Effects of mannan level and β-mannanase supplementation on growth performance,apparent total tract digestibility and blood metabolites of growing pigs

The exogenous enzymes are less consistent in their effects as their beneficial effects depend upon the types and level non-starch polysaccharides (NSP) present in the diets. Therefore, exogenous enzymes should be selected on the basis of types and amount of the NSP in the pig diets. The objectives of the present experiments were to investigate the effects of dietary level of mannan and β-mannanase supplementation on growth performance, apparent total tract digestibility (ATTD) of energy and nutrients, and blood metabolites of growing pigs. In Exp. 1, 96 barrows were randomly allotted to four treatments on the basis of BW. There were four replicates in each treatment with six pigs per replicate. The dietary treatments were a corn–soybean meal (SBM)-based control diet and three other diets consisted of the control diet supplemented with 400, 800 or 1600 U of β-mannanase/kg diet. The final BW, average daily gain (ADG) and blood glucose increased (linear, P<0.05) with increasing concentrations of dietary β-mannanase. The ATTD of dry matter (DM), gross energy (GE) and β-mannan was higher (linear, P<0.05) with increase in dietary β-mannanase concentrations. In Exp. 2, 288 barrows were allotted to six treatments in a 2×3 factorial arrangement of mannan level (high v. low) and addition of β-mannanase (0, 400 or 800 U/kg diet). There were four replicates in each treatment with 12 pigs/replicate. Pigs were fed corn–SBM-based low-mannan diet (6.1 g/kg) or high-mannan (25.2 g/kg) diet in which corn and SBM were partially replaced with 50 g/kg diet palm kernel meal. All diets were fed in meal form for 42 days. Pigs fed diets supplemented with β-mannanase had greater (P<0.05) final BW, ADG, feed to gain (F : G), the ATTD of DM, GE, and β-mannan and blood glucose concentration compared with pigs fed diets without β-mannanase. In addition, the final BW, ADG, F : G and the ATTD of GE and β-mannan were reduced (P<0.05) in low mannan level. The dietary level of mannan and the β-mannanase supplementation had no effects (P>0.05) on the concentrations of blood total cholesterol, triacylglycerides and blood urea nitrogen. These results indicate that supplementation of β-mannanase to low- or high-mannan diets have potential to improve the performance of growing pigs. In addition, palm kernel meal may partially replace corn and SBM without reducing pig performance if β-mannanase is added to diet.     

Effects of the supplementation of distillers’ grape residues on ruminal degradability,whole tract digestibility and nitrogen metabolism in sheep

ABSTRACT

Five ruminally and duodenally cannulated Kazakh male lambs (30 ± 2.75 kg) maintained singly in a metabolic cage were used in a 5 × 5 Latin square experiment to investigate the effect of supplementing a ration with five different levels of distillers’ grape residue (DGR) on ruminal degradability, whole tract digestibility and nitrogen (N) metabolism of growing lambs. The rations were isoenergetic and isonitrogenous and contained 0, 3.85, 7.70, 11.55 and 15.41% DGR (DM basis). Each experimental period lasted for 18 d: 10 d for adaptation to the dietary treatment and 8 d for faecal, urinary, ruminal and duodenal digesta sample collections. The outflow rate of ruminal digesta increased (p = 0.032) linearly with the increased level of dietary neutral detergent fibre content, caused by the supplementation of DGR. As a result, the effective degradability of dry matter and crude protein decreased significantly with the treatments. Although the dietary intake of N, duodenal flow of total N, and the endogenous N at the duodenum were not affected by experimental treatments, N fractions in the digesta were altered. Ruminal microbial N decreased (p < 0.01) linearly; in contrast, ruminal un-degradable protein increased linearly (p < 0.01) in response to the increased addition of DGR. Although there was no significant difference in faecal N among treatments, N retention was increased linearly (p = 0.014), owing to the remarkable reduction (p = 0.016) of urinary N excretion with an increasing level of DGR. The results indicate that the DGR has some potential benefits of increasing the supply of bypass protein and of improving the utilisation efficiency of N for sheep. Therefore, the supplementation of DGR in ruminant feeding is recommended at levels not exceeding 10% of the diet.     

