More for less: a study of environmental flows during drought in two Australian rivers

1. In rivers affected by drought, flow regulation can further reduce flow and intensify its effects. We measured ecological responses to environmental flows, during a prolonged drought in a regulated river (Cotter River), compared with a drought affected, unregulated river (Goodradigbee River) in south‐eastern Australia. 2. Environmental flows in the regulated Cotter River were reduced from a monthly average base flow of 15 MLd^?1 to only 5 MLd^?1, which was implemented as two test flow regimes. Initially, flows were delivered in cycles of 14 days at 3 MLd^?1 followed by 3 days at 14 MLd^?1 and then another 14 days at 3 MLd^?1 to make up the monthly average of 5 MLd^?1. This flow regime continued for 6 months, after which a preliminary ecological assessment indicated deterioration in river condition. Consequently, the flow regime was altered to a cycle of 2 MLd^?1 for 28 days followed by 20 MLd^?1 for either 3 or 4 days. This new flow regime continued for another 5 months. 3. The ecological outcomes of the test flow regimes were assessed in terms of (i) the provision of available habitat (wetted channel) for aquatic biota; (ii) the accumulation of periphyton; and (iii) the structure and richness of macroinvertebrate assemblages. 4. Flow of 20 MLd^?1 covered most of the streambed in the Cotter River, thus providing more wetted area and connectivity between habitats than flows of 2, 3 or 14 MLd^?1. Depth and velocity were always less in the Cotter River than in the unregulated Goodradigbee River. Periphyton decreased in the Cotter River during the 2/20 MLd^?1 flow regime, which combined the lowest and greatest test flow volumes, while periphyton did not change significantly in the unregulated river. 5. The reduced flow in the Cotter River resulted in fewer macroinvertebrates than expected (13) compared with unregulated Goodradigbee sites (19), although the magnitude of the differences did not depend on the test flow releases. Macroinvertebrates in the Cotter River became numerically dominated by Diptera and Oligochaeta, while Ephemeroptera, Plecoptera and Trichoptera decreased in abundance. 6. In the Cotter River, the monthly average flow of 5 MLd^?1 (exceeded 97% of the time pre‐regulation) was insufficient to maintain the macroinvertebrate assemblages in reference condition, regardless of release patterns. However, short‐term ecological objectives were achieved, such as reduced periphyton accumulation and increased habitat availability, and the environmental flows maintained the river’s ability to recover (resilience) when higher flows returned.     

Investigating the effects of predator removal and habitat management on nest success and breeding population size of a farmland passerine: a case study

Passerines are especially vulnerable to predation at the pre-independence stage. Although the role of nest success in British farmland passerine declines is contentious, improvement in nest success through sympathetic management could play a role in their reversal. Because habitat is known to interact with predation, management options for mitigation will need to consider effects of nest predation. We present results from an observational study of a population of Common Blackbird Turdus merula on a farm which has experienced a range of agri-environment and game-management options, including a period with nest predator control, as a case study to address some of these issues. We used an information theoretic model comparison procedure to look for evidence of interactions between habitat and nest predation, and then asked whether habitat management and nest predator abundances could explain population trends at the site through their effects on nest success. Interactions were detected between measures of predator abundance and habitat variables, and these varied with nest stage – habitat within the vicinity of the nest appeared to be important at the egg stage, and nest-placement characteristics were important at the nestling stage. Although predator control appeared to have a positive influence on Blackbird breeding population size, the non-experimental set-up meant we could not eliminate other potential explanations. Variation in breeding population size did not appear to be influenced by variation in nest success alone. Our study demonstrates that observational data can only go so far in detection of such effects, and we discuss how it might be taken further. Agri-environment and game-management techniques are likely to influence nest predation pressure on farmland passerines, but the patterns, mechanisms and importance to population processes remain not wholly understood.     

A novel liver specific isoform of the rat LAR transcript is expressed as a truncated isoform encoded from a 5'UTR located within intron 11

Background  

The leukocyte common antigen related receptor (LAR) protein has been shown to modulate the signal transduction of a number of different growth factors, including insulin and insulin-like growth factor 1. Splice variants exhibit differing roles and are expressed according to tissue type and developmental stage.     

