Stairway to Heaven: Evaluating Levels of Biological Organization Correlated with the Successful Ascent of Natural Waterfalls in the Hawaiian Stream Goby Sicyopterus stimpsoni

Selective pressures generated by locomotor challenges act at the level of the individual. However, phenotypic variation among individuals that might convey a selective advantage may occur across any of multiple levels ofbiological organization. In this study, we test for differences in external morphology, muscle mechanical advantage, muscle fiber type and protein expression among individuals of the waterfall climbing Hawaiian fish Sicyopterus stimpsoni collected from sequential pools increasing in elevation within a single freshwater stream. Despite predictions from previous laboratory studies of morphological selection, few directional morphometric changes inbody shape were observed at successively higher elevations. Similarly, lever arm ratios associated with the main pelvic sucker, central to climbing ability in this species, did not differ between elevations. However, among climbingmuscles, the adductor pelvicus complex (largely responsible for generating pelvic suction during climbing) contained a significantly greater red muscle fiber content at upstream sites. A proteomic analysis of the adductor pelvicusrevealed two-fold increases in expression levels for two respiratory chain proteins (NADH:ubiquinone reductase and cytochrome b) that are essential for aerobic respiration among individuals from successively higher elevations.Assessed collectively, these evaluations reveal phenotypic differences at some, but not all levels of biological organization that are likely the result of selective pressures experienced during climbing

Accelerated shelf-life testing of quality loss for a commercial hydrolysed hen egg white powder

In recent years, due to the specific health benefits associated with bioactive peptides and the reduction of protein allergenicity by enzymatic hydrolysis, the utilisation of protein hydrolysates in functional foods and beverages for both protein supplementation and clinical use has significantly increased. However, few studies have explored the moisture-induced effects on food protein hydrolysates, and the resulting changes in the structure and texture of the food matrix as well as the loss in functional properties of bioactive peptides during storage. The main purpose of this study is to determine the influence of water activity (a(w)) on the storage quality of a commercial spray-dried hydrolysed hen egg white powder (HEW). During storage at 45 degrees C for two months at different a(w)s (0.05-0.79), the selected physicochemical properties of the HEW samples were analysed. Overall, the effect of a(w) on the colour change of HEW at 45 degrees C for one month was similar to that of HEW after four months at 23 degrees C due to the presence of a small amount of glucose in HEW. Several structural changes occurred at a(w)s from 0.43 to 0.79 including agglomeration, stickiness and collapse. Kinetic analysis showed a first-order hyperbolic model fit for the change in the L* value, the total colour difference (Delta E*) and the fluorescence intensity (FI). There was a high correlation between colour change and fluorescence, as expected for the Maillard reaction. The reduction in the remaining free amino groups was about 5% at a(w) 0.50 and 6% at a(w) 0.79 after one month storage. In summary, during storage, the Maillard reaction and/or its resulting products could decrease the nutritional value and the quality of HE

Stairway to Heaven: Evaluating Levels of Biological Organization Correlated with the Successful Ascent of Natural Waterfalls in the Hawaiian Stream Goby <i>Sicyopterus stimpsoni</i>

<div><p>Selective pressures generated by locomotor challenges act at the level of the individual. However, phenotypic variation among individuals that might convey a selective advantage may occur across any of multiple levels of biological organization. In this study, we test for differences in external morphology, muscle mechanical advantage, muscle fiber type and protein expression among individuals of the waterfall climbing Hawaiian fish <i>Sicyopterus stimpsoni</i> collected from sequential pools increasing in elevation within a single freshwater stream. Despite predictions from previous laboratory studies of morphological selection, few directional morphometric changes in body shape were observed at successively higher elevations. Similarly, lever arm ratios associated with the main pelvic sucker, central to climbing ability in this species, did not differ between elevations. However, among climbing muscles, the adductor pelvicus complex (largely responsible for generating pelvic suction during climbing) contained a significantly greater red muscle fiber content at upstream sites. A proteomic analysis of the adductor pelvicus revealed two-fold increases in expression levels for two respiratory chain proteins (NADH:ubiquinone reductase and cytochrome b) that are essential for aerobic respiration among individuals from successively higher elevations. Assessed collectively, these evaluations reveal phenotypic differences at some, but not all levels of biological organization that are likely the result of selective pressures experienced during climbing.</p> </div

Variation in morphometric variables across successively higher elevation collecting localities.

