Influence of ferric chloride treated Leucaena leucocephala on metabolism of mimosine and 3-hydroxy 4(1H)-pyridone in growing rabbits

Twenty-five 42-days old New Zealand white rabbits were weaned and accustomed to a control ration in the 1st week and randomly allotted to five groups of five rabbits each. They were offered the control ration (G-1), and in other groups a portion of the control ration was replaced by Leucaena leaf meal (LLM) treated with 1.2% FeCl₃ or untreated i.e. 25% LLM (G-2), 50% LLM (G-3), 25% treated LLM (G-4), and 50% treated LLM (G-5) ration in pelleted form in a 8 weeks feeding cum metabolism trial. Average intake of mimosine and 3,4 DHP (dihydroxypyridone) was 304.6 and 129.5; 680.2 and 212.3; 279.6 and 147.6; and 643.1 and 239.9 mg day⁻¹ in G-2–G-5, respectively. Mimosine and 2,3 DHP were not detected in faeces. The faecal excretion of 3,4 DHP (as % intake of mimosine plus 3,4 DHP) in the rabbits of groups G-4 (43.5) and G-5 (40.6) was significantly (P<0.05) higher due to FeCl₃ treatment as compared to excretion in groups G-2 (30.1) and G-3 (21.4) fed untreated LLM. GOT (Glutamic oxalacetic transaminase), GPT (Glutamic-pyruvic transaminase), T₃ (tri-iodothyronine) and T₄ (thyroxine) levels in blood were within normal physiological range. Mimosine 3,4 DHP and 2,3 DHP, all were excreted through urine. The urinary excretion of 3,4 DHP was significantly lower (P<0.05) in G-4 and G-5. The overall excretion of DHP (2,3 and 3,4 DHP) was similar in all the groups. Severe hepatic and kidney damage occured in G-2 and G-3, while, in G-4 and G-5 very mild or no damage to liver and kidney was recorded. All tissues were devoid of mimosine, but DHP was present in liver, kidney and lungs. The maximum DHP in liver indicated as the primary site of DHP metabolism. In vitro incubation of LLM with caecal contents revealed 72.68–100% microbial degradation of mimosine. The overall DHP degradation ranged from 7.10% to 37.81% being the highest in G-3. The results indicated that, FeCl₃ treated leucaena could be used in commercial meat rabbit rations.     

Mimosine produced by the tree-legume Leucaena provides growth advantages to some Rhizobium strains that utilize it as a source of carbon and nitrogen

Growth of most Rhizobium strains is inhibited by mimosine, a toxin found in large quantities in the seeds, foliage and roots of plants of the genera Leucaena and Mimosa. Some Leucaena-nodulating strains of Rhizobium can degrade mimosine (Mid⁺) and are less inhibited by mimosine in the growth medium than the mimosine-nondegrading (Mid^-) strains. Ten Mid⁺ strains were identified that did not degrade 3-hydroxy-4-pyridone (HP), a toxic intermediate of mimosine degradation. However, mimosine was completely degraded by these strains and HP was not accumulated in the cells when these strains were grown in a medium containing mimosine as the sole source of carbon and nitrogen. The mimosine-degrading ability of rhizobia is not essential for nodulation of Leucaena species, but it provides growth advantages to Rhizobium strains that can utilize mimosine, and it suppresses the growth of other strains that are sensitive to this toxin.     

Influence of gradual adaptation of cattle to Leucaena leucocephala leaf meal on biodegradation of mimosine and 3- hydroxy-4(1H)-pyridone (3,4 DHP) in rumen,their levels in blood,fate and influence of absorbed DHP on thyroid hormones and liver enzymes

