The Effect of Copper on the Color of Shrimps: Redder Is Not Always Healthier

The objective of this research is to test the effects of copper on the color of pacific white shrimp (Litopenaeus vannamei) in vivo. Forty-eight shrimps (L. vannamei) were exposed to a low concentration of copper (1 mg/L; experimental treatment) and forty-eight shrimps were used as controls (no copper added to the water). As a result of this experiment, it was found that shrimps with more copper are significantly redder than those designated as controls (hue _{(500–700 nm)}: P = 0.0015; red chroma _{(625–700 nm)}: P<0.0001). These results indicate that redder color may result from exposure to copper and challenge the commonly held view that highly pigmented shrimps are healthier than pale shrimps.     

Innovative Individuals Are Not Always the Best Demonstrators: Feeding Innovation and Social Transmission in Serinus canaria

Background

Feeding innovation occurs when individuals choose a novel, unknown type of food and/or acquire new feeding skills. Here we studied feeding innovation and social transmission of the new feeding habit in canaries. Adult canaries eat a wide variety of seeds but avoid larger ones such as those of sunflowers. We determined whether adults of both sexes are equally prone to innovate when confronted with sunflower seeds and whether free-interactions facilitate transmission of the new feeding habit in a sex-dependent manner.

Methodology/Principal Findings

First we determined which sex was more innovative, i.e., was more successful at husking and eating the novel seeds. Males were clearly more innovative than females. Due to this, experienced males served as model for either male or female observers in three different conditions (free interaction with a demonstrator, visual interaction with a demonstrator placed behind a transparent wall and access to seeds in the presence of a non-demonstrating bird). During free interactions, the new feeding habit was only transmitted to females. In contrast, transmission of seed handling to male observers only occurred if demonstrator and observer were separated by the transparent wall. Indeed, aggressive behaviors between males prevented social transmission during free interactions. Finally, we studied the influence of the less innovative females in feeding-habit transmission. First, we obtained female demonstrators by making them freely interact with male demonstrators. Once they acquired innovative responses to sunflower seeds we studied feeding-habit transmission towards male and female observers. Observers of both sexes learned during free interactions with female demonstrators. No aggressive behavior occurred. Males were also able to learn after visual interactions with the female demonstrator.

Conclusions/Significance

Our results show that the most innovative individuals (males) are not always the best demonstrators, and that social relationship and sex are crucial factors for the spread of a new feeding habit among canaries. These factors determine the kind of interaction between individuals and the time spent together, thus affecting the transmission of novel habits within the population.     

The Effects of Endophytes on Seed Production and Seed Predation of Tall Fescue and Meadow Fescue

Fungal endophytes of grasses are often included in agricultural management and in ecological studies of natural grass populations. In European agriculture and ecological studies, however, grass endophytes are largely ignored. In this study, we determined endophyte infection frequencies of 13 European cultivars and 49 wild tall fescue (Schedonorus phoenix) populations in Northern Europe. We then examined seed production and seed predation of endophyte-infected (E+) and endophyte-free (E?) tall fescue (in wild grass populations and in a field experiment) and meadow fescue (Schedonorus pratensis; in a field experiment only). Endophytes were detected in only one of the 13 cultivars. In contrast, >90% of wild tall fescue plants harbored endophytes in 45 wild populations but were absent in three inland populations in Estonia. In three wild tall fescue study sites, 17%, 22%, and 56% of the seeds were preyed upon by the cocksfoot moth. Endophyte infection did not affect seed mass of tall fescue in the field experiment. However, seed predation was lower in E+ than E? grasses in the two tall fescue populations with higher predation rates. For meadow fescue, the mean number of seeds from E+ plants was higher than E? plants, but E? and E+ seeds had equal rates of predation by the moth. Our results suggest that the effects of grass endophytes on seed production and cocksfoot moth seed predation vary considerably among grass species, and the effects may depend on herbivore pressure and other environmental conditions.     

