Nuclear RNase MRP is required for correct processing of pre-5.8S rRNA in Saccharomyces cerevisiae.

RNase MRP is a site-specific ribonucleoprotein endoribonuclease that cleaves RNA from the mitochondrial origin of replication in a manner consistent with a role in priming leading-strand DNA synthesis. Despite the fact that the only known RNA substrate for this enzyme is complementary to mitochondrial DNA, the majority of the RNase MRP activity in a cell is found in the nucleus. The recent characterization of this activity in Saccharomyces cerevisiae and subsequent cloning of the gene coding for the RNA subunit of the yeast enzyme have enabled a genetic approach to the identification of a nuclear role for this ribonuclease. Since the gene for the RNA component of RNase MRP, NME1, is essential in yeast cells and RNase MRP in mammalian cells appears to be localized to nucleoli within the nucleus, we utilized both regulated expression and temperature-conditional mutations of NME1 to assay for a possible effect on rRNA processing. Depletion of the RNA component of the enzyme was accomplished by using the glucose-repressed GAL1 promoter. Shortly after the shift to glucose, the RNA component of the enzyme was found to be depleted severely, and rRNA processing was found to be normal at all sites except the B1 processing site. The B1 site, at the 5' end of the mature 5.8S rRNA, is actually composed of two cleavage sites 7 nucleotides apart. This cleavage normally generates two species of 5.8S rRNA at a ratio of 10:1 (small to large) in most eukaryotes. After RNase MRP depletion, yeast cells were found to have almost exclusively the larger species of 5.8S rRNA. In addition, an aberrant 309-nucleotide precursor that stretched from the A2 to E processing sites of rRNA accumulated in these cells. Temperature-conditional mutations in the RNase MRP RNA gene gave an identical phenotype.Translation in yeast cells depleted of the smaller 5.8S rRNA was found to remain robust, suggesting a possible function for two 5.8S rRNAs in the regulated translation of select messages. These results are consistent with RNase MRP playing a role in a late step of rRNA processing. The data also indicate a requirement for having the smaller form of 5.8S rRNA, and they argue for processing at the B1 position being composed of two separate cleavage events catalyzed by two different activities.     

Molecular evaluation of an Alu repeat including a polymorphic variable poly(dA) (AluVpA) in the vitamin D binding protein (DBP) gene

We investigated an Alu element at the end of intron 8 of the human vitamin D-binding protein (hDBP, group-specific component, GC) gene that shows a polymorphic poly(A) tail due to a variable number of tandem repeats (AluVpA) forming the 3 end of this member of the most abundant class of short interspersed repeated DNA element (SINES). The Alu element sequence in intron 8 of the GC gene was identical in all three common GC alleles (GC*1F, GC*1S, and GC*2) and could be classified as an Alu-Sa or Alu class-II sequence. The polymerase chain reaction was used to amplify selectively a fragment of about 200 bp containing the identified (TAAA)n repeat from genomic DNA of 188 unrelated human subjects. The size of the amplified products was determined by polyacrylamide gel electrophoresis. Four alleles (named GC-18*6, GC-I8*8, GC-I8*10, and GC-18*11) were found that differed in size by multiples of four nucleotides. The allele frequencies ranged from 0.0053 to 0.8511 and the observed heterozygosity was 26%. The stable inheritance of this polymorphic patterned poly(A) sequence was confirmed by a segregation study of a highly informative family with 19 members. Statistically significant linkage disequilibrium between the AluVpA and the GC isoelectric focusing (IEF) phenotypes was found in a sample of 188 unrelated individuals and delta values were calculated from the observed haplotype distribution.     

Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.     

Different roles of CheY1 and CheY2 in the chemotaxis of Rhizobium meliloti

Cells of Rhizobium meliloti swim by the unidirectional, clockwise rotation of their right-handed helical flagella and respond to tactic stimuli by modulating the flagellar rotary speed. We have shown that wild-type cells respond to the addition of proline, a strong chemoattractant, by a sustained increase in free-swimming speed (chemokinesis). We have examined the role of two response regulators, CheY1 and CheY2, and of CheA autokinase in the chemotaxis and chemokinesis of R. meliloti by comparing wild-type and mutant strains that carry deletions in the corresponding genes. Swarm tests, capillary assays, and computerized motion analysis revealed that (i) CheY2 alone mediates 60 to 70% of wild-type taxis, whereas CheY1 alone mediates no taxis, but is needed for the full tactic response; (ii) CheY2 is the main response regulator directing chemokinesis and smooth swimming in response to attractant, whereas CheY1 contributes little to chemokinesis, but interferes with smooth swimming; (iii) in a CheY2-overproducing strain, flagellar rotary speed increases upon addition and decreases upon removal of attractant; (iv) both CheY2 and CheY1 require phosphorylation by CheA for activity. We conclude that addition of attractant causes inhibition of CheA kinase and removal causes activation, and that consequent production of CheY1-P and CheY2-P acts to slow the flagellar motor. The action of the chief regulator, CheY2-P, on flagellar rotation is modulated by CheY1, probably by competition for phosphate from CheA.     

Analyse des procédures du test de Hühner ou test postcoïtal tel qu'il est pratiqué en région Alsace

The Huhner test is an easy, unpainful, unexpensive test which must be done first at the time of unfertility exploration. His clinical and prognosticated interest is much debated because many imprecisions in its realisation and interpretation occur. Our multicentric study proves that this test is quite standardized in his realisation but a loss of its efficacity appears by the fact of a inadequate collaboration between attending physicians and biologists.     