Three rumen fistulated Karan Fries crossbred (Holstein X Tharparkar) calves were fed increasing dry matter (DM) levels of 25%, 50%, 75% and 100% through leucaena leaf meal (LLM) starting at week 1, 2, 3 and 4, respectively. The mimosine, 3,4 DHP and 2,3 DHP levels were determined in strained rumen liquor (SRL) and serum at 0, 1, 2, 4, 8, 12 and 24 h postfeeding on days 1, 8, 15, 22, 29 and 42. LLM was incubated for 24 h with SRL in vitro on days 0, 7, 14, 21, 28 and 41 to study mimosine and dihydroxypyridone (DHP) biodegradation. On day 43, 1–1.5 l of rumen liquor was transferred to another set of three unadapted calves which were fed 50% LLM after transfer of inoculum. DM intake was 1.78%, 2.13%, 2.27%, 1.66%, 1.54% and 1.35% of live weight during the 1st through 5th week, respectively. Both in vitro and in vivo studies showed extensive degradation of mimosine to 3,4 DHP and 2,3 DHP from first day of LLM feeding. The overall in vitro DHP degradation was nil, 28.6%, 43.3% and 40.1% on day upto 15, 21, 28 and 42 of LLM feeding. No mimosine was found in serum on any day of sampling. The 3,4 DHP detected (56.94±31.65 μg ml⁻¹ serum) one hour post feeding on day 1 exhibited a decline from day 22 onwards. The serum also contained 2,3 DHP on days 8, 15, 22, 42. The faecal and urinary excretion of 3,4 DHP and 2,3 DHP as percent of mimosine intake declined from first week (76.3±2.8) to 4th week (42.1±4.1). The feeding of LLM resulted in reduced level of T₃ and T₄ within a week of LLM feeding. The level of T₃ improved to normal by 6th week while that of T₄ remained low. The SGOT and SGPT activities were within normal range. The gradual adaptation to LLM feeding caused Karan Fries calves to acquire DHP degrading ability to nontoxic compounds and this ability was transferred through transfer of rumen liquor from such calves to other unadapted calves at as early as 9th day of LLM feeding. The results revealed the possibility of two types of microbes degrading mimosine and 3,4 DHP to 2,3 DHP. One type of 2,3 DHP degrading microbes may be inhibited in the presence of 3,4 DHP whereas the other type may be active.     

Mimosine, a Toxin Present in Leguminous Trees (Leucaena spp.), Induces a Mimosine-Degrading Enzyme Activity in Some Rhizobium Strains

Thirty-seven Rhizobium isolates obtained from the nodules of leguminous trees (Leucaena spp.) were selected on the basis of their ability to catabolize mimosine, a toxin found in large quantities in the seeds, foliage, and roots of plants of the genera Leucaena and Mimosa. A new medium containing mimosine as the sole source of carbon and nitrogen was used for selection. The enzymes of the mimosine catabolic pathway were inducible and were present in the soluble fraction of the cell extract of induced cells. On the basis of a comparison of the growth rates of Rhizobium strains on general carbon and nitrogen sources versus mimosine, the toxin appears to be converted mostly to biomass and carbon dioxide. Most isolates able to grow on mimosine as a source of carbon and nitrogen are also able to utilize 3-hydroxy-4-pyridone, a toxic intermediate of mimosine degradation in other organisms.     

Effect of dietary copper on the growth performance,non-specific immunity and resistance to Aeromonas hydrophila of juvenile Chinese mitten crab,Eriocheir sinensis

An 8-week feeding trial was conducted to determine the dietary copper (Cu) on growth performance and immune responses of juvenile Chinese mitten crab Eriocheir sinensis. Six semi-purified diets with six copper levels (1.88, 11.85, 20.78, 40.34, 79.56 and 381.2 mg kg^?1 diet) of CuSO₄·5H₂O were fed to E. sinensis (0.45 ± 0.01 g). Each diet was fed to the crab in five replicates. The crab fed diets with 20.78 and 40.34 mg Cu kg^?1 diet had significantly greater weight gain and hemolymph oxyhemocyanin content than those fed diets with 1.88 and 381.2 mg Cu kg^?1 diet. Survival rates of crab were not significantly different between all treatment groups. The activities of copper–zinc superoxide dismutase (Cu–Zn SOD), phenoloxidase (PO), and total hemocyte count (THC) significantly increased when the supplementation of dietary copper reached 20.78–40.34 mg Cu kg^?1 diets. In the bacteria challenge experiment with Aeromonas hydrophila, survival rates significantly increased and reached a plateau when the dietary copper increased from 1.88 to 40.34 mg kg^?1, whereas significantly decreased when the dietary copper increased from 40.34 to 381.2 mg kg^?1. This study indicates that the level of dietary copper is important in regulating growth and immune response in crab.     

