Showing papers by "University of Georgia published in 1994"

Transactions, Volume, and Volatility

Abstract: We show that the positive volatility-volume relation documented by numerous researchers actually reflects the positive relation between volatility and the number of transactions. Thus, it is the occurrence of transactions per se, and not their size, that generates volatility; trade size has no information beyond that contained in the frequency of transactions. Our results suggest that theoretical research needs to entertain scenarios in which (1) both the frequency and size of trades are endogenously determined, yet (2) the size of trades has no information content beyond that contained in the number of transactions. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.

Water-Stable Aggregates and Organic Matter Fractions in Conventional- and No-Tillage Soils

Abstract: No-tillage (NT) practices can improve soil aggregation and change the distribution and retention of soil organic matter (SOM) compared with conventional tillage (CT), but the relationships between aggregates and SOM fractions are poorly known. The effects of long-term (13-yr) CT and NT management on water-stable aggregates (WSA) and aggregate-associated SOM were investigated on a Hiwassee sandy clay loam (clayey, kaolinitie, thermic Rhodic Kanhapludult). Samples were collected at two depths in replicated CT and NT plots and separated into five aggregate size classes by wet sieving. The stability of intact WSA was measured turbidimetrically. The C and N content of total, participate (POM), and mineral-associated organic matter was determined for each size class. Whole-soil organic C was 18% higher in NT (30.7 Mg C ha-») than in CT (26.1 Mg C ha"). In CT, macroaggregates (>250 um) were fewer and less stable than those of NT. The POM C made up = 36% of whole soil C regardless of tillage, but the quantity of POM was nearly 20% higher in NT than in CT. The POM comprised a higher percentage of total aggregate N in surface soils of NT than in CT and values increased with increases in aggregate size. In NT, concentrations of total and mineral-associated C and N were higher in the 106to 250-|im WSA than in the other size classes but, in CT, the concentrations were similar among size classes. An alternative view of aggregate organization is discussed in which microaggregates are formed in association with POM at the center of macroaggregates, helping to explain relationships between SOM storage and aggregate size distributions under different management practices. C of soils results in the disruption of soil aggregates and the loss of SOM compared with native sod and pasture soils (van Veen and Paul, 1981; Tisdall and Oades, 1982; Elliott, 1986; Kay, 1990). Under CT practices, plowing, harrowing, and rotary tillage result in mixing of the soil profile and the fragmentation and burial of crop residues. These effects tend to moderate the fluctuations of temperature and water in buried residues and increase their proximity to mineral nutrients, thereby enhancing residue decomposition and organic matter transformations (Blevins et al., 1984; Beare et al., 1992). With NT management, the soil is not plowed and crop residues accumulate on the soil surface as a mulch. Several studies have shown that if residues are not removed, NT management can improve soil aggregation and reduce losses of SOM that result from cultivation (Havlinetal., 1990; Carter, 1992; Weill et al,, 1989). However, other studies report few changes in soil aggregation (Hamblin, 1980) and no effects on SOM content other than changes in the depth distribution of SOM with plowing (Angers et al., 1992; Carter and Rennie, 1982). M.H. Beare, Inst. for Crop and Food Research (Lincoln), Private Bag 4704, Christchurch, New Zealand; and P.P. Hendrix, Dep. of Agronomy and Inst. of Ecology, and D.C. Coleman, Inst. of Ecology, Univ. of Georgia, Athens, GA 30602. Received 8 Mar. 1993. Corresponding author. Published in Soil Sci. Soc. Am. J. 58:777-786 (1994). Kaolinitie soils of the southeast USA are characterized by high dispersibility, a factor that may increase the susceptibility of cultivated soils to aggregate disruption, surface crusting, reduced infiltration, and erosion (Miller and Baharuddin, 1986; Sumner, 1992). In warm humid climatic regimes, these factors can contribute to rapid losses of SOM and a decline in the productivity of agricultural soils (Giddens, 1957; Bruce et al., 1990b; Sanchez et al., 1989). Many studies have investigated relationships between whole SOM and WSA (e.g., Chaney and Swift, 1984; Kemper and Koch, 1966; Angers et al., 1992), but relatively few have attempted to isolate and characterize the SOM associated with WSA (Dormaar, 1983; Baldock et al., 1987; Monrozier et al., 1991). Knowledge of aggregate-associated SOM may be important to understanding how changes in aggregation under different tillage and residue management practices contribute to the accumulation and loss of SOM (Elliott, 1986; Gupta and Germida, 1988). These relationships are largely unknown for soils of the southeastern USA. Furthermore, understanding these relationships is crucial for evaluating the applicability of the hierarchical model of aggregate organization (Tisdall and Oades, 1982) to a broader range of soils and management conditions. Both physical and chemical methods have been used to fractionate and characterize SOM. Although the limitations of these individual techniques are well known (Elliott and Cambardella, 1991; Duxbury et al., 1989), various combinations of physical and chemical separation techniques have been used to successfully characterize the chemical composition of primary organo-mineral particle-size fractions (Turchenek and Oades, 1979; Andersonetal., 1981; Tiessen and Stewart, 1983). Cambardella and Elliott (1992) recently described a simple method combining chemical dispersion with particle-size separation to isolate and subsequently characterize particulate and mineral-associated organic matter of native sod and agricultural soils from the Great Plains. Their results suggest that whole soil POM accounts for much of the SOM lost with cultivation of native sod and that NT practices can significantly reduce these losses. In this study, we combined wet-sieving techniques for the isolation of WSA with the chemical dispersion and physical separation methods of Cambardella and Elliott (1992) to investigate relationships between soil aggregation and the location and composition of aggregateassociated SOM in CT and NT soils. Our objectives were to describe the effects of long-term CT and NT management of a double-cropped soil on (i) the size Abbreviations: NT, no-tillage; SOM, soil organic matter; CT, conventional-tillage; WSA, water-stable aggregates; POM, paniculate organic matter; HSB, Horseshoe Bend Experimental Area; FLPOM, floating particulate organic matter; ASI, aggregate stability index; ANOVA, analysis of variance. 777 Published May, 1994

