Guillermo R. Reboredo

Non-enzymatic lipid peroxidation of microsomes and mitochondria isolated from liver and heart of pigeon and rat.

Studies were carried out to determine the level of ascorbate-Fe2+ dependent lipid peroxidation of mitochondria and microsomes isolated from liver and heart of rat and pigeon. Measurements of chemiluminescence indicate that the lipid peroxidation process was more effective in mitochondria and microsomes from rat liver than in the same organelles obtained from pigeon. In both mitochondria and microsomes from liver of both species a significant decrease of arachidonic acid was observed during peroxidation. The rate C18:2 n6/C20:4 n6 was 4.5 times higher in pigeon than in rat liver. This observation can explain the differences noted when light emission and unsaturation index of both species were analysed. A significant decrease of C18:2 n6 and C20:4 n6 in pigeon liver mitochondria was observed when compared with native organelles whereas in pigeon liver microsomes only C20:4 n6 diminished. In rat liver mitochondria only arachidonic acid C20:4 n6 showed a significant decrease whereas in rat liver microsomes C20:4 n6 and C22:6 n3 decreased significantly. However changes were not observed in the fatty acid profile of mitochondria and microsomes isolated from pigeon heart. In the heart under our peroxidation conditions the fatty acid profile does not appear to be responsible for the different susceptibility to the lipid peroxidation process. The lack of a relationship between fatty acid unsaturation and sensitivity to peroxidation observed in heart suggest that other factor/s may be involved in the protection to lipid peroxidation in microsomes and mitochondria isolated from heart.

Fatty acid profiles and lipid peroxidation of microsomes and mitochondria from liver, heart and brain of Cairina moschata

Studies were done to analyze the fatty acid composition and sensitivity to lipid peroxidation (LP) of mitochondria and microsomes from duck liver, heart and brain. The fatty acid composition of mitochondria and microsomes was tissue-dependent. In particular, arachidonic acid comprised 17.39+/-2.32, 11.75+/-3.25 and 9.70+/-0.40% of the total fatty acids in heart, liver and brain mitochondria respectively but only 13.39+/-1.31, 8.22+/-2.43 and 6.44+/-0.22% of the total fatty acids in heart, liver and brain microsomes, respectively. Docosahexahenoic acid comprised 17.02+/-0.78, 4.47+/-1.02 and 0.89+/-0.07% of the total fatty acids in brain, liver and heart mitochondria respectively but only 7.76+/-0.53, 3.27+/-0.73 and 1.97+/-0.38% of the total fatty acids in brain, liver and heart microsomes. Incubation of organelles with ascorbate-Fe(2+) at 37 degrees C caused a stimulation of LP as indicated by the increase in light emission: chemiluminescence (CL) and the decrease of arachidonic acid to: 5.17+/-1.34, 8.86+/-0.71 and 5.86+/-0.68% of the total fatty acids in heart, liver and brain mitochondria, respectively, and to 4.10+/-0.61 in liver microsomes. After LP docosahexahenoic acid decrease to 7.29+/-1.47, 1.36+/-0.18 and 0.30+/-0.11% of the total fatty acids in brain, liver and heart mitochondria. Statistically significant differences in the percent of both peroxidable fatty acids (arachidonic and docosahexaenoic acid) were not observed in heart and brain microsomes and this was coincident with absence of stimulation of LP. The results indicate a close relationship between tissue sensitivity to LP in vitro and long chain polyunsaturated fatty acid concentration. Nevertheless, any oxidative stress in vitro caused by ascorbate-Fe(2+) at 37 degrees C seems to avoid degradation of arachidonic and docosahexaenoic acids in duck liver and brain microsomes. It is possible that because of the important physiological functions of arachidonic and docosahexaenoic acids in these tissues, they are protected to maintain membrane content during oxidative stress.

