RFLP-based maps of the homoeologous group-6 chromosomes of wheat and their application in the tagging of Pm12, a powdery mildew resistance gene transferred from Aegilops speltoides to wheat

Genetic maps of the homoeologous group-6 chromosomes of bread wheat, Triticum aestivum, have been constructed spanning 103 cM on 6A, 90 cM on 6B and 124 cM on 6D. These maps were transferred to a Chinese Spring (CS) x line #31 cross to locate a dominant powdery mildew resistance gene, Pm12, introgressed into line #31 from Aegilops speltoides. Pm12 was shown to lie on the short arm of translocation chromosome 6BS-6SS.6SL in line #31, but could not be mapped more precisely due to the lack of recombination between the 6S Ae. speltoides segment and chromosome 6B. Possible strategies to reduce the size of the alien segment, which probably encompasses the complete long arm and more than 82% of the short arm of chromosome 6B, are discussed.     

Analysis of wild-type and mutant p21WAF-1 gene activities.

The p21WAF-1 gene is positively regulated by the wild-type p53 protein. p21WAF-1 has been shown to interact with several cyclin-dependent kinase complexes and block the activity of G1 cyclin-dependent kinases (cdks). Mutational analysis with the p21WAF-1 gene localized a site, at amino acid residues 21 and 24 in the amino terminus of the protein, for p21WAF-1 binding to cyclins D and E. This region of the protein is conserved (residues 21 to 26) in other p21WAF-1 family members, p27kip-1 and p57kip-2. The same p21WAF-121,24 mutant also fails to bind to cyclin D1-cdk 4 or cyclin E-cdk 2 complexes in vitro, suggesting that amino acid residues 21 and 24 are important for p21WAF-1-cdk-cyclin trimeric complex interactions. The p21WAF-1 wild-type protein will suppress tumor cell growth in culture while p21WAF-1 mutant proteins with defects in residues 21 and 24 fail to suppress tumor cell growth. The overexpression of cyclin D or E in these cells will partially overcome the growth suppression of wild-type p21WAF-1 protein in cells. These results provide evidence that p21WAF-1 acts through cyclin D1-cdk4 and cyclin E-cdk2 complexes in vivo to induce the growth suppression. The p21WAF-1 binding sites for cyclins (residues 21 to 26), cdk2 (residues 49 to 71), and proliferating-cell nuclear antigen (residues 124 to 164) have all been mapped to discrete sites on the protein.     

On the existence of stable pairing distributions

We formulate and analyze pair-formation models for multiple groups with general pairing rates and arbitrary mixing probabilities. Under the assumption of constant recruitment rates and equal average duration of all types of partnerships, we have shown that the dynamics are relatively simple because of the monotonicity properties of the dynamical system associated with the pairing/mixing of heterogeneous populations of male and female individuals. In fact, we have shown that the corresponding asymptotic stable paired distribution is given precisely by the asymptotic values of the matrices that prescribe the mixing/contact structure. In other words, if the sizes of the mixing subpopulations of males and females are asymptotically constant and if the average durations of partnerships are about the same regardless of type, then the matrices that describe the mixing between subpopulations also characterize the distribution of paired types. Alternatively, if the distribution of the average duration of relationships between individuals has a large variance then it may be impossible to detect any relationship between the mixing/contact structure and the observed distribution of paired types. The study of models with constant per-capita recruitment rates give rise to homogeneous systems of degree one. The analysis of the dynamics of pairs for models with exponentially growing populations of singles is complicated. So far, we are only able to classify the stability of all non-strictly positive boundary exponential solutions. From our incomplete analysis, it is not possible to detect necessary and sufficient conditions for the existence and stability of strictly interior exponential solutions. We cannot rule out the possibility of oscillations. The mathematical problems associated with the stability of exponential solutions of dynamical systems of degree one are of relevance in demography, epidemiology, and population dynamics.On leave from University of Alabama in Huntsville     

人粒细胞集落刺激因子（hG－CSF）cDNA3′－UTR对其表达的影响

利用人粒细胞集落刺激因子（ｈＧ－ＣＳＦ）ｃＤＮＡ３′端非翻译区（３′－ＵＴＲ）中存在的ＤｒａⅠ酶切位点,通过部分酶切与完全酶切,删除３′－ＵＴＲ不同长度,构建了四种ｈＧ－ＣＳＦｃＤＮＡ瞬时重组表达质粒。转染ＣＯＳ－７细胞后,生物活性测定结果提示,ｈＧ－ＣＳＦｃＤＮＡ３′－ＵＴＲ对其表达起负调控作用,其关键性序列位于紧接终止密码子ＴＧＡ下游的６５ｂｐ范围内,３′－ＵＴＲ对ｈＧ－ＣＳＦｃＤＮＡ表达的影响与转录水平的差别有一定关系。     

