Numerical dominance and phylotype diversity of marine Rhodobacter species during early colonization of submerged surfaces in coastal marine waters as determined by 16S ribosomal DNA sequence analysis and fluorescence in situ hybridization

Early stages of surface colonization in coastal marine waters appear to be dominated by the marine Rhodobacter group of the alpha subdivision of the division Proteobacteria (alpha-Proteobacteria). However, the quantitative contribution of this group to primary surface colonization has not been determined. In this study, glass microscope slides were incubated in a salt marsh tidal creek for 3 or 6 days. Colonizing bacteria on the slides were examined by fluorescence in situ hybridization by employing DNA probes targeting 16S or 23S rRNA to identify specific phylogenetic groups. Confocal laser scanning microscopy was then used to quantify and track the dynamics of bacterial primary colonists during the early stages of surface colonization and growth. More than 60% of the surface-colonizing bacteria detectable by fluorescence staining (Yo-Pro-1) could also be detected with the Bacteria domain probe EUB338. Archaea were not detected on the surfaces and did not appear to participate in surface colonization. Of the three subdivisions of the Proteobacteria examined, the alpha-Proteobacteria were the most abundant surface-colonizing organisms. More than 28% of the total bacterial cells and more than 40% of the cells detected by EUB338 on the surfaces were affiliated with the marine Rhodobacter group. Bacterial abundance increased significantly on the surfaces during short-term incubation, mainly due to the growth of the marine Rhodobacter group organisms. These results demonstrated the quantitative importance of the marine Rhodobacter group in colonization of surfaces in salt marsh waters and confirmed that at least during the early stages of colonization, this group dominated the surface-colonizing bacterial assemblage.     

CD26: an expanding role in immune regulation and cancer

In this review, we highlight major aspects of the biology of CD26, a dipeptidyl peptidase IV (DPPIV)-containing surface glycoprotein with multiple functions. In particular, we discuss findings demonstrating that CD26/DPPIV has an essential role in immune regulation as a T cell activation molecule and a regulator of chemokine function. We also review recent studies that identify key cellular molecules that physically associate with CD26 and the potential consequences of their interaction, including those with clinically-related implications. Furthermore, we present work suggesting a role for CD26 in the pathogenesis and behavior of selected human cancers, both solid tumors and hematological malignancies. We present recent studies that investigate the potential role of CD26 as a molecular target for novel treatment modalities for T cell lymphoid malignancies and possibly other hematological malignancies, with work involving the use of anti-CD26 monoclonal antibody, CD26-transfected cells as well as soluble CD26 molecules.     

Variation in mitochondrial DNA of Vietnamese pigs: relationships with Asian domestic pigs and Ryukyu wild boars

Mitochondrial DNA (mtDNA) sequences (574 bp) of 30 Vietnamese pigs (large and small) were examined and compared with those of 61 haplotypes from wild boars and domestic pigs from various locations in Asia. The large Vietnamese pigs had genetic links to Ryukyu wild boars in southern Japan. The small Vietnamese pigs were closely related to other East Asian domestic pigs. These results indicate that Vietnamese pigs are genetically diverse and may be descendents of wild and domestic pigs from other regions of Asia.     

Thelephantins D-H: five p-terphenyl derivatives from the inedible mushroom Thelephora aurantiotincta

Five p-terphenyl derivatives named thelephantins D-H (1-5) together with nine known compounds, thelephantins A-C (6-8), ganbajunin E (9), p-hydroxylbenzoic acid (10), ganbajunin C (11), thelephorin A (12), 2-O-methylatromentin (13) and atromentin (14), were isolated from the methanolic extract of fruit bodies of the Thelephoraceous Basidiomycete Thelephora aurantiotincta. Their structures were elucidated by high-resolution MS, 2D NMR, IR and UV spectroscopic analysis.     

A Robertsonian translocation, rob(2;28), found in Vietnamese cattle

A new Robertsonian translocation, rob(2;28), was discovered in a local population of the Vietnamese Cattle. The animal (2n = 59, XY) was found by Q- and R-banding to be a heterozygous carrier of a centric fusion translocation involving chromosomes 2 and 28. FISH analysis using a bovine satellite I DNA probe demonstrated that the centromeric heterochromatin block of the rob(2;28) chromosome become much smaller than its ancestors suggesting a monocentric nature of this centric fusion. This is the first report identifying a Robertsonian translocation in Southeast Asian cattle by karyotyping of banded chromosomes.     

