Invited review: Total solids concentration in milk or milk replacer for dairy calves

Restricting milk or milk replacer (MR) fed to dairy calves to 10% of body weight at 12.5% total solids (TS) concentration is a common feeding strategy that promotes early weaning and lowers total feed costs for raising young calves. However, this strategy has been associated with inferior performance and compromised welfare. Because a restricted liquid nutrition plan limits calf growth due to limited supply of nutrients, research on increased supply of nutrients from liquid has shown improved growth, health, and welfare of calves. Nutrient supply may be increased by feeding larger amounts of milk or MR averaging 12.5% TS, or by increasing TS above the usual 12.5% TS by increasing MR TS concentration alone (TS+), or by increasing TS concentration and volume simultaneously (TSV+). The objective of this review is to discuss liquid nutrition plans with greater TS concentration in MR or in milk diets, considering the effects of such strategies on performance and digestive tract development before weaning and the future performance of dairy calves. This review will focus on liquid nutrition plans that are based on increased TS concentration (i.e., TS+ or TSV+); therefore, enhanced liquid nutrition plans based only on increased volumes will not be the discussed. Improved growth rates have been observed in calves fed TSV+ programs. However, reduced starter intake preweaning can also have negative effects on dry matter intake, average daily gain, and digestibility postweaning. Feeding a TS+ program may reduce impairment of starter intake and therefore have positive effects on performance, nutrient digestibility, and health. When considering an accelerated nutrition plan with TS+ or TSV+, it is important to consider osmolality of the liquid diet. Further studies are necessary to confirm this hypothesis and the cost-benefit of alternative liquid nutrition plans, as well as the optimal TS concentration of milk or MR fed to dairy calves.

Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises

We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.

Footwear designed to enhance energy return improves running economy compared to a minimalist footwear: does it matter for running performance?

The present study compared the effects of a footwear designed to enhance energy return (thermoplastic polyurethane, TPU) vs minimalist shoes on running economy (RE) and endurance performance. In this counterbalanced and crossover design study, 11 recreational male runners performed two submaximal constant-speed running tests and two 3-km time-trials with the two shoe models. Oxygen uptake was measured during submaximal constant-speed running tests in order to determine the RE at 12 km/h and oxygen cost of running (CTO2) at individual average speed sustained during the 3-km running time-trials wearing either of the two shoes. Our results revealed that RE was improved (2.4%) with TPU shoes compared with minimalist shoes (P=0.01). However, there was no significant difference for CTO2 (P=0.61) and running performance (P=0.52) comparing the TPU (710±60 s) and the minimalist (718±63 s) shoe models. These novel findings demonstrate that shoes with enhanced mechanical energy return (i.e. TPU) produced a lower energy cost of running at low (i.e., 12 km/h) but not at high speeds (i.e., average speed sustained during the 3-km running time-trial, ∼15 km/h), ultimately resulting in similar running performance compared to the minimalist shoe.

Energy and protein requirements of crossbred Holstein × Gyr calves fed milk with milk replacer containing increasing dry-matter concentrations

Context There is a lack of studies concerning the nutrient requirements of dairy calves, mainly, evaluating different genetic groups. Aims The objective was to quantify energy and protein requirements of dairy calves up to 60 days, testing the influence of genetic composition (Holstein or crossbred Holstein × Gyr) on these requirements. Methods The study involved 42 bull calves (3 days of age), including animals with less than 15/16 Holstein composition (considered crossbred) and animals with more than 15/16 Holstein pedigree (considered purebred). Six calves were slaughtered at the start of the experiment to estimate the initial body composition of the animals. Of the remaining animals, four formed the maintenance group (fed 3 L/day of raw milk), and the other 32 were distributed into four treatments, which consisted of 6 L/day of raw milk, with increasing DM contents of 13.5%, 16.1%, 18.2% and 20.4% respectively. The DM contents were corrected for adding milk replacer to the raw milk. All animals had free access to starter feed and water. Digestibility trials were conducted at 28 and 56 days of life, with total faeces collection being performed for 5 days and urine collection for a period of 24 h. At 60 days of life, the animals were slaughtered to determine their body composition. Key results Net energy requirements for maintenance and metabolisable energy requirements for maintenance were 57.6 and 86.8 kcal/(empty bodyweight, EBW)0.75.day respectively. The efficiency of utilisation of metabolisable energy for maintenance was 66%. Net energy requirements for gain (NEg, Mcal/day) can be estimated by the following equation: , where EBG is empty body gain (kg/day) and EBW is in kilograms. The efficiency of utilisation of metabolisable energy for gain was 27%. The metabolisable-protein requirement for maintenance was 3.22 g/EBW0.75.day. Net protein requirement for gain (NPg, g/day) can be estimated by the following equation:, where RE is retained energy (Mcal/day). The efficiency of utilisation of metabolisable protein for gain was 59.1%. Conclusions Genetic group does not affect energy or protein requirements of pre-weaned calves. The estimates presented here can be used to calculate nutrient requirements of pre-weaned calves aged up to 60 days. Implications Inclusion of milk replacer in the liquid feed had a negative impact on diet quality.

