Connectivity of Caribbean coral populations: complementary insights from empirical and modelled gene flow

Understanding patterns of connectivity among populations of marine organisms is essential for the development of realistic, spatially explicit models of population dynamics. Two approaches, empirical genetic patterns and oceanographic dispersal modelling, have been used to estimate levels of evolutionary connectivity among marine populations but rarely have their potentially complementary insights been combined. Here, a spatially realistic Lagrangian model of larval dispersal and a theoretical genetic model are integrated with the most extensive study of gene flow in a Caribbean marine organism. The 871 genets collected from 26 sites spread over the wider Caribbean subsampled 45.8% of the 1900 potential unique genets in the model. At a coarse scale, significant consensus between modelled estimates of genetic structure and empirical genetic data for populations of the reef-building coral Montastraea annularis is observed. However, modelled and empirical data differ in their estimates of connectivity among northern Mesoamerican reefs indicating that processes other than dispersal may dominate here. Further, the geographic location and porosity of the previously described east-west barrier to gene flow in the Caribbean is refined. A multi-prong approach, integrating genetic data and spatially realistic models of larval dispersal and genetic projection, provides complementary insights into the processes underpinning population connectivity in marine invertebrates on evolutionary timescales.     

Physiological and antioxidant responses of two accessions of Arabidopsis thaliana in different light and temperature conditions

During their lifetime, plants need to adapt to a changing environment, including light and temperature. To understand how these factors influence plant growth, we investigated the physiological and antioxidant responses of two Arabidopsis accessions, Shahdara (Sha) from the Shahdara valley (Tajikistan, Central Asia) in a mountainous area and Lovvik‐5 (Lov‐5) from northern Sweden to different light and temperature conditions. These accessions originate from different latitudes and have different life strategies, both of which are known to be influenced by light and temperature. We showed that both accessions grew better in high‐light and at a lower temperature (16°C) than in low light and at 23°C. Interestingly, Sha had a lower chlorophyll content but more efficient non‐photochemical quenching than Lov‐5. Sha, also showed a higher expression of vitamin E biosynthetic genes. We did not observe any difference in the antioxidant prenyllipid level under these conditions. Our results suggest that the mechanisms that keep the plastoquinone (PQ)‐pool in more oxidized state could play a role in the adaptation of these accessions to their local climatic conditions.     

Cyclodextrin production and genetic characterization of cyclodextrin glucanotranferase of <Emphasis Type="Italic">Paenibacillus graminis</Emphasis>

Paenibacillus graminis strains were described recently as cyclodextrin (CD) producers. Cyclodextrins are produced by cyclodextrin glucanotransferase (CGTase) which has not been characterized in P. graminis. Similar amounts of α- and β-CDs were produced by P. graminis (MC22.13) and P. macerans (LMD24.10^T). Primers were designed to sequence the gene encoding CGTase from P. graminis. A phylogenetic tree was constructed and P. graminis CGTase protein showed to be closer (79.4% protein identity) to P. macerans |P31835|. Hybridization studies suggested that the gene encoding CGTase is located in different positions in the genomes of P. macerans and P. graminis.     

Cellulolytic enzymes for the hydrolysis of leached beet cosette

Summary Cellulolytic fungi were isolated from rotting leaves and tested for extra-cellular cellulase activities (CMCase, avicelase, cellobiase and xylanase). The effect of the proportion of the enzyme activities on the rate of degradation of leached beet cosette was observed using a range of supernatant fluids in appropriate combinations. At low cosette concentrations (1.5–3.0 g/l), avicelase and cellobiase were the rate limiting enzymes; avicelase in the initial stages of reaction and cellobiase after 6–8 hours, when cellobiose inhibition becomes important. A ratio of celiobiase to avicelase of approx 2.0 was established as appropriate. At higher substrate concentrations (10 g/l, 40 g/l) the best cellobiase to avicelase ratio was maintained and up to 40% hydrolysis was obtained in the 10 g/l incubation with 10 Uav/l and 20 Ucellob/l. At 100 g/l cosette concentration, substrate inhibition was observed.     

Molecular Characterization of Subtype H11N9 Avian Influenza Virus Isolated from Shorebirds in Brazil

Migratory aquatic birds play an important role in the maintenance and spread of avian influenza viruses (AIV). Many species of aquatic migratory birds tend to use similar migration routes, also known as flyways, which serve as important circuits for the dissemination of AIV. In recent years there has been extensive surveillance of the virus in aquatic birds in the Northern Hemisphere; however in contrast only a few studies have been attempted to detect AIV in wild birds in South America. There are major flyways connecting South America to Central and North America, whereas avian migration routes between South America and the remaining continents are uncommon. As a result, it has been hypothesized that South American AIV strains would be most closely related to the strains from North America than to those from other regions in the world. We characterized the full genome of three AIV subtype H11N9 isolates obtained from ruddy turnstones (Arenaria interpres) on the Amazon coast of Brazil. For all gene segments, all three strains consistently clustered together within evolutionary lineages of AIV that had been previously described from aquatic birds in North America. In particular, the H11N9 isolates were remarkably closely related to AIV strains from shorebirds sampled at the Delaware Bay region, on the Northeastern coast of the USA, more than 5000 km away from where the isolates were retrieved. Additionally, there was also evidence of genetic similarity to AIV strains from ducks and teals from interior USA and Canada. These findings corroborate that migratory flyways of aquatic birds play an important role in determining the genetic structure of AIV in the Western hemisphere, with a strong epidemiological connectivity between North and South America.     

Behavior of sperm nuclei in intact and bisected metaphase II mouse oocytes fertilized in the presence of colcemid

Our objective was to examine the developmental fate of sperm nuclei in oocytes fertilized under conditions of meiotic arrest. Therefore zona-free metaphase II oocytes and oocyte fragments (nucleate and anucleate) were fertilized in the presence of colcemid. In anucleate oocyte fragments, normal male pronuclei develop. In contrast, in intact oocytes and nucleate fragments sperm nuclei after initial decondensation undergo secondary condensation. This state is maintained as long as the oocytes are treated with colcemid. When the drug is removed 3 h after insemination, the meiotic spindle(s) is reconstructed, the second polar body(ies) is extruded, and a female pronucleus (or micronuclei) forms. At the same time the sperm nucleus decondenses again and transforms into a male pronucleus. In addition oocytes fertilized in the presence of colcemid could not be refertilized. These observations suggest that oocytes and oocyte fragments fertilized in the presence of colcemid undergo activation despite the failure of pronucleus formation. The inhibitory effect of colcemid on the formation of pronuclei is expressed only in the presence of oocyte chromosomes. We suggest that colcemid stabilizes factors responsible for chromosome condensation that are associated with oocyte chromosomes but not factors (whether the same or different) present in the cytoplasm.     

Interaction of chiral MS-245 analogs at h5-HT6 receptors

Optically active pyrrolidinylmethylindole analogs related in structure to the benzenesulfonyltryptamine 5-HT(6) receptor antagonist MS-245 were evaluated and their R-isomers were found to bind with affinity higher than their S-enantiomers.