Effects of prometryn and acetochlor on arbuscular mycorrhizal fungi and symbiotic system

Prometryn and acetochlor are common herbicides widely used to control weeds in agricultural systems. The impacts of the two herbicides on spore germination, hyphal elongation, the biomass and malondialdehyde content of carrot hairy roots were investigated using a strict in vitro cultivation system associating the Ri T-DNA-transferred carrot hairy roots with Glomus etunicatum. Alternatively, root colonization, daughter spore production and the proportion of hyphae with succinate dehydrogenase (SDH) and alkaline phosphatase (ALP) activities were also investigated. No significant impact on spore germination was noted in the presence of acetochlor at all three concentrations tested, while a significant decrease was observed with prometryn only at the highest concentration. Moreover, an inverse correlation was identified between herbicides concentrations and G. etunicatum root colonization and spore production as well as hyphal SDH and ALP activity, with a positive correlation identified among these four factors. Both herbicides exerted negative effects on the arbuscular mycorrhizal (AM) fungus and symbiosis at increasing concentrations, with prometryn apparently more toxic than acetochlor. Furthermore, the AM symbiotic system was shown to improve biomass, reduce malondialdehyde accumulation and ease lipid peroxidation in carrot hairy roots and decrease damage in host plants, thus enhancing plant tolerance to adverse conditions.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, the effect of prometryn and acetochlor on the physiology and metabolic activities of the AM fungus Glomus etunicatum were investigated. Our findings demonstrate for the first time, the impact of the two herbicides at three concentrations (0.1, 1 and 10 mg l(-1)) on transformed carrot hairy roots/AM fungus association under strict in vitro culture conditions, which may guide the application of the two herbicides in modern agriculture.

Thermosensitive polymeric hydrogels as drug delivery systems

Thermosensitive hydrogels are very important biomaterials used in drug delivery systems (DDSs), which gained increasing attention of researchers. Thermosensitive hydrogels have great potential in various applications, such as drug delivery, cell encapsulation, tissue engineering, and etc. Especially, injectable thermosensitive hydrogels with lower sol-gel transition temperature around physiological temperature have been extensively studied. By in vivo injection, the hydrogels formed non-flowing gel at body temperature. Upon incorporation of pharmaceutical agents, the hydrogel systems could act as sustained drug release depot in situ. Injectable thermosensitive hydrogel systems have a number of advantages, including simplicity of drug formulation, protective environment for drugs, prolonged and localized drug delivery, and ease of application. The objective of this review is to summarize fundamentals, applications, and recent advances of injectable thermosensitive hydrogel as DDSs, including chitosan and related derivatives, poly(N-isopropylacrylamide)-based (PNIPAAM) copolymers, poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) copolymers and its derivatives, and poly(ethylene glycol)/ biodegradable polyester copolymers.

Laser-driven shock acceleration of monoenergetic ion beams

We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate ~200 MeV proton beams with state-of-the-art 100 TW class laser systems.

Beclin 1 and autophagy are required for the tumorigenicity of breast cancer stem-like/progenitor cells

Malignant breast tissue contains a rare population of multi-potent cells with the capacity to self-renew; these cells are known as cancer stem-like cells (CSCs) or tumor-initiating cells. Primitive mammary CSCs/progenitor cells can be propagated in culture as floating spherical colonies termed ‘mammospheres'. We show here that the expression of the autophagy protein Beclin 1 is higher in mammospheres established from human breast cancers or breast cancer cell lines (MCF-7 and BT474) than in the parental adherent cells. As a result, autophagic flux is more robust in mammospheres. We observed that basal and starvation-induced autophagy flux is also higher in aldehyde dehydrogenase 1-positive (ALDH1⁺) population derived from mammospheres than in the bulk population. Beclin 1 is critical for CSC maintenance and tumor development in nude mice, whereas its expression limits the development of tumors not enriched with breast CSCs/progenitor cells. We found that decreased survival in autophagy-deficient cells (MCF-7 Atg7 knockdown cells) during detachment does not contribute to an ultimate deficiency in mammosphere formation. This study demonstrates that a prosurvival autophagic pathway is critical for CSC maintenance, and that Beclin 1 plays a dual role in tumor development.