Effect of nutrient deficiency on accumulation and relative molecular weight of poly-β-hydroxybutyric acid by methylotrophic bacterium,Pseudomonas 135

Summary Pseudomonas 135, a facultative methylotroph, was cultivated on methanol as a sole carbon and energy source for the accumulation of poly--hydroxybutyric acid (PHB). The cells grew fairly well on minimal synthetic medium containing 0.5% (v/v) of methanol at pH 7.0 and 30° C. The maximum specific growth rate was determined to be 0.26–0.28 h^–1 with a growth yield of 0.38 in the optimized growth medium. For stimulation of PHB accumulation in the cells, deficiency of nutrients such as NH _inf4 ^sup+ , Mg²⁺ and PO _inf4 ^sup3– was crucial even though cell growth was significantly suppressed. The PHB content of a 40-h culture was determined to be 37% of the total cell mass in NH _inf4 ^sup+ -limited medium, 42.5% on Mg²⁺-deficient medium, and 34.5% on PO _inf4 ^sup3– -deficient medium. The maximum content of PHB in the cells could reach 55% in NH _inf4 ^sup+ -limited fed-batch culture. The average relative molecular eight determined by gel permeation chromatography was 3.7 × 10⁵ in NH _inf4 ^sup+ -limited culture, 2.5 × 10⁵ in Mg²⁺-deficientmedium, and 3.1 × 10⁵ in PO _inf4 ^sup3– -deficient medium. Polydispersity determined in each culture was relatively high (about 10–11). The solid PHB had a melting temperature of 173° C. Correspondence to: J. M. Lebeault     

Influence of submerged macrophytes,temperature, and nutrient loading on the development of redox potential around the sediment–water interface in lakes

Redox potential is a significant factor in aquatic systems to regulate the availability of nutrients and some metals. To assess the driving variables regulating redox potential, background parameters (dissolved oxygen, pH, temperature, chlorophyll-a, soluble reactive and total phosphorus content of water, coverage and height of submerged macrophytes) and redox potential profiles around the sediment–water interface (SWI) were measured in simulated shallow lake ecosystems. There were two nutrient regimes (enriched and non-enriched) and three temperature scenarios (unheated; +3.5°C; +5°C) installed in the experimental setups, which were constructed to study the effects of global climate change. Temperature did not have any detectable effect on redox potentials, and we presume that nutrient addition had only indirect positive effects through triggering phytoplankton dominance which causes macrophyte absence. When submerged macrophytes were present in high density (80–100% coverage), redox potentials at the SWI varied between 60–215 mV and the mean redox potential was 133 ± 34 mV (mean ± 1 SD). In contrast to this, when phytoplankton dominance was coupled to low macrophyte density (0–20% coverage), the range of redox potentials at the SWI was 160–290 mV and the mean redox potential was 218 ± 34 mV. The results revealed the primary importance of submersed macrophytes; macrophyte coverage determined alone the redox potential of the sediment–water interface by 81%. This study suggests that possible positive effects of macrophytes on redox potential can be suppressed by their negative effects in case of 80–100% coverage and total inhabitation of the water column.     

Influence of nutrient and water stress on Norway spruce production in south Sweden — the role of air pollutants

