Search

Deep-sea animals inhabiting the hadal zone (>6000 m deep) are frequently reported to occupy large bathymetric ranges, but details of intra-specific population structure and the underlying drivers remain poorly understood. Here we describe the population structure of the dominant SW Pacific hadal amphipod, Bathycallisoma schellenbergi, across its bathymetric range in the Kermadec (10,047 m) and New Hebrides (7156 m) trenches and explore the factors likely responsible for the observed patterns. These two trenches are relatively close geographically but underlie different water masses and are topographically isolated by the Kermadec fore-arc. The minimum depth of B. schellenbergi was ~1000 m shallower in the New Hebrides Trench than in the Kermadec Trench although similar patterns of ontogenetic stratification were present; juveniles were restricted to depths Hirondellea dubia, at mid-trench depths corresponded to maximum densities of B. schellenbergi , a trend that was reversed towards the trench axes regardless of actual depth. This suggests that the population structure and amphipod assemblages are more affected by how trench topography influences the distribution of food and potential ecological interactions, rather than simply by the effects of hydrostatic pressure.

Purpose Exercise and sport participation lead to many physical and psychosocial benefits. However, barriers to exercise and sporting participation exist. This study aims to examine if stammering acts as a barrier to exercise and sporting participation in adults. Methods One hundred and six adults who stammer (male n = 74, female n = 32; 33.83 ± 14.5 years) completed an anonymous questionnaire which evaluated their stammering history, exercise and sporting participation, views on why they exercise, whether stammering prevented or negatively influenced their participation in exercise or sport. Descriptive statistics were then calculated. Results The majority (90.6 %) of participants take part in some form of exercise/sport. However, their stammer prevented them from taking part in a specific exercise/sport at least once (49.1 %), due to being too nervous to introduce themselves, nervous or fear of stammering or being judged. Their stammer also negatively impacted their involvement when participating at least once (42.4 %), with not feeling part of the team and fear of speaking reported. Self-disclosure of their stammer and improving awareness of stammering were identified as common facilitators for taking part in exercise/sport. Conclusion Stammering was not found to impact general participation in exercise and sport but was identified as a barrier to partaking in specific exercise and sport and their enjoyment thereof. Encouraging those who stammer to inform those involved in sport and exercise (e.g. fellow players, coaches) about their stammer and improving stammer awareness across the general and sporting population may encourage further participation in exercise and sport in those who stammer.

Highly refractive and transparent polyphosphonates with varying aromatic backbones have been synthesised by polycondensation of phosphonic dichlorides and diols, significantly expanding the reported scope of these intrinsic high refractive index polymers. The polyphosphonates display excellent thermal properties, with thermal stability up to 450 °C and tuneable glass transition temperatures ranging from 41 to 214 °C by terminating the polymer with different alcohols. The polymers synthesised also possess excellent optical properties, with low UV cut off points and high refractive indices up to 1.66, the highest reported for this type of polymer. We also report Abbe numbers for this class of polymers for the first time; all are high (>22), making these polymers excellent potential candidates for a range of optical applications.

There are few biological datasets that span large bathymetric ranges with sufficient resolution to identify trends across the abyssal and hadal transition zone, particularly over multiple trenches. Here, scavenging Amphipoda were collected from three trenches in the South Pacific Ocean at bathyal to hadal depths. Diversity and community structure were examined from stations within the Kermadec Trench (1490–9908 m) and New Hebrides Trench (2000–6948 m) and additional data were included from the South Fiji Basin (4000 m) and Peru-Chile Trench (4602–8074 m). The hadal community structure of the Kermadec and New Hebrides trenches were distinct from the surrounding abyssal and bathyal depths and correlated to hydrostatic pressure and POC flux. Low POC flux in the New Hebrides Trench and South Fiji Basin best explained the dissimilarity in abyssal community structure from those of the disparate Kermadec and Peru-Chile trenches. POC flux also best explained patterns in hadal community structure with the Kermadec and New Hebrides Trench communities showing greater similarity to each other than to the eutrophic Peru-Chile Trench. Hydrostatic pressure was the strongest driver of intra-trench assemblage composition in all trench environments. A unimodal pattern of species diversity, peaking between 4000 and 5000 m, was best explained by hydrostatic pressure and temperature.

