Alternative splicing of barley clock genes in response to low temperature:evidence for alternative splicing conservation

Alternative splicing (AS) is a regulated mechanism that generates multiple transcripts from individual genes. It is widespread in eukaryotic genomes and provides an effective way to control gene expression. At low temperatures, AS regulates Arabidopsis clock genes through dynamic changes in the levels of productive mRNAs. We examined AS in barley clock genes to assess whether temperature-dependent AS responses also occur in a monocotyledonous crop species. We identify changes in AS of various barley core clock genes including the barley orthologues of Arabidopsis AtLHY and AtPRR7 which showed the most pronounced AS changes in response to low temperature. The AS events modulate the levels of functional and translatable mRNAs, and potentially protein levels, upon transition to cold. There is some conservation of AS events and/or splicing behaviour of clock genes between Arabidopsis and barley. In addition, novel temperature-dependent AS of the core clock gene HvPPD-H1 (a major determinant of photoperiod response and AtPRR7 orthologue) is conserved in monocots. HvPPD-H1 showed a rapid, temperature-sensitive isoform switch which resulted in changes in abundance of AS variants encoding different protein isoforms. This novel layer of low temperature control of clock gene expression, observed in two very different species, will help our understanding of plant adaptation to different environments and ultimately offer a new range of targets for plant improvement

Comparative genomics of the tardigrades <i>Hypsibius dujardini</i> and <i>Ramazzottius varieornatus</i>

Tardigrada, a phylum of meiofaunal organisms, have been at the center of discussions of the evolution of Metazoa, the biology of survival in extreme environments, and the role of horizontal gene transfer in animal evolution. Tardigrada are placed as sisters to Arthropoda and Onychophora (velvet worms) in the superphylum Panarthropoda by morphological analyses, but many molecular phylogenies fail to recover this relationship. This tension between molecular and morphological understanding may be very revealing of the mode and patterns of evolution of major groups. Limnoterrestrial tardigrades display extreme cryptobiotic abilities, including anhydrobiosis and cryobiosis, as do bdelloid rotifers, nematodes, and other animals of the water film. These extremophile behaviors challenge understanding of normal, aqueous physiology: how does a multicellular organism avoid lethal cellular collapse in the absence of liquid water? Meiofaunal species have been reported to have elevated levels of horizontal gene transfer (HGT) events, but how important this is in evolution, and particularly in the evolution of extremophile physiology, is unclear. To address these questions, we resequenced and reassembled the genome of H. dujardini, a limnoterrestrial tardigrade that can undergo anhydrobiosis only after extensive pre-exposure to drying conditions, and compared it to the genome of R. varieornatus, a related species with tolerance to rapid desiccation. The 2 species had contrasting gene expression responses to anhydrobiosis, with major transcriptional change in H. dujardini but limited regulation in R. varieornatus. We identified few horizontally transferred genes, but some of these were shown to be involved in entry into anhydrobiosis. Whole-genome molecular phylogenies supported a Tardigrada+Nematoda relationship over Tardigrada+Arthropoda, but rare genomic changes tended to support Tardigrada+Arthropoda

Cytology and Cytogenetics

Several cytological aspects have been considered in tardigrades. Firstly, the cell constancy which is not a true eutely being several mitoses present even after hatching, even though some organs, such epidermis and nervous ganglia, have the same cell number in juveniles and adults. The total number of these cells is speciesspecific. Then the ultrastructure of cuticle, epidermis, feeding and digestive apparatus, excretory and osmoregulatory organs, muscles, nerve cells, sensory cells and storage cells has been considered. Instead, the ultrastructure of the germ cells has been considered in the chapter on reproduction. With regard to chromosome number and shape, it has been observed that generally there is little difference among the species (n ¼ 5 or n ¼ 6), but several cases of polyploid populations exist, often very similar to diploid populations from a morphological point of view. In most cases the polyploid populations do not have males and reproduce by apomixis. Studies on the genome size have confirmed the presence of polyploid populations, as well as the presence of nuclei with multiple amounts of DNA within the same specimen. The genome size of the tardigrades is always relatively small and does not seem related to phylogenetic lineages. Studies on tardigrade genomes have placed this phylum at the centre of discussions on the evolution of Metazoa and have considered the role of horizontal gene transfer in animal evolution with contrasting results

Induction of interleukin-12 production in mouse macrophages by berberine, a benzodioxoloquinolizine alkaloid, deviates CD4(+) T cells from a Th2 to a Th1 response

In this study we investigated whether berberine-mediated induction of interleukin-12 (IL-12) production in antigen-presenting cells could regulate a cytokine profile of antigen-primed CD4(+) T helper (Th) cells. Pretreatment with berberine induced IL-12 production in both macrophages and dendritic cells, and significantly increased the levels of IL-12 production in lipopolysaccharide-stimulated macrophages and in CD40 ligand-stimulated dendritic cells. Importantly, berberine pretreatment of macrophages increased their ability to induce interferon-γ (IFN-γ) and reduced their ability to induce IL-4 in antigen-primed CD4(+) T cells. Berberine did not influence the macrophage cell surface expression of the class II major histocompatibility complex molecule, the co-stimulatory molecules CD80 and CD86, and intracellular adhesion molecule-1. Addition of neutralizing anti-IL-12p40 monoclonal antibody to cultures of berberine-pretreated macrophages and CD4(+) T cells restored IL-4 production in antigen-primed CD4(+) T cells. The in vivo administration of berberine resulted in the enhanced induction of IL-12 production by macrophages when stimulated in vitro with lipopolysaccharide or heat-killed Listeria monocytogenes, leading to the inhibition of the Th type 2 cytokine profile (decreased IL-4 and increased IFN-γ production) in antigen-primed CD4(+) T cells. These findings may point to a possible therapeutic use of berberine or medicinal plants containing berberine in the Th type 2 cell-mediated immune diseases such as allergic diseases