Enhanced ambient UVB light affects growth,body condition and the investment in innate and adaptive immunity in three-spined sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>)

With ongoing environmental change, ultraviolet-B radiation (UVB) reaching the Earth’s surface has increased over recent decades with consequences for terrestrial and also aquatic ecosystems. Despite evidence for direct physiological and immunological responses of aquatic animals following enhanced UVB exposure, studies investigating indirect impacts of ambient UVB radiation are scarce and mainly used only single doses and/or artificially high amounts of UVB. In the present study, the influence of chronic exposure to elevated UVB levels on growth, body condition and immune function was investigated in three-spined sticklebacks (Gasterosteus aculeatus). Fish were kept outdoors for 68 ± 2 days under two different spectral conditions; one group was exposed to natural solar radiation (UVB-normal), while the other group received additional UVB light for four hours daily (UVB-enhanced). Enhanced UVB radiation was within the range of UVB levels measured at the study site. Fish length and weight were determined at the beginning and end of the experiment to compare growth and body condition between the two treatment groups. At the end of the experiment, the splenosomatic index and the granulocyte-to-lymphocyte ratio were determined as immune parameters. Fish from the UVB-enhanced group showed a reduced growth and body condition as well as a lower splenosomatic index compared to the UVB-normal group. Furthermore, UVB-treated fish had a higher granulocyte-to-lymphocyte ratio representing a relatively higher activation of innate compared to adaptive immunity. Consequently, increased but ecologically relevant levels of ambient UVB negatively affect growth and body condition and have a considerable impact on immunity in three-spined sticklebacks.     

钙离子对PSII颗粒放氧活性的影响

外加5 mmol/L Ca~(2 )可以使菠菜PSⅡ颗粒的放氧活性增高。PSⅡ颗粒经EGTA透析、低pH值、光照、2 mol/L NaCl等处理后,放氧活性下降,同时,这些颗粒的钙含量也相应降低。但当外加 5 mmol/L Ca~(2 )时,可使这些颗粒全部或部分地恢复放氧活性。PSⅡ颗粒中存在的钙对放氧起着重要作用;钙在PSⅡ颗粒中的结合位点不止一个,其结合状态有紧密和松散之别。     

Increased predation risk while mate guarding as a cost of reproduction for male broad-headed skinks (Eumeces laticeps)

We investigated antipredatory costs associated with mate guarding as potential costs of reproduction for male broad-headed skinks. Mate guarding by male lizards may increase fitness by preventing loss of fertilizations of the guarded female's eggs to other males, but it may have several costs. In addition to lost opportunities to search for additional females, risk of injury while fighting other males, and energetic expenditures while following females and fighting, guarding males might suffer increased risk of predation and reduction of opportunities to forage. We studied potential antipredatory costs of mate guarding by simulating predators searching for and approaching pairs of lizards in the field. Among pairs of lizards in close proximity to each other, males were detected before females 10 times more frequently than females were detected before males, and females fled before males much more frequently than males fled before females when pairs were approached, leaving the males exposed to the predator. After one or both lizards fled, males frequently followed females by scanning visually and scent trailing, exposing themselves to the predator while the female hid. Females never followed males. The implications of these findings for antipredatory costs of mate guarding are discussed. Electronic Publication     

Shoal choice and ultraviolet reflections in stickleback populations from different photic habitats

Grouping is a widespread phenomenon in the animal kingdom and the decision to join a group is a function of individual and environmental conditions, meaning that any advantages and disadvantages have to be pondered constantly. Shoaling decisions in fishes are communicated via a variety of factors, such as colour signals, amongst other ultraviolet (UV) signals. The sensitivity for ultraviolet signals is assumed to be costly and a function of the predominant ecological conditions. The island of North Uist, Scotland, comprises bodies of water that possess great variation in their spectral distribution, especially in the UV spectral range. We examined different populations of three‐spined stickleback (Gasterosteus aculeatus L.), which is known to use UV for visual tasks, consisting of three populations from tea‐stained lakes and four from clear‐water lakes, concerning their preferences to join a shoal viewed under UV‐present and UV‐absent conditions. Nonreproductively active sticklebacks from tea‐stained lakes significantly preferred the shoal under UV‐absent conditions, whereas sticklebacks from clear‐water lakes did not show a significant preference. Reflection measurements showed that the UV chroma (intensity) of sticklebacks from tea‐stained lakes was higher than that of sticklebacks from clear‐water, most likely contrasting maximally against the UV‐poor background or compensating for a stronger attenuation of the signal.     

The familial placement of Bryowijkia (Musci: Trachypodaceae)

The synapotypic feature of seriate leaf cell papillae positioned on cell lumina and directed over the longitudinal cross walls alliesBryowijkia with the Trachypodaceae. The Hedwigiaceae consist of four closely related genera, and excludesRhacocarpus, a genus best placed in its own family, the Rhacocarpaceae. These taxa all belong in the Leucodontineae (Isobryales) and are not related to either the Grimmiales or the Orthotrichales.     

Bryophyte response surfaces along ecological and climatic gradients

Bivariate response surfaces were fitted to abundance data for 6 mire bryophyte species in ecological and climatic space in western Canada. Response surfaces were derived by gridding data, eliminating outliers, and reducing effects of overly influential abundance values. Predicted values at each grid node were calculated as distance-weighted means of all observed values within a predetermined radius of each node. Response surfaces accurately delimited species ecological and climatic ranges. The gridding process consistently underestimated observed abundance values, and paired t-tests indicated significant differences between predicted and observed values for Sphagnum fuscum and Tomenthypnum nitens in ecological space, and for Sphagnum fuscum, Tomenthypnum nitens, and Scorpidium scorpioides in climatic space. Predicted values were significantly different only for those species that had large data sets, and for species that had clusters of points with an inordinately large number of data points within them. However, with the exception of Sphagnum tenellum, predicted and observed values were significantly correlated for all species in both ecological and climatic space. R ² analyses for the linear relationship between predicted and observed values can be used as a diagnostic tool to determine the effectiveness of the gridding process to accurately predict observed abundance values.Abbreviations p statistical probability     

Amino acid analysis of culture media and autolysates by capillary gas chromatography

N-heptofluorbutyryl-O-propyl ethers from 20 natural amino acids were analysed on a capillary column Am-Ac by gas chromatography. A high reproducibility of the quantitative estimation of the compounds studied was achieved not only for the standard mixtures but when analysing the amino acid composition of the autolysates of the baker's yeast and cultural media.     

On the empirical choice of the time window for restricted mean survival time

The t-year mean survival or restricted mean survival time (RMST) has been used as an appealing summary of the survival distribution within a time window [0, t]. RMST is the patient's life expectancy until time t and can be estimated nonparametrically by the area under the Kaplan-Meier curve up to t. In a comparative study, the difference or ratio of two RMSTs has been utilized to quantify the between-group-difference as a clinically interpretable alternative summary to the hazard ratio. The choice of the time window [0, t] may be prespecified at the design stage of the study based on clinical considerations. On the other hand, after the survival data have been collected, the choice of time point t could be data-dependent. The standard inferential procedures for the corresponding RMST, which is also data-dependent, ignore this subtle yet important issue. In this paper, we clarify how to make inference about a random “parameter.” Moreover, we demonstrate that under a rather mild condition on the censoring distribution, one can make inference about the RMST up to t, where t is less than or even equal to the largest follow-up time (either observed or censored) in the study. This finding reduces the subjectivity of the choice of t empirically. The proposal is illustrated with the survival data from a primary biliary cirrhosis study, and its finite sample properties are investigated via an extensive simulation study.