The thermohaline expressway: the Southern Ocean as a centre of origin for deep-sea octopuses

Understanding how environmental forcing has generated and maintained large-scale patterns of biodiversity is a key goal of evolutionary research and critical to predicting the impacts of global climate change. We suggest that the initiation of the global thermohaline circulation provided a mechanism for the radiation of Southern Ocean fauna into the deep sea. We test this hypothesis using a relaxed phylogenetic approach to coestimate phylogeny and divergence times for a lineage of octopuses with Antarctic and deep-sea representatives. We show that the deep-sea lineage had their evolutionary origins in Antarctica, and estimate that this lineage diverged around 33?million years ago (Ma) and subsequently radiated at 15?Ma. Both of these dates are critical in development of the thermohaline circulation and we suggest that this has acted as an evolutionary driver enabling the Southern Ocean to become a centre of origin for deep-sea fauna. This is the first unequivocal molecular evidence that deep-sea fauna from other ocean basins originated from Southern Ocean taxa and this is the first evidence to be dated.

Substantial genetic divergence between morphologically indistinguishable populations of Fasciola suggests the possibility of cryptic speciation.

The liver flukes, Fasciola hepatica and Fasciola gigantica, are considered to be sister species and between them present a major threat worldwide to livestock production. In this study sequence data have been employed from informative regions of the nuclear and mitochondrial genomes of over 200 morphologically F. hepatica-like or F. gigantica-like flukes from Europe, sub-Saharan Africa and South Asia to assess genetic diversity. Evidence is presented for the existence of four well-separated clades: African gigantica-like flukes, Indian gigantica-like flukes, European hepatica-like flukes and African high-altitude hepatica-like flukes. Application of the Biological Species Concept to trematodes is problematic; however, the degree of separation between these groups was sufficient for them to be considered as distinct species using the four times rule for speciation.

The Effect of Human RIghts on Criminal Evidentiary Processes: Convergence, Divergence or Realignment?

This article examines the contribution which the European Court of Human Rights has made to the development of common evidentiary processes across the common law and civil law systems of criminal procedure in Europe. It is argued that the continuing use of terms such as 'adversarial' and 'inquisitorial' to describe models of criminal proof and procedure has obscured the genuinely transformative nature of the Court's jurisprudence. It is shown that over a number of years the Court has been steadily developing a new model of proof that is better characterised as 'participatory' than as 'adversarial' or 'inquisitorial'. Instead of leading towards a convergence of existing 'adversarial' and 'inquisitorial' models of proof, this is more likely to lead towards a realignment of existing processes of proof which nonetheless allows plenty of scope for diverse application in different institutional and cultural settings.

Escape times for rigid Brownian rotators in a bistable potential from the time evolution of the Green function and the characteristic time of the probability evolution

The greatest relaxation time for an assembly of three- dimensional rigid rotators in an axially symmetric bistable potential is obtained exactly in terms of continued fractions as a sum of the zero frequency decay functions (averages of the Legendre polynomials) of the system. This is accomplished by studying the entire time evolution of the Green function (transition probability) by expanding the time dependent distribution as a Fourier series and proceeding to the zero frequency limit of the Laplace transform of that distribution. The procedure is entirely analogous to the calculation of the characteristic time of the probability evolution (the integral of the configuration space probability density function with respect to the position co-ordinate) for a particle undergoing translational diffusion in a potential; a concept originally used by Malakhov and Pankratov (Physica A 229 (1996) 109). This procedure allowed them to obtain exact solutions of the Kramers one-dimensional translational escape rate problem for piecewise parabolic potentials. The solution was accomplished by posing the problem in terms of the appropriate Sturm-Liouville equation which could be solved in terms of the parabolic cylinder functions. The method (as applied to rotational problems and posed in terms of recurrence relations for the decay functions, i.e., the Brinkman approach c.f. Blomberg, Physica A 86 (1977) 49, as opposed to the Sturm-Liouville one) demonstrates clearly that the greatest relaxation time unlike the integral relaxation time which is governed by a single decay function (albeit coupled to all the others in non-linear fashion via the underlying recurrence relation) is governed by a sum of decay functions. The method is easily generalized to multidimensional state spaces by matrix continued fraction methods allowing one to treat non-axially symmetric potentials, where the distribution function is governed by two state variables. (C) 2001 Elsevier Science B.V. All rights reserved.

Structure and kinetics of phosphonopyruvate hydrolase from Variovorax sp. Pal2: New insight into the divergence of catalysis within the PEP mutase/isocitrate lyase superfamily .

Phosphonopyruvate (P-pyr) hydrolase (PPH), a member of the phosphoenolpyruvate (PEP) mutase/isocitrate lyase (PEPM/ICL) superfamily, hydrolyzes P-pyr and shares the highest sequence identity and functional similarity with PEPM. Recombinant PPH from Variovorax sp. Pal2 was expressed in Escherichia coli and purified to homogeneity. Analytical gel filtration indicated that the protein exists in solution predominantly as a tetramer. The PPH pH rate profile indicates maximal activity over a broad pH range.The steady-state kinetic constants determined for a rapid equilibrium ordered kinetic mechanism with Mg+2 binding first (Kd =140 ± 40 M), are kcat = 105 ± 2 s-1 and P-pyr Km = 5 ± 1 M. PEP (slow substrate kcat = 2 × 10-4 s-1), oxalate, and sulfopyruvate are competitive inhibitors with Ki values of 2.0 ± 0.1 mM, 17 ± 1 M, and 210 ± 10 M, respectively. Three PPH crystal structures have been determined, that of a ligand-free enzyme, the enzyme bound to Mg2+ and oxalate (inhibitor), and the enzyme bound to Mg2+ and P-pyr (substrate). The complex with the inhibitor was obtained by cocrystallization, whereas that with the substrate was obtained by briefly soaking crystals of the ligand-free enzyme with P-pyr prior to flash cooling. The PPH structure resembles that of the other members of the PEPM/ICL superfamily and is most similar to the functionally related enzyme, PEPM. Each monomer of the dimer of dimers exhibits an (/)8 barrel fold with the eighth helix swapped between two molecules of the dimer. Both P-pyr and oxalate are anchored to the active site by Mg2+. The loop capping the active site is disordered in all three structures, in contrast to PEPM, where the equivalent loop adopts an open or disordered conformation in the unbound state but sequesters the inhibitor from solvent in the bound state. Crystal packing may have favored the open conformation of PPH even when the enzyme was cocrystallized with the oxalate inhibitor. Structure alignment of PPH with other superfamily members revealed two pairs of invariant or conservatively replaced residues that anchor the flexible gating loop. The proposed PPH catalytic mechanism is analogous to that of PEPM but includes activation of a water nucleophile with the loop Thr118 residue.