Community Attitudes and Practices of Urban Residents Regarding Predation by Pet Cats on Wildlife: An International Comparison

International differences in practices and attitudes regarding pet cats'' interactions with wildlife were assessed by surveying citizens from at least two cities in Australia, New Zealand, the UK, the USA, China and Japan. Predictions tested were: (i) cat owners would agree less than non-cat owners that cats might threaten wildlife, (ii) cat owners value wildlife less than non-cat owners, (iii) cat owners are less accepting of cat legislation/restrictions than non-owners, and (iv) respondents from regions with high endemic biodiversity (Australia, New Zealand, China and the USA state of Hawaii) would be most concerned about pet cats threatening wildlife. Everywhere non-owners were more likely than owners to agree that pet cats killing wildlife were a problem in cities, towns and rural areas. Agreement amongst non-owners was highest in Australia (95%) and New Zealand (78%) and lowest in the UK (38%). Irrespective of ownership, over 85% of respondents from all countries except China (65%) valued wildlife in cities, towns and rural areas. Non-owners advocated cat legislation more strongly than owners except in Japan. Australian non-owners were the most supportive (88%), followed by Chinese non-owners (80%) and Japanese owners (79.5%). The UK was least supportive (non-owners 43%, owners 25%). Many Australian (62%), New Zealand (51%) and Chinese owners (42%) agreed that pet cats killing wildlife in cities, towns and rural areas was a problem, while Hawaiian owners were similar to the mainland USA (20%). Thus high endemic biodiversity might contribute to attitudes in some, but not all, countries. Husbandry practices varied internationally, with predation highest where fewer cats were confined. Although the risk of wildlife population declines caused by pet cats justifies precautionary action, campaigns based on wildlife protection are unlikely to succeed outside Australia or New Zealand. Restrictions on roaming protect wildlife and benefit cat welfare, so welfare is a better rationale.     

Differences between temperate and tropical birds in seasonal acclimatization of thermoregulatory traits

Phenotypic flexibility can be an important determinant of fitness in variable environments. The climatic variability hypothesis (CVH) predicts that phenotypic flexibility in thermoregulatory traits will be greater in temperate species than tropical species as a means of coping with increased temperature seasonality at higher latitudes. However, support for the CVH has been mixed, and recent studies suggest that tropical birds are capable of substantial phenotypic flexibility. To test the generality of the CVH, we used flow‐through respirometry to quantify seasonal acclimatization in thermoregulatory traits in suites of temperate (n = 6) and tropical (n = 41) birds. We used W/S ratios (winter/summer trait values) to quantify the direction and magnitude of seasonal change (W/S ratio of 1 means no seasonal change). Temperate species exhibited coordinated changes in thermoregulatory traits in winter, including large increases in thermoneutral zone (TNZ) breadth and reductions in heat loss below the lower limit of the TNZ. Conversely, tropical species exhibited idiosyncratic seasonal thermoregulatory responses, and mean W/S ratios were close to 1 for all traits, indicative of little seasonal change and consistent with predictions of the CVH. Nevertheless, mean W/S ratios did not differ significantly between temperate and tropical species for either M_b or BMR, demonstrating that tropical birds can also exhibit substantial thermoregulatory flexibility. Our results highlight the need for complementary acclimation experiments to determine if latitudinal differences in seasonal acclimatization are due to inherent differences in capacity for flexibility.     

The inhibition of the carbon concentrating mechanism of the green alga Chlorella saccharophila by acetazolamide

The effects of the carbonic anhydrase (CA) inhibitors acetazolamide (AZ) and dextran-bound sulfonamide (DBS) on HCO₃⁻-dependent O₂ evolution in Chlorella saccharophila were evaluated. Addition of 4 μ M AZ or 0.4 mg ml⁻¹ DBS to photosynthesizing cells reduced the O₂ evolution rate at low dissolved inorganic carbon (DIC) concentration, decreased the size of the intracellular acid-labile carbon pool, and decreased the apparent affinity of the cells for DIC. Measurement of the whole-cell affinity of cells for CO₂ and HCO₃⁻ in the presence and absence of inhibitors indicated that active HCO₃⁻ transport was inhibited by AZ and DBS. The inhibition of HCO₃⁻ transport was independent of the inhibition of external and internal CA. These results suggest that the active uptake of HCO₃⁻ occurs initially by the interaction of HCO₃⁻ and a CA-like transporter.     