Here we provide the first record of the ‘supergiant’ amphipod Alicella gigantea Chevreux, 1899 (Alicellidae) from the Southern Hemisphere, and extend the known bathymetric range by over 1000 m to 7000 m. An estimated nine individuals were observed across 1500 photographs taken in situ by baited camera at 6979 m in the Kermadec Trench, SW Pacific Ocean. Nine specimens, ranging in length from 102 to 290 mm were recovered by baited trap at depths of 6265 m and 7000 m. Mitochondrial and nuclear DNA sequences obtained indicate a cosmopolitan distribution for the species. Data and observations from the study are used to discuss the reason for gigantism in this species, and its apparently disjunct geographical distribution.

The ability to inhibit inappropriate responses is central to cognitive control, but whether the same brain mechanisms mediate inhibition across different tasks is not known. We present evidence for a common set of frontal and parietal regions engaged in response inhibition across three tasks: a go/no-go task, a flanker task, and a stimulus-response compatibility task. Regions included bilateral anterior insula/frontal operculum and anterior prefrontal, right dorsolateral and premotor, and parietal cortices. Insula activity was positively correlated with interference costs in behavioral performance in each task. Principal components analysis showed a coherent pattern of individual differences in these regions that was also positively correlated with performance in all three tasks. However, correlations among tasks were low, for both brain activity and performance. We suggest that common interference detection and/or resolution mechanisms are engaged across tasks, and that inter-task correlations in behavioral performance are low because they conflate measurements of common mechanisms with measurements of individual biases unique to each task.

Is there a single executive process or are there multiple executive processes that work together towards the same goal in some task? In these experiments, we use counter switching and response inhibition tasks to examine the neural underpinnings of two cognitive processes that have often been identified as potential executive processes: the switching of attention between tasks, and the resolution of interference between competing task responses. Using functional magnetic resonance imaging (fMRI), for both event-related and blocked design tasks, we find evidence for common neural areas across both tasks in bilateral parietal cortex (BA 40), left dorsolateral prefrontal cortex (DLPFC; BA 9), premotor cortex (BA 6) and medial frontal cortex (BA 6/32). However, we also find areas preferentially involved in the switching of attention between mental counts (BA 7, BA 18) and the inhibition of a prepotent motor response (BA 6, BA 10), respectively. These findings provide evidence for the separability of cognitive processes underlying executive control.

Solid phase peptide library screening followed by extension of a lead recognition element for binding to a dsDNA sequence (NF binding site of IL6) using solution phase screening, delivered a new DNA binding peptide, Ac-Arg-Ual-Sar-Chi-Chi-Tal-Arg-CONH 2 . In the present research, the contribution of the different amino acid side chains to the binding strength of the peptide to dsDNA was investigated using an ethidium bromide displacement test. Based on these results, the lead structure was optimized by deconvolution. Eight new unnatural amino acids were evaluated at two positions of the heptapeptide replacing the Ual-Sar fragment. The strongest dsDNA binding was observed using {[(3-chlorophenyl)methyl]amino}acetic acid (Cbg) and β-cyclohexyl-l-alanine (Cha) respectively, at those two positions. A 10-fold increase in affinity compared to the Ual-Sar sequence was obtained. Further enhancement of dsDNA binding was obtained with hybrid molecules linking the newly developed peptide fragment to an acridine derivative with a flexible spacer. This resulted in ligands with affinities in the μM range for the dsDNA target ( K d of 2.1×10 −6 M). DNase I footprinting with the newly developed oligopeptide motifs showed the presence of a pronounced pyrimidine specificity, while conjugation to an intercalator seems to redirect the interaction to mixed sequences. This way, new unnatural oligopeptide motifs and hybrid molecules have been developed endowed with different sequence selectivities. The results demonstrate that the unnatural peptide library approach combined with subsequent modification of selected amino acid positions, is very suited for the discovery of novel sequence-specific dsDNA binding ligands.

In the biosynthesis of proteins, each amino acid passes from the aminoacyl adenylate to become an amino acid ester and finally a 2′ (3′) peptidyl ester of the AMP residue at the end of a tRNA. Consequently, the chemistry of protein synthesis is the chemistry of aminoacyl and peptidyl AMP. Our data has revealed properties of 5′-AMP and its esters which should allow the preferential catalytic synthesis of l -amino acid peptides via a bis(2′, 3′-aminoacyl) ester intermediate. Results in this paper concern one step in the proposed process and show that preexisting Ac- l -Phe monoester reacts about 2.5-times faster to form diester than preexisting Ac- d -Phe monoester.