Effects of supplementing yeast culture to diets differing in starch content on performance and feeding behavior of dairy cows

The objectives were to evaluate the effects of a culture of Saccharomyces cerevisiae (YC) on lactation performance of cows fed diets differing in starch content. Fifty-six Holstein cows at 42 d postpartum were blocked by parity and milk production and randomly assigned to 1 of 4 treatments, low starch (23% diet DM) and no YC (LS-control), low starch and 15 g/d of YC (LS-YC), high starch (29% diet DM) and no YC (HS-control), and high starch and 15 g/d of YC (HS-YC). The experiment lasted 14 wk. Blood was sampled twice weekly during the first 5 wk in the experiment. Feeding behavior was evaluated in 2 consecutive days when cows were 33 d in the experiment. On d 92 in the experiment, cows were challenged with 3 kg of corn grain DM immediately before the morning feeding. Blood was sampled in the first 12 h after the challenge. Rumen fluid was collected 5 h after the challenge, and pH, ammonia N, short-chain fatty acids, and lactate concentrations were quantified. Lactation performance was measured daily before and after the challenge. Supplementation with YC increased yields of 3.5% fat-corrected milk and energy-corrected milk by 2.2 and 2.0 kg/d, and the increments were observed in both low- and high-starch diets. Feeding HS tended to decrease milk fat content (LS = 3.88 vs. HS = 3.73%), but increased concentration (LS = 2.87 vs. HS = 3.00%) and yield (LS = 1.11 vs. HS = 1.20 kg/d) of milk true protein. Feeding YC increased yields of fat and true protein in milk by 100 and 60 g/d. Energy balance, body weight, and feed efficiency did not differ with treatments. Feeding HS reduced eating time (LS = 177 vs. HS = 159 min/12 h) and intermeal interval (LS = 103 vs. HS = 82 min), but tended to increase eating rate (LS = 139 vs. HS = 150 g/min). Interactions were detected between level of starch and YC for ruminating time, meal duration, and meal size because within LS, feeding YC increased ruminating time 23 min/12 h, but reduced meal duration 6 min/meal and meal size 0.7 kg/meal. Concentrations of glucose in plasma increased (LS = 62.1 vs. HS = 63.8 mg/dL), whereas those of urea N decreased (LS = 10.1 vs. HS = 9.4 mg/dL) with feeding HS compared with LS in the first 5 wk in the experiment, and the same responses were observed after the challenge with corn grain. After the challenge, rumen pH was less and short-chain fatty acid concentrations were greater in cows fed HS compared with those fed LS; however, supplementing YC to high-starch diets increased rumen pH (HS-control = 5.72 vs. HS-YC = 6.12) and reduced concentrations of lactate in rumen fluid (HS-control = 7.72 vs. HS-YC = 1.33 mM) and haptoglobin in plasma 28%. Feeding YC improved lactation performance irrespective of the level of dietary starch and reduced the risk of subacute rumen acidosis induced by a grain challenge when cows were fed a high-starch ration.

Murine melanoma cells incomplete reprogramming using non-viral vector

OBJECTIVES

The reprogramming of cancer cells into induced pluripotent stem cells or less aggressive cancer cells can provide a modern platform to study cancer-related genes and their interactions with cell environment before and after reprogramming. Herein, we aimed to investigate the reprogramming capacity of murine melanoma B16F10 cells.

MATERIALS AND METHODS

The B16F10 was transfected using non-viral circular DNA plasmid containing the genes Sox-2, Oct4, Nanog, Lin28 and green fluorescent protein (GFP). These cells were characterized by immunofluorescence, analysis RT-PCR and cell cycle.

RESULTS

Our results demonstrated for the first time that reprogramming of B16F10 may be induced using non-viral minicircle DNA containing the four reprogramming factors Oct4, Sox2, Lin 28, Nanog (OSLN) and the GFP reporter gene. The resulting clones are composed by epithelioid cells. These cells display characteristics of cancer stem cells, thus expressing pluripotent stem cell markers and dividing asymmetrically and symmetrically. Reprogrammed B16F10 cells did not form teratomas; however, they showed the suppression of tumourigenic abilities characterized by a reduced tumour size, when compared with parental B16F10 cell line. In contrast to parental cell line that showed accumulation of the cells in S phase of cell cycle, the cells of reprogrammed clones are accumulated in G1 phase. Long-term cultivation of reprogrammed B16F10 cells induces regression of their reprogramming.

CONCLUSIONS

Our data imply that in result of reprogramming of B16F10 cells less aggressive Murine Melanoma Reprogrammed Cancer Cells may be obtained. These cells represent an interesting model to study mechanism of cells malignancy as well as provide a novel tool for anti-cancer drugs screening.

