The aim of this study was to determine the effect of the supplementation of an organic acid (citric acid), antibiotic growth promoter (avilamycin), and their combination for a period of 35 d on the growth, feed efficiency, carcass yield, tibia ash, and immune status of broilers. One hundred sixty 1-d-old broiler chicks (Hubbard Classic) were randomly distributed into 4 groups with 4 replicate cages having 10 birds in each. A corn-soybean-based diet was used as the basal diet (control). The basal diet was supplemented with an organic acid (citric acid, 0.5%), an antibiotic growth promoter (avilamycin, 0.001%), and their combination in other groups. The highest BW was attained in citric acid-fed chicks (1,318 g), which was significantly (P < 0.05) higher than control chicks (1,094 g) or avilamycin-fed chicks (1,217 g). The combination-fed chicks showed similar weight (1,246 g) as citric acid- or avilamycin-fed chicks (P > 0.05). Total feed intake was higher in citric acid-fed chicks compared with antibiotic-supplemented chicks. The addition of citric acid improved feed conversion efficiency (g of weight gain/ kg of feed intake) significantly (P < 0.05) compared with control chicks or its combination with avilamycin. Higher carcass weights were found in chicks fed the combination diet. Supplementation of citric acid increased tibia ash percentage significantly (P < 0.05) compared with controls. Addition of citric acid reduced the pH of the formulated diets. An improvement of immune status was detected by densely populated immunocompetent cells in the lamina propria and submucosa of cecal tonsils and ileum and also in the cortex and medulla of bursa follicles in citric acid-supplemented chicks. Supplementation of citric acid at 0.5% in the diet had positive effects on growth, feed intake, feed efficiency, carcass yield, bone ash, and immune status of broilers. Therefore, citric acid might be a useful additive instead of antibiotic growth promoters such as avilamycin, considering performance and health status of broilers.

No abstract

The survival of a bacterium with a depleted oxygen or nutrient supply is important for its long-term persistence inside the host under stressful conditions. We studied a gene, dps, from Mycobacterium smegmatis, encoding a protein, Dps (for DNA binding protein from starved cells), which is overexpressed under oxidative and nutritional stresses and provides bimodal protection to the bacterial DNA. Characterization of the dps promoter in vivo is therefore important. We cloned a 1-kb putative promoter region of the dps gene of M. smegmatis in an Escherichia coli-Mycobacterium shuttle vector, pSD5B, immediately upstream of the lacZ gene. Promoter activities were assayed in vivo both in solid medium and in liquid cultures by quantitative ␤-galactosidase activity measurements. To characterize the minimal promoter region, a 200-bp fragment from the whole 1-kb sequence was further cloned in the same vector, and in a similar way, ␤-galactosidase activity was quantitated. Primer extension analysis was performed to determine the ؉1 transcription start site of the gene. Point mutations were inserted in the putative promoter sequences in the ؊10 and ؊20 regions, and the promoter sequence was confirmed. The promoter was not recognized by purified M. smegmatis core RNA polymerase reconstituted with purified Mycobacterium tuberculosis A or B during multiple-and single-round in vitro transcription assays. Promoter-specific in vivo pull-down assays with an immobilized 1-kb DNA fragment containing the dps promoter established that extracellular function sigma factors were associated with this starvation-inducible promoter. Singleround transcription at the dps promoter further supported the idea that only core RNA polymerase reconstituted with F or H can generate proper transcripts.

