Analysis of Mycosporine-Like Amino Acids in Selected Algae and Cyanobacteria by Hydrophilic Interaction Liquid Chromatography and a Novel MAA from the Red Alga Catenella repens

Mycosporine-like amino acids (MAAs), a group of small secondary metabolites found in algae, cyanobacteria, lichens and fungi, have become ecologically and pharmacologically relevant because of their pronounced UV-absorbing and photo-protective potential. Their analytical characterization is generally achieved by reversed phase HPLC and the compounds are often quantified based on molar extinction coefficients. As an alternative approach, in our study a fully validated hydrophilic interaction liquid chromatography (HILIC) method is presented. It enables the precise quantification of several analytes with adequate retention times in a single run, and can be coupled directly to MS. Excellent linear correlation coefficients (R² > 0.9991) were obtained, with limit of detection (LOD) values ranging from 0.16 to 0.43 µg/mL. Furthermore, the assay was found to be accurate (recovery rates from 89.8% to 104.1%) and precise (intra-day precision: 5.6%, inter-day precision ≤6.6%). Several algae were assayed for their content of known MAAs like porphyra-334, shinorine, and palythine. Liquid chromatography-mass spectrometry (LC-MS) data indicated a novel compound in some of them, which could be isolated from the marine species Catenella repens and structurally elucidated by nuclear magnetic resonance spectroscopy (NMR) as (E)-3-hydroxy-2-((5-hydroxy-5-(hydroxymethyl)-2-methoxy-3-((2-sulfoethyl)amino)cyclohex-2-en-1-ylidene)amino) propanoic acid, a novel MAA called catenelline.     

Simulated water and solute distribution from a crossed triple line-source

Summary Multivariable irrigation experiments are usually expensive and seldom cover the whole range of desired values. The crossed triple line-source (CTLS) was designed to provide a relatively simple and inexpensive irrigation system for creating continuous gradients of more than one variable. A computer model was developed to assist in evaluating the continuously changing multivariable levels, produced by the CTLS, given various inputs. A single sprinkler's distribution function was used in the model's development. The results of the overlapping sprinkling patterns are calculated throughout the experimental area for water depth, salinity level, and Nitrogen concentration. Measured values of irrigation water electrical conductivity (EC_i) and Nitrogen concentration were in good agreement with predicted values.     

Classification of cassava into ‘bitter’ and ‘cool’ in Malawi: From farmers' perception to characterisation by molecular markers

Cassava roots, a major food in Africa, contain cyanogenic glucosides that may cause toxic effects. Malawian women farmers considered fields of seemingly similar cassava plants to be mixes of both ‘cool’ and ‘bitter’ cultivars. They regard roots from ‘cool’ cultivars as non-toxic. Roots of ‘bitter’ were considered to require extensive traditional processing done by women to be safe for consumption. But curiously, these women farmers preferred ‘bitter’ cultivars since toxicity confers protection against theft, which was a serious threat to the food security of their families. We studied how well these farmers comprehend the effects of genetic variations in cassava when dealing with cyanogenesis in this complex system. Using molecular markers we show that most plants farmers identified as belonging to a particular named cultivar had a genotype typical of that cultivar. Farmers' ethno-classification into ‘cool’ and ‘bitter’ cultivars corresponded to a genetic sub-division of the typical genotypes of the most common cultivars, with four-fold higher cyanogenic glucoside levels in the bitter cultivars. Examining morphology, farmers distinguished genotypes better than did the investigators when using a standard botanical key. Undoubtedly, these women farmers grasp sufficiently the genetic diversity of cassava with regard to cyanogenesis to simultaneously benefit from it and avoid its dangers. Consequently, acyanogenic cassava – the breeding of which is an announced good of some cassava genetic improvement programmes – is not a priority to these farmers. Advances in molecular genetics can help improve food supply in Africa by rapid micropropagation, marker assisted breeding and introduction of transgenic varieties, but can also help to elucidate tropical small-scale farmers' needs and skills. This revised version was published online in August 2006 with corrections to the Cover Date.     

