The objective of the present study was to evaluate anti-diabetic effects of chromium picolinate (CrPic) and biotin supplementations in type 2 diabetic rats. The type 2 diabetic rat model was induced by high-fat diet (HFD) and low-dose streptozotocin. The rats were divided into five groups as follows: (1) non-diabetic rats fed a regular diet; (2) diabetic rats fed a HFD; (3) diabetic rats fed a HFD and supplemented with CrPic (80 μg/kg body weight (BW) per d); (4) diabetic rats fed a HFD and supplemented with biotin (300 μg/kg BW per d); (5) diabetic rats fed a HFD and supplemented with both CrPic and biotin. Circulating glucose, cortisol, total cholesterol, TAG, NEFA and malondialdehyde concentrations decreased (P< 0·05), but serum insulin concentrations increased (P< 0·05) in diabetic rats treated with biotin and CrPic, particularly with a combination of the supplements. Feeding a HFD to diabetic rats decreased PPAR-γ expression in adipose tissue and phosphorylated insulin receptor substrate 1 (p-IRS-1) expression of liver, kidney and muscle tissues, while the supplements increased (P< 0·001) PPAR-γ and p-IRS-1 expressions in relevant tissues. Expression of NF-κB in the liver and kidney was greater in diabetic rats fed a HFD, as compared with rats fed a regular diet (P< 0·01). The supplements decreased the expression of NF-κB in diabetic rats (P< 0·05). Results of the present study revealed that supplementing CrPic and biotin alone or in a combination exerts anti-diabetic activities, probably through modulation of PPAR-γ, IRS-1 and NF-κB proteins.

Treatment with a combination of four nutrients, i.e. R-α-lipoic acid, acetyl-l-carnitine, nicotinamide and biotin, just as with pioglitazone, significantly improves glucose tolerance, insulin release, plasma NEFA, skeletal muscle mitochondrial biogenesis and oxidative stress in Goto–Kakizaki (GK) rats. However, it is not known whether treatment with these nutrients can improve mitochondrial function and reduce oxidative stress in GK rats. The effects of a combination of these four nutrients on mitochondrial function, oxidative stress and apoptosis in GK rat liver were investigated. Livers of untreated GK rats showed (1) abnormal changes in the activities of mitochondrial complexes (decreases in I, III and IV and increases in II and V), (2) increases in protein oxidation, (3) decreases in antioxidant enzymes (superoxide dismutase, glutathione S-transferase, NADH-quinone oxidoreductase-1), (4) a decrease in total antioxidant capacity but increases in reduced glutathione level and glyceraldehyde 3-phosphate dehydrogenase expression and (5) significant increases in apoptosis biomarkers, including expression of p21 and p53. A 3-month treatment with the four nutrients significantly improved most of these abnormalities in GK rats, and the effects of the nutrient combination were greater than those of pioglitazone for most of these indices. These results suggest that dietary supplementation with nutrients that are thought to influence mitochondrial function may be an effective strategy for improving liver dysfunction in GK diabetic rats.

In the rods of Bufo marinus and other species, bleaching of the rhodopsin in isolated cells leads to a loss of sensitivity and response amplitude and to a shortened response duration. These changes are permanent for cells bathed in Ringer&s solution. They are due to as yet unknown modulations in the transduction biochemistry. In this paper, we report that these changes can be partly or completely reversed by supplying biotin, pyruvate, and elevated glucose to the rod. The time course of this reversal and the substances which promote it imply that these are metabolically mediated effects. Based on the reported action of biotin and pyruvate on the one hand and on the changes of the response waveforms on the other hand, we believe that the phenomena we observe involve the later steps of the transduction cycle.

