The structure and evolution of the spider monkey delta-globin gene

We have isolated the delta-globin gene of the New-World spider monkey, Ateles geoffroyi, and compared its nucleotide sequence with those of other primate delta- and beta-globin genes. Among primate delta-globin genes, the rate of nonsynonymous substitutions is much less than the rate of synonymous substitutions. This suggests that primate delta- globin genes may remain under evolutionary conservation, perhaps because hemoglobin A2 has an as yet unknown physiological importance.      

Biochemical pathways in prokaryotes can be traced backward through evolutionary time

For the first time, a credible prokaryotic phylogenetic tree is being assembled by Woese and others using quantitative sequence analysis of oligonucleotides in the highly conservative rRNA. This provides an evolutionary scale against which the evolutionary steps that led to the arrangement and regulation of contemporary biochemical pathways can be measured. This paper presents an emerging evolutionary picture of aromatic amino acid biosynthesis within a large superfamily assemblage of prokaryotes that is sufficiently developed to illustrate a new perspective that will be applicable to many other biochemical pathways.      

The evolutionary history of the amylase multigene family in Drosophila pseudoobscura

In Drosophila pseudoobscura, the amylase (Amy) multigene family is contained within a series of inversions, or gene arrangements, on the third chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL) inversions are central to the phylogeny of arrangements, and have clusters of other arrangements derived from them. The gene arrangements belonging to each of these three clusters have a characteristic number of Amy genes, ranging from three in ST to two in SC to one in TL. This distribution pattern can reflect a history of either duplications or deletions, although the data available in the past did not permit a decision between these alternatives. We provide unambiguous evidence that three Amy genes were present before the divergence of the ST, SC, and TL arrangements. Thus, the current status of the Amy multigene family is the result of deletions in the TL and SC arrangements, which created three new pseudogenes: TL Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences revealed that, in the SC and ST arrangements, pseudogene evolution has been retarded, most likely due to the homogenization effect of gene conversion. Finally, by determining the original copy number, we have reconstructed the evolutionary history of the Amy multigene family and linked it with the evolution of the central gene arrangements.      

USE OF SENSORY EVALUATION FOR MEASURING DEODORIZING EFFECTS OF AN AIR CONDITIONER

The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R² values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures.     

Effects of taurine depletion on intrinsic contractility of rat ventricular papillary muscles

Contractile parameters in Krebs-Henseleit media containing various calcium concentrations were compared in left ventricular papillary muscles of two groups of rats: control and taurine depleted. All tests were carried out with the muscles at initial length, Lmax, the length that produced maximal active tension. From measurements of after- and un-loaded contractions, the velocity-tension curves and the derived maximum velocity of shortening were not different between the groups. Time to peak shortening and extent of shortening were not altered, while relaxation times and contraction duration were significantly prolonged for taurine-depleted muscles. Peak isometric tension and its rate of development were significantly reduced in taurine-depleted muscles compared with controls. Postrest (3 min) stimuli and paired stimuli (200-ms interval) evoked similar potentiated contractile responses in both groups, such that the ratio of their peak tensions remained unchanged. For taurine-depleted muscles the force-frequency relationship (a negative staircase) was parallel to, but lower than, control. These experiments suggest that taurine deficiency leads to reductions in action potential triggered calcium release from internal stores, and deficits in calcium sequestration. This may result from disfacilitation of calcium binding to the sarcoplasmic reticulum and other storage sites during taurine deficiency.     

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+/K+ homeostasis

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na⁺] and [K⁺] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na⁺‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K⁺] and the [Na⁺]/[K⁺] ratio in leaf and stem but not for [Na⁺] arising a disagreement with the corresponding RIL population. Their association with leaf [Na⁺] and salt tolerance in tomato is also discussed.     