Enterococcal surface protein Esp is not essential for cell adhesion and intestinal colonization of Enterococcus faecium in mice

Background  

Enterococcus faecium has globally emerged as a cause of hospital-acquired infections with high colonization rates in hospitalized patients. The enterococcal surface protein Esp, identified as a potential virulence factor, is specifically linked to nosocomial clonal lineages that are genetically distinct from indigenous E. faecium strains. To investigate whether Esp facilitates bacterial adherence and intestinal colonization of E. faecium, we used human colorectal adenocarcinoma cells (Caco-2 cells) and an experimental colonization model in mice.     

The effects of gibberellin A3 on white clover during floral development

Hokkanen & Pimentel (1984) proposed a novel approach for the selection of biocontrol agents. They advocated the selection of agents from a relative of the weed plant rather than from the target weed species itself. The new relationship that such agents would have with the weed would be characterised by a relative lack of homeostasis compared with the old herbivore-plant associations traditionally used in weed biocontrol, and would consequently be more effective. There are few examples to support these contentions because of the traditional use of old herbivore-plant associations in weed biocontrol. In the present study, herbivore-plant associations in agricultural situations, which are analogous to agent-weed associations, are examined to assess the potential of new associations for weed biocontrol. The herbivores on 14 introduced crop plants which have salient similarities to the major weeds in the south-western Cape were surveyed: (a) 68% of the 188 insect and mite herbivores are indigenous species in new associations with these host plants, and (b) of the five most damaging pests on each of 13 of the crop plants, 53% are in new associations with the plants. Of the 40 most important agricultural pests in South Africa, 58% are in new associations, confirming these results. About 50% of the insect and mite herbivores in new associations with their host plants are oligophagous, indicating that new associations are not necessarily characterised by polyphagy and hence unsafe for use in weed biocontrol. We conclude that new associations between herbivore species and host plants have strong potential in weed biocontrol because (a) their frequency in agriculture indicates that they can easily be established in weed biocontrol situations, (b) they are as damaging as old associations and (c) they are not necessarily unsafe as regards host specificity. We therefore advocate the use of both the classical approach and that of Hokkanen & Pimentel (1984). Our support for Hokkanen & Pimentel (1984) is, however, based on evidence and rationale clearly different to theirs, and we provide novel guidelines, which can be routinely and practically applied in the selection of agents for weed biocontrol.     

Estimating the rate of evolution of the rate of molecular evolution

A simple model for the evolution of the rate of molecular evolution is presented. With a Bayesian approach, this model can serve as the basis for estimating dates of important evolutionary events even in the absence of the assumption of constant rates among evolutionary lineages. The method can be used in conjunction with any of the widely used models for nucleotide substitution or amino acid replacement. It is illustrated by analyzing a data set of rbcL protein sequences.      

Site localization of sialyl Lewis(x) antigen on alpha1-acid glycoprotein by high performance liquid chromatography-electrospray mass spectrometry

A simple, fast and sensitive method was developed to verify the presence of the sialyl Lewis(x) antigen on an N-linked glycoprotein. High performance liquid chromatography-electrospray mass spectrometry (HPLC-ESI/MS) was used to identify which of the five N-linked glycosylation sites of human plasma alpha1-acid-glycoprotein (orosomucoid, OMD) contain the sialyl Lewis(x) antigen. OMD was digested with proteolytic enzymes and analyzed by reversed phase chromatography coupled with on-line ESI/MS. A tandem mass spectrometry experiment was designed to detect the presence of the sialyl Lewis(x) antigen based on the observation of an 803 mass to charge ratio ( m/z ) ion produced in the intermediate pressure region of the ESI interface. The ESI/MS signal at m/z 803 is consistent with an oxonium ion for a glycan structure containing NeuAc, Gal, GlcNAc, and Fuc. The identity of the m/z 803 ion was confirmed by ESI/MS/MS analysis of the m/z 803 fragment ion and comparison with a sialyl Lewis(x) standard. The stereochemistry and linkage positions were assigned using previous NMR analysis but could be determined with permethylation analysis if necessary. The analysis of OMD gave a pattern showing signal for the sialyl Lewis(x) antigen coeluting with each of the five N-linked glycopeptides. The ability to monitor sialyl Lewis(x) expression at each of the five sites is of interest in the study of OMD's role in inflammatory diseases.