Small genome of the fungus Escovopsis weberi,a specialized disease agent of ant agriculture

Many microorganisms with specialized lifestyles have reduced genomes. This is best understood in beneficial bacterial symbioses, where partner fidelity facilitates loss of genes necessary for living independently. Specialized microbial pathogens may also exhibit gene loss relative to generalists. Here, we demonstrate that Escovopsis weberi, a fungal parasite of the crops of fungus-growing ants, has a reduced genome in terms of both size and gene content relative to closely related but less specialized fungi. Although primary metabolism genes have been retained, the E. weberi genome is depleted in carbohydrate active enzymes, which is consistent with reliance on a host with these functions. E. weberi has also lost genes considered necessary for sexual reproduction. Contrasting these losses, the genome encodes unique secondary metabolite biosynthesis clusters, some of which include genes that exhibit up-regulated expression during host attack. Thus, the specialized nature of the interaction between Escovopsis and ant agriculture is reflected in the parasite’s genome.The highly evolved agricultural lifestyle of leaf-cutting ants has attracted particular attention because these ants cultivate a symbiotic fungus that serves as their major food source. These ants cut leaves, preprocess them into small pieces, and feed them to the cultivated fungus (1). The capacity of the cultivated fungus to break down plant material gives ant agriculturalists access to the vast nutrient stores locked within neotropical plants (Fig. 1A) (2–5). The symbiosis between fungus-growing ants and their cultivated fungi has persisted for at least 50 million years (6).Open in a separate windowFig. 1.Escovopsis weberi, a specialized mycoparasite of the fungus-growing ant symbiosis, has a small genome compared with other Pezizomycotina fungi. (A) Both fungus-growing ants and the mycoparasite E. weberi use the ants’ cultivated fungi as their primary food source. The ability of the cultivated fungi to efficiently break down plant material gives both consumers access to the biomass of neotropical plants. (B) Size and protein-coding gene content of genomes of diverse fungi in the Pezizomycotina. Bayesian phylogeny estimated using partial amino acid alignments of three genes (Rpb1, Rpb2, ef1-α). All posterior probabilities are greater than 0.95. Phylogeny is rooted with Sacchormyces cervesiae (not shown). (C) Relationship between genome size and gene content. A list of genomes included in this panel is in SI Appendix, Table S1.Like human agriculture, ant agriculture is hampered by disease. The ants’ fungal crops are attacked and consumed by fungal parasites of the genus Escovopsis (Ascomycota, Pezizomycotina: anamorphic Hypocreales) (Fig. 1A) (7), which have evolved in association with the ants and their cultivated fungi (8). Escovopsis infection can have detrimental impacts on garden health and, consequently, on the survival of ant colonies (9, 10). Such mycoparasitism, the phenomenon whereby one fungus is parasitic on another fungus, is rare. It is most well-known for species from the genus Trichoderma, some of which are used as biocontrol agents for fungal diseases and others of which attack human-cultivated fungi (11–13). In contrast to Trichoderma species, however, Escovopsis species grow poorly in their hosts’ absence (SI Appendix, Figs. S1 and S2).Escovopsis species have never been isolated outside of fungus-growing ant colonies, and different strains of Escovopsis are capable of attacking the fungi grown by different fungus-growing ant species (8, 14, 15). The long-term, specialized evolutionary history of the association between Escovopsis and their hosts provides a unique venue to explore the consequences of host specialization on pathogen genome evolution. Here, we assemble and annotate the genome of a strain of Escovopsis weberi. Consistent with expectations under an evolutionary transition toward using a narrow host range, and similar to many other specialized, host-associated microbes (16, 17), E. weberi exhibits gene loss. Contrasting other fungal pathogens, the large genomes of which are expanded with genetic elements that influence host adaptation (18), the genome size of Escovopsis is small compared with those of its closest sequenced relatives.     

Regenerative Cell and Tissue-based Therapies for Pulmonary Arterial Hypertension

Within the span of 2 decades, cell-based regenerative therapies for pulmonary arterial hypertension have progressed from bench-side hypotheses to clinical realities. Promising preclinical investigations that examined the therapeutic potential of endothelial progenitor cell and mesenchymal stem cell populations have demonstrated the safety and efficacy of these cell types and provided the foundation for first-in-man clinical trials. Moreover, these studies have improved our understanding of the therapeutic mechanisms by which stem/progenitor cells exert their regenerative functions. Ultimately, these discoveries have led to new applications for stem and progenitor cells including the autologous cell reseeding of decellularized or synthetic lung scaffolds. In this review, an overview of established and emerging cell and tissue regenerative therapies for pulmonary lung diseases are presented, along with discussion of recent advancements in the emerging field of repopulating decellularized or bioengineered lung scaffolds with stem/progenitor cells for allogeneic transplant.     

Chronic hepatitis B virus infection and rubella susceptibility in pregnant women

Summary. Increased rubella susceptibility has been shown in subjects from the Asian‐Pacific region where chronic hepatitis B virus (HBV) infection is endemic. This study was performed to explore the relationship between chronic HBV infection and rubella susceptibility in the obstetric population. We conducted a retrospective cohort study on 50556 pregnant women delivered in a university obstetric unit from January 1998 to June 2008. The incidence of rubella susceptibility according to maternal HBV carrier status was examined. HBV infection and rubella susceptibility were found in 5105 (10.1%) and 6102 (12.1%) women, respectively. Rubella susceptibility was more common in women with HBV (13.1%vs 12.0%, P = 0.017), even after adjusting for other confounding factors (odds ratio 1.11, 95% confidence interval 1.01–1.21). Advancing age was associated with progressively decreasing odds of rubella susceptibility, from 0.48 at age 20–24 years to 0.34 at age ≥40 years in women without HBV infection, but had no effect in women with hepatitis B. In conclusion, our study is the first to demonstrate an association between chronic HBV infection with rubella susceptibility. Further studies are warranted to confirm whether chronic HBV infection, especially that acquired by vertical transmission, may impair the immune response to rubella vaccine or natural infection throughout the reproductive age.     

BAD and Bcl-2 regulation are early events linking neuronal endoplasmic reticulum stress to mitochondria-mediated apoptosis

The mechanism of endoplasmic reticulum (ER)-mediated apoptosis in neurons was examined. Using primary cortical neurons, we show that nordihydroguaiaretic acid (NDGA) and brefeldin A (BFA), two ER stressors, induce early ER stress as shown by Western blotting of the eukaryotic initiation factor-2alpha (eIF2alpha), an ER stress marker. This event was associated with an enhancement of neuronal apoptosis as demonstrated by the time-dependent increase in caspase-3 activity and by nuclear fragmentation. The study of the apoptotic signaling showed the translocation of cytochrome c from the mitochondrial matrix to the cytosol. Further evaluation of the apoptotic process revealed that NDGA and BFA induced a rapid dephosphorylation of BAD and decrease expression of Bcl-2. Altogether, our results indicate that neuronal ER stress is associated with an apoptotic cascade involving the mitochondria.     

细胞因子在肝硬化病变中的作用

目的 为了探讨细胞因子与肝硬化病理过程之间的关系。方法 对３０例肝硬化病人应用双抗体夹心法检测血清ＩＬ－６,ＩＬ－８,ＴＮＦ－α含量结果 肝硬化病人血清ＩＬ－６,ＩＬ－８,ＴＮＦ－α含量较对照组升高,血清ＩＬ－６,ＩＬ－８,ＴＮＦ含量三者变化相一致,结论细胞因子在肝纤维化的因过程中起到一定的作用。