373 research outputs found
Sex-partitioning of the <i>Plasmodium falciparum</i> stage V gametocyte proteome provides insight into <i>falciparum</i>-specific cell biology
One of the critical gaps in malaria transmission biology and surveillance is our lack of knowledge about Plasmodium falciparum gametocyte biology, especially sexual dimorphic development and how sex ratios that may influence transmission from the human to the mosquito. Dissecting this process has been hampered by the lack of sex-specific protein markers for the circulating, mature stage V gametocytes. The current evidence suggests a high degree of conservation in gametocyte gene complement across Plasmodium, and therefore presumably for sex-specific genes as well. To better our understanding of gametocyte development and subsequent infectiousness to mosquitoes, we undertook a Systematic Subtractive Bioinformatic analysis (filtering) approach to identify sex-specific P. falciparum NF54 protein markers based on a comparison with the Dd2 strain, which is defective in producing males, and with syntenic male and female proteins from the reanalyzed and updated P. berghei (related rodent malaria parasite) gametocyte proteomes. This produced a short list of 174 male- and 258 female-enriched P. falciparum stage V proteins, some of which appear to be under strong diversifying selection, suggesting ongoing adaptation to mosquito vector species. We generated antibodies against three putative female-specific gametocyte stage V proteins in P. falciparum and confirmed either conserved sex-specificity or the lack of cross-species sex-partitioning. Finally, our study provides not only an additional resource for mass spectrometry-derived evidence for gametocyte proteins but also lays down the foundation for rational screening and development of novel sex-partitioned protein biomarkers and transmission-blocking vaccine candidates
Enhancement of the bioproduction potential of an amylaceous effluent
9 pĂĄginas, 12 figuras, 4 tablasThe treatment of starchy effluents could provide the basis
for a series of simultaneous or alternative bioproductions
easily integrable into a system of greater economic
attraction that the simple production of SCP. In order to
define some of the possible options, this study uses an
amylaceous effluent for simultaneous production of SCP
and an amylolytic preparation which is partially consumed
in the saccharification of a parallel flow of the
same effluent concentrated by ultrafiltration with cutoff
at 100 kD.
With regard to the development of the above system,
this paper describes the problems associated with ultrafiltration,
the conditions that optimize saccharification
of the concentrate and the requirements of various possible
bioproductions that couM be obtained from the
saccharified concentrate.CICYT (project ALl 789-
9O).Peer reviewe
Structural characterization and release profile of omega-3 fatty-acids encapsulated in nanoemulsions
Omega-3 (-3) fatty-acids are functional compounds with various benefits such as reduction of cardiovascular diseases. However, these fatty acids degrade quickly, present low water solubility and an unpleasant aroma, which make essential their encapsulation. The encapsulation (e.g. nanoemulsion production) process can change structural properties, which can affect the behavior of the system when applied to food matrices and within the gastrointestinal tract.
The objective of this work was to characterize oil-in-water bio-based nanoemulsions with -3 using lactoferrin as a natural emulsifier, when submitted to different drying processes.
Nanoemulsions were produced using high-pressure homogenization (5 cycles, 20,000 psi) using 2 % (w/w) lactoferrin and 5 % (w/w) -3. Nanoemulsions were dried by nanospray-drying (Nano Spray dryer B-90HP, Buchi) and freeze-drying methods. Physical and morphological properties were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. Circular dichroism (CD) and FTIR-ATR were used to assess possible structural and chemical changes after dry treatments. Moreover, -3 release profile was studied in ethanol (20 % and 50 % (v/v)) at 25 ÂșC (simulation of food matrices) and at pH 7.4 and pH 2 at 37 ÂșC (simulation of different gastrointestinal phases).
DLS results showed that original size (170 nm) and zeta-potential (+30 mV) of nanoemulsions was not achieved after nanospray-drying process probably caused by protein agglomeration. CD and FTIR-ATR results revealed lactoferrin structural modifications after drying processes as well as a reduction of -helix and -sheet content, being this effect more evident on nanospray-drying samples. FTIR-ATR results showed shifts of the amide I and amide II bands in both drying processes samples. At 20 % ethanol, -3 began to release after 48h which could allow nanoemulsions incorporation in food products such as ice cream and mayonnaise.
This work provides useful information to design nanoemulsions aiming lipophilic compound encapsulation for food applications.info:eu-repo/semantics/publishedVersio
Development of bio-based nanoemulsions to improve physical and chemical stability of omega-3 fatty acids
The 19th Gums & Stabilisers for the Food Industry Conference: Hydrocolloid MultifunctionalityNowadays there is a high interest of food industry to develop nutritional food products. This concept
promoted the development of bio-based structures to encapsulate bioactive compounds and thus
enhance their physical and chemical stability during storage until the consumption. In this field
nanotechnology can offers several advantages, not only improving water solubility but also in the
increase of bioavailability of lipophilic bioactive compounds. Omega-3 polyunsaturated fatty acids (Ï-3
fatty acids) are known for their functional properties such as: improving cardiovascular health,
decrease inflammation, increase cognitive function, and influence on neurological and visual
development. However, Ï-3 fatty acids are highly susceptible to oxidation, have an intense odour and
present low water solubility, which makes its direct application in foods extremely difficult. In order to
reduce these problems, the nanoencapsulation, through the use of nanoemulsions can be used.
