Exceptional Diversity, Non-Random Distribution, and Rapid Evolution of Retroelements in the B73 Maize Genome

Recent comprehensive sequence analysis of the maize genome now permits detailed discovery and description of all transposable elements (TEs) in this complex nuclear environment. Reiteratively optimized structural and homology criteria were used in the computer-assisted search for retroelements, TEs that transpose by reverse transcription of an RNA intermediate, with the final results verified by manual inspection. Retroelements were found to occupy the majority (>75%) of the nuclear genome in maize inbred B73. Unprecedented genetic diversity was discovered in the long terminal repeat (LTR) retrotransposon class of retroelements, with >400 families (>350 newly discovered) contributing >31,000 intact elements. The two other classes of retroelements, SINEs (four families) and LINEs (at least 30 families), were observed to contribute 1,991 and ∼35,000 copies, respectively, or a combined ∼1% of the B73 nuclear genome. With regard to fully intact elements, median copy numbers for all retroelement families in maize was 2 because >250 LTR retrotransposon families contained only one or two intact members that could be detected in the B73 draft sequence. The majority, perhaps all, of the investigated retroelement families exhibited non-random dispersal across the maize genome, with LINEs, SINEs, and many low-copy-number LTR retrotransposons exhibiting a bias for accumulation in gene-rich regions. In contrast, most (but not all) medium- and high-copy-number LTR retrotransposons were found to preferentially accumulate in gene-poor regions like pericentromeric heterochromatin, while a few high-copy-number families exhibited the opposite bias. Regions of the genome with the highest LTR retrotransposon density contained the lowest LTR retrotransposon diversity. These results indicate that the maize genome provides a great number of different niches for the survival and procreation of a great variety of retroelements that have evolved to differentially occupy and exploit this genomic diversity

Surgical treatment of rectal prolapse: experience and late results with 51 patients Tratamento cirúrgico da procidência retal: experiência e resultados tardios de 51 pacientes

The "best" surgical technique for the management of complete rectal prolapse remains unknown. Due to its low incidence, it is very difficult to achieve a representative number of cases, and there are no large prospective randomized trials to attest to the superiority of one operation over another. PURPOSE: Analyze the results of surgical treatment of complete rectal prolapse during 1980 and 2002. METHOD: Retrospective study. RESULTS: Fifty-one patients underwent surgical treatment during this period. The mean age was 56.7 years, with 39 females. Besides the prolapse itself, 33 patients complained of mucous discharge, 31 of fecal incontinence, 14 of constipation, 17 of rectal bleeding, and 3 of urinary incontinence. Abdominal operations were performed in 36 (71%) cases. Presacral rectopexy was the most common abdominal procedure (29 cases) followed by presacral rectopexy associated with sigmoidectomy (5 cases). The most common perineal procedure was perineal rectosigmoidectomy associated with levatorplasty (12 cases). Intraoperative bleeding from the presacral space developed in 2 cases, and a rectovaginal fistula occurred in another patient after a perineal rectosigmoidectomy. There were 2 recurrences after a mean follow-up of 49 months, which were treated by reoperation. CONCLUSION: Abdominal and perineal procedures can be used to manage complete rectal prolapse with safety and good long-term results. Age, associated medical conditions, and symptoms of fecal incontinence or constipation are the main features that one should bear in mind in order to choose the best surgical approach.<br>A técnica cirúrgica mais apropriada para a correção da procidência retal permanece motivo de controvérsia. Por se tratar de afecção pouco freqüente, há dificuldade de avaliação de número adequado de pacientes em estudos randomizados e existe pouca evidência para comprovar a superioridade de alguma das técnicas. OBJETIVO: Analisar os resultados de eficácia e segurança do tratamento cirúrgico da procidência retal em pacientes operados entre 1980 e 2002. MÉTODO: Estudo retrospectivo. RESULTADOS: Cinqüenta e um pacientes foram operados. A idade média foi de 56,7 anos e 39 eram mulheres. Além do prolapso, 33 pacientes queixavam-se de eliminação de muco, 31 tinham incontinência anal, 14 apresentavam constipação, 17 com sangramento retal e 3 incontinência urinária. Operações abdominais foram realizadas em 36 (71%) casos, sendo a retopexia sem prótese a operação mais realizada (29 casos) seguida pela retossigmoidectomia com retopexia (5 casos). A operação perineal mais realizada foi a retossigmoidectomia com plastia dos elevadores (12 casos). O sangramento sacral foi a única complicação intra-operatória e ocorreu em dois casos. Como complicação pós-operatória, houve um caso de fístula retovaginal após operação de retossigmoidectomia perineal. Após seguimento médio de 49 meses, observamos recidiva da procidência em 2 casos. CONCLUSÕES: Operações abdominais e perineais podem ser utilizadas com segurança e eficácia no tratamento cirúrgico da procidência do reto. A idade, a presença de afecções associadas, comorbidades e os sintomas de constipação e incontinência são as principais variáveis envolvidas na escolha da operação. As operações de retopexia abdominal e retossigmoidectomia perineal estão associadas a bons resultados

‘DEOS CHAMP-01C 70’: A model of the Earth’s gravity field computed from accelerations of the CHAMP satellite

Performance of a recently proposed technique for gravity field modeling has been assessed with data from the CHAMP satellite. The modeling technique is a variant of the acceleration approach. It makes use of the satellite accelerations that are derived from the kinematic orbit with the 3-point numerical differentiation scheme. A 322-day data set with 30-s sampling has been used. Based on this, a new gravity field model – DEOS CHAMP-01C 70 - is derived. The model is complete up to degree and order 70. The geoid height difference between the DEOS CHAMP-01C 70 and EIGEN-GRACE01S models is 14 cm. This is less than for two other recently published models: EIGEN-CHAMP03Sp and ITG-CHAMP01E. Furthermore, we analyze the sensitivity of the model to some empirically determined parameters (regularization parameter and the parameter that controls the frequency-dependent data weighting).We also show that inaccuracies related to non-gravitational accelerations, which are measured by the on-board accelerometer, have a minor influence on the computed gravity field model.Remote SensingAerospace Engineerin