Exotic mitotic mechanisms

The emergence of eukaryotes around two billion years ago provided new challenges for the chromosome segregation machineries: the physical separation of multiple large and linear chromosomes from the microtubule-organizing centres by the nuclear envelope. In this review, we set out the diverse solutions that eukaryotic cells use to solve this problem, and show how stepping away from ‘mainstream’ mitosis can teach us much about the mechanisms and mechanics that can drive chromosome segregation. We discuss the evidence for a close functional and physical relationship between membranes, nuclear pores and kinetochores in generating the forces necessary for chromosome segregation during mitosis.     

Planning for reserve adequacy in dynamic landscapes; maximizing future representation of vegetation communities under flood disturbance in the Pantanal wetland

Aim Using a probabilistic modelling framework, we aimed to incorporate landscape spatiotemporal dynamics into reserve design. We employed a spatially explicit stochastic model, which integrates both hydrological and biological processes, to simulate the wetland’s biological succession. Location Pantanal wetland (with 140,000 km²) between Brazil, Bolivia and Paraguay. Methods We used the reserve design software Marxan to optimize the current and future representation (up to 50 years) of 20% of five plant communities with maximum reliability (i.e. smallest uncertainty). The Kappa statistic was used to compare selection frequencies of individual sites through a set of planning timeframes (5, 17, 25 and 50 years) and the likely pattern of biological succession over these periods. Results Solutions based on static vegetation distributions were significantly dissimilar from solutions based on the expected modelled changes resulting from the flood disturbance and succession dynamics. Increasing the required reliability of biodiversity outcomes resulted in more expensive reserve solutions. We demonstrated the flexibility of probabilistic decision‐making methods to illuminate the trade‐offs between reliability and efficiency of site selection. Main conclusions Considering the importance of habitat heterogeneity to the principles and practice of systematic conservation planning, it is notable that landscape dynamics have not been a central theme in conservation planning. In the case of the Pantanal hydrosere, acknowledging and planning for temporal dynamics required an ability to model succession and define acceptable levels of outcome reliability, but ultimately improved the long‐term Adequacy of resulting reserve networks.     

Transfer and expression of mutations in pleiotropic genes determining the synthesis of extracellular enzymes in Bacillus subtilis

The mutations in the genes determining the levels of extracellular enzymes production were transferred into Bacillus subtilis 168 strain by genetic transformation technique. The method used has permitted registering the transfer of pleiotropic genes. Seven amylase producers were detected among 126 his+ transformants screened, as well as five metalprotease producers among 246 gly+ transformants. Cotransfer of pap and hpr mutant genes linked with his+ or gly+ genes might result in finding the producers among the mentioned prototrophic transformants. Selection of linked markers in transformation, presented in the paper, is discussed to be a useful technique for obtaining producer strains for industrial production.     

Stay by thy neighbor? Social organization determines the efficiency of biodiversity markets with spatial incentives

Market-based conservation instruments, such as payments, auctions or tradable permits, are environmental policies that create financial incentives for landowners to engage in voluntary conservation on their land. But what if ecological processes operate across property boundaries and land use decisions on one property influence ecosystem functions on neighboring sites? This paper examines how to account for such spatial externalities when designing market-based conservation instruments. We use an agent-based model to analyze different spatial metrics and their implications on land use decisions in a dynamic cost environment. The model contains a number of alternative submodels which differ in incentive design and social interactions of agents, the latter including coordinating as well as cooperating behavior of agents. We find that incentive design and social interactions have a strong influence on the spatial allocation and the costs of the conservation market.     

A LINE element is present at the site of a 300-kb deletion starting in intron 10 of the PAX6 gene in a case of familial aniridia

We have identified a 300-kb germline deletion in 11p13 in a family with aniridia but no Wilms’ tumor. Cloning and sequencing of the breakpoint revealed that the deletion starts in intron 10 of the PAX6 gene and removes the C-terminal part of the proline-serine-threonine rich domain, leaving both DNA-binding domains intact. The PAX6 gene is joined head-to-head to a LINE-1 (L1) element. The L1 is truncated at the 3′ end, removing part of ORF2. Sequencing of the L1 element shows that it does not encode a functional transposase and is therefore probably not an active element. These data suggest that the L1 element is normally present at the site of the distal deletion endpoint in 11p13. No extensive sequence homologies are detected at the deletion junction points; however, the PAX6 gene as well as the L1 element have runs of T nucleotides at this position, indicating that the deletion occurred by nonhomologous recombination. Several consensus recognition sequences for topoisomerase I flank the deletion site in both sequences, suggesting an involvement of this enzyme during the deletion-recombination process. Received: 22 November 1995 / Revised: 25 March 1996     

A NEMATODE-DESTROYING HYPHOMYCETE FORMING PARALLEL MULTISEPTATE HYALINE CONIDIA IN CIRCULAR ARRANGEMENT

In several Petri plate cultures that had been inoculated with decaying plant detritus from central Maryland, a fungus developed which attacks nematodes by extending a rather wide infection-tube either from an adhesive hyphal protuberance, or, more often, from a subglobose adhesive cell produced terminally on its elongate-ellipsoid pluriseptate hyaline conidia. A number (sometimes three) of these conidia are borne simultaneously in peripheral positions on the broadly rounded tip of the colorless condiophore, and are directed upward, parallel to the conidiophore axis. From the segment immediately below its adhesive cell, each conidium puts forth laterally a flexible unicellular tubular appendage that grows downward approximately to the level of the spore attachment. The fungus is described as Haptocara latirostrum gen. n., sp. n. Although presumably belonging in the Moniliaceae, it shows no close kinship with the numerous interrelated clampless Hyphomycetes that have been made known as subsisting through capture of nematodes.