Protein Reserves Research Articles

ФОТОФОСФОРИЛИРОВАНИЕ, СТРУКТУРА ХЛОРОПЛАСТОВ И АМИНОКИСЛОТНЫЙ СОСТАВ ЗАПАСНОГО БЕЛКА В ЗЕРНЕ ЯЧМЕНЯ И ПШЕНИЦЫ ПРИ ОБРАБОТКЕ РАСТЕНИЙ N,N-ДИФЕНИЛМОЧЕВИНОЙ

The numerous data suggest an important role of phytohormones, particularly cytokinins, in regulation of plants growth and development. The cytokinins stimulates the cells division, takes part in cells differentiation and other physiological processes. In the present paper the effect of N,N-diphenylurea (DPU), a compound possessing cytokinine activity, on the rate of photophosphorylation and thylakoid membrane structure of chloroplasts in milky phase as well as on amino acid composition of reserve protein of barley ( Hordeum vulgare L.) of the Trumpf and Odesskii varieties and wheat ( Triticum aestivum L.) of the Moskovskaya 35 and Tulunskaya varieties was investigated. The treatment with DPU changed the rates of cyclic and acyclic photophosphorylation of thylakoid membrane isolated from flag leaves of treated plants and induced destructive changes in chloroplasts. The changes in percentage ratio of a number of amino acids in reserve grain protein, especially proline, were shown. The modifications in mesophyll cells of chloroplasts after DPU treatment suggest that an action of this compound at the beginning of milky phase accelerates the process of plants aging, but its action at the beginning of flowering phase results in converse effect. A conclusion was done that DPU controls energy metabolism in the leaves and protein exchange in grain of wheat and barley plants.

Development of coffee somatic and zygotic embryos to plants differs in the morphological, histochemical and hydration aspects

In Coffea arabica L., the development of direct sowing of somatic embryos (SE) in planting substrate, with subsequent nursery production of plants, has promoted the industrialization of somatic embryogenesis. However, plant conversion rates are still low and require improvements to enhance the cost-effectiveness of commercial micropropagation. With the aim of improving plant regeneration from SE, we studied the morphological and histological criteria and water characteristics during germination and plant conversion of zygotic embryos (ZE) and SE. At the cotyledonary stage, SE produced in a 1 l RITA(®) temporary immersion bioreactor (area 55.8 cm(2)) were morphologically similar in size (2-3 mm) but abnormal as compared with mature ZE. Protein and starch reserve levels were extremely low throughout germination and conversion to plantlets, while the water status remained steady [water content (WC) from 76 to 87%, Ψ from -0.37 to -0.47 MPa, pressure potential from 0.69 to 0.24 MPa]. In ZE, spectacular hydration occurred during the first 3 weeks (WC from 37 to 75%; Ψ from -6.24 to -1.0 MPa). Cotyledons remained undifferentiated for 10 weeks after sowing. Conversely, after only 3 weeks under germination conditions in a RITA(®) bioreactor, spongy and palisade parenchyma and stomata formed in SE cotyledons. The ZE plant conversion was faster than that of SE (14 vs. 22 weeks) and more efficient (rates 96 vs. 55%), with much more substantial hypocotyl and cotyledon development. The use of a new 5 l MATIS(®) bioreactor (area 355 cm(2)), designed especially to favor embryo dispersion and light transmittance to SE, markedly improved the embryo-to-plantlet conversion rate (91%). These results highlight the morphological heterogeneity and lack of protein reserves in SE at the beginning of the germination phase and marked differences in water characteristics. However, they also reveal high phenotypic plasticity, leading to a highly efficient plantlet conversion rate due to better embryo dispersion and light transmittance in more horizontal bioreactors.

