Grass straw mulching to suppress emergence and early growth of weeds

Sorghum, pearl millet, and Brachiaria ruziziensis have similar characteristics which have led to their use for mulch formation in no-till systems. This study was carried out to evaluate the potential of these three species as straw suppliers to suppress weed emergence. Initial findings led to the conclusion that both pearl millet and Brachiaria ruziziensis have similar or superior potential as weed suppressors, compared to sorghum straw, a species with recognized allelopathic potential. Subsequently, new trials were conducted under greenhouse conditions by sowing weed species in pots, followed by covering of the soil with the straw under evaluation. Independent experiments were conducted for Euphorbia heterophylla and Bidens pilosa. In each experiment, the factors analyzed were type of straw (pearl millet and B. ruziziensis), amount of straw (equivalent to 4 and 8 t ha-1 dry mass) and irrigation method (surface and subsurface). Both pearl millet and B. ruziziensis have shown to be species that can be cultivated to produce straw with allelopathic potential. These effects were effective in suppressing the emergence or early growth of E. heterophylla and B. pilosa. There was no difference in the suppression of emergence of these species when the soil cover level was alternated between 4 and 8 t ha-1 dry mass.

Sinningia allagophylla(Gesneriaceae): in vitro cultivation of a native plant of the Brazilian cerrado

We used axillary buds as initial explants for hormone interaction studies required for in vitro cultivation of S. allagophylla. Callus production was achieved on gelled Murashige & Skoog medium (MS) supplemented with indole-3-acetic acid (IAA= 0.1 and 0.5 mg.l­1 alone or combined with 6 benzylaminopurine) (BA= 0.01 and 0.1 mg.l-1). A hormone balance between IAA and BA that would encourage shoot bud development was not found. Nodal segments from axenic cultures grown in the presence of cytokinin (0.1 mg.1­1 of BA) without any auxin on MS medium with half-strength macronutrients were used as a standard explant source for subsequent experiments on optimum mineral culture media composition for S. allagophylla in vitro cultivation. We found that explants kept in vitro on gelled Gamborg et al. (B5) mineral composition culture medium showed better shoot and specially root growth than on MS medium. Comparisons of the ammonium and nitrate ratios of MS and B5 media indicate that B5 medium has a substantial reduced ammonium ion when compared to MS medium, as well as a lower total nitrogen level. The growth response pattern obtained in vitro may be evidence of the adaptation of this species to soils of poor mineral composition as found in the Brazilian cerrado, as well as an indication that nitrogen levels play a key role for S. allagophylla growth.

In vitro culture of Phyllanthus stipulatus (Euphorbiaceae)

An efficient micropropagation protocol was developed for the medicinal plant Phyllanthus stipulatus (Euphorbiaceae) using nodal segments for axillary shoot proliferation. Maximum multiplication rates (8-9 shoots per explant) was achieved on MS media supplemented with either 2.5-5.0 muM IBA. The best basal media for axillary shoot proliferation when 0.62 muM BA was supplemented were MS, MS/2 and AR (4-5 shoots per explant). Rooting was achieved with 100% of the microshoots on MS medium without growth regulators. Regenerated plants were successfully acclimatized and about 88% of plantlets survived under ex vitro conditions. Flowering was observed in 81% of the ex vitro grown plantlets after 12 weeks of acclimatization. High frequency callus initiation and growth was achieved when nodal segment explants were inoculated either in the vertical position, in the light on MS medium supplemented with 5.0 muM NAA or horizontally oriented, in the dark on MS supplemented with 5.0 muM NAA or 1.25-5.0 muM BA or 2iP. Root cultures were successfully established on MS medium containing 1.1 muM NAA. The optimized micropropagation, callus and root culture protocols offer the possibility to use cell/organ culture techniques for vegetative propagation and secondary metabolism studies.

