Accumulation of stem sugar and its remobilisation in response to drought stress in a sweet sorghum genotype and its near-isogenic lines carrying different stay-green loci

Near isogenic lines (NILs) of sweet sorghum genotype S35 into which individual stay green loci were introgressed, were used to understand the contribution of Stay green loci to stem sugar accumulation and its remobilization under drought stress exposure. Sugar and starch content, activities of sugar metabolism enzymes and levels of their expression were studied in the 3rd (source) leaf from panicle and the 5th (sugar storing) internode of the three lines, in irrigated plants and in plants exposed to a brief drought exposure at the panicle emergence stage. Annotation of genes in the respective Stay green loci introgressed in the NILs was carried out using bioinformatics tools. The leaves of NILs accumulated more photoassimilates and the internodes accumulated more sugar, as compared to the parent S35 line. Drought stress exposure led to a decrease in the starch and sugar levels in leaves of all three lines, while an increase in sugar levels was observed in internodes of the NILs. Sugar fluxes were accompanied by alterations in the activities of sugar metabolizing enzymes as well as the expression of genes related to sugar metabolism and transport. Remobilization of sugars from the stem internodes was apparent in the NILs when subjected to drought stress, since the peduncle, which supports the panicle, showed an increase in the sugar content, even when photoassimation in source leaves was reduced. Several genes related to carbohydrate metabolism were located in the Stay green loci, which probably contributed to variation in the parameters studied.

Combining additive manufacturing and catalysis: a review

A review on additive manufacturing (AM) applied to heterogeneous catalysis reveals enabling power of AM and challenges to overcome in chemical interfacing and material printability.

Rapid detection of rifampicin resistance in Mycobacterium tuberculosis by high-resolution melting curve analysis

SETTING

High-resolution melting curve analysis (HRMA) can be used to screen for mutations in genes without the need for specific probes, with low turnaround time and high cost-effectiveness.

OBJECTIVE

To detect the sensitivity and specificity of a line-probe assay (LPA) and HRMA in comparison with BACTEC™ MGIT™ 960 for the detection of rifampicin (RMP) resistance.

DESIGN

A total of 219 Mycobacterium tuberculosis isolates tested by MGIT 960 for RMP susceptibility were tested with HRMA and LPA. Discordant samples were processed for sequencing of the RMP resistance-determining region (RRDR) of the rpoB gene.

RESULTS

HRMA identified 93 of 103 (90.3%) isolates that were resistant and 113/116 (97.4%) that were susceptible on MGIT 960, with a sensitivity and specificity of respectively 90.3% and 97.4%. HRMA identified 117/119 (98.3%) LPA-susceptible and 94/100 (94%) resistant isolates, with 98.3% specificity and 94% sensitivity. Two isolates that were susceptible on LPA but resistant on HRMA showed silent mutations at 539 and 541 codons on sequencing, while 6 isolates that were susceptible on HRMA but resistant on LPA showed D516V (n = 4) and H526C/D (n = 2) mutations. Four isolates (3.9%) that were resistant on MGIT were susceptible on all three genotypic methods, which could be due to mutations outside the RRDR or efflux pumps.

CONCLUSION

HRMA shows good potential as a rapid screening tool for the detection of drug resistance.

Systemic jasmonic acid modulation in mycorrhizal tomato plants and its role in induced resistance against Alternaria alternata

