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PubMed2006

Increased leptin expression in the dorsal vagal complex suppresses adiposity without affecting energy intake and metabolic hormones.

OBJECTIVE: Increased leptin transgene expression locally in hypothalamic sites suppresses weight and energy intake, enhances thermogenic energy expenditure, and differentially modulates metabolic hormones for an extended period. We evaluated whether a similar localized expression of leptin transgene in the dorsal vagal complex (DVC) in the caudal brain stem that also displays the biologically relevant leptin receptor would reproduce these varied responses and thus demonstrate functional connectivity between the hypothalamus and DVC. RESEARCH METHODS AND PROCEDURES: Adult female rats were microinjected with a recombinant adeno-associated virus encoding either rat leptin or green fluorescent protein gene (control) in the DVC. Food intake and body weight were monitored weekly, and metabolic variables were analyzed at the end of 10 weeks. RESULTS AND DISCUSSION: Increased leptin transgene expression in the DVC suppressed the time-related increase in body weight accompanied by a transient decrease in food intake at week 1 post-injection and little effect on thermogenic energy expenditure. That suppression of weight was due to decreased adiposity is shown by the markedly suppressed white adipose tissue-derived hormones, leptin and adiponectin. Circulating concentrations of pancreatic insulin, gastric ghrelin, and glucose levels were unchanged. This segregation of the varied effects of leptin expression in hypothalamic sites vs. DVC endorses the view that among the various endocrine organs under sympathetic nervous system control, only those leptin-activated neural circuits in the hypothalamus that suppress weight and adiposity on a long-term basis transverse through DVC en route to white adipose tissue.

Adiponectin↗

PubMed2006

Subacute effects of transgenic crylab bacillus thuringiensis corn litter on the isopods Trachelipus rathkii and armadillidium nasatum.

Laboratory studies were conducted to investigate the subacute effects of transgenic Cry1Ab corn leaf material containing Bacillus thuringiensis (Bt) protein on the terrestrial isopods Trachelipus rathkii and Armadillidium nasatum. Survival and growth were measured for eight weeks in isopods fed leaf material of two Bt11 corn varieties, two Monsanto 810 (Mon810) corn varieties, and the isolines of each. Total lipid and protein content of the organisms was measured to examine effects on energetic reserves. Armadillidium nasatum individuals in all treatments responded similarly. For T. rathkii, no statistically significant effect of Bt was observed, but statistical differences were observed in growth between hybrids. Protein and sugar content of the food were found to be correlated with the differences in growth for T. rathkii. Total protein content was higher in T. rathkii and A. nasatum fed material with higher protein and sugar content. A trend toward less growth in T. rathkii on Bt corn varieties versus their isolines triggered a concentration-response assay with purified Cry1Ab protein. No adverse effects of purified Bt protein were observed. These results indicate that little hazard to T. rathkii and A. nasatum from Bt corn leaf material from these hybrids exists. However, nutritional differences in corn hybrids contributed to differences in isopod growth.

Animals↗

PubMed1993

Designer enzyme and cell applications in industry and in environmental monitoring.

Renewed world interest in enzyme biotechnological industries now derives from the expectation that many new biocatalysts will be created by genetic engineering associated with protein engineering designer techniques, or by chemical modification of existing enzymes by use of protein tailoring methods. The biocatalysts produced are mainly enzymes, abzymes (catalytic antibodies) and synzymes (synthetic analogues or mimics), and these will be used in industry, synthesis, therapy: and in bioanalysis of components of foodstuffs, and the environment including water, air and soil. The biocatalysts, including whole cells, are firstly incorporated into a particular bioreactor form by use of enzyme engineering techniques such as immobilization, and are then used, as appropriate, to modify their substrates. Improved processing or enhanced products are thereby achieved in the case of manufacturing industry: or monitoring signals are generated, often in the form of a measurable change in current flow, in the case of environmental biosensors. Designer enzymes and cells can be made now for identified applications where the presently available biocatalysts are inadequate, incompatible or uncompetitive.

Biotechnology↗

PubMed2004

[Improving the nutritional value of plant foods through transgenic approaches].