Two Years Later: Journals Are Not Yet Enforcing the ARRIVE Guidelines on Reporting Standards for Pre-Clinical Animal Studies

There is growing concern that poor experimental design and lack of transparent reporting contribute to the frequent failure of pre-clinical animal studies to translate into treatments for human disease. In 2010, the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines were introduced to help improve reporting standards. They were published in PLOS Biology and endorsed by funding agencies and publishers and their journals, including PLOS, Nature research journals, and other top-tier journals. Yet our analysis of papers published in PLOS and Nature journals indicates that there has been very little improvement in reporting standards since then. This suggests that authors, referees, and editors generally are ignoring guidelines, and the editorial endorsement is yet to be effectively implemented.     

Sorption of Fe (Hydr)Oxides to the Surface of Shewanella putrefaciens: Cell-Bound Fine-Grained Minerals Are Not Always Formed De Novo

Shewanella putrefaciens, a gram-negative, facultative anaerobe, is active in the cycling of iron through its interaction with Fe (hydr)oxides in natural environments. Fine-grained Fe precipitates that are attached to the outer membranes of many gram-negative bacteria have most often been attributed to precipitation and growth of the mineral at the cell surface. Our study of the sorption of nonbiogenic Fe (hydr)oxides revealed, however, that large quantities of nanometer-scale ferrihydrite (hydrous ferric oxide), goethite (α-FeOOH), and hematite (α-Fe₂O₃) adhered to the cell surface. Attempts to separate suspensions of cells and minerals with an 80% glycerin cushion proved that the sorbed minerals were tightly attached to the bacteria. The interaction between minerals and cells resulted in the formation of mineral-cell aggregates, which increased biomass density and provided better sedimentation of mineral Fe compared to suspensions of minerals alone. Transmission electron microscopy observations of cells prepared by whole-mount, conventional embedding, and freeze-substitution methods confirmed the close association between cells and minerals and suggested that in some instances, the mineral crystals had even penetrated the outer membrane and peptidoglycan layers. Given the abundance of these mineral types in natural environments, the data suggest that not all naturally occurring cell surface-associated minerals are necessarily formed de novo on the cell wall.     

Differential Effects of Hunting on Pre-Dispersal Seed Predation and Primary and Secondary Seed Removal of Two Neotropical Tree Species

Many of the mammals undergoing drastic declines in tropical forests worldwide are important seed dispersers and seed predators, and thus changes in mammal communities due to hunting will affect plant recruitment. It has been hypothesized that larger-seeded species will suffer greater reductions in seed removal and thus greater increases in predispersal seed predation than smaller-seeded species. We compared primary and secondary seed removal and predispersal seed predation of two tree species between hunted and nonhunted sites in Central Panama. Seeds of Oenocarpus mapora (Arecaceae) are 16-times greater in size than those of Cordia bicolor (Boraginaceae). We quantified primary seed removal and predispersal seed predation using seed traps, and we assessed secondary seed removal using seed removal plots. Primary removal of C. bicolor was 43 percent lower in the hunted sites, while primary removal of O. mapora was not significantly different. Secondary removal of unprotected O. mapora seeds on the ground was 59 percent lower in hunted sites, while secondary removal of C. bicolor was not significantly different. Predispersal seed predation of O. mapora by mammals was significantly lower in hunted sites, while predispersal seed predation by insects was not significantly different in either species. In combination with other studies, our results suggest that seed size is not a reliable predictor of the impacts of hunting. Mammal defaunation differentially affects stages and modes of seed dispersal and seed predation of different plant species, suggesting that these influences are complex and related to multiple plant traits.     

The Effect of Dung and Dispersal on Postdispersal Seed Predation of Attalea phalerata (Arecaceae) by Bruchid Beetles1

Low postdispersal mortality of palm seeds in tapir dung is hypothesized to result from the mechanical barrier provided by dung against bruchid infestation and/or from the distance to adult palms at which seeds are dispersed. We tested these hypotheses by distributing endocarps of Attalea phalerata Mart. ex Spreng. in experimental dung piles in Beni, Bolivia. Predation rates were significantly lower for seeds covered by dung than for exposed or partially covered seeds, but did not differ between seeds placed below and 50 m away from palms. Thus, dung, not short‐distance dispersal, protects seeds against bruchid beetles, and may ultimately promote survival of palm seeds.     

