Gel Diet Research Articles

Evaluation of a gel-based versus micro-pellet diet for adult zebrafish (Danio rerio).

Ad libitum feeding of laboratory zebrafish has potential benefits for colony management, but would require a new type of diet, such as a gel that remains in the tank. We hypothesized that adult zebrafish fed a gel diet would have similar body size and reproductive success compared with those fed a standard micro-pellet diet. The gel diet’s impact on water quality was determined to be safe for zebrafish prior to starting a 12-week feeding study. Two hundred adult AB zebrafish of mixed sex were randomly assigned to be fed exclusively either gel or micro-pellet diet. Fish body length and mass were measured every two weeks, and fish were bred within each feed group to assess fecundity. Zebrafish consumed less gel diet than expected. Body length, mass, and breeding success were lower in the gel diet fish than in the micro-pellet diet fish. Low consumption of the gel diet and/or nutritional differences between the two diets may have contributed to reduced growth and fecundity. Though the gel diet could reduce time personnel spend feeding and be safer for fish in static tanks, the tested formulation was not a satisfactory alternative to the control micro-pellet diet in a research zebrafish colony.

Impact of diet change on the gut microbiome of common marmosets (Callithrix jacchus).

Appropriate diet and health of the common marmoset in captivity are essential both for the welfare of the animal and to improve experimental outcomes. Our study shows that a gel diet compared to a biscuit diet improves the health of a marmoset colony, is linked to increases in Bifidobacterium species, and increases the removal of molecules associated with disease. The diet transition had an influence on the molecular changes at both the pair and time point group levels, but only at the pair level for the microbial changes. It appears to be more important which genes and functions present changed rather than specific microbes. Further studies are needed to identify specific components that should be considered when choosing an appropriate diet and additional supplementary foods, as well as to validate the benefits of providing probiotics. Probiotics containing Bifidobacterium species appear to be useful as probiotic supplements to the laboratory marmoset diet, but additional work is needed to validate these findings.

Optimization of Brewer's Yeast Quantity in Liquid and Gel Larval Diets for the Mediterranean Fruit Fly.

Several artificial larval diets have been developed, evaluated and used for mass-rearing of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Teprhitidae). There are several efforts to reduce the cost of rearing and optimize the quality of the produced sterile males that are destined for release in sterile insect release programs. Survival, growth, longevity and reproductive capacity of sterile males are strongly connected with the most expensive ingredient, the brewer's yeast (protein), in the larval diet. The current study focused on settling the optimal content of brewer's yeast in a liquid diet and a gel diet. Egg hatch rates, developmental duration of immatures, pupation rate, pupae and adult survival were recorded as indicators of quantity and quality of the produced adults. Egg hatch was higher and larval developmental duration longer in the gel diet. In contrast to the liquid diet, an increase in brewer's yeast concentration was correlated with increased pupation rate and pupae survival in the gel diet. Reducing brewer's yeast up to 50% of its initial quantity had no significant effect on the survival of the emerging adults regardless of the diet type. Our findings may contribute to the production of low-cost and effective diets for use in mass-rearing facilities of medflies.

Electronic recording of lifetime locomotory activity patterns of adult medflies.

Age-specific and diurnal patterns of locomotory activity, can be considered as biomarkers of aging in model organisms and vary across the lifetime of individuals. Τhe Mediterranean fruit fly (medfly), Ceratitis capitata, is a commonly used model-species in studies regarding demography and aging. In the present study, we introduce a modification of the automated locomotory activity electronic device LAM25system (Locomotory Activity Monitor)-Trikinetics, commonly used in short time studies, to record the daily locomotory activity patterns of adult medflies throughout the life. Additionally, fecundity rates and survival of adult medflies were recorded. Male and female medflies were kept in the system tubes and had access to an agar-based gel diet, which provided water and nutrients. The locomotory activity was recorded at every minute by three monitors in the electronic device. The locomotory activity of females was higher than that of males across the different ages. For both sexes locomotory rates were high during the first 20 days of the adult life and decreased in older ages. The activity of males was high in the morning and late afternoon hours, while that of females was constantly high throughout the photophase. Negligible locomotory activity was recorded for both sexes during the nighttime. Males outlived females. Fecundity of females was higher in younger ages. Our results support the adoption of LAM25system in studies addressing aging of insects using medfly as a model organism.