Influence of Three Nitrogen Fertilization Schedules on Bermudagrass and Seashore Paspalum: II. Carbohydrates and Crude Protein in Stolons

ABSTRACTIn the transition zone, a primary concern in managing warm‐season turfgrasses is turf survival under low temperatures. The objectives of this study were to determine the effects of three N fertilization schedules on stolon carbohydrates and crude protein (CP) reserves of four bermudagrasses [Cynodon dactylon (L.) Pers.] and a seashore paspalum (Paspalum vaginatum Sw.). A field trial was performed at the agricultural experimental farm of Padova University (northeastern Italy). Bermudagrass cultivars Princess‐77, Riviera, SWI 1014, and Yukon and seashore paspalum ‘Sea Spray’ were compared under three N fertilization schedules: (i) 6.7 g N m–2 on 15 May, 15 June, and 15 August, (ii) 5 g N m–2 on 15 May, 15 June, 15 August, and 15 October, and (iii) 4 g N m–2 on 15 May, 15 June, 15 August, 15 September, and 15 October. Turf samples measuring 20 by 20 by 4 (depth) cm were collected monthly from September to April 2009 to 2010 and 2010 to 2011. The stolons were separated from the remainder of the samples and starch, water‐soluble carbohydrates (WSC), and CP were determined on a dry matter basis. The bermudagrass cultivar Riviera was characterized by high stolon density and showed highest carbohydrates (starch and WSC) content along with Yukon. Late‐season applications of N had limited influence on carbohydrates content but increased the concentrations of CP from November through April.

Plasticity in Learning Causes Immediate and Trans-Generational Changes in Allocation of Resources

Plasticity in the development and expression of behavior may allow organisms to cope with novel and rapidly changing environments. However, plasticity itself may depend on the developmental experiences of an individual. For instance, individuals reared in complex, enriched environments develop enhanced cognitive abilities as a result of increased synaptic connections and neurogenesis. This suggests that costs associated with behavioral plasticity-in particular, increased investment in "self" at the expense of reproduction-may also be flexible. Using butterflies as a system, this work tests whether allocation of resources changes as a result of experiences in "difficult" environments that require more investment in learning. We contrast allocation of resources among butterflies with experience in environments that vary in the need for learning. Butterflies with experience searching for novel (i.e., red) hosts, or searching in complex non-host environments, allocate more resources (protein and carbohydrate reserves) to their own flight muscle. In addition, butterflies with experience in these more difficult environments allocate more resources per individual offspring (i.e., egg size and/or lipid reserves). This results in a mother's experience having significant effects on the growth of her offspring (i.e., dry mass and wing length). A separate study showed this re-allocation of resources comes at the expense of lifetime fecundity. These results suggest that investment in learning, and associated changes in life history, can be adjusted depending on an individual's current need, and their offspring's future needs, for learning.

Risk‐sensitive allocation in seasonal dynamics of fat and protein reserves in a long‐lived mammal

Body reserves of numerous taxa follow seasonal rhythms that are a function of temporal patterns in food availability and life-history events; however, tests of the theory underlying the allocation of somatic reserves for long-lived organisms are rare, especially for free-ranging mammals. We evaluated the hypothesis that allocation of somatic reserves to survival (i.e., metabolic processes) and reproduction should be sensitive to current nutritional state relative to seasonal thresholds in those reserves. Our goal was to reveal the linkages between nutrition and life-history traits to understand how long-lived, iteroparous organisms balance the allocation of somatic reserves to reproduction, while retaining reserves as insurance for survival in unpredictable environments. Our evaluation was based on seasonal dynamics in fat (measured as ingesta-free body fat; IFBFat) and protein reserves (measured as ingesta-free, fat-free body mass; IFFFBMass) of 136 female mule deer (Odocoileus hemionus) over 8years. Although mean changes in fat and protein reserves were positive over summer and negative over winter, accretion and catabolism of those reserves was not consistent among individuals. Over winter, both lipid and protein stores available in autumn were catabolized in proportion to their availability above a post-winter threshold (5·8% IFBFat, 33kg IFFFBMass); however, lean body tissue was spared at the expense of lipid reserves. Female deer mostly synthesized lean body tissue over summer and committed post-winter fat reserves to reproduction relative to their availability above an autumn threshold (>8·6% IFBFat), which was lowered by 2·8 percentage points (pp) for each additional young recruited. Mothers reduced their autumn fat threshold to secure current reproductive investment and, thereby, endured a cost of reproduction at the expense of fat accumulation. Allocation of somatic reserves occurred in a risk-sensitive framework; females allocated reserves relative to their availability above seasonal thresholds. In contrast to current notions of summer accretion and winter catabolism of body reserves, some individuals deposited reserves over winter and catabolized reserves over summer, mainly because regulation of individual condition was state-dependent. Consequently, behaviour and life-history strategies may be as much a function of nutritional contributions of the previous season as of the current one.