Dietary administration of the probiotic,Lactobacillus plantarum,enhanced the growth,innate immune responses,and disease resistance of the grouper Epinephelus coioides

The percent weight gain (PWG) and feed efficiency (FE) of Epinephelus coioides were calculated, and the lactobacilli and total microbiota in the posterior intestines, and non-specific immune parameters of grouper, and its susceptibility to Streptococcus sp. and an iridovirus were determined when the fish were fed diets containing Lactobacillus plantarum at 0 (control), 10⁶, 10⁸, or 10¹⁰ colony-forming units (cfu) kg^?1 for 4 weeks. Results showed that grouper fed a diet containing L. plantarum at the levels of 10⁶, 10⁸, and 10¹⁰ cfu kg^?1 had significantly increased PGW and FE especially at 10⁸ cfu kg^?1 group which were 404.6% and 1.26, respectively. L. plantarum significantly increased in the fish posterior intestines during the L. plantarum feeding period, but decreased rapidly from the intestine within 1 week after changing to the control diet (without L. plantarum). Fish fed a diet containing L. plantarum at 10⁶ and 10⁸ cfu kg^?1 had significantly higher survival rates than those fed the control diet after challenge with Streptococcus sp., as well as those fed 10⁸ cfu kg^?1 after challenge with an iridovirus, causing increases in the survival rates of 23.3%, 20.0%, and 36.7%, respectively, compared to the control group. The alternative complement activity (ACH₅₀) level of fish fed diets containing L. plantarum after 4 weeks was significantly higher than that of fish fed the control diet, and that of the 10⁸ cfu kg^?1 group was significantly higher than those of the 10⁶ and 10¹⁰ cfu kg^?1 groups, which increased by 83.4% compared to the control group. The lysozyme activity and glutathione peroxidase (GPx) activity of fish fed the L. plantarum-containing diets at 10⁸ and 10¹⁰ cfu kg^?1 significantly increased compared to those fed the 10⁶ cfu kg^?1 L. plantarum diet and control diet, and had increased by 76.3% and 136.6%, and 57.1% and 113.3%, respectively, compared to those fed the control diet. The phagocytic activity (PA), phagocytic index (PI), and respiratory bursts of head kidney leucocytes of fish fed 10⁶, 10⁸, and 10¹⁰ cfu kg^?1 L. plantarum diets were significantly higher than those of fish fed the control diet after 4 weeks of feeding, and increased 2.2-, 2.2-, and 2.3-fold; 1.8-, 1.8-, and 2.0-fold; and 1.4-, 1.4-, and 1.4-fold, respectively, compared to the control group. We therefore recommend dietary L. plantarum administration at 10⁸ cfu kg^?1 to promote growth and enhance immunity and resistance against Streptococcus sp. and an iridovirus of E. coioides.     

Lysine requirements of imported European pigs in the humid lowland tropics from 23 to 62 kg liveweight

The responses of 144 Large White × Landrace pigs (72 castrated males and 72 females; mean initial liveweight approximately 23 kg) to graded additions of L-lysine monohydrochloride to a basal diet containing yellow maize and groundnut meal and 180 g crude protein per kg were studied. Total dietary lysine levels ranged from 5–12 g kg^?1. All diets contained digestible energy of 15.44–16.02 MJ kg^?1 DM. The pigs were individually fed from 23 to 33, 47 or 62 kg liveweight. Growth performance, carcass characteristics, nitrogen retention and plasma urea concentration were employed as response criteria. Influence of sex on lysine requirements for optimum growth, nitrogen retention and efficiency of essential amino acids utilization measured by minimum plasma urea concentration was also investigated.Supplementing the basal diet with L-lysine monohydrochloride significantly (P < 0.001) improved growth performance. Castrated male pigs grew faster and responded better to dietary lysine supplementation than gilts. No apparent decline in lysine requirements for optimum growth performance was observed for the two sexes of pigs as they got older. Optimum growth performance in castrated males was obtained with 9, 8 and 8 g lysine kg^?1 diets for the liveweight ranges 23–33, 23–47 and 23–62 kg, respectively. Optimum growth performance of the gilts for all three liveweight ranges was obtained at an estimated dietary lysine concentration of 11 g kg^?1.Optimum lean deposition, carcass leanness and other carcass measurements were obtained at 8 g lysine kg^?1 diet. Carcass data were not analysed for influence of sex.Plasma urea concentration showed further evidence of a quicker and cheaper indirect index of dietary amino acid adequacy in pigs. Minimal plasma urea concentration was obtained at 7–8 g lysine kg^?1 diet for the three liveweight ranges investigated.In a humid tropical environment, such as Ibadan, the dietary lysine requirement of Large White × Landrace pigs of 23–62 kg is about 9 g lysine kg^?1 diet for optimum growth performance and carcass quality, but nitrogen metabolism and plasma urea data suggest a lower level of to 7–9 g lysine kg^?1 diet.     