A GENETIC PERSPECTIVE OF MAMMALIAN VARIATION AND EVOLUTION IN THE INDONESIAN ARCHIPELAGO: BIOGEOGRAPHIC CORRELATES IN THE FRUIT BAT GENUS CYNOPTERUS

This study investigated allozyme and morphometric variability within the genus Cynopterus, with particular emphasis on C. nusatenggara, which is endemic to Wallacea, the area encompassing the Oriental-Australian biogeographic interface. The genetic distances between Cynopterus species are small by mammalian standards and suggest that this genus has undergone a recent series of speciation events. The genetic distance between populations of C. nusatenggara is strongly correlated with both the contemporary sea-crossing distance between islands and the estimated sea crossing at the time of the last Pleistocene glacial maximum, 18,000 b .p . This observation, together with low levels of population substructure within islands as shown by F-statistics, indicates that the sea is a primary and formidable barrier to gene exchange. The genetic distance and the great-circle geographical distance between the populations of C. nusatenggara are not correlated, although a principal-coordinates analysis of genetic distance reveals relationships between the populations that are similar to their geographical arrangement. A strong negative correlation exists between the level of heterozygosity within island populations of C. nusatenggara and the minimum sea-crossing distance to the nearest large source population. This is interpreted as reflecting an isolation effect of the sea, leading to reduced heterozygosity in populations that have larger sea barriers between them and the large source islands. Independently of this, heterozygosity is negatively associated with longitude, which in turn is associated with systematic changes in the environment such as a gradual decline in rainfall from west to east. The association between heterozygosity and longitude is interpreted as reflecting an association between genetic and environmental variance and supports the niche-width theory of genetic variance. Morphometric variability did not show any of the main effects demonstrated in the genetic data. Furthermore, there was no evidence that, at the level of individuals, genetic and morphometric variability were associated.     

Actions and interactions of growth hormone and insulin-like growth factor-II: body and organ growth of transgenic mice

To characterize long-term actions and interactions of growth hormone (GH) and insulin-like growth factor-II (IGF-II) on postnatal body and organ growth, hemizygous phosphoenolpyruvate carboxykinase (PEPCK)-human IGF-II transgenic mice were crossed with hemizygous PEPCK-bovine GH transgenic mice. The latter are characterized by two-fold increased serum levels of IGF-I and exhibit markedly increased body, skeletal and organ growth. Four different genetic groups were obtained: mice harbouring the IGF-II transgene (I), the bGH transgene (B), or both transgenes (IB), and non- transgenic controls (C). These groups of mice have previously been studied for circulating IGF-I levels (Wolf et al., 1995a), whereas the present study deals with body and organ growth. Growth curves (week 3 to 12) were estimated by regression with linear and quadratic components of age on body weight and exhibited significantly (p < 0.001) greater linear coefficients in B and IB than in I and C mice. The linear coefficients of male I and C mice were significantly (p < 0.001) greater than those of their female counterparts, whereas this sex-related difference was absent in the bGH transgenic groups. The weights of internal organs as well as the weights of abdominal fat, skin and carcass were recorded from 3.5- to 8- month-old mice. In addition, organ weight-to-body weight-ratios (relative organ weights) were calculated. Except for the weight of abdominal fat, absolute organ weights were as a rule significantly greater in B and IB than in I and C mice. IGF-II overproduction as a tendency increased the weights of kidneys, adrenal glands, pancreas and uterus both in the absence and presence of the bGH transgene. Analysis of relative organ weights demonstrated significant (p < 0.05) effects of elevated IGF- II on the relative growth of kidneys (males and females) and adrenal glands (females), confirming our previous report on organ growth of PEPCK-IGF-II transgenic mice. In females, IGF-II and GH overproduction were additive in stimulating the growth of spleen and uterus, providing evidence for tissue-specific postnatal growth promoting effects by IGF-II in the presence of elevated IGF-I     

Carbohydrate and the cytokine response to 2.5h of running

Nehlsen-Cannarella, S. L., O. R. Fagoaga, D. C. Nieman, D. A. Henson, D. E. Butterworth, R. L. Schmitt, E. M. Bailey, B. J. Warren, A. Utter, and J. M. Davis. Carbohydrate and the cytokineresponse to 2.5 h of running. J. Appl.Physiol. 82(5): 1662-1667, 1997.This randomized,double-blind, placebo-controlled study was designed to determine theinfluence of 6% carbohydrate (C) vs. placebo (P) beverage ingestion oncytokine responses (5 total samples over 9 h) to 2.5 h ofhigh-intensity running (76.7 ± 0.4% maximalO₂ uptake) by 30 experiencedmarathon runners. For interleukin-6 (IL-6), a difference in the patternof change between groups was found, highlighted by a greater increasein P vs. C immediately postrun (753 vs. 421%) and 1.5 h postrun (193 vs. 86%) [F(4,112) = 3.77, P = 0.006]. Forinterleukin-1-receptor antagonist (IL-1ra), a difference in the patternof change between groups was found, highlighted by a greater increasein P vs. C 1.5 h postrun (231 vs. 72%)[F(2,50) = 6.38, P = 0.003]. No significant interaction effects were seen for bioactive IL-6 or IL-1. The immediate postrun plasma glucose concentrations correlated negatively with those of plasma cortisol (r = 0.67, P < 0.001); postrun plasma cortisol (r = 0.70, P < 0.001) and IL-6 levels(r = 0.54, P = 0.003) correlated positively withlevels of IL-1ra. Taken together, the data indicate that carbohydrateingestion attenuates cytokine levels in the inflammatory cascade inresponse to heavy exertion.