Aldosterone Regulates Vasopressin Escape through Changes in Water and Urea Transporters

Vasopressin escape is a process that prevents the continuous decrease in serum sodium even under conditions of sustained high vasopressin. Previous reports suggest that this process is regulated by aldosterone but the mechanism is not fully defined. In this study, aldosterone synthase (Cyp11b2) knockout and wild‐type mice were implanted with 14‐day osmotic mini‐pumps delivering 5 ng/h dDAVP (desmopressin, type 2 vasopressin receptor agonist) to promote distal nephron water reabsorption. Urine osmolality was measured before and then daily (24‐h urine collections) throughout the experiment. After 4 days of increased urine osmolality, mice were given a gel diet to force additional fluid consumption. Urine osmolality of the wild type mice was significantly lower (successful escape) than that of aldosterone synthase knockout mice. Protein analysis showed that both AQP2 and UT‐A1 protein abundances were higher in the aldosterone synthase knockout than wild‐type mice at the end of the escape period. To confirm the findings from the aldosterone synthase knockout mice, the mineralocorticoid receptor blocker spironolactone (20mg/kg/day, s.c.) or vehicle was given to rats that were receiving vasopressin by mini‐pump in a comparable vasopressin escape protocol to the mice. The spironolactone‐treated rats displayed a higher urine osmolality and lower serum sodium level versus untreated escaping rats. Phosphoserine 256‐AQP2 (PS256‐AQP2) was significantly increased in the spironolactone‐treated rats. Our results indicate that: vasopressin escape is prevented if aldosterone or its receptor are not available; and increased abundance of AQP2 or UT‐A1, or PS256‐AQP2, contributes to deficient vasopressin escape in the absence of aldosterone.

Kir6.1- and SUR2-dependent KATP overactivity disrupts intestinal motility in murine models of Cantú syndrome.

Cantú syndrome (CS), caused by gain-of-function (GOF) mutations in pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunit genes, is frequently accompanied by gastrointestinal (GI) dysmotility, and we describe 1 CS patient who required an implanted intestinal irrigation system for successful stooling. We used gene-modified mice to assess the underlying KATP channel subunits in gut smooth muscle and to model the consequences of altered KATP channels in CS gut. We show that Kir6.1/SUR2 subunits underlie smooth muscle KATP channels throughout the small intestine and colon. Knockin mice, carrying human KCNJ8 and ABCC9 CS mutations in the endogenous loci, exhibited reduced intrinsic contractility throughout the intestine, resulting in death when weaned onto solid food in the most severely affected animals. Death was avoided by weaning onto a liquid gel diet, implicating intestinal insufficiency and bowel impaction as the underlying cause, and GI transit was normalized by treatment with the KATP inhibitor glibenclamide. We thus define the molecular basis of intestinal KATP channel activity, the mechanism by which overactivity results in GI insufficiency, and a viable approach to therapy.

Restricted Water Intake and Hydration with Fructose-Containing Beverages during Infancy Predispose to Aggravate an Acute Renal Ischemic Insult in Adolescent Rats.

We aimed to investigate the effects of chronic fluid restriction and hydration with a sweetened beverage (SB) in rats from weaning until adolescence, in a posterior acute kidney injury (AKI) event induced by ischemia-reperfusion (I/R). We followed 5 groups of weaning rats: control group (C); two groups with 22 h/day fluid restriction, a group hydrated for two hours with water (-W) and a group hydrated with SB; one group receiving SB ad libitum all day (+SB); and one group in which water consumption was increased using a gel diet. The rats that reached adolescence were submitted to I/R. Fluid restriction and/or SB hydration induced mild renal alterations that were significantly accentuated in the -SB group and resulted in worse outcomes after I/R-induced AKI that resulted in a catastrophic fall in creatinine clearance and diffuse acute tubular necrosis. In summary, low tap water intakes, as well as SB intake in infancy, prompt kidney worse outcomes in a later event of AKI during adolescence and both insults magnify kidney damage. Studies on hydration habits in children are recommended to disclose the potentially harmful effects that those behavioral patterns might carry to future renal health.

Artificial Larval Diet Mediates the Microbiome of Queensland Fruit Fly.