Amplification of multi-gigawatt 3 ps pulses in an atmospheric CO2 laser using ac Stark effect

The 3 ps pulses are amplified to ~20 GW peak power in a TEA CO(2) laser using ac Stark broadening. Demonstration of such broadband coherent amplification of 10 μm pulses opens opportunities for a powerful mid-IR source at a high-repetition rate.

Cloning, expression analysis and sequence prediction of the CCAAT/enhancer-binding protein alpha gene of Qinchuan cattle

CCAAT/enhancer-binding protein alpha (C/EBPα) is an essential transcription factor, regulating the differentiation of adipocytes. We cloned the complete open reading frame of C/EBPα gene of Qinchuan cattle and analyzed its protein structures and expression profile in 15 tissues via DNA cloning, sequencing and RT-PCR. Analysis of the putative protein sequences revealed that C/EBPα consists of alpha helices, random coils and a few extended strands. A significant transmembrane structure was observed in amino acid region 233 to 252. A basic leucine zipper domain was also found in amino acid region 277 to 340, which is characteristic of C/EBPs. Homologous comparison with various species indicated that the C/EBPα gene of Qinchuan cattle shares 97, 95, 94, 94, and 93% similarity in amino acid sequences with Sus scrofa, Homo sapiens, Rattus norvegicus, Oryctolagus cuniculus, and Mus musculus, respectively, implying strong sequence conservation of C/EBPα during evolution. RT-PCR revealed that the mRNA expression level of bovine C/EBPα gene in subcutaneous fat is much higher than that in the other 14 tissues, and the relative quantity in fat tissue increases with cattle age.

Inhibitory effects of enterococci on the production of hydrogen sulfide by hydrogen sulfide-producing bacteria in raw meat

AIMS

Applying competitive exclusion micro-organisms to control hydrogen sulfide (H₂S) gas produced by hydrogen sulfide-producing bacteria (SPB) in chicken meat.

METHODS AND RESULTS

Five SPB strains, isolated from animal by-products, were used for screening lactic acid bacteria (LAB) that can inhibit the production of H₂S by SPB in trypticase soy broth supplemented with L-cysteine (TSB-L-cys). A sensitive and accurate test strip method was developed for H₂S determination in real time. One LAB strain, isolate L86, from cheese whey, demonstrated the highest inhibitory activity against the production of H₂S by SPB. The isolate L86 was confirmed as Enterococcus faecium that does not possess genes encoding for vancomycin resistance based on PCR analysis. Enterococcus faecium strain L86 reduced (P < 0·05) the yield of H₂S upto 51·2% in 10 h at 35°C in TSB-L-cys medium. In fresh chicken meat, the yield of H₂S produced by the artificially inoculated SPB was reduced (P < 0·05) by 48·6, 49·7 and 69·8% in 10 h at 35, 30 and 25°C, respectively. Enterococcus faecium strain L86 also reduced (P < 0·05) by 53·8% on the yield of H₂S produced by the indigenous SPB in partially spoiled chicken meat at 35°C for 10 h.

CONCLUSIONS

Enterococcus faecium strain L86 is effective on inhibiting the production of H₂S by SPB.

SIGNIFICANCE AND IMPACT OF THE STUDY

The application of this biological agent to raw animal by-products will provide a safer working environment in rendering processing plants and produce higher-quality rendered products.

Let-7 Inverts the Chemoresistance of Breast Tumor-Initiating Cells

Background: Cancers may arise from rare self-renewing highly tumorigenic “stem” cells, which are thought not only to be the source of the tumor, but also to be responsible for resistance to cancer therapy and subsequent tumor recurrence. Our preliminary data strongly suggest that let-7 is a master regulator of BT-IC self-renewal and multipotency. It is likely that let-7 regulates many other genes/pathways during BT-IC differentiation. However, we do not know whether let-7 might also regulate other putative aspects of “stemness” such as chemoresistance.Material and Methods: Quantified qRT-PCR was used to test the expression of let-7a in chemoresistant breast tumor tissue from patients, as well as the chemosensitive samples. The location of let-7a in primary breast cancer samples from patients with chemoresistance were compared to the samples without chemoresistance by in situ hybridization analysis.SK-3rd Cells, which is a cell line enriched in breast tumor-initiating cells, were cultured in suspension to form mammosphere which could be induced to differentiation with adhesive culture. Lentivirus-mediated let-7a transduction was used to increase the expression level of let-7a.Let-7 target gene expression (HRAS and HMGA2) was determined by qRT-PCR and western blot. The response of BT-ICs to chemotherapy was determined by MTT, Annexin V and Tunel.Results: The expression level of let-7a microRNA in chemoresistant patients were significantly lower than the patients without chemoresistance (P&lt;0.05). The let-7a mimics can effectively enhance the expression of let-7a in mammospheric SK-3rd cells, and reduced the expression level of H-RAS and HMGA2 proteins, which are the targets of let-7. Mammospheric SK-3rd cells tranfected with let-7a mimics had a lower proliferation rate and a higher apoptosis rate under epirubicin treatment.Conclusion: Lack of expression of let-7 regulates BT-IC resistance to chemotherapy. Therefore, let-7a may be an effective maker to predict the response of tumor to chemotherapy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1136.