A low degree of fatty acid unsaturation leads to high resistance to lipid peroxidation in mitochondria and microsomes of different organs of quail (Coturnix coturnix japonica)

Birds – particularly long-lived species – have special adaptations for preventing tissue damage caused by reactive oxygen species. The objective of the present study was to analyse the fatty acid composition and non-enzymatic lipid peroxidation of mitochondria and microsomes obtained from liver, heart and brain of quail (Coturnix coturnix japonica), a short-lived bird. Fatty acids located in total lipids of rat liver, heart and brain mitochondria and microsomes were determined using gas chromatography and lipid peroxidation was evaluated using a chemiluminescence assay. The unsaturated fatty acid content found in mitochondria and microsomes of all tissue examined was approximately 50 and 40%, respectively with a prevalence of C18:1 n9. The C18:2 n6 content in brain mitochondria was significantly lower as compared to liver and heart mitochondria. Whereas the C20:4 n6 content in mitochondria from all tissues examined and brain microsomes was approximately 6%, liver and heart microsomes exhibited lower values. C22:6 n3 was absent in liver mitochondria, very low content in liver microsomes and heart organelles (between 0.5 and 1%) and high content in brain organelles, with mitochondria having the highest value (11%). Whereas liver and heart organelles were not affected when subjected to lipid peroxidation, brain mitochondria were highly affected, as indicated by the increase in chemiluminescence and a considerable decrease of C20:4 n6 and C22:6 n3. These results indicate that a low degree of fatty acid unsaturation in liver and heart organelles of quail, a short-lived bird, may confer advantage by decreasing their sensitivity to lipid peroxidation process.

High resistance to lipid peroxidation of bird heart mitochondria and microsomes: Effects of mass and maximum lifespan

The aim of this investigation was to study the connection between body size, fatty acid composition and sensitivity to lipid peroxidation of heart mitochondria and microsomes isolated from different size bird species: manon (Lonchura striata), quail (Coturnix coturnix var japonica), pigeon (Columba livia), duck (Cairina moschata) and goose (Anser anser), representing a 372-fold range of body mass. Fatty acids of total lipids were determined using gas chromatography and lipid peroxidation was evaluated with a chemiluminescence assay. The fatty acids present in heart organelles of the different bird species analyzed showed a small number of significant allometric trends. In mitochondria, from the individual fatty acid data, palmitoleic acid (C16:1 n7) increased allometrically (r=0.878), while stearic acid (C18:0) was negatively related to body mass (r=-0.903). Interestingly, none of the calculated fatty acid variables, the average fatty acid saturated, monounsaturated, polyunsaturated (PUFA) and the unsaturation index (UI) was established to show significant body size-related variations. In heart microsomes, the content of C18:0 was significantly smaller (r=-0.970) in the birds of greater size. A significant allometric increase in linoleic acid (C18:2 n6) (r=0.986), polyunsaturated (r=0.990) and UI (r=0.904) was observed in the larger birds. The total n6 fatty acids of heart mitochondria did not show significant differences when it was correlated to body mass of the birds. Moreover, positive allometric relationships were shown for microsomes. The total n3 fatty acids of heart mitochondria and microsomes indicated no significant correlations to body mass of birds. The C16:1 n7, C18:0 in mitochondria and C18:0, C18:2 n6, PUFA, UI and PUFA n6 in microsomes showed significant differences when they were correlated to maximum life span (MLSP) of birds. As light emission=chemiluminescence originated from heart organelles was not statistically significant, a lack of correlation between the sensitivity to lipid peroxidation and body size or maximum life span was obtained. These results indicate that the high resistance of bird hearts to the attack by free radicals is body size-independent and would be related to the preservation of cardiac function.

A NEW OXYURIDA (THELASTOMATIDAE) FROM CYCLOCEPHALA SIGNATICOLLIS BURMEISTER (COLEOPTERA: SCARABAEIDAE) FROM ARGENTINA

Cephalobellus cyclocephalae n. sp. (Oxyurida: Thelastomatidae), a parasite of larvae of Cyclocephala signaticollis (Coleoptera, Scarabaeidae), found in Argentina is described and illustrated. It is characterized by the cuticle striated at the anterior end in both sexes, with 15 annules, buccal cavity short and not armed, and the male with 4 pairs of genital papillae, 1 pair of preanal papillae, 3 pairs of postanal papillae.

