Age-related skeletal dynamics and decrease in bone strength in DNA repair deficient male trichothiodystrophy mice

Accumulation of DNA damage caused by oxidative stress is thought to be one of the main contributors of human tissue aging. Trichothiodystrophy (TTD) mice have a mutation in the Ercc2 DNA repair gene, resulting in accumulation of DNA damage and several features of segmental accelerated aging. We used male TTD mice to study the impact of DNA repair on bone metabolism with age. Analysis of bone parameters, measured by micro-computed tomography, displayed an earlier decrease in trabecular and cortical bone as well as a loss of periosteal apposition and a reduction in bone strength in TTD mice with age compared to wild type mice. Ex vivo analysis of bone marrow differentiation potential showed an accelerated reduction in the number of osteogenic and osteoprogenitor cells with unaltered differentiation capacity. Adipocyte differentiation was normal. Early in life, osteoclast number tended to be increased while at 78 weeks it was significantly lower in TTD mice. Our findings reveal the importance of genome stability and proper DNA repair for skeletal homeostasis with age and support the idea that accumulation of damage interferes with normal skeletal maintenance, causing reduction in the number of osteoblast precursors that are required for normal bone remodeling leading to a loss of bone structure and strength.     

Dual energy x-ray absorptiometry analysis contributes to the prediction of hip osteoarthritis progression

Introduction  

To determine if structural bone parameters obtained from dual energy X-ray absorptiometry (DXA) contribute to the prediction of progression of hip osteoarthritis (OA) and to test if the difference between the most affected (OA) hip and the contralateral hip adds to this prediction.     

Shedding of Vaccine Viruses with Increased Antigenic and Genetic Divergence after Vaccination of Newborns with Monovalent Type 1 Oral Poliovirus Vaccine

