Genetics of metabolic variations between Yersinia pestis biovars and the proposal of a new biovar, microtus

Yersinia pestis has been historically divided into three biovars: antiqua, mediaevalis, and orientalis. On the basis of this study, strains from Microtus-related plague foci are proposed to constitute a new biovar, microtus. Based on the ability to ferment glycerol and arabinose and to reduce nitrate, Y. pestis strains can be assigned to one of four biovars: antiqua (glycerol positive, arabinose positive, and nitrate positive), mediaevalis (glycerol positive, arabinose positive, and nitrate negative), orientalis (glycerol negative, arabinose positive, and nitrate positive), and microtus (glycerol positive, arabinose negative, and nitrate negative). A 93-bp in-frame deletion in glpD gene results in the glycerol-negative characteristic of biovar orientalis strains. Two kinds of point mutations in the napA gene may cause the nitrate reduction-negative characteristic in biovars mediaevalis and microtus, respectively. A 122-bp frameshift deletion in the araC gene may lead to the arabinose-negative phenotype of biovar microtus strains. Biovar microtus strains have a unique genomic profile of gene loss and pseudogene distribution, which most likely accounts for the human attenuation of this new biovar. Focused, hypothesis-based investigations on these specific genes will help delineate the determinants that enable this deadly pathogen to be virulent to humans and give insight into the evolution of Y. pestis and plague pathogenesis. Moreover, there may be the implications for development of biovar microtus strains as a potential vaccine.     

Analysis of FAK-associated signaling pathways in the regulation of cell cycle progression

Focal adhesion kinase (FAK) is an important mediator of signal transduction pathways initiated by integrins in cell migration, survival and cell cycle regulation. The ability of FAK to mediate integrin signaling in the regulation of cell cycle progression depends on the phosphorylation of Tyr397, which implies a functional significance for the formation of FAK signaling complexes with Src, phosphatidylinositol-3-kinase (PI3K) and Grb7. We have previously described a FAK mutant, D395A, that selectively disrupts FAK binding to PI3K, but allows FAK association with Src. Using this mutation in a mislocalized FAK mutant background, we show here that formation of a FAK/PI3K complex is not sufficient for cell cycle progression but the formation of a FAK/Src complex plays an essential role. We also show that mutation of D395 to A disrupted FAK association with Grb7. This suggests that a FAK/Grb7 complex is not involved in the cell cycle regulation either, which is supported by direct analysis of cells expressing a dominant negative Grb7 construct. Finally, we provide evidence that the Src-dependent association of FAK with Grb2 and p130(Cas) are both required for the regulation of cell cycle progression by FAK. Together, these studies identify important FAK downstream signaling pathways in cell cycle regulation.     

Microbial Ecology and Association of Bacillus thuringiensis in Chicken Feces Originating from Feed

To explain the association of Bacillus thuringiensis (Bt) with animal feces, an ecological analysis in chickens was conducted by introducing a cry ^? strain marked by production of green fluorescent protein (GFP). After feeding with the tagged Bt strains, the feces of the tested chickens were collected at different times, isolated, and the morphology of Bt was observed. It was shown that Bt strain HD-73GFP in spore form could be isolated from feces of chickens for a period of 13 d, and then it disappeared thereafter. Bt could be detected only up to day 4 (but not thereafter), when chickens were fed with vegetative cells of HD-73GFP. To confirm the source of newly isolated strains, the gfp gene was examined by polymerase chain reaction (PCR), which showed that all the isolated strains harbored the marker gene. Recent data from isolation and PCR had suggested that fecal Bt strains had originated from food. Chicken tissues were thus dissected to isolate Bt strains and to investigate whether Bt could be located in vivo. Bt was located within the duodenum in spore form. Compared to the morphology of the isolated strains at different growth times, the growth rates of all the tested Bt had little changes when passing through the digestive system to the feces. Dissection of the chickens confirmed that Bt was safe for the tested animal.     

Sirtuin 5 regulates the proliferation,invasion and migration of prostate cancer cells through acetyl‐CoA acetyltransferase 1

Sirtuin 5 (SIRT5) is a NAD⁺‐dependent class III protein deacetylase, and its role in prostate cancer has not yet been reported. Therefore, to explore the diagnosis and treatment of prostate cancer, we investigated the effect of SIRT5 on prostate cancer. Sirtuin 5 was assessed by immunohistochemistry in 57 normal and cancerous prostate tissues. We found that the tissue expression levels of SIRT5 in patients with Gleason scores ≥7 were significantly different from those in patients with Gleason scores <7 (P < .05, R > 0). Further, mass spectrometry and pathway screening experiments showed that SIRT5 regulated the activity of the mitogen‐activated protein kinase (MAPK) pathway, which in turn modulated the expression of MMP9 and cyclin D1. Being a substrate of SIRT5, acetyl‐CoA acetyltransferase 1 (ACAT1) was regulated by SIRT5. SIRT5 also regulated MAPK pathway activity through ACAT1. These results revealed that SIRT5 promoted the activity of the MAPK pathway through ACAT1, increasing the ability of prostate cancer cells to proliferate, migrate and invade. Overall, these results indicate that SIRT5 expression is closely associated with prostate cancer progression. Understanding the underlying mechanism may provide new targets and methods for the diagnosis and treatment of the disease.     

