Plasmodium falciparum: population genetic analysis by multilocus enzyme electrophoresis and other molecular markers.

Abderrazak, S. B., Oury, B, Lal, A. A., Bosseno, M.-F., Force-Barge, P., Dujardin, J.-P., Fandeur, T., Molez, J.-F., Kjellberg, F., Ayala, F. J., and Tibayrenc, M. 1999. Plasmodium falciparum: Population genetic analysis by multilocus enzyme electrophoresis and other molecular markers. Experimental Parasitology 92, 232-238. The population structure of Plasmodium falciparum, the agent of malignant malaria, is uncertain. We have analyzed multilocus enzyme electrophoresis (MLEE) polymorphisms at 7-12 gene loci in each of four populations (two populations in Burkina Faso, one in Sudan, one in Congo), plus one "cosmopolitan" sample consisting of parasite cultures from 15 distant localities in four different continents. We have also performed random amplified polymorphic DNA analysis (RAPD) and restriction fragment length polymorphism (RFLP) and characterized gene varia tion at four antigen genes in the Congo population. All genetic assays show abundant genetic variability in all populations analyzed. With the isoenzyme assays, strong linkage disequilibrium is apparent in at least two local populations, the Congo population and one population from Burkina Faso, as well as in the cosmopolitan sample, and less definitely in the other Burkina Faso population. However, no linkage disequilibrium is detected in the Congo population with the molecular assays. We failed to detect any nonrandom association between the different kinds of genetic markers; that is, MLEE with RAPD or RFLP, RAPD with RFLP, and so on. Although isoenzyme data show statistical departures from panmictic expectations, these results suggest that in the areas under survey, P. falciparum populations do not undergo predominant clonal evolution and show no clear-cut subdivisions, un like Trypanosoma cruzi, Leishmania sp., and other major parasitic species. We discuss the epidemiological and taxonomical significance of these results.     

Endogenous IL-33 is highly expressed in mouse epithelial barrier tissues, lymphoid organs, brain, embryos, and inflamed tissues: in situ analysis using a novel Il-33-LacZ gene trap reporter strain

IL-33 (previously known as NF from high endothelial venules) is an IL-1 family cytokine that signals through the ST2 receptor and drives cytokine production in mast cells, basophils, eosinophils, invariant NKT and NK cells, Th2 lymphocytes, and type 2 innate immune cells (natural helper cells, nuocytes, and innate helper 2 cells). Little is known about endogenous IL-33; for instance, the cellular sources of IL-33 in mouse tissues have not yet been defined. In this study, we generated an Il-33-LacZ gene trap reporter strain (Il-33(Gt/Gt)) and used this novel tool to analyze expression of endogenous IL-33 in vivo. We found that the Il-33 promoter exhibits constitutive activity in mouse lymphoid organs, epithelial barrier tissues, brain, and embryos. Immunostaining with anti-IL-33 Abs, using Il-33(Gt/Gt) (Il-33-deficient) mice as control, revealed that endogenous IL-33 protein is highly expressed in mouse epithelial barrier tissues, including stratified squamous epithelia from vagina and skin, as well as cuboidal epithelium from lung, stomach, and salivary gland. Constitutive expression of IL-33 was not detected in blood vessels, revealing the existence of species-specific differences between humans and mice. Importantly, IL-33 protein was always localized in the nucleus of producing cells with no evidence for cytoplasmic localization. Finally, strong expression of the Il-33-LacZ reporter was also observed in inflamed tissues, in the liver during LPS-induced endotoxin shock, and in the lung alveoli during papain-induced allergic airway inflammation. Together, our findings support the possibility that IL-33 may function as a nuclear alarmin to alert the innate immune system after injury or infection in epithelial barrier tissues.     

Quenching of a room temperature fluorescence band at 693 nm during photoactivation of the water-splitting system of Photosystem II in flashed barley leaves

The modifications of the room temperature fluorescence spectrum during the photoactivation of the water-splitting system by continuous illumination were investigated in flashed barley leaves. A blue shift of the chlorophyll fluorescence band was detected during the first 2 min of illumination. During this shift, a decrease of the fluorescence intensity around 693 nm could be demonstrated in difference spectra and in second derivative spectra. This decrease is interpreted as a quenching of PS II fluorescence during the photoactivation. A relative fluorescence increase around 672 nm also occurred during the same period and is thought to reflect rapid light-induced chlorophyll formation. The flashed leaves contained small amounts of photoactive photochlorophyllide which could be removed by a short flash of intense white light given before continuous illumination. The fact that such flash had only weak effect on the 693 nm fluorescence decrease, whereas it strongly reduced the amplitude of the 672 nm fluorescence increase, favours the above interpretations.Abbreviations chl chlorophyll - PS II Photosystem II - PS I Photosystem I     

In vitro selection of miltefosine resistance in promastigotes of Leishmania donovani from Nepal: genomic and metabolomic characterization

