Coordinating conservation: global networking for species survival

The Species Survival Commission (SSC) of IUCN—the World Conservation Union is the largest, most comprehensive and diverse professional conservation network in existence today. It brings together over 6000 volunteers from more than 160 countries to contribute to the conservation of biological diversity by developing and executing programmes to study, save, restore, and manage wisely species and their habitats. The SSC is organized primarily along taxonomic lines, with members distributed in 96 Specialist Groups focusing on distinct groups of species. These groups are a source of the most current and expert information on the conservation status and priorities for action for species in the wild. As such, they provide an invaluable resource in setting priorities for captive propagation and in linking ex situ actions. In addition, the SSC has five disciplinary Specialist Groups that provide expertise to both the zoo community and field conservationists in areas such as reintroductions, veterinary medicine, captive breeding as a conservation tool, and the impact of invasive species on native flora and fauna. The effectiveness of the SSC is greatly enhanced by the close connections within its network between zoo professionals, academic scientists, field conservationists, and managers of natural resources. Challenges to the SSC currently include better information management, organization at the national level, and extending coverage in areas such as marine biodiversity.     

COMPARATIVE REPRODUCTIVE BIOLOGY OF ACER PENSYLVANICUM AND A. SPICATUM (ACERACEAE)

Pollination mechanisms and floral features affecting reproduction were examined in two closely-related species, Acer pensylvanicum and A. spicatum. Intra-specific crossing experiments, studies of pollen stainability and ovule number, and observations of the flowers in the field revealed that neither species bears functionally hermaphroditic flowers. Three flower-types were found in each species: staminate, pistillate, and a third type that is morphologically hermaphroditic. The latter form sheds viable pollen, but the pistil does not contain ovules. Pollen-ovule ratios of both species are in the range of expectation for a facultatively xenogamous reproductive system. Outcrossing is accomplished by entomophily in both species. A variety of insects from several orders visit the flowers; however bees in the genus Andrena (Hymenoptera: Andrenidae), especially A. milwaukeensis, are considered the most important pollinators of both maple species because of their fidelity to Acer, their intrafloral behavior, and their ability to carry pollen. However, flies are the most abundant visitors to A. pensylvanicum. Apomixis is an important means of reproduction in A. spicatum. Although floral phenology of these maple species overlaps within a geographical region they were never found blooming simultaneously when growing together.     

Nanosecond fluctuations of the molecular backbone of collagen in hard and soft tissues: a carbon-13 nuclear magnetic resonance relaxation study

We have determined the amplitude of nanosecond fluctuations of the collagen azimuthal orientation in intact tissues and reconstituted fibers from an analysis of 13C NMR relaxation data. We have labeled intact rat calvaria and tibia collagen (mineralized and cross-linked), intact rat tail tendon and demineralized bone collagen (cross-linked), and reconstituted lathyritic (non-cross-linked) chick calvaria collagen with [2-13C]glycine. This label was chosen because one-third of the amino acid residues in collagen are glycine and because the 1H-13C dipolar coupling is the dominant relaxation mechanism. Spin-lattice relaxation times (T1) and nuclear Overhauser enhancements were measured at 15.09 and 62.98 MHz at 22 and -35 degrees C. The measured NMR parameters have been analyzed by using a dynamic model in which the azimuthal orientation of the molecule fluctuates as a consequence of reorientation about the axis of the triple helix. We have shown that if root mean square fluctuations in the azimuthal orientations are small, gamma rms much less than 1 rad, the correlation function decays with a single correlation time tau and T1 depends only upon tau and gamma rms and not the detailed model of motion. Our analysis shows that, at 22 degrees C, tau is in the 1-5-ns range for all samples and gamma rms is 10 degrees, 9 degrees, and 5.5 degrees for the non-cross-linked, cross-linked, and mineralized samples, respectively. At -35 degrees C, gamma rms is less than 3 degrees for all samples. These results show that mineral and low temperature significantly restrict the amplitude of nanosecond motions of the collagen backbone.(ABSTRACT TRUNCATED AT 250 WORDS)