Semi-solid Culture Method Research Articles

A novel temporary immersion bioreactor system for large scale multiplication of banana (Rasthali AAB\u2014Silk)

Musa sp. cultivar Rasthali (Silk AAB) is a choice variety of the Asian sub-continent. Its production and sustenance are threatened by Fusarium wilt, which affects the livelihoods of small and marginal farmers. The use of quality planting material is one of the strategies to manage the disease. Availability of quality planting material for varieties other than Grand Naine is limited. Large-scale micropropagation using existing technologies is laborious and expensive. Temporary immersion bioreactor system is emerging as a potential advancement in the micropropagation industry. In this study, a cost-effective temporary immersion bioreactor (TIB) system has been developed and an efficient micropropagation method has been standardized. Explants cultured in TIB with 250 ml of culture medium in a 2-min immersion frequency of 6 h were found to be efficient for shoot proliferation and rooting. Its efficacy has been compared with the semisolid culture method. At the end of the 6th subculture, 1496 ± 110 shoots per explant were obtained in TIB. Chlorophyll, carotenoid, stomatal index, and the number of closed stomata were examined to determine the physiological functions of the plants grown in TIB and compared with semisolid grown plantlets. Plantlets grown in TIB were genetically stable and were confirmed using inter-simple sequence repeat (ISSR) markers. The multiplication of shoots in TIB was 2.7-fold higher than the semisolid culture method, which is suitable for large-scale production of planting material for commercial applications.

Anti-radiation effect and mechanism studies of ethanol extracts from Spatholobus suberectus and its active component catechin

To study the anti-radiation effect and mechanism of ethanol extracts from Spatholobus suberectus and its active component catechin, ICR mice were exposed to 6Gy irradiation and randomly divided into normal group, model group, positive control group (amifostine, 43.6 mg•kg⁻¹, iv 30 min before irradiation), SSD group (10, 20, 40 g•kg⁻¹) and catechin group (50, 100, 200 mg•kg⁻¹). The mice were administered the appropriate drugs once a day after irradiation for 28 consecutive days. Blood samples were collected from the tail end and the number of peripheral blood cells was counted before irradiation and on day 1, 3, 7, 14, 21 and 28 using a microcell counter. Changes of thymus and spleen index of mice on day 7 were observed. The serum SOD, GSH-Px activity and MDA level were detected by the colorimetric method. The colony forming ability of bone marrow hematopoietic progenitor cells on day 7 was detected by semi solid culture method. The HE staining was adopted to observe the pathological changes. The apoptosis of bone marrow cells was detected by flow cytometry. The expression of cleaved caspase-3 and Bax of bone marrow cells were measured separately by western-blotting and immunohistochemistry method. SSD and catechin can both significantly revert the irradiated-induced decline in hematological parameters (RBC, WBC, PLT, Hb), improve thymus and spleen index, significantly enhance serum SOD and GSH-Px activity and decrease the MDA level. The proliferation and differentiation of hematopoietic progenitor cells in bone marrow were promoted, the apoptosis of bone marrow cells was significantly up-regulated and the expression of cleaved caspase-3 and Bax was significantly reduced in SSD and catechin group. SSD and catechin have significant anti-radiation effect and its mechanism may be related to hematopoietic promoting, antioxidant and anti-apoptotic effects.

Effect of up-regulated expression of tumor suppressor gene p14(ARF) on apoptosis of chronic myeloid leukemia cells

To investigate the effect of up-regulated expression of tumor suppressor gene p14(ARF) on apoptosis of chronic myeloid leukemia (CML) cells and its interaction with imatinib. Tumor suppressor gene p14(ARF) was transduced into K562 (K562-p14(ARF)) and 4 blast crisis primary CML cells (CML-BC 1-4) using vesicular stomatitis virus glycoprotein (VSV-G) pseudotyped lentiviral vector with cells transduced by empty vector as control. Fluorescence microscopy and flow cytometry were applied to measure transduction efficiency, and Western blotting assay was used to detect p14(ARF) protein of K562 cells. WST-8 method was used to determine cell growth inhibition rate of K562 cells transduced by the target gene under different concentrations of imatinib (0, 0.015, 0.062, 0.125, 0.25, 0.5, 1.0, 2.0 μmol/L). Cell apoptosis and leukemic cellular colony-forming ability were detected by Annexin V-FITC/PI dyeing using flow cytometry (FCM) and semi-solid culture method respectively. Fluorescence microscopy and FCM showed that transduction efficiency (GFP positive cells) of K562-p14(ARF), K562-VSV and CML-BC1 cells were close to 100%, and CML-BC 2-4 cells were 80% to 90% on average. Results of Western blotting showed that the levels of ARF protein expression of K562 cells transduced by p14(ARF) were significantly higher than of untransduced cells; the apoptosis rate of K562-p14(ARF) was 20%; the mean apoptosis rate of 4 primary leukemic cells transduced by the p14(ARF) [(71.1±22.4)%] was significantly higher than of control group [(12.4±6.2)%] (P<0.05). Imatinib significantly inhibited the proliferation of K562-p14(ARF) cells in a dose-dependent manner. The mean leukemic cellular colony-forming unit of 4 primary leukemic cells transduced by the p14(ARF) (41.5±13.2) was significantly lower than of the control group (88.5±7.9) (P<0.05). Increased p14(ARF) gene expression could induce apoptosis of CML cells; Moreover, it could enhance inhibitory effect on cell proliferation when combined with imatinib.