Ammonium as sole N source improves grain quality in wheat

The skilful handling of N fertilizer, including N source type and its timing, is necessary to obtain maximum profitability in wheat crops in terms of production and quality. Studies on grain yield and quality with ammonium as sole N source have not yet been conducted. The aim of this study was to evaluate the effect of N source management (nitrate vs. ammonium), and splitting it into two or three amendments during the wheat life cycle, on grain yield and quality under irrigated conditions. This experiment demonstrates that Cezanne wheat plants growing with ammonium as exclusive N source are able to achieve the same yield as plants growing with nitrate and that individual wheat plants grown in irrigated pots can efficiently use late N applied in GS37. Ammonium nutrition increased both types of grain reserve proteins (gliadins and glutenins) and also increased the ratio gli/glu with respect to nitrate nutrition. The splitting of the N rate enhanced the ammonium effect on grain protein composition. The application of ammonium N source, especially when split into three amendments, has an analogous effect on grain protein content and composition to applications at a higher N rate, leading to higher N use efficiency.

Measurement of mid-arm muscle circumference and prognosis in stage IV non-small cell lung cancer patients

Overall survival (OS) varies widely in patients with stage IV non-small cell lung cancer (NSCLC). Strong prognostic factors are still needed to improve decision-making regarding standard treatment options, to stratify patients for inclusion in innovative therapeutic trials and to identify patients who would be best treated with palliative care rather than with systemic chemotherapy. Mid-arm muscle circumference (MAMC) is a bedside anthropometric measurement that estimates somatic protein reserve, an early indicator of nutritional depletion. This measurement is simple, non-invasive, objective and inexpensive to perform. We evaluated MAMC as a potential prognostic factor in patients with stage IV NSCLC. A total of 56 non-selected consecutive patients with stage IV NSCLC were evaluated. The MAMC measurement results for these patients were expressed as a percentage of the expected reference values, adjusted for gender and age. Patients were categorized as normal (MAMC ≥90%) or depleted (MAMC <90%). The mean age of patients was 63 years (range 47–80), and the mean MAMC was 89 (range 66–122), with 55% of patients classified as depleted. The median OS was 6.2 months (95% CI, 5.1–7.3). In the subgroup with normal MAMC, the median OS was 10.2 months (95% CI, 9.2–11.1). In patients classified as depleted, the median OS was 5.0 months (95% CI, 4.2–5.8). The difference in OS between these two subgroups was highly significant (p<0.001 by the log-rank test; HR=0.21; 95% CI, 0.09–0.5 for patients with normal MAMC). In a multivariate analysis with Karnofsky status, age and gender as covariates, the difference in OS between the MAMC groups remained statistically significant (p<0.001, according to the Cox proportional hazards model). MAMC is a strong independent prognostic factor in stage IV NSCLC patients. Patients with MAMC <90% of the expected value had poor OS.

Changes in back fat thickness during late gestation predict colostrum yield in sows

