Skeletal muscle adiposity is associated with serum lipid and lipoprotein levels in Afro‐Caribbean men

Objective: When compared with other ethnic groups, African ancestry individuals have lower triglycerides and higher High‐density lipoprotein cholesterol (HDL‐C) levels, although the mechanisms for these differences remain unclear. A comprehensive array of factors potentially related to fasting serum lipid and lipoprotein levels in African ancestry men was evaluated. Design and Methods: Men (1,821) underwent dual‐energy X‐ray absorptiometry measures of total body fat and quantitative computed tomography assessments of calf skeletal muscle adiposity [subcutaneous and intermuscular adipose tissue (AT), and muscle density as a measure of intra‐muscular AT]. Results: Multivariable linear regression analysis identified age (?), total body fat (+), subcutaneous AT (?), fasting glucose (+), fasting insulin (+), diastolic blood pressure (+), and non‐African ancestry (+) as independent correlates of triglycerides (all P < 0.05). Total body fat (+), intra‐muscular AT (?), and diastolic blood pressure (+) were independent correlates of Low‐density lipoprotein cholesterol (LDL‐C) (all P < 0.001). Age (+), waist circumference (?), fasting insulin (?), physical activity (+), and alcohol intake (+) were independent correlates of HDL‐C (all P < 0.05). Conclusions: A novel relationship between skeletal muscle adiposity and serum lipid and lipoprotein levels in African ancestry men, independent of total and central adiposity was illuminated. In African ancestry populations, genetic factors are likely a significant determinant of triglycerides levels.     

Identification of a Functional Connectome for Long-Term Fear Memory in Mice

Long-term memories are thought to depend upon the coordinated activation of a broad network of cortical and subcortical brain regions. However, the distributed nature of this representation has made it challenging to define the neural elements of the memory trace, and lesion and electrophysiological approaches provide only a narrow window into what is appreciated a much more global network. Here we used a global mapping approach to identify networks of brain regions activated following recall of long-term fear memories in mice. Analysis of Fos expression across 84 brain regions allowed us to identify regions that were co-active following memory recall. These analyses revealed that the functional organization of long-term fear memories depends on memory age and is altered in mutant mice that exhibit premature forgetting. Most importantly, these analyses indicate that long-term memory recall engages a network that has a distinct thalamic-hippocampal-cortical signature. This network is concurrently integrated and segregated and therefore has small-world properties, and contains hub-like regions in the prefrontal cortex and thalamus that may play privileged roles in memory expression.     

Phylogenetic relationships of a Patagonian frog radiation,the Alsodes + Eupsophus clade (Anura: Alsodidae), with comments on the supposed paraphyly of Eupsophus

The frog clade composed of the alsodid genera Alsodes + Eupsophus is the most species‐rich of the Patagonian endemic frog clades, including nearly 31 of the slightly more than 50 species of that region. The biology of this group of frogs is poorly known, its taxonomy quite complex (particularly Alsodes), and its diversity in chromosome number striking when compared with other frogs (collectively, there are species having 2n = 22, 2n = 26, 2n = 28, 2n = 30 or 2n = 34). We present a phylogenetic analysis of this Patagonian frog clade based on mitochondrial and nuclear gene sequences. We sequenced five mitochondrial genes (cytochrome b, cytochrome oxidase I, 12S, 16S, NADH dehydrogenase subunit 1) with three intervening tRNAs, and fragments of three nuclear genes (seven in absentia homolog 1, rhodopsin exon 1, RAG‐1), for a maximum of 6510 bp for multiple specimens from 26 of the 31 species. We recovered Eupsophus as polyphyletic, with E. antartandicus, E. sylvaticus, and E. taeniatus in Batrachylidae, in accordance with most previous hypotheses. Based on this result, we transfer E. antartandicus and E. taeniatus back to Batrachyla, and E. sylvaticus to Hylorina (resurrected from the synonymy of Eupsophus), remediating the paraphyly of Eupsophus. Our results strongly corroborate the monophyly of Alsodes + Eupsophus (sensu stricto), the individual monophyly of these genera, and the monophyly of the species groups of Eupsophus. They also show the non‐monophyly of all non‐monotypic species groups of Alsodes proposed in the past. Our results expose several taxonomic problems particularly in Alsodes, and to a lesser extent in Eupsophus. This phylogenetic context suggests a rich evolutionary history of karyotypic diversification in the clade, in part corroborating previous hypotheses. In Alsodes, we predict three independent transformations of chromosome number from the plesiomorphic 2n = 26. All these, strikingly, involve increments or reductions of pairs of haploid chromosomes. Finally, the phylogenetic pattern recovered for Alsodes and Eupsophus suggests a trans‐Andean origin and diversification of the group, with multiple, independent ingressions over cis‐Andean regions.     

