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1.
S M Garn A R Frisancho A K Poznanski J Schweitzer M B McCann 《American journal of physical anthropology》1971,34(3):431-433
Fusion of the centers of the triquetral and lunate (the os lunato-triquetrum) was observed in 1.6% of 7,543 subjects primarily of African origin as compared with 0.1% of 11,663 persons of European origin. The fusion was twice as common in females as in males, multifactorial inheritance was suggested in the lineages studied, and a possible selective disadvantage was postulated after comparison with West African fusion frequencies. 相似文献
2.
S Gilgenkrantz J P Fryns P Droulle M Schweitzer B Chadefaux M Prieur 《Journal de génétique humaine》1987,35(1):51-61
In two cases, first interpreted as mosaic tetrasomy 21, the R banding and the gene dosage studies lead us to conclude to a mosaic tetrasomy 12 p. In Pallister mosaic syndrome and in Teschler-Nicola/Killian syndrome, the very similar clinical signs and the identical abnormal chromosome, missing in leucocytes, led us to conclude that Pallister and Teschler-Nicola/Killian syndrome, as well as mosaic tetrasomy 21 are one and the same syndrome tetrasomy 12 p. This tissue limited mosaic is probably more frequent than it is assumed. Prenatal diagnosis can be made since the supernumerary chromosome is found in amniocytes. The distinctive tissue distribution is probably a selective process due to cellular differentiation gene, CD9 (or Alb 6) located to 12 p. 相似文献
3.
4.
We have used slice preparation from newborn rats to study the development of the nucleus tractus solitarius neuronal network and brain intracellular phosphorus metabolites. As shown previously on adults, the newborn preparation retains local excitatory and inhibitory synaptic connections and enables study of intrinsic electrical properties in the nucleus tractus solitarius. Electrophysiological investigation of inhibitory synaptic transmission demonstrated a maturational step at days 4-6 after birth. Nuclear magnetic resonance spectroscopy of brain slices revealed a metabolic maturation between postnatal days 11 and 17. Results emphasize the differential maturation steps during the postnatal development of rat central nervous system. Possibly, Sudden Infant Death Syndrome may result from the abnormal timing in the occurrence of these steps. 相似文献
5.
Increasing specific leaf weight (SLW) may improve leaf apparent photosynthesis (AP) in soybean [Glycine max (L.) Merr.] but screening for SLW and AP is laborious. The Objectives of this study were (i) to determine the time course of SLW and chlorophyll concentration in experimental lines selected for differences in SLW and (ii) to evaluate the potential use of the Minolta 502 SPAD meter as a rapid estimator of SLW, AP and chlorophyll concentration in leaves of soybean. In 1991 and 1992, sixteen experimental lines representing extremes in SLW were grown at Urbana, IL, and West Lafayette, IN, with three replications at each location. SPAD values, SLW and AP were measured at the R2 (full flower), R4 (full pod) and R5 (beginning seed) growth stages. In 1992 SLW, SPAD values and chlorophyll concentration were measured weekly. Seasonal patterns of SPAD values, SLW, and chlorophyll concentration were very similar through R5. After R5, SLW continued to increase but SPAD values and chlorophyll concentration declined. SPAD values and SLW were highly correlated at the R2, R4 and R5 stages at both locations and in both years. Environmental conditions during this research were not suitable for maximum AP expression, which is likely why AP and SPAD values were correlated only at the R4 growth stage at Urbana in 1992. SPAD measurements were consistent across diverse environments and effectively separated the high SLW lines from the low SLW lines. Measuring with the Minolta 502 SPAD meter is rapid, simple and non-destructive and could be an alternative method for direct selection for SLW.Abbreviations AP-
leaf apparent photosynthesis
- CV-
coefficient of variation
- Rug-
leaf rugosity
- SLW-
specific leaf weight
- SPAD-L-
SPAD value of the most recently expanded terminal leaflet
- SPAD-P-
SPAD value of leaflet used to measure AP
- SPAD-S-
SPAD value of leaflets used to measure SLW
- SPAD-U-
SPAD value of the terminal leaflet one node above the most recently expanded terminal leaflet
The US Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged 相似文献
6.