BCL11B suppression does not influence CD34+ cell differentiation and proliferation

The B-cell chronic lymphocytic leukemia (CLL)/lymphoma 11B (BCL11B) gene plays a critical role in T-cell differentiation and proliferation. However, little is understood about the role of BCL11B in human hematopoietic stem/progenitor cells. Small interfering RNA (siRNA)-mediated suppression of the BCL11B was shown to induce apoptosis in human T-cell acute lymphoblastic leukemia cells. To further characterize the role of BCL11B in hematopoietic stem/progenitor cells and assess the safety of siRNA-mediated targeted therapy, the in vitro differentiation and proliferation of CD34+ cells after BCL11B-siRNA935 treatment were studied. CD34+ cells were sorted from three cases of umbilical cord blood by the magnetic activated cell sorting technique, and the purity was identified by flow cytometry. BCL11B-siRNA935 was delivered into CD34+ cells by nucleofection and the BCL11B expression level was analyzed by quantitative real-time polymerase chain reaction. Erythroid burst-forming units (BFU-E), granulocyte/macrophage colony-forming units (CFU-GM), and megakaryocyte colony-forming units (CFU-Meg) were assessed using BCL11B-siRNA935-treated CD34+ cells by the methylcellulose semi-solid culture method. The BCL11B expression level in CD34+ cells was significantly lower than that in Molt-4 cells and peripheral blood mononuclear cells from healthy individuals. An approximate one-fold reduction in the BCL11B mRNA level was observed 24 hours post-transfection with BCL11B-siRNA935. However, there was no significant difference on the colony formation ability of BFU-E, CFU-GM, and CFU-Meg for CD34+ cells between the BCL11B-siRNA935-treated and mock-transfected groups (P > 0.05). BCL11B suppression by RNA interference had no significant influence on the differentiation and proliferation of CD34+ cells. In conclusion, the BCL11B-siRNA935 used in this study may be safe, and BCL11B may be considered a new candidate for targeted gene therapy in T-cell malignancies.

Insulin-Expressing Colonies Developed From Murine Embryonic Stem Cell–Derived Progenitors

Previous studies describe a unique culture method for the commitment of murine embryonic stem cells to early endocrine pancreata. In this report, early pancreatic-like beta-cell progenitors were enriched and a colony assay devised to allow these progenitors to differentiate into insulin-expressing colonies in vitro. An embryonic stem cell line with enhanced green fluorescent protein (EGFP) inserted into one allele of neurogenin 3 (Ngn3), a marker for pancreatic endocrine progenitors, was differentiated. During the late stage of culture, 20-30% of cells were Ngn3-EGFP(+). Gene expression profiling using the PancChip microarray platform demonstrated that Ngn3-EGFP(+) cells differentially express endocrine-related genes. A novel semisolid culture method was developed to support the formation of individual insulin/C-peptide-expressing colonies from dissociated single cells. Approximately 0.1-0.6% of Ngn3-EGFP(+) cells gave rise to insulin-expressing colonies, a three- to fivefold enrichment of beta-cell-like progenitors, or insulin-expressing colony-forming units (ICFUs), compared with nonsorted cells. All of the single colonies expressed insulin II, while 69% coexpressed insulin I and 44% coexpressed glucagon. Some single colonies expressed insulin I, insulin II, and Pdx-1 (pancreatic duodenal homeobox-1), but not glucagon. In other colonies, glucagon expression overlapped with C-peptide II in double immunostaining analysis, suggesting heterogeneity among the ICFUs and their resulting colonies. Together, these results demonstrate that progenitors that have the potential to give rise to insulin-expressing cells can be derived from murine embryonic stem cells.

Direct production of citric acid from raw starch by Aspergillus niger

The present study deals with the direct production of citric acid from raw starch by Aspergillus niger. Shake flask and semi solid culture methods were compared using A. niger GCB-47 (parental strain) and GCMC-7 (mutant strain). When cultivated in shaking culture with 150 g/l soluble starch as a carbon source, the mutant strain GCMC-7 produced 69.5 g/l citric acid, which was, 1.48-fold greater than the parental strain GCB-47. From a practical viewpoint, direct production of citric acid from corn and potato starch was examined using semi-solid culture. On the basis of a comparison of kinetic parameters namely the volumetric substrate uptake rate (Qs), the specific substrate uptake rate (qs), the volumetric productivity, theoretical yield and specific product formation rate, it was observed that the mutant strain was a faster growing organism. The mutant strain GCMC-7 produced 71.4 and 92.9 g/l citric acid, approximately 1.44 and 1.12 times as much as the parental strain GCB-47, from 200 g/l corn and potato starch, respectively. The findings suggest that GCMC-7 possesses enhanced ability for sugar metabolism and citric acid production.

