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391.
Linkage disequilibrium between mutation and RFLP haplotype at the phenylalanine hydroxylase locus in the German population 总被引:17,自引:7,他引:10
Uta Lichter-Konecki Magdalena Schlotter David S. Konecki Sigfried Labeit Savio L. C. Woo Friedrich K. Trefz 《Human genetics》1988,78(4):347-352
Summary Restriction fragment length polymorphism (RFLP) haplotypes at the phenylalanine hydroxylase (PAH) locus have been determined in 60 German families with PAH deficiency. Similar to the Danish population, about 90% of the mutant alleles are confined to four distinct haplotypes. There are however, differences in the frequency distributiion of these haplotypes among the mutant alleles between the two populations. Using an oligonucleotide probe for the splicing mutation associated with mutant haplotype 3 in the Danish population, a tight association between the mutation and the RFLP haplotype has also been observed in Germany. The results provide strong evidence that the splicing mutation occurred on a haplotype 3 chromosome and that the mutant allele has spread into different populations smong Caucasians. 相似文献
392.
Charles D. Derby David N. Blaustein 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,163(6):777-794
1. | In order to understand the functional organization of the crustacean olfactory system, we are using intracellular recording and staining techniques to correlate the structure and function of single, odorant-sensitive interneurons in the brain of the crayfishProcambarus clarkii. We describe here the anatomy and physiology of interneurons that connect the brain with the medullae terminales or other eyestalk ganglia. |
2. | All of the interneurons in our study (Table 1, Figs. 3–15) are at least third-order olfactory neurons (second-order olfactory interneurons) because they respond to chemostimulation of the olfactory organ (the antennules) but do not branch in the olfactory lobe (the neuropil to which primary olfactory receptor cells of the antennules project). |
3. | Much of the central nervous system, including the three main divisions of the brain (protocerebrum, deuterocerebrum, tritocerebrum) (Fig. 1) and the medullae terminales (Fig. 2), are involved in integrating olfactory or multimodal (including olfactory) information, since these areas contain neurites of olfactory interneurons. Previous studies have indicated that regions involved in such processing include the olfactory lobes and accessory lobes of the deuterocerebrum, and regions I, II, IV, and VII (in some species) of the medullae terminales. Our results show that also prominent among regions involved in olfactory or multimodal (including olfactory) integration are the anterior and posterior optic neuropils of the protocerebrum (Figs. 3–11, 14, 15), the lateral and medial antennular neuropils of the deuterocerebrum (Figs. 3, 4, 7), the tegumentary neuropils (Figs. 3, 4, 8, 11) and the antennal neuropils (Figs. 3–5) of the tritocerebrum, and neuropils III, VI, XII of the medullae terminales (Figs. 12, 13). |
4. | These olfactory interneurons were sensitive to chemostimulation (unimodal), chemo- and mechanostimulation (bimodal), or chemo-, mechano-, and photostimulation (trimodal) (Table 1). Responses could be excitatory or inhibitory, even for a given neuron (Table 1). Morphologically complex interneurons (those having bilateral branching) were more likely to have complex response characteristics (trimodal sensitivity) (Figs. 8–12) than were morphologically simpler interneurons (those having unilateral branching) (Figs. 3–7, 14, 15). Olfactory interneurons with a soma in the medulla terminalis showed the most complex response profiles: they were trimodal, and were excited by odorants but were inhibited by touch and/or light (Figs. 12, 13). This finding suggests that these are complex, high order interneurons. |
5. | Our studies reveal that olfactory and other sensory information is transmitted between the brain and the medullae terminales (and possibly other eyestalk ganglia) by a coactivated, parallel array of structurally and functionally diverse neurons. |
393.
Relationship between the differential adsorption of odorants by the olfactory mucus and their perception in mixtures 总被引:1,自引:1,他引:0
It was proposed recently that the differential adsorption ofodorants by the olfactory mucus may constitute the first stepin the processing of odor mixtures [Laing, D.G. (1988) Ann.NY Acad. Sci., 510, 6166]. In the present study psychophysicalprocedures were used to determine if there was a relationshipbetween differential adsorption by the olfactory mucus and theperception of odorants of different polarity in binary mixtures.With the eight odor pairs studied, differential adsorption andthe polarity of an odorant were not predictors of how well anodorant would be perceived in a mixture or how it would suppressor enhance the perception of other odorants. 相似文献
394.
Geraldine E. Oliva George W. Rutherford Moses Grossman Janet Shalwitz Abigail English Frances Taylor David Werdegar 《The Western journal of medicine》1988,148(5):586-589
Although adolescents account for only 0.4% of reported cases of the acquired immunodeficiency syndrome (AIDS) in the United States, they are sexually active and, therefore, at risk of acquiring human immunodeficiency virus (HIV) infection. To address issues of HIV control in adolescents, we developed guidelines that emphasize education and medical care and deemphasize antibody testing. For adolescents known to be infected with HIV, we recommend no restrictions on access to educational or treatment programs except when their health providers recommend such restrictions to protect them from exposure to opportunistic infections. For adolescents of unknown antibody status with a possible previous exposure to HIV, we recommend that as long as the incidence of HIV infection and clinical AIDS remains low, there should be no restrictions on residential placements and no routine antibody testing. 相似文献
395.
