TY  - JOUR
A1  - Kern, Selina
A1  - Agarwal, Shruti
A1  - Huber, Kilian
A1  - Gehring, Andre P.
A1  - Strödke, Benjamin
A1  - Wirth, Christine C.
A1  - Brügl, Thomas
A1  - Abodo, Liane Onambele
A1  - Dandekar, Thomas
A1  - Doerig, Christian
A1  - Fischer, Rainer
A1  - Tobin, Andrew B.
A1  - Alam, Mahmood M.
A1  - Bracher, Franz
A1  - Pradel, Gabriele
T1  - Inhibition of the SR Protein-Phosphorylating CLK Kinases of Plasmodium falciparum Impairs Blood Stage Replication and Malaria Transmission
JF  - PLOS ONE
N2  - Cyclin-dependent kinase-like kinases (CLKs) are dual specificity protein kinases that phosphorylate Serine/Arginine-rich (SR) proteins involved in pre-mRNA processing. Four CLKs, termed PfCLK-1-4, can be identified in the human malaria parasite Plasmodium falciparum, which show homology with the yeast SR protein kinase Sky1p. The four PfCLKs are present in the nucleus and cytoplasm of the asexual blood stages and of gametocytes, sexual precursor cells crucial for malaria parasite transmission from humans to mosquitoes. We identified three plasmodial SR proteins, PfSRSF12, PfSFRS4 and PfSF-1, which are predominantly present in the nucleus of blood stage trophozoites, PfSRSF12 and PfSF-1 are further detectable in the nucleus of gametocytes. We found that recombinantly expressed SR proteins comprising the Arginine/Serine (RS)-rich domains were phosphorylated by the four PfCLKs in in vitro kinase assays, while a recombinant PfSF-1 peptide lacking the RS-rich domain was not phosphorylated. Since it was hitherto not possible to knock-out the pfclk genes by conventional gene disruption, we aimed at chemical knock-outs for phenotype analysis. We identified five human CLK inhibitors, belonging to the oxo-beta-carbolines and aminopyrimidines, as well as the antiseptic chlorhexidine as PfCLK-targeting compounds. The six inhibitors block P. falciparum blood stage replication in the low micromolar to nanomolar range by preventing the trophozoite-to-schizont transformation. In addition, the inhibitors impair gametocyte maturation and gametogenesis in in vitro assays. The combined data show that the four PfCLKs are involved in phosphorylation of SR proteins with essential functions for the blood and sexual stages of the malaria parasite, thus pointing to the kinases as promising targets for antimalarial and transmission blocking drugs.
KW  - parasite
KW  - expression
KW  - mosquito
KW  - splicing factors
KW  - lactate dehydrogenase
KW  - xanthurenic acid
KW  - in-vitro
KW  - RNA-SEQ
KW  - identification
KW  - culture
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-115405
SN  - 1932-6203
VL  - 9
IS  - 9
ER  - 
TY  - JOUR
A1  - Keller, Daniela Barbara
A1  - Schultz, Jörg
T1  - Word Formation Is Aware of Morpheme Family Size
N2  - Words are built from smaller meaning bearing parts, called morphemes. As one word can contain multiple morphemes, one morpheme can be present in different words. The number of distinct words a morpheme can be found in is its family size. Here we used Birth-Death-Innovation Models (BDIMs) to analyze the distribution of morpheme family sizes in English and German vocabulary over the last 200 years. Rather than just fitting to a probability distribution, these mechanistic models allow for the direct interpretation of identified parameters. Despite the complexity of language change, we indeed found that a specific variant of this pure stochastic model, the second order linear balanced BDIM, significantly fitted the observed distributions. In this model, birth and death rates are increased for smaller morpheme families. This finding indicates an influence of morpheme family sizes on vocabulary changes. This could be an effect of word formation, perception or both. On a more general level, we give an example on how mechanistic models can enable the identification of statistical trends in language change usually hidden by cultural influences.
KW  - linguistic morphology
KW  - language
KW  - death rates
KW  - psycholinguistics
KW  - chi square tests
KW  - vocabulary
KW  - birth rates
KW  - culture
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112848
ER  -