forest. Mangium rapidly developed into a secondary forest consisting of a wide diversity of understory trees and shrubs. The bird community correspondingly increased in species richness and diversity, and we were able to relate these increases specifically to canopy height, secondary canopy development, and shrub cover. Species of common, small bodied frugivores, nectarivores, and insectivores were diverse in older plantation groves, as were common mid-sized insectivores. However, large, specialized, and normally uncommon taxa (e.g., galliforms, pigeons, hornbills, barbets, midsized woodpeckers, muscicapine flycatchers, and wren babblers) were rare or nonexistent in the plantations. Because we lacked species-specific data on foraging, nesting, and other behaviors of most groups of birds, it was difficult to explain the precise causes of seral diversification in any group except woodpeckers, which have been well studied in Southeast Asia. Thus, in future, particular emphasis needs to be placed on obtaining such data. Industrial plantations, by virtue of their simple structure, variably aged groves, and bird community richness, are good places to gather such data.     

Trace elements in vegetation downwind of a coal-fired power plant

Concentrations of As, B, Br, Co, Cu, F, Ga, Li, Mo, Ni, Sr, V, and Zn were measured in samples of four different kinds of plant at distances of 8, 12, 16, 24, 40, 70, and 120 km downwind of a large coalfired power plant in New Mexico. Concentrations of B, Br, Co, Li, and Sr decreased with distance from the power plant in grasses, but not in shrubs. Fluorine concentrations decreased in stems of a shrub. These decreases, taken with concentration enrichment and solubility considerations, provide circumstantial evidence that at least B and F trends may be due to power plant stack emissions.