Structure and developmental expression of the chicken NGF receptor

The nucleotide and deduced amino acid sequence of a cDNA clone of the chicken NGF receptor (NGFR) is reported and is compared with sequences of mammalian NGF receptors. A model is presented in which monodentate or bidentate binding of NGF dimers to repeated cysteine-rich sequence elements of the receptor yields low- or high-affinity NGF binding, respectively. In situ hybridization is used to characterize expression of NGFR in developing chick from 40 hr to 10 days of embryogenesis. NGFR mRNA expression is detected in premigratory neural crest cells, in epibranchial placode cells, and in all sensory, sympathetic and parasympathetic derivatives of these structures. In the embryonic CNS, NGFR mRNA is detected in the mantle zone but not the periventricular germinal zone throughout most of the neural tube. By Embryonic Day 8, NGFR mRNA is detected in a substantial fraction of cells in every brain region, with highest levels present in developing motor neurons. NGFR mRNA also is transiently expressed in many mesenchymal cell populations including cells in branchial arch, sclerotome, muscle anlagen, and feather follicles. The functional significance of wide-spread embryonic expression of the NGF receptor is discussed.     

Density-dependent processes in the life history of fishes: evidence from laboratory populations of zebrafish Danio rerio

Population regulation is fundamental to the long-term persistence of populations and their responses to harvesting, habitat modification, and exposure to toxic chemicals. In fish and other organisms with complex life histories, regulation may involve density dependence in different life-stages and vital rates. We studied density dependence in body growth and mortality through the life-cycle of laboratory populations of zebrafish Danio rerio. When feed input was held constant at population-level (leading to resource limitation), body growth was strongly density-dependent in the late juvenile and adult phases of the life-cycle. Density dependence in mortality was strong during the early juvenile phase but declined thereafter and virtually ceased prior to maturation. Provision of feed in proportion to individual requirements (easing resource limitation) removed density dependence in growth and substantially reduced density dependence in mortality, thus indicating that 'bottom-up' effects act on growth as well as mortality, but most strongly on growth. Both growth and mortality played an important role in population regulation, with density-dependent growth having the greater impact on population biomass while mortality had the greatest impact on numbers. We demonstrate a clear ontogenic pattern of change in density-dependent processes within populations of a very small (maximum length 5 mm) fish, maintained in constant homogeneous laboratory conditions. The patterns are consistent with those distilled from studies on wild fish populations, indicating the presence of broad ontogenic patterns in density-dependent processes that are invariant to maximum body size and hold in homogeneous laboratory, as well as complex natural environments.     