David H. Sachs Chief Sharon Germana Mona El-Gamil Kenth Gustafsson Francois Hirsch Karen Pratt 《Immunogenetics》1988,28(1):22-29
Class II genes of miniature swine have been characterized by restriction fragment length polymorphism (RFLP) analysis and by analysis of a series of clones isolated from a lymphocyte genomic library. For RFLP analysis, DNA samples from three independent major histocompatibility complex homozygous lines and three intra-MHC recombinant lines were digested with a variety of restriction enzymes and analyzed in Southern blots using human cDNA probes for DP, DQ, DR, and DZ alpha genes, and DP, DQ, DR, and DO beta genes. One, or at most two, unique fragments were detected by hybridization with each of the human probes tested. In contrast, multiple bands (five to six for most enzymes examined) were detected by each of the human probes tested, the majority of which were found to cross-react with at least three of these probes under conditions of moderate stringency. Genomic DNA from the SLA
c
haplotype was cloned into an EMBL-3 bacteriophage vector, and the corresponding genomic library was screened with each of these human cDNA probes. The class II genes thereby isolated from this library showed characteristics consistent with those anticipated from the RFLP analysis. Thus, unique genes were obtained which showed no evidence of cross-hybridization, while genes showed extensive cross-hybridization and were frequently detected in the library by more than one human gene probe. These data are consistent with early evolutionary divergence of a genes, prior to mammalian speciation, and with continuing evolution of genes, with possible shared usage of these genes by different a loci. The data also imply that genes can readily be assigned to loci homologous to their human counterparts, but that genes will require further mapping and/or sequence analysis to confirm assignments. 相似文献
396.
Summary The optimal growth rate ofLipomyces
starkeyi, with dextran as sole carbon source, was found within the pH range 2.5–4.0, and temperature between 25–30°C. This yeast was unable to grow above 33°C. Dextranase production optima paralleled growth optima, except at pH 2.5. Decrease in enzyme yield at this pH could not be attributed to poor yeast growth or enzyme stability. 相似文献
397.
Crepidostomum wikgreni n. sp. is described from the gall-bladder and intestine of the whitefish Coregonus acronius in Lake Yli-Kitka in NE Finland. It is morphologically similar to Crepidostomum farionis, with which it occurs sympatrically and sometimes concurrently; but it differs in that the eggs are much larger, i.e. 96±6.5 m mean-length, as opposed to 71±4.7 m mean-length for C. farionis in the same host and locality.It is suggested that the new species has arisen from C. farionis after deglaciation and since c. 8,400 BP, at which time the waters of the Lake Kitka System were isolated from those in the rest of Finland and flowed eastwards into the White Sea Basin. The isolation of the White Sea Basin appears to have been maintained by watersheds running north-south close to the Fenno-Soviet border and east-west through central Karelia. It is further suggested that C. farionis currently occurring in Lake Yli-Kitka is a recent re-introduction brought about by the translocation of fish-stocks. 相似文献
398.
The carcinogenicity of several groups of carcinogens is evoked with particular reference to Dibenzo(c,g)carbazole derivatives. The activity of these derivatives is discussed with respect to their species and organ specificity. The enzymatic equipment is decisive as to whether the compounds formed can react with DNA or are simply detoxified and eliminated. All these carcinogens are complete carcinogens, i.e. they have the property of both initiation and promotion. 相似文献
399.
The cytochrome b-f complex is composed of four polypeptide subunits, three of which, cytochrome f, cytochrome b-563 and subunit IV, are encoded in chloroplast DNA and synthesised within the chloroplast, and the fourth, the Rieske FeS protein, is encoded in nuclear DNA and synthesised in the cytoplasm. The assembly of the cytochrome b-f complex therefore requires the interaction of subunits encoded by different genomes. A key role for the nuclear-encoded Rieske FeS protein in the assembly of the complex is suggested by a study of cytochrome b-f complex mutants. The assembly of individual subunits of the complex may be regulated by the availability of prosthetic groups. The genes for the chloroplast-encoded subunits and cDNA clones for the Rieske FeS protein have been isolated and characterised. Cytochrome f and the Rieske FeS protein are synthesised initially with N-terminal presequences required for their correct assembly within the chloroplast. The deduced amino acid sequences of the four subunits have been used to suggest models for the arrangement of the polypeptides in the thylakoid membrane. 相似文献
400.
In chloroplasts and a number of prokaryotes, -aminolevulinic acid (ALA), the universal precursor of porphyrins, is synthesized by a multistep enzymatic pathway with glutamyl-tRNAGlu as an intermediate. The ALA synthesizing system from barley chloroplasts is highly specific in its tRNA requirement for chloroplast tRNAGlu; a number of other Glu-tRNAs are inactive in ALA formation although they can be glutamylated by chloroplast aminoacyl-tRNA synthetases. In order to obtain more information about the structural features defining the ability of a tRNA to be recognized by the ALA synthesizing enzymes, we purified and sequenced two cytoplasmic tRNAGlu species from barley embryos which are inactive in ALA synthesis. By using glutamylated tRNAs as a substrate for the overall reaction, we showed that Glu-tRNA reductase is the enzyme responsible for tRNA discrimination. 相似文献