Genetic characterization of Latin-American Creole cattle using microsatellite markers

Genetic diversity in and relationships among 26 Creole cattle breeds from 10 American countries were assessed using 19 microsatellites. Heterozygosities, F-statistics estimates, genetic distances, multivariate analyses and assignment tests were performed. The levels of within-breed diversity detected in Creole cattle were considerable and higher than those previously reported for European breeds, but similar to those found in other Latin American breeds. Differences among breeds accounted for 8.4% of the total genetic variability. Most breeds clustered separately when the number of pre-defined populations was 21 (the most probable K value), with the exception of some closely related breeds that shared the same cluster and others that were admixed. Despite the high genetic diversity detected, significant inbreeding was also observed within some breeds, and heterozygote excess was detected in others. These results indicate that Creoles represent important reservoirs of cattle genetic diversity and that appropriate conservation measures should be implemented for these native breeds in order to minimize inbreeding and uncontrolled crossbreeding.     

Roles of cytokines and progesterone in the regulation of the nitric oxide generating system in bovine luteal endothelial cells

Nitric oxide (NO) produced by luteal endothelial cells (LECs) plays important roles in regulating corpus luteum (CL) function, yet the local mechanism regulating NO generation in bovine CL remains unclear. The purpose of the present study was to elucidate if tumor necrosis factor‐α (TNF), interferon γ (IFNG), and/or progesterone (P4) play roles in regulating NO generating system in LECs. Cultured bovine LECs obtained from the CL at the mid‐luteal stage (Days 8–12 of the cycle) were treated for 24 hr with TNF (2.9 nM), IFNG (2.5 nM), or P4 (0.032–32 µM). NO production was increased by TNF and IFNG, but decreased by P4 (P < 0.05). TNF and IFNG stimulated the relative steady‐state amounts of inducible nitric oxide synthase (iNOS) mRNA and iNOS protein expression (P < 0.05), whereas P4 inhibited relative steady‐state amounts of iNOS mRNA and iNOS protein expression (P < 0.05). In contrast, endothelial nitric oxide synthase (eNOS) expression was not affected by any treatment. TNF and IFNG stimulated NOS activity (P < 0.05) and 1400W, a specific inhibitor of iNOS, reduced NO production stimulated by TNF and IFNG in LECs (P < 0.05). Onapristone, a specific P4 receptor antagonist, blocked the inhibitory effect of P4 on NO production in LECs (P < 0.05). The overall findings suggest that TNF and IFNG accelerate luteolysis by increasing NO production via stimulation of iNOS expression and NOS activity in bovine LECs. P4, on the other hand, may act in maintaining CL function by suppressing iNOS expression in bovine LECs. Mol. Reprod. Dev. 79: 689–696, 2012. © 2012 Wiley Periodicals, Inc.     

Evf, a virulence factor produced by the Drosophila pathogen Erwinia carotovora, is an S-palmitoylated protein with a new fold that binds to lipid vesicles

Erwinia carotovora are phytopathogenic Gram-negative bacteria of agronomic interest as these bacteria are responsible for fruit soft rot and use insects as dissemination vectors. The Erwinia carotovora carotovora strain 15 (Ecc15) is capable of persisting in the Drosophila gut by the sole action of one protein, Erwinia virulence factor (Evf). However, the precise function of Evf is elusive, and its sequence does not provide any indication as to its biochemical function. We have solved the 2.0-angstroms crystal structure of Evf and found a protein with a complex topology and a novel fold. The structure of Evf confirms that Evf is unlike any virulence factors known to date. Most remarkably, we identified palmitoic acid covalently bound to the totally conserved Cys209, which provides important clues as to the function of Evf. Mutation of the palmitoic binding cysteine leads to a loss of virulence, proving that palmitoylation is at the heart of Evf infectivity and may be a membrane anchoring signal. Fluorescence studies of the sole tryptophan residue (Trp94) demonstrated that Evf was indeed able to bind to model membranes containing negatively charged phospholipids and to promote their aggregation.     

Predicting the distribution of the crested tinamous, Eudromia spp. (Aves, Tinamiformes)

A bioclimatic analysis of the crested tinamous was conducted to explore climatic factors underpinning the distribution of both Eudromia elegans and E. formosa and to evaluate its potential application in paleontological studies. The study utilized records throughout the entire known range of Eudromia spp. in southern South America. Relationships between 20 environmental parameters and the presence of Eudromia species were established, mapping and characterizing their spatial distribution in a geographic information system using BIOCLIM and MAXENT algorithms. The MAXENT prediction map shows a more homogeneous pattern while BIOCLIM showed a patchier pattern. The models applied here generated maps that adjust to the well-known previous distributions of both species. Nevertheless, for Eudromia elegans, the distribution predicted by MAXENT includes areas where it is actually considered absent, and the BIOCLIM prediction does not include some areas where it is presumed present. Eudromia formosa were found in warmer and wetter sites than E. elegans. Low precipitation areas were identified as suitable for Eudromia elegans. Strong differences between the climatic profiles for both Eudromia spp distributions occurred, with the precipitation the most important influence. E. formosa tolerates the highest maximum temperatures, whereas E. elegans supports the lowest temperatures.     