In this work, Lactoferrin (Lf), a protein derived from milk with a wide range of reported biological
activities (e.g. antioxidant, antimicrobial and cancer prevention) was used as natural emulsifier for the
development of oil-in-water nanoemulsions. Nanoemulsions were produced with a high-pressure
homogenizer applied for 5 cycles at 20000 psi. Different Lf concentrations (0.2; 0.6; 1; 2; 3; 4 and 5%
(w/w)) were tested. The nanoemulsions physical properties were evaluated in terms of size and ζ-
potential measurements using dynamic light scattering (DLS) and by surface tension using the Ring
method. The morphology of nanoemulsions were analysed by transmission electron microscopy
(TEM). The physical and chemical stability of these nanoemulsions was assessed during 50 days, at
storage temperatures of 4 ÂșC and 25 ÂșC, being the chemical stability of nanoemulsions was evaluated
by antioxidant activity measurements using DPPH radical scavenging assay. Results showed that
according to the Lf concentration used different properties were obtained. Nanoemulsions with Lf
concentrations between 2 and 5% (w/w) presented sizes around 160 nm and a ζ-potential higher than
+30 mV. For concentrations below 2 % (w/w), nanoemulsions presented sizes around 200 nm and a ζ-
potential bellow +30 mV. It was noticed that higher Lf concentrations lead to smaller sizes and higher
ζ-potential values. By increasing the Lf concentration was observed a decrease on superficial tension
of nanoemulsions. TEM measurements showed that nanoemulsions particles have defined spherical
shape. Results also showed that nanoemulsions with Lf concentration above 2 % (w/w) present better
properties (smaller sizes and higher ζ-potential) so the storage stability of these nanoemulsions were
assessed. Nanoemulsions stored at 4 ÂșC did not exhibit significant variations in size and ζ-potential
values, while at 25 ÂșC the nanoemulsions suffered an size increase (around 35 nm compared to initial
value) and a reduction in ζ-potential (around 20 mV compared to initial value) during storage. At these
conditions, it was also observed that nanoemulaions with Lf concentrations of 2 and 3 % (w/w) present
an instability (variations of size and ζ-potential) after 14 days of storage at 25 ÂșC, while for higher Lf
concentrations (4 and 5 % (w/w)) the changes only start to be noticed latter (after 29 days of storage).
Antioxidant activity did not demonstrate significant changes before and after storage at both
temperatures (IC50 was around 14 mg/g of solution). This work provides important information that can
be useful for the design of nanoemulsions aiming the encapsulation of lipophilic compounds for
pharmaceutical and food applications.info:eu-repo/semantics/publishedVersio
Microwave-assisted extraction of sulfated fucans from brown seaweed and evaluation of fungal strains for enzymesactive production toward this class of polysaccharide
Sulphated polysaccharides from brown seaweedss
comprise a complex group of macromolecules with
a wide range of important biological properties such
as anticoagulant, antioxidant, antiproliferative,
antitumoral, anticomplementary, anti-inflammatory,
antiviral, antipeptic and antiadhesive activities.
Fucoidan is one of the main sulphated fucan, mostly
interesting for their biological activities specially the
potential to inhibit HIV reverse transcriptase and the
possible application as active compound in
antiretroviral drugs. However, algae remain largely
unexploited and seaweeds can be found in sufficient
amount for the commercial exploitation. Usually,
most of the processes to recover sulfated
polysaccharides from natural sources consist in acid
extractions during long reaction times. Specific
enzymes able to degrade fucoidan matrix
(fucoidanases) are important tools to establish
structural characteristics and biological functions of
this polysaccharide. Such enzymes, have been only
isolated from marine organisms. Reports of fungal
microorganisms with enzymatic activity over this
sulfated-polysaccharide are scarce. The aims of the
present work were: 1) to recovery of sulphated
polysaccharides (fucoidan) by microwave-assisted
extraction under different operational conditions and
2) the identification of fungal strains able to growth
over fucoidan-based media and to produce active
fucoidanases
Extraction of sulfated polysaccharides by autohydrolysis of brown seaweed Fucus vesiculosus
The extraction of sulfated polysaccharides (fucoidan) by autohydrolysis (AH) of brown seaweed Fucus vesiculosus was studied. Experimental assays were performed under different conditions of temperature (160 to 200°C) and reaction time (10 to 30 min) according to a 22 central composite design, and the conditions able to maximize the fucoidan yield were selected. The alga degradation and the total sugar yield in the liquor after AH were also determined
to each experimental condition. The highest fucoidan yield (âŒ16.5% w/w) was obtained when the AH process was performed at 180°C for 20 min. This product was characterized by high-performance liquid chromatography, infrared analysis spectroscopy, and thermal gravimetric analyses, which verified the presence of fucose and galactose as main components (70:30% mol ratio, in average) and an SO3 content higher than 20%. AH process under optimum reaction
conditions was an effective method to recover fucoidan from F. vesiculosus. The use of this technology brings also important advantages from economical and environmental viewpoints since it does not require the use of chemical solvent and generates less waste when compared to conventional extraction procedures.R.M. Rodriguez-Jasso would like to thank the Mexican Science and Technology Council (CONACYT, Mexico) for Ph.D. fellowship support (grant number 213592/308679). The authors also thank Professor Isabel Sousa Pinto, Rita Araujo PhD from CII-MAR, University of Porto, and Bartolomeu de Souza PhD for the collaboration during the selection and collection of the seaweed used in this study
Kinetic and morphometric evaluation of fucoidanâdegrading fungal strains
Fucoidan is a sulfated fucose heteroâpolysaccharide found in brown algae. This compound has a
wide variety of biological activities including anticoagulant, antithrombotic, antitumoral and
antiviral (Alexeeva et al. 2002; Ellouali et al. 1993; McClure et al. 1992). Specific enzymes able to
degrade fucoidan matrix are important tools to establish structural characteristics and biological
functions of this polysaccharide. Such enzymes, called fucoidanases, have been only isolated from
marine organisms (Sakai et al. 2004; Giordano et al. 2006). Reports of fungal microorganisms with
enzymatic activity over this sulfatedâpolysaccharide are scarce.
