Showing papers by "Washington State University published in 1997"

Folding-Unfolding Transitions in Single Titin Molecules Characterized with Laser Tweezers

Abstract: Titin, a giant filamentous polypeptide, is believed to play a fundamental role in maintaining sarcomeric structural integrity and developing what is known as passive force in muscle. Measurements of the force required to stretch a single molecule revealed that titin behaves as a highly nonlinear entropic spring. The molecule unfolds in a high-force transition beginning at 20 to 30 piconewtons and refolds in a low-force transition at approximately 2.5 piconewtons. A fraction of the molecule (5 to 40 percent) remains permanently unfolded, behaving as a wormlike chain with a persistence length (a measure of the chain's bending rigidity) of 20 angstroms. Force hysteresis arises from a difference between the unfolding and refolding kinetics of the molecule relative to the stretch and release rates in the experiments, respectively. Scaling the molecular data up to sarcomeric dimensions reproduced many features of the passive force versus extension curve of muscle fibers.

Pollen germination and tube growth

Abstract: Many aspects of Angiosperm pollen germination and tube growth are discussed including mechanisms of dehydration and rehydration, in vitro germination, pollen coat compounds, the dynamic involvement of cytoskeletal elements (actin, microtubules), calcium ion fluxes, extracellular matrix elements (stylar arabinogalactan proteins), and control mechanisms of gene expression in dehydrating and germinating pollen. We focus on the recent developments in pollen biology that help us understand how the male gamete survives and accomplishes its successful delivery to the ovule of the sperm to effect sexual reproduction.

Jasmonate is essential for insect defense in Arabidopsis.

Abstract: The signaling pathways that allow plants to mount defenses against chewing insects are known to be complex. To investigate the role of jasmonate in wound signaling in Arabidopsis and to test whether parallel or redundant pathways exist for insect defense, we have studied a mutant (fad3–2 fad7–2 fad8) that is deficient in the jasmonate precursor linolenic acid. Mutant plants contained negligible levels of jasmonate and showed extremely high mortality (≈80%) from attack by larvae of a common saprophagous fungal gnat, Bradysia impatiens (Diptera: Sciaridae), even though neighboring wild-type plants were largely unaffected. Application of exogenous methyl jasmonate substantially protected the mutant plants and reduced mortality to ≈12%. These experiments precisely define the role of jasmonate as being essential for the induction of biologically effective defense in this plant–insect interaction. The transcripts of three wound-responsive genes were shown not to be induced by wounding of mutant plants but the same transcripts could be induced by application of methyl jasmonate. By contrast, measurements of transcript levels for a gene encoding glutathione S-transferase demonstrated that wound induction of this gene is independent of jasmonate synthesis. These results indicate that the mutant will be a good genetic model for testing the practical effectiveness of candidate defense genes.

Stereoselective Bimolecular Phenoxy Radical Coupling by an Auxiliary (Dirigent) Protein Without an Active Center

Abstract: The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol.

Chloroplast DNA intraspecific phylogeography of plants from the Pacific Northwest of North America

Abstract: Molecular studies of plants from the Pacific Northwest of North America suggest a recurrent pattern of genetic differentiation and geographic structuring. In each of five angiosperms and one fern species representing diverse life histories, cpDNA data indicate two clades of populations that are geographically structured. A northern group comprises populations from Alaska to central or southern Oregon, whereas populations from central Oregon southward to northern California form a southern group. In several of these species, a few populations having southern genotypes may have survived in glacial refugia further north in the Olympic Peninsula, Queen Charlotte Islands, and Prince of Wales Island. Allozyme data reveal a similar pattern of differentiation in several other plants from the Pacific Northwest. North-south partitioning of genotypes has also been reported for several animal species from this region. On a broader geographic scale, northsouth partitioning of genotypes has also been observed in other plants from western North America having a variety of geographic distributions. Some species also display a reduction of genetic variability in the northern portion of their range compared to the south. The data suggest strongly that past glaciation profoundly influenced the genetic architecture of the flora and fauna of the Pacific Northwest. Two alternative hypotheses are advanced to explain the geographic structuring of genotypes. First, past glaciation may have created discontinuities in the geographic distributions of plant species, with populations surviving in several well-isolated northern and southern refugia. Following glaciation, migration of genetically differentiated, once-isolated populations resulted in the formation of a continuous geographic distribution with a major genetic discontinuity. Alternatively, plants survived and subsequently migrated northward from a southern refugium, and a genotype became fixed in one or a few populations at the leading edge of recolonization. Subsequent long-distance dispersal from this leading edge resulted in a relatively uniform northern genotype that differs from the southern genotype(s). Whatever the underlying mechanism, Pleistocence glaciation may have molded the intraspecific genetic architecture of both plants and animals from the Pacific Northwest in a geographically similar manner. Future studies should seek to obtain a comprehensive phylogeography for regions that includes a diversity of both plants and animals.

