570 research outputs found
Molecular evidence for resurrection of 'Plesiochorus elongatus' (Digenea : Gorgoderidae) : an urinary bladder parasite of sea turtles
Trematodes of the genus Plesiochorus were recovered from the urinary bladder of a stranded female adult loggerhead sea turtle, Caretta caretta, on a beach in Rio de Janeiro State, Brazil. Morphological analysis of the specimens revealed characteristics resembling the sub-species Plesiochorus cymbiformis elongatus rather than the recently synonymised Plesiochorus cymbiformis. Molecular phylogenetic analysis of the ITS2 region also showed that P. c. elongatus was distinct from P. cymbiformis and related taxa. Further analysis of the ITS2 revealed substantial differentiation between P. cymbiformis from the USA and Brazil and the newly sequenced P. c. elongatus from Brazil, while a previously unspecified Plesiochorus sp. from the USA closely related to the novel Brazilian P. c. elongatus was reconciled as a USA isolate of P. c. elongatus. Based on both the morphological and molecular data it is suggested that P. c. elongatus should be referred to as Plesiochorus elongatus and be considered as the second species in the genus
Sea lice (Copepoda: Caligidae) from South Africa, with descriptions of two new species of Caligus
Thirteen species of sea lice (family Caligidae) are reported from a range of elasmobranch and actinopterygian fishes caught off South Africa or obtained from public aquaria in South Africa. Two new species of Caligus Müller, 1785 are described: C. linearis n. sp. from Pomatomus saltatrix (Linnaeus) and C. tumulus n. sp. from Chrysoblephus cristiceps (Valenciennes). A supplementary description is provided for both sexes of Caligus tetrodontis Barnard, 1948 taken from Amblyrhynchotes honckenii (Bloch) and previous records of this parasite from South African fishes are critically reviewed. It is concluded that Caligus material from Arothron hispidus Linnaeus was previously misidentified as C. tetrodontis and is in urgent need of re-examination. Morphological and molecular observations on Caligus furcisetifer Redkar, Rangnekar & Murti, 1949 indicate that this copepod is phenotypically and genetically identical to Lepeophtheirus natalensis Kensley & Grindley, 1973, and the latter becomes a junior subjective synonym of C. furcisetifer. We include new geographical distribution records for Caligus longipedis Bassett-Smith, 1898, C. rufimaculatus Wilson, 1905 and Lepeophtheirus spinifer Kirtisinghe, 1937, extending into South African waters, as well as both new distribution and host records for Alebion gracilis Wilson, 1905, Caligus dakari van Beneden, 1892 and Lepeophtheirus acutus Heegaard, 1943. The molecular analysis confirmed the monophyly of the genus Caligus. The South African species of Caligus did not cluster together, but the two included South African species of Lepeophtheirus were recovered as sister taxa
DNA barcoding of the medically important freshwater snail 'Physa acuta' reveals multiple invasion events into Africa
The medically important freshwater snail Physa acuta is highly invasive and has been reported in several freshwater environments across Africa. To identify species and provide initial insights into the origins of P. acuta into African freshwater environments standard molecular barcoding analyses, using the mitochondrial cytochrome c oxidase subunit I gene (COI), was performed on P. acuta isolates from Angola, Burundi and South Africa. Phylogenetic analyses of isolates from Africa could not be distinguished from P. acuta populations from other countries. Comparisons of COI sequences between isolates of P. acuta showed there to be no geographically specific clusters and the African isolates were distributed across four distinct unrelated clades suggesting several independent invasion events. Haplotype analyses indicated that there were a high number of haplotypes with low variation between them, which led to significant differences in AMOVA analyses between countries. This was further evidence of multiple invasion events suggesting multiple novel haplotypes being continually and independently introduced to each country. This approach not only provides initial insight into the invasion of Africa by P. acuta but a molecular method to monitor and manage the use of an agent of biological control
How do care partners of people with rare dementia use language in online peer support groups? A quantitative text analysis study
We used quantitative text analysis to examine conversations in a series of online support groups attended by care partners of people living with rare dementias (PLWRD). We used transcripts of 14 sessions (>100,000 words) to explore patterns of communication in trained facilitators’ (n = 2) and participants’ (n = 11) speech and to investigate the impact of session agenda on language use. We investigated the features of their communication via Poisson regression and a clustering algorithm. We also compared their speech with a natural speech corpus. We found that differences to natural speech emerged, notably in emotional tone (d = −3.2, p < 0.001) and cognitive processes (d = 2.8, p < 0.001). We observed further differences between facilitators and participants and between sessions based on agenda. The clustering algorithm categorised participants’ contributions into three groups: sharing experience, self-reflection, and group processes. We discuss the findings in the context of Social Comparison Theory. We argue that dedicated online spaces have a positive impact on care partners in combatting isolation and stress via affiliation with peers. We then discuss the linguistic mechanisms by which social support was experienced in the group. The present paper has implications for any services seeking insight into how peer support is designed, delivered, and experienced by participants
Post-translational Protein Deimination in Cod (Gadus morhua L.) Ontogeny: Novel Roles in Tissue Remodelling and Mucosal Immune Defences?