Molecular basis of intercellular adhesion in the biofilm-forming Staphylococcus epidermidis 总被引:13,自引:3,他引:10
Christine Heilmann Oliver Schweitzer Christiane Gerke Nongnuch Vanittanakom Dietrich Mack Friedrich Götz 《Molecular microbiology》1996,20(5):1083-1091
The Staphylococcus epidermidis genes icaABC are involved in the synthesis of the polysaccharide intercellular adhesin (PIA), which is located mainly on the cell surface, as shown by immunofluorescence studies with PIA-specific antiserum. PIA was shown to be a linear β-1,6-linked glucosaminoglycan composed of at least 130 2-deoxy-2-amino-D-glucopyrano-syl residues of which 80–85% are N-acetylated, the rest being non-N-acetylated and positively charged. A transposon insertion in the icaABC gene cluster (ica, intercellular adhesion) led to the loss of several traits, such as the ability to form a biofilm on a polystyrene surface, cell aggregation, and PIA production. The mutant could be complemented by transformation with the IcaABC-carrying plasmid pCN27. Transfer of pCN27 into the heterologous host Staphylococcus carnosus led to the formation of large cell aggregates, the formation of a biofilm on a glass surface, and PIA expression. The nucleotide sequence of icaABC suggests that the three genes are organized in an operon and that they are co-transcribed from the mapped ica A promoter. Ica A contains four potential transmembrane helices, indicative of a membrane location. The deduced Ica A sequence shows similarity to those of polysaccharide-polymerizing enzymes, the most pronounced being with a Rhizobium meliloti N-acetylglucosaminyltransferase involved in lipo-chitin biosynthesis (22.5% overall identity and 37.4% overall similarity). This similarity suggests that Ica A has N-acetylglucosaminyltransferase activity in the formation 相似文献
7.
We studied nutrient-limitation of bacterioplankton growth in Lake Constance, a mesotrophic lake, between February and August in 1992. We amended 1-m filtrates with a single nutrient or nutrient combinations at 5 or 10 m final concentration, and the limiting nutrient or nutrient combination was inferred from the assay in which bacterial growth was most stimulated. The following nutrients were added individually or in combination: glucose, amino acids, peptone, and ammonium as C and N sources, and inorganic phosphate. From January until the beginning of the phytoplankton spring bloom in mid-April, C alone was growth-limiting. During the spring bloom a complex growth-limitation pattern occurred; first P was limiting, then for only 1 week C + N together, and thereafter P + C. During the clear-water phase with very low chlorophyll concentrations, P + C together limited bacterial growth again, interrupted by a period when C + N + P shortage caused a triple limitation. Later in the season, P + C were growth-limiting again. The growth efficiency (bacterial biomass produced/substrates used) on the basis of amino acid and carbohydrate used varied between 17 and 35%. The addition of various C and N sources indicated that the growth efficiency strongly depended on the quality of the substrates and the adaptation of the bacterial assemblages, for example, whether C and N originated from amino acids or glucose and ammonium. 相似文献
8.
Barry I. Schweitzer Kevin H. Gardner Gregory Tucker-Kellogg 《Journal of biomolecular NMR》1995,6(2):180-188
Summary While both 31P and 113Cd are present at locations of interest in many different macromolecular systems, heteronuclear-detected relaxation measurements on these nuclei have been restrained by limitations in either resolution or signal-to-noise ratio. We have developed hetero TOCSY-based methods to overcome both of these problems. Two-dimensional versions of these experiments were utilized to measure 31P T1 and T2 values in DNA oligonucleotides; the additional resolution offered by a second dimension allowed determination of these values for most of the 31P resonances in a DNA dodecamer. The results from the experiments indicated that there was little significant variation in T1 values for the different phosphates in the DNA dodecamer; however, the T2 values showed a clear pattern, with lower values in the interior of the sequence than at the ends of the helix. Furthermore, a significant correlation between 31P chemical shifts and T2 values was observed. One-dimensional, frequency-selective versions of these experiments were also developed for use on systems containing a smaller number of heteronuclear spins. These methods were applied to investigate the heteronuclear relaxation properties of 113Cd in 113Cd2LAC9(61), a Cys6Zn2 DNA-binding domain. Data from the experiments confirm biochemical evidence that more significant differences occur in the metal-protein interactions between the two metal-binding sites than has been previously identified for proteins containing this motif. 相似文献
9.