The effects of increasing amounts of milk replacer powder added to whole milk on feed intake and performance in dairy heifers

The aim of this study was to evaluate the effects on feed intake, heifer performance, and health of increasing the total solids (TS) content of liquid feed (whole milk) by adding increasing amounts of milk replacer powder during the pre- and postweaning periods. Crossbred Holstein-Gyr heifers (n=60) were assigned to 1 of 4 treatments (n=15 per group), which consisted of different TS concentrations: 12.5, 15.0, 17.5, and 20.0% of liquid feed. Heifers received 6 L of liquid feed per day, divided into 2 equal meals (0800 and 1600h) and provided in buckets, from 5 to 55d of age. From 56 to 59d of age, the total amount of liquid feed was reduced by half, maintaining only morning feedings. Heifers were weaned at 60d and monitored until 90d of age. Water and starter were provided ad libitum during the entire experiment. Corn silage was included in the diet during the postweaning period (70d of age). Feed intake and health scores were evaluated daily. Body weight and body frame development were recorded weekly. Starting at 14d, ruminal pH was measured every other week. Laboratory analysis determined that the actual TS contents of the liquid feed were 13.5, 16.1, 18.2, and 20.4%, for the proposed 12.5, 15.0, 17.5, and 20.0% TS treatments, respectively. The osmolality of liquid feed treatments was 265 to 533mOsm/L. Intake of liquid feed was similar among treatments from 4wk of age. During the preweaning period, starter intake, fecal score, and days with diarrhea were similar among treatments. Ruminal pH at weaning averaged 6.2 and was similar among treatments. Increasing concentrations of TS in the liquid feed were associated with linear increases in average daily gain, final body weight, and growth performance, but linear decreases in feed efficiency. During the postweaning period, intake of starter, corn silage, and water were similar among treatments, as well as average daily gain and feed efficiency. Final body weight and growth performance during the postweaning period also increased linearly with concentration of TS in liquid feed. Increasing the concentration of TS in liquid feed up to 20.4% increased performance and body frame development in dairy heifers during the pre- and postweaning periods and had no effects on solid feed intake or health.

Antioxidant enzymes activities of Burkholderia spp. strains-oxidative responses to Ni toxicity

Increased agriculture production associated with intense application of herbicides, pesticides, and fungicides leads to soil contamination worldwide. Nickel (Ni), due to its high mobility in soils and groundwater, constitutes one of the greatest problems in terms of environmental pollution. Metals, including Ni, in high concentrations are toxic to cells by imposing a condition of oxidative stress due to the induction of reactive oxygen species (ROS), which damage lipids, proteins, and DNA. This study aimed to characterize the Ni antioxidant response of two tolerant Burkholderia strains (one isolated from noncontaminated soil, SNMS32, and the other from contaminated soil, SCMS54), by measuring superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione S-transferase (GST) activities. Ni accumulation and bacterial growth in the presence of the metal were also analyzed. The results showed that both strains exhibited different trends of Ni accumulation and distinct antioxidant enzymes responses. The strain from contaminated soil (SCMS54) exhibited a higher Ni biosorption and exhibited an increase in SOD and GST activities after 5 and 12 h of Ni exposure. The analysis of SOD, CAT, and GR by nondenaturing PAGE revealed the appearance of an extra isoenzyme in strain SCMS54 for each enzyme. The results suggest that the strain SCMS54 isolated from contaminated soil present more plasticity with potential to be used in soil and water bioremediation.

Benzofuroxan derivatives N-Br and N-I induce intrinsic apoptosis in melanoma cells by regulating AKT/BIM signaling and display anti metastatic activity in vivo

Background

Malignant melanoma is an aggressive type of skin cancer, and despite recent advances in treatment, the survival rate of the metastatic form remains low. Nifuroxazide analogues are drugs based on the substitution of the nitrofuran group by benzofuroxan, in view of the pharmacophore similarity of the nitro group, improving bioavailability, with higher intrinsic activity and less toxicity. Benzofuroxan activity involves the intracellular production of free-radical species. In the present work, we evaluated the antitumor effects of different benzofuroxan derivatives in a murine melanoma model.

Methods

B16F10-Nex2 melanoma cells were used to investigate the antitumor effects of Benzofuroxan derivatives in vitro and in a syngeneic melanoma model in C57Bl/6 mice. Cytotoxicity, morphological changes and reactive oxygen species (ROS) were assessed by a diphenyltetrasolium reagent, optical and fluorescence microscopy, respectively. Annexin-V binding and mitochondrial integrity were analyzed by flow cytometry. Western blotting and colorimetry identified cell signaling proteins.

Results

Benzofuroxan N-Br and N-I derivatives were active against murine and human tumor cell lines, exerting significant protection against metastatic melanoma in a syngeneic model. N-Br and N-I induce apoptosis in melanoma cells, evidenced by specific morphological changes, DNA condensation and degradation, and phosphatidylserine translocation in the plasma membrane. The intrinsic mitochondrial pathway in B16F10-Nex2 cells is suggested owing to reduced outer membrane potential in mitochondria, followed by caspase −9, −3 activation and cleavage of PARP. The cytotoxicity of N-Br and N-I in B16F10-Nex2 cells is mediated by the generation of ROS, inhibited by pre-incubation of the cells with N-acetylcysteine (NAC). The induction of ROS by N-Br and N-I resulted in the inhibition of AKT activation, an important molecule related to tumor cell survival, followed by upregulation of BIM.

Conclusion

We conclude that N-Br and N-I are promising agents aiming at cancer treatment. They may be useful in melanoma therapy as inducers of intrinsic apoptosis and by exerting significant antitumor activity against metastatic melanoma, as presently shown in syngeneic mice.