Effects of iron-ore particles on propagule release, growth and photosynthetic performance of Sargassum vulgare C. Agardh (Phaeophyta, Fucales)

The effect of iron-ore particles on the propagule release and growth of Sargassum vulgare C. Agardh was tested under treatments with different concentrations of iron-ore particles: 0.1, 1.0, 10.0 g.L-1 and a solution of 10.0 g.L-1 of filtered iron-ore. Filtered seawater was used as control. Photosynthesis vs. irradiance (P-I) curves were calculated for S. vulgare in the presence of iron-ore and in seawater. There was no significant difference in the number of propagules released by the receptacles or in the percentage of zygote formation among the treatments. The released propagules acted like aggregation centers for the particles, those more heavily coated with iron (10.0 g.L-1) exhibiting the highest sinking velocity (32.6 ± 9.8 mm.s-1). No difference in the percentage of embryo survival was detected during the first week in culture. After four weeks the embryos grew in all treatments. Maximum frond development (5.3 ± 0.8 mm) was observed in treatment of seawater enriched with Provasoli's medium (PES) while initial filoids did not develop in three treatments without PES and with iron-ore (0.1 g.L-1, 1.0 g.L-1 and 10.0 g.L-1). The values for Pmax, alpha and respiration showed no significant differences between the P-I curves. The calculated value for I K was 106.26 µmol.m-2.s-1 to the control curve and 981.49 µmol.m-2.s-1 to the iron-ore curve. The results indicate that the iron-ore particles in high concentration reduce the growth of S. vulgare as they recovered the embryos, juveniles and young plants. In contrast, the presence of the particles did not affect the release of gametes, percentage of zygote formation or the percentage of embryo survival.

Effect of nitrate and ammonium on the growth and protein concentration of Microcystis viridis Lemmermann (Cyanobacteria)

Cyanobacteria are a very important group in aquatic systems, particularly in eutrophic waters. Therefore studies about their success in the environment are essential. Many hypotheses have tried to explain the dominance of Cyanobacteria, and several emphasized the importance of various nitrogen sources for the success of the group. In this study, we measured the effect of ammonium and nitrate on the growth and protein concentration of Microcystis viridis (Cyanobacteria). This species is well-known because bloom formation in eutrophic waters. The study was carried out, in experimental batch cultures, using the WC medium with different nitrogen sources: ammonium, nitrate, ammonium + nitrate (50% ammonium + 50% nitrate) and ammonium at different concentrations (to test for possible NH4+ toxicity). Protein, ammonium and nitrate concentrations were measured at end of each experiment, whereas samples for cell counts were taken daily. Results showed that Microcystis viridis grew faster with ammonium (µ = 0.393 day-1) than with nitrate (µ = 0.263 day-1) and ammonium + nitrate (µ = 0.325 day-1). This pattern is explained by the metabolism of ammonium that presents higher uptake and assimilation rates than nitrate. Maximum cell concentration, however, was higher in the ammonium + nitrate treatment, followed by nitrate treatment. Higher protein concentration were observed in the treatment with nitrate. In the ammonium toxicity test, no difference between the control and NH4+ at 50% was found. Thus, the ammonium concentrations used in these experiments were not toxic. Our results suggest that Cyanobacteria is able to grow on both nitrogen sources even if ammonium may allow faster growth and bloom development.

Xyloglucans from Hymenaea courbaril var. stilbocarpa seeds affect Arabidopsis thaliana seedling growth by enhancing lateral root development

The effect of crude xyloglucan (XG) preparations from jatobá (Hymenaea courbaril var. stilbocarpa (Hayne) Y. T. Lee & Langenh.) seeds on Arabidopsis thaliana (L.) Heynh. root system development was investigated. The XG extracts exerted a dual effect on root system development by slowing down root growth and improving lateral root formation. These observed morphological changes were not due to oligosaccharides that could be generated following hydrolysis of the XG polymers, since XG hydrolysate induced a drastic inhibition of the overall growth process of the Arabidopsis thaliana seedlings. Histochemical test of GUS gene expression assay performed on seven and 14-days-old transgenic Arabidopsis thaliana plants carrying the CycB1;1-GUS fusion indicated that the improvement of the lateral root development by jatobá XG extracts was not correlated with the expression of this cell cycle marker gene in the root system. A potential agricultural application of jatobá seeds XG extract is discussed.