Aggregate-Protected and Unprotected Organic Matter Pools in Conventional- and No-Tillage Soils

Abstract: No-tillage (NT) practices can result in greater soil aggregation and higher soil organic matter (SOM) levels than conventional-tillage (CT) practices, but the mechanisms for these effects are poorly known. Our objectives were to describe the size and quality of biologically active pools of aggregate-associated SOM in long-term CT and NT soils of the southeastern USA. Samples were collected from replicated CT and NT plots on a Hiwassee sandy clay loam (clayey, kaolinitic, thermic Rhodic Kanhapludult) and separated into four aggregate size classes (>2000, 250-2000, 106-250, 53-106 m) by wet sieving. Potentially mineralizable C and N and N2O emissions were measured from 20-d laboratory incubations of intact and crushed macroaggregates (>250 m) and intact microaggregates (<250 m). Three primary pools of aggregate-associated SOM were quantified: unprotected, protected, and resistant C and N. Aggregate-unprotected pools of SOM were 21 to 65% higher in surface soils of NT than of CT, with greater differences in the macroaggregate size classes. Disruption of macroaggregates increased the mineralization of SOM in NT but had little effect in CT. Rates of mineralization from protected and unprotected pools of C were higher in surface soils of CT than of NT. Macroaggregateprotected SOM accounted for 18.8 and 19.1% of the total mineralizable C and N (0-15 cm), respectively, in NT but only 10.2 and 5.4% of the total mineralizable C and N in CT. Our results indicate that macroaggregates in NT soils provide an important mechanism for the protection of SOM that may otherwise be mineralized under CT practices.

Control of programmed cell death by the baculovirus genes p35 and iap.

Abstract: The SF-21 insect cell line undergoes rapid and widespread apoptosis when treated with actinomycin D or when infected with a mutant of the baculovirus Autographa californica nuclear polyhedrosis virus lacking a p35 gene or a functionally active iap (inhibitor of apoptosis) gene. Here we provide evidence that the basis for the induction of apoptosis by these two different stimuli is the cessation of RNA synthesis. We also show that expression of either p35 or two different functional iap homologs blocks apoptosis independently of other viral genes, indicating that these gene products act directly on the cellular apoptotic pathway. The iap genes encode a C3HC4 (or RING) finger motif found in a number of transcriptional regulatory proteins, as well as two additional Cys/His motifs (baculovirus iap repeats). We show that specific amino acids within both the C3HC4 finger and the N-terminal baculovirus iap repeat are critical for anti-apoptosis function. Overexpression of either mammalian bcl-2 or adenovirus E1B-19K, genes which block apoptosis when overexpressed in a number of mammalian cells, does not block actinomycin D-induced apoptosis in SF-21 cells.