Lack of Effect of Dietary Chromium Supplementation on Growth Performance and Serum Insulin, Glucose, and Lipoprotein Levels in Broilers Reared Under Heat Stress Condition

This study evaluated the effects of supplemental dietary chromium (Cr) on the performance, carcass traits, and some serum parameters of broilers under a heat stress (23.9 to 37 °C cycling) condition. A total of 150 1-day-old broiler chicks (Cobb 500) according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Treatments were supplemented with 0 (control), 600, and 1,200 μg kg^?1 Cr in the form of Cr chloride (CrCl₃) and Cr L-methionine from 1 to 49 days of age. Blood samples were collected from two birds in each replicate to determine serum parameters at 35 and 49 days of age. The body mass, feed intake, and conversion ratio were not influenced by dietary Cr (P?>?0.05). Dietary supplementation of Cr from either CrCl₃ or Cr L-methionine caused increased serum concentrations of Cr (P?<?0.05), but had no effect on serum insulin and glucose concentrations at both sampling times (P?>?0.05). Serum triglycerides, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were also not significantly affected (P?>?0.05) by dietary treatments, whereas total cholesterol concentration decreased in chicks fed Cr L-methionine compared to the control (P?<?0.05).     

Effects of adherent Lactobacillus cultures on growth,weight of organs and intestinal microflora and volatile fatty acids in broilers

A total of 180 1-day old Arbor Acres chicks was used to investigate the effects of a single L. acidophilus I 26 strain or a mixture of 12 Lactobacillus cultures on the production performance, weight of organs, and intestinal microflora and VFA of broilers. The chicks were assigned randomly into three groups with 60 chicks per treatment. The three dietary treatments were: (i) basal diet (acted as control); (ii) basal diet+1 g kg⁻¹ L. acidophilus I 26; and (iii) basal diet+1 g kg⁻¹ mixture of 12 Lactobacillus strains. The results showed that the addition of either a single L. acidophilus I 26 strain or a mixture of 12 Lactobacillus cultures to the basal diet increased significantly (P<0.05) the body weight and feed:gain ratio of broilers for 0–6 weeks. Supplementing the Lactobacillus cultures, singly or in a mixture, in the diet of broilers also decreased significantly (P<0.05) the numbers of coliforms in the cecum 10 and 20 days after feeding, increased significantly (P<0.05) the total VFA in the ileum and cecum, and lowered the cecal pH values. However, the addition of the Lactobacillus cultures in the diets did not increase significantly the lactobacilli population in the ileum and cecum of broilers, except for 30 days after feeding. There were also no significant differences in the populations of total anaerobes, total aerobes, Bifidobacteria and Streptococcus in the ileal and cecal contents of chickens fed with or without Lactobacillus cultures. No significant differences were found in the weight of the liver, spleen, bursa, gizzard, duodenum, jeju-ileum and total small intestine of broilers given the different dietary treatments.     

midD-encoded ‘rhizomimosinase’ from Rhizobium sp. strain TAL1145 is a C–N lyase that catabolizes L-mimosine into 3-hydroxy-4-pyridone, pyruvate and ammonia

Rhizobium sp. strain TAL1145 catabolizes mimosine, which is a toxic non-protein amino acid present in Leucaena leucocephala (leucaena). The objective of this investigation was to study the biochemical and catalytic properties of the enzyme encoded by midD, one of the TAL1145 genes involved in mimosine degradation. The midD-encoded enzyme, MidD, was expressed in Escherichia coli, purified and used for biochemical and catalytic studies using mimosine as the substrate. The reaction products in the enzyme assay were analyzed by HPLC and mass spectrometry. MidD has a molecular mass of ~45 kDa and its catalytic activity was found to be optimal at 37 °C and pH 8.5. The major product formed in the reaction had the same retention time as that of synthetic 3-hydroxy-4-pyridone (3H4P). It was confirmed to be 3H4P by MS/MS analysis of the HPLC-purified product. The K _m, V _max and K _cat of MidD were 1.27 × 10^?4 mol, 4.96 × 10^?5 mol s^?1 mg^?1, and 2,256.05 s^?1, respectively. Although MidD has sequence similarities with aminotransferases, it is not an aminotransferase because it does not require a keto acid as the co-substrate in the degradation reaction. It is a pyridoxal-5′-phosphate (PLP)-dependent enzyme and the addition of 50 μM hydroxylamine completely inhibited the reaction. However, the supplementation of the reaction with 0.1 μM PLP restored the catalytic activity of MidD in the reaction containing 50 μM hydroxylamine. The catalytic activity of MidD was found to be specific to mimosine, and the presence of its structural analogs including l-tyrosine, l-tryptophan and l-phenylalanine did not show any competitive inhibition. In addition to 3H4P, we also identified pyruvate and ammonia as other degradation products in equimolar quantities of the substrate used. The degradation of mimosine into a ring compound, 3H4P with the release of ammonia indicates that MidD of Rhizobium sp. strain TAL1145 is a C–N lyase.     