Directing protein and energy sources towards lactation is crucial to optimise milk production in sows but how this influences colostrum yield (CY) remains unknown. The aim of this study was to identify associations between CY and the sow’s use of nutrient resources. We included 37 sows in the study that were all housed, fed and managed similarly. Parity, back fat change (ΔBF), CY and performance parameters were measured. We obtained sow serum samples 3 to 4 days before farrowing and at D1 of lactation following overnight fasting. These were analysed for non-esterified fatty acids (NEFA), urea, creatinine, (iso)butyrylcarnitine (C4) and immunoglobulins G (IgG) and A (IgA). The colostrum samples collected 3, 6 and 24 h after the birth of the first piglet were analysed for their nutrient and immunoglobulins content. The technical parameters associated with CY were parity group (a; parities 1 to 3=value 0 v. parities 4 to 7=value 1) and ΔBF D85-D109 of gestation (mm) (b): CY (g)=4290–842a–113b. (R2=0.41, P<0.001). The gestation length (P<0.001) and the ΔBF between D109 and D1 of lactation (P=0.050) were identified as possible underlying factors of the parity group. The metabolic parameters associated with CY were C4 at 3 to 4 days before farrowing (a), and 10logC4 (b) and 10logNEFA (c) at D1 of lactation: CY (g)=3582–1604a+1007b−922c (R2=0.39, P=0.001). The colostrum composition was independent of CY. The negative association between CY and ΔBF D85-D109 of gestation could not be further explained based on our data. Sows that were catabolic 1 week prior to farrowing seemed unable to produce colostrum to their full potential. This was especially the case for sows with parities 4 to 7, although they had a similar feed intake, litter birth weight and colostrum composition compared with parities 1 to 3 sows. In conclusion, this study showed that parity and the use of body fat and protein reserves during late gestation were associated with CY, indicating that proper management of the sow’s body condition during late gestation could optimise the intrinsic capacity of the sow’s CY.

Protein Bodies in Cotyledon Cells Exhibit Differential Patterns of Legumin-Like Proteins Mobilization during Seedling Germinating States

Olive (Olea europaea L.) tree is one of the most extensive and important agricultural crop in Mediterranean countries due to its beneficial health and nutritional properties and its high economic value. Currently, olive tree constitutes the sixth most important cultivated plant in the world, spreading from the Mediterranean region of origin to new production areas such as Australia, South and North America and South Africa. However, the mobilization processes of storage materials i.e. reserve proteins during seed germination, which are largely involved in essential physiological process including plant growth and development, remain poorly understood. Morphometric and immunohistochemistry analyses of protein bodies contained in olive seed storage tissues, cotyledon and endosperm, were performed by using different microscopy techniques, including light (bright-field and fluorescence) microscopy and transmission electron microscopy. Furthermore, we used legumin-like proteins (11S-type globulins) as a molecular marker to study the mobilization of reserve proteins from PBs of cotyledons at germinating seedling stages by using immunofluorescence assays. Results demonstrated that cotyledon and endosperm are characterized by distinct PBs populations containing legumin-like proteins, distinctly discriminated by the number of PBs per cell and tissue, size, immunofluorescence and histochemical staining. These features reflect differential PBs biogenesis during development and maturation processes in olive seed tissues endosperm and cotyledon, in relation to proteins (polypeptides) final composition, SSPs processing and/or packaging during seed maturation. Three different mobilization patterns of legumin-like proteins were identified for the first time in cotyledon PBs during seedling germinating process. Mature proteins composition and/or processing, cell types and enzyme composition and/or differential activation have been discussed as key features determining how proteins mobilize from PBs for further degradation in the cotyledon.

Effects of treatment of the fat body trophocytes of Melipona quadrifasciata anthidioides nurse workers and virgin queens in culture by juvenile hormone III and ecdysterone (20‐HE)

The fat body (FB) consists of two types of cells: throphocytes and oenocytes. Throphocytes are related to intermediary metabolism storing lipids, carbohydrates, and proteins while oenocytes play role in the lipids and lipoproteins production. The vitellogenin is the precursor of egg yolk (vitelline) and is synthesized on FB. The aim of this work was to analyze the effects of hormones acting in bee reproduction, as juvenile hormone (JH) and ecdisteroids (20 HE) on FB cells, where vitellogenin is synthesized. For the study were chose nurse workers that in Melipona quadrifasciata anthidioides present activated ovaries and produce eggs, and virgin queens whose ovaries are not yet activated, presenting only previtellogenic follicles. FB trophocytes from these classes of bees were cultivated in media containing different amounts of JH and 20-HE. The effects on trophocytes cytoplasm reserves of lipids, proteins, and activity of acid phosphatase were compared by observing preparations from cultured FB, treated and control, by transmission electron microscopy (TEM). The results showed that the hormones effects are related to the bee's caste and functional ovary stage. The role of acid phosphatase on mobilization of the trophocyte reserves was also determined.

