Variation in maternal and anxiety-like behavior associated with discrete patterns of oxytocin and vasopressin 1a receptor density in the lateral septum.

The relationship between anxiety and maternal behavior has been explored across species using a variety of approaches, yet there is no clear consensus on the nature or direction of this relationship. In the current study, we have assessed stable individual differences in anxiety-like behavior in a large cohort (n=57) of female F2 hybrid mice. Using open-field behavior as a continuous and categorical (high vs. low) measure we examined the relationship between the anxiety-like behavior of virgin F2 females and the subsequent maternal behavior of these females. In addition, we quantified oxytocin (OTR) and vasopressin (V1a) receptor density within the lateral septum to determine the possible correlation with anxiety-like and maternal behavior. We find that, though activity levels within the open-field do predict latency to engage in pup retrieval, anxiety-like measures on this test are otherwise not associated with subsequent maternal behavior. OTR density in the dorsal lateral septum was found to be negatively correlated with activity levels in the open-field and positively correlated with frequency of nursing behavior. V1a receptor density was significantly correlated with postpartum licking/grooming of pups. Though we do not find support for the hypothesis that individual differences in trait anxiety predict variation in maternal behavior, we do find evidence for the role of OTR and V1a receptors in predicting maternal behavior in mice and suggest possible methodological issues (such as distinguishing between trait and state anxiety) that will be a critical consideration for subsequent studies of the anxiety-maternal behavior relationship. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

The challenge of early surgery for cryptorchidism.

OBJECTIVE: In congenital cryptorchidism, a recent Nordic Consensus report recommends surgical correction at 6-12 months of age to prevent male infertility. In published series of orchiopexies the median age at surgery is often 3 years or more. The aim of this study was to evaluate whether early surgery is technically safe. MATERIAL AND METHODS: The study included 356 boys with 418 orchiopexies and median 1 year of follow-up. RESULTS: At follow-up 367 testes were in the scrotum without iatrogenic atrophy. Eight testes were atrophied and in 43 cases a redo operation was performed to achieve a scrotal position of the testis. All acquired undescended testes had a successful result. The age at operation for the group with congenital undescended testes in the intracanalicular position or in a position close to the external inguinal annulus was 4 months to 14.5 years. In the latter group the median age at operation for the 41 failures was 2 years and 4 months, which is significantly younger than the median age for the more successful operations (3 years and 9 months). CONCLUSION: The standard orchiopexy is technically demanding in small boys. Focus on successful operative results in specialist centres is important when treating cryptorchidism with early surgery, otherwise the positive beneficial biological impact on fertility potential may be lost due to treatment failure.

Social influences on neurobiology and behavior: epigenetic effects during development.

The quality of the social environment can have profound influences on the development and activity of neural systems with implications for numerous behavioral and physiological responses, including the expression of emotionality. Though social experiences occurring early in development may be particularly influential on the developing brain, there is continued plasticity within these neural circuits amongst juveniles and into early adulthood. In this review, we explore the evidence derived from studies in rodents which illustrates the social modulation during development of neural systems, with a particular emphasis on those systems in which a long-term effect is observed. One possible explanation for the persistence of dynamic changes in these systems in response to the environment is the involvement of epigenetic mechanisms, and here we discuss recent studies which support the role of these mechanisms in mediating the link between social experiences, gene expression, neurobiological changes, and behavioral variation. This literature raises critical questions about the interaction between neural systems, the concordance between neural and behavioral changes, sexual dimorphism in effects, the importance of considering individual differences in response to the social environment, and the potential of an epigenetic perspective in advancing our understanding of the pathways leading to variations in mental health.

Anomalously high radon concentrations in dwellings located on permeable glacial sediments.

Indoor radon concentrations were measured in different seasons in 104 dwellings located on a highly permeable ice-marginal moraine in Kinsarvik, Western Norway. The measurements revealed the highest indoor radon levels ever detected in Norway and extreme variations in seasonal and short-term indoor radon levels. Annual average indoor radon concentrations up to 56 000 Bq m(-3) and a mean value of 4340 Bq m(-3) for the whole residential area are reported. By using the ICRP conversion factors to effective dose, these indoor radon values correspond to a total annual effective dose of 930 mSv and 72 mSv, respectively. By using the conversion as recommended by UNSCEAR, the effective doses would be about 50% higher. The indoor radon concentrations are found to be strongly influenced by thermally induced flows of radon-bearing soil air directed towards the upper part of the ice-marginal deposit in winter and towards the area of lowest elevation in summer. The pattern of seasonal variations observed suggests that in areas where thermal convection may occur, annual average indoor radon levels should be derived from measurements performed both in summer and in winter.

