Redefining the requirement for total sulfur amino acids in the diet of barramundi (Lates calcarifer) including assessment of the cystine replacement value

This study was designed to confirm a previous estimate of the methionine (Met) and total sulfur amino acid (TSAA) requirement of juvenile barramundi (Lates calcarifer) (Coloso et al., 1999) with a view for further study. Triplicate groups of fish (initial weight: 18.3 g ± 1.5 g) were fed diets with graded levels of dietary Met (7.2–12.8 g kg−1 DM), centred around a previously reported requirement, and a constant dietary cystine (Cys) inclusion (5.9 g kg−1 DM) over a 42 day period. At the termination of the experiment, a significant linear increase (p<0.001) in %BW gain was observed in response to increasing dietary methionine, with no plateau in growth, suggesting the previous estimate of requirement may have been inadequate. A second experiment was designed to re-evaluate the Met/TSAA requirement in which a broader range of methionine inclusion levels were assessed (8.6–21.4 g kg−1 diet DM Met). Triplicate groups of fish (initial weight: 36.4 g ± 8.3 g) were fed the diets for a period of 49 days. A plateau and subsequent depression in growth, as well as significant (p<0.05) effects of dietary Met inclusion on %BW gain, feed conversion ratio (FCR) and protein retention efficiency (PRE) were observed at the conclusion of this experiment. The best fitting of nine nutrient response models, the Compartmental Model (R2=0.71), predicted a requirement for Met of between 10.5 (95% of maximum response) and 13.6 g kg−1 (99% of maximum response) in a diet with 592 g kg−1 CP and 6.6 g kg−1 Cys (17.1–20.2 g kg−1 TSAA; 1.8–2.3% CP Met +1.1% CP Cys). This TSAA requirement is equivalent to 43–51% of the lysine content of the diets. The applicability of this mode of expression and its relation to the ideal protein concept is discussed as is the application of different response models to the data. The impact of dietary Met:Cys ratio was also investigated with results suggesting at least 40% of dietary Met can be replaced with Cys without significantly affecting animal performance. It was concluded that disparity in the estimates of Met and TSAA requirement between this study and that of Coloso et al. (1999) was likely the result of a combination of model choice, experimental design and mode of expression of the requirements

Metal-only Lewis pairs between group 10 metals and Tl(I) or Ag(I): insights into the electronic consequences of Z-type ligand binding†

Complexes bearing electron rich transition metal centers, especially those displaying coordinative unsaturation, are well-suited to form reverse-dative σ-interactions with Lewis acids. Herein we demonstrate the generality of zerovalent, group 10 m-terphenyl isocyanide complexes to form reverse-dative σ-interactions to Tl(I) and Ag(I) centers. Structural and spectroscopic investigations of these metal-only Lewis pairs (MOLPs) has allowed insight into the electronic consequences of Lewis-acid ligation within the primary coordination sphere of a transition metal center. Treatment of the bis-isocyanide complex, Pt(CNArDipp2)2 (ArDipp2 = 2,6-(2,6-(i-Pr)2C6H3)2C6H3) with TlOTf (OTf = [O3SCF3]−) yields the Pt/Tl MOLP [TlPt(CNArDipp2)2]OTf (1). 1H NMR and IR spectroscopic studies on 1, and its Pd congener [TlPd(CNArDipp2)2]OTf (2), demonstrate that the M → Tl interaction is labile in solution. However, treatment of complexes 1 and 2 with Na[BArF4] (ArF = 3,5-(CF3)2C6H3) produces [TlPt(CNArDipp2)2]BArF4 (3) and [TlPd(CNArDipp2)2]BArF4 (4), in which Tl(I) binding is shown to be static by IR spectroscopy and, in the case of 3, 195Pt NMR spectroscopy as well. This result provides strong evidence that the M → Tl linkages can be attributed primarily to σ-donation from the group 10 metal to Tl, as loss of ionic stabilization of Tl by the triflate anion is compensated for by increasing the degree of M → Tl σ-donation. In addition, X-ray Absorption Near-Edge Spectroscopy (XANES) on the Pd/Tl and Ni/Tl MOLPs, [TlPd(CNArDipp2)2]OTf (2) and [TlNi(CNArMes2)3]OTf, respectively, is used to illustrate that the formation of a reverse-dative σ-interaction with Tl(I) does not alter the spectroscopic oxidation state of the group 10 metal. Also reported is the ability of M(CNArDipp2)2 (M = Pt, Pd) to form MOLPs with Ag(I), yielding the complexes [AgM(CNArDipp2)2]OTf (5, M = Pt; 6, M = Pd). As was determined for the Tl-containing MOLPs 1–4, it is shown that the spectroscopic oxidation states of the group 10 metal in 5 and 6 are essentially unchanged compared to the zerovalent precursors M(CNArDipp2)2. However, in the case of 5 and 6, the formation of a dative M → Ag σ-bonding interaction facilitates the binding of Lewis bases to the group 10 metal trans to Ag, illustrating the potential of acceptor fragments to open up new coordination sites on transition metal complexes without formal, two-electron oxidation