The most nutrients required in the human diet come from plants. The nutritional quality of plant products affects the human healthy. The advance of molecular cloning and transgenic technology has provided a new way to enhance the nutritional value of plant material. Transgenic modification of plant nutritional value has progressed greatly in the following aspects: improving the quality, composition and levels of protein, starch and fatty acid in different crops; increasing the levels of antioxidants (e.g. carotenoids and flavonoids); breeding the new type of plants with medical value for human. To date, many transgenic plants with nutritional enhancement have been developed. These transgenic plant products could be directly used as human diet or as valued materials in developing the "functional food" with especial nutritional quality and healthy effects after they are approved by a series of evaluations on their safety and nutritional efficiency for human being. We designed new zinc finger transcription factors (ZFP-TFs) that can specifically down-regulate the expression of the endogenous soybean FAD2-1 gene which catalyzes oleic acid to linoleic acid. Seed-specific expression of these ZFP-TFs in transgenic soybean somatic embryos repressed FAD2-1 transcription and increased significantly the levels of oleic acid, indicating that the engineered ZFP-TFs are capable of regulating fatty acid metabolism and modulating the expression of endogenous genes in plants.

Antioxidants↗

PubMed2005

Genetically engineered vaccines.

The application of recombinant DNA technology to allergen research has provided the sequence information and genetic material to produce new types of allergy vaccines. One general strategy has been to use the knowledge to produce synthetic peptides that represent selected T-cell or B-cell epitopes. The production of genetically engineered allergens provides an alternative strategy to construct hypoallergenic vaccines, which can provide a better and less selected representation of the epitopes. Many strategies have been used to produce such hypoallergens, and their ability to reduce allergenicity has been amply demonstrated by skin and nasal provocation tests. The retention of T cell-stimulating activity has also been demonstrated, and a consistent feature of the vaccines has been, despite the reduced immunoglobulin E (IgE)-binding reactivity, the ability to induce anti-allergen IgG antibody. The lead hypoallergens have been polypeptide fragments and trimeric constructs of the birch allergen Bet v 1. A clinical trial with these medicaments has shown the ability to modify IgE and IgG antibody production, skin test reactivity, and symptom scores. This is the first trial of a recombinant allergy vaccine, and it has set a benchmark for further studies. A new generation of hypoallergens is now being produced based on the detailed knowledge of the tertiary structures of the allergens and of the T-cell and B-cell epitopes. The modifications have been made to change the topography of the allergens while retaining a stable, folding structure. In the case of Bet v 1, tertiary structures of hypoallergens have been determined. Structurally modeled hypoallergens have been produced for pollen, venom, food, and latex allergens, with promising characteristics from preclinical studies.

Allergens↗

PubMed2001

A potential role of central insulin in learning and memory related to feeding.

1. Hypothalamic insulin (HI) is well known for its role in feeding regulation. In addition, its concentration is modified in response to meals. Recent studies suggest that brain insulin participates in memory processes, possibly through stimulation by glucose. 2. The present microdialysis study focused on local in vivo regulation of HI by glucose and on the effects of aging on HI, since aging is characterized by deterioration of memory, body weight regulation, and central glucose utilization. Glucose (8 mM) infused for 5 min increased extracellular HI levels rapidly, by 4.6-fold, and cerebellar insulin levels by 0.4-fold only, suggesting a specific area-dependent regulation of HI by glucose. Neither insulinemia nor glycemia were affected, suggesting a central mechanism. The same dose of glucose induced a modest (0.4-fold), delayed (45 min) increase in hypothalamic serotonin, suggesting that the effect of glucose on HI is independent of a previously defined local serotonin-induced insulin release. HI levels in old normal weight rats were half the levels of young rats. In genetically old obese (fa/fa) Zucker rats, HI concentration was 30% of that in young normal rats, suggesting a deterioration of HI availability when aging and obesity are combined. 3. The above results, in line with recent considerations on a potential role of central insulin in learning and memory, suggest particular effects of HI on feeding and memory and probably on a specific "memory for food."

Age Factors↗

PubMed2006

Current status of regulating biotechnology-derived animals in Canada: animal health and food safety considerations.

