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PubMed2002

A possible evolutionary origin for the Mn4 cluster of the photosynthetic water oxidation complex from natural MnO2 precipitates in the early ocean.

The photosynthetic water oxidation complex consists of a cluster of four Mn atoms bridged by O atoms, associated with Ca2+ and Cl-, and incorporated into protein. The structure is similar in higher plants and algae, as well as in cyanobacteria of more ancient lineage, dating back more than 2.5 billion years ago on Earth. It has been proposed that the proto-enzyme derived from a component of a natural early marine manganese precipitate that contained a CaMn4O9 cluster. A variety of MnO2 minerals are found in nature. Three major classes are spinels, sheet-like layered structures, and three-dimensional networks that contain parallel tunnels. These relatively open structures readily incorporate cations (Na+, Li+, Mg2+, Ca2+, Ba2+, H+, and even Mn2+) and water. The minerals have different ratios of Mn(III) and Mn(IV) octahedrally coordinated to oxygens. Using x-ray spectroscopy we compare the chemical structures of Mn in the minerals with what is known about the arrangement in the water oxidation complex to define the parameters of a structural model for the photosynthetic catalytic site. This comparison provides for the structural model a set of candidate Mn(4) clusters-some previously proposed and considered and others entirely novel.

Evolution, Molecular↗
PubMed2000

The evolution and understanding of hierarchical complexity in biology from an algebraic perspective.

We develop the rigorous notion of a model for understanding state transition systems by hierarchical coordinate systems. Using this we motivate an algebraic definition of the complexity of biological systems, comparing it to other candidates such as genome size and number of cell types. We show that our complexity measure is the unique maximal complexity measure satisfying a natural set of axioms. This reveals a strong relationship between hierarchical complexity in biological systems and the area of algebra known as global semigroup theory. We then study the rate at which hierarchical complexity can evolve in biological systems assuming evolution is "as slow as possible" from the perspective of computational power of organisms. Explicit bounds on the evolution of complexity are derived showing that, although the evolutionary changes in hierarchical complexity are bounded, in some circumstances complexity may more than double in certain "genius jumps" of evolution. In fact, examples show that our bounds are sharp. We sketch the structure where such complexity jumps are known to occur and note some similarities to previously identified mechanisms in biological evolutionary transitions. We also address the question of, How fast can complexity evolve over longer periods of time? Although complexity may more than double in a single generation, we prove that in a smooth sequence of t "inclusion" steps, complexity may grow at most from N to (N + 1)t + N, a linear function of number of generations t, while for sequences of "mapping" steps it increases by at most t. Thus, despite the fact that there are major transitions in which complexity jumps are possible, over longer periods of time, the growth of complexity may be broken into maximal intervals on which it is bounded above in the manner described.

Animals↗
PubMed2003

A phylogenetic study of cytochrome b561 proteins.

BACKGROUND: As an antioxidant and cofactor to numerous metabolic enzymes, ascorbate has an essential role in plants and animals. Cytochromes b561 constitute a class of intrinsic membrane proteins involved in ascorbate regeneration. Despite their importance in ascorbate metabolism, no evolutionary analysis has been presented so far on this newly described protein family. RESULTS: Cytochromes b561 have been identified in a large number of phylogenetically distant species, but are absent in fungi and prokaryotes. Most species contain three or four cytochrome b561 paralogous proteins, and the encoding genes usually have four or five exons. At the protein level, sequence similarities are rather low between cytochromes b561 within a single species (34-45% identity), and among phylogenetically distant species (around 30% identity). However, particular structural features characterizing this protein family are well conserved in members from all species investigated. These features comprise six transmembrane helices, four strictly conserved histidine residues, probably coordinating the two heme molecules, and putative ascorbate and monodehydro-ascorbate (MDHA) substrate-binding sites. Analysis of plant cytochromes b561 shows a separation between those from monocotyledonous and dicotyledonous species in a phylogenetic tree. CONCLUSIONS: All cytochromes b561 have probably evolved from a common ancestral protein before the separation of plants and animals. Their phyletic distribution mirrors the use of ascorbate as primary antioxidant, indicating their role in ascorbate homeostasis and antioxidative defense. In plants, the differentiation into four cytochrome b561 isoforms probably occurred before the separation between monocots and dicots.