Transfection of a reporter plasmid into cultured cells by sonoporation in vitro

Abstract: Cultured Chinese hamster ovary cells were exposed to 2.25-MHz ultrasound in sterile 4.5-mL polyethylene chambers and tested for cell lysis, sonoporation and DNA transfection. Ten percent of Albunex, a gas-body-based ultrasound contrast agent, was added to ensure cavitation nucleation, and the chambers were rotated at 60 rpm to promote cavitation activity during the 1-min exposures. Uptake of large fluorescent dextran molecules by some cells was observed for spatial peak pressure amplitudes as low as 0.1 MPa, which indicates transient permeabilization and resealing, i.e., sonoporation, of these cells during exposure. Significant lysis occurred for 0.2 MPa, and increased rapidly for exposures above the apparent cavitation threshold (using the H2O2 production test) of about 0.4 MPa spatial peak pressure amplitude. In the DNA transfection tests, 20 micrograms/mL luciferase reporter plasmid was added to the suspension during exposure, and cells were assayed for proliferation ability and luciferase gene expression 2 days after exposure. Cell proliferation was greatly reduced above the cavitation threshold. Luciferase production was significant for 0.20-MPa exposure, and reached 0.33 ng per 10(6) cells at 0.8-MPa exposure. The luciferase production was great for cells exposed in medium supplemented with serum than for cells exposed in serum-free medium. Cells harvested for exposure either in the log phase or in the stationary phase of culture gave similar proliferation and transfection results. The effects essentially disappeared when the Albunex was omitted from the suspension and the tube was not rotated. Thus, sonoporation by ultrasonic cavitation in the rotating tube system yields plasmid transfection with subsequent transient gene expression.

Macromolecular Trafficking Indicated by Localization and Turnover of Sucrose Transporters in Enucleate Sieve Elements

Abstract: The leaf sucrose transporter SUT1 is essential for phloem loading and long-distance transport of assimilates. Both SUT1 messenger RNA (mRNA) and protein were shown to be diurnally regulated and to have high turnover rates. SUT1 protein was detected by immunolocalization in plasma membranes of enucleate sieve elements (SEs) in tobacco, potato, and tomato. Analysis by in situ hybridization showed that SUT1 mRNA localizes mainly to the SE and is preferentially associated with plasmodesmata. Antisense inhibition of SUT1 expression under control of a companion cell (CC)-specific promoter indicated synthesis of SUT1 mRNA in the CC. These results provide evidence for targeting of plant endogenous mRNA and potentially SUT1 protein through phloem plasmodesmata and for sucrose loading at the plasma membrane of SE.

Virtual assembly using virtual reality techniques

Abstract: Virtual reality is a technology which is often regarded as a natural extension to 3D computer graphics with advanced input and output devices. This technology has only recently matured enough to warrant serious engineering applications. The integration of this new technology with software systems for engineering, design, and manufacturing will provide a new boost to the field of computer-aided engineering. One aspect of design and manufacturing which may be significantly affected by virtual reality is design for assembly. This paper presents a research effort aimed at creating a virtual assembly design environment.

