Effects of ambient acidity on chemosensory learning: an example of an environmental constraint on acquired predator recognition in wild juvenile Atlantic salmon (Salmo salar)

Abstract –  In many prey fish species, learning the identity of novel predators may be facilitated when novel predator cues and an aversive stimulus are presented together. Damage-released chemical alarm cues are typically released from the skin of prey individuals following mechanical damage and are known to mediate the learned recognition of novel predators. While such chemically mediated acquired predator recognition can provide increased survival benefits to prey, environmental constraints impeding learning may exist. For example, in several fish species the ability to detect chemical alarm cues is impaired in under acidic conditions and as such, inhibits this chemically mediated learning. In this experiment, we studied in two streams of different mean acidity level (pH c . 6.0 and 7.0), to assess if wild juvenile Atlantic salmon ( Salmo salar ) had the ability to acquire the recognition of a novel lemon essence odour when paired with conspecific chemical alarm cues. Our results demonstrate that under acidic conditions, no learned recognition of the novel odour occurred. In neutral conditions, however, salmon recognised the novel odour as a predation threat. This result suggests that ambient acidity creates an environmental constraint on chemically mediated learned recognition of a novel cue.     

Extended exposure to trichostatin A after activation alters the expression of genes important for early development in nuclear transfer murine embryos

The low viability of embryos reconstructed by somatic cell nuclear transfer (SCNT) is believed to be associated with epigenetic modification errors, and reduction of those errors may improve the viability of SCNT embryos. The present study shows the effect of trichostatin A (TSA), a strong inhibitor of histone deacetylase, on the development of murine SCNT embryos. After enucleation and nuclear injection, reconstructed murine oocytes were activated with or without TSA for 6 hr (TSA-6 hr). After activation, TSA treatment was extended to 3 hr (TSA-9 hr), 5 hr (TSA-11 hr) and 18 hr (TSA-24 hr) during culture. As a result, the SCNT embryos in the TSA-11 hr group showed a remarkably higher blastocyst rate (21.1%) when compared with the nontreated embryos (3.4%), while the concentration of TSA did not significantly affect embryonic development. The expressions of histone deacetylase (HDAC1 and HDAC2) and DNA methylation (DNMT3a and DNMT3b) genes decreased in the TSA-11 hr and TSA-24 hr groups, while there was an increase in the expression of histone acetyltransferase (P300 and CBP), pluripotency (OCT4 and NANOG) and embryonic growth/trophectoderm formation (FGF4)-related genes in the same groups. The expression of CDX2, a critical gene for trophectoderm formation was upregulated only in the TSA-24 hr group. Our results show that TSA treatment during the peri- and postactivation period improves the development of reconstructed murine embryos, and this observation may be explained by enhanced epigenetic modification of somatic cells caused by TSA-induced hyperacetylation, demethylation and upregulation of pluripotency and embryonic growth after SCNT.     

Classification of synthetic polyurethane leather by mechanical properties according to consumers’ preference for fashion items

This study aims to evaluate the effect of mechanical properties on consumers’ preference for fashion leather items, and to classify them by the mechanical properties of synthetic leather. Mechanical properties were measured by the KES-FB system and a survey of experts was conducted with a preference evaluation for various items using 15 types of synthetic polyurethane leather. More easily transformable and lighter leathers are preferred for clothing, while the leathers that have better dimensional stability are preferred for purses, bags, shoes, and boots, and those with smooth surface are preferred for furniture. Furthermore, synthetic leathers were classified into three clusters by mechanical properties. There was no difference between clusters in preference for non-clothing item, because no perception of various mechanical properties was caused by the structural characteristics of each items by design. On the other hand, for clothing items, consumers’ preferences are significantly affected by mechanical properties.     

Preparation and characterization of polyurethane foam using a PLA/PEG polyol mixture

Polyurethanes are polymers with urethane linkages in their backbone. It is prepared by polyaddition polymerization between isocyanates and polyols, which produce different chemical, physical, and mechanical properties depending on their types and characteristics. Previous reports of polyurethane foams prepared by using PEG polyol indicated prominent features in the elasticity and recovery of the foams. However, it is necessary to improve the mechanical strength of these materials. In this study, polyurethane foams were prepared using a PLA/PEG polyol mixture and 1,6-hexamethylene diisocyanate. PLA polyol was synthesized by the direct condensation polymerization of lactic acid. The polyurethane foams were characterized using FE-SEM analysis, FT-IR spectroscopy, water absorbency measurement, and mechanical property measurement. In FE-SEM analysis, it was shown that the PLA content of polyol mixture significantly affected the porous structure. FT-IR spectra confirmed that urethane linkages formed between the PLA/PEG polyols and the isocyanates. The water absorbency decreased due to the hydrophobicity of PLA. With respect to the mechanical properties, the breaking stress and the Young’s modulus increased with increasing PLA content. When the PLA content of polyols was 60 and 70 percent, the breaking strain was significantly higher than those of other polyurethane foams.     