Epipolarization Microscopic Immunogold Assay: a Combination of Immunogold Silver Staining, Enzyme-Linked-Immunosorbent Assay and Epipolarization Microscopy

We describe a new immunoassay which combines an immunosorbent assay, Immunogold silver staining and epipolarization microscopy. Our new assay procedure features multiple samples on a single microscope slide, and high sensitivity of epipolarization microscope for detection of silver-enhanced colloidal gold as a final immunoassay product. We call the new immunoassay “on slide immunogold assay” (OSIGA). This new method uses biotinylated antibody and streptavidin-gold reaction with silver enhancement technique. With OSIGA it is possible to investigate 30 samples on a single microscopic slide. Our preliminary studies used 10-20 μ1 samples and detected nanogram quantities of a standardized protein solution. Unlike enzyme linked immunosorbent assay (ELISA), which has a limited time for reading the final color products, the OSIGA specimens can be dried or resin mounted for longer storage and future reference.     

Physiological Elevations of Glucocorticoids Potentiate Glutamate Accumulation in the Hippocampus

Abstract: Glucocorticoids (GCs) are secreted during stress and can damage the hippocampus over the course of aging and impair the capacity of hippocampal neurons to survive excitotoxic insults. Using microdialysis, we have previously observed that GCs augment the extracellular accumulation of glutamate and aspartate in the hippocampus following kainic acid-induced seizures. In that study, adrenalectomized rats maintained on minimal GC concentrations were compared with those exposed to GCs elevated to near-pharmacological levels. We wished to gain insight into the physiological relevance of these observations. Thus, we have examined the effects of GCs over the normal physiological range on glutamate and aspartate profiles; this was done by implanting adrenalectomized rats with GC-secreting pellets, which produce stable and controllable circulating GC concentrations. We observe that incremental increases in GC concentrations cause incremental increases in glutamate accumulation before the kainic acid insult, as well as in the magnitude of the glutamate response to kainic acid. Elevating GC concentrations from the circadian trough to peak doubled cumulative glutamate accumulation, whereas a rise into the stress range caused a fourfold increase in accumulation. Similar, although smaller, effects also occurred with aspartate accumulation (as well as with taurine but not glutamine accumulation). These data show that the highly elevated GC concentrations that accompany neurological insults such as seizure or hypoxia-ischemia will greatly exacerbate the glutamate accumulation at that time. Furthermore, stress levels of GCs augmented glutamate accumulation even in the absence of an excitotoxic insult, perhaps explaining how sustained stress itself damages the hippocampus. Finally, even the moderately ?levated basal GC concentrations that typically occur in aged rats augmented glutamate accumulation, perhaps explaining how GCs damage the hippocampus over the course of normal aging.     

Development and Application of Cloned DNA Probes for Clavibacter xyli subsp. xyli, the Causal Agent of Sugarcane Ratoon Stunting

Eco RI restriction fragments of genomic DNA from Clavibacter xyli subsp. xyli (CXX) were ligated with plasmid pUC18 and cloned in Escherichia coli JM109. The cloned DNA inserts from recombinant plasmids were Eco RI-excised and labeled with non-radioactive digoxigenin and used as probes. Ten specific DNA probes, RSD3, 15, 30, 31, 32, 35, 37, 41, 71, and 73 were selected for disease detection and pathogen differentiation. In the specificity tests, all of the 10 CXX DNA, probes differentiated Clavibacter xyli from other bacteria specifically. Seven out of the 10 CXX probes crossreacted with C. x. subsp. cynodontis (CXC) very weakly under moderate stringency wash conditions of hybridization. In the sensitivity tests, all of the 10 DNA probes detected the homologous DNA of CXX from 0.19 to 0.75 ng. To detect various cell numbers of CXX, the DNA probes detected 10⁴ to 10⁵ cells effectively. In Southern hybridizations, distinctly different band patterns were shown when the probes hybridized with DNA from CXX and CXC. Among these probes, RSD3, 15, 30, 31, 35, 37, and 71, efficiently detected CXX present in the sap collected from symptomless sugarcane.     

广西崇左县冲塘新石器时代人骨微量元素的初步研究

本文对广西崇左县冲塘新石器时代的３个个体（Ｍ０２,Ｓ０８,Ｓ０９）的肢骨进行了化学元素（Ｓｒ,Ｚｎ,Ｃａ,Ｐ,Ｃｄ,Ｐｈ）的含量测定．并根据研究结果对当时人类的生活环境、食物性质作了推测和分析．