Last‐century changes of alpine grassland water‐use efficiency: a reconstruction through carbon isotope analysis of a time‐series of Capra ibex horns

The ecophysiological response of an alpine grassland to recent climate change and increasing atmospheric CO₂ concentration was investigated with a new strategy to go back in time: using a time‐series of Capra ibex horns as archives of the alpine grasslands' carbon isotope discrimination (¹³Δ). From the collection of the Natural History Museum of Bern, horns of 24 males from the population of the Augstmatthorn–Brienzer Rothorn mountains, Switzerland, were sampled covering the period from 1938 to 2006. Samples were taken from the beginning of each year‐ring of the horns, representing the beginning of the horn growth period, the spring. The horns' carbon ¹³C content (Δ¹³C) declined together with that of atmospheric CO₂ over the 69‐year period, but ¹³Δ increased slightly (+0.4‰), though significantly (P<0.05), over the observation period. Estimated intercellular CO₂ concentration increased (+56 μmol mol^?1) less than the atmospheric CO₂ concentration (+81 μmol mol^?1), so that intrinsic water‐use efficiency increased by 17.8% during the 69‐year period. However, the atmospheric evaporative demand at the site increased by approximately 0.1 kPa between 1955 and 2006, thus counteracting the improvement of intrinsic water‐use efficiency. As a result, instantaneous water‐use efficiency did not change. The observed changes in intrinsic water‐use efficiency were in the same range as those of trees (as reported by others), indicating that leaf‐level control of water‐use efficiency of grassland and forests followed the same principles. This is the first reconstruction of the water‐use efficiency response of a natural grassland ecosystem to last century CO₂ and climatic changes. The results indicate that the alpine grassland community has responded to climate change by improving the physiological control of carbon gain to water loss, following the increases in atmospheric CO₂ and evaporative demand. But, effective leaf‐level water‐use efficiency has remained unchanged.     

Unusual fast sedimenting mitochondria producing heavy DNA in the cells of aging coleoptiles of wheat seedlings

A fraction of unusual fast sedimenting (10 min at 600-1700g) particles with properties of mitochondria has been detected in wheat seedlings. This fraction conventionally called "heavy" mitochondria amounts (by protein) to about 40% of the total subcellular particle fraction sedimented by 10 min centrifugation at 17,000g. The specific feature of these "heavy" mitochondria in aging tissues is an ability to synthesize and even superproduce heavy (rho = 1.718 g/cm3) mitochondrial DNA (H-mtDNA). The share of "heavy" mitochondria sedimented in the interval between 1000 and 1700g and possessing the maximal H-mtDNA synthesis in aging coleoptiles is about 1.5-fold higher than that in young coleoptiles. Although "heavy" mitochondria are present in young plant organs, they seem to be unable to synthesize H-mtDNA; heavy mtDNA forms only in mitochondria of aging or old cells. Thus, aging in plants is accompanied by a change in population of mitochondria and appearance of the ability for selective H-mtDNA superproduction in a certain mitochondrial fraction. Mitochondria isolated from wheat coleoptiles are practically not stimulated by uncouplers. "Heavy" (600-1700g) and usual (4,300-17,400g) mitochondria are similar in respiration rates, cytochrome compositions, cytochrome c amount (per mg protein) and sensitivities to respiration inhibitors. However, "heavy" mitochondria contain (per mg protein) cytochromes b and aa3 by 10-20% and Ca2+ by 2-3-fold more than normal mitochondria. Ultrastructural analysis showed that the isolated fraction of fast sedimenting mitochondria consists of a suspension of closed membrane vesicles filled with cytoplasm and containing one or a few mitochondria. We observed similar structures in situ in vacuoles of parenchyma cells in the apical part of intact coleoptiles. The process of formation of such structures was detected by serial ultra-thin section analysis. It was shown that tonoplast protrudes into vacuoles, the separate mitochondria translocate into these protrusions, and then these structures separate. As a result, the suspended cytoplasmic bodies containing mitochondria appear in vacuoles. Appearance of these bodies containing mitochondria and, in particular, the superproduction of H-mtDNA in them correlate with processes of aging and cell transition to apoptosis.     

