Milligram Of Dry Weight Research Articles

Amidated pleurocidin peptide encapsulated in biodegradable poly(lactide-co-glycolide) microparticles sustains its antibacterial activity against Photobacterium damselae subsp. piscicida in cobia

Photobacterium damselae subsp. piscicida (PDP), the causative agent of fish pasteurellosis, has become a serious threat leading to high mortalities in cage-cultured juveniles of cobia (Rachycentron canadum). However, overuse of conventional antibiotics to control the infection raises the emergence of resistant bacteria as well as the presence of residual drugs in animals and the environment. Further efforts are therefore needed to look for new and effective antibacterial agents, such as antimicrobial peptides (AMPs), for use on the fish farm to replace conventional antibiotics before commercial vaccines against PDP are available. In the present study, the fish-derived AMP, pleurocidin (PLE), was used as an anti-PDP agent. After C-terminal amidation, the resulting amidated PLE peptide, PLE(am), was further encapsulated with the poly (lactide-co-glycolide) (PLG) polymer to generate PLG-PLE(am) microparticles that would sustain release of antibacterial PLE(am) and elicit effective protection against PDP in cobia. PLG-PLE(am) microparticles, 4.25–5.39 μm in diameter, contained 14.69–18.47 μg of entrapped PLE(am) per milligram of dry weight of microparticles and showed 81%~84% entrapment efficiency. The amount of released PLE(am) from PLG microparticles gradually increased over a 28-day triphasic controlled-release period and the released PLE(am) still retained its antibacterial activity. Peritoneal injection with PLG-PLE(am) microparticles further protected all cobia from a lethal peritoneal infection of 2 × 103 CFU PDP (MML-3) and allowed cobia to survive relatively longer (14 days post infection). In conclusion, the sustained release of antibacterial PLE(am) peptide from PLG-PLE(am) microparticles can preserve the antibacterial activity to result in effective protection in cobia. Our study provides notable evidence to indicate the feasibility of using PLG-PLE(am) microparticles as an antibacterial agent against PDP in cobia.

Differences in the chemical composition of Enterococcus faecalis biofilm under conditions of starvation and alkalinity

ABSTACTThis study aimed to investigate the dynamic changes that occur in the chemical composition of an Enterococcus faecalis (E. faecalis) biofilm under conditions of starvation and in an alkaline environment and to explore the function of chemical composition changes in the resistance of the E. faecalis biofilm to an extreme environment. This study established an in vitro E. faecalis biofilm model under starvation and in an alkaline environment. During the formation of the biofilm, the pH value and nutritional condition of the culture medium were changed, and the changes in chemical composition were observed using biochemical measures. The results showed that, when the pH value of the culture medium was 11, the percentage of water-insoluble polysaccharides in the biofilm was significantly lower than under other conditions. In addition, the percentage of water-soluble polysaccharides in culture medium with pH values of 9 and 11 gradually decreased. The level of the water-soluble polysaccharides in each milligram of dry weight of biofilm at pH 11 increased compared to that under other conditions. The results from this study indicate that the chemical composition of E. faecalis biofilm changed in extreme environments. These changes served as a defensive mechanism for E. faecalis against environmental pressures.

Occurrence of Two Pathways for Malate Oxidation in Bacteroids Isolated from Sesbania rostrata Stem Nodules during C2H2 Reduction

Malate oxidation supported C(2)H(2) reduction by bacteroids isolated from Sesbania rostrata stem nodules. Optimal activity reached 7.5 nanomoles per minute per milligram of dry weight and was in the same order of magnitude as that observed with succinate but always required a lower O(2) tension. Malate dehydrogenase (EC 1.1.1.37), purified 66-fold from bacteroids, actively oxidized malate (K(m) = 0.19 millimolar). Malic enzyme (EC 1.1.1.39) from Sesbania bacteroids had a lower affinity for malate (K(m) = 2.32 millimolar). Both enzymes exclusively required NAD(+) as cofactor and required an alkaline pH for optimal activity. 2-Oxoglutarate and oxalate, inhibiting malate dehydrogenase and malic enzyme, respectively, were used to specifically block each malate oxidation pathway in bacteroids. The predominance of malate dehydrogenase activity to support bacteroid N(2) fixation was demonstrated. The inhibition of O(2) consumption by 2-oxoglutarate confirmed the importance of the malate dehydrogenase pathway in malate oxidation. It is proposed that the utilization of malate, with regard to O(2), is important in a general strategy of this legume to maintain N(2) fixation under O(2) limited conditions.