A selenium-induced peroxidation of glutathione in algae

Two unicellular marine algae cultured in media containing sodium selenite were examined for glutathione peroxidase activity. The 400 g supernatant from disrupted cells of both the green alga Dunaliella primolecta and the red alga Porphyridium cruentum were able to enhance both the H₂O₂ and the tert-butyl hydroperoxide dependent oxidation of glutathione. The glutathione peroxidation activity of D. primolecta was reduced only slightly by heating the 400 g supernatant, a 30% decrease in the rate with H₂O₂ and 10% decrease in the rate with t-BuOOH being observed. Heating caused the H₂O₂ dependent activity in P. cruentum to be reduced by only 30%, but the activity with t-BuOOH was reduced by 90%. Freezing decreased the t-BuOOH dependent activity of P. cruentum by 90%, but did not lower the t-BuOOH dependent activity of D. primolecta or the H₂O₂ dependent activity of either alga. It was concluded that the heat and cold stable, glutathione peroxidation was non-enzymatic in nature. A variety of small molecules (ascorbate, Cu(NO₃)₂, selenocystine, dimethyldiselenide and selenomethionine) were shown to be able to enhance the hydroperoxide dependent oxidation of glutathione in the assay system employed in this study. Such compounds could be responsible for the activity observed in algae. The heat and cold labile t-BuOOH reductase activity of P. cruentumwas possibly enzymatic, but was not attributable to the presence of glutathione-S-transferase. Both algae, when cultured in the presence of added selenite, displayed an approximate doubling of the non-enzymatic H₂O₂ and t-BuOOH dependent glutathione oxidase activities. The heat and cold labile t-BuOOH reductase activity of P. cruentum was unaltered when the alga was grown in the presence of added selenite. These observations are consistent with the hypothesis that selenium compounds present in the algae are responsible for the selenium induced glutathione peroxidation.     

Genetic markers on BTA14 predictive for residual feed intake in beef steers and their effects on carcass and meat quality traits

With the high cost of feed for animal production, genetic selection for animals that metabolize feed more efficiently could result in substantial cost savings for cattle producers. The purpose of this study was to identify DNA markers predictive for differences among cattle for traits associated with feed efficiency. Crossbred steers were fed a high‐corn diet for 140 days and average daily feed intake (ADFI), average daily gain (ADG), and residual feed intake (RFI) phenotypes were obtained. A region on chromosome 14 was previously associated with RFI in this population of animals. To develop markers with the highest utility for predicting an animal's genetic potential for RFI, we genotyped additional markers within this chromosomal region. These polymorphisms were genotyped on the same animals (n = 1066) and tested for association with ADFI, ADG and RFI. Six markers within this region were associated with RFI (P ≤ 0.05). After conservative correction for multiple testing, one marker at 25.09 Mb remained significant (P = 0.02) and is responsible for 3.6% of the RFI phenotypic variation in this population of animals. Several of these markers were also significant for ADG, although none were significant after correction. Marker alleles with positive effects on ADG corresponded to lower RFI, suggesting an effect increasing growth without increasing feed intake. All markers were also assessed for their effects on meat quality and carcass traits. All of the markers associated with RFI were associated with adjusted fat thickness (AFT, P ≤ 0.009) and three were also associated with hot carcass weight (HCW, P ≤ 0.003). Marker alleles associated with lower RFI were also associated with reduced AFT, and if they were associated for HCW, the effect was an increase in weight. These markers may be useful as prediction tools for animals that utilize feed more efficiently; however, validation with additional populations of cattle is required.     

Disentangling the relative importance of climate,size and competition on tree growth in Iberian forests: implications for forest management under global change

