Cryptic species of cardinalfish with evidence for old and new divergence

Larval dispersal and limited knowledge of physical boundaries challenge our understanding of the processes that drive genetic divergence and potential speciation in the marine environment. Divergence, both within and between populations of marine taxa, is not uncommon, but spatial and temporal stability of observed genetic structure is not well known. Previously, we detected large genetic differences among populations of the cardinalfish species Ostorhinchus doederleini inhabiting adjacent coral reefs. Here, we determined the spatial and temporal persistence of these genetic structures over the course of ten consecutive generations. Using microsatellite markers, we detected large changes (genetic population distance, D _est, ranged from 0.04 to 0.46) in the genetic structure in some years, but some reefs maintained the same populations for nearly all sampling years. As this species’ life span does not exceed 1 yr, persistence of distinct reef populations suggests natal homing. Mitochondrial identity based on two mtDNA markers corroborates the nuclear genetic evidence for genetic differences large enough to constitute different clades and even cryptic species in O. doederleini, which, based on gross morphology, was thought to be a single taxon. Habitat specialization was observed in one clade that exclusively inhabited reef lagoons, while all clades could be observed on reef slopes. We suggest that local habitat recognition combined with local population recognition and selection against hybrids can form barriers that maintain a cryptic species complex.     

Cathepsins B, K, and L are regulated by a defined collagen type II peptide via activation of classical protein kinase C and p38 MAP kinase in articular chondrocytes

Degradation of the extracellular matrix (ECM) is a prominent feature in osteoarthritis (OA), which is mainly because of the imbalance between anabolic and catabolic processes in chondrocytes resulting in cartilage and bone destruction. Various proteases act in concert to degrade matrix components, e.g. type II collagen, MMPs, ADAMTS, and cathepsins. Protease-generated collagen fragments may foster the destructive process. However, the signaling pathways associated with the action of collagen fragments on chondrocytes have not been clearly defined. The present data demonstrate that the N-terminal telopeptide of collagen type II enhances expression of cathepsins B, K, and L in articular chondrocytes at mRNA, protein, and activity levels, mediated at least in part through extracellular calcium. We also demonstrate that the induction is associated with the activation of protein kinase C and p38 MAP kinase.     

Intermediates in the oxidative pathway from torulene to torularhodin in the red yeasts Cystofilobasidium infirmominiatum and C. capitatum (Heterobasidiomycetes, Fungi)

Two red Cystofilobasidium spp. isolated from spring sap-flows of Betula pendula were analysed for their carotenoid content. In Cystofilobasidium infirmominiatum, three unusual pigments were detected and identified by structure elucidation as oxidised torulene derivatives. These included 16'-hydroxytorulene and torularhodinaldehyde, two carotenoids known so far only from chemical synthesis or as postulated biosynthetic intermediates en route to torularhodin. Unprecedented formation of beta-apo-2'-carotenal was also observed. The production of these pigments in pure culture was dependent on enhanced oxidative stress caused by cultivation in well-aerated (indented) flasks with or without 2% ethanol (16'-hydroxytorulene), or with 100 microM duroquinone (torularhodinaldehyde and beta-apo-2'-carotenal). Among these three pigments, only 16'-hydroxytorulene was detected in C. capitatum. Torularhodin, a common end product of carotenoid oxidation in red yeasts, was not produced by either species under any incubation conditions. Biosynthetic aspects of incomplete oxidation of torulene by these Cystofilobasidium spp. are discussed.     

Correlation of MicroRNA-16, MicroRNA-21 and MicroRNA-101 Expression with Cyclooxygenase-2 Expression and Angiogenic Factors in Cirrhotic and Noncirrhotic Human Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is a classical example of inflammation-linked cancer and is characterized by hypervascularity suggesting rich angiogenesis. Cycloxygenase-2 (COX-2) is a potent mediator of inflammation and is considered to upregulate angiogenesis. The aims of the study are (1) to analyze expression of Cox-2 mRNA, Cox-2 protein, miR-16, miR-21 and miR-101 in HCC and adjacent liver parenchyma in cirrhotic and noncirrhotic liver, (2) to investigate the relation between COX-2 expression, miR-21 expression and angiogenic factors in these tissues and (3) to investigate the association between miR-16 and miR-101 and COX-2 expression.

Methods

Tissue samples of HCC and adjacent liver parenchyma of 21 noncirrhotic livers and 20 cirrhotic livers were analyzed for COX-2 expression at the mRNA level (qRT-PCR) and at the protein level by Western blot and immunohistochemistry. Gene expression of VEGFA, VEGFR1, VEGFR2, Ang-1, Ang-2 and Tie-2 were correlated with COX-2 levels. miR-16, miR-21 and miR-101 gene expression levels were quantified in HCC tumor tissue.

Results

COX-2 mRNA and protein levels were lower in HCC as compared to adjacent liver parenchyma both in cirrhotic and noncirrhotic liver. COX-2 protein localized mainly in vascular and sinusoidal endothelial cells and in Kupffer cells. At the mRNA level but not at the protein level, COX-2 correlated with mRNA levels of angiogenic factors VEGFR1, Ang-1, and Tie2. miR-21 expression was higher in cirrhotic tissues versus noncirrhotic tissues. MiR-101 expression was lower in cirrhotic versus noncirrhotic adjacent liver parenchyma. None of the miRNAs correlelated with COX-2 expression. miR-21 correlated negatively with Tie-2 receptor in adjacent liver parenchyma.

Conclusions

In human HCC, COX-2 mRNA but not COX-2 protein levels are associated with expression levels of angiogenic factors. MiR-21 levels are not associated with angiogenic molecules. MiR-16 and miR-101 levels do not correlate with COX-2 mRNA and protein levels.     

Female mice carrying a defective Alox15 gene are protected from experimental colitis via sustained maintenance of the intestinal epithelial barrier function

Lipoxygenases (ALOXs) are involved in the regulation of cellular redox homeostasis. They also have been implicated in the biosynthesis of pro- and anti-inflammatory lipid mediators and play a role in the pathogenesis of inflammatory diseases, which constitute a major health challenge owing to increasing incidence and prevalence in all industrialized countries around the world. To explore the pathophysiological role of Alox15 (leukocyte-type 12-LOX) in mouse experimental colitis we tested the impact of systemic inactivation of the Alox15 gene on the extent of dextrane sulfate sodium (DSS) colitis. We found that in wildtype mice expression of the Alox15 gene was augmented during DSS-colitis while expression of other Alox genes (Alox5, Alox15b) was hardly altered. Systemic Alox15 (leukocyte-type 12-LOX) deficiency induced less severe colitis symptoms and suppressed in vivo formation of 12-hydroxyeicosatetraenoic acid (12-HETE), the major Alox15 (leukocyte-type 12-LOX) product in mice. These alterations were paralleled by reduced expression of pro-inflammatory gene products, by sustained expression of the zonula occludens protein 1 (ZO-1) and by a less impaired intestinal epithelial barrier function. These results are consistent with in vitro incubations of colon epithelial cells, in which addition of 12S-HETE compromised enantioselectively transepithelial electric resistance. Consistent with these data transgenic overexpression of human ALOX15 intensified the inflammatory symptoms. In summary, our results indicate that systemic Alox15 (leukocyte-type 12-LOX) deficiency protects mice from DSS-colitis. Since exogenous 12-HETE compromises the expression of the tight junction protein ZO-1 the protective effect has been related to a less pronounced impairment of the intestinal epithelial barrier function.