Social Capital and the Generation of Human Capital

Abstract: We make use of a large sample of data taken from the National Educational Longitudinal Survey, to examine the effects of various measures of financial, human and social capital on the likelihood of dropping out of school. We test whether social capital mediates the effect of parental financial and human capital on leaving school. The findings indicate that both more general measures of social capital (attending a Catholic school, family structure) and more specific measures of social capital (parentchild and parent-school interaction) are related to dropping out of high school. The findings also indicate that social capital interacts with the financial and human capital of parents to determine school continuation. In reaction to the influence of economic theory on sociological thought, Coleman (1988) argues that the well-known concepts of financial and human capital (cf., Becker 1964, 1991) should be supplemented by the concept of social capital when attempting to explain human action. Coleman bases his argument on the selfevident fact that persons' actions are shaped by social context and not simply by the financial and human resources available to them. In this article, we test Coleman's argument by making use of a large sample of data taken from the National Educational Longitudinal Study to evaluate the joint impact of financial, human, and social capital on the creation of human capital in the next generation. In addition, we move beyond the simple consideration of the marginal effect of social capital by seeking to determine whether social capital

Formation of plant RNA virus replication complexes on membranes: role of an endoplasmic reticulum-targeted viral protein.

Abstract: The mechanisms that direct positive-stranded RNA virus replication complexes to plant and animal cellular membranes are poorly understood. We describe a specific interaction between a replication protein of an RNA plant virus and membranes in vitro and in live cells. The tobacco etch virus (TEV) 6 kDa protein associated with membranes as an integral protein via a central 19 amino acid hydrophobic domain. In the presence or absence of other viral proteins, fluorescent fusion proteins containing the 6 kDa protein associated with large vesicular compartments derived from the endoplasmic reticulum (ER). Infection by TEV was associated with a collapse of the ER network into a series of discrete aggregated structures. Viral RNA replication complexes from infected cells were also associated with ER-like membranes. Targeting of TEV RNA replication complexes to membranous sites of replication is proposed to involve post-translational interactions between the 6 kDa protein and the ER.

A glycine to serine change in puroindoline b is associated with wheat grain hardness and low levels of starch-surface friabilin

Abstract: The quantitative level of friabilin 15-kDa protein present on the surface of water-washed starch is highly correlated with wheat grain softness. Friabilin is composed primarily, if not exclusively, of the proteins puroindoline a and b. The transcript levels of these two proteins are similar among hard and soft wheat varieties, and the expression of both is controlled by the short arm of chromosome 5D, also the chromosomal location of the Hardness gene. We report here a glycine to serine sequence change in puroindoline b associated with hard grain texture. This amino acid change results from a single nucleotide mutation and resides in a region thought to be important for the lipid-binding properties of puroindolines. No recombination was observed between the serine puroindoline-b mutation, hard grain texture and low levels of starch surface friabilin among a set of 83 homozygous 5D recombinant lines derived from the soft-textured variety ‘Chinese Spring’ and the substitution line ‘Chinese Spring’ containing the 5D chromosome of the hard-textured variety ‘Cheyenne’. The sequence change reported here may adversely affect the lipid-binding properties of puroindoline-b and so effect hard grain texture. The results suggest that grain hardness results from puroindoline-b functionality such that the Hardness gene is a direct manifestation of puroindoline structure. We are suggesting the tentative molecular marker loci designations of Pinb-D1a and Pinb-D1b for the glycine and serine puroindoline-b types, respectively.

The solution structure of an HMG-I(Y)-DNA complex defines a new architectural minor groove binding motif.

Abstract: The solution structure of a complex between a truncated form of HMG-I(Y), consisting of the second and third DNA binding domains (residues 51-90), and a DNA dodecamer containing the PRDII site of the interferon-beta promoter has been solved by multidimensional nuclear magnetic resonance spectroscopy. The stoichiometry of the complex is one molecule of HMG-I(Y) to two molecules of DNA. The structure reveals a new architectural minor groove binding motif which stabilizes B-DNA, thereby facilitating the binding of other transcription factors in the opposing major groove. The interactions involve a central Arg-Gly-Arg motif together with two other modules that participate in extensive hydrophobic and polar contracts. The absence of one of these modules in the third DNA binding domain accounts for its-100 fold reduced affinity relative to the second one.

Inauthenticity and depression : Assessing the consequences of interactive service work

Abstract: Interactive service jobs are an increasingly important feature of the occupational landscape. Despite over a decade of rising employment within this segment of the economy, researchers are only beg...

Identification and molecular cloning of a gene encoding a fibronectin-binding protein (CadF) from Campylobacter jejuni.