Immunomodulatory effect of sodium alginate enriched diet in kelp grouper Epinephelus brneus against Streptococcus iniae

The effect of diets containing sodium alginate at 0, 0.5, 1.0, and 2.0 g kg^?1 following challenge with Streptococcus iniae in kelp grouper Epinephelus bruneus were assessed with reference to survival rate and innate immune parameters such as alternative complement, lysozyme, natural haemagglutination, respiratory burst, superoxide dismutase, and phagocytic activities on week 1, 2, and 4. Fish fed with sodium alginate containing diet at 1.0 and 2.0 g kg^?1 after being challenged with S. iniae had higher survival rates of 75% and 60%, respectively than those fed with control diet (0 g kg^?1). With any enriched diet the percentage of macrophages significantly decreased from week 1–4, while the percentage of neutrophils and lymphocytes significantly increased. The alternate complement activity, natural haemagglutination, and phagocytic activities of infected fish fed with sodium alginate containing diet at 1.0 g kg^?1 on week 2 and 1.0 and 2.0 g kg^?1 diets on week 4 were significantly higher when compared to the control. The lysozyme, respiratory bursts, and superoxide dismutase activities of fish fed with enriched diets at 1.0 and 2.0 g kg^?1 were significantly increased on week 2 and 4. We therefore recommend that at 1.0 or 2.0 g kg^?1 dietary administration of sodium alginate can enhance innate immunity and disease resistance in kelp grouper against S. iniae.     

Influence of hyperosmolar basal media on hybridoma cell growth and antibody production

To investigate the influence of hyperosmolar basal media on hybridoma response, S3H5/γ2bA2 and DB9G8 hybridomas were cultivated in a batch mode using hyperosmolar basal media resulting from additional sodium chloride supplementation. The basal media used in this study were IMDM, DMEM, and RPMI 1640, all of which are widely used for hybridoma cell culture. In IMDM, two hybridomas showed different responses to hyperosmotic stress regarding specific MAb productivity (q _MAb), though they showed similar depression of cell growth in hyperosmolar media. Unlike S3H5/γ2bA2 hybridoma, the q _MAb of DB9G8 hybridoma was not enhanced significantly around 390 mOsm kg^?1. The variation of basal media influenced DB9G8 hybridoma response to hyperosmotic stress regarding q _MAb. In IMDM, the q _MAb of DB9G8 hybridoma was increased by more than 200% when the osmolality increased from 281 to 440 mOsm/kg. However, in RPMI 1640 and DMEM, similar amplitude of osmolality increase resulted in less than 100% increase in q _MAb. The variation of basal media also influenced the cell growth in hyperosmolar medium. Both hybridomas were more tolerant against hyperosmotic stress in DMEM than in IMDM, which was found to be due to the high osmolality of standard DMEM. The osmolalities of standard IMDM and DMEM used for inocula preparation were 281 and 316 mOsm kg^?1, respectively. Thus, when the cells were cultivated at 440 mOsm kg^?1, the cells in IMDM experienced higher osmotic shock than in DMEM. By using the inoculum prepared at 317 mOsm kg^?1 in IMDM, S3H5/γ2bA2 cell growth at 440 mOsm kg^?1 in IMDM was comparable to that in DMEM. Taken together, the results obtained from this study show that the selection of basal media is an important factor for MAb production by employing hyperosmotic stress.     

Isolation and biological activities of 3-hydroxy-4(1H)-pyridone

3-Hydroxy-4(4H)-pyridone (3,4-DHP), a degraded product of mimosine [β-[N-(3-hydroxy-4-oxypyridyl)]-α-aminopropionic acid], is known to cause goiters, loss of hair, and infertility in animals, but limits of 3,4-DHP on separation and purification have prevented efforts on investigating other toxicity and biological properties of 3,4-DHP. By this study, a novel and simple isolation of 3,4-DHP was developed either from Leucaena leaves using an ion-exchanged resin or mimosine degraded in high temperature (110°C, 6?h). The inhibition of mimosine on the growth of barnyardgrass was approximately fourfold higher (IC₅₀?=?0.04?mg?g^?1) than that of 3,4-DHP (IC₅₀?=?0.15?mg?g^?1). In general, the antifungal activity of mimosine is much stronger than that of 3,4-DHP, but it differs depending on the kind of fungi. The 1,1-diphyenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of 3,4-DHP, in contrast with the growth inhibitory activity, is about fourfold stronger [EC₅₀?=?2.4?mg?g^?1 gallic acid equivalent (GAE)] than that of mimosine [EC₅₀?=?10.3?mg?g^?1 GAE]. This study is the first to report on the herbicidal, antifungal, and antioxidant activities of 3,4-DHP.     