The developmental pattern of biotinylated proteins (BP) during embryogenesis and maturation of soybean seed was characterized. Detection of these BP was compared with the development of desiccation tolerance in seeds. Three groups of BP were detected in soybean seeds using a biotin-streptavidin detection method: the first group consisted of a set of three bands with a mean apparent MW of 85 kDa (called BP85), detected in crude extracts of embryonic axes (EA) from non-dehydrated seeds (NDS) and from artificially slow-dehydrated seeds (DS); the second one, BP75, was a single protein with an apparent MW of 75 kDa and was expressed in cotyledons (COT) and EA tissues of NDS and DS; the third group with a mean apparent MW of 35 kDa (BP35), was expressed at high levels only in COT of NDS. BP35 concentration was highest in the early stages of seed development (21 days after flowering — DAF) and decreased as seeds developed, being almost imperceptible after 47 DAF. Conversely, only traces of BP75 and BP85 extracted from EA and COT were detected at early stages of seed development (21–33 DAF). Maximum levels of accumulation of these proteins were expressed at 42–47 DAF and remained constant until harvest maturity. Desiccation-tolerant stage of the seeds was initiated at 47 DAF, which coincided with the stage of maximum accumulation of BP75 and BP85 in the seeds, however, appearance of these proteins could be stimulated by desiccation of immature seeds that had not achieved desiccation tolerance. Therefore changes in biotinylated proteins are coincident with, but not sufficient for, the development of desiccation tolerance.

Biotin is an important vitamin. It is biologically active as a protein prosthetic group, where it functions in enzymatically catalysed carboxylation reactions. It has previously been shown that the ability to synthesize biotin is not necessary for germination of Arabidopsis thaliana seeds, but that this process is required for early seedling growth. This research was conducted to determine if changes in the detection of biotinylated proteins could be observed that reflect changes in the need for biotin-mediated enzyme reactions observed during early soybean seedling growth. A seed specific 75-kDa biotinylated protein present in the embryonic axes and the cotyledons was lost during the first 3 d of germination. Seed specificity, and pattern of expression during germination suggest that this protein is a homologue of the seed specific 65-kDa biotinylated protein previously identified in pea (Pisum sativum). If samples were not treated with 2-mercaptoethanol, three equally spaced proteins at approx. 85 kDa were visible. In the presence of 2-ME these proteins appeared as a single 85-kDa band. This triplet was distinct only in the embryonic axes of dry seeds and not in imbibed seeds or in other plant parts. This demonstrates that imbibitional changes do occur in the pool of biotinylated proteins present in dry soybean seeds, and that 2-ME treatment can inhibit complete identification of the biotinylated proteins present in seed tissues.

Biotin is a member of the vitamin B-complex family. Biotin deficiency has been associated with hyperglycaemia and insulin resistance in animals and humans. In the present study, we investigated the pharmacological effects of biotin on hypertension in the stroke-prone spontaneously hypertensive rat (SHRSP) strain. We observed that long-term administration of biotin decreased systolic blood pressure in the SHRSP strain; also, a single dose of biotin immediately decreased systolic blood pressure in this strain. Pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazole [4,3-α]quinoxalin-1-one abolished the hypotensive action of biotin in the SHRSP strain, while pretreatment with the NO synthase inhibitor NG-nitro-l-arginine methyl ester had no effect on the action of biotin. Biotin reduced coronary arterial thickening and the incidence of stroke in the SHRSP strain. These results suggest that the pharmacological dose of biotin decreased the blood pressure of the SHRSP via an NO-independent direct activation of soluble guanylate cyclase. Our findings reveal the beneficial effects of biotin on hypertension and the incidence of stroke.

The effect of feeding supplemental biotin on net absorption and metabolism of nutrients by the portal-drained viscera (PDV; the gut, pancreas, spleen and associated fat) and liver of lactating dairy cows was measured. Three cows in early to mid-lactation catheterised for measurements of net nutrient absorption and metabolism by the PDV and liver were fed a total-mixed ration with or without supplemental biotin at 20 mg/day using a switch-back design (ABA v. BAB) with three 2-week periods. There were no effects of feeding biotin on dry matter intake (22.2 kg/day), milk yield (29.5 kg/day) or milk composition. There was also no effect of feeding biotin on net release of glucose by the liver, net liver removal of glucose precursors (propionate, alanine, lactate) or net liver release of β-hydroxybutyrate. Feeding biotin increased net PDV release of ammonia. Reasons for the response are not certain, but a numerical increase in net PDV release of acetate suggests that rumen or hindgut fermentation was altered. Results of the present study do not support the hypothesis that supplemental biotin increases liver glucose production in lactating dairy cows.