Low Sugar Is Not Always Good: Impact of Specific O-Glycan Defects on Tip Growth in Arabidopsis

Mutants of the O-glycosylation pathway of extensins as well as molecular dynamics simulations uncover the effects of the O-glycosylation machinery on root hair tip growth.The hydroxyproline-rich O-glycoproteins (HRGPs) comprise several groups of O-glycoproteins, including extensins (EXTs), ultimately secreted into plant cell walls. The latter are shaped by several posttranslational modifications, mainly hydroxylation of Pro residues into Hyp and further O-glycosylation on Hyp and Ser (Supplemental Fig. S1A). EXTs contain several Ser-(Hyp)₄ repeats, usually O-glycosylated with chains of up to four or five linear arabinosyl units on each Hyp (Velasquez et al., 2011; Ogawa-Ohnishi et al., 2013) and monogalactosylated on Ser residues (Saito et al., 2014). O-Glycosylated Ser-(Hyp)₄ repeats are not only present in EXTs but can potentially decorate several other EXT-like chimeras and hybrid EXT glycoproteins that contain other domains, such as arabinogalactan protein-EXTs, Pro-rich protein-EXTs, Leu-rich repeat-EXTs, Pro-rich kinases, and formins with an extracellular EXT domain, etc. In addition, Hyp-O-arabinosylation also occurs in single Hyp units in the small secreted glycopeptide hormones (e.g. CLAVATA3 [CLV3]) with up to three arabinosyl units (Ohyama et al., 2009; Matsubayashi, 2010; Shinohara and Matsubayashi, 2013). In this context, three groups of arabinosyltransferases (AraTs), hydroxyproline O-arabinosyltransferase1 (HPAT1) to HPAT3 (classified as GT8 in the Carbohydrate Active Enzymes database), Reduced Residual Arabinose1 (RRA1) to RRA3, and Xyloglucanase113 (XEG113; GT77 family), have recently been implicated in the sequential addition of the innermost three l-arabinosyl residues (Egelund et al., 2007; Ogawa-Ohnishi et al., 2013; Supplemental Table S1). In addition, one novel peptidyl-Ser galactosyltransferase named SERGT1 has been reported to add a single α-galactopyranose residue to each Ser residue in Ser-(Hyp)₄ motifs of EXTs, thus belonging to the GT96 family within the Carbohydrate Active Enzymes database (Supplemental Table S1). Finally, glycosylated EXTs are possibly cross-linked by putative type III peroxidases at the Tyr residues, forming EXT linkages (Cannon et al., 2008) able to build a three-dimensional network likely to interact with other cell wall components like pectins (Cannon et al., 2008). EXT assembly into a putative glycoprotein network seems to be crucial for cell expansion of root hair, and several EXT and EXT-related mutants (e.g. ext6-7, ext10-12, and Leu-rich repeat extensin1, etc.) were previously isolated with abnormal root hair cell expansion phenotypes (Ringli, 2010; Velasquez et al., 2011).Here, by using mutants of several known enzymes of the O-glycosylation pathway of HRGPs, we addressed to what extent each specific defect on the O-glycosylation machinery impacts root hair tip growth. In addition, we refer only to Hyp-O-arabinosylation and Ser-O-galactosylation modifications of EXT and EXT-related proteins, while we have excluded Hyp O-(arabino)galactosylation, commonly present in other types of HRGP like arabinogalactan proteins, from our analysis. Finally, by molecular dynamic simulations, we propose a possible model to explore how these two specific types of O-glycan defects would affect EXT self-assembly and, ultimately, their impact on the polarized cell expansion. We use a classical EXT repetitive sequence to begin to explore how O-glycosylation might affect glycoprotein conformation and possible self-interactions in the context of polarized growth, but we are aware of the complexity and diversity of EXT and EXT-related proteins that offers several other possible scenarios.     

