Defective Translation in RC<Superscript>−</Superscript> Cells

Mutation in the RC gene results in the formation of a species of β galactosidase with reduced specific activity and increased thermolability.     

In Vivo and In Vitro Localization of Leishmania within Macrophage Phagolysosomes: Use of Colloidal Gold as a Lysosomal Label1

The interaction of Leishmania with lysosomes within macrophages in vivo has been investigated. Lysosomes labeled with colloidal gold in vivo fused with phagocytic vacuoles containing Leishmania amastigotes within the macrophages of infected footpad tissue of BALB/c mice. This localization of Leishmania within macrophage phagolysosomes in vivo is the first confirmation for any obligate intracellulaire protozoon that parasite-lysosome interactions in vitro occur in vivo.     

Stereotypic boring behaviour inferred from the earliest known octopod feeding traces: Early Eocene,southern England

Todd, JA. & Harper, EM. 2011: Stereotypic boring behaviour inferred from the earliest known octopod feeding traces: Early Eocene, southern England. Lethaia, Vol. 44, pp. 214–222. A bulk sample of 267 disarticulated valves of the bivalve Venericor clarendonensis (Wood) collected from the Lower Eocene London Clay (southern UK) yielded 38 individuals that had been perforated by small drill holes (0.70–2.14 mm in outer diameter). These drill holes had more or less circular plan views, with slightly irregular openings, and taper as they pass through the valve, conforming to the ichnotaxon Oichnus simplex Bromley. They show stereotypic positioning, being concentrated in the posterior region on the prey, moreover there is remarkable preference for perforating the sites of muscle attachment (principally the posterior adductor). We consider the most likely culprits to be octopods. As such these are the oldest octopod drill holes yet recorded. They provide the only evidence of these important top predators in this shallow marine community and also demonstrate that the sophisticated predatory behaviour shown by modern octopods had been evolved by at least the Early Eocene. □Eocene, octopod behaviour, Oichnus, stereotypic boring.     

High gene flow and metapopulation dynamics detected for three species in a dryland river system

1. The highly variable hydrology of dryland rivers has important implications for population dynamics in these systems. In western Queensland, fluctuations in sub‐population size are likely to lead to local bottlenecks and extinctions, increasing the need for connectivity and gene flow to maintain population viability. 2. Using microsatellite markers, we explored evidence for this metapopulation structure in two species of freshwater fish (Maquaria ambigua and Tandanus tandanus) and one crustacean (Macrobrachium australiense) in a sub‐catchment of the upper Murray–Darling Basin, Australia. 3. Overall, we found very weak genetic structure for all three species. Two species (M. ambigua and M. australiense) showed some significant genetic structure that did not correlate with geographic distance. However, decomposed pairwise regression analysis revealed evidence for intense genetic drift at the waterhole scale, suggesting that local bottlenecks are driving what little genetic structure does exist for these species. 4. The results identify the local impact of bottlenecks on genetic diversity, but highlight the importance of gene flow in maintaining population viability in these highly variable systems. As the impacts of bottlenecks are likely to be tempered by gene flow, it is suggested that the maintenance of connectivity is of paramount importance in this dryland system.     

Effaced preservation in the Ediacara biota and its implications for the early macrofossil record

Abstract: Ediacaran structures known as ‘pizza discs’ or Ivesheadia have long been considered enigmatic. They are amongst the oldest known members of the Ediacara biota, apparently restricted to the Avalonian successions of Newfoundland and the UK, c. 579–560 Ma. Here, we suggest that these impressions are taphomorphs, resulting from the post‐mortem decay of the frondose Ediacaran biota. Ediacaran fossils range from well‐preserved, high‐fidelity variants to almost completely effaced specimens. The effaced specimens are inferred to have undergone modification of their original morphology by post‐mortem microbial decay on the sea floor, combined with sediment trapping and binding. In this style of preservation, morphological details within the organism became variously subdued as a function of the extent of organic decay prior to casting by overlying sediments. Decay and effacement were progressive in nature, producing a continuum of grades of preservation on Ediacaran bedding planes. Fossils preserved by such ‘effaced preservation’ are those that have suffered these processes to the extent that only their gross form can be determined. We suggest that the lack of detailed morphology in effaced specimens renders such fossils unsuitable for use as type material, as it is possible that several taxa may, upon degradation and burial, generate similar morphological taphomorphs. We here reinterpret the genus Ivesheadia as a taphomorph resulting from extensive post‐mortem decay of frondose organisms. Blackbrookia, Pseudovendia and Shepshedia from beds of comparable age in England are likewise regarded as taphomorphs broadly related to Charnia or Charniodiscus spp. To reflect the suggestion that such impressions are likely to be taphomorphs, and not taxonomically discrete, we propose the term ivesheadiomorphs to incorporate all such effaced taphonomic expressions of Ediacaran macrofossil taxa in Avalonian assemblages. Our recognition of effaced preservation has significant implications for Ediacaran taxonomy, and consequently for measures of Ediacaran diversity and disparity. It is implied that Avalonian assemblages preserve both organisms that were alive and organisms that were already dead at the time of burial. As such, the fossil assemblages cannot be taken to represent census populations of living organisms, as in prior interpretations.     