Intermediate landscape disturbance maximizes metapopulation density

The viability of metapopulations in fragmented landscapes has become a central theme in conservation biology. Landscape fragmentation is increasingly recognized as a dynamical process: in many situations, the quality of local habitats must be expected to undergo continual changes. Here we assess the implications of such recurrent local disturbances for the equilibrium density of metapopulations. Using a spatially explicit lattice model in which the considered metapopulation as well as the underlying landscape pattern change dynamically, we show that equilibrium metapopulation density is maximized at intermediate frequencies of local landscape disturbance. On both sides around this maximum, the metapopulation may go extinct. We show how the position and shape of the intermediate viability maximum is responding to changes in the landscape’s overall habitat quality and the population’s propensity for local extinction. We interpret our findings in terms of a dual effect of intensified landscape disturbances, which on the one hand exterminate local populations and on the other hand enhance a metapopulation’s capacity for spreading between habitat clusters.     

Bleeding of Farmed Atlantic Cod: Residual Blood,Color, and Quality Attributes of Pre- and Postrigor Fillets as Affected by Perimortem Stress and Different Bleeding Methods

The main objectives of the study were to (a) assess the effect of perimortem stress on blood drainage, (b) compare the efficiency of gill cutting and direct gutting as bleeding methods, and (c) compare pre- and postrigor filleting strategies for presence of residual blood in Atlantic cod fillets. Anesthetized cod had significantly higher drainage of blood compared to stressed fish. Nevertheless, the visual assessments of residual blood were not affected by stress or bleeding method. Some minor, but significant, differences between pre- and postrigor fillets were found. Stressed fish were initially less light in color than those unstressed, but after ice storage there was no noticeable difference. However, initially, the largest difference in fillet color was due to different bleeding methods. Fillets cut from fish subjected to gill cutting were lighter and less red in color than those bled by direct gutting. After 7 and 21 days of storage, the color differences observed in fresh and salted fillets, respectively, were mainly due to the different rigor status when they were filleted, indicating that fillets cut postrigor were superior to fillets cut prerigor. Prerigor filleting resulted in lower water holding capacity after ice storage in anesthetized, direct gutted cod.     

Evaluation of opioid receptors in synovial membranes of horses

OBJECTIVE: To evaluate mu-opioid receptors in synovial membranes of horses and determine whether these receptors are up-regulated in nerve endings during inflammation. SAMPLE POPULATION: Synovial tissue obtained from 39 client-owned horses during arthroscopy and 14 research horses during necropsy; brain and synovial tissues were obtained during necropsy from 1 horse, and control tissues were obtained from a mouse. PROCEDURE: Horses were classified into 7 groups on the basis of histologically determined degree of inflammation. Binding of primary rabbit antibody developed against mu-opioid receptors in equine synovial tissue was studied, using western blot analysis. Synovial membranes were tested for mu-opioid receptors by immunohistochemical staining, using a diaminobenzidine-cobalt chloride chromogen. Homogenates of synovial membranes were evaluated by use of radioligand binding. RESULTS: Examination of western blots of equine thalamus revealed that rabbit antibody developed against mu-opioid receptors yielded a band (molecular weight, 55 kd) that corresponded with that of other opioid receptors. Use of immunohistochemical staining of synovial tissue revealed considerable staining in the proliferative lining layer and in regions surrounding vascular structures. Specific radioligand binding of tissue homogenates was found in all groups. We did not detect significant differences in binding between horses with inflammation and horses without inflammation. CONCLUSIONS AND CLINICAL RELEVANCE: Results of immunohistochemical analysis and radioligand binding of tissue homogenates suggest that there are opioid receptors in synovial membranes of horses. Our results support the practice of intra-articular administration of opioids to relieve pain after arthroscopic surgery in horses.     

Effect of mammary secretions on functions of polymorphonuclear leukocytes in pigs

OBJECTIVE: To determine the effects of porcine mammary secretions on polymorphonuclear (PMN) leukocyte function and to relate concentrations of estradiol-17beta and cortisol in mammary secretions to PMN cell function. SAMPLE POPULATION: Mammary secretions from 10 healthy sows and blood PMN leukocytes from 27 healthy sows. PROCEDURE: Mammary secretions were collected within 24 hours after parturition (colostrum) and 12 to 13 days later (milk). Chemoattractant properties were assessed by use of a cell migration assay. Phagocytic capacity of PMN cells in colostrum and milk was assessed by recording chemiluminescence following phagocytosis of Escherichia coli or zymosan. Estradiol-17beta and cortisol concentrations were determined by use of radioimmunoassays. RESULTS: Chemoattractant properties of colostrum and milk were significantly greater than that of zymosan-activated serum. However, chemoattractant properties did not differ significantly between the 2 types of secretions. The capacity of PMN cells in colostrum to phagocytose either zymosan or E. coli was less, compared with cells in milk, and the ability of cells in either type of mammary secretion to phagocytose E. coli was greater than the ability to phagocytose zymosan. Concentrations of estradiol-17beta and cortisol were greater in colostrum, compared with milk. No clear relation was evident between PMN cell activity and hormone concentrations in mammary secretions. CONCLUSIONS AND CLINICAL RELEVANCE: Although chemoattractant properties of colostrum and milk did not differ, the phagocytic capacity of PMN cells in colostrum was significantly less than that of cells in milk. This may predispose sows to coliform mastitis during the early postparturient period.     

