A microfluidic system for localised growth of biofilms and studies of realated biochemical kinetics

Nous avons développé une biopuce de microfluidique qui est capable de surveiller continuellement la population de cellules dans les biofilms en conditions d'écoulement laminaire bien contrôlées. Ce dispositif microfluidique est capable de modeler la formation des biofilms linéaires en utilisant une approche de flux basé sur un modèle. Les considérations de conception et méthodologie de fabrication d'un micro-bioréacteur à deux niveaux, inclus le flux basé sur un modèle (FT-μBR) qui génère un flux de croissance du biofilm entouré par les 3 côtés par un flux de confinement et inhibiteur de croissance. Grâce à une combinaison d'expériences et de simulations, nous avons évalué et exploité exhaustivement les paramètres de contrôle pour manipuler les dimensions du modèle de flux de croissance du biofilm. Ce dispositif est ensuite utilisé pour développer des modèles linéaires du biofilm avec des dimensions contrôlables. Une étude de validation de principe utilisant le dispositif démontre son utilité dans la réalisation des mesures de taux de croissance du biofilms dans différents environnements de force de cisaillement. Cela ouvre la voie à des études quantitatives sur les effets de l'environnement des cisaillements locaux sur les propriétés des biofilms et pour la synthèse d'une nouvelle génération de biomatériaux fonctionnels ayant des propriétés contrôlables.We have developed a microfluidic biochip that is capable of continuously monitoring cell population in biofilms under well-controlled laminar flow conditions. This microfluidic device capable of patterning linear biofilm formations using a flow-templating approach. The design considerations and fabrication methodology of a two level flow-templating micro-bioreactor (FT-μBR) generates a biofilm growth stream surrounded on 3 sides by a growth inhibiting confinement stream. Through a combination of experiments and simulations we comprehensively evaluate and exploit control parameters to manipulate the biofilm growth template stream dimensions. The FT-μBR is then used to grow biofilm patterns with controllable dimensions. A proof-of-principle study using the device demonstrates its utility in conducting biofilm growth rate measurements under different shear stress environments. This opens the way for quantitative studies into the effects of the local shear environment on biofilm properties and for the synthesis of a new generation of functional biomaterials with controllable properties

Facilitators of adherence to Self-management in type 2 diabetic patients: A phenomenological study

Abstract Introduction: Diabetes is chronic disease affecting all aspects of daily life and hence is a priority health care strategy. Its treatment needs a bio-psychosocial approach. One of the major problems in its management is patient noncompliance to therapeutic regimens. This qualitative phenomenological study aimed at assessing to patient experiences of factors facilitating self-management. Materials and Methods: Patients were recruited from the “Glands and Metabolism Research Center” and “Alzahra hospital” in Isfahan in 2006.

CAN I DO…? LIFE WITH TYPE II DIABETES: A PHENOMENOLOGICAL STUDY

Background: Diabetes is a chronic disease affects many aspects of daily life. We need a bio-psychosocial approach to patients and their problems in diabetes management. Since patient’s beliefs about health and disease will guide self management measures, a holistic understanding toward subject is necessary. The aim of this study was to identify and describe the lived experiences of patients with diabetes in a qualitative study. Methods: A descriptive phenomenological framework used to guide the project of inquiry. Eleven volunteered patients (6 men, 5 women) were recruited by purposed sampling from “Glands and Metabolism Research Center” and “Al-Zahra Hospital” of Isfahan in 2006. In-depth unstructured one to one interviews conducted and interview data were transcribed and analyzed for themes using collizi method. Results: Five themes were identified including; "Why I get", "Disease requirements", "Can I do", "Limitations", "Silent motion towards death". 3 first items belongs to participants' perception about diseases etiology, treatment, and their feeling about their situation, respectively. “Silent movement towards death” and “limitation” pointed to the patients' belief about limitation in nutrition and having a healthy child and nature of disease. Conclusion: Based on findings, patients’ beliefs about their disease and health situation can affect health behaviors and self-management, and act as barriers and facilitators in patient behaviors. Findings suggest considering this factor in self management preparing program

An efficient in vitro plantlet regeneration from shoot tip cultures of Curculigo latifolia, a medicinal plant

