Relationship between hydraulic conductance and citrus dwarfing by the Flying Dragon rootstock (Poncirus trifoliata L. Raft var. monstruosa)

This work studied the hydraulic characteristics and physiological behavior of two trifoliate orange (Poncirus trifoliata L. Raft) varieties—Flying Dragon (FD) and Rubidoux (RT)—with contrasting size-controlling potential when used as rootstocks for citrus trees. Thus, Valencia orange scions growing on RT root system develop about 40 % more biomass than scions on FD. The anatomical study of xylem root tissue of both rootstocks showed that the number of vessels per cross-sectional area in RT almost doubled that found in FD, whereas diameter distribution did not vary significantly. Hydraulic resistance determined in rootstocks, and bud union segments were, respectively, 2- and 3.4-fold higher in trees on FD than in trees on RT. Root systems accounted for 46.5 and 55.2 % of whole-plant hydraulic resistance, whereas bud union segments represented 7.5 and 14.6 % of this parameter, the dwarfing rootstock (FD) having the highest values. Reduced hydraulic conductance in plants on FD rootstock diminished water potential in high evaporative demand periods, causing a reduction in stomatal conductance with respect to plants on RT. This leads to lower net photosynthetic CO₂ assimilation, which may affect biomass production. Translocation of ¹³C-labeled photoassimilates from leaves to roots was lower in plants on FD than in plants on RT, indicating that in the dwarfing rootstock (FD) there may be a vascular resistance to sucrose transport at the budding union level. Findings show that reduced hydraulic conductance may be the main cause of rootstock-induced dwarfing in citrus grafted onto FD.     

Formation of S-(carboxymethyl)-cysteine in rat liver mitochondrial proteins: effects of caloric and methionine restriction

Maillard reaction contributes to the chemical modification and cross-linking of proteins. This process plays a significant role in the aging process and determination of animal longevity. Oxidative conditions promote the Maillard reaction. Mitochondria are the primary site of oxidants due to the reactive molecular species production. Mitochondrial proteome cysteine residues are targets of oxidative attack due to their specific chemistry and localization. Their chemical, non-enzymatic modification leads to dysfunctional proteins, which entail cellular senescence and organismal aging. Previous studies have consistently shown that caloric and methionine restrictions, nutritional interventions that increase longevity, decrease the rate of mitochondrial oxidant production and the physiological steady-state levels of markers of oxidative damage to macromolecules. In this scenario, we have detected S-(carboxymethyl)-cysteine (CMC) as a new irreversible chemical modification in mitochondrial proteins. CMC content in mitochondrial proteins significantly correlated with that of the lysine-derived analog N ^ε-(carboxymethyl)-lysine. The concentration of CMC is, however, one order of magnitude lower compared with CML likely due in part to the lower content of cysteine with respect to lysine of the mitochondrial proteome. CMC concentrations decreases in liver mitochondrial proteins of rats subjected to 8.5 and 25 % caloric restriction, as well as in 40 and 80 % methionine restriction. This is associated with a concomitant and significant increase in the protein content of sulfhydryl groups. Data presented here evidence that CMC, a marker of Cys-AGE formation, could be candidate as a biomarker of mitochondrial damage during aging.     

Actin acting at the Golgi

The organization, assembly and remodeling of the actin cytoskeleton provide force and tracks for a variety of (endo)membrane-associated events such as membrane trafficking. This review illustrates in different cellular models how actin and many of its numerous binding and regulatory proteins (actin and co-workers) participate in the structural organization of the Golgi apparatus and in trafficking-associated processes such as sorting, biogenesis and motion of Golgi-derived transport carriers.     

The carbohydrate-binding module of Fragaria × ananassa expansin 2 (CBM-FaExp2) binds to cell wall polysaccharides and decreases cell wall enzyme activities “in vitro”

A putative carbohydrate binding module (CBM) from strawberry (Fragaria × ananassa Duch.) expansin 2 (CBM-FaExp2) was cloned and the encoding protein was over-expressed in Escherichia coli and purified in order to evaluate its capacity to bind different cell wall polysaccharides “in vitro”. The protein CBM-FaExp2 bound to microcrystalline cellulose, xylan and pectin with different affinities (K_ad = 33.6 ± 0.44 mL g^?1, K_ad = 11.37 ± 0.87 mL g^?1, K_ad = 10.4 ± 0.19 mL g^?1, respectively). According to “in vitro” enzyme assays, this CBM is able to decrease the activity of cell wall degrading enzymes such as polygalacturonase, endo-glucanase, pectinase and xylanase, probably because the binding of CBM-FaExp2 to the different substrates interferes with enzyme activity. The results suggest that expansins would bind not only cellulose but also a wide range of cell wall polymers.     

