The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence

The terrestrial water cycle links the soil and atmosphere moisture reservoirs through four fluxes: precipitation, evaporation, runoff, and atmospheric moisture convergence (net import of water vapor to balance runoff). Each of these processes is essential for sustaining human and ecosystem well-being. Predicting how the water cycle responds to changes in vegetation cover remains a challenge. Recently, changes in plant transpiration across the Amazon basin were shown to be associated disproportionately with changes in rainfall, suggesting that even small declines in transpiration (e.g., from deforestation) would lead to much larger declines in rainfall. Here, constraining these findings by the law of mass conservation, we show that in a sufficiently wet atmosphere, forest transpiration can control atmospheric moisture convergence such that increased transpiration enhances atmospheric moisture import and results in water yield. Conversely, in a sufficiently dry atmosphere increased transpiration reduces atmospheric moisture convergence and water yield. This previously unrecognized dichotomy can explain the otherwise mixed observations of how water yield responds to re-greening, as we illustrate with examples from China's Loess Plateau. Our analysis indicates that any additional precipitation recycling due to additional vegetation increases precipitation but decreases local water yield and steady-state runoff. Therefore, in the drier regions/periods and early stages of ecological restoration, the role of vegetation can be confined to precipitation recycling, while once a wetter stage is achieved, additional vegetation enhances atmospheric moisture convergence and water yield. Recent analyses indicate that the latter regime dominates the global response of the terrestrial water cycle to re-greening. Evaluating the transition between regimes, and recognizing the potential of vegetation for enhancing moisture convergence, are crucial for characterizing the consequences of deforestation as well as for motivating and guiding ecological restoration.     

Ectomycorrhizal diversity on the roots of Pitch pine (Pinus rigida Mill.) saplings as influenced by remediation and soil metal content

From 1913 to 1980, two zinc smelters in Palmerton, Pennsylvania, emitted large quantities of atmospheric pollutants nearly eliminating forests along a ridge above the town. In 2008, a remediation treatment was applied to the land above one of the smelters that included the planting of several locally adapted plant species. It also included mineral fertilization and mycorrhizal inoculation. One of the species, the Pitch pine (Pinus rigida, Mill.), is a native tree that is both tolerant of metalliferous soils and obligatorily ectomycorrhizal. This report summarizes the results of two observational studies conducted 5 years after the remediation treatment. The first study's objective was to compare ectomycorrhizal communities on treated Pitch pine saplings, with communities on naturally regenerating saplings in an adjacent non-remediated area. The second study's objective was to determine if the composition of the fungal communities on root tips of naturally regenerating Pitch pine saplings differed with distance from the smelters. Fungal community compositions were determined using internal transcribed spacer rRNA sequences. Comparisons of sequences from the remediated and non-remediated sites revealed that communities at the remediated sites had lower taxonomic diversity and were dominated by members of a genus in the remediation inoculant. The results of the smelter-proximity study indicated that although fungal diversity did not differ markedly with distance from the smelters, the relative abundances of some taxa were greater on saplings growing directly above the smelters, where the soils contained highest concentrations of zinc and cadmium.     

Compact structure of ribosomal chromatin in Xenopus laevis.

Micrococcal nuclease digestion was used as a tool to study the organization of the ribosomal chromatin in liver, blood and embryo cells of X. laevis. It was found that in liver and blood cells, ribosomal DNA is efficiently protected from nuclease attack in comparison to bulk chromatin. Although ribosomal chromatin is fragmented in a typical nucleosomal pattern, a considerable portion of ribosomal DNA retains a high molecular weight even after extensive digestion. A greater accessibility of the coding region in comparison to the non-coding spacer was found. In embryos, when ribosomal DNA is fully transcribed, these genes are even more highly protected than in adult tissues: in fact, the nucleosomal ladder can hardly be detected and rDNA is preserved in high molecular weight. Treatment of chromatin with 0.8 M NaCl abolishes the specific resistance of the ribosomal chromatin to digestion. The ribosomal chromatin, particularly in its active state, seems to be therefore tightly complexed with chromosomal proteins which protect its DNA from nuclease degradation.     

Spontaneous generation of adriamycin semiquinone radicals at physiologic pH.

Adriamycin semiquinone radicals are spontaneously generated by adriamycin solutions at physiologic pH. Rate of radical formation and equilibrium-state radical yield increase with increasing pH from 7.4 to 8.85. The radicals are oxygen sensitive, but the mechanism of radical formation is oxygen independent and associated with proton removal from the dihydroquinone of adriamycin. The less cardiotoxic and non-mutagenic (Ames test) anthracycline 5-iminodaunorubicin does not form semiquinone radicals spontaneously at physiologic pH.     

Three rare G-6-PD variants from Porto Alegre,Brazil

Summary Studies in 772 children and their mothers living in Porto Alegre, Brazil, disclosed three rare G-6-PD phenotypes. The first, observed in a dark mulatto, is probably identical to a variant previously found in Northeastern Brazil and was named Gd Minas Gerais-like; a white boy of German ancestry showed what seems to be Seattle-like; and a white man of Portuguese ancestry presented a previously undescribed variant that is being called Gd Porto Alegre. The allele responsible for Gd Minas Gerais may be more prevalent in Brazilian populations than was previously thought. Its estimated frequency in 214 black males from Porto Alegre is 0.005.     

Extreme divergence of a novel wheat thionin generated by a mutational burst specifically affecting the mature protein domain of the precursor.

A new type of neutral thionin (type V), specifically expressed in developing wheat endosperm, has been found to be encoded by a set of single-copy genes located in the long arms of chromosomes 1A, 1B and 1D, within less than 10,000 base-pairs of those corresponding to the highly basic type-I thionins. Divergence between types I and V has occurred through a process of accelerated evolution that has affected the amino acid sequence of the mature thionin but not the precursor domains corresponding to the N-terminal signal peptide and the long C-terminal acidic peptide. This process involved a deletion and a non-synonymous nucleotide substitution rate equal to the synonymous rate in the thionin sequence.     

Echocardiographic parameters and indices in the normal beagle dog.

M-mode and two-dimensional echocardiographic measurements were made from the right sternal border of 50 healthy Beagles (25 males and 25 females) approximately 7 months old. The dogs were conscious and standing during the investigation. The following parameters, in systole and diastole, were measured on the echocardiographic images: left ventricular posterior wall thickness (LVWT); intraventricular septum thickness (IST); left ventricular internal dimension (LVID); and circumference (LVC). Fractional shortening (FS) and ejection fraction (EF) were also calculated. Mean, standard deviation, range and coefficient of variation are reported for each echocardiographic parameter and for body weight. Males and females were considered separately and together. Each parameter was analysed statistically to check for differences between the sexes and for correlations with body weight. A statistically significant difference between the sexes was only observed for LVWT in systole and diastole. A linear regression with body weight was obtained only for LVID in systole and in diastole. The results show that morphofunctional cardiac homogeneity is independent of size in dogs of this breed and age.