Animals↗
PubMed2006

Facial patterns in Cercopithecoidea and Hominoidea: a geometric approach.

The maxillofacial and orbital compartments of the primate skull contribute to the ontogenetic and phylogenetic variability of the viscerocranium and are of crucial evolutionary relevance. As the form of organisms changes depending on endo- and exogenous factors, metrical evaluation of specific adaptations and incorporation of the results into a biological framework could be helpful in identifying valid characters for separation of taxa (e.g. family, genus, and species) and in understanding divergence and convergence. During the last two decades a morphometric "revolution" heralded by Rohlf & Marcus (1993), Adams et al. (2004) and Oxnard (2004) brought about a synthesis of traditional quantitative-morphometrical with modern methods. This approach is called "Geometric Morphometrics (GM)" and constitutes the coremethod applied here. Based on standardized photographs (in Norma frontalis), landmarks (LM) were set and two-dimensional coordinates (X, Y) recorded for the facial cranium in selected representatives of the superfamilies Cercopithecoidea and Hominoidea. The comparison of two datasets by means of factor analysis and distance computation for the complete maxillofacial complex on the one hand, and circumorbital and orbital features on the other, indicate that morphological differences between super-families and genera are valid for separating them even in a heterogeneous sample like the one presented here. Including more landmarks and therewith capturing the morph in a more complex way optimizes separation within the sample.

Algorithms↗
PubMed1995

Phylogenetic study of bisexual Artemia using random amplified polymorphic DNA.

Study of polymorphisms in the eukaryotic genome is an important way to discover the evolutionary relationships between species. Artemia (Crustacea, Anostraca) offers a very interesting model for evolutionary studies. In fact the genus, distributed all over the world in hundreds of known biotopes, comprises both bisexual sibling species and parthenogenetic populations easily available from the Artemia Reference Center of Ghent. In spite of great interest in it and its extensive use in aquaculture, little is known about relationships between the different species and intraspecific populations. Recently it has been demonstrated that polymorphisms in genomic fingerprints generated by arbitrarily primed polymerase chain reaction (PCR) can distinguish between strains in many organisms. We have used this technique to estimate the phylogenetic relationships existing between 14 populations living in the American continent, in the Mediterranean area, and in China. The principal coordinate analysis (PCO) obtained from 86 random amplified polymorphic DNA (RAPD) markers indicates that the populations analyzed can be divided into homogeneous clusters representing the four known bisexual species--the American A. franciscana and A. persimilis, the Mediterranean A. salina, and the A. species from China.

Animals↗
PubMed2006

Maintenance of above-branch balance during primate arboreal quadrupedalism: coordinated use of forearm rotators and tail motion.

Animals that live and travel in trees display a variety of morphological and behavioral adaptations to help them maintain balance on narrow flexible supports. Among these adaptations are long tails that can be used as counterweights, and freely mobile limbs in order to reach discontinuous supports. Here we describe two additional ways in which these features can contribute to balance during arboreal locomotion. Electromyographic (EMG) recordings of the forearm rotators pronator quadratus and supinator during over-ground and above-branch quadrupedal locomotion in five species of Old World monkeys revealed their contribution to shifting the weight of the body to help change the direction of travel and maintain balance on a branch. In addition, we observed a coordinated mechanism consisting of a sweeping tail rotation toward the direction of imbalance, to impart an angular momentum to the body that assists in the restoration of balance. While all five primate species utilized forearm rotators to shift their bodies toward one side or the other during quadrupedal walking along a branch, the tail-whip mechanism was most frequently used by the largest and most terrestrial species. We suggest that their large size and/or terrestrial habits have made them less adept at arboreal locomotion, and therefore most likely to utilize auxiliary balancing mechanisms. The usefulness of a long tail as a balancing aid during arboreal locomotion highlights the puzzling nature of the evolutionary loss of a tail in the ape and human lineage.

Animals↗
PubMed1996

The enigma of common fragile sites.

