Changes in the starvation response through covalent cell attachment

Covalent attachment of Candida utilis cells, possibly simulating natural microbial immobilizations, stimulated stable and significant enhancement of extracellular production of alkaline protease, specifically induced by four different starvation conditions. The enzyme analysis confirmed the identity of the proteases released under all conditions of starvation and no parallel production of other proteolytic enzyme. The enhancement phenomenon as a uniform and stable effect of the whole cell immobilization is discussed in relation to the effect of multipoint, cell-solid surface contact, potentially bringing positive modulations of complex, cellular functions.     

In Vivo Interaction Proteomics Reveal a Novel p38 Mitogen-Activated Protein Kinase/Rack1 Pathway Regulating Proteostasis in Drosophila Muscle

Several recent studies suggest that systemic aging in metazoans is differentially affected by functional decline in specific tissues, such as skeletal muscle. In Drosophila, longevity appears to be tightly linked to myoproteostasis, and the formation of misfolded protein aggregates is a hallmark of senescence in aging muscle. Similarly, defective myoproteostasis is described as an important contributor to the pathology of several age-related degenerative muscle diseases in humans, e.g., inclusion body myositis. p38 mitogen-activated protein kinase (MAPK) plays a central role in a conserved signaling pathway activated by a variety of stressful stimuli. Aging p38 MAPK mutant flies display accelerated motor function decline, concomitant with an enhanced accumulation of detergent-insoluble protein aggregates in thoracic muscles. Chemical genetic experiments suggest that p38-mediated regulation of myoproteostasis is not limited to the control of reactive oxygen species production or the protein degradation pathways but also involves upstream turnover pathways, e.g., translation. Using affinity purification and mass spectrometry, we identified Rack1 as a novel substrate of p38 MAPK in aging muscle and showed that the genetic interaction between p38b and Rack1 controls muscle aggregate formation, locomotor function, and longevity. Biochemical analyses of Rack1 in aging and stressed muscle suggest a model whereby p38 MAPK signaling causes a redistribution of Rack1 between a ribosome-bound pool and a putative translational repressor complex.     

Algorithm of Regulatory Signal Recognition in DNA Sequences

An algorithm is proposed for extracting regulatory signals from DNA sequences. The algorithm complexity is nearly quadratic. The results of testing the algorithm on artificial and natural sequences are presented.     

FIMM, a database of functional molecular immunology: update 2002

FIMM database (http://sdmc.krdl.org.sg:8080/fimm) contains data relevant to functional molecular immunology, focusing on cellular immunology. It contains fully referenced data on protein antigens, major histocompatibility complex (MHC) molecules, MHC-associated peptides and relevant disease associations. FIMM has a set of search tools for extraction of information and results are presented as lists or as reports.     

Competing Activities of Heterotrimeric G Proteins in Drosophila Wing Maturation

Drosophila genome encodes six alpha-subunits of heterotrimeric G proteins. The Gαs alpha-subunit is involved in the post-eclosion wing maturation, which consists of the epithelial-mesenchymal transition and cell death, accompanied by unfolding of the pupal wing into the firm adult flight organ. Here we show that another alpha-subunit Gαo can specifically antagonize the Gαs activities by competing for the Gβ13F/Gγ1 subunits of the heterotrimeric Gs protein complex. Loss of Gβ13F, Gγ1, or Gαs, but not any other G protein subunit, results in prevention of post-eclosion cell death and failure of the wing expansion. However, cell death prevention alone is not sufficient to induce the expansion defect, suggesting that the failure of epithelial-mesenchymal transition is key to the folded wing phenotypes. Overactivation of Gαs with cholera toxin mimics expression of constitutively activated Gαs and promotes wing blistering due to precocious cell death. In contrast, co-overexpression of Gβ13F and Gγ1 does not produce wing blistering, revealing the passive role of the Gβγ in the Gαs-mediated activation of apoptosis, but hinting at the possible function of Gβγ in the epithelial-mesenchymal transition. Our results provide a comprehensive functional analysis of the heterotrimeric G protein proteome in the late stages of Drosophila wing development.     

Post‐glacial history and introgression in Abies (Pinaceae) species of the Russian Far East inferred from both nuclear and cytoplasmic markers

Aim The main aim of the present study is to infer the post‐glacial history of Abies species from north‐east Asia and to test the hypotheses that coastal Abies populations suffered less from climatic fluctuations during Pleistocene glacial periods than their more continental counterparts, and that Sakhalin was a major area of introgression. Location Natural ranges of the fir species Abies nephrolepis, Abies sachalinensis and Abies holophylla in the Russian Far East, and of Abies gracilis, which is endemic to the Kamchatka Peninsula. Methods Nineteen populations were sampled for allozyme analysis. Seventeen of these populations were also screened for variation at two paternally inherited chloroplast DNA microsatellite loci (cpSSR) and variation at one maternally inherited mitochondrial marker (nad4‐3/4). Finally a subset of 11 populations was analysed with amplified fragment length polymorphism (AFLP). Comparisons were made with already available Abies sibirica data. For all sets of markers, we estimated genetic diversity and differentiation using an analysis of molecular variance (AMOVA). Population clustering was assessed with a Bayesian approach implemented in structure v.2.3. Results Among the three major species, A. sibirica, A. nephrolepis and A. sachalinensis, A. sachalinensis demonstrated the highest cytoplasmic and nuclear diversity and the most continental species, A. sibirica, the lowest. Both nuclear and mitochondrial DNA markers revealed the presence of a transitional zone on Sakhalin Island between A. nephrolepis and A. sachalinensis of south Sakhalin. The structure analysis delivered very clear results confirming the admixed origin of A. sachalinensis, with a genetic contribution from A. nephrolepis. No variation in cytoplasmic markers was found in A. gracilis, suggesting the occurrence of a recent bottleneck. Main conclusions There is a clear reduction of genetic diversity in Abies species from the Pacific coast into the continent. The higher diversity in A. sachalinensis could have two causes: a larger effective population size in the islands due to relatively stable climatic conditions and consequently less pronounced demographic fluctuations in population size and/or hybridization with continental and Japanese populations. Sakhalin Island is a major transitional zone for conifer species. Finally, the fir from Kamchatka, A. gracilis, should be regarded as a separate species closely related to the A. nephrolepis–A. sachalinensis complex.