Diversity and abundance of the abnormal chromosome 10 meiotic drive complex in Zea mays.

Maize Abnormal chromosome 10 (Ab10) contains a classic meiotic drive system that exploits the asymmetry of meiosis to preferentially transmit itself and other chromosomes containing specialized heterochromatic regions called knobs. The structure and diversity of the Ab10 meiotic drive haplotype is poorly understood. We developed a bacterial artificial chromosome (BAC) library from an Ab10 line and used the data to develop sequence-based markers, focusing on the proximal portion of the haplotype that shows partial homology to normal chromosome 10. These molecular and additional cytological data demonstrate that two previously identified Ab10 variants (Ab10-I and Ab10-II) share a common origin. Dominant PCR markers were used with fluorescence in situ hybridization to assay 160 diverse teosinte and maize landrace populations from across the Americas, resulting in the identification of a previously unknown but prevalent form of Ab10 (Ab10-III). We find that Ab10 occurs in at least 75% of teosinte populations at a mean frequency of 15%. Ab10 was also found in 13% of the maize landraces, but does not appear to be fixed in any wild or cultivated population. Quantitative analyses suggest that the abundance and distribution of Ab10 is governed by a complex combination of intrinsic fitness effects as well as extrinsic environmental variability.

Transgenes in Mexican maize: molecular evidence and methodological considerations for GMO detection in landrace populations.

A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces.

Parallelism and convergence in post-domestication adaptation in cereal grasses.

The selection of desirable traits in crops during domestication has been well studied. Many crops share a suite of modified phenotypic characteristics collectively known as the domestication syndrome. In this sense, crops have convergently evolved. Previous work has demonstrated that, at least in some instances, convergence for domestication traits has been achieved through parallel molecular means. However, both demography and selection during domestication may have placed limits on evolutionary potential and reduced opportunities for convergent adaptation during post-domestication migration to new environments. Here we review current knowledge regarding trait convergence in the cereal grasses and consider whether the complexity and dynamism of cereal genomes (e.g., transposable elements, polyploidy, genome size) helped these species overcome potential limitations owing to domestication and achieve broad subsequent adaptation, in many cases through parallel means. This article is part of the theme issue 'Convergent evolution in the genomics era: new insights and directions'.

PLAB, a novel placental bone morphogenetic protein.

Bone morphogenetic proteins (BMP) constitute a sub-group of the large transforming growth factor-beta (TGF-beta) family. They play important roles in the embryonic development of multiple structures and in adult bone modeling. We have recently isolated a novel member of the BMP family from placenta, termed PLAB. PLAB is expressed highly in placenta, but can be found upon stringent analysis in low levels in most other tissues. At the amino acid level, PLAB is most closely related to BMP-8/OP-2, another member of the BMP family. Like TGF-beta, PLAB inhibits the proliferation of primitive hematopoietic progenitors. The high expression of PLAB by placenta raises the possibility that it may be a mediator of placental control of embryonic development.

The differential fate of mesonephric tubular-derived efferent ductules in estrogen receptor-alpha knockout versus wild-type female mice.

We investigated mesonephric tubular-derived efferent ductules in female wild-type (WT) and estrogen receptor-alpha knockout (ERalphaKO) mice from late fetal to adult life. On gestational day 17, efferent ductules in both fetal WT and ERalphaKO females were well developed and morphologically similar, although one third the size of the male counterpart. Unexpectedly, efferent ductules with a ciliated epithelium were still present on postnatal day 10 in WT and ERalphaKO females. By day 23, however, marked phenotypic differences occurred in efferent ductules of WT and ERbetaKO vs. ERalphaKO female mice. In the latter, efferent ductules became hypertrophied and dilated, whereas only small tubules remained in WT and ERbetaKO adult mice. The serum testosterone concentrations were similar in 21- to 25-day-old ERalphaKO, heterozygous, and WT female mice, suggesting that increased testosterone was not inducing enlargement of efferent ductules in ERalphaKO females. In conclusion, remnants of efferent ductules persisted in normal adult female mice, although these structures were greatly reduced in size compared with efferent ductules in ERalphaKO female mice. The underlying mechanism inducing hypertrophy and dilation of efferent ductules in ERalphaKO females is not clear, but secretory and/or reabsorptive function of female efferent ductules may involve ERalpha.

Alcohol and suicidal behavior.