A field experiment primarily designed for simulating the indirect effects of air pollutants for a 25-year-old Norway spruce stand in SW Sweden is presented (The Skogaby project). Treatment include irrigation; artificial drought; ammonium sulphate addition; nitrogen-free-fertilization and irrigation with liquid fertilizers including a complete set of nutrients. The experiment has a randomized block design with four replicates per treatment. Growth response on an areal basis of basal area, height and dry mass of stems, branches and needles after up to four years of treatment are presented. Dry mass is estimated using allometric equations based on destructive samplings of trees.The stand suffered from temporary water stress during all four years investigated despite 970– 1160 mm of annual precipitation. Irrigation resulted in improved above-ground dry mass production (stem, bark, branches, needles, litter fall) by 20% during the first 3 years of treatment, whereas 2 years of drought treatment followed by 1 year of recovery led to 10% reduced dry mass growth. During year 2 of recovery, however, basal area growth was only about half of that of the control.Nitrogen, markedly, was a growth limiting nutrient, although the stand got approx. 20 kg N ha^-1 y^-1 from deposition. Ammonium sulphate addition (100 kg N ha^-1 y^-1) resulted in 31% improved dry mass production whereas irrigation with liquid fertilization (100 kg N ha^-1 y^-1) including all important nutrient elements led to 57% increased dry mass growth after 3 years of treatment. Basal area growth of the latter treatment gradually increased and during year 4 of treatment was 123% larger than the control. Nitrogen-free-fertilization resulted in a small improvement of dry mass production (+10%).After 3 years of treatment, the amount of needles had increased markedly for both treatments including irrigation, whereas drought treated trees instead had decreased their needle amount vs control. The increase in needle amount occurred as a result of both larger formation of needles and higher preservence of old needles, the opposite relations being found for the drought treated trees. At the same point larger needle formation in combination with a higher shedding of older needles was found for trees treated with ammonium sulphate and nitrogen-free-fertilizer.It is concluded that there is no stage of N saturation in the Skogaby site as there is no leaching of N from the control plots and N fertilization results in both increased tree growth and N uptake.     

Influence of ambient and enhanced ultraviolet-B radiation on the plant growth and physiological properties in two contrasting populations of Hippophae rhamnoides

Two contrasting sea buckthorn (Hippophae rhamnoides L.) populations from low and high altitude regions were employed to investigate the effects of prevailing and enhanced ultraviolet-B (UV-B) radiation on plant growth and physiological properties under a UV-B-enhanced/exclusion system. The experimental design included three UV-B regimes, including excluded (-UVB), near-ambient (NA) and enhanced UV-B (+UVB) radiation. Compared with the control (-UVB), NA caused the formation of smaller but thicker plant leaves in both sea buckthorn populations, paralleled with significant increments of carotenoids and UV-absorbing compounds as well as improved water economy. NA also induced more biomass partition from shoot to root, but CO(2) assimilation rate (A), photosynthetic area and biomass accumulation were unaffected. The low-altitude population seemed sensitive to +UVB, as indicated by the decreases in total biomass, A and ascorbic acid content (Asa, an antioxidant) compared with NA. However, little +UVB effect occurred on the high-altitude population, and we suggest that the higher tolerance of this population could be associated with its specific morphological and physiological characteristics, such as small but thick leaves and high-level of Asa content, as well as its greater physiological modification in response to NA, e.g., increases in protective compounds (carotenoids and UV-absorbing compounds) and improvement in water economy, in comparison to the low-altitude population, which form an effective adaptation strategy to enhanced UV-B stress.     

Specific activity of α-l-fucosidase in sera with phenotypes of either low,intermediate, or high total enzyme activity and in a fucosidosis serum

The quantity of -l-fucosidase activity in human serum is determined by heredity. An individual may inherit either low, intermediate, or high serum enzyme activity. An enzyme-linked immunoabsorbent assay has been developed that can detect 0.3 ng of -l-fucosidase protein. Enzyme protein in serum of 102 individuals ranged from 20 to 835 ng/ml. The group included individuals with low, intermediate, and high enzyme activity. The specific activity of -l-fucosidase within this group was statistically the same (mean±SD=11,002±1051 U/mg). Thus, individuals with low and intermediate enzyme activity in serum had lower amounts of enzyme protein with the same specific activity as in individuals with high enzyme activity. Fucosidosis is a rare inherited disease in which -l-fucosidase activity in tissues and body fluids is low or absent. The concentrations of enzyme protein in sera of a fucosidosis patient and parents were 76, 565, and 604 ng/ml, respectively, and the specific activities of enzyme were 1316, 8938, and 8858 U/mg, respectively. Thus, the fucosidosis serum probably contained a structurally altered enzyme with reduced catalytic activity. The somewhat low specific activities in the parents suggested that their sera contained both structurally altered and normal protein.This research was supported by National Institutes of Health Grants AM 32161 and GM 31425.     