Proportion of Tumor Initiating Cells Contributes to Chemotherapeutic Resistance of Breast Cancers

Background: The mechanisms determining chemotherapeutic resistance of breast cancers are rather complicated with a variety of molecules involved. While targeting one single molecule or one signaling pathway are not sufficient to reverse chemo-resistance. Therefore, it is more important to identify and eliminate the subpopulations of tumor cells that are resistant to chemotherapy. Recently, accumulating evidence demonstrates that a wide variety of malignancies may be driven by a small subset of “tumor-initiating cells (T-ICs) displays a variety of drug-resisting mechanisms. Nevertheless, it remains obscure whether the proportion of breast tumor initiating cells (BT-ICs) correlates with chemotherapeutic sensitivity of breast cancers, and whether targeting BT-ICs may help to reverse chemo-resistance in the malignancy.Material and Methods: Using immunohistochemistry, we tested the expression level of ALDH1 in 192 human breast cancer samples before underwent neoadjuvant chemotherapy and analyzed the relationship between the ALDH1 level and clinical pathological features including clinical response and disease free survival (DFS). We tested the proportion of CD44+/CD24-, ALDH1+ and side population in primary cancer cells, wide type MCF7 and Adriamycin resistant (AdrR) MCF-7 by FACS. Compared the mammosphere formations in suspension culture. We further tested the drug sensitivity after treated with 1UM Lapatinib in AdrR MCF-7 mammospheric cells by MTT and AnnexinV staining. Results: In all 192 cases, there were 19.79% (38 of 192) cases with high ALDH1 expression (&gt;20% positive cancer cells) compared to 80.21% (154 of 192) cases with low expression (≤20% positives cells). The clinical response (PR and cCR) was only 52.63%% (20 of 38) in patients with high ALDH1 expression compared with 81.17% (125 of 154) in patients with low ALDH1 expression (x2=15.926; P=0.000). Patients with low ALDH1expression survived significantly longer than those with high ALDH1 expression (P = 0.006). In primary cancer cells, the percentage of ALDH1+ and CD44+/CD24-cells were up to 8.72% ±3.73% and 36% ±7.9% in the PD samples respectively, whereas only 1.42%±1.63% and 3.17 ±0.45% in PR samples (p=0.037 and 0.018). Moreover, mammosphere formation of primary human breast cancer cells was 10-20 fold higher in PD samples than in PR samples (p=0.01). Then we compared the proportion of BT-ICs between two breast cancer cell lines. The mammoshpere formation rate of the AdrR MCF-7 increased to 9.1%±1.01% compared with 1.03%±0.15% in the parent MCF-7 breast cancer cell (p=0.0046), meanwhile, the percentage of CD44+/CD24- cells was much higher in the AdrR MCF-7 cells(64.85%±1.3% vs than 1.3%±0.1%,p=0.01), the proportion of ALDH1+ cells was 15.9%±1.5% to 2.7%±0.3% (p=0.01),as well as the percentage of side population was 10.8%±1.4% to.0.25%±0.05% (p=0.001).After treated with Lapatinib, the sensitivity of passaged mammospheric AdrR MCF-7 cells to chemotherapy increased in the cell viability assay, while the dead cells increased from 50% ±2.8% to 75%±6.5% tested by FACS under chemotherapy pressure (p=012).Conclusion: Proportion of tumor initiating cells contributes to chemotherapeutic resistance of breast cancers.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 503.