Seed Dynamics of Early and Late Successional Tree Species in Tropical Abandoned Pastures: Seed Burial as a Way of Evading Predation

We explored different treatments to enhance the probability of sowed seeds of two early successional (ES, Cecropia obtusifolia and Ochroma pyramidale) and two late successional (LS, Brosimum costaricanum and Dialium guianense) species to escape predation and germinate in abandoned cattle‐raising pasture fields in Southeastern Mexico. ES species were sown in groups of 50 seeds under three treatments: invertebrate exclusion, burial, and exposition to seedeaters. LS species were sown in groups of 10 seeds under three treatments: vertebrate exclusion, burial, and exposition to seedeaters. We registered seed predation and germination 2, 4, 8, 16, 32, and 64 days after the initial sowing. Overall, ES showed higher predation rates (mean ± SE = 0.45 ± 0.07 seed seed^?1 day^?1; n = 3) than LS species (0.09 ± 0.02 seed seed^?1 day^?1). Cecropia obtusifolia was completely predated in all treatments after 8 days. Burial and exclusion treatments reduced final predation in circa 6% for O. pyramidale, relative to that of exposed seeds (85% after 8 days); most germination occurred in buried seeds (3.7%). In B. costaricanum, burial enabled germination by 10%; exposed and excluded seeds were removed 100%. Dialium guianense showed 12% germination in buried seeds and circa 20% of the seeds were not removed after 64 days. Direct sowing would be a recommended rainforest restoration practice for species with relatively large seeds if deposited in groups and buried. Studies which address variation across numerous sites are necessary in order to generate more consistent seed predation patterns and rainforest restoration principles in tropical pastures.     

Effect of Potassium on Sucrose and Amino Acid Release from the Seed Coat of Developing Seeds of Pisum sativum

After removal of the embryo from developing seeds of Pisum sativum,the ‘empty’ ovules (seed coats without enclosedembryo) were filled with a solution (pH 5.5) containing mannitol(usually 400 mM) to which various salts were added. A solutioncontaining two isotopes ((a) [²H]-sucrose/[–¹⁴C]aminoisobutyricacid (AIB) or (b) [³H]valine/[₁₄C]asparagine mixture) was administeredto the plant via the petiole subtending the fruiting node, and[²H]solute and [¹⁴C]solute unloading from the seed coat wasmeasured, in pulse-labelling experiments of about 5 h. The presenceof 25 or 50 mM K⁺ in the ‘empty’ ovule enhancedthe release of sucrose from the seed coat particularly duringthe first hours of the experiment, but the stimulating effectof K⁺ on the release of labelled solutes derived from aminoacids was much smaller. The presence of 25 mM CaCl₂ did notaffect the release of sucrose or amino acids from the seed coat.The effect of K⁺ on sucrose and amino acid release is explainedas an inhibition of sucrose and amino acid resorption from theseed coat apoplast into seed coat cells, after unloading fromthe seed coat unloading sites. It is suggested that amino acidrelease is much less affected by K⁺ than sucrose release, becausefar less resorption of amino acids by seed coat parenchyma cellstakes place during amino acid transport into the seed coat cavity. Pisum sativum, pea, assimilate transport, assimilate unloading, seed-coat exudate, seed development, sucrose resorption, surgical treatment     

石硖龙眼未成熟种子种胚的萌发及成苗的研究

以花后82～87 d的石硖龙眼(Dimocarpus longan Lour.‘Shixia’)未成熟果实在4℃贮藏24 h,研究种子与种胚的萌发与成苗情况。结果表明:河沙直播未成熟胚的最终成苗率达到80%,远高于离体培养未成熟种子的最终成苗率(12.63%～44.03%);虽然4℃的低温贮藏略为推迟了河沙直播未成熟胚的萌发时间,但对最终成苗率及幼苗生长的影响不大,这对龙眼杂交育种中未成熟种子种胚的挽救具有较好的应用价值。     

The Effect of Bleaching on the Terpene Chemistry of Plexaurella fusifera: Evidence that Zooxanthellae Are Not Responsible for Sesquiterpene Production