Myocardial preservation related to magnesium content of hyperkalemic cardioplegic solutions at 8 °C

This study investigates whether the addition of magnesium to a hyperkalemic cardioplegic solution containing 0.1 mM ionized calcium improves myocardial preservation, and whether there is an optimal magnesium concentration in this solution. Isolated perfused rat hearts were arrested for two hours by this cardioplegic solution, which was fully oxygenated and infused at 8 °C every 15 minutes to simulate clinical conditions. The cardioplegic solution contained either 0, 2, 4, 8, 16, or 32 mM magnesium. At end-arrest, the myocardial creatine phosphate concentration (nanomoles per milligram of dry weight) was 20.7 ± 2.1, 22.9 ± 1.7, 24.8 ± 2.0, 31.3 ± 1.4, 33.1 ± 1.8, and 31.6 ± 0.8, respectively, in hearts given cardioplegic solution containing these magnesium concentrations. Thus, the concentration of creatine phosphate was significantly higher at end-arrest when the cardioplegic solution contained 8, 16, or 32 mM than 0 or 2 mM magnesium ( p < 0.002) or 4 mM magnesium ( p < 0.02), and highest with 16 mM magnesium. Also, creatine phosphate was more sensitive to the magnesium concentration of the cardioplegic solution than was end-arrest adenosine triphosphate levels, which did not differ among the experimental groups. Aortic flow, expressed as a percentage of prearrest aortic flow, was 60.3 ± 5.0, 70.2 ± 5.5, 71.6 ± 4.4, 71.8 ± 4.8, 81.0 ± 5.0, and 71.8 ±5.3, respectively. The addition of magnesium to the cardioplegic solution improved recovery of aortic flow ( p < 0.05, 16 mM versus 0 mM magnesium). We conclude from these data that with deep myocardial hypothermia and at an ionized calcium concentration of 0.1 mM, the addition of magnesium, over a broad concentration range, improved preservation of myocardial creatine phosphate and, at a concentration of 16 mM, improved aortic flow. The optimal magnesium concentration in the cardioplegic solution was 16 mM.

Effect of Azospirillum brasilense inoculation on root morphology and respiration in tomato seedlings

The level of Azospirillum brasilense strain Cd colonization in the rhizosphere of some vegetables was 104–105 colony-forming units (CFU) per root of one plant in 2-week-old plants inoculated with 5 × 108Azospirillum cells. Significant increases in root length (35%) and in top (90%) and root (50%) dry weight and total leaf area (90%) were observed in 18-day-old inoculated tomato plants compared with non-inoculated controls. An inoculum concentration of 1 × 108 to 5 × 108 CFU/ml stimulated the appearance of root hairs. Large numbers of bacteria (1 × 109 CFU/ml) caused asymmetrical growth of the root tip. In a petri dish system, Azospirillum (1 × 108 CFU/ml) increased root dry weight (150%), protein content (20%), respiration rate per root (70%) and the specific activity of malate dehydrogenase (45%–65%) over non-inoculated controls. The specific respiration rate, expressed as micromol of O2 per minute per milligram of dry weight of roots, was significantly lower in inoculated roots, suggesting that less energy was spent for accumulation of more dry material.