Una nueva especie del género Cameronia Basir (Oxyurida: Thelastomatidae) parásita de Gryllodes laplatae Sauss (Orthoptera: Gryllidae) en Argentina

Cameronia laplatae n. sp. found in City Bell, Argentina, parasitizing crickets is described and illustrated. The new species is distinguished from other members of the genus Cameronia by the distribution pattern of the genital papillae in the male. It differs from all congeners mainly in having two pairs preanal y two pairs postanal papillae.

New species of Cephalobium (Rhabditida, Diplogasteridae) parasite of nymphs of Gryllodes laplatae (Orthoptera, Gryllidae) in Argentina

Cephalobium bidentatum sp. nov., parasitizing nymphs of Gryllodes laplatae Sauss (Orthoptera, Gryllidae) from Argentina, is described and illustrated. It is distinguished from other members of the genus Cephalobium COBB, 1920, by having the buccal cavity very sclerotized with two hook-shaped teeth, vagina short and muscular, male has two spicules with hook-shaped tips, and by the distribution pattern of the postanal papillae: one pair under the anus, three pairs between the anus and the tail, and two pairs at the base of the tail appendage.

Binema bonaerensis n. sp. (Oxyurida: Thelastomatidae) parasite of Neocurtilla claraziana saussure (Orthoptera: Gryllotalpidae) in Argentina

The nematode Binema bonaerensis n. sp. (Oxyurida: Thelastomatidae) is described from the intestine of the mole cricket of Neocurtilla claraziana Saussure (Orthoptera: Gryllotalpidae) from Buenos Aires Province, Argentina. It is distinguished mainly by having a conical tail; three sclerotized arches in the buccal cavity; an excretory pore immediately posterior to the base of the esophagus and the presence of five pairs of male genital papillae with one pair preanal and four pairs postanal.

An allometric study of fatty acids and sensitivity to lipid peroxidation of brain microsomes and mitochondria isolated from different bird species

The objective of this investigation was to examine the relationship between body size, fatty acid composition and sensitivity to lipid peroxidation of mitochondria and microsomes isolated from the brain of different size bird species: manon, quail, pigeon, duck and goose, representing a 372-fold range of body mass. Fatty acids of total lipids were determined using gas chromatography and lipid peroxidation was evaluated using a chemiluminescence assay. The allometric study of the fatty acids present in brain mitochondria and microsomes of the different bird species showed a small number of significant allometric trends. In mitochondria the percentage of monounsaturated fatty acids, was significantly lower in the larger birds (r=-0.965; P<0.008). The significant allometric increase in 18:2 n-6; linoleic acid (r=0.986; P<0.0143), polyunsaturated (r=0.993; P<0.007) and total unsaturated (r=0.966; P<0.034) in brain microsomes but not in mitochondria may indicate a preferential incorporation of this fatty acid in the brain endoplasmic reticulum of the larger bird species. The brain of all birds studied had a high content of docosahexaenoic acid. However brain mitochondria but not microsomes isolated from all the birds analyzed showed a significant decrease of arachidonic and docosahexaenoic acids during lipid peroxidation. The allometric analyses of chemiluminescence were not statistically significant. In conclusion our results show absence of correlation between the sensitivity to lipid peroxidation of brain mitochondria and microsomes with body size and maximum life span.

Two new rhabditida species (Nematoda: Rhabditidae) parasites of Cyclocephala signaticollis (Coleoptera: Scarabaeidae) in Argentina.

Two different Rhabditida species (Nematoda: Rhabditidae) Parasitorhabditis platidontus n. sp. and Cruznema campestris n. sp. are described and illustrated from the larvae of Cyclocephala signaticollis (Coleoptera: Scarabaeidae) from Buenos Aires province, Argentina. Parasitorhabditis platidontus n. sp. is characterized by having 4 odontoplates in the stoma and the vulva is at 80% of the length of the body. Cruznema campestris n. sp. can be distinguished by the presence of 4 odontoplates and the arrangement of the male genital papillae, 9 pairs, of which 4 are preanal and 5 postanal.