Association of Proliferating Macrophages with High Grade, Hormone Receptor Negative Breast Cancer

Macrophages, a key cell in the inflammatory cascade, have been associated with poor prognosis in cancers, including breast cancer. Tumor associated macrophages (TAM) have also been shown to play a role in invasion and metastases. In this study, we investigated the role of a subset of macrophages known as proliferating macrophages (promacs) in breast cancer. We examined the relationship between promacs and clinico-pathologic characteristics such as tumor size, grade, lymph node metastasis, hormone receptor status, molecular subtype, and survival. This study was conducted at two independent institutions (University of California, San Francisco and University of Chicago) using two independent cohorts of patients with breast cancer. Formalin-fixed, paraffin-embedded sections and/or tissue microarrays were double-stained with anti-CD68 (a macrophage marker) and anti-PCNA (a proliferation marker) antibodies. The number of total macrophages as well as promacs per high power field were counted. Molecular subtypes were determined from gene expression array analyses. Outcomes were available for a subset of the cases and Kaplan Meier survival curves were generated.Tumor tissue from two different cohorts of patients with breast cancer were stained and analyzed at two independent institutions. In both studies, promac density was significantly correlated with higher grade, hormone-receptor negative tumors, and a basal-like subtype. In contrast there was no correlation between numbers of promacs and tumor size, stage, or number of involved lymph nodes. The presence of increased promacs was a significant predictor of survival in these treated patients. Proliferating macrophages are more abundant in high grade tumors, and predict a worse outcome, independent of stage and grade. These findings, corroborated at two independent institutions, suggest that the presence of promacs is associated with tumor progression and increased promac density may serve as a prognostic indicator for poor outcomes. Novel therapies that are able to target and halt the activity of promacs may be a promising strategy for the treatment of promac rich tumors.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3042.

Breast Cancer Initiating Cells Promote Chemoresistance by Pre-Activation of the DNA Damage Repair

Background: Breast tumor initiating cells (BT-ICs) display a variety of drug-resisting mechanisms including overxpression of ATP binding cassette (ABC) transporters and anti-apoptotic molecules. Unfortunately, application of P-glycoprotein inhibitors has not been successful in several clinical trials .Based on the tumor initiating cell concept, an alternative model posits that the T-ICs are naturally resistant to chemotherapy through their quiescence and their capacity for DNA repair. Gaining a better insight into the mechanisms of BT-IC resistance to chemotherapy might therefore lead to new therapeutic targets and better anticancer strategies.Material and Methods: We generated large numbers of BT-IC-enriched cells (SK-3rd) by in vivo passage of breast cancer cells SKBR3 in NOD/SCID mice treated with epirubicin, then enriched BT-ICs again by isolating spherical clusters of self-replicating cells (“mammospheres”) from suspension cultures. Under chemotherapy pressure, compared the apoptosis between BT-IC and non BT-IC by MTT, Annexin V, DNA ladder and hochest 33342 staining, and analyzed the cell cycles by Flow cytometry. We tested the DNA repair capacity after chemo-induced DNA damage between BT-IC and non BT-IC by single cell gel electrophoresis and tested the expression of DNA damage checkpoint protein by immunoblot.Results:SK-3rd formed 40-fold more mammospheres than SKBR3 (16.7%±2.6% vs 0.5%±0.2%; P&lt;0.001). Compared with non BT-IC, BT-IC treated with epirubicin showed more viability as assessed by MTT assay. After treated with 0.3ug/ml Epirubicin for 24 hours, withdrew the drug, and then repaired for 12, 24 hours respectively, analyzed the Annexin V positive cells in BT-IC were less than n non BT-IC(17.27%±2.3% vs 56%±6.7%; P=0.026), hochest staining also showed the similar results.SK-3rd mammospheric cells treated with or without Epirubicin arrested in G0/1 stage. Breast T-IC can repair chemo-induced DNA damage more efficiently than non BT-IC. Treated with or without Epirubicin, Sk-3rd mammospheric cells can pre-activated phosphorylated DNA chk2checkpoint (Thr68),but not in non BT-IC.Dicussion: The discovery of cancer initiating cells in solid tumors has changed our view of carcinogenesis and chemotherapy. In our study, we found that, BT-IC was more resistant than non BT-IC under the same chemotherapy pressure Although initiating cells can self-renew, they are generally quiescent, spending most of their time in G0. BT-IC treated with or without Epirubicin activated DNA checkpoint phosphorylated chk2 and arrested in G0/1 stage, which implied that BT-IC can target itself to arrest in G0/1 stage and pre-active chk2. When treated with DNA damage, BT-IC has enough time and quickly responses to repair damaged DNA, and at last contributes to the failure of chemotherapy. The new insight into the mechanisms of initiating -cell chemoresistance might allow the development of new strategies to improve targeted therapies in breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1121.

