Homing endonucleases catalyze double-stranded DNA breaks and somatic transgene excision in Aedes aegypti

Aedes aegypti is a major vector of arthropod-borne viruses such as yellow fever virus and dengue viruses. Efforts to discern the function of genes involved in important behaviours, such as vector competence and host seeking through reverse genetics, would greatly benefit from the ability to generate targeted gene disruptions. Homing endonucleases are selfish elements which catalyze double-stranded DNA (dsDNA) breaks in a sequence-specific manner. In this report we demonstrate that the homing endonucleases I- Ppo I, I- Sce I, I- Cre I and I- Ani I are all able to induce dsDNA breaks in adult female Ae. aegypti chromosomes as well as catalyze the somatic excision of a transgene. These experiments provide evidence that homing endonucleases can be used to manipulate the genome of this important disease vector.     

软骨组织工程的研究进展

目前，软骨组织工程已在基础研究方面取得了令人瞩目的成果，并在临床应用方面进行了初步尝试，为I临床软骨缺损的修复提供了新的思路与途径，已经成为该领域主要的研究方向，但其大规模临床应用尚存在诸多困难。现结合近年的研究成果，就组织工程化软骨的种子细胞、生物支架材料、体内外构建以及临床应用等方面进行综述。     

A case of laparoscopy-assisted vaginal cuff suturing for vaginal cuff dehiscence after total laparoscopic hysterectomy

IntroductionVaginal cuff dehiscence after hysterectomy is a rare complication and occurs in less than 1% of patients. It can present with serious complications, such as bowel evisceration and peritonitis.Presentation of caseA 51-year-old multigravida Korean woman underwent total laparoscopic hysterectomy for leiomyoma. Six months later, she reported lower abdominal pain and vaginal bleeding. Physical examination revealed rebound tenderness in the lower abdomen, and pelvic examination showed a small amount of vaginal bleeding with an evisceration of the small intestine through the vagina that exhibited healthy peristalsis. The eviscerated bowel, which seemed to be a part of the ileum, was carefully manually reduced transvaginally into the abdominal cavity. Laparoscopic observation revealed adhesions between the omentum, small intestine, and the peritoneum. Specifically, the small intestine was adhered around the vaginal cuff. An abdominal abscess was found in the left lower abdominal cavity. An adhesiotomy was performed and the abdominal abscess was removed and irrigated. Complete separation of the anterior and posterior vaginal cuff edges was obtained. The vaginal cuff was closed with interrupted 0-polydioxanone absorbable sutures without bowel injury. A 6-month follow-up examination revealed complete healing of the vaginal cuff.DiscussionIn this case, we were able to make use of both laparoscopic and transvaginal methods to perform a successful repair with a minimally invasive and safe technique.ConclusionLaparoscopically assisted vaginal cuff suturing for vaginal cuff dehiscence after total laparoscopic hysterectomy was found to be effective, safe, and minimally invasive.     

Median cleft lip: A new method of surgical repair

The aim is to discuss a new method of muscle repair in midline cleft lip. Three patients with midline cleft lip were repaired with our technique of muscle repair and the results evaluated. Our new method of muscle repair in the form of ''Z'' helps in forming the philtral dimple.     

A possible mechanism for exonuclease 1-independent eukaryotic mismatch repair

Mismatch repair contributes to genetic stability, and inactivation of the mammalian pathway leads to tumor development. Mismatch correction occurs by an excision-repair mechanism and has been shown to depend on the 5′ to 3′ hydrolytic activity exonuclease 1 (Exo1) in eukaryotic cells. However, genetic and biochemical studies have indicated that one or more Exo1-independent modes of mismatch repair also exist. We have analyzed repair of nicked circular heteroduplex DNA in extracts of Exo1-deficient mouse embryo fibroblast cells. Exo1-independent repair under these conditions is MutLα-dependent and requires functional integrity of the MutLα endonuclease metal-binding motif. In contrast to the Exo1-dependent reaction, we have been unable to detect a gapped excision intermediate in Exo1-deficient extracts when repair DNA synthesis is blocked. A possible explanation for this finding has been provided by analysis of a purified system comprised of MutSα, MutLα, replication factor C, proliferating cell nuclear antigen, replication protein A, and DNA polymerase δ that supports Exo1-independent repair in vitro. Repair in this system depends on MutLα incision of the nicked heteroduplex strand and dNTP-dependent synthesis-driven displacement of a DNA segment spanning the mismatch. Such a mechanism may account, at least in part, for the Exo1-independent repair that occurs in eukaryotic cells, and hence the modest cancer predisposition of Exo1-deficient mammalian cells.     

The Loss of Pleasure,or Why We Are Still Talking about Oedipus

This article brings psychoanalysis to the fore in grappling with the question: Why does patriarchy persist? It highlights the psychological function of patriarchy as a defense against loss by connecting Gilligan's research on development with Bowlby's studies of attachment. Pathological responses to loss parallel the gender codes of patriarchal masculinity and femininity, which are internalized through an initiation that forces ruptures in relationship and subverts the capacity for repair. This parallel suggests that the gender roles, which uphold a patriarchal order, simultaneously defend against the loss of connection inherent in that order. The loss of pleasure and a change in voice signal the psyche's induction into patriarchy and highlight a potential within psychoanalysis to foster a healthy resistance against losses that otherwise appear necessary or natural.     

Dynamics of the bacterial SMC complex and SMC-like proteins involved in DNA repair

Bacteria and archaea possess several different SMC-like proteins, which perform essential functions in a variety of chromosome dynamics, such as chromosome compaction, segregation, and DNA repair. SMC-like proteins localize to distinct sites within the cells at different time points in the cell cycle, or are recruited to sites of DNA breaks and damage. The bacterial SMC (MukB) complex appears to perform a condensin-like function, while SbcC and RecN act early during DNA repair, but apparently at different sites within the cells. Thus, bacterial SMC-like proteins have dynamic functions in chromosome segregation and maintenance of genetic stability.