Control of oral biofilm formation by an antimicrobial decapeptide.

Oral biofilms are mixed-species microbial communities, and their uncontrolled outgrowth can express as oral diseases. Antimicrobial peptides represent alternative classes of antimicrobials that exhibit selectivity for prokaryotes. We wanted to test the effect of a synthetic decapeptide antimicrobial, KSL, on the development of oral biofilms formed by isolated human salivary bacteria. We used differential interference contrast microscopy, coupled with a dual-flow cell system, to determine the effect of KSL on oral biofilm development. We used reductions of viable counts and confocal microscopy to assess the bactericidal activity of KSL on mature oral biofilms. KSL effectively blocked biofilm development. A significant effect on the viability of mature biofilms was observed when KSL was used in the presence of a surface-active agent, or after biofilms were mechanically disrupted. This study shows that KSL may be a useful adjunct for conventional oral hygiene to prevent plaque-mediated dental diseases.

Simultaneous inactivation of the wprA and dltB genes of Bacillus subtilis reduces the yield of alpha-amylase.

AIMS: In Gram-positive bacteria, signal peptide-bearing secretory proteins are translocated through the cytoplasmic membrane and fold into their native conformation on the outside of the cell. The products of the Bacillus subtilis wprA and dltB genes separately influence post-translocational stages of the secretion process by mediating proteolytic degradation and folding of secretory proteins. Inactivation of either wprA or dltB in B. subtilis increases the yield of secretory proteins released into the culture medium in an intact and biologically active conformation. The aim of this work was to study the combined influence of these genes. METHODS AND RESULTS: A wprA/dltB double mutant was constructed, but did not have an additive effect on secretion and caused a significant reduction in the yield of alpha-amylase. CONCLUSIONS AND SIGNIFICANCE: The activities of the wprA gene and the dlt operon interact in a negative way to influence the growth cycle and protein secretion. The mechanism by which this may occur, and its potential significance for the secretion of native and non-native proteins from B. subtilis and related bacteria, is discussed.

Relationship between omega3 long-chain polyunsaturated fatty acid status during early infancy and neurodevelopmental status at 1 year of age.

OBJECTIVE: To determine the influence of alpha-linolenic acid (ALA; 18 : 3omega3) intake and, hence, the influence of plasma and/or erythrocyte phospholipid content of docosahexaenoic acid (DHA; 22 : 6omega3) during early infancy on neurodevelopmental outcome of term infants. METHODS: The Bayley Scales of Infant Development (second edition), the Clinical Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) and the Gross Motor Scale of the Revised Gesell Developmental Inventory were administered at a mean age of 12.26 +/- 0.94 months to 44 normal term infants enrolled in a study evaluating the effects of infant formulas differing only in ALA content (0.4, 1.0, 1.7 and 3.2% of total fatty acids). RESULTS: As reported previously [Jensen et al., Lipids 13 (1996) 107; J. Pediatr. 131 (1997) 200], the group fed the formula with the lowest ALA content had the lowest mean plasma and erythrocyte phospholipid DHA contents at 4 months of age. This group also had the lowest mean score on every neurodevelopmental measure. The difference in mean gross motor developmental quotient of this group versus the group fed the formula with 1.0% ALA but not of the other groups was statistically significant (P < 0.05). Across the groups, motor indices correlated positively with each other and with the plasma phospholipid DHA content at 4 months of age (P=0.02-0.03). The CLAMS developmental quotient correlated with the erythrocyte phospholipid content of 20 : 5omega3 (P < 0.01) but not with DHA. CONCLUSIONS: These statistically significant correlations suggest that the omega3 fatty acid status during early infancy may be important with respect to neurodevelopmental status at 1 year of age and highlight the need for further studies of this possibility.

A randomized, double-blind, placebo-controlled trial of docosahexaenoic acid supplementation in children with attention-deficit/hyperactivity disorder.

