Leishmania species: Detection and identification by nested PCR assay from skin samples of rodent reservoirs

Many rodent species act as reservoir hosts of zoonotic cutaneous leishmaniasis in endemic areas. In the present study a simple and reliable assay based on nested PCR was developed for the detection and identification of Leishmania parasites from rodent skin samples. We designed Leishmania-specific primers that successfully amplified ITS regions of Leishmania major, Leishmania gerbilli and Leishmania turanica using nested PCR. Out of 95 field collected Rhombomys opimus, 21 were positive by microscopic examination and 48 by nested PCR. The percentage of gerbils infected with L. major, L. gerbilli and L. turanica was 3.2%, 1.1% and 27.4%, respectively. In 15.8% of the rodents, we found mixed natural infections by L. major and L. turanica, 1.1% by L. major and L. gerbilli, and 2.1% by the three species. We concluded that this method is simple and reliable for detecting and identifying Leishmania species circulating in rodent populations.     

A molecular view on pluripotent stem cells

Pluripotent stem cells are undifferentiated cells that are capable of differentiating to all three embryonic germ layers and their differentiated derivatives. They are transiently found during embryogenesis, in preimplantation embryos and fetal gonads, or as established cell lines. These unique cell types are distinguished by their wide developmental potential and by their ability to be propagated in culture indefinitely, without loosing their undifferentiated phenotype. This short review intends to give a general overview on the pluripotent nature of embryo-derived stem cells with a focus on human embryonic stem cells.     

Large P body-like RNPs form in C. elegans oocytes in response to arrested ovulation, heat shock, osmotic stress, and anoxia and are regulated by the major sperm protein pathway

As Caenorhabditis elegans hermaphrodites age, sperm become depleted, ovulation arrests, and oocytes accumulate in the gonad arm. Large ribonucleoprotein (RNP) foci form in these arrested oocytes that contain RNA-binding proteins and translationally masked maternal mRNAs. Within 65 min of mating, the RNP foci dissociate and fertilization proceeds. The majority of arrested oocytes with foci result in viable embryos upon fertilization, suggesting that foci are not deleterious to oocyte function. We have determined that foci formation is not strictly a function of aging, and the somatic, ceh-18, branch of the major sperm protein pathway regulates the formation and dissociation of oocyte foci. Our hypothesis for the function of oocyte RNP foci is similar to the RNA-related functions of processing bodies (P bodies) and stress granules; here, we show three orthologs of P body proteins, DCP-2, CAR-1 and CGH-1, and two markers of stress granules, poly (A) binding protein (PABP) and TIA-1, appear to be present in the oocyte RNP foci. Our results are the first in vivo demonstration linking components of P bodies and stress granules in the germ line of a metazoan. Furthermore, our data demonstrate that formation of oocyte RNP foci is inducible in non-arrested oocytes by heat shock, osmotic stress, or anoxia, similar to the induction of stress granules in mammalian cells and P bodies in yeast. These data suggest commonalities between oocytes undergoing delayed fertilization and cells that are stressed environmentally, as to how they modulate mRNAs and regulate translation.     

Bcl-2 proteins link programmed cell death with growth and morphogenetic adaptations in the fungal plant pathogen Colletotrichum gloeosporioides

Proteins belonging to the Bcl-2 family regulate apoptosis in mammals by controlling mitochondria efflux of cytochrome c and other apoptosis-related proteins. Homologues of human Bcl-2 proteins are found in different metazoan organisms where they play a similar role, while they seem to be absent in plants and fungi. Nonetheless, Bcl-2 protein members can induce or prevent yeast cell death, suggesting that enough functional conservation exists between apoptotic machineries of mammals and fungi. Here we show that induction or prevention of apoptosis by Bcl-2 proteins in the fungal plant pathogen Colletotrichum gloeosporioides is tightly linked with growth and morphogenetic adaptation that occur throughout the entire fungal life cycle. Isolates expressing the pro-apoptotic Bax protein underwent cell death with apoptotic characteristics, and showed alterations in conidial germination that are associated with pathogenic and non-pathogenic life styles. Isolates expressing the anti-apoptotic Bcl-2 protein had prolonged longevity, were protected from Bax-induced cell death, and exhibited enhanced stress resistance. These isolates also had enhanced mycelium and conidia production, and were hyper virulent to host plants. Our findings show that apoptotic-associated machinery regulates morphogenetic switches, which are critical for proper responses and adaptation fungi to different environments.     

