Ploidy, sex and crossing over in an evolutionary aging model

Nowadays, many forms of reproduction coexist in nature: Asexual, Sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give I possible scenario. By studying the performance of Populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find all evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms oil Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations. (c) 2005 Elsevier B.V. All rights reserved.

Variations in the sensitivity of different primers for detecting Wolbachia in Anastrepha (diptera: tephritidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Wolbachia in Anastrepha Fruit Flies (Diptera: Tephritidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oviposition and survival in females of Procornitermes araujoi under laboratory conditions (Isoptera, Termitidae, Nasutitermitinae)

After an enormous swarming of Procornitermes araujoi when a great number of females were collected, we investigated the occurrence of parthenogenesis beyond oviposition and survival of these females under laboratory conditions. The groups of virgin females were faster in their first oviposition than females of male-female pairs, nevertheless their eggs never hatch. The survival data showed higher longevity in the group of three females when compared with groups of two and four females.

Produção de embriões por fecundação in vitro e ativação partenogenética visando o isolamento de células tronco embrionárias felinas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimulação ovariana, recuperação e maturação de oócitos de veado-catingueiro (Mazama gouazoubira)

Pós-graduação em Medicina Veterinária - FCAV

Interação núcleo-citoplasmática em embriões e expressão de genes imprinted em fetos bovinos produzidos in vivo, in vitro e partenogenéticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Life cycle of Cosmolaelaps jaboticabalensis (Acari: Mesostigmata: Laelapidae) on Frankliniella occidentalis (Thysanoptera: Thripidae) and two factitious food sources

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Imprinted gene expression in in vivo- And in vi/ro-produced bovine embryos and chorio-allantoic membranes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Life cycle and reproductive traits of marine podonids (Cladocera, Onychopoda) in a coastal subtropical area

We studied the temporal distribution and reproductive biology of marine podonids during two consecutive years off Ubatuba, southeast coast of Brazil. Podonid specimens and their eggs and embryos were counted, measured and classified into categories. Pseudevadne tergestina was the most abundant species, and was more abundant in surface layers, in warm seasons, when the water column was stratified because of bottom intrusions of the cold and nutrient-rich South Atlantic Central Water (SACW) onto the inner shelf. Evadne spinifera had a similar temporal and vertical distribution, but with lower abundance and frequency. Pleopis schmackeri did not show a clear seasonal distribution, but preferred bottom layers. Pleopis polyphemoides and Podon intermedius occurred in low abundances, and only under SACW influence. Parthenogenetic females were dominant among all podonid species. Gamogenetic females of P. polyphemoides and P. intermedius were observed, but males of neither species occurred. This suggests that in tropical and subtropical regions, P. tergestina, E. spinifera and P. schmackeri reproduce through parthenogenesis during most of the year.

Reproductive biology and species geographical distribution in the Melastomataceae: a survey based on New World taxa

Apomictic plants are less dependent on pollinator services and able to occupy more diverse habitats than sexual species. However, such assumptions are based on temperate species, and comparable evaluation for species-rich Neotropical taxa is lacking. In this context, the Melastomataceae is a predominantly Neotropical angiosperm family with many apomictic species, which is common in the Campos Rupestres, endemism-rich vegetation on rocky outcrops in central Brazil. In this study, the breeding system of some Campo Rupestre Melastomataceae was evaluated, and breeding system studies for New World species were surveyed to test the hypothesis that apomixis is associated with wide distributions, whilst sexual species have more restricted areas. The breeding systems of 20 Campo Rupestre Melastomataceae were studied using hand pollinations and pollen-tube growth analysis. In addition, breeding system information was compiled for 124 New World species of Melastomataceae with either wide (1000 km) or restricted distributions. Most (80 ) of the Campo Rupestre species studied were self-compatible. Self-incompatibility in Microlicia viminalis was associated with pollen-tube arrest in the style, as described for other Melastomataceae, but most self-incompatible species analysed showed pollen-tube growth to the ovary irrespective of pollination treatment. Apomictic species showed lower pollen viability and were less frequent among the Campo Rupestre plants. Among the New World species compiled, 43 were apomictic and 77 sexual (24 self-incompatible and 53 self-compatible). Most apomictic (86 ) and self-incompatible species (71 ) presented wide distributions, whilst restricted distributions predominate only among the self-compatible ones (53 ). Self-compatibility and dependence on biotic pollination were characteristic of Campo Rupestre and narrowly distributed New World Melastomataceae species, whilst apomictics are widely distributed. This is, to a certain extent, similar to the geographical parthenogenesis pattern of temperate apomictics.

Morphological records of oocyte maturation in the parthenogenetic tick Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae)

Oocyte maturation in the thelytokous parthenogenetic tick Amblyomma rotundatum was examined for the first time using light and scanning electron microscopy. The panoistic ovary lacks nurse and follicular cells and is a single continuous tubular structure forming a lumen delimited by the ovarian wall. Oocytes of tick species are usually classified according to cytoplasm appearance, the presence of germinal vesicle, the presence of yolk granules, and the chorion. However, for this species, we also use oocyte size as an auxiliary tool since most oocytes were in stages I-Ill and were histologically very similar. Oocytes were classified into five development stages, and specific characteristics were observed: mature oocytes with thin chorion, pedicel cells arranged forming an epithelium with two Or more oocytes attached by the same structure, and a large number of oocytes in the process of reabsorption. (C) 2011 Elsevier GmbH. All rights reserved.

The use of parthenotegenetic and IVF bovine blastocysts as a model for the creation of human embryonic stem cells under defined conditions

Clinical application of human embryonic stem cells will be possible, when cell lines are created under xeno-free and defined conditions. We aimed to establish methodologies for parthenogenetic activation, culture to blastocyst and mechanical isolation of the inner cell mass (ICM) using bovine oocytes, as a model for derivation and proliferation of human embryonic stem cells under defined xeno-free culture conditions. Cumulus-oocyte-complexes were in vitro matured and activated using Ca(2+)Ionophore and 6-DMAP or in vitro fertilized (IVF). Parthenotes and biparental embryos were cultured to blastocysts, when their ICM was mechanically isolated and placed onto a substrate of fibronectin in StemProA (R) medium. After attachment, primary colonies were left to proliferate and stained for pluripotency markers, alkaline phosphatase and Oct-4. Parthenogenesis and fertilization presented significantly different success rates (91 and 79 %, respectively) and blastocyst formation (40 and 43 %, respectively). ICMs from parthenogenetic and IVF embryos formed primary and expanded colonies at similar rates (39 % and 33 %, respectively). Six out of eight parthenogenetic colonies tested positive for alkaline phosphatase. Three colonies were analyzed for Oct-4 and they all tested positive for this pluripotency marker. Our data show that Ca2+ Ionophore, and 6-DMAP are efficient in creating large numbers of blastocysts to be employed as a model for human oocyte activation and embryo development. After mechanical isolation, parthenogetic derived ICMs showed a good rate of derivation in fibronectin and Stem-Pro forming primary and expanded colonies of putative embryonic stem cells. This methodology may be a good strategy for parthenogenetic activation of discarded human oocytes and derivation in defined conditions for future therapeutic interventions.

Wolbachia, normally a symbiont of Drosophila, can be virulent, causing degeneration and early death

Wolbachia, a maternally transmitted microorganism of the Rickettsial family, is known to cause cytoplasmic incompatibility, parthenogenesis, or feminization in various insect species. The bacterium–host relationship is usually symbiotic: incompatibility between infected males and uninfected females can enhance reproductive isolation and evolution, whereas the other mechanisms enhance progeny production. We have discovered a variant Wolbachia carried by Drosophila melanogaster in which this cozy relationship is abrogated. Although quiescent during the fly’s development, it begins massive proliferation in the adult, causing widespread degeneration of tissues, including brain, retina, and muscle, culminating in early death. Tetracycline treatment of carrier flies eliminates both the bacteria and the degeneration, restoring normal life-span. The 16s rDNA sequence is over 98% identical to Wolbachia known from other insects. Examination of laboratory strains of D. melanogaster commonly used in genetic experiments reveals that a large proportion actually carry Wolbachia in a nonvirulent form, which might affect their longevity and behavior.

The Mos/mitogen-activated protein kinase (MAPK) pathway regulates the size and degradation of the first polar body in maturing mouse oocytes.

Mos is an upstream activator of mitogen-activated protein kinase (MAPK) and, in mouse oocytes, is responsible for metaphase II arrest. This activity has been likened to its function in Xenopus oocytes as a component of cytostatic factor. Thus, Mos-deficient female mice (MOS-/-) are less fertile and oocytes derived from these animals fail to arrest at metaphase II and undergo parthenogenetic activation [Colledge, W. H., Carlton, M. B. L., Udy, C. B. & Evans, M. J. (1994) Nature (London) 370, 65-68 and Hashimoto, N., Watanabe, N., Furuta. Y., Tamemoto, B., Sagata, N., Yokoyama, M., Okazaki, K., Nagayoshi, M., Takeda, N., Ikawa, Y. & Aizawa, S. (1994) Nature (London) 370, 68-71]. Here we show that maturing MOS-/- oocytes fail to activate MAPK throughout meiosis, while p34cdc2 kinase activity is normal until late in metaphase II when it decreases prematurely. Phenotypically, the first meiotic division of MOS-/- oocytes frequently resembles mitotic cleavage or produces an abnormally large polar body. In these oocytes, the spindle shape is altered and the spindle fails to translocate to the cortex, leading to the establishment of an altered cleavage plane. Moreover, the first polar body persists instead of degrading and sometimes undergoes an additional cleavage, thereby providing conditions for parthenogenesis. These studies identify meiotic spindle formation and programmed degradation of the first polar body as new and important roles for the Mos/MAPK pathway.