The Flowering Unit in the Synflorescences of Amaranthaceae

The structure of the synflorescence and the flowering units in Amaranthaceae are characterized. The synflorescence is polytelic. In the flowering unit we recognize the main florescence and the enrichment zone. The florescences may consist of: (1) Fully developed partial florescences bearing three or more flowers; (2) Partial florescences reduced to one or a few fertile flowers having prophylls with more or less modified axillary productions; or (3) No partial florescences but solitary flowers having prophylls with no axillary productions. We described the flowering unit in species with florescences bearing a solitary flower and the flowering unit in species with florescences bearing partial florescences. Hypothesized developmental processes are described, with a view to finding relationships among different models characterized in the family as well as defining characters for cladistic studies, which may be useful to depict all the variations observed.     

Restoring the activity of serum-inhibited bovine lung extract surfactant (BLES) using cationic additives

In this work four cationic additives were used to improve the surface activity of lung surfactants, particularly in the presence of bovine serum that was used as a model surfactant inhibitor. Two of those additives were chitosan in its soluble hydrochloride form with average molecular weights of 113 kDa and 213 kDa. The other two additives were cationic peptides, polylysine 50 kDa and polymyxin B. These additives were added to bovine lipid extract surfactant (BLES) and the optimal additive-surfactant ratio was determined based on the minimum surface tension upon dynamic compression, carried out in a constrained sessile drop (CSD) device in the presence of 50 μl/ml serum. At the optimal ratio all the BLES-additive mixtures were able to achieve desirable minimum surface tensions. The optimal additive-surfactant ratios for the chitosan chlorides are consistent with a previously proposed patch model for the binding of the anionic lipids in BLES to the positive charges in chitosan. For the peptides, the optimal binding ratios were consistent with ratios established previously for the binding of these peptides to monolayers of anionic lipids. The optimal formulation containing these peptides were able to reach low minimum surface tension in systems containing 500 μl/ml of serum, matching the effectiveness of a lung surfactant extract that had not undergone post-separation processes and therefore contained all its proteins and lipids (complete lung surfactant).     

Characterization of the satellite DNA Msat-160 from species of Terricola (Microtus) and Arvicola (Rodentia, Arvicolinae)

In the subfamily Arvicolinae (Cricetidae, Rodentia) the satellite DNA Msat-160 has been so far described in only some species from the genus Microtus and in one species from another genus, Chionomys nivalis. Here we cloned and characterized this satellite in two new arvicoline species, Microtus (Terricola) savii and Arvicola amphibius (terrestris). We have also demonstrated, by PCR and FISH, its existence in the genomes of several other species from both genera. These results suggest that Msat-160 already occurred in the common ancestor of the four genera/subgenera of Arvicolinae (Microtus, Chionomys, Arvicola, and Terricola). In Arvicola and Terricola, Msat-160 showed the basic monomer length of 160 bp, although a higher-order repeat (HORs) of 640 bp could have been probably replacing the original monomeric unit in A. a. terrestris. Msat-160 was localized by FISH mostly on the pericentromeric regions of the chromosomes, but the signal intensity and the number of carrier chromosomes varied extremely even between closely related species, resulting in a species-specific pattern of chromosomal distribution of this satellite. Such a variable pattern most likely is a consequence of a rapid amplification and contraction of particular repeats in the pericentromeric regions of chromosomes. In addition, we proposed that the rapid variation of pericentromeric repeats is strictly related to the prolific species radiation and diversification of karyotypes that characterize Arvicolinae lineage. Finally, we performed phylogenetic analysis in this group of related species based on Msat-160 that results to be in agreement with previously reported phylogenies, derived from other molecular markers.     

Mid-Holocene skua remains from King George Island,Antarctica

Seven avian remains from Mid-Holocene strata of the southeastern coast of Potter Peninsula (King George Island: Isla 25 de Mayo, South Shetland Islands, Antarctica) are reported. They were described and assigned to the brown skua Stercorarius antarcticus lonnbergi (Aves, Laridae), a living species currently breeding in the area. The presence of penguins in the same sequence is in agreement with the current dynamics of the coastal ecosystems of Antarctica. Nowadays, penguins and skuas frequent these same environments.