TfoX-Based Genetic Mapping Identifies Vibrio fischeri Strain-Level Differences and Reveals a Common Lineage of Laboratory Strains

Bacterial strain variation exists in natural populations of bacteria and can be generated experimentally through directed or random mutation. The advent of rapid and cost-efficient whole-genome sequencing has facilitated strain-level genotyping. Even with modern tools, however, it often remains a challenge to map specific traits to individual genetic loci, especially for traits that cannot be selected under culture conditions (e.g., colonization level or pathogenicity). Using a combination of classical and modern approaches, we analyzed strain-level variation in Vibrio fischeri and identified the basis by which some strains lack the ability to utilize glycerol as a carbon source. We proceeded to reconstruct the lineage of the commonly used V. fischeri laboratory strains. Compared to the wild-type ES114 strain, we identify in ES114-L a 9.9-kb deletion with endpoints in tadB2 and glpF; restoration of the missing portion of glpF restores the wild-type phenotype. The widely used strains ESR1, JRM100, and JRM200 contain the same deletion, and ES114-L is likely a previously unrecognized intermediate strain in the construction of many ES114 derivatives. ES114-L does not exhibit a defect in competitive squid colonization but ESR1 does, demonstrating that glycerol utilization is not required for early squid colonization. Our genetic mapping approach capitalizes on the recently discovered chitin-based transformation pathway, which is conserved in the Vibrionaceae; therefore, the specific approach used is likely to be useful for mapping genetic traits in other Vibrio species.     

A genetic linkage map of a cichlid fish,the tilapia (Oreochromis niloticus).

We have constructed a genetic map for a tilapia, Oreochromis niloticus, using DNA markers. The segregation of 62 microsatellite and 112 anonymous fragment length polymorphisms (AFLPs) was studied in 41 haploid embryos derived from a single female. We have identified linkages among 162 (93.1%) of these markers. 95% of the microsatellites and 92% of the AFLPs were linked in the final map. The map spans 704 Kosambi cM in 30 linkage groups covering the 22 chromosomes of this species. Twenty-four of these linkage groups contain at least one microsatellite polymorphism. From the number of markers 15 or fewer cM apart, we estimate a total map length of approximately 1000-1200 cM. High levels of interference are observed, consistent with measurements in other fish species. This map is a starting point for the mapping of single loci and quantitative traits in cichlid fishes.     

The risk‐return trade‐off between solitary and eusocial reproduction

Social insect colonies can be seen as a distinct form of biological organisation because they function as superorganisms. Understanding how natural selection acts on the emergence and maintenance of these colonies remains a major question in evolutionary biology and ecology. Here, we explore this by using multi‐type branching processes to calculate the basic reproductive ratios and the extinction probabilities for solitary vs. eusocial reproductive strategies. We find that eusociality, albeit being hugely successful once established, is generally less stable than solitary reproduction unless large demographic advantages of eusociality arise for small colony sizes. We also demonstrate how such demographic constraints can be overcome by the presence of ecological niches that strongly favour eusociality. Our results characterise the risk‐return trade‐offs between solitary and eusocial reproduction, and help to explain why eusociality is taxonomically rare: eusociality is a high‐risk, high‐reward strategy, whereas solitary reproduction is more conservative.     

A Peptide to Reduce Pulmonary Edema in a Rat Model of Lung Transplantation

Background

Despite significant advances in organ preservation, surgical techniques and perioperative care, primary graft dysfunction is a serious medical problem in transplantation medicine in general and a specific problem in patients undergoing lung transplantation. As a result, patients develop lung edema, causing reduced tissue oxygenation capacity, reduced lung compliance and increased requirements for mechanical ventilatory support. Yet, there is no effective strategy available to protect the grafted organ from stress reactions induced by ischemia/reperfusion and by the surgical procedure itself.

Methods

We assessed the effect of a cingulin-derived peptide, XIB13 or a random peptide in an established rat model of allogeneic lung transplantation. Donor lungs and recipients received therapeutic peptide at the time of transplantation and outcome was analyzed 100min and 28 days post grafting.

Results

XIB13 improved blood oxygenation and reduced vascular leak 100min post grafting. Even after 28 days, lung edema was significantly reduced by XIB13 and lungs had reduced fibrotic or necrotic zones. Moreover, the induction of an allogeneic T cell response was delayed indicating a reduced antigen exchange between the donor and the host.

Conclusions

In summary, we provide a new tool to strengthen endothelial barrier function thereby improving outcomes in lung transplantation.     

Stereotactic LINAC-Radiosurgery for Glomus Jugulare Tumors: A Long-Term Follow-Up of 27 Patients

Background

The optimal treatment of glomus jugulare tumors (GJTs) remains controversial. Due to the critical location, microsurgery still provides high treatment-related morbidity and a decreased quality of life. Thus, we performed stereotactical radiosurgery (SRS) for the treatment of GJTs and evaluated the long-term outcome.

Methods

Between 1991 and 2011, 32 patients with GJTs underwent SRS using a linear accelerator (LINAC) either as primary or salvage therapy. Twenty-seven patients (median age 59.9 years, range 28.7–79.9 years) with a follow-up greater than five years (median 11 years, range 5.3–22.1 years) were selected for retrospective analysis. The median therapeutic single dose applied to the tumor surface was 15 Gy (range 11–20 Gy) and the median tumor volume was 9.5 ml (range 2.8–51 ml).

Results

Following LINAC-SRS, 10 of 27 patients showed a significant improvement of their previous neurological complaints, whereas 12 patients remained unchanged. Five patients died during follow-up due to old age or other, not treatment-related reasons. MR-imaging showed a partial remission in 12 and a stable disease in 15 patients. No tumor progression was observed. The actuarial overall survival rates after five, ten and 20 years were 100%, 95.2% and 79.4%, respectively.

Conclusions

Stereotactic LINAC-Radiosurgery can achieve an excellent long-term tumor control beside a low rate of morbidity in the treatment of GJTs. It should be considered as an alternative therapy regime to surgical resection or fractionated external beam radiation either as primary, adjuvant or salvage therapy.