An Execution Model for Fine-Grained Parallelism in Ada

20th International Conference on Reliable Software Technologies - Ada-Europe 2015 (Ada-Europe 2015), 25 to 29, Jun, 2015. Madrid, Spain. Best Paper Award.This paper extends the authors earlier proposal for providing Ada with support for fine-grained parallelism with an execution model based on the concept of abstract executors, detailing the progress guarantees that these executors must provide and how these can be assured even in the presence of potentially blocking operations. The paper also describes how this execution model can be applied to real-time systems

Overview of the Tevatron Collider Complex: Goals, Operations and Performance

For more than two decades the Tevatron proton-antiproton collider was the centerpiece of the world's high energy physics program. The collider was arguably one of the most complex research instruments ever to reach the operation stage and is widely recognized for numerous physics discoveries and for many technological breakthroughs. In this article we outline the historical background that led to the construction of the Tevatron Collider, the strategy applied to evolution of performance goals over the Tevatron's operational history, and briefly describe operations of each accelerator in the chain and achieved performance.Comment: Includes modifications suggested by reviewer

Postprandial plasma free amino acid profile and hepatic gene expression in juvenile barramundi (Lates calcarifer) is more responsive to feed consumption than to dietary methionine inclusion

The effects of dietary methionine (Met) supply on the postprandial pattern of plasma free amino acids and the differential expression of several genes associated with a number of sulfur amino acid and protein turnover pathways in the liver of juvenile barramundi (Lates calcarifer) was investigated. At the conclusion of a 49-day growth trial assessing the requirement for dietary Met, three treatments were selected (with deficient (DEF; 8.6 g kg−1), adequate (ADQ; 14.9 g kg−1) and excessive (EXC; 21.4 g kg−1)) levels of dietary Met, based on their respective growth responses. A peak occurred in plasma free Met at 2 h post-feeding in fish fed the DEF and ADQ diets and at 4 h post-feeding in fish in the EXC treatment. Liver samples collected at these timepoints, as well as those taken as a pre-feeding control, were analyzed for expression of genes involved in Met turnover (CGL, MAT-1, MAT-2a) and taurine biosynthetic pathways (CSAD, ADO, CDO), target of rapamycin inhibition (Redd-1), the somatotropic axis (GHR-II, IGFI, IGF-II) and protein turnover pathways (MUL-1, ZFAND-5). Markers of sulfur amino acid turnover were more significantly affected by time after feeding than by dietary Met level, suggesting production of these enzymes may be primarily regulated by the consumption of feed or protein, rather than by the dietary composition. Further, metabolised Met appeared likely to have been directed through S-Adenosylmethionine (SAM) dependent pathways, rather than converted to Cys, which may have contributed to the observed growth response. Both genes influencing the conversion of Met to SAM appear to be active at this lifestage in barramundi. Previously described markers of proteolytic pathways appear to be conserved in this species and we have confirmed that ZFAND-5 is a reliable biomarker of this process in barramundi. A number of important genes were investigated for the first time in this species and shown to be nutritionally regulated

Harnessing cross-species alignment to discover SNPs and generate a draft genome sequence of a bighorn sheep (Ovis canadensis)

Background: Whole genome sequences (WGS) have proliferated as sequencing technology continues to improve and costs decline. While many WGS of model or domestic organisms have been produced, a growing number of non-model species are also being sequenced. In the absence of a reference, construction of a genome sequence necessitates de novo assembly which may be beyond the ability of many labs due to the large volumes of raw sequence data and extensive bioinformatics required. In contrast, the presence of a reference WGS allows for alignment which is more tractable than assembly. Recent work has highlighted that the reference need not come from the same species, potentially enabling a wide array of species WGS to be constructed using cross-species alignment. Here we report on the creation a draft WGS from a single bighorn sheep (Ovis canadensis) using alignment to the closely related domestic sheep (Ovis aries). Results: Two sequencing libraries on SOLiD platforms yielded over 865 million reads, and combined alignment to the domestic sheep reference resulted in a nearly complete sequence (95% coverage of the reference) at an average of 12x read depth (104 SD). From this we discovered over 15 million variants and annotated them relative to the domestic sheep reference. We then conducted an enrichment analysis of those SNPs showing fixed differences between the reference and sequenced individual and found significant differences in a number of gene ontology (GO) terms, including those associated with reproduction, muscle properties, and bone deposition. Conclusion: Our results demonstrate that cross-species alignment enables the creation of novel WGS for non-model organisms. The bighorn sheep WGS will provide a resource for future resequencing studies or comparative genomics