A procedure was developed for in vitro propagation of Curculigo latifolia through shoot tip culture. Direct regeneration and indirect scalp induction of Curculigo latifolia were obtained from shoot tip grown on MS medium supplemented with different concentrations and combinations of thidiazuron and indole-3-butyric acid. Maximum response for direct regeneration in terms of percentage of explants producing shoot, shoot number, and shoot length was obtained on MS medium supplemented with combination of thidiazuron (0.5 mg L−1) and indole-3-butyric acid (0.25 mg L−1) after both 10 and 14 weeks of cultures. Indole-3-butyric acid in combination with thidiazuron exhibited a synergistic effect on shoot regeneration. The shoot tips were able to induce maximum scalp from basal end of explants on the medium with 2 mg L−1 thidiazuron. Cultures showed that shoot number, shoot length, and scalp size increased significantly after 14 weeks of culture. Transferring of the shoots onto the MS medium devoid of growth regulators resulted in the highest percentage of root induction and longer roots, while medium supplemented with 0.25 mg L−1 IBA produced more numbers of roots

Administration of Bacillus subtilis strains in the rearing water enhances the water quality, growth performance, immune response, and resistance against Vibrio harveyi infection in juvenile white shrimp, Litopenaeus vannamei

In this study, vegetative cell suspensions of two Bacillus subtilis strains, L10 and G1 in equal proportions, was administered at two different doses 105 (BM5) and 108 (BM8) CFU ml−1 in the rearing water of shrimp (Litopenaeus vannamei) for eight weeks. Both probiotic groups showed a significant reduction of ammonia, nitrite and nitrate ions under in vitro and in vivo conditions. In comparison to untreated control group, final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) and digestive enzymatic activity were significantly greater in the BM5 and BM8 groups. Significant differences for survival were recorded in the BM8 group as compared to the control. Eight weeks after the start of experiment, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differences in shrimp survival between probiotic and control groups. Cumulative mortality of the control group was 80%, whereas cumulative mortality of the shrimp that had been given probiotics was 36.7% with MB8 and 50% with MB5. Subsequently, real-time RT-PCR was employed to determine the mRNA levels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and β-1,3-glucan- binding protein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was only significantly up-regulated in the BM5 group compared to the BM8 and control groups. These results suggest that administration of B. subtilis strains in the rearing water confers beneficial effects for shrimp aquaculture, considering water quality, growth performance, digestive enzymatic activity, immune response and disease resistance

Forage yield and quality of kenaf (Hibiscus cannabinus L.) for consumption as ruminant feed

This study was carried out to evaluate 40 kenaf accessions for forage yield and quality at Universiti Putra Malaysia in 2009. Forage yield and quality traits were measured at the initial flowering stage. The kenaf accessions showed highly significant variation for most of trait studied. Plant dry matter yield ranged from 5286 kg ha-1 (Everglade 41) to 16801 kg ha-1 (IX51). Crude protein content of the leaf ranged from 13.6% (G46) to 22.3% (75-71) and it was higher than stem which is ranged from 2.7 % (FDW-75-8) to 7.5 % (K465/117). Leaf ADF were significantly different among the accessions, where FDW 75-82 gave the highest (24.7%) while C74 gave the lowest (16%). Broad-sense heritability was highest for days to flowering (hB2= 97.6%) and lowest for CP of stem (h2= 11.2 %). In conclusion IX51, Cuba2032 (with high yield), 75-71 and Everglade 41 (with high CP content), were the most superior among the 40 kenaf accessions evaluated and were found highly potential for forage. These accessions can therefore be utilized in further breeding programs to produce new kenaf varieties with high feed value for ruminant consumption

Detection and identification of antibiotic biosynthesis genes in Bacillus subtilis strains

Two Bacillus subtilis strains L10 and G1, previously isolated from fermented pickles, were tested for antibacterial activity against Vibrio harveyi using a well-diffusion agar assay. Antibiotic biosynthesis genes were then detected in both bacterial strains and included the following genes: bacA, bacB and bacD genes for bacilysin production, ppsE/fenB gene for plipastatin/fengycin production, albF and albA genes for subtilosin production, and srfAB and sfP genes for surfactin production. Based on these results, two B. subtilis strains could be considered as potential biological control agents in aquaculture

Establishment of tissue culture protocols for Curculigo latifolia dryand and determination of uniformity among plantlets using SSR markers