For the final stages in the eradication of poliovirus type 1 (P1), the World Health Organization advocates the selective use of monovalent type 1 oral poliovirus vaccine (mOPV1). To compare the immunogenicity of mOPV1 with that of trivalent OPV (tOPV) in infants, a study was performed in Egypt in 2005. Newborns were vaccinated with mOPV1 or tOPV immediately after birth and were challenged with mOPV1 after 1 month. Vaccination with mOPV1 at birth resulted in significantly higher seroconversion against P1 viruses and lower excretion of P1 viruses than vaccination with tOPV. Intratypic differentiation of the viruses shed by the newborns revealed the presence of remarkably high numbers of antigenically divergent (AD) P1 isolates, especially in the mOPV1 study group. The majority of these AD P1 isolates (71%) were mOPV1 challenge derived and were shed by newborns who did not seroconvert to P1 after the birth dose. Genetic characterization of the viruses revealed that amino acid 60 of the VP3 region was mutated in all AD P1 isolates. Isolates with substitution of residue 99 of the VP1 region had significantly higher numbers of nonsynonymous mutations in the VP1 region than isolates without this substitution and were preferentially shed in the mOPV1 study group. The widespread use of mOPV1 has proven to be a powerful tool for fighting poliovirus circulation in the remaining areas of endemicity. This study provides another justification for the need to achieve high vaccination coverage in order to prevent the circulation of AD strains.Polioviruses are the causative agents of human poliomyelitis and belong to the genus Enterovirus in the family Picornaviridae. The virus is transmitted primarily by the fecal-oral route and replicates in the human intestinal tract. The virus may also be transmitted through respiratory droplets and may replicate for a short period in the upper respiratory tract and tonsillar tissue. From either site of primary replication, the virus may invade the central nervous system and cause paralysis following infection and destruction of motor neurons. Three serologically different types of poliovirus can be distinguished (poliovirus type 1 [P1], P2, and P3), and only limited cross-protection exists between serotypes (35).In 1988, the World Health Assembly passed a resolution to eradicate wild poliovirus globally. A worldwide vaccination campaign with the trivalent oral poliovirus vaccine (tOPV) was launched by the World Health Organization (WHO). This vaccine contains the three attenuated poliovirus vaccine strains developed by Albert Sabin in the proportion of 10:1:6 for P1, P2, and P3, respectively. These OPV strains have been selected to replicate successfully in the human intestinal tract but not in the cells of the central nervous system. In addition to a strong humoral response, these strains generate strong intestinal immunity (12). Sabin type 1 is considered to be the most stable of the three attenuated poliovirus serotypes (19). This strain has 54 mutations compared to the parental Mahoney strain, of which 6 are primarily responsible for attenuation. Sabin type 2 has two major determinants of attenuation, and Sabin type 3 has three determinants of attenuation (11, 32). Upon replication in the human intestinal tract, the sites of attenuation can mutate, which results in reversion of the Sabin strains toward a parental neurovirulent phenotype. Also as a consequence of replication in the host, antibodies are produced that recognize the antigenic sites of the Sabin strains (42). This immunogenic pressure could favor the selection of antigenically divergent (AD) viruses with substituted residues in parts of these antigenic sites. AD Sabin viruses might circulate among a population for a long period and evolve into vaccine-derived polioviruses (VDPVs; with differences of >1% from the prototype Sabin viruses in the VP1 region) capable of causing outbreaks. These viruses might escape current diagnostic screening methods, and the risk for generation of these viruses should be reduced as much as possible (1, 9, 16).The tOPV vaccination campaigns have been very successful, since the number of countries with endemic wild poliovirus circulation decreased from >125 in 1988 to 4 in 2006, and wild type 2 poliovirus has likely been eradicated since 1999 (5). The tOPV vaccine, however, is known to be less immunogenic against type 1 and 3 polioviruses. After tOPV administration, the superior replicative capacity of the P2 vaccine strain interferes with effective replication of the other two serotype viruses in the human intestine (30). To eradicate wild P1 as well, vaccination with monovalent type 1 oral poliovirus vaccine (mOPV1) was introduced in the remaining countries where poliovirus is endemic, since this vaccine is more immunogenic for type 1 than the tOPV (4, 20).In 2005/2006, a clinical study was conducted in Egypt to compare the immunogenicity of mOPV1 with that of the tOPV in newborns (15). Newborns were vaccinated with mOPV1 or tOPV as soon as possible after birth and were challenged with mOPV1 4 weeks later. Vaccination with mOPV1 at birth resulted in a higher humoral and mucosal protection against P1 at day 28 than vaccination with tOPV at birth.In line with the recommendations of the WHO Polio Laboratory Network, we determined the antigenic characters of all the viruses shed by the newborns of the Egyptian study by using an intratypic differentiation (ITD) enzyme-linked immunosorbent assay (ELISA). The outcome of this analysis, an unexpectedly high percentage of AD isolates, prompted further investigation. To determine the possible presence of VDPVs and to gain insight into the genetic and antigenic evolution of the mOPV1 and tOPV isolates shed by the newborns in this study, we determined the sequences of the capsid regions of these isolates. We looked for correlates with antigenic change and rates of mutagenesis in the viruses and compared the evolution rates of the viruses shed by vaccinees of both study groups. We also linked the serological data collected during the study to the excretion of Sabin 1 isolates.     

Regulation of the <Emphasis Type="Italic">cellulose synthase-like</Emphasis> gene family by light in the maize mesocotyl

The cellulose synthase-like (ZmCSL) gene family of maize was annotated and its expression studied in the maize mesocotyl. A total of 28 full-length CSL genes and another 13 partial sequences were annotated; four are predicted to be pseudogenes. Maize has all of the CSL subfamilies that are present in rice, but the CSLC subfamily is expanded from 6 in rice to 12 in maize, and the CSLH subfamily might be reduced from 3 to 1. Unlike rice, maize has a gene in the CSLG subfamily, based on its sequence similarity to two genes annotated as CSLG in poplar. Light regulation of glycan synthase enzyme activities and CSL gene expression were analyzed in the mesocotyl. A Golgi-localized glucan synthase activity is reduced by ~50% 12 h after exposure to light. β-1,4-Mannan synthase activity is reduced even more strongly (>85%), whereas β-1,4-xylan synthase, callose synthase, and latent IDPase activity respond only slightly, if at all, to light. At least 17 of the CSL genes (42%) are expressed in the mesocotyl, of which four are up-regulated at least twofold, seven are down-regulated at least twofold, and six are not affected by light. The results contribute to our understanding of the structure of the CSL gene family in an important food and biofuel plant, show that a large percentage of the CSL genes are expressed in the specialized tissues of the mesocotyl, and demonstrate that members of the CSL gene family are differentially subject to photobiological regulation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Do lichens domesticate photobionts like farmers domesticate crops? Evidence from a previously unrecognized lineage of filamentous cyanobacteria

