Lactoperoxidase (LPO) is a glycosylated antimicrobial protein present in milk with a molecular mass of 78 kDa. LPO is included in many biological processes and is well-known to have biocidal actions, acting as an active antibiotic and antiviral agent. The wide spectrum biocidal activity of LPO is mediated via a definite inhibitory system named lactoperoxidase system which plays a potent role in the innate immune response. With the current advancement in nanotechnology, nanoformulations can be developed for stabilizing and potentiating the activity of LPO for several applications. In the research described in this Research Communication, fresh LPO purified from bovine mammary gland secretions was used for nanoparticle synthesis using a simple thermal process at different pH and temperatures. The round-shaped nanoparticles (average size 229 nm) were successfully synthesized at pH 7.0 and a temperature of 75°C. These nanoparticles were tested against four different bacterial species namely S. flexineri, P. aeruginosa, S. aureus, and E. coli. The prepared nanoparticles exhibited strong inhibition of the growth against all four bacterial species as stated by their MIC and ZOI values. These results may help in increasing the efficiency of lactoperoxidase system and will assist in identifying novel avenues to enhance the stability and antimicrobial function of LPO in drug discovery and industrial processes.

Galerucella placida Baly feeds on the rice-field weed Polygonum orientale L. (Polygonaceae) in India and Bangladesh during autumn and winter seasons. The insect is widely available during the winter season when the temperature fluctuates between 9 and 24 °C. Hence, it is of considerable interest to study how the adults cope with the stress resulting due to temperature fluctuations. Consequently, we analysed the levels of H2O2, antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD), peroxidases (POD), guaiacol peroxidase (GPX), pyrogallol peroxidases (PPX), ascorbate peroxidases (APOX) and glutathione-S-transferases (GST)] and malondialdehyde (MDA) at 9, 12, 15, 18, 21 and 24 °C in adult G. placida. H2O2 was highest at 24 °C followed by 9 °C and lowest at 18 and 21°C. CAT and SOD were highest at 9 °C followed by 24 °C, while POD was highest at 24 °C followed by 9 °C. CAT and POD were lowest at 18 and 21 °C, but SOD was the lowest at 21 °C. APOX were three-fold higher at 9 °C compared to 12 °C, which was the lowest at 18 and 21 °C, implying that APOX had strong detoxification function at 9 °C. GST was highest and lowest at 9 and 21 °C, respectively. MDA was highest at 9 °C and lowest at 18 and 21 °C, which did not differ significantly at 15 and 24 °C, suggesting that lower and higher temperature stress was accompanied by lipid peroxidation. This finding provides useful information for mass rearing of G. placida for predicting population dynamics and understanding the potential for G. placida as biocontrol agent under varying environmental conditions.

Introduction. Wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most important disease of banana worldwide, causing severe yield losses in commercial and local consumption cultivars. Chemical control is currently the most used method to manage the Fusarium wilt of banana, although it is toxic, expensive and dangerous. Therefore, control through genetic improvement is widely encouraged. Hence, breeding was carried out to develop banana hybrids with putative resistance. Materials and methods. Hybridization of identified resistant diploids with commercial triploids and tetraploids was carried out; it resulted in development of 22 hybrids with improved agronomic characters. In a second step, screening of these hybrids for resistance to Foc race 1 was attempted using the double cup method of challenge inoculation with the pathogen in the roots of the hybrids at optimum level. Host responses of the susceptible and resistant hybrids were examined under greenhouse conditions through biochemical and isozyme analysis. Results. Six hybrids among the 22 hybrids with improved agronomic characters were selected based on their yield and they were evaluated for resistance. Three of them were resistant to Foc and the others were susceptible. The resistance mechanism involving the relation of enzymes such as peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine lyase (PAL), and biochemicals such as phenols, proline and lignin showed relatively higher activity in resistant hybrids and parents than susceptible ones. Isozyme analysis of PO and PPO carried out using selected resistant and susceptible hybrids revealed the induction of specific isoforms in the resistant hybrids upon challenge inoculation. Conclusion. Three hybrids were identified as potential hybrids with good yield and resistance to Foc race 1.

