Selection of several classes of mimosine-degradation-defective Tn3Hogus-insertion mutants of Rhizobium sp. strain TAL1145 on the basis of mimosine-inducible GUS activity

2001 ◽  
Vol 47 (6) ◽  
pp. 488-494 ◽  
Author(s):  
P M Fox ◽  
D Borthakur
Keyword(s):  
Leucaena Leucocephala ◽  
Inhibitory Effect ◽  
Gus Activity ◽  
Cosmid Clone ◽  
Tree Legume ◽  
Correct Orientation ◽  
Escherichia Coli Cells ◽  
Rhizobium Sp ◽  
Insertion Mutants ◽  
Selection Of

Rhizobium sp. strain TAL1145 that nodulates Leucaena leucocephala degrades mimosine, a toxin produced by this tree legume. A cosmid clone, pUHR263, containing ~25 kb cloned DNA was isolated by plating Escherichia coli cells containing the cosmid clone library of TAL1145 on a minimal medium in which 3-hydroxy-4-pyridone (HP), a degradation product of mimosine, was used as the source of nitrogen. Cosmid pUHR263 was mutagenized by random insertions of Tn3Hogus, a transposon that makes transcriptional gus fusions when it is inserted in a gene in the correct orientation. Various pUHR263::Tn3Hogus derivatives that showed mimosine-inducible or mimosine-repressible GUS activities when transferred to the Rhizobium sp. strain TAL1145 were selected. Mutants of TAL1145 were constructed by transferring these Tn3Hogus insertions into the TAL1145 chromosome through double-homologous recombination. These mutants were classified into five classes on the basis of defects in mimosine degradation. The growth of these mutants was inhibited to different extents by mimosine applied to the growth medium. Mimosine forms a red-colored Fe-mimosine complex when FeCl3 is added to the medium. The inhibitory effect of Fe-mimosine on growth of the mutants was much less than that of mimosine.Key words: mimosine, mid and pyd genes, Leucaena leucocephala, tree legume, Tn3Hogus.

Giant leucaena (Leucaena leucocephala subsp. glabrata): a versatile tree-legume for sustainable agroforestry

2019 ◽  
Vol 94 (1) ◽  
pp. 251-268 ◽  
Author(s):  
Ahmed Bageel ◽  
Michael D. H. Honda ◽  
James T. Carrillo ◽  
Dulal Borthakur
Keyword(s):  
Leucaena Leucocephala ◽  
Tree Legume

Effect of a mixed silage of king grass (Cenchrus purpureus) and forage legumes (Leucaena leucocephala or Gliricidia sepium) on sheep intake, digestibility and nitrogen balance

2019 ◽  
Vol 59 (12) ◽  
pp. 2259
Author(s):  
A. A. Santana ◽  
L. Cheng ◽  
D. M. Verdecia ◽  
J. L. Ramírez ◽  
S. López ◽  
...  
Keyword(s):  
Leucaena Leucocephala ◽  
Urine Volume ◽  
Gliricidia Sepium ◽  
Nutrient Digestibility ◽  
Tree Legume ◽  
N Content ◽  
N Retention ◽  
Grass Silage ◽  
Pelibuey Sheep ◽  
Intake Ratio

Ensiled king grass (Cenchrus purpureus (Schumach.) Morrone) is commonly used as feed in tropical ruminant production. However, ruminant performance can be limited by low nitrogen (N) content in tropical grass silage. A mixed feed of legume–king grass silage may be an option to improve ruminant production. We investigated the effects of feeding an ensiled mixture of king grass forage and foliage of a browse tree legume, either leucaena (Leucaena leucocephala (Lam.) de Wit) or gliricidia (Gliricidia sepium (Jacq.) Walp), on dry matter (DM) intake, DM digestibility, organic matter (OM) digestibility and N balance of Pelibuey sheep. Twelve male lambs 9–11 months old were blocked by initial bodyweight (33 ± 3 kg, mean ± s.d.) into three groups of four lambs and randomly assigned to one of three feed treatments: king grass silage (KS); mixed king grass and leucaena silage (KLS); and mixed king grass and gliricidia silage (KGS). Results showed that DM and OM were similar among silages. The N content was higher (P < 0.001) in KLS and KGS than in KS. DM intake and DM digestibility were higher (P < 0.001) in KLS and KGS than in KS. OM digestibility was higher (P < 0.001) in KLS than in KS. Nitrogen intake, faecal N, urine volume, urinary N, digested N, N digestibility, N retention and retained N:N intake ratio from KLS and KGS treatments were higher (P < 0.05) than from KS. A lower (P < 0.01) urinary N:N intake ratio was detected from KGS and KLS than from KS. This study demonstrated that, compared with silage made from king grass alone, legume–king grass silage mixtures can improve intake and nutrient digestibility in Pelibuey lambs. Further, N retention can be enhanced when legume–king grass silages are used as feed compared with king grass silage alone.

