The microRNA miR-17 regulates lung FoxA1 expression during lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI) is a severe pulmonary disease that causes a high number of fatalities worldwide. Studies have shown that FoxA1 expression is upregulated during ALI and may play an important role in ALI by promoting the apoptosis of alveolar type II epithelial cells. However, the mechanism of FoxA1 overexpression in ALI is unclear. In this study, an in vivo murine model of ALI and alveolar type II epithelial cells injury was induced using lipopolysaccharide (LPS). LPS upregulated FoxA1 in the lung tissue of the in vivo ALI model and in LPS-challenged type II epithelial cells. In contrast, miR-17 was significantly downregulated in these models. After miR-17 antagomir injection, the expression of FoxA1 was significantly increased in ALI mice. MiR-17 mimics could significantly inhibit FoxA1 mRNA and protein expression, whereas the miR-17 inhibitor could significantly increase FoxA1 mRNA and protein expression in LPS-induced type II epithelial cells. Thus, our results suggest that the downregulation of miR-17 expression could lead to FoxA1 overexpression in ALI.     

Caenorhabditis nematodes colonize ephemeral resource patches in neotropical forests

Factors shaping the distribution and abundance of species include life‐history traits, population structure, and stochastic colonization–extinction dynamics. Field studies of model species groups help reveal the roles of these factors. Species of Caenorhabditis nematodes are highly divergent at the sequence level but exhibit highly conserved morphology, and many of these species live in sympatry on microbe‐rich patches of rotten material. Here, we use field experiments and large‐scale opportunistic collections to investigate species composition, abundance, and colonization efficiency of Caenorhabditis species in two of the world''s best‐studied lowland tropical field sites: Barro Colorado Island in Panamá and La Selva in Sarapiquí, Costa Rica. We observed seven species of Caenorhabditis, four of them known only from these collections. We formally describe two species and place them within the Caenorhabditis phylogeny. While these localities contain species from many parts of the phylogeny, both localities were dominated by globally distributed androdiecious species. We found that Caenorhabditis individuals were able to colonize baits accessible only through phoresy and preferentially colonized baits that were in direct contact with the ground. We estimate the number of colonization events per patch to be low.     

No evidence that polyandry benefits females in Drosophila melanogaster

Understanding the evolution of polyandry (mating with multiple males) is a major issue in the study of animal breeding systems. We examined the adaptive significance of polyandry in Drosophila melanogaster, a species with well-documented costs of mating in which males generally cannot force copulations. We found no direct fitness advantages of polyandry. Females that mated with multiple males had no greater mean fitness and no different variance in fitness than females that mated repeatedly with the same male. Subcomponents of reproductive success, including fecundity, egg hatch rate, larval viability, and larval development time, also did not differ between polyandrous and monogamous females. Polyandry had no affect on progeny sex ratios, suggesting that polyandry does not function against costly sex-ratio distorters. We also found no evidence that polyandry functions to favor the paternity of males successful in precopulatory sexual selection. Experimentally controlled opportunities for precopulatory sexual selection had no effect on postcopulatory sperm precedence. Although these results were generally negative, they are supported with substantial statistical power and they help narrow the list of evolutionary explanations for polyandry in an important model species.     

Design,synthesis, and biological evaluation of a cephalosporin-monohydroguaiaretic acid prodrug activated by a monoclonal antibody-beta-lactamase conjugate

A novel cephalosporin derivative of monohydroguaiaretic acid (cephem-M(3)N, 7) was synthesized and found to possess anticancer activity against human leukemia (K562), breast carcinoma (MCF7), human lung cancer (A549), human colon cancer (Colo205) and pancreatic cancer cells (Capan2 and MiaPaCa2). A tumor targeting fusion protein (dsFv3-beta-lactamase) was also used in conjunction with cephem-based M(3)N 7 and its potency toward K562, MCF7, A549, Colo205, Capan2, and MiaPaCa2 was found to approach that of the free M(3)N (4). In the presence of dsFv3-beta-lactamase, tumor cells were found to be much more susceptible to conjugate 7 than normal human embryonic lung (HEL) cells and normal fibroblasts (Hef522). These notions provide a new approach to the use of nordihydroguaiaretic acid (NDGA) and its derivatives for antitumor therapy.     

Soil biotic processes remain remarkably stable after 100-year extreme weather events in experimental grassland and heath

Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that extreme weather events pose threats to ecosystem functioning, particularly to nutrient cycling and biomass production. These ecosystem functions depend strongly on below-ground biotic processes, including the activity and interactions among plants, soil fauna, and micro-organisms. Here, experimental grassland and heath communities of three phytodiversity levels were exposed either to a simulated single drought or to a heavy rainfall event. Both weather manipulations were repeated for two consecutive years. The magnitude of manipulations imitated the local 100-year extreme weather event. Heavy rainfall events increased below-ground plant biomass and stimulated soil enzyme activities as well as decomposition rates for both plant communities. In contrast, extreme drought did not reduce below-ground plant biomass and root length, soil enzyme activities, and cellulose decomposition rate. The low responsiveness of the measured ecosystem properties in face of the applied weather manipulations rendered the detection of significant interactions between weather events and phytodiversity impossible. Our data indicate on the one hand the close interaction between below ground plant parameters and microbial turnover processes in soil; on the other hand it shows that the plant–soil system can buffer against extreme drought events, at last for the period of investigation.     