Peptidylarginine deiminases (PADs) are calcium dependent enzymes with physiological and pathophysiological roles conserved throughout phylogeny. PADs promote post-translational deimination of protein arginine to citrulline, altering the structure and function of target proteins. Deiminated proteins were detected in the early developmental stages of cod from 11 days post fertilisation to 70 days post hatching. Deiminated proteins were present in mucosal surfaces and in liver, pancreas, spleen, gut, muscle, brain and eye during early cod larval development. Deiminated protein targets identified in skin mucosa included nuclear histones; cytoskeletal proteins such as tubulin and beta-actin; metabolic and immune related proteins such as galectin, mannan-binding lectin, toll-like receptor, kininogen, Beta2-microglobulin, aldehyde dehydrogenase, bloodthirsty and preproapolipoprotein A-I. Deiminated histone H3, a marker for anti-pathogenic neutrophil extracellular traps, was particularly elevated in mucosal tissues in immunostimulated cod larvae. PAD-mediated protein deimination may facilitate protein moonlighting, allowing the same protein to exhibit a range of biological functions, in tissue remodelling and mucosal immune defences in teleost ontogeny
Pentraxins CRP-I and CRP-II are post-translationally deiminated and differ in tissue specificity in cod (Gadus morhua L.) ontogeny
Pentraxins are fluid phase pattern recognition molecules that form an important part of the innate immune defence and are conserved between fish and human. In Atlantic cod (Gadus morhua L.), two pentraxin-like proteins have been described, CRP-I and CRP-II. Here we show for the first time that these two CRP forms are post-translationally deiminated (an irreversible conversion of arginine to citrulline) and differ with respect to tissue specific localisation in cod ontogeny from 3 to 84 days post hatching. While both forms are expressed in liver, albeit at temporally differing levels, CRP-I shows a strong association with nervous tissue while CRP-II is strongly associated to mucosal tissues of gut and skin. This indicates differing roles for the two pentraxin types in immune responses and tissue remodelling, also elucidating novel roles for CRP-I in the nervous system. The presence of deimination positive bands for cod CRPs varied somewhat between mucus and serum, possibly facilitating CRP protein moonlighting, allowing the same protein to exhibit a range of biological functions and thus meeting different functional requirements in different tissues. The presented findings may further current understanding of the diverse roles of pentraxins in teleost immune defences and tissue remodelling, as well as in various human pathologies, including autoimmune diseases, amyloidosis and cancer
Characterisation of tabanid flies (Diptera: Tabanidae) in South Africa and Zambia and detection of protozoan parasites they are harbouring
Tabanids are haematophagous flies feeding on livestock and wildlife. In the absence of information on the relationship of tabanid flies and protozoan parasites in South Africa and Zambia, the current study was aimed at characterizing tabanid flies collected in these two countries as well as detecting protozoan parasites they are harbouring. A total of 527 tabanid flies were collected whereby 70.2% were from South Africa and 29.8% were from Zambia. Morphological analysis revealed a total of 5 different genera collected from the sampled areas namely: Ancala, Atylotus, Haematopota, Philoliche and Tabanus. DNA extracted from South African Tabanus par and T. taeniola tested positive for the presence of Trypanosoma congolense and T. theileri whilst one member from T. par was positive for T. brucei-like parasite. DNA extracted from Zambian tabanid flies tested positive for the presence of Besnoitia besnoiti at 1.27% (2/157), Babesia bigemina 5.73% (9/157), Theileria parva-like species 30.11% (30/157) and 9.82% (14/157) for Trypanosoma evansi-like species. This study is the first to report on Babesia and Theileria parasites in tabanid flies. Further investigations are required to determine the role of tabanids in transmission of the detected protozoan parasites in livestock and wildlife in South Africa and Zambia
The role of manufacturing and market managers in strategy development:lessons from three companies
According to researchers and managers, there is a lack of agreement between marketing and manufacturing managers on critical strategic issues. However, most of the literature on the subject is anecdotal and little formal empirical research has been done. Three companies are investigated to study the extent of agreement/disagreement between manufacturing and marketing managers on strategy content and process. A novel method permits the study of agreement between the two different functional managers on the process of developing strategy. The findings consistently show that manufacturing managers operate under a wider range of strategic priorities than marketing managers, and that manufacturing managers participate less than marketing managers in the strategy development process. Further, both marketing and manufacturing managers show higher involvement in the strategy development process in the latter stages of the Hayes and Wheelwright four-stage model of manufacturing’s strategic role
Streamer Wave Events Observed in Solar Cycle 23
In this paper we conduct a data survey searching for well-defined streamer
wave events observed by the Large Angle and Spectrometric Coronagraph (LASCO)
on-board the Solar and Heliospheric Observatory (SOHO) throughout Solar Cycle
23. As a result, 8 candidate events are found and presented here. We compare
different events and find that in most of them the driving CMEs ejecta are
characterized by a high speed and a wide angular span, and the CME-streamer
interactions occur generally along the flank of the streamer structure at an
altitude no higher than the bottom of the field of view of LASCO C2. In
addition, all front-side CMEs have accompanying flares. These common
observational features shed light on the excitation conditions of streamer wave
events.
We also conduct a further analysis on one specific streamer wave event on 5
June 2003. The heliocentric distances of 4 wave troughs/crests at various
exposure times are determined; they are then used to deduce the wave properties
like period, wavelength, and phase speeds. It is found that both the period and
wavelength increase gradually with the wave propagation along the streamer
plasma sheet, and the phase speed of the preceding wave is generally faster
than that of the trailing ones. The associated coronal seismological study
yields the radial profiles of the Alfv\'en speed and magnetic field strength in
the region surrounding the streamer plasma sheet. Both quantities show a
general declining trend with time. This is interpreted as an observational
manifestation of the recovering process of the CME-disturbed corona. It is also
found that the Alfv\'enic critical point is at about 10 R where the
flow speed, which equals the Alfv\'en speed, is 200 km s
New experimental data for the decays and from SND detector
The processes and have been
studied with SND detector at VEPP-2M collider in the vicinity of
resonance. The branching ratios and were obtained.Comment: 5 pages, 4 figures, talk given at 8th International Conference on
Hadron Spectroscopy (HADRON 99), Beijing, China, 24-28 Aug 199
- …