Assessment of the ozone tolerance of two soybean cultivars (Glycine max cv. Sambaíba and Tracajá) cultivated in Amazonian areas

Brazilian soybean cultivars (Glycine max Sambaíba and Tracajá) routinely grown in Amazonian areas were exposed to filtered air (FA) and filtered air enriched with ozone (40 and 80 ppb, 6 h/day for 5 days) to assess their level of tolerance to this pollutant by measuring changes in key biochemical, physiological, and morphological indicators of injury and in enzymatic and non-enzymatic antioxidants. Sambaíba plants were more sensitive to ozone than Tracajá plants, as revealed by comparing indicator injury responses and antioxidant stimulations. Sambaíba exhibited higher visible leaf injury, higher stomatal conductance, and a severe decrease in the carbon assimilation rate. Higher ozone level (80 ppb) caused an increase in cell death in both cultivars. Levels of malondialdehyde and hydrogen peroxide also increased in Tracajá exposed under 80 ppb. Sambaíba plants exhibited decreases in ascorbate and glutathione levels and in enzymatic activities associated with these antioxidants. The higher tolerance of the Tracajá soybean appeared to be indicated by reduced physiological injuries and lower stomatal conductance, which might decrease the influx of ozone and enhance oxidation-reduction reactions involving catalase, ascorbate peroxidase, ascorbate, and glutathione, most likely stimulated by higher hydrogen peroxide.

Enhanced transpiration rate in the high pigment 1 tomato mutant and its physiological significance

Tomato high pigment (hp) mutants represent an interesting horticultural resource due to their enhanced accumulation of carotenoids, flavonoids and vitamin C. Since hp mutants are known for their exaggerated light responses, the molecules accumulated are likely to be antioxidants, recruited to deal with light and others stresses. Further phenotypes displayed by hp mutations are reduced growth and an apparent disturbance in water loss. Here, we examined the impact of the hp1 mutation and its near isogenic line cv Micro-Tom (MT) on stomatal conductance (gs), transpiration (E), CO(2) assimilation (A) and water use efficiency (WUE). Detached hp1 leaves lost water more rapidly than control leaves, but this behaviour was reversed by exogenous abscisic acid (ABA), indicating the ability of hp1 to respond to this hormone. Although attached hp1 leaves had enhanced gs, E and A compared to control leaves, genotypic differences were lost when water was withheld. Both instantaneous leaf-level WUE and long-term whole plant WUE did not differ between hp1 and MT. Our results indicate a link between exaggerated light response and water loss in hp1, which has important implications for the use of this mutant in both basic and horticultural research.

Dermatan sulfate is the major metachromatic glycosaminoglycan in the integument of the anuran Bufo ictericus

Glycosaminoglycans from the ventral and dorsal integuments of the anuran Bufo ictericus were characterized based on biochemical and histochemical methods. Dermatan sulfate is the major metachromatic glycosaminoglycan found in these tissues, but small amount of heparan sulfate was also detected. The average molecular mass of the dermatan sulfate is approximately 20 kDa, similar to the glycosaminoglycan isolated from mammalian skin. In addition, the amphibian integument contains high amounts of hyaluronic acid, especially in the ventral area. We also observed that the glycosaminoglycans occur in the anuran integument as irregular deposits through the spongious dermis and in the mast cells, as revealed by histochemical analysis using Alcian blue, dimethylmethylene blue and toluidine blue stains. The concentration and composition of glycosaminoglycans found in the amphibian integument resemble those from mammalian skin except for the higher concentration of hyaluronic acid in the amphibian tissue. Possibly, this observation indicates that the function of the sulfated glycosaminoglycan in these tissues has been preserved during evolution, although the amphibian integument and the human skin have their own particular physiology.

Nickel elicits a fast antioxidant response in Coffea arabica cells

The antioxidant responses of coffee (Coffea arabica L.) cell suspension cultures to nickel (Ni) were investigated. Ni was very rapidly accumulated in the cells and the accumulation could be directly correlated with the increase of NiCl(2) concentration in the medium. At 0.05 mM NiCl(2) growth was stimulated, but at 0.5 mM NiCl(2), the growth rate was reduced. An indication of alterations in the presence of reactive oxygen species was detected by an increase in lipid peroxidation at 0.5 mM NiCl(2). Catalase (CAT; EC 1.11.1.6), glutathione reductase (GR; EC 1.6.4.2), ascorbate peroxidase (APX; EC 1.11.1.11), guaiacol peroxidase (GOPX; EC 1.11.1.7) and superoxide dismutase (SOD; EC 1.15.1.1) activities were increased, particularly at earlier NiCl(2) exposure times and the activities were higher at 0.5 mM NiCl(2) for most of exposure times tested. Non-denaturing PAGE revealed one CAT isoenzyme, nine SOD isoenzymes and four GR isoenzymes. The SOD isoenzymes were differentially affected by NiCl(2) treatment and one GR isoenzyme was increased by NiCl(2). NiCl(2) at 0.05 mM did not induce lipid peroxidation and the main response appeared to be via the induction of SOD, CAT, GOPX and APX activities for the removal of the reactive oxygen species and through the induction of GR to ensure the availability of reduced glutathione.

The aspartic acid metabolic pathway, an exciting and essential pathway in plants

Aspartate is the common precursor of the essential amino acids lysine, threonine, methionine and isoleucine in higher plants. In addition, aspartate may also be converted to asparagine, in a potentially competing reaction. The latest information on the properties of the enzymes involved in the pathways and the genes that encode them is described. An understanding of the overall regulatory control of the flux through the pathways is undisputedly of great interest, since the nutritive value of all cereal and legume crops is reduced due to low concentrations of at least one of the aspartate-derived amino acids. We have reviewed the recent literature and discussed in this paper possible methods by which the concentrations of the limiting amino acids may be increased in the seeds.