The effect of dietary inclusion of starch,sucrose and xylose on the utilization of dietary energy in sheep

A calorimetric experiment of 4 × 4 Latin square design was undertaken to study the effect of sugar-beet pulp (SBP), maize starch, sucrose and xylose on energy metabolism in sheep. The four diets comprised a diet (A) of dried grass, soya-bean meal and SBP (450, 50 and 500 g kg⁻¹ on dry matter (DM) basis) and corresponding diets in which 400 g kg⁻¹ of SBP was replaced by maize starch (B), sucrose (C) or xylose (D); all diets were offered at a level of 600 g DM day⁻¹. After the Latin square was completed, energy value of the basal diet of dried grass and soya-bean meal (900 and 100 g kg⁻¹ DM; 600 g day⁻¹) was determined in the same four sheep.Treatment differences in organic matter, gross energy, nitrogen (N) and neutral detergent fibre (NDF) digestibility were non-significant. Differences in N retention were not significant.Digestible energy (DE) contents (MJ kg⁻¹ DM) were 13.27, 13.22, 13.21 and 13.21 MJ kg⁻¹ for diets A, B, C and D, respectively. Energy loss in methane was higher (P < 0.05) for Diet A than for other diets. Metabolizable energy (ME) contents for the diets A-D were 11.25, 11.22, 11.32 and 11.40 MJ kg⁻¹ DM, respectively. Metabolizability (q) of the diets averaged 0.642 and was not significantly affected by the diet given. There was a trend for heat production to be higher in sheep given the sucrose-containing diet (C) than in those given other diets (6.34 versus 6.04 MJ day⁻¹) and as a result, energy retention was lower (0.38 versus 0.64 MJ day⁻¹), but the difference did not reach statistical difference. Efficiencies of utilization of ME for maintenance and fattening (k_mf) averaged 0.67 and were in good agreement with those predicted from equations of the Agricultural Research Council (1980) excepting the lower k_mf (0.63) for Diet C.The mean ME content of SBP calculated by difference was 13.05 MJ kg⁻¹ DM and the corresponding values for mixtures of SBP + starch, SBP + sucrose and SBP + xylose (600 and 400 g kg⁻¹ DM) were 12.98, 13.16 and 13.36 MJ kg⁻¹ DM, respectively.     

What can cell cycle and ultrastructure tell us about desiccation tolerance in Leucaena leucocephala germinating seeds?

Desiccation tolerance (DT) is the ability to tolerate dehydration to levels below 0.1 g(H₂O) g^?1(dry mass) and subsequent rehydration without lethal damage. Here, it is proposed that Leucaena leucocephala, a tree species, has potential to be model tolerant species in seed research. Using flow cytometry and transmission electron microscopy, cytological changes related to loss of DT in Leucaena primary roots were followed during germination. Leucaena seeds lost their DT at the end of germination and this coincided with an increase in cellular 4C DNA content. A negative correlation between the 8C DNA content and the capacity of germinating Leucaena seeds to tolerate desiccation was also observed. Apparently, the seeds of Leucaena underwent extra cycles of endoreduplication and accumulated a high content of DNA — an event not previously linked to DT. The ultrastructural damage imposed by drying overcame Leucaena primary root cell resilience and their ability to resume normal growth. Nuclear DNA content may be used as indicator of progress of germination and loss of DT in Leucaena.     

