Conservation implications of the mating system of the Pampa Hermosa landrace of peach palm analyzed with microsatellite markers

Peach palm (Bactris gasipaes) is cultivated by many indigenous and traditional communities from Amazonia to Central America for its edible fruits, and is currently important for its heart-of-palm. The objective of this study was to investigate the mating system of peach palm, as this is important for conservation and breeding. Eight microsatellite loci were used to genotype 24 open-pollinated progenies from three populations of the Pampa Hermosa landrace maintained in a progeny trial for genetic improvement. Both the multi-locus outcrossing rates (0.95 to 0.99) and the progeny level multi-locus outcrossing rates (0.9 to 1.0) were high, indicating that peach palm is predominantly allogamous. The outcrossing rates among relatives were significantly different from zero (0.101 to 0.202), providing evidence for considerable biparental inbreeding within populations, probably due to farmers planting seeds of a small number of open-pollinated progenies in the same plot. The correlations of paternity estimates were low (0.051 to 0.112), suggesting a large number of pollen sources (9 to 20) participating in pollination of individual fruit bunches. Effective population size estimates suggest that current germplasm collections are insufficient for long-term ex situ conservation. As with most underutilized crops, on farm conservation is the most important component of an integrated conservation strategy

Local-Scale Patterns of Genetic Variability, Outcrossing, and Spatial Structure in Natural Stands of Arabidopsis thaliana

As Arabidopsis thaliana is increasingly employed in evolutionary and ecological studies, it is essential to understand patterns of natural genetic variation and the forces that shape them. Previous work focusing mostly on global and regional scales has demonstrated the importance of historical events such as long-distance migration and colonization. Far less is known about the role of contemporary factors or environmental heterogeneity in generating diversity patterns at local scales. We sampled 1,005 individuals from 77 closely spaced stands in diverse settings around Tübingen, Germany. A set of 436 SNP markers was used to characterize genome-wide patterns of relatedness and recombination. Neighboring genotypes often shared mosaic blocks of alternating marker identity and divergence. We detected recent outcrossing as well as stretches of residual heterozygosity in largely homozygous recombinants. As has been observed for several other selfing species, there was considerable heterogeneity among sites in diversity and outcrossing, with rural stands exhibiting greater diversity and heterozygosity than urban stands. Fine-scale spatial structure was evident as well. Within stands, spatial structure correlated negatively with observed heterozygosity, suggesting that the high homozygosity of natural A. thaliana may be partially attributable to nearest-neighbor mating of related individuals. The large number of markers and extensive local sampling employed here afforded unusual power to characterize local genetic patterns. Contemporary processes such as ongoing outcrossing play an important role in determining distribution of genetic diversity at this scale. Local “outcrossing hotspots” appear to reshuffle genetic information at surprising rates, while other stands contribute comparatively little. Our findings have important implications for sampling and interpreting diversity among A. thaliana accessions

Anurans from the Lower Cretaceous Jehol Group of western Liaoning, China

BACKGROUND: To date, the Lower Cretaceous Jehol Group of western Liaoning, China has yielded five monotypic genera of anurans, including Liaobatrachus grabaui, Callobatrachus sanyanensis, Mesophryne beipiaoensis, Dalianbatrachus mengi, and Yizhoubatrachus macilentus. However, the validity and distinctness of these taxa have been questioned. METHODOLOGY/PRINCIPAL FINDING: We provide a comprehensive analysis of the Jehol frogs that includes a re-examination of the published taxa as well as an examination of a number of new specimens that have been collected over the past 10 years. The results show that the five previously named taxa can be referred to three species of one genus-Liaobatrachus grabaui, L. beipiaoensis comb. nov. and L. macilentus comb. nov.. The diagnosis of Liaobatrachus is revised, and a new diagnosis is provided for each species of this genus. We also establish Liaobatrachus zhaoi sp. nov., on the basis of a dozen well-preserved specimens from a new locality. This taxon is distinguished by a unique combination of characteristics, including relatively long hind limbs, a rounded rather than triangular acetabulum, and a gradually-tapering cultriform process of the parasphenoid. In addition, an unnamed frog from a higher horizon, which has narrow sacral diapophyses and particularly long legs, is different from Liaobatrachus and represents another form of anuran in the Jehol Biota. CONCLUSION/SIGNIFICANCE: Comparisons with other Mesozoic and extant anurans and the primary phylogenetic analysis both suggest that Liaobatrachus is a member of the anuran crown-group and forms a polytomy with leiopelmatids (Ascaphus and Leiopelma) and the remaining crown-group anurans (Lalagobatrachia).Liping Dong, Zbyněk Roček, Yuan Wang, Marc E H. Jone

Immunotherapy of spontaneous mammary carcinoma with fusions of dendritic cells and mucin 1-positive carcinoma cells

The tumour-associated antigen mucin 1 (MUC1) is a multifunctional protein involved in protection of mucous membranes, signal transduction, and modulation of the immune system. More than 70% of cancers overexpress MUC1, making MUC1 a potential target for immunotherapy. In the present study, MUC1 transgenic mice were crossed with syngeneic strains that express the polyomavirus middle-T oncogene (PyMT) driven by the mouse mammary tumour virus promoter long-terminal repeat (MMTV-LTR). The resultant breed (MMT mice) developed spontaneous MUC1-expressing mammary carcinomas with 100% penetrance at 8–15 weeks of age. As found in human breast cancer, the mammary carcinoma in MMT mice arose in multiple stages. Immunization with fusions of dendritic cells and MUC1-positive tumour cells (FC/MUC1) induced MUC1-specific immune responses that blocked or delayed the development of spontaneous breast carcinomas. In contrast, there was no delay of tumour development in MMT mice immunized with irradiated MC38/MUC1 tumour cells. The efficacy of fusion cells was closely correlated with the timing of initial immunization. Immunization with FC/MUC1 initiated in MMT mice at < 1, 1–2 and 2–3 months of age rendered 33, 5 and 0% of mice free of tumour, respectively, up to 6 months. Whereas mice immunized in the later stage of tumour development succumbed to their disease, immunization resulted in control of tumour progression and prolongation of life. These results indicate that immunization with FC/MUC1 can generate an anti-MUC1 response that is sufficient to delay the development of spontaneous mammary carcinomas and control tumour progression in MMT mice