Mobilization of Reserve Proteins and Activities of Cysteine Peptidases During Germinative and Post-Germinative Events of Cowpea Seeds

Cysteine peptidases are the best characterized peptidases among those involved with storage protein mobilization during seed germination. In the present work we show two major groups of cysteine peptidase activities, one of higher (55 to 97 kDa) and other with lower (15 to 20 kDa) molecular masses which are temporally activated after 24 and 48 HAI, respectively, in germinating cowpeas. The former group is found both in protein bodies and in cytoplasmic fraction, while the latter is mostly present outside protein bodies. A third cysteine peptidase activity of ~37 kDa was specifically active at quiescent cotyledons and at 12 and 60 hours after imbibition (HAI). Main peptidase activities of albumin fractions were synchronizedly detected with radicle emergence at 36 HAI. Major vicilin mobilization was more pronounced from 60 HAI onwards and steadily increased until 144 HAI, when low levels of the smallest vicilin subunit were present. Cysteine peptidases were susceptible to iodoacetamide, E-64, iodoacetic acid, pCMB and β-mercaptoethanol, except for the ~37 kDa peptidase, which was not affected by any of the inhibitors. By a two-dimensional native/SDS-PAGE combination it was observed an apparent linear arrangement of protein breakdown products as well as of peptidase activity spots. The finding may indicate a complex set of sequential proteolytic events where peptidases induce or activate new peptidases, which may act upon different aggregates or zymogens, and these hydrolysis products appear in a line of constant decreasing Rf x Mr ratio.

Missing pieces in protein deposition and mobilization inside legume seed storage vacuoles: calcium and magnesium ions

AbstractDuring the maturation of dicotyledonous seeds, organic carbon, nitrogen and sulphur are stored in protein storage vacuoles (PSVs) as storage globulins. Several studies point to the coexistence of storage proteins with proteases responsible for their degradation inside PSVs. Different mechanisms have been proposed to explain why there is no proteolysis during this period. Protein aggregation to form large supramolecular structures resistant to proteolytic attack could be the reason. However, during germination, and particularly following its completion, the globulin aggregates must undergo disintegration to allow protease attack for protein reserve mobilization. Based on the well-described concentration-dependent ability of Ca2+ and Mg2+ to promote in vitro aggregation and disaggregation of globulins, we explored a possible role for these alkaline earth cations in globulin packaging and mobilization. Ca2+ and Mg2+ measurements in purified PSVs [6.37 μmol and 43.9 μmol g− 1 dry weight (DW) of cotyledons, respectively] showed the presence of these two alkaline earth cations within this compartment. To our knowledge, this is the first time that Ca2+ and Mg2+ have been quantified in purified PSVs from Lupinus albus seeds. Considering the importance of these two alkaline earth cations inside PSVs, which represent 14.6% and 60.7% of the total seed Mg2+and Ca2+, respectively, globulin aggregation and disaggregation profiles were assayed using experimental conditions closer to those that are physiologically present (proportion of Ca2+ and Mg2+, and acidic pH). Based on: (1) the high in vivo abundance of Ca2+ and Mg2+ inside PSVs; and (2) globulin aggregation and disaggregation profiles, together with structural and physiological evidence already reported in the literature, an important physiological role for Ca2+ and Mg2+ in globulin packaging and mobilization inside PSVs is suggested.

