Search Results (4)

Objective: We evaluate the immunotherapeutic potential of the yellow fever virus vaccine strain 17D (YFV 17D) for intratumoral therapy of pancreatic cancer in mice. Methods: The cytopathic effect of YFV 17D on mouse syngeneic pancreatic cancers cells were studied both in vitro and in vivo and on human pancreatic cancers cells in vitro. Results: YFV 17D demonstrated a strong cytopathic effect against human cancer cells in vitro. Although YFV 17D did not exhibit a lytic effect against Pan02 mouse cells in vitro, a single intratumoral administration of 17D caused a delay in tumor growth and an increase in median survival by 30%. Multiple injections of 17D did not further improve the effect on tumor growth; however, it notably extended the median survival. Furthermore, preliminary immunization with 17D enhanced its oncotherapeutic effect. Conclusions: Intratumoral administration of yellow fever virus vaccine strain 17D delayed tumor in a murine model of pancreatic cancer. The fact that YFV 17D in vitro affected human cancer cells much more strongly than mouse cancer cells appears promising. Hence, we anticipate that the in vivo efficacy of YFV-17D-based oncolytic therapy will also be higher against human pancreatic carcinomas compared to its effect on the mouse pancreatic tumor. Full article

Litter size plays an essential role in mammalian evolution and is one of the most important factors determining whether an organism is deemed to have a ‘slow’ or ‘fast’ life history strategy. Humans are distinct in being classified as having slow life history yet bearing singletons who have completed relatively less growth than other ape neonates. Previous work has proposed that the ancestral primate gave birth to singletons. However, primate litter size has not yet been contextualized within a broad phylogenetic assessment of mammalian life history. We performed a comprehensive investigation of primate litter size using life history data for 155 primate species, and litter size data for an additional 791 boreoeutherian mammals. Litter size and life history traits have strong phylogenetic signal in primates (Pagel’s lambda: 0.99, p < 0.001; Blomberg’s K: 0.6311. p < 0.001), and litter size is significantly negatively correlated with gestation length (p < 0.001). Our data support that the last common ancestors of both primates and Haplorhini gave birth to multiples (litter size 1.7 and 1.6, respectively). We also find that singleton-bearing pregnancies evolved convergently in multiple primate lineages, including tarsiers and other haplorhines. This study contributes significantly to our understanding of life history and litter size in mammals, and we emphasize the utility of a callitrichid model for investigating the evolution of human reproduction. Full article

Tamarins, small Neotropical primates of the genera Saguinus and Leontocebus, have a mainly frugivorous-faunivorous diet. While consuming the pulp of a high diversity of fruit species, they also swallow seeds and void them intact, thus acting as seed dispersers. Here we compare different aspects of the seed dispersal ecology of tamarins with that of large Neotropical primates from the genera Ateles (spider monkeys) and Lagothrix (woolly monkeys). Due to their small body size, tamarins disperse seeds of a smaller size range, fewer seeds per defecation, and seeds from a smaller number of different plant species per defecation compared to these atelines. We discuss whether tamarin seed dispersal is redundant or complementary to seed dispersal by atelines. On the level of plant species, our comparisons suggest that redundancy or complementarity depends on the plant species concerned. On the habitat level, seed dispersal by tamarins and large New World primates is probably complementary. Particularly, since tamarins are capable of persisting in disturbed forests and near human settlements, they are more likely to contribute to the natural regeneration of such areas than larger primates. Full article

The Amazon basin is one of the most biologically diverse places on earth. However, agricultural expansion and infrastructure development have led to widespread deforestation that threatens the survival of many taxa. Conservation strategies to contest these threats include protected areas and environmental legislation. Nevertheless, the basic biology of many taxa is largely unknown, which poses an immense challenge when devising effective strategies to safeguard such species in the long-term. This is particularly true for primates. Monkeys from the genus Mico are poorly studied with half of the currently known species being described after 1976, and their distribution and threats remain poorly understood. Using the model Maxent, we re-evaluated the distribution range for Rondon’s marmoset, one of the most threatened species in this genus. Our results estimated a distribution that is 15,500 km² smaller than previously described for this species (68,649 km²). Furthermore, much of its modeled distribution (71%) lies outside of protected areas. Agriculture expansion and infrastructure development have converted/destroyed 20,532 km² of forest within its range (38%) mainly in areas without protection. Another 10,316 km² of forest is projected to be cleared by 2040 under current deforestation patterns. The expected cumulative loss of over 50% of its range size in the coming 15 years raise awareness about the threaten category of this species. In the absence of new protected areas, it remains to be seen whether Rondon’s marmoset can be effectively conserved in remaining fragments of forest in farmlands. Full article