Effect of increased pressure of nitrogen on thermoregulation of mammals

Consumption of oxygen in rats was studied under conditions of the gas different ambient temperatures and pressure. A dependence was revealed between the neutral temperature and the high gas pressure. Mathematical model revealed an increase oxygen consumption at an increase gas pressure. The data suggest that the animal body temperature may be kept unaltered through an increased pressure of oxygen-nitrogen as a compensation of the heat transmission increased in an increased oxygen consumption.     

Nucleotide variation in the triosephosphate isomerase (Tpi) locus of Drosophila melanogaster and Drosophila simulans

DNA sequence variation in a 1.1-kb region including the coding portion of the Tpi locus was examined in 25 homozygous third-chromosome lines of Drosophila melanogaster, nine lines of Drosophila simulans, and one line of Drosophila yakuba. Our data show that the widespread allozyme polymorphism observed in cosmopolitan D. melanogaster is due to a glutamic acid substitution occurring in a phylogenetically conserved lysine that has been identified as part of the "hinged-lid" active site of the enzyme. This observation suggests that the replacement polymorphism may have important functional consequences. One replacement polymorphism was also observed in D. simulans, although its functional relevance is more difficult to assess, since it affects a site that is not strongly conserved. This amino acid change in D. simulans is associated with a single lineage possessing seven unique silent substitutions, which may be indicative of balancing selection or population subdivision. The absence of fixed amino acid differences between D. melanogaster and D. simulans and only a single difference with D. yakuba suggests that triose phosphate isomerase is under strong functional constraint. Silent variation is slightly higher for D. melanogaster than for D. simulans. Finally, we outline the general lack of evidence for old balanced polymorphisms at allozyme loci in D. melanogaster.      

The ability of rhesus macaques to perform elementary mathematical actions

Rhesus macaques were presented as an example with multitudes in the range from 1–2 to 5–6 “dots,” 10 mm in diameter, on the monitor screen. By consecutive discrete pressing the key with “+” symbol, the monkeys formed on the “field of counting” a randomized multitude equal to that presented as an example. O. Koehler’s hypothesis of connection between counting and thinking and the proximity of the consecutive effector form of counting to discrete nature of human language is discussed.     

Development of a quantitative PCR variant, and use of it for assessing gene expression

The data on the development of a quantitative PCR technique are presented, including the synthesis of modified primers, the choice of conditions for the removal of reaction-mixture components from the amplified DNA, and the colorimetric detection of the PCR product. The application of this technique to the assessment of the level of gene expression in nonculturable bacterial forms characterized by a drastically reduced metabolism is described.     

Screening of marine bacteria for fucoidan hydrolases

Twenty-five strains of epiphytic marine bacteria isolated from the brown algae Fucus evanescens and Chorda filum and fifty-three bacteria isolated from the sea cucumber Apostichopus japonicus were screened for fucoidanases using fucoidans prepared from the brown algae F. evanescens, Laminaria cichorioides, and L. japonica. Eighteen bacterial epiphytes and thirty-eight bacterial isolates from the sea cucumber were found to contain fucoidanases, which were able to hydrolyze either all of the fucoidans studied or some of them. Bacteria of the genera Cytophaga and Alteromonas/Pseudoalteromonas exhibited the highest fucoidanase activities, which, however, did not exceed the activity of fucoidanases from the already known sources.     

Antibiotic resistance and putative origin of Staphylococcus aureus and Klebsiella strains isolated from the children with intestinal dysbacteriosis

The results of the statistical treatment of data on the analyses of 766 children, the residents of Moscow, for dysbacteriosis are presented; of these children, 34 were aged up to 1 month and 732, from 1 month to 1 year. This study revealed that in the fist year of life in children with dysbacteriosis the dominating bacterial species were S. aureus, bacteria of the genus Klebsiella and fungi of the genus Candida. From the intestine of children aged up to 1 month S. aureus and Klebsiella were isolated more often than from children aged up to 1 year. The results of the study of antibioticograms demonstrated that 21.6% of S. aureus strains and 74.4% of Klebsiella strains were multiresistant to antibiotics. Taking into account the fact that multiresistance to antibiotics was characteristic of hospital strains, the suggestion was made that the isolated strains were of hospital origin and such strains could colonize the intestine of children in maternity hospitals.