Autosomal and maternal effects on pupation behavior inDrosophila melanogaster

This study demonstrates the importance of using a complete set of 16 reciprocal crosses (F₁, backcrosses, and F₂) to thoroughly investigate both genetic and nongenetic influences on patterns of inheritance of larval pupation behavior inDrosophila melanogaster. Larvae derived from natural populations show significant variation in pupal height, defined as the distance a larva pupates above the feeding substrate. Differences in the distance a larva pupates from fruit in nature is known to affect the fitness ofDrosophila populations. In this study the heredity of pupal height is analyzed by performing crosses between high- and low-pupating strains. We found that the inheritance of pupal height fit a classical additive polygenic model of inheritance, with intermediate F₁ pupal heights and greater variances in the F₂ generation. In addition, a significant maternal effect was also found by analyzing the reciprocal backcrosses. Progeny with low-pupating mothers had lower pupation heights than those with low-pupating fathers. Similarly, progeny with high-pupating mothers tended to have higher pupal heights than those with high-pupating fathers. This maternal effect was not attributable to strain differences in permanent cytoplasmic factors, sex chromosomes, or developmental time. Finally, we speculate upon the environmental conditions under which a transient maternal effect on pupation behavior would be expected to evolve in natural populations.This work was supported by a University Research Fellowship and Operating Grant from the Natural Sciences and Engineering Research Council to M. B. Sokolowski. S. J. Bauer was the recipient of an Ontario Graduate Scholarship.     

Electrophysiological measures of conflict and reward processing are associated with decisions to engage in physical effort

Anterior cingulate cortex (ACC), a key brain region involved in cognitive control and decision making, is suggested to mediate effort- and value-based decision making, but the specific role of ACC in this process remains debated. Here we used frontal midline theta (FMT) and the reward positivity (RewP) to examine ACC function in a value-based decision making task requiring physical effort. We investigated whether (1) FMT power is sensitive to the difficulty of the decision or to selecting effortful actions, and (2) RewP is sensitive to the subjective value of reward outcomes as a function of effort investment. On each trial, participants chose to execute a low-effort or a high-effort behavior (that required squeezing a hand-dynamometer) to obtain smaller or larger rewards, respectively, while their brainwaves were recorded. We replicated prior findings that tonic FMT increased over the course of the hour-long task, which suggests increased application of control in the face of growing fatigue. RewP amplitude also increased following execution of high-effort compared to low-effort behavior, consistent with increased valuation of reward outcomes by ACC. Although neither phasic nor tonic FMT were associated with decision difficulty or effort selection per se, an exploratory analysis revealed that the interaction of phasic FMT and expected value of choice predicted effort choice. This interaction suggests that phasic FMT increases specifically under situations of decision difficulty when participants ultimately select a high-effort choice. These results point to a unique role for ACC in motivating and persisting at effortful behavior when decision conflict is high.     

Oligogenic determination of morphine analgesic magnitude: A genetic analysis of selectively bred mouse lines

Two ongoing selective breeding projects have produced mice that display divergent analgesic responses to morphine. These two projects have selected for similar phenotypes: high and low levorphanol analgesia (HAR/LAR lines; Portland, OR) and high and low swim stress-induced analgesia (HA/LA lines; Jastrzebiec, Poland). Evidence suggests genetic commonalities between mice of the two projects. Using a Mendelian breeding protocol, we have recently found that one or two genetic loci predominantly determine the high morphine analgesia exhibited by HA mice. In the present study we demonstrate that the differential morphine analgesia (5 mg/kg. i.p.) displayed by HAR and LAR mice is similarly oligogenic, predominantly determined by two unlinked loci. A complementation analysis, in which the analgesic responses to morphine of the recessive homozygotes of each project (HAR and HA) were compared to those of their hybrid offspring (HAR x HA), revealed that different genetic loci have been fixed in each project. An intriguing bimodal distribution was observed in the HAR x HA population: Some HAR x HA hybrids displayed greater morphine analgesia than either HAR or HA mice, whereas others displayed minimal analgesia. LAR x LA hybrids displayed less analgesia than either LAR or LA mice. The analgesic responses of HAR x LA and LAR x HA mice were comparable to those of their low-line parents. These findings indicate not only that different loci were responsible for producing high morphine responders in each selection project but that these distinct loci can interact synergistically to produce superhigh and superlow responders.     