Social transmission of novel foraging behavior in bats: frog calls and their referents

The fringe-lipped bat, Trachops cirrhosus, uses prey-emitted acoustic cues (frog calls) to assess prey palatability . Previous experiments show that wild T. cirrhosus brought into the laboratory are flexible in their ability to reverse the associations they form between prey cues and prey quality . Here we asked how this flexibility can be achieved in nature. We quantified the rate at which bats learned to associate the calls of a poisonous toad species with palatable prey by placing bats in three groups: (a) social learning, in which a bat inexperienced with the novel association was allowed to observe an experienced bat; (b) social facilitation, in which two inexperienced bats were presented with the experimental task together; and (c) trial-and-error, in which a single inexperienced bat was presented with the experimental task alone. In the social-learning group, bats rapidly acquired the novel association in an average of 5.3 trials. In the social-facilitation and trial-and-error groups, most bats did not approach the call of the poisonous species after 100 trials. Thus, once acquired, novel associations between prey cue and prey quality could spread rapidly through the bat population by cultural transmission. This is the first case to document predator social learning of an acoustic prey cue.     

Genomewide scan in families with schizophrenia from the founder population of Afrikaners reveals evidence for linkage and uniparental disomy on chromosome 1

We report on our initial genetic linkage studies of schizophrenia in the genetically isolated population of the Afrikaners from South Africa. A 10-cM genomewide scan was performed on 143 small families, 34 of which were informative for linkage. Using both nonparametric and parametric linkage analyses, we obtained evidence for a small number of disease loci on chromosomes 1, 9, and 13. These results suggest that few genes of substantial effect exist for schizophrenia in the Afrikaner population, consistent with our previous genealogical tracing studies. The locus on chromosome 1 reached genomewide significance levels (nonparametric LOD score of 3.30 at marker D1S1612, corresponding to an empirical P value of.012) and represents a novel susceptibility locus for schizophrenia. In addition to providing evidence for linkage for chromosome 1, we also identified a proband with a uniparental disomy (UPD) of the entire chromosome 1. This is the first time a UPD has been described in a patient with schizophrenia, lending further support to involvement of chromosome 1 in schizophrenia susceptibility in the Afrikaners.     

Intimate Partner Femicide in South Africa in 1999 and 2009

Background

Death is the most extreme consequence of intimate partner violence. Female homicide studies with data on the perpetrator–victim relationship can provide insights. We compare the results of two South African national studies of female homicide with similar sampling done 10 y apart.

Methods and Findings

We conducted a retrospective national survey using a weighted cluster design of a proportionate random sample of 38 mortuaries to identify homicides committed in 2009. We abstracted victim data from mortuary and autopsy reports, and perpetrator data from police interviews. We compared homicides of women 14 y and older in 2009 with previously published data collected with the same methodology for homicides committed in 1999.The study found that the rate of female homicide per 100,000 female population in 2009 was 12.9 (95% confidence interval [CI]: 9.3, 16.5), compared to 24.7 (95% CI: 17.7, 31.6) in 1999. The incidence rate ratio of 0.54 (95% CI: 0.20, 0.84) reflects a significantly lower rate in 2009. The rate of intimate partner femicide was 5.6/100,000 in 2009 versus 8.8/100,000 in 1999, with an incidence rate ratio of 0.63 (95% CI: 0.24, 1.02), indicating no difference between rates. Logistic regression analysis of homicide characteristics showed that the odds ratio of suspected rape among non-intimate femicides in 2009 compared to 1999 was 2.61 (95% CI: 1.23, 4.08) and among intimate partner femicides it was 0.84 (95% CI: 0.50, 1.42). The OR of homicide by gunshot was 0.54 (95% CI: 0.30, 0.99) in 2009 versus 1999. There was a significant drop in convictions of perpetrators of non-intimate femicide in 2009 versus 1999 (OR = 0.32 [95% CI: 0.19, 0.53]). Limitations of the study include the relatively small sample size and having only two time points.