Comparison of Photoacclimation in Twelve Freshwater Photoautotrophs (Chlorophyte,Bacillaryophyte, Cryptophyte and Cyanophyte) Isolated from a Natural Community

Different representative of algae and cyanobacteria were isolated from a freshwater habitat and cultivated in laboratory to compare their photoacclimation capacity when exposed to a wide range of light intensity and to understand if this factor may modify natural community dominance. All species successfully acclimated to all light intensities and the response of phytoplankton to increased light intensity was similar and included a decrease of most photosynthetic pigments accompanied by an increase in photoprotective pigment content relative to Chl a. Most species also decreased their light absorption efficiency on a biovolume basis. This decrease not only resulted in a lower fraction of energy absorbed by the cell, but also to a lower transfer of energy to PSII and PSI. Furthermore, energy funnelled to PSII or PSI was also rearranged in favour of PSII. High light acclimated organisms also corresponded to high non-photochemical quenching and photosynthetic electron transport reduction state and to a low Φ''_M. Thus photoacclimation processes work toward reducing the excitation pressure in high light environment through a reduction of light absorption efficiency, but also by lowering conversion efficiency. Interestingly, all species of our study followed that tendency despite being of different functional groups (colonial, flagellated, different sizes) and of different phylogeny demonstrating the great plasticity and adaptation ability of freshwater phytoplankton to their light environment. These adjustments may explain the decoupling between growth rate and photosynthesis observed above photosynthesis light saturation point for all species. Even if some species did reach higher growth rate in our conditions and thus, should dominate in natural environment with respect to light intensity, we cannot exclude that other environmental factors also influence the population dynamic and make the outcome harder to predict.     

The K+/H+ antiporter LeNHX2 increases salt tolerance by improving K+ homeostasis in transgenic tomato

The endosomal LeNHX2 ion transporter exchanges H⁺ with K⁺ and, to lesser extent, Na⁺. Here, we investigated the response to NaCl supply and K⁺ deprivation in transgenic tomato (Solanum lycopersicum L.) overexpressing LeNHX2 and show that transformed tomato plants grew better in saline conditions than untransformed controls, whereas in the absence of K⁺ the opposite was found. Analysis of mineral composition showed a higher K⁺ content in roots, shoots and xylem sap of transgenic plants and no differences in Na⁺ content between transgenic and untransformed plants grown either in the presence or the absence of 120 mm NaCl. Transgenic plants showed higher Na⁺/H⁺ and, above all, K⁺/H⁺ transport activity in root intracellular membrane vesicles. Under K⁺ limiting conditions, transgenic plants enhanced root expression of the high‐affinity K⁺ uptake system HAK5 compared to untransformed controls. Furthermore, tomato overexpressing LeNHX2 showed twofold higher K⁺ depletion rates and half cytosolic K⁺ activity than untransformed controls. Under NaCl stress, transgenic plants showed higher uptake velocity for K⁺ and lower cytosolic K⁺ activity than untransformed plants. These results indicate the fundamental role of K⁺ homeostasis in the better performance of LeNHX2 overexpressing tomato under NaCl stress.     

Bicarbonate infusion and pH clamp moderately reduce hyperventilation during ramp exercise in humans.

To test the hypothesis that the decrease in plasma pH contributes to the hyperventilation observed in humans in response to exercise at high workloads, five healthy male subjects performed a ramp exercise [maximal workload: 352 W (SD 35)] in a control situation and when arterialized plasma pH was maintained at the resting level (pH clamp) by intravenous infusion of sodium bicarbonate [129 mmol (SD 23), beginning at 59% maximal workload (SD 5)]. Bicarbonate infusion did not modify O(2) consumption (Vo(2)) but significantly (P < 0.05) increased arterial Pco(2), plasma bicarbonate concentration, and respiratory exchange ratio (P < 0.05). At the three highest workloads, pulmonary ventilation (Ve) and Ve/Vo(2) were approximately 5-10% lower (P < 0.05) when bicarbonate was infused than in the control situation, and hyperventilation was reduced by 15-30%. These data suggest that the decrease in plasma pH is one of the factors that contribute to the hyperventilation observed at high workloads.