scholarly journals Biological fixation of nitrogen by native isolates of Rhizobium sp. symbionts of Leucaena leucocephala (Lam.) De Wit

2019 ◽  
Vol 68 (2) ◽  
pp. 75-83 ◽  
Author(s):  
Juan Guillermo Cubillos-Hinojosa ◽  
Pablo Ernesto Milian Mindiola ◽  
Jorge Luis Hernández Mulford ◽  
Arnaldo De Jesús Peralta Castilla
Keyword(s):  
Leucaena Leucocephala ◽  
Animal Feed ◽  
Block Design ◽  
Stem Length ◽  
Nitrogen Accumulation ◽  
Symbiotic Association ◽  
Silvopastoral Systems ◽  
Biological Fixation ◽  
Commercial Strain ◽  
Rhizobium Sp

Forage legumes such as Leucaena leucocephala, besides being a rich source of protein for animal feed, its inclusion in silvopastoral systems provides fundamental components to improve soil properties. These plants have the ability to establish symbiotic association with the genus Rhizobium sp. and fix biologically atmospheric nitrogen favoring growth and development, being reflected in production increases. The objective of this research was to evaluate the capacity of native isolates of Rhizobium sp. and a commercial strain in biological nitrogen fixation (BNF) in L. leucocephala plants. Two separate bioassays to evaluate the efficiency of the FBN of the native isolates and the commercial strain under greenhouse conditions, followed by a randomized complete block design with 7 x 2 factorial arrangement, seven treatments, two factors: native isolates and commercial strains and bacterial concentrations (106 and 108 cells.ml-1), with three repetitions and five experimental units. The first bioassay was carried out with seeds, determining the percentage of germination, the length and thickness of the stem, number of leaves, dry weight of the aerial part, number of nodule/plant and the percentage of nitrogen accumulated in the area part of the plant. In the second bioassay with 30-day-old seedlings, the same variables of the first bioassay were determined, with the exception of the percentage of germination. In the first bioassay, a greater stimulation was found in the germination of L. leucocephala seeds at a concentration of 108 cells.mL-1. Regarding stem length and thickness, accumulated dry matter, leaf  development and nitrogen accumulation, better results were found in the treatments with the native isolates L27, L36 and L38 in a concentration of 106 cells.mL-1 above the commercial strain in concentration of 108 cells.mL-1. The native isolates of Rhizobium sp. exert a positive effect on the FBN and the germination of plants of L. leucocephala, which will allow to conduct future field studies that allow to potentiate the culture of L. leucocephala and silvopastoral systems for bovine feeding.

scholarly journals REJECTION OF TUMOR ALLOGRAFTS BY MOUSE SPLEEN CELLS SENSITIZED IN VITRO

1971 ◽  
Vol 133 (4) ◽  
pp. 821-833 ◽  
Author(s):  
Irun R. Cohen ◽  
Amiela Globerson ◽  
Michael Feldman
Keyword(s):  
Inhibitory Effect ◽  
Lymphoid Cells ◽  
Mouse Spleen ◽  
Target Cells ◽  
Functional Assay ◽  
Spleen Cells ◽  
Growth Of Tumor ◽  
Selection Of

This paper reports a model system of cellular immunity in which allosensitization of mouse spleen cells is induced in vitro. Allosensitization was achieved by culturing spleen cells upon monolayers of allogeneic fibroblasts. The ability of the spleen cells to inhibit the growth of tumor allografts in vivo served as a functional assay of sensitization. We found that unsensitized spleen cells or spleen cells sensitized against unrelated fibroblast antigens had no inhibitory effect on the growth of allogeneic fibrosarcoma cells when they were injected together into irradiated recipients. In contrast, spleen cells which were specifically allosensitized in vitro were found to be highly effective in inhibiting the growth of an equal number of allogeneic tumor cells. Several times more spleen cells from mice sensitized in vivo were required to produce a similar immune effect. This confirms the findings of previous studies which indicate that sensitization in cell culture can promote the selection of specifically sensitized lymphocytes. Preincubating sensitizing fibroblasts with allo-antisera blocked the allosensitization of spleen cells. This suggests that antibodies binding to fibroblasts may inhibit the induction of sensitization by competing with lymphocytes for antigenic sites. Mouse spleen cells which were able to recognize and reject tumor allografts in vivo were unable to cause lysis of target fibroblasts in vitro. Such fibroblasts, however, were susceptible to lysis by rat lymphoid cells sensitized by a similar in vitro method. These findings indicate that the conditions required for lymphocyte-mediated lysis of target cells may not be directly related to the processes of antigen recognition and allograft rejection in vivo.