Homologues of the pea SBP65, a late embryogenesis abundant (LEA) biotinylated protein that behaves as a putative sink for the free vitamin biotin during embryo development, were characterized biochemically in various plant species, including soybean, lentil, peanut, rape, cabbage, carrot and sugarbeet. Based on sequence homologies, the genome of Arabidopsis thaliana contains a gene putatively encoding a homologue of pea SBP65. These proteins exhibit two remarkable features. First, they only accumulate in seeds, particularly during late stages of embryo development. The results strongly suggest that these seed-specific biotinylated proteins belong to the class of plant proteins called seed maturation proteins, which are presumed to play major roles in embryo development. Secondly, covalent attachment of biotin occurs at a lysine residue within a conserved motif of (V/M)GKF, which shows no resemblance to the highly conserved AMKM tetrapeptide that houses the target lysine residue in the well-characterized biotin-dependent carboxylases and decarboxylases. These findings highlight novel structural features for protein biotinylation.

Biotin is required by rumen microbes for efficient fermentation. To evaluate the role of protozoa in ruminal biotin metabolism, five diets composed of grass hay or of grass hay/cereal grain mixtures were supplied to faunated or defaunated RUSITEC fermenters. In the mixed diets, hay was replaced to 33:67 or 67:33 w/w on an air-dried basis by either wheat or maize grain in order to simulate different cellulolytic and amylolytic fermentation conditions. Defaunation increased SCFA production, whereas NH4 concentration and the release of CH4 were reduced. Biotin input declined when cereal grain was used to replace the hay. With the exception of the high-wheat treatment, defaunated fermenters yielded higher biotin outputs than faunated fermenters. The biotin balance, calculated as the difference between the total biotin output (biotin in the solid residue contained in the nylon bags after fermentation plus the biotin in the effluent) and the biotin input with the feed, was negative for all the dietary treatments apart from fermenters supplied with the high-maize diet. It was less negative or, in the case of the high-maize diets, more positive for defaunated compared with faunated fermenters. It was concluded that, under normal faunated conditions, protozoa directly utilise or indirectly affect the bacterial synthesis and/or utilisation of biotin. With diets of a high fermentation potential, as realised with the high-wheat diet, protozoa prevent the development of a bacterial population that would utilise high or synthesise low amounts of biotin.

FPD is a common condition amongst commercially grown turkey poults. It causes the skin of the footpad to become hard and scaly, often developing horn-like pegs of abnormal keratin. The footpad can become swollen, frequently splitting. In the centre of the lesion the epidermis separates, and is often totally necrotic. Heterophils filter into the stratum germinativum.

The cause of FPD is complex, but many contributing factors have been suggested, such as dietary intake, skin structure, bird weight and sex, litter moisture and litter type. Litter quality is affected by many other factors such as stocking density, air temperature and moisture, season, consistency and amount of faeces (affected by diet), and drinker design.

Wet litter is the most likely factor affecting FPD, followed by biotin deficiency. Experimental evidence suggests that biotin deficiency causes FPD, and that commercial rations do not contain enough biotin to prevent these lesions. Supplementations of biotin have been shown to reduce the severity and incidence of lesions. Wet litter has also been identified as a possible causative agent. Broilers and poults reared on wet litter have an increased incidence and severity of FPD lesions, but the problem is alleviated by replacing the wet litter with dry. Biotin supplementations are able to reduce FPD to a certain extent if birds are reared on dry litter, but if on wet litter, lesions may still occur. Biotin intake and wet litter appear to be the factors most likely to influence the development of FPD.

Experimental results are difficult to compare because rearing conditions differ. Further experimentation is needed to determine the optimum amount of biotin required for healthy growth and lesion free foot pads, and to ascertain the real effects of other suggested causes.

This report is a standardized compendium of age-related reproductive response data of turkey hens from the use of dietary supplemental d-biotin, pyridoxine and folic acid; and of commercial and domestic egg injections of each of the crystalline vitamins to determine their limiting inherent essence in causing embryo failure. With reproductive response data reported in each of three grouped time periods of production (5–6 wk each), the system of analysis was not confounded with feed consumption with the progression of maternal age.

Maternal age had no effect on vitamin transport to the egg for any of the three vitamins; and no effect on hatchability or poult weight, with the exception of biotin and folic acid, respectively. With the progression of maternal age, higher dietary biotin and folic acid levels were required for hatchability and poult weight, respectively, after 5–6 wk of production.