An apoptosis-inhibiting gene from a nuclear polyhedrosis virus encoding a polypeptide with Cys/His sequence motifs.

Abstract: Two different baculovirus genes are known to be able to block apoptosis triggered upon infection of Spodoptera frugiperda cells with p35 mutants of the insect baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV):p35 (P35-encoding gene) of AcMNPV (R. J. Clem, M. Fechheimer, and L. K. Miller, Science 254:1388-1390, 1991) and iap (inhibitor of apoptosis gene) of Cydia pomonella granulosis virus (CpGV) (N. E. Crook, R. J. Clem, and L. K. Miller, J. Virol. 67:2168-2174, 1993). Using a genetic complementation assay to identify additional genes which inhibit apoptosis during infection with a p35 mutant, we have isolated a gene from Orgyia pseudotsugata NPV (OpMNPV) that was able to functionally substitute for AcMNPV p35. The nucleotide sequence of this gene, Op-iap, predicted a 30-kDa polypeptide product with approximately 58% amino acid sequence identity to the product of CpGV iap, Cp-IAP. Like Cp-IAP, the predicted product of Op-iap has a carboxy-terminal C3HC4 zinc finger-like motif. In addition, a pair of additional cysteine/histidine motifs were found in the N-terminal regions of both polypeptide sequences. Recombinant p35 mutant viruses carrying either Op-iap or Cp-iap appeared to have a normal phenotype in S. frugiperda cells. Thus, Cp-IAP and Op-IAP appear to be functionally analogous to P35 but are likely to block apoptosis by a different mechanism which may involve direct interaction with DNA.

A genetic linkage map of the bovine genome

Abstract: A cattle genetic linkage map was constructed which marks about 90% of the expected length of the cattle genome. Over 200 DNA polymorphisms were genotyped in cattle families which comprise 295 individuals in full sibling pedigrees. One hundred and seventy-one loci were found linked to one other locus. Twenty nine of the 30 chromosome pairs are represented by at least one of the 36 linkage groups. Less than a 50 cM difference was found in the male and female genetic maps. The conserved loci on this map show as many differences in gene order compared to humans as is found between humans and mice. The conservation is consistent with the patterns of karyotypic evolution found in the rodents, primates and artiodactyls. This map will be important for localizing quantitative trait loci and provides a basis for further mapping.

Asset Sales, Firm Performance, and the Agency Costs of Managerial Discretion

Abstract: We argue that management sells assets when doing so provides the cheapest funds to pursue its objectives rather than for operating efficiency reasons alone This hypothesis suggests that (1) firms selling assets have high leverage and/or poor performance, (2) a successful asset sale is good news and (3) the stock market discounts asset sale proceeds retained by the selling firm In support of this hypothesis, we find that the typical firm in our sample performs poorly before the sale and that the average stock-price reaction to asset sales is positive only when the proceeds are paid out

Extensin:repetitive motifs, functional sites, post-translational codes, and phylogeny