Conclusions

Female homicide in South Africa was lower in 2009 than 1999, but intimate partner femicide and suspected rape homicide rates were not statistically different. The cause of the difference is unknown. The findings suggest that South Africa needs greater efforts nationally to implement evidence-based violence prevention. Please see later in the article for the Editors'' Summary     

UNICELLULAR CYANOBIONTS IN OPEN OCEAN DINOFLAGELLATES,RADIOLARIANS, AND TINTINNIDS: ULTRASTRUCTURAL CHARACTERIZATION AND IMMUNO‐LOCALIZATION OF PHYCOERYTHRIN AND NITROGENASE1

Cyanobacterial symbionts (cyanobionts) have been identified forming associations with various open ocean eukaryotic host genera, including two dinophysoid genera, Histioneis sp. and Ornithocercus sp., two radiolarians, Spongastaurus and Dictyocoryne truncatum, sp., and a tintinnid, Codonella sp. The TEM analysis revealed that single individual hosts were closely associated with one to two different cyanobacterial morphotypes (cyanobionts) and two hosts had in addition to cyanobionts, one to two bacterial cell types. Eleven significantly (P<0.01) different cell types were identified as cyanobionts, with cell diameters ranging 0.5±0.38–3.7±0.66 μm. Using immunogold‐labeling techniques coupled to the TEM, four of the five cell types contained phycoerythrin (PE) at high levels (>71±28 gold particles·μm^?2). Immunolabeling‐TEM using nitrogenase antisera demonstrated a significant (P<0.01) nitrogenase content in cell type four cyanobionts of Histioneis sp. host 1 (39±34 gold particles·μm^?2). The cyanobionts of the radiolarians were of a cell diameter (0.5–0.8 μm) and showed ultrastructural characters (peripheral thylakoids) reminiscent of Prochlorococcus sp. Also, an open ocean tintinnid, Codonella sp., was shown to contain cyanobacteria as symbionts for the first time. In all cyanobionts, glycogen storage was obvious, no cellular degradation was visible, cells were observed in the process of cellular division, and antisera localization was apparent. These observations suggest that the relationship between host eukaryote and cyanobacteria is an active one, and likely symbiotic.     

Tracking of progressing human DNA polymerase δ holoenzymes reveals distributions of DNA lesion bypass activities

During DNA replication, DNA lesions in lagging strand templates are initially encountered by DNA polymerase δ (pol δ) holoenzymes comprised of pol δ and the PCNA processivity sliding clamp. These encounters are thought to stall replication of an afflicted template before the lesion, activating DNA damage tolerance (DDT) pathways that replicate the lesion and adjacent DNA sequence, allowing pol δ to resume. However, qualitative studies observed that human pol δ can replicate various DNA lesions, albeit with unknown proficiencies, which raises issues regarding the role of DDT in replicating DNA lesions. To address these issues, we re-constituted human lagging strand replication to quantitatively characterize initial encounters of pol δ holoenzymes with DNA lesions. The results indicate pol δ holoenzymes support dNTP incorporation opposite and beyond multiple lesions and the extent of these activities depends on the lesion and pol δ proofreading. Furthermore, after encountering a given DNA lesion, subsequent dissociation of pol δ is distributed around the lesion and a portion does not dissociate. The distributions of these events are dependent on the lesion and pol δ proofreading. Collectively, these results reveal complexity and heterogeneity in the replication of lagging strand DNA lesions, significantly advancing our understanding of human DDT.