There was a lack of/or minor effect of dietary pyridoxine on the transfer of vitamin B6, for hatchability of turkey eggs. Egg injections of pyridoxine were vital for increasing hatchability even though the hen's diet was amply supplemented with pyridoxine. Manual egg vitamin injections are considered valuable for diagnosing possible limiting vitamins for hatchability. The manual injection method utilized small egg numbers and was administered at selective intervals over the production cycle. Automated injections were utilized for commercial flocks where egg numbers were large. Automated egg injections performed in the commercial sector, had no detrimental influence on poult viability or growth after hatching. Statistical reliability existed between hatchability results of automated and manual egg injections of a single vitamin level, and between different flocks of the same strain, both commercial and experimental.

The report offers practical insight for versatile changes in meeting dietary and egg needs of the three vitamins for higher reproductive performance. The report also offers new insight for hatchability improvement with dietary biotin with the progression of age in the hen.

RNA affinity tags would be very useful for the study of RNAs and ribonucleoproteins (RNPs) as a means for rapid detection, immobilization, and purification. To develop a new affinity tag, streptavidin-binding RNA ligands, termed “aptamers,” were identified from a random RNA library using in vitro selection. Individual aptamers were classified into two groups based on common sequences, and representative members of the groups had sufficiently low dissociation constants to suggest they would be useful affinity tools. Binding of the aptamers to streptavidin was blocked by presaturation of the streptavidin with biotin, and biotin could be used to dissociate RNA/streptavidin complexes. To investigate the practicality of using the aptamer as an affinity tag, one of the higher affinity aptamers was inserted into RPR1 RNA, the large RNA subunit of RNase P. The aptamer-tagged RNase P could be specifically isolated using commercially available streptavidin-agarose and recovered in a catalytically active form when biotin was used as an eluting agent under mild conditions. The aptamer tag was also used to demonstrate that RNase P exists in a monomeric form, and is not tightly associated with RNase MRP, a closely related ribonucleoprotein enzyme. These results show that the streptavidin aptamers are potentially powerful tools for the study of RNAs or RNPs.

The contribution of the Ser45 hydrogen bond to biotin binding activation and equilibrium thermodynamics was investigated by biophysical and X-ray crystallographic studies. The S45A mutant exhibits a 1,700-fold greater dissociation rate and 907-fold lower equilibrium affinity for biotin relative to wild-type streptavidin at 37 °C, indicating a crucial role in binding energetics. The crystal structure of the biotin-bound mutant reveals only small changes from the wild-type bound structure, and the remaining hydrogen bonds to biotin retain approximately the same lengths. No additional water molecules are observed to replace the missing hydroxyl, in contrast to the previously studied D128A mutant. The equilibrium ΔG°, ΔH°, ΔS°, ΔC°P, and activation ΔG[Dagger] of S45A at 37 °C are −13.7 ± 0.1 kcal/mol, −21.1 ± 0.5 kcal/mol, −23.7 ± 1.8 cal/mol K, −223 ± 12 cal/mol K, and 20.0 ± 2.5 kcal/mol, respectively. Eyring analysis of the large temperature dependence of the S45A off-rate resolves the ΔH[Dagger] and ΔS[Dagger] of dissociation, 25.8 ± 1.2 kcal/mol and 18.7 ± 4.3 cal/mol K. The large increases of ΔH[Dagger] and ΔS[Dagger] in the mutant, relative to wild-type, indicate that Ser45 could form a hydrogen bond with biotin in the wild-type dissociation transition state, enthalpically stabilizing it, and constraining the transition state entropically. The postulated existence of a Ser45-mediated hydrogen bond in the wild-type streptavidin transition state is consistent with potential of mean force simulations of the dissociation pathway and with molecular dynamics simulations of biotin pullout, where Ser45 is seen to form a hydrogen bond with the ureido oxygen as biotin slips past this residue after breaking the native hydrogen bonds.

The response of pigs to supplemental biotin (500 μg/kg diet) was studied in a growth trial from 15 to 88 kg live weight. Food: gain ratio was significantly improved during the grower phase and there was a tendency for improvement in the starter and finisher phases. There was also a tendency towards improved carcass grading.