Analysis of bacterial populations in a grassland soil according to rates of development on solid media

Abstract The process of colony formation by bacteria from grassland soil sampled in April, July and September was simulated by a colony-forming curve (CFC). The CFC was a super-imposition of several component curves (cCFC) given theoretically by the first order reaction (FOR) model [3,6]. The pattern of FOR model curves was not influenced by the time of sampling and four cCFCs were always recognized during an incubation period of 160 h. It was considered that the CFC describes an inherent property of the bacterial population of the field. Bacterial isolates were obtained from colonies produced in each of four cCFCs on agar plates. Isolates corresponding to one cCFC were classified as one group. The bacterial isolates were characterized by morphological and physiological tests and subsequently clustered. Few oligotrophic bacteria were obtained among bacteria which produced visible colonies within 63 h of incubation time. On the other hand, approx. 50% of bacteria which produced v colonies after 63 h were oligotrophic bacteria. The time required for the appearance of the first colony, t _r of the FOR model, was very similar in the isolates belonging to one group. A close linear relationship was observed between t _r value and doubling time of isolates.     

γ-Irradiation induces P2X7 receptor-dependent ATP release from B16 melanoma cells

Background

Ionizing irradiation causes not only growth arrest and cell death, but also release of growth factors or signal transmitters, which promote cancer malignancy. Extracellular ATP controls cancer growth through activation of purinoceptors. However, there is no report of radiation-induced ATP release from cancer cells. Here, we examined γ-irradiation-induced ATP release and its mechanism in B16 melanoma.

Methods

Extracellular ATP was measured by luciferin–luciferase assay. To investigate mechanism of radiation-induced ATP release, we pharmacologically inhibited the ATP release and established stable P2X₇ receptor-knockdown B16 melanoma cells using two short hairpin RNAs targeting P2X₇ receptor.

Results

Cells were exposed to 0.5–8 Gy of γ-rays. Extracellular ATP was increased, peaking at 5 min after 0.5 Gy irradiation. A selective P2X₇ receptor channel antagonist, but not anion transporter inhibitors, blocked the release of ATP. Further, radiation-induced ATP release was significantly decreased in P2X₇ receptor-knockdown cells. Our results indicate that γ-irradiation evokes ATP release from melanoma cells, and P2X₇ receptor channel plays a significant role in mediating the ATP release.

General Significance

We suggest that extracellular ATP could be a novel intercellular signaling molecule released from cancer cells when cells are exposed to ionizing radiation.     

Endothelin regulates neural crest deployment and fate to form great vessels through Dlx5/Dlx6-independent mechanisms

Endothelin-1 (Edn1), originally identified as a vasoconstrictor peptide, is involved in the development of cranial/cardiac neural crest-derived tissues and organs. In craniofacial development, Edn1 binds to Endothelin type-A receptor (Ednra) to induce homeobox genes Dlx5/Dlx6 and determines the mandibular identity in the first pharyngeal arch. However, it remains unsolved whether this pathway is also critical for pharyngeal arch artery development to form thoracic arteries. Here, we show that the Edn1/Ednra signaling is involved in pharyngeal artery development by controlling the fate of neural crest cells through a Dlx5/Dlx6-independent mechanism. Edn1 and Ednra knock-out mice demonstrate abnormalities in pharyngeal arch artery patterning, which include persistent first and second pharyngeal arteries, resulting in additional branches from common carotid arteries. Neural crest cell labeling with Wnt1-Cre transgene and immunostaining for smooth muscle cell markers revealed that neural crest cells abnormally differentiate into smooth muscle cells at the first and second pharyngeal arteries of Ednra knock-out embryos. By contrast, Dlx5/Dlx6 knockout little affect the development of pharyngeal arch arteries and coronary arteries, the latter of which is also contributed by neural crest cells through an Edn-dependent mechanism. These findings indicate that the Edn1/Ednra signaling regulates neural crest differentiation to ensure the proper patterning of pharyngeal arch arteries, which is independent of the regional identification of the pharyngeal arches along the dorsoventral axis mediated by Dlx5/Dlx6.     

Effect of amines as activators on the alcohol-oxidizing activity of pyrroloquinoline quinone-dependent quinoprotein alcohol dehydrogenase

Pyrroloquinoline quinone-dependent quinoprotein alcohol dehydrogenases (PQQ-ADH) require ammonia or primary amines as activators in in vitro assays with artificial electron acceptors. We found that PQQ-ADH from Pseudomonas putida KT2440 (PpADH) was activated by various primary amines, di-methylamine, and tri-methylamine. The alcohol oxidation activity of PpADH was strongly enhanced and the affinity for substrates was also improved by pentylamine as an activator.     

Nematocidal activity of 6-O-octanoyl- and 6-O-octyl-d-allose against larvae of Caenorhabditis elegans

ABSTRACT

The nematocidal activities of the fatty acid esters of d-allose were examined using the larvae of C. elegans. Among the fatty acid esters, 6-O-octanoyl-d-allose (3) showed significant activity. 6-O-octanoyl-d-glucose (5) showed no activity, indicating that the D-allose moiety is essential for the nematocidal activity of 3. A nonhydrolyzable alkoxy analog 6-O-octyl-d-allose (6) also showed activity equivalent to that of 3.     