Expression pattern of glycoconjugates in the Bidderian and ovarian follicles of the Brazilian toad Bufo ictericus analyzed by lectin histochemistry

The Bidder's organ and ovary of the Brazilian toad Bufo ictericus were studied by light microscopy, using hematoxylin-eosin (HE) and periodic acid Schiff (PAS) staining. The expression and distribution of carbohydrate moieties was analyzed by lectin histochemistry, using 8 lectins with different carbohydrate specificities: Ulex europaeus (UEA I), Lens culinaris (LCA), Erythrina cristagalli (ECA), Arachis hypogaea (PNA), Ricinus communis (RCA I), Aleuria aurantia (AAA), Triticum vulgaris (WGA), and Glycine maximum (SBA). The results showed that the Bidderian zona pellucida presented alpha-mannose, alpha-L-fucose, beta-D-galactose, N-acetyl-D-glucosamine, and alpha/beta-N-acetyl-galactosamine residues. The Bidderian follicular cells showed the presence of beta-D-galactose and N-acetyl-D-glucosamine. In the extracellular matrix, alpha-mannose and alpha/beta-N-acetyl-galactosamine residues were detected. The ovarian zona pellucida showed alpha-L-fucose, N-acetyl-D-glucosamine, alpha/beta-N-acetyl-galactosamine residues, and alpha-mannose and N-acetyl-D-glucosamine residues were detected in the follicular cells. Thus, the zona pellucida in both organs contains N-acetyl-D-glucosamine, and alpha/beta-N-acetyl-galactosamine residues. alpha-L-fucose residues were detected in the zona pellucida of both organs, using different lectins. Considering that beta-D-galactose residue was absent from ovary but present in the Bidder's organ, this sugar residue may play an important role in follicle development, blocking the Bidderian follicles and preventing further development of the Bidder's organ into a functional ovary.

Morphology of Bufo ictericus integument (Amphibia, Bufonidae)

Bufo ictericus integument was investigated by stereoscopic, low vacuum scanning electron microscopy, transmission electron microscopy and light microscopy. The studies revealed, that the dorsal integument surface is rougher than ventral. Three types of projections are visualized: larger rounded verrucae, smaller conical cornified tubercles, and conical short spines. Prominent verrucae are observed on the dorsal surface, being flatter on the ventral surface. The tubercles are visualized only on the dorsal surface. The verrucae are separated by grooves that may contribute spreading and retention of the glandular secretion upon the integument. The pattern of the epidermal grooves is also important for water distribution, protecting the animal against desiccation. The epidermis is composed of a stratified epithelium with intraepithelial blood vessels, where keratinocytes predominate, but flask cells, and Merkel cells also occur. In the spongious dermis, cutaneous glands are visualized. The compact dermis is a series of alternating layers of bundles of collagenous fibers, and between spongious and compact dermis there are basophilic areas that correspond to Eberth-Katschenko layer. The dorsal and the ventral surfaces of B. ictericus are morphologically distinct. The integument structure is related to the physiology of each surface and represents an adaptation to habitat, reflecting a lifestyle of the animal.

Are high-lysine cereal crops still a challenge?

The essential amino acids lysine and threonine are synthesized in higher plants via a pathway starting with aspartate that also leads to the formation of methionine and isoleucine. Lysine is one of most limiting amino acids in plants consumed by humans and livestock. Recent genetic, molecular, and biochemical evidence suggests that lysine synthesis and catabolism are regulated by complex mechanisms. Early kinetic studies utilizing mutants and transgenic plants that over-accumulate lysine have indicated that the major step for the regulation of lysine biosynthesis is at the enzyme dihydrodipicolinate synthase. Despite this tight regulation, recent strong evidence indicates that lysine catabolism is also subject to control, particularly in cereal seeds. The challenge of producing crops with a high-lysine concentration in the seeds appeared to be in sight a few years ago. However, apart from the quality protein maize lines currently commercially available, the release of high-lysine crops has not yet occurred. We are left with the question, is the production of high-lysine crops still a challenge?

Evaluation of biochemical and serological methods to identify and clustering yeast cells of oral Candida species by CHROMagar test, SDS-PAGE and ELISA

The purpose of this work was to evaluate biochemical and serological methods to characterize and identify Candida species from the oral cavity. The strains used were five Candida species previously identified: C. albicans, C. guilliermondii, C. parapsilosis, C. krusei, C. tropicalis, and Kluyveromyces marxianus, as a negative control. The analyses were conducted through the SDS-PAGE associated with statistical analysis using software, chromogenic medium, and CHROMagar Candida (CA), as a differential medium for the isolation and presumptive identification of clinically important yeasts and an enzyme-linked immunoabsorbent assay (ELISA), using antisera produced against antigens from two C. albicans strains. This method enabled the screening of the three Candida species: C. albicans, C. tropicalis, and C. krusei, with 100% of specificity. The ELISA using purified immunoglobulin G showed a high level of cross-reaction against protein extracts of Candida species. The SDS-PAGE method allowed the clustering of species-specific isolates using the Simple Matching coefficient, S(SM) = 1.0. The protein profile analysis by SDS-PAGE increases what is known about the taxonomic relationships among oral yeasts. This methodology showed good reproducibility and allows collection of useful information for numerical analysis on information relevant to clinical application, and epidemiological and systematical studies.

