Antifungal and antibacterial activities of Araucaria araucana (Mol.) K. Koch heartwood lignans

Five lignans (secoisolariciresinol, pinoresinol, eudesmin, lariciresinol, and lariciresinol-4-methyl ether) were isolated from an MeOH extract from Araucaria araucana (Mol.) K. Koch wood for the first time in this species and their structures determined with spectroscopic methods. The antimicrobial activities of these compounds were determined for the bacteria Citrobacter sp., Bacillus subtilis, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, and Pseudomonas aeruginosa, and for the white rooting and staining fungi Mucor miehei, Paecilomyces variotii, Ceratocystis pilifera, Trametes versicolor, and Penicillium notatum, and in addition, the MeOH extract was evaluated against Aspergillus niger, Candida albicans, Fusarium moniliforme, F. sporotrichum and Trichophyton mentagrophytes. The most sensitive bacteria against pinoresinol were the Gram-positive. However, secoisolariciresinol exhibited a significant antifungal activity on fungi of white rooting and wood staining and this compound completely inhibited the mycelial growth of T. versicolor and C. pilifera at 300 and 400 microg per disc, respectively, whereas pinoresinol showed a moderate inhibitory activity. On the other hand, the MeOH extract had the highest activity against rooting and staining and pathogenic fungi as well as T. versicolor, Fusarium spp. and Trichophyton mentagrophytes, inhibiting completely the growth at 400 microg per disc.     

Coenzymes, viruses and the RNA world

The results of a detailed bioinformatic search for ribonucleotidyl coenzyme biosynthetic sequences in DNA- and RNA viral genomes are presented. No RNA viral genome sequence available as of April 2011 appears to encode for sequences involved in coenzyme biosynthesis. In both single- and double-stranded DNA viruses a diverse array of coenzyme biosynthetic genes has been identified, but none of the viral genomes examined here encodes for a complete pathway. Although our conclusions may be constrained by the unexplored diversity of viral genomes and the biases in the construction of viral genome databases, our results do not support the possibility that RNA viruses are direct holdovers from an ancient RNA/protein world. Extrapolation of our results to evolutionary epochs prior to the emergence of DNA genomes suggest that during those early stages living entities may have depended on discontinuous genetic systems consisting of multiple small-size RNA sequences.     

Ovulation induction in rabbit does submitted to artificial insemination by adding buserelin to the seminal dose

This study was aimed at determining if a GnRH analogue, buserelin, could be used for ovulation induction in rabbit does submitted to artificial insemination (AI) by intravaginal administration, by adding the hormone to the seminal dose. In a first experiment, 39 secondiparous experimental does (Hyplus strain PS19, Grimaud Frères, France, of about 30 weeks of age) were divided into 3 groups of 13 does each, which at the moment of AI received the following treatments, respectively: (1) control: an intramuscular injection of buserelin (0.8 microg/doe), (2) 8 microg/doe of buserelin added to the insemination dose, and (3) 16 microg/doe of buserelin added to the insemination dose. The experiment was done using 3 consecutive cycles at 42 day-intervals (n = 39). Four does from each of the 3 groups had blood taken at the fourth cycle for LH determination at 0, 60, 90, 120 and 150 min relative to AI. Kindling rates were 82% (28/34), 56% (29/36) and 85% (33/39), respectively for treatments 1, 2 and 3. In the does of groups 2 and 3, LH peaks were detected 60 min after AI, whereas in the does from group 1, the LH peak was detected 90 min after AI. Prolificacy was not different for the 3 treatments (average litter sizes ranged from 10.4 to 10.8). In a second experiment, 3 buserelin concentrations (8, 12 and 16 microg/doe) were used intravaginally and compared with the control treatment (0.8 microg/doe, via intramuscular). This experiment was done using 100 nulliparous rabbit does (Hyplus strain PS19, Grimaud Frères, France, of about 19 weeks of age) (4 groups of 25 does each) located on a commercial farm, to test if the previous results would be confirmed under field conditions. Kindling rates were no different (P < 0.05) for the 4 treatment groups [91.7% (22/24), 79.2% (19/24), 87.0% (20/23) and 87.5% (21/24) respectively for the control, 8, 12 and 16 microg of intravaginal buserelin], however, prolificacy was higher when using the maximal dose of intravaginal buserelin (11.7 vs. 9.4 for the control group). It was concluded that buserelin can be used for ovulation induction in rabbit does when included in the seminal dose, with similar AI results as those obtained when the hormone is administered intramuscularly.     

