A new species of Syphacia (Nematoda: Oxyuridae) from Calomys laucha (Rodentia: Cricetidae) in an agroecosystem of central Argentina

A new oxyurid nematode Syphacia hodarae n. sp. is described from the cecum and rectum of the cricetid rodent Calomys laucha Fischer, 1814 (Sigmodontinae, Phyllotini), captured in an agroecosystem of central Argentina. The new species is distinguished from other members of the genus mainly by the shape of the cephalic plate, presence of cervical alae in females, absence of lateral alae, and absence of deirids. Some characters are shared with Syphacia carlitosi, a parasite of Akodon azarae from the wetlands in Argentina. However, S. hodarae can be differentiated from this species by the absence of ornamentation on the accessory hook of the gubernaculum, length of spicule and gubernaculum, size of the eggs, and distance to the vulva from the anterior end. This is the first record of a Syphacia species from the tribe Phyllotini in Argentina, and the first time a Syphacia species is reported from C. laucha .     

Silencing of NHE-1 blunts the slow force response to myocardial stretch

Myocardial stretch induces a biphasic force response: a first abrupt increase followed by a slow force response (SFR), believed to be the in vitro manifestation of the Anrep effect. The SFR is due to an increase in Ca2? transient of unclear mechanism. We proposed that Na?/H? exchanger (NHE-1) activation is a key factor in determining the contractile response, but recent reports challenged our findings. We aimed to specifically test the role of the NHE-1 in the SFR. To this purpose small hairpin interference RNA capable of mediating specific NHE-1 knockdown was incorporated into a lentiviral vector (l-shNHE1) and injected into the left ventricular wall of Wistar rats. Injection of a lentiviral vector expressing a nonsilencing sequence (scramble) served as control. Myocardial NHE-1 protein expression and function (the latter evaluated by the recovery of pH(i) after an acidic load and the SFR) were evaluated. Animals transduced with l-shNHE1 showed reduced NHE-1 expression (45 ± 8% of controls; P < 0.05), and the presence of the lentivirus in the left ventricular myocardium, far from the site of injection, was evidenced by confocal microscopy. These findings correlated with depressed basal pH(i) recovery after acidosis [(max)dpH(i)/dt 0.055 ± 0.008 (scramble) vs. 0.009 ± 0.004 (l-shNHE1) pH units/min, P < 0.05], leftward shift of the relationship between J(H?) (H? efflux corrected by the intrinsic buffer capacity), and abolishment of SFR (124 ± 2 vs. 101 ± 2% of rapid phase; P < 0.05) despite preserved ERK1/2 phosphorylation [247 ± 12 (stretch) and 263 ± 23 (stretch l-shNHE1) % of control; P < 0.05 vs. nonstretched control], well-known NHE-1 activators. Our results provide strong evidence to propose NHE-1 activation as key factor in determining the SFR to stretch.     

Biogeography,habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data

Rivers and lake systems in the southern cone of South America have been widely influenced by historical glaciations, carrying important implications for the evolution of aquatic organisms, including prompting transitions between marine and freshwater habitats and by triggering hybridization among incipient species via waterway connectivity and stream capture events. Silverside fishes (Odontesthes) in the region comprise a radiation of 19 marine and freshwater species that have been hypothesized on the basis of morphological or mitochondrial DNA data to have either transitioned repeatedly into continental waters from the sea or colonized marine habitats following freshwater diversification. New double digest restriction‐site associated DNA data presented here provide a robust framework to investigate the biogeographical history of and habitat transitions in Odontesthes. We show that Odontesthes silversides originally diversified in the Pacific but independently colonized the Atlantic three times, producing three independent marine‐to‐freshwater transitions. Our results also indicate recent introgression of marine mitochondrial haplotypes into two freshwater clades, with more recurring instances of hybridization among Atlantic‐ versus Pacific‐slope species. In Pacific freshwater drainages, hybridization with a marine species appears to be geographically isolated and may be related to glaciation events. Substantial structural differences of estuarine gradients between these two geographical areas may have influenced the frequency, intensity and evolutionary effects of hybridization events.     

Antibacterial activity of Lemna minor extracts against Pseudomonas fluorescens and safety evaluation in a zebrafish model

The treatment of bacterial diseases in aquaculture is done using antibiotics, their applications has resulted in contamination and bacterial resistance. Natural extracts are a potential alternative as an antimicrobial, they have demonstrated effectiveness in their use aimed at treating conditions. The purpose of this study was to evaluate the antimicrobial activity of Lemna minor extracts against Pseudomonas fluorescens with different solvent for extraction. Methanol, chloroform and hexane were used. Subsequently, the safety assessment of the extracts in Danio rerio embryos and larvae was performed to validate as ecologically harmless. Antibacterial activity was detected in three extracts with significant differences (p = 0.001). Hexane extract had the highest antibacterial activity, followed by chloroform and methanol extracts. The three extracts have differences with respect to the control, between times and concentrations tested (p = 0.001). Minimum inhibitory concentration values (MIC) at 24 h methanolic extract ME 0.05 µg mL⁻¹. In embryos and larvae increased safety of the LC₅₀ methanolic extract was evidenced followed by the hexane and chloroform extract. No morphological or tissue changes were observed in embryos and larvae. The hexane extracts of L. minor had a greater bactericidal effect against P. fluorescens and are functional because of their antibacterial activity, but methanolic extract is more safety in embryos and larvae of D. rerio, making it a potential alternative for use in the treatment and control of septicemia in fish.     