Coevolving protein residues: maximum likelihood identification and relationship to structure

The identification of protein sites undergoing correlated evolution (coevolution) is of great interest due to the possibility that these pairs will tend to be adjacent in the three-dimensional structure. Identification of such pairs should provide useful information for understanding the evolutionary process, predicting the effects of site-directed substitution, and potentially for predicting protein structure. Here, we develop and apply a maximum likelihood method with the aim of improving detection of coevolution. Unlike previous methods which have had limited success, this method allows for correlations induced by phylogenetic relationships and for variation in rate of evolution along branches, and does not rely on accurate reconstruction of ancestral nodes. In order to reduce the complexity of coevolutionary relationships and identify the primary component of pairwise coevolution between two sites, we reduce the data to a two-state system at each site, regardless of the actual number of residues observed at that site. Simulations show that this strategy is good at identifying simple correlations and at recognizing cases in which the data are insufficient to distinguish between coevolution and spurious correlations. The new method was tested by using size and charge characteristics to group the residues at each site, and then evaluating coevolution in myoglobin sequences. Grouping based on physicochemical characteristics allows categorization of coevolving sites into positive and negative coevolution, depending on the correlation between equilibrium state frequencies. We detected a striking excess of negative coevolution (corresponding to charge) at sites brought into proximity by the periodicity of the alpha-helix, and there was also a tendency for sites with significant likelihood ratios to be close in the three-dimensional structure. Sites on the surface of the protein appear to coevolve both when they are close in the structure, and when they are distant, implying a role for folding and/or avoidance of quaternary structure in the coevolution process.     

Low-flow vascular remodeling in the metabolic syndrome X

Peripheral microvascular dysfunction is a common affliction in patients with the metabolic syndrome X. Previous studies have described a number of vascular impairments in vasomotor control in both human patients and animal models of syndrome X, but the net effect of these impairments on microvascular structure has not been examined. The goal of the current study was to test the hypothesis that syndrome X reduces muscle perfusion and induces vascular remodeling. The obese Zucker rat was used as a model of syndrome X, and the microcirculation of the hindlimb and brain were examined. Obese Zucker rats were obese, hyperlipidemic, hyperinsulinemic, and hyperglycemic. Blood flow to the hindlimb was reduced by 59% in obese rats relative to lean rats. Skeletal muscle resistance arteries of the hindlimb microcirculation of obese rats had thinner walls, smaller lumens, and reduced distensibility. Hindlimb microvessels from obese rats also demonstrated reduced expression of vascular smooth muscle cell markers. Each of these traits is consistent with low-flow remodeling. In contrast, the cerebral microcirculation, where flow is vigorously autoregulated, showed no vascular remodeling nor were there changes in microvascular smooth muscle marker expression. Neither physical activity nor muscle mass were significantly different between lean and obese rats. Taken together, these findings suggest that syndrome X, by reducing hindlimb blood flow, induces a marked remodeling of microcirculation to favor smaller, less distensible vessels. This remodeling may result in an architectural limitation of maximum perfusion capacity and may be an important maladaption in the progression of peripheral microvascular disease.     

Analysis of among-site variation in substitution patterns

Substitution patterns among nucleotides are often assumed to be constant in phylogenetic analyses. Although variation in the average rate of substitution among sites is commonly accounted for, variation in the relative rates of specific types of substitution is not. Here, we review details of methodologies used for detecting and analyzing differences in substitution processes among predefined groups of sites. We describe how such analyses can be performed using existing phylogenetic tools, and discuss how new phylogenetic analysis tools we have recently developed can be used to provide more detailed and sensitive analyses, including study of the evolution of mutation and substitution processes. As an example we consider the mitochondrial genome, for which two types of transition deaminations (C⇒T and A⇒G) are strongly affected by single-strandedness during replication, resulting in a strand asymmetric mutation process. Since time spent single-stranded varies along the mitochondrial genome, their differential mutational response results in very different substitution patterns in different regions of the genome. Published: September 2, 2004.     

The ambush hypothesis: hidden stop codons prevent off-frame gene reading

Coding sequences lack stop codons, but many stops appear off-frame. Off-frame stops (stops in -1 and +1 shifted reading frames, termed hidden stops) terminate frame-shifted translation, potentially decreasing energy, and resource waste on nonfunctional proteins. Benefits may include reduced waste elimination costs and avoidance of potentially cytotoxic frame-shifted products. Our "ambush" hypothesis suggests that hidden stops are sometimes selected for. Codons of many amino acids can contribute to hidden stops, depending on the synonymous position state and adjacent codons. In vertebrate mitochondria, 31.75% of all amino acid combinations can form hidden stops. Codons with more potential to form hidden stops have greater usage frequency and bias in their favor among synonymous codons. Among primates, predicted mitochondrial rRNA secondary structure stability correlates negatively with the number of hidden stops in the mitochondrial genome. The taxonomic distribution of genetic codes suggests that +1 frameshifts might be more frequent than -1 frameshifts. This is confirmed by analyses of primate mitochondrial genomes: species with unstable rRNAs have more +1 stops, but the correlation is weak for -1 stops. High hidden stop density seems to be an adaptation in species with slippage prone ribosomes (unstable rRNAs). Hidden stops may thus compensate for reduced efficiency of some parts of the biosynthetic machinery. Some experimental data confirm our hypothesis: gene expression increases with the experimentally manipulated number of stops in the promoter region of a gene, suggesting biotechnological applications.