A Novel Flow Cytometric Hemozoin Detection Assay for Real-Time Sensitivity Testing of Plasmodium falciparum

Resistance of Plasmodium falciparum to almost all antimalarial drugs, including the first-line treatment with artemisinins, has been described, representing an obvious threat to malaria control. In vitro antimalarial sensitivity testing is crucial to detect and monitor drug resistance. Current assays have been successfully used to detect drug effects on parasites. However, they have some limitations, such as the use of radioactive or expensive reagents or long incubation times. Here we describe a novel assay to detect antimalarial drug effects, based on flow cytometric detection of hemozoin (Hz), which is rapid and does not require any additional reagents. Hz is an optimal parasite maturation indicator since its amount increases as the parasite matures. Due to its physical property of birefringence, Hz depolarizes light, hence it can be detected using optical methods such as flow cytometry. A common flow cytometer was adapted to detect light depolarization caused by Hz. Synchronized in vitro cultures of P. falciparum were incubated for 48 hours with several antimalarial drugs. Analysis of depolarizing events, corresponding to parasitized red blood cells containing Hz, allowed the detection of parasite maturation. Moreover, chloroquine resistance and the inhibitory effect of all antimalarial drugs tested, except for pyrimethamine, could be determined as early as 18 to 24 hours of incubation. At 24 hours incubation, 50% inhibitory concentrations (IC50) were comparable to previously reported values. These results indicate that the reagent-free, real-time Hz detection assay could become a novel assay for the detection of drug effects on Plasmodium falciparum.     

E‐Clic – easy climate data converter

There are an increasing number of studies that are now focussing on the influence of climate change on species’ distributions. However, access to predictive climatic datasets for future scenarios is difficult due to their specific formats and/or the need to be geographically downscaled. The TYN dataset is freely available to users and provides a synthetic format with several climatic models and IPCC future climate scenarios. Moreover, the CRU historical dataset (1901–2000) is also available which allows users to create baseline models for current climatic variables. E‐clic is a free, user‐friendly software package that offers three different ways to convert these two datasets into a spatially explicit raster format which is compatible with the most common geographic information systems and usable on different platforms.     

Colour and size of flowers in relation to pollination of Erica species

Summary Data on flower colour polymorphism were recorded for 341 of some 426 species of Erica occurring in the south-western Cape, South Africa. Thirty-eight per cent of these Erica species are colour polymorphic, the incidence of polymorphism being greater than expected for ornithophilous species and lower than expected for anemophilous species. Both altitude and season of flowering are correlated with the incidence of colour polymorphism, with most polymorphs occurring in species which have relatively large altitudinal ranges and extended flowering periods. The mean corolla length for each of pink, purple and white flowers is significantly shorter than that for each of red, orange, yellow and green flowers, suggesting that these two sets of colours correspond with entomophily and ornithophily, respectively. There are no Erica species with blue flowers. We suggest that the patterns of colour polymorphism, because of their relationships with the behaviour of pollinators, may reflect patterns of speciation in the genus.     

Evolutionary history of the European free-tailed bat,a tropical affinity species spanning across the Mediterranean Basin

The Mediterranean Basin is a global biodiversity hotspot, hosting a number of native species belonging to families that are found almost exclusively in tropical climates. Yet, whether or not these taxa were able to survive in the Mediterranean region during the Quaternary climatic oscillations remains unknown. Focusing on the European free-tailed bat (Tadarida teniotis), we aimed to (a) identify potential ancient populations and glacial refugia; (b) determine the post-glacial colonization routes across the Mediterranean; and (c) evaluate current population structure and demography. Mitochondrial and nuclear markers were used to understand T. teniotis evolutionary and demographic history. We show that T. teniotis is likely restricted to the Western Palearctic, with mitochondrial phylogeny suggesting a split between an Anatolian/Middle East clade and a European clade. Nuclear data pointed to three genetic populations, one of which is an isolated and highly differentiated group in the Canary Islands, another distributed across Iberia, Morocco, and France, and a third stretching from Italy to the east, with admixture following a pattern of isolation by distance. Evolutionary and demographic reconstruction supports a pre-Last Glacial Maximum (LGM) colonization of Italy and the Anatolian/Middle East, while the remaining populations were colonized from Italy after the Younger Dryas. We also found support for demographic expansion following the Iberian colonization. The results show that during the LGM T. teniotis persisted in Mediterranean refugia and has subsequently expanded to its current circum-Mediterranean range. Our findings raise questions regarding the physiological and ecological traits that enabled species with tropical affinities to survive in colder climates.     

Heat waves trigger swift changes in the diet and life-history of a freshwater snail

Hydrobiologia - Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these...     