G-protein signaling abnormalities mediated by CD95 in salivary epithelial cells

Salivary epithelial cells from patients with primary Sj?gren's syndrome (SS) undergo Fas-mediated apoptosis. Bcl-2 and Bcl-xL are apoptosis suppressing oncogenes. Very little is known about the role of these oncogene molecules in salivary epithelial cells. To investigate the possible prevention of salivary glandular destruction in SS by Bcl-2 and Bcl-xL, stable transfectants expressing these molecules were made from HSY cells, a human salivary epithelial cell line. HSY cells were transfected with an expression vector for human Bcl-2 or Bcl-xL. Stable transfectants were selected and apoptosis was induced by anti-Fas antibody. Apoptosis was quantified by propidium iodide staining followed by flow cytometry. Caspase activity was detected by immunohistochemical analysis and enzyme cleavage of DEVD-AMC, a fluorescent substrate. Response to carbachol, a muscarinic receptor agonist, and EGF was measured by Ca2+ mobilization and influx. Fas-mediated apoptosis was significantly inhibited in Bcl-2 and Bcl-xL transfectants compared to wild-type and control transfectants (empty vector). Surprisingly, caspase activity was not inhibited in Bcl-2 and Bcl-xL transfectants. Activation of the Fas pathway in the Bcl-2 and Bcl-xL transfectants by antibody also inhibited carbachol and EGF responsiveness (i.e., Ca2+ mobilization and/or influx) by 50-60%. This Fas-mediated inhibition of cell activation was partially or completely restored by specific peptide interference of caspase enzyme activity. The prevention of Fas-mediated apoptosis by the overexpression of Bcl-2 and Bcl-xL in salivary gland epithelial cells results in injured cells expressing caspase activity and unable to respond normally to receptor agonists. Such damaged cells may exist in SS patients and could explain the severe dryness out of proportion to the actual number of apoptotic cells seen on salivary gland biopsy.     

The EGFR/ErbB3 Pathway Acts as a Compensatory Survival Mechanism upon c-Met Inhibition in Human c-Met+ Hepatocellular Carcinoma

Backgroundc-Met, a high-affinity receptor for Hepatocyte Growth Factor (HGF), plays a critical role in tumor growth, invasion, and metastasis. Hepatocellular carcinoma (HCC) patients with activated HGF/c-Met signaling have a significantly worse prognosis. Targeted therapies using c-Met tyrosine kinase inhibitors are currently in clinical trials for HCC, although receptor tyrosine kinase inhibition in other cancers has demonstrated early success. Unfortunately, therapeutic effect is frequently not durable due to acquired resistance.MethodsWe utilized the human MHCC97-H c-Met positive (c-Met⁺) HCC cell line to explore the compensatory survival mechanisms that are acquired after c-Met inhibition. MHCC97-H cells with stable c-Met knockdown (MHCC97-H c-Met KD cells) were generated using a c-Met shRNA vector with puromycin selection and stably transfected scrambled shRNA as a control. Gene expression profiling was conducted, and protein expression was analyzed to characterize MHCC97-H cells after blockade of the c-Met oncogene. A high-throughput siRNA screen was performed to find putative compensatory survival proteins, which could drive HCC growth in the absence of c-Met. Findings from this screen were validated through subsequent analyses.ResultsWe have previously demonstrated that treatment of MHCC97-H cells with a c-Met inhibitor, PHA665752, results in stasis of tumor growth in vivo. MHCC97-H c-Met KD cells demonstrate slower growth kinetics, similar to c-Met inhibitor treated tumors. Using gene expression profiling and siRNA screening against 873 kinases and phosphatases, we identified ErbB3 and TGF-α as compensatory survival factors that are upregulated after c-Met inhibition. Suppressing these factors in c-Met KD MHCC97-H cells suppresses tumor growth in vitro. In addition, we found that the PI3K/Akt signaling pathway serves as a negative feedback signal responsible for the ErbB3 upregulation after c-Met inhibition. Furthermore, in vitro studies demonstrate that combination therapy with PHA665752 and Gefitinib (an EGFR inhibitor) significantly reduced cell viability and increased apoptosis compared with either PHA665752 or Gefitinib treatment alone.Conclusionc-Met inhibition monotherapy is not sufficient to eliminate c-Met⁺ HCC tumor growth. Inhibition of both c-Met and EGFR oncogenic pathways provides superior suppression of HCC tumor growth. Thus, combination of c-Met and EGFR inhibition may represent a superior therapeutic regimen for c-Met⁺ HCC.