Abstract: Homologous hydroxyproline-rich glycoproteins (HRGPs) of the plant extracellular matrix include extensins, repetitive proline-rich proteins (RPRPs), some nodulins, gum arabic glycoprotein (GAGP), arabinogalactan-proteins (AGPs), and chimeric proteins such as potato lectin which contain an extensin module fused to a lectin. The key to the role of HRGPs in cell wall self-assembly and cell extension lies in their chemistry, which is dependent on extensive post-translational modifications (PTMs): hydroxylation, glycosylation, and cross-linking. Repetitive peptide motifs characterize HRGPs. One or more repetitive peptide motifs and their variants, singly or in combination, may constitute functional sites involved in various aspects of cell wall assembly, as follows: (i) X-Hypn including Ser-Hyp4 (arabinosylation site, molecular rigidity, and reptation). (ii) Pro-Hyp-Val-Tyr-Lys and variants (putative intermolecular cross-links, adhesion, cohesion, and possible beta-turns). (iii) Tyr-X-Tyr-Lys (intramolecular isodityrosine [IDT] cross-links increase molecular rigidity and hydrophobicity). (iv) (Glyco)peptide palindromes (centrosymmetric domains: putative self-assembly nucleation sites). (v) Ionic interaction sites (protein-protein and protein-carbohydrate cross-links). (vi) Hyp and Ser glycosylation sites (enhance conformational stability and molecular recognition). (vii) Extensin modules in chimeric proteins (e.g. solanaceous lectins). Rules for the post-translational modifications are emerging: (i) Hydroxylation of proline residues may depend on multiple, sequence-specific prolyl hydroxylases rather than on a single (polyproline-II) conformation-dependent enzyme. Furthermore, Lys-Pro, Tyr-Pro, and Phe-Pro are not hydroxylated, while Pro-Val is always. (ii) Contiguity of Hyp residues probably determines the extent of Hyp glycosylation, blocks of tetrahydroxyproline (Hyp4) being the most highly arabinosylated, while single non-contiguous Hyp residues are rarely arabinosylated, although they are likely attachment sites for the larger arabinogalactan substituents of gum arabic glycoprotein and arabinogalactan-proteins. (iii) While intramolecular cross-links involve IDT, unidentified intermolecular cross-links most likely involve the Val-Tyr-Lys motif (perhaps also Val-Lys-Pro-Tyr-His-Pro), probably as an adduct between Tyr and Lys catalyzed in vitro by a pI 4.6 extensin cross-linking peroxidase. Thus, we can classify HRGPs functionally as either cross-linking or non-cross-linking, i.e. CL- or NCL-extensins. Their protistan origin obscures the phylogenetic affinities of a single extensin-HRGP family due to their sequence divergence. We propose a phylogenetic series ranging from the minimally glycosylated basic RPRPs to the highly glycosylated acidic AGPs. Furthermore, based on similarities between dicots and gymnosperm extensins, and their marked difference from graminaceous monocot extensins, graminaceous monocot and dicot lines may have diverged as early as the progymnosperms.(ABSTRACT TRUNCATED AT 400 WORDS)

Nitrogen Uptake, Dissolved Organic Nitrogen Release, and New Production

Abstract: In oceanic, coastal, and estuarine environments, an average of 25 to 41 percent of the dissolved inorganic nitrogen (NH4+ and NO3–) taken up by phytoplankton is released as dissolved organic nitrogen (DON). Release rates for DON in oceanic systems range from 4 to 26 nanogram-atoms of nitrogen per liter per hour. Failure to account for the production of DON during nitrogen-15 uptake experiments results in an underestimate of gross nitrogen uptake rates and thus an underestimate of new and regenerated production. In these studies, traditional nitrogen-15 techniques were found to underestimate new and regenerated production by up to 74 and 50 percent, respectively. Total DON turnover times, estimated from DON release resulting from both NH4+ and NO3– uptake, were 10 ± 1, 18 ± 14, and 4 days for oceanic, coastal, and estuarine sites, respectively.

To Extend or Not to Extend: Success Determinants of Line Extensions:

Abstract: The authors study the determinants of line extension success using data on 75 line extensions of 34 cigarette brands over a 20-year period to investigate the relative effects of brand, extension, a...

Customer Expectations and Perceptions of Service Quality in Retail Apparel Specialty Stores

Abstract: Examines the differences between consumers′ expectations and perceptions of service quality they received when shopping apparel specialty stores. Also takes into account consumer demographic characteristics. Utilizes SERVQUAL scale and methodology developed by Parasuraman et al., (1991). Calculates gap scores by subtracting the expectation scores from the perception scores. Using a factor analysis procedure, four determinants of service quality emerged: (1) Personal Attention; (2) Reliability; (3) Tangibles; and (4) Convenience. Findings indicate greatest disparity between expectations and perceptions for the Personal Attention factor. Consumer demographic characteristics of race, marital status, and income provided significant differences between expectations and perceptions for Reliability and Convenience. Also considers the importance of service as a patronage criterion for apparel specialty store consumers. Indicates that service ranked third in importance behind merchandise assortment and price.