Larval diets used for artificial rearing can have a significant effect on insect biology. The Queensland fruit fly (aka “Qfly”), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is one of the greatest challenges for fruit growers in Australia. The sterile insect technique (SIT) is being developed to manage outbreaks in regions that remain free of Qfly and to reduce populations in regions where this species is endemic. Factory scale rearing is essential for SIT; however, artificial larval diets are known to affect the microbiome of Qfly, which may then affect fly performance. In this study, high-throughput Illumina sequencing was used to assess the Qfly microbiome in colonies reared, for five generations from nature, on two common artificial diets (carrot and gel). At generation five (G5), the microbiome was assessed in larvae, pupae, adult males and adult females and standard fly quality control parameters were assessed together with additional performance measures of mating propensity and survival under nutritional stress. At the genus level, bacterial communities were significantly different between the colonies reared on the two larval diets. However, communities converged at Phyla to family taxonomic levels. Bacterial genera of Morganella, Citrobacter, Providencia, and Burkholderia were highly abundant in all developmental stages of Qfly reared on the gel diet, when compared to the carrot diet. Despite abundance of these genera, a greater percentage of egg hatching, heavier pupal weight and a higher percentage of fliers were found in the Qfly reared on the gel diet. Mating propensity and survival under nutritional stress was similar for adult Qfly that had been reared on the two larval diets. Overall, our findings demonstrate that the artificial larval diet strongly influences the microbiome and quality control measures of Qfly, with likely downstream effects on performance of flies released in SIT programs.

The effect of various processed seaweed, Kappaphycus alvarezii products as gel diet thickener on the utilization of nutrition in Rabbitfish, Siganus guttatus cultivation in the floating net cage

Seaweed, K. alvarezii as a gel diet thickener. The quality of the thickener is determined by the processing method. The purpose of this study was to determine the type of processed seaweed, K. alvarezii product, which is the best thickener in the gel diet based on fish body nutrient contents, protein efficiency ratio (PER), and protein retention (PR). Experimental fishes used were rabbitfish with an average weight of 55.23±4.46 g/individual, which was cultivated in a small cage (hapa) measuring 100 x 70 x 100 cm and placed in floating net cages (FNC). An experimental diet is a gel diet. The frequency of feeding is done twice a day, 7:00 in the morning, and 16:00 in the afternoon by satiation. The experimental design used was a completely randomized design (CRD) with 4 treatments and 5 replications. The treatment in this study was a gel diet containing some processed seaweed products such as dried seaweed flour (treatment A), fermented seaweed flour (treatment B), carrageenan flour (treatment C), and seaweed soft (treatment D). Analysis of variance (ANOVA) was carried out, and the W Tukey test was continued for the treatment that had a significant effect on determining the effect of various processed seaweed products on the measured parameters. The results showed that processed seaweed products in the gel diet significantly affected changes in fish protein, lipid and carbohydrate contents, protein efficiency ratio, and protein retention in rabbitfish. The best nutritional content of fish, PER, and PR is found in treatment B (fermented seaweed flour). Based on the results of this study, it was concluded that the nutritional body content of fish, REP, and RP was best obtained in rabbitfish, which consumed a gel diet containing fermented seaweed.

Effect of seaweed, Kappphycus alvarezii fermentation by various fermenters combinations as thickener on gel strength, attractiveness and palatability of gel diet in Tilapia, Oreohromis niloticus