One hundred and fifty breakpoint sites were recorded during an analysis of aphidicolin-ethanol inducible fragile sites (FS) in 56 blood samples and 13 amniocyte cultures and were classified according to the criteria formulated by the Chromosome Coordinating Meeting. The finding of previously unlisted FS in this sample, the altered expression of FS in conditions not usually associated with chromosomal abnormalities and the apparent lack of tissue specificity indicate the importance of one or more fundamental mechanisms operating to produce the diverse associated clinical phenotypes, with the chromosomal fragility representing an intermediate phenotype. Several lines of evidence converge towards the conclusion that FS are a manifestation of an altered state of genetic activity at areas associated with transcriptional regulation, because of their concordance with CpG islands, nuclease sensitive sites, replication origins, zinc finger protein domains and viral integration sites. An investigation is required whether this phenomenon could contribute both to evolutionary diversity through increased recombination, the formation of unstable repeat sequences and variable methylation, and to the expression of multigene disease processes resulting in the production of variable and complex phenotypes, even within families.

Chromosome Fragile Sites↗
PubMed1975

Transformations of consciousness. A cartography. I. The perception-hallucination continuum.

Self-awareness emerges from the evolutionary transformation of material structures into magical, mythical and mental structures of consciousness. Western varieties of conscious states may be mapped on a perception-hallucination continuum of increasing ergotropic or hyper-arousal. These levels of subcortical arousal are cortically or cognitively interpreted as normal, creative, hyperhrenic, cataleptic and ecstatic states. During increasing hyper-arousal (characterized by EEG desynchronization): (1) the variability of the EEG amplitude decreases in introverts whereas in extroverts, it increases; (2) exteroception is transformed into an experience of interoception, while willed motor activity becomes increasingly impaired and ultimately inhibited, and (3) information processing during these hallucinatory states is preferentially shifted from the speech dominant and motor-coordinating or "major" toward the nonverbal, gestalt-perceiving, the non-dominant or "minor" cortical hemisphere.

Amnesia↗
PubMed2025

Conserved HSFA1-dependent chromatin dynamics drive heat stress responses in plants.

Eukaryotic organisms remodel chromatin landscapes to regulate gene expression in response to environmental stress. In plants, heat stress (HS) induces widespread chromatin changes, yet the role of heat shock transcription factors (HSFs) in chromatin remodeling and their evolutionary conservation remains unclear. Using Marchantia polymorpha Mphsf mutants and Arabidopsis thaliana Athsfa1s mutants, we identify HSFA1 as a key regulator of HS-induced cis-regulatory element (CRE) accessibility, a mechanism conserved across land plants, mice, and humans. Gene regulatory network modeling reveals parallel transcription factor subnetworks, with MpWRKY10 and MpABI5B acting as indirect and negative HS regulators. We further showed that ABA modulates gene expression in an HSFA1-dependent manner without inducing chromatin remodeling. Finally, we develop a machine learning framework integrating chromatin accessibility and CRE information to predict gene expression across species, revealing stress-responsive regulatory logic at the transcriptional level. These findings provide insights into how TFs coordinate chromatin architecture to drive stress adaptation.

Heat-Shock Response↗
PubMed1995

[Immunology of human Plasmodium falciparum malaria].

The various stages of Plasmodium falciparum (sporozoites and liver stages, asexual blood stages and gametocytes) each interact in a particular way with the human immune system. Specific immunity against the liver stages is achieved through a coordinated action of CD8 T cells and specific antibodies, the latter in collaboration with NK cells and macrophages. In this reaction, interferon-gamma plays an essential role. A non-specific "concomitant" immunity against sporozoites is based on a cytokine reaction, elicited by the blood stages. In practice, the high variability in the immunogenic structures of the sporozoite precludes completely protection against recurrent infections. The spleen macrophages have a pivotal role in the immune defense against the asexual blood stages. The elimination of merozoites and parasitized red blood cells (RBC) is facilitated by specific antibodies, produced under the control of CD4 T cells. There are, however, multiple mechanisms of immune deviation, suppression and evolutionary adaptation, which inhibit a sterilizing immunity against the blood stages. Nevertheless, symptoms may be absent in exposed adults, even when parasitemia persists. This clinical resistance, however, is relatively short-lived, once exposition is interrupted. The observation that HIV infection has no adverse effect on malaria also is a remarkable but consistent finding. All these data indicate that a strong T cell-mediated immune memory is absent in human P. falciparum infections. Cerebral malaria and some other serious complications are the consequence of insufficient elimination of parasitized erythrocytes by the spleen, presumably in combination with parasite factors (particular variant surface structures) and with human host genetics (HLA type, blood group etc.). Parasitized RBC massively stick to the endothelium of the micro-vessels and non-parasitized RBC roset around the parasitized ones. Eventually, serious problems in the micro-perfusion and in the local metabolism occur and organ failure may finally ensue. The immune reaction against the surface-antigens of the sexual stage is limited and insufficient, most probably for similar reasons as in the asexual stages. Internal structures of the gametocytes, however, are highly immunogenic, but, unfortunately. Normally cannot be reached by the immune system. Based on these fundamental data, some of the perspectives of vaccination and new therapeutic tools are critically discussed.