<p>Size-corrected residuals of sixteen morphological traits (and the hydrodynamic index fineness ratio) compared among the four collection sites (Nanue 1 through 4 on the x-axis). Solid lines represent medians, dashed lines represent means, boxes indicate the 25^th and 75^th percentiles, and bars delineate 10^th and 90^th percentiles. Data points outside this range are graphed individually. Alphabetical designations for the ANOVA groupings of sites follow the rank of mean values, with earlier letters indicating higher means. Sample sizes for all graphs: Nanue 1, N=50; Nanue 2, N=30; Nanue 3, N=35; Nanue 4, N=21.</p

Percentage of red and intermediate fibers in three muscles in <i>Sicyopterus stimpsoni</i>.

<p>(A) Comparison of red and intermediate fiber contribution across muscle types, independent of stream segment; (B) % red and intermediate muscle fibers in adductor pectoralis, a muscle not involved in climbing; (C) % red and intermediate muscle fibers in the abductor pelvicus complex muscle; (D) % red and intermediate muscle fibers in the adductor pelvicus complex muscle. Sample size indicated in each column. Letters above columns indicate statistically significant differences between columns (p<0.05; Kruskal-Wallis with Dunn’s <i>post-hoc</i> test).</p

Measurements taken from <i>Sicyopterus stimpsoni</i> for morphometric analysis.

<p>Anatomical variables linked to numbers in this figure can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0084851#pone-0084851-t001" target="_blank">Table 1</a>.</p

Muscles assessed for effects of climbing selection.

<p>(A) Schematic drawing of <i>Sicyopterus stimpsoni</i> (upper left) and the area of dissection (box and enlargement). Muscles and their respective in- and out-levers are indicated in the magnified drawings of the pelvic girdle (B, C). The relative position of the adductor pectoralis is indicated by the arrow near the top of the drawing. The position of the abductor pelvicus complex deep to the pelvis is indicated by the hashed line in C. Muscles for which red fiber content was established are in bold print. Drawing not to scale.</p

Schematic topography of Nanue stream on the Big Island of

<div><p>Hawai’i (Hawai’i). </p> <p>Arrow on the map indicates location of Nanue stream. Name and length of stream segment are indicated below each segment. Approximate heights of waterfalls are provided next to the vertical lines, with an image of each waterfall. Schematic drawing not to scale.</p></div

Assessing Occurrence and Biological Consequences of Contaminants of Emerging Concern on Oceanic Islands

Freshwater streams on oceanic islands serve critical ecological and economic functions. However, these are underrepresented in assessments of pollution from contaminants of emerging concern (CEC). Furthermore, freshwater streams and their endemic fauna often have characteristics that are distinct from those of continental streams and model species, calling extrapolations from studies of such systems into question for island streams. In the current study, we assessed the presence of CEC across three sampling events and five freshwater streams on the Island of Hawai&rsquo;i. We also exposed juveniles of the native fish species Sicyopterus stimpsoni to a mixture of commonly co-occurring CEC for 96 h in static renewal experiments, testing for impacts of CEC in two ecologically relevant assays of functional performance. CEC from multiple sources were ubiquitous in Hawaiian streams, including human-use pharmaceuticals, agricultural herbicides, and industrial runoff. Concentrations of CEC were comparable to published studies from continental streams, exceeding total concentrations of 1000 ng/L for the eight quantified CEC in four samples, and approaching 2500 ng/L in one sample. Effects on exposed fish were subtle and limited to treatments with higher CEC concentrations but indicated potential impacts of CEC on locomotor performance. These results indicate that Hawaiian streams follow a global trend of widespread freshwater pollution by CEC that are accompanied by subtle effects on native fish species and highlight the need for the inclusion of endemic species and ecologically relevant assays when assessing the effects of contaminants in island habitats