Vaccinia virus protein C4 inhibits NF-κB activation and promotes virus virulence

Vaccinia virus (VACV) strain Western Reserve protein C4 has been characterized and its function and contribution to virus virulence assessed. Bioinformatic analysis showed that C4 is conserved in six orthopoxvirus species and shares 43 % amino acid identity with VACV protein C16, a known virulence factor. A recombinant VACV expressing a C-terminally tagged version of C4 showed that, like C16, this 37 kDa protein is expressed early during infection and localizes to both the cytoplasm and the nucleus. Functional assays using a firefly luciferase reporter plasmid under the control of a nuclear factor kappa B (NF-κB)-dependent promoter demonstrated that C4 inhibits NF-κB activation at, or downstream of, the inhibitor of kappa kinase (IKK) complex. Consistent with this, C4 inhibited interleukin-1β-induced translocation of p65 into the nucleus. A VACV lacking the C4L gene (vΔC4) showed no significant differences from wild-type virus in growth kinetics or spread in cell culture, but had reduced virulence in a murine intranasal model of infection. vΔC4-infected mice exhibited fewer symptoms, lost less weight and recovered 7 days earlier than animals infected with control viruses expressing C4. Furthermore, bronchoalveolar lavage fluid from vΔC4-infected mice had increased cell numbers at day 5 post-infection, which correlated with reduced lung virus titres from this time onward. C4 represents the ninth VACV protein to inhibit NF-κB activation and remarkably, in every case examined, loss of each protein individually caused an alteration in virus virulence, despite the presence of other NF-κB inhibitors.

Effects of elevated selenium on body condition, oxidative stress, and organ health in greater scaup wintering at Lake Ontario

AbstractElevated selenium (Se) concentrations have been detected in tissues of greater (Aythya marila) and lesser (A. affinis) scaup and it has been hypothesized that these Se concentrations may be affecting scaup health and reducing survival and, thus, negatively affecting scaup populations in North America. We evaluated the influence of hepatic Se concentrations on lipid and protein reserves, organ masses, tissue health, and oxidative stress of greater scaup wintering at western Lake Ontario during December–March, 2006–2007. Although we detected Se at elevated levels, all greater scaup with physical abnormalities (13 of 73 birds) had Se concentrations below the acute health problem threshold established for mallards (33 µg/g). Neither organ masses, protein reserves, nor measures of oxidative stress were influenced by hepatic Se concentrations, whereas lipid reserves varied positively with hepatic Se concentrations. Results suggest that hepatic Se concentrations at levels recorded in our study do not affect body condition or physical health of greater scaup. © 2012 The Wildlife Society.

Usefulness Of Nutritional Parameters Based On Creatinine Kinetic Model In Predicting Prognosis In Severe Aki Patients Requring Crrt

Malnutrition and protein catabolism have been known as important prognostic factors in AKI patient. The purpose of the present study was to evaluate the usefulness of application of creatinine (CKM) and urea kinetic modeling (UKM) based on the mass balance equation during CRRT treatment and their prognostic significance in severe AKI patients. Urea generation rate (UGR; mg/min) and Cr production rate (Pc; mg/day) were calculated by measuring urea and Cr production/removal balance from patients’ serum, the spent dialysate from CRRT and, if any, urine in 50 ICU patients with severe AKI receiving CRRT. Protein catabolic rate (nPCR; g/kg/d) and lean body mass (LBM; kg) were calculated according to the equations; PCR = [(9.35 x UGR)/BW]+0.17, LBM=(0.029xPc)+7.38. Pc was standardized with body weight and converted into Cr Index (CI; mg/kg/d). The impact of these CKM and UKM parameters on the prognosis in addition to conventional subjective global assessment (SGA) and other known traditional prognostic factors was analyzed. Overall survival of the subjects was 35.3%. Non-survivors showed not only significantly higher APACHE II and chronic comorbidities scores but also severely-malnourished state demonstrated by lower serum albumin, BMI, CI, and LBM. It was revealed that independent parameters associated with mortality were poor SGA (C; Hazard ratio 3.5), low CI (<11 mg/kg/d; HR 1.8), and high comorbidities score (≥3; HR 1.9). In conclusion, nutritional state and chronic comorbidities were major factors predicting the clinical outcome of severe AKI patients requiring CRRT. CKM was a simple and useful method in the assessment of nutritional state during CRRT treatment. Low creatinine production reflecting poor nutrition and protein reserve was associated with poor prognosis in severely ill ARF patients.