Mir-128 Regulates the Self-Renewal of Breast Tumor-Initiating Cells through HTERT

Background: hTERT (human telomerase reverse transcriptase), which maintains telomere ends by addittion of the telomere repeat sequence TTAGGG, is increased in cancer cells and embryonic stem cells. However, whether hTERT has a role in regulating breast tumor-initiating cells remains unknown. Therefore, the regulation of hTERT in breast tumor initiating cells (BT-IC) would potentially facilitate our understanding of the etiology of breast cancer.Material and Methods: Enrichment for BT-ICs was performed by mammospheres from suspension cultures. The capacity of self-renewal and differentiation of BT-ICs were determined by mammosphere formation, immunohistochemical analysis of epithelial markers and FACS, respectively. TRAP assay was used to detect telomerase activity. The expression levels of hTERT in BT-ICs, with or without lentivirus-mediated mir-128 transduction, were determined by qRT-PCR and western blot. hTERT siRNA or lentivirus-shTERT were used to silence the expression of hTERT in BT-ICs. Differentially expressed mir-128 in BT-ICs was quantified by qRT-PCR and Northern Blot. The expression of BMI1 was determined by Western Blot.Results: hTERT, as well as telomerase activity, had a higher expression in BT-ICs, compared to the differentiated breast cancer cells. BMI1, the target of mir-128, is increased in BT-ICs. Conversely, the expression level of mir-128 is lower in BT-ICs, compared to the differentiated cells. Mir-128 over-expressing reduced the level of BMI1,as well as hTERT, in BT-ICs. Silencing BMI1 by lentivirus-shRNA transfection in BT-ICs leads to the decrease of hTERT protein level. Furthermore, BT-ICs, with hTERT knockdown, lost its ability to form mammospheres and proliferated poorly under differentiating conditions.Conclutions: mir-128 miRNA is reduced in mammospheric BT-ICs, resulting in up-regulation of BMI1, which further brought on the up-regulation of hTERT. And hTERT promotes self-renewal and blocks epithelial differentiation of BT-ICs. Therefore, mir-128 regulates BT-IC stem-cell like properties by BMI1 and hTERT.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5157.

Olfactory discrimination deficits in mice lacking the dopamine transporter or the D2 dopamine receptor

Previous pharmacological studies have implicated dopamine as a modulator of olfactory bulb processing. Several disorders characterized by altered dopamine homeostasis in olfaction-related brain regions display olfactory deficits. To further characterize the role of dopamine in olfactory processing, we subjected dopamine transporter knockout mice (DAT -/-) and dopamine receptor 2 knockout mice (D2 -/-) to a battery of olfactory tests. In addition to behavioral characterization, several neurochemical markers of olfactory bulb integrity and function were examined. DAT -/- mice displayed an olfactory discrimination deficit, but did not differ detectably from DAT wildtype (DAT +/+) mice in odor habituation, olfactory sensitivity, or odor recognition memory. Neurochemically, DAT -/- mice have decreased D2 receptor staining in the periglomerular layer of the olfactory bulb and increased tyrosine hydroxylase immunoreactivity compared to DAT +/+ controls. D2 -/- mice exhibited the same olfactory deficit as the DAT -/- mice, further supporting the role of dopamine at the D2 synapse in olfactory discrimination processing. The findings presented in this paper reinforce the functional significance of dopamine and more specifically the D2 receptor in olfactory discrimination and may help explain the behavioral phenotype in the DAT and D2 knockout mice.

[Sixty years of study on Chinese military medicine]

Before Liberation, the study on Chinese military medicine is a virgin land. Since 1949, preliminary investigation has been made in ancient military medicine in China. Unfortunately, the study is rather superficial in the definition, scope and division of historical period of the ancient military medicine. PLA used to pay attention to the investigation and systematization and many reminescences, original articles and monographs have been published. In view of the lack of systematization in this field, the Ministry of Health of General Logistics Department, PLA, organized, in 1988, experts and professors of military medicine, together with administrators, scientific cadres, to compile Chinese History of Military Medicine which was completed in 1994, to be published soon.