Effects of pig genotype (Iberian v. Landrace × Large White) on nutrient digestibility, relative organ weight and small intestine structure at two stages of growth

Although the effects of pig genotype on total-tract apparent digestibility (TTAD) have been widely reported in the literature, there is controversial information on the digestive capacity of indigenous breeds compared with lean-type pigs. The strategy of this study was to test the effects of pig genotype and crude protein (CP) supply on performance, digestive utilization of nutrients, relative organ weight and morphometric analysis of the small intestine. Thirty-eight Iberian (IB) and Landrace × Large White (LD) pigs were used. Three pigs per genotype were slaughtered at approximately 15 kg BW. The remaining pigs were fed one of two diets differing in CP content (13% or 17% as fed) using a pair-fed procedure. Feeding level was restricted at 0.8 × ad libitum of IB pigs. Nutrient digestibility and nitrogen (N) balance trials were performed at 30 and 80 kg BW. Four pigs per dietary treatment and genotype were slaughtered at approximately 50 and 115 kg BW. The gastrointestinal tract and the rest of the visceral organs were weighed and samples of the small intestine were taken to carry out histological and histometrical studies. Daily gain and gain-to-feed ratio were higher in LD than in IB pigs during the fattening and growing-fattening periods (P < 0.01). N TTAD was significantly higher for LD pigs at 30 kg BW (P < 0.05), whereas at 80 kg BW we observed greater values for digestibility of organic matter and energy in IB pigs (averaging 1.5%, P < 0.01). Both N retention (NR) and efficiency of NR were increased in LD pigs at 30 and 80 kg BW (30% as mean value). The proportional weight of the small intestine was greater in LD than in IB pigs at 50 and 115 kg BW. Histometry showed that IB presented a lower muscle layer thickness than LD pigs in ileum, irrespective of the BW (P < 0.05). In contrast, LD pigs showed approximately 10% higher ileal villi length and villi-to-crypt ratio than IB pigs at 115 kg BW. CP supply affected to a larger extent the small intestinal micro-anatomical structure of LD pigs at 50 kg BW. In conclusion, our results suggests that although the higher growth rate, NR and efficiency of NR observed in LD pigs might be associated with presumably more efficient structural aspects of the small intestine, the main differences between the two genotypes should be attributed to a larger extent to protein and energy utilization in tissues with consequences for the overall efficiency of energy use.     

Effects of γ-rays on Poly-L-glutamic acid and Poly-D,L-glutamic acid in the solid state

Summary Poly-L-glutamic acid and poly-D,L-glutamic acid, as models of proteins, were irradiated with⁶⁰Co--radiation in air and under vacuo to examine whether or not the changes caused by the exposure to ionizing radiation depend on the conformations of polypeptides.It was found that theG- values (yield of main-chain scissions per 100 eV of energy absorbed) of both polypeptides are approximately equal for the irradiation in air, while under vacuo theG- value of poly-D,L-glutamic acid is larger than that of poly-L-glutamic acid. This observation for irradiation under vacuo was ascribed to the stabilizing effect of intramolecular hydrogen bond bridges in poly-L-glutamic acid. It was also found that the-helical structure of poly-L-glutamic acid is destroyed by the exposure to ionizing radiation.     

Environmental Influence on Planktonic Cladocerans and Copepods in the Floodplain of the Upper River Paraná, Brazil

The abundance of microcrustacean species recorded in plankton samples from the littoral and pelagic zones of the Upper Paran River, State of Mato Grosso do Sul, Brazil, was evaluated in relation to abiotic and biotic environmental factors. The cladocerans Bosminopsis deitersi and Bosmina hagmann i were most abundant. The presence or absence of aquatic macrophytes also influenced abundance and species composition. The true zooplankton species were most abundant at the pelagic stations, while species of Chydoridae and Macrothricidae contributed markedly to microcrustacean abundance and species richness at littoral stations. Species abundance was also strongly affected by water level variation. Microcrustaceans, mainly bosminids, were most abundant during low water. During high water, bosminids decreased in abundance while most other species increased. The higher variation of the environmental factors during high water probably explains the shift in abundance patterns. Changes in water level increased mixing of littoral and pelagic microcrustaceans between sampling stations.     