Steps in the formation of neurites and synapses studied in cultured leech neurons

Leech neurons in culture have provided novel insights into the steps in the formation of neurite outgrowth patterns, target recognition and synapse formation. Identified adult neurons from the central nervous system of the leech can be removed individually and plated in culture under well-controlled conditions, where they retain their characteristic physiological properties, grow neurites and form specific chemical or electrical synapses. Different identified neurons develop distinctive outgrowth patterns that depend on their identities and on the molecular composition of the substrate. On native substrates, the patterns displayed by these neurons reproduce characteristics from the adult or the developing neurons. In addition, the substrate may induce selective directed growth between pairs of neurons that normally make contact in the ganglion. Upon contact, pairs of cultured leech neurons form chemical or electrical synapses, or both types depending on the neuronal identities. Anterograde and retrograde signals during membrane contact and synapse formation modify the distribution of synaptic terminals, calcium currents, and responses to 5-hydroxytryptamine.

alpha-Tocopherol enhances tumour growth inhibition by cis-dichlorodiammine platinum (II)

Present studies indicate that alpha-tocopherol enhances the efficacy of cisplatin as demonstrated by inoculation of Dalton's lymphoma cells incubated with either cisplatin (5 or 10 µg/ml) alone or cisplatin + alpha-tocopherol (25 or 50 µg/ml) into C3H/He mice. Tumour cells (3 x 10(6) cells/mouse) incubated with cisplatin grow slowly in syngeneic mice as indicated by the late appearance of tumour. However, mice failed to develop tumour when inoculated with tumour cells incubated with cisplatin + alpha-tocopherol. When the animals were challenged with tumour cells (3 x 10(6) cells/mouse) on the 15th day after the initial inoculation, 30-50% survived more than 60 days, with 10% tumour-free survivors being observed in some groups. Antitumour activity was higher in mice receiving lymphoma cells (3 x 10(6) cells/mouse) preincubated with cisplatin + alpha-tocopherol compared to cisplatin alone. Tumour-bearing mice receiving cisplatin in combination with different concentrations of alpha-tocopherol exhibited significantly higher (P<0.001) intratumour platinum content (123-306%) but without any change in the kidney platinum content as compared to those receiving cisplatin (5 or 10 µg/ml) alone. Enhancement of cisplatin-induced tumour growth inhibition is probably due to the modulation of tumour cell membrane permeability by alpha-tocopherol. alpha-Tocopherol might increase the influx of cisplatin into tumour cells, causing the DNA repair machinery to be less efficient due to increased efficiency of adduct formation in the DNA molecule. This effect of alpha-tocopherol can render cisplatin more effective as an antitumour agent.

A single strain of Mycobacterium bovis bacillus Calmette-Guérin (BCG) grown in two different media evokes distinct humoral immune responses in mice

Two attenuated bacillus Calmette-Guérin (BCG) preparations derived from the same Moreau strain, Copenhagen but grown in Sauton medium containing starch and bacto-peptone (onco BCG, O-BCG), or asparagine (intradermal BCG, ID-BCG), exhibited indistinguishable DNA sequences and bacterial morphology. The number of viable bacilli recovered from spleen, liver and lungs was approximately the same in mice inoculated with the vaccines and was similarly reduced (over 90%) in mice previously immunized with either BCG vaccine. The humoral immune response evoked by the vaccines was, however, distinct. Spleen cell proliferation accompanying the growth of bacilli in tissue was significantly higher in mice inoculated with O-BCG. These cells proliferated in vitro upon challenge with the corresponding BCG extract. Previous cell treatment with mAb anti-CD4 T cells abolished this effect. Anti-BCG antibodies, as assayed either in serum by ELISA or by determining the number of antibody-producing spleen cells by the spot-ELISA method, were significantly higher in mice inoculated with ID-BCG. Anti-BCG antibodies were detected in all immunoglobulin classes, but they were more prevalent in IgG with the following distribution among its isotypes: IgG1>(IgG2a = IgG2b)>IgG3. When some well-characterized Mycobacterium tuberculosis antigens were used as substitutes for BCG extracts in ELISA, although antibodies against the 65-kDa and 96-kDa proteins were detected significantly, antibodies against the 71-kDa, 38-kDa proteins and lipoarabinomannan were only barely detected or even absent. These results indicate that BCG bacilli cultured in Sauton-asparagine medium permitted the multiplication of bacilli, tending to induce a stronger humoral immune response as compared with bacilli grown in Sauton-starch/bacto-peptone-enriched medium.

