Resource Quantity Affects Benthic Microbial Community Structure and Growth Efficiency in a Temperate Intertidal Mudflat

Estuaries cover <1% of marine habitats, but the carbon dioxide (CO2) effluxes from these net heterotrophic systems contribute significantly to the global carbon cycle. Anthropogenic eutrophication of estuarine waterways increases the supply of labile substrates to the underlying sediments. How such changes affect the form and functioning of the resident microbial communities remains unclear. We employed a carbon-13 pulse-chase experiment to investigate how a temperate estuarine benthic microbial community at 6.5°C responded to additions of marine diatom-derived organic carbon equivalent to 4.16, 41.60 and 416.00 mmol C m−2. The quantities of carbon mineralized and incorporated into bacterial biomass both increased significantly, albeit differentially, with resource supply. This resulted in bacterial growth efficiency increasing from 0.40±0.02 to 0.55±0.04 as substrates became more available. The proportions of diatom-derived carbon incorporated into individual microbial membrane fatty acids also varied with resource supply. Future increases in labile organic substrate supply have the potential to increase both the proportion of organic carbon being retained within the benthic compartment of estuaries and also the absolute quantity of CO2 outgassing from these environments

Evidence that Adaptation in Drosophila Is Not Limited by Mutation at Single Sites

Adaptation in eukaryotes is generally assumed to be mutation-limited because of small effective population sizes. This view is difficult to reconcile, however, with the observation that adaptation to anthropogenic changes, such as the introduction of pesticides, can occur very rapidly. Here we investigate adaptation at a key insecticide resistance locus (Ace) in Drosophila melanogaster and show that multiple simple and complex resistance alleles evolved quickly and repeatedly within individual populations. Our results imply that the current effective population size of modern D. melanogaster populations is likely to be substantially larger (≥100-fold) than commonly believed. This discrepancy arises because estimates of the effective population size are generally derived from levels of standing variation and thus reveal long-term population dynamics dominated by sharp—even if infrequent—bottlenecks. The short-term effective population sizes relevant for strong adaptation, on the other hand, might be much closer to census population sizes. Adaptation in Drosophila may therefore not be limited by waiting for mutations at single sites, and complex adaptive alleles can be generated quickly without fixation of intermediate states. Adaptive events should also commonly involve the simultaneous rise in frequency of independently generated adaptive mutations. These so-called soft sweeps have very distinct effects on the linked neutral polymorphisms compared to the standard hard sweeps in mutation-limited scenarios. Methods for the mapping of adaptive mutations or association mapping of evolutionarily relevant mutations may thus need to be reconsidered

Bladder dysfunction after repeat laparoscopic uterine nerve ablation (LUNA)

The authors report a case of voiding dysfunction with reduced sensation and areflexia 13 months after a repeat LUNA due to pelvic nerve injury. Anatomic distortion and increased vascularity were likely contributing factors. Repeat procedures may expose patients to a risk of such injury due to anatomic distortion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45904/1/192_2005_Article_BF01961846.pd

Governing social practice: technology and institutional change

In this article, we extend the concept of technology beyond the conventional understanding of systems and artifacts as embodiments of particular functionalities that are variously enacted in local settings. Technological artifacts or systems epitomize operational couplings that extend beyond the human-technology interface. Such couplings entail multiple, unobtrusive, back-staged links that evade human interpretation yet are critically involved in the reproduction and control of social relations. Cast in this light, technologies emerge as complex rationalized embodiments for structuring social relationships and, in this quality, complement and occasionally compete with institutional modes of governance. We explore these ideas in the empirical context of cultural memory organizations (e. g., libraries, archives, museums). As the outcome of the technological developments that have marked the field over the last two decades, the operations of memory institutions increasingly mingle with those of information aggregators and search engines. These developments reframe longstanding professional practices of memory organizations and, in this process, challenge their institutional mandate