Aphids are, arguably, the single most damaging group of agricultural insect pests throughout the world. Plant tolerance, which is a plant response to an insect pest, is viewed as an excellent management strategy. Developing testable hypotheses based on genome-wide and more focused methods will help in understanding the molecular underpinnings of plant tolerance to aphid herbivory. As a first step in this process, we undertook transcript profiling with Affymetrix GeneChip Barley Genome arrays using RNA extracted from tissues of tolerant and susceptible genotypes collected at three hours, three days and six days after Diuraphis noxia introduction. Acquired data were compared to identify changes unique to the tolerant barley at each harvest date. Transcript abundance of 4086 genes was differentially changed over the three harvest dates in tolerant and susceptible barley in response to D. noxia feeding. Across the three harvest dates, the greatest number of genes was differentially expressed in both barleys at three days after aphid introduction. A total of 909 genes showed significant levels of change in the tolerant barley in response to D. noxia feeding as compared to susceptible plants infested with aphids. Many of these genes could be assigned to specific metabolic categories, including several associated with plant defense and scavenging of reactive oxygen species (ROS). Interestingly, two peroxidase genes, designated HvPRXA1 and HvPRXA2, were up-regulated to a greater degree in response to D. noxia feeding on tolerant barley plants, indicating that specific peroxidases could be important for the tolerance process. These findings suggest that the ability to elevate and sustain levels of ROS-scavenging enzymes could play an important role in the tolerant response.

Introduction. After harvest, litchi fruits (Litchi chinensis Sonn.) rapidly lose their bright red skin color. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments associated with the oxidation of phenolic compounds by polyphenol oxidase (PPO) and/or peroxidase (POD). An anthocyanase has been also identified in litchi peel. Our work aimed at characterizing two specific litchi varieties that differ greatly in their color and browning behavior. Materials and methods. The anthocyanins, polyphenol oxidase (PPO), peroxidase (POD) and anthocyanase in the pericarp of two litchi cultivars, Kwai May and Wai Chee, grown in Reunion Island and Spain, respectively, were studied. Results and discussion. The qualitative composition of major anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside) was identical for the two cultivars studied, but, quantitatively, the variety Kwai May had a lower concentration than Wai Chee (64% less) of cyanidin-3-rutinoside. This component represented more than 90% of total anthocyanins in both cultivars. The activity of PPO was 6 times greater in the variety Kwai May than in Wai Chee and the activity of POD 30 times greater. The activity of POD was greater than that of PPO in both varieties. These differences help to explain the different behaviors of the cultivars during subsequent postharvest studies.

Introduction. Pour introduire Ricinodendron heudelotii (Euphorbiacée) dans les agrosystèmes, des plantules ayant un système racinaire pivotant peuvent être produites par embryogenèse somatique in vitro. Nous avons étudié l’effet de quelques phytohormones exogènes sur certains paramètres biochimiques caractéristiques de l’embryogenèse somatique de l’espèce. Matériel et méthodes. Des cals et des embryons somatiques ont été induits par culture de fragments de feuilles sur un milieu de base enrichi en (1, 2 ou 3) mg 2,4-D·L–1 ou de combinaisons [2,4-D / kinétine] ou [2,4-D / BAP] impliquant différentes concentrations des hormones. Les extractions et analyses des sucres totaux, phénols, protéines totales et activité des peroxydases ont été faites après (30, 50 et 70) j de développement des cals. Résultats. Après 30 j de culture, les meilleurs pourcentages d’explants formant des cals ont varié de 72,1 % à 100 % selon les phyto-hormones utilisées. Après 50 j de culture, ces cals ont formé des amas globulaires de cellules en division (nodules embryonnaires). Après 70 j de culture, 17,4 % des cals ont différencié les embryons somatiques multiformes en présence de 3 mg 2,4-D·L–1; 23,1 %, en présence de [1 mg 2,4-D·L–1 + 1 mg kinétine·L–1] et 27,6 %, [1 mg 2,4-D·L–1 + 2 mg BAP·L–1]. La teneur en sucres a été la plus élevée à 30 j (formation des cals) et 50 j (formation des nodules embryonnaires sur cals), alors que les teneurs en phénols, en protéines et l’activité des peroxydases ont été plus élevées à 70 j (différenciation des embryons somatiques sur cals). Discussion et conclusion. À l’instar de ce qui se passe chez d’autres espèces végétales, chez R. heudelotii, les phytohormones exogènes interviendraient dans le contrôle du métabolisme des paramètres biochimiques impliqués dans la formation des embryons somatiques et de leur développement.

