Cosmocercid nematodes have been documented with much criticism due to the numerous inaccurate descriptions, redescriptions and synonymisation of found species. This is due to indistinguishable ...characters of females and the lack of male specimens found. Consequently, the species
C. ornata
is the most commonly found species worldwide and the only species of the genus reported in South Africa. In the present study, we found
Cosmocerca
in three different amphibian species, namely
Cacosternum boettgeri
,
Kassina senegalensis
and
Phrynomantis bifasciatus
. Based on differences in the shape of the gubernaculum and number of papillae, the found nematodes were assigned to three new species namely
C.
daly
n. sp.,
C. monicae
n. sp. and
C. makhadoensis
n. sp. Descriptions of species are followed by pairwise and phylogenetic analysis of partial ITS-28S sequences. All three species were found only in their host types from distant localities. Therefore, we hypothesise that host specificity of
Cosmocerca
from South African amphibians might be rather high and that the presence of
C. ornata
throughout South Africa is rather doubtful.
Soil organic matter (SOM) is tightly linked to soil quality, but cultivation generally causes a decline in SOM, reducing soil quality and releasing carbon dioxide into the atmosphere. ...Internationally, countries are expected to reduce their greenhouse gas (GHG) emissions, and compile and update GHG inventories. Many developing countries, such as those in southern Africa, do not have reliable information regarding SOM levels in cultivated soils, changes over time and best management practices to maintain or even restore SOM. A review was conducted to collate published research on SOM or its indicator elements, carbon (C) and nitrogen (N) in cultivated fields in southern Africa. A total of 84 publications were assessed, and information such as date, location, SOM/soil organic carbon (SOC) and clay content and key findings were recorded. Most of the publications (90 %) were published post-1990. The spatial distribution of these studies is very non-uniform. A decline of 25–53 % in SOC due to cultivation was evident for cultivated fields in different precipitation zones in southern Africa, with SOC ranging from 0.7 to 2.5 %. These values correlate relatively well with existing SOC maps. A strong correlation between SOC and clay content in natural soil is weakened following cultivation. Carbon sequestration and GHG emission dynamics under various management systems and for different climatic regions, as well as how field crop production can play a role in mitigating climate change, are poorly understood. Intensified monitoring by multi-institutional collaboration is recommended to address this issue.
An HPLC method was developed and validated to quantify and identify several statins (atorvastatin, fluvastatin, pitavastatin and pravastatin) that were used during transdermal drug delivery. The ...method proved to be most effective with a Restek Ultra C
, 250 x 4.6 mm, 5 μm column, a flow rate of 1.0 ml/min, UV detection at 240 nm and injection volume of 10 μl. The mobile phase used was acetonitrile/Milli-Q
water with 0.1% orthophosphoric acid starting with 30% acetonitrile, which increased linearly to 70% (after 4 min) for up to 10 min and then re-equilibrated to start conditions. This HPLC method indicated linearity (correlation coefficient (R²) of 1) within the concentration range of 0.05-200.00 μg/ml and had an average recovery of 98-103%. Limit of detection (LOD) and limit of quantification (LOQ) showed that statins could still be identified at concentrations of 0.004-0.006 μg/ml with the exception of atorvastatin (quantifiable at 0.013-0.035 μg/ml). Specificity performed during method validation, confirmed that the method was suitable for accurate detection and quantification of the statins when included in the transdermal formulations with other excipients.
This communication details the maternal care of Hemisus marmoratus and Hemisus guttatus. A Hemisus mother stays with the eggs, protecting them during their time in the nest chamber, and ensures their ...ultimate arrival in a body of water, at varying stages of development, via a variety of different techniques, ranging from nest placement and slide construction to tadpole transportation. We confirm that a sticky glue-like substance is used during inguinal amplexus of H. guttatus, with only the hands of the male being glued to the female. Field observations indicate that H. marmoratus females carry their offspring to the water, gluing her hind legs together to increase the surface area for the tadpoles to adhere to during the journey.
The triazine herbicide atrazine has been suggested to be a potential disruptor of normal sexual development in male frogs. The goals of this study were to collect native ranid frogs from sites in ...agricultural and non-agricultural areas and determine whether hypothesised atrazine effects on the gonads could be observed at the gross morphological and histological levels. Juvenile and adult green frogs (
Rana clamitans), bullfrogs (
R. catesbeiana) and leopard frogs (
R. pipiens) were collected in the summers of 2002 and 2003. Atrazine concentrations were below the limit of quantification at non-agricultural sites, and concentrations did not exceed 2
μg/L at most agricultural sites. One concentration greater than 200
μg atrazine/L was measured once at one site in 2002. Hermaphroditic individuals with both male and female gonad tissue in either one or both gonads, were found at a low incidence at both non-agricultural and agricultural sites, and in both adults and juveniles. Testicular oocytes (TO) were found in male frogs at most of the sites, with the greatest incidence occurring in juvenile leopard frogs. TO incidence was not significantly different between agricultural and non-agricultural sites with the exception of juveniles collected in 2003. Atrazine concentrations were not significantly correlated with the incidence of hermaphroditism, but maximum atrazine concentrations were correlated with TO incidence in juvenile frogs in 2003. However, given the lack of a consistent relationship between atrazine concentrations and TO incidence, it is more likely the TOs observed in this study result from natural processes in development rather than atrazine exposure.