Diurnal Changes in Volume and Specific Tissue Weight of Crassulacean Acid Metabolism Plants

The diurnal variations in volume and in specific weight were determined for green stems and leaves of Crassulacen acid metabolism (CAM) plants. Volume changes were measured by a water displacement method. Diurnal variations occurred in the volume of green CAM tissues. Their volume increased early in the light period reaching a maximum about mid-day, then the volume decreased to a minimum near midnight. The maximum volume increase each day was about 2.7% of the total volume. Control leaves of C(3) and C(4) plants exhibited reverse diurnal volume changes of 0.2 to 0.4%. The hypothesis is presented and supported that green CAM tissues should exhibit a diurnal increase in volume due to the increase of internal gas pressure from CO(2) and O(2) when their stomata are closed. Conversely, the volume should decrease when the gas pressure is decreased.The second hypothesis presented and supported was that the specific weight (milligrams of dry weight per square centimeter of green surface area) of green CAM tissues should increase at night due to the net fixation of CO(2). Green CAM tissues increased their specific weight at night in contrast to control C(3) and C(4) leaves which decreased their specific weight at night. With Kalanchoë daigremontiana leaves, the calculated increase in specific leaf weight at night based on estimates of carbohydrate available for net CO(2) fixation was near 6% and the measured increase in specific leaf weight was 6%.Diurnal measurements of CAM tissue water content were neither coincident nor reciprocal with their diurnal patterns of either volume or specific weight changes.

The effects of ozone and nitrogen fertilizer on tall fescue, ladino clover, and a fescue–clover mixture. I. Growth, regrowth, and forage production

The effects of chronic ozone (O3) and (or) nitrogen fertilizer on growth, regrowth, and forage production of ladino clover (Trifolium repens L. cv. Tillman) and tall fescue (Festuca arundinaceae Schreb. cv. Kentucky 31) grown in pots separately and together in open-top chambers in the field were studied from April 27 to October 19, 1979. Mean 7 h per day (0930 to 1630 EDT) O3 concentrations for this period were as follows: charcoal-filtered air chambers, 0.03 ppm; nonfiltered air chambers (NF-1), 0.05 ppm; nonfiltered air chambers with O3 added for 7 h per day (NF-2), 0.08 ppm; and ambient air, 0.05 ppm. Ozone reduced regrowth (milligrams of dry weight per plant per week) and total forage production of clover and the fescue–clover mixture. The magnitude of the reductions of clover growth and forage production corresponded in general to the O3 levels. Growth of fescue was not significantly modified by O3 treatments. Nitrogen fertilization stimulated the growth of fescue but had little impact on the growth of clover. Nitrogen fertilization did not change the response of either species to O3.

Ration alimentaire et bilan énergétique individuel dans une population de montagne de Lacerta vivipara

The diet of Lacerta vivipara was estimated in the laboratory by determining the relationship between fecal production and food intake. Transposed to free-living individuals, this relationship between the daily consumption C in milligrams of dry weight and the total fresh weight of lizards in grams becomes C = 20.4 W0,85. By knowing the number of days during which lizards can eat, the assimilation rate, the weight increase, the mean weight of the tail, the rate of autotomy, and the weight of a brood, the individual energy budget has been established for each sex according to age. The proportion of the assimilated biomass used for growth reaches a peak in young lizards, then decreases regularly to a negligible degree in older animals. The energy used for reproduction is low at first in primiparous females but becomes three times as great in older females.[Traduit par le journal]

Bioassay of cholecystokinin in the duodenal mucosa.

Cholecystokinin (CCK)-like activities in the duodenal mucosa were measured by bioassay in patients with duodenal ulcer, cholelithiasis and some other gastrointestinal diseases as well as in healthy normal subjects. The mean CCK-like activity of the duodenal mucosa in patients with duodenal ulcer and cholelithiasis was 0.405 Ivy dog units per milligram and 0.376 Ivy dog units per milligram of dry weight of the duodenal mucosa (IDU/mg d.w.), respectively. Both these figures are significantly higher than 0.180 IDU/mg d.w. in normal subjects (p less than 0.005, p less than 0.005, respectively). It can be speculated that the CCK-level of the duodenal mucosa in patients with cholelithiasis may be regulated by a feedback mechanism and CCK in patients with duodenal ulcer may act physiologically for the cure of duodenal ulcer.