OBJECTIVE: To determine whether docosahexaenoic acid (DHA) supplementation for 4 months decreases the symptoms of attention-deficit/hyperactivity disorder (ADHD). STUDY DESIGN: Sixty-three 6- to-12-year-old children with ADHD, all receiving effective maintenance therapy with stimulant medication, were assigned randomly, in a double-blind fashion, to receive DHA supplementation (345 mg/d) or placebo for 4 months. Outcome variables included plasma phospholipid fatty acid patterns, scores on laboratory measures of inattention and impulsivity (Test of Variables of Attention, Children's Color Trails test) while not taking stimulant medication, and scores on parental behavioral rating scales (Child Behavior Checklist, Conners' Rating Scale). Differences between groups after 4 months of DHA supplementation or placebo administration were determined by analysis of variance, controlling for age, baseline value of each outcome variable, ethnicity, and ADHD subtype. RESULTS: Plasma phospholipid DHA content of the DHA-supplemented group was 2.6-fold higher at the end of the study than that of the placebo group (4.85 +/- 1.35 vs 1.86 +/- 0.87 mol % of total fatty acids; P <.001). Despite this, there was no statistically significant improvement in any objective or subjective measure of ADHD symptoms. CONCLUSION: A 4-month period of DHA supplementation (345 mg/d) does not decrease symptoms of ADHD.

Internal consistency, temporal stability, and reproducibility of individual index scores of the Test of Variables of Attention in children with attention-deficit/hyperactivity disorder.

Psychometric properties of the Test of Variables of Attention (TOVA) were examined in a cohort of children (n=63) strictly diagnosed with attention-deficit/hyperactivity disorder (AD/HD). Internal consistency was assessed via correlational analyses to determine the degree of agreement among various test portions. The temporal stability of errors of omission, errors of commission, response time, and response time variability was evaluated using test-retest reliability. Reproducibility of individual scores for the same indices was assessed using the Bland-Altman procedure. Select TOVA index scores exhibited high internal consistency in this cohort. Although the temporal stability of group scores (test-retest reliability) was satisfactory, individual test scores were less reproducible. Temporal stability and individual test-retest score agreement were greater for response time and response time variability than for errors of omission and errors of commission.

The influence of secretory-protein charge on late stages of secretion from the Gram-positive bacterium Bacillus subtilis.

Following their secretion across the cytoplasmic membrane, processed secretory proteins of Bacillus subtilis must fold into their native conformation prior to translocation through the cell wall and release into the culture medium. The rate and efficiency of folding are critical in determining the yields of intact secretory proteins. The B. subtilis membrane is surrounded by a thick cell wall comprising a heteropolymeric matrix of peptidoglycan and anionic polymers. The latter confer a high density of negative charge on the wall, endowing it with ion-exchange properties, and secretory proteins destined for the culture medium must traverse the wall as the last stage in the export process. To determine the influence of charge on late stages in the secretion of proteins from this bacterium, we have used sequence data from two related alpha-amylases, to engineer the net charge of AmyL, an alpha-amylase from Bacillus licheniformis that is normally secreted efficiently from B. subtilis. While AmyL has a pI of 7.0, chimaeric enzymes with pI values of 5.0 and 10.0 were produced and characterized. Despite the engineered changes to their physico-chemical properties, the chimaeric enzymes retained many of the enzymic characteristics of AmyL. We show that the positively charged protein interacts with the cell wall in a manner that influences its secretion.

Effect of docosahexaenoic acid supplementation of lactating women on the fatty acid composition of breast milk lipids and maternal and infant plasma phospholipids.

To determine whether docosahexaenoic acid (DHA) supplementation of breast-feeding mothers increases the DHA contents of breast milk and infant plasma phospholipids (PPs), breast-feeding women were randomly assigned to 3 DHA-supplementation groups (170-260 mg/d) or a control group. Group 1 (n = 6) consumed an algae-produced high-DHA triacylglycerol; group 2 (n = 6) consumed high-DHA eggs; group 3 (n = 6) consumed a high-DHA, low-eicosapentaenoic acid marine oil; and group 4 (n = 6) received no supplementation. From before to after supplementation (2 and 8 wk postpartum), mean (+/-SD) maternal PP DHA increased in groups 1, 2, and 3 by 1.20 +/- 0.53, 0.63 +/- 0.82, and 0.76 +/- 0.35 mol% of fatty acids, respectively (23-41%), but decreased in group 4 by 0.44 +/- 0.34 mol% (15%). Breast-milk DHA of groups 1, 2, and 3 increased by 0.21 +/- 0.16, 0.07 +/- 0.11, and 0. 12 +/- 0.07 mol%, respectively (32-91%) but decreased in group 4 by 0.03 +/- 0.04 mol% (17%). Mean infant PP DHA in groups 1, 2, and 3 increased by 1.63 +/- 0.79, 0.40 +/- 1.0, and 0.98 +/- 0.61 mol%, respectively (11-42%), but only by 0.18 +/- 0.74 mol% (5%) in group 4. Correlations between the DHA contents of maternal plasma and breast milk and of milk and infant PPs were significant. Breast-milk and maternal and infant PP 22:5n-6 concentrations were lowest in group 2. DHA supplementation increases the plasma and breast-milk DHA concentrations of lactating women, resulting in higher PP DHA concentrations in infants.