Deuterium ( 2 H) NMR was used to investigate the interaction of L-Phenylalanine [with aromatic protons replaced by deuterons (Phe-D 5 )], with 5′-AMP and polyadenylic acid (poly A). A considerable change in line width of the aromatic deuteron signals of Phe was observed. These data were plotted using a Scatchard-type equation, and yielded apparent binding constants for L-Phe to 5′-AMP and poly A of 7 and 11 M −1 , respectively. Future applications of 2 H-NMR in the study of nucleic acid-protein interactions are discussed.

This paper summarizes our views and data relative to the coevolution of the genetic code and the process of protein synthesis. The component aminoacyl transfer reactions were found to be spontaneous for the most part. However, formation of peptides from phenylalanyl-AMP-ester did not occur, and this observation raises some question as to the mechanism of peptide bond formation in the contemporary. Exploration of properties of amino acids and nucleotides show correlations between both the hydrophobicity and the hydrophilicity of amino acids and their anticodon nucleotides. Furthermore, work with thermal proteinoids shows a possible affinity of amino acids for anticodon nucleotides. We suggest, as a result of these observations, that a primitive protein synthesis system may have existed in which classes of amino acids were activated by mononucleotide triphosphates (i.e., ATP would activate all hydrophobic amino acids, UTP would activate charged hydrophilic amino acids, CTP uncharged hydrophilic amino acids and GTP those of intermediate hydrophobicity). In this model the nucleotidyl triphosphates simultaneously activate and adapt the amino acids. Subsequently, the nucleotide, carrying the amino acid, base pairs with a “messenger” RNA, organizing the amino acids for polymerization. An essential feature of the model is that the recognition step takes place before the “messenger” is present. The mononucleotides are thus envisioned as the simplest evolutionary precursors of tRNAs. Natural selection processes would have led to the evolution from 1/1 coding with mononucleotide adaptors to 3/1 coding via evolution of the tRNAs.

Histones and ribosomal proteins are basic proteins that participate in gene regulation and protein synthesis, respectively. How these proteins interact with nucleic acids is not yet clear, although specificities in these interactions have been observed. Study of the interaction of mononucleotides with basic polyamino acids is one approach to understanding such interactions. The results of studies with the mononucleotides can help elucidate the normal molecular processes in biological systems and also shed light on some effects of drugs, such as puromycin and tubericidin, that are nucleotide derivatives. A review of studies on the interaction of mononucleotides and basic polyamino acids such as polylysine and polyarginine is presented. In addition, a short review of the self-associative properties of mononucleotides is given. Studies of the mononucleotide-polyamino acid interaction have involved a wide variety of techniques including equilibrium dialysis, NMR, optical rotatory dispersion, circular dichroism, and precipitate analysis.

Studies have been made of the behaviour of a water film on the heated central rod of an annular test section carrying flowing steam at atmospheric pressure, the water having been introduced through a porous wall. The outer glass wall of the annulus was heated to prevent condensation and droplet deposition, and hence the inner rod surface was rendered clearly visible. The onset of nucleation within the film was demonstrated and the conditions for its initiation were determined and compared with theoretical predictions; in other experiments “burnout”, or “dry-out”, heat flux measurements were made and related to the measured residual film flow on the heated rod. Visual and photographic studies revealed a relatively stable condition of break-up of the climbing film, with rivulets around dried-out patches, before the burnout trip operated. The residual film flow rate at which dry patches appeared was very small indeed and the “burnout” phenomenon was clearly the result simply of total loss of water from the film by evaporation and entrainment; the local value of the heat flux at the site of the burnout was evidently of only secondary relevance. There was evidence that bubble nucleation in the film could contribute appreciably to the loss by entrainment at high heat fluxes.

N-Acetylglycyl adenylate anhydride has been shown to be readily converted in high yield to N-acetylglycyl imidazolide in the presence of excess imidazole at pH 7. The aminoacyl group can then be transferred from the imidazolide to become esters of mono- or polynucleotides. These observations suggest that histidine may be in the active site of the aminoacyl-tRNA synthetases, catalyzing the transfer of aminoacyl groups from the adenylate to tRNA.