In this study, we followed the genomic, lipidomic and metabolomic changes associated with the selection of miltefosine (MIL) resistance in two clinically derived Leishmania donovani strains with different inherent resistance to antimonial drugs (antimony sensitive strain Sb‐S; and antimony resistant Sb‐R). MIL‐R was easily induced in both strains using the promastigote‐stage, but a significant increase in MIL‐R in the intracellular amastigote compared to the corresponding wild‐type did not occur until promastigotes had adapted to 12.2 μM MIL. A variety of common and strain‐specific genetic changes were discovered in MIL‐adapted parasites, including deletions at the LdMT transporter gene, single‐base mutations and changes in somy. The most obvious lipid changes in MIL‐R promastigotes occurred to phosphatidylcholines and lysophosphatidylcholines and results indicate that the Kennedy pathway is involved in MIL resistance. The inherent Sb resistance of the parasite had an impact on the changes that occurred in MIL‐R parasites, with more genetic changes occurring in Sb‐R compared with Sb‐S parasites. Initial interpretation of the changes identified in this study does not support synergies with Sb‐R in the mechanisms of MIL resistance, though this requires an enhanced understanding of the parasite's biochemical pathways and how they are genetically regulated to be verified fully.     

Influence de la concentration du glucose et de l'azote sur la morphologie de Candida albicans et la formation de ses chlamydospores dans un milieu de culture synthétique

Résumé Candida albicans a été cultivé à l'obsurité, à 28 °C, dans un milieu de culture synthétique liquide dans lequel on fait varier les concentrations de glucose et d'azote. Des indices de chlamydosporulation ont pu etre calculés pour les milieux contenant au plus 0,08 g/l de glucose. Lorsque la concentration de glucose est plus importante, les thalles pseudomycéliens portent, dans certains cas, de nombreuses chlamydospores, mais aussi des chaines de cellules à contenu dense; ces thalles bourgeonnent des éléments levuriformes qui se détachent et continuent à bourgeonner dans le milieu de culture. Les différentes morphologies rencontrées sont décrites, illustrées et ordonnées en fonction des concentrations de glucose et d'azote du milieu.

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Candida albicans was grown in the darkness, at 28 °C, in a synthetic medium in which glucose and nitrogen concentrations were varied. Numeric appraisal of the chlamydospore index was possible only in the medium where glucose concentration was 0,08 g/l or less. When the glucose concentration raised, pseudomycelial thalli bore numerous chlamydospores but sometimes also chains of cells with a dense granular content. These thalli bud yeast cells which separate and bud again in the medium. The different morphological aspects of the cultures are decribed, illustrated and classified according to the glucose and nitrogen concentration of the medium.

     

Role of dynein, dynactin, and CLIP-170 interactions in LIS1 kinetochore function

Mutations in the human LIS1 gene cause type I lissencephaly, a severe brain developmental disease involving gross disorganization of cortical neurons. In lower eukaryotes, LIS1 participates in cytoplasmic dynein-mediated nuclear migration. We previously reported that mammalian LIS1 functions in cell division and coimmunoprecipitates with cytoplasmic dynein and dynactin. We also localized LIS1 to the cell cortex and kinetochores of mitotic cells, known sites of dynein action. We now find that the COOH-terminal WD repeat region of LIS1 is sufficient for kinetochore targeting. Overexpression of this domain or full-length LIS1 displaces CLIP-170 from this site without affecting dynein and other kinetochore markers. The NH2-terminal self-association domain of LIS1 displaces endogenous LIS1 from the kinetochore, with no effect on CLIP-170, dynein, and dynactin. Displacement of the latter proteins by dynamitin overexpression, however, removes LIS1, suggesting that LIS1 binds to the kinetochore through the motor protein complexes and may interact with them directly. We find that of 12 distinct dynein and dynactin subunits, the dynein heavy and intermediate chains, as well as dynamitin, interact with the WD repeat region of LIS1 in coexpression/coimmunoprecipitation and two-hybrid assays. Within the heavy chain, interactions are with the first AAA repeat, a site strongly implicated in motor function, and the NH2-terminal cargo-binding region. Together, our data suggest a novel role for LIS1 in mediating CLIP-170-dynein interactions and in coordinating dynein cargo-binding and motor activities.     

Identification of genes involved in growth inhibition of breast cancer cells transduced with estrogen receptor

Estrogen receptor alpha (ERalpha)-negative breast cancer cells display an aggressive phenotype. We previously showed that adenoviral expression of ERalpha in ER-negative breast cancer cells leads to an estrogen-dependent down-regulation of the proliferation, which could be of interest to control the growth of such cells. In this study, we observed an increase in protein levels of p21 and p27 cyclin-dependent kinase inhibitors, whereas pRb phosphorylation is strongly decreased. Flow cytometry experiments showed a slower transit of cells in G1 (hormone-independent), a hormone-induced accelerated transit through S phase and a possible arrest in G2/M phase. In addition, ERalpha-expressing cells were undergoing apoptosis. By using cDNA macroarrays, we identified a novel collection of genes regulated by liganded ERalpha potentially regulating cell cycle, apoptosis, cell signalling, stress response and DNA repair.