Gel diet is one of the aquaculture diets that use seaweed, K. alvarezii, as a thickener made with cooking with water contents of between 50-70%. One effort to increase the nutritional content of seaweed is fermentation. However, fermentation affects the attractiveness, palatability, and gel strength of aquaculture artificial diet. This study aims to compare various fermenter combinations that are most effective in fermenting seaweed, K. alvarezii meal in terms of attractiveness, palatability, and gel strength. This research was carried out at the Laboratory of Nutrition and Feed Technology, Faculty of Marine Sciences and Fisheries, Hasanuddin University, Makassar, Indonesia. Experimental fishes used were tilapia size 7, 15, and 28 g. Various combinations of fermenters as treatment were seaweed meal without fermenter (treatment A), + 1.5g Bacillus sp. (treatment B), + 1.5g Bacillus sp. + 1.5 g of Rhizopus sp. (treatment C), + 1.5 g Bacillus sp. + 1.5g Saccharomyces sp. (treatment D), and + 1.5g Bacillus sp. + 1.5g Aspergillus sp. (treatment E). Fermentation is carried out on an an-aerobic basis. The parameters measured were attractiveness, palatability, and gel strength. The experimental design used was a completely randomized design with 5 treatments and 5 replications. Data were analyzed by ANOVA and W-Tukey test. The results of this study indicate that the attractiveness and gel strength of the experimental diet were the same in all treatments (p>0.05), while the highest palatability of the experimental diet was obtained in the experimental fish that consumed D diet, namely seaweed meal fermented with 1.5g Bacillus sp. + 1.5g Saccharomyces sp. Based on the results of this study, it was concluded that tilapia, which consumed the gel diet, contained seaweed fermented with 1.5g Bacillus sp. + 1.5g Saccharomyces sp. has the best palatability.

Bioavailable silicon forms in dietary supplements

Silicon (Si) is an element necessary for the proper functioning of the body. It affects cell viability, osteoblast differentiation, blood vessel elasticity, type I collagen synthesis, as well as the condition of the skin, hair, and nails. It is also considered an antiatherosclerotic agent. The silicon content in the human body is 6 – 7 g, and the only absorbable form is orthosilicic acid. The average daily requirement of the body for this element is in the range of 20 to 40 mg, whose diet does not fully provide. In addition, the silicon content in the body decreases with age, so there is a need for its supplementation. There are many liquid, gel, and spray diet supplements available that vary in concentration and silicon compound. The aim of the research was to determine the content of orthosilicic acid in liquid diet supplements. Thirteen preparations were selected for the study, in which concentration of available silicon was determined by a spectrophotometric method. This method was based on reaction in the acidic environment of dissociated silicon with ammonium molybdate. Among the selected products, the highest concentration of available silicon form was obtained for pharmaceuticals composed of choline stabilized orthosilicic acid, which is in the range of 50-2000 ppm. However, its concentration in preparations containing monomethylsilanetriol (MMST) did not exceed 50 ppm. Keywords: chemical sciences, orthosilicic acid, Uv-Vis spectroscopy

Agar and Carrageenan as Cost-Effective Gelling Agents in Yeast-Reduced Artificial Diets for Mass-Rearing Fruit Flies and Their Parasitoids.

The development of cost-effective diets for mass-rearing fruit flies (Diptera: Tephritidae) and their parasitoids in pest control programs based on the Sterile Insect Technique is a high priority worldwide. To this end, we tested carrageenan, agar, gelatin and two types of pregelatinized corn starches as gelling agents at varying percentages in a yeast-reduced liquid larval diet for rearing the Mexfly, Anastrepha ludens. Only diets with 0.234% (w/w) agar or 0.424% carrageenan were identified as diets with potential for mass-rearing A. ludens in terms of the number of pupae recovered from the diet, pupal weight, adult emergence, flight ability and diet cost. Comparative experiments showed that yeast-reduced agar and carrageenan gel diets produced heavier pupae and higher proportions of flying adults than the standard mass-rearing diet. The gel-agar and mass-rearing diets produced more pupae than the gel-carrageenan diet, but the latter produced more suitable larvae as hosts for rearing of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) females, a widely used fruit fly biocontrol agent. Yeast-reduced agar and carrageenan gel diets could represent cost-effective fruit fly mass-rearing diets if a practical system for gel diet preparation and dispensation at fruit fly mass-rearing facilities is developed.

Assessment of Bactrocera dorsalis (Diptera: Tephritidae) Diets on Adult Fecundity and Larval Development: Insights Into Employing the Sterile Insect Technique.