Adult↗
PubMed2026

From commensal to pathobiont: The emergence of virulence-enhanced Escherichia coli in China's food-animal systems - insights with future implications.

A fundamental shift in Escherichia coli epidemiology is being driven by convergence of virulence determinants and antimicrobial resistance within linked human-animal-environment systems. In China, the rapid growth of food-animal production, extensive antimicrobial use, and complex food networks are accelerating the emergence and dissemination of virulence-enhanced E. coli pathobionts. This review synthesizes recent epidemiological, genomics, and outbreak data to characterize China's evolving landscape of food-animal-associated E. coli. We highlight a significant shift from classical pathotypes to hybrid lineages that simultaneously carry virulence factors and last-resort antibiotic resistance determinants, including mcr-1, tet(X4), and blaNDM. These traits disseminate rapidly via plasmid-mediated horizontal gene transfer, facilitating rapid adaptation and enabling cross-sectoral One Health transmission. National surveillance, foodborne outbreak investigations, and whole-genome sequencing data show that food-animal reservoirs are active evolutionary niches that drive pathogen diversity and fitness, rather than serving merely as contamination sources. Whole-genome sequencing also pinpoints high-risk clones (e.g., ST394) and plasmid-mediated co-selection of virulence and AMR. The emergence of hybrid pathotypes (e.g., STEC/ETEC) and AMR-virulence co-selection challenges traditional classification and limits the effectiveness of conventional surveillance approaches. The 2017 colistin ban reduced mcr-1, yet ongoing resistance and emerging tet(X4) demand integrated surveillance. Collectively, these findings call for reconceptualizing E. coli as a dynamic genomic entity embedded within a unified ecological network. Addressing this threat requires an integrated One Health strategy including genomic surveillance, agricultural antimicrobial stewardship, and coordinated food-environment-clinical monitoring to prevent high-risk clone emergence and global spread.

Animals↗
PubMed1992

Fast and simple Monte Carlo algorithm for side chain optimization in proteins: application to model building by homology.

An unknown protein structure can be predicted with fair accuracy once an evolutionary connection at the sequence level has been made to a protein of known 3-D structure. In model building by homology, one typically starts with a backbone framework, rebuilds new loop regions, and replaces nonconserved side chains. Here, we use an extremely efficient Monte Carlo algorithm in rotamer space with simulated annealing and simple potential energy functions to optimize the packing of side chains on given backbone models. Optimized models are generated within minutes on a workstation, with reasonable accuracy (average of 81% side chain chi 1 dihedral angles correct in the cores of proteins determined at better than 2.5 A resolution). As expected, the quality of the models decreases with decreasing accuracy of backbone coordinates. If the back-bone was taken from a homologous rather than the same protein, about 70% side chain chi 1 angles were modeled correctly in the core in a case of strong homology and about 60% in a case of medium homology. The algorithm can be used in automated, fast, and reproducible model building by homology.

Algorithms↗
PubMed2005

Emerging from the fog: hypotheses and paradigms in developmental biology--the Society for Developmental Biology 2005 Annual Meeting Report.

