A vegetation classification and description of white-winged flufftail (Sarothrura ayresi) habitat at selected high-altitude peatlands in South Africa.

The white-winged flufftail is listed as critically endangered, and limited knowledge about the species' ecology has been identified as a limiting factor to effectively conserving the bird. Little is known about the vegetation inhabited by the white-winged flufftail, which hampers the identification and management of its habitat. This study presents a fine-scale classification and description of the vegetation of wetland sites where the bird is known to be present. A plant phytosociological study was conducted to describe the plant communities and vegetation structure of the habitat. Three sites were selected at Verloren Valei Nature Reserve and two at Middelpunt Wetland, Mpumalanga, South Africa, shortly after the white-winged flufftail breeding season. A total of 60 sample plots were placed within the study sites, where all plant species present were recorded and identified. Other aspects such as plant height, water depth and anthropogenic influences were also documented. A modified TWINSPAN analysis resulted in the identification of three sub-communities that can be grouped into one major community. The Cyperaceae, Asteraceae and Poaceae families dominate the vegetation, with the sedges Carex austro-africana and Cyperus denudatus being dominant, and the grasses Leersia hexandra and Arundinella nepalensis co-dominant. The broad habitat structure consisted of medium to tall herbaceous plants (0.5-0.7 m) with shallow slow-flowing water.

Critical obstruction of the right ventricular outflow tract by a primary hemangioendothelioma in a seven month old.

A 7-month-old presented with failure to thrive and a murmur. Echocardiography demonstrated a large mass in the right ventricular outflow tract, extending through the pulmonary valve. During anaesthetic induction this caused critical obstruction of the outflow tract and cardiac arrest. Pathological diagnosis showed the lesion to be a primary hemangioendothelioma. Despite surgical excision and steroid therapy, the mass continued to grow for a period of 8 weeks, but then began to regress spontaneously.

Differentiation between human and animal isolates of Cryptosporidium parvum using molecular and biological markers.

Isolates of Cryptosporidium parvum obtained from infected humans, calves and lambs were typed using arbitrary primed polymerase chain reaction (AP-PCR) and isoenzyme electrophoresis. All animal isolates tested (n = 17) showed similar profiles in AP-PCR and isoenzyme typing. In AP-PCR assays, 9 out of 15 human isolates showed a distinct "human" profile while the remaining 6 isolates showed the "animal" profile. In isoenzyme typing, 5 human isolates which had shown "human" profiles in AP-PCR demonstrated a unique isoenzyme banding pattern, while 2 isolates which had shown "animal" profiles in AP-PCR gave the "animal" banding pattern. In a murine model of infection, all four animal isolates tested were highly infective but only one of four human isolates identified as "human" type in the AP-PCR and isoenzyme typing systems was infective. The good correlation between the data from the different typing systems supports the hypothesis that there are genetically distinct human and animal populations of C. parvum.

Immunity to Cryptosporidium muris infection in mice is expressed through gut CD4+ intraepithelial lymphocytes.

The role of gut intraepithelial lymphocytes (IEL) in immunity to cryptosporidial infection was investigated with a murine infection model involving Cryptosporidium muris. Oocyst shedding was monitored in severe combined immunodeficiency (SCID) mice infected with C. muris following intravenous injection of mesenteric lymph node (MLN) cells or intestinal IEL from BALB/c donor mice which were naive or previously infected with C. muris. SCID mice receiving no lymphoid cells developed chronic infections and excreted large numbers of oocysts until the end of the experiment. SCID mice injected with IEL from immune animals, however, were able to overcome the infection, and furthermore, these animals produced fewer oocysts and recovered sooner than ones which received IEL or MLN cells from naive BALB/c donors. Similar levels of protection were obtained in SCID mice injected with either 2 X 10(6) IEL or MLN cells from immune donor mice. Depletion of CD4+ cells from immune IEL, however, abrogated the ability to transfer immunity to SCID mice, while depletion of CD8+ cells only marginally reduced the protective capacity of immune IEL. Finally, control SCID mice which received no lymphocytes had < or = 1% CD4+ cells in the IEL from the small intestine, whereas the IEL from SCID mice recovered from infection, as a result of injection with immune IEL, contained 15% CD4+ cells. Thus, the ability to control C. muris infection correlated with the presence of the protective CD4+ cells in the gut epithelium.

Murine infection model for maintenance and amplification of Cryptosporidium parvum oocysts.