Bactrocera dorsalis (Hendel) is a notorious insect pest that attacks diverse vegetables and fruits worldwide. The sterile insect technique has been developed as an environmentally friendly and effective control method that depends on the mass production of target flies. Because dietary yeast (protein) and sucrose (carbohydrate) are important in adult diets, yeast:sucrose (Y:S) mixtures are crucial for the mass-rearing of B. dorsalis. In this study, we found adult diets with different ratios of yeast to sucrose-influenced fecundity, and an extremely high or low Y:S ratios significantly decreased egg production of B. dorsalis. Additionally, the maximum oviposition efficiency was realized at dietary yeast to sucrose ratios of 1:1 and 1:3, suggesting their potential use to produce more eggs for the mass production of B. dorsalis. Here, new gel diets having different yeast concentrations (g/L water) were also assessed for rearing B. dorsalis larvae. Gel diets containing 20 g/L yeast led to a higher pupation, pupal weight and adult eclosion rate, and a shorter developmental time than other yeast concentrations. Moreover, the present gel diet also resulted in greater pupal production and adult emergence rates than previously used liquid and solid artificial diets, revealing that it is suitable for rearing B. dorsalis larvae. This research provides a useful reference on artificial diets mixtures for mass rearing B. dorsalis, which is critical for employing the sterile insect technique.

Comparison of Gel Larval Diet With Traditional Lucerne Chaff and Carrot Solid Diets for Rearing of Queensland Fruit Fly (Diptera: Tephritidae).

Sterile insect technique (SIT) for Queensland fruit fly, Bactrocera tryoni Froggatt, Australia's most economically damaging fruit fly species, is currently undergoing a major renewal and expansion. SIT relies on efficient and economical mass-rearing procedures that produce high-quality flies. Two solid larval diets, carrot and lucerne chaff, have traditionally been used to rear Queensland fruit fly. Recently, a gel larval diet has been developed to eliminate biological bulking agents from the mass-rearing process, but to date, there has been no direct comparison of gel larval diet with traditional solid diets. In the present study, the performance of flies reared on gel larval diet was compared with the performance of flies reared on carrot and lucerne chaff diets. In addition, to investigate whether the performance of reared flies depends on ancestral diet as well as tested diet, we sourced eggs from a colony maintained on carrot diet and from a colony maintained on a lucerne chaff diet. Overall, the gel diet was as good or better than the solid diets in all quality control parameters, including, egg-larval duration, pupal number, pupal recovery, adult emergence, percentage of fliers, and rate of fliers. Of note, larvae developed faster and pupated more synchronously on the gel diet than on either of the solid diets. At the loading densities used, gel and carrot diets produced less waste than lucerne chaff diet. Gel diets offer a rearing solution for Queensland fruit fly that eliminates biological bulking agents and yields faster and more synchronous larval development without compromising productivity or quality.

Prenatal Sildenafil Therapy Improves Cardiovascular Function in Fetal Growth Restricted Offspring of Dahl Salt-Sensitive Rats.

Fetal growth restriction (FGR) is associated with increased risk for cardiovascular and renal disorders in later life. Prenatal sildenafil improves birth weight in FGR animal models. Whether sildenafil treatment protects against long-term cardiovascular and renal disease in these offspring is unknown. The aim of this study is to test the hypothesis that prenatal sildenafil ameliorates cardiovascular and renal function in FGR offspring of Dahl salt-sensitive rats. Sildenafil citrate (60 mg/kg per day) or control gel diet (containing 0.3% salt) was administered from gestational day ten until birth. In male and female offspring, the mean arterial pressure was measured by telemetry in 1 subset from week 5 until week twenty. Echocardiographic parameters, glomerular filtration rate, and fractional electrolyte excretion were determined in another subset at week 9. Aortic and mesenteric artery rings were prepared to assess endothelial-dependent (acetylcholine) and -independent (sodium nitroprusside) vasorelaxation (week 10). The rise in mean arterial pressure per week was attenuated in treated versus untreated male offspring. Mesenteric arteries showed an increased endothelium-dependent relaxation and improved endothelium-independent relaxation in treated versus control male offspring. No differences in aortic relaxation, echocardiographic parameters or renal function were observed between groups. Prenatal sildenafil treatment subtly improves cardiovascular but not renal function in the offspring of this FGR rat model. Translationally, in utero treatment could be beneficial for cardiovascular programming in a sex-specific manner; however, caution is warranted since recent human trials have been halted because of potentially deleterious neonatal side effects when treating pregnancies complicated with severe FGR with sildenafil.