Effect of sedation with detomidine and butorphanol on pulmonary gas exchange in the horse

Background  

Sedation with α₂-agonists in the horse is reported to be accompanied by impairment of arterial oxygenation. The present study was undertaken to investigate pulmonary gas exchange using the Multiple Inert Gas Elimination Technique (MIGET), during sedation with the α₂-agonist detomidine alone and in combination with the opioid butorphanol.     

Structural analysis of chloroplast tail‐anchored membrane protein recognition by ArsA1

In mammals and yeast, tail‐anchored (TA) membrane proteins destined for the post‐translational pathway are safely delivered to the endoplasmic reticulum (ER) membrane by a well‐known targeting factor, TRC40/Get3. In contrast, the underlying mechanism for translocation of TA proteins in plants remains obscure. How this unique eukaryotic membrane‐trafficking system correctly distinguishes different subsets of TA proteins destined for various organelles, including mitochondria, chloroplasts and the ER, is a key question of long standing. Here, we present crystal structures of algal ArsA1 (the Get3 homolog) in a distinct nucleotide‐free open state and bound to adenylyl‐imidodiphosphate. This approximately 80‐kDa protein possesses a monomeric architecture, with two ATPase domains in a single polypeptide chain. It is capable of binding chloroplast (TOC34 and TOC159) and mitochondrial (TOM7) TA proteins based on features of its transmembrane domain as well as the regions immediately before and after the transmembrane domain. Several helices located above the TA‐binding groove comprise the interlocking hook‐like motif implicated by mutational analyses in TA substrate recognition. Our data provide insights into the molecular basis of the highly specific selectivity of interactions of algal ArsA1 with the correct sets of TA substrates before membrane targeting in plant cells.     

��-arrestin Kurtz inhibits MAPK and Toll signalling in Drosophila development

β‐Arrestins have been implicated in the regulation of multiple signalling pathways. However, their role in organism development is not well understood. In this study, we report a new in vivo function of the Drosophila β‐arrestin Kurtz (Krz) in the regulation of two distinct developmental signalling modules: MAPK ERK and NF‐κB, which transmit signals from the activated receptor tyrosine kinases (RTKs) and the Toll receptor, respectively. Analysis of the expression of effectors and target genes of Toll and the RTK Torso in krz maternal mutants reveals that Krz limits the activity of both pathways in the early embryo. Protein interaction studies suggest a previously uncharacterized mechanism for ERK inhibition: Krz can directly bind and sequester an inactive form of ERK, thus preventing its activation by the upstream kinase, MEK. A simultaneous dysregulation of different signalling systems in krz mutants results in an abnormal patterning of the embryo and severe developmental defects. Our findings uncover a new in vivo function of β‐arrestins and present a new mechanism of ERK inhibition by the Drosophila β‐arrestin Krz.     

YMR313c/TGL3 encodes a novel triacylglycerol lipase located in lipid particles of Saccharomyces cerevisiae

Previous work from our laboratory (Athenstaedt, K., Zweytick, D., Jandrositz, A., Kohlwein, S. D., and Daum, G. (1999) J. Bacteriol. 181, 6441-6448) showed that the gene product of YMR313c (named Tgl3p) is a component of yeast lipid particles, and deletion of this gene led to an increase in the cellular level of triacylglycerols (TAG). These observations suggested that TGL3 may encode a TAG lipase of Saccharomyces cerevisiae. Here we demonstrate by cell fractionation and by microscopic inspection of a strain bearing a Tgl3p-GFP hybrid that this polypeptide is highly enriched in the lipid particle fraction but virtually absent from other organelles. The entire TAG lipase activity of lipid particles is attributed to Tgl3p, because the activity in this organelle is completely absent in a Deltatgl3 deletion mutant, whereas it is significantly enhanced in a strain overexpressing Tgl3p. A His6-tagged Tgl3p hybrid purified close to homogeneity from a yeast strain overexpressing this fusion protein exhibited high TAG lipase activity. Most importantly, experiments in vivo using the fatty acid synthesis inhibitor cerulenin demonstrated that deletion of TGL3 resulted in a decreased mobilization of TAG from lipid particles. The amino acid sequence deduced from the open reading frame YMR313c contains the consensus sequence motif GXSXG typical for lipolytic enzymes. Otherwise, Tgl3p has no significant sequence homology to other lipases identified so far. In summary, our data identified Tgl3p as a novel yeast TAG lipase at the molecular level and by function in vivo and in vitro.