In vitro–in vivo study on the effects of plant compounds on rumen fermentation,microbial abundances and methane emissions in goats

Two in vitro and one in vivo experiments were conducted to investigate the effects of a selection of plant compounds on rumen fermentation, microbial concentration and methane emissions in goats. Treatments were: control (no additive), carvacrol (CAR), cinnamaldehyde (CIN), eugenol (EUG), propyl propane thiosulfinate (PTS), propyl propane thiosulfonate (PTSO), diallyl disulfide (DDS), a mixture (40 : 60) of PTS and PTSO (PTS+PTSO), and bromochloromethane (BCM) as positive control with proven antimethanogenic effectiveness. Four doses (40, 80, 160 and 320 µl/l) of the different compounds were incubated in vitro for 24 h in diluted rumen fluid from goats using two diets differing in starch and protein source within the concentrate (Experiment 1).The total gas production was linearly decreased (P<0.012) by all compounds, with the exception of EUG and PTS+PTSO (P⩾0.366). Total volatile fatty-acid (VFA) concentration decreased (P⩽0.018) only with PTS, PTSO and CAR, whereas the acetate:propionate ratio decreased (P⩽0.002) with PTS, PTSO and BCM, and a tendency (P=0.064) was observed for DDS. On the basis of results from Experiment 1, two doses of PTS, CAR, CIN, BCM (160 and 320 µl/l), PTSO (40 and 160 µl/l) and DDS (80 and 320 µl/l) were further tested in vitro for 72 h (Experiment 2). The gas production kinetics were affected (P⩽0.045) by all compounds, and digested NDF (DNDF) after 72 h of incubation was only linearly decreased (P⩽0.004) by CAR and PTS. The addition of all compounds linearly decreased (P⩽0.009) methane production, although the greatest reductions were observed for PTS (up to 96%), DDS (62%) and BCM (95%). No diet–dose interaction was observed. To further test the results obtained in vitro, two groups of 16 adult non-pregnant goats were used to study in vivo the effect of adding PTS (50, 100 and 200 mg/l rumen content per day) and BCM (50, 100 and 160 mg/l rumen content per day) during the 9 days on methane emissions (Experiment 3). The addition of PTS and BCM resulted in linear reductions (33% and 64%, respectively, P⩽0.002) of methane production per unit of dry matter intake, which were lower than the maximum inhibition observed in vitro (87% and 96%, respectively). We conclude that applying the same doses in vivo as in vitro resulted in a proportional lower extent of methane decrease, and that PTS at 200 mg/l rumen content per day has the potential to reduce methane emissions in goats. Whether the reduction in methane emission observed in vivo persists over longer periods of treatments and improves feed conversion efficiency requires further research.     

Effect of 17β-estradiol on cells stained for FSHβ and/or LHβ in the dog pituitary gland

Summary The effect of long-term treatment (52 weeks) with high doses of 17-estradiol (1.28 mg/kg/week intramuscularly) on gonadotrophs was studied in the pituitary gland of the beagle bitch. For immunochemical staining the immunoperoxidase technique and antisera to the specific beta () subunits of FSH and LH were employed. For control purposes antisera to the following hormones were also used: bovine TSH, canine GH, canine PRL and porcine ACTH¹. In the pars distalis and pars tuberalis of control bitches, in addition to the cells which react solely with antisera to either LH or FSH, most cells were reactive to both antisera. The cells stained for FSH were less numerous than those shown to contain LH. TSH, PRL, GH and ACTH/MSH were localized in distinctly different cell types in the pars distalis of all control animals. In the treated bitches, almost complete regression of cells classically identified as gonadotrophs and stained for LH was observed. On the other hand, using the antiserum to FSH, selective immunochemical staining was localized in cells fitting the morphological characteristics of TSH cells. All these cells were also stained for TSH. However, a few cells were also shown to react solely with the antiserum to TSH. These cells, which seem to contain both TSH and FSH, were further clearly differentiated from PRL, GH and ACTH/MSH cells on the basis of their cytological features, intraglandular distribution and by immunochemical double staining. These observations support the concept that the one cell-one hormone theory may not necessarily apply to the glycoprotein hormones of the dog pituitary gland.Abbreviations of Hormones cited in this Paper ACTH Adrenocorticotropin - FSH Follicle Stimulating Hormone - GH Growth Hormone - LH Luteinizing Hormone - MSH Melanocyte Stimulating Hormone - PRL Prolactin - TSH Thyrotropin The authors are grateful to Mrs. K. Oertel for carrying out the experimental work on animals, to Mrs. B. Schilk and Miss U. Tüshaus for their excellent technical assistance, and to Dr. P. Günzel for his advice and encouragement     

