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ABSTRACT. Mussels are one of the most cultivated and commercialized bivalves worldwide and in southern Chile its culture represent an important economic activity. The species identification within the Mytilus genera, by morphological features, is unreliable, so we used a polymorphism RFLP in the gene encoding the polyphenolic adhesive protein as a species-specific genetic marker to describe Mytilus species diversity in southern Chile, and evaluate possible applications in traceability, food quality and safety. Using Me 15-16 marker most mussels were M. chilensis, finding no other pure individuals; however, putative hybrids of M. chilensis x M. trossulus and M. chilensis x M. galloprovincialis were detected. There was no evidence of M. edulis. The presence of the M. trossulus allele, faraway from its distribution area, demands further analysis with different genetic markers to allow a better understanding of its origin. In addition, the correspondence between markers that distinguishes northern from southern hemisphere M. galloprovincialis, with those who discriminates between M. chilensis and M. galloprovincialis would contribute to the taxonomic status of Chilean blue mussels. In Chile, the genetic composition of Mytilus indicates that geographical origin of mussels and its traceability cannot be established merely from the identification of the species. The use of other markers would be required. Keywords: Mytilus, mussels, genetic identification, Me 15-16, PCR-RFLP, southern Chile. Composición genética de especies de

We evaluated the impact of recipient and cord blood unit (CBU) genetic polymorphisms related to immune response on outcomes after unrelated cord blood transplantations (CBTs). Pretransplant DNA samples from 696 CBUs with malignant diseases were genotyped for NLRP1, NLRP2, NLRP3, TIRAP/Mal, IL10, REL, TNFRSF1B, and CTLA4. HLA compatibility was 6 of 6 in 10%, 5 of 6 in 39%, and ≥4 of 6 in 51% of transplants. Myeloablative conditioning was used in 80%, and in vivo T-cell depletion in 81%, of cases. The median number of total nucleated cells infused was 3.4 × 10/kg. In multivariable analysis, patients receiving CBUs with GG-CTLA4 genotype had poorer neutrophil recovery (hazard ratio [HR], 1.33; P = .02), increased nonrelapse mortality (NRM) (HR, 1.50; P < .01), and inferior disease-free survival (HR, 1.41; P = .02). We performed the same analysis in a more homogeneous subset of cohort 1 (cohort 2, n = 305) of patients who received transplants for acute leukemia, all given a myeloablative conditioning regimen, and with available allele HLA typing (HLA-A, -B, -C, and -DRB1). In this more homogeneous but smaller cohort, we were able to demonstrate that GG-CTLA4-CBU was associated with increased NRM (HR, 1.85; P = .01). Use of GG-CTLA4-CBU was associated with higher mortality after CBT, which may be a useful criterion for CBU selection, when multiple CBUs are available.

Mussels (Mytilus spp.) are one of the most cultivated and commercialized bivalves in southern Chile; culture is currently supplied almost entirely from wild-caught seed obtained from relatively few collection centers. The genetic diversity and differentiation of the blue mussel in southern Chile was investigated by sampling six locations: one natural bank and five seed collection centers. Nine polymorphic microsatellite (SSR) loci were genotyped (Mgu1, Mgu3, MT203, MT282, Mg15, Mg56, Med737, MIT02 and MGE005). We found 75 different alleles, six of which were private alleles. Of the analyzed loci, 45 of 54 tests performed deviated from Hardy-Weinberg equilibrium after sequential Bonferroni correction (P < 0.05), revealing significant heterozygote deficiencies. The polymorphic information content (PIC) ranged from 0.322 (MGE005) to 0.893 (Mgu1). Despite the long distance between some sampling sites (up to 1360 km), genetic differentiation among the sites was low (FST = 0.043, P < 0.0001). The Bayesian cluster analysis (STRUCTURE) indicated two probable clusters, while the non-parametric cluster analysis (AWclust) identified two to four clusters. Both analyses showed a high level of admixture within clusters. Our results indicate that blue mussels in southern Chile show lower genetic diversity than in other countries, low inbreeding levels, and limited genetic differentiation among locations.