Hierarchical Decision Making in Stochastic Manufacturing Systems

Abstract: Most manufacturing systems are large, complex, and subject to uncertainty. Obtaining exact feedback policies to run these systems is nearly impossible, both theoretically and computationally. It is a common practice, therefore, to manage such systems in a hierarchical fashion. This book articulates a theory that shows that hierarchical decision making in the context of a goal-seeking manufacturing system can lead to near optimization of its objective. The approach in this book considers manufacturing systems in which events occur at different time scales. For example, changes in demand may occur far more slowly than breakdowns and repairs of production machines. This suggests that capital expansion decisions that respond to demand are relatively longer term than those decisions regarding production. Thus, long-term decisions such as those dealing with capital expansion can be based on the average existing production rapacity, and can be expected to be nearly optimal even though the short-term capacity fluctuations are ignored. Having the long-term decisions in hand, one can then solve the simpler problem of obtaining production rates. Increasingly complex and realistic models of manufacturing systems with failure-prone machines facing uncertain demands are formulated as stochastic optimal control problems. Partial characterization of their solutions is provided when possible along with their hierarchical decomposition based on event frequencies. In the latter case, multilevel decisions are constructed in the manner described above and these decisions are shown to be asymptotically optimal as the average time between successive short-term events becomes much smaller than that between successive long-term events. Much attention is given to establish that the order of deviation of the cost of the hierarchical solution from the optimal cost is small. The striking novelty of the approach is that this is done without solving for the optimal solution, which as stated earlier is an insurmountable task. This approach presents a paradigm in convex production planning, whose roots go back to the classical work of Arrow, Karlin and Scarf (1958). It also represents a new research direction in control theory. Finally, the material covered in the book cuts across the disciplines of Operations Management, Operations Research, System and Control theory, Industrial Engineering, Probability and Statistics, and Applied Mathematics. It is anticipated that the book would encourage development of new models and techniques in these disciplines.

Oligosaccharins: structures and signal transduction.

Abstract: Oligosaccharins are complex carbohydrates that can function in plants as molecular signals that regulate growth, development, and survival in the environment [3]. Studies of plant-microorganism interactions yielded the first evidence that oligosaccharins could serve as biological signals. Much of this research focused on the synthesis and accumulation of antimicrobial phytoalexins in response to microbial attack. Phytoalexin synthesis and accumulation are observed not only after microbial infection, but also after treatment of plant tissue with cell-free extracts of microbial origin. The active components in these extracts are commonly referred to as ‘elicitors’. The term ‘elicitor’ was originally used to refer to molecules and other stimuli that induce the synthesis and accumulation of phytoalexins in plant cells [130], but is now commonly used for molecules that stimulate any plant defense mechanism [68, 70, 71, 104].

Stowaway: a new family of inverted repeat elements associated with the genes of both monocotyledonous and dicotyledonous plants.

Abstract: Members of a new inverted repeat element family, named Stowaway, have been found in close association with more than 40 monocotyledonous and dicotyledonous plant genes listed in the GenBank and EMBL nucleic acid data bases. Stowaway elements are characterized by a conserved terminal inverted repeat, small size, target site specificity (TA), and potential to form stable DNA secondary structures. Some elements are located at the extreme 3' ends of sequenced cDNAs and supply polyadenylation signals to their host genes. Other elements are in the 5' upstream regions of severa1 genes and appear to contain previously identlfied cis-acting regulatory domains. Although the Stowaway elements share many structural features with the recently discovered Tourist elements, the two families share no significant sequence similarity. Together, the Stowaway and Tourist families serve to define an important new class of short inverted repeat elements found in possibly all flowering plant genomes.

Latitudinal patterns in leaf litter breakdown: is temperature really important?

Abstract: SUMMARY 1. Forest stream food webs depend largely on input of dead riparian zone leaves for their energy, which is converted into living biomass by microbes, macroinvertebrates and fish. 2. Temperature has been invoked as important in controlling breakdown rates, and aquatic biologists have suggested that by normalizing processing rates to degree days rather than days, one can ‘factor out’ the effect of temperature and compare processing rates in streams with different thermal regimes (e.g. different seasons or study sites in different biomes). 3. We examined processing rates (k) along a latitudinal (i.e. thermal) gradient by using reciprocal transplants of leafpacks. We placed leafpacks of ten tree species (representing a large range of leaf litter quality) in streams in Costa Rica, Michigan and Alaska using coarse-mesh (20mm) litter bags. We then examined both the ‘per day’(kday) and ‘per degree day’ (kdegree day) models of leaf litter processing. While processing rates (per day) were fastest at the Costa Rica site (as expected), rates at the Alaska and Michigan sites were similar to each other, which we would not predict if temperature were the principal factor controlling breakdown rate. If using degree days eliminates any effect of differing thermal regimes, rates should be similar across latitudes; however, rates at the Alaska site were much faster (per degree day) than rates at the sites in Costa Rica and Michigan. 4. We compared our data with studies in the North American literature. Regression analysis of kday and kdegree day against latitude of the study site revealed that processing rates (kday) of leaves (from a wide range of tree species in a wide range of stream types) showed no significant change with increasing latitude. However, when normalized for temperature (kDegree day), a positive correlation was found between processing rates and latitude, causing us to reject the hypothesis that normalizing processing rates to cumulative degree days removes the effect of temperature. 5. We suggest three hypotheses: (i) shredding insect populations have adapted to the local thermal regime, and invertebrate-mediated processing rates are either similar between regions (showing no latitudinal pattern), or increase with latitude; (ii) microbial populations are less active at colder temperatures, and the rate of microbially mediated processing of leaf litter will show a decrease with latitude, and consequently (iii) the relative importance of invertebrate v microbial processing changes on a latitudinal gradient, with invertebrates being more important at high latitudes.