Development of an effective regulatory system for genetically engineered animals and their products has been the subject of increasing discussion among researchers, industry and policy developers, as well as the public. Since transgenesis and cloning are relatively new scientific techniques, transgenic animals are 'novel' organisms for which there is limited information. The issues associated with the regulation of transgenic animals pertain to environmental impact, human food safety, animal health and welfare, trade and ethics. It is a challenge for the developers to prove the safety of the products of biotechnology-derived animals and also for regulators to regulate this increasingly powerful technology with limited background information. In principle, an effective regulatory sieve should permit safe products while forming a formidable barrier for those posing an unacceptable risk. Regulatory initiatives for biotechnology-derived animals and their products should be able to ensure high standards for human and animal health, a sound scientific basis for evaluation; transparency and public involvement, and maintenance of genetic diversity. This review proposes a regulatory regime that is based on scientific risk based assessment and approval of products or by-products of biotechnology-derived animals and its application in context to Canadian regulations.

Animal Welfare↗

PubMed1994

Opportunities for manipulating the seed protein composition of wheat and barley in order to improve quality.

Wheat and barley are the major temperate cereals, being used for food, feed and industrial raw material. However, in all cases the quality may be limited by the amount, composition and properties of the grain storage proteins. We describe how a combination of biochemical and molecular studies has led to an understanding of the molecular basis for breadmaking quality in wheat and feed quality in barley, and also provided genes encoding key proteins that determine quality. The control of expression of these genes has been studied in transgenic tobacco plants and by transient expression in cereal protoplasts, providing the basis for the production of transgenic cereals with improved quality characteristics.

Amino Acid Sequence↗

PubMed2001

Transgenic DNA introgressed into traditional maize landraces in Oaxaca, Mexico.

Concerns have been raised about the potential effects of transgenic introductions on the genetic diversity of crop landraces and wild relatives in areas of crop origin and diversification, as this diversity is considered essential for global food security. Direct effects on non-target species, and the possibility of unintentionally transferring traits of ecological relevance onto landraces and wild relatives have also been sources of concern. The degree of genetic connectivity between industrial crops and their progenitors in landraces and wild relatives is a principal determinant of the evolutionary history of crops and agroecosystems throughout the world. Recent introductions of transgenic DNA constructs into agricultural fields provide unique markers to measure such connectivity. For these reasons, the detection of transgenic DNA in crop landraces is of critical importance. Here we report the presence of introgressed transgenic DNA constructs in native maize landraces grown in remote mountains in Oaxaca, Mexico, part of the Mesoamerican centre of origin and diversification of this crop.

Agrobacterium tumefaciens↗

PubMed2006

Molecular mechanism of mutagenesis induced by olaquindox using a shuttle vector pSP189/mammalian cell system.

Olaquindox, a quinoxaline 1,4-dioxide derivative from quindoxin, is widely used as an animal growth promoter in China. We tested olaquindox as a mutagen in a SV40-based shuttle vector pSP189 and African green kidney cell (Vero E6 cell line) system to define the safety of olaquindox as a food-additive for animals. When applied at 6.6 microg/ml, olaquindox caused 12 times higher mutation frequency in comparison to untreated controls. More than 70% of base substitutions happened at G:C base pairs featuring G:C to T:A or G:C to A:T conversions. Frequency of point mutations for in vitro modified plasmids was also dramatically increased from the spontaneous background level. Olaquindox-induced mutations did not occur randomly along the supF shuttle vector, but instead, had a hot spot at base pair #155 which accounts for 37% of total mutations. Olaquindox-induced mutations also showed sequence-specificity in which most point mutations occurred at site N in a 5'-NNTTNN-3' sequence while most tandem bases deletion and rearrangement were seen at the 5'-ANGGCCNAAA-3' sequence. We conclude that olaquindox induces DNA mutation, therefore, should not be used as an additive to promote animal growth.

Animals↗

PubMed2002

Production of a freeze-thaw-stable potato starch by antisense inhibition of three starch synthase genes.

The use of unmodified starches in frozen foods is severely limited by the undesirable textural changes that occur after freezing and thawing. Retrogradation of glucan chains leads to syneresis, a separation of the starch gel and water phases. Stabilization of the starch structure is normally achieved by chemical modification to prevent these changes from occurring. We have now created a freeze-thaw-stable potato starch by alteration of starch composition and structure by genetic modification. An amylose-free starch with short-chain amylopectin was produced by simultaneous antisense downregulation of three starch synthase genes. This starch is extremely freeze-thaw-stable and shows no syneresis even after five freeze-thaw cycles. The use of this starch has potential for environmental and consumer benefits because its production requires no chemical modification.

