Protocol development for somatic embryogenesis, SSR markers and genetic modification of Stipagrostis pennata (Trin.) De Winter

BACKGROUND

Stipagrostis pennata (Trin.) De Winter is an important species for fixing sand in shifting and semi-fixed sandy lands, for grazing, and potentially as a source of lignocellulose fibres for pulp and paper industry. The seeds have low viability, which limits uses for revegetation. Somatic embryogenesis offers an alternative method for obtaining large numbers of plants from limited seed sources.

RESULTS

A protocol for plant regeneration from somatic embryos of S. pennata was developed. Somatic embryogenesis was induced on Murashige & Skoog (MS) medium supplemented with 3 mg·L-1 2,4-D subsequently shoots were induced on MS medium and supplemented with 5 mg·L-1 zeatin riboside. The highest shoots induction was obtained when embryogenic callus derived from mature embryos (96%) in combination with MS filter-sterilized medium was used from Khuzestan location. The genetic stability of regenerated plants was analysed using ten simple sequence repeats (SSR) markers from S. pennata which showed no somaclonal variation in regenerated plants from somatic embryos of S. pennata. The regenerated plants of S. pennata showed genetic stability without any somaclonal variation for the four pairs of primers that gave the expected amplicon sizes. This data seems very reliable as three of the PCR products belonged to the coding region of the genome. Furthermore, stable expression of GUS was obtained after Agrobacterium-mediated transformation using a super binary vector carried by a bacterial strain LBA4404.

CONCLUSION

To our knowledge, the current work is the first attempt to develop an in vitro protocol for somatic embryogenesis including the SSR marker analyses of regenerated plants, and Agrobacterium-mediated transformation of S. pennata that can be used for its large-scale production for commercial purposes.

Histopathological Evidence in Support of the Association of Elevated Proton Spin-lattice Relaxation Times with the Malignant State

The pulsed nuclear magnetic resonance technique was explored for its potential diagnostic value in human cancer. Measurements of proton spin-lattice relaxation times (T1) of cellular water protons of normal and malignant esophageal tissues showed elevated T, values in the latter. In some cases, tissues which appeared normal on gross examination assumed as uninvolved tissues had T, values higher than the other grossly uninvolved tissues and often closer to the T, of the corresponding tumor tissue. A histopathological study of the assumed uninvolved areas also studied for the T, values was therefore undertaken. A preliminary study demonstrated the presence of malignant cell groups or clusters in some of the uninvolved samples with higher T1 compared to the true uninvolved tissues, which had a normal histological picture and low T, values. This observation has brought out the importance of histopathological studies in addition to relaxation studies to comprehend contributory factors to relaxation. Secondly, it lends support to the thesis of elevated T, values being characteristics of the malignant state.

Magnetic resonance imaging (MRI) of Saccharum officinarum L. (sugarcane) during its growth for sucrose content

Magnetic Resonance Imaging (MRI) was employed to monitor changes in image intensities in stems of sugarcane which reflect on the increase in sucrose concentration. Contrast in images originates in the increase of sucrose concentration in the aqueous phase of the predominant parenchyma cells and physiological changes. In matured stems mixed MR intensity patterns were observed in transverse planes. We associate this due to the reflection of vascular bundles in ground parenchyma cells which constitute 80% sucrose storage.

Significance of histopathology in pulsed NMR studies on cancer

Characterization of tissue by pulsed nuclear magnetic resonance spectrometry opened a new area of research. The differences in the NMR parameters T1 and T2 of normal and malignant tissues constitute the basis for their distinction by pulsed NMR spectrometry and also by NMR imaging in vivo. The present studies were undertaken to correlate the role of constituent histological elements encountered in various malignancy-associated changes and T1 variations and are based on evaluation of samples taken from surgically resected specimens of carcinoma of the esophagus, comprising the uninvolved portions of the esophagus and the gastric end on gross examination. The uninvolved and involved regions showed low and high T1 values, respectively. High T1 values were also encountered in the zones of samples of uninvolved esophagus which histologically revealed areas with dysplasia. This feature, viz., dysplasia representing malignancy-associated changes, has been found to recur in many samples. Detailed histological studies provided further evidence confirming that areas with dysplasia contribute to an increase in T1 values whereas in zones at the gastric end metaplasia and hyperplasia are more common. The results are of value for demarcation of tumor area by in vivo NMR imaging.