Importance of hyaluronan biosynthesis and degradation in cell differentiation and tumor formation

Hyaluronan is an important connective tissue glycosaminoglycan. Elevated hyaluronan biosynthesis is a common feature during tissue remodeling under both physiological and pathological conditions. Through its interactions with hyaladherins, hyaluronan affects several cellular functions such as cell migration and differentiation. The activities of hyaluronan-synthesizing and -degrading enzymes have been shown to be regulated in response to growth factors. During tumor progression hyaluronan stimulates tumor cell growth and invasiveness. Thus, elucidation of the molecular mechanisms which regulate the activities of hyaluronan-synthesizing and -degrading enzymes during tumor progression is highly desired.

Interaction between growth differentiation factor 9, insulin-like growth factor I and growth hormone on the in vitro development and survival of goat preantral follicles

The objective of this study was to determine the effects of GDF-9, IGF-I, and GH alone or combined on preantral follicle survival, activation and development after 1 and 7 days of in vitro culture. Either fresh (non-cultured) or cultured ovarian tissue was processed for histological and fluorescence analysis. For all media tested, the percent of normal follicles was greater when compared to minimum essential medium supplemented (MEM+) alone, except when ovarian tissue was cultured with GDF-9/IGF-I or GDF-9/GH (P < 0.05). Fluorescence analysis showed that the percent of viable follicles after 7 days of culture was similar for non-cultured tissue and for all treatments tested. The percent of primordial follicles was reduced (P < 0.05) and there was a significant and concomitant increase in the percent of intermediate and primary follicles in all treatments tested after 7 days of culture when compared to non-cultured tissue. After 7 days of culture, the highest percent of intermediate follicles was observed with IGF-I/GH (61.3%), and the highest percent of primary follicles was achieved with IGF-I (57.7%). After 7 days of culture in MEM+ containing GDF-9, IGF-I and GH alone or in all associations, a significant increase in follicular diameter was observed when compared to MEM+ alone and non-cultured tissue. In conclusion, GDF-9, IGF-I and GH alone or in combination maintain preantral follicle survival and promote primordial follicle activation. Nevertheless, the data showed that IGF-I/GH and IGF-I alone are efficient in promoting the transition from primordial to intermediate follicles and from intermediate to primary follicles, respectively.

Normal skin and hypertrophic scar fibroblasts differentially regulate collagen and fibronectin expression as well as mitochondrial membrane potential in response to basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) regulates skin wound healing; however, the underlying mechanism remains to be defined. In the present study, we determined the effects of bFGF on the regulation of cell growth as well as collagen and fibronectin expression in fibroblasts from normal human skin and from hypertrophic scars. We then explored the involvement of mitochondria in mediating bFGF-inducedeffects on the fibroblasts. We isolated and cultivated normal and hypertrophic scar fibroblasts from tissue biopsies of patients who underwent plastic surgery for repairing hypertrophic scars. The fibroblasts were then treated with different concentrations of bFGF (ranging from 0.1 to 1000 ng/mL). The growth of hypertrophic scar fibroblasts became slower with selective inhibition of type I collagen production after exposure to bFGF. However, type III collagen expression was affected in both normal and hypertrophic scar fibroblasts. Moreover, fibronectin expression in the normal fibroblasts was up-regulated after bFGF treatment. bFGF (1000 ng/mL) also induced mitochondrial depolarization in hypertrophic scar fibroblasts (P < 0.01). The cellular ATP level decreased in hypertrophic scar fibroblasts (P < 0.05), while it increased in the normal fibroblasts following treatment with bFGF (P < 0.01). These data suggest that bFGF has differential effects and mechanisms on fibroblasts of the normal skin and hypertrophic scars, indicating that bFGF may play a role in the early phase of skin wound healing and post-burn scar formation.