Calcium buffering in presynaptic nerve terminals. I. Evidence for involvement of a nonmitochondrial ATP-dependent sequestration mechanism 总被引:14,自引:1,他引:13
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M P Blaustein R W Ratzlaff N C Kendrick E S Schweitzer 《The Journal of general physiology》1978,72(1):15-41
A latent ATP-dependent Ca storage system is enriched in preparations of pinched-off presynaptic nerve terminals (synaptosomes), and is exposed when the terminals are disrupted by osmotic shock or saponin treatment. The data indicate that a fraction of the Ca uptake (measured with 45Ca) is associated with the intraterminal mitochondria; it is blocked by ruthenium red, by FCCP, and by azide + dinitrophenol + oligomycin. There is, however, a residual ATP-dependent Ca uptake that is insensitive to the aforementioned poisons; this (nonmitochondrial) Ca uptake is blocked by tetracaine, mersalyl and A-23187. Moreover, A-23187 rapidly releases previously accumulated Ca from these (nonmitochondrial) storage sites, whereas the Ca chelator, EGTA, does not. The proteolytic enzyme, trypsin, spares the mitochondria but inactivates the nonmitochondrial Ca uptake mechanism. Chemical measurements of total Ca indicate that the ATP-dependent Ca uptake at the nonmitochondrial sites involves the net transfer of Ca from medium to tissue fragments. This system can sequester Ca when the ambient-ionized Ca2+ concentration (buffered with EGTA) is less than 0.3 micrometer; brain mitochondria take up little Ca when the ionized Ca2+ level is this low. Preliminary subfractionation studies indicate that the nonmitochondrial Ca storage system does not sediment with synaptic vesicles. We propose that this Ca storage system, which has many properties comparable to those of skeletal muscle sarcoplasmic reticulum, may be associated with intraterminal smooth endoplasmic reticulum. This Ca-sequestering organelle may help to buffer intracellular Ca. 相似文献
10.
Bribosia E Bylemans D Huysmans S Schweitzer P Migon M van Impe G 《Communications in agricultural and applied biological sciences》2005,70(4):527-538
Elder shrubs (Sambucus nigra L.) were planted in an experimental apple orchard as bordering hedgerow with the objective of rearing syrphids (Diptera: Syrphidae) and consequently enhancing the biological control of the rosy apple aphid Dysaphis plantaginea (Passerini). The inoculative introduction of the specific elder aphid Aphis sambuci L. (Homoptera: Aphididae) in late March 2002 and again in 2003 led to the complete hedgerow turning into an early and productive alternative prey reservoir for indigenous syrphids. The species Scaeva pyrastri (L.), S. selenetica (Meigen), Syrphus ribesii (L.), S. vitripennis Meigen, Epistrophe eligans (Harris), E. nitidicollis (Meigen), Platycheirus scutatus (Meigen), Eupeodes corollae (F.), Meligramma triangulifera (Zetterstedt) and Episyrphus balteatus (De Geer) developed on the elder hedgerow during the spring 2002 taking advantage of the aphid infestation. The season 2003 was characterised by a quite different species abundance pattern as, contrary to the previous year when both monovoltine and polyvoltine species were equally represented, the monovoltine syrphids (Epistrophe spp.) represented the dominant group exploiting the elder aphids. A parallel analysis showed that the faeces of the first adult syrphids observed ovipositing on the elder hedgerow in spring contained digested pollen of mainly apple. Our observations indicate the possibility of establishing a local population of monovoltine syrphids in apple orchards by managing an aphid-infested elder hedgerow, without any additional pollen or nectar producing plants. 相似文献