Evaluation of methods for assessing visual function of infants.

PURPOSE: Commonly used behavioral and electrical testing methods for estimation of visual acuity and visual function in infants yield different estimates and may not accurately predict visual acuity and visual function in later life. Moreover, neither test-retest variability nor side-by-side comparisons of the various methods have been thoroughly evaluated in the same infant population. The purpose of this study was to provide such an evaluation. METHOD: The test-retest variability of visual acuity and visual function was evaluated for the Teller Acuity Card (TAC) procedure, sweep visual evoked potential (VEP), as well as latency and amplitude measured by transient pattern VEP. Groups of approximately 20 infants contributed test-retest data. Visual function estimated by the various methods in a larger group of infants (n = 118) was compared. Correlations between methods and the validity of the various methods to detect maturational changes between 4 and 8 months of age were also assessed. Administration of these tests was according to standard and usual procedures. RESULTS: The average percent difference between test and retest estimates of acuity as well as the SD was lowest for transient VEP latency (3%, 7% SD). The other methods were markedly more variable: sweep VEP (2%, 22% SD), TAC procedure (8%, 20% SD), and transient VEP amplitude (7.5%, 39% SD). Average coefficients of variation showed a similar trend: transient VEP latency, 8%; sweep VEP, 15%; TACs, 30%; and transient amplitude, 53%. Correlations among estimates by the methods were poor, but expected changes in visual maturation from 4 to 8 months of age were detected with all methods. CONCLUSIONS: All methods evaluated provide valid and reliable test-retest data for a group, but are less valid for estimating visual acuity and visual function of an individual subject. The poor correlations between any 2 of the testing methods suggest that each test assesses a different aspect of vision. Nonetheless, expected maturational changes between 4 and 8 months of age were readily detectable by all methods evaluated.

Myelodysplastic syndrome with hypereosinophilia and a nonrandom chromosomal abnormality dic(1;7): confirmation of eosinophil clonal involvement by fluorescence in situ hybridization.

We report a case of de novo myelodysplastic syndrome (MDS) with hypereosinophilia and dic(1;7) in which eosinophil clonal involvement was confirmed by fluorescence in situ hybridization. There have been two previous reports in the literature of eosinophilic MDS with dic(1;7) or t(1;7) in which eosinophil clonality was demonstrated. The specific breakpoints on chromosomes 1 and 7 differ in the three cases, making it difficult to implicate disruption of a single gene as causative; nevertheless, the nonrandom occurrence of t(1;7) or dic(1;7) with malignant eosinophilic proliferations suggests that this chromosomal rearrangement is involved in the etiology of the disease.

Effect of dietary linoleic/alpha-linolenic acid ratio on growth and visual function of term infants.

OBJECTIVES: To determine the effect of alpha-linolenic acid (ALA) intake (or the dietary linoleic acid [LA]/ALA ratio) on the growth and visual function of term infants. STUDY DESIGN: Normal term infants were assigned randomly and in masked fashion at birth to receive formulas with approximately 16% of total fatty acids as LA and 0.4%, 1.0%, 1.7%, or 3.2% of fatty acids as ALA (LA/ALA ratios of 44, 18.2, 9.7, and 4.8) for the first 4 months of life. The fatty acid pattern of plasma phospholipids was determined shortly after birth and at approximately 21, 60, and 120 days of age. Anthropometric data were obtained at the same times and also at approximately 240 days of age. Transient visual evoked responses (VERs) were measured at approximately 120 and 240 days of age. For comparisons, anthropometric and VER data also were obtained in infants who were exclusively breast-fed for the first 4 months of life. RESULTS: Infants who received the formula with 3.2% ALA (LA/ALA ratio, 4.8) had higher plasma concentrations of phospholipid docosahexaenoic acid (DHA) but lower concentrations of arachidonic acid at 21, 60, and 120 days of age. Mean weight of this group at 120 days of age was 760 gm less (p < 0.05) than the mean weight of the group that received the formula with 0.4% ALA (LA/ALA ratio, 44). Despite differences in plasma phospholipid DHA contents among groups, neither VER latency nor amplitude differed significantly among formula groups or between any formula group and age-matched, breast-fed infants. CONCLUSIONS: The highest versus the lowest ALA intake (or the lowest vs the highest LA/ALA ratio) resulted in higher plasma phospholipid DHA content from 21 to 120 days of age but was not associated with improved visual function as assessed by transient VER. Moreover, mean body weight of infants who received the highest versus lowest ALA intake was less at 120 days (p < 0.05). These data suggest that the lower LA/ALA ratios currently recommended for infant formulas should not be adopted until the effect of such ratios on growth are evaluated more completely.