Introduction: Donor and recipient polymorphisms of immune defense and inflammatory cytokine genes have been associated with outcomes after bone marrow or peripheral blood stem cell transplantation (SCT), but have not been described in the setting of umbilical cord blood transplantation (CBT). Material and Methods: We evaluated the impact of genetic polymorphisms of recipients and CBU units on survival and other CBT outcomes using the following candidate genes related to immune response: NACHT-leucine-rich repeat with a pyrin domain at N-terminus (NLRP1-rs5862, NLRP2-rs043684, NLRP3-rs10754558), Toll-interleukin-1 receptor domain containing adaptor protein (TIRAP/Mal-rs8177374), interleukin-10 (IL10-rs1800872), V-rel reticuloendotheliosis viral oncogene homolog (REL-rs13031237), tumor necrosis factor receptor superfamily - member 1B (TNFRSF1B-rs1061622) and associated protein 4 of cytotoxic T lymphocyte (CTLA4-rs3087243). Seven Netcord banks provided pre-transplant DNA samples from 851 CBU units and 173 recipients. All patients underwent CBT at EBMT centers. Malignant (n=696) and non-malignant (n=155) diseases were analyzed separately. Results: Among the 851 recipients, 57% were male and 61% adults. Degree of HLA matching between CBU unit and recipient (HLA-A, -B at antigen level and -DRB1 at allele level) was 6/6 in 12%, 5/6 in 40%, and ≤4/6 in 48% of transplants. Myeloablative conditioning was used in 77% of cases and anti-thymocyte globulin or monoclonal antibodies in 82% of cases. Median infused total nucleated cells (TNC) and CD34+ cells were 3.7x107/kg and 1.6x105/kg, respectively. In the cohort with malignant diseases, multivariable analysis adjusted for patient-, donor- and disease-related variables showed that recipients of CBU with GG CTLA4 genotype had a poorer neutrophil engraftment (HR 1.24; 95% CI 1.09-1.40; p=0.03), increased NRM (HR 1.52; 95% CI 1.35-1.72%; p<0.01) and inferior disease-free survival (DFS) (HR 1.41; 95% CI 1.06-1.88; p=0.02), whereas the AA CTLA4 genotype was associated with lower relapse rate (HR 0.64; 95% CI 0.57-0.72; p=0.02). Recipients of GG TNFRSF1B CBU had lower platelet recovery (HR 1.94; 95% CI 1.71-2.19; p=0.02). With the aim to confirm these results in a more homogenous cohort of recipients, we analyzed recipients with acute leukemias, receiving myeloablative conditioning and with available high resolution typing of HLA-A,-B,-C and-DRB1 (n=305). In this subset analysis, recipients of GG CTLA4 CBU had increased NRM (HR 1.72; 95% CI 1.10-2.70%; p=0.02), but no impact on DFS and relapse was observed. In the cohort of patients with non-malignant diseases (n=155), there was no statistical association between the selected candidate genes and outcomes. Similarly, all recipient gene polymorphisms tested (n=173) were not associated with CBT outcomes. Conclusion: In this retrospective analysis, CBU gene polymorphisms CTLA4 and TNFSF1B impacted CBT outcomes. Importantly, CTLA4 GG genotype was associated with inferior survival and the AA genotype with lower relapse rate in patients with malignant disorders. The possible biological explanation of the impact of CTLA4 is that GG genotype is associated with decreased production of soluble CTLA4 (whose primarily functions is to inhibit T-cell activation) which contributes to decrease suppression of T-cell alloimune responses post CBT If these findings are confirmed in further studies, CTLA4 gene polymorphisms can be used among other factors to select CBU with the aim to improve survival after CBT. Disclosures No relevant conflicts of interest to declare.