Competitiveness of Rhizobium sp. [Leucaena leucocephala (Lam.) Dewit] strains and their genetically marked derivatives

1996 ◽  
Vol 22 (6) ◽  
pp. 443-447
Author(s):  
D.M. Swelim ◽  
L.D. Kuykendall ◽  
F.M. Hashem ◽  
S.M. Abdel-Wahab ◽  
N.I. Hegazi
Keyword(s):  
Leucaena Leucocephala ◽  
Rhizobium Sp

scholarly journals Investigation of the effect of hydrocinnamic (3-phenylpropanoic) acid on the microbiological corrosion of steel

2020 ◽  
Author(s):  
А.А. Грибанькова ◽  
М.А. Агиевич ◽  
О.А. Евтуховская ◽  
В.В. Гурченко ◽  
С. Чжай ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Ph Value ◽  
Inhibitory Effect ◽  
Bacterial Cells ◽  
Microbiological Corrosion ◽  
Sulfate Reducing ◽  
Corrosion Of Steel ◽  
Reducing Bacteria ◽  
Number Of Bacteria ◽  
Selection Of

В основе работы лежит исследование воздействия органического соединения (ОС) – гидрокоричной (3-фенилпропановой) кислоты на бактериальные клетки СРБ (сульфатредуцирующих бактерий) являющиеся стимуляторами коррозионных процессов. Подбор условий использования и количественная оценка эффективности ингибирующего (биоцидного) действия исследуемого ОС, которое может быть применено для защиты стали от коррозии в средах, содержащих сульфатредуцирующие бактерии. В ходе исследования было изучено влияние ОС на развитие сульфатредуцирующих бактерий и определены такие параметры, как изменение значения pH и окислительно-восстановительного потенциала образцов в среде, численности бактерий и содержания биогенного сероводорода в зависимости от концентрации используемого ОС. Сделаны основные выводы о ингибирующем коррозию и биоцидном действиях испытуемого органического соединения путем оценки скорости коррозии образцов стали и защитном эффекте в зависимости от выбранных концентраций органического соединения методом гравиметрии. Дополнительная оценка ингибирующего действия была проведена методом электрохимической импедансной спектроскопии и методом снятия поляризационных кривых испытуемых образцов. The study is based on the study of the effect of an organic compound (OC) – hydrocinnamic (3-phenylpropanoic) acid on the bacterial cells of SRB (sulfate-reducing bacteria), which are stimulants of corrosion processes. Selection of conditions of use and a quantitative assessment of the effectiveness of the inhibitory (biocidal) action of the studied OC, which can be used to protect steel from corrosion in environments containing SRB. In the course of the study, the effect of OC on the development of SRB was studied and such parameters as the change in the pH value and the redox potential of the samples in the medium, the number of bacteria and the content of biogenic hydrogen sulfide depending on the concentration of the used OC were determined. The main conclusions are drawn about the inhibitory corrosion and biocidal actions of the test OC by assessing the corrosion rate of steel samples and the protective effect depending on the selected concentrations of the OC by gravimetry. An additional assessment of the inhibitory effect was carried out by the method of electrochemical impedance spectroscopy and by the method of taking the polarization curves of the test samples.

scholarly journals Intrabody Targeting HIF-1α Mediates Transcriptional Downregulation of Target Genes Related to Solid Tumors

2021 ◽  
Vol 22 (22) ◽  
pp. 12335
Author(s):  
Yaozhong Hu ◽  
Ema Romão ◽  
Cécile Vincke ◽  
Lea Brys ◽  
Yvon Elkrim ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Hypoxic Condition ◽  
Inhibitory Effect ◽  
Intracellular Expression ◽  
Proliferation And Metastasis ◽  
Immune Library ◽  
Selection Of

Uncontrolled growth of solid tumors will result in a hallmark hypoxic condition, whereby the key transcriptional regulator of hypoxia inducible factor-1α (HIF-1α) will be stabilized to activate the transcription of target genes that are responsible for the metabolism, proliferation, and metastasis of tumor cells. Targeting and inhibiting the transcriptional activity of HIF-1 may provide an interesting strategy for cancer therapy. In the present study, an immune library and a synthetic library were constructed for the phage display selection of Nbs against recombinant PAS B domain protein (rPasB) of HIF-1α. After panning and screening, seven different nanobodies (Nbs) were selected, of which five were confirmed via immunoprecipitation to target the native HIF-1α subunit. The inhibitory effect of the selected Nbs on HIF-1 induced activation of target genes has been evaluated after intracellular expression of these Nbs in HeLa cells. The dramatic inhibition of both intrabody formats on the expression of HIF-1-related target genes has been confirmed, which indicated the inhibitory efficacy of selected Nbs on the transcriptional activity of HIF-1.

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