Curculin found in Curculigo latifolia fruit has great potential for the pharmaceutical industry. Studies were conducted with the objectives of establishing a tissue culture protocol for C. latifolia and to determine uniformity among plantlets and their mother plants using SSR markers. Although the plants are found abundantly in Malaysia, commercial fruit production from superior varieties is at the early stage. Propagation through seeds and rhizomes are poor and planting using materials harvested directly from the forest is precarious as the genetics of this plant is understudied. Therefore tissue culture provides the means of producing true to type and uniform seedlings in mass numbers. Plants were collected from Jelebu, Negeri Sembilan and maintained under 70% shade with regular watering for at least six months. Petioles and shoot tips were used as explants but this resulted in very high in vitro contamination. Therefore, a sterilization protocol suitable for C. latifolia was developed. Sterilization and browning elimination were performed by pre-treatment with different antioxidants (citric acid, ascorbic acid and PVP (0.1%)), fungicide (bavistin 0.1%), and antibiotic (chloramphinicol 0.1%) on an orbital shaker for 9 hours followed by disinfecting with mercuric chloride (0.1%) for 5 minutes with 62.5% of shoot tips and 100% survival of explants after 45 days of culture. Petiole explants resulted in a higher percentage of explant (83.3%); however, there was more necrosis than with shoot tips, and there was a lower percentage of explant survival (49.2%). Thus, shoot tips were preferred for use as explants for regeneration. The direct regeneration of shoots from explants were optimized using Murashige and Skoog (1962) medium supplemented with different concentrations of single thidiazuron (TDZ) treatment (0, 0.5, 1, 1.5, 2 mgl-1) or in combination with IBA (0, 0.25, 0.5 mgl-1). The best results in terms of percentage of regeneration (77.8% and 83.3%), number of shoots (3.08 and 7.52) and shoot length (1.43 and 2.71 cm) were from treatment consisting of 0.5 mgl-1 TDZ and 0.25 mgl-1 after 10 and 14 weeks of culture, respectively. Meristems were elongated and roots were induced to generate a single plant in the control treatment. In this study it was also observed that a single concentration of 2 mgl-1 TDZ produced the highest percentage of scalp induction (77.8%). Scalp induction from shoot tip explants on MS medium with different concentrations of TDZ (0, 1, 2, 3, 4 mgl-1) showed that TDZ at a concentration of 3 mgl-1 was the best treatment for percentage of scalp induction (83.3%). In determining the growth pattern and best time for sub-culturing, the scalp weighing 1.1 ± 0.02 g was transferred onto MS medium containing 3 mgl-1 TDZ. This confirmed that four weeks interval was the best time for scalp sub-culturing. Scalp maintenance studies were performed on MS medium supplemented with different concentration of TDZ (0, 1, 2, 3, 4 mgl-1) with sub-culturing at four week intervals for three subcultures. The results indicated that 3 mgl-1 was the best concentration of TDZ for scalp maintenance (5.91 g) and the highest growth index (4.91) was obtained after the third subculture. Root induction and elongation studies were performed by separating regenerated shoots longer than 2 cm and culturing onto MS medium supplemented with different concentrations of IBA (0, 0.25, 0.5, 0.75 mgl-1). Shoots sub-cultured every four weeks showed that MS medium devoid of plant growth regulators was the best treatment for percentage root induction (86.7%) and root length (4.87 cm), but IBA at a concentration of 0.25 mgl-1 induced more roots (7.64) after eight weeks of culture. SSR markers were developed using 3′ and 5′ anchored ISSR markers. Amplified PCR products were ligated into vector and transformed into E.coli after purification. The positive clones were sequenced and SSR primers were designed using the PRIMER3 software (http:// www.genome.wi.mit.edu/cgibin/ primer/primer3.cgi). These primers were tested on 12 accessions of wild C. latifolia collected from all states of Peninsular Malaysia. From the 33 designed SSR primers, 22 primers were able to amplify C. latifolia target DNA and 11 primer pairs were polymorphic. The number of observed alleles (Na) per locus ranged from three to six. The allele size was between 141 and 306 bp. The observed heterozygosity ranged from 0.00 to 0.37, whereas the expected heterozygosity ranged from 0.52 to 0.81. The polymorphic information content (PIC) value of each locus was between 0.59 and 0.81, with an average of 0.67 showing that the primers were highly polymorphic. Genetic variations observed in the mother plants when they were analyzed using the 11 primers. Plantlets from in vitro cultures showed the same allele sizes when compared to their mother plants and generic uniformity was observed among the plantlets. Plantlets reached 2.5 cm in height before separation from explants and sub-culturing thus avoiding somaclonal variations. The plantlets were then prepared for acclimatization and transfered to the nursery. This study demonstrated a new breakthrough for producing uniform plantlets from in vitro cultures for C.latifolia. It established a sterilization technique, optimal conditions for direct and indirect regeneration of uniform plantlets and finally provided a means of producing seedlings from superior hybrids with desirable fruits