Contrasting patterns of X-chromosome divergence underlie multiple sex-ratio polymorphisms in stalk-eyed flies.

Sex-linked segregation distorters cause offspring sex ratios to differ from equality. Theory predicts that such selfish alleles may either go to fixation and cause extinction, reach a stable polymorphism or initiate an evolutionary arms race with genetic modifiers. The extent to which a sex ratio distorter follows any of these trajectories in nature is poorly known. Here, we used X-linked sequence and simple tandem repeat data for three sympatric species of stalk-eyed flies (Teleopsis whitei and two cryptic species of T. dalmanni) to infer the evolution of distorting X chromosomes. By screening large numbers of field and recently laboratory-bred flies, we found no evidence of males with strongly female-biased sex ratio phenotypes (SR) in one species but high frequencies of SR males in the other two species. In the two species with SR males, we find contrasting patterns of X-chromosome evolution. T. dalmanni-1 shows chromosome-wide differences between sex-ratio (XSR ) and standard (XST ) X chromosomes consistent with a relatively old sex-ratio haplotype based on evidence including genetic divergence, an inversion polymorphism and reduced recombination among XSR chromosomes relative to XST chromosomes. In contrast, we found no evidence of genetic divergence on the X between males with female-biased and nonbiased sex ratios in T. whitei. Taken with previous studies that found evidence of genetic suppression of sex ratio distortion in this clade, our results illustrate that sex ratio modification in these flies is undergoing recurrent evolution with diverse genomic consequences.

Children's symptoms in the wake of Challenger: a field study of distant-traumatic effects and an outline of related conditions.

OBJECTIVE: The Challenger space shuttle explosion in January 1986 offered an opportunity to determine what, if any, symptoms of posttraumatic stress disorder (PTSD) and bereavement normal latency-age children and adolescents would develop after a distant, horrifying event. METHOD: With a structured interview, the authors assessed the symptoms of 153 randomly selected children from Concord, N.H., and Porterville, Calif. Responses were statistically compared between East Coast children, who saw the event on television and who generally cared more about the teacher aboard Challenger, and West Coast children, who heard about it first; between latency-age children and adolescents; and between children seen 5-7 weeks later and those same children seen 14 months later. RESULTS: More than 60% of the subjects feared at least one stimulus related to Challenger within the first 5-7 weeks of the explosion. The East Coast and latency-age groups appeared significantly more symptomatic than did the West Coast and adolescent groups. Over the 14-month study period, most symptoms dramatically faded. However, adolescents' diminished expectations for the future in general increased, and latency-age children's changed approach to space careers held relatively steady. Three East Coast latency-age children met the DSM-III-R symptom requirements for PTSD in 1986; no children met these in 1987. CONCLUSIONS: Children's symptomatic patterns after Challenger relate to the patterns for PTSD listed in diagnostic manuals and to three symptoms not in the DSM-IV list. To the authors, distant traumas appear to be one of a newly defined spectrum of trauma-related conditions that include relatively evanescent symptoms and a few longer-lasting ones. These symptoms may affect large numbers of normal children.

Children's thinking in the wake of Challenger.

OBJECTIVE: The Challenger spacecraft explosion in 1986 offered an opportunity to study the thinking of normal children after a sudden and distant disaster, differences in thinking among children of different levels of emotional concern and different ages, and changes in their thinking over time. METHOD: The authors studied six thinking patterns known to characterize childhood posttraumatic stress disorder and four additional hypothesized patterns in 153 randomly selected children of Concord, N.H. (who watched the explosion on television) and Porterville, Calif. (who heard about it later). They compared the structured-interview responses of the more involved (East Coast) and less involved (West Coast) children, of the latency-age children and the adolescents, and of the children initially (5-7 weeks after the explosion) and 14 months later. RESULTS: The children exhibited the 10 predictable thinking patterns. They initially defended themselves, denying the reality of the explosion. They later fantasized about it. They tried to cope by seeking additional information on their own, at home, and at school. Most children talked about Challenger, but a minority of the latency-age youngsters avoided related talk and thoughts. The adolescents experienced more paranormal thinking, philosophical changes, and negative attitudes. Over the year, omens, paranormal experiences, and Challenger-based fantasies tended to disappear, but negative views about institutions and the world's future held steady or increased. CONCLUSIONS: The children's thinking followed predictable patterns. A higher degree of emotional involvement (East Coast children) was strongly linked to these thinking patterns, as was being an adolescent. Distant disasters appear to set up commonalities of thought that might come to characterize certain generations of children.

Children's memories in the wake of Challenger.

OBJECTIVE: The Challenger spacecraft explosion of Jan. 28, 1986, offered an opportunity to study the memories of normal latency and adolescent children of different emotional involvements following one sudden and distant disaster. How would children of various levels of concern express their memories? And if studied over time, how would these narratives change? Would there be developmental differences? And would there be false details of memory? METHOD: The authors set out to compare the memories of 153 children from Concord, N.H. (who watched the explosion on television), and Porterville, Calif. (who heard about it). The structured-interview responses of involved and less involved children; latency-age versus adolescent children; and those seen initially (5-7 weeks after the explosion) versus those same children seen later (at 14 months) were statistically compared. RESULTS: The vast majority of children's memories of Challenger were clear, consistent, and detailed, with highlighting of personal placement, who else was there, and personal occurrences linked to the event. Those children who were less emotionally involved demonstrated significantly less clarity, consistency, and correct ordering of sequences and were less likely to remember personal placement, other people who were there, and related personal incidents. About 30% of all children in this study misunderstood something about Challenger and incorporated these misunderstandings into their memories as false details. Latency-age children continued to harbor false details for 14 months, as opposed to the adolescents. CONCLUSIONS: Childhood memories of the Challenger space shuttle explosion appeared predictable, were related to patterns of memory that have been observed following single, unrepeated traumas, and reflected age and stage differences.

Rocky Mountain spotted fever encephalitis: MR findings.

We describe a case of Rocky Mountain spotted fever encephalitis and present the associated findings of an MR examination of the brain, which showed increased signal intensity in the distribution of perivascular spaces. Resolution of the MR abnormalities coincided with clinical improvement.