Bayesian estimates of genetic parameters for pre-conception traits, gestation length and calving interval in beef cattle

A total of 5253 records obtained from 2081 Rubia Gallega beef cows managed using artificial insemination as the only reproduction system were analysed to estimate genetic parameters for days to first insemination (DFI), days from first insemination to conception (FIC), number of inseminations per conception (IN), days open (DO), gestation length (GL) and calving interval (CI) via multitrait Bayesian procedures. Estimates of the mean of posterior distribution of the heritability of DFI, FIC, IN, DO, GL and CI were, respectively, 0.050, 0.078, 0.071, 0.053, 0.037 and 0.085 and the corresponding estimates for repeatability of these traits were 0.116, 0.129, 0.147, 0.138, 0.082 and 0.132, respectively. No significant genetic correlations associated to DFI or GL were found. However, genetic correlations between the other four analysed traits were high and significant. Genetic correlations between FIC and IN, DO and CI were similar and higher than 0.85. Genetic correlations of IN-DO and IN-CI were over 0.65. The highest genetic correlation was estimated for the pair DO-CI (0.992) that can be considered the same trait in genetic terms. Results indicated that DFI can be highly affected by non-genetic factors thus limiting its usefulness to be used as an earlier indicator of reproductive performance in beef cattle. Moreover, GL could not be associated to the reproductive performance of the cow before conception. The other four analysed traits, FIC, IN, DO and CI, have close genetic relationships. The inclusion of IN as an earlier indicator of fertility in beef cattle improvement programs using artificial insemination as the main reproductive system can be advisable due to the low additional recording effort needed.     

Sexual selection in a polygynous rodent (Ctenomys talarum): an analysis of fighting capacity

The South American subterranean rodent genus Ctenomys (Caviomorpha: Octodontoidea), which uses both claws and teeth to dig, shows striking morphological adaptations to its specialized mode of life. Among other traits, the genus has evolved a powerful jaw musculature and procumbent incisors that are used for dento-excavation. Behavioral observations indicate that these traits are also used during male aggressive encounters, which characterize the polygynous mating system of one of the species of the genus, Ctenomys talarum. A question emerges about sexual selection: could it have induced further changes in traits primarily evolved as adaptations for digging? To address this issue, we studied functional and morphological attributes of the jaw and incisors in specimens of C. talarum. Incisor bite forces were measured on wild females and males from a local population (Mar de Cobo; Buenos Aires Province) by means of a strain gauge load cell force transducer. Museum specimens coming from the same population were studied to assess anatomical attributes of both sexes. Since this species exhibits dimorphism in body size, the possible effect of body mass on the studied traits was analyzed. Males and females showed significant differences in biting performance and mandibular width, but when size was taken into account these differences disappeared. However, other dimorphic traits can vary with a certain independence with respect to size, particularly the 2nd moment of area of the incisors and, to a lesser extent, incisor procumbency. The former geometrical parameter, which is proportional to the bending strength, was highly dimorphic. This fact suggests that, during aggressive encounters between males, biting would place large bending loads on the incisors.     

Ectomycorrhizas of Cortinarius helodes and Gyrodon monticola with Alnus acuminata from Argentina

Field ectomycorrhizas of Cortinarius helodes Moser, Matheny & Daniele (sp. nov) and Gyrodon monticola Sing. on Alnus acuminata Kunth (Andean alder, aliso del cerro) are described based on morphological and anatomical features. Ectomycorrhizal roots were sampled beneath fruitbodies of C. helodes and G. monticola from two homogeneous A. acuminata forest sites located in Tucumán and Catamarca Provinces in Argentina. C. helodes ectomycorrhizas showed a thick white to beige mantle exuding a milky juice when injured, were bluish toward the apex, and had hyphal strands in the mantle. G. monticola ectomycorrhizas showed some conspicuous features like highly differentiated rhizomorphs, inflated brown cells on the mantle surface, and hyaline and brown emanating hyphae with dolipores. Restriction fragment length polymorphism analysis of the nuclear rDNA internal transcribed spacer provided a distinctive profile for each of the collections of fruitbodies and the mycorrhizal morphotypes.