212. Effects of prenatal sildenafil treatment on long-term cardiovascular function in offspring from dahl salt-sensitive rats

Introduction Fetal growth restriction (FGR) is associated with increased risk for cardiovascular disorders in later life. Cardiovascular disease is the most common cause of death worldwide. Previous studies report that prenatal sildenafil improves pregnancy outcomes, such as birthweight, in FGR animal models; however, whether sildenafil treatment is protective against long-term cardiovascular disease in these offspring is unknown. Objective We hypothesize that prenatal sildenafil reduces blood pressure and endothelial dysfunction in FGR offspring from Dahl salt-sensitive (SS) rats on normal salt intake. Methods Sildenafil citrate (60 mg/kg/day) or control gel diet was administered from gestational day 10 until birth. Birthweight and litter size were measured (treated n = 10; untreated n = 8 dams). Telemetry devices (DSI) were implanted via the femoral artery to measure mean arterial pressure (MAP) from weeks 5–8 in the offspring (treated n = 12; untreated n = 4). Aortic rings were isolated from 10 week old offspring to assess vascular sensitivity ( logEC 50 ) to endothelial-dependent (acetylcholine) and -independent (sodium nitroprusside, SNP) vasorelaxation (treated n = 10; untreated n = 10). Data shown as mean ± S.E.M. Results No sex differences were observed in any variables; therefore, data were pooled between males and females. Sildenafil improved birthweight (treated 6.8 ± 0.2; untreated 6.2 ± 0.1 g; p = 0.02) without significantly changing viable litter size (treated 9.6 ± 0.9; untreated 7.9 ± 1.0; p = 0.23). While MAP at 5 weeks was similar between groups (treated 107 ± 1; untreated 108 ± 2 mmHg; p = 0.55), there was a trend towards lower MAP in prenatally treated offspring at 8 weeks (treated 116 ± 1; untreated 120 ± 2 mmHg; p = 0.09). Aortas from offspring of treated dams displayed enhanced sensitivity to acetylcholine ( logEC 50 : treated −7.4 ± 0.3; untreated −6.6 ± 0.3 M; p = 0.03), but not to SNP (treated −8.2 ± 0.3; untreated −7.9 ± 0.2 M; p = 0.43). Discussion Prenatal sildenafil treatment improves birthweight in a model of FGR. In young adult offspring, there was a trend towards a sex-independent lowering of blood pressure and increased endothelium-dependent relaxation.

RYGB increases the satiating effect of intrajejunal lipid infusions in female rats

We used a novel rat model to investigate the physiological bases of early satiation after Roux-en-Y gastric bypass surgery (RYGB). Female rats were subjected to RYGB or sham surgery. Chronic infusion catheters were placed in the Roux limb of RYGB rats and the corresponding anatomical locus of the jejuna of sham-RYGB rats. Rats were also ovariectomized and chronically treated with either estradiol (E2; 2 μg each 4th day SC) or the oil vehicle. Testing was begun 10–12 wk after surgery. Intrajejunal lipid infusions (10 min, 4.4 mL, 8.8 kcal) were performed just before test meals of a low-energy artificially sweetened gel diet (0.1 kcal/g) that RYGB rats ingest avidly. Intrajejunal lipid infusions reduced test-meal size more in RYGB rats than sham-operated rats, indicating that, at least after prolonged adaptation to surgery, the satiating actions of lipids acting intra- or post-jejunally are increased by RYGB and that accelerated meal appearance in the intestines after RYGB is not necessary for this effect. The satiating effects of intrajejunal lipid infusions were similar in E2-and oil-treated rats, suggesting that the effect was not dependent on an activational effect of estrogens. In a second experiment, pretreatment with the cholecystokinin A-receptor antagonist devazepide reduced the satiating effect of intrajejunal lipid infusions in E2-treated RYGB rats. Although these data are preliminary due to the smaller numbers of rats than in the first experiment, they suggest that cholecystokinin-mediated jejunal satiation contributes to early satiation after RYGB in ovariectomized rats with peri-ovulatory levels of estradiol. The results of these experiments may be relevant to understanding RYGB outcome in pre- and postmenopausal women.

Oral Delivery of Nisin in Resistant Starch Based Matrices Alters the Gut Microbiota in Mice.