Introduction of sheep meat breeds in extensive systems: Lamb carcass characteristics

Genotype effects on lamb carcass traits were investigated in a 4-year study aimed at assessing potential benefits from introducing meat breeds into the wool-oriented extensive sheep systems of northeastern Patagonia, Argentina. Five ram [Corriedale: CO; Border Leicester: BL; Île de France: IF; Texel: TX; and synthetic CRIII (25% Merino, 37.5% IF, 37.5% TX)] and 5 dam (CO; synthetic CRIII; BLCO: BL × CO; IFCO: IF × CO; and TXCO: TX × CO) genotypes were represented in the study. Data were collected from 436 male lambs of 9 genotypes (CO × CO, BL × CO, IF × CO, TX × CO, CRIII × CO, CRIII × BLCO, CRIII × IFCO, CRIII × TXCO, and CRIII × CRIII). Hot carcass weights and dressing yields were determined after slaughtering. Carcasses were given conformation and subcutaneous fat scores using the EUROP system [scale varying from E (best) to P (poorest) for conformation, and from 1 (lean) to 5 (overfat) for subcutaneous fat]. Linear measurements of carcass length and width were recorded and carcass compactness indices were calculated from those. Purebred CO acted as a standard for comparisons. On a constant liveweight basis, genotypes CRIII × IFCO and CRIII × CRIII presented higher (P < 0.05) carcass weight and dressing yield than CO × CO and BL × CO. Crossbred and synthetic genotypes showed higher (P < 0.05) carcass width than CO × CO. With the exception of BL × CO the remaining genotypes showed higher (P < 0.05) carcass width/length ratio than CO × CO. The probability that carcasses of crossbred and synthetic lambs presented better conformation than CO × CO was higher than 84%. Carcasses of CRIII × IFCO lambs were given the best conformation scores. The probability that BL × CO carcasses presented higher subcutaneous fat than the remaining genotypes exceeded 79%. Our results indicate significant improvements in carcass conformation arising from crossing. Sheep farmers in extensive systems could take advantage of the higher fatness of BL crossbred lambs to produce light carcasses with adequate fat cover, a crucial industry requirement. Terminal crossbreeding with Île de France, Texel, and CRIII rams could be implemented to improve carcass conformation thus matching market demand for heavy carcasses with limited fat content. Second cross schemes did not improve carcass commercial traits over the best terminal cross or the synthetic CRIII breed.     

Automatically Generated Algorithms for the Vertex Coloring Problem

The vertex coloring problem is a classical problem in combinatorial optimization that consists of assigning a color to each vertex of a graph such that no adjacent vertices share the same color, minimizing the number of colors used. Despite the various practical applications that exist for this problem, its NP-hardness still represents a computational challenge. Some of the best computational results obtained for this problem are consequences of hybridizing the various known heuristics. Automatically revising the space constituted by combining these techniques to find the most adequate combination has received less attention. In this paper, we propose exploring the heuristics space for the vertex coloring problem using evolutionary algorithms. We automatically generate three new algorithms by combining elementary heuristics. To evaluate the new algorithms, a computational experiment was performed that allowed comparing them numerically with existing heuristics. The obtained algorithms present an average 29.97% relative error, while four other heuristics selected from the literature present a 59.73% error, considering 29 of the more difficult instances in the DIMACS benchmark.     

NOA36 Protein Contains a Highly Conserved Nucleolar Localization Signal Capable of Directing Functional Proteins to the Nucleolus,in Mammalian Cells

NOA36/ZNF330 is an evolutionarily well-preserved protein present in the nucleolus and mitochondria of mammalian cells. We have previously reported that the pro-apoptotic activity of this protein is mediated by a characteristic cysteine-rich domain. We now demonstrate that the nucleolar localization of NOA36 is due to a highly-conserved nucleolar localization signal (NoLS) present in residues 1–33. This NoLS is a sequence containing three clusters of two or three basic amino acids. We fused the amino terminal of NOA36 to eGFP in order to characterize this putative NoLS. We show that a cluster of three lysine residues at positions 3 to 5 within this sequence is critical for the nucleolar localization. We also demonstrate that the sequence as found in human is capable of directing eGFP to the nucleolus in several mammal, fish and insect cells. Moreover, this NoLS is capable of specifically directing the cytosolic yeast enzyme polyphosphatase to the target of the nucleolus of HeLa cells, wherein its enzymatic activity was detected. This NoLS could therefore serve as a very useful tool as a nucleolar marker and for directing particular proteins to the nucleolus in distant animal species.     

Evolutionary Conserved Positions Define Protein Conformational Diversity

Conformational diversity of the native state plays a central role in modulating protein function. The selection paradigm sustains that different ligands shift the conformational equilibrium through their binding to highest-affinity conformers. Intramolecular vibrational dynamics associated to each conformation should guarantee conformational transitions, which due to its importance, could possibly be associated with evolutionary conserved traits. Normal mode analysis, based on a coarse-grained model of the protein, can provide the required information to explore these features. Herein, we present a novel procedure to identify key positions sustaining the conformational diversity associated to ligand binding. The method is applied to an adequate refined dataset of 188 paired protein structures in their bound and unbound forms. Firstly, normal modes most involved in the conformational change are selected according to their corresponding overlap with structural distortions introduced by ligand binding. The subspace defined by these modes is used to analyze the effect of simulated point mutations on preserving the conformational diversity of the protein. We find a negative correlation between the effects of mutations on these normal mode subspaces associated to ligand-binding and position-specific evolutionary conservations obtained from multiple sequence-structure alignments. Positions whose mutations are found to alter the most these subspaces are defined as key positions, that is, dynamically important residues that mediate the ligand-binding conformational change. These positions are shown to be evolutionary conserved, mostly buried aliphatic residues localized in regular structural regions of the protein like β-sheets and α-helix.