Levels of acetyl coenzyme A, reduced and oxidized coenzyme A, and coenzyme A in disulfide linkage to protein in dormant and germinated spores and growing and sporulating cells of Bacillus megaterium

Dormant spores of Bacillus megaterium were found to contain approximately 850 pmol of coenzyme A (CoA) per milligram of dry weight. Of this total, less than 1.5% was acetyl-CoA, 25% was CoA-disulfide, 43% was in disulfide linkage to protein, and the remainder was the free thiol. Dormand spores of Bacillus cereus and Clostridium bifermentans contained 700 and 600 pmol of CoA per milligram of dry weight, respectively; in both species approximately 45% of the CoA 45% of the CoA was in disulfide linkage to protein. During germination of spores of all three species, greater than 75% of the CoA-protein disulfides were cleaved. In B. megaterium, cleavage of these disulfides during spore germination did not require exogenous metabolites and occurred at about the same time as the initiation of germination. Much of the CoA was converted to acetyl-CoA at this time. Dormant spores also contained reduced nicotinamide adenine dinucleotide-dependent CoA-disulfide reductase at levels higher than those in other stages of growth. The level of total CoA in the growing cells was two- to three-fold higher than in spores. This level remained constant throughout growth and sporulation, but less than 2% of the total cellular CoA was in disulfide linkage to protein until late in sporulation. The CoA-protein disulfides accumulated exclusively within the developing spore at about the time when dipicolinic acid was accumulated.

Zur Bestimmung von Blei in Mikroproben von biologischem Material mittels flammenloser Atomabsorptions-Spektrophotometrie

Summary A method is described for micro determination of lead in biological samples. Following wet digestion a micro solvent extraction of ammonium pyrrolidine dithiocarbamate — Pb chelate into methyl isobutyl ketone was carried out prior to flameless atomic absorption determination. Traces of lead in small biological samples (few milligrams of dry weight) down to the limit of 10 ppb/dry weight can be determined with an accuracy of about ± 5% without using standard addition methods.

Changes in cortisol binding to soluble receptor proteins in rat liver and thymus during development and ageing

Changes in labeled cortisol binding to soluble cytoplasmic proteins of rat liver and thymus during development and ageing of animals have been observed. The relationship of age and cortisol binding to a fraction of soluble liver proteins precipitated at 50% saturation with ammonium sulfate displayed two maxima: The first one on the seventh day of postnatal life and the second one at 2.5 months of age. Binding of hormone to macromolecules of the same fraction prepared from older animals was less efficient. Almost the same picture has been obtained when total bound activity to macromolecular cytosol fraction was expressed per milligram of dry weight of liver. Binding of labeled cortisol to total cytosol macromolecules of liver and thymus was most efficient in 3-month-old animals and decreased after that, which is of interest in view of totally opposite effects of glucocorticoids upon various biosynthetic processes of these organs.

Food Energy Budget for the Yellow-Poplar Weevil, Odontopus Calceatus (Say)

An energy budget was developed for Odontopus calceatus feeding on fresh Liriodendron tulipifera leaves. Calorific content was determined for both weevil biomass and weevil feces. Food consumption was estimated to be 97% of dry body weight per day with an egestion rate of 45%. Assimilation was 50% of both dry matter and of energy per day. Respiration of O. calceatus was 0.88 cal per milligram of dry weight per day at 27%C. Based on these data and information on field population biomass for a Liriodendron forest (1965 in East Tennessee), canopy consumption was estimated at 1.9% (17.7 Kcal/m2). See full-text article at JSTOR

Comparative studies on blood-stream and culture forms of Trypanosoma lewisi— II. Biochemical composition

1.1. The non-protein nitrogen and RNA content per milligram dry weight and per trypanosome of both the blood-stream and culture forms is higher at 4 days than at any other time during cultivation or infection.2.2. The percentage protein per milligram of dry weight of the blood-stream forms increases during the course of the infection, but it decreases during the growth of the culture forms.3.3. The 4-day blood-stream form has a lower protein content per trypanosome than 7- and 12-day blood-stream or 4-, 6- and 10-day culture forms.4.4. Variation in the dry weight of trypanosomes occur both with the blood-stream and culture forms.5.5. Variations in neural lipid, phospholipid and cholesterol content per trypanosome appear to exist in both forms.6.6. The amounts of RNA and protein, but not DNA, per trypanosome for the culture forms of Trypanosoma lewisi and Trypanosoma cruzi are similar.