Confirmation of Clematis hybrids using molecular markers

The hybrid origin of progeny from crosses of Clematis tubulosa and Clematis brevicaudata was investigated using randomly amplified polymorphic DNA (RAPD) and single nucleotide polymorphisms (SNPs) from sequence analysis of chloroplast rbcL, accD genes, and the C. brevicaudatamatK gene. Plants collected from three and four populations of C. brevicaudata (C. brev) and C. tubulosa (C. tubu), respectively, from Mt. Songshan, Beijing, China were used as parents for hybridization. Morphological characters of pollen, seeds, and leaves were recorded in 2007. DNA from leaf samples of both parents and of C. brev × C. tubu and C. tubu × C. brev were extracted, and used for RAPD and SNPs from sequence data. A dendrogram was constructed by the branching neighbor-joining (IB-NJ) method. Proportionate population scores were generated by the admixture model using the STRUCTURE software. Based on morphological characters, C. brevicaudata was quite uniform. However, variations were detected in C. tubulosa. Hybrids of C. brev × C. tubu and C. tubu × C. brev showed intermediate morphological characters of the parents. Accessions of C. tubu × C. brev were clustered into 2 groups, with the majority of hybrids belonging to group IV b in the RAPD dendrogram, suggesting that this resulted from variations within C. tubulosa. In general, the hybrid origin of all progeny characterized by morphological characters was supported by the RAPD and SNPs data. These results indicate that RAPD results supported by SNPs data will be useful tool to verify hybrids.     

Forest structure and carbon dynamics of an intact lowland mixed dipterocarp forest in Brunei Darussalam

Tropical forests play a critical role in mitigating climate change because they account for large amount o terrestrial carbon storage and productivity.However,there are many uncertainties associated with the estimation o carbon dynamics.We estimated forest structure and carbon dynamics along a slope(17.3°–42.8°)and to assess the relations between forest structures,carbon dynamics,and slopes in an intact lowland mixed dipterocarp forest,in Kuala Belalong,Brunei Darussalam.Living biomass,basa area,stand density,crown properties,and tree family composition were measured for forest structure.Growth rate,litter production,and litter decomposition rates were also measured for carbon dynamics.The crown form index and the crown position index were used to assess crown properties,which we categorized into five stages,from very poor to perfect.The living biomass,basal area and stand density were 261.5–940.7 Mg ha~(-1),43.6–63.6 m~2ha~(-1)and 6,675–8400 tree ha~(-1),respectively.The average crown form and position index were 4,which means that the crown are mostly symmetrical and sufficiently exposed for photosynthesis.The mean biomass growth rate,litter production,litter decomposition rate were estimated as11.9,11.6 Mg ha~(-1)a~(-1),and 7.2 g a~(-1),respectively.Biomass growth rate was significantly correlated with living biomass,basal area,and crown form.Crown form appeared to strongly influence living biomass,basal area and biomass growth rate in terms of light acquisition.However,basal area,stand density,crown properties,and biomass growth rate did not vary by slope or tree family composition.The results indicate that carbon accumulation by tree growth in an intact lowland mixed dipterocarp forest depends on crown properties.Absence of any effect of tree family composition on carbon accumulation suggests that the main driver of biomass accumulation in old-growth forests of Borneo is not species-specific characteristics of tree species.     

Interspecific variations in seed germination of Corylopsis

This study was initiated to investigate the differences in germination percentages and rates between Corylopsis coreana Uyeki and Corylopsis sinensis var. calvescens Rehder & E.H. Wilson following a warm stratification (WS) and cold stratification (CS), and to study the effect of different WS temperatures interacting with different durations of CS. Warm stratification at 10 °C, 15 °C, 20 °C, and 25 °C was given for 1 month (1 M 10 °C, 15 °C, 20 °C, and 25 °C WS) followed by 0 M, 1 M, 2 M, and 3 M of CS at 5 °C (0 M, 1 M, 2 M, 3 M CS) and seeds were germinated in an air conditioned greenhouse maintained at 18.5 °C/18 °C. On average, less than 1% of C. coreana seeds germinated when sown without any WS and CS or with 1 M 15 °C, 20 °C, and 25 °C WS without CS treatment. However, 26% C. coreana seeds germinated after 1 M 10 °C WS without any CS treatment. Germination was not affected by WS temperatures when followed by 2 M 5 °C CS. It is concluded that C. coreana exhibited low seed germination at 10 °C and that this temperature could be considered the upper limit of CS for C. coreana. Only 2 M CS was required for more than 90% seeds to germinate. However, C. sinensis var. calvescens required longer than 3 M CS for more than 29% seeds to germinate. This clearly shows that there is an interspecific variation in optimum dormancy-breaking requirements.