Trypanosome Prereplication Machinery: A Potential New Target for an Old Problem

Approximately ten million people suffer from Chagas disease worldwide, caused by Trypanosoma cruzi, with the disease burden predominately focused in Latin America. Sleeping sickness is another serious health problem, caused by Trypanosoma brucei, especially in sub-Saharan countries. Unfortunately, the drugs currently available to treat these diseases have toxic effects and are not effective against all disease phases or parasite strains. Therefore, there is a clear need for the development of novel drugs and drug targets to treat these diseases. We propose the trypanosome prereplication machinery component, Orc1/Cdc6, as a potential target for drug development. In trypanosomes, Orc1/Cdc6 is involved in nuclear DNA replication, and, despite its involvement in such a conserved process, Orc1/Cdc6 is distinct from mammalian Orc1 and Cdc6 proteins. Moreover, RNAi-mediated silencing of trypanosome Orc1/Cdc6 expression in T. brucei decreased cell survival, indicating that Orc1/Cdc6 is critical for trypanosome survival

Trypanosoma cruzi DNA replication includes the sequential recruitment of pre-replication and replication machineries close to nuclear periphery

In eukaryotes, many nuclear processes are spatially compartmentalized. Previously, we have shown that in Trypanosoma cruzi, an early-divergent eukaryote, DNA replication occurs at the nuclear periphery where chromosomes remain constrained during the S phase of the cell cycle. We followed Orc1/Cdc6, a pre-replication machinery component and the proliferating cell nuclear antigen (PCNA), a component of replication machinery, during the cell cycle of this protozoon. We found that, at the G(1) stage, TcOrc1/Cdc6 and TcPCNA are dispersed throughout the nuclear space. During the G(1)/S transition, TcOrc1/Cdc6 migrates to a region close to nuclear periphery. At the onset of S phase, TcPCNA is loaded onto the DNA and remains constrained close to nuclear periphery. Finally, in G(2), mitosis and cytokinesis, TcOrc1/Cdc6 and TcPCNA are dispersed throughout the nuclear space. Based on these findings, we propose that DNA replication in T. cruzi is accomplished by the organization of functional machineries in a spatial-temporal manner.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Universidade Federal de São Paulo, Parasitol Lab, Inst Butantan, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilUniv Fed Rio de Janeiro, Inst Biofis Carlos Chagas Filho, Lab Ultraestrutura Celular Hertha Meyer, BR-21941 Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Parasitol Lab, Inst Butantan, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, São Paulo, BrazilWeb of Scienc

Studies of the Orc1/Cdc6 component of pre-replication machinery of trypanosomes.

Em eucariotos, a origem de replicação é reconhecida por um complexo ORC, a proteína Cdc6 e outras proteínas. Nos tripanossomas, encontramos somente uma proteína similar a Orc1 e Cdc6, que chamaremos de Orc1/Cdc6. Nesta tese serão descritos os estudos realizados sobre Orc1/Cdc6 do Trypanosoma cruzi e do Trypanosoma brucei. As proteínas recombinantes dos tripanossomas apresentam atividade de ATPase e são capazes de substituir Cdc6 em ensaio de complementação em leveduras. A indução do silenciamento do gene de Orc1/Cdc6 por RNAi resulta em células anucleadas. Orc1/Cdc6 é expressa durante todo o ciclo celular das formas replicativas, permanecendo associada à cromatina. No caso do T.cruzi, Orc1/Cdc6 é expressa não só nas formas replicativas, mas também nas formas não replicativas. Nestas últimas, a proteína expressa não interage com o DNA, este resultado sugere que a ausência desta interação deve contribuir para ausência da duplicação do DNA nas formas infectivas do T. cruzi.In eukaryotes, the replication origin is recognized by a complex ORC, Cdc6 and other proteins. The trypanosomes contain only one protein, we named it Orc1/Cdc6. Here we show that the recombinant Orc1/Cdc6 from T.cruzi (TcOrc1/Cdc6) and from T.brucei (TbOrc1/Cdc6) present ATPase activity, replaced yeast Cdc6 in a phenotypic complementation assay. The induction of Orc1/Cdc6 silencing by RNA interference in T.brucei resulted in enucleated cells. Orc1/Cdc6 is expressed during the entire cell cycle and in all stages of the life cycle of trypanosomes, remaining associated with chromatin in all stages of the cell cycle. This association is different among the stages from T. cruzi life cycle. In the non replicative ones, Orc1/Cdc6 does not interact with DNA. The lack of pre-replication machinery-DNA interaction in T. cruzi non-replicative stages might contribute to the absence of DNA replication in these stages

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data

NEOTROPICAL CARNIVORES: a data set on carnivore distribution in the Neotropics

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non-detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non-governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer-reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non-detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio-temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large-scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data