Effect of Growth Rate on the Synthesis of Penicillin by Penicillium chrysogenum in Batch and Chemostat Cultures

The kinetics of penicillin production by Penicillium chrysogenum Wis 54-1255 in a glucose-limited chemostat and in batch cultures are reported. The specific production rate of penicillin, q pen (units per milligram of dry weight per hour) was independent of specific growth rate over the range 0.014 to 0.086 hr -1 . Growth was stopped by restricting the glucose supply to the “maintenance ration,” that is, the glucose requirement of the organism at zero growth rate with all other nutrients in excess. Under such conditions, the organism dry weight remained constant, but the q pen fell approximately linearly to zero at a rate inversely related to the previous growth rate. Glucose supplied in excess of the maintenance ration inhibited the decay of q pen . At a critical growth rate between 0.009 and 0.014 hr -1 , the decay was completely inhibited. Quantitative expressions for the q pen of growing and nongrowing cultures were derived and used to predict the steady-state concentrations of penicillin accumulating in one- and two-stage continuous processes. A rational explanation of the kinetics of penicillin accumulation in batch cultures is given, relating the rate of penicillin synthesis to growth rate. It is concluded that an important role of corn steep liquor (CSL), a heterogeneous carbon and nitrogen source commonly used in penicillin production media, is the provision of substrates which allow a high concentration of mold to be reached before the growth rate falls below the critical value. CSL had no significant effect on q pen .

Effect of Growth Rate on the Synthesis of Penicillin by Penicillium chrysogenum in Batch and Chemostat Cultures

The kinetics of penicillin production by Penicillium chrysogenum Wis 54-1255 in a glucose-limited chemostat and in batch cultures are reported. The specific production rate of penicillin, q(pen) (units per milligram of dry weight per hour) was independent of specific growth rate over the range 0.014 to 0.086 hr. Growth was stopped by restricting the glucose supply to the "maintenance ration," that is, the glucose requirement of the organism at zero growth rate with all other nutrients in excess. Under such conditions, the organism dry weight remained constant, but the q(pen) fell approximately linearly to zero at a rate inversely related to the previous growth rate. Glucose supplied in excess of the maintenance ration inhibited the decay of q(pen). At a critical growth rate between 0.009 and 0.014 hr, the decay was completely inhibited. Quantitative expressions for the q(pen) of growing and nongrowing cultures were derived and used to predict the steady-state concentrations of penicillin accumulating in one- and two-stage continuous processes. A rational explanation of the kinetics of penicillin accumulation in batch cultures is given, relating the rate of penicillin synthesis to growth rate. It is concluded that an important role of corn steep liquor (CSL), a heterogeneous carbon and nitrogen source commonly used in penicillin production media, is the provision of substrates which allow a high concentration of mold to be reached before the growth rate falls below the critical value. CSL had no significant effect on q(pen).

Placental oxygen consumption in vitro: I. Baseline studies

Barcroft-Warburg respirometric observations of fresh in vitro placental tissue have been reported as part of a correlative study of the effects of various clinical features upon placental metabolism and their relationship to fetal development and survival.Data are presented to illustrate the rates of decay of placental activity under various conditions of storage, indicating the urgent need to study the material in the freshest possible state. Similarly, degradation occurs so rapidly during manometric studies that consecutive observations for the purpose of determining the effects of adding substrates are interdicted.The reduction of the oxygen concentration of the gas phase produces a corresponding, although nonlinear, reduction in oxygen uptake.Normal term placentas consume 2.02 ± 0.03 μl of oxygen per milligram of dry weight per hour. A linear decline is seen from early pregnancy to term.Numerous clinical factors are correlated with placental oxygen consumption, but, except in rare instances, the data are not sufficiently numerous to allow for statistical verification of observed trends.