Mandibular ramus-related Stafne's bone cavity

Mandibular bone depressions located on the lingual/buccal aspect of the mandibular ramus are the rarest variants of the so-called Stafne's bone cavities, or major salivary gland-related depressions, with only 17 cases reported in the literature including both clinical cases and archaeological specimens. We report the case of a 14-year-old male patient who sought clinical assistance complaining of a hard expansion on the lower left premolar-molar region. Apart from a unilocular radiolucent lesion between the lower left second premolar and first molar, a panoramic radiograph showed another radiolucent lesion located in the right mandibular ramus, at the level of the mandibular foramen. Computed tomography (CT) revealed an expansile lesion in the left mandibular body, later diagnosed as a simple bone cyst through surgical exploration. The three-dimensional CT volume rendering reconstructed image showed that the second lesion, located on the lingual aspect of the ascending ramus, was an actual cortical bone defect, which was diagnosed as a mandibular ramus-related Stafne's bone cavity. Considering the young age of the patient, the size of the defect, the recognizedly slow development of mandibular bone defects and, above all, the location of the bone defect under discussion, we believe it to have a congenital rather than a developmental origin (i.e. it was caused by a focal failure during intramembranous ossification of the mandible). If this is the case, mandibular bone depressions should not be seen exclusively as salivary gland-related bone defects.

Isolation of the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase from Phaseolus vulgaris

Lysine is catabolyzed by the bifunctional enzyme lysine 2-oxoglutarate reductase-saccharopine dehydrogenase (LOR-SDH) in both animals and plants. LOR condenses lysine and 2-oxoglutarate into saccharopine, using NADPH as cofactor and SDH converts saccharopine into alpha-aminoadipate delta-semialdehyde and glutamic acid, using NAD as cofactor. The distribution pattern of LOR and SDH among different tissues of Phaseolus vulgaris was determined. The hypocotyl contained the highest specific activity, whereas in seeds the activities of LOR and SDH were below the limit of detection. Precipitation of hypocotyl proteins with increasing concentrations of PEG 8000 revealed one broad peak of SDH activity, indicating that two isoforms may be present, a bifunctional LOR-SDH and possibly a monofunctional SDH. During the purification of the hypocotyl enzyme, the LOR activity proved to be very unstable, following ion-exchange chromatography. Depending on the purification procedure, the protein eluted as a monomer of 91-94 kDa containing only SDH activity, or as a dimer of 190 kDa with both, LOR and SDH activities, eluting together.

Analysis of the aspartic acid metabolic pathway using mutant genes

Amino acid metabolism is a fundamental process for plant growth and development. Although a considerable amount of information is available, little is known about the genetic control of enzymatic steps or regulation of several pathways. Much of the information about biochemical pathways has arisen from the use of mutants lacking key enzymes. Although mutants were largely used already in the 60's, by bacterial and fungal geneticists, it took plant research a long time to catch up. The advance in this area was rapid in the 80's, which was followed in the 90's by the development of techniques of plant transformation. In this review we present an overview of the aspartic acid metabolic pathway, the key regulatory enzymes and the mutants and transgenic plants produced for lysine and threonine metabolism. We also discuss and propose a new study of high-lysine mutants.

Lysine metabolism in higher plants

The essential amino acid lysine is synthesised in higher plants via a pathway starting with aspartate, that also leads to the formation of threonine, methionine and isoleucine. Enzyme kinetic studies and the analysis of mutants and transgenic plants that overaccumulate lysine, have indicated that the major site of the regulation of lysine synthesis is at the enzyme dihydrodipicolinate synthase. Despite this tight regulation, there is strong evidence that lysine is also subject to catabolism in plants, specifically in the seed. The two enzymes involved in lysine breakdown, lysine 2-oxoglutarate reductase (also known as lysine a-ketoglutarate reductase) and saccharopine dehydrogenase exist as a single bifunctional protein, with the former activity being regulated by lysine availability, calcium and phosphorylation/ dephosphorylation.

Antioxidant enzymes responses to cadmium in radish tissues

To investigate the antioxidant responses of radish (Raphanus sativus L.) to cadmium (Cd) treatment, seedlings of a tolerant variety were grown in increasing concentrations of CdCl(2), ranging from 0.25-1 mM, for up to 72 h in a hydroponic system. Analysis of Cd uptake indicated that most of the Cd accumulated in the roots, but some was also translocated and accumulated in the leaves, especially at the higher concentrations of Cd used in the experiments. Roots and leaves were analysed for catalase, glutathione reductase and superoxide dismutase activities. Catalase and glutathione reductase activities increased considerably in the roots and leaves after 24 h exposure to the metal, indicating a direct correlation with Cd accumulation. The analysis of native PAGE enzyme activity staining, revealed several superoxide dismutase isoenzymes in leaves, with the two predominant isoenzymes exhibiting increases in activity in response to Cd treatment. The results suggest that in radish, the activity of antioxidant enzymes responds to Cd treatment. The main response may be via the activation of the ascorbate-glutathione cycle for the removal of hydrogen peroxide, or to ensure the availability of glutathione for the synthesis of Cd-binding proteins.