Propagation of Cryptosporidium parvum is problematic because in vitro development of the parasite is poor and animals are only briefly susceptible as neonates. At present oocysts of the parasite are usually procured by passage in neonatal sheep or cattle. In the present study, large numbers of oocysts of C. parvum could be isolated following infection of dexamethasone-treated adult C57BL/6 mice. The amount of immunosuppressive drug and the regimen of administration were critical for successful maintenance of the parasite, however. Routinely, 10 mice (age, 8 to 12 weeks) were injected four times on alternate days with 1.0 mg of dexamethasone, and the last injection was given on the same day as oral inoculation with 10(6) oocysts. By using a simplified procedure for oocyst purification from mouse feces, approximately 10(9) oocysts were obtained. This model is inexpensive and comparatively safe to handle, and the numbers of animals inoculated can be varied to obtain the required number of oocysts. Thus, this murine infection model would be a suitable alternative to the use of neonatal calves or sheep for efficient oocyst propagation.

Differentiation between human and animal strains of Cryptosporidium parvum using isoenzyme typing.

Isoenzyme typing was used to study a number of oocyst isolates of Cryptosporidium parvum from different geographical locations and of human or animal origin. All isolates showed identical enzyme motility when glucose phosphate isomerase (GPI; 23 isolates tested) or lactate dehydrogenases (LDH; 20 isolates tested) was assayed. However, two isoenzyme forms were observed with phosphoglucomutase (PGM; 9 animal isolates showed one form, while 8/9 human isolates showed a second form) and hexokinase (HK; 4 human isolates showed one form and 6 animal isolates showed a second form). Thus, PGM and HK each exhibit 2 isoenzymes corresponding to 2 parasite populations associated with separate hosts. The data from this study, plus supportive evidence obtained by different methods and by independent researchers, lend support to the hypothesis that separate cycles of transmission of C. parvum may exist within human and animal hosts.

Cryptosporidium muris in adult mice: adoptive transfer of immunity and protective roles of CD4 versus CD8 cells.

The aim of this study was to investigate the role of the CD4 and CD8 T cells in immunity to cryptosporidia by using Cryptosporidium muris and a mouse model of infection. Two approaches were used, each involving the use of rat anti-T-cell surface marker monoclonal antibodies (MAbs). In the first, the adoptive transfer of immunity was studied by using the CB.17 SCID mouse (which lacks T and B cells) as the host; in the second, the effect on susceptibility of BALB/c mice to infection was examined following depletion of T cells or subsets of T cells. In adoptive immunity experiments, the conditions which differentiated between resistance associated with reconstitution of SCID mice with naive BALB/c lymphocytes and the transfer of immunity with primed lymphocytes from infected animals were determined. Primed spleen or mesenteric lymph node cells conferred better protection to recipients than naive cells when obtained from donors which had developed resistance to infection. Adoptive immunity was abrogated when Thy.1 cells or CD4 cells were depleted from primed cells, while depletion of CD8 cells could reduce the level of protection. In the study of C. muris in BALB/c mice, treatment with either anti-Thy.1 plus anti-Lyt.1 or anti-CD4 MAbs increased susceptibility to a primary infection as determined by the size and duration of oocyst production, but an anti-CD8 MAb produced an increase only in oocyst shedding. Thus, both CD4 and, to a lesser extent, CD8 cells appeared to be involved in resistance to primary and secondary C. muris infection.

Isoenzyme variation within the genus Cryptosporidium.

Soluble extracts of the oocysts of Cryptosporidium parvum had demonstrable, but low, activities of malate dehydrogenase (MDH, EC. 1.1.1.37), carboxylesterase (ES, EC 3.1.1.1) and lactate dehydrogenase (LDH, EC. 1.1.1.27) following thin-layer starch-gel electrophoresis. Much higher activities of glucose phosphate isomerase (GPI, EC. 5.3.1.9) and phosphoglucomutase (PGM, EC. 2.7.5.1) were found, and zymograms of these two enzymes were used to characterise isolates of C. parvum from human, bovine, ovine and cervine sources, C. muris from the brown rat and C. baileyi from young turkeys. PGM and GPI zymograms clearly distinguished between C. parvum, C. muris and C. baileyi. The five isolates of C. parvum showed the same electrophoretic mobility for GPI, whereas the PGM mobility of the single human isolate of C. parvum examined was clearly different from that of the other isolates. This is the first report of the use of isoenzymes to distinguish between species and isolates of Cryptosporidium.

Hydrogen ion titration and amino acid analysis of hemocyanin from the spiny lobster Jasus edwardsii.

Potentiometric and spectrophotometric titrations, isoelectric focusing and amino acid analyses, have been made on the hemocyanin from Jasus edwardsii. Counts of acidic neutral and alkaline groups were made from the titrations, enabling comparisons to be made with the amino acid analysis. Thermodynamic analysis of the data indicated that changes in the native protein structure took place at pH 4.0, 8.4 and 10.7. These observations are discussed in terms of dissociation, shifts in pK and conformational changes in the protein.