Silencing HIF-1α reduces the adhesion and secretion functions of acute leukemia hBMSCs

Hypoxia inducible factor-1α (HIF-1α) is an important transcription factor, which plays a critical role in the formation of solid tumor and its microenviroment. The objective of the present study was to evaluate the expression and function of HIF-1α in human leukemia bone marrow stromal cells (BMSCs) and to identify the downstream targets of HIF-1α. HIF-1α expression was detected at both the RNA and protein levels using real-time PCR and immunohistochemistry, respectively. Vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) were detected in stromal cells by enzyme-linked immunosorbent assay. HIF-1α was blocked by constructing the lentiviral RNAi vector system and infecting the BMSCs. The Jurkat cell/BMSC co-cultured system was constructed by putting the two cells into the same suitable cultured media and conditions. Cell adhesion and secretion functions of stromal cells were evaluated after transfection with the lentiviral RNAi vector of HIF-1α. Increased HIF-1α mRNA and protein was detected in the nucleus of the acute myeloblastic and acute lymphoblastic leukemia compared with normal BMSCs. The lentiviral RANi vector for HIF-1α was successfully constructed and was applied to block the expression of HIF-1α. When HIF-1α of BMSCs was blocked, the expression of VEGF and SDF-1 secreted by stromal cells were decreased. When HIF-1α was blocked, the co-cultured Jurkat cell’s adhesion and migration functions were also decreased. Taken together, these results suggest that HIF-1α acts as an important transcription factor and can significantly affect the secretion and adhesion functions of leukemia BMSCs.

Diabetes mellitus affects the biomechanical function of the callus and the expression of TGF-beta1 and BMP2 in an early stage of fracture healing

Transforming growth factor beta 1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) are important regulators of bone repair and regeneration. In this study, we examined whether TGF-β1 and BMP-2 expressions were delayed during bone healing in type 1 diabetes mellitus. Tibial fractures were created in 95 diabetic and 95 control adult male Wistar rats of 10 weeks of age. At 1, 2, 3, 4, and 5 weeks after fracture induction, five rats were sacrificed from each group. The expressions of TGF-β1 and BMP2 in the fractured tibias were measured by immunohistochemistry and quantitative reverse-transcription polymerase chain reaction, weekly for the first 5 weeks post-fracture. Mechanical parameters (bending rigidity, torsional rigidity, destruction torque) of the healing bones were also assessed at 3, 4, and 5 weeks post-fracture, after the rats were sacrificed. The bending rigidity, torsional rigidity and destruction torque of the two groups increased continuously during the healing process. The diabetes group had lower mean values for bending rigidity, torsional rigidity and destruction torque compared with the control group (P<0.05). TGF-β1 and BMP-2 expression were significantly lower (P<0.05) in the control group than in the diabetes group at postoperative weeks 1, 2, and 3. Peak levels of TGF-β1 and BMP-2 expression were delayed by 1 week in the diabetes group compared with the control group. Our results demonstrate that there was a delayed recovery in the biomechanical function of the fractured bones in diabetic rats. This delay may be associated with a delayed expression of the growth factors TGF-β1 and BMP-2.

Culture alternative medium for the growth of extreme halophilic bacteria in fish products

Halotolerant or halophilic (Archaeabacteria) microorganisms can be found in salted and ripening fish products that are not affected by salt. They can be moderate or extremely halophilic bacteria. The extremely halophilic bacteria require between 15-30% of NaCl for growth. The extremely halophilic archaeobacteria may be selectively isolated in different media. The aim of this work was to determine the effectiveness of the Salt-Agar-Milk medium, a medium modified in our laboratory through the addition of MgSO4 and KCl - named SAMm, and its effect on the bacterial growth by means of comparison with other media, with and without milk, determining time of incubation and counting. Two samples of salted fish from local fish salting factories and two laboratory strains were used. The factory samples were matured anchovy and anchovy fillets in oil, and the laboratory strains were: Haloarcula spp. (proteolytic) and Halococcus spp. (non-proteolytic). The following media were alternatively used for the isolation of extremely halophilic bacteria: IRAM; Formulation of Gibbons and collaborators, Cod Milk agar, and SAMm. IRAM and Gibbons were also used enriched with milk. In the SAMm medium, there were obtained count values similar or higher than the ones of the traditional media; besides the simplicity of its elaboration, the possibility to obtain positive results two or three days earlier also added to its benefit. Consequently, it can be considered an alternative to the media traditionally used for the studied halophilic bacteria.