The Society for Developmental Biology 64th annual meeting took place by the beautiful San Francisco Bay from July 27th to August 1st, 2005. Organized under the leadership of Judith Kimble (SDB President, U. Wisconsin-Madison), the meeting attracted over one thousand developmental biologists from all over the world. They gathered to present data, exchange ideas and enjoy basking in the warm sun on the piers. Strong themes emerged from the diverse subjects discussed at the meeting, demonstrating exciting trends towards the unifying goal of understanding the progression from a single cell to an adult organism. Cell and Tissue Polarity was a recurring topic at the meeting. Questions like "is there polarity", "how is it achieved" and "how is it linked to stem cell maintenance" were discussed. Post-transcriptional regulation involving protein degradation and microRNA (miRNA) modulation of gene expression was featured in the context of transition between meiosis to mitosis and asymmetries in the embryo. It is apparent that Evolutionary Developmental Biology, once a major driving influence in the early days of the field, continues to enjoy a renaissance as researchers familiar with traditional model organisms are increasingly attracted to the field and as modern genetic and molecular approaches are applied to an increasingly varied assortment of organisms. The attention is beginning to pay off as laboratories are starting to generate significant results shedding light into how developmental programs are altered to generate morphological diversity. In the Satellite Symposium on Plant Development held on July 27th, 2005, the overriding theme was on the identity and maintenance of Stem Cells in Plants. Finally, researchers working on diverse organisms have shown a strong effort to address Developmental Coordination: on the subcellular, cellular and tissue levels. Advanced imaging techniques are combined with traditional genetic methods to scrutinize and compare dynamic processes in four dimensions. This tremendous increase in resolution has facilitated the identification of key signaling mechanisms that embryos utilize to form coordinated body plans. For an exceptional effort in keeping with Society tradition, the 2005 annual meeting also offered opportunities to address broader issues revolving around education and professional development as well as a special session on embryonic stem cell research. Throughout the 5-day meeting, participants found time to honor the contributions of colleagues, exchange career and grant planning strategies, contemplate the big picture and recognize the efforts of young investigators, postdoctoral fellows and students.

Animals↗
PubMed1999

Site-directed mutagenesis of diphosphoinositol polyphosphate phosphohydrolase, a dual specificity NUDT enzyme that attacks diadenosine polyphosphates and diphosphoinositol polyphosphates.

Diphosphoinositol polyphosphate phosphohydrolase (DIPP) hydrolyzes diadenosine 5',5"'-P(1),P(6)-hexaphosphate (Ap(6)A), a Nudix (nucleoside diphosphate attached-moiety "x") substrate, and two non-Nudix compounds: diphosphoinositol pentakisphosphate (PP-InsP(5)) and bis-diphosphoinositol tetrakisphosphate ((PP)(2)-InsP(4)). Guided by multiple sequence alignments, we used site-directed mutagenesis to obtain new information concerning catalytically essential amino acid residues in DIPP. Mutagenesis of either of two conserved glutamate residues (Glu(66) and Glu(70)) within the Nudt (Nudix-type) catalytic motif impaired hydrolysis of Ap(6)A, PP-InsP(5), and (PP)(2)-InsP(4) >95%; thus, all three substrates are hydrolyzed at the same active site. Two Gly-rich domains (glycine-rich regions 1 and 2 (GR1 and GR2)) flank the Nudt motif with potential sites for cation coordination and substrate binding. GR1 comprises a GGG tripeptide, while GR2 is identified as a new functional motif (GX(2)GX(6)G) that is conserved in yeast homologues of DIPP. Mutagenesis of any of these Gly residues in GR1 and GR2 reduced catalytic activity toward all three substrates by up to 95%. More distal to the Nudt motif, H91L and F84Y mutations substantially decreased the rate of Ap(6)A and (PP)(2)-InsP(4) metabolism (by 71 and 96%), yet PP-InsP(5) hydrolysis was only mildly reduced (by 30%); these results indicate substrate-specific roles for His(91) and Phe(84). This new information helps define DIPP's structural, functional, and evolutionary relationships to Nudix hydrolases.

Acid Anhydride Hydrolases↗
PubMed1986

Cloning of cDNA and genomic DNA for human von Willebrand factor.

The recent isolation of cDNA and genomic DNA clones for human vWF by ourselves and others has finally laid to rest the historical notion that factor VIII and vWF might have a precursor-product or other complex relationship. These two hemostatic activities are clearly present on two distinct proteins, each encoded by a separate gene. Whether ther is coordinate regulation of the factor VIII and vWF genes is still unknown. The structure and structure-function relationships of the vWF protein have been elucidated by many investigators, only some of whom can be cited in this short paper. Together, these molecular biology and protein chemistry studies have shown that vWAgII is the amino-terminal propeptide of vWF, explaining the proportional deficiency of these two plasma proteins in von Willebrand disease (type I). In addition, sites of proteolytic processing, glycosylation, and disulfide bond formation have been defined, and some of the binding functions of mature vWF have been identified with specific amino acid sequences. The protein has a highly repeated structure, suggesting a complex evolutionary history. The A domains of vWF appear to be homologous to complement factor B, and perhaps to component C2, although the biological meaning of this similarity is unknown. Genomic DNA clones have been isolated corresponding to approximately one third of the vWF gene on chromosome 12, and a fragment of the cDNA also hybridizes to uncharacterized sequences on chromosome 22. Preliminary studies in von Willebrand disease have revealed two patients with very large deletions in the vWF gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2006

The replicator equation on graphs.

