Effect of mutation on genetic differentiation among nonequilibrium populations

The usefulness of GST and similar measures of genetic differentiation has been questioned repeatedly because of their dependence on the amount of heterozygosity within populations, creating problems when comparing degrees of divergence at loci with different mutation rates. Although the effect of mutation on GST is expected to be small in the early phases of divergence, it is unclear for how long after separation from a common ancestral population that GST is largely unaffected by mutation and by the resulting effect on heterozygosity. We address this question through analysis of the recursion equations for gene identity under the infinite allele model of mutation, and derive conditions describing when the effect of mutation on GST can be ignored under mutation-migration-drift equilibrium conditions and during the preceding transition phase. An important result is that during the transition phase GST is not only affected by mutation, but also by the heterozygosity in the base population from which the subpopulations diverged. The effect of mutation on GST is significant from the very start of the divergence process when initial heterozygosity is low, whereas GST is only weakly affected by mutation in the early phases of differentiation when initial heterozygosity is high. Thus, differentiation following a severe bottleneck is strongly dependent on mutation. The standardized measure of differentiation, G'ST, suggested by Hedrick (2005), may be helpful when comparing amounts of divergence at loci with different mutation rates under steady-state conditions, provided that migration is very low. In many other situations the use of G'ST might be misleading, however, and its application should be exercised with caution.     

Carbon sequestration potential in European croplands has been overestimated

Yearly, per‐area carbon sequestration rates are used to estimate mitigation potentials by comparing types and areas of land management in 1990 and 2000 and projected to 2010, for the European Union (EU)‐15 and for four country‐level case studies for which data are available: UK, Sweden, Belgium and Finland. Because cropland area is decreasing in these countries (except for Belgium), and in most European countries there are no incentives in place to encourage soil carbon sequestration, carbon sequestration between 1990 and 2000 was small or negative in the EU‐15 and all case study countries. Belgium has a slightly higher estimate for carbon sequestration than the other countries examined. This is at odds with previous reports of decreasing soil organic carbon stocks in Flanders. For all countries except Belgium, carbon sequestration is predicted to be negligible or negative by 2010, based on extrapolated trends, and is small even in Belgium. The only trend in agriculture that may be enhancing carbon stocks on croplands at present is organic farming, and the magnitude of this effect is highly uncertain. Previous studies have focused on the potential for carbon sequestration and have shown quite significant potential. This study, which examines the sequestration likely to occur by 2010, suggests that the potential will not be realized. Without incentives for carbon sequestration in the future, cropland carbon sequestration under Article 3.4 of the Kyoto Protocol will not be an option in EU‐15.     

Molecular cloning and functional characterization of mouse coactosin-like protein.

Coactosin was first isolated from Dictyostelium discoideum and, as reported, human coactosin-like protein (CLP) was identified in a yeast two-hybrid screen using 5-lipoxygenase (5LO) as a bait. A mouse CLP (mCLP) cDNA clone was identified among EMBL/GenBank EST sequences. The derived amino acid sequence (142 residues) was 95.1% identical with human CLP. Here, we also show that mCLP interacts with actin and 5LO in the two-hybrid system. High-speed cosedimentation assays and GST-binding assays confirmed these protein interactions. In chemical cross-linking experiments, one molecule of mCLP was covalently linked to either one subunit of actin or one molecule of 5LO. The mCLP-F-actin and mCLP-5LO associations were pH-insensitive and Ca(2+)-independent. However, association with actin was best observed at low salt concentrations, while association with 5LO was favored by salt, indicating different binding characteristics.     