Amylopectin↗

PubMed2006

A NAC Gene regulating senescence improves grain protein, zinc, and iron content in wheat.

Enhancing the nutritional value of food crops is a means of improving human nutrition and health. We report here the positional cloning of Gpc-B1, a wheat quantitative trait locus associated with increased grain protein, zinc, and iron content. The ancestral wild wheat allele encodes a NAC transcription factor (NAM-B1) that accelerates senescence and increases nutrient remobilization from leaves to developing grains, whereas modern wheat varieties carry a nonfunctional NAM-B1 allele. Reduction in RNA levels of the multiple NAM homologs by RNA interference delayed senescence by more than 3 weeks and reduced wheat grain protein, zinc, and iron content by more than 30%.

Amino Acid Sequence↗

PubMed2003

Engineering fructan metabolism in plants.

Fructans, or polyfructosylsucroses, are storage carbohydrates present in many higher plants. They are also considered healthy food ingredients. Engineering crops into high level production of specific fructan molecules is one of the mayor strategic research goals. Understanding the properties of fructosyltransferases is important, in order to direct the synthesis of fructans. In plants at least two fructosyltransferases are needed to synthesise fructans. One enzyme synthesises the fructan trisaccharide 1-kestose, the next enzyme uses 1-kestose for elongation and/or modification, producing longer fructans. The specificity of fructosyltransferases determines the type of glycosidic bond formed and the donor and acceptor substrates used. This enables the synthesis of many structurally diverse fructans. The production of these molecules in crops such as sugar beet and potato makes the commercial use of fructans feasible.

Biotechnology↗

PubMed1994

Dyslipidemia and coronary artery disease.

Genetically determined and metabolically induced disturbances in lipid metabolism, as manifested in several types of dyslipidemia, have been shown to be causally related to the development of coronary artery disease (CAD). A diversity of clinical and angiographic studies has been made to evaluate the linkage between plasma lipid-control therapy in the development of initial and recurrent cardiovascular events. The plan of treatment invariably begins with a low-fat, low-cholesterol diet before initiation of drug therapy. However, many patients have difficulty in adhering to the low-fat diet. Fortunately, metabolic studies show that foods which contain fats rich in stearic (saturated) and oleic (monounsaturated) fatty acids may be given in limited amounts to boost patients' compliance to a low-fat diet and to prevent their blood lipids from rising to abnormal levels. A bile acid sequestrant (cholestyramine or colestipol) is the first-line drug for control of hypercholesterolemia. Either gemfibrozil or gemfibrozil plus niacin is prescribed to raise high-density lipoprotein (HDL) levels of CAD patients. Approval of two HMG CoA reductase inhibitors, pravastatin and simvastatin, by the FDA gives physicians the additional flexibility of employing a single or a combination drug therapy for optimal control of dyslipidemia. The association of low serum cholesterol level (< 160 mg/dl) with increase in noncardiac mortality has prompted health professionals to consider modifying the universal screening and treatment of serum cholesterol in children and young women and to use hypolipidemic drugs in patients judiciously.

Arteriosclerosis↗

PubMed2001

[Current features of food allergies: the need of allergy surveillance].

The prevalence of food allergy in European populations has been evaluated at between 1.8 and 4.4%. In the French population it is 3.24%. This frequency, as well as the gravity of some manifestations, has already led to preventive and curative measures being taken in school settings. This increase is related to multiple environmental factors: changes in intestinal microflora, early diversification of foods in children, interference of drugs favoring clinical severity in adults. Allergenicity can be modified by food industry techniques. The appearance of novel foods (exotic proteins or those derived from animal feed, and soon GMOs), the growing use of food proteins as ingredients, constitute new risks. The absence of validated experimental methods for evaluating the allergic risk of food proteins makes it necessary to implement a policy of allergy vigilance for novel foods. Studies concerning the allergic risk for lupin flour, a new ingredient used in baked goods, are given as an example. They indicate the frequency of sensitization and cross peanut-lupin flour allergy, the low reactive threshold, indicating the risk of the level of incorporation presently allowed. They make possible current screening for this allergy in the population. Allergy vigilance is a recent concept that aims to set up surveillance of food allergy risks in a manner analogous to that of pharmacovigilance for drugs. A project for creating such a structure is being discussed. Although the central structure remains at the initiative of the Agence Française de Sécurité Sanitaire de l'Alimentation (French Agency for Food Safety) and the Institut de Veille Sanitaire (Institute of Health) the authors specify what a peripheral network of allergists should be, analyze the desired content of the bi-directional flow of information, and propose envisaging an intermediate regulatory organization, specialized in the diagnosis and treatment of food allergies. The ongoing idea is that environmental pressures on the genetics of atopic disease lead to a continuum of IgE-dependent responses towards all the potential allergens in the entire population. Consequently, the creation of such a structure is advised in the name of the Precautionary Principle.

