Proximity to forest edge does not affect crop production despite pollen limitation

A decline in pollination function has been linked to agriculture expansion and intensification. In northwest Argentina, pollinator visits to grapefruit, a self-compatible but pollinator-dependent crop, decline by approximately 50% at 1km from forest edges. We evaluated whether this decrease in visitation also reduces the pollination service in this crop. We analysed the quantity and quality of pollen deposited on stigmas, and associated limitation of fruit production at increasing distances (edge: 10, 100, 500 and 1000m) from the remnants of Yungas forest. We also examined the quantitative and qualitative efficiency of honeybees as pollen vectors. Pollen receipt and pollen tubes in styles decreased with increasing distance from forest edge; however, this decline did not affect fruit production. Supplementation of natural pollen with self- and cross-pollen revealed that both pollen quantity and quality limited fruit production. Despite pollen limitation, honeybees cannot raise fruit production because they often do not deposit sufficient high-quality pollen per visit to elicit fruit development. However, declines in visitation frequency well below seven visits during a flower's lifespan could decrease production beyond current yields. In this context, the preservation of forest remnants, which act as pollinator sources, could contribute to resilience in crop production. Like wild plants, pollen limitation of the yield among animal-pollinated crops may be common and indicative not only of pollinator scarcity, but also of poor pollination quality, whereby pollinator efficiency, rather than just abundance, can play a broader role than previously appreciated.     

Paleoparasitological records in a canid coprolite from Patagonia, Argentina

In this note, organic remains identified as a canid coprolite were examined. The material was dated at 6540 +/- 110 B.P.; it was collected in the Perito Moreno National Park, Santa Cruz, Argentina. Paleoparasitological analysis was performed following standard procedures. Coprolite fragments were rehydrated in a trisodium phosphate aqueous solution and subjected to spontaneous sedimentation for microscope analysis. Eggs of nematodes identified as Trichuris sp., Capillaria sp., Uncinaria sp., and an ascaridid (probably Toxascaris sp.) or spirurids (presumably Physaloptera sp.), plus a cestode (Anoplocephalidae), presumably Moniezia sp., were found.     

Denoising of surface EMG with a modified Wiener filtering approach

The correlation dimension D₂ yields good results in several biomedical fields. Nonetheless, no clinical application to electromyography has been developed yet. One reason is the high electromagnetic noise typical of clinical environments. This noise is characterized by sharp spectral lines of variable intensity and frequency. The filtering techniques commonly implemented in electromyographs can efficiently deal with this kind of noise. They allow a safe estimate of linear quantities like the root mean square (r.m.s.) or the median frequency (MF). Their performance is not as good for nonlinear purposes. The filters may modify the nonlinear properties of the signal, leading to unacceptable estimates of D₂. We consider a simple procedure based on a modified Wiener filter. Its performance is compared with that from a bandpass followed by multiple notch filters. Our procedure leads to a gain in precision and accuracy when estimating D₂. The two filtering approaches are also compared with respect to a biomedical application proposed by others. Using data from 12 healthy subjects, the modified Wiener procedure raises the percentage of successes in that application from 17% to 83%. New experimental data suggest D₂ carries information not carried by r.m.s. or MF.     

Statistical characterization of piezoelectric coefficient d23 in cow bone.

In a newly developed, highly sensitive dilatometer we applied pulsatile electric fields to five dry bone samples cut from mid-tibial sections within a 90 degrees angle from the rear to front axis. Samples of five cows were studied. We measured the piezoelectric coefficient d23 establishing its mean and confidence interval for the first time. An analysis of variance detected a significant difference of the coefficient between animals (P < 0.01) but not between samples (P = 0.5). Between animals the coefficient ranged from 9.6 x 10(-14) to 27.1 x 10(-14) C/N. It can no longer be assumed that piezoelectricity is an inherent property of bone, constant between animals.     

Expansion of mesenchymal stem cells isolated from pediatric and adult donor bone marrow

The enormous plasticity of mesenchymal stem cells (MSCs) suggests an improvement of a standard protocol of isolation and ex vivo expansion for experimental and clinical use. We isolated and expanded MSCs from bone marrow (BM) of pediatric and young adult donors, to analyze the growth kinetic, immunophenotype, telomere length, karyotype during ex vivo expansion. Seventeen BM samples were collected from young adult donors and 8 from pediatric donors. MSCs isolated from two groups showed no morphological differences while their cell growth was strictly related to the donor's age. The MSCs isolated from pediatric donors reached a cumulative PD almost twice as high as MSCs isolated from young adult donors after 112 days (10.2 +/- 1.9 versus 5.5 +/- 3.7). Furthermore, we analyzed the modulation of antigen expression in the MSCs isolated from two groups until 10th passage (77 days) and there was no significant difference between the modulation of antigen expression. In particular, at the first passage, MSCs showed a low contamination of hemopoietic cells which became insignificant in the following passages. There was a high expression of CD90, CD29, CD44 and CD105 and variable and moderate expression of CD166 and CD106 at the start of MSC culture and at each passage during expansion. No chromosomal alteration or evidence of cellular senescence were observed in all analyzed samples. All these data suggest that MSCs can be isolated and expanded from most healthy donors, providing for an autologous source of stem cells.     

Contrasting climate influences on Nothofagus pumilio establishment along elevational gradients

Predicted warmer temperatures and more frequent extreme climatic events in the southern Andes may affect the dynamics of the Patagonian forests. These environmental changes may differentially alter the probability of Nothofagus pumilio establishment across its altitudinal range of distribution. We monitored fruit fall, seedling emergence and survival at altitudinal distribution range of N. pumilio forests in Santa Cruz (49°22′ S—72°56′ W), Argentina. Fruit fall, seedling emergence and survival were tested in relation to drought, based on the SPEI (Standardized Precipitation Evapotranspiration Index), interacting with elevation. Fruit fall was consistently higher at low elevation and the abundance of fruits was not affected by drought intensity. Density of new-born seedlings was?~?9 to 24 times lower at low- than at high-elevation plots in our first observations (2014 and 2016), characterized by warm-dry climatic conditions in spring-early summers. In contrast, seedling abundance was?~?1.5 times larger at low elevations during relatively cold-wet growing seasons. Survival probability was explained by the interaction between SPEI and elevation. At low elevation and in dry periods, survival probability was lower (CI 54–72%) than in wet periods (CI 68–84%) but at high elevation similar survival was registered even with positive or negative SPEI values. Our results show interacting effects of elevation and drought on tree establishment at the elevation limits, with positive and negative drought effects at high and low elevations, respectively. Predicted increase of extreme drought events during the XXI century could be detrimental for N. pumilio establishment at dry, low-elevation forests.