Molecular mechanics parameters

Abstract: A general scheme for choosing unknown parameters for use in the MM2 and MM3 force fields is discussed, and implemented in the form of a computer program.

Statistical Relationships between Topography and Precipitation Patterns

Abstract: Statistical relationships between topography and the spatial distribution of mean annual precipitation are developed for ten distinct mountainous regions. These relationships are derived through linear bivariate and multivariate analyses, using six topographic variables as predictors of precipitation. These predictors are elevation, slope, orientation, exposure, the product (or interaction) of slope and orientation, and the product of elevation and exposure. The two interactive terms are the best overall bivariate predictors of mean annual precipitation, whereas orientation and exposure are the strongest noninteractive bivariate predictors. The regression equations in many of the climatically similar regions tend to have similar slope coefficients and similar y-intercept values, indicating that local climatic conditions strongly influence the relationship between topography and the spatial distribution of precipitation. In contrast, the regression equations for the tropical and extratropical regi...

Retrotransposons in the flanking regions of normal plant genes: a role for copia-like elements in the evolution of gene structure and expression

Abstract: The wx-K mutation results from the insertion of a copia-like retrotransposon into exon 12 of the maize waxy gene. This retrotransposon, named Hopscotch, has one long open reading frame encoding all of the domains required for transposition. Computer-assisted database searches using Hopscotch and other plant copia-like retroelements as query sequences have revealed that ancient, degenerate retrotransposon insertions are found in close proximity to 21 previously sequenced plant genes. The data suggest that these elements may be involved in gene duplication and the regulation of gene expression. Similar searches using the Drosophila retrotransposon copia did not reveal any retrotransposon-like sequences in the flanking regions of animal genes. These results, together with the recent finding that reverse-transcriptase sequences characteristic of copia-like elements are ubiquitous and diverse in plants, suggest that copia-like retrotransposons are an ancient component of plant genomes.

Reading and Writing to Learn Science: Achieving Scientific Literacy.

Abstract: A key step in helping students to achieve scientific literacy is to ensure that each school's curriculum supports students' efforts to learn science meaningfully. Educational researchers play a vital role in this step by providing teachers, teacher educators, administrators, and policy makers with information about the creation of a curriculum that supports scientific literacy. In a scientific literacy curriculum, reading and writing can serve as dynamic vehicles for learning science meaningfully. The task of educational researchers is to show how reading and writing can be used most effectively to support science learning. Much of what is done now in schools is based on teacher intuition—good intuition—but intuition nonetheless. What is needed is school-based research to validate and build upon these intuitions. This article is intended to stimulate research on reading and writing to learn science.

The Aspergillus nidulans abaA gene encodes a transcriptional activator that acts as a genetic switch to control development.

Abstract: The Aspergillus nidulans abaA gene encodes a protein containing an ATTS DNA-binding motif and is required for the terminal stages of conidiophore development. Results from gel mobility shift and protection, missing-contact, and interference footprint assays showed that AbaA binds to the sequence 5'-CATTCY-3', where Y is a pyrimidine, making both major- and minor-groove contacts. Multiple AbaA binding sites are present in the cis-acting regulatory regions of several developmentally controlled structural genes as well as those of the upstream regulatory gene brlA, the downstream regulatory gene wetA, and abaA itself. These cis-acting regulatory regions confer AbaA-dependent transcriptional activation in a heterologous Saccharomyces cerevisiae gene expression system. From these observations, we propose that the AbaA transcription factor establishes a novel set of feedback regulatory loops responsible for determination of conidiophore development.