There is a growing recognition of the role the gastrointestinal microbiota plays in health and disease. Ingested antimicrobial proteins and peptides have the potential to alter the gastrointestinal microbiota; particularly if protected from digestion. Nisin is an antimicrobial peptide that is used as a food preservative. This study examined the ability of nisin to affect the murine microbiota when fed to mice in two different starch based matrices; a starch dough comprising raw starch granules and a starch gel comprising starch that was gelatinized and retrograded. The effects of the two starch matrices by themselves on the microbiota were also examined. Following 16S rRNA compositional sequencing, beta diversity analysis highlighted a significant difference (p = 0.001, n = 10) in the murine microbiota between the four diet groups. The differences between the two nisin containing diets were mainly attributable to differences in the nisin release from the starch matrices while the differences between the carriers were mainly attributable to the type of resistant starch they possessed. Indeed, the differences in the relative abundance of several genera in the mice consuming the starch dough and starch gel diets, in particular Akkermansia, the relative abundance of which was 0.5 and 11.9%, respectively (p = 0.0002, n = 10), points to the potential value of resistance starch as a modulator of beneficial gut microbes. Intact nisin and nisin digestion products (in particular nisin fragment 22–31) were detected in the feces and the nisin was biologically active. However, despite a three-fold greater consumption of nisin in the group fed the nisin in starch dough diet, twice as much nisin was detected in the feces of the group which consumed the nisin in starch gel diet. In addition, the relative abundance of three times as many genera from the lower gastrointestinal tract (GIT) were significantly different (p < 0.001, n = 10) to the control for the group fed the nisin in starch gel diet, implying that the starch gel afforded a degree of protection from digestion to the nisin entrapped within it.

Dapagliflozin slows the progression of the renal and liver fibrosis associated with type 2 diabetes.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic oral agents indicating promising effects on cardiovascular and renal end points. However, the renoprotective effects of SGLT2 inhibitors are not fully understood. Also, metabolic effects of SGLT2 inhibition on other organ systems, such as effects on hepatic steatosis, are not fully understood. This study sought to address these questions by treating 18-wk-old uninephrectomized db/db mice with the selective SGLT2 inhibitor dapagliflozin. Untreated db/db mice developed progressive albuminuria, glomerular mesangial matrix expansion, and fatty liver associated with increased renal expression of TGFβ1, PAI-1, type IV collagen and fibronectin, and liver deposition of fibronectin, type I and III collagen, and laminin. Treatment with dapagliflozin (1 mg·kg-1·day-1) via gel diet from 18 to 22 wk of age not only reduced blood glucose (371.14 ± 55.02 mg/dl in treated db/db vs. 573.53 ± 21.73 mg/dl in untreated db/db, P < 0.05) and Hb A1c levels (9.47 ± 0.79% in treated db/db vs. 12.1 ± 0.73% in untreated db/db, P < 0.05) but also ameliorated the increases in albuminuria and markers of glomerulosclerosis and liver injury seen in untreated db/db mice. Furthermore, both renal expressions of NF-kB p65, MCP-1, Nox4, Nox2, and p47phox and urine TBARS levels and liver productions of myeloperoxidase and reactive oxygen species, the markers of tissue inflammation and oxidative stress, were increased in untreated db/db mice, which were reduced by dapagliflozin administration. These results demonstrate that dapagliflozin not only improves hyperglycemia but also slows the progression of diabetes-associated glomerulosclerosis and liver fibrosis by improving hyperglycemia-induced tissue inflammation and oxidative stress.

Effect of diet on growth in captive Podocnemis unifilis: assessing optimal diets for turtles in head-starting programs

Because turtles have come under increasing pressures from habitat loss and over-exploitation as food sources and traditional medicine, efforts have focused on options for conservation, including head-starting programs. Success of head-starting programs depends on establishing economical means of rearing hatchlings over relatively short time frames to sizes resistant to predation. We examined effects of three different diets on growth of a clutch of captive Yellow-spotted Amazon River Turtles (Podocnemis unifilis) over a two-year period in a Florida zoo. Rates of growth differed among the three treatment groups; relationships between morphological variables were not affected by diet. Results indicate that turtles fed on a commercial gel diet may exceed growth rates of animals fed on a more natural, vegetarian diet by more than 15% as measured by straight-line carapace length, or by more than 50% in body mass. Use of a vegetarian diet reduced costs to less than 10% of the cost of a commercial gel diet. Choice of diets for turtles in head-starting programs is a variable that should be weighed against other conservation objectives such as captive duration and intended sizes attained.