Fine mapping of the <Emphasis Type="Italic">qCTS4</Emphasis> locus associated with seedling cold tolerance in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Rice seedlings are sensitive to low temperatures (≤15°C) and under prolonged or repeated exposure, yellowing and stunting are commonly observed. Damage to seedlings results in poor stand establishment and delayed maturation, which can cause significant reductions in yield. In general, japonica rice varieties exhibit more cold tolerance than indica varieties. Earlier genetic analysis of the California rice variety M202 revealed several quantitative trait loci (QTL) that contribute to its tolerance to low temperatures in comparison to the indica rice variety IR50. Among these QTL, qCTS4 is associated with tolerance to yellowing and stunting of rice seedlings and accounts for 40% of the phenotypic variation. Here we report on the fine mapping of qCTS4 to a 128 kb region of chromosome 4, which is highly suppressed for recombination in our mapping populations. Our results provide the necessary foundation for identifying the gene(s) underlying qCTS4 and the markers developed here may be used to introgress this region into indica varieties to improve seedling tolerance to low temperatures. The mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

β-N-Acetylhexosaminidase in Peripheral Blood Lymphocytes and Monocytes in the Different Forms and Stages of Multiple Sclerosis

Abstract: The activity of the acidic glycohydrolase β- N -acetylhexosaminidase, an enzyme system normally participating in the stepwise degradation of glycoproteins, glycolipids, and proteoglycans, appears to be modulated in lymphocytes and monocytes from peripheral blood of patients affected by multiple sclerosis during different stages of the disease. In particular, a significant decrease in this enzyme activity, compared with healthy subjects, was observed in patients affected by the relapsing-remitting form both in a stable clinical status and during a relapse as well as in patients with the progressive form. The decrease in total intracellular hexosaminidase activity in lymphomonocytes of multiple sclerosis patients was accompanied by an enrichment of this activity associated with the plasma membrane fraction as demonstrated by experiments of subcellular fractionation. The analysis carried out using two synthetic substrates, 4-methylumbelliferyl N -acetyl-β- d -glucosaminide and its sulfate derivative, enables us to demonstrate that this accumulation is mainly due to isoenzymes with a ββ structure, whereas lysosomal fractions confirmed the classical presence of both αβ and ββ forms (hexosaminidases A and B, respectively). This was particularly evident in the plasma membrane fraction from mononuclear cells of patients with a clinical exacerbation of the disease. Considered together, these observations provide additional insight into the abnormality of peripheral blood immune cells in multiple sclerosis and may contribute to the understanding of the basic mechanisms underlying the pathological events resulting in the demyelinating process.     

A topological classification of G-quadruplex structures

A topological classification of most quadruplex structures is proposed, based on two main characteristics: 1) the relative orientation of the strands and 2) the nature of the loops connecting the strands.     

Recovering full DNA barcodes from natural history collections of Tephritid fruitflies (Tephritidae, Diptera) using mini barcodes

The family of Tephritid fruit flies (Tephritidae, Diptera) is composed of more than 4000 species and more than 350 are of economic importance (EI). The Tephritid Barcoding Initiative (TBI) aims at obtaining DNA barcodes for all EI species and the majority of their congeners. Dry pinned specimens from natural history collections are an important resource for reference material, but were often collected decades ago. We observed a strong decrease in the success rate of obtaining a full COX1 DNA barcode (658 bp), with an increasing age of the specimens. Obtaining full barcodes is often not possible using standard protocols. We developed a universal Tephritid primer set for multiple overlapping mini-barcodes that allows reconstructing the full COX1 DNA barcode. These newly developed primers and the corresponding protocol will facilitate the utilization of the extensive natural history collection by the TBI consortium.     

Discrepancies between subgeneric classification and molecular phylogeny of Ceratitis (Diptera: Tephritidae), can the evolution of host use provide some clues?

Using molecular data from three protein encoding genes and 49 taxa (98 specimens from 20 African countries), we provide an extended phylogeny of Ceratitis and investigate the evolution of stenophagy across clades. Bayesian tree reconstructions support previously proposed monophyletic lineages (Pardalaspis, Pterandrus section A, Pterandrus section B+Ceratitis sensu stricto) and reveal the occurrence of two new monophyletic groups including Ceratalaspis/Hoplolophomyia (viz. Cl(A), and Cl(B)+H). The reconstruction of ancestral character states shows that stenophagy evolved repeatedly and independently in five different clades (Podocarpus, Solanum, Strychnos, Tabernaemontana and Vepris feeders). The evolution of feeding preferences is closely related to the phylogenetic patterns of Ceratalaspis/Hoplolophomyia whose sections include either polyphagous species (Cl(A)) or stenophagous taxa (Cl(B)+H) that are further subdivided in Vepris and Solanum feeders. The evolution of stenophagy in the genus Ceratits appears as the result of a process leading to the exploitation of "unconventional" fruits (viz. toxic and/or not fleshy) and involving either metabolic adaptation to toxic plant compounds and/or the capability of penetrating fruits with thick cuticles.     

Volume,pH, and ion-content regulation in human red cells: Analysis of transient behavior with an integrated model

Summary A basic mathematical model of human red cells is presented which integrates the charge and nonideal osmotic behavior of hemoglobin and of other impermeant cell solutes with the ion transport properties of the red cell membrane. The computing strategy was designed to predict the behavior of all measurable variables in time in ways that optimize comparison with experimentally determined behavior. The need and applications of such a model are illustrated in three separate examples covering different areas of experimentation in the physiology and pathophysiology of red cells.     

In vitro effects of beta-endorphin on testicular release of androgens in the lizard podarcis sicula raf

The effects of the proopiomelanocortin-derived opioid peptide, beta-endorphin (β-EP), and of the opioid antagonist, naloxone (NAL), on both basal and pituitary-stimulated androgen secretion from superfused quiescent and active testes were assessed in the adult lizard, Podarcis sicula. In the absence of the homologous pituitary, in vitro treatment with β-EP and/or NAL did not affect basal secretion of androgens from quiescent and active testes. Conversely, in the presence of the homologous pituitary, treatment with β-EP brought about a decrease in androgen secretion in active testes, but no effect on quiescent ones Naloxone counteracted the inhibitory effect of β-EP in active testes, and enhanced maximal pituitary-stimulated secretion of androgens in quiescent but not in active testes. The effects produces by β-endorphin and naloxone were reversible. These results suggest that, in this lizard, opioids might be involved in the control of androgen release. The lack of effect of β-EP and naloxone when added directly to the testes seems to suggest that the opioid agonist and antagonist act on androgen release by modulating pituitary gonadotrophin output. © 1996 Wiley-Liss, Inc.