Rhythmic Changes in Synapse Numbers in Drosophila melanogaster Motor Terminals

Previous studies have shown that the morphology of the neuromuscular junction of the flight motor neuron MN5 in Drosophila melanogaster undergoes daily rhythmical changes, with smaller synaptic boutons during the night, when the fly is resting, than during the day, when the fly is active. With electron microscopy and laser confocal microscopy, we searched for a rhythmic change in synapse numbers in this neuron, both under light:darkness (LD) cycles and constant darkness (DD). We expected the number of synapses to increase during the morning, when the fly has an intense phase of locomotion activity under LD and DD. Surprisingly, only our DD data were consistent with this hypothesis. In LD, we found more synapses at midnight than at midday. We propose that under LD conditions, there is a daily rhythm of formation of new synapses in the dark phase, when the fly is resting, and disassembly over the light phase, when the fly is active. Several parameters appeared to be light dependent, since they were affected differently under LD or DD. The great majority of boutons containing synapses had only one and very few had either two or more, with a 70∶25∶5 ratio (one, two and three or more synapses) in LD and 75∶20∶5 in DD. Given the maintenance of this proportion even when both bouton and synapse numbers changed with time, we suggest that there is a homeostatic mechanism regulating synapse distribution among MN5 boutons.     

Chromatin Relaxation-Mediated Induction of p19INK4d Increases the Ability of Cells to Repair Damaged DNA

The maintenance of genomic integrity is of main importance to the survival and health of organisms which are continuously exposed to genotoxic stress. Cells respond to DNA damage by activating survival pathways consisting of cell cycle checkpoints and repair mechanisms. However, the signal that triggers the DNA damage response is not necessarily a direct detection of the primary DNA lesion. In fact, chromatin defects may serve as initiating signals to activate those mechanisms. If the modulation of chromatin structure could initiate a checkpoint response in a direct manner, this supposes the existence of specific chromatin sensors. p19INK4d, a member of the INK4 cell cycle inhibitors, plays a crucial role in regulating genomic stability and cell viability by enhancing DNA repair. Its expression is induced in cells injured by one of several genotoxic treatments like cis-platin, UV light or neocarzinostatin. Nevertheless, when exogenous DNA damaged molecules are introduced into the cell, this induction is not observed. Here, we show that p19INK4d is enhanced after chromatin relaxation even in the absence of DNA damage. This induction was shown to depend upon ATM/ATR, Chk1/Chk2 and E2F activity, as is the case of p19INK4d induction by endogenous DNA damage. Interestingly, p19INK4d improves DNA repair when the genotoxic damage is caused in a relaxed-chromatin context. These results suggest that changes in chromatin structure, and not DNA damage itself, is the actual trigger of p19INK4d induction. We propose that, in addition to its role as a cell cycle inhibitor, p19INK4d could participate in a signaling network directed to detecting and eventually responding to chromatin anomalies.     

Punto de corte de espesor de tejido adiposo epicárdico para predecir síndrome metabólico en población venezolana

ObjectiveTo define an echocardiographically-assessed cut-off point for epicardial adipose tissue (EAT) thickness associated to metabolic syndrome (MS) components in Venezuelan subjects.MethodsFifty-two subjects aged 20-65 years diagnosed with MS according to International Diabetes Federation criteria and 45 sex- and age-matched controls were selected. Blood glucose and plasma lipids were tested; EAT thickness and left ventricular mass were measured by echocardiography.ResultsNo significant age and sex differences were found between the two groups. Body weight, body mass index, waist circumference, and systolic and diastolic blood pressure were significantly higher (P = .0001) in the MS group. This group showed significantly higher levels of fasting blood glucose (P = .0001), total cholesterol (P = .002), LDL-C (P = .007), non-HDL-C (P = .0001), triglycerides (P = .0001), Tg-HDL-C ratio (P = .0001), and lower HDL-C levels (P = .0001) as compared to the control group. EAT thickness (P = .0001) and left ventricular mass (P = .017) were significantly higher in the MS group. The ROC curve showed an AUC of 0.852 (P = .0001) with a power of the test of 0.99. A 5-mm EAT thickness showed a sensitivity of 84.62% (95% CI: 71.9-93.1) and a specificity of 71.11% (95% CI: 55.7-83.6) for predicting MS. The odds ratio of this population for experiencing MS due to an EAT ≥ 5 mm was 8.25 (95% CI: 3.15-21.56; P = .0001).ConclusionAn EAT value ≥ 5 mm has good sensitivity and specificity for predicting MS in the Venezuelan population.     

Foraging and vigilance time allocation in a guanaco (<Emphasis Type="Italic">Lama guanicoe</Emphasis>) population reintroduced in Quebrada del Condorito National Park (Córdoba,Argentina)

In reintroduction projects, ethology studies play a significant role in evaluating the behaviour of the individuals in habitats where they are reintroduced. We studied foraging and vigilance time allocation of a guanaco (Lama guanicoe) population reintroduced in Quebrada del Condorito National Park (QCNP), in the central mountains of Córdoba, Argentina. On average, individuals showed a higher proportion of time invested in vigilance and a lower proportion of time invested in foraging than a previously studied guanaco population belonging to the same ecological region as the source population, suggesting that at the time of this study, the reintroduced population was not fully adapted to the new habitat or suffered from an increased predation pressure. On the other hand, as expected for the species, throughout the study period, males allocated more time to vigilance than females, both sexes increasing vigilance during the reproductive period, and females increasing foraging time allocation during the post-reproductive period. Taking into account that further reinforcement to the existing population is planned, the present results may contribute to the elaboration of management strategies aimed at the successful establishment of guanaco in QCNP.