Twice-Over Rotational Grazing and Its Impacts on Grassland Songbird Abundance and Habitat Structure

The majority of native prairie has been lost throughout North America. Much of the remaining prairie is used for livestock grazing, so conservation of prairie species depends on sustainable grazing practices. Our objective was to evaluate the benefits of twice-over rotational grazing, in comparison with continuous season-long grazing and ungrazed “idle” fields, in conserving prairie songbirds. Northern mixed-grass prairie in southwest Manitoba, Canada is near the northern range limits for many endangered grassland birds, and thus is an important area for evaluating the contribution of twice-over grazing in the conservation of songbirds, including species at risk. In 2008 and 2009, we compared the relative abundances and diversity of grassland birds on 22 twice-over rotation, 15 season-long, and 8 ungrazed sites, using multiple 100-m fixed-radius point-count plots per site. Analyses were conducted using generalized linear mixed models. Although one obligate grassland bird, Savannah sparrows (Passerculus sandwichensis), had significantly higher relative abundances on twice-over than season-long sites in 2009, season-long pastures had higher species richness and diversity of obligate grassland birds in both years. Season-long grazing may actually benefit grassland bird communities by creating spatially heterogeneous but temporally stable areas of high and low livestock use within the pasture, thus increasing diversity of microhabitats. We found little evidence that twice-over grazing contributed to the conservation of grassland songbirds in subhumid northern mixed-grass prairies.     

Effects of blood contamination of cerebrospinal fluid on results of indirect fluorescent antibody tests for detection of antibodies against Sarcocystis neurona and Neospora hughesi.

The purpose of this study was to determine the effect of blood contamination of cerebrospinal fluid (CSF) on the results of indirect fluorescent antibody tests (IFATs) for Sarcocystis neurona and Neospora hughesi. The in vitro study used antibody-negative CSF collected from non-neurologic horses immediately after euthanasia and blood samples from 40 healthy horses that had a range of IFAT antibody titers against S. neurona and N. hughesi. Serial dilutions of whole blood were made in seronegative CSF to generate blood-contaminated CSF with red blood cell (RBC) concentrations ranging from 10 to 100,000 RBCs/microl. The blood-contaminated CSF samples were then tested for antibodies against both pathogens using IFAT. Blood contamination of CSF had no detectable effect on IFAT results for S. neurona or N. hughesi at any serologic titer when the RBC concentration in CSF was <10,000 RBCs/microl. At concentrations of 10,000-100,000 RBCs/microl of CSF, positive CSF results (IFAT titer >or=5) for S. neurona and N. hughesi were detected only when the corresponding serum titers were >or=160 and >or=80, respectively. The IFAT performed on CSF is reliable for testing horses for equine protozoal myeloencephalitis caused by S. neurona or N. hughesi, even when blood contamination causes the RBC concentration in CSF to be up to 10,000 RBCs/microl.     

Cardiac change as a function of attention to and awareness of continuous verbal text

A 17-minute passage taken from a patient's talking in a psychoanalytic interview was played to 40 subjects, including trained therapists, therapists in training, and inexperienced undergraduates. Subjects were alerted to the organizing theme (termination of the patient's treatment) and asked to attend to direct and indirect references to this theme. Tonic heart rate, averaged over 30-second periods, was lower when clues were present on the tape than during control periods when clues were not present. Profiles of phasic heart rate were drawn for 11-second periods that overlapped the end of each clue and control passage. Profiles associated with clues were significantly lower than profiles for control passages; profiles for recalled and recognized clues showed a wave form distinct from that of profiles associated with unrecognized clues.     