Tomato plants colonised with the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum show systemic induced resistance to the foliar pathogen Alternaria alternata, as observed in interactions of other AM-colonised plants with a range of pathogens. The role of jasmonic (JA) and salicylic (SA) acid in expression of this mycorrhiza-induced resistance (MIR) against A. alternata was studied by measuring: (i) activity of enzymes reported to be involved in their biosynthesis, namely lipoxygenase (LOX) and phenylammonia lyase (PAL); and (ii) levels of methyl jasmonate (MeJA) and SA. Transcript abundance of some defence genes associated with JA and SA response pathways were also studied. Both LOX and PAL activity increased twofold in response to pathogen application to control plants. AM-colonised plants had three-fold higher LOX activity compared to control plants, but unlike controls, this did not increase further in response to pathogen application. Higher LOX activity in AM-colonised plants correlated with four-fold higher MeJA in leaves of AM-colonised plants compared to controls. Treatment of plants with the JA biosynthesis inhibitor salicylhydroxamic acid (SHAM) led to 50% lower MeJA in both control and AM-colonised plants and correlated with increased susceptibility to A. alternata, suggesting a causal role for JA in expression of MIR against the pathogen. Genes involved in JA biosynthesis (OPR3) and response (COI1) showed six- and 42-fold higher expression, respectively, in leaves of AM-colonised plants compared to controls. AM-colonised plants also showed increased expression of the SA response gene PR1 and that of the wound-inducible polypeptide prosystemin. Our results suggest that the systemic increase in JA in response to AM colonisation plays a key role in expression of MIR against A. alternata.

A direct observation of bacterial coverage and biofilm formation by Acidithiobacillus ferrooxidans on chalcopyrite and pyrite surfaces

To obtain a fundamental understanding of the population behaviour of Acidithiobacillus ferrooxidans at chalcopyrite and pyrite surfaces, the early stage attachment behaviour and biofilm formation by this bacterium on chalcopyrite (CuFeS2) and pyrite (FeS2) were studied by optical microscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The results indicate there was no significant difference in selectivity of bacterial attachment between chalcopyrite and pyrite. However, the result of ToF-SIMS analysis suggests that the surface of the pyrite was covered more extensively by biofilm than that of the chalcopyrite, which may indicate more extracellular polymeric substances (EPS) formation by bacterial cells growing on pyrite. EBSD and optical image analysis indicated that selectivity of bacterial attachment to chalcopyrite was not significantly affected by crystal orientation. The results also suggest that the bacterial population in defective areas of chalcopyrite was significantly higher than on the polished surfaces.

Cleidocranial dysplasia with autosomal dominant inheritance pattern

Cleidocranial dysplasia (CCD) is an autosomal dominant disease with a wide range of expression, characterized by clavicular hypoplasia, retarded cranial ossification, delayed bone and teeth development, supernumerary teeth, stomatognathic, craniofacial and skeletal abnormalities. This paper presents a case of CCD in a female with brachycephalic skull, depressed frontal bone and nasal bridge, hypoplastic middle one-third of face with mandibular prognathism and hyper mobility of both shoulders with associated radiographic features. Odontologist is often the first professional who patient of CCD approaches, since there is a delay in the eruption or absence of permanent teeth. The premature diagnosis allows a scope for proper treatment modalities, offering a better life quality for patient.

Adalimumab induced pulmonary sarcoid reaction

Sarcoidosis is a multisystem granulomatous inflammatory disease of unknown etiology. There is evidence that Tumor Necrosis Factor alpha (TNF-α) antagonists are useful in the treatment of advanced or refractory disease. However, sarcoidosis-like reaction has been reported with TNF-α blockade in other inflammatory conditions. Here we report a case of sarcoid-like reaction in a patient with psoriatic arthritis shortly after initiation of adalimumab therapy. Stopping adalimumab and systemic anti-inflammatory therapy with corticosteroids resulted in resolution of pulmonary symptoms and chest radiographic findings. Though TNF-α plays a critical role in pathogenesis of sarcoidosis, the development of sarcoid reaction with TNF-α blockade is paradoxical and the mechanism of this response remains unknown. TNF-α induced sarcoid-reaction could involve multiple organs. Its development with one agent does not preclude therapy with other TNF-α blockers.