The determination of acetaldehyde in blological samples by head-space gas chromatography

A method for the determination of acetaldehyde (AcH) in biological samples by head-space gas chromatography is presented. Human venous blood (antecubital), rat blood (heart-punctured) rat liver (freeze-clamped), and rat and mouse brain (freeze-clamped) were used as the biological samples. The method involves two steps, in the first of which the samples are deproteinized with perchloric acid (PCA). Rat blood can, alternatively, be hemolyzed with water. In the second step, the deproteinized supernatant or hemolyzed blood is pipetted into a serum bottle, which is sealed with a rubber stopper and brought to 65°C in a sampling turntable. Head-space samples are then automatically taken for GLC analysis. Ethanol causes a nonenzymatic formation of AcH in the PCA supernatants of liver and brain, which can be inhibited by the use of thiourea. This reaction is minor in the blood supernatants and cannot be inhibited there by thiourea. The method described measures the total AcH content without regard to any binding. Some of the AcH in rat blood was shown to be bound.     

Long-term development in a Baltic fish community exposed to bleached pulp mill effluent

Observations near a Swedish pulp mill at the Bothnian Sea during 1982-1992 revealed low fish abundance and a disturbed community structure. The presence of endocrine disrupting or toxic substances in effluent water was indicated by biomarker responses, impaired reproduction and stimulated growth in perch (Perca fluviatilis). In 1992 the bleaching process was altered and a secondary treatment system was installed, improving the quality and decreasing the amount of effluent. This paper presents the results of follow-up studies during 1995-1998 with the objective to analyse any recovery of the fish community due to changes in mill operations. Although abundance and diversity of the fish community did recover, an effect of enrichment, indicated by high catches of cyprinids, was still visible in the vicinity of the mill outlet. Sexual maturation was delayed, gonad development was retarded, average growth rate was faster, and the condition factor was higher in perch caught in the vicinity of the effluent outlet, than in perch captured elsewhere. It is concluded that substances inhibiting reproduction and causing growth disturbance were still present in the effluents in effective concentrations.     

Notes on the genus Erythrochlamys (Lamiaceae)

A new species of the genus Erythrochlamys is described: E. frulicosa from Somalia and Ethiopia. An interesting variation in E, leucosphaera is also discussed.     

Effect of back reactions in the S-cycle on photosynthesis in very weak light

Photosynthesis in light which is so weak that excitation rates are comparable to the decay rates of S-states is modelled. It is found that oxygen evolution rate varies in a non-linear way with Photosystem II excitation rate in this region, but asymptotically approaches a linear relationship (with a slope of one oxygen molecule per four excitations) as excitation rate increases. The asymptote gives an intercept (zero oxygen evolution rate) on the excitation rate axis. The question is raised, whether this model is compatible with photoautotrophy in a red alga found at 268 m depth and able to carry out photosynthesis in extremely weak light. It is found that no unorthodox mechanisms for the S-cycle in this alga have to be assumed to explain its performance.     

The occurrence of haemosporidian parasites in the Fennoscandian bluethroat ( Luscinia svecica) population

A total of 86 adult bluethroats (Luscinia svecica) from nine different localities, covering the full length of the Fennoscandian mountain range, were screened for blood parasites of the three genera Haemoproteus, Plasmodium and Leucocytozoon using a recently developed polymerase chain reaction method. The overall occurrence of infection was 59.3%. Prevalence of Leucocytozoon spp. (47.7%), Plasmodium spp. (23.3%) and Haemoproteus spp. (1.2%) was detected. Of the infected birds, 15.1% carried mixed infections. Five different mitochondrial DNA-lineages of Leucocytozoon spp., eight lineages of Plasmodium spp. and one lineage of Haemoproteus spp. were found. Due to large sequence divergence these corresponded to at least five different species, but with the possibility of all 14 being independent evolutionary units with the potential of evolving different effects on the host. Of the lineages of Leucocytozoon spp., the most common was found throughout the range. The occurrence of the second most common lineage of Leucocytozoon spp. showed significant variation in prevalence between sites. The data also showed molecular evidence of one lineage of Leucocytozoon sp. existing in more than one species of avian host, thus challenging the use of host taxon as a taxonomic character when distinguishing between different species leucocytozoids.Communicated by F. Bairlein