Metabolism of Bovine Semen. IX. Glutamic-Oxaloacetic and Glutamic-Pyruvic Transaminase Activities

Summary Assays on 63 samples of bovine semen gave an average of 623±48 units of glutamic-oxaloacetic transaminase (GO-T) and 15±1 units of glutamic-pyruvic transaminase (GP-T) per milliliter of seminal plasma. Statistically significant correlations of .849 for GO-T and .409 for GP-T were observed between seminal plasma transaminase activity and numbers of spermatozoa per milliliter of semen. When spermatozoa were freed of seminal plasma and the GO-T and GP-T activities in seminal plasma and cells compared, more activity was associated with the cells than with seminal plasma. With seminal plasma-free cells, GO-T per milligram of dry weight was similar to that reported in several bovine tissues, but lower than the activity in heart, liver, and skeletal muscle.

RESPIRATORY TRENDS IN PERIANTH SEGMENTS OF MAGNOLIA GRANDIFLORA

STUDIES OF floral respiration have in general been carried out to indicate the trend in respiration rate over a period of days or weeks. James and Beevers (1950) observed in the immature tissue of Arum spadix a gradual decrease in respiration followed by a sharp rise during the period of maturation. Siegelman et al. (1958) found a similar pattern in disks of rose petals during development. The trend in respiration appeared to be similar to the climacteric curve of several fruits as described by Biale (1958). However, in work done on excised mature flowers or floral parts of camellias by Bonner and Honda (1950), of roses by Siegelman (1952), and of Cattleya mossiae Hook. by Sheehan (1954), there was a continual drop in respiration with no increase comparable to a climacteric. In this study the relationship of metabolic activity, as indicated by oxygen consumption, to stages in floral development and to cytological changes is reported for the perianth segments of Magnolia grandiflora . MATERIALS AND METHODS.-Six trees in the Los Angeles area served as source for flowers. The blooming season in this region is May, June, and July. The work reported here was done during June and July of 1956. The flowers were selected at random and labeled on the first morning of bloom. This day was designated as the first day of bloom and all measurements were referred to this time. To determine the approximate age of buds in relation to the first day of bloom, a large group of buds from a given area on one tree was tagged and their length was recorded by daily measurements. Buds for respiration determinations were taken from the same region on the tree and their age, in relation to the first day of bloom, was estimated by comparison with those carried through to bloom. Flowers were collected and their age recorded in days and hours, with midnight prior to the first morning of bloom designated as the zero point. A lapse of from '70 to 90 min. occurred between picking and the beginning of a test in Warburg vessels; the data were recorded as of the time of picking. Respiration rate was based on oxygen uptake, measured by the Warburg manometric method and recorded as Qo2 (microliters of oxygen per milligram of dry weight per hour). Disks about 9 mm. in diameter were cut from the inner perianth segments with a cork borer. Between 15 and 18 of these disks, whose total weight varied between 390 and 410 mg., were used in each flask; in older flowers, due to desiccation, more disks had to be

Oxygen requirements of Strongyloides papillosus infective larvae

1. 1. The free-living, infective larvae of Strongyloides papillosus were found to have a high oxygen consumption. The larvae consumed an average of 28.6 microliters of oxygen per hour per milligram of dry weight ( Q o 2 ). 2. 2. The larvae could not survive in the absence of oxygen. They are therefore classified as “strict aerobes”. 3. 3. The infective larvae were “cyanide sensitive.” Respiration was completely inhibited, resulting in death, by 1 × 10 −3 M HCN. 4. 4. Cytochrome oxidase was detected colorimetrically in larval homogenates. Coupled with the action of HCN, these results indicated the presence of a cytochrome system in the larvae. 5. 5. The comparative results of the Q o 2 of S. papillosus larvae and other parasitic nematode larvae indicated an inverse relationship between Q o 2 and longevity of these forms.