We study evolutionary games on graphs. Each player is represented by a vertex of the graph. The edges denote who meets whom. A player can use any one of n strategies. Players obtain a payoff from interaction with all their immediate neighbors. We consider three different update rules, called 'birth-death', 'death-birth' and 'imitation'. A fourth update rule, 'pairwise comparison', is shown to be equivalent to birth-death updating in our model. We use pair approximation to describe the evolutionary game dynamics on regular graphs of degree k. In the limit of weak selection, we can derive a differential equation which describes how the average frequency of each strategy on the graph changes over time. Remarkably, this equation is a replicator equation with a transformed payoff matrix. Therefore, moving a game from a well-mixed population (the complete graph) onto a regular graph simply results in a transformation of the payoff matrix. The new payoff matrix is the sum of the original payoff matrix plus another matrix, which describes the local competition of strategies. We discuss the application of our theory to four particular examples, the Prisoner's Dilemma, the Snow-Drift game, a coordination game and the Rock-Scissors-Paper game.

Animals↗
PubMed2000

The basis of prostaglandin synthesis in coral: molecular cloning and expression of a cyclooxygenase from the Arctic soft coral Gersemia fruticosa.

In vertebrates, the synthesis of prostaglandin hormones is catalyzed by cyclooxygenase (COX)-1, a constitutively expressed enzyme with physiological functions, and COX-2, induced in inflammation and cancer. Prostaglandins have been detected in high concentrations in certain corals, and previous evidence suggested their biosynthesis through a lipoxygenase-allene oxide pathway. Here we describe the discovery of an ancestor of cyclooxygenases that is responsible for prostaglandin biosynthesis in coral. Using a homology-based polymerase chain reaction cloning strategy, the cDNA encoding a polypeptide with approximately 50% amino acid identity to both mammalian COX-1 and COX-2 was cloned and sequenced from the Arctic soft coral Gersemia fruticosa. Nearly all the amino acids essential for substrate binding and catalysis as determined in the mammalian enzymes are represented in coral COX: the arachidonate-binding Arg(120) and Tyr(355) are present, as are the heme-coordinating His(207) and His(388); the catalytic Tyr(385); and the target of aspirin attack, Ser(530). A key amino acid that determines the sensitivity to selective COX-2 inhibitors (Ile(523) in COX-1 and Val(523) in COX-2) is present in coral COX as isoleucine. The conserved Glu(524), implicated in the binding of certain COX inhibitors, is represented as alanine. Expression of the G. fruticosa cDNA afforded a functional cyclooxygenase that converted exogenous arachidonic acid to prostaglandins. The biosynthesis was inhibited by indomethacin, whereas the selective COX-2 inhibitor nimesulide was ineffective. We conclude that the cyclooxygenase occurs widely in the animal kingdom and that vertebrate COX-1 and COX-2 are evolutionary derivatives of the invertebrate precursor.

Alanine↗
PubMed2006

Integrative plant biology: role of phloem long-distance macromolecular trafficking.

Recent studies have revealed the operation of a long-distance communication network operating within the vascular system of higher plants. The evolutionary development of this network reflects the need to communicate environmental inputs, sensed by mature organs, to meristematic regions of the plant. One consequence of such a long-distance signaling system is that newly forming organs can develop properties optimized for the environment into which they will emerge, mature, and function. The phloem translocation stream of the angiosperms contains, in addition to photosynthate and other small molecules, a variety of macromolecules, including mRNA, small RNA, and proteins. This review highlights recent progress in the characterization of phloem-mediated transport of macromolecules as components of an integrated long-distance signaling network. Attention is focused on the role played by these proteins and RNA species in coordination of developmental programs and the plant's response to both environmental cues and pathogen challenge. Finally, the importance of developing phloem transcriptome and proteomic databases is discussed within the context of advances in plant systems biology.

Biological Transport↗