Abstract: Campylobacter jejuni, a Gram-negative bacterium, is a common cause of gastrointestinal disease. By analogy with other enteric pathogens such as Salmonella and Shigella, the ability of C. jejuni to bind to host cells is thought to be essential in the pathogenesis of enteritis. Scanning electron microscopy of infected INT407 cells suggested that C. jejuni bound to a component of the extracellular matrix. Binding assays using immobilized extracellular matrix proteins and soluble fibronectin showed specific and saturable binding of fibronectin to C. jejuni. Ligand immunoblot assays using 125I-labelled fibronectin revealed specific binding to an outer membrane protein with an apparent molecular mass of 37 kDa. A rabbit antiserum, raised against the gel-purified protein, reacted with a 37 kDa protein in all C. jejuni isolates (n = 15) as tested by immunoblot analysis. Antibodies present in convalescent serum from C. jejuni-infected individuals also recognized a 37 kDa protein. The gene encoding the immunoreactive 37kDa protein was cloned and sequenced. Sequencing of overlapping DNA fragments revealed an open reading frame (ORF) that encodes a protein of 326 amino acids with a calculated molecular mass of 36872Da. The deduced amino acid sequence of the ORF exhibited 52% similarity and 28% identity to the root adhesin protein from Pseudomonas fluorescens. Isogenic C. jejuni mutants which lack the 37 kDa outer membrane protein, which we have termed CadF, displayed significantly reduced binding to fibronectin. Biotinylated fibronectin bound to a protein with an apparent molecular mass of 37 kDa in the outer membrane protein extracts from wild-type C. jejuni as judged by ligand-binding blots. These results indicate that the binding of C. jejuni to fibronectin is mediated by the 37 kDa outer membrane protein which is conserved among C. jejuni isolates.

Winter cover crop effects on soil organic carbon and carbohydrate in soil

Abstract: Winter cover crops may increase soil organic carbon (SOC) levels or reduce their rate of depletion. Selection of appropriate cover crops to increase SOC requires an adequate knowledge of the quality and quantity of plant biomass produced and its rate of decomposition in soil. This study examined the SOC and carbohydrate concentrations in soil as affected by several leguminous and nonleguminous cover crops after 6 yr of a corn (Zea mays L.) cover crop double cropping system in a temperate, humid region. The vegetation in the control treatment without cover crops was primarily shepherd's-purse [Capsella bursa-pastoris (L.) Medikus]. The cover crops had a variable effect on SOC and soil carbohydrate concentrations due to a significant difference in total organic C and carbohydrate produced by the cover crops. The buried bag technique showed that the biomass C from the aboveground biomass of the cover crops decomposed rapidly in the soil with a half-life averaging 30.9 ± 9.4 (SD) d in 1992 and 55.2 ± 7.8 (SD) d in 1993. The decomposition of carbohydrate in the aboveground biomass in the soil was also rapid with an average half-life of 40.0 ± 13.1 (SD) d in 1992 and 50.5 ± 11.8 (SD) d in 1993. The overriding cover crop effect on SOC and carbohydrate was due to the magnitude of the C inputs from the cover crops. With more than 4 Mg ha -1 of top biomass, cereal rye (Secale cereale L.) and annual ryegrass (Lolium multijlorum Lam.) were better suited as winter cover crops for building SOC levels in this region than Austrian winter pea (Lathyrus hirsutus L.), hairy vetch (Vicia villosa Roth), and canola (Brassica napus L.).

Sources of Variation for Starch Gelatinization, Pasting, and Gelation Properties in Wheat

Abstract: The starch of wheat (Triticum aestivum L.) flour affects food product quality due to the temperature-dependent interactions of starch with water during gelatinization, pasting, and gelation. The objective of this study was to determine the fundamental basis of variation in gelatinization, pasting, and gelation of prime starch derived from seven different wheat cultivars: Kanto 107, which is a partial waxy mutant line, and six near-isogenic lines (NILs) differing in hardness. Complete pasting curves with extended 16-min hold at 93°C were obtained using the Rapid Visco Analyser (RVA). Apparent amylose content ranged from 17.5 to 23.5%; total amylose content ranged from 22.8 to 28.2%. Starches exhibited significant variation in onset of gelatinization. However, none of the parameters measured consistently correlated with onset or other RVA curve parameters that preceded peak paste viscosity. Peak paste viscosity varied from 190 to 323 RVA units (RVU). Higher peak, greater breakdown, lower final visc...

