Waseem Safdar

Development and characterisation of antibacterial suture functionalised with N-halamines

Braided and biodegradable polyglycolide suture was antibacterially functionalised with N-halamines via layer-by-layer assembly technique. Multilayers of chitosan (polycation) and poly-sodium-p-styrenesulfonate (polyanion) were successfully coated via electrostatic assembly, followed by top layer of chitosan on polyglycolide suture. Upon chlorination of coated suture with dilute sodium hypochlorite solution, the amino groups of chitosan were transformed into N-halamine structures. The transformation was assessed by iodometric/thiosulfate titration, Fourier transform infrared spectroscopy and differential scanning calorimeter analysis. The surface morphology of coated suture was observed by scanning electron microscope and atomic force microscope. Chlorine loading, antibacterial efficacy and tensile strength of chlorinated sutures treated with two different molecular weights of chitosan were compared and evaluated. A general trend of linear increase in chlorine loadings of sutures with the increase in number of layers and solution concentration was found. The chlorinated suture with high molecular weight chitosan coating completely inactivated both Escherichia coli O157:H7 and Staphylococcus aureus bacteria within 15 min of contact time. The 3T3 mouse fibroblasts in vitro cell cytocompatibility studies demonstrated that antibacterial sutures have fairly good biocompatibility.

Effects of twenty standard amino acids on biochemical constituents, docosahexaenoic acid production and metabolic activity changes of Crypthecodinium cohnii

The influence of 20 standard amino acids was investigated on growth, lipid accumulation, docosahexaenoic acid (DHA) production and cell biochemical composition of Crypthecodinium cohnii. C. cohnii efficiently utilize organic nitrogen (predominantly threonine and to a lesser extent tyrosine and serine) as compared to inorganic nitrogen (NH4)2SO4. However, No significant effect was observed on major biochemical composition of C. cohnii (lipids, carbohydrates and proteins) under N limitation or supplementation with different N-sources. Key lipogenic enzymes glucose-6-phosphate dehydrogenase, ATP-citrate lyase, fatty acid synthase, malic enzyme, citrate synthase (CS), NAD+ and NADP+ dependent isocitrate dehydrogenase were shown to be vital in lipogenesis of C. cohnii. Our results indicated that the process of lipid accumulation in C. cohnii is growth-associated and does not depend upon the trigger of nitrogen depletion. This unusual behavior would suggest that the metabolism of the cells may not be entirely the same as in other lipid-accumulating microorganisms.

Comparative analysis of nine different small heat shock protein gene promoters in Oryza sativa L. subsp. indica

Small heat shock proteins (sHSPs), the intra cellular chaperons respond to high temperatures and other stresses, are expressed under the control of the heat shock factors, which recognize highly conserved cis-regulatory elements (CREs). The present study was designed to identify and compare nine different sHSP gene promoters from rice on the basis of their location on chromosomes, sequence similarities, evolutionary relationship and putative binding sites of transcription factors. Additionally, they were analyzed for their functional importance in the regulation of sHSP genes. For this, 5′ upstream region of nine sHSP genes from Oryza sativa was amplified, sequenced and analyzed. RFLP mapping approach using molecular linkage maps of three-way cross-population showed that OsHSP 16.9A, OsHSP 16.9B, OsHSP 16.9C and OsHSP C-II genes were clustered on the short arm of chromosome 1 with a 1238-bp overlapped sequence between OsHSP 16.9A and OsHSP 16.9B, whereas OsHSP 17.3, OsHSP 17.7, OsHSP 17.9, OsHSP 18.0 and OsHSP 26 genes were clustered on chromosome 3 with a 420-bp overlapped sequence between OsHSP 17.3 and OsHSP 18.0. Evolutionary analysis revealed that sHSPs that clustered on different chromosomes in the same specie showed high sequence similarity and evolved prior to the divergence of their localization. Eighteen CREs remained conserved among all sHSP gene promoters during evolution. These common regulatory elements are related to disease resistance, hormonal responses, light responses, seed storage proteins, tissue-specific expression, pollen development and other environmental stresses. Moreover, CCAATBOX1 was also found in all sHSP gene promoters involved in the regulation of heat shock response. Conclusively, promoter region of sHSP genes seems to be capable of driving genes expression during stress and genetic manipulation might be helpful in producing better quality rice.

An update on hypoallergenicity of peanut and soybean: where are we now?

Legumes are considered as one of the major sources of protein as well as providing other vital components of the diet. At the same time, unfortunately, the leguminous crops peanut and soybean also possess food allergens. The majority of legume allergens originate from four protein families and superfamilies ((i) cupins, (ii) prolamins, (iii) profilins and (iv) pathogenic related proteins larger group) and mainly induce IgE-mediated allergenic reactions. The ace strategy to manage the food allergy strictly encompasses avoiding the food allergens. Apart from numerous other alternative approaches for the treatment of food hypersensitivity, elimination of allergens from food crop(s) is a recent direction of research. Two important approaches have been successfully exploited to develop hypoallergenic leguminous crops: (i) lowering or removing the contents of allergy related proteins via germplasm lines screening and (ii) silencing the allergenic proteins encoding native genes via genetic transformation. Both of these strategies have yielded promising results in the production of peanut and soybean cultivars with low levels of allergic proteins. This current review will elaborate the efforts which have been made to develop hypoallergenic peanut and soybean cultivars to manage the legume allergy with a brief concluding debate on the challenges which still need to be addressed before such products could be launched for consumers in the market place.

Genetic assessment of the genus Pisum L. based on sequence specific amplification polymorphism data

The present study was conducted to analyze genetic diversity among 56 accessions of Pisum sativum, Pisum elatius, Pisum pumilio, Pisum fulvum and Podandrogyne brevipedunculata from Syria (42) and a set of 16 reference accessions from Israel (3), Ethiopia (2), Greece (2), Italy (2), Turkey (3), Tunisia (1) and Georgia (1). The study was based on the analysis of multiple data sets generated using sequence specific amplification polymorphism (SSAP) and associated morphological and ecogeographic data. The diversity analysis based on SSAP markers resulted in 83 scorable fragments in P. sativum, P. elatius (63), P. fulvum (62), P. pumilio (53), P. brevipedunculata (31) and P. abyssinicum (29). Genetic variability was measured as Nei’s gene diversity and maximum polymorphism was found in P. elatius (33.87%) and P. fulvum (32.74%) whereas minimum diversity was observed in P. brevipedunculata (12.48%). Pair wise band sharing among Pisum species was also calculated, significant band sharing was observed between P. fulvum and P. elatius, P. elatius and P. sativum and P. pumilio and P. elatius. The relationship among species as revealed by SSAP data could not significantly be correlated with those based on the agro-morphologic characters, suggesting that the two inferences are independent and estimates of genetic relations differently among Pisum taxa. The ecogeographic data associated with Pisum species (latitude, longitude) were also plotted using Arc View GIS 3.2 in order to show the distribution of species in Syria.