Plasma B-type Natriuretic Peptide as a Predictor of Cardiovascular Events in Subjects with Atrial Fibrillation: A Community-Based Study

Objectives

Atrial fibrillation (AF) is a significant public health issue due to its high prevalence in the general population, and is associated with an increased risk of cardiovascular (CV) events including systemic thrombo-embolism, heart failure, and coronary artery disease. The relationship between plasma B-type natriuretic peptide (BNP) and CV risk in real world AF subjects remains unknown.

Methods

The subject of the study (n = 228; mean age = 69 years) was unselected individuals with AF in a community-based population (n = 15,394; AF prevalence rate = 1.5%). The CV event free rate within each BNP tertile was estimated, and Cox regression analysis was performed to examine the relative risk of the onset of CV events among the tertiles. The prognostic ability of BNP was compared to an established risk score for embolic events (CHADS2 score). In addition, to determine the usefulness of BNP as a predictor in addition to CHADS2 score, we calculated Net Reclassification Improvement (NRI) and Integrated Discrimination Improvement (IDI) indices.

Results

During the follow-up period 58 subjects experienced CV events (52 per 1,000 person-years). The event-free ratio was significantly lower in the highest tertile (p < 0.02). After adjustment for established CV risk factors, the hazard ratio (HR) of the highest tertile was significantly higher than that of the lowest tertile (HR = 2.38; p < 0.02). The predictive abilities of plasma BNP in terms of sensitivity and specificity for general CV events were comparable to those of CHADS2 score. Adding BNP to the CHADS2 score only model improved the NRI (0.319; p < 0.05) and the IDI (0.046; p < 0.05).

Conclusion

Plasma BNP is a valuable biomarker both singly or in combination with an established scoring system for assessing general CV risk including stroke, heart failure and acute coronary syndrome in real-world AF subjects.     

Evidence for Finely-Regulated Asynchronous Growth of Toxoplasma gondii Cysts Based on Data-Driven Model Selection

Toxoplasma gondii establishes a chronic infection by forming cysts preferentially in the brain. This chronic infection is one of the most common parasitic infections in humans and can be reactivated to develop life-threatening toxoplasmic encephalitis in immunocompromised patients. Host-pathogen interactions during the chronic infection include growth of the cysts and their removal by both natural rupture and elimination by the immune system. Analyzing these interactions is important for understanding the pathogenesis of this common infection. We developed a differential equation framework of cyst growth and employed Akaike Information Criteria (AIC) to determine the growth and removal functions that best describe the distribution of cyst sizes measured from the brains of chronically infected mice. The AIC strongly support models in which T. gondii cysts grow at a constant rate such that the per capita growth rate of the parasite is inversely proportional to the number of parasites within a cyst, suggesting finely-regulated asynchronous replication of the parasites. Our analyses were also able to reject the models where cyst removal rate increases linearly or quadratically in association with increase in cyst size. The modeling and analysis framework may provide a useful tool for understanding the pathogenesis of infections with other cyst producing parasites.     

Vasohibin-2 expressed in human serous ovarian adenocarcinoma accelerates tumor growth by promoting angiogenesis

Vasohibin-1 (VASH1) is a VEGF-inducible endothelium-derived angiogenesis inhibitor and VASH2 is its homolog. Our previous analysis revealed that VASH1 is expressed in endothelial cells to terminate angiogenesis, whereas VASH2 is expressed in infiltrating mononuclear cells mobilized from bone marrow to promote angiogenesis in a mouse model of hypoxia-induced subcutaneous angiogenesis. To test the possible involvement of VASH2 in the tumor, we examined human ovarian cancer cells for the presence of VASH2. Immunohistochemical analysis revealed that VASH2 protein was preferentially detected in cancer cells of serous ovarian adenocarcinoma. We then used SKOV-3 and DISS, two representative human serous adenocarcinoma cell lines, and examined the role of VASH2 in the tumor. The knockdown of VASH2 showed little effect on the proliferation of cancer cells in vitro but notably inhibited tumor growth, peritoneal dissemination, and tumor angiogenesis in a murine xenograft model. Next, we stably transfected the human VASH2 gene into two types of murine tumor cells, EL-4 and MLTC-1, in which endogenous VASH2 was absent. When either EL-4 or MLTC-1 cells were inoculated into VASH2 (-/-) mice, the VASH2 transfectants formed bigger tumors when compared with the controls, and the tumor microvessel density was significantly increased. VASH2 stimulated the migration of endothelial cells, and its increased expression in cancer cells is related to the decrease of mir-200b. These results indicate that VASH2 expressed in serous ovarian carcinoma cells promoted tumor growth and peritoneal dissemination by promoting angiogenesis. Mol Cancer Res; 10(9); 1135-46. ?2012 AACR.     

Measurement of individual cell strength of <Emphasis Type="Italic">Botryococcus braunii</Emphasis> in cell culture

Botryococcus braunii is a microalga considered for biofuel production and may require physical disruption of cells/colonies for efficient hydrocarbon extraction. In this study, the strength of individual cells of B. braunii was measured using a nanoindenter. From the load and cell size, the pressure for bursting the cell was calculated to be 56.9 MPa. This value is 2.3–10 times those of Saccharomyces cerevisiae and Chlorella vulgaris found in another research, because B. braunii has two types of cell walls with different thicknesses. The energy required to disrupt 1 g of dry B. braunii cells, estimated by load-displacement curves, is 3.19 J g^?1 which is 0.19–1.2 times higher than those of S. cerevisiae and C. vulgaris. When using a high-pressure homogenizer for disrupting B. braunii cells, the cell disruption degree increased with the treatment pressure at above 30 MPa, and 70% of cells were disrupted at 80 MPa.