The close association between marine invertebrates, zooxanthellae, and numerous bacteria gives rise to the question of the identity of the actual producer of secondary metabolites. In fall of 2005, a widespread bleaching event occurred throughout the Caribbean Sea in which some colonies of the gorgonian coral Plexaurella fusifera bleached. This study investigated whether zooxanthellae play a key role in the biosynthesis of secondary metabolite terpenes from P. fusifera. The extent of bleaching was examined by chlorophyll A analysis and also by zooxanthellae isolation and cell counting. The bleached and unbleached colonies were found to contain similar concentrations of eremophilene as the major terpene, and both exhibited similar biosynthetic capability as evaluated by the transformation of [C(1)-(3)H]-farnesyl diphosphate to the sesquiterpenes. Differences in bacterial communities between the bleached and unbleached colonies were analyzed using molecular techniques, and preliminary indications are that unbleached and bleached corals are dominated by low G + C firmicutes and gammaproteobacteria, respectively. It therefore appears that terpene biosynthesis can proceed independently of the zooxanthellae in P. fusifera, suggesting that the coral or a bacterium is the biosynthetic source.     

The Effect of Pollen Source vs. Flower Type on Progeny Performance and Seed Predation under Contrasting Light Environments in a Cleistogamous Herb

Dimorphic cleistogamy is a specialized form of mixed mating system where a single plant produces both open, potentially outcrossed chasmogamous (CH) and closed, obligately self-pollinated cleistogamous (CL) flowers. Typically, CH flowers and seeds are bigger and energetically more costly than those of CL. Although the effects of inbreeding and floral dimorphism are critical to understanding the evolution and maintenance of cleistogamy, these effects have been repeatedly confounded. In an attempt to separate these effects, we compared the performance of progeny derived from the two floral morphs while controlling for the source of pollen. That is, flower type and pollen source effects were assessed by comparing the performance of progeny derived from selfed CH vs. CL and outcrossed CH vs. selfed CH flowers, respectively. The experiment was carried out with the herb Ruellia nudiflora under two contrasting light environments. Outcrossed progeny generally performed better than selfed progeny. However, inbreeding depression ranges from low (1%) to moderate (36%), with the greatest value detected under shaded conditions when cumulative fitness was used. Although flower type generally had less of an effect on progeny performance than pollen source did, the progeny derived from selfed CH flowers largely outperformed the progeny from CL flowers, but only under shaded conditions and when cumulative fitness was taken into account. On the other hand, the source of pollen and flower type influenced seed predation, with selfed CH progeny the most heavily attacked by predators. Therefore, the effects of pollen source and flower type are environment-dependant and seed predators may increase the genetic differences between progeny derived from CH and CL flowers. Inbreeding depression alone cannot account for the maintenance of a mixed mating system in R. nudiflora and other unidentified mechanisms must thus be involved.     

捕食风险的种群动态效应及其作用机理研究进展

捕食者不但可以通过直接捕杀猎物而控制猎物的种群数量,还可以通过捕食风险效应影响猎物种群的繁殖和动态,并且在某些情况下,捕食风险效应对猎物种群动态的控制作用甚至大于捕食者的直接捕杀.关于捕食风险效应对猎物动物繁殖产出和种群动态变化的作用及其机理方面的野外研究越来越受到国内外学者重视.本文介绍了近年来捕食风险效应的研究进展,重点关注了美国黄石国家公园中捕食者对马鹿(Cervus elephus)、加拿大育空地区的捕食者对白靴兔(Lepus americanus)的捕食风险效应等案例研究,以阐明捕食风险效应对猎物种群动态影响的重要性,以及关于捕食风险效应影响猎物种群繁殖和动态机理的两个假说(捕食者敏感食物假说、捕食应激假说).并结合我国在捕食者与猎物之间关系的研究现状,提出了进一步在野外开展捕食风险效应对濒危有蹄类猎物种群动态影响研究的建议,阐释了开展这些研究的重要意义.     

