We used six ruminally cannulated steers in a two-period crossover design to study ruminal fermentative and microbial changes associated with induced subacute acidosis. Steers were adapted to either an 80% alfalfa hay (hay-adapted)- or corn grain (grain-adapted)-based concentrate diet. After feed was withheld for 24 h, steers were overfed with an all-grain diet at 3.5 x NEm daily for 3 d. Rumina...

In it, the authors question whether there is adequate evidence to consider this multiflagellated protozoon of significant importance in the context of the respiratory tract. Mu et al. [2] have also suggested that all the cases diagnosed as pulmonary L. blattarum infection reported in China were misdiagnosed. It is true that it is difficult for microscopists who are not familiar with the techniq...

Protistan assemblages of aquatic ecosystems are the focus of extensive research in aquatic ecology. One stimulus for this work has been the long-standing recognition that phototrophic protists (the unicellular algae) constitute a major fraction of the primary productivity within aquatic ecosystems. Another incentive has been the realization that protozoa (heterotrophic protists) play a pivotal ...

In ciliates, a variety of processes are regulated by Ca2+, e.g., exocytosis, endocytosis, ciliary beat, cell contraction, and nuclear migration. Differential microdomain regulation may occur by activation of specific channels in different cell regions (e.g., voltage-dependent Ca2+ channels in cilia), by local, nonpropagated activation of subplasmalemmal Ca stores (alveolar sacs), by different s...

The roles free-living amebae and the parasitic protozoa Entamoeba histolytica and Balantidium coli play as agents of waterborne zoonotic diseases are examined. The free-living soil and water amebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are recognized etiologic agents of mostly fatal amebic encephalitides in humans and other animals, with immunocompromised and immunoc...

In ciliates, a variety of processes are regulated by Ca', e.g., exocytosis, endocytosis, ciliary beat, cell contraction, and nuclear migration. Differential microdomain regulation may occur by activation of specific channels in different cell regions (e.g., voltagedependent Ca' channels in cilia), by local, nonpropagated activation of subplasmalemmal Ca stores (alveolar sacs), by different sens...

The demarcation of protist kingdoms is reviewed, a complete revised classification down to the level of subclass is provided for the kingdoms Protozoa, Archezoa, and Chromista, and the phylogenetic basis of the revised classification is outlined. Removal of Archezoa because of their ancestral absence of mitochondria, peroxisomes, and Golgi dictyosomes makes the kingdom Protozoa much more homoge...

Protistan bacterivory, a microbial process involving ingestion and digestion, is ecologically important in the microbial loop in aquatic and terrestrial ecosystems. While bacterial resistance to protistan ingestion has been relatively well understood, little is known about protistan digestion in which some ingested bacteria could not be digested in cells of major protistan grazers in the natura...

The ciliated protozoan Tetrahymena thermophila undergoes extensive programmed DNA rearrangements during the development of a somatic macronucleus from the germ line micronucleus in its sexual cycle. To investigate the relationship between programmed DNA rearrangements and transposable elements, we identified several members of a family of non-long terminal repeat (LTR) retrotransposons (retropo...