Effects of increasing the intake of dietary β-glucans by exchanging wheat for barley on nutrient digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid concentration and manure ammonia emissions in finishing pigs

An experiment (complete randomised design) was conducted to investigate the linear and quadratic effects of barley β-glucan inclusion level on total tract nutrient apparent digestibility, nitrogen excretion, intestinal microflora, volatile fatty acid (VFA) profile and manure ammonia emissions in pigs. Twenty-four boars (66 kg) were assigned to one of four treatments: (T1) 0 g/kg barley (control diet) (5.6 g/kg β-glucan), (T2) 222 g/kg barley (12.1 g/kg β-glucan), (T3) 444 g/kg barley (18.9 g/kg β-glucan) and (T4) 666 g/kg barley (25 g/kg β-glucan). Barley was substituted for wheat in the diet. The diets were formulated to contain similar concentrations of digestible energy and digestible lysine. There was a linear decrease (P < 0.001) in the total tract apparent digestibility of dry matter, organic matter, gross energy and neutral-detergent fibre with increasing β-glucan concentration. Faecal nitrogen excretion was affected by dietary β-glucan concentration (quadratic P < 0.05). There was a linear decrease in Enterobacteria concentrations (P < 0.05) with increasing dietary β-glucan concentration. Increasing dietary barley levels caused a linear decrease in colonic (P < 0.01) and caecal pH (P < 0.001). Total caecal VFA and propionic acid were affected by dietary β-glucan concentration (quadratic, P < 0.05). There was a linear decrease in the proportion of acetic acid (P < 0.001), isobutyric acid (P < 0.01) and isovaleric acid (P < 0.05) with increasing levels of dietary barley in both the caecum and colon. There was a linear increase in the proportion of propionic acid (P < 0.001) and butyric acid (P < 0.05) with increasing barley in the colon. In conclusion, high level of dietary β-glucan (25 g/kg) is required to reduce offensive odour forming branched-chain VFAs; however, diet digestibility is compromised at such levels.     

Effects of high irradiances on photosynthesis,growth and crassulacean acid metabolism in the epiphyteKalanchoö uniflora

Summary Kalancho? uniflora was grown in the glasshouse with and without shading. Chlorophyll content, area/FW ratio and specific leaf area were higher in leaves of shaded as compared to unshaded plants. Light saturation curves and continuous gas exchange measurements showed that the apparent quantum yield and the light-saturated photosynthetic rate were higher in shaded plants. Shaded plants had lower “mesophyll resistances” than unshaded plants, indicating that the different photosynthetic capacities reflected different contents of ribulose biphosphate carboxylase-oxygenase. Highlight treatment of plants grown in the shade resulted in a decreased photosynthetic efficiency, showing that these plants were sensitive to photoinhibition. However, dry matter production was higher in unshaded than in shaded plants. Obviously the difference in irradiance between the two growth regimes did more than offset the differences in photosynthetic efficiency. Applying additional nutrients did not alter the effects of high PFDs. The results are discussed in respect to photosynthetic performence and plant distribution in the epiphytic habitat.     