Direct production of citric acid from starch by a 2-deoxyglucose-resistant mutant strain of Aspergillus niger

Citric acid production from starch by Aspergillus niger was studied by the shake and semi-solid culture methods. For citric acid production, the parental strain Yang no. 2 and a 2-deoxyglucose (DG)-resistant mutant strain, C192, were used. When cultivated in shake culture with 140 g/ l soluble starch as a carbon source, strain C192 produced 69.5 g/ l of citric acid, 1.54 times that produced by Yang no. 2, and showed enhanced glucoamylase production (a maximum level of 0.134 μkat/ml at 5 d). From a practical viewpoint, direct production of citric acid from corn- and potato starch was examined using the semi-solid culture method. When cultivated in a semi-solid culture using bagasse as a carrier, C192 produced 107.4 and 92.9 g/ l of citric acid, approximately 1.14 and 1.09 times as much as Yang no. 2, from 200 g/ l of corn- and potato starch, respectively. C192 exhibited enhanced glucoamylase production during the entire cultivation periods in comparison with that of Yang no. 2.

Citric acid production from cellobiose by 2-deoxyglucose-resistant mutant strains of Aspergillus niger in semi-solid culture

Citric acid production from cellobiose by Aspergillus niger was studied by a semi-solid culture method using bagasse as a carrier. From the parental strain Yang no. 2, mutant strains showing resistance to 2-deoxy-d-glucose (DG) on minimal medium containing glucose as a carbon source were induced. The representative mutant strain M155 was selected and subjected to further mutation. The new series of mutant strains showing resistance to DG on minimal medium containing cellobiose as a carbon source was induced, and among them the best mutant strain C192 showed higher citric acid productivity than Yang no. 2 in semi-solid culture when glucose was used as a carbon source. Moreover, in semi-solid culture, the strain C192 produced 49.6 g/l of citric acid, 1.6 times as much citric acid as Yang no. 2 produced, from 100 g cellobiose/l and showed enhanced β-glucosidase production. In shake culture, the extracellular β-glucosidase activity of C192 was higher than that of Yang no. 2 when not only cellobiose but also glucose and glycerol, catabolite repressors, were used as a carbon source. These results indicate that mutant strains such as C192 are insensitive to catabolite repression.

The Wellcome Foundation lecture, 1986. The molecular control of normal and leukaemic granulocytes and macrophages.

The development of semisolid culture methods supporting the clonal proliferation and maturation of granulocytes and macrophages led to the discovery of a group of specific glycoproteins, the colony-stimulating factors (CSFs), whose function it is to control the proliferation and functional activity of granulocytes, macrophages and associated blood cells. The four known CSFs in the mouse and man have been purified and complementary DNAs (cDNAs) for each have been cloned. The injection of bacterially synthesized recombinant CSF into mice has demonstrated that these CSFs can function in vivo to regulate granulocyte and macrophage formation. A major physiological role played by these CSFs is to control resistance to invading microorganisms through mechanisms capable of extremely rapid activation. Because the CSFs are the only known proliferative factors for these cells, the CSFs are involved in the initiation and the emergence of myeloid leukaemia but, conversely, at least one of the CSFs, G-CSF, is able to suppress myeloid leukaemic populations because of the ability of the CSFs to initiate differentiation commitment in responding granulocytic and macrophage populations. The CSFs are promising agents for clinical use in the treatment of infections in patients with depressed granulocyte-macrophage formation and possibly in the management of some types of myeloid leukaemia.

Erythroid progenitors (BFU-e and CFU-e) in acute leukaemia.

Bone marrow erythroid progenitor cells were examined from 50 cases of acute leukaemia and from 20 normal subjects using an in vitro semisolid culture method. Numbers of both primitive erythroid progenitor cells (BFU-e) and later-stage erythroid progenitor cells (CFU-e) were remarkably depressed in patient with acute leukaemia in active phase. However, both BFU-e and CFU-e recovered to within normal range when the patients achieved remission. Peripheral blood BFU-e of children with acute lymphocytic leukaemia in remission were also examined and found to have values not significantly different from those of control subjects. There was no distinct correlation between the numbers of erythroid bursts or colonies and the duration of remission in patients with acute leukaemia in remission. The reduction of BFU-e and CFU-e in active acute leukaemia suggests the involvement of erythropoietic progenitors in the pathophysiology of this type of leukaemia.