Soybean leghemoglobin targeted to potato chloroplasts influences growth and development of transgenic plants

 Potato tubers were transformed with a chimeric gene made by the fusion of the soybean leghemoglobin encoding gene (lba) with the chloroplastic targeting sequence from Rubisco. This construct was placed under the control of the strong constitutive 35S promoter and the 3' nontranslated region of Rubisco from pea. Leghemoglobin expression on kanamycin-resistant plants was monitored by RT-PCR. Furthermore, immunodetection of subcellular fractions of transgenic plants revealed that leghemoglobin was imported and correctively processed inside the organelle. In addition, analysis of transgenic plants revealed reduced growth and decreased tuber production compared with the untransformed plants. It is suggested that leghemoglobin expression in potato chloroplasts interferes with aerobic metabolism, leading to physiological and morphological changes.

Targeting of the soybean leghemoglobin to tobacco chloroplasts: effects on aerobic metabolism in transgenic plants

Several attempts have been made to alter the aerobic metabolism of plants, especially those related to the oxygenation or carboxylation of Rubisco. However, designing a more efficient Rubisco protein is rather problematic since its structural manipulation leads frequently to an enhancement of oxygenase activity, which is responsible for photorespiratory losses. In order to reduce oxygen availability inside the chloroplast, a chimeric gene consisting of a soybean leghemoglobin cDNA (lba) ligated to the chloroplast targeting signal sequence of the Rubisco small subunit gene, was introduced and expressed in Nicotiana tabacum. Lb was efficiently imported and correctly processed inside the chloroplasts of transgenic tobacco plants. Furthermore, the level of Lb expression in leaf tissue ranged from 0.01 to 0.1%. Analysis of photosynthesis, starch, sucrose and enzymes involved in aerobic metabolism, revealed that despite the high affinity of Lb for oxygen, no significant difference was observed in relation to the control plants. These results suggest that higher Lb concentrations would be required inside the chloroplasts in order to interfere on aerobic metabolism.

Quality protein maize: a biochemical study of enzymes involved in lysine metabolism

Quality protein maize (QPM) varieties have been produced by the introduction of opaque-2 modifier genes. Two QPM varieties, BR451 and BR473, a wild type and an opaque-2 variety, have been used to study key enzymes controlling lysine metabolism in the endosperm during development. Aspartate kinase and homoserine dehydrogenase enzymes, which are involved in lysine and threonine biosynthesis, respectively, exhibited identical activity patterns during endosperm development, with a maximum specific activity at 16 days after pollination. The QPM varieties exhibited higher levels of aspartate kinase activity in the endosperm, suggesting an increased rate of lysine biosynthesis when compared to the opaque-2 and wild-type genotypes. Similar results were observed for the lysine ketoglutarate reductase and saccharopine dehydrogenase enzymes, which form a single bifunctional polypetide involved in endosperm lysine degradation. Both enzyme activities were strongly reduced in the opaque-2 maize variety when compared to the wild-type maize, whereas the QPM varieties exhibited even lower levels of lysine ketoglutarate reductase-saccharopine dehydrogenase activities when compared to the opaque-2 variety. The developmental pattern of enzyme activity showed a different profile when compared to the enzymes involved in lysine biosynthesis, with activity being detected only 12-16 days after pollination (DAP) and maximum activities approximately 24 DAP. These results also suggest that the modifier genes have intensified the effect of the opaque-2 mutation on lysine ketoglutarate reductase-saccharopine dehydrogenase. These alterations lead to an increase in soluble lysine in the endosperm of the QPM varieties when compared to the opaque-2 and wild type.

Structure and regulation of the bifunctional enzyme lysine-oxoglutarate reductase-saccharopine dehydrogenase in maize

The lysine-oxoglutarate reductase (LOR) domain of the bifunctional enzyme lysine-oxoglutarate reductase-saccharopine dehydrogenase (LOR/SDH) from maize endosperm was shown to be activated by Ca2+, high salt concentration, organic solvents and Mg2+. The Ca2+-dependent enhancement of LOR activity was inhibited by the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) and calmidazolium. Limited proteolysis was used to assess the structure/function relationship of the enzyme. Digestion with elastase separated the bifunctional 125-kDa polypeptide into two polypeptides of 65 kDa and 57 kDa, containing the functional domains of LOR and SDH, respectively. Proteolysis did not affect SDH activity, while LOR showed a time-dependent and protease-concentration-dependent inactivation followed by reactivation. Prolonged digestion or increasing amounts of elastase produced a complex pattern of limit polypeptides derived from additional cleavage sites within the 65-kDa (LOR) and 57-kDa (SDH) domains. The SDH-containing polypeptides inhibited the enzymatic activity of LOR-containing polypeptides. When separated from the SDH domain by limited proteolysis and ion-exchange chromatography, the LOR domain retained its Ca2+ activation property, but was no longer activated by high salt concentrations. These results suggest that the LOR activity of the native enzyme is normally inhibited such that after modulation, the enzyme undergoes a conformational alteration to expose the catalytic domain for substrate binding.