Zinc seed coating improves the growth,grain yield and grain biofortification of bread wheat

This study, comprising three independent experiments, was conducted to optimize the zinc (Zn) application through seed coating for improving the productivity and grain biofortification of wheat. Experiment 1 was conducted in petri plates, while experiment 2 was conducted in sand-filled pots to optimize the Zn seed coating using two sources (ZnSO₄, ZnCl₂) of Zn. In the first two experiments, seeds of two wheat cultivars Lasani-2008 and Faisalabad-2008 were coated with 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75 and 2.00 g Zn kg^?1 seed using ZnSO₄ and ZnCl₂ as Zn sources. The results of experiment I revealed that seed coating with 1.25 and 1.50 g Zn kg^?1 seed using both sources of Zn improved the seedling emergence. However, seed coated with 1.25 and 1.50 g Zn kg^?1 seed using ZnSO₄ was better regarding improvement in seedling growth and seedling dry weight. The results of the second experiment indicated that seed coated with 1.25 and 1.50 g Zn kg^?1 seed using ZnSO₄ improved the seedling emergence and seedling growth of tested wheat cultivars. However, seed coating beyond 1.5 g Zn kg^?1 seed using either Zn source suppressed the seedling emergence. Third experiment was carried out in glass house in soil-filled earthen pots. Seeds of both wheat cultivars were coated with pre-optimized treatments (1.25, 1.50 g Zn kg^?1 seed) using both Zn sources. Seed coating with all treatments of ZnSO₄ and seed coating with 1.25 g Zn kg^?1 seed using ZnCl₂ improved the seedling emergence and yield-related traits of wheat cultivars. Seed coating with 1.25 g Zn kg^?1 seed also improved the chlorophyll a and b contents. Maximum straw Zn contents, before and after anthesis, were recorded from seed coated with 1.5 g Zn kg^?1 seed using either Zn source. Increase in grain yield from seed coating followed the sequence 1.25 g Zn kg^?1 seed (ZnSO₄) >1.25 g Zn kg^?1 seed (ZnCl₂) >1.5 g Zn kg^?1 seed (ZnSO₄). However, increase in grain Zn contents from seed coated was 1.5 g Zn kg^?1 seed (ZnCl₂) >1.25 and 1.5 g Zn kg^?1 seed (ZnCl₂, ZnSO₄) >1.25 g Zn kg^?1 seed (ZnSO₄). Seed coating with Zn increased the grain Zn contents from 21 to 35 %, while 33–55 % improvement in grain yield was recorded. In conclusion, wheat seeds may be coated with 1.25 g Zn kg^?1 seed using either source of Zn for improving the grain yield and grain Zn biofortification.     

Dietary Supplementation of Zinc Nanoparticles and Its Influence on Biology,Physiology and Immune Responses of the Freshwater Prawn,Macrobrachium rosenbergii

The present study was conducted to assess the influence of dietary zinc nanoparticles (size 50 nm) on the growth, biochemical constituents, enzymatic antioxidant levels and the nonspecific immune response of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL). The concentrations of dietary supplement zinc nanoparticles (ZnNPs) were 0, 10, 20, 40, 60 and 80 mg kg^?1 with the basal diet, and the level of Zn in ZnNP-supplemented diets were 0.71, 10.61, 20.73, 40.73, 60.61 and 80.60 mg kg^?1, respectively. ZnNP-incorporated diets were fed to M. rosenbergii PL (initial body weight, 0.18?±?0.02 g) in a triplicate experimental setup for a period of 90 days. ZnNP supplemented feed fed PL up to 60 mg kg^?1 showed significantly (P?<?0.05) improved performance in survival, growth and activities of digestive enzymes (protease, amylase and lipase). The concentrations of biochemical constituents (total protein, total amino acid, total carbohydrate and total lipid), total haemocyte count and differential haemocyte count were elevated in 10–60 mg kg^?1 ZnNP supplemented feed fed PL. However, the PL fed with 80 mg ZnNPs kg^?1 showed negative results. Activities of enzymatic antioxidants [superoxide dismutase (SOD) and catalase (CAT)], metabolic enzymes [glutamate–oxaloacetate transaminase (GOT) and glutamate–pyruvate transaminase (GPT)] and the process of lipid peroxidation (LPO) in the hepatopancreas and muscle showed no significant alterations in 10–60 mg kg^?1 ZnNP supplemented feed fed PL. Whereas, 80 mg ZnNPs kg^?1 supplemented feed fed PL showed significant elevations in SOD, CAT, LPO, GOT and GPT. Therefore, 80 mg ZnNPs kg^?1 was found to be toxic to M. rosenbergii PL. Thus, the study suggests that up to 60 mg ZnNPs kg^?1 can be supplemented for regulating survival, growth and immunity of M. rosenbergii.     