Transition metals in human cancer II

Many of the trace metals are associated with enzymes involved in vital physiological roles. It would therefore seem reasonable to expect alterations in the levels of certain elements to be associated with cancer. Secondly, their levels would indicate whether or not they have a direct influence on the proton spin-lattice relaxation time (T1), as determined by pulsed nuclear magnetic resonance spectrometry (NMR). The results obtained on leukaemic bone marrow and oesophageal cancer were reported earlier. In the present work is reported the data obtained for the levels of the transition elements Fe, Zn, Mn and Cu in human cancers of other regions of the body. The role of trace metals has been discussed from the point of view both of their value as markers of malignancy, and of the elevation of proton spin-lattice relaxation times.

Distinction between normal and leukemic bone marrow by water protons nuclear magnetic resonance relaxation times

Pulsed nuclear magnetic resonance studies have been carried out on bone marrow of normal human subjects and patients with leukemia: chronic myeloid leukemia (CML) and acute myeloid leukemia (AML). It was observed that the proton spin-lattice relaxation time (T1) value was discriminatory in the normal and leukemic cases with a statistical significance of (p less than 0.01). Ouabain treatment of cells did not show any perceptible change of T1 value when compared with the nontreated cells, indicating that the concomitant cation effluxes do not affect spin-lattice relaxation time. The water contents of normal, leukemic, and ouabain treated cells were in the range 60%-80%. Higher Fe levels were encountered in the normal than the leukemic samples, while levels of Zn, Cu, Mn, Co, and Ni were elevated in the leukemic samples compared with the normals. Despite the T1 differences observed, the multiparameter studies do not uniquely pinpoint factors responsible for the elevation of T1 in the malignant state.

Transition metals in an experimental tumour system

In this report we present an analysis by atomic absorption spectrometry of some of the transition metals Fe, Zn, Cu, Mn, Co, and Ni in tissues and nuclear fractions in an experimental tumour system.

The effect of U.V.-irradiation on lambda DNA transcription

The effect of U.V.-irradiation of template DNA has been studied in vitro in the E. coli RNA polymerase system with native and U.V.-treated lambda DNA. Lambda DNA is more susceptible to U.V. than is calf-thymus DNA, yet a residual activity is observed at a U.V. dose of 0-5+10(4) erg/mm2. From the kinetic analysis of the reaction and the incorporation of lambda 32P-labelled nucleoside triphosphates, it seems reasonable to conclude that U.V.-irradiation probably does not affect the DNA initiation sites, recognizable by RNA polymerase. The transcription products made with U.V.-irradiated lambda DNA are assymmetrical, and hybridized to the right half (R) and the left half (L) of lambda DNA with the ratio of R/L = 4/1, and they show a lower hybridizability than the transcripts with native lambda DNA. The initiation sites recognizable by RNA polymerase seem to be the same on both native and U.V.-irradiated lambda DNA though the transcription of U.V.-treated lambda DNA appears to terminate with rather short RNA chains.

Evaluation of acridine orange fluorescence test in viability studies on Escherichia coli

Cultures of Escherichia coli subjected to various treatments were studied for their viability loss, as well as for the changes in fluorescent response on staining with the fluorochrome acridine orange. The treatments employed were irradiation with gamma rays (two different dose rates), beta rays, and ultraviolet rays; thermal shock; thymine starvation; and streptomycin inhibition. Marked deviations from "Strugger effect" are seen. The differences in response observed at different dose rates of irradiation are discussed.