Rodent hosts and flea vectors in Brazilian plague foci: a review

Plague, caused by the Yersinia pestis bacterium, has several foci scattered throughout a large area from the Brazilian territory that ranges from the Northeastern State of Ceará to the Southeastern State of Minas Gerais and another separated area at the State of Rio de Janeiro. This review gathers data from plague control and surveillance programs on the occurrence and geographic distribution of rodent hosts and flea vectors in the Brazilian plague areas during the period of from 1952 to 2019. Furthermore, we discuss how the interaction between Y. pestis and some rodent host species may play a role in the disease dynamics. The absence of human cases nowadays in Brazil does not mean that it was eradicated. The dynamics of plague in Brazil and in other countries where it was introduced during the 3rd pandemic are quite alike, alternating epidemics with decades of quiescence. Hence, it remains an important epidemic disease of global concern. The existence of a large animal reservoir and competent vectors demonstrate a need for continuous surveillance to prevent new outbreaks of this disease in humans.     

Speciation and calcium competition effects on cadmium sorption by sandy soil at various pHs

The effects of Ca competition, ionic strength, inorganic complexation and pH on cadmium adsorption by a sandy soil were studied. Sorption of Cd was measured using four different electrolytes CaCl₂, Ca(NO₃)₂, NaNO₃ and NaCl at a constant ionic strength (I) of 0.003 M at three different pHs, at variable Ca/Na ratio with a constant ionic strength of 0.03 and at variable ionic strengths between 0.003 and 0.3 M for two different pHs for Ca(NO₃)₂ and NaNO₃. The measured Cd sorption isotherms were non-linear. In the case of Cl as electrolyte anion, 13% of the Cd in solution is complexed at I= 0.003 (0.002 M Cl) and 91% of Cd is complexed at I= 0.3 (0.2 M Cl). If NO₃ is the anion, none of Cd is complexed at I= 0.003 and 11% at I= 0.3. The Cd complexes do not adsorb significantly. Calcium competition, at an ionic strength of 0.03, reduced the Cd adsorption by 60–80% compared with the case that Na is the cation. Increasing the ionic strength from 0.003 to 0.3 decreased Cd sorption by 60% for Ca(NO₃)₂ and 25% for NaNO₃ due to a decrease of the activity coefficient, increase of inorganic complexation and increase of Ca competition. A decrease of one pH unit reduces Cd sorption of about 75%. Sorption of Cd by soil could be described adequately with the three-species Freundlich (3SF) equation in which pH, complexation, Ca competition and ionic strength effects were taken into account.     

An ATP gate controls tubulin binding by the tethered head of kinesin-1

Kinesin-1 is a two-headed molecular motor that walks along microtubules, with each step gated by adenosine triphosphate (ATP) binding. Existing models for the gating mechanism propose a role for the microtubule lattice. We show that unpolymerized tubulin binds to kinesin-1, causing tubulin-activated release of adenosine diphosphate (ADP). With no added nucleotide, each kinesin-1 dimer binds one tubulin heterodimer. In adenylyl-imidodiphosphate (AMP-PNP), a nonhydrolyzable ATP analog, each kinesin-1 dimer binds two tubulin heterodimers. The data reveal an ATP gate that operates independently of the microtubule lattice, by ATP-dependent release of a steric or allosteric block on the tubulin binding site of the tethered kinesin-ADP head.     

SUSTAINABLE NITROGEN MANAGEMENT INDEX: DEFINITION,GLOBAL ASSESSMENT AND POTENTIAL IMPROVEMENTS

● A composite N management index is proposed to measure agriculture sustainability. ● Nitrogen management has been moving towards sustainability targets globally. ● The improvement was achieved mainly by yield increase, while Nitrogen Use Efficiency (NUE) stagnated. ● No country achieved both yield and NUE targets and spatial variation is large. ● Region-specific yield targets can be used to supplement the standard Sustainable Nitrogen Management Index (SNMI). To represent the sustainability of nitrogen management in the Sustainable Development Goals indicator framework, this paper proposes a sustainable nitrogen management index (SNMI). This index combines the performance in N crop yield and N use efficiency (NUE), thereby accounting for the need for both food production and environmental protection. Applying SNMI to countries around the world, the results showed improvement in the overall sustainability of crop N management over the past four decades, but this improvement has been mainly achieved by crop yield increase, while global NUE has improved only slightly. SNMI values vary largely among countries, and this variation has increased since the 1970s, implying different levels of success, even failure, in improving N management for countries around the world. In the standard SNMI assessment, the reference NUE was defined as 1.0 (considered an ideal NUE) and the reference yield was defined as 90 kg·ha⁻¹·yr⁻¹ N (considering a globally averaged yield target for meeting food demand in 2050). A sensitivity test that replaced the reference NUE of 1.0 with more realistic NUE targets of 0.8 or 0.9 showed overall reduction in SNMI values (i.e., improved performance), but little change in the ranking among countries. In another test that replaced the universal reference yield with region-specific attainable yield, SNMI values declined (i.e., improved performance) for most countries in Africa and West Asia, whereas they increased for many countries in Europe and South America. The index can be improved by further investigation of approaches for setting region-specific yield targets and high-quality data on crop yield potentials. Overall, SNMI offers promise for a simple and transparent approach to assess progress of countries toward sustainable N management with a single indicator.     

Human Influence on the Atmospheric Vertical Temperature Structure: Detection and Observations

Recent work suggests a discernible human influence on climate. This finding is supported, with less restrictive assumptions than those used in earlier studies, by a 1961 through 1995 data set of radiosonde observations and by ensembles of coupled atmosphere-ocean simulations forced with changes in greenhouse gases, tropospheric sulfate aerosols, and stratospheric ozone. On balance, agreement between the simulations and observations is best for a combination of greenhouse gas, aerosol, and ozone forcing. The uncertainties remaining are due to imperfect knowledge of radiative forcing, natural climate variability, and errors in observations and model response.     

Colonial growth of Neurospora. Sorbose and enzymes alter the composition of the cell wall and induce morphological changes

L-Sorbose, an agent which induces colonial growth in Neurospora crassa, also induces structural changes in the cell wall. Acid hydrolyzates of cell walls isolated from sorbose-grown (colonial) hyphae contain more glucosamine and less glucose than do hydrolyzates of cell walls obtained from normally growing hyphae. Snail digestive juice, an agent which effects a structural change in the cell wall of N. crassa by liberating from it large quantities of glucose, has been found to induce colonial growth.