Characterization of a new and highly distinguishable HLA-A allele in a Spanish family

Correspondence to: J. L. Vicario.     

The binding of zinc,but not cadmium,by phytic acid in roots of crop plants

Plant species adapted to soils enriched with heavy metals often accumulate these metals in their above or below ground organs. In this study, electron probe microanalysis of fractured, quench-frozen root specimens of common crop species shows that an appreciable quantity of Zn can be bound as Zn phytate (myo-inositolkis-hexaphosphate) within small vacuoles of cells in the root elongation zone of lucerne, soybean, lupins, tomato, rapeseed, cabbage, radish, maize and wheat exposed to high levels of Zn (80–300 M). Globular deposits of Zn phytate are most frequently observed in the endodermis of dicotyledonous species and in the pericycle of monocotyledonous species, but may also occur in the stele and inner cortex after prolonged exposure to toxic levels of Zn. The deposits could not be found in Zn-treated sunflower, field peas and Italian ryegrass. In three crop species, lucerne, soybean and maize, Zn-induced phytate globules were frequent, but exposure of roots to 30 M Cd did not induce the formation of Cd-containing globular deposits as observed inLemna minor (Van Steveninck et al., 1990a, 1992). Simultaneous Zn and Cd treatment induced the formation of Zn phytate globules as effectively as Zn alone, and Cd was not detected in the deposits.     

In vitro TRH release from hypothalamus slices varies during the diurnal cycle

We have previously described a daily rhythm in thyrotropin releasing hormone (TRH) and TRH mRNA in the rat hypothalamus. To determine whether TRH release fluctuates in a diurnal manner, we have measured basal and potassium stimulated release from hypothalamic slices, and compared it to release from olfactory bulb slices, during the diurnal cycle. Basal TRH release was higher at 7:00 h than at any other time (1:00, 13:00 or 19:00 h) in either hypothalamus or olfactory bulb. The ratio of stimulated over basal release was higher in the hypothalamus at 19:00 h, when TRH content was highest. Potassium stimulated TRH release from olfactory bulb was not different from basal release at any time. TRH release fluctuations were not due to a rhythm of extracellular inactivation: the activity of pyroglutamyl aminopeptidase II, an ectoenzyme responsible for TRH inactivation, was constant throughout the cycle. Our data demonstrate that diurnal variations of TRH release occur in vitro and that the enhanced responsiveness to potassium stimulation in hypothalamus is correlated with increased levels of peptide.     

Adenylate Uptake by Proplastids from Cultured Cells of Tobacco {Nicotiana tabacum L. cv. BY2) Indicates That an Adenylate Translocator is Present in All Types of Plastid

The presence of an adenylate translocator in the envelope membranesof proplastids isolated from the cultured cells of tobacco (Nicotianatabacum L. cv. BY2) was examined by means of transport experimentsusing the silicone oil filtering centrifugation technique. Itwas observed that proplastids can import [³H]ATP, [³H]ADP, [³H]AMPand less specifically ADP-[¹⁴C]Glc which can eventually be usedfor starch biosynthesis. The effects of specific inhibitorsof the mitochondrial adenylate translocator, i.e. atractyloside,bongkrekic acid and carboxyatractyloside were tested. Similarto the case of amyloplasts isolated from the cultured cellsof sycamore and chloroplasts isolated from spinach leaves, onlyATP and ADP-Glc uptake were shown to be partially inhibitedby carboxyatractyloside. On the other hand, neither atractylosidenor bongkrekic acid exerted a significant inhibitory effecton adenylate uptake. (Received August 8, 1992; Accepted November 26, 1992)     

Wind chill factor applied to Patagonian climatology

The wind cooling effect determines wind chill equivalent-temperatures, which may be rather different to actual temperature. In a windy region such as Patagonia, this difference may reach a magnitude and persistence to become an important bioclimatic element. This paper quantifies the wind cooling effect in Patagonia by the presentation of equivalent isotherms as an adaptation of the usual isotherm maps to the regional bioclimatic environment. It is concluded that due to seasonal variations in wind speed, the annual equivalent temperature range is smaller than the actual temperature range, thus increasing oceanic features, from a thermal viewpoint, of the Patagonian climate.«Les vents que chassent, à travers une échancrure de la Cordillère des Andes, les hautes pressions du Pacifique, s'étranglent et s'accelèrent dans un étroit couloir de cent kilomètres de front, en direction de l'Atlantique, et raclent tout sur leur passage».Antoine de Saint-Exupéry «Un sens à la vie» (1956)     