New insights into the metabolism of long chain polyunsaturated fatty acids during infancy.

Data obtained with stable isotope methodology have demonstrated that preterm and term infants can convert LA and ALA, respectively, to AA and DHA. In addition, they have clarified the pathways by which infants convert LA and ALA to LCPUFA and have demonstrated the importance of factors such as the dietary LA/ALA ratio and postnatal age on biosynthesis of AA and DHA. Further work is needed to clarify the role of other influential factors on endogenous synthesis of LCPUFA and to determine the absolute amounts of endogenous LCPUFA synthesis. Such data are necessary to define more precisely the LCPUFA requirements of growing infants.

Intermediates in endogenous synthesis of C22:6 omega 3 and C20:4 omega 6 by term and preterm infants.

An alternative pathway of omega 3 and omega 6 fatty acid metabolism has been described in isolated rate hepatocytes and human fibroblasts. This alternative pathway, which is independent of delta 4 desaturation, involves elongation of C22 5 omega 3 and C22:4 omega 6 to C24 fatty acids, delta 6 desaturation of the C24 fatty acids and subsequent beta oxidation of the desaturated products to C22:6 omega 3 and C22:5 omega 6. To determine whether this alternative pathway is operative in the human infant and also to obtain additional information concerning endogenous conversion of C18:3 omega 3 and C18:2 omega 6 to longer chain more unsaturated fatty acids, presence of [M + 18] isotopomers of omega 3 and omega 6 fatty acids in the plasma phospholipid fraction of term and preterm infants after administration of [U-13C]18:3 omega 3 and [U-13C]18:2 omega 6 was determined by negative chemical ionization gas chromatography/mass spectrometry. [M + 18] isotopomers of the following omega 3 fatty acids were detected: C18:3, C18:4, C20:3, C20:4, C20:5, C22:4, C22:5, C22:6, C24:4 (two infants only), C24:5, and C24:6. [M + 18] isotopomers of omega 6 fatty acids detected included only C18:2, C18:3, C20:2, C20:3, and C20:4, but sensitivity was insufficient to detect [M + 18] isotopomers of C22 and C24 omega 6 fatty acids. Presence of [M + 18] isotopomers of C24:5 omega 3 and C24:6 omega 3 indicates that these fatty acids were synthesized endogenously from C18:3 omega 3. This plus the in vitro data strongly suggests that infants use the recently described alternative pathway in endogenous synthesis of C22:6 omega 3. However, involvement also of delta 4 desaturation cannot be excluded. Detection of [M + 18] isotopomers of C20:3 omega 3, C20:2 omega 6, and C22:4 omega 3 suggests that C18:3 omega 3, C18:2 omega 6, and C20:4 omega 3 are elongated as well as desaturated. The specific fate of these elongation products and their importance in endogenous synthesis of omega 3 and omega 6 long chain polyunsaturated fatty acids remain to be determined.

Effect of dietary alpha-linolenic acid intake on incorporation of docosahexaenoic and arachidonic acids into plasma phospholipids of term infants.