Origin of the amphibian chytrid fungus Weldon, Ché; du Preez, Louis H; Hyatt, Alex D ...
Emerging infectious diseases,
12/2004, Letnik:
10, Številka:
12
Journal Article
Recenzirano
Odprti dostop
The sudden appearance of chytridiomycosis, the cause of amphibian deaths and population declines in several continents, suggests that its etiologic agent, the amphibian chytrid Batrachochytrium ...dendrobatidis, was introduced into the affected regions. However, the origin of this virulent pathogen is unknown. A survey was conducted of 697 archived specimens of 3 species of Xenopus collected from 1879 to 1999 in southern Africa in which the histologic features of the interdigital webbing were analyzed. The earliest case of chytridiomycosis found was in a Xenopus laevis frog in 1938, and overall prevalence was 2.7%. The prevalence showed no significant differences between species, regions, season, or time period. Chytridiomycosis was a stable endemic infection in southern Africa for 23 years before any positive specimen was found outside Africa. We propose that Africa is the origin of the amphibian chytrid and that the international trade in X. laevis that began in the mid-1930s was the means of dissemination.
The objective of this study was to characterize concentrations of atrazine, terbuthylazine, and other pesticides in amphibian habitats in surface waters of a corn-production area of the western ...Highveld region (North-West Province) of South Africa. The study was conducted from November 2001 to June 2002, coinciding with the corn-production season. Pesticide residues were measured at regular intervals in surface water from eight ponds, three in a non-corn-growing area (NCGA) and five within the corn-growing area (CGA). Measured atrazine concentrations differed significantly among sites and between samples. In the five CGA sites, the maximum atrazine concentrations measured during the study ranged from 1.2 to 9.3
μg/L. Although no atrazine was recorded as being applied in the catchment of the three NCGA sites, maximum concentrations from 0.39 to 0.84
μg/L were measured during the study, possibly as a result of atmospheric transport. Maximum measured concentrations of terbuthylazine ranged from 1.22 to 2.1
μg/L in the NCGA sites and from 1.04 to 4.1
μg/L in the CGA sites. The source of terbuthylazine in the NCGA sites may have been in use other than in corn. The triazine degradation products, deisopropylatrazine (DIA) and deethylatrazine (DEA) and diaminochlorotriazine (DACT) were also found in water from both the CGA and NCGA sites. Concentrations of DIA were ≥1
μg/L throughout the season, while DEA concentrations were mostly <0.5
μg/L before planting but increased after planting and application of herbicides to concentrations >2
μg/L in some locations. Concentrations of DACT were highly variable (LOD to 8
μg/L) both before and after planting and application, suggesting that they resulted from historical use of triazines in the area. Other herbicides such as simazine and acetochlor were only detected infrequently and pesticides such as S-metolachlor, cypermethrin, monocrotophos, and terbuphos, known to be used in the CGA, were not detected in any of the samples. Because of dilution by higher than normal rainfall in the study period, these concentrations may not be predictive of those in years of normal rainfall.
Concentrations of atrazine in an agricultural region vary greatly and are influenced by rainfall amounts.
One of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. In this context, the role of parasites is not negligible as it may ...enhance the success of invaders. The red-eared slider, Trachemys scripta elegans, has been globally considered among the worst invasive species. Since its introduction through the pet trade, T. s. elegans is now widespread and represents a threat for indigenous species. Because T. s. elegans coexists with Emys orbicularis and Mauremys leprosa in Europe, it has been suggested it may compete with the native turtle species and transmit pathogens. We examined parasite transfer from American captive to the two native species that co-exist in artificial pools of a Turtle Farm in France. As model parasite species we used platyhelminth worms of the family Polystomatidae (Monogenea) because polystomes have been described from American turtles in their native range. Phylogenetic relationships among polystomes parasitizing chelonian host species that are geographically widespread show patterns of diversification more complex than expected. Using DNA barcoding to identify species from adult and/or polystome eggs, several cases of host switching from exotic to indigenous individuals were illustrated, corroborating that parasite transmission is important when considering the pet trade and in reintroduction programmes to reinforce wild populations of indigenous species.
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