Nam Prakash

Ultrastructural Studies of conidiogenesis ofAscochyta rabiei, the causal Organism of chickpea blight

Studies employing transmission (TEM) and scanning (SEM) electron microscopy revealed that conidiogenous cells of the chickpea blight fungus,Ascochyta rabiei (Pass.) Labr., resembled phialides in most of their features. The phialides were generally of a simple type, but occasionally they proliferated in a percurrent fashion. There is enough evidence to suggest that the fungus is better placed in genusPhoma. SEM has been employed for the first time to study internal details of fructifications of a closed type in coelomycete fungi.

Control of minicell producing cell division by cAMP-receptor protein complex in Escherichia coli

SummaryIt has been established that the strain CA8000 of Escherichia coli K 12 produces minicells. This phenotype of CA8000 has been shown to be suppressed by additional mutations in cya or crp genes. Minicell production by cya+crp+min bacteria is probably a consequence of error, introduced by horizontal growth, in the selection of site on the envelope for initiation of hemispherical growth.

Synthesis and Development of Starch Granules in High Lysine Barley Grains

Electron microscopy studies of developing endosperm have shown differences in the synthesis and development of starch granules between high lysine mutant Notch-2 and parent NP 113. The starch granules in Notch-2 were modified and did not develop into characteristic oval granules. Based on iodine absorption and phospholipids analysis, it is suggested that the presence of phospholipids impairs the development of starch granule in Notch-2. This is further confirmed by higher lipid density across starch granule in mutant Notch-2, and its absence in NP 113. Amylopectin from mutant differs from that of NP 113. The results indicate that the lack of geometry and smaller size of starch granules in Notch-2 is ultimately due to specific interaction of lipids with developing starch granules, and this leads to decreased yield.

Protein Bodies at Early Stages of Development in High Lysine Mutant Notch-2 and Parent NP-113 Barley

In barley parent NP-113, endospermic protein bodies originate on rough endoplasmic reticulum, either as electron transluscent vesicles or as very small, spherical, electron dense protein bodies, These are translocated to vacuoles tor enlargement and subsequent storage, Endospermic protein bodies of Notch-2 high lysine mutant are either vacuolar, or confined to distended cisternae of smooth endoplasmic reticulum. Vacuolar protein bodies are of two types one, flocculent, which loosely fill up almost the entire vacuolar space; two, spherical, relatively compact and granular, Protein bodies, confined to smooth endoplasmic reticulum are small, spherical, electron dense or electron transluscent, These protein bodies fuse to form electron dense proteinaceous masses which are deposited in the cytosol due to disruption of the confining smooth endoplasmic reticulum.

The interfibrillar phase in poly(ethylene terephthalate) fibre

Abstract Transmission electron microscopy (TEM) at high magnification of thin cross-sections of drawn multifilament poly (ethylene terephthalate) yarn and of this yarn after heat-setting in the slack state at 250°C and in the taut state at 258°C is shown to provide evidence for the existence of crystallites whose lateral dimensions are consistent with those measured from wide-angle X-ray diffraction (WAXD). The denser, crystalline microfibrils appear to be separated by interfibrillar material of lower density in all the samples examined. The electron micrographs bring out the important differences in the morphologies of the three samples, the implications of which are critically examined.

Amyloplasts and Starch Characterization in High Lysine Barley Mutant

Starch granules of Notch-2 high lysine barley mutant are small, irregular in shape and show a virtual loss of birefringence and a higher gelatinization temperature, compared to parent NP-113. Starch polymer of Notch-2 is qualitatively different from parent, as evidenced by X-ray diffractograms. There is a higher incidence of V-pattern at early development as also at maturity in mutant as compared to parent. Intensities corresponding to B-pattern are present at early development in both parent and mutant. B-pattern persists at maturity in mutant, while it is replaced by A-pattern in parent. Amyloplasts of mutant are modified in contrast to normal, oblong amyloplasts of parent. Modified amyloplasts show loss of grana, increased granulation and lipid droplets. Extensive lipid complexing with starch polymers in mutant is indicated and possible commercial and nutritional potentials speculated.

Studies on Symbiotic Properties of Purine Auxotrophs of Strain Rmd 201 of Rhizobium Meliloti

The knowledge of the process of infection thread formation and establishment of functional nodules still remains obscure at molecular level. Yet studies on various rhizobial mutants clearly imply that certain deficiencies of bacteria can severely limit normal symbiotic process.

Isolation and characterization of gsv mutants of grain pea pisum sativum having white stem and green leaflets

Two Gsv- mutants have been isolated in mutagenized grain pea (Pisum sativum). A nuclear gene is affected in each mutant. The Gsv- plants are recessive homozygotes (gsv/gsv). They bear white stems and green leaves; the petiole, rachis, and veins on stipules and leaflets are also white. In the Gsv- plants, the stem is devoid of chlorophylls, although normal amounts of chlorophylla andb are present in leaflets. Mature chloroplasts and CO2 reduction ability are present in mesophyll tissue of leaves but absent in stem. The characteristics of Gsv- mutants allow the conclusion that the genes involved in chloroplast development and photosynthetic functions are regulated by different nuclear genes in mesophyll leaf cells on the one hand and green cells of stem and related tissues in functionally different segments of shoot on the other. It is proposed that segment-wise genetic control of photosynthesis in shoot is a rule among higher plants.

Contact electron micrography for characterization of paper in a transmission electron microscope: a new technique

Modern electron microscopes are usually fitted with a plate camera system for recording high-resolution electron micrographs. In this paper a simple method of using this plate camera for recording a contact micrograph of thin paper on photographic cut sheet, using accelerated electrons at 80 to 100kV in a Philips transmission electron microscope has been described and discussed. Results indicate that the scattered electrons through the sheet of paper do record the structural morphology and help in characterization of paper and its quality. In addition to paper technology, this technique may find potential applications in polymer film and solid state industries and several other areas which require characterization of thin specimens.

Type 1 fimbriation is negatively regulated by cyclic AMP and its receptor proteinvia conjugative plasmid F inEscherichia coli K-12

AbstractsExpression of fimbriation was studied inEscherichia coli K-12 CA8000 HfrH, and itscya, crp and MS2 resistant mutants. The cells of cya+ crp+ parent strain were observed to be flagellated bacilli, lacking fimbriae, unable to agglutinate erythrocytes and deficient in ability to produce surface pellicle during growth in stationary culture. The cells ofcya andcrp mutants were observed to be cocci or coccobacilli devoid of flagella, having haemagglutinating activity, fimbriated and capable of producing surface pellicle in stationary cultures. The fimbriation and haemagglutinating activities were lower incya mutants grown with cAMP supplementation. Thecya andcrp mutants produced relatively small, smooth and compact colonies consisting mostly of fimbriated cells, like those of earlier described Fimσ mutants. Thecya+ crp+ MS2 resistant mutant produced large sized colonies like those of parent but was deficient in conjugal donor ability. It resembledcya andcrp mutants in haemagglutinating and fimbriation properties. Thecya andcrp mutants have been earlier shown to be deficient in several Tra functions including conjugal donor ability. It is concluded thatEscherichia coli K-12 cells express fimbriation when Tra functions of F-plasmid carried in them are not expressed either due to deficiency of active cAMP-receptor protein complex or mutation in F-plasmid or when F-plasmid is absent.