XX/XO, a rare sex chromosome system in Potamotrygon freshwater stingray from the Amazon Basin, Brazil

Potamotrygonidae is a representative family of South American freshwater elasmobranchs. Cytogenetic studies were performed in a Potamotrygon species from the middle Negro River, Amazonas, Brazil, here named as Potamotrygon sp. C. Mitotic and meiotic chromosomes were analyzed using conventional staining techniques, C-banding, and detection of the nucleolus organizing regions (NOR) with Silver nitrate (Ag-NOR). The diploid number was distinct between sexes, with males having 2n = 67 chromosomes, karyotype formula 19m + 8sm + 10st + 30a, and fundamental number (FN) = 104, and females having 2n = 68 chromosomes, karyotype formula 20m + 8sm + 10st + 30a, and FN = 106. A large chromosome, corresponding to pair number two in the female karyotype, was missing in the male complement. Male meiotic cells had 33 bivalents plus a large univalent chromosome in metaphase I, and n = 33 and n = 34 chromosomes in metaphase II. These characteristics are consistent with a sex chromosome system of the XX/XO type. Several Ag-NOR sites were identified in both male and female karyotypes. Positive C-banding was located only in the centromeric regions of the chromosomes. This sex chromosome system, which rarely occurs in fish, is now being described for the first time among the freshwater rays of the Amazon basin.     

Reserve selection in the Succulent Karoo,South Africa: coping with high compositional turnover

The Succulent Karoo biome is home to the world's richest succulent flora. It has approximately 1954 endemic plant species, and is the only semi-arid region to qualify as a hotspot of global significance. Despite its importance, only 2% of the biome is currently protected. Based on its flora, the biome can be divided into 12 bioregions, reflecting its high compositional turnover in relation to environmental and geographical gradients. Only three of these bioregions (the Gariep Centre, the Namaqualand Rocky Hills and the Tanqua Karoo) contain National Parks, and three contain large (over 10000 ha) provincial reserves (the Gariep Centre, the Namaqualand Rocky Hills and the Little Karoo). The current reserve system does little to conserve biodiversity, with only one reserve significantly conserving Red Data Book (RDB) plant diversity. Using a RDB plant species database of 3874 records at a quarter degree scale (QDS = 15×15), we used hotspot analyses and iterative reserve selection algorithms to identify possible locations for future reserves. The hotspot analysis and iterative analyses yielded similar results for the top 11 QDS, mainly due to very high local endemism. Also because of the local endemism and the high species turnover within the biome, the real-world iterative algorithm (starting with the seven already reserved QDS) selected a very large total number of QDS (59% of the total in the biome) to conserve all RDB species. As a possible alternative to conservation planning based on QDS, we also assessed priorities at the scale of bioregions, but showed that representation at this geographic level misses important areas defined at a finer scale. We suggest that if the objective is to maximise the retention of RDB species in the landscape (to pre-empt extinction by scheduling the allocation of limited conservation resources), at least the top 5% of QDS (n=11) selected by the iterative procedure, and identified as the core conservation sequence by analysis of endemicity and threat, should be given priority for reservation. Less extensive and, in some cases, less formal conservation action can be applied to QDS later in the sequence, based on species-specific monitoring and action plans. Of the 11 core areas, four fall in a node centred on the Vanrhynsdorp Centre, two fall in a node centred on the Kamiesberg, and the remaining five are isolated. With existing reserves, the core areas capture 50% of the RDB flora in 8% of the biome.     

A comparative cytogenetic study of five piranha species (Serrasalmus,Serrasalminae) from the Amazon basin

Cytogenetic studies were conducted on five piranha species belonging to the genus Serrasalmus, subfamily Serrasalminae (Serrasalmus altispinis, S. compressus, S. elongatus, S. manuelli, and S. spilopleura). All the species were collected in the Amazon basin: confluence of Negro and Solimõoes Rivers (CatalãoLake), Solimões River (Marchantaria Island – Camaleão Lake), Uatumã River (Hydroelectric Power Station of Balbina), and Pitinga River (Hydroelectric Power Station of Pitinga). All the five species possess 2n = 60 chromosomes with 5–12 subtelo- and acrocentric chromosomes bearing nucleolar organizer regions. A proximal C-band positive heterochromatin block was evident on the long arms of a medium-sized metacentric chromosome pair in all the analized species, thus making it a cytogenetic marker for the genus. It is hypothesized that 2n = 60 chromosomes represents a derived feature in terms of the chromosomal evolution of piranhas because the basal lineages possess 2n = 62. Both Robertsonian centric fusion and non-Robertsonian rearragements such as pericentric inversions seem implicated in the chromosomal evolution of this group.