Growth and maintenance respiration in leaves of northern red oak seedlings and mature trees after 3 years of ozone exposure

A two-component model of growth and maintenance respiration is used to study the response of northern red oak (Quercus rubra L.) seedlings and 32-year-old trees to sub-ambient (10 μmol h; cumulative dose based on 7 h daily mean), ambient (43 μmol h), and twice-ambient (85 μmolh) ozone. The relative growth rates (RGR) of leaves sampled from seedlings and trees were similar across treatments, as were specific leaf respiration rates (SRR). Growth coefficients estimated from the SRR versus RGR relationship averaged 25-3 mol CO2 kg^?1 leaf dry mass produced for seedlings and 21-5 mol kg^?1 for trees. Maintenance coefficients ranged from 0-89 to 1-07 mol CO₂ kg^?1 leaf dry mass d^?1 for seedlings and from 0-64 to 0-84 mol kg-1 d^?1 for trees. Neither coefficient was affected by ozone. Leaves sampled throughout the growing season also showed little response of respiration to ozone. This occurred despite a 30% reduction in net photosynthesis for trees grown at twice-ambient ozone. These results suggest that growth and maintenance respiration in young northern red oak leaves are not affected by ozone and that in older leaves injury can occur without a parallel increase in so-called ‘maintenance’ respiration.     

Effects of Zinc Glycinate on Productive and Reproductive Performance,Zinc Concentration and Antioxidant Status in Broiler Breeders

An experiment was conducted to investigate the effects of zinc glycinate (Zn-Gly) supplementation as an alternative for zinc sulphate (ZnSO₄) on productive and reproductive performance, zinc (Zn) concentration and antioxidant status in broiler breeders. Six hundred 39-week-old Lingnan Yellow broiler breeders were randomly assigned to 6 groups consisting of 4 replicates with 25 birds each. Breeders were fed a basal diet (control group, 24 mg Zn/kg diet), basal diet supplemented with 80 mg Zn/kg diet from ZnSO₄ or basal diet supplemented with 20, 40, 60 and 80 mg Zn/kg diet from Zn-Gly. The experiment lasted for 8 weeks after a 4-week pre-test with the basal diet, respectively. Results showed that Zn supplementation, regardless of sources, improved (P?<?0.05) the feed conversion ratio (kilogram of feed/kilogram of egg) and decreased broken egg rate, and elevated (P?<?0.05) the qualified chick rate. Compared with the ZnSO₄ group, the 80 mg Zn/kg Zn-Gly group significantly increased (P?<?0.05) average egg weight, fertility, hatchability and qualified chick rate, whereas it decreased (P?<?0.05) broken egg rate. The Zn concentrations in liver and muscle were significantly higher (P?<?0.05) in 80 mg Zn/kg Zn-Gly group than that in ZnSO₄ group. Compared with ZnSO₄ group, 80 mg Zn/kg Zn-Gly group significantly elevated (P?<?0.05) the mRNA abundances of metallothionein (MT) and copper-zinc superoxide (Cu-Zn SOD), as well as the Cu-Zn SOD activity and MT concentration in liver. Moreover, the 80 mg Zn/kg Zn-Gly group had higher (P?<?0.05) serum T-SOD and Cu-Zn SOD activities than that in the ZnSO₄ group. This study indicated that supplementation of Zn in basal diet improved productive and reproductive performance, Zn concentration and antioxidant status in broiler breeders, and the 80 mg Zn/kg from Zn-Gly was the optimum choice for broiler breeders compared with other levels of Zn from Zn-Gly and 80 mg/kg Zn from ZnSO₄.     

Effect of prebiotic mannan oligosaccharide on hematological and blood serum biochemical parameters of cultured juvenile great sturgeon (Huso huso Linnaeus, 1754)

The nutritional effects of prebiotic mannan oligosaccharide were evaluated using hematological and blood serum biochemical parameters in cultured juvenile great sturgeon (Huso huso). Fish were offered formulated diets containing two levels of prebiotic mannan oligosaccharide (2 and 4 g kg^?1); a basal diet with no prebiotics was used as control. The experiment lasted for 46 days. Blood samples were collected from the caudal veins of 18 apparently healthy fish (average weight 217.77 ± 29.8 g) at the end of the trial. No significant differences were found in the serum enzyme activity levels between treatments (P > 0.05). However, adding mannan oligosaccharide as a supplement to the basal diet resulted in significant differences in lymphocytes and eosinophils between the control and the 2 g kg^?1 treatment (P < 0.05) as well as a significant difference in the creatinine factor in the 2 g kg^?1 mannan oligosaccharide treatment (P < 0.05). The results show that it would be advantageous to add 2 g kg^?1 mannan oligosaccharide to the diets of juvenile great beluga sturgeon (Huso huso).