Soils in warmer and less developed countries have less micronutrients globally

Soil micronutrients are capital for the delivery of ecosystem functioning and food provision worldwide. Yet, despite their importance, the global biogeography and ecological drivers of soil micronutrients remain virtually unknown, limiting our capacity to anticipate abrupt unexpected changes in soil micronutrients in the face of climate change. Here, we analyzed >1300 topsoil samples to examine the global distribution of six metallic micronutrients (Cu, Fe, Mn, Zn, Co and Ni) across all continents, climates and vegetation types. We found that warmer arid and tropical ecosystems, present in the least developed countries, sustain the lowest contents of multiple soil micronutrients. We further provide evidence that temperature increases may potentially result in abrupt and simultaneous reductions in the content of multiple soil micronutrients when a temperature threshold of 12–14°C is crossed, which may be occurring on 3% of the planet over the next century. Altogether, our findings provide fundamental understanding of the global distribution of soil micronutrients, with direct implications for the maintenance of ecosystem functioning, rangeland management and food production in the warmest and poorest regions of the planet.     

Low species turnover of upland Amazonian birds in the absence of physical barriers

Aim

One of the oldest and most powerful ways for ecologists to explain distinct biological communities is to invoke underlying environmental differences. But in hyper-diverse systems, which often display high species richness and low species abundance, these sorts of community comparisons are especially challenging. The classic view for Amazonian birds posits that riverine barriers and habitat specialization determine local and regional community composition. We test the tacit, complementary assumption that similar bird communities should therefore permeate uniform habitat between major rivers, regardless of distance.

Location

Upland (terra firme) rainforests of central Amazonia.

Methods

We conducted intensive whole-community surveys of birds in three pairs of 100-ha plots, separated by 40–60 km. We then used dissimilarity indices, cluster analysis, and ordination to characterize differences among the six avian communities.

Results

In all, we detected 244 forest-dependent birds, with an average of 190 species (78%) per plot. Species turnover was negligible, no unique indicator species were found among plot pairs, and all documented species were already known from a complete inventory at one of the three sites.

Main Conclusions

Our study corroborates the classic biogeographical pattern and suggests that turnover contributes little to regional avian diversity within upland forests. Using a grain size of 100 ha, this implies that upland birds perceive the environment as uniform, at least over distances of ~60 km. Therefore, to maximize both local species richness and population persistence, our findings support the conservation of very large tracts of upland rainforest. Our analyses also revealed that the avifauna at Reserva Ducke, encroached by urban sprawl from the city of Manaus, shows the hallmarks of a disturbed community, with fewer vulnerable insectivores. This defaunation signals that even an enormous preserve (10 × 10 km) in lowland Amazonia is not insulated from anthropogenic degradation within the surrounding landscape.     

An unethical trial and the politicization of the COVID-19 pandemic in Brazil: The case of Prevent Senior

The Brazilian Federal Senate created a Parliamentary Inquiry Commission (CPI) to investigate the Bolsonaro government's irregularities in the management of the COVID-19 pandemic. One of the cases that drew attention was the research conducted by Prevent Senior, a private health insurance company, on the early treatment of COVID-19. The article analyzes the scientific validity of the research and the ethical problems related to its implementation. It is based on analysis of Prevent Senior's report of the clinical study, the Brazilian and USA clinical trial registries, the Senate's CPI report, and on the information reported by the media. This case of scientific fraud and political-ideological bias exemplifies how Prevent Senior, using a questionable protocol to enhance its reputation and gain government support, was instrumental in building the “early treatment” narrative for COVID-19, and shows how it served as a basis for a government public policy that promoted the use of ineffective drugs.     

Selection of synthetic proteins to modulate the human frataxin function

Frataxin is a kinetic activator of the mitochondrial supercomplex for iron-sulfur cluster assembly. Low frataxin expression or a decrease in its functionality results in Friedreich's Ataxia (FRDA). With the aim of creating new molecular tools to study this metabolic pathway, and ultimately, to explore new therapeutic strategies, we have investigated the possibility of obtaining small proteins exhibiting a high affinity for frataxin. In this study, we applied the ribosome display approach, using human frataxin as the target. We focused on Affi_224, one of the proteins that we were able to select after five rounds of selection. We have studied the interaction between both proteins and discussed some applications of this specific molecular tutor, concerning the modulation of the supercomplex activity. Affi_224 and frataxin showed a K_D value in the nanomolar range, as judged by surface plasmon resonance analysis. Most likely, it binds to the frataxin acidic ridge, as suggested by the analysis of chemical shift perturbations (nuclear magnetic resonance) and computational simulations. Affi_224 was able to increase Cys NFS1 desulfurase activation exerted by the FRDA frataxin variant G130V. Importantly, Affi_224 interacts with frataxin in a human cellular model. Our results suggest quaternary addition may be a new tool to modulate frataxin function in vivo. Nevertheless, more functional experiments under physiological conditions should be carried out to evaluate Affi_224 effectiveness in FRDA cell models.