Alcohol dependence and alcohol intoxication are important risk factors for suicidal behavior. However, the mechanism for the relationship remains unclear. This review presents a conceptual framework relating alcohol to suicidal behavior. Distal risk factors create a statistical potential for suicide. Alcohol dependence, as well as associated comorbid psychopathology and negative life events, act as distal risk factors for suicidal behavior. Proximal risk factors determine the timing of suicidal behavior by translating the statistical potential of distal risk factors into action. The acute effects of alcohol intoxication act as important proximal risk factors for suicidal behavior among the alcoholic and nonalcoholic alike. Mechanisms responsible for alcohol's ability to increase the proximal risk for suicidal behavior include alcohol's ability to: (1) increase psychological distress, (2) increase aggressiveness, (3) propel suicidal ideation into action through suicide-specific alcohol expectancies, and (4) constrict cognition which impairs the generation and implementation of alternative coping strategies. Moreover, the proximal risk factors associated with acute intoxication are consistent with Baumeister's (1990) escape theory of suicide. Suggestions for additional research are discussed, including the possibility that a nonlinear cusp catastrophe model characterizes the relationship between alcohol intoxication and suicidal behavior.

Remember that? A comparison of real-time versus retrospective recall of smoking lapses.

Research and treatment assessments often rely on retrospective recall of events. The accuracy of recall was tested using accounts of smoking lapse episodes from 127 participants who had quit smoking, and lapses and temptations were recorded in near-real time using a hand-held computer. These computer records were compared with retrospective accounts elicited 12 weeks later, with a focus on recall of lapses in 4 content domains: mood, activity, episode Triggers, and abstinence violation effects. Recall of lapses was quite poor: Average kappas for items ranged from 0.18 to 0.27. Mean profile rs assessing recall for the overall pattern of behavior were .36, .30, .33, and .44 for these domains, respectively. In recall, participants overestimated their negative affect and the number of cigarettes they had smoked during the lapse, and their recall was influenced by current smoking status. The findings suggest caution in the use of recall in research and intervention.

Effects of cue exposure and deprivation on cognitive resources in smokers.

This research examines the effects of manipulations designed to induce an urge to smoke on cognitive resources. Two cue-exposure experiments were conducted in which current smokers' reported urge to smoke and cognitive resources, as measured by a secondary reaction time (RT) probe, were assessed. In each study, subjects came to the laboratory twice, once while deprived of smoking for 12 hr and once when they were nondeprived. During each session, subjects were exposed to both smoking and control cues. Results indicated that experimental manipulations designed to elicit a strong urge to smoke led to an increase in self-reported urge to smoke and a decrease of available cognitive resources, as measured by RT. In addition, these 2 measures were significantly correlated. These data, in conjunction with previous findings using alcohol-dependent subjects (M. A. Sayette et al., 1994), lend support to the validity of RT as an objective measure of the effects of cue exposure on cognitive resources.

A test of the appraisal-disruption model of alcohol and stress.

OBJECTIVE: Faced with a large body of contradictory findings, investigators have begun to propose cognitive factors that moderate the effects of alcohol on stress. We tested the hypothesis, stemming from the appraisal-disruption model (ADM), that alcohol would be more likely to reduce stress when consumed prior to exposure to a stressor than when consumed following exposure. METHOD: Male and female social drinkers (N = 169, 85 men) with or without a parental history of alcoholism were recruited using separate structured clinical interviews with the participant and with a biological parent. Participants drank a moderate dose of alcohol or a placebo in one of two temporal sequences. Stress was induced by asking participants to present a self-disclosing speech about their physical appearance. Stress responses were assessed using four types of measures: self-reported anxiety, pulse rate, facial expression associated with negative affect and threat-related interference on a color-naming task. RESULTS: Alcohol was generally more likely to attenuate stress responses when initial exposure to a social stressor followed drinking than when it preceded drinking. CONCLUSIONS: Findings were consistent with predictions stemming from the ADM. Alcohol appears to be more likely to reduce stress when initial stress appraisal occurs during intoxication. In contrast, when initial appraisal occurs prior to drinking, alcohol is less effective in attenuating stress.

The relationship of self-efficacy expectancies to relapse among alcohol dependent men and women: a prospective study.

OBJECTIVE: We studied the relationship of self-efficacy expectancies measured during inpatient alcohol treatment and time to first drink and time to relapse following hospitalization. We also examined whether the relationship of in-hospital self-efficacy and posttreatment drinking outcome differed by gender. METHOD: We measured self-efficacy expectancies using the Situational Confidence Questionnaire (SCQ) in 100 subjects (59 men) during inpatient treatment for alcohol dependence. We followed subjects monthly for 1 year and examined the relationship of their in-hospital SCQ scores to posttreatment drinking behavior, as measured by time to first drink, time to relapse and percent abstinent days. RESULTS: Self-efficacy during hospitalization was related to relapse during the 12 months following hospitalization. Survival analysis demonstrated that in-hospital SCQ scores greater than 45 were predictive of better drinking outcomes. The median number of days to relapse after treatment were 30 and 135, respectively, in those with in-hospital SCQ scores less than or equal to 45 compared with those with SCQ scores greater than 45. There were no gender differences in self-efficacy measured during hospitalization, nor were there gender differences in the relationship of self-efficacy to time to relapse. However, men with SCQ scores less than or equal to 45 had fewer abstinent days during follow-up. CONCLUSIONS: Among both men and women being treated for alcohol dependence, a cut-off score of 45 on the SCQ may be especially important in helping clinicians assess patients who are at high risk for more rapid return to drinking after hospitalization.