Proposal of non-invasive experimental model to induce scoliosis in rats

In the literature, there are several experimental models that induce scoliosis in rats; however, they make use of drugs or invasive interventions to generate a scoliotic curve. To design and apply a non-invasive immobilization model to induce scoliosis in rats. Four-week old male Wistar rats (85±3.3g) were divided into two groups: control (CG) and scoliosis (SG). The animals in the SG were immobilized by two vests (scapular and pelvic) made from polyvinyl chloride (PVC) and externally attached to each other by a retainer that regulated the scoliosis angle for twelve weeks with left convexity. After immobilization, the abdominal, intercostal, paravertebral, and pectoral muscles were collected for chemical and metabolic analyses. Radiographic reports were performed every 30 days over a 16-week period. The model was effective in the induction of scoliosis, even 30 days after immobilization, with a stable angle of 28±5º. The chemical and metabolic analyses showed a decrease (p<0.05) in the glycogenic reserves and in the relationship between DNA and total protein reserves of all the muscles analyzed in the scoliosis group, being lower (p<0.05) in the convex side. The values for the Homeostatic Model Assessment of Insulin Resistance indicated a resistance condition to insulin (p<0.05) in the scoliosis group (0.66±0.03), when compared to the control group (0.81±0.02). The scoliosis curvature remained stable 30 days after immobilization. The chemical and metabolic analyses suggest changes in muscular homeostasis during the induced scoliosis process.

Energy reserve modification in different age groups of Daphnia schoedleri (Anomopoda: Daphniidae) exposed to hexavalent chromium

Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms’ age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48h EC50 of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants.

Cytohistological Analysis and Mobilization of Reserves in Jatropha curcas L. Seed

ABSTRACTJatropha curcas L. is gaining interest as a promising energy crop whose oil is suitable for biodiesel production. The aim of our investigation was to study the type, localization, and dynamics of the reserves in J. curcas seed, which is considered the principal product of this species, utilized for biodiesel production. We investigated the cyto‐anatomical structure of the mature and germinating seeds and the storage substances localization in their different tissues. To this aim different techniques of light and electron microscopy were utilized (toluidine blue and periodic acid‐Schiff [PAS] staining and transmission electron microscope [TEM] observations). The results showed that, in mature seeds, protein vacuoles and oil bodies were present in the endosperm, embryo, and cotyledons. During germination the endosperm reserves were mobilized and the endosperm was characterized by vacuolated cells without protein and oil reserves; the oil and protein content also decreased in the cotyledons where, at this stage, starch grains appeared. Starch grains were also detected in the hypocotyl, where oil and protein reserves were not observed. Our studies confirmed that all portions of the mature seed (except the seed coat) contributed to store reserves and were a good source of oil, while immediately after germination the distribution of reserves was significantly modified and seeds were not a good source of the oil.

Protein–protein interaction inhibitors get into the groove

Drug developers are getting closer to tapping an unmined gold reserve of protein–protein interaction targets.

Variation in Body Composition and Digestive Organs of Tundra Swans during Migration at Long Point, Lake Erie, Ontario

Tundra Swans (Cygnus columbianus) spend a substantial portion of their annual cycle at migratory staging areas. Despite the potential importance of staging areas to conservation of Eastern Population (EP) Tundra Swans, few data are available to assess life-history strategies of the species during migration. During 1999 and 2000, 48 adult Tundra Swans were collected during peak periods of spring and autumn migration at Long Point, Ontario, Canada, to establish baselines on nutrient reserve levels and morphology of digestive organs. Results were compared to nutrient reserve data for EP Tundra Swans collected at a major wintering area in North Carolina, USA. Lipid reserve levels did not differ between sexes nor varied with body size, but lipid reserves were approximately two times greater in autumn than spring. Males had greater protein reserves than females, and protein reserves were similar during autumn and spring. Although digestive organs were predicted to be longer and heavier during autumn, no seasonal variation in digestive organs was detected. Lipid reserve levels of Tundra Swans at Long Point during spring were similar to those recorded for wintering birds in North Carolina, suggesting that lipid reserves catabolized from autumn through winter were not replenished prior to arriving at this initial spring staging area. The results highlight the importance of managing quality aquatic and terrestrial foraging habitats at staging areas for conservation EP Tundra Swans.