We have systematically made a set of precisely defined, single-gene deletions of all nonessential genes in Escherichia coli K-12. Open-reading frame coding regions were replaced with a kanamycin cassette flanked by FLP recognition target sites by using a one-step method for inactivation of chromosomal genes and primers designed to create in-frame deletions upon excision of the resistance cassette. Of 4288 genes targeted, mutants were obtained for 3985. To alleviate problems encountered in high-throughput studies, two independent mutants were saved for every deleted gene. These mutants-the 'Keio collection'-provide a new resource not only for systematic analyses of unknown gene functions and gene regulatory networks but also for genome-wide testing of mutational effects in a common strain background, E. coli K-12 BW25113. We were unable to disrupt 303 genes, including 37 of unknown function, which are candidates for essential genes. Distribution is being handled via GenoBase (http://ecoli.aist-nara.ac.jp/).

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Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection.

▪ Abstract Local habitat and biological diversity of streams and rivers are strongly influenced by landform and land use within the surrounding valley at multiple scales. However, empirical associations between land use and stream response only varyingly succeed in implicating pathways of influence. This is the case for a number of reasons, including (a) covariation of anthropogenic and natural gradients in the landscape; (b) the existence of multiple, scale-dependent mechanisms; (c) nonlinear responses; and (d) the difficulties of separating present-day from historical influences. Further research is needed that examines responses to land use under different management strategies and that employs response variables that have greater diagnostic value than many of the aggregated measures in current use. In every respect, the valley rules the stream.      H.B.N. Hynes (1975)

http://deq.idaho.gov/media/525804-Landscapes_Riverscapes_Influence_landuse_stream_ecosystems_Allan_2004.pdf

Landscapes and Riverscapes: The Influence of Land Use on Stream Ecosystems

Biofilms are complex communities of microorganisms attached to surfaces or associated with interfaces. Despite the focus of modern microbiology research on pure culture, planktonic (free-swimming) bacteria, it is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces. Furthermore, these microbial communities are often composed of multiple species that interact with each other and their environment. The determination of biofilm architecture, particularly the spatial arrangement of microcolonies (clusters of cells) relative to one another, has profound implications for the function of these complex communities. Numerous new experimental approaches and methodologies have been developed in order to explore metabolic interactions, phylogenetic groupings, and competition among members of the biofilm. To complement this broad view of biofilm ecology, individual organisms have been studied using molecular genetics in order to identify the genes required for biofilm development and to dissect the regulatory pathways that control the plankton-to-biofilm transition. These molecular genetic studies have led to the emergence of the concept of biofilm formation as a novel system for the study of bacterial development. The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced our understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis of biofilm development.

Microbial Biofilms: from Ecology to Molecular Genetics

Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment.

The extra-oral digestion of creeping water bugs (Naucoridae: Hemiptera) hinders the study of their diet using the standard method of identifying prey body parts in the gut. Genetic methods are available, but rely on PCR tests or similar diagnostics to confirm suspected prey. Where the potential prey is unknown and a broad search for all possible prey is desirable, methods that can potentially capture any prey item are required. Naucoris sp. is known to harbor Mycobacterium ulcerans (Actinomycetales: Mycobacteriaceae), the causative bacterium of Buruli ulcer. Outbreaks of Buruli ulcer have been associated with disturbed freshwater habitats, but the mode of transmission to humans remains unclear. Here we examine the diet of Naucoris sp., a dominant aquatic predator in water bodies in Ghana where the prevalence of Buruli ulcer is high. We cloned and sequenced 576 PCR products (mtDNA rrnL, cox1) isolated from the gut of 60 Naucoris sp. individuals to determining diet composition as broadly as possible. Using phylogenetic analysis of newly sequenced clones and 6 potential prey taxa collected from the site, sequences isolated from Naucoris sp. guts matched locally collected Coleoptera (Hydrophilidae). Blastn queries to GenBank of other clone sequences produced matches to (Anura) (n = 1), Rotifera (n = 5), and fungi (n = 4) as additional components of the diet. Our results suggest that sp. in this Buruli ulcer-endemic area feeds on a wide range of prey and body sizes, and that the approach could be successfully applied to studies of aquatic food webs where morphological identification of prey is impossible and where little or no a priori knowledge is available.

https://bioone.org/journals/journal-of-insect-science/volume-12/issue-2/031.012.0201/A-Molecular-Approach-to-Identifying-the-Natural-Prey-of-the/10.1673/031.012.0201.pdf

A Molecular Approach to Identifying the Natural Prey of the African Creeping Water Bug Naucoris, A Potential Reservoir of Mycobacterium ulcerans

Experiments were conducted in experimental channels to study feeding variability through time and between conspecific individuals of four species of lotic predators. Large and small Rhyacophila dor...

Feeding variability among individual aquatic predators in experimental channels

A CO2-Alsynite® attractant trap for collecting large numbers of wild adult stable flies, Stomoxys calcitrans , for subsequent mark-release studies is described. The largest numbers of adult flies were collected when traps were placed 10 cm above ground level. Six traps, placed at a local dairy in Michigan, USA, consistently caught 8000 to 10,000 adult stable flies per week throughout the summer.

An Efficient Trap for Collecting Wild Adult Stable Flies, Stomoxys Calcitrans (Diptera: Muscidae), for Mark-Release Studies

Directly beneath the lateral palatal brushes of larvae of Aedes triseriatus (Say) and Anopheles quadrimaculatus Say the epidermis is invaginated. Some of the epidermal cells secrete the brush of the next instar. Other cells are glandular and secrete a mucosubstance, which fills the space between the epidermis and labral cuticle. The mucosubstance is also found externally on the palatal brushes, although no connection to the glands has been discovered. The glands and mucosubstance may be homologous with those of larval Simuliidae. The mucosubstance probably captures particulate food during suspension feeding. Phylogenetic aspects of the glands are considered briefly.

Larval Mosquito (Diptera: Culicidae) Feeding Mechanisms: Mucosubstance Production for Capture of Fine Particles

The adult emergence patterns and species distribution and abundance of Tipulidae in three woodland floodplains diffenng in size and in the diversity of vegetation were studied in southwestern Michigan during 1977. Adults and larvae were sampled by using emergence traps and core samples of leaf litter and humus, respectively. Twentyfour species of Tipulidae belonging to 15 genera were recorded from emergence trap samples. Adult emergence patterns among species groups were characterized and there were differences in species composition among floodplains. Abundance and distribution of larval tipulids were influenced by two closely related environmental factors: soil moisture and organic content. Adult distribution appeared to be influenced by factors affecting evaporation rate, that is, relative humidity, air movement, and insolation.

Richard W. Merritt

Papers

A Molecular Approach to Identifying the Natural Prey of the African Creeping Water Bug Naucoris, A Potential Reservoir of Mycobacterium ulcerans

Feeding variability among individual aquatic predators in experimental channels

An Efficient Trap for Collecting Wild Adult Stable Flies, Stomoxys Calcitrans (Diptera: Muscidae), for Mark-Release Studies

Larval Mosquito (Diptera: Culicidae) Feeding Mechanisms: Mucosubstance Production for Capture of Fine Particles

Adult Emergence Patterns and Species Distribution and Abundance of Tipulidae in Three Woodland Floodplains