Ultrastructural Study on the Development of Babesia equi (Coccidia: Piroplasmia) in the Salivary Glands of its Vector Ticks1

The formation of Babesia equi sporozoites in the salivary glands of three tick species (Hyalomma anatolicum anatolicum, H. a. excavatum, Rhipicephalus turanicus) was studied by electron microscopy. The development was identical in all three vectors. On the 8th day post repletionem kinetes of B. equi had invaded alveoli of the nymphal salivary glands and were transformed to sporonts bounded by a single membrane. The sporonts were polymorphous bodies each with a highly lobed nucleus and numerous mitochondria. These stages persisted during ecdysis of the tick nymph to the adult stage. After attachment of these newly molted adults to a new host the formation of sporozoites was completed within five days. The sporonts occupied most of the infected alveolus and were extensively divided into cytoplasmic portions of various size. On the 4th day after attachment of the tick, sporozoite-anlagen, into each of which a nucleus and a mitochondrion were incorporated, appeared at the periphery of the sporonts. An apical complex with a polar ring, rhoptries, and micronemes was formed at the tip of each protruding anlage. Finally thousands of pyriform sporozoites (3.0 × 1.2 μm) filled the hypertrophied alveolus. This development is similar to sporogony in the genus Theileria.     

Mammalian Cross-Reactive H-Y Antigen Induces Sex Reversal in vitro in the Avian Testis

Testes of either newborn rats or newly hatched chickens, dissociated into single cell suspensions, reorganize in vitro into their histotypic structures. In birds, the heterogametic female sex is H-Y antigen positive, and not the male as in mammals. Cocultivation of rat and chicken testicular cells results in the reorganization of an ovotestis. A similar result is obtained after cultivation of chicken testicular cells in the supernatant medium of cultured human male Burkitt lymphoma Daudi cells. Rat testicular Sertoli cells as well as Daudi cells are a source of H-Y antigen. The simultaneous application of H-Y antigen and anti-H-Y antiserum prevents ovotestis formation. It is concluded that H-Y antigen which is known to be testis-organizing in mammals, is the ovary-organizing factor in birds.     

Phycobiliprotein fluorescence of Nostoc punctiforme changes during the life cycle and chromatic adaptation: characterization by spectral confocal laser scanning microscopy and spectral unmixing

Many cyanobacteria are highly adaptable to light quality, and many species undergo a complex life cycle. In this study we show that adaptive changes in the photosynthetic apparatus of cyanobacteria are not only caused by environmental, but also by developmental factors. Spectral confocal laser scanning microscopy (CLSM) was used to analyse in vivo the fluorescence spectra of the photosynthetic pigments chlorophyll a (Chl a), allophycocyanin (APC), phycocyanin (PC) and phycoerythrin (PE) of two Nostoc punctiforme strains. Changes in pigment fluorescence emission occurred in different developmental stages. Strain 1:1-26 showed an emission maximum at 674 nm in motile hormogonia stages, whereas vegetative stages showed maxima at 658 and 575 nm. These changes were not caused by chromatic adaptation. In contrast, the second strain (1:1-26lg) showed distinct fluorescence spectra, pigment localization and clear chromatic adaptation in red light. When these properties are known, both strains can be easily distinguished by the spectral CLSM method, which also allows the localization of the pigments within single cells. To calculate the contribution of individual phycobiliproteins to the observed changes, fluorescence spectra were analysed by spectral unmixing. This allowed the mathematical estimation of fluorescence shares for the individual phycobiliproteins in different developmental stages and both before and after chromatic adaptation. It is concluded that care should be taken when characterizing cyanobacteria by differences in pigment fluorescence, because these differences are influenced not only by chromatic adaptation, but also developmental stages. Spectral CLSM offers a powerful method to study the phycobiliprotein composition in vivo.