Populational Changes of the Enteric Protozoans Opalina spp. and Nyctotherus cordiformis During the Ontogeny of Anuran Tadpoles

ABSTRACT. We studied ontogenetic population changes of Opalina and Nyctotherus cordiformis in eight species of tadpoles from 10 sites in east-central Mississippi. Most tadpoles acquired Opalina early in development, while the acquisition of N. cordiformis was variable. Developmental stage, species and collection site explained significant amounts of the variation in Opalina density of tadpoles ( F = 11.6; df = 27, 235; P < 0.0001) and metamorphs ( F = 7.31; df = 24, 84; P < 0.0001). Relationships between Opalina density and host stage showed either (1) a gradual decrease or (2) a gradual increase throughout host ontogeny. Opalina densities declined during metamorphosis. Density variations of N. cordiformis were explained by host species of tadpoles ( F = 9.30; df = 7, 142; P < 0.0001) and by host species and stage of metamorphs ( F = 5.85; df = 8, 62; P < 0.0001).
The length of larval period, habitat duration and generation time of the protozoans are suggested as major modifiers of the protozoan densities. Hosts with long larval periods show a decreasing population density and hosts with short developmental periods show a pattern of increasing density. Neither pattern was detected in tadpoles from temporary sites. Metamorphic declines in protozoan density, but not necessarily the loss of protozoans, reflect metamorphic alterations of the gut common to all hosts.     

Prey diversity and selectivity of the African fish eagle: data from a roost in northern Kenya

A total of 1872 bones from a fish eagle roost at Lake Turkana, Kenya was identified and analysed to provide data on fish eagle prey and diet. The approach of this study complements field observation studies in that it provides a long‐term analysis and quantification of the diet, rather than short qualitative observations. The study found that, at least where fish is relatively abundant, fish eagles are both selective and opportunistic: selective in taking preferred fish in much greater proportions than natural availability, and also in avoiding unwanted fish regardless of abundance, but opportunistic in taking certain other species in proportion to their availability. They also show considerable selection in size and habitat preferences of prey. Non‐fish prey forms a considerable proportion of the diet, and probably represents both opportunistic hunting, possibly when conditions for fishing are poor, and killing of other predators robbing fish eagle nests.
As well as describing and quantifying the fish eagle diet at Lake Turkana, data from this study suggest that further study is needed to quantify the impact of fish eagle predation on Clarias lazera , a rare, but valuable species to the Lake Turkana fishery. The study of bird roost prey remains also provides baseline data for studies of fossil microfaunal accumulations. Scatters of bones under fish eagle roosts are common in eastern Africa, and undoubtedly contribute to many of the fossil bone accumulations recovered. One of us (DM) has noted that the taxonomic and skeletal composition of the Koobi Fora roost bears a great resemblance to some of the clusters she is analysing from Olduvai Gorge. Further similar studies will provide additional data on bird roost accumulations.     

The Ultrastructure of Chaenea teres and an Analysis of the Phylogeny of the Haptorid Ciliates

Chaenea teres has typical haptorid ultrastructure. The somatic monokinetid has two transverse microtubular ribbons, an overlapping postciliary microtubular ribbon, and a laterally directed kinetodesmal fiber. The evered cytopharynx forms a dome at the apical end of the cell. The base of the dome is surrounded by oral dikinetids. The left, anterior kinetosome of the oral pair is not ciliated and has a transverse microtubular ribbon, a nematodesmata and a single postciliary microtubule. The right, posterior kinetosome is ciliated and has only postciliary microtubules. The kinetosomes at the anterior ends of the somatic kinetics are close together and their transverse microtubules and nematodesmata contribute to the support of the cytopharynx. The transverse microtubules of these oralized somatic kinetosomes, together with those from the oral dikinetids, line the cytopharynx. Accessory or bulge microtubules arise perpendicular to the transverse microtubules. A dorsal brush of three kineties of clavate cilia is found on the cell surface just posterior to the oral region. Mucocysts and a single type of toxicyst are present. The toxicysts are confined to the oral region. There are multiple ovoid macronuclei that stain weakly. Micronuclei were not observed. Cladistic analysis indicates the Chaenea may be most closely related to Fuscheria and Acropisthium. The cladistic analysis also suggests that existing taxonomies of the subclass Haptoria need to be revised. We propose some modifications to Foissner & Foissner's classification that include transferring Helicoprorodon, Actinobolina, the buetschiliids, and the balantidiids to the order Haptorida and recognizing the close relationship between pleurostomes and spathidiids.     