The biosynthesis and metabolism of the aspartate derived amino acids in higher plants

The essential amino acids lysine, threonine, methionine and isoleucine are synthesised in higher plants via a common pathway starting with aspartate. The regulation of the pathway is discussed in detail, and the properties of the key enzymes described. Recent data obtained from studies of regulation at the gene level and information derived from mutant and transgenic plants are also discussed. The herbicide target enzyme acetohydroxyacid synthase involved in the synthesis of the branched chain amino acids is reviewed.

The enzymology of lysine catabolism in rice seeds--isolation, characterization, and regulatory properties of a lysine 2-oxoglutarate reductase/saccharopine dehydrogenase bifunctional polypeptide

In plant, the catabolism of lysine has only been studied in some detail in maize. The enzymes lysine 2-oxoglutarate reductase (also known as lysine alpha-ketoglutarate reductase; LOR) and saccharopine dehydrogenase (SDH), which convert lysine into saccharopine, and saccharopine into glutamic acid and 2-aminoadipate 6-semialdehyde, respectively, were isolated from immature rice seeds and partially purified through a three-step purification procedure involving ammonium sulphate precipitation, and anion-exchange and gel-filtration chromatographies, leading to a final yield of 30% for LOR and 24% for SDH. The molecular masses estimated by gel-filtration chromatography on a Sephacryl S200 column and by native non-denaturing PAGE using Ferguson plots were 203 kDa for both enzymes by gel-filtration and 202 kDa for both enzymes by native non-denaturing PAGE. A second band of LOR and SDH activities on native gels was observed for both enzymes with an estimated molecular mass of 396 kDa, which indicated a multimeric structure. Kinetic studies were consistent with an ordered sequence mechanism for LOR, where 2-oxoglutarate is the first substrate and saccharopine is the last product. The results observed for the LOR/SDH activity ratios during purification, the copurification in all three steps, the molecular masses, the relative mobilities on native non-denaturing gels and the pI estimated for LOR and SDH suggest the existence of a bifunctional polypeptide containing LOR and SDH activities.

[Prevalence of serologic markers of hepatitis B and D viruses in children of the Caiabi and Txucarramãe tribes from the Indian Reservation of Xingu, central Brazil]

The medical literature has shown that the inhabitants of the Amazon region are highly affected by hepatitis B and delta viruses infection, but this has never been studied in Indian children by age group. A study of the prevalence of serological markers of hepatitis B and delta viruses in Indian children aged 0 to 14 years living in the PIX was carried out. This Park is located in Central Brazil, a region which is in the transition between the savannab to the south and the Amazon jungle to the north. To determine the prevalence of HBV and HDV markers in Indian children and to characterize the route of HBV transmission in this region. Out of the 17 tribes living in the PIX, two--the Caiabi and the Txucarramãe--were chosen because both live in the North part of the Park, but have quite different ways of life. The overall prevalence of HBV serum markers was: HBsAg, 4.5%; anti-HBs, 39.6%; anti-HBc, 44.1%; any marker of HBV, 47.3%; and anti-HDV, 0.0%. However, a striking difference in the prevalence of hepatitis B markers was observed between the two tribes: younger Caiabi children were much less affected than the Txucarramãe ones. The prevalence of HBsAg in fertile women was 12%, being anti-HBe positive. Our data suggest that HBV infection is highly prevalent among Indian children living in this Indigenous Park and vertical infection is not an important route of transmission in either tribes.

Clinical evaluation of luteal function

OBJECTIVE

To determine the ability of luteal phase length determined by basal body temperature (BBT) pattern and a midluteal serum progesterone level to predict the result of an endometrial biopsy in a subsequent cycle.

METHODS

We performed a retrospective analysis of 141 women with a history of infertility who were being evaluated for luteal function. The luteal phase length determined from a BBT chart of one menstrual cycle was compared to a single midluteal serum progesterone level from a second menstrual cycle. These findings were compared to a luteal phase endometrial biopsy performed in a third menstrual cycle. Subjects were divided into four groups depending upon luteal phase length (normal 11 or more days) and serum progesterone level (normal at least 10 ng/mL). The four groups were designated "normal," "short luteal phase," "low progesterone," and "abnormal," depending upon the results of the two tests. The frequency of in- and out-of-phase endometrial biopsy results in the four groups was compared.

RESULTS

There was no difference in the occurrence of an in- or out-of-phase endometrial biopsy when the four groups were compared.

CONCLUSION

Neither luteal phase length nor a single midluteal serum progesterone level was predictive of subsequent in-phase or out-of-phase endometrial biopsy.

Lanthanum nitrate labelling of the outer cell wall surface of phagocytized Paracoccidioides loboi in human lobomycosis

Lesioned skin tissues from a female Caiabi indian with lobomycosis were processed for routine electron microscopy using, in the initial steps, solutions containing 2% lanthanum nitrate. The pattern of tracer distribution suggests that the tracer penetrates into the cavity containing the parasite through exocytotic-like apertures situated at the cell wall outer region. The tracer also infiltrates the virtual space between the cell wall and its recovering membrane, spreading over varying areas of the outer surface of the cell wall. The contrast imparted to the pericellular macrophage space by the lanthanum nitrate enabled easy localization of fibrillar, cell wall derived material which reaches the adjacent extracellular milieu.