Total and Differential Leucocyte Counts and Lymphocyte Subpopulations in Lymph, Afferent and Efferent to the Supramammary Lymph Node, During Endotoxin-Induced Bovine Mastitis

Leucocyte trafficking in afferent and efferent mammary lymph and the supramammary lymph node in cows was examined during 4 h after intramammary infusion of endotoxin from Escherichia coli. Total and differential leucocyte counts were measured in milk, blood and lymph. The proportions of CD4(+), CD8(+), major histocompatibility complex (MHC) class II(+) and IgM(+) lymphocytes were examined in the lymph and lymph node. At post-infusion hour (PIH) 4, the flow rates of both lymph fluids had increased approximately eightfold. Total leucocyte concentration increased in afferent lymph, but decreased in efferent lymph. Neutrophils increased in afferent lymph at PIH 2 and in efferent lymph and milk at PIH 4. The predominant cell type in afferent lymph shifted from lymphocyte to neutrophil while lymphocyte was still at PIH 4 the predominant type in efferent lymph. Among the lymphocytes, B cells were predominant in afferent lymph and lymph node at PIH 4 while T cells, mainly CD4(+) cells, were predominant in efferent lymph both at PIH 0 and PIH 4. The CD4 : CD8 ratio was higher in efferent lymph and the challenged lymph node than in afferent lymph and the control node, respectively. There was a significant difference in proportions of each lymphocyte subpopulation except for IgM(+) cells, between afferent and efferent lymph after infusion. According to the results, there was already during the first hours of the immune response, a non-random trafficking of neutrophils and lymphocyte subpopulations resulting in a changed distribution of cells in afferent and efferent lymph and a difference in lymphocyte reactivity between the two lymph fluids.     

Effects of topical application of three pyrethroid insecticides on spontaneous activity in sensory nerves of Periplaneta americana and Blabera craniifer

Electrophysiological techniques were used to analyse the effects, on the activity in the sensory nerves of Periplaneta americana and Blabera craniifer, after topical applications of three different pyrethroid insecticides: deltamethrin, (1R)-tetramethrin, and 5-benzyl-3-furylmethyl (E)-(1R)-cis-2,2-dimethyl-3-(2-oxothiolan-3-ylidenemethyl)cyclopropanecarboxylate (RU-15525; ‘Kadethrin’). The insecticides were applied: (a) to the cercus, and the activity was recorded on the cercal nerve and on the central nervous connectives; or (b) to the last segments of the metathoracic leg, and the corresponding activity was recorded on the crural nerve. In both cases, several categories of receptor were affected but the major part of the recorded activity came from the mechanoreceptors, the functional properties of which were monitored throughout the experiments. In most cases, topical application of small amounts of pyrethroid were found to induce an increase in the spontaneous activity, followed by decrease in excitability. Characteristic differences were, however, found between the three compounds and the effects were concentration- and solvent-dependent. The results were consistent with those obtained from experiments on the sense organs of vertebrates but did not support the idea that the effectiveness of pyrethroid insecticides with an α-cyanobenzyl group, compared with those without an α-cyanobenzyl group, originates from a greater effect on the peripheral sensory receptors.     

Afforestation trials with Prosopis chilensis (Mol.) Stuntz and Prosopis flexuosa D.C. in the Dry Chaco, Argentina

In implantation trials carried out with Prosopis chilensis and Prosopis flexuosa, the following variables were considered: implantation time (December and March), implantation technique (direct seeding and seedling transplantation) and age of the seedlings at the time of transplantation (60, 105 and 150 days). Survival was evaluated for more than 9 months after implantation and trials were repeated in 3 consecutive years.

Results from both species were similar and they show that survival after transplantation was higher (60–80%) than from direct seeding (35–45%). Survival from transplantation was independent of the size and age of the seedlings and it was less affected by climatic conditions than direct field sowing. Survival from direct seeding was higher in March than in December. The best time for either implantation alternative would be the end of the summer or beginning of fall, when climatic conditions increase the probability of seedling survival.