Devonian monospecific assemblages: new insights into the ecology of reduced-oxygen depositional settings

Low-diversity fossil assemblages interpreted as representing dysaerobic communities are common in the Phanerozoic rock record, and those composed of a single species have particular utility for recognizing the lowest bottom-water oxygen levels. An unusually high-diversity of clades including three rhynchonelliform, two linguliform, and one bivalve species occur in monospecific assemblages within Middle and Upper Devonian black shales of New York State. These six taxa are interpreted to be adapted to extremely reduced bottom-water oxygen levels as inferred from detailed sedimentological data and their repeated monospecific occurrence; however these groups represent two distinct ecologies. Three of these taxa are restricted to sediments deposited under the lowest dysaerobic conditions, while the other three taxa, unlike other fossils characteristic of reduced-oxygen levels, also occur in and are even dominant in high-diversity assemblages. The rhynchonellid brachiopod Eumetabolotoechia multicostata is the most abundant taxon within these units and has a remarkable ecological range as dominant from the lowest dysaerobic zone to near-normal marine oxygen levels. These Devonian groups, when present in monospecific assemblages, have utility for characterizing the lowest dysaerobic zone where trace fossil assemblages, most commonly used to describe these low-oxygen depositional settings, are absent or poorly developed.     

Phylogeny and Systematic Position of Zosterodasys (Ciliophora, Synhymeniida): A Combined Analysis of Ciliate Relationships Using Morphological and Molecular Data

ABSTRACT. The Synhymeniida is characterized both by a band of somatic dikinetids, the synhymenium, extending across the surface of the cell and by a ventral cell mouth lacking specialized feeding cilia but subtended by a well-developed cyrtos. The synhymeniids have been hypothesized to be members of the class Nassophorea but our previous ultrastructural study of the synhymeniid genus Zosterodasys did not show any clear synapomorphies that would permit definitive placement in the Nassophorea or as a sister taxon to any of the other ciliate groups possessing a cyrtos. In the present study, simultaneous analysis of morphological and small subunit rDNA molecular data indicates that the Synhymeniida are sister to the class Phyllopharyngea and that this clade is, in turn, sister to the remaining Nassophorea, although this result is sensitive to dataset inclusion and alignment parameters. While this suggests that taxa with a ventral cyrtos might be united into a named taxon (e.g. resurrecting the Hypostomata), additional data are needed to reach a definitive conclusion.     

HIV risk behaviors among outpatients with severe mental illness in Rio de Janeiro,Brazil

We conducted the first study to examine rates of sexual activity, sexual risk behaviors, sexual protective behaviors, injection drug use (IDU), needle sharing, and knowledge about HIV/AIDS among outpatients with severe mental illness (SMI) in Rio de Janeiro, Brazil. Using a measure with demonstrated reliability, we found that 42% of 98 patients engaged in vaginal or anal sex within the past three months. Comorbid substance use disorder was significantly associated with sexual activity. Only 22% of sexually active patients used condoms consistently, despite having better HIV knowledge than those who were sexually abstinent. Overall, 45% of patients reported not engaging in any HIV protective behaviors. There were no reports of drug injection. Adults with SMI in Brazil are in need of efficacious HIV prevention programs and policies that can sustain these programs within mental health treatment settings.     

Studies on the Action of the Nuclear Factor Promoting Actinomycin D-Binding Capacity of Chromatin

It is well known that actinomycin D binds to C-G pairs of DNA. The amount of actinomycin D bound to chromatin thus depends directly on the demasked sites of chromatin DNA. The actinomycin D binding of rat liver chromatin, obtained by the method of Dingman and Sporn, was studied in the presence and absence of liver and kidney nuclear extracts (NE). The actinomycin D binding of liver chromatin increases greatly under the action of liver nuclear extract. No changes occur in liver chromatin actinomycin D binding capacity after the action of kidney NE. The removal of protein or RNA from liver NE removes its ability to change the actinomycin D binding capacity of the liver chromatin. According to the obtained results it may be assumed that the nuclear extract contains the factor which plays a role in controlling cell differentiation.