Most large‐scale multispecies studies of tree growth have been conducted in tropical and cool temperate forests, whereas Mediterranean water‐limited ecosystems have received much less attention. This limits our understanding of how growth of coexisting tree species varies along environmental gradients in these forests, and the implications for species interactions and community assembly under current and future climatic conditions. Here, we quantify the absolute effect and relative importance of climate, tree size and competition as determinants of tree growth patterns in Iberian forests, and explore interspecific differences in the two components of competitive ability (competitive response and effect) along climatic and size gradients. Spatially explicit neighborhood models were developed to predict tree growth for the 15 most abundant Iberian tree species using permanent‐plot data from the Spanish Second and Third National Forest Inventory (IFN). Our neighborhood analyses showed a climatic and size effect on tree growth, but also revealed that competition from neighbors has a comparatively much larger impact on growth in Iberian forests. Moreover, the sensitivity to competition (i.e. competitive response) of target trees varied markedly along climatic gradients causing significant rank reversals in species performance, particularly under xeric conditions. We also found compelling evidence for strong species‐specific competitive effects in these forests. Altogether, these results constitute critical new information which not only furthers our understanding of important theoretical questions about the assembly of Mediterranean forests, but will also be of help in developing new guidelines for adapting forests in this climatic boundary to global change. If we consider the climatic gradients of this study as a surrogate for future climatic conditions, then we should expect absolute growth rates to decrease and sensitivity to competition to increase in most forests of the Iberian Peninsula (in all but the northern Atlantic forests), making these management considerations even more important in the future.     

Site Mapping and Characterization of O-Glycan Structures on α-Dystroglycan Isolated from Rabbit Skeletal Muscle

The main extracellular matrix binding component of the dystrophin-glycoprotein complex, α-dystroglycan (α-DG), which was originally isolated from rabbit skeletal muscle, is an extensively O-glycosylated protein. Previous studies have shown α-DG to be modified by both O-GalNAc- and O-mannose-initiated glycan structures. O-Mannosylation, which accounts for up to 30% of the reported O-linked structures in certain tissues, has been rarely observed on mammalian proteins. Mutations in multiple genes encoding defined or putative glycosyltransferases involved in O-mannosylation are causal for various forms of congenital muscular dystrophy. Here, we explore the glycosylation of purified rabbit skeletal muscle α-DG in detail. Using tandem mass spectrometry approaches, we identify 4 O-mannose-initiated and 17 O-GalNAc-initiated structures on α-DG isolated from rabbit skeletal muscle. Additionally, we demonstrate the use of tandem mass spectrometry-based workflows to directly analyze glycopeptides generated from the purified protein. By combining glycomics and tandem mass spectrometry analysis of 91 glycopeptides from α-DG, we were able to assign 21 different residues as being modified by O-glycosylation with differing degrees of microheterogeneity; 9 sites of O-mannosylation and 14 sites of O-GalNAcylation were observed with only two sites definitively exhibiting occupancy by either type of glycan. The distribution of identified sites of O-mannosylation suggests a limited role for local primary sequence in dictating sites of attachment.     

Sodium—A Functional Plant Nutrient

Plant scientists usually classify plant mineral nutrients based on the concept of “essentiality” defined by Arnon and Stout as those elements necessary to complete the life cycle of a plant. Certain other elements such as Na have a ubiquitous presence in soils and waters and are widely taken up and utilized by plants, but are not considered as plant nutrients because they do not meet the strict definition of “essentiality.” Sodium has a very specific function in the concentration of carbon dioxide in a limited number of C₄ plants and thus is essential to these plants, but this in itself is insufficient to generalize that Na is essential for higher plants. The unique set of roles that Na can play in plant metabolism suggests that the basic concept of what comprises a plant nutrient should be reexamined. We contend that the class of plant mineral nutrients should be comprised not only of those elements necessary for completing the life cycle, but also those elements which promote maximal biomass yield and/or which reduce the requirement (critical level) of an essential element. We suggest that nutrients functioning in this latter manner should be termed “functional nutrients.” Thus plant mineral nutrients would be comprised of two major groups, “essential nutrients” and “functional nutrients.” We present an array of evidence and arguments to support the classification of Na as a “functional nutrient,” including its requirement for maximal biomass growth for many plants and its demonstrated ability to replace K in a number of ways, such as being an osmoticium for cell enlargement and as an accompanying cation for long-distance transport. Although in this paper we have only attempted to make the case for Na being a “functional nutrient,” other elements such as Si and Se may also confirm to the proposed category of “functional nutrients.”