Uterine and fetal asphyxia monitoring in parturient sows treated with oxytocin

Oxytocin is used to induce and control parturition, nevertheless, the increase of uterine contractions decreases blood flow and gaseous exchange through the womb predisposing to intra-partum mortality. The objective of the present study was to evaluate the effect of oxytocin on myometrial activity, fetal intrauterine hypoxia and postnatal asphyxia in sows during farrowing. Hybrid (n = 120) sows approaching the time of farrowing were randomly assigned in two groups of 60 animals each. Group I (G(1): control) was treated IM with saline solution and Group II (G(2)) was injected IM with oxytocin (1IU/6kg LW) as a single dose at birth of the first piglet. Both average number of myometrial contractions and intensity in G(2) were greater (P < 0.01) as compared with G(1). The mean of intra-partum stillbirths (IPS's) and those where fetal cardiac frequency (FCF) or heart beats, could not be detected after birth, were greater (P < 0.01) in G(2) as compared with G(1). The average decelerations of FCF known as dips II, which indicate severe hypoxia, was greater in G(2) (P < 0.01) as compared with that of G(1). There was a greater (P < 0.01) number of intra-partum stillbirths, stained with severe meconium in G(2) when compared with G(1). Oxytocin treatment increased (P < 0.01) the number of pigs born alive with ruptured umbilical cords and those with different grades of meconium staining on their skin. It was concluded that administration of oxytocin at the onset of parturition increased the myometrial activity, decreased fetal cardiac frequency, predisposed the rupture of umbilical cords and the degree of meconium staining, and increased intra-partum mortality.     

An estimation of the floristic richness of Bolivia’s Andean dry valleys

We estimate plant species richness of Bolivian Andean dry valleys applying the species/genus ratio of Compositae to all reported genera for those regions. The results suggest the existence of around 1500 species in the Bolivian dry valleys (12.6% more than the species recorded). A brief biogeographical analysis of our results suggests that the use of species/genus ratio of Compositae to estimate the size of the flora in Bolivian Andean dry valleys should be considered with caution, since the central Andes are geologically very young, and explosive speciation processes have taken place only in some taxa (mainly in Bromeliaceae and Cactaceae). We offer some evidence pointing to the possibility that the Andean dry valleys may possess many more species than suggested by the Compositae species/genus ratio. We discuss the implications of our estimation for conservation of the Andean dry valleys, which only represent 0.7% of the protected area of Bolivia.     

Is <Emphasis Type="Italic">Pinus radiata</Emphasis> invading the native vegetation in central Chile? Demographic responses in a fragmented forest

Forest fragmentation facilitates the invasion of exotic species. This threat may be especially severe if forest fragments are surrounded by plantations of exotic species like Pinus radiata, an aggressive colonizer and shade-intolerant tree that has invaded successfully several native ecosystems of the southern hemisphere. In this study, we experimentally tested if the conditions of a successful seedling establishment P. radiata are fulfilled at the Coastal Maulino forest, an endemic fragmented forest of central Chile. Results demonstrated that seeds are dispersed into the native forests, however seedling establishment occurs only at the edges. We conclude that this exotic species is not invading native forests up to date. However, we suggest to conduct evaluations of seed rain and seedling establishment in the long term, in order to monitor the fate of this exotic species in fragmented native forest of Central Chile.     

Dynasore, a cell-permeable inhibitor of dynamin

Dynamin is essential for clathrin-dependent coated vesicle formation. It is required for membrane budding at a late stage during the transition from a fully formed pit to a pinched-off vesicle. Dynamin may also fulfill other roles during earlier stages of vesicle formation. We have screened about 16,000 small molecules and have identified 1, named here dynasore, that interferes in vitro with the GTPase activity of dynamin1, dynamin2, and Drp1, the mitochondrial dynamin, but not of other small GTPases. Dynasore acts as a potent inhibitor of endocytic pathways known to depend on dynamin by rapidly blocking coated vesicle formation within seconds of dynasore addition. Two types of coated pit intermediates accumulate during dynasore treatment, U-shaped, half formed pits and O-shaped, fully formed pits, captured while pinching off. Thus, dynamin acts at two steps during clathrin coat formation; GTP hydrolysis is probably needed at both steps.     

Low nitric oxide bioavailability contributes to the genesis of experimental cerebral malaria

The role of nitric oxide (NO) in the genesis of cerebral malaria is controversial. Most investigators propose that the unfortunate consequence of the high concentrations of NO produced to kill the parasite is the development of cerebral malaria. Here we have tested this high NO bioavailability hypothesis in the setting of experimental cerebral malaria (ECM), but find instead that low NO bioavailability contributes to the genesis of ECM. Specifically, mice deficient in vascular NO synthase showed parasitemia and mortality similar to that observed in control mice. Exogenous NO did not affect parasitemia but provided marked protection against ECM; in fact, mice treated with exogenous NO were clinically indistinguishable from uninfected mice at a stage when control infected mice were moribund. Administration of exogenous NO restored NO-mediated signaling in the brain, decreased proinflammatory biomarkers in the blood, and markedly reduced vascular leak and petechial hemorrhage into the brain. Low NO bioavailability in the vasculature during ECM was caused in part by an increase in NO-scavenging free hemoglobin in the blood, by hypoargininemia, and by low blood and erythrocyte nitrite concentrations. Exogenous NO inactivated NO-scavenging free hemoglobin in the plasma and restored nitrite to concentrations observed in uninfected mice. We therefore conclude that low rather than high NO bioavailability contributes to the genesis of ECM.     