Phylogenetic diversity of lichen photobionts is low compared to that of fungal counterparts. Most lichen fungi are thought to be associated with just four photobiont genera, among them the cyanobacteria Nostoc and Scytonema, two of the most important nitrogen fixers in humid ecosystems. Although many Nostoc photobionts have been identified using isolated cultures and sequences, the identity of Scytonema photobionts has never been confirmed by culturing or sequencing. We investigated the phylogenetic placement of presumed Scytonema photobionts and unicellular morphotypes previously assigned to Chroococcus, from tropical Dictyonema, Acantholichen, Coccocarpia, and Stereocaulon lichens. While we confirm that filamentous and unicellular photobiont morphotypes belong to a single clade, this clade does not cluster with Scytonema but represents a novel, previously unrecognized, highly diverse, exclusively lichenized lineage, for which the name Rhizonema is available. The phylogenetic structure observed in this novel lineage suggests absence of coevolution with associated mycobionts at the species or clade level. Instead, highly efficient photobiont strains appear to have evolved through photobiont sharing between unrelated, but ecologically similar, coexisting lineages of lichenized fungi ("lichen guilds"), via the selection of particular photobiont strains through and subsequent horizontal transfer among unrelated mycobionts, a phenomenon not unlike crop domestication.     

A five-gene phylogeny of Pezizomycotina

Pezizomycotina is the largest subphylum of Ascomycota and includes the vast majority of filamentous, ascoma-producing species. Here we report the results from weighted parsimony, maximum likelihood and Bayesian phylogenetic analyses of five nuclear loci (SSU rDNA, LSU rDNA, RPB1, RPB2 and EF-lalpha) from 191 taxa. Nine of the 10 Pezizomycotina classes currently recognized were represented in the sampling. These data strongly supported the monophyly of Pezizomycotina, Arthoniomycetes, Eurotiomycetes, Orbiliomycetes and Sordariomycetes. Pezizomycetes and Dothideomycetes also were resolved as monophyletic but not strongly supported by the data. Lecanoromycetes was resolved as paraphyletic in parsimony analyses but monophyletic in maximum likelihood and Bayesian analyses. Leotiomycetes was polyphyletic due to exclusion of Geoglossaceae. The two most basal classes of Pezizomycotina were Orbiliomycetes and Pezizomycetes, both of which comprise species that produce apothecial ascomata. The seven remaining classes formed a monophyletic group that corresponds to Leotiomyceta. Within Leotiomyceta, the supraclass clades of Leotiomycetes s.s. plus Sordariomycetes and Arthoniomycetes plus Dothideomycetes were resolved with moderate support.     

Effect of bioaugmentation and supplementary carbon sources on degradation of polycyclic aromatic hydrocarbons by a soil-derived culture

The degradation of polycyclic aromatic hydrocarbons (PAHs) by an undefined culture obtained from a PAH-polluted soil and the same culture bioaugmented with three PAH-degrading strains was studied in carbon-limited chemostat cultures. The PAHs were degraded efficiently by the soil culture and bioaugmentation did not significantly improve the PAH degrading performance. The presence of PAHs did, however, influence the bacterial composition of the bioaugmented and non-bioaugmented soil cultures, resulting in the increase in cell concentration of sphingomonad strains. the initial enhancement of the degradation of the PAHs by biostimulation gradually disappeared and only the presence of salicylate in the additional carbon sources had a lasting slightly stimulating effect on the degradation of phenanthrene. The results suggest that bioaugmentation and biostimulation have limited potential to enhance PAH bioremediation by culture already proficient in the degradation of such contaminants.     

Endothelium specific matrilysin (MMP-7) expression in human cancers.