Helminth infection reactivates latent γ-herpesvirus via cytokine competition at a viral promoter.

Mammals are coinfected by multiple pathogens that interact through unknown mechanisms. We found that helminth infection, characterized by the induction of the cytokine interleukin-4 (IL-4) and the activation of the transcription factor Stat6, reactivated murine γ-herpesvirus infection in vivo. IL-4 promoted viral replication and blocked the antiviral effects of interferon-γ (IFNγ) by inducing Stat6 binding to the promoter for an important viral transcriptional transactivator. IL-4 also reactivated human Kaposi's sarcoma-associated herpesvirus from latency in cultured cells. Exogenous IL-4 plus blockade of IFNγ reactivated latent murine γ-herpesvirus infection in vivo, suggesting a "two-signal" model for viral reactivation. Thus, chronic herpesvirus infection, a component of the mammalian virome, is regulated by the counterpoised actions of multiple cytokines on viral promoters that have evolved to sense host immune status.

Development of a brief measure of semantic priming.

Neuropsychologists use a variety of stimuli to investigate semantic memory functioning. Methodological concerns limit interpretation of performance differences between patients and nonpatient controls. The present study describes the development of a brief measure of semantic memory. Results indicate that this measure of semantic priming provides a brief, yet sensitive, measure of semantic memory. It may prove useful for researchers interested in examining semantic memory processes in cognitively impaired individuals.

Dietary genistein increased DMBA-induced mammary adenocarcinoma in wild-type, but not ER alpha KO, mice.

Dietary supplements containing concentrates of plant-derived estrogens are being increasingly used by consumers as alternatives for hormone replacement therapy, for treatment of menopausal symptoms, and as cancer preventives. The effect of dietary genistein on dimethylbenz[a]anthracene (DMBA)-induced mammary tumor development was investigated in wild-type (ER alpha WT) and estrogen receptor-alpha knockout (ER alpha KO) mice. ER alpha WT and ER alpha KO mice were fed a casein-based diet containing 0 or 1 g genistein/kg diet from weaning. Tumors were induced by oral administration of DMBA and subscapular implantation of medroxyprogesterone acetate. No tumors were observed in ER alpha KO mice. In ER alpha WT mice, dietary intake of genistein influenced tumor development, enhancing anaplasia of mammary cancer. Mice consuming genistein expressed malignant mammary adenocarcinoma, whereas benign adenomas were observed in mice fed the control diet. Dietary intake was also influenced by genistein, with ER alpha WT and ER alpha KO mice fed genistein consuming less food (p < 0.0001) and subsequently weighing less than mice fed the control diet (p < 0.0001). Significant differences in food intake by genotype were also observed (p = 0.0017), with ER alpha KO mice consuming less than ER alpha WT mice. Overall, this study found no protective effect of genistein on DMBA-induced mammary tumors in mice and suggests a potential adverse effect on tumor development when high levels of genistein are consumed.

Gonadotropin induction of ovulation and corpus luteum formation in young estrogen receptor-alpha knockout mice.

Estrogen receptor-alpha (ERalpha) knockout (ERalphaKO) female mice are infertile. Initially, they exhibit normal follicular development, but by 4-5 wk of age, they begin to develop hemorrhagic ovarian cysts. Follicles in adult ERalphaKO female mice progress to the graafian stage, but there are no corpora lutea (CL). To test whether ERalpha is required for ovarian folliculogenesis, ovulation, and CL formation, eCG and hCG were used to ovulate 3- to 5-wk-old ERalphaKO and wild-type (WT) sibling mice. Gonadotropin administration resulted in ovulation in both ERalphaKO and WT mice. Gonadotropin-treated ERalphaKO females that ovulated produced 7.09 +/- 0.77 oocytes per mouse, whereas gonadotropin-treated WT female mice had 16.17 +/- 0.84 oocytes. Surprisingly, ruptured ERalphaKO ovarian follicles developed into CL that had normal morphology. Gonadotropin-treated ERalphaKO mice had 3-fold higher concentrations of serum progesterone than did control ERalphaKO mice that had been administered saline rather than gonadotropins. Thus, the CL in gonadotropin-treated ERalphaKO mice appeared to be steroidogenically functional. On the basis of these findings, ovarian folliculogenesis, ovulation, and CL formation can occur in the absence of ERalpha, although to a lesser extent than in WT mice.