The fractional conversion rates of plasma phospholipid alpha-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) to docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6), respectively, and the fractional rates of incorporation of 22:6n-3 and 20:4n-6 into plasma phospholipids were determined in 27 healthy 3-wk-old term infants who had received formulas with approximately 16% of fat as 18:2n-6 and 0.4% (n = 6), 1.0% (n = 11), or 3.2% (n = 10) as 18:3n-3 from birth. The infants were given a single dose of both [U-13C] 18:2n-6 and [U-13C] 18:3n-3 with a feeding, and blood samples were collected 8, 12, and 24 h afterward for determination of the isotopic enrichments of the [M + 18] isotopomers of plasma phospholipid fatty acids by negative chemical ionization gas chromatography/mass spectrometry. A simple precursor/product compartmental model was used to estimate fractional rates of conversion and incorporation. All infants converted 18:3n-3 to 22:6n-3 and 18:2n-6 to 20:4n-6. Although the fractional rate of conversion of 18:3n-3 to 22:6n-3 did not differ among groups, the fractional rate of incorporation of 22:6n-3 into the plasma phospholipid fraction was greater in infants who received 3.2% vs. 0.4% or 1.0% 18:3n-3 (4.1 +/- 2.2 vs. 1.6 +/- 1.5 or 2.0 +/- 1.0% of the plasma phospholipid 22:6n-3 pool daily). The fractional rate of conversion of 18:2n-6 to 20:4n-6 was less in infants who received the 3.2% 18:3n-3 intake (0.4 +/- 0.3% of the plasma phospholipid 18:2n-6 pool daily vs. 1.1 +/- 0.7% and 0.8 +/- 0.5% in those who received 0.4 and 1.0% 18:3n-3, respectively). The fractional rate of incorporation of 20:4n-6 into plasma phospholipid also was less in the 3.2% vs. the 0.4 and 1.0% 18:3n-3 groups (2.7 +/- 1.4% vs. 5.9 +/- 2.6 and 4.4 +/- 1.7%, respectively, of the plasma phospholipid 20:4n-6 pool daily).

Biochemical effects of dietary linoleic/alpha-linolenic acid ratio in term infants.

Recent statements concerning linoleic (LA) and alpha-linolenic acid (LNA) intakes for infants include a desirable range of LA/LNA ratios. To evaluate several dietary LA/LNA ratios, the fatty acid patterns of plasma and erythrocyte phospholipid fractions, as well as plasma total lipid fractions, were determined shortly after birth and at 21, 60, and 120 d of age in term infants fed formula with 16% of fat as LA and either 0.4, 0.95, 1.7, or 3.2% as LNA (LA/LNA ratios of approximately 44, 18, 10, and 5). The content of all n-3 fatty acids in both plasma fractions was higher at all times in infants who received the highest LNA intake; however, the docosahexaenoic acid (DHA) content was only half that shortly after birth or reported in breast-fed infants of comparable ages. The LA content of plasma lipids of all groups was higher at all times than shortly after birth but did not differ among groups. The arachidonic acid (AA) content was higher in infants who received the lowest LNA intake, but only half that at birth or reported in breast-fed infants. In contrast, the DHA content of the erythrocyte phospholipid fraction did not differ among groups until 120 d of age when it was higher in those who received the highest LNA intake and the AA content of this fraction did not differ among groups at any time. These data demonstrate that dietary LA/LNA ratios between 5 and 44 do not result in plasma or erythrocyte lipid levels of DHA or plasma lipid levels of AA similar to those at birth or reported by others in breast-fed infants. However, the data indicate that the LA/LNA ratio of the formula is an important determinant of the amounts of DHA and AA required to achieve plasma and erythrocyte levels of these fatty acids similar to those of breast-fed infants.

Isolation and characterization of Bacillus subtilis genomic lacZ fusions induced during partial purine starvation.

Random genomic Bacillus subtilis lacZ fusions were screened in order to identify the possible existence of regulons responding to the stimuli generated by partial purine starvation. A leaky pur mutation (purL8) was isolated and used to generate the partial purine starvation conditions in the host strain used for screening. On the basis of their induction during partial purine starvation, seven genomic lacZ fusions were isolated. None of the fusions map in loci previously reported to contain purine-regulated genes. One fusion maps very close to the citB locus and may very well be a citB fusion. The fusions were divided into two types on the basis of their response to complete starvation for either ATP or GTP or both components at the same time. Except for one, type 2 fusions were induced by specific starvation for ATP and by simultaneous starvation for ATP and GTP, but not by specific GTP starvation in a gua strain or by GTP starvation induced by the addition of decoyinine. Type 1 fusions were equally well induced by all three kinds of purine starvation including GTP starvation induced by decoyinine. Further subdivisions of the fusions were obtained on the basis of their responses to the spo0A gene product. A total of five fusions showed that spo0A affected expression. One class was unable to induce lacZ expression in the absence of the spo0A gene product, whereas the other class had increased lacZ expression during partial purine starvation in a spo0A background.