Sex selection may be inadvertently performed in in-vitro fertilization--embryo transfer programmes

The present study aims to ascertain whether sex selection maybe inadvertently performed in human in-vitro fertilization (IVF)and embryo transfer (IVF-embryo transfer) programmes when selectingfor high quality embryos (those with the fastest cleaving ratesand/or the best morphology) at the fresh transfer cycle. Allpatients entering into the study were treated with gonadotrophinsafter pituitary suppression with gonadotrophin-releasing hormoneagonists (GnRHa) and had intrauterine embryo transfer on day2 post-insemination. These patients were retrospectively dividedinto three groups according to whether the difference in meannumber of cells between embryos transferred and all embryosavailable for transfer in a given cycle was less than (negativeselection), equal to (no selection) or greater (positive selection)than zero. In cycles resulting in singleton births, the sexratio of the resulting babies was significantly (P 0.005) shiftedtoward the female (88.8%) and to the male (90.0%) in the negativeand positive selection groups respectively. No shift in sexratio was observed in cycles resulting in multiple births. Maternalage was another independent factor affecting sex ratio at birth.Sex ratio was significantly (P 0.05) skewed in favour of males(62.7%) and females (71.4%) in women <35 and 235 years ofage respectively. Maternal age, number of embryos transferredand the event of selecting or not selecting the slowest cleavingembryos for transfer were entered automatically in a three-groupdiscriminant model for distinguishing cycles resulting in onlyboys, both boys and girls, and only girls. These data suggestthat (i) sex selection may be inadvertently performed in IVF-embryotransfer programmes when selecting for high quality embryosat the fresh transfer cycles; (ii) human endometria may be favourable,indifferent or hostile to either fast cleaving or slow cleavingembryos depending on maternal age; and (iii) ‘natural’sex selection may be performed for social, psychological ormedical reasons.     

Preliminary study of the incidence of disomy in sperm fractions after MicroSort flow cytometry

Using triple colour fluorescent in-situ hybridization (FISH) we have evaluated, on a blind basis, the disomy level for chromosome 21 and the sex chromosomes in flow cytometric sorted sperm samples. There were no statistically significant differences in the disomy rates when comparing the sorted samples (either for X- or Y-bearing spermatozoa) with non-sorted samples. There were no diploid spermatozoa observed in any sample group after MicroSort processing.     

Thymocyte maturation is regulated by the activity of the helix-loop-helix protein, E47

The E2A proteins, E12 and E47, are required for progression through multiple developmental pathways, including early B and T lymphopoiesis. Here, we provide in vitro and in vivo evidence demonstrating that E47 activity regulates double-positive thymocyte maturation. In the absence of E47 activity, positive selection of both major histocompatibility complex (MHC) class I- and class II-restricted T cell receptors (TCRs) is perturbed. Additionally, development of CD8 lineage T cells in an MHC class I-restricted TCR transgenic background is sensitive to the dosage of E47. Mice deficient for E47 display an increase in production of mature CD4 and CD8 lineage T cells. Furthermore, ectopic expression of an E2A inhibitor helix-loop-helix protein, Id3, promotes the in vitro differentiation of an immature T cell line. These results demonstrate that E2A functions as a regulator of thymocyte positive selection.     

广西卫Ⅵ项目实施与效果评价

１９９５年,广西壮族自治区开始实施卫Ⅵ项目,共有３０个项目县。各级政府和卫生职能部门,注意以项目为龙头,以重点、难点为突破口,做到项目目标明确,工作职责分清,措施落实到位,做好分类指导,加强监督检查,从而保证项目顺利进行,使项目工作取得了明显效果。至１９９８年底止,项目的１６个指标已基本达标,其中有１２个指标已达到了项目终期目标要求,有力地推动了全区妇幼卫生事业的发展。     

The Patient Factor

Long-term results of bariatric surgery are reviewed. The weight criteria for patient acceptance for bariatric surgery and their variation are presented graphically and discussed. Factors affecting patient selection in an attempt to improve outcome results in the small group of patients who currently achieve less weight loss than anticipated are defined. An attempt is made to define pre-operative criteria for selection of pure restrictive versus combined restrictive and malabsorptive procedures. Aspects of motivation, co-morbidity, age and pre-operative weight are discussed and the position statement of the ASBS in regard to laparoscopic bariatric surgery is defined.     

Acceptance of Surgery for Obesity by Academic Surgeons in North America

BACKGROUND: Have surgeons in North America accepted operations for the treatment of severe obesity? This question was posed by organizers of the Ninth International Symposium on Obesity Surgery that met in Stockholm in September, 1995. Study design: In order to obtain opinions which might help to answer the question posed, a 1-page questionnaire was sent to 151 chairmen of academic departments of surgery in North America in December 1994 asking about the acceptance and use of surgical operations for the treatment of severe obesity. RESULTS: Answers, received from 112 or 74%, indicated that operative treatment should be used (74%), was effective (77%) and safe (71 %). However, only 65% of departments provided such operations. Operative treatment for obesity was available outside the department in 53%. The operations most frequently used were Roux-en-Y gastric bypass (RGB) and vertical banded gastroplasty (VBG). A single operation was offered by 44 departments and a choice of two or more operations in 30 departments. RGB and VBG were equally in use. Gastric banding was used as an alternative to VBG in six departments. Other operations were in use in six departments either alone (three) or as alternatives to RGB and VBG (three). CONCLUSIONS: It appears that surgical treatment of obesity is accepted and available in the majority of academic departments of surgery.