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Biological Unit (biological + unit)
Selected AbstractsGenetic population structure of marine fish: mismatch between biological and fisheries management unitsFISH AND FISHERIES, Issue 4 2009Henning Reiss Abstract An essential prerequisite of a sustainable fisheries management is the matching of biologically relevant processes and management action. In fisheries management and assessment, fish stocks are the fundamental biological unit, but the reasoning for the operational management unit is often indistinct and mismatches between the biology and the management action frequently occur. Despite the plethora of population genetic data on marine fishes, to date little or no use is made of the information, despite the fact that the detection of genetic differentiation may indicate reproductively distinct populations. Here, we discuss key aspects of genetic population differentiation in the context of their importance for fisheries management. Furthermore, we evaluate the population structure of all 32 managed marine fish species in the north-east Atlantic and relate this structure to current management units and practice. Although a large number of studies on genetic population structure have been published in the last decades, data are still rare for most exploited species. The mismatch between genetic population structure and the current management units found for six species (Gadus morhua, Melanogrammus aeglefinus, Merlangius merlangus, Micromesistius poutassou, Merluccius merluccius and Clupea harengus), emphasizes the need for a revision of these units and questions the appropriateness of current management measures. The implementation of complex and dynamic population structures into novel and less static management procedures should be a primary task for future fisheries management approaches. [source] Type II dehydroquinase: molecular replacement with many copiesACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2008Kirsty Anne Stewart Type II dehydroquinase is a small (150-amino-acid) protein which in solution packs together to form a dodecamer with 23 cubic symmetry. In crystals of this protein the symmetry of the biological unit can be coincident with the crystallographic symmetry, giving rise to cubic crystal forms with a single monomer in the asymmetric unit. In crystals where this is not the case, multiple copies of the monomer are present, giving rise to significant and often confusing noncrystallographic symmetry in low-symmetry crystal systems. These different crystal forms pose a variety of challenges for solution by molecular replacement. Three examples of structure solutions, including a highly unusual triclinic crystal form with 16 dodecamers (192 monomers) in the unit cell, are described. Four commonly used molecular-replacement packages are assessed against two of these examples, one of high symmetry and the other of low symmetry; this study highlights how program performance can vary significantly depending on the given problem. In addition, the final refined structure of the 16-dodecamer triclinic crystal form is analysed and shown not to be a superlattice structure, but rather an F -centred cubic crystal with frustrated crystallographic symmetry. [source] Structure of the conserved hypothetical protein MAL13P1.257 from Plasmodium falciparumACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2006Margaret A. Holmes The structure of a conserved hypothetical protein, PlasmoDB sequence MAL13P1.257 from Plasmodium falciparum, Pfam sequence family PF05907, has been determined as part of the structural genomics effort of the Structural Genomics of Pathogenic Protozoa consortium. The structure was determined by multiple-wavelength anomalous dispersion at 2.17,Å resolution. The structure is almost entirely ,-sheet; it consists of 15 ,-strands and one short 310 -helix and represents a new protein fold. The packing of the two monomers in the asymmetric unit indicates that the biological unit may be a dimer. [source] Microgeographic population structure of brook charr: a comparison of microsatellite and mark-recapture dataJOURNAL OF FISH BIOLOGY, Issue 3 2003B. K. Adams Polymorphism at five microsatellite genetic markers (genotyped n = 496) and mark-recapture tagging data (tagged n = 9813) were used to define the population structure of brook charr, Salvelinus fontinalis from the Indian Bay watershed, Newfoundland, Canada. Despite the absence of physical barriers to migration among lakes, both genetic and tagging data suggest that brook charr in each lake represent reproductively isolated populations. Exact tests comparing allele frequencies, , (global value = 0·063), Rst (global value = 0·052), individual assignment tests, and Nei's genetic distance provided congruent estimates of population subdivision in agreement with the tagging data (only 2·2% of recaptures were lake-to-lake). The genetic structure of the brook charr populations corresponded with the geographic structure of the drainage basin on a qualitative level, although linear distance over water was not significantly correlated with the tagging data or the genetic distance measures. The agreement between the tagging and the genetic data suggest that microsatellite markers can be useful tools for defining real biological units. The results also suggest that brook charr exhibit microgeographic population structure at the watershed scale, and that this is the scale at which conservation and management of this salmonid might best be implemented. [source] | |||||||||||||