Identification of Theileria parva and Theileria sp. (buffalo) 18S rRNA gene sequence variants in the African Buffalo (Syncerus caffer) in southern Africa

Theileria parva is the causative agent of Corridor disease in cattle in South Africa. The African buffalo (Syncerus caffer) is the reservoir host, and, as these animals are important for eco-tourism in South Africa, it is compulsory to test and certify them disease free prior to translocation. A T. parva-specific real-time polymerase chain reaction (PCR) test based on the small subunit ribosomal RNA (18S rRNA) gene is one of the tests used for the diagnosis of the parasite in buffalo and cattle in South Africa. However, because of the high similarity between the 18S rRNA gene sequences of T. parva and Theileria sp. (buffalo), the latter is also amplified by the real-time PCR primers, although it is not detected by the T. parva-specific hybridization probes. Preliminary sequencing studies have revealed a small number of sequence differences within the 18S rRNA gene in both species but the extent of this sequence variation is unknown. The aim of the current study was to sequence the 18S rRNA genes of T. parva and Theileria sp. (buffalo), and to determine whether all identified genotypes can be correctly detected by the real-time PCR assay. The reverse line blot (RLB) hybridization assay was used to identify T. parva and Theileria sp. (buffalo) positive samples from buffalo blood samples originating from the Kruger National Park, Hluhluwe-iMfolozi Park, the Greater Limpopo Transfrontier Park, and a private game ranch in the Hoedspruit area. T. parva and Theileria sp. (buffalo) were identified in 42% and 28%, respectively, of 252 samples, mainly as mixed infections. The full-length 18S rRNA gene of selected samples was amplified, cloned and sequenced. From a total of 20 sequences obtained, 10 grouped with previously published T. parva sequences from GenBank while 10 sequences grouped with a previously published Theileria sp. (buffalo) sequence. All these formed a monophyletic group with known pathogenic Theileria species. Our phylogenetic analyses confirm the distinction between Theileria sp. (buffalo) and T. parva and indicate the existence of a single group of T. parva and two Theileria sp. (buffalo) 18S rRNA gene variants in the African buffalo. Despite the observed variation in the full-length parasite 18S rRNA gene sequences, the area in the V4 hypervariable region where the RLB and real-time PCR hybridization probes were developed was relatively conserved. The T. parva specific real-time PCR assay was able to successfully detect all T. parva variants and, although amplicons were obtained from Theileria sp. (buffalo) DNA, none of the Theileria sp. (buffalo) 18S rRNA sequence variants were detected by the T. parva-specific hybridization probes.     

Changing soil and surface conditions during rainfall: Single rainstorm/subsequent rainstorms

During rainstorms, physical properties of the soil surface change significantly. As a result of surface sealing, variations in infiltration rate, water content, water suction, bulk density and surface roughness can be observed and quantified. Dynamic processes taking place on the soil surface were investigated in laboratory and field experiments on a typical loess-derived soil in Germany. This study focused on the effects of continuous and subsequent rainfall treatments. Furthermore, all laboratory experiments were carried out in two different initial moisture regimes. In the laboratory experiments, a capillary rainfall simulator was used. Water suction was measured with microtensiometers 2 cm below the sealed surface in a 30 s time interval. The water content was determined with TDR probes in a variable time step, depending on the movement of the infiltration front. Compared to the continuous rainfall treatment, the decline of infiltration rate was much steeper in the subsequent rainfall events. After 2 h of continuous rainfall, a ‘drying effect' could be observed underneath the surface sealing at a depth of 2 cm. This was not the case in the intermittent treatment. Saturated conditions 10 cm below the surface sealing were reached in none of the treatments. The variation of bulk density within the first centimeter of the soil was determined via computed tomography and also with two simple methods using micro soil cores [Fohrer, N., 1995. Auswirkungen von Bodenfeuchte, Bodenart und Oberflächenbeschaffenheit auf Prozesse der Flächenerosion durch Wasser. PhD Thesis, Technical University Berlin, Bodenökologie und Bodengenese, No. 19, 183 pp.] and immersion as described by Roth [Roth, C.H., 1997. Bulk density of surface crusts: depth functions and relationships to texture. Catena 29 (3–4) 223–237.]. Under continuous rainfall conditions, the initially dry plots showed a higher compaction than the initially moist treatments. In the case of subsequent rainstorms, it was shown that the bulk density–depth function is not constant with time. The alteration of surface roughness was measured using a laser relief meter. The levelling effect of the intermittent rainfall regime proved to be much stronger in comparison to the continuous event.