A longitudinal study of Escherichia coli O157 in fourteen cattle herds

Abstract: Escherichia coli O157 shedding in 14 cattle herds was determined by faecal culture at intervals of approximately 1 month for up to 13 months. The overall prevalence was 1.0% (113/10832 faecal samples) and 9 of the 14 herds were detected as positive. Herds positive 2 years previously (n = 5) had a higher prevalence of positive cattle (median = 1.9%) than herds which had been negative on a previous sampling (n = 8, median = 0.2%). Weaned heifers had a higher prevalence (1.8%) than did unweaned calves (0.9%) or adults (0.4%). For all herds the highest prevalence occurred in the summer months, which resulted in most of the positive faecal samples being collected on a minority of sampling visits.

Spongiform encephalopathy in free-ranging mule deer (odocoileus hemionus), white-tailed deer (odocoileus virginianus) and rocky mountain elk (cervus elaphus nelsoni) in northcentral colorado

Abstract: Between March 1981 and June 1995, a neurological disease characterized histologically by spongiform encephalopathy was diagnosed in 49 free-ranging cervids from northcentral Colorado (USA). Mule deer (Odocoileus hemionus) were the primary species affected and accounted for 41 (84%) of the 49 cases, but six Rocky Mountain elk (Cervus elaphus nelsoni) and two white-tailed deer (Odocoileus virginianus) were also affected. Clinical signs included emaciation, excessive salivation, behavioral changes, ataxia, and weakness. Emaciation with total loss of subcutaneous and abdominal adipose tissue and serous atrophy of remaining fat depots were the only consistent gross findings. Spongiform encephalopathy characterized by microcavitation of gray matter, intraneuronal vacuolation and neuronal degeneration was observed microscopically in all cases. Scrapie-associated prion protein or an antigenically indistinguishable protein was demonstrated in brains from 26 affected animals, 10 using an immunohistochemical staining procedure, nine using electron microscopy, and seven using Western blot. Clinical signs, gross and microscopic lesions and ancillary test findings in affected deer and elk were indistinguishable from those reported in chronic wasting disease of captive cervids. Prevalence estimates, transmissibility, host range, distribution, origins, and management implications of spongiform encephalopathy in free-ranging deer and elk remain undetermined.

Sequence Data Analysis for Long Disordered Regions Prediction in the Calcineurin Family.

Abstract: Our recently reported results (PSB 3:471-482, 1998; Proc. IEEE Intnl. Conf. Neural Networks 1:90-95, 1997; PSB 3:435-446, 1998) provide strong support for a hypothesis that some amino acid sequences code for disordered regions rather than structured ones and that such disordered regions are commonly involved in function. General and family-specific neural network predictors developed in those previous studies suggest that different classes of disordered regions exist. Here, family-specific data preprocessing for disorder prediction in the calcineurin (CaN) family is explored. The results show that prediction of order and disorder on CaN sequence data benefits significantly from the use of family-specific preprocessing, with feature extraction through principal components analysis (PCA) outperforming feature selection techniques, although all methods do a good job of discriminating CaN-specific disordered regions from CaN-specific ordered regions. On the other hand, for the discrimination of CaN-specific disordered regions from general (unrelated to CaN) ordered regions, feature selection approaches proved to be more appropriate than PCA. The results further support a hypothesis that different kinds of disordered regions exist, as all family-specific disorder predictors developed in this study significantly outperformed a previously reported general multi-family disorder predictor.