Influence of homologous recombinational repair on cell survival and chromosomal aberration induction during the cell cycle in γ-irradiated CHO cells

The repair of DNA double-strand breaks (DSBs) by homologous recombinational repair (HRR) underlies the high radioresistance and low mutability observed in S-phase mammalian cells. To evaluate the contributions of HRR and non-homologous end-joining (NHEJ) to overall DSB repair capacity throughout the cell cycle after γ-irradiation, we compared HRR-deficient RAD51D-knockout 51D1 to CgRAD51D-complemented 51D1 (51D1.3) CHO cells for survival and chromosomal aberrations (CAs). Asynchronous cultures were irradiated with 150 or 300 cGy and separated by cell size using centrifugal elutriation. Cell survival of each synchronous fraction (～20 fractions total from early G1 to late G2/M) was measured by colony formation. 51D1.3 cells were most resistant in S, while 51D1 cells were most resistant in early G1 (with survival and chromosome-type CA levels similar to 51D1.3) and became progressively more sensitive throughout S and G2. Both cell lines experienced significantly reduced survival from late S into G2. Metaphases were collected from every third elutriation fraction at the first post-irradiation mitosis and scored for CAs. 51D1 cells irradiated in S and G2 had ～2-fold higher chromatid-type CAs and a remarkable ～25-fold higher level of complex chromatid-type exchanges compared to 51D1.3 cells. Complex exchanges in 51D1.3 cells were only observed in G2. These results show an essential role for HRR in preventing gross chromosomal rearrangements in proliferating cells and, with our previous report of reduced survival of G2-phase NHEJ-deficient prkdc CHO cells [Hinz et al., DNA Repair 4, 782–792, 2005], imply reduced activity/efficiency of both HRR and NHEJ as cells transition from S to G2.     

Agonist of the adenosine A3 receptor,IB-MECA,and inhibitor of cyclooxygenase-2, meloxicam,given alone or in a combination early after total body irradiation enhance survival of γ-irradiated mice

There exists a requirement for drugs which would be useful in therapy of an acute radiation damage of a mammalian organism. The aim of the study was to evaluate survival parameters in mice exposed to a lethal γ-ray dose of 8.5 Gy and treated with single doses of an adenosine A₃ receptor agonist, IB-MECA, or a cyclooxygenase-2 (COX-2) inhibitor, meloxicam, administered alone or in a combination early after irradiation, i.e., 0.5 and 1 h post-irradiation, respectively. The assessed parameters were the mean survival time (MST) and the cumulative percentage 30-day survival (CPS). Administrations of single intraperitoneal doses of either IB-MECA 0.5 h post-irradiation or meloxicam 1 h post-irradiation resulted in statistically significant increases of MST in comparison with the control irradiated mice. Combined administration of IB-MECA and meloxicam was found to be the only treatment statistically enhancing the parameter of CPS and to lead to the most expressive increase in MST of the experimental mice. The findings add new knowledge on the action of an adenosine A₃ receptor agonist and a COX-2 inhibitor in an irradiated mammalian organism and suggest the potential of both the investigated drugs in the treatment of the acute radiation damage.     

A new form of renin in normal human plasma: “big renin” is a mixture of inactive prorenin and the new active high molecular weight renin

A new form of active renin was separated from inactive prorenin in normal human plasma by a new affinity chromatographic method on a column of Cibacron Blue F3GA-agarose. This active renin has a molecular weight of 54,000, considerably higher than the hitherto recognized active renin of 40,000 dalton in human plasma. The molecular weight of inactive prorenin was 56,000±2,000. Active renin produced from the inactive prorenin by trypsin or pepsin digestion or by acid treatment in $\text{in vitro}$ experiments showed a molecular weight of 54,000±2,000. Active renin with a molecular weight of 40,000 was not found in 6 samples of untreated plasma of normal human subjects nor was it formed by treatment with trypsin, pepsin, or acid pH. It is concluded that a large form of active renin (54,000 dalton) exists in normal human plasma which is distinct from a smaller form and that the activatable “big renin” is a mixture of this active renin and totally inactive prorenin. This explains the absence of molecular weight change during the activation of “big renin”.