Buying and Believing: Sri Lankan Advertising and Consumers in a Transnational World

Buying and Believing: Sri Lankan Advertising and Consumers in. Transnational World. Steven Kemper. Chicago: University of Chicago Press, 2001. 263 pp.     

A historical perspective of the genus Mytilus (Bivalvia: Mollusca) in New Zealand: multivariate morphometric analyses of fossil, midden and contemporary blue mussels

The taxonomic status of smooth shelled blue mussels of the genus Mytilus has received considerable attention in the last 25 years. Despite this, the situation in the southern hemisphere remains uncertain and is in need of clarification. Recent work suggests that contemporary New Zealand mussels from two cool/cold temperate locations are M. galloprovincialis. However, the distribution of Mytilus in New Zealand ranges from 35 ° to 52 ° south (～ 1800 km), meaning that large areas of the subtropical/warm temperate north and the subantarctic south remain unsampled, an important consideration when species of this genus exhibit pronounced macrogeographical differences in their distributions which are associated with environmental variables such as water temperature, salinity, wave action and ice cover. This study employed multivariate morphometric analyses of one fossil, 83 valves from middens, and 92 contemporary valves from sites spanning the distributional range of blue mussels to determine a historical and contemporary perspective of the taxonomic status of Mytilus in New Zealand. The findings indicated that all fossil and midden mussels are best regarded as M. galloprovincialis and confirmed that contemporary mussels, with one possible regional exception, are also best regarded as M. galloprovincialis. Contemporary mussels from the Bay of Islands (warm temperate/subtropical) exhibited much greater affinity to M. edulis than they did to M. galloprovincialis, indicating that mussels from this area require detailed genetic examination to determine their taxonomic status. The analyses revealed a significant difference between the fossil/midden mussels and the contemporary mussels, consistent with levels of present day differentiation among intraspecific populations and not thought to reflect any substantive temporal change between mussels of the two groups. The continuous distribution of M. galloprovincialis in New Zealand from the warm north to the subantarctic south indicates that the physiology of this species is adapted to a wide range of water temperature conditions. Therefore, the distribution of this species on a worldwide scale is unlikely to be restricted by its adaptation to warm water alone, as has previously been widely assumed. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 82 , 329–344.     

Habitat-Suitability Models for Cavity-Nesting Birds in a Postfire Landscape

ABSTRACT Models of habitat suitability in postfire landscapes are needed by land managers to make timely decisions regarding postfire timber harvest and other management activities. Many species of cavity-nesting birds are dependent on postfire landscapes for breeding and other aspects of their life history and are responsive to postfire management activities (e.g., timber harvest). In addition, several cavity nesters are designated as species at risk. We compare the ability of 2 types of models to distinguish between nest and non-nest locations of 6 cavity-nesting bird species (Lewis's woodpecker [Melanerpes lewis], black-backed woodpecker [Picoides arcticus], hairy woodpecker [P. villosus], northern flicker [Colaptes auratus], western bluebird [Sialia mexicana], and mountain bluebird [S. currucoides]) in the early postfire years for a ponderosa pine (Pinus ponderosa) forest in Idaho, USA. The 2 model sets consisted of 1) models based on readily available remotely sensed data and 2) models containing field-collected data in addition to remotely sensed data (combination models). We evaluated models of nesting habitat by quantifying the model's ability to correctly identify nest and non-nest locations and by determining the percentage of correctly identified nest locations. Additionally, we developed relative habitat-suitability maps for nesting habitat of black-backed and Lewis's woodpeckers from the best models. For all species except Lewis's woodpeckers, model performance improved with the addition of field-collected data. Models containing remotely sensed data adequately distinguished between nest and non-nest locations for black-backed woodpecker and Lewis's woodpecker only, whereas models containing both field-collected and remotely sensed data were adequate for all 6 species. Improvements in the availability of more accurate remote sensing technology would likely lead to improvements in the ability of the models to predict nesting locations. External validation with data from other wildfires is necessary to confirm the general applicability of our habitat-suitability models to other forests. Land managers responsible for maintaining habitat for cavity-nesting birds in postfire landscapes can use these models to identify potential nesting areas for these species and select areas in burned forests where postfire salvage logging is most likely to have minimal impacts on cavity-nesting bird habitats.