Adolescent↗

PubMed2002

Behavioural models of population growth rates: implications for conservation and prediction.

Conservation biologists often wish to predict how vertebrate populations will respond to local or global changes in conditions such as those resulting from sea-level rise, deforestation, exploitation, genetically modified crops, global warming, human disturbance or from conservation activities. Predicting the consequences of such changes almost always requires understanding the population growth rate and the density dependence. Traditional means of directly measuring density dependence are often extremely difficult and have the problem that if the environment changes then it is necessary to remeasure the density dependence. We describe an alternative approach that does not require such long datasets and can be used to predict the density dependence under novel conditions. Game theory can be used to describe behavioural decisions that individuals make in response to interference, prey depletion, territorial behaviour or social dominance, and the resultant fitness consequences. It is then possible to predict how survival or reproductive output changes with population size. From this we can then make predictions about the responses of populations to environmental changes. We will illustrate how this can be applied to a range of species and a range of applied problems.

Animals↗

PubMed2006

Daily timed meals dissociate circadian rhythms in hepatoma and healthy host liver.

Dividing cells, including human cancers, organize processes necessary for their duplication according to circadian time. Recent evidence has shown that disruption of central regulation of circadian rhythms can increase the rate at which a variety of cancers develop in rodents. To study circadian rhythms in liver tumors, we have chemically induced hepatocellular carcinoma in transgenic rats bearing a luciferase reporter gene attached to the promoter of a core circadian clock gene (Period 1). We explanted normal liver cells and hepatomas, placed them into short-term culture, and precisely measured their molecular clock function by recording light output. Results show that isolated hepatocellular carcinoma is capable of generating circadian rhythms in vitro. Temporally restricting food availability to either day or night altered the phase of the rhythms in both healthy and malignant tissue. However, the hepatomas were much less sensitive to this signal resulting in markedly different phase relationships between host and tumor tissue as a function of mealtime. These data support the conclusion that hepatoma is differentially sensitive to circadian timing signals, although it maintains the circadian organization of the nonmalignant cells from which it arose. Because circadian clocks are known to modulate the sensitivity of many therapeutic cytotoxic targets, controlling meal-timing might be used to increase the efficacy of treatment. Specifically, meal and treatment schedules could be designed that take advantage of coincident times of greatest tumor sensitivity and lowest sensitivity of host tissue to damage.

Animals↗

PubMed2005

Biotechnological production and applications of phytases.

Phytases decompose phytate, which is the primary storage form of phosphate in plants. More than 10 years ago, the first commercial phytase product became available on the market. It offered to help farmers reduce phosphorus excretion of monogastric animals by replacing inorganic phosphates by microbial phytase in the animal diet. Phytase application can reduce phosphorus excretion by up to 50%, a feat that would contribute significantly toward environmental protection. Furthermore, phytase supplementation leads to improved availability of minerals and trace elements. In addition to its major application in animal nutrition, phytase is also used for processing of human food. Research in this field focuses on better mineral absorption and technical improvement of food processing. All commercial phytase preparations contain microbial enzymes produced by fermentation. A wide variety of phytases were discovered and characterized in the last 10 years. Initial steps to produce phytase in transgenic plants were also undertaken. A crucial role for its commercial success relates to the formulation of the enzyme solution delivered from fermentation. For liquid enzyme products, a long shelf life is achieved by the addition of stabilizing agents. More comfortable for many customers is the use of dry enzyme preparations. Different formulation technologies are used to produce enzyme powders that retain enzyme activity, are stable in application, resistant against high temperatures, dust-free, and easy to handle.

6-Phytase↗