Activation-induced deaminase: light and dark sides

Activation-induced deaminase (AID) is required for class switch recombination (CSR) and somatic hypermutation (SHM), which are responsible for secondary diversification of antibodies in germinal centers. AID initiates these processes by deamination of cytosines on the immunoglobulin (Ig) locus, a potentially mutagenic activity. AID expression is restricted to germinal-center B cells, but the mechanisms that regulate its target specificity are not completely understood. Here, we review the most recent findings on the regulation of AID targeting and discuss how AID activity on non-Ig genes is relevant to the generation of chromosome translocations and to lymphomagenesis.     

Equine cloning: in vitro and in vivo development of aggregated embryos

The production of cloned equine embryos remains highly inefficient. Embryo aggregation has not yet been tested in the equine, and it might represent an interesting strategy to improve embryo development. This study evaluated the effect of cloned embryo aggregation on in vitro and in vivo equine embryo development. Zona-free reconstructed embryos were individually cultured in microwells (nonaggregated group) or as 2- or 3-embryo aggregates (aggregated groups). For in vitro development, they were cultured until blastocyst stage and then either fixed for Oct-4 immunocytochemical staining or maintained in in vitro culture where blastocyst expansion was measured daily until Day 17 or the day on which they collapsed. For in vivo assays, Day 7-8 blastocysts were transferred to synchronized mares and resultant vesicles, and cloned embryos were measured by ultrasonography. Embryo aggregation improved blastocyst rates on a per well basis, and aggregation did not imply additional oocytes to obtain blastocysts. Embryo aggregation improved embryo quality, nevertheless it did not affect Day 8 and Day 16 blastocyst Oct-4 expression patterns. Equine cloned blastocysts expanded and increased their cell numbers when they were maintained in in vitro culture, describing a particular pattern of embryo growth that was unexpectedly independent of embryo aggregation, as all embryos reached similar size after Day 7. Early pregnancy rates were higher using blastocysts derived from aggregated embryos, and advanced pregnancies as live healthy foals also resulted from aggregated embryos. These results indicate that the strategy of aggregating embryos can improve their development, supporting the establishment of equine cloned pregnancies.     

A palaeoparasitological analysis of rodent coprolites from the Cueva Huenul 1 archaeological site in Patagonia (Argentina)

The aim of the present study was to examine the parasite fauna present in rodent coprolites collected from Cueva Huenul 1 (CH1), northern Neuquén (Patagonia, Argentina), an archaeological site that provides stratified sequences of archaeological and palaeontological remains dating from the Late Pleistocene/Early Holocene Transition to the Late Holocene period. Twenty rodent coprolites collected from different sedimentary units from the site, with ages ranging from 13.844 ± 75-1.416 ± 37 years BP, were examined for parasites. Each coprolite was processed as a whole: rehydrated, homogenised, spontaneously sedimented and examined using light microscopy. The coprolites and the eggs of any parasites present were described, measured and photographed. In all, 158 parasite eggs were found in 10 coprolites. The faeces were positive for Viscachataenia quadrata Denegri, Dopchiz, Elissondo & Beveridge and Monoecocestus sp. Beddard (Cestoda: Anoplocephalidae) and for Heteroxynema (Cavioxyura) viscaciae Sutton & Hugot (Nematoda: Oxyuridae). The coprolites examined were tentatively attributed to Lagidium viscacia Molina (Mammalia, Rodentia, Caviomorpha, Chinchillidae). The life cycles of these parasites are discussed.     

High mitochondrial mutation rates estimated from deep-rooting Costa Rican pedigrees

Estimates of mutation rates for the noncoding hypervariable Region I (HVR-I) of mitochondrial DNA vary widely, depending on whether they are inferred from phylogenies (assuming that molecular evolution is clock-like) or directly from pedigrees. All pedigree-based studies so far were conducted on populations of European origin. In this article, we analyzed 19 deep-rooting pedigrees in a population of mixed origin in Costa Rica. We calculated two estimates of the HVR-I mutation rate, one considering all apparent mutations, and one disregarding changes at sites known to be mutational hot spots and eliminating genealogy branches which might be suspected to include errors, or unrecognized adoptions along the female lines. At the end of this procedure, we still observed a mutation rate equal to 1.24 × 10(-6) , per site per year, i.e., at least threefold as high as estimates derived from phylogenies. Our results confirm that mutation rates observed in pedigrees are much higher than estimated assuming a neutral model of long-term HVRI evolution. We argue that until the cause of these discrepancies will be fully understood, both lower estimates (i.e., those derived from phylogenetic comparisons) and higher, direct estimates such as those obtained in this study, should be considered when modeling evolutionary and demographic processes.