Over-expression of matrilysin (MMP-7) is predominantly associated with epithelial (pre)malignant cells. In the present study MMP-7 expression is also found in endothelial cells in various human cancer types. Endothelial MMP-7 was associated with CD34 and/or CD105 expression. These immunohistochemical data were confirmed by RT-PCR on VEGF-stimulated endothelial cells. In addition, MMP-7 was also identified in sprouting endothelial cells in vitro. The potential clinical relevance of endothelial MMP-7 was assessed for cervical cancer patients by evaluating the association with overall survival. In contrast to MMP-7 in malignant epithelial cells, MMP-7 expression in endothelial cells showed a significant association with poor survival (LR 5.12, P=0.02, n=30). Our data suggest that MMP-7 is involved in tumor angiogenesis, thereby contributing to malignant growth and hence associated with decreased survival.     

Platelet endothelial cell adhesion molecule-1 (PECAM-1) inhibits low density lipoprotein-induced signaling in platelets

At physiological concentrations, low density lipoprotein (LDL) increases the sensitivity of platelets to aggregation- and secretion-inducing agents without acting as an independent activator of platelet functions. LDL sensitizes platelets by inducing a transient activation of p38MAPK, a Ser/Thr kinase that is activated by the simultaneous phosphorylation of Thr180 and Tyr182 and is an upstream regulator of cytosolic phospholipase A2 (cPLA2). A similar transient phosphorylation of p38MAPK is induced by a peptide mimicking amino acids 3359-3369 in apoB100 called the B-site. Here we report that the transient nature of p38MAPK activation is caused by platelet endothelial cell adhesion molecule 1 (PECAM-1), a receptor with an immunoreceptor tyrosine-based inhibitory motif. PECAM-1 activation by cross-linking induces tyrosine phosphorylation of PECAM-1 and a fall in phosphorylated p38MAPK and cPLA2. Interestingly, LDL and the B-site peptide also induce tyrosine phosphorylation of PECAM-1, and studies with immunoprecipitates indicate the involvement of c-Src. Inhibition of the Ser/Thr phosphatases PP1/PP2A (okadaic acid) makes the transient p38MAPK activation by LDL and the B-site peptide persistent. Inhibition of Tyr-phosphatases (vanadate) increases Tyr-phosphorylated PECAM-1 and blocks the activation of p38MAPK. Together, these findings suggest that, following a first phase in which LDL, through its B-site, phosphorylates and thereby activates p38MAPK, a second phase is initiated in which LDL activates PECAM-1 and induces dephosphorylation of p38MAPK via activation of the Ser/Thr phosphatases PP1/PP2A.     

Circulation of endemic type 2 vaccine-derived poliovirus in Egypt from 1983 to 1993

From 1988 to 1993, 30 cases of poliomyelitis associated with poliovirus type 2 were found in seven governorates of Egypt. Because many of the cases were geographically and temporally clustered and because the case isolates differed antigenically from the vaccine strain, it was initially assumed that the cases signaled the continued circulation of wild type 2 poliovirus. However, comparison of sequences encoding the major capsid protein, VP1 (903 nucleotides), revealed that the isolates were related (93 to 97% nucleotide sequence identity) to the Sabin type 2 oral poliovirus vaccine (OPV) strain and unrelated (<82% nucleotide sequence identity) to the wild type 2 polioviruses previously indigenous to Egypt (last known isolate: 1979) or to any contemporary wild type 2 polioviruses found elsewhere. The rate and pattern of VP1 divergence among the circulating vaccine-derived poliovirus (cVDPV) isolates suggested that all lineages were derived from a single OPV infection that occurred around 1983 and that progeny from the initiating infection circulated for approximately a decade within Egypt along several independent chains of transmission. Complete genomic sequences of an early (1988) and a late (1993) cVDPV isolate revealed that their 5' untranslated region (5' UTR) and noncapsid- 3' UTR sequences were derived from other species C enteroviruses. Circulation of type 2 cVDPVs occurred at a time of low OPV coverage in the affected communities and ceased when OPV coverage rates increased. The potential for cVDPVs to circulate in populations with low immunity to poliovirus has important implications for current and future strategies to eradicate polio worldwide.