DURABILITY TESTING OF SILICONE MATERIALS FOR PROTON EXCHANGE MEMBRANE FUEL CELL USE

Silicone resins are ideal candidates for proton exchange membrane fuel cells (PEMFC) sealing and gasketing. They have many advantages for PEMFC application, such as superior stability and longevity under harsh environments, low water absorption, and broad temperature range. However, as this work shows, silicone-based materials have one big drawback: low molecular weight siloxanes, oligomers, and/or degradation byproducts may readily migrate from the base material into the fuel cell membrane, forming glassy structures, reducing the mechanical durability, and ultimately fracturing the proton exchange membrane (PEM). A novel, in situ testing method has been developed to test the effect of siloxanes on PEMFCs. The mechanism for migration of cyclic siloxanes to the PEM interface, causing it to fail in a brittle fashion, is presented. A commercially available silicone gasket material was used as a case study to validate the mechanism. Optical microscopy, scanning electron microscopy, and inductively coupled plasma were used to perform failure analysis of the tested samples. Thermogravimetric analysis was used to measure the removal rate of low molecular weight cyclic siloxanes. Gas chromatography–mass spectrometry was used to separate the organic molecules off-gassing from the material at temperature and provide a mass spectrum of each component.

Rhabdomyosarcoma in middle ear of an adult: a rare presentation

Rhabdomyosarcoma of the middle ear is a rare tumor, even rarer in adults and has a very poor prognosis. We report here an unusual case of rhabdomyosarcoma in middle ear of an adult, mimicking chronic suppurative otitis media and facial nerve palsy.

Higher incidence of C677T polymorphism of the MTHFR gene in North Indian patients with vascular disease

Homocysteine is a sulfur-containing amino acid, which is derived from dietary methionine. Hyperhomocysteinemia has been implicated in vascular disease for over a decade now, and can be treated with B vitamins. Among its causes is polymorphism of the MTHFR gene, the most common being the cytidine to thymidine at position 677 (MTHFR C677T), which gives rise to three genotypes - normal homozygous CC, heterozygous CT and homozygous variant TT. An attempt was made to ascertain the prevalence of this MTHFR C677T in our population so that preventive measures may accordingly be instituted. Blood samples from 70 patients with vascular disease and 70 healthy controls were analyzed for plasma homocysteine levels (chemiluminescent immunoassay) and for the presence of MTHFR C677T (polymerase chain reaction analysis). Homocysteine was higher in the homozygous subjects (TT genotype) than in the heterozygous (CT genotype). In patients, the frequency of the C allele was significantly lower, and that of the T allele was significantly higher than the corresponding frequencies in controls. In conclusion, the North Indian urban population has higher homocysteine levels associated with the TT genotype. Hence, instituting measures towards reduction of homocysteine levels in the population would probably reduce the incidence and morbidity of vascular disease in our population.

Metastatic angiosarcoma presenting as diffuse alveolar hemorrhage

Angiosarcoma is a rare malignant neoplasm of the vascular or lymphatic endothelium. Diffuse alveolar hemorrhage is a rare presenting manifestation of angiosarcoma. We describe a case of pulmonary metastasis of angiosarcoma who presented with diffuse alveolar hemorrhage as initial manifestation.

Evidence for a sodium-dependent proline and glycine-betaine uptake in the cyanobacterium Nostoc muscorum

The cyanobacterium Nostoc muscorum is able to utilized proline and glycine-betaine as a nitrogen source under unstressed growth conditions. This cyanobacterium when grow in modified Chu No. 10 medium (without Na+) unable to utilized proline and glycine-betaine as a nitrogen source. Spontaneously occurring mutant clones defective in Na+ transport (Na+-R) were isolated and analyzed for proline and glycine-betaine utilization. The mutant phenotype showed normal heterocyst frequency and nitrogenase activity even in the medium containing 1 mM proline or 1 mM glycine-betaine, indicates the role of Na+ for proline/glycine-betaine uptake. The Na+-R mutant showed 100% survival at pH 11 and was simultaneously able to uptake and utilize proline/glycine-betaine at higher alkaline pH. This indicates that proline and glycine-betaine uptake systems are more efficient at higher alkaline pH. Since, the hypersaline environments are rich in Na+ contents and have alkaline pH, therefore it is suggested that the origin and evolution of specific compatible solutes may not depend only on the osmoregulatory role they play, but also on the other ecological factors operating simultaneously in the organism's niche.