. W. 2010. Effect of dietary citric acid, flavomycin and their combination on the performance, tibia ash and immune status of broiler. Can. J. Anim. Sci. 90: 57Á63. The goal of this research was to investigate the effect of citric acid (CA), the antibiotic growth promoter flavomycin (FL) and their combination on the growth performance, tibia ash and immune status of broilers. One hundred and sixty straight run day-old broiler chicks (Hubbard Classic) were randomly distributed into four dietary groups, with four replicate cages having 10 birds in each. Standard cornÁsoybean-based basal starter diet was given to control birds. Diets for other groups were further fortified by 0.5% CA, 0.001% FL and their combination (0.5% CA plus 0.001% FL). On day 35, CA and its combination (CA'FL) group had 17 and 12% increase in live weight compared with control, respectively (PB0.05). Total live weight on day 35 was 1141, 1337, 1169, and 1275 g bird Á1 in different groups, respectively (PB0.05). Cumulative feed intake was higher (P B0.05) in CA and its combination (CA'FL) compared with the control and FL groups on day 28. Supplementation with CA improved (P0.05) feed conversion ratio [FCR; feed intake (kg):weight gain (kg)] compared with FL and its combination (CA'FL). Carcass yield was increased (P0.05) due to the addition of CA and its combination (CA'FL). Tibia ash content in the CA group (59.0) was higher (PB0.05) than in the control (53.6%), FL (53.1%) and their combination (57.1%). The lymphocyte cells associated with immunity in the lymphoid organs (caecal tonsil, bursa Fabricius and ileum) were more densely populated, suggesting an increased level of innate immunity in the CA group. Overall mortality was low (1.25%), and there were no treatment-related effects on mortality. Citric acid reduced the pH of formulated feeds, but mild reduction was found in the pH of the faeces. Dietary supplementation of 0.5% CA increase weight gain, feed intake, tibia ash deposition and non-specific immunity (PB0.05) as well as feed efficiency and carcass yield (P0.05) of broilers. Citric acid has potential as a growth promoter to replace the antibiotic growth promoter FL. . Les oiseaux du groupe AC avaient plus (PB0,05) de cendres dans le tibia (59,0%) que ceux du groupe te´moin (53,6%), du groupe FL (53,1%) et du groupe prenant le me´lange (57,1%). Les organes lymphoı¨des (gros intestin, amygdales, bourses de Fabricius et ile´on) renfermaient plus de lymphocytes associe´s au pouvoir immunitaire, ce qui laisse croire que les oiseaux du groupe CA jouissaient d'une meilleure immunite´inne´e. Dans l'ensemble, le taux de mortalite´e´tait faible (1,25 %) et les traitements n'ont eu aucune incidence sur la mortalite´. L'acide citrique re´duit le pH de la ration, mais celui des fe`ces ne connaıˆt qu'une le´ge`re baisse. L'addition de 0,5 % d'AC aux aliments

Natural products have long been used as drugs to treat a wide array of human diseases. The lead compounds discovered from natural sources are used as novel templates for developing more potent and safer drugs. Natural products produce biological activity by binding with biological macromolecules, since natural products complement the protein-binding sites and natural product–protein interactions are already optimized in nature. Sirtuin 6 (SIRT6) is an NAD+ dependent histone deacetylase enzyme and a unique Sirtuin family member. It plays a crucial role in different molecular pathways linked to DNA repair, tumorigenesis, glycolysis, gluconeogenesis, neurodegeneration, cardiac hypertrophic responses, etc. Thus, it has emerged as an exciting target of several diseases such as cancer, neurodegenerative diseases, aging, diabetes, metabolic disorder, and heart disease. Recent studies have shown that natural compounds can act as modulators of SIRT6. In the current review, a list of natural products, their sources, and their mechanisms of SIRT6 activity modulation has been compiled. The potential application of these naturally occurring SIRT6 modulators in the amelioration of major human diseases such as Alzheimer’s disease, aging, diabetes, inflammation, and cancer has also been delineated. Natural products such as isoquercetin, luteolin, and cyanidin act as SIRT6 activators, whereas vitexin, catechin, scutellarin, fucoidan, etc. work as SIRT6 inhibitors. It is noteworthy to mention that quercetin acts as both SIRT6 activator and inhibitor depending on its concentration used. Although none of them were found as highly selective and potent modulators of SIRT6, they could serve as the starting point for developing selective and highly potent scaffolds for SIRT6.