Background and objective The objective of this study was to determine the dose as well as the duration of exposure–dependent effects of methohexital on neutrophil [polymorphonuclear leucocyte (PMN)] free amino acid profiles and, in a parallel study, on PMN immune functions.

Methods Whole blood samples were taken from 20 volunteers and incubated with methohexital [0 (control), 3.6, 26, 130 and 260 μgmL−1] for 10, 30, 60 or 120 min. PMN amino acid profiles were documented using advanced PMN separation and highperformance liquid chromatography procedures. Superoxide anion (O2−) and hydrogen peroxide production (H2O2), and activity of released myeloperoxidase (MPO), were determined photometrically.

Results After methohexital, significant dose (≥26 μg mL−1) as well as duration of exposure–dependent (≥30 min) increases in histidine, isoleucine, leucine, valine, methionine, serine, glycine, threonine, and decreases in glutamine, glutamate, aspartate, asparagine, arginine, ornithine, citrulline, alanine and taurine were observed (P ≤0.05). Concerning PMN immune functions, methohexital significantly decreased O2−, H2O2 formation and MPO (≥26 μgmL−1, ≥30 min, P≤0.05).

Conclusions Altogether, there is significant relevance to the pharmacological regimens which enhance the supply of methohexital in whole blood. In regards to our results, we suggest that considerable changes in PMN ‘dynamic free amino acid pool’, for example induced by methohexital, may be one of the determinants in cell nutrition adversely affecting PMN metabolism. It is partially through its effect on the PMN free amino acid pool that maleficent pharmacological stress may have an unintentional influence on PMN immune functions.

The three youngest age-classes of needles of Norway spruce (Picea abies) were collected from four sites in the Krusne Hory Mountains (Czech Republic) characterized by different levels of damage caused by environmental pollution. Histochemical methods did not reveal any differences in localization of phenolics among the needles. Mesophyll cells close to the epidermis of needles and cells around resin ducts and substomatal cavities often accumulated higher amounts of phenolics than the rest of the mesophyll cells, but this was independent of age and damage. Needles of different age- and damage-class did not show any marked changes in general lignification pattern. However, a lower intensity of histochemical detection of lignin was observed in needles from the most damaged site. This finding was confirmed by chemical analysis using thioglycolic acid. Generally, the amount of lignin in mesophyll cells was lower in damaged trees than in healthy ones. Using the Folin–Ciocalteau method, no significant differences in the total content of phenolics were observed in the needles, although HPLC revealed marked alterations in the forms of seven phenolic acids. Concentrations of conjugated forms of phenolic acids (esters and glycosides) were higher in damaged needles (255.9 μg g−1 f. wt) than in healthy needles (189.8 μg g−1 f. wt). By contrast, content of esterified phenolic acids incorporated into cell walls was higher in needles from healthy trees (101.1 μg g−1 f. wt) than in damaged needles (78.3 μg g−1 f. wt). Marked differences were also observed in the activity of soluble peroxidases, although the activity of ionically bound forms was approximately the same in healthy and damaged needles. The total amounts of chlorophylls and carotenoids decreased as environmental damage increased.