A Gene Encoding a Chloroplast-Targeted Lipoxygenase in Tomato Leaves Is Transiently Induced by Wounding, Systemin, and Methyl Jasmonate

Abstract: We investigated the relationship between the expression of lipoxygenase (LOX) genes and the systemin-dependent wound response in tomato (Lycopersicon esculentum) leaves. A polymerase chain reaction-based approach was used to isolate two tomato Lox cDNAs, called TomLoxC and TomLoxD. Both TomLOXC and TomLOXD amino acid sequences possess an N-terminal extension of about 60 residues that were shown by in vitro uptake to function as transit peptides, targeting these proteins into the chloroplast. Within 30 to 50 min following wounding or systemin or methyl jasmonate treatments, the TomLoxD mRNA level increased and reached a maximum between 1 and 2 h. TomLoxC mRNA was not detectable in leaves and was not found following wounding, but it was found in ripening fruits, indicating that the two tomato Lox genes are regulated in different tissues by different processes. The results suggest that the TomLoxD gene is up-regulated in leaves in response to wounding and encodes a chloroplast LOX that may play a role as a component of the octadecanoid defense-signaling pathway.

Constraints on frugivory by bears

Abstract: Bears consuming wild fruits for fall energy accumulation are constrained by several factors, including intake rate, the physiological capacity of the gastrointestinal tract, and the metabolic efficiency of gain in body mass. We measured these relationships through foraging and feeding trials using captive and wild black bears (Ursus americanus) and grizzly bears (Ursus arctos). Four fruit types covering a range of sizes and clustering were offered to captive bears to determine the effect of density, size, and presentation on intake rate. Intake rate (in grams per minute) and bite rates (in bites per minute) increased cur- vilinearly with increasing fruit density in singly spaced fruits. Maximum intakes ranged from 30 g/min for 0.5-g berries to >200 g/min for 4.2-g fruits. The highest bite rates were obtained during the initial encounter with each patch as bears consumed all visually apparent fruits on the surface. Bite rates quickly dropped by 15-20% as foraging continued within the patch. Maximum bite rates were not depressed until initial fruit density fell to 100 kg. We concluded that large bears, such as grizzlies, must depend on plants that permit large bite sizes or high bite rates through fruit clustering and bush configuration that reduce leaf-to-fruit ratios.

Intensive behavioral treatment for preschoolers with severe mental retardation and pervasive developmental disorder.

Abstract: From archival records, we assessed outcomes achieved by preschoolers with both severe mental retardation and autistic features: (a) an experimental group (n = 11), which received intensive behavioral treatment, and (b) a comparison group (n = 10), which received minimal treatment. At intake (mean CA = 3.08 years), the groups did not differ significantly on any variable. At follow-up children in the experimental group obtained a higher mean IQ and evinced more expressive speech than did those in the comparison group. Behavior problems diminished in both groups. Results indicate that intensively treated children achieved clinically meaningful gains relative to the comparison group but remained quite delayed.

The Timing of Sexual Intercourse among Adolescents Family, Peer, and Other Antecedents

Abstract: Children's perceptions of their relationships with their parents and peers in 1976 and 1981, respectively, along with other salient antecedent variables, were related to their age at first sexual intercourse, as reported in 1987. Data came from the National Survey of Children, a three-wave longitudinal study of 1,145 children age 7-11 (Wave 1), 12-16 (Wave 2), and 18-22 (Wave 3). Antecedent variables were taken from both Round 1 and Round 2 surveys. When the same variables were present at both times, the more recent data were used if the survey occurred prior to age of first sexual intercourse; if not, the Round 1 data were used. Separate analyses were run to predict timing of sexual intercourse for males and females. Age of first date, dating often, number of friends perceived to have had sex at age 16, being Black, having parents undergo marital changes during the child's school years, and fighting at school were the most significant predictors of age at first sexual intercourse among males. All of thes...

Identifying disordered regions in proteins from amino acid sequence

Abstract: A rule-based and several neural network predictors are developed for identifying disordered regions in proteins. The rule-based predictor, which relied on the observation that disordered regions contain few aromatic amino acids, was suitable only for very long disordered regions, whereas the neural network predictors were developed separately for short-, medium-, and long-disordered regions (LDRs), The out-of-sample prediction accuracies on a residue-by-residue basis ranged from 69 to 74% for the neural network predictors when applied to the same length class, but fell to 59 to 67% when applied to different length classes. Testing the rule-based predictor on a residue-by-residue basis using out-of-sample LDRs gave a success rate of 70%. Application of both the rule-based and LDR neural network predictors to large databases of protein sequences provide strong evidence that disordered regions are very common in nature. These results are consistent with our recent proposal that disordered regions are crucial for the evolution of molecular recognition.