Christian Schwarz

Chloroplast heat shock protein Cpn60 from Chlamydomonas reinhardtii exhibits a novel function as a group II intron-specific RNA-binding protein

Intron‐binding proteins in eukaryotic organelles are mainly encoded by the nuclear genome and are thought to promote the maturation of precursor RNAs. Here, we present a biochemical approach that enable the isolation of a novel nuclear‐encoded protein from Chlamydomonas reinhardtii showing specific binding properties to organelle group II intron RNA. Using FPLC chromatography of chloroplast protein extracts, a 61‐kDa RNA‐binding protein was isolated and then tentatively identified by mass spectrometry as the chloroplast heat shock protein Cpn60. Heterologous Cpn60 protein was used in RNA protein gel mobility shift assays and revealed that the ATPase domains of Cpn60 mediates the specific binding of two group II intron RNAs, derived from the homologous chloroplast psaA gene and the heterologous mitochondrial LSU rRNA gene. The function of Cpn60 as a general organelle splicing factor is discussed.

Density-PDFs and Lagrangian statistics of highly compressible turbulence

Abstract In isothermal, highly compressible turbulent flows, density fluctuations follow a log-normal distribution. We establish a connection between these density fluctuations and the probability-density-functions (PDF) of Lagrangian tracer particles advected with the flow. Our predicted particle statistics is tested against large scale numerical simulations, which were performed with 512 3 collocation points and 2 million tracer particles integrated over several dynamical times.

Relationship between mRNA levels and protein accumulation in a chloroplast promoter-mutant of Chlamydomonas reinhardtii

The photosynthetic chloroplast mutant G64 of Chlamydomonas reinhardtii was shown to contain a single point mutation within the 5′ region of the psbD gene encoding the D2 protein of the photosystem II reaction center. The mutation affects the sequence element TATAATAT which has previously been hypothesized to function as the psbD promoter. Run-on analysis confirmed that transcription of psbD in the mutant was reduced to approximately 10% of the wild-type level. However, psbD mRNA accumulated to approximately 35%, despite the prominent decrease in RNA synthesis. This suggests that RNA-stabilization effects can compensate to some extent for a reduction in transcriptional activity. Interestingly, a direct correlation between transcript levels and the accumulation of the psbD gene product, the D2-protein, was observed in G64. The data suggest that posttranscriptionally acting regulatory factors determine the rate-limiting steps of chloroplast psbD gene expression.

A remarkable new species of Mythomantis Giglio-Tos, 1916 from northern Borneo, with notes on the systematics of Deroplatyinae Westwood, 1889 (Mantodea: Mantidae)

A conspicuous new species of praying mantid, Mythomantis serrata sp. nov., from the Malaysian part of Borneo is described and illustrated. A key to the three known species of the genus Mythomantis and their known geographic distribution is provided. Several morphological characters, most notably those in the male genitals, suggest a close relationship between Mythomantis and the Southeast Asian genera Pseudempusa and Deroplatys. As a consequence, we propose to transfer Mythomantis from Angelinae to Deroplatyinae, and Pseudempusa from Miomantinae Rivetinini to Deroplatyinae, while removing Brancsikia from this subfamily.

Nematomorpha from the Philippines, with description of two new species

With the exception of one species, no horsehair worms (Nematomorpha) were known to date from the Philippines. We report here several records, almost all from Panay Island. Two species, Gordius jorriti and Acutogordius finni, are described as new species. Two species of Chordodes, C. caledoniensis and C. cf. moutoni, were found. In addition, further specimens from the genera Gordius, Acutogordius and Chordodes could not be determined to species level.

A new genus and species of praying mantis (Insecta, Mantodea, Mantidae) from Indochina, with a key to Mantidae of South-East Asia

Mekongomantis quinquespinosa gen. et sp. nov., a new Mantidae genus and species is described based on specimens from two localities-Lam Vien plateau in Vietnam and the environments of Umphang, Thailand. The new genus has five posteroventral spines on the forefemur, a feature previously unknown in any Mantidae (sensu stricto) genus. The rest of external morphology is similar to Tenodera Burmeister, 1838 and Mantis Linnaeus, 1758, while the characters of the male genitalia place the species more closely to Hierodula Burmeister, 1838 and Camelomantis Giglio-Tos, 1917. The discovery of such a large (>70 mm) genus level taxon exemplifies the poorly studied diversity of Mantodea in the rapidly deteriorating Greater Mekong area. To ease identification, we also provide a key to the Mantidae of South-East Asia.