Screening of rice cultivars for Cr-stress response by using the parameters of seed germination,morpho-physiological and antioxidant analysis

Rice is the most important crop for the majority of population across the world with sensitive behavior toward heavy metals such as chromium (Cr) in polluted regions. Although, there is no information on the Cr resistance phenotyping in rice. Herein, two different groups of rice cultivars (normal, and hybrid) were used, each group with 14 different rice cultivars. Firstly, seed germination analysis was conducted by evaluating various seed germination indices to identify the rice cultivars with greatest seed germination vigor. Furthermore, exposure of chromium (Cr) toxicity to 28 different rice varieties (NV1-NV14, HV1-HV14) caused noticeable plant biomass reduction. Subsequently, NV2, NV6, NV10, NV12, NV13 (normal type), HV1, HV4, HV8, and HV9 (hybrid types) were pragmatic as moderately sensitive varieties, while NV3, NV4, NV9, and NV14 (normal type), HV3, HV6, HV7, and HV13 were observed as moderately tolerant. Although, NV7, and HV10 were ranked most sensitive cultivars, and NV11, and HV14 were considered as most tolerant varieties as compared to the other rice (both groups) genotypes. Afterward, Cr induced reduction in chlorophyll pigments were significantly lesser in HV14 relative to NV11, NV7, and especially HV10, and as a result HV14 modulated the total soluble sugar level as well as reduced ROS accumulation, and MDA contents production by stimulating the antioxidant defense mechanism conspicuously which further reduced the electrolyte leakage as well. Our outcomes provide support to explore the Cr tolerance mechanism in cereal crops as well as knowledge about rice breeding with increased tolerance against Cr stress.     

By-Products of Zea mays L.: A Promising Source of Medicinal Properties with Phytochemistry and Pharmacological Activities: A Comprehensive Review

Zea mays (Z. mays) is one of the main cereal crops in the world, and it′s by-products have exhibited medicinal properties to explore. This article intends to review the chemical compositions and pharmacological activities of by-products of Z. mays (corn silks, roots, bract, stems, bran, and leaves) which support the therapeutic potential in the treatment of different diseases, with emphasis on the natural occurring compounds and detailed pharmacological developments. Based on this review, 231 natural compounds are presented. Among them, flavonoids, terpenes, phenylpropanoids, and alkaloids are the most frequently reported. The by-products of Z. mays possess diuretic effects, hepatoprotective, anti-diabetic, antioxidant, neuroprotective, anti-inflammatory, anti-cancer, plant protection activity, and other activities. This article reviewed the phytochemistry and pharmacological activities of Z. mays for comprehensive quality control and the safety and effectiveness to enhance future application.     

Directed neural differentiation of duck embryonic germ cells

Although the avian primordial germ cells (PGCs) have been used to produce transgenic birds, their characteristics largely remain unknown. The isolation, culture, biological characterization, and directed neural differentiation of duck EG cells were assayed in this study. The Results showed that the EG cells were got by isolating embryonic gonad and surrounding tissue from 7-day-old duck embryo. The PGCs co-cultured with their gonadal somatic cells were well grown. After passaging, the EG cells were incubated in medium with cytokines and Mitomycin C on inactivated duck embryonic fibroblasts (DEFs) feeder layers. After several passages, alkaline phosphatase (ALP) and periodic acid-Schiff (PAS) resulted positive, cellular markers detection positive for SSEA-1, SSEA-4, TRA-1-60, and TRA-1-81. Karyotype analysis showed the EG cells kept diploid condition and the hereditary feature was stable in accordance with varietal characteristics of duck. These cells grew continuously for 11 passages on DEFs. Under induction of medium with BME, RA, and IBMX, the EG cells lost undifferentiated state, large amount of neural cells appeared with the formation of neural cells networks. Special Nissl body was found by toluidine blue stain after induced for 7 days. Immunofluorescence staining results indicated that differentiated EG cells expressed Nestin, NSE, and GFAP positive. The expression of Nestin, NSE, and GFAP mRNA were positive by RT-PCR. The results revealed that RA can obviously promote the directed differentiation of duck EG cells into neural lineage. The duck EG cells will be useful for the production of transgenic birds, for cell replacement therapy and for studies of germ cell differentiation.     

On-line heat flux measurements improve the culture medium for the growth and productivity of genetically engineered CHO cells

With the increasingly competitive commercial production of target proteins by hybridoma and genetically engineered cells, there is an urgent requirement for biosensors to monitor and control on-line and in real time the growth of cultured cells. Since growth is accompanied by an enthalpy change, heat dissipation measured by calorimetry could act as an index for metabolic flow rate. Recombinant CHO cell suspensions producing interferon-γ were pumped to an on-line flow calorimeter. The results showed that an early reflection of metabolic change is size-specific heat flux obtained from dividing heat flow rate by the capacitance change of the cell suspension, using the on-line probe of a dielectric spectroscope. Comparison of heat flux with glucose and glutamine fluxes indicated that the former most accurately reflected decreased metabolic activity. Possibly this was due to accumulation of lactate and ammonia resulting from catabolic substrates being used as biosynthetic precursors. Thus, the heat flux probe is an ideal on-line biosensor for fed-batch culture. A stoichiometric growth reaction was formulated and data for material and heat fluxes incorporated into it. This showed that cell demand for glucose and glutamine was in the stoichiometric ratio of ∼3:1 rather than the ∼5:1 in the medium. It was demonstrated that the set of stoichiometric coefficients in the reaction were related through the extent of reaction (advancement) to overall metabolic activity (flux). The fact that this approach can be used for medium optimisation is the basis for an amino-acid-enriched medium which improved cell growth while decreasing catabolic fluxes. This revised version was published online in July 2006 with corrections to the Cover Date.