种皮和环境温度对橡胶树种子萌发的影响

在人工气候箱控制的条件下,研究了种皮和环境温度对橡胶树(Hevea brasiliensis)种子萌发的影响.结果表明,种皮对橡胶树种子的吸水和萌发具有明显的机械限制作用;去除种皮后种子萌发速率加快,萌发指数增大,但萌发率从83.8%下降到47.8%,幼苗活力指数从332.3下降到187.9.15℃以下的温度明显推迟种子萌发,且萌发率下降.去除种皮后的种仁萌发率、萌发指数和幼苗活力指数均随着温度的升高而增大;有种皮种子的萌发率、萌发指数和幼苗活力指数分别在20℃(94.7%)、30℃(1.86)和25℃(374.4)时最大,而萌发速率系数随着温度的升高先增大后减小.在橡胶树栽培和胶园建设中,可利用种皮对种仁水分散失的限制作用以及对低温的不敏感性,有效延长橡胶树种子的贮藏时间,提高萌发率和籽苗质量.     

Wheat Seed Carboxypeptidase and Joint Action on Gliadin of Proteases from Dry and Germinating Seeds

A carboxypeptidase preparation, homogeneous according to polyacrylamidegel electrophoresis and ultracentrifugation, was obtained fromwheat seeds. The isolation procedure included (NH₄)₂SO₄ fractionation,gel-filtration on Sepharose-6B and affinity chromatography onCABS-Sepharose. Mr of the enzyme determined by gel-filtrationwas 126 000. The enzyme consisted of two non-identical subunitsof Mr 60 000 and 63 000. The pl of the carboxypeptidase was5.7. The inhibitory analysis revealed that the isolated enzymeis a serine carboxypeptidase. The carboxypeptidase preferentiallyhydrolysed N-substituted dipeptides with aromatic amino acidresidues at the C-terminus and showed weak hydrolysing activitytowards gliadin. The combined action of carboxypeptidase andaspartic proteinase from dry wheat seeds led to an increasein the degree of proteolysis of the storage protein comparedto that resulting from the sum of the action of individual enzymes.The cysteine proteinase from germinated wheat seeds caused completedegradation both of gliadin, which had first been treated withproteases of dry seeds (aspartic proteinase plus carboxypeptidase),and of untreated gliadin. However, when gliadin had first beenhydrolysed with dry seed proteases, the rate of its proteolysiswith cysteine proteinase increased 3–4 times comparedto the non-hydrolysed gliadin. The data indicate the importanceof preliminary modification of gliadin with dry wheat proteases,which, apparently, enhances the supply of nutritive substancesto the embryo in the course of seed germination. Key words: Wheat, gliadin, carboxypeptidase, proteinases, proteolysis     

Ageing and Osmotic Priming in Wheat Seeds: Effects Upon Certain Components of Seed Quality

Deteriorated wheat seed lots were osmotically primed and surface-dried,dried-back, then aged for two more weeks Osmotic priming didnot affect the final germination in any of the aged seed lots,but mean germination time was decreased The response of unagedseed lot to treatments was studied in the following the timecourses of germination, as well as L-[4, 5-²H]leucine and [6-³H]thymidineincorporation (as a measure of protein and DNA synthesis, respectively)into dissected embryos during the early hours of germinationIt was found that the variation in mean germination time andthe rate of synthetic reactions were related The greatest improvementin the components of seed lot quality was achieved after primingand surface drying The beneficial effects of priming were apparenteven after dehydration followed by two further weeks of ageingCumulative correlations between mean germination time and variousbiochemical tests in variously treated aged seed lots were highlysignificant The physiological processes involved in deteriorationand recovery and the potential application of biochemical testsin detecting vigour changes are discussed Triticum durum, seed, ageing, osmotic priming, mean germination time, protein DNA synthesis     

捕食风险与动物行为及其决策的关系

捕食风险与动物行为及其决策的关系边疆晖樊乃昌（中国科学院西北高原生物研究所,西宁８１０００１）（浙江师范大学,金华３１００００）ＴｈｅＥｆｅｃｔｏｆＰｒｅｄａｔｉｏｎＲｉｓｋｏｎＡｎｉｍａｌｓ’ＢｅｈａｖｉｏｒａｎｄＴｈｅｉｒＤｅｃｉｓｉｏｎ．Ｂｉａ...