Mycelial growth and morphology of filamentous fungi can be mathematically described by kinetic
models, through the estimation of specific growth rate of molds on plates containing target
polysaccharide as sole carbon source, using image processing techniques (Loera and Viniegra
1998). In this sense, the aim of this work was to identify fungal strains able to growth over
fucoidan media as sources of active fucoidanases, by quantification of kinetic and morphology
features, to establish the influence of media composition on growth patterns.
Aspergillus niger PSH, Penicillium purpurogenum GH2 and Mucor sp. 3P were the screened
strains. Different culture media with and without mineral salts were tested for microbial growth.
Fucoidan of Laminaria japonica and urea were used as carbon and nitrogen source. Radial growth
rate (Ur) was kinetically monitored measuring colony diameters. Hyphal length (Lav) and diameter
(Dh) were quantified by image analyses measurements.
All the evaluated strains were able to growth on different fucoidanâurea media, and their plate
invasion capacity and radial growth rate were directly proportional to measured morphometric
parameters. The three fungi strains synthesize acting metabolites toward fucoidan matrix, and
are important tools for the synthesis of sulfated fucanâdegrading enzymes. These results are, until
now, the first report of enzymes able to growth and degrade fucoidan obtained by terrestrial
fungus
Microwave-assisted extraction of sulfated polysaccharides(fucoidan)from brown seaweed
Sulfated polysaccharides (fucoidan) were recovered from brown seaweed Fucus vesiculosus by microwave-assisted extraction (MAE). Different conditions of pressure (30 to 120 psi), extraction time (1 to 31 min), and alga/water ratio (1/25 to 5/25 g ml-1) were evaluated during this process aiming to establish a condition to maximize the extraction results. The alga degradation (%), total sugar yield (%), and SO3 content (%) were also determined to each experimental condition. All the studied variables presented significant (p<0.05) influence on fucoidan yield. MAE at 120 psi, 1 min, using 1 g alga/25 ml water was the best condition for the fucoidan recovery. L-fucose was the main constituent of this polysaccharide, which also contained xylose and galactose. MAE under optimum reaction conditions was an effective method to recover fucoidan from Fucus vesiculosus. This method required short extraction times, and non corrosive solvents, resulting in reduced costs and being an environmentally friend technique.The financial support from Mexican Science and Technology Council (CONACYT, grant number: 2066071230415) and the Portuguese Foundation for Science and Technology (FCT) are gratefully acknowledged. The authors also thank Bruna Fonseca and Professor Teresa Tavares for the accessibility to the microwave assisted equipment; and Professor Isabel Sousa Pinto and Rita Araujo from CIIMAR - Interdisciplinary Centre of Marine and Environmental Research for facilitate the algae selection
Camel genetic resources conservation through tourism: A key sociocultural approach of camelback leisure riding
Camels are exotic elements, which can be comprised within adventure travel companies promoting ecotourism activities. Such recreations contribute to sustainable livelihoods for local communities and educational empowerment towards nature and its conservation. At present, some local camel breedsâ survival reduces to this animal-based leisure industry and its reliability to perform and promote customized services accurately. By conducting an on-site questionnaire to customers participating in camelback riding tours, we assessed the motivational factors affecting participation, satisfaction, and loyalty in this tourism segment that may have made it socially differentiated. The sixfold combination of staff performance, culture geography, diverse and humane close interaction, camel behavior and performance, sociotemporal context, and positive previous experience involves the elemental dimensions that explain customer satisfaction and return intention probability within this entertainment business. Customer knowledge is essential for stakeholders to build personalized riding experiences and align profits with environmental sustainability and biodiversity mainstream concerns into their everyday operations. In turn, domestic camel tourist rides could be managed as a viable path to nature conservation by helping endangered local breeds to avoid their functional devaluation and potential extinction
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