The physical dormancy of seeds has been poorly studied in species from tropical forests, such as the Atlantic Forest. This study aimed to examine the effect of moderate alternating temperatures on breaking the physical dormancy of seeds, the morphoanatomy and histochemistry of seed coats, and to locate the structure/region responsible for water entrance into the seed, after breaking the physica...

During the summers of 2000, 2001, and 2002, 1,950 fecal samples from 4 families, 10 genera, and 16 species of rodents in Alaska, U.S.A. (N1⁄41,711), and Siberia, Russia (N1⁄4239) were examined for coccidia (Apicomplexa: Eimeriidae). The 4 families sampled were Dipodidae (jumping mice), Erethizontidae (New World porcupines), Muridae (mice, rats), and Cricetidae (voles, lemmings). Nineteen oocyst...

The Coccidia and the Cryptosporidia infect both coldand warm-blooded vertebrates, yet members of the genera Toxoplasma, Eimeria, Sarcocystis, and Cryptosporidium (which mostly parasitize the latter hosts) have received most of the attention by far because of their importance to human and veterinary health. Our knowledge about a wide array of apicomplexans found in fish, amphibians, and reptiles...

A moderate amount of information is available on coccidian parasites (Apicomplexa) of snakes of Oklahoma (McAllister et al. 1995, 2011, 2013), and, although another reptile from the state, the ground skink (Scincella lateralis) has been thoroughly surveyed (McAllister et al. 1994, 2014), nothing, to our knowledge, has been published on coccidia of any lizard in Oklahoma. Yet, Oklahoma supports ...

Six new species of coccidia are described from endangered Phelsuma spp. geckoes (Sauria: Gekkonidae) endemic to Mauritius, Indian Ocean. Five new species (3 Eimeria and 2 Isospora species) are described from Phelsuma rosagularis Vinson et Vinson; all lack a micropyle and an oocyst residuum, and all have a sporocyst residuum. Oocysts of Eimeria swinnertonae sp. n. are ellipsoidal, 22.2 x 17.8 (2...

Title of Document: POLLEN TUBES FAIL TO TARGET OVULE IN THE ABSENCE OF TWO CATION/PROTON EXCHANGERS IN ARABIDOPSIS Yongxian Lu Doctor of Philosophy, 2010 Directed By: Professor Heven Sze Department of Cell Biology & Molecular Genetics Flowering plant reproduction requires precise delivery of the sperm cells to the ovule by a pollen tube. Guiding signals from female cells are being identified, t...

Meiosis is a central feature in the reproductive program of plants and all other sexually reproducing eukaryotes. In plants such as Arabidopsis thaliana, reproduction initiates during the development of the male (anther) and female (ovule) reproductive structures from somatic tissue. During anther development, a group of cells differentiate to form archesporial cells, which in turn give rise to...

OBJECTIVE To observe morphological details of the eggs of Haemagogus (Conopostegus) leucocelaenus, seen for the first time via scanning electron microscopy (SEM), with morphometric analysis of the main structures. METHODS Eggs of Hg. leucocelaenus were obtained from females captured in the Biological Reserve of Tinguá, State of Rio de Janeiro. Some of the eggs were kept for hatching and other...

A new coccidian parasite of the genus Caryospora Léger, 1904 is described from the colubrid snake Psammophis schokari (Forskål, 1775). Oocysts of Caryospora maxima sp. n. are spherical or subspherical, 43.0 (40.0-46.0) × 42.1 (40.0-44.0) μm, with smooth and bilayered oocyst wall ca. 2.0 μm thick. A micropyle, oocyst residuum and polar granule are absent. Sporocysts are broadly ellipsoidal, 21.3...

A tiny, dry ball comprising two sperm cells and a vegetative cell protected by a tough layer of sporopollenin (otherwise known as a pollen grain) lands on a stigma. Upon hydration, the vegetative cell gives rise